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Hypertension

Hypertension

Definition

Hypertension is high blood pressure. Blood pressure is the force of blood pushing against the walls of arteries. Arteries are the blood vessels that carry oxygenated blood from the heart to the body's tissues.

Description

As blood flows through arteries, it pushes against the inside of artery walls. The more pressure the blood exerts on the artery walls, the higher the blood pressure is. The size of arteries also affects the blood pressure. When the muscular walls of arteries are relaxed, or dilated, the pressure of the blood flowing through them is lower than when the artery walls narrow, or constricted.

Blood pressure is highest when the heart beats to push blood out into the arteries. When the heart relaxes to fill with blood again, the pressure is at its lowest point. Blood pressure when the heart beats is called systolic pressure. Blood pressure when the heart is at rest is called diastolic pressure. When blood pressure is measured, the systolic pressure is stated first and the diastolic pressure second. Blood pressure is measured in millimeters of mercury (mm Hg). For example, if a person's systolic pressure is 120 and diastolic pressure is 80, it is written as 120/80 mm Hg.

Blood pressure measurements

The National Heart, Lung, and Blood Institute in Bethesda, Maryland released clinical guidelines for blood pressure in 2003, lowering the standard normal readings for adults to less than 120 over less than 80.

Although there are set blood pressure ranges for adults, normal blood pressure ranges for children vary according to age, gender, and height so that different levels of growth are considered when evaluating blood pressure. In children, blood pressure normally rises during growth and maturation and varies greatly during adolescence .

Specific systolic and diastolic blood pressure percentiles have been established for each age, gender, and height group. In children ages six to 12, up to 125/80 mm Hg is considered normal. In youth ages 1215, 126/78 mm Hg is normal, and for ages 1618, 132/82 mm Hg is normal.

Children whose blood pressure is above the 95th percentile for their age/gender/height group are diagnosed with hypertension. Children whose blood pressure is between the 90th and 95th percentile are diagnosed with pre-hypertension. Adolescents whose blood pressure is greater than 120/80 also may be diagnosed with pre-hypertension.

Complications

Childhood hypertension is serious because it increases the risk of heart disease, stroke , and other medical problems in adulthood. Serious complications can be avoided by ensuring the child gets regular blood pressure checks and by treating hypertension as soon as it is diagnosed.

If left untreated, hypertension can lead to the following long-term complications:

  • atherosclerosis, also called arteriosclerosis
  • peripheral vascular disease
  • heart attack
  • stroke
  • enlarged heart and heart failure
  • kidney damage or kidney failure
  • retinopathy or blindness

Atherosclerosis is hardening of the arteries. The walls of arteries have a layer of muscle and elastic tissue that makes them flexible and able to dilate and constrict as blood flows through them. High blood pressure can make the artery walls thicken and harden. When artery walls thicken, the inside of the blood vessel narrows. Cholesterol and fats are more likely to build up on the walls of damaged arteries, making them even narrower. Blood clots also can get trapped in narrowed arteries, blocking the flow of blood. When atherosclerosis occurs in the blood vessels leading to the legs and feet, it is called peripheral vascular disease. Blood flow is decreased to the legs and feet with peripheral vascular diseases and can cause poor circulation in the legs, claudication, or aneurysm.

Arteries narrowed by atherosclerosis may not deliver enough blood to organs and other tissues. Reduced or blocked blood flow to the heart can cause a heart attack. If an artery to the brain is blocked, a stroke can result.

Hypertension makes the heart work harder to pump blood through the body. The extra workload can make the heart muscle thicken and stretch. When the heart becomes enlarged it cannot pump enough blood. If the hypertension is not treated, the heart may fail.

The kidneys remove the body's wastes from the blood. If hypertension thickens the arteries to the kidneys, less waste can be filtered from the blood. As the condition worsens, the kidneys fail and wastes build up in the blood. Dialysis or a kidney transplant is needed when the kidneys fail.

Hypertension can cause damage to blood vessels in the eyes, leading to retinopathy, or damage to the retina. Retinal damage becomes severe when blood pressure levels are high and remain elevated for a prolonged period of time.

Demographics

In the United States, an estimated 510 percent of children have hypertension, and one in four adults (about 50 million) have hypertension. About 30 percent of those with hypertension do not know they have it. Hypertension is more common in men than women and in people over age 65 than in younger persons. It also is more frequent and severe in African-American and Mexican-American adults and children than in white Americans. The prevalence of high blood pressure among African-Americans and whites in the southeastern United States is greater, and death rates from stroke are higher than among those in other regions.

In the early 2000s, high blood pressure in children and adolescents is on the rise. A 2003 report indicated this increase is most likely due to a greater number of overweight and obese children and adolescents. The U.S. Centers for Disease Control and Prevention studied the health and nutrition of Americans in the National Health and Nutrition Examination Surveys for more than 40 years, and the last data were collected in 2000. Researchers found a trend of high blood pressure in children ages eight to 17 years who were overweight or obese.

Causes and symptoms

Causes

Many different actions or situations can normally raise blood pressure. Physical activity and changes in position can temporarily raise blood pressure. Stressful situations can make blood pressure go up. When the stress goes away, blood pressure usually returns to normal. Certain medications also may change blood pressure, but usually blood pressure returns to normal when the drug is discontinued. These temporary increases in blood pressure are not considered hypertension. A diagnosis of hypertension is made only when a person has at least three separate high blood pressure readings performed one to several weeks apart.

Hypertension without a known cause is called primary or essential hypertension. Although the cause of hypertension is unknown in 9095 percent of adults, primary hypertension is uncommon in children, occurring in less than 12 percent of hypertensive children.

When a child has hypertension caused by another medical condition, it is called secondary hypertension. Secondary hypertension can be caused by a number of different illnesses. Kidney disease causes hypertension in 8085 percent of childhood cases. The kidneys regulate the balance of salt and water in the body. If the kidneys cannot rid the body of excess salt and water, blood pressure goes up. Kidney infections, a narrowing of the arteries that carry blood to the kidneys, called renal artery stenosis, and other kidney disorders can disturb the salt and water balance.

As body weight increases, blood pressure rises. Being overweight or obese is the strongest predictor of hypertension in young adults. Obesity has steadily increased in children and adolescents over the years. An estimated 16 percent of school-age children are over-weight. High blood pressure develops about 10 years after a young person becomes overweight. Obesity may cause other cardiovascular diseases if it is not managed or treated properly.

Risk factors

Risk factors are conditions that increase the chance of developing hypertension. Some of these risk factors can be changed to reduce the risk of developing hypertension or to lower blood pressure:

  • being overweight or obese
  • lack of physical activity
  • a diet high in fat, salt, and sugar
  • heredity
  • low birth weight and subsequent rapid weight gain
  • male sex
  • race
  • congenital conditions, such as coarctation of the aorta
  • diabetes
  • kidney disease
  • in adolescents, heavy alcohol consumption and use of oral contraceptives
  • in adults, being over the age of 60

Although smoking is not directly related to high blood pressure in children and adolescents, those who smoke should stop to reduce their risk of developing other health problems such as coronary artery disease.

Some risk factors for hypertension can be changed, while others cannot. Some children inherit a tendency to develop hypertension, and the risk increases if both parents are hypertensive. Children who have the risk factors above can work with their doctor and family to manage the controllable risk factors.

Symptoms

Hypertension generally does not cause symptoms. When symptoms occur, they are usually mild and non-specific. In young children (age three and younger), symptoms may include:

  • irritability
  • excessive crying
  • failure to gain weight
  • poor feeding
  • low-grade fever

In older children, symptoms may include:

  • dizziness
  • headaches
  • vomiting
  • heart palpitations

In severe and acute (sudden-onset) cases, hypertension can cause seizures, swelling throughout the body, blindness, or renal (kidney) failure. All of these symptoms require immediate medical attention and hospitalization .

When to call the doctor

If a child has any of the following symptoms, the parent or caregiver should call the child's doctor:

  • unexplained headache
  • sudden or gradual changes in vision
  • dizziness or light-headedness that does not resolve with rest
  • nausea associated with headache
  • unexplained or uncontrollable vomiting
  • heart palpitations

If a child has any of these symptoms, the parent or caregiver should immediately seek emergency medical attention:

  • severe headache
  • fainting
  • seizures or convulsions
  • swelling throughout the body
  • unexplained blurred vision or vision loss
  • severe chest pain or shortness of breath
  • unexplained sudden weakness

Diagnosis

Blood pressure in children should be checked regularly: at least at every doctor's visit after age three. Early detection and treatment of hypertension improve the child's overall health and decrease the risk of future health problems associated with hypertension.

Blood pressure is measured with an instrument called a sphygmomanometer. A cloth-covered rubber cuff is wrapped around the upper arm and inflated. When the cuff is inflated, an artery in the arm is squeezed to momentarily stop the flow of blood. Then, the air is let out of the cuff while a stethoscope placed over the artery is used to detect the sound of the blood spurting back through the artery. This first sound is the systolic pressure, the pressure when the heart beats. The last sound heard as the rest of the air is released is the diastolic pressure, the pressure between heartbeats. Both sounds are recorded on the mercury gauge on the sphygmomanometer.

The arm cuff used to measure blood pressure in children must be appropriate to the child's size, or the reading may be inaccurate.

A typical physical examination to evaluate hypertension includes:

  • medical and family history
  • physical examination
  • ophthalmoscopy: examination of the blood vessels in the eye
  • blood and urine tests

The physical exam may include several blood pressure readings at different times and in different positions. For at least five minutes before the blood pressure reading is taken, the child should be seated in a chair, with feet on the floor and arms supported at heart level. For best results, the child should not eat or drink caffeinated products within the 30 minutes prior to the exam. The physician uses a stethoscope to listen to sounds made by the heart and blood flowing through the arteries.

During the physical exam, the child's pulse, reflexes, and height and weight are checked and recorded. Internal organs are palpated to determine if they are enlarged.

Because hypertension can cause damage to the blood vessels in the eyes, the eyes may be checked with a instrument called an ophthalmoscope. The physician will look for thickening, narrowing, or hemorrhages in the blood vessels.

Urine and blood tests may be done to evaluate health and to detect the presence of certain substances that may indicate an underlying condition that is causing the hypertension.

Usually blood tests and urine tests, along with the physical examination and medical history, are enough to make the diagnosis of hypertension. If necessary, to rule out other medical conditions or to assess any damage from hypertension and/or its treatment, the following tests may be performed:

  • Chest x ray: To detect an enlarged heart, other vascular abnormalities, or lung disease.
  • Electrocardiogram (ECG): To measure the electrical activity of the heart. It can detect if the heart muscle is enlarged and if there is damage to the heart muscle from blocked arteries.
  • Echocardiogram (echo): To produce a graphic outline of the heart's movement, valves, and chambers, used to evaluate the function of the heart and valves. Echo is often combined with Doppler ultrasound and color Doppler. During the echo, an ultrasound transducer (hand-held wand placed on the skin of the chest) emits high-frequency sound waves to produce pictures of the heart's valves and chambers. An echo is used in pediatric patients diagnosed with hypertension to determine the extent of left ventricular hypertrophy, a condition in which the heart's main pumping vessel is enlarged.

Treatment

There is no cure for primary hypertension, but blood pressure can almost always be lowered with the correct treatment. The goal of treatment is to lower blood pressure to levels that will prevent heart disease and other complications of hypertension that could manifest in adulthood. In secondary hypertension, the disease that is responsible for the hypertension is treated in addition to the hypertension itself. Successful treatment of the underlying disorder may cure the secondary hypertension.

Clinicians should work with the child and the parents or caregivers to develop an individual treatment plan. Specific treatment goals vary. Treatment should be provided by a pediatric cardiologist or pediatrician with special knowledge and experience in the treatment of high blood pressure.

Lifestyle changes

Depending on the results of diagnostic tests, childhood hypertension is generally treated with lifestyle changes, including diet and exercise , before antihypertensive medication is prescribed. Lifestyle changes that may reduce blood pressure include:

  • losing weight
  • exercising regularly
  • reducing fat, salt, and sugar in the diet
  • managing stress and anxiety
  • quitting smoking and reducing alcohol consumption, as applicable in older children

Reaching and maintaining a healthy body weight is important. Overweight children with hypertension are recommended to lose weight until they are within 15 percent of their healthy body weight. Even a small amount of weight loss can make a major difference. Physical activities should be encouraged, and sedentary activities such as watching television or playing video games should be limited. The recommended exercise goal is aerobic activity, such as brisk walking, at least 30 minutes per day, most days of the week.

A pediatrician can calculate a healthy range of body weight for the child, recommend dietary guidelines, and provide activity guidelines to help the child safely and effectively lose weight. A consultation with a registered dietitian also may assist the parent or caregiver in implementing dietary changes.

Nutritional concerns

Dietary guidelines are individualized, based on the child's blood pressure levels and specific needs. In children older than two years of age, the following low-fat dietary guidelines are recommended:

  • Total fat intake should comprise 30 percent or less of total calories consumed per day.
  • Calories consumed as saturated fat should equal no more than 8 to 10 percent of total calories consumed per day.
  • Total cholesterol intake should be less than 300 mg/dl per day.

Elevated blood pressure can be reduced by an eating plan that emphasizes fruits, vegetables, and low-fat dairy foods, and which is low in saturated fat, total fat, and cholesterol. The DASH diet is recommended for patients with hypertension and includes whole grains, poultry, fish, and nuts. Fats, red meats, sodium, sweets, and sugar-sweetened beverages are limited. Sodium should also be reduced to no more than 1,500 milligrams per day.

A gradual transition to a heart-healthy diet can help decrease a child's risk of coronary artery disease and other health conditions in adulthood. Parents can replace foods high in fat with grains, vegetables, fruits, lean meat, and other foods low in fat and high in complex carbohydrates and protein. They can resist adding salt to foods while cooking and avoid highly processed foods that are usually high in sodium, such as fast foods, canned foods, boxed mixes, and frozen meals.

Alternative treatment

Alternative and complementary therapies include approaches that are considered to be outside the mainstream of traditional health care.

Techniques that induce relaxation and reduce stress, such as yoga , tai chi, meditation, guided imagery, and relaxation training, may be helpful in controlling blood pressure. Acupuncture and biofeedback training also may help induce relaxation. Before learning or practicing any particular technique, it is important for the parent/caregiver and child to learn about the therapy, its safety and effectiveness, potential side effects, and the expertise and qualifications of the practitioner. Although some practices are beneficial, others may be harmful to certain patients.

Dietary supplements, including garlic, fish oil (omega-3 fatty acids), L-arginine, soy, coenzyme Q10, phytosterols, and chelation therapy may be beneficial, but the exact nature of their effects on blood pressure is unknown. There is little scientific evidence that these therapies lower blood pressure or prevent the complications of high blood pressure, and most of these supplements have not been studied extensively in children and adolescents.

Vitamin E and beta carotene supplements were once thought to help prevent the development of heart disease, but subsequent studies disprove that assumption.

Medications

Medications usually are not prescribed for children as a first-line treatment for hypertension. Medications are prescribed, however, to treat hypertension when the child has significant high blood pressure or organ damage, or when diet and exercise are not adequately controlling the child's blood pressure.

Follow-up care

Follow-up care for hypertension includes home blood pressure monitoring. The parent or caregiver checks the child's blood pressure at different times of the day and records the readings. The doctor reviews this blood pressure record during the child's check-ups to evaluate the effectiveness of the child's treatment and to make any necessary adjustments.

Depending on the child's blood pressure levels and presence of other medical conditions such as diabetes, the doctor may recommend annual eye exams to detect the presence of vision changes and the development of retinopathy.

Prognosis

There is no cure for hypertension. However, it can be well controlled with the proper treatment. Therapy with a combination of lifestyle changes and sometimes antihypertensive medicines usually can manage blood pressure. For most children, early primary hypertension causes no immediate risk of serious health problems, but it does increase the risk for future organ damage. The key to avoiding serious complications of hypertension is to detect and treat it at the earliest possible age so that preventive treatment can be initiated.

Prevention

Avoiding or eliminating known risk factors helps reduce the risk of developing hypertension. Making the same changes recommended for treating hypertension can reduce a child's risk of developing hypertension:

  • losing weight if overweight or obese
  • exercising regularly
  • reducing salt, fat, and sugar in the diet
  • reducing fat intake
  • managing stress and anxiety
  • quitting smoking and limiting alcohol, as applicable in older children

Parental concerns

Parents should reinforce with the child that hypertension is a serious condition that can cause more health problems later in life. Parents should work with their child to make dietary changes and increase their activity level to manage hypertension and prevent it from getting worse. Everyone can benefit when a heart-healthy lifestyle is followed, so the dietary and activity changes made for the hypertensive child will benefit the entire family.

Resources

BOOKS

McGoon, Michael D., and Bernard J. Gersh, eds. Mayo Clinic Heart Book: The Ultimate Guide to Heart Health, 2nd ed. New York: William Morrow and Co., Inc., 2000.

Moore, Thomas, et al. The Dash Diet for Hypertension: Lower Your Blood Pressure in Fourteen Days without Drugs. New York: Simon & Schuster, Inc., 2001.

Topol, Eric J. Cleveland Clinic Heart Book: The Definitive Guide for the Entire Family from the Nation's Leading Heart Center. New York: Hyperion, 2000.

Trout, Darrell, and Ellen Welch. Surviving with Heart: Taking Charge of Your Heart Care. Golden, CO: Fulcrum Publishing, 2002.

PERIODICALS

McNamara, Damian. "Obesity Behind Rise in Incidence of Primary Hypertension." Family Practice News (April 1, 2003): 4551.

. "Trial Shows Efficacy of Lifestyle Changes for Blood Pressure: More Intensive than Typical Office Visit." Family Practice News (July 1, 2003): 12.

"New Blood Pressure Guidelines Establish Diagnosis of Prehypertension: Level Seeks to Identify At-risk Individuals Early." Case Management Advisor (July 2003): S1.

Sorof, Jonathan M., et al. "Cardiovascular risk factors and sequelae in hypertensive children identified by referral versus school-based screening." Hypertension 43 (2004): 214.

KEY TERMS

Aneurysm A weakened area in the wall of a blood vessel which causes an outpouching or bulge. Aneurysms may be fatal if these weak areas burst, resulting in uncontrollable bleeding.

Aorta The main artery located above the heart that pumps oxygenated blood out into the body. The aorta is the largest artery in the body.

Arteriosclerosis A chronic condition characterized by thickening, loss of leasticity, and hardening of the arteries and the build-up of plaque on the arterial walls. Arteriosclerosis can slow or impair blood circulation. It includes atherosclerosis, but the two terms are often used synonymously.

Artery A blood vessel that carries blood away from the heart to the cells, tissues, and organs of the body.

Atrial Referring to the upper chambers of the heart.

Claudication Cramping or pain in a leg caused by poor blood circulation. This condition is frequently caused by hardening of the arteries (atherosclerosis). Intermittent claudication occurs only at certain times, usually after exercise, and is relieved by rest.

Coarctation of the aorta A congenital defect in which severe narrowing or constriction of the aorta obstructs the flow of blood.

Dialysis A process of filtering and removing waste products from the bloodstream, it is used as a treatment for patients whose kidneys do not function properly. Two main types are hemodialysis and peritoneal dialysis. In hemodialysis, the blood flows out of the body into a machine that filters out the waste products and routes the cleansed blood back into the body. In peritoneal dialysis, the cleansing occurs inside the body. Dialysis fluid is injected into the peritoneal cavity and wastes are filtered through the peritoneum, the thin membrane that surrounds the abdominal organs.

Diastolic blood pressure Diastole is the period in which the left ventricle relaxes so it can refill with blood; diastolic pressure is therefore measured during diastole.

Heart attack Damage that occurs to the heart when one of the coronary arteries becomes narrowed or blocked.

Obesity An abnormal accumulation of body fat, usually 20% or more over an individual's ideal body weight.

Overweight Being 25 to 29 percent over the recommended healthy body weight for a specific age and height, as established by calculating body mass index.

Retinopathy Any disorder of the retina.

Sphygmomanometer An instrument used to measure blood pressure.

Stroke Interruption of blood flow to a part of the brain with consequent brain damage. A stroke may be caused by a blood clot or by hemorrhage due to a burst blood vessel. Also known as a cerebrovascular accident.

Systolic blood pressure Blood pressure when the heart contracts (beats).

Ventricles The lower pumping chambers of the heart. The ventricles push blood to the lungs and the rest of the body.

ORGANIZATIONS

American College of Cardiology. Heart House, 9111 Old Georgetown Rd., Bethesda, MD 208141699. Web site: <www.acc.org>.

American Heart Association. 7320 Greenville Ave., Dallas, TX 75231. Web site: <www.americanheart.org>.

American Society of Hypertension. 148 Madison Ave., 5th Floor, New York, NY 10016. Web site: <www.ash-us.org>.

The Cleveland Clinic Heart Center. The Cleveland Clinic Foundation, 9500 Euclid Ave., F25, Cleveland, OH 44195. Web site: <www.clevelandclinic.org/heartcenter>.

Toni Rizzo Teresa G. Odle Angela M. Costello

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Hypertension

Hypertension

Definition

Hypertension is the medical term for high blood pressure. Blood pressure is the force of blood pushing against the walls of arteries as it flows through them. Arteries are the blood vessels that carry oxygenated blood from the heart to the body's tissues.

Description

As blood flows through arteries, it pushes against the inside of the artery walls. The more pressure the blood exerts on the artery walls, the higher the blood pressure. The size of small arteries also affects the blood pressure. When the muscular walls of arteries are relaxed, or dilated, the pressure of the blood flowing through them is lower than when the artery walls are narrow, or constricted.

Blood pressure is highest when the heart beats to pump blood out into the arteries. When the heart relaxes to fill with blood again, the pressure is at its lowest point. Blood pressure when the heart beats is called systolic pressure. Blood pressure when the heart is at rest is called diastolic pressure. When blood pressure is measured, the systolic pressure is stated first and the diastolic pressure second. Blood pressure is measured in millimeters of mercury (mm Hg). For example, if a person's systolic pressure is 120 and diastolic pressure is 80, it is written as 120/80 mm Hg. The American Heart Association considers blood pressure above 140 over 90 high for adults.

Hypertension is a major health problem, especially because it has no symptoms. Many people have hypertension without knowing it. In the United States, about 50 million people age sixty and older have high blood pressure. Hypertension is more common in men than women and in people over the age of 65 than in younger persons. More than half of all Americans over the age of 65 have hypertension. It is also more common in African-Americans than in white Americans.

Hypertension is serious because people with the condition have a higher risk for heart disease and other medical problems than people with normal blood pressure. Serious complications can be avoided by getting regular blood pressure checks and treating hypertension as soon as it is diagnosed.

If left untreated, hypertension can lead to the following medical conditions:

  • arteriosclerosis, also called atherosclerosis
  • blindness
  • heart attack
  • stroke
  • enlarged heart
  • kidney damage

Arteriosclerosis is hardening of the arteries. The walls of arteries have a layer of muscle and elastic tissue that makes them flexible and able to dilate and constrict as blood flows through them. High blood pressure can make the artery walls thicken and harden. When artery walls thicken, the inside of the blood vessel narrows. Cholesterol and fats are more likely to build up on the walls of damaged arteries, making them even narrower. Blood clots can also get trapped in narrowed arteries, blocking the flow of blood.

Arteries narrowed by arteriosclerosis may not deliver enough blood to organs and other tissues. Reduced or blocked blood flow to the heart can cause a heart attack. If an artery to the brain is blocked, a stroke can result.

Hypertension makes the heart work harder to pump blood through the body. The extra workload can make the heart muscle thicken and stretch. When the heart becomes too enlarged it cannot pump enough blood. If the hypertension is not treated, the heart may fail.

The kidneys remove the body's wastes from the blood. If hypertension thickens the arteries to the kidneys, less waste can be filtered from the blood. As the condition worsens, the kidneys fail and wastes build up in the blood. Dialysis or a kidney transplant are needed when the kidneys fail. About 25% of people who receive kidney dialysis have kidney failure caused by hypertension.

Causes & symptoms

Many different actions or situations can normally raise blood pressure. Physical activity can temporarily raise blood pressure. Stressful situations can make blood pressure go up. When the stress goes away, blood pressure usually returns to normal. These temporary increases in blood pressure are not considered hypertension. A diagnosis of hypertension is made only when a person has multiple high blood pressure readings over a period of time.

The cause of hypertension is not known in 9095% of the people who have it. Hypertension without a known cause is called primary or essential hypertension. When a person has hypertension caused by another medical condition, it is called secondary hypertension. Secondary hypertension can be caused by a number of different illnesses. Many people with kidney disorders have secondary hypertension. The kidneys regulate the balance of salt and water in the body. If the kidneys cannot rid the body of excess salt and water, blood pressure goes up. Kidney infections , a narrowing of the arteries that carry blood to the kidneys, called renal artery stenosis, and other kidney disorders can disturb the salt and water balance.

Cushing's syndrome and tumors of the pituitary and adrenal glands often increase levels of the adrenal gland hormones cortisol, adrenalin, and aldosterone, which can cause hypertension. Other conditions that can cause hypertension are blood vessel diseases, thyroid gland disorders, some prescribed drugs, alcoholism , and pregnancy .

Even though the cause of most hypertension is not known, some people have risk factors that give them a greater chance of getting hypertension. Many of these risk factors can be changed to lower the chance of developing hypertension or as part of a treatment program to lower blood pressure.

Risk factors for hypertension include:

  • age over 60
  • male sex
  • race (The African-American community has a higher incidence of hypertension.)
  • heredity
  • salt sensitivity
  • obesity
  • inactive lifestyle
  • heavy alcohol consumption
  • use of oral contraceptives

Some risk factors for hypertension can be changed, while others cannot. Age, male sex, and race are risk factors that a person cannot deter. Some people inherit a tendency to get hypertension. People with family members who have hypertension are more likely to develop it than those whose relatives are not hypertensive. People with these risk factors can avoid or eliminate the other risk factors to lower their chance of developing hypertension.

Diagnosis

Because hypertension does not cause symptoms, it is important to have blood pressure checked regularly. Blood pressure is measured with an instrument called a sphygmomanometer. A cloth-covered rubber cuff is wrapped around the upper arm and inflated. When the cuff is inflated, an artery in the arm is squeezed to momentarily stop the flow of blood. Then, the air is let out of the cuff while a stethoscope placed over the artery is used to detect the sound of the blood spurting back through the artery. This first sound is the systolic pressure, the pressure when the heart beats. The last sound heard as the rest of the air is released is the diastolic pressure, the pressure between heartbeats. Both sounds are recorded on the mercury gauge on the sphygmomanometer.

A number of such factors as pain , stress, or anxiety can cause a temporary increase in blood pressure. For this reason, hypertension is not diagnosed on the basis of only one high blood pressure reading. If a blood pressure reading is 140/90 or higher for the first time, the physician will have the person return for another blood pressure check. Diagnosis of hypertension usually is made based on two or more readings after the first visit. Sometimes, patients have high blood pressure only while in the doctor's office. This phenomenon, called "white-coat hypertension" has usually been dismissed as mere anxiety over visiting the doctor. In late 2001, an Italian study questioned dismissal of these patients as not being hypertensive and encouraged further study.

Systolic hypertension of the elderly is common and is diagnosed when the diastolic pressure is normal or low, but the systolic is elevated, e.g. 170/70 mm Hg. This condition usually coexists with hardening of the arteries (atherosclerosis).

Blood pressure measurements are classified in stages according to severity:

  • normal blood pressure: lower than 130/85 mm Hg
  • high normal: 130139/8589 mm Hg
  • mild hypertension: 140159/9099 mm Hg
  • moderate hypertension: 160179/100109 mm Hg
  • severe hypertension: 180209/110119
  • very severe hypertension: 210/120 or higher

A typical physical examination to evaluate hypertension includes:

  • medical and family history
  • physical examination
  • ophthalmoscopy: examination of the blood vessels in the eye
  • chest x ray
  • electrocardiograph (ECG)
  • blood and urine tests

The medical and family history help the physician determine if the patient has any conditions or disorders that might contribute to or cause the hypertension. A family history of hypertension might suggest a genetic predisposition to the disorder.

The physical exam may include several blood pressure readings at different times and in different positions. The physician uses a stethoscope to listen to sounds made by the heart and blood flowing through the arteries. The pulse, reflexes, height, and weight are checked and recorded. Internal organs are palpated, or felt, to determine if they are enlarged.

Because hypertension can cause damage to the blood vessels in the eyes, the eyes may be checked with an instrument called an ophthalmoscope. The physician will look for thickening, narrowing, or hemorrhages in the blood vessels.

A chest x ray can detect an enlarged heart, other heart abnormalities, or lung disease.

An electrocardiogram (ECG) measures the electrical activity of the heart. It can detect if the heart muscle is enlarged and if there is damage to the heart muscle from blocked arteries.

Urine and blood tests may be done to further evaluate health and to detect the presence of disorders that might cause hypertension.

Treatment

There is no cure for primary hypertension, but blood pressure can almost always be lowered with the correct treatment. The goal of treatment is to lower blood pressure to levels that will prevent heart disease and other complications of hypertension. In secondary hypertension, the disease that is responsible for the hypertension is treated in addition to the hypertension itself. Successful treatment of the underlying disorder may cure the secondary hypertension.

Treatment to lower blood pressure usually includes changes in diet and getting regular exercise . Patients with mild or moderate hypertension who do not have damage to the heart or kidneys may first be treated primarily with lifestyle changes.

Lifestyle changes that may reduce blood pressure by about 510 mm Hg include:

  • reducing salt intake
  • reducing fat intake
  • losing weight
  • getting regular exercise
  • quitting smoking
  • reducing alcohol consumption
  • managing stress

Natural remedies approved by a physician may also lower or even prevent hypertension. Aromatherapy as a treatment option uses essential oils either inhaled from a bottle in times of anxiety or massaged daily into the skin at bedtime in the area beneath the collarbone. Blue chamomile and lavender are known for their stress relief and relaxation effects.

Food therapy has also been shown to affect blood pressure. Muscles that regulate blood pressure have been noted to dilate with the intake of celery; celery juice has also been found to have a mild diuretic effect. Eating fresh fruits and vegetables, which are high in potassium and magnesium , lowers systemic sodium and fluid levels in the circulatory system. A 2001 study showed that reducing intake of sodium decreases blood pressure in participants with or without hypertension. Garlic intake has also been linked with lowering blood pressures. Taken either via enteric-coated capsules or fresh garlic cloves, allicin is thought to be the ingredient that brings down the blood pressure.

Relaxation and meditation can help lower blood pressure. Focusing on relaxing music can also slow the heart rate and lower blood pressure, as can imagery (envisioning coolness seeping into the pores and throughout the body, sensing that blood pressure is within normal range). Yoga experts cite two specific poses, the corpse pose and the knee squeeze, when used in combination with breathing exercises, as being particularly helpful in relieving tension and improving blood flow.

Allopathic treatment

Patients whose blood pressure remains higher than 139/90 will most likely be advised to take antihypertensive medication. Numerous drugs have been developed to treat hypertension. The choice of medication will depend on the stage of hypertension, side effects, other medical conditions the patient may have, and other medicines the patient is taking.

Patients with mild or moderate hypertension are initially treated with monotherapy, a single antihypertensive medicine. If treatment with a single medicine fails to lower blood pressure sufficiently, a different medicine may be tried or another medicine may be added to the first. Patients with more severe hypertension may initially be given a combination of medicines to control their hypertension. Combining antihypertensive medicines with different types of action often controls blood pressure with smaller doses of each drug than would be needed for monotherapy.

Antihypertensive medicines fall into several classes:

  • diuretics
  • beta-blockers
  • calcium channel blockers
  • angiotensin-converting enzyme inhibitors (ACE inhibitors)
  • alpha-blockers
  • alpha-beta blockers
  • vasodilators
  • peripheral-acting adrenergic antagonists
  • centrally-acting agonists

Diuretics help the kidneys eliminate excess salt and water from the body's tissues and the blood. This helps reduce the swelling caused by fluid buildup in the tissues. The reduction of fluid dilates the walls of arteries and lowers blood pressure.

Beta-blockers lower blood pressure by acting on the nervous system to slow the heart rate and reduce the force of the heart's contraction. They are used with caution in patients with heart failure, asthma , diabetes, or circulation problems in the hands and feet.

Calcium channel blockers block the entry of calcium into muscle cells in artery walls. Muscle cells need calcium to constrict, so reducing their calcium keeps them more relaxed and lowers blood pressure.

ACE inhibitors block the production of substances that constrict blood vessels. They also help reduce the buildup of water and salt in the tissues. They are often given to patients with heart failure, kidney disease, or diabetes. ACE inhibitors may be used together with diuretics.

Alpha-blockers act on the nervous system to dilate arteries and reduce the force of the heart's contractions.

Alpha-beta blockers combine the actions of alpha and beta blockers.

Vasodilators act directly on arteries to relax their walls so blood can move more easily through them. They lower blood pressure rapidly and are injected in hypertensive emergencies when patients have dangerously high blood pressure.

Peripheral-acting adrenergic antagonists act on the nervous system to relax arteries and reduce the force of the heart's contractions. They usually are prescribed together with a diuretic. Peripheral acting adrenergic antagonists can cause slowed mental function and lethargy.

Centrally-acting agonists also act on the nervous system to relax arteries and slow the heart rate. They are usually used with other antihypertensive medicines.

In 2001, a medical device company announced findings about the effectiveness of a breathing device to work along with antihypertensive medications. By helping patients alter breathing patterns to lengthen the phase in which they exhale, they could slow breathing and see beneficial effects on blood pressure accumulate. The device is available through prescription only, but is pending over-the-counter-clearance from the Food and Drug Administration (FDA.)

Expected results

There is no cure for hypertension. However, it can be well controlled with the proper treatment. The key to avoiding serious complications of hypertension is to detect and treat it before damage occurs. Because antihypertensive medicines control blood pressure, but do not cure it, patients must continue taking the medications to maintain reduced blood pressure levels and avoid complications.

Prevention

Prevention of hypertension centers on avoiding or eliminating known risk factors. Even persons at risk because of age, race, or sex or those who have an inherited risk can lower their chance of developing hypertension.

The risk of developing hypertension can be reduced by making the same lifestyle changes recommended for treating hypertension.

Resources

BOOK

Bellenir, Karen, and Peter D. Dresser, eds. Cardiovascular Diseases and Disorders Sourcebook. Detroit: Omnigraphics, 1995.

Texas Heart Institute. Heart Owner's Handbook. New York: John Wiley and Sons, 1996.

PERIODICALS

Boschart, Sherry. "Guided Breathing Exercise May Help Cut Hypertension (Preliminary Trial Results)." Internal Medicine News 34, no. 21 (November 1, 2001): 3031.

"Study Suggests White-Coat Hypertension is Not Harmless." Medical Devices and Surgical Technology Week (December 23, 2001): 26.

Vollmer, William M., et al. "Effects of Diet and Sodium Intake on Blood Pressure: Subgroup Analysis of the DASH-Sodium Trail." Annals of Internal Medicine 135, no. 12 (December 18, 2001): 10191020.

ORGANIZATION

American Heart Association. 7272 Greenview Avenue, Dallas, TX 75231-4596. (800) AHS-USA1. <http://www.amhrt.org>.

National Heart, Lung, and Blood Institute. Information Center. PO Box 30105, Bethesda, MD 20824-0105. (301) 251-1222.

Texas Heart Institute. Heart Information Service, PO Box 20345, Houston, TX 77225-0345. (800) 292-2221.

Kathleen Wright

Teresa G. Odle

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Hypertension

Hypertension

Definition

Hypertension is high blood pressure. Blood pressure is the force of blood pushing against the walls of arteries as it flows through them. Arteries are the blood vessels that carry oxygenated blood from the heart to the body's tissues.

Description

As blood flows through arteries it pushes against the inside of the artery walls. The more pressure the blood exerts on the artery walls, the higher the blood pressure will be. The size of small arteries also affects the blood pressure. When the muscular walls of arteries are relaxed, or dilated, the pressure of the blood flowing through them is lower than when the artery walls narrow, or constrict.

Blood pressure is highest when the heart beats to push blood out into the arteries. When the heart relaxes to fill with blood again, the pressure is at its lowest point. Blood pressure when the heart beats is called systolic pressure. Blood pressure when the heart is at rest is called diastolic pressure. When blood pressure is measured, the systolic pressure is stated first and the diastolic pressure second. Blood pressure is measured in millimeters of mercury (mm Hg). For example, if a person's systolic pressure is 120 and diastolic pressure is 80, it is written as 120/80 mm Hg. The American Heart Association has long considred blood pressure less than 140 over 90 normal for adults. However, the National Heart, Lung, and Blood Institute in Bethesda, Maryland released new clinical guidelines for blood pressure in 2003, lowering the standard normal readings. A normal reading was lowered to less than 120 over less than 80.

Hypertension is a major health problem, especially because it has no symptoms. Many people have hypertension without knowing it. In the United States, about 50 million people age six and older have high blood pressure. Hypertension is more common in men than women and in people over the age of 65 than in younger persons. More than half of all Americans over the age of 65 have hypertension. It also is more common in African-Americans than in white Americans.

Hypertension is serious because people with the condition have a higher risk for heart disease and other medical problems than people with normal blood pressure. Serious complications can be avoided by getting regular blood pressure checks and treating hypertension as soon as it is diagnosed.

If left untreated, hypertension can lead to the following medical conditions:

  • arteriosclerosis, also called atherosclerosis
  • heart attack
  • stroke
  • enlarged heart
  • kidney damage.

Arteriosclerosis is hardening of the arteries. The walls of arteries have a layer of muscle and elastic tissue that makes them flexible and able to dilate and constrict as blood flows through them. High blood pressure can make the artery walls thicken and harden. When artery walls thicken, the inside of the blood vessel narrows. Cholesterol and fats are more likely to build up on the walls of damaged arteries, making them even narrower. Blood clots also can get trapped in narrowed arteries, blocking the flow of blood.

Arteries narrowed by arteriosclerosis may not deliver enough blood to organs and other tissues. Reduced or blocked blood flow to the heart can cause a heart attack. If an artery to the brain is blocked, a stroke can result.

Hypertension makes the heart work harder to pump blood through the body. The extra workload can make the heart muscle thicken and stretch. When the heart becomes too enlarged it cannot pump enough blood. If the hypertension is not treated, the heart may fail.

The kidneys remove the body's wastes from the blood. If hypertension thickens the arteries to the kidneys, less waste can be filtered from the blood. As the condition worsens, the kidneys fail and wastes build up in the blood. Dialysis or a kidney transplant are needed when the kidneys fail. About 25% of people who receive kidney dialysis have kidney failure caused by hypertension.

Causes and symptoms

Many different actions or situations can normally raise blood pressure. Physical activity can temporarily raise blood pressure. Stressful situations can make blood pressure go up. When the stress goes away, blood pressure usually returns to normal. These temporary increases in blood pressure are not considered hypertension. A diagnosis of hypertension is made only when a person has multiple high blood pressure readings over a period of time.

The cause of hypertension is not known in 90 to 95 percent of the people who have it. Hypertension without a known cause is called primary or essential hypertension.

When a person has hypertension caused by another medical condition, it is called secondary hypertension. Secondary hypertension can be caused by a number of different illnesses. Many people with kidney disorders have secondary hypertension. The kidneys regulate the balance of salt and water in the body. If the kidneys cannot rid the body of excess salt and water, blood pressure goes up. Kidney infections, a narrowing of the arteries that carry blood to the kidneys, called renal artery stenosis, and other kidney disorders can disturb the salt and water balance.

Cushing's syndrome and tumors of the pituitary and adrenal glands often increase levels of the adrenal gland hormones cortisol, adrenalin, and aldosterone, which can cause hypertension. Other conditions that can cause hypertension are blood vessel diseases, thyroid gland disorders, some prescribed drugs, alcoholism, and pregnancy.

Even though the cause of most hypertension is not known, some people have risk factors that give them a greater chance of getting hypertension. Many of these risk factors can be changed to lower the chance of developing hypertension or as part of a treatment program to lower blood pressure.

Risk factors for hypertension include:

  • age over 60
  • male sex
  • race
  • heredity
  • salt sensitivity
  • obesity
  • inactive lifestyle
  • heavy alcohol consumption
  • use of oral contraceptives

Some risk factors for getting hypertension can be changed, while others cannot. Age, male sex, and race are risk factors that a person can't do anything about. Some people inherit a tendency to get hypertension. People with family members who have hypertension are more likely to develop it than those whose relatives are not hypertensive. People with these risk factors can avoid or eliminate the other risk factors to lower their chance of developing hypertension. A 2003 report found that the rise in incidence of high blood pressure among children is most likely due to an increase in the number of overweight and obese children and adolescents.

Diagnosis

Because hypertension doesn't cause symptoms, it is important to have blood pressure checked regularly. Blood pressure is measured with an instrument called a sphygmomanometer. A cloth-covered rubber cuff is wrapped around the upper arm and inflated. When the cuff is inflated, an artery in the arm is squeezed to momentarily stop the flow of blood. Then, the air is let out of the cuff while a stethoscope placed over the artery is used to detect the sound of the blood spurting back through the artery. This first sound is the systolic pressure, the pressure when the heart beats. The last sound heard as the rest of the air is released is the diastolic pressure, the pressure between heart beats. Both sounds are recorded on the mercury gauge on the sphygmomanometer.

Normal blood pressure is defined by a range of values. Blood pressure lower than 120/80 mm Hg is considered normal. A number of factors such as pain, stress or anxiety can cause a temporary increase in blood pressure. For this reason, hypertension is not diagnosed on one high blood pressure reading. If a blood pressure reading is 120/80 or higher for the first time, the physician will have the person return for another blood pressure check. Diagnosis of hypertension usually is made based on two or more readings after the first visit.

Systolic hypertension of the elderly is common and is diagnosed when the diastolic pressure is normal or low, but the systolic is elevated, e.g.170/70 mm Hg. This condition usually co-exists with hardening of the arteries (atherosclerosis).

Blood pressure measurements are classified in stages, according to severity:

  • normal blood pressure: less than less than 120/80 mm Hg
  • pre-hypertension: 120-129/80-89 mm Hg
  • Stage 1 hypertension: 140-159/90-99 mm Hg
  • Stage 2 hypertension: at or greater than 160-179/100-109 mm Hg

A typical physical examination to evaluate hypertension includes:

  • medical and family history
  • physical examination
  • ophthalmoscopy: Examination of the blood vessels in the eye
  • chest x ray
  • electrocardiograph (ECG)
  • blood and urine tests.

The medical and family history help the physician determine if the patient has any conditions or disorders that might contribute to or cause the hypertension. A family history of hypertension might suggest a genetic predisposition for hypertension.

The physical exam may include several blood pressure readings at different times and in different positions. The physician uses a stethoscope to listen to sounds made by the heart and blood flowing through the arteries. The pulse, reflexes, and height and weight are checked and recorded. Internal organs are palpated, or felt, to determine if they are enlarged.

Because hypertension can cause damage to the blood vessels in the eyes, the eyes may be checked with a instrument called an ophthalmoscope. The physician will look for thickening, narrowing, or hemorrhages in the blood vessels.

A chest x ray can detect an enlarged heart, other vascular (heart) abnormalities, or lung disease.

An electrocardiogram (ECG) measures the electrical activity of the heart. It can detect if the heart muscle is enlarged and if there is damage to the heart muscle from blocked arteries.

Urine and blood tests may be done to evaluate health and to detect the presence of disorders that might cause hypertension.

Treatment

There is no cure for primary hypertension, but blood pressure can almost always be lowered with the correct treatment. The goal of treatment is to lower blood pressure to levels that will prevent heart disease and other complications of hypertension. In secondary hypertension, the disease that is responsible for the hypertension is treated in addition to the hypertension itself. Successful treatment of the underlying disorder may cure the secondary hypertension.

Guidelines advise that clinicians work with patients to agree on blood pressure goals and develop a treatment plan for the individual patient. Actual combinations of medications and lifestyle changes will vary from one person to the next. Treatment to lower blood pressure may include changes in diet, getting regular exercise, and taking antihypertensive medications. Patients falling into the pre-hypertension range who don't have damage to the heart or kidneys often are advised to make needed lifestyle changes only. A 2003 report of a clinical trial showed that adults with elevated blood pressures lowered them as mush as 38% by making lifestyle changes and participating in the DASH diet, which encourages eating more fruit and vegetables.

Lifestyle changes that may reduce blood pressure by about 5 to 10 mm Hg include:

  • reducing salt intake
  • reducing fat intake
  • losing weight
  • getting regular exercise
  • quitting smoking
  • reducing alcohol consumption
  • managing stress

Patients whose blood pressure falls into the Stage 1 hypertension range may be advised to take antihypertensive medication. Numerous drugs have been developed to treat hypertension. The choice of medication will depend on the stage of hypertension, side effects, other medical conditions the patient may have, and other medicines the patient is taking.

If treatment with a single medicine fails to lower blood pressure enough, a different medicine may be tried or another medicine may be added to the first. Patients with more severe hypertension may initially be given a combination of medicines to control their hypertension. Combining antihypertensive medicines with different types of action often controls blood pressure with smaller doses of each drug than would be needed for just one.

Antihypertensive medicines fall into several classes of drugs:

  • diuretics
  • beta-blockers
  • calcium channel blockers
  • angiotensin converting enzyme inhibitors (ACE inhibitors)
  • alpha-blockers
  • alpha-beta blockers
  • vasodilators
  • peripheral acting adrenergic antagonists
  • centrally acting agonists

Diuretics help the kidneys eliminate excess salt and water from the body's tissues and the blood. This helps reduce the swelling caused by fluid buildup in the tissues. The reduction of fluid dilates the walls of arteries and lowers blood pressure. New guidelines released in 2003 suggest diuretics as the first drug of choice for most patients with high blood pressure and as part of any multi-drug combination.

Beta-blockers lower blood pressure by acting on the nervous system to slow the heart rate and reduce the force of the heart's contraction. They are used with caution in patients with heart failure, asthma, diabetes, or circulation problems in the hands and feet.

Calcium channel blockers block the entry of calcium into muscle cells in artery walls. Muscle cells need calcium to constrict, so reducing their calcium keeps them more relaxed and lowers blood pressure.

ACE inhibitors block the production of substances that constrict blood vessels. They also help reduce the build-up of water and salt in the tissues. They often are given to patients with heart failure, kidney disease, or diabetes. ACE inhibitors may be used together with diuretics.

Alpha-blockers act on the nervous system to dilate arteries and reduce the force of the heart's contractions.

Alpha-beta blockers combine the actions of alpha and beta blockers.

Vasodilators act directly on arteries to relax their walls so blood can move more easily through them. They lower blood pressure rapidly and are injected in hypertensive emergencies when patients have dangerously high blood pressure.

Peripheral acting adrenergic antagonists act on the nervous system to relax arteries and reduce the force of the heart's contractions. They usually are prescribed together with a diuretic. Peripheral acting adrenergic antagonists can cause slowed mental function and lethargy.

Centrally acting agonists also act on the nervous system to relax arteries and slow the heart rate. They are usually used with other antihypertensive medicines.

Prognosis

There is no cure for hypertension. However, it can be well controlled with the proper treatment. Therapy with a combination of lifestyle changes and antihypertensive medicines usually can keep blood pressure at levels that will not cause damage to the heart or other organs. The key to avoiding serious complications of hypertension is to detect and treat it before damage occurs. Because antihypertensive medicines control blood pressure, but do not cure it, patients must continue taking the medications to maintain reduced blood pressure levels and avoid complications.

Prevention

Prevention of hypertension centers on avoiding or eliminating known risk factors. Even persons at risk because of age, race, or sex or those who have an inherited risk can lower their chance of developing hypertension.

The risk of developing hypertension can be reduced by making the same changes recommended for treating hypertension:

  • reducing salt intake
  • reducing fat intake
  • losing weight
  • getting regular exercise
  • quitting smoking
  • reducing alcohol consumption
  • managing stress

Resources

PERIODICALS

McNamara, Damian. "Obesity Behind Rise in Incidence of Primary Hypertension." Family Practice News April 1, 2003: 45-51.

McNamara, Damian. "Trial Shows Efficacy of Lifestyle Changes for BP: More Intensive Than Typical Office Visit." Family Practice News July 1, 2003: 1-2.

"New BP Guidelines Establish Diagnosis of Pre-hypertension: Level Seeks to Identify At-risk Individuals Early." Case Management Advisor July 2003: S1.

"New Hypertension Guidelines: JNC-7." Clinical Cardiology Alert July 2003: 54-63.

ORGANIZATIONS

American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. http://www.americanheart.org.

National Heart, Lung and Blood Institute. PO Box 30105, Bethesda, MD 20824-0105. (301) 251-1222. http://www.nhlbi.nih.gov.

Texas Heart Institute. Heart Information Service. PO Box 20345, Houston, TX 77225-0345. http://www.tmc.edu/thi.

KEY TERMS

Arteries Blood vessels that carry blood to organs and other tissues of the body.

Arteriosclerosis Hardening and thickening of artery walls.

Cushing's syndrome A disorder in which too much of the adrenal hormone, cortisol, is produced; it may be caused by a pituitary or adrenal gland tumor.

Diastolic blood pressure Blood pressure when the heart is resting between beats.

Hypertension High blood pressure.

Renal artery stenosis Disorder in which the arteries that supply blood to the kidneys constrict.

Sphygmomanometer An instrument used to measure blood pressure.

Systolic blood pressure Blood pressure when the heart contracts (beats).

Vasodilator Any drug that relaxes blood vessel walls.

Ventricle One of the two lower chambers of the heart.

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Hypertension

Hypertension

DIAGNOSING HYPERTENSION

STRESS AND HYPERTENSION

TREATMENT OF HYPERTENSION

BIBLIOGRAPHY

Hypertension (high blood pressure) is a highly prevalent and largely symptomless chronic medical condition that affects almost one in three adults living in industrialized nations. Hypertension is more prevalent among blacks than whites, with prevalence rates of black Americans among the highest in the world. Among whites, hypertension is more prevalent among males than females until age sixty-five, when females with hypertension begin to outnumber males. Among blacks, hypertension becomes more prevalent among females in comparison to males much earlier, beginning at age forty-five. Although prevalence rates of hypertension typically increase with age in industrialized countries, inhabitants of nonindustrialized countries maintain stable blood pressures across their lifespan, suggesting that lifestyle factors associated with industrialization are associated with an increased propensity for developing hypertension. Prevalence rates for hypertension among Hispanic or Latino, Asian, and Native American populations are much lower than among white and black Americans.

There are two forms of hypertension: primary (or essential) hypertension and secondary hypertension. Essential hypertension represents the vast majority of cases and is characterized by chronically elevated blood pressure of unknown origin. In contrast, secondary hypertension is characterized by elevated blood pressures caused by another physiological abnormality, such as kidney disease, endocrine disturbances, or blockage of blood circulation. Regardless of form, hypertension is associated with increased risk for a number of diseases of the cardiovascular system, including coronary heart disease, stroke, peripheral artery disease, and congestive heart failure. Hypertension is therefore the primary cause of mortality in more than 10 percent of deaths among whites and more than 20 percent of deaths among blacks.

DIAGNOSING HYPERTENSION

The diagnosis of hypertension is typically made by a physician during a medical evaluation in a clinic setting. As part of this evaluation, measures of blood pressure are obtained by temporarily blocking blood flow in the brachial artery (upper arm) with an occluding cuff and listening to sounds of blood pulsations, called Korotkoff sounds, as arterial flow resumes. The first sound detected is associated with the magnitude of arterial pressure during cardiac contraction and is called systolic blood pressure (SBP). The disappearance of the Korotkoff sounds that occurs when blood flow returns to normal is associated with the magnitude of arterial pressure during cardiac refilling and is called diastolic blood pressure (DBP). Measures of SBP that are less than 120 millimeters of mercury (mm Hg) and DBP that are less than 80 mm Hg are considered within the normal range. SBPs and DBPs higher than these values are associated with increased risks for cardiovascular disease consequences in a linear fashion; a diagnosis of Stage 1 hypertension is assigned for patients with SBPs between 140 and 159 mm Hg or DBPs between 90 and 99 mm Hg, and a diagnosis of Stage 2 hypertension is assigned for patients with SBPs greater than 160 mm Hg or DBPs greater than 100 mm Hg.

It is well established that blood pressures measured by health care professionals in clinic settings often bear little correspondence to blood pressures that occur during daily life, creating diagnostic dilemmas for health care providers. In some cases, patients exhibit high blood pressures in the clinic but normal blood pressures in other settings, a condition called white coat hypertension from the presumption that these patients display physiological stress reactions while having their blood pressure measured. Another group of patients exhibits normal blood pressures in the clinic setting accompanied by elevated blood pressures throughout daily life. This condition has been termed masked hypertension, as both physician and patient are unaware of the elevated blood pressures unless sophisticated automated blood pressure devices, called ambulatory blood pressure monitors, are used to assess blood-pressure levels throughout a normal day. White coat hypertension is typically associated with lesser risk for cardiovascular disease, while masked hypertension is associated with risk profiles comparable to patients with untreated hypertension.

STRESS AND HYPERTENSION

It is widely recognized that an exposure to stressful life events, such as enduring natural or human-made disasters, being employed in a highly stressful job, or living in conditions of socioeconomic deprivation, is associated with increased blood pressure. However, not all persons exposed to these types of stressful events or life situations develop hypertension. This suggests that individual difference factors exist that either increase or decrease vulnerability for developing hypertension. Individual difference factors associated with a risk for hypertension can be categorized into three types: demographic and historical developmental factors, modifiable psychological or behavioral factors, and modifiable social factors.

Demographic and historical developmental variables represent risk factors that cannot be modified by the individual. For example, it is well known that hypertension runs in families, suggesting a genetic contribution. A risk for hypertension associated with ones age, gender, or race represents other factors that are not modifiable by the individual. Specific medical conditions such as diabetes mellitus or obesity are also associated with an increased risk for hypertension.

Several modifiable lifestyle behavioral factors are associated with an increased risk for hypertension; foremost among these are physical inactivity and excessive consumption of alcohol or sodium. Three psychological characteristics have also been associated with hypertension. First, hypertensive patients often exhibit higher rates of symptoms of depression, anxiety, and anger than persons with normal blood pressure, leading researchers to hypothesize that a negative affect is associated with an increased risk for hypertension. Second, hypertensive patients have been shown to express anger less effectively than persons with normal blood pressure, either displaying more overt aggression during confrontation or suppressing the expression of anger entirely. Third, hypertensive patients exhibit higher rates of emotional defensiveness than persons with normal blood pressures, indicating that this tendency to be out of touch with their emotions may play a role in their condition.

A few modifiable social environment factors have also been implicated in establishing risk for developing hypertension. Families of hypertensive patients, for example, have been characterized as exhibiting less social skill than those of non-hypertensive patients, particularly when handling conflict. Further, as with many other chronic medical conditions, a lack of social support is strongly associated with an increased incidence of hypertension.

No single demographic, modifiable psychological, or social environmental individual difference variable explains entirely why stress leads to hypertension, suggesting that a combination of factors explains the association between stress and hypertension. For example, several individual difference variables have been hypothesized to explain the high prevalence of hypertension among black Americans. First, increased sodium retention in response to stress has been observed among black Americans that some social epidemiologists believe results from adaptive physiologies of African ancestors who survived the middle passage from Africa to America. Second, the psychological construct of John Henryism, described as effortful active coping in the face of extreme adversity, has been directly associated with blood-pressure levels in some black American samples, particularly those of low socio-economic status. Finally, an exposure to the racism and discrimination that is frequently experienced by many black Americans represents a social environmental factor that has been linked to higher blood pressure. Although consistent support linking each of these three individual difference variables to hypertension is lacking, there is sufficient evidence to suggest that each affects blood-pressure levels for some black Americans and is partly involved in explaining their increased prevalence of hypertension.

The physiological mechanisms through which psychological, behavioral, and social factors influence the risk for hypertension are unknown, although the autonomic nervous system is thought to be involved. Evidence from animal studies and from prospective trials on humans has revealed that participants who exhibit exaggerated blood-pressure responses to stress are more likely to develop hypertension later in life. According to this reactivity hypothesis, psychological factors, like the experience or inappropriate expression of anger, promote the onset of hypertension only inasmuch as they result in elevated blood-pressure responses to stress, which are presumably driven by the autonomic nervous system. Based upon this hypothesis, a considerable amount of research has linked various risk factors associated with hypertension to the magnitude of blood-pressure reactivity to stress. For example, healthy offspring of hypertensive parents exhibit greater blood-pressure reactions to stress than offspring of non-hypertensive parents. Similarly, both overt aggression and anger suppression are associated with heightened blood-pressure reactions to stress, in contrast to the appropriate expression of anger. Although the exact pathway through which psychosocial risk factors exert their influence on blood pressureregulating organs is still unknown, the reactivity hypothesis has provided important clues regarding how a psychological construct like suppressed anger could lead to a physiological disturbance of blood-pressure regulation.

TREATMENT OF HYPERTENSION

Because of the high prevalence and lethal consequences of hypertension, a number of interventions have been developed to lower blood pressure. The primary treatment strategy for both lowering blood pressure and reducing the risk of cardiovascular disease associated with hypertension consists of a variety of antihypertensive medications.

Although the various classes of medications operate through different physiological pathways, they all are potent blood pressurelowering agents. Unfortunately, a large number of hypertensive patients do not take their medication as prescribed, partly because the side effects can be more noticeable than the condition of hypertension itself.

Several non-pharmacologic methods are known to lower blood pressure and have served as useful adjunct treatments for hypertensive patients and as primary preventive strategies for persons at risk for developing hypertension. Weight loss, typically achieved through a combination of dietary management and increased physical activity, can result in blood-pressure reductions comparable to antihypertensive medication. Sodium restriction and potassium supplementation also reduce blood pressures, particularly among patients who are sodium sensitive. Eliminating the consumption of alcohol is an effective means of lowering blood pressure among hypertensive patients who consume alcohol regularly.

Because psychological factors are linked to hypertension, the blood pressurereducing properties of three psychological interventions have been examined: relaxation, biofeedback, and individualized stress-management programs. The magnitude of blood-pressure reductions observed with relaxation and biofeedback interventions is generally much lower than those observed with anti-hypertensive medication. Because stress-management approaches are individualized based upon the patients unique psychological profile, larger reductions in blood pressure have been observed.

Hypertension is a chronic medical condition with no single cause. By considering both pharmacologic and non-pharmacologic interventions with respect to each individual patient, effective intervention and prevention programs will help eliminate hypertension as a public health problem.

BIBLIOGRAPHY

American Heart Association. 2004. Heart Disease and Stroke Statistics2005 Update. Dallas, TX: American Heart Association.

Blumenthal, James A., Andrew Sherwood, Elizabeth C. D. Gullette, et al. 2002. Biobehavioral Approaches to the Treatment of Essential Hypertension. Journal of Clinical and Consulting Psychology 70 (3): 569589.

Brondolo, Elizabeth, Ricardo Rieppi, Kim P. Kelly, and William Gerin. 2003. Perceived Racism and Blood Pressure: A Review of the Literature and Conceptual and Methodological Critique. Annals of Behavioral Medicine 25 (1): 5565.

Chobanian, Aram V., George L. Bakris, Henry R. Black, et al. 2003. Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Hypertension 42 (6): 12061252.

Fields, Larry E., Vicki L. Burt, Jeffrey A. Cutler, et al. 2004. The Burden of Adult Hypertension in the United States 1999 to 2000: A Rising Tide. Hypertension 44 (4): 398404.

Jorgensen, Randall S., Blair T. Johnson, Monika E. Kolodziej, and George E. Schreer. 1996. Elevated Blood Pressure and Personality: A Meta-analytic Review. Psychological Bulletin 120 (2): 293320.

Larkin, Kevin T. 2005. Stress and Hypertension: Examining the Relation between Psychological Stress and High Blood Pressure. New Haven, CT: Yale University Press.

Kevin T. Larkin

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Hypertension

Hypertension

Blood pressure is the force with which blood pushes against the artery walls as it travels through the body. Like air in a balloon, blood fills arteries to a certain capacityand just as too much air pressure can cause damage to a balloon, too much blood pressure can harm healthy arteries. Blood pressure is measured by two numberssystolic pressure and diastolic pressure. Systolic pressure measures cardiac output and refers to the pressure in the arterial system at its highest. Diastolic pressure measures peripheral resistance and refers to arterial pressure at its lowest. Blood pressure is normally measured at the brachial artery with a sphygmomanometer (pressure cuff) in millimeters of mercury (mm Hg) and given as systolic over diastolic pressure.

A blood pressure reading thus appears as two numbers. The upper number is the systolic pressure, which is the peak force of blood as the heart pumps it. The lower number is the diastolic pressure, which is the pressure when the heart is filling or relaxing before the next beat. Normal blood pressure for an adult is 120/70 (on average), but normal for an individual varies with the height, weight, fitness level, age, and health of a person.

What Is Hypertension?

Hypertension, or high blood pressure, is defined as a reading of 140/90 on three consecutive measurements at least six hours apart. The definition varies for pregnant women, where hypertension is defined as 140/90 on two consecutive measurements six hours apart. Consistently high blood pressure causes the heart to work harder than it should and can damage the coronary arteries, the brain, the kidneys, and the eyes. Hypertension is a major cause of stroke .

Types of Hypertension

Hypertension is classified as either primary (or essential ) hypertension or secondary hypertension. Primary hypertension has no specific origin but is strongly associated with lifestyle. It is responsible for 90 to 95 percent of diagnosed hypertension and is treated with stress management, changes in diet , increased physical activity, and medication (if needed). Secondary hypertension is responsible for 5 to 10 percent of diagnosed hypertension. It is caused by a preexisting medical condition such as congestive heart failure, kidney failure, liver failure, or damage to the endocrine (hormone ) system.

Pregnancy-induced hypertension (PIH) may appear in otherwise healthy women after the twentieth week of pregnancy. It is more likely to occur in women who are overweight or obese . PIH may be mild or severe, and it is accompanied by water retention and protein in the urine. About 5 percent of PIH cases progress to preeclampsia. Preeclampsia is characterized by dizziness, headache, visual disturbance, abdominal pain, facial edema , poor appetite, nausea , and vomiting. Severe preeclampsia affects the mother's blood system, kidneys, brain, and other organs. In rare cases, the woman can die. Preeclampsia is more likely to occur during first pregnancies, multiple fetuses, in women with existing hypertension, and in women younger than twenty-five years old or over thirty-five years old. If convulsions occur with PIH, it is called eclampsia. PIH disappears within a few weeks after birth.

Causes of Hypertension

Many prescription and over-the-counter drugs can cause or exacerbate hypertension. For example, corticosteroids and immunosuppressive drugs increase blood pressure in most solid-organ transplant recipients. Medication taken for pain and inflammation such as nonsteroidal anti-inflammatory drugs (NSAIDs) and cyclooxygenase-2 (COX-2) inhibitors may raise blood pressure since their antiprostaglandin properties affect the kidneys.

Tobacco products (cigarettes, cigars, smokeless tobacco) contain nicotine, which temporarily increases blood pressure (for about thirty minutes or less). The blood pressure of smokers should be rechecked after thirty minutes if initial readings are high. Nicotine patches that are used for smoking cessation do not appear to increase blood pressure.

There does not appear to be a direct relationship between caffeine and chronic hypertension, even though caffeine intake can cause an acute (rapid but brief) increase in blood pressure. This may be due to the fact that tolerance to caffeine develops rapidly.

Chronic overuse of alcohol is a potentially reversible cause of hypertension. Five percent of hypertension is due to alcohol consumption and 30 to 60 percent of alcoholics have hypertension. Alcohol-induced hypertension is more likely to occur in women than men.

Diet and Hypertension

Sodium intake has been a primary target for hypertension control, though it is ranked fourth as the lifestyle factor associated with hypertension. About 50 percent of individuals appear to be "sodium sensitive." This means that excessive sodium intake tends to increase blood pressure in these groups of people, and they do not appear to excrete excessive amount of salt via the kidneys. Sodium-sensitive individuals include the elderly, obese individuals, and African Americans. The Dietary Guidelines for Americans recommend that adults consume no more than 2,400 milligrams of sodium daily. There are a number of ways to limit sodium in the diet, including:

  • Do not use salt at the table
  • Check food labels for sodium content
  • Choose unprocessed foods
  • Limit processed meats and cheeses
  • Limit pickled meats and vegetables
  • Limit salty snacks
  • Limit intake of soy sauce, BBQ sauce, and other condiments and foods that may be high in sodium

Potassium supplements (24 grams daily) have been shown to moderately decrease blood pressure. Fruits and vegetables are excellent sources of potassium. The Dietary Guidelines for Americans recommend that adults consume at least 3,500 milligrams of potassium daily. A diet high in fruits and vegetables has been linked to a decreased risk of both hypertension and stroke. Foods high in omega-3 fatty acids have positive effects on hypertension and cardiovascular disease by relaxing arteries and thinning the blood. In addition, several studies have demonstrated that individuals with hypertension may benefit from daily doses of calcium (800 mg) or magnesium (300 mg).

The DASH Eating Plan

Research has shown that a diet that is low in sodium but rich in calcium, potassium, and magnesium can decrease blood pressure, especially among African Americans. This eating plan is called the DASH (Dietary Approach to Stop Hypertension) eating plan and it is as effective in decreasing blood pressure as some medications commonly used to treat hypertension. The DASH eating plan is based on 2,000 calories a day with 18 percent of the calories coming from protein, 55 percent from carbohydrates , and 27 percent from fats. The eating plan contains less fat than the Food Guide Pyramid, more fruits and vegetables, and includes a serving of nuts.

Pharmacological Treatment of Hypertension

Hypertension is commonly treated with medication, and a combination of two or more drugs is common. Patients are usually given a diuretic to help them excrete excess fluids. However, most diuretics also cause excretion of potassium in the urine, and individuals on diuretics should monitor their potassium intakes. Drugs used to control hyertension include beta-blockers (e.g., atenolol [Tenorim]) which act to slow heart rate and cause some vasodilation (widening of the lumen, or interior, of blood vessels). Drugs that contain calcium channel blockers (e.g., amlopidine [Norvasc]) or angiotensinconverting enzyme (ACE) inhibitors also cause vasodilation.

Lifestyle Treatment of Hypertension

Most of the risk factors for primary hypertension are preventable, and lifestyle modification may prevent as well as treat the condition. Secondary hypertension can be managed by treating the underlying cause. Individuals in the high normal and stage 1 hypertension categories should attempt to lower blood pressure through diet and lifestyle changes before going on a regimen of medications. Recommendations include:

  • Eliminate tobacco
  • Control stress
  • Maintain weight at 15 percent or less of desirable weight
  • Restrict alcohol intake to no more than two drinks a day for men and one for women (one drink equals 12 ounces of beer, 5 ounces of wine, or 1.5 ounces 80-proof whiskey)
  • Restrict sodium intake to 1.5 to 2.5 grams per day (4 to 6 tsp salt)
  • Exercise five to seven days a week for sixty minutes per session
  • Increase intake of fruits and vegetables
  • Increase intake of low-fat dairy products

see also Cardiovascular Diseases; Heart Disease.

Delores C. S. James

Bibliography

Anderson, Douglas M., et al. (2003). Mosby's Medical, Nursing, and Allied Health Dictionary, 6th edition. St. Louis, MO: Mosby.

Worthington-Roberts, B., and Williams, S. (1997). Nutrition in Pregnancy and Lactation, 6th edition. Madison, WI: Brown and Benchmark.

Internet Resources

Onusko, E. (2003). "Diagnosing Secondary Hypertension." American Family Physician 67:6774. Also available from <http://www.aafp.org/afp>

National Heart, Lung, and Blood Institute. "Facts about the DASH Eating Plan." Available from <http://www.nhlbi.gov/health>

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hypertension

hypertension or high blood pressure, elevated blood pressure resulting from an increase in the amount of blood pumped by the heart or from increased resistance to the flow of blood through the small arterial blood vessels (arterioles). Hypertension is generally defined as a blood pressure reading greater than 140 over 90; presssures of 120–139 over 80–89 are now considered prehypertension. When the cause is unknown, the hypertension is called primary, or essential, hypertension. When a cause can be identified (e.g., a disorder of the adrenal glands, kidneys, or arteries), the condition is known as secondary hypertension. Factors such as heredity, obesity, smoking, and emotional stress are thought to play a role; the usual immediate cause is an imbalance in the body's vasoconstriction/fluid retention systems, often involving a decrease in the kidney's secretion of the regulatory hormone, renin.

Known as the "silent killer," hypertension often produces few overt symptoms; it may, however, result in damage to the heart, eyes, kidneys, or brain and ultimately lead to congestive heart failure, heart attack (see infarction), kidney failure, or stroke. African Americans and women are the most affected. Treatment of hypertension includes diets to reduce weight and salt and alcohol intake, increased exercise, quitting smoking, and various drugs, such as diuretics, ACE inhibitors, beta-blockers, calcium-channel blockers or angiotensin-receptor blockers, as well as biofeedback. Many patients require a combination of drugs to control their blood pressure. Treatment for persons with prehypertension includes dietary and other lifestyle changes. Recent research has questioned the importance of dietary salt as a major contributor to hypertension; some studies point to low calcium intake as a cause.

See also eclampsia.

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hypertension

hypertension (hy-per-ten-shŏn) n. high blood pressure, i.e. elevation of the arterial blood pressure above the normal range expected in a particular age group. Hypertension may be of unknown cause (essential h. or hyperpiesia). It may also result from disease (secondary or symptomatic h.), as of the kidneys (renal h.), endocrine system, or arteries. Complications that may arise from hypertension include atherosclerosis, heart failure, cerebral haemorrhage, and kidney failure. Most cases of hypertension depend upon long-term drug therapy to lower the blood pressure and maintain it within the normal range. The drugs used include thiazide diuretics, ACE inhibitors, and calcium-channel blockers. See also portal hypertension, pulmonary (hypertension).

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Hypertension

HYPERTENSION

DEFINITION


Hypertension is the medical name for high blood pressure.

DESCRIPTION


The circulatory system is the network of organs and blood vessels through which blood travels in the body. Blood is pumped out of the heart into blood vessels known as arteries. After passing through the body, blood returns to the heart by way of blood vessels known as veins.

As blood flows through arteries and veins, it pushes on their walls. Blood pressure is defined as the force exerted by blood inside arteries.

Blood does not flow steadily through the circulatory system. At one moment, the heart muscle squeezes blood out of the heart into the arteries. At this point, the blood pressure is high because of the force exerted by the heart. At the next moment, the heart muscle relaxes to let fresh blood into the heart. At this point, the blood pressure is lower because of reduced force by the heart muscle.

Hypertension: Words to Know

Arteries:
Blood vessels that carry blood from the heart to organs and tissues of the body.
Arteriosclerosis:
Hardening and thickening of artery walls.
Diastolic blood pressure:
Blood pressure exerted by the heart when it is resting between beats.
Sphygmomanometer:
An instrument used to measure blood pressure.
Systolic blood pressure:
Blood pressure exerted by the heart when it contracts (beats).
Vasodilator:
Any drug that causes a blood vessel to relax.

The two stages of high and low blood pressure have special names. The highest pressure reached by blood in the arteries is called the systolic pressure. The lowest pressure reached by blood in the arteries is known as the diastolic pressure.

When a doctor or nurse takes a person's blood pressure, he or she records two readings: the systolic (highest) and the diastolic (lowest) pressure. For example, a patient's blood pressure might be recorded as 140/80, which is read as "140 over 80." That reading means that the patient's highest blood pressure is 140 and the lowest blood pressure is 80.

The numbers 140 and 80 are measured in units called "millimeters of mercury" or "mm Hg." This unit is commonly used by scientists to measure pressure.

The American Heart Association considers blood pressure less than 140 and greater than 90 to be normal for adults. A person whose diastolic pressure is less than 90 is said to have low blood pressure. Someone with a systolic pressure of more than 140 is said to have high blood pressureor hypertension.

Hypertension is a serious problem because people with the condition have a higher risk for heart disease and other medical problems than people with normal blood pressure. If left untreated, hypertension can lead to a number of medical conditions, including:

  • Arteriosclerosis
  • Heart attack (see heart attack entry)
  • Stroke (see stroke entry)
  • Enlarged heart
  • Kidney damage

Arteriosclerosis is also called hardening of the arteries. The arteries are normally flexible. They expand and contract to adjust to the flow of blood through them. High blood pressure can cause artery walls to become thick and tough. The arteries themselves may become narrower. Blood cannot flow as easily through them.

When that happens, certain substances in the blood can begin to build up inside the arteries. These substances make the openings even narrower. Eventually, an artery may close completely. When that happens, blood can no longer flow through the circulatory system. A blocked artery can result in a heart attack or a stroke.

Hypertension can also damage the heart itself because the heart has to work harder to push blood through the circulatory system. It grows larger to keep up with this job. If the heart becomes too large, it may no longer be able to pump enough blood through the body. The heart may fail.

Kidneys can also be damaged by hypertension. The kidneys filter waste products from the blood. If blood vessels to the kidneys become clogged, fewer wastes are removed from the blood. The kidneys may fail and wastes may build up in the blood. About 25 percent of the people who are treated for failed kidneys have hypertension.

CAUSES


High blood pressure can be caused by certain events in a person's life. For example, strenuous physical activity or stress can cause blood pressure to rise. However, high blood pressure is usually temporary in such cases. When the activity ceases or the stress goes away, the blood pressure returns to normal. This form of high blood pressure is not regarded as a form of hypertension.

True hypertension exists only when a person has high blood pressure readings on a number of different occasions. If a doctor suspects hypertension, he or she will take a number of blood pressure readings over a period of weeks. If those readings are consistently high, the patient may have hypertension.

The cause of hypertension in 90 to 95 percent of all cases is not known. One important factor may be heredity. People who have family members with hypertension are more likely to develop the condition than people whose family members have no hypertension. Hypertension with no known cause is called primary hypertension.

Hypertension can also be caused by a variety of medical conditions. For example, people with kidney disorders may develop hypertension. The kidneys regulate the balance of water and salt in the body. If the kidneys do not function normally, the amount of salt and water in the body may increase. This increase can cause high blood pressure.

Other conditions that can cause hypertension include blood vessel diseases, disorders of the thyroid or other glands, alcoholism (see alcoholism entry), pregnancy, and the use of certain prescription drugs. Hypertension caused by some other medical problem is known as secondary hypertension.

Certain factors are known to increase a person's risk for hypertension. These factors include:

  • Age over sixty
  • Male sex
  • Heredity
  • Sensitivity to table salt
  • Obesity (see obesity entry)
  • Inactive lifestyle
  • Heavy alcohol consumption
  • Use of oral contraceptives (birth control pills)

SYMPTOMS


Hypertension is a major health problem, especially because it has no symptoms. Many people have hypertension without knowing it. In the United States, about fifty million people age six and older have high blood pressure. Hypertension is more common in men than women and in people over the age of sixty-five than in younger persons.

DIAGNOSIS


Because hypertension does not produce symptoms it is important to have regular checkups. Taking a person's blood pressure is simple and painless. A doctor or nurse uses an instrument called a sphygmomanometer. A sphygmomanometer (pronounced SFIG-moh-muh-nahm-et-er) consists of a cloth-covered rubber cuff and a pressure valve. The cuff is wrapped around the patient's arm, and air is pumped into the cuff. As the air is slowly released, the doctor or nurse listens through a stethoscope to the sound of the blood rushing through the artery. He or she reads the pressure at which he or she hears distinctive heart sounds (the "lubb" and "dubb" made when a heart beats). These readings provide the patient's systolic and diastolic blood pressures.

MEASURING BLOOD PRESSURE

Blood exerts pressure. Anyone who has ever cut an artery knows that fact. When that happens, blood gushes out of the artery with surprising force. That fact was first discovered by the English physician William Harvey (15781657) in the 1600s.

No one actually tried to measure blood pressure, however, until nearly a century later. Then, the English clergyman and physiologist Stephen Hales devised the first blood pressure measuring device. He cut open the blood vessel in various animals and inserted a metal pipe into the vessel. He then connected the pipe to a long glass tube. Blood was pushed out of the vessel into the glass tube. The blood rose to different levels in the tube for different animals.

It took another century for physicians to find a way to take blood pressure without actually cutting into a blood vessel. In 1876, the German physician Samuel Siegried von Basch (18371905) invented the first sphygmo-manometer (pronounced SFIG-moh-muh-nahmet-er). That tongue-twisting name describes the type of blood pressure measuring device used today. It consists of a rubber tube placed around the patient's upper arm. Air is pumped into the tube. Pressure from the air briefly cuts off the flow of blood in the patient's arm.

As the air is released from the tube, the medical worker listens to the patient's arm through a stethoscope. As blood starts flowing in the arm again, the sound produced by systolic pressure can be heard. A few moments later, the sound produced by the diastolic pressure can be heard. The worker notes the amount of pressure observed in a gauge on the arm band at each sound. These two pressures make up the patient's blood pressure reading.

There is no single point at which a person is said to have hypertension. Instead, certain levels of the condition are set depending on the person's blood pressure. These levels are as follows:

  • Normal blood pressure: In the range 130/85
  • High normal: In the ranges 130140/8590
  • Mild hypertension: In the ranges 140160/90100
  • Moderate hypertension: In the ranges 160180/100110
  • Severe hypertension: In the ranges 180210/110120
  • Very severe hypertension: Higher than 210/120

Patients with higher-than-normal blood pressure may then be given other tests. These include:

  • Medical and family histories. These help a doctor find out if the patient has risk factors in his or her family. If hypertension is common in the family, the patient is likely to be at higher risk for the condition.
  • Physical examination. Sometimes other health problems may be discovered during a physical examination that explain the patient's high blood pressure.
  • Examination of the blood vessels in the eyes. High blood pressure may cause blood vessels in the eyes to become thick or narrow. Bleeding in the eyes may also be visible.
  • Chest X ray. This is used to check for an enlarged heart, other heart disorders, and lung disease.
  • Electrocardiograph (ECG). This test measures the electrical activity of the heart. It can determine whether the heart muscle is functioning normally.
  • Blood and urine tests. These help determine the general health of the patient.

TREATMENT


There is no cure for primary hypertension, but blood pressure can almost always be reduced with the correct treatment. The goal of this treatment is to prevent the complications of hypertension.

In cases of secondary hypertension, one approach is to treat the medical condition that causes hypertension. Efforts may be made at the same time to reduce the patient's blood pressure.

A program designed to reduce blood pressure usually has three parts: changes in diet, a plan of regular exercise, and antihypertensive medications. Some changes in lifestyle that can reduce blood pressure include the following:

  • Reducing salt intake
  • Reducing fat intake
  • Losing weight
  • Getting regular exercise
  • Quitting smoking
  • Reducing alcohol consumption
  • Learning how to manage stress

For patients with mild or moderate hypertension, these steps may be enough to bring their blood pressure into the normal or high normal range. For patients with more serious hypertension, medications may be prescribed. A variety of medications are available for the treatment of hypertension. They fall into the following categories:

  • Diuretics help the kidneys eliminate excess salt and water. The loss of fluid from the kidneys causes arteries to expand and blood pressure to become lower.
  • Beta-blockers cause the heart to beat more slowly and with less force.
  • Calcium channel blockers help relax muscle cells, reducing the force with which they pump blood.
  • Angiotensin converting enzyme (ACE) inhibitors are chemicals that prevent blood vessels from tightening up. As a result, the pressure exerted by blood in the blood vessels is reduced.
  • Alpha-blockers act on the nervous system, causing arteries to expand and reduce the pressure exerted by the heart on blood flow.
  • Vasodilators are chemicals that act directly on arteries, causing them to relax (dilate) so that blood can move more easily through them.
  • Nervous system antagonists and agonists act on the nerves that control the size of arteries. They cause arteries to open and allow blood to flow through them more easily.

PROGNOSIS


There is no cure for hypertension, but it can be controlled by changes in one's lifestyle and the use of medications. The major goal of treatment is to avoid the most serious complications of hypertension, such as heart disease and strokes.

PREVENTION


Some risk factors of hypertension cannot be eliminated. For example, a person may inherit a tendency for the disorder. But many risk factors can be prevented or reduced. Some of the most important changes a person can make in his or her life to prevent hypertension include the following:

  • Reduce salt intake.
  • Reduce fat intake.
  • Lose weight.
  • Get regular exercise.
  • Quit smoking.
  • Reduce alcohol consumption.
  • Learn how to manage stress.

FOR MORE INFORMATION


Books

Murray, Michael T. Heart Disease and High Blood Pressure: How You Can Benefit from Diet, Vitamins, Minerals, Herbs, Exercise, and Other Natural Methods. Rocklin, CA: Prima Publishing, 1997.

Pickering, Thomas. Good News About High Blood Pressure: Everything You Need to Know to Take Control of HypertensionAnd Your Life. New York: Simon and Schuster, 1996.

Texas Heart Institute. Heart Owner's Handbook. New York: John Wiley and Sons, 1996.

Wood, Stephen, and George Wood. Conquering High Blood Pressure: The Complete Guide to Managing Hypertension. New York: Insight Books, 1997.

Organizations

American Heart Association. 7272 Greenview Ave., Dallas, TX 75231-4596. (800) AHSUSA1. http://www.amhrt.org.

National Heart, Lung, and Blood Institute. Information Center. PO Box 30105, Bethesda, MD 208240105. (301) 2511222.

Web sites

"Ask NOAH About: Heart Disease and Stroke." NOAH: New York Online Access to Health. [Online] http://www.noah.cuny.edu/heart_disease/heartdisease.html#H. (accessed on October 25, 1999).

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hypertension

hypertension High blood pressure. There is no exact level of blood pressure which labels a person hypertensive, but values as high as 160 mm Hg/90 mm Hg (= systolic/diastolic; highest and lowest in the period of one heart beat) would generally be regarded as marginal in someone at rest. A systolic blood pressure higher than this is reached by healthy people in heavy exercise, and if the exercise is ‘static’ (isometric), both systolic and diastolic are higher; but ‘hypertension’ is a term usually reserved for abnormally high pressure at rest.

Stuart Judge


See blood pressure.

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Hypertension

Hypertension

What Is Hypertension?

Who Has High Blood Pressure?

What the Numbers Mean

How Does the Body Control Blood Pressure?

What Causes Hypertension?

How Does Hypertension Affect the Body?

Hypertension Is Defined by Numbers

How Is Hypertension Diagnosed?

How Is Hypertension Treated?

Can Hypertension Be Prevented?

Hypertension, or high blood pressure, is a condition in which the pressure of the blood in the arteries is above normal.

KEYWORD

for searching the Internet and other reference sources

Heart disease

What Is Hypertension?

Hypertension is the medical term for high blood pressure. Arteries are the blood vessels that carry the blood from the heart through the entire body. High blood pressure results either when the output of the blood pumped by the heart increases, or when there is an increased resistance to the flow of blood through the arteries, or both. In terms of numbers, a resting blood pressure of 140/90 or greater in an adult is usually considered to be high. Normal blood pressure levels are lower in children and rise with age.

Everyones blood pressure goes up in moments of excitement or stress, and that is considered to be normal. High blood pressure is considered a medical condition only when it continues over an extended period of time. This condition can then become a serious threat to health; the higher the pressure and the longer it is untreated, the greater the risk.

People who have hypertension are more likely to suffer a stroke, heart attack, or failure of the kidneys or heart. For this reason, and because there usually are no symptoms, hypertension has been termed the silent killer.

Who Has High Blood Pressure?

Hypertension definitely is not the kind of condition one person can catch from another. Its causes are varied and complex: hereditary (genetic) factors, medical conditions, or medications can play roles. In most cases, no single cause for a persons hypertension can be found.

Certain generalizations can be made about its prevalance* in the overall population, however. It has been estimated that 60 million people in the United States have high blood pressure. This amounts to about 20 percent of the population, or one in every five persons. This prevalance is believed to be about the same in most industrialized Western countries; but the prevalance of high blood pressure is relatively low in developing (poor) or Third World countries.

* prevalance
of a disease or condition means how common it is in a population of people.

It is further estimated that about one-third to one-half of people with high blood pressure are unaware of their condition. Many people first find out when they go for a routine medical check-up.

The prevalance of hypertension is slightly higher in women than in men. Men and women of African descent are both more likely than others to develop the disorder. Hypertension usually begins after ages 20 to 30, and is uncommon in children and teenagers. Besides age, gender, and race, factors that have been linked to high blood pressure include obesity, smoking, a diet high in sodium (such as that found in table salt), excessive use of alcohol, and a family history of the disorder.

What the Numbers Mean

Blood pressure is measured in units called millimeters of mercury (mm Hg). It is written as two numbers, one over the other. The number on top is the systolic pressure (when the heart contracts). The bottom number is the diastolic pressure (when the heart relaxes between beats).

 BLOOD PRESSURE IN ADULTS   
Normal Pressure Systolic (mm Hg)  Diastolic (mm Hg)
Idealless than 120andless than 80
Normalless than 130andless than 85
High normal130-139or85-89
Hypertension    
STAGE 1 (Mild)140-159or90-99
STAGE 2 (Moderate)160-179or100-109
STAGE 3 (Severe)180 or higheror110 or higher

How Does the Body Control Blood Pressure?

As the heart forces blood into the arteries, the blood is kept under constant pressure. Many times a day, blood pressure rises briefly when the heart beats faster to supply blood to the parts of the body that need it. For example, a persons legs will need more blood when he or she is running a race. After the effort has ended, the blood pressure returns to its usual level.

Did You Know?

  • People almost never can tell whether or not they have high blood pressure by how they feel.
  • About one-third to one-half of the people who have high blood pressure do not even know it.
  • Hypertension is called the silent killer because it can cause heart attack and stroke without warning symptoms.
  • Many people with mild hypertension can be treated without the use of drugs.
  • The guidelines for preventing high blood pressure are the same as the guidelines for leading a healthy life.

Over time, when a person is at rest, the body controls blood pressure in two basic ways. One way is by constricting, or narrowing, the arterioles (ar-TEE-re-olz), blood vessels that branch off larger arteries. The other way is by regulating the fluid volume of the blood.

The kidneys have a key role in both of these functions. By secreting the hormone renin, they cause the arterioles to constrict, thereby raising the blood pressure. In addition, the kidneys control the fluid volume of the blood either by retaining sodium or by excreting it into the urine. Blood volume and blood pressure increase when sodium is retained in the body.

What Causes Hypertension?

Hypertension results when the body systems, which keep the width of the arterioles and the fluid volume of the blood in a normal relationship, become unbalanced. This disruption may occur because of disease or some other influence. Disease, such as disorders of the kidneys, certain tumors, or artery conditions, account for only about 10 percent of hypertension cases. In the great majority of patients, the precise cause remains unknown. In these instances, the disorder is referred to as primary hypertension or essential hypertension.

Certain factors are known to be influential in producing hypertension. Factors that may contribute to the development of hypertension include a fatty diet and lack of exercise (which can lead to obesity) and too much salt in the diet. Hypertension also occasionally occurs in women who are taking birth control pills. Other factors include diabetes, smoking, and excessive alcohol consumption.

How Does Hypertension Affect the Body?

Hypertension rarely causes symptoms by itself. When it does, the blood pressure usually is extremely high. Symptoms may then include headache, nosebleeds, dizziness, confusion, and seizures. A florid (reddish) complexion is not, as is often believed, a sign of hypertension.

Hypertension leads to or speeds up the process of atherosclerosis (ath-er-o-skle-RO-sis), or hardening of the arteries. In this process, cholesterol and other materials carried in the blood can build up in places along the artery walls damaged by years of high pressure. If a blockage should occur in the coronary arteries, which supply blood to the heart muscle, a heart attack ensues. If artery blockage occurs in the brain, the result is a stroke. Damage to arterioles can lead to brain hemorrhage (another kind of stroke), kidney failure, or blindness. Over a period of years, hypertension can bring about heart failure by overworking the heart.

The course of hypertension if left untreated varies in different people. In most, the blood pressure tends to increase gradually over the years.

Hypertension During Pregnancy

A serious condition called preeclampsia (pree-ee-KLAMP-see-a) develops during the second half of pregnancy in about 7 percent of women. This disorder is characterized by a sudden rise in blood pressure, along with severe headaches, visual disturbances, and retention of fluids in the body. The condition is most common in first pregnancies and in women younger than 25 or older than 35. If left untreated, preeclampsia can lead to eclampsia, which is characterized by seizures and extremely high blood pressure that may be fatal to the mother or baby.

Hypertension Is Defined by Numbers

Blood pressure is expressed as two numbers: the systolic (sis-TOL-ik) pressure and the diastolic (dy-a-STOL-ik) pressure. The higher number is the systolic pressure, which occurs during systole (SIS-to-lee), when the heart contracts. The lower number is the diastolic pressure, which occurs during diastole (dy-AS-to-lee), when the heart relaxes between beats.

These numbers are read from a special instrument, called a sphygmomanometer (sfig-mo-ma-NOM-e-ter). Written down, the two numbers are separated by a slash. Normal pressure taken at rest in adults is about 120/80, expressed as 120 over 80. Healthy young adults typically will have a pressure of about 110/75, however, and normal blood pressures are even lower in young children. As previously mentioned, a pressure of 140/90 or more in adults means hypertension.

How Is Hypertension Diagnosed?

When diagnosing hypertension, the physician may take more than one reading, especially if the first reading is high. This is so because blood

pressure varies over time. Moreover, some patients have what is called white coat hypertension. This means that their blood pressure tends to go up when they are in a doctors office, because being in the presence of a physician makes them feel anxious. To get an accurate reading, doctors will try to have their patients feel as relaxed as possible. If the patient has never had his or her blood pressure taken before, it is important for the doctor to explain that the process is painless.

What Is a Sphygmomanometer?

A sphygmomanometer (sfig-mo-ma-NOM-e-ter) is the instrument that measures blood pressure. It consists of an inflatable cuff, or wide band, that is wrapped around the upper arm, a rubber bulb to inflate the cuff, and a device that gives the pressure reading.

In measuring the pressure, the cuff is inflated until it briefly stops the flow of blood in the arm (a painless process). The air pressure is then gradually released while a stethoscope (STETH-o-skope), a listening device, is placed on the artery of the arm just below the cuff. The pressure when the sound of the pulse is heard as the blood first begins to flow again is called the systolic pressure (the higher number). As more pressure is released, the sound of the pulse becomes muffled and disappears. The pressure at that point is called the diastolic pressure (the lower number).

The pressure is read on a gauge, which can be a glass column filled with mercury (the earliest type), a dial, or a digital readout. In some instruments, the blood pressure may be read directly, without the use of a stethoscope. The actual numbers in blood pressure readings represent millimeters of mercury (mm Hg), based upon the original glass column filled with mercury.

The word sphygmomanometer comes from the Greek sphygmos, meaning pulse, plus manometer, a pressure gauge.

Diagnosing high blood pressure has to do with more than just numbers, however. The doctor will have to try to determine the cause. The patient may be asked about eating and exercise habits. If someone else in the family has a history of high blood pressure, that may be important. The doctor also may want to know about the patients salt intake, consumption of alcohol, smoking habits, use of medications such as birth control pills, and use of street drugs. Urine and blood samples may be taken to check on kidney function and blood cholesterol levels.

It is commonly observed that blood pressure tends to go up with age. Although true statistically, this does not mean that it is acceptable from a health standpoint. Blood pressure of more than 140/90 usually is considered a cause of concern at any age.

How Is Hypertension Treated?

For the small percentage of patients whose hypertension is caused by particular disorders of the kidneys or certain tumors or artery conditions, surgery may be the chosen treatment and provide a cure. For the great majority, however, the choice of treatment will likely be lifestyle changes or medication in addition to lifestyle changes.

Good Health Habits

Many people who have mild hypertension (not much more than 140/90) can lower their blood pressure by adopting certain modifications in their lifestyle and diet, without the use of drugs. These changes may involve losing weight, getting more exercise, or modifying the diet in certain ways.

Excess weight, especially obesity, can be a factor in raising blood pressure. In losing weight, usually it is best to take a gradual approach and to emphasize reduction of fat in the diet. Any weight loss program also should include regular exercise such as walking briskly or jogging (with a doctors approval in adult patients). Many experts believe that it is almost impossible to lose weight permanently through diet alone.

Most people with hypertension can help to lower their blood pressure by going on a low-sodium, or low-salt, diet. Studies have shown that people can get all the salt they need in the foods they eat without adding any. Good rules to follow are to add less salt at the table and in cooking, and to shop for foods low in sodium. Labels on cans or packages of processed food will indicate how much sodium is contained in each portion.

Another factor that may be implicated in high blood pressure is stress. Although some stress is unavoidable in daily life, frequent unrelieved stress can be harmful. It is worthwhile to find ways, such as relaxation techniques, to lower stress levels. Physical exercise is an effective way to decrease stress and blood pressure in many people.

Common-sense rules about avoiding harmful substances apply to people with normal as well as high blood pressure. It is inadvisable to smoke at any age or for adults to have more than one or two alcoholic drinks per day. The nicotine from cigarettes speeds up the heart and constricts blood vessels. Alcohol abuse has been associated with increased risk of developing hypertension, as well as many other health problems. Street drugs such as cocaine can have a direct adverse effect on the heart and increase blood pressure.

Medication

If hypertension is moderate or severe, or if mild hypertension does not respond to diet, exercise, and other lifestyle changes, medicines may be prescribed. Doctors today have several different types to choose from, depending upon their patients particular needs.

Diuretic drugs are among the more commonly used. They act to increase the flow of urine and decrease the blood volume. Another group, called beta-blockers, alters the way the nervous system functions in the control of blood pressure. A third group of drugs, called vasodilators (va-zo-DY-layt-orz), act to relax the blood vessels, thereby decreasing the resistance to blood flow. Other types may be prescribed as well.

Prescription drugs for hypertension may have various side effects, depending upon the drug and the person taking it. All antihypertensive drugs may cause dizziness and fainting, however, if the blood pressure is lowered too much. It is extremely important not to stop taking medication once begun without consulting the doctor.

Doctors treating hypertension may wish to have their patients keep track of their blood pressure by taking readings at regular intervals. Devices for home use are available for this purpose.

Can Hypertension Be Prevented?

For teenagers and young adults, who are unlikely to have the condition early in life, hypertension may seem only a remote consideration. However, establishing a healthy lifestyle by keeping fit and trim through exercise and good eating habits, and not smoking, can help prevent health problems such as hypertension from developing later on in life. This is particularly important for people who have a family history of hypertension.

Lastly, it is important for everyone to get their blood pressure checked regularly. Although doing so will not actually prevent hypertension, it can get someone who has the condition into treatment earlier, thereby keeping it under control and lessening the risk of developing such serious health problems as heart attack and stroke.

See also

Diabetes

Heart Disease

Stroke

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hypertension

hypertension High blood pressure; a risk factor for ischaemic disease, stroke, and kidney disease. May be due to increased sensitivity to salt (correctly sensitivity to sodium), and treated by restriction of salt intake, together with drugs; increased intake of fruits and vegetables (as a safe source of potassium) is recommended. See also ‘salt‐free’ diet.

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hypertension

hy·per·ten·sion / ˌhīpərˈtenshən/ • n. Med. abnormally high blood pressure. ∎  a state of great psychological stress.

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hypertension

hypertension Persistent high blood pressure. It can damage blood vessels and may increase the risk of strokes or heart disease. See also hypotension

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hypertension

hypertension See blood pressure.

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hypertension

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natation, nation, negation, notation, nutation, oblation, oration, ovation, potation, relation, rogation, rotation, Sarmatian, sedation, Serbo-Croatian, station, taxation, Thracian, vacation, vexation, vocation, zonation •accretion, Capetian, completion, concretion, deletion, depletion, Diocletian, excretion, Grecian, Helvetian, repletion, Rhodesian, secretion, suppletion, Tahitian, venetian •academician, addition, aesthetician (US esthetician), ambition, audition, beautician, clinician, coition, cosmetician, diagnostician, dialectician, dietitian, Domitian, edition, electrician, emission, fission, fruition, Hermitian, ignition, linguistician, logician, magician, mathematician, Mauritian, mechanician, metaphysician, mission, monition, mortician, munition, musician, obstetrician, omission, optician, paediatrician (US pediatrician), patrician, petition, Phoenician, physician, politician, position, rhetorician, sedition, statistician, suspicion, tactician, technician, theoretician, 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electrocution, elocution, evolution, execution, institution, interlocution, irresolution, Lilliputian, locution, perlocution, persecution, pollution, prosecution, prostitution, restitution, retribution, Rosicrucian, solution, substitution, volution •cushion • resumption • München •pincushion •Belorussian, Prussian, Russian •abduction, conduction, construction, deduction, destruction, eduction, effluxion, induction, instruction, introduction, misconstruction, obstruction, production, reduction, ruction, seduction, suction, underproduction •avulsion, compulsion, convulsion, emulsion, expulsion, impulsion, propulsion, repulsion, revulsion •assumption, consumption, gumption, presumption •luncheon, scuncheon, truncheon •compunction, conjunction, dysfunction, expunction, function, junction, malfunction, multifunction, unction •abruption, corruption, disruption, eruption, interruption •T-junction • liposuction •animadversion, aspersion, assertion, aversion, Cistercian, coercion, conversion, desertion, disconcertion, dispersion, diversion, emersion, excursion, exertion, extroversion, immersion, incursion, insertion, interspersion, introversion, Persian, perversion, submersion, subversion, tertian, version •excerption

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Hypertension

Hypertension

History

Complications

Causes and symptoms

Diagnosis

Treatment

Prognosis

Prevention

Resources

Hypertension is high blood pressure. Blood pressure is the force of blood pushing against the walls of arteries as it flows through them. Arteries are the blood vessels that carry oxygenated blood from the heart to the bodys tissues. According to the U.S. Centers for Disease Control and Prevention (CDC), in 2004, hypertension killed over 2,900 people in the United States; which relates to about 7.8 people per 100,000 in the U.S. population.

As blood flows through arteries it pushes against the inside of the artery walls. The more pressure the blood exerts on the artery walls, the higher the blood pressure will be. The size of small arteries also affects the blood pressure. When the muscular walls of arteries are relaxed, or dilated, the pressure of the blood flowing through them is lower than when the artery walls narrow, or constrict.

Blood pressure is highest when the heart beats to push blood out into the arteries. When the heart relaxes to fill with blood again, the pressure is at its lowest point. Blood pressure when the heart beats is called systolic pressure. Blood pressure when the heart is at rest is called diastolic pressure. When blood pressure is measured, the systolic pressure is stated first and the diastolic pressure second. Blood pressure is measured

in millimeters of mercury (mm Hg). For example, if a persons systolic pressure is 120 and diastolic pressure is 80, it is written as 120/80 mm Hg. The American Heart Association considers blood pressure less than 140 over 90 normal for adults.

Hypertension is a major health problem, especially because it has no symptoms. Many people have hypertension without knowing it. In the United States, about 50 million people age six years and older have high blood pressure. Hypertension is more common in men than women and in people over the age of 65 years than in younger persons. More than half of all Americans over the age of 65 years have hypertension. It is also more common in African-Americans than in white Americans.

History

Attempts to find effective ways to treat hypertension led researchers to uncover the methods by which the body regulates blood pressure; knowledge of that process is still evolving. In 1898, physiologists Robert Adolf Tigerstedt (18531923) and Per Gustaf Bergman (18741955) found that an enzyme produced by the kidneys affected blood pressure. American pathologist Henry Goldblatt (18911977) and colleagues confirmed the role of the kidneys in 1934, producing hypertension in dogs by constricting the kidney arteries. In 1940, Braun-Menendez in Argentina and Irvine Page and Oscar Helmer at the Cleveland Clinic in Ohio found that renin, the kidney enzyme, catalyzed the formation of angiotensin, a very potent vasoconstrictor (a substance that causes blood vessels to contract). In the 1950s, researchers discovered that renin causes the production of angiotensin I, which has little physiological effect but is stimulated by angiotensin converting enzyme to produce the vessel-constricting angiotensin II. In the 1960s, F. Gross and others further found that angiotensin stimulates production of the hormone aldosterone by the adrenal glands, which in turn promotes retention of sodium and water, boosting the fluid content of the circulatory system and, thus, the pressure on blood vessel walls. Angiotensins were also shown to act on the nervous system, stimulating release of the neurotransmitter norepinephrine, which signals the arterioles to constrict. This complex is called the reninangiotensin-aldosterone system. Exactly why the system malfunctions to produce hypertension is not yet known, except in the approximately 10% of cases in which high blood pressure is the result of specific, known physical disorders, particularly of the kidneys and adrenal glands.

Effective drug treatments to control high blood pressure were not developed until after World War II (19391945), although some early attempts at drug treatment were made. French surgeon Mathieu Jaboulay (18601913), in 1900, reported on his drastic approach to alleviate severe hypertension: sympathectomy, or the cutting of the nerves that stimulate blood vessel constriction. Two American doctors took a dietary approach; Frederick Allen promoted salt and water restriction in 1920, and Walter Kempner (19031997) put patients on a no-salt rice diet in the 1940s.

The modern era of drug treatment for hypertension began with the introduction of reserpine in 1953. Reserpine was first derived from the snakeroot plant, Rauwolfia serpentina, long used by medical practitioners in India, both to lower blood pressure and induce relaxation. Rauwolfia was first mentioned in Western medical literature in a 1563 Portuguese work, but it was not studied seriously by Western-trained Indian physicians until 1931. The results of a clinical trial published by Dr. Rustom Jal Vakil (19111974) in 1949 caught the attention of Dr. Robert Wilkins, director of the hypertension clinic at Massachusetts General Hospital. Wilkins confirmed the hypotensive (anti-hypertensive) effect of Rauwolfia in 1952. The active ingredient was soon isolated and named reserpine; it was synthesized in 1956 by Robert Burns Woodward of Harvard University (Massachusetts). Reserpine was the first antihyperten-sive drug to achieve wide clinical use because of its nearly universal effectiveness. (It acts by interfering with transmission of norepinephrine.) It was also widely sold as a tranquilizer.

Other drugs took the place of reserpine as manufacturers and researchers focused their attention on anti-hypertensives beginning in the 1950s. The discovery of the first thiazide diuretic, benzothiadiazine, was reported in 1957 by the drug company Merck, Sharp and Dohme. Thiazide diuretics, which increase excretion of sodium chloride and water by stimulating the flow of urine, are widely used today to lower blood pressure. They may be taken in combination with methyldopa, an antihypertensive introduced in 1963, or with the beta-blockers, a new class of drugs that came on the market in 1964. James Black, senior pharmacologist at Imperial Chemical Industries of Great Britain, was responsible for the development of the first beta blocker, propranolol. American biochemist Raymond Ahlquist had suggested that epinephrine and norepinephrine transmit their signalswhich cause an increase in heart rate and stronger contractions of the heart and blood vesselsto beta receptor sites on the heart muscle. In 1957, Black noted reports of a drug that blocked the stimulating effects of adrenaline on the heart, and set about creating a new chemical compound that would block the effects of epinephrine and norepinephrine at the beta receptor sites. This was accomplished by 1960, with the improved beta-blocker propranolol appearing in 1964. Beta blockers are now widely used to treat both angina and high blood pressure.

Two other antihypertensives were introduced in the 1980s. Calcium channel blockers work by blocking the channel that carries calcium to muscle cells; since calcium is required for contraction of the muscles in artery walls and affects the rate at which the heart beats, lowering calcium levels in muscle also lowers blood pressure. ACE (angiotensin converting enzyme) inhibitors interfere with the effect of an enzyme that stimulates angiotensin I to convert to the powerful vasoconstrictor angiotensin II and that also promotes the destruction of bradykinin, a powerful vasodilator (a substance that promotes the relaxation of blood vessels). Ferreira and his coworkers first found BPFs, factors that intensify the bodys reaction to bradykinin, in the venom of pit vipers in the 1960s. The BPFs inhibited the action of an enzyme that Erdos and associates showed was identical to angiotensin converting enzyme. BPFs were then synthesized, and in 1977 Cushman and his colleagues developed the first orally effective ACE inhibitor, captopril. Recently, it has been discovered that ACE inhibitors also reduce the rate of heart failure and progress of heart disease following heart attack.

Other drug treatments include sympathetic (adrenergic) nervous system blockers, which inhibit the sympathetic nervous system; vasodilators, which lower vascular resistance by dilating the blood vessels; and HMG-CoA reductase inhibitors, which are used with dietary modifications to reduce cholesterol levels. However, drug therapy, which usually includes side effects, is not the only way to treat hypertension. From the 1970s on, doctors have recommended exercise, weight loss, eliminating smoking, stress reduction, and a diet low in sodium, caffeine, alcohol, and cholesterol as a means of lowering blood pressure.

Advances are also being made in discovering the biological roots of hypertension. For example, in 1998 researchers reported that glucocorticoid (a specific group of corticoids, or adrenal cortex steroids) abnormalities may play a role in familial disposition to hypertension. Investigators also identified two oncogenes that may be related to sodium-related hypertension by affecting how sodium is released or retained by sodium channels in the kidneys. Variations of an ACE (angiotensin converting enzyme) gene, which encodes for an enzyme that helps regulate blood volume and controls salt and water balance, have also been linked to hypertension in men but not women.

Complications

Hypertension is serious because people with the condition have a higher risk for heart disease and other medical problems than people with normal blood pressure. Serious complications can be avoided by getting regular blood pressure checks and treating hypertension as soon as it is diagnosed.

If left untreated, hypertension can lead to the following medical conditions:

  • Arteriosclerosis, also called atherosclerosis,
  • Heart attack,
  • Stroke,
  • Enlarged heart, and
  • Kidney damage.

Arteriosclerosis is hardening of the arteries. The walls of arteries have a layer of muscle and elastic tissue that makes them flexible and able to dilate and constrict as blood flows through them. High blood pressure can make the artery walls thicken and harden. When artery walls thicken, the inside of the blood vessel narrows. Cholesterol and fats are more likely to build up on the walls of damaged arteries, making them even narrower. Blood clots can also get trapped in narrowed arteries, blocking the flow of blood.

Arteries narrowed by arteriosclerosis may not deliver enough blood to organs and other tissues. Reduced or blocked blood flow to the heart can cause a heart attack. If an artery to the brain is blocked, a stroke can result.

Hypertension makes the heart work harder to pump blood through the body. The extra workload can make the heart muscle thicken and stretch. When the heart becomes too enlarged it cannot pump enough blood. If the hypertension is not treated, the heart may fail.

The kidneys remove the bodys wastes from the blood. If hypertension thickens the arteries to the kidneys, less waste can be filtered from the blood. As the condition worsens, the kidneys fail and wastes build up in the blood. Dialysis or a kidney transplant are needed when the kidneys fail. About 25% of people who receive kidney dialysis have kidney failure caused by hypertension.

Causes and symptoms

Many different actions or situations can normally raise blood pressure. Physical activity can temporarily raise blood pressure. Stressful situations can make blood pressure go up. When the stress goes away, blood pressure usually returns to normal. These temporary increases in blood pressure are not considered hypertension. A diagnosis of hypertension made only when a person has multiple high blood pressure readings over a period of time.

The cause of hypertension is not known in 90 to 95% of the people who have it. Hypertension without a known cause is called primary or essential hypertension.

When a person has hypertension caused by another medical condition, it is called secondary hypertension. Secondary hypertension can be caused by a number of different illnesses. Many people with kidney disorders have secondary hypertension. The kidneys regulate the balance of salt and water in the body. If the kidneys cannot rid the body of excess salt and water, blood pressure goes up. Kidney infections, a narrowing of the arteries that carry blood to the kidneys, called renal artery stenosis, and other kidney disorders can disturb the salt and water balance.

Cushing syndrome and tumors of the pituitary and adrenal glands often increase levels of the adrenal gland hormones cortisol, adrenalin, and aldosterone, which can cause hypertension. Other conditions that can cause hypertension are blood vessel diseases, thyroid gland disorders, some prescribed drugs, alcoholism, and pregnancy.

Even though the cause of most hypertension is not known, some people have risk factors that give them a greater chance of getting hypertension. Many of these risk factors can be changed to lower the chance of developing hypertension or as part of a treatment program to lower blood pressure.

Risk factors for hypertension include:

  • Age over 60 years,
  • Male gender,
  • Race,
  • Heredity,
  • Salt sensitivity,
  • Obesity,
  • Inactive lifestyle,
  • Heavy alcohol consumption, and
  • Use of oral contraceptives.

Some risk factors for getting hypertension can be changed, while others cannot. Age, male gender, and race are risk factors that a person cannot do anything about. Some people inherit a tendency to get hypertension. People with family members who have hypertension are more likely to develop it than those whose relatives are not hypertensive. A person with these risk factors can avoid or eliminate the other risk factors to lower their chance of developing hypertension.

Diagnosis

Because hypertension does not cause symptoms, it is important to have blood pressure checked regularly. Blood pressure is measured with an instrument called a sphygmomanometer. A cloth-covered rubber cuff is wrapped around the upper arm and inflated. When the cuff is inflated, an artery in the arm is squeezed to momentarily stop the flow of blood. Then, the air is let out of the cuff while a stethoscope placed over the artery is used to detect the sound of the blood spurting back through the artery. This first sound is the systolic pressure, the pressure when the heart beats. The last sound heard as the rest of the air is released is the diastolic pressure, the pressure between heart beats. Both sounds are recorded on the mercury gauge on the sphygmomanometer.

Normal blood pressure is defined by a range of values. Blood pressure lower than 140/90 mm Hg is considered normal. A blood pressure around 120/80 mm Hg is considered the best level to avoid heart disease. A number of factors such as pain, stress, or anxiety can cause a temporary increase in blood pressure. For this reason, hypertension is not diagnosed on one high blood pressure reading. If a blood pressure reading is 140/90 or higher for the first time, the physician will have the person return for another blood pressure check. Diagnosis of hypertension usually is made based on two or more readings after the first visit.

Systolic hypertension of the elderly is common and is diagnosed when the diastolic pressure is normal or low, but the systolic is elevated, e.g., 170/70 mm Hg. This condition usually co-exists with hardening of the arteries (atherosclerosis).

Blood pressure measurements are classified in stages, according to severity:

  • Normal blood pressure: less than 130/85 mm Hg,
  • High normal: 130 to 139/85 to 89 mm Hg,
  • Mild hypertension: 140 to 159/90 to 99 mm Hg,
  • Moderate hypertension: 160 to 179/100 to 109 mm Hg,
  • Severe hypertension: 180 to 209/110 to 119, and
  • Very severe hypertension: 210/120 or higher.

A typical physical examination to evaluate hypertension includes:

  • Medical and family history,
  • Physical examination,
  • Ophthalmoscopy: Examination of the blood vessels in the eye,
  • Chest x-ray,
  • Electrocardiograph (ECG), and
  • Blood and urine tests.

The medical and family history help the physician determine if the patient has any conditions or disorders that might contribute to or cause the hypertension. A family history of hypertension might suggest a genetic predisposition for hypertension.

The physical examination may include several blood pressure readings at different times and in different positions. The physician uses a stethoscope to listen to sounds made by the heart and blood flowing through the arteries. The pulse, reflexes, height, and weight are checked and recorded. Internal organs are palpated, or felt, to determine if they are enlarged.

Because hypertension can cause damage to the blood vessels in the eyes, the eyes may be checked with a instrument called an ophthalmoscope. The physician will look for thickening, narrowing, or hemorrhages in the blood vessels.

A chest x ray can detect an enlarged heart, other vascular (heart) abnormalities, or lung disease.

An electrocardiogram (ECG) measures the electrical activity of the heart. It can detect if the heart muscle is enlarged and if there is damage to the heart muscle from blocked arteries.

Urine and blood tests may be done to evaluate health and to detect the presence of disorders that might cause hypertension.

Treatment

There is no cure for primary hypertension, but blood pressure can almost always be lowered with the correct treatment. The goal of treatment is to lower blood pressure to levels that will prevent heart disease and other complications of hypertension. In secondary hypertension, the disease that is responsible for the hypertension is treated in addition to the hypertension itself. Successful treatment of the underlying disorder may cure the secondary hypertension.

Treatment to lower blood pressure usually includes changes in diet, getting regular exercise, and taking antihypertensive medications. Patients with mild or moderate hypertension who do not have damage to the heart or kidneys may first be treated with lifestyle changes.

Lifestyle changes that may reduce blood pressure by about 5 to 10 mm Hg include:

  • Reducing salt intake,
  • Reducing fat intake,
  • Losing weight,
  • Getting regular exercise,
  • Quitting smoking,
  • Reducing alcohol consumption, and
  • Managing stress.

Patients whose blood pressure remains higher than 139/90 will most likely be advised to take antihypertensive medication. Numerous drugs have been developed to treat hypertension. The choice of medication will depend on the stage of hypertension, side effects, other medical conditions the patient may have, and other medicines the patient is taking.

Patients with mild or moderate hypertension are initially treated with monotherapy, a single antihypertensive medicine. If treatment with a single medicine fails to lower blood pressure enough, a different medicine may be tried or another medicine may be added to the first. Patients with more severe hypertension may initially be given a combination of medicines to control their hypertension. Combining antihypertensive medicines with different types of action often controls blood pressure with smaller doses of each drug than would be needed for monotherapy.

Antihypertensive medicines fall into several classes of drugs:

  • Diuretics,
  • Beta-blockers,
  • Calcium channel blockers,
  • Angiotensin converting enzyme inhibitors (ACE inhibitors),
  • Alpha-blockers,
  • Alpha-beta blockers,
  • Vasodilators,
  • Peripheral acting adrenergic antagonists, and
  • Centrally acting agonists.

Diuretics help the kidneys eliminate excess salt and water from the bodys tissues and the blood. This helps reduce the swelling caused by fluid buildup in the tissues. The reduction of fluid dilates the walls of arteries and lowers blood pressure.

Beta-blockers lower blood pressure by acting on the nervous system to slow the heart rate and reduce the force of the hearts contraction. They are used with caution in patients with heart failure, asthma, diabetes, or circulation problems in the hands and feet.

Calcium channel blockers block the entry of calcium into muscle cells in artery walls. Muscle cells need calcium to constrict, so reducing their calcium keeps them more relaxed and lowers blood pressure.

ACE inhibitors block the production of substances that constrict blood vessels. They also help reduce the build-up of water and salt in the tissues. They are often given to patients with heart failure, kidney disease, or diabetes. ACE inhibitors may be used together with diuretics.

Alpha-blockers act on the nervous system to dilate arteries and reduce the force of the hearts contractions.

Alpha-beta blockers combine the actions of alpha and beta blockers.

Vasodilators act directly on arteries to relax their walls so blood can move more easily through them. They lower blood pressure rapidly and are injected in hypertensive emergencies when patients have dangerously high blood pressure.

Peripheral acting adrenergic antagonists act on the nervous system to relax arteries and reduce the force of the hearts contractions. They usually are prescribed together with a diuretic. Peripheral acting adrenergic antagonists can cause slowed mental function and lethargy.

Centrally acting agonists also act on the nervous system to relax arteries and slow the heart rate. They are usually used with other antihypertensive medicines.

KEY TERMS

Arteries Blood vessels that carry blood to organs and other tissues of the body.

Arteriosclerosis Hardening and thickening of artery walls.

Cushing syndrome A disorder in which too much of the adrenal hormone, cortisol, is produced; it may be caused by a pituitary or adrenal gland tumor.

Diastolic blood pressure Blood pressure when the heart is resting between beats.

Hypertension High blood pressure.

Renal artery stenosis Disorder in which the arteries that supply blood to the kidneys constrict.

Sphygmomanometer An instrument used to measure blood pressure.

Systolic blood pressure Blood pressure when the heart contracts (beats).

Vasodilator Any drug that relaxes blood vessel walls.

Ventricles The two lower chambers of the heart; also the main pumping chambers.

Prognosis

There is no cure for hypertension. However, it can be well controlled with the proper treatment. Therapy with a combination of lifestyle changes and antihypertensive medicines usually can keep blood pressure at levels that will not cause damage to the heart or other organs. The key to avoiding serious complications of hypertension is to detect and treat it before damage occurs. Because antihypertensive medicines control blood pressure, but do not cure it, patients must continue taking the medications to maintain reduced blood pressure levels and avoid complications.

Prevention

Prevention of hypertension centers on avoiding or eliminating known risk factors. Even persons at risk because of age, race, or sex or those who have an inherited risk can lower their chance of developing hypertension.

The risk of developing hypertension can be reduced by making the same changes recommended for treating hypertension.

Resources

BOOKS

Fuster, Valentin, ed. Hursts The Heart. New York: McGraw-Hill, Medical Publications Division, 2004.

Rosendorff, Clive, ed. Essential Cardiology: Principles and Practice. Totowa, NJ: Humana Press, 2005.

Zipes, Douglas, ed. Braunwalds Heart Disease: A Textbook of Cardiovascular Medicine. Philadelphia, PA: W.B. Saunders, 2005.

Toni Rizzo

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Hypertension

Hypertension

Definition

Hypertension is high blood pressure. Blood pressure is the force of blood pushing against the walls of arteries as it flows through them.

Description

As blood flows through arteries it pushes against the inside of the artery walls. The more pressure the blood exerts on the artery walls, the higher the blood pressure will be. The size of small arteries also affects the blood pressure. When the muscular walls of arteries are relaxed, or dilated, the pressure of the blood flowing through them is lower than when the artery walls narrow, or constrict.

Blood pressure is highest when the heart beats to pump blood out into the arteries. Between beats, when the heart relaxes to refill with blood, the pressure drops to its lowest point. The blood pressure peak, when the heart pumps, is called systolic pressure. The blood pressure trough, when the heart is filling, is called diastolic pressure. When blood pressure is measured, the systolic pressure is stated first and the diastolic pressure second. Blood pressure is measured in millimeters of mercury (mm Hg). For example, if a person's systolic pressure is 120 and diastolic pressure is 80, it is written as 120/80 mm Hg. The American Heart Association considers systolic blood pressure less than 140 and diastolic blood pressure less than 90 normal for adults.

Hypertension is a significant public health problem. Since it has no symptoms, many people are unaware that they have hypertension. In the United States, about 50 million people age six and older have high blood pressure. Hypertension occurs more frequently in men than women and in people over the age of 65 than in younger persons. More than half of all Americans over the age of 65 have hypertension. It is also more prevalent in African Americans than in white Americans.

Hypertension is serious because it places patients at higher risk for heart disease and other medical problems than people with normal blood pressure. Serious complications may be prevented by encouraging patients to check their blood pressure regularly, and by treating hypertension once it is diagnosed.

If left untreated, hypertension can lead to the following medical conditions:

  • arteriosclerosis, also called atherosclerosis
  • myocardial infarction (heart attack)
  • cerebrovascular accident (stroke)
  • left ventricular hypertrophy leading to congestive heart failure
  • chronic renal failure (kidney damage)

Arteriosclerosis is hardening of the arteries. The walls of arteries have a layer of muscle and elastic tissue that makes them flexible and able to dilate and constrict as needed. High blood pressure can cause artery walls to thicken and harden. When artery walls thicken, the lumen (hollow center of the blood vessel) narrows. Cholesterol and fatty plaques are more likely to build up on the walls of damaged arteries, further narrowing them. Blood clots can also become trapped in narrowed arteries, blocking the flow of blood.

Arteries narrowed by arteriosclerosis may restrict blood flow to organs and other tissues. Reduced or blocked blood flow to the heart can cause myocardial infarction (a heart attack). Similarly, if an artery to the brain is blocked, a stroke can result.

Hypertension forces the heart muscle to work harder to pump blood through the body. The extra workload can cause the heart muscle to thicken and stretch. When the heart becomes too enlarged, it cannot pump enough blood. If hypertension continues and is not treated, the heart may fail.

The kidneys remove waste from the blood. Chronic hypertension thickens the arteries to the kidneys and impairs renal (kidney) function. As the condition progresses, the kidneys eventually fail and hemodialysis or kidney transplant will be needed. About 25% of people who receive hemodialysis have kidney failure caused by hypertension.

Causes and symptoms

Blood pressure varies in response to physical and emotional stimuli. Many different actions or situations normally raise blood pressure. Physical activity can temporarily raise blood pressure. Emotionally stressful situations also can increase blood pressure. When the stress subsides or disappears, blood pressure usually returns to normal. These temporary increases in blood pressure are not considered hypertension. A diagnosis of hypertension is made only when a patient has multiple high blood pressure readings over a period of time.

For 90-95% of patients with hypertension, the cause is unknown. Hypertension without a known cause is called primary or essential hypertension.

When a patient has hypertension caused by another medical condition, it is considered secondary hypertension. Secondary hypertension may be caused by a variety of disorders. Many patients with kidney diseases have secondary hypertension because the kidneys regulate the balance of salt and water in the body. If the kidneys cannot rid the body of excess salt and water, blood pressure rises. Chronic pyelonephritis (kidney infections), renal artery stenosis, and glomerulonephritis are examples of kidney diseases that may cause secondary hypertension.

Cushing's syndrome and tumors of the pituitary and adrenal glands often increase levels of the adrenal gland hormones—cortisol, adrenaline and aldosterone—which can cause hypertension. Other conditions that may cause secondary hypertension are vasculitis, thyroid disorders, some prescription and over-the-counter medications, alcoholism, and pregnancy.

Although the cause of most hypertension is not known, some individuals have greater risk of developing hypertension. Many lifestyle-associated risk factors may be modified or eliminated to reduce the chance of developing hypertension or to reduce blood pressure in patients with hypertension.

Risk factors for hypertension include:

  • Age; persons over 60 are at greater risk.
  • Gender; males are more often affected.
  • Race; African Americans are more often affected.
  • Heredity; persons with a family history of hypertension are at greater risk.
  • Salt sensitivity.
  • Obesity.
  • Inactive, sedentary lifestyle.
  • Heavy alcohol consumption.
  • Use of oral contraceptives.

Some risk factors for getting hypertension can be changed, while others cannot. Age, gender, heredity, and race are risk factors that cannot be influenced. An individual with any of these non-modifiable risk factors should avoid or eliminate other, controllable risk factors to reduce the chance of developing hypertension.

Diagnosis

Since hypertension is asymptomatic (does not cause symptoms), it is important for patients to have regular blood pressure checks. Conventionally, blood pressure is measured with an instrument called a sphygmomanometer. When the cuff is inflated, an artery in the arm is squeezed to momentarily stop the flow of blood. Then, the air is let out of the cuff while a stethoscope placed over the artery is used to detect the sound of the blood spurting back through the artery. This first sound is the systolic pressure, the pressure when the heart beats. The last sound heard as the air is being released is the diastolic blood pressure.

Normal blood pressure is defined by a range of values. Systolic blood pressure lower than 140 mm Hg and diastolic blood pressure lower than 90 mm Hg is considered normal. A number of factors such as pain, stress, or anxiety can cause a temporary increase in blood pressure. For this reason, hypertension is not diagnosed on the basis of a single elevated blood pressure reading. If a blood pressure reading is 140/90 or higher, the physician or mid-level practitioner (physician assistant or nurse practitioner) will have the patient return for another blood pressure check or instruct the patient to check their blood pressure at home using an inexpensive, automated device. Diagnosis of hypertension usually is made based on two or more readings after the first visit.

Isolated systolic hypertension is common among older adults and is diagnosed when diastolic pressure is normal or low, but the systolic is elevated, e.g., 170/70 mm Hg. This condition usually co-exists with atherosclerosis (hardening of the arteries).

Blood pressure measurements are classified in stages, according to severity:

  • Normal blood pressure: less than 130/85 mm Hg.
  • High normal: 130-139/85-89 mm Hg.
  • Mild hypertension: 140-159/90-99 mm Hg.
  • Moderate hypertension: 160-179/100-109 mm Hg.
  • Severe hypertension: 180-209/110-119 mm Hg.
  • Very severe hypertension: 210/120 mm Hg or higher.

A typical physical examination to evaluate hypertension includes:

  • medical and family history
  • physical examination
  • ophthalmoscopy: examination of the blood vessels in the eye
  • chest x ray
  • electrocardiogram (ECG)
  • blood and urine tests, including electrolytes, creatinine, protein, calcium, random blood sugar, thyroid stimulating hormone (TSH), routine and microscopic urinalysis, and urine for culture and sensitivity

The medical and family history help the physician or mid-level practitioner to determine if the patient has any conditions or disorders that might contribute to or cause the hypertension. A family history of hypertension may suggest a genetic predisposition for hypertension.

The physical exam may include several blood pressure readings at different times and in different postural positions. The physician or mid-level practitioner uses a stethoscope to listen to sounds made by the heart and for abdominal bruits (blood flowing through partially obstructed arteries). The pulse, reflexes, and height and weight are checked and recorded. Internal organs are palpated to determine if they are enlarged.

Since hypertension may cause damage to the blood vessels in the eyes, the eyes may be examined with an ophthalmoscope to detect thickening, narrowing, or hemorrhages in the blood vessels.

A chest x ray can detect an enlarged heart, other vascular abnormalities, or pulmonary (lung) disease.

An electrocardiogram (ECG) measures the electrical activity of the heart. It can detect if the heart muscle is enlarged and if there is damage to the heart muscle from blocked arteries.

Urine and blood tests may be performed to determine whether the hypertension has already caused kidney damage and to detect the presence of disorders that might cause secondary hypertension.

Treatment

There is no cure for primary hypertension, but blood pressure can almost always be lowered with appropriate treatment. The goal of treatment is to lower blood pressure to levels that will prevent heart disease and other complications of hypertension. In secondary hypertension, the underlying disease responsible for the hypertension is treated along with the hypertension itself. Successful treatment of the underlying disorder may entirely eliminate the secondary hypertension.

Treatment to lower blood pressure usually includes changes in diet, regular exercise, and antihypertensive medications. Patients with mild or moderate hypertension who do not have damage to the heart or kidneys may initially be treated with lifestyle changes.

Lifestyle changes that may reduce blood pressure by about 5-10 mm Hg include:

  • Reduce salt intake.
  • Reduce fat intake.
  • Lose weight.
  • Get regular exercise.
  • Quit smoking.
  • Reduce alcohol consumption.
  • Manage stress.

Patients whose blood pressure remains higher than 139/89 will most likely be advised to take antihypertensive medication. Numerous drugs have been developed to treat hypertension. The choice of medication will depend on the stage of hypertension, side effects, other medical conditions the patient may have, and other medicines the patient is taking.

Patients with mild or moderate hypertension are initially treated with monotherapy, a single antihypertensive medicine. If treatment with a single medicine fails to lower blood pressure sufficiently, a different medicine may be tried or another medicine may be added to the first. Patients with more severe hypertension may initially be given a combination of drugs to control hypertension. Combining antihypertensive medicines with different mechanisms of action often controls blood pressure with smaller doses of each drug than would be needed for monotherapy. It is not uncommon to treat a patient with hypertension with three or more different anti-hypertensive drugs.

Antihypertensive medicines include several classes of drugs:

  • diuretics
  • beta-adrenergic blockers
  • calcium channel blockers
  • angiotensin converting enzyme inhibitors (ACE inhibitors)
  • angiotensin receptor antagonists
  • alpha-adrenergic blockers
  • alpha-beta adrenergic blockers
  • vasodilators
  • selective alpha-adrenergic antagonists
  • centrally acting adrenergic agonists

Diuretics, such as hydrochlorthiazide, help the kidneys eliminate excess salt and water, thereby reducing intravascular volume. This results in dilatation of arteries and lower blood pressure.

Beta-adrenergic blockers, such as metoprolol or atenolol, lower blood pressure by blocking the effects of adrenaline thereby slowing the heart rate and reducing the force of the heart's contraction. They are used with caution in patients with heart failure, asthma, diabetes, or peripheral arterial disease.

Calcium channel blockers, such as diltiazem, nifedipine, or verapamil, block the entry of calcium into muscle cells in artery walls. Muscle cells need calcium to contract, so reducing their calcium keeps them more relaxed and the arteries dilated. This action lowers blood pressure.

ACE inhibitors, such as lisinopril or captopril, block the effects of angiotensin converting enzyme, thus reducing the production of aldosterone. They are also used for treating congestive heart failure or diabetic nephropathy. ACE inhibitors may be used together with diuretics.

Angiotensin receptor antagonists, such as losartan or candesartin, block angiotensin II receptors in many tissues, allowing blood vessels to dilate and the kidneys to eliminate excess sodium and water.

Alpha-adrenergic blockers, such as phentolamine, act on the nervous system to dilate arteries and reduce the force of the heart's contractions.

Alpha-beta andrenergic blockers, such as labetlol, combine the actions of alpha and beta blockers.

Vasodilators, such as hydralazine, act directly on arteries to relax their walls so blood can move more easily through them. They lower blood pressure rapidly and are injected in hypertensive emergencies when patients have dangerously high blood pressure.

Selective alpha-adrenergic antagonists, such as prazosin or terazosin, act on the nervous system to relax arteries and reduce the force of the heart's contractions. They usually are prescribed together with a diuretic. Selective alpha-adrenergic antagonists may cause slowed mental function and lethargy.

Centrally acting adrenergic agonists, such as clonidine or methyldopa, also act on the nervous system to relax arteries and slow the heart rate. They are usually used with other antihypertensive medicines.

Health care team roles

The diagnosis of hypertension may be made by a primary care physician, mid-level practitioner, or nurse. Often, hypertension is identified during a routine medical visit or during screening at events such as health fairs. Laboratory technologists perform needed blood work and urinalysis; radiologic technologists conduct any ordered x rays, ECG, or imaging studies. Patients returning for follow-up blood pressure checks may be seen by nurses and may receive nutrition education from dieticians.

Patient education

Nurses, health educators, dieticians, physicians, mid-level practitioners, and other health professionals are involved in educating the community-at-large about the risks associated with untreated hypertension. Screening programs to detect hypertension also aim to identify individuals with hypertension and encourage them to seek treatment.

Since the condition is asymptomatic, many patients mistakenly believe that they can safely stop treating their hypertension. Health professionals should not only emphasize the importance of adherence, but also should educate patients about the long-term health risks and consequences of untreated hypertension.

Prognosis

There is no known cure for hypertension. However, it can be effectively controlled with proper treatment. Therapy with a combination of lifestyle changes and antihypertensive medicines usually can maintain blood pressure at levels that will not cause damage to the heart or other organs. The key to avoiding serious complications of hypertension is to detect and treat it before damage occurs. Because antihypertensive medicines control blood pressure, but do not cure it, patients must continue taking the medications to maintain reduced blood pressure levels and avoid complications.

Prevention

Prevention of hypertension centers on avoiding or eliminating known risk factors. Even persons at risk because of age, race, or gender or those who have an inherited risk can lower their chance of developing hypertension.

The risk of developing hypertension can be reduced by making the same changes recommended for treating hypertension:

  • Reduce salt intake.
  • Reduce fat intake.
  • Lose weight.
  • Get regular exercise.
  • Quit smoking.
  • Reduce alcohol consumption.
  • Manage stress.

KEY TERMS

Arteries— Blood vessels that carry blood to organs and other tissues of the body.

Arteriosclerosis (atherosclerosis)— Hardening and thickening of artery walls.

Cushing's syndrome— A disorder in which too much of the adrenal hormone, cortisol, is produced; it may be caused by a pituitary or adrenal gland tumor.

Diastolic blood pressure— Blood pressure when the heart is resting between beats.

Hypertension— High blood pressure.

Renal artery stenosis— Disorder in which the arteries that supply blood to the kidneys constrict.

Sphygmomanometer— An instrument used to measure blood pressure.

Systolic blood pressure— Blood pressure when the heart contracts (beats).

Vasodilator— Any drug that relaxes blood vessel walls.

Ventricle— One of the two lower chambers of the heart.

Resources

BOOKS

Ahya, Shubhada N., Kellie Flood, and Subramanian Paranjothi. The Washington Manual of Medical Therapeutics, 30th ed. Philadelphia: Lippincott Williams & Wilkins, 2001, pp. 76-85.

Bellenir, Karen, and Peter D. Dresser, eds. Cardiovascular Diseases and Disorders Sourcebook. Detroit: Omnigraphics, 1995.

Texas Heart Institute. Heart Owner's Handbook. New York: John Wiley and Sons, 1996.

PERIODICALS

"Pulmonary Hypertension." American Family Physician (May 1, 2001).

Woods, Anne Dabrow. "Managing Hypertension." Nursing Library (March 1999).

ORGANIZATIONS

American Heart Association. 7272 Greenview Avenue, Dallas, TX 75231-4596. (800) AHS-USA1. 〈http://www.amhrt.org/〉.

National Heart, Lung, and Blood Institute. Information Center. PO Box 30105, Bethesda, MD 20824-0105. (301) 251-1222.

Texas Heart Institute. Heart Information Service, PO Box 20345, Houston, TX 77225-0345. (800) 292-2221.

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Hypertension

Hypertension

Definition

Description

Demographics

Origins

Function

Benefits

Precautions

Risks

Research and general acceptance

Resources

Definition

Hypertension is the medical term for high blood pressure. Each time the heartbeats, it forces blood into the arteries. Blood pressure is the force created when blood moving through the body’s arteries pushes against the artery walls. Arteries are the blood vessels that carry blood from the heart throughout the body. Though many factors can cause hypertension, diet plays a major role in controlling high blood pressure.

Blood pressure

Normal< 120/80
Prehypertension120-129/80-84
Hypertension130-139/85-89
Stage 1> 140/90
Stage 2140-180/90-110

source:National Heart, Lung and Blood Institute, National Institutes of Health, U.S. Department of Health and Human Services.

(Illustration by GGS Information Services/Thomson Gale.).

Description

Blood pressure is measured as it pushes against the inside of artery walls. The low blood pressure point, when the heart is at rest, is called diastolic pressure. Blood pressure is measured in millimeters of mercury (mm Hg) and the systolic reading is read and recorded first, with the diastolic pressure reading following. For example, if a person’s high, or systolic, pressure is 118 and his or her low pressure is 70, the blood pressure would be announced and recorded as 118/70 mm Hg, or “118 over 70.” This would fall into the normal range, according to the American Heart Association (AHA). The association’s recommended blood pressure levels are less than 120 mm Hg for systolic pressure and less than 80 mm Hg for diastolic pressure.

If a person’s systolic pressure rises above 120 mm Hg and up to 139 mm Hg or diastolic pressure rises to a level of 80-80 mm Hg, the person is considered “prehypertensive.” High blood pressure is defined as a reading above 140 mm Hg systolic or 90 mm Hg diastolic. If the systolic raises above 160 mm Hg or the diastolic goes above 100, the person is considered in the Stage 2 high blood pressure range. High blood pressure can have serious health consequences. In particular, it is a major risk factor for stroke and heart attack.

Diet is an important part of controlling high blood pressure. A diet to control hypertension consists of eating fewer calories, reducing salt, eating more potassium, reducing alcohol consumption and eating lots of fruits and vegetables. Eating fewer calories and reducing fat, especially saturated fat, will help keep weight down. And lowering weight to normal range usually helps lower blood pressure. Salt is well known as a problem for people with high blood pressure. Most diets for hypertension includes decreasing use of table salt and sodium in processed foods.

KEY TERMS

Monounsaturated fat— Fats that contain one double or triple bond per molecule. Though these fats still have many of calories, they can help lower blood cholesterol if used in place of saturated fats. Examples of monounsaturated fats are canola oil and olive oil.

Triglyceride— A storage form of energy that often is used to measure fat ingestion and metabolism, and resulting risk for heart disease.

Potassium can do the opposite of sodium; it can help lower blood pressure. Potassium is best found in foods rather than in supplements. Foods rich in potassium include apricots, avocados, bananas, melons, kiwis, lima beans, oranges, prunes, spinach, tomatoes, squash, potatoes, and whole grains. Fresh fruits and vegetables are low in sodium, rich in potassium and fiber , as well as vitamins and minerals .

Plant proteins also may help lower blood pressure; the best sources of proteins come from soy products, beans, peas, lentils, peanuts, brown rice, broccoli, and potatoes. A hypertension diet may be supplied by a physician, a center that specializes in heart healthy lifestyles, a nutritionist, or be based on the “DASH” or Dietary Approaches to Stop Hypertension eating plan.

The DASH diet emphasizes lean meats, fish, chicken, low-fat dairy, fruits, vegetables, whole grains, legumes, nuts, and seeds. Vegetarian diets also may help keep blood pressure low. The OmniHeart diet is similar to DASH but may emphasize a particular food group, such as protein , more. Other lifestyle changes, such as quitting cigarette smoking and increasing activity by regularly exercising also may be recommended.

Demographics

Nearly one in three adults, or about 65 million people, in the United States have high blood pressure. Of these, about one-third do not know they have the disease because there are no real symptoms. The American Heart Association reports that in 2002, high blood pressure killed more than 49,000 Americans and was listed as a primary or contributing cause of death in more than 261,000 deaths in the United States. Blacks get high blood pressure more often than whites. Men are more likely to develop the disease between age 35 and 55, while women are more at risk for hypertension after menopause. In 2003, a report found that high blood pressure incidence was even rising among children and was most likely due to the increased number of overweight and obese children and adolescents.

Origins

For years, physicians have known that controlling the amount of salt one eats could help control hypertension. But this can be difficult, since much of the sodium people eat today comes from prepared and pre-packaged foods. Other dietary factors also contribute to high blood pressure. In the 1990s, scientists from the National Heart, Lung, and Blood Institute (NHLBI) conducted key studies to look at the effects of diet on blood pressure. These trials, called “DASH”, showed that an eating plan low in saturated fat, cholesterol and total fat, but high in fruits, vegetables and low-fat dairy foods helped lower blood pressure. DASH trials also followed the effects of a reduced sodium diet on blood pressure. As a result, a comprehensive eating plan was developed with specific suggestions from each food group.

The American Heart Association revised its dietary guidelines in 2000 to build upon the Step 1 Diet, also created by the NHLBI to reduce risk of cardiovascular disease. Later research found that eating fiber could lower blood pressure. In 2006, scientists also recommended that as long as people were on a healthy diet, replacing some of the carbohydrates recommended in diets such as DASH, with proteins and monounsaturated fats can further lower blood pressure.

Function

High blood pressure cannot be cured and is a condition that lasts a lifetime. People with hypertension must work throughout their lives to control their blood pressure and keep it within normal ranges. Many will do so with careful monitoring of blood pressure and a combination of lifestyle and diet changes, as well as possible use of medications.

A hallmark of controlling high blood pressure is to eat foods rich with potassium and avoid foods high in sodium. Another important component of controlling blood pressure is reducing saturated fat intake. Diets like the DASH diet encourage eating more servings of fresh fruits and vegetables, which are naturally low in sodium. They also encourage keeping a check on total calories, fat, carbohydrates, and eating a balanced diet. Together, these diet strategies help keep weight and the balance of sodium and other of the body’s minerals in balance.

Since manufacturers add sodium to preserve canned fish and poultry, choosing fresh fish and poultry instead can make a big difference in the level of sodium in the diet. Alternatives to canned and instant products include Fresh vegetables and pastas and rice.

Benefits

Not everyone is sensitive to salt; some people have high blood pressure for other reasons such as heredity. But it is estimated that about one-half of people with high blood pressure are “salt-sensitive”. When they eat excessive amounts of salt, their blood pressure rises. Overweight and obesity are other factors affecting blood pressure control; therefore, developing dietary and lifestyle habits aimed at maintaining or losing weight are encouraged. Closely following a diet such as DASH or one prescribed by a physician to keep weight in the normal range will help control blood pressure. In addition to controlling blood pressure, people who follow eating plans that consist of controlled portions, balanced intake from all food groups, and reduced sodium will enjoy other heart-healthy benefits, such as lower cholesterol.

Precautions

Eating plans such as DASH or those suggested by a physician must be followed carefully in order to work. Learning how to read labels and to recognize hidden salt in prepared dishes is as important as pushing away the saltshaker at meals. People who begin the DASH eating plan may want to gradually work up to the increased amount of fiber to prevent bloating and potential diarrhea. People with kidney trouble or heart failure should talk with their physicians before starting a diet that boosts potassium.

A diet for hypertension helps prevent high blood pressure or is one tool to control blood pressure. Diet is not a substitute for prescribed medications, so patients should never stop taking medicines prescribed for high blood pressure without checking with their physicians.

Risks

It is important to involve a physician or registered dietitian in diet planning for high blood pressure and to check the advice of credible organizations such as the American Heart Association, the American Dietetic Association, or the National Heart, Lung, and Blood Institute for information on diets recommended by those other than physicians and health care providers.

QUESTIONS TO ASK YOUR DOCTOR

  • How do I know what diet is best for my individual condition?
  • What’s my daily sodium limit?
  • What foods should I avoid?
  • What foods should I choose more often?

People with high blood pressure should not rely on “fad” diets for quick weight or blood pressure fixes.

Research and general acceptance

In a clinical trial the DASH diet lowered systolic blood pressure for patients with high blood pressure by an average of 11 mm Hg and diastolic blood pressure by an average of 5.5 mm Hg. A review of research also shows that patients with high blood pressure who lost 3% to 9% of their body weight experienced a drop of 3 mm Hg in both systolic and diastolic blood pressure measurements.

Research shows that decreased use of sodium helps lower blood pressure. A review of 17 clinical trials showed that people with hypertension who ate a reduced-sodium diet had reductions of 5 mm Hg in systolic blood pressure and 3 mm Hg in diastolic blood pressure. Research also has shown a link between increased sodium intake and obesity in the United States. Reducing alcohol consumption by nearly two-thirds resulted in improvements of between 2.5mm Hg and 4 mm Hg in blood pressure. Research has shown that vegetarians in industrialized countries generally have lower blood pressures, but in clinical trials, the vegetarian diets reduced systolic blood pressure but had no real effect on diastolic blood pressure.

Resources

BOOKS

Heller, Marla. The DASH Diet. Amidon Press, 2005.

ORGANIZATIONS

American Heart Association. 7272 Greenville Ave., Dallas,.

TX 75231. (800) 242-8721. http://www.americanheart.org>

National Heart, Lung, and Blood Institute. P.O. Box 30105, Bethesda, MD 20284. (301) 592-8573. <http://www.nhlbi.nih.gov>

Teresa G. Odle

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Hypertension

Hypertension

Definition

Hypertension, also called high blood pressure , occurs when the pressure of blood against artery walls as it flows throughout the body is higher than normal. Prolonged high blood pressure can seriously damage not only blood vessels but the heart and other organs.

Description

Hypertension is not technically a disease, but is an indication that something is wrong within the circulatory system, which includes the heart and the blood vessels. Normally, when the heart beats, blood is pumped throughout the body by way of an intricate network of blood vessels. The arteries take blood to the capillaries that nourish the cells, and the veins return the blood to the heart, where it is oxygenated by the lungs and then pumped from the heart again. When something constricts the arterial walls, then pressure within the artery is increased. This results in a high blood pressure reading.

Blood pressure is measured with a stethoscope and a sphygmomanometer, which consists of a blood

Percentage of people in the United States age 65 and over who reported having hypertension, by sex and by race, 2005–2006
Sex Percent
Data is based on a 2-year average from 2005–2006.
source: National Health Interview Survey, National Center for
Health Statistics, Centers for Disease Control and Prevention,
U.S. Department of Health and Human Services
(Illustration by GGS Information Services. Cengage Learning,
Gale)
Men52.0%
Women54.3%
Total 53.3%
Race Percent
White51.3%
Black70.4%
Hispanic or Latino53.8%

pressure cuff that is place around the upper arm and a measuring device. A healthcare provider will pump up the blood pressure cuff until it is tight around the arm and will listen to the flow of the blood within the artery. Blood pressure is recorded using two numbers, one on the top and one the bottom. Systolic pressure occurs when the heart beats. This is when the heart is working and is the top number in a blood pressure reading. The diastolic pressure, or the bottom number, is when the heart relaxes. Until 2003, normal blood pressure was considered under 140/90. The National Heart, Lung, and Blood Institute (NHLBI) lowered those guidelines to under 120/80 and created a new category of hypertension called prehypertension.

High blood pressure can lead to serious complications, including stroke, heart attack, heart disease , or kidney damage. Since hypertension makes the heart work harder, the muscles of that organ can become stretched or thickened. This is a condition called an enlarged heart. Though one might think that a stronger muscle would work better, in the case of the heart, an enlarged heat means that the muscle itself has become weaker. This can lead to heart failure.

Arteries can become blocked due to clots or the build up of plaque, causing blood flow to narrow to vital organs. This causes stroke and heart attack.

The aging process can sometimes cause arteriosclerosis or hardening of the arteries, which can make pumping blood throughout the body much more difficult, creating high blood pressure. This also can limit vital nutrients and oxygen to organs in the body. The brain is especially susceptible to inadequate blood flow.

When the arteries to the kidneys become narrowed, the kidneys filter less blood, and wastes can build up. The kidneys can fail, resulting in the need for dialysis or a kidney transplant. Nearly a fourth of those on kidney dialysis have kidney failure because of hypertension.

Because blood vessels are also working hard, bulges or aneurysms can form. These become weakened places that can burst, which can cause stroke, disability, and death . Aneurysms are commonly found in the aorta, the main artery leading away from the heart, as well as in the brain, the intestines, and the legs.

Hypertension can also affect the eyes by blocking veins in the retina, causing aneurysms in and around the eye, and even swelling the base of the optic nerve. These changes can impair vision and even cause blindness.

Types of hypertension

With the new blood pressure guidelines by the NHLBI in 2003, hypertension has been categorized differently.

Prehypertension is a blood pressure reading above 120/80 but under 140/90. This type of high blood pressure increases the risk of developing hypertension later in life. It is usually treated with lifestyle changes. However, if a patient has diabetes or kidney disease, the doctor may need to treat this type of hypertension with medication.

Primary hypertension occurs when the blood pressure reading is 140/90 or above. This type of high blood pressure is also called essential hypertension or idiopathic hypertension. It has no known cause and occurs in 90 percent of high blood pressure patients. There are two stages of this condition. Stage I has blood pressure that ranges from 140/90 to under 160/100. Stage II has readings over 160/100.

Secondary hypertension also has a blood pressure reading of 140/90 or above. This type of high blood pressure is due to an underlying medical condition.

Isolated systolic hypertension is a type of high blood pressure that is concerned with high systolic pressure, even though the diastolic pressure can be within normal levels. Diastolic pressure increases with age until about 50, and then it levels off or even decreases. Systolic pressure increases with age due to other circulatory conditions such as arteriosclerosis or heart problems. Isolated systolic hypertension is the most common form of hypertension for older adults, with nearly 65 percent of high blood pressure patients over 60 reporting having this type. It is also the least likely of all types of hypertension to be treated well. The NHLBI has recommended that systolic blood pressure be the key criterion for diagnosing hypertension in older adults.

White coat hypertension is an increase in blood pressure due to becoming stressed in the doctor's office. Usually, patients with this condition have normal readings when their blood pressure is taken in other settings. Many doctors who suspect a patient of having white coat hypertension will suggest that a patient take blood pressure readings at home with a home blood pressure monitor and report the findings to the doctor.

Risk factors

There are some risk factors that pre-dispose some patients to having hypertension. Some of these factors reflect lifestyle choices and therefore can be changed, thus reducing the risk of developing hypertension. Others cannot. Age, gender, race, and having a family history of high blood pressure are examples of factors that cannot be changed. The risk of developing hypertension increases with age. Men have a greater chance of developing high blood pressure before age 55, and more women have it after menopause . Hypertension tends to run in families, and African Americans have a greater risk of developing it.

Demographics

Nearly 73 million American adults have hypertension, and half of them are women. More than 40 percent of African Americans have high blood pressure, and they have it at an earlier age and with more severity than other ethnic groups. Almost half of all people over age 50 have hypertension. Moreover, almost two-thirds of Americans with high blood pressure do not have the condition under adequate control. Women diagnosed with pre-hypertension have a 100 percent increase in risk of developing hypertension, whereas men with the condition only have a 45 percent increase. In 2003, a study revealed a rise in the incidence of high blood pressure among children and teenagers due to increased obesity rates.

Causes and symptoms

Causes

Blood pressure can vary throughout the day. It can also increase with physical activity or stress . Patients may also have elevated blood pressure due to taking cold medications containing pseudoephedrin or nonsteroid anti-inflammatory drugs such as aspirin or ibuprofen. In most cases, blood pressure returns to normal when the activity or medications are stopped. Pregnancy can also elevate blood pressure and should be monitored since it can lead to pre-eclamsia, a condition that can be dangerous to mother and baby. In most cases, hypertension in pregnancy is temporary.

Sustained high blood pressure, however, often has no known cause. Nevertheless, patients with secondary hypertensionmayhave it because of a numberof medical conditions, including kidney disease, thyroid disorders, diseases or tumors of the adrenal gland, Cushing's syndrome (a condition where there is too much corticosteroid hormone in the blood), narrowing of the arteries, or sleep apnea. The underlying condition must be treated in addition to hypertension.

Symptoms

Called the silent killer, hypertension often has no symptoms. Some patients, however, may report headache, blurred vision, nosebleeds, dizziness , shortness of breath, drowsiness, confusion, or even numbness or tingling in the hands or feet. The only way hypertension is diagnosed is by checking blood pressure with a sphygmomanometer.

Diagnosis

Hypertension is usually not diagnosed by one blood pressure reading since other factors can temporarily raise blood pressure, such as anxiety or too much caffeine . Doctors will usually take blood pressure readings over many days or ask the patient to use a blood pressure monitor at home and record the readings, making sure to check blood pressure at the same time each day. Sometimes, doctors will take two or three blood pressure readings during an office visit.

If the initial reading is quite high, for example it is 180/110, or if there are symptoms of an underlying disease that could produce secondary hypertension, the doctor may treat hypertension immediately. Generally, a high blood pressure reading over 160/100 should be treated and checked again within two weeks. Those readings between 140/90 and 159/99 should be rechecked within a month, and prehypertensive patients can be monitored every six months. A normal reading only requires a yearly recheck.

In order to take a proper blood pressure reading, the patient should avoid tobacco and caffeine a half hour before having blood pressure taken and should sit quietly for five minutes before the test. The patient should sit in a chair with both feet on the floor, and the arm that is used should be supported at heart level. Some healthcare providers will ask the patient to rest the arm on a desk or table. Often the patient is asked to wear short sleeves.

Some patients may have upper arms that are bigger than the standard blood pressure cuff. In that case, the healthcare provider may use a larger cuff. Some patients may have a slightly lower reading with a larger cuff.

The doctor will also take a thorough family history, asking questions about chest pain , kidney disease, diabetes, or thyroid disease. The patient will be asked about family members who have hypertension or heart disease.

A physical exam usually follows the medical history. Sometimes, the doctor will listen to blood flow sounds with a stethoscope not only in the chest but in the neck, abdomen, or groin to see if there are blocked arteries. The doctor will also examine the small blood vessels in the back of the eyes to look for damage from undiagnosed high blood pressure.

In many cases, other tests are not required unless the patient has other factors that warrant further study. The doctor may order blood tests, an electrocardiogram, or even a chest x ray .

Treatment

Treating hypertension can reduce a patient's risk of having a stroke by 38 percent or a heart attack by 27 percent. If there is an underlying cause of hypertension, treating that condition will reduce blood pressure. Sometimes the doctor will recommend hypertension medication in addition to the medications for the underlying condition.

For patients with primary hypertension, the doctor usually recommends a combination of lifestyle changes and medication. Lifestyle changes include eating a healthy diet , reducing salt, and quitting smoking . Patients also are urged to get enough sleep and to manage stress through a variety of techniques including deep breathing and meditation.

Many people with hypertension may also be overweight, causing the heart to work harder. Even a moderate reduction of ten pounds can reduce blood pressure. Patients are also encouraged to exercise at least 30 minutes every day. NHLBI suggests that exercise does not need to be sport-oriented, but may include walking and household chores, such as washing the car, gardening, raking leaves, washing windows, or even pushing a baby stroller.

Patients with prehypertension are educated about their risk of developing primary hypertension. Lifestyle changes are encouraged, but no medication is usually given, though some doctors may do so.

Medications

Hypertension medications will not cure the condition but will help patients keep their blood pressure readings within normal levels. Coupled with lifestyle changes, many patients may reduce the amount of high blood pressure medications they need.

There are nine types of medications used to treat hypertension. Different types work on the mechanisms of hypertension in different ways. In initial treatment, doctors may need to try different medications or different combinations of medications for each patient. Sometimes, that results in smaller doses of each medication when combined than would be needed with only one type of drug. Additionally, each of these medications may cause unpleasant side effects. The doctor may try a few different drugs before finding the one that a patient can tolerate.

Diuetics are sometimes called water pills because they increase the kidney's ability to flush excess water and sodium from the body. Having less fluid to carry, the arteries have less pressure within them. Diuretics are the first drug of choice in the treatment of hypertension and often are combined with other drugs. One of the most common diuretics is hydrocholorothiazide. Diuretics increase the frequency of urination and can flush potassium from the body. Patients taking these drugs may need to monitor their potassium levels and eat foods rich in potassium or take a potassium supplement.

Approved medications used to treat high blood pressure
source: Food and Drug Administration, U.S. Department of
Health and Human Services
(Illustration by GGS Information Services. Cengage Learning,
Gale)
  • Diuretics, or “water pills,” which help the kidneys flush extra water and
    salt from your body and decrease blood volume
  • Drugs that block the effects of angiotensin (a substance in the body
    that constricts blood vessels) reduce blood pressure by relaxing blood
    vessels, including:
    • Angiotensin converting enzyme (ACE) inhibitors
    • Angiotensin II receptor blockers (ARBs)
    • Beta blockers, which also cause the heart to beat with less force
  • Drugs that directly relax the blood vessels, including:
    • Calcium channel blockers (CCBs)
    • Other direct dilators (relaxers) of blood vessels
    • Alpha blockers, which reduce nerve impulses that tighten blood
      vessels
    • Nervous system inhibitors, which control nerve impulses from the
      brain to relax blood vessels
Many people with high blood pressure may need more than one
medication to reach their goal blood pressure. Your health care provider
can tell you if you should be on medication and, if so, which drug(s) may
be best for you.

Beta-blockers reduce nerve impulses to the arteries and the heart, causing the heart to work less and beat slower. Blood pressure is reduced because the heart is pumping less blood through the arteries.

Calcium channel blockers (CCBs) stop calcium from entering the arteries and the heart. One type of CCB slows the heart and opens up the arteries. Newer CCBs only dilate the arteries but have no effect on how hard the heart works.

Angiotensin converting enzyme inhibitors (ACE inhibitors) inhibit angiotensin II, a hormone that causes arteries to narrow. This medication allows the arteries to relax, thus reducing blood pressure. ACE inhibitors are often used in combination with diuretics. They also can raise potassium levels and can affect kidney function.

Angiotensin antagonists or angiotensin II receptor blockers (ARBS) are similar to ACE inhibitors because they stop the production of angiotensin II, but these drugs also widen the arteries. ARBS have few side effects.

Alpha-blockers reduce nerve impulses that cause the arteries to constrict. The blood flows freely and blood pressure goes down.

Alpha-beta blockers are combined drugs, slowing the heart and reducing the nerve impulses to constrict the arteries.

Vasodilators relax the muscles in the blood vessel walls, opening up the arteries allowing blood to flood.

Peripheral acting adrenergic antagonists work on the nervous system to relax the muscles of the artery walls and slow the heart. They often are used with diuretics. These drugs can cause lethargy and slowed mental functioning.

Nervous system inhibitors control nerve impulses from the brain that allow the arteries to relax.

Centrally acting agonists work directly on the brain to reduce blood pressure. They can often cause depression or drowsiness.

Alternative treatment

Herbal medicine has been helpful for some patients. However, these substances should be used with caution and under the direction of a qualified herbalist since even small doses may be potentially dangerous. Among the herbs recommended for hypertension are Coleus forshohlii, hawthorne, mistletoe, and rauwolfia.

Nutrition/Dietetic concerns

Dietary changes can help manage hypertension. The Dietary Approaches to Stop Hypertension, or DASH, diet has been highly recommended because it offers a well-balanced plan that is low in fat, cholesterol, red meat, and sugar. It is also low in salt. Patient should eat a healthy diet low in saturated fat and cholesterol and rich in whole grains, fruits, vegetables, and low-fat dairy products. Protein should come from lean meats, poultry, and fish.

A Harvard study in 2007 found that eating low-fat dairy products and other foods rich in calcium and vitamin D helped reduce hypertension in women aged 45 and older. Additionally, the NHLBI also recommends increasing potassium intake to 4,600 mg. a day.

Salt has been a factor in high blood pressure because it increases the volume of the blood flowing through the arteries in the body. Reducing the amount of salt you eat can reduce blood volume. Most salt comes from processed foods, therefore patients need to read food labels and avoid fast foods that are high in salt. Sodium should be limited to between 1,500 mg to 2,400 mg a day. That is three-fourths of a teaspoon to about a teaspoon and a fourth of salt. Table salt can be replaced with herbs and spices.

Some doctors may recommend that patients with hypertension reduce the amount of caffeine in their diets. This includes not only coffee and tea, but chocolate and carbonated drinks.

KEY TERMS

Aneurysm —A bulge in an artery.

Cushing's syndrome —A condition where there is too much corticosteroid hormone in the blood, which can cause hypertension.

Diastolic pressure —The pressure on the arteries when the heart relaxes.

Diuetics —A class of blood pressure medication, sometimes called water pills, that increase the kidney's ability to flush excess water and sodium from the bloodstream.

Pre-eclamsia —A dangerous condition in pregnancy, involving high blood pressure and protein in the urine.

Sphygmomanometer —An instrument used to measure blood pressure.

Systolic pressure —The pressure on the arteries when the heart beats.

In addition, patients are asked to limit the amount of alcohol they drink. A man should have no more than two drinks a day, and a woman should only have one.

Prognosis

There is no cure for hypertension, though it can be managed and serious complications can be avoided. Many times, weight loss and exercise can reduce the amount of medication that a patient needs, and in some cases moderate hypertension may be reversed.

Prevention

Hypertension can be avoided by quitting smoking, eating a proper diet, exercising, maintaining a proper weight, using less salt, drinking in moderation, and managing stress. For some individuals with family histories of high blood pressure, prevention may not be possible. Nevertheless, the onset of hypertension may be delayed or the severity of the disorder may be lessened through lifestyle changes and/or medication.

Caregiver concerns

The healthcare provider will need to educate patients about hypertension and what patients can do to manage this disease. Patients may need to consult a dietician to help them develop a healthy eating plan to lose weight or eliminate salt from their diets. Patients may need encouragement or creative ways to exercise more.

Importantly, careful monitoring of medication is essential, looking for side effects and checking kidney function and potassium levels. With elderly patients, the healthcare provider may need to suggest techniques for remembering to take medications every day at the same time of day. This may necessitate enlisting loved ones into reminding these patients.

Resources

PERIODICALS

“Diagnosing hypertension.” Hypertension (Harvard Special Health Report) (2007):21.

“Dietary approaches to stop hypertension (The DASH Diet) (Cardiology Advisor 2007).” Clinical Reference Systems (May 2007).

“Halting hypertension with a healthy diet.” Harvard Health commentaries (August 2006).

“High blood pressure: Common, commonly uncontrolled, and dangerous.” Staying Healthy from the Faculty of the Harvard Medical School (August 2006).

“High blood pressure: Secondary hypertension (Adult Health Advisor 2007).” Clinical Reference System (May 2007).

“How low should your blood pressure be?.” Harvard health commentaries (January 2007).

“Hypertension.” CareNotes (May 2007).

Wang, Lu; Manson, JoAnne E.; Buring, Julie E; Lee, I-Min; and Sesso, Howard D. “Dietary intake of dairy products, calcium, and vitamin D and the risk of hypertension in middle-aged and older women.” Hypertension (February 2008).

OTHER

NIH Senior Health. http://www.nihseniorhealth.gov.

ORGANIZATIONS

American Heart Association National Center, 7272 Greenville Avenue, Dallas, Texas, 75231-4596, 800 242-8721, http://www.americanheart.org.

American Society of Hypertension, 148 Madison Avenue, Fifth Floor, New York, New York, 10016, 212-696 9099, 212-696-0711, http://www.ash-us.org.

National Heart, Lung, and Blood Institute (NHLBI), PO Box 30105, Bethesda, Maryland, 20824-0105, 301-592 73, http://www.nhlbi.nih.gov.

National Institute on Aging (NIA), 31 Center Drive, MSC 2292, Building 31, Room 5C27, Bethesda, Maryland, 20892, 301-496-1752, 301-496-1072, http://www.nia.nih.gov.

Janie F. Franz

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Hypertension

Hypertension

Hypertension is high blood pressure . Blood pressure is the force of blood pushing against the walls of arteries as it flows through them. Arteries are the blood vessels that carry oxygenated blood from the heart to the body's tissues.

As blood flows through arteries it pushes against the inside of the artery walls. The more pressure the blood exerts on the artery walls, the higher the blood pressure will be. The size of small arteries also affects the blood pressure. When the muscular walls of arteries are relaxed, or dilated, the pressure of the blood flowing through them is lower than when the artery walls narrow, or constrict.

Blood pressure is highest when the heart beats to push blood out into the arteries. When the heart relaxes to fill with blood again, the pressure is at its lowest point. Blood pressure when the heart beats is called systolic pressure. Blood pressure when the heart is at rest is called diastolic pressure. When blood pressure is measured, the systolic pressure is stated first and the diastolic pressure second. Blood pressure is measured in millimeters of mercury (mm Hg). For example, if a person's systolic pressure is 120 and diastolic pressure is 80, it is written as 120/80 mm Hg. The American Heart Association considers blood pressure less than 140 over 90 normal for adults.

Hypertension is a major health problem, especially because it has no symptoms. Many people have hypertension without knowing it. In the United States, about 50 million people age six and older have high blood pressure. Hypertension is more common in men than women and in people over the age of 65 than in younger persons. More than half of all Americans over the age of 65 have hypertension. It is also more common in African-Americans than in white Americans.

Hypertension is serious because people with the condition have a higher risk for heart disease and other medical problems than people with normal blood pressure. Serious complications can be avoided by getting regular blood pressure checks and treating hypertension as soon as it is diagnosed.

If left untreated, hypertension can lead to the following medical conditions:

  • arteriosclerosis , also called atherosclerosis
  • heart attack
  • stroke
  • enlarged heart
  • kidney damage

Arteriosclerosis is hardening of the arteries. The walls of arteries have a layer of muscle and elastic tissue that makes them flexible and able to dilate and constrict as blood flows through them. High blood pressure can make the artery walls thicken and harden. When artery walls thicken, the inside of the blood vessel narrows. Cholesterol and fats are more likely to build up on the walls of damaged arteries, making them even narrower. Blood clots can also get trapped in narrowed arteries, blocking the flow of blood.

Arteries narrowed by arteriosclerosis may not deliver enough blood to organs and other tissues. Reduced or blocked blood flow to the heart can cause a heart attack. If an artery to the brain is blocked, a stroke can result.

Hypertension makes the heart work harder to pump blood through the body. The extra workload can make the heart muscle thicken and stretch. When the heart becomes too enlarged it cannot pump enough blood. If the hypertension is not treated, the heart may fail.

The kidneys remove the body's wastes from the blood. If hypertension thickens the arteries to the kidneys, less waste can be filtered from the blood. As the condition worsens, the kidneys fail and wastes build up in the blood. Dialysis or a kidney transplant are needed when the kidneys fail. About 25% of people who receive kidney dialysis have kidney failure caused by hypertension.


Causes and symptoms

Many different actions or situations can normally raise blood pressure. Physical activity can temporarily raise blood pressure. Stressful situations can make blood pressure go up. When the stress goes away, blood pressure usually returns to normal. These temporary increases in blood pressure are not considered hypertension. A diagnosis of hypertension made only when a person has multiple high blood pressure readings over a period of time.

The cause of hypertension is not known in 90-95% of the people who have it. Hypertension without a known cause is called primary or essential hypertension.

When a person has hypertension caused by another medical condition, it is called secondary hypertension. Secondary hypertension can be caused by a number of different illnesses. Many people with kidney disorders have secondary hypertension. The kidneys regulate the balance of salt and water in the body. If the kidneys cannot

rid the body of excess salt and water, blood pressure goes up. Kidney infections, a narrowing of the arteries that carry blood to the kidneys, called renal artery stenosis, and other kidney disorders can disturb the salt and water balance.

Cushing syndrome and tumors of the pituitary and adrenal glands often increase levels of the adrenal gland hormones cortisol, adrenalin and aldosterone, which can cause hypertension. Other conditions that can cause hypertension are blood vessel diseases, thyroid gland disorders, some prescribed drugs, alcoholism, and pregnancy.

Even though the cause of most hypertension is not known, some people have risk factors that give them a greater chance of getting hypertension. Many of these risk factors can be changed to lower the chance of developing hypertension or as part of a treatment program to lower blood pressure.

Risk factors for hypertension include:

  • age over 60
  • male sex
  • race
  • heredity
  • salt sensitivity
  • obesity
  • inactive lifestyle
  • heavy alcohol consumption
  • use of oral contraceptives

Some risk factors for getting hypertension can be changed, while others cannot. Age, male sex, and race are risk factors that a person cannot do anything about. Some people inherit a tendency to get hypertension. People with family members who have hypertension are more likely to develop it than those whose relatives are not hypertensive. A person with these risk factors can avoid or eliminate the other risk factors to lower their chance of developing hypertension.


Diagnosis

Because hypertension does not cause symptoms, it is important to have blood pressure checked regularly. Blood pressure is measured with an instrument called a sphygmomanometer. A cloth-covered rubber cuff is wrapped around the upper arm and inflated. When the cuff is inflated, an artery in the arm is squeezed to momentarily stop the flow of blood. Then, the air is let out of the cuff while a stethoscope placed over the artery is used to detect the sound of the blood spurting back through the artery. This first sound is the systolic pressure, the pressure when the heart beats. The last sound heard as the rest of the air is released is the diastolic pressure, the pressure between heart beats. Both sounds are recorded on the mercury gauge on the sphygmomanometer.

Normal blood pressure is defined by a range of values. Blood pressure lower than 140/90 mm Hg is considered normal. A blood pressure around 120/80 mm Hg is considered the best level to avoid heart disease. A number of factors such as pain , stress, or anxiety can cause a temporary increase in blood pressure. For this reason, hypertension is not diagnosed on one high blood pressure reading. If a blood pressure reading is 140/90 or higher for the first time, the physician will have the person return for another blood pressure check. Diagnosis of hypertension usually is made based on two or more readings after the first visit.

Systolic hypertension of the elderly is common and is diagnosed when the diastolic pressure is normal or low, but the systolic is elevated, e.g., 170/70 mm Hg. This condition usually co-exists with hardening of the arteries (atherosclerosis).

Blood pressure measurements are classified in stages, according to severity:

  • normal blood pressure: less than 130/85 mm Hg
  • high normal: 130–139/85–89 mm Hg
  • mild hypertension: 140–159/90–99 mm Hg
  • moderate hypertension: 160–179/100–109 mm Hg
  • severe hypertension: 180–209/110–119
  • very severe hypertension: 210/120 or higher

A typical physical examination to evaluate hypertension includes:

  • medical and family history
  • physical examination
  • ophthalmoscopy: Examination of the blood vessels in the eye
  • chest x-ray
  • electrocardiograph (ECG)
  • blood and urine tests

The medical and family history help the physician determine if the patient has any conditions or disorders that might contribute to or cause the hypertension. A family history of hypertension might suggest a genetic predisposition for hypertension.

The physical exam may include several blood pressure readings at different times and in different positions. The physician uses a stethoscope to listen to sounds made by the heart and blood flowing through the arteries. The pulse, reflexes, height, and weight are checked and recorded. Internal organs are palpated, or felt, to determine if they are enlarged.

Because hypertension can cause damage to the blood vessels in the eyes, the eyes may be checked with a instrument called an ophthalmoscope. The physician will look for thickening, narrowing, or hemorrhages in the blood vessels.

A chest x ray can detect an enlarged heart, other vascular (heart) abnormalities, or lung disease.

An electrocardiogram (ECG) measures the electrical activity of the heart. It can detect if the heart muscle is enlarged and if there is damage to the heart muscle from blocked arteries.

Urine and blood tests may be done to evaluate health and to detect the presence of disorders that might cause hypertension.


Treatment

There is no cure for primary hypertension, but blood pressure can almost always be lowered with the correct treatment. The goal of treatment is to lower blood pressure to levels that will prevent heart disease and other complications of hypertension. In secondary hypertension, the disease that is responsible for the hypertension is treated in addition to the hypertension itself. Successful treatment of the underlying disorder may cure the secondary hypertension.

Treatment to lower blood pressure usually includes changes in diet, getting regular exercise , and taking anti-hypertensive medications. Patients with mild or moderate hypertension who do not have damage to the heart or kidneys may first be treated with lifestyle changes.

Lifestyle changes that may reduce blood pressure by about 5-10 mm Hg include:

  • reducing salt intake
  • reducing fat intake
  • losing weight
  • getting regular exercise
  • quitting smoking
  • reducing alcohol consumption
  • managing stress

Patients whose blood pressure remains higher than 139/90 will most likely be advised to take antihypertensive medication. Numerous drugs have been developed to treat hypertension. The choice of medication will depend on the stage of hypertension, side effects, other medical conditions the patient may have, and other medicines the patient is taking.

Patients with mild or moderate hypertension are initially treated with monotherapy, a single antihypertensive medicine. If treatment with a single medicine fails to lower blood pressure enough, a different medicine may be tried or another medicine may be added to the first. Patients with more severe hypertension may initially be given a combination of medicines to control their hypertension. Combining antihypertensive medicines with different types of action often controls blood pressure with smaller doses of each drug than would be needed for monotherapy.

Antihypertensive medicines fall into several classes of drugs:

  • diuretics
  • beta-blockers
  • calcium channel blockers
  • angiotensin converting enzyme inhibitors (ACE inhibitors)
  • alpha-blockers
  • alpha-beta blockers
  • vasodilators
  • peripheral acting adrenergic antagonists
  • centrally acting agonists

Diuretics help the kidneys eliminate excess salt and water from the body's tissues and the blood. This helps reduce the swelling caused by fluid buildup in the tissues. The reduction of fluid dilates the walls of arteries and lowers blood pressure.

Beta-blockers lower blood pressure by acting on the nervous system to slow the heart rate and reduce the force of the heart's contraction. They are used with caution in patients with heart failure, asthma , diabetes, or circulation problems in the hands and feet.

Calcium channel blockers block the entry of calcium into muscle cells in artery walls. Muscle cells need calcium to constrict, so reducing their calcium keeps them more relaxed and lowers blood pressure.

ACE inhibitors block the production of substances that constrict blood vessels. They also help reduce the build-up of water and salt in the tissues. They are often given to patients with heart failure, kidney disease, or diabetes. ACE inhibitors may be used together with diuretics.

Alpha-blockers act on the nervous system to dilate arteries and reduce the force of the heart's contractions.

Alpha-beta blockers combine the actions of alpha and beta blockers.

Vasodilators act directly on arteries to relax their walls so blood can move more easily through them. They lower blood pressure rapidly and are injected in hypertensive emergencies when patients have dangerously high blood pressure.

Peripheral acting adrenergic antagonists act on the nervous system to relax arteries and reduce the force of the heart's contractions. They usually are prescribed together with a diuretic. Peripheral acting adrenergic antagonists can cause slowed mental function and lethargy.

Centrally acting agonists also act on the nervous system to relax arteries and slow the heart rate. They are usually used with other antihypertensive medicines.


Prognosis

There is no cure for hypertension. However, it can be well controlled with the proper treatment. Therapy with a combination of lifestyle changes and antihypertensive medicines usually can keep blood pressure at levels that will not cause damage to the heart or other organs. The key to avoiding serious complications of hypertension is to detect and treat it before damage occurs. Because antihypertensive medicines control blood pressure, but do not cure it, patients must continue taking the medications to maintain reduced blood pressure levels and avoid complications.


Prevention

Prevention of hypertension centers on avoiding or eliminating known risk factors. Even persons at risk because of age, race, or sex or those who have an inherited risk can lower their chance of developing hypertension.

The risk of developing hypertension can be reduced by making the same changes recommended for treating hypertension.


Resources

books

Bellenir, Karen, and Peter D. Dresser, eds. Cardiovascular Diseases and Disorders Sourcebook. Detroit: Omnigraphics, 1995.

Texas Heart Institute. Heart Owner's Handbook. New York: John Wiley and Sons, 1996.


Toni Rizzo

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Arteries

Blood vessels that carry blood to organs and other tissues of the body.

Arteriosclerosis

—Hardening and thickening of artery walls.

Cushing's syndrome

—A disorder in which too much of the adrenal hormone, cortisol, is produced; it may be caused by a pituitary or adrenal gland tumor.

Diastolic blood pressure

—Blood pressure when the heart is resting between beats.

Hypertension

—High blood pressure.

Renal artery stenosis

—Disorder in which the arteries that supply blood to the kidneys constrict.

Sphygmomanometer

—An instrument used to measure blood pressure.

Systolic blood pressure

—Blood pressure when the heart contracts (beats).

Vasodilator

—Any drug that relaxes blood vessel walls.

Ventricles

—The two lower chambers of the heart; also the main pumping chambers.

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Hypertension

Hypertension

Hypertension is the medical term used to describe the physical condition of high blood pressure. Approximately 50 million people in the United States are afflicted with hypertension, with similar proportions of the populations of other Western countries also at risk. High blood pressure is more commonly found in older adults (defined as persons over the age of 50); persons of African descent in these countries are more seriously affected, due to genetic reasons.

Hypertension is a multidimensional health problem that occurs when the pressure created within the arteries by the usual functioning of the cardiovascular system places excess pressure on the arteries. The causes of high blood pressure are varied. The cardiovascular system delivers blood and its cargos of energy fuels, oxygen, and nutrients through the power of the heart. Each heartbeat creates pressure along the entire arterial system. The flow of blood and the function of all related systems will be optimal at a range of blood pressures. Blood pressure that is too high for the arterial vessels, or less commonly, blood pressure that is too low, create malfunctions within the entire cardiovascular network.

There is often more than one discrete cause of hypertension in any person. Typically, a number of circumstances exist to create the basis for the condition, which can include: genetic structure (there is a significantly greater likelihood of high blood pressure if one or both parents of a person had hypertension; lifestyle factors (eating habits, excess weight, level of physical fitness, particularly the level of aerobic fitness, excessive alcohol consumption, and smoking; one or more of these circumstances will increase the risk of the person developing high blood pressure); medications (certain medications that will contribute to high blood pressure include decongestant nasal sprays and various anti-inflammatory medicines); kidney and various hormonal (endocrine system) disorders.

Hypertension presents difficulties in its detection because it provides few outward physical symptoms. Instead, high blood pressure is the connection to a series of potential fatal events, including stroke, heart attack, heart arrhythmia (irregular heart beat), and kidney failure. The only determinative investigation for the existence of hypertension is the blood pressure test. Using a device attached to the person's arm, at heart level, the pressure generated by the cardiovascular system is measured using two indicators. As the heart beats, the power of blood being pushed along the artery by this pulse creates pressure on the arterial wall. The peak level of this type of blood pressure at each beat is known as the systolic pressure. During the rest interval between each heartbeat, the measure of resistance within the small arteries of the cardiovascular system to the flow of blood is determined. This pressure is referred to as the diastolic pressure.

Blood pressure is a variable within all persons; factors such as recent physical exercise, the consumption of a stimulant such as caffeine, emotional state, and medication may all significantly influence the outcome of a blood pressure test. For this reason, blood pressures are often measured a number of times before any definitive conclusion will be reached regarding the likely existence of hypertension. A reading of 120/80 (the figures are as calculated from the blood pressure test equipment scale, measured in mm of mercury, or mmHg) is accepted as a healthy blood pressure standard. When the systolic reading exceeds 140, or when the diastolic measure is greater than 90, or when both indicators are above these limits, the probability of the presence of hypertension is very high.

While hypertension may be difficult to lower significantly, it can be managed effectively through a number of means. Physical fitness and accompanying weight management, with their resulting improved cardiovascular health, are essential components to any treatment of hypertension. Increased weight places stress on the heart and cardiovascular system; the foods typically consumed by adults who are overweight are those high in fat, a substance that tends to lead to the creation of plaque, an artery-clogging substance. When arteries are clogged in this way, the passage through which blood passes becomes smaller, resulting in a correspondingly greater volume of blood being directed against a smaller vessel, increasing pressure on the artery. Physical activity tends to stimulate the production compounds known as high density lipoproteins (HDLs), which have a plaque-resistant effect within the arteries.

Prescription diuretics are sometimes administered to stimulate urine production, with a corresponding reduction in fluid and blood volumes, which tends to ease pressure within the arteries. Other medications, including angiotesin and vasodilators, are prescribed to assist in the constriction and the relaxation of the walls of the arteries.

see also Cardiovascular system; Diet; Genetics; Weight gain.

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