Heart disease is the narrowing or blockage of the arteries and vessels that provide oxygen and nutrient-rich
blood to the heart. It is caused by atherosclerosis , an accumulation of fatty materials on the inner linings of arteries that restricts blood flow. When the blood flow to the heart is completely cut off, the result is a heart attack because the heart is starved of oxygen.
Heart disease, also called coronary heart disease or coronary artery disease, is the leading cause of death for both men and women in the United States. According to the American Heart Association, deaths from coronary artery disease have declined somewhat since about 1990, but more than 40,000 people still died from the disease in 2000. About 13 million Americans have active symptoms of coronary artery disease.
Heart disease occurs when the coronary arteries become partially blocked or clogged. This blockage limits the flow of blood through the coronary arteries, the major arteries supplying oxygen-rich blood to the heart. The coronary arteries expand when the heart is working harder and needs more oxygen. If the arteries are unable to expand, the heart is deprived of oxygen (myocardial ischemia ). When the blockage is limited, chest pain or pressure called angina may occur. When the blockage cuts off the blood flow, the result is heart attack (myocardial infarction or heart muscle death).
Healthy coronary arteries are open, elastic, smooth, and slick. The artery walls are flexible and expand to let more blood through when the heart needs to work harder. The disease process is thought to begin with an injury to the linings and walls of the arteries. This injury makes them susceptible to atherosclerosis and production of blood clots (thrombosis).
Causes & symptoms
Heart disease is usually caused by atherosclerosis. Cholesterol and other fatty substances accumulate on the inner wall of the arteries. They attract fibrous tissue, blood components, and calcium . They then harden into artery-clogging plaques. Atherosclerotic plaques often form blood clots that can also block the coronary arteries (coronary thrombosis). Congenital defects and muscle spasms of arteries or heart muscles also block blood flow. Recent research indicates that infection from organisms such as chlamydia bacteria may be responsible for some cases of heart disease.
A number of major contributing risk factors increase the chance of developing heart disease. Some of these can be changed and some cannot. The greater the number of risk factors, the greater the chance of developing heart disease.
Major risk factors
Major risk factors significantly increase the chance of developing heart disease. These include:
- Heredity. People whose parents have heart disease are more likely to develop it. African-Americans are also at increased risk because they experience a high rate of severe hypertension .
- Gender. Men are more likely to have heart attacks than women and to have them at a younger age. Over the age of 60, however, women have heart disease at a rate equal to that of men.
- Age. Men who are 45 years of age and older and women who are 55 years of age and older are more likely to have heart disease. Occasionally, heart disease may strike men or women in their 30s. People over 65 are more likely to die from a heart attack. Older women are twice as likely as older men to die within a few weeks of a heart attack.
- Smoking . Smoking increases both the chance of developing heart disease and the chance of dying from it. Smokers are more than twice as likely as nonsmokers to have a heart attack and are two to four times more likely die from it.
- High cholesterol levels. Dietary sources of cholesterol are meat, dairy food, eggs, and other animal fat products. It is also produced by the body. Age, body fat, diet, exercise , heredity, and sex affect one's blood cholesterol. Total blood cholesterol is considered high at levels above 240 mg/dL and borderline at 200-239 mg/dL. High-risk levels of low-density lipoprotein (LDL cholesterol) begin at 130-159 mg/dL, depending on other risk factors. Risk of developing heart disease increases steadily as blood cholesterol levels increase above 160 mg/dL.
- High blood pressure. High blood pressure makes the heart work harder and weakens it over time. It increases the risk of heart attack, stroke , kidney failure, and congestive heart failure. A blood pressure of 140 over 90 or above is considered high. The risk of heart attack or stroke is raised several times for people with high blood pressure combined with obesity , smoking, high cholesterol levels, or diabetes.
- Lack of physical activity. Lack of exercise increases the risk of heart disease. Even modest physical activity, like walking, is beneficial if done regularly.
- Diabetes mellitus. The risk of developing heart disease is seriously increased for diabetics. More than 80% of diabetics die of some type of heart or blood vessel disease.
Contributing risk factors
Contributing risk factors have been linked to heart disease, but their significance is not known yet. Contributing risk factors are:
- Obesity. Excess weight increases the strain on the heart and increases the risk of developing heart disease even if no other risk factors are present. Obesity increases blood pressure and blood cholesterol and can lead to diabetes.
- Hormone replacement therapy (HRT). Even though physicians once believed that HRT could help prevent heart disease in women, the Women's Health Initiative (WHI) released information in 2002 and 2003 showing that use of combined hormones (estrogen and progestin) is harmful in women who already have coronary artery disease.
- Stress and anger. Some scientists believe that poorly managed stress and anger can contribute to the development of heart disease and increase the blood's tendency to form clots (thrombosis). Stress increases the heart rate and blood pressure and can injure the lining of the arteries.
- Chest pain (angina). Angina is the main symptom of coronary heart disease but it is not always present. Other symptoms include shortness of breath, chest heaviness, tightness, pain, a burning sensation, squeezing, or pressure either behind the breastbone or in the left arm, neck, or jaws. According to the American Heart Association, 63% of women and 48% of men who died suddenly of heart disease had no previous symptoms of the disease.
Diagnosis begins with a visit to the physician, who will take a medical history, discuss symptoms, listen to the heart, and perform basic screening tests. These tests will measure blood lipid levels, blood pressure, fasting blood glucose levels, weight, and other indicators. Other diagnostic tests include resting and exercise electrocardiograms, echocardiography, radionuclide scans, and coronary angiography. The treadmill exercise (stress) test is an appropriate screening test for those with high risk factors even though they feel well.
An electrocardiogram (ECG) shows the heart's activity and may reveal a lack of oxygen (ischemia). Electrodes covered with conducting jelly are placed on the patient's chest, arms, and legs. They send impulses of the heart's activity through an oscilloscope (a monitor) to a recorder that traces them on paper. Another type of electrocardiogram, known as the exercise stress test, measures how the heart and blood vessels respond to exertion when the patient is exercising on a treadmill or a stationary bike. Both tests can be performed in a physician's office or outpatient facility.
Echocardiography, or cardiac ultrasound, uses sound waves to create an image of the heart's chambers and valves. A technician applies gel to a hand-held transducer, then presses it against the patient's chest. The heart's sound waves are converted into an image that can be displayed on a monitor. The test does not reveal the coronary arteries themselves but can detect abnormalities in the heart wall caused by heart disease. Typically performed in a doctor's office or outpatient facility, the test takes 30-60 minutes.
Radionuclide angiography enables physicians to see the blood flow of the coronary arteries. Nuclear scans are performed by injecting a small amount of a radiopharmaceutical, such as thallium, into the bloodstream. As the patient lies on a table, a camera that uses gamma rays to produce an image of the radioactive material passes over the patient and records pictures of the heart. Radionuclide angiography is usually performed in a hospital's nuclear medicine department. The radiation exposure is about the same as that in a chest x ray.
Coronary angiography is considered the most accurate method for making a diagnosis of heart disease but it is also the most invasive. During coronary angiography the patient is awake but sedated. The cardiologist inserts a catheter into a blood vessel and guides it into the heart. A contrast dye (a radiopaque substance that is visible on x ray) is injected into the catheter and x rays are taken. Coronary angiography is performed in a cardiac catheterization laboratory in either an outpatient or inpatient surgery unit.
Herbal medicine has a variety of remedies that may have a beneficial effect on heart disease. Garlic (Allium sativum ), myrrh (Commiphora molmol ), oats (Avena sativa ) may help reduce cholesterol and hawthorn (Crataegus spp.), linden (Tilia europaea ), and yarrow (Achillea millefolium ) are sometimes recommended to control high blood pressure, a risk factor for heart disease. Tea, especially green tea (Camellia sinensis ), is high in antioxidants ; studies have shown that it may have a preventative effect against atherosclerosis. Coenzyme Q10 has been shown to be beneficial for 70% of patients with congenitive heart failure. According to Dr. Elson Haas, taurine, an amino acid found in meat and fish proteins, is used to treat heart arrhythmia. Two grams three times a day for people with congestive heart failure showed improved cardiovascular functions.
Yoga and other bodywork, massage, relaxation , aromatherapy, and music therapies may also help prevent heart disease and stop, or even reverse, the progression of atherosclerosis. Vitamin and mineral supplements that reduce, reverse, or protect against heart disease include B-complex vitamins, calcium, chromium, magnesium , L-carnitine, zinc , and the antioxidant vitamins C and E. The effectiveness of vitamins C and E is still under debate, and physicians caution that they be used in moderation.
Traditional Chinese medicine (TCM) may recommend herbal remedies, massage, acupuncture , and dietary modification. A healthy diet (including cold water fish as a source of essential fatty acids ) and exercise are important components of both alternative and conventional prevention and treatment strategies.
New reports on diet and heart disease have answered some questions, but others remain unclear. While one study concludes that four servings per day of fruit and vegetables are associated with a slight drop in risk of heart disease, eight or more servings per day can produce a significant drop in risk. Another study showed that consuming legumes at least four times per week lowered risk of heart disease from 11% to 22% compared with consuming legumes less than once a week. Research on antioxidants continues to send mixed messages, with some reports showing that vitamins E, C, and other antioxidants can help prevent heart disease, and other studies showing they have no effect. Many physicians and researchers therefore recommend that those wanting to follow healthy heart habits continue to eat a diet rich in antioxidants but recognize that there is probably no value in adding antioxidant supplements to a good diet.
Heart disease can be treated in many ways. The choice of treatment depends on the patient and the severity of the disease. Treatments include lifestyle changes and drug therapy, coronary artery bypass surgery, and percutaneous transluminal coronary angioplasty, although these are not cures. Heart disease is a chronic disease requiring lifelong care.
Percutaneous transluminal coronary angioplasty, usually called coronary angioplasty, is a nonsurgical procedure. A catheter tipped with a balloon is threaded from a blood vessel in the thigh into the blocked artery. The balloon is inflated, compressing the plaque to enlarge the blood vessel and open the blocked artery. The balloon is then deflated and the catheter removed.
People with moderate heart disease may gain adequate control through lifestyle changes and drug therapy. Drugs such as nitrates, beta-blockers, and calcium-channel blockers relieve chest pain and complications of heart disease, but they cannot clear blocked arteries. Nitrates improve blood flow to the heart, and beta-blockers reduce the amount of oxygen required by the heart during stress. Calcium-channel blockers help keep the arteries open and reduce blood pressure.
Aspirin helps prevent blood clots from forming on plaque deposits, reducing the likelihood of a heart attack and stroke. Cholesterol-lowering medications are also indicated in most cases.
Coronary angioplasty is successful about 90% of the time, but for one-third of patients the artery narrows again within six months. The procedure can be repeated. It is less invasive and less expensive than coronary artery bypass surgery.
In coronary artery bypass surgery, a healthy vein from an arm, leg, or chest wall is used to build a detour around the coronary artery blockage. The healthy vessel then supplies oxygen-rich blood to the heart. Bypass surgery is major surgery. It is appropriate for those patients with blockages in two or three major coronary arteries, those with severely narrowed left main coronary arteries, and those who have not responded to other treatments. About 70% of patients who have bypass surgery experience full relief from angina; about 20% experience partial relief. Only about 3-4% of patients per year experience a return of symptoms.
Three other surgical procedures for unblocking coronary arteries are being studied and used on a limited basis. Atherectomy is a procedure in which the cardiologist shaves off and removes strips of plaque from the blocked artery. In laser angioplasty, a catheter with a laser tip is inserted into the affected artery to burn or break down the plaque. A metal coil called a stent can be implanted permanently to keep a blocked artery open. Stenting is becoming more common.
Advances in medicine and the adoption of healthier lifestyles have caused a substantial decline in death rates from heart disease since the mid-1980s. New diagnostic techniques enable doctors to identify and treat heart disease in its earliest stages. New technologies and surgical procedures have extended the lives of many patients who would have otherwise died. Research on heart disease continues.
A healthy lifestyle can help prevent heart disease and slow its progress. A heart-healthy lifestyle includes maintaining a healthy diet, regular exercise, weight maintenance, no smoking, moderate drinking, controlling hypertension, and managing stress. Cardiac rehabilitation programs are excellent to help prevent recurring coronary problems for people who are at risk and who have had coronary events and procedures.
A healthy diet includes a variety of foods that are low in fat, especially saturated fat, low in cholesterol, and high in fiber. It includes plenty of fruits and vegetables and limited salt. Saturated fats should equal seven to 10% of calories, polyunsaturated fats should equal about 10%, monounsaturated fat should be 15%, and carbohydrates should total 55-60% of daily calories. Fat should comprise no more than 30% of total daily calories and should be taken preferably as fish oil , olive oil, seeds, and vegetable oil. New evidence shows that replacing saturated fat with unsaturated fat is more effective in lowering coronary heart disease risk than reducing total fat intake. Eating cold-water fish or taking comparable omega-3 polyunsaturated fatty acid supplements can help prevent cardiac death. In 2003, the American Heart Association began advocating daily servings of fatty fish or three fish oil capsules daily.
Cholesterol, a waxy substance containing fats, is found in foods such as meat, dairy, eggs, and other animal products. It is also produced in the liver. Soluble fiber can help lower cholesterol. Dietary cholesterol should be limited to about 300 milligrams per day. Many popular lipid-lowering drugs can reduce LDL cholesterol by an average of 25-30% when used with a low-fat, lowcholesterol diet.
Antioxidants are chemical compounds in plant foods. When people eat antioxidant-rich foods, they may improve the function of the arteries, prevent arterial plaque formation, and reduce their risk of cancer . Colorful vegetables and fruits are sources of antioxidants, and are rich in fiber, vitamins, and minerals. They are lowcalorie and nearly fat-free. Vitamin C and beta-carotene, found in many fruits and vegetables, keep LDL-cholesterol from turning into a form that damages coronary arteries. Whole grains, especially whole oats and oat bran, reduce cholesterol.
Excess sodium can increase the risk of high blood pressure. Many processed foods contain large amounts of sodium. Daily intake should be limited to about 2,400 milligrams, about the amount in a teaspoon of salt.
The Food Guide Pyramid developed by the U.S. Departments of Agriculture and Health and Human Services provides easy-to-follow guidelines for daily heart-healthy eating.
Aerobic exercise can lower blood pressure, help control weight, and increase HDL (good) cholesterol. It also may keep the blood vessels more flexible. The Centers for Disease Control and Prevention and the American College of Sports Medicine recommend moderate to intense aerobic exercise lasting about 30 minutes four or more times per week for maximum heart health. People with heart disease or risk factors should consult a doctor before beginning an exercise program.
Maintaining a desirable body weight
People who are 20% or more over their ideal body weight have an increased risk of developing heart disease. Losing weight can help reduce total and LDL cholesterol, reduce triglycerides, and boost HDL cholesterol. It may also reduce blood pressure. Eating right and exercising are two key components of losing weight.
Smoking has many adverse effects on the heart. It increases the heart rate, constricts major arteries, and can create irregular heartbeats. It also raises blood pressure, contributes to the development of plaque, increases the formation of blood clots, and causes blood platelets to cluster and impede blood flow. When smokers quit the habit, heart damage can be repaired. Several studies have shown that ex-smokers face the same risk of heart disease as nonsmokers within five to 10 years after they quit.
Drinking in moderation
Modest consumption of alcohol may actually protect against heart disease because alcohol appears to raise levels of HDL cholesterol. The American Heart Association defines moderate consumption as one ounce of alcohol per day, roughly one cocktail, one 8-ounce glass of wine, or two 12-ounce glasses of beer. Excessive drinking is always bad for the heart. It usually raises blood pressure and can poison the heart and cause abnormal heart rhythms or even heart failure.
Seeking diagnosis and treatment for hypertension
High blood pressure, one of the most common and serious risk factors for heart disease, can be completely controlled through lifestyle changes and medication. Seeking out the diagnosis and treatment is critical because hypertension often exhibits no symptoms; many people do not know they have it. Moderate hypertension can be controlled by reducing dietary intake of sodium and fat, exercising regularly, managing stress, abstaining from smoking, and drinking alcohol in moderation.
- —A deposit of fatty substances and calcium that accumulates in the lining of the artery wall.
Everyone experiences stress. Stress can sometimes be avoided and, when it is inevitable, it can be managed through relaxation techniques, exercise, and other methods.
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DeBakey, Michael E., and Antonio M. Gotto, Jr. Heart disease, and Surgical Treatment of Heart disease. In The New Living Heart. Holbrook, MA: Adams Media Corporation, 1997.
Haas, Elson, M.D. Staying Healthy with Nutrition: The Complete Guide to Diet and Natural Medicine. Berkeley, CA: Celestial Arts, 1992.
Ody, Penelope. The Complete Medicinal Herbal. New York: DK Publishing. 1993.
Cerrato, Paul L. "Antioxidants, CAD, and Diabetes." Contemporary OB/GYN (January 2002): 111.
Dioreto, Stacy. "Legume Intake Lowers CHD Risk." Patient Care (January 30, 2002): 41.
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Mirzaei, H.A. "Role of Soy Protein in Lowering LDL Levels." The Journal of Nutrition (March 2002): 604S.
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Teresa G. Odle
"Heart Disease." Gale Encyclopedia of Alternative Medicine. . Encyclopedia.com. (July 23, 2017). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/heart-disease
"Heart Disease." Gale Encyclopedia of Alternative Medicine. . Retrieved July 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/heart-disease
The heart, which is about the size of a human fist, is the body's largest, strongest, and most important muscle. The heart continuously pumps blood through the body, helps regulate and prolong health, and controls the flow (circulation) of blood to the lungs, organs, muscles, and tissues in the body.
Heart disease is a leading cause of debilitation and death worldwide in men and women over age sixty-five. In many countries heart disease is viewed as a "second epidemic," replacing infectious diseases as the leading cause of death. It is especially devastating in countries that do not have adequate health care. There are many types of diseases and disorders that affect the heart.
Congenital Heart Disease
Congenital cardiac anomaly (CAA), also known as congenital heart disease (CHD), refers to any structural defect of the heart or major vessels that exists from birth. It is the most common cause of infant death, other than problems of prematurity, and death is likely to occur in the first year of life. CAA may result either from genetic causes or from external causes such as maternal infection or exposure to other factors that affect embryonic development . The general problems associated with CAA include increased cardiac workload, hypertension , poor oxygenation of blood, and respiratory infections. There are many types of CAA, including aortic stenosis, atrial septal defect, valvular stenosis, and pulmonary stenosis.
Rheumatic Heart Disease
Rheumatic heart disease (RHD) involves damage to the heart and heart vessels caused by rheumatic fever. A susceptible person acquires a streptococcal infection, which may trigger an autoimmune reaction in the heart tissue. Rheumatic fever can cause swelling (inflammation) in the heart, joints, brain, and spinal cord. Rheumatic fever produces fatigue (tiredness) and the infection can damage or weaken heart valves. Problems with the heart may be evident early, or it may occur long after the infection. RHD is characterized by heart murmurs, abnormal pulse rate and rhythm, and congestive heart failure. Acute RHD requires aggressive treatment to prevent heart failure. Chronic RHD requires continuous observation. If poor cardiac function develops, it may be treated with a low-sodium diet and diuretics . Patients with deformed heart valves should be given prophylactic antibiotics before dental and surgical procedures.
Myocardial Infarction (MI)
Myocardial infarction (MI) is the clinical term for a heart attack . It is caused by occlusion (blockage) of the coronary artery (atherosclerosis ) or a blood clot (coronary thrombosis), resulting in the partial or total blockage of one of the coronary arteries. When this occurs, the heart muscle (myocardium) does not receive enough oxygen . If the MI is mild, the heart muscle may partially repair itself. Permanent damage may occur when a portion of the heart muscle dies (called an infarction).
MI is characterized by crushing chest pains that may radiate to the left arm, neck, or upper abdomen (which may feel like acute indigestion or a gallbladder attack). The affected person usually has shortness of breath, ashen color, clammy hands, and faints. Treatment within one hour of the heart attack is important and usually includes chewing aspirin and administering CPR. Many individuals die each year of their first MI.
Coronary Artery Disease (CAD)
Coronary artery disease (CAD) refers to any one of the conditions that affect the coronary arteries and reduces blood flow and nutrients to the heart. It is the leading cause of death worldwide for both men and women. The most common kind of CAD is atherosclerosis, which results in narrowing and hardening of the arteries. Coronary atherosclerosis is at epidemic proportions worldwide.
Traditionally, CAD was seen as a disease of aging and was observed primarily in the elderly. However, atherosclerosis is now occurring more often in younger populations. One out of every three individuals worldwide, and one in five in the United States, dies from heart disease each year. In the United States, CAD has declined more rapidly in whites than in blacks. CAD affects women ten years later than men, mostly due to the protective production of estrogen . After menopause , a woman is two times more susceptible to heart disease than women who have not reached menopause.
Risk factors. Controlled risk factors associated with CAD include hypertension; cigarette smoking; elevated blood lipids (e.g. cholesterol , triglyceride ); a high-fat diet (especially saturated fats and trans-fatty acids ); physical inactivity; obesity ; diabetes ; and stress . Lifestyle changes can assist in prevention of CAD. Uncontrolled risk factors include a family history of CAD, gender (higher in males), and increasing age.
Tobacco use is one of the leading contributors to heart disease. Smoking increases the risk of heart attacks (and increases the risk of lung diseases) by decreasing oxygen flow to the heart and lungs. Hypertension, which makes the heart work harder than normal, can be caused by poor diet, excessive dietary salt, lack of exercise, smoking, and chronic stress. Adult-onset diabetes mellitus may result from poor dietary habits and lack of exercise over a lifetime. Uncontrolled diabetes can lead to heart failure. Exercise can reduce the risk for CAD by increasing coronary blood flow, and it has shown positive effects on blood flow to the heart (myocardial perfusion). Long-term benefits of exercise include lower incidences of coronary heart failure and increased cardiac function in normal subjects.
Prevention. Health professionals recommend that dietary fat be reduced to 30 percent or less of total calories . The diet also should have no more than 10 percent of its calories from saturated fats, no more than 300 milligrams (mg) of cholesterol daily, no more than 2,400 mg of sodium, and at least 3,500 mg of potassium. A plant-based diet consisting primarily of whole grains, fruits, and vegetables is recommended. Eating at least 25 grams of fiber and five servings of fruits and vegetables daily may reduce the risk for heart disease.
Individuals who consume alcohol should do so in moderation. Moderation is defined as two drinks for men and one drink for women daily. Alcohol is a very addictive substance, however, and should not be used as a primary means of prevention. Caffeine in moderation has no adverse effect; however, excessive intake may make the heart pump faster. Increased heart rate stresses the heart and may cause long-term damage to blood vessels.
Establishing good exercise and dietary habits early in childhood is important to prevent heart disease. Regular activity and proper nutrition decreases reactivity to stress and makes the heart stronger and more efficient. At least thirty minutes of moderate exercise daily is recommended to prevent heart disease. Stress management helps to prevent high blood pressure , which is a major contributor to heart disease. Techniques such as yoga, deep breathing, and meditation may prevent coronary disease by improving resistance to stress.
see also Arteriosclerosis; Atherosclerosis; Cardiovascular Diseases; Exercise.
Goldberg, I. J.; Mosca, L.; Piano, M. R.; and Fisher, E. A. (2001). "Wine and Your Heart: A Science Advisory for Healthcare Professionals from the Nutrition Committee, Council on Epidemiology and Prevention, and Council on Cardiovascular Nursing of the American Heart Association." Circulation 103:472–475.
Insel, P. M., and Roth, W. T. (2004). "Cardiovascular Disease and Cancer." In Core Concepts in Health, 9th (brief) edition. New York: McGraw-Hill.
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American Heart Association/American Stroke Association. "Heart Disease and Stroke Statistics—2003 Update." Available from <http://www.americanheart.org>
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"Heart Disease." Nutrition and Well-Being A to Z. . Encyclopedia.com. (July 23, 2017). http://www.encyclopedia.com/food/news-wires-white-papers-and-books/heart-disease
"Heart Disease." Nutrition and Well-Being A to Z. . Retrieved July 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/food/news-wires-white-papers-and-books/heart-disease
heart disease, any of several abnormalities of the heart and its function in maintaining blood circulation. Heart disease is the cause of approximately half the deaths in the United States each year. Among the most common causes of heart disease are degenerative changes in the coronary blood vessels, infectious diseases, and congenital heart disease. Congenital defects result from abnormal development of the fetal heart, commonly in the valves or septa. Such defects can be precipitated by environmental conditions in the uterus, such as the presence of the rubella virus, or they can be inherited. Infectious diseases acquired after birth, such as rheumatic fever, syphilis, and endocarditis, can also damage the valves of the heart. In addition, the heart muscle itself can be affected: hypertensive heart disease (see hypertension) can cause it to enlarge, and it can become inflamed by rheumatic fever. Arteriosclerotic depositions in the coronary arteries result in the narrowing of these vessels, causing insufficient blood flow and oxygen to the heart muscle, a condition known as coronary artery disease. The characteristic radiating chest pain, angina pectoris, is the most prominent symptom of this condition. Coronary arteries already narrowed by arteriosclerosis are made susceptible to blockage by a clot (coronary thrombosis), causing the death of the heart muscle supplied by the affected artery, a life-threatening event called a myocardial infarction, or heart attack. Hypertensive, coronary, congenital, and other forms of cardiovascular disease, either singly or in combination, can lead to a state in which the heart is unable to expel sufficient blood for the metabolic demands of the body, ultimately resulting in congestive heart failure. Disturbances in the normal heartbeat, called arrhythmias, can occur by themselves or in conjunction with other heart problems, for example infarction affecting the area of the heart that controls the heartbeat.
"heart disease." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (July 23, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/heart-disease
"heart disease." The Columbia Encyclopedia, 6th ed.. . Retrieved July 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/heart-disease
Heart disease is a broad term covering many conditions that prevent the heart from working properly to pump blood throughout the body.
for searching the Internet and other reference sources
Coronary artery disease
Max, who had just turned 14, and his grandfather Harry often shared a Saturday morning ritual: breakfast at their favorite diner, followed by a brisk game of tennis. On this occasion, they both ordered the special: two fried eggs, four strips of bacon, hotcakes, and a side of hash browns. Plates cleared, they hit the tennis courts, but only ten minutes into their game, Harry, breathing hard and sweating heavily, stopped and complained of a squeezing pain in his chest. Although his grandfather protested that it was most likely indigestion, Max went for help. At the emergency room, his grandfather was given aspirin and put on a heart monitor that showed
that he had experienced a mild heart attack. A nurse told Max that his quick action might have saved his grandfather’s life.
Heart disease is a group of diseases that prevent the heart from working as well as it should.
Only a little larger than a fist, a normal, healthy heart is at the center of the body’s cardiovascular system*. Each day the average heart beats, or expands and contracts, about 100,000 times. In a 70-year lifetime, an average human heart beats more than 2.5 billion times.
- * cardiovascular system
- (kar-dee-o-VAS-ku-lur) is comprised of the heart and blood vessels.
The circulatory system* is responsible for providing nourishment to the body’s cells and removing wastes from them. The arteries take oxygenated blood from the heart to the cells; the veins take blood from the cells to the lungs for reoxygenation and recirculation by the heart.
- * circulatory system
- (SIR-ku-la-tor-ee) is made up of the heart, arteries, veins, capillaries, and circulating blood.
The coronary arteries encircle the heart from above and below like strands of ivy. With their strong, flexible walls and smooth linings, healthy coronary arteries supply blood to the heart itself, in much the same way as a hose transports water to a garden.
At birth, these coronary arteries are completely open and clear, permitting a maximum flow of blood to the heart, but as people age, these vessels can become clogged with a thick combination of lipids (fats), cholesterol, calcium, and other substances. As these layers accumulate inside the arteries, they can lead to arteriosclerosis (ar-teer-e-o-skle-RO-sis), a condition also known as “hardening of the arteries,” since this buildup eventually stiffens the inner artery walls. Atherosclerosis (ath-er-o-skle-RO-sis), a buildup of plaque* on the innermost portion of the vessel, is the most common form of arteriosclerosis. Over time, plaque continues to accumulate in the blood vessels, much like grease that clogs a kitchen drainpipe. The result is a narrowing of the inside diameter of the vessel.
- * plaque
- (PLAK) is a raised patch or swelling on a body surface. Arterial plaque occurs on the inner surface of an artery and is produced by fatty deposits.
Coronary arteries affected by atherosclerosis will eventually develop coronary artery disease, a condition in which the vessels are so narrow that they can no longer provide adequate nutrients or oxygen to nourish the heart. Blood flow is blocked either partially or totally.
Heart attacks are injuries to the heart muscle that occur when blood flow through a coronary artery is interrupted, cutting off the vital supply of oxygen to the heart. Blood can be kept from the heart by narrowing
of the arteries by atherosclerotic plaque, by a blood clot blocking the narrowed vessel, or by a contraction (spasm) of the artery in response to a lack of oxygen or blood. The part of the heart muscle affected by the blockage is usually slowly starved of oxygen. The longer the heart muscle goes without nourishment, the more muscle tissue deteriorates or dies. Quick action, like that taken by Max, is essential.
Blocked arteries are not the only cause of heart attacks. Hypertension, or high blood pressure, can be a contributing factor. Pumping blood against high pressures in the blood vessels (as occur in people with uncontrolled hypertension) can put too much strain on the heart. Abuse of alcohol, viral infections, tuberculosis, parasites, or other vascular (blood vessel) diseases can also lead to heart disease.
Diseased valves can also put abnormal strain on the heart. The four valves, located between the atria (upper chambers) and ventricles (lower chambers) of the heart, open and close like tiny camera shutters to make sure that blood flows in the right amount and in the right direction. If a valve is scarred and cannot open completely, the heart has to work harder to pump enough blood through the obstruction. A valve that does not close completely can allow blood to go backward through the heart chambers, making the heart work harder by having to pump the same blood twice.
Bacterial endocarditis, or inflammation of the endocardium (the inner surface of the heart), is an infection that can cause the heart valves to malfunction. Such an infection may rarely follow oral surgery or dental work, when normally harmless bacteria are released into the bloodstream. This generally affects valves that were previously damaged from rheumatic heart disease or other conditions.
Body Mass Index
The body mass index (BMI) has been used since the early 1980s as a medical standard for obesity measurement. To calculate BMI:
1. Multiply weight in pounds by 700
2. Divide that number by height in inches
3. Divide that number by height in inches again
The recommended BMI is 20 to 26. The overweight range is 26 to 27.3 for women and 26 to 27.8 for men. Most “experts” say that obesity begins with a BMI greater than 27.3 for women and 27.87 for men. All agree that anyone with a BMI over 30 is obese.
Various forms of heart disease can also cause dysrhythmias (dis-RITH-me-as), or disturbances in the normal heartbeat pattern. Although many of these are harmless, some are quite serious. For example, ventricular fibrillation (ven-TRIK-yoo-lar fib-rill-AY-shun), a type of heart rhythm in which pumping is uncoordinated and ineffective, can cause sudden death.
Heart disease is not contagious and, to a large extent, can be prevented, controlled, and, in some cases, even reversed. When looking at what causes heart disease, researchers divide the risk factors* into those that people can control and those that they cannot. Among the factors that cannot be changed are:
- * risk factors
- are things about people, such as their age, weight or diet that increase their chances of getting a certain disease.
- Age. As people age, their cholesterol levels usually increase and hardening of the arteries appears and progresses in most people.
- Gender. Men have higher cholesterol levels than women until around age 45. Women catch up after menopause*.
- * menopause
- (MEN-o-pawz) is the time of life when women stop menstruating (having their monthly period) and can no longer become pregnant.
- Family histories. People with a family history of heart disease are at increased risk.
The good news is that some risk factors can be controlled. These include:
- Smoking. Smokers’ risk of heart attack is almost twice that of nonsmokers, and their risk of sudden cardiac death is two to four times that of nonsmokers. Quitting (or never starting!) is a definite heart-healthy move.
- High blood pressure. Hypertension puts extra stress on the heart. Taking medication to lower high blood pressure, maintaining healthy body weight, avoiding salt, and increasing exercise can help people reduce blood pressure.
- Blood lipids. Lowering fats in the blood, such as cholesterol, can reduce the risk of heart disease. Individuals who come from a family with heart disease; who have other risk factors such as smoking, diabetes, hypertension, obesity, or physical inactivity; or who have a parent with a high cholesterol level should have their lipid levels monitored by a doctor.
- Diabetes. Many people with diabetes have high blood pressure or are obese. Diabetes can also increase lipid levels and accelerate the development of atherosclerosis, heart attack, and stroke.
- Obesity. Obesity is generally defined as having an adult body mass index greater than 27 (see sidebar). About one third of American adults are obese, even though maintaining a healthy weight throughout life seems to be one of the best ways of living longer and healthier. In a famous 30-year study of 5,127 adults in Framingham, Massachusetts, between 1948 and 1978, those who maintained their weight from age 25 on had a lower risk of heart disease. Those who lowered their weight over this time reduced their risk even further.
- Physical activity. Exercisers have a lower rate of cardiovascular disease; those who are inactive have a higher rate. Aerobic exercise* lowers the heart rate, lipid levels, and blood pressure and decreases body fat. Such activities include brisk walking, running, swimming, rowing, and jumping rope for at least ten to fifteen minutes. It is estimated that 60 percent of American adults get no aerobic exercise.
- * aerobic exercise
- (air-O-bik) is exercise designed to increase oxygen consumption by the body; it helps keep the heart and lungs in shape.
The U.S. and the World
The American Heart Association says cardiovascular disease has been the leading cause of death in the United States every year since 1900, except the year 1918. According to the AHA’s 1999 Heart and Stroke Statistical Update:
- Almost 60 million Americans have some form of cardiovascular disease. The most common condition is high blood pressure, which affects 50 million Americans.
- Heart disease killed 944,148 people in the United States in 1997, making it the leading cause of death. It accounts for about 40 percent of all deaths each year in America.
- About 84 percent of heart disease deaths occur in people who are 65 and older.
Heart disease also is a leading cause of death worldwide. The World Health Organization reports that in 1998, for example, 32 percent of all deaths (16.7 million) resulted from heart disease. It was the number 1 cause of death in all regions of the world, except Africa (where it was ninth) and the western Pacific (where it was third).
WHO predicts that worldwide heart disease death rates will climb during the next two decades if developing nations continue their trend toward increased smoking and more westernized diets.
Other risk factors that can be controlled include drinking too much alcohol and having too much stress.
The fat connection
Cholesterol (ko-LES-ter-ol) is a soft, waxy substance that circulates in the blood and is found in every cell of the body. It is an important building material for cells and nerves and is used for the production of certain hormones. Cholesterol is used by the liver to make bile acids, which help digest food. Triglycerides (try-GLIS-er-ides) are fats in the blood that, like cholesterol, can come from either the diet or can be produced by the liver. Triglycerides are different from cholesterol, but like cholesterol, they are normally present in the blood. Elevated triglycerides may be associated with certain illnesses.
The body makes all the cholesterol it needs, but people also get cholesterol from their diets, particularly when they eat foods made from animal and dairy products. High blood cholesterol levels can have many causes, including genes (heredity) and lifestyle choices (diet). Too much cholesterol can lead to coronary heart disease. Hyperlipid disorders, in which there is too much cholesterol or too much triglyceride in the blood, are some of the most common inherited conditions in humans, affecting one in every 500 people. In persons with such disorders, risk factors such as obesity, cigarette smoking, and high blood pressure can increase the chance of coronary heart disease even further.
Heart disease is the number one killer in developed countries, and heart attacks are recognized as the most obvious sign of heart disease. Each year, 1.5 million Americans have heart attacks. But one problem with heart disease is that in 20 to 40 percent of people (like Max’s grandfather), a heart attack is the first symptom of the disease. By then, plaque may have narrowed one or more arteries, limiting their ability to supply an area of the heart muscle with the oxygen and nutrients it needs.
Because a heart attack can cause severe damage by robbing the heart of oxygen, a quick reaction to the earliest signs of a heart attack is essential. Angina pectoris (an-JY-na PEK-to-ris), a squeezing, tightness, or heaviness in the chest that can extend to the left arm, neck, jaw, or shoulder blade, is often the first sign that someone with atherosclerosis is at risk for a heart attack. Physical exercise, a heavy meal, strong emotions, or extreme temperatures can bring it on. If angina occurs when a person is at rest, this means that the heart is starving for oxygen even when it is not working hard. Besides chest pain, weakness, fainting, profuse sweating, nausea, and vomiting can accompany a heart attack, although a heart attack that arrives without angina—a “silent” heart attack—may not be revealed until a patient shows up in the physician’s office for an unrelated condition.
Valve disease can cause related symptoms of dizziness, fatigue, weakness, shortness of breath, and chest pain when exercising. These same signs, along with edema (e-DEE-ma), an accumulation of fluid that occurs when the heart cannot keep the circulation moving properly, can indicate heart failure*. Gravity often pulls the fluid downward, causing swelling in the feet, ankles, and legs.
- * heart failure
- is a medical term used to describe a condition in which a damaged heart cannot pump enough blood to meet the oxygen and nutrient demands of the body. People with heart failure may find it hard to exercise due to the insufficient blood flow, but many people live a long time with heart failure.
Depending on the type of heart disease, a physician can use a number of different tests to help pinpoint heart problems. They are divided into invasive tests done internally and noninvasive tests that can be performed externally. Noninvasive procedures include:
- Electrocardiogram (ECG or EKG). A recording of the heart’s electrical activity to help a doctor diagnose and monitor irregular heart rhythms, heart attacks, or other abnormalities. A portable ECG machine worn by a patient called a Holter monitor can also test the effectiveness of drug therapy for dysrhythmias and monitor pacemaker* functions for 12, 24, or 48 hours.
- Stress test . An ECG performed during exercise to determine the cause of chest pain and other symptoms related to physical activity.
- Echocardiogram . Ultrasonic waves, or high-frequency inaudible sound waves, are bounced off the surfaces of the heart and converted into an image that can be displayed on a monitor to diagnose congenital* heart disease, valve disease, congestive* heart failure, and other conditions.
- Ultra-fast computed tomography. Scanning that employs electron beams to detect calcium deposits in the coronary arteries.
- * pacemaker,
- a device whose function is to send electrical signals that control the heartbeat. The heart’s natural pacemaker is the sinoatrial node, a special group of cells. Sometimes it is necessary to implant a battery-powered pacemaker that sends small electrical charges through an electrode placed next to the wall of the heart.
- * congenital
- (kon-JEN-i-tul) means existing at birth.
- * congestive
- (kon-JES-tiv) means characterized by accumulation of too much fluid.
Invasive procedures include cardiac catheterization, which is used to evaluate coronary artery disease, causes of angina, complications following a heart attack, heart defects, and other internal disorders. A catheter, or long, thin tube, is inserted into the cardiovascular system, usually through
an arm or leg artery. A contrast solution (a dye that will show up on film) is then injected to visualize the blood vessels on film (angiography). Depending on where the catheter is positioned, it can diagnose the extent of coronary artery plaque buildup or abnormalities of the aorta* and valves.
- * aorta
- (ay-OR-ta) is the major large artery that carries blood from the heart to the rest of the the body.
Although many heart conditions cannot be cured, they can be controlled with lifestyle changes, medication, or surgery, or a combination of these strategies.
Irregular heartbeats, heart failure, and angina are often treated with a combination of healthy lifestyle changes and medications. One of the most common medications used is nitroglycerine (ny-tro-GLIS-er-in), in the form of a tiny pill dissolved under the tongue, which acts to open the heart’s blood vessels and permit more oxygen to flow to the heart muscle. Beta-blockers decrease the heart s demand for oxygen by slowing down the heart rate. Aspirin, which helps keep the blood from clotting easily, is given to people who have heart disease or a high risk of heart disease to decrease the likelihood of blood clots and thereby lowers the risk of heart attack and premature death. At the time of a heart attack, patients may be given special clot-dissolving medications intravenously (injected into a vein) to help unclog the diseased coronary arteries. Medications are also used to control high blood pressure.
Angioplasty (AN-je-o-plas-tee), also called balloon angioplasty, opens up vessels blocked by plaque buildup. A specially designed balloon is threaded through an artery. Once positioned, the balloon is set at the narrowest portion of the blocked artery and inflated, pumping up and widening the channel. After the artery is opened, the balloon is withdrawn.
One problem is that coronary arteries opened by angioplasty often close within three to six months. To prevent this, surgeons often place a stent, a 1-inch tube of wirelike stainless steel shaped like a tiny coiled spring, into the vessel, where it is expanded. The stent props the vessel open like scaffolding supports a tunnel. Stents can also be lifesaving for
Frog’s Legs and Galvanometers
Today’s sophisticated electrocardiograph (ECG or EKG) began with the study of frogs’ legs.
During the 1700s, scientists Luigi Galvani (1737-1798) and Alessandro Volta (1745-1827) used frogs to study muscle action. Their work led to development of the galvanometer (gal-va-NOM-e-ter), which measures current by electromagnetic action.
In 1903, William Einthoven (1860-1927) introduced the string galvanometer. Einthoven’s galvanometer evolved into today’s EKG machine, one of the fundamental tools that cardiologists use to monitor the heart’s rhythms.
Did You Know?
- Coronary heart disease is the largest killer of American men and women. Every 29 seconds someone suffers a coronary problem; every minute someone dies from one.
- Managing heart failure costs Americans between $10 and $15 billion annually.
- Almost 15,000 heart transplants have been done since the 1980s, according to the United Network of Organ Sharing. About 2,500 are performed each year, with many other patients waiting in line.
patients whose arteries suddenly collapse or spasm (contract) and close during angioplasty, setting off a heart attack.
Convenience stores, cafeterias, and snack bars used to post warnings near their microwave ovens for people with pacemakers. Electromagnetic radiation emitted from the microwave ovens sometimes caused current variations in the pacemakers. Pacemakers today are shielded from stray electromagnetic forces and have a backup mode in case of disruption of the main circuit’s programming.
Atherectomy (ath-er-EK-to-mee) is the excision (cutting out) and physical removal of plaque from arteries. It is used in place of or along with balloon angioplasty. Once the balloon is inflated, a miniature cutter whirs forward to scrape deposits from the wall of the vessel like a tiny rotor clearing a clogged drain. Debris is pushed to a special collection chamber, and when the device is withdrawn, the debris comes with it.
Pacemakers can be inserted to restore a regular heartbeat. Advanced devices can sense and respond to changes in body movement, temperature, and breathing rate.
Bypass surgery is a procedure in which a segment of vein taken from the leg or an artery from the chest is grafted to an opening in the side of the normal coronary artery above the obstructed (blocked) segment and then to the normal portion of the artery below the obstruction. Blood then “bypasses” the obstructed segment, much like taking a road detour around a construction site.
Damaged valves can be replaced with mechanical valves made of plastic or Dacron or a biological valve taken from a pig, cow, or human donor.
Cardiac transplantation is the most dramatic means of treating patients with severe heart failure. Although still filled with challenges, the procedure is well accepted around the world and is being performed more often. However, not enough human hearts are available from organ donors.
Heart disease often represents a turning point in a person’s life. People who formerly led unhealthy, mainly inactive lives may be inspired to change the way they live by eating more healthily, exercising regularly, and quitting smoking.
Chewing the Fat
Experts suggest that it is a good idea for all healthy Americans above the age of two to modify their diets. Among specific suggestions are:
- Reduce total dietary fat to no more than 30 percent of total daily calories.
- Reduce dietary saturated fat and cholesterol: switch from whole to skim milk, reduce the number of egg yolks eaten, avoid solid cooking fats like lard, give up foods containing certain vegetable oils such as palm or coconut oils, and substitute frozen yogurt, sherbet, or ice milk for ice cream.
In the case of a heart attack, full recovery generally takes about four to six weeks, depending on the extent of the injury, the patient’s overall health, and the condition of the rest of the heart. Most people are able to resume regular activities within a few weeks or months. Like all patients with heart disease or damage, those who have had heart attacks need to adopt a healthier lifestyle, including eating a low-fat diet. Most go on to recover and enjoy many more productive years of life.
Arnold, Caroline. Heart Disease. Danbury, CT: Franklin Watts, 1992. Describes the heart and circulatory system and both genetic and acquired diseases that can affect the functioning of the heart.
The National Institutes of Health posts information about heart disease on its website at: http://www.nhlbi.nih.gov/health/public/heart/other/chdfacts.htm
"Heart Disease." Complete Human Diseases and Conditions. . Encyclopedia.com. (July 23, 2017). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/heart-disease-0
"Heart Disease." Complete Human Diseases and Conditions. . Retrieved July 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/heart-disease-0
HEART DISEASE. SeeCardiovascular Disease .
"Heart Disease." Dictionary of American History. . Encyclopedia.com. (July 23, 2017). http://www.encyclopedia.com/history/dictionaries-thesauruses-pictures-and-press-releases/heart-disease
"Heart Disease." Dictionary of American History. . Retrieved July 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/history/dictionaries-thesauruses-pictures-and-press-releases/heart-disease