Cardiomyopathy is a chronic disease of the heart muscle (myocardium), in which the muscle is abnormally enlarged, thickened, and/or stiffened. The weakened heart muscle loses the ability to pump blood effectively, resulting in irregular heartbeats (arrhythmias ) and possibly even heart failure.
Cardiomyopathy, a disease of the heart muscle, primarily affects the left ventricle, which is the main pumping chamber of the heart. The disease is often associated with inadequate heart pumping and other heart function abnormalities. Cardiomyopathy is not common (affecting about 50,000 persons in the United States) but it can be severely disabling or fatal. Severe cases may result in heart failure and will require a heart transplant for patient survival. Cardiomyopathy is a heart condition that not only affects middle-aged and elderly persons, but can also affect infants, children, and adolescents.
There are four major types of cardiomyopathy:
- Dilated (congestive cardiomyopathy ). This is the most common form of the disease. The heart cavity is enlarged and stretched (cardiac dilation), which results in weak and slow pumping of the blood, which in turn can result in the formation of blood clots. Abnormal heart rhythms (arrhythmias) and disturbances in the electrical conduction processes in the heart may also occur. Most patients with this type of cardiomyopathy develop congestive heart failure. There is also a genetically-linked cardiac disease, Barth syndrome, that can cause dilated cardiomyopathy. This syndrome affects male children, and is usually diagnosed at birth or within the first few months of life. Pregnant women during the last trimester of pregnancy or after childbirth may develop a type of dilated cardiomyopathy referred to as peripartum cardiomyopathy.
- Hypertrophic cardiomyopathy. With this type of cardiomyopathy, the muscle mass of the left ventricle enlarges, or hypertrophies. In hypertrophic obstructive cardiomyopathy (HOCM), the septum (wall) between the two heart ventricles (the pumping chambers) becomes enlarged and obstructs blood flow from the left ventricle. The thickened wall can also distort one leaflet of the mitral valve, which results in leakage. HOCM is most common in young adults. HOCM is often hereditary, caused by genetic mutations in the affected person's DNA. The disease is either inherited through one parent who is a carrier or through both parents who each contribute a defective gene. HOCM is also referred to as asymmetrical septal hypertrophy (ASH) or idiopathic hypertrophic subaortic stenosis (IHSS). In another form of hypertrophic cardiomyopathy, non-obstructive cardiomyopathy, the enlarged heart muscle does not obstruct the blood flow through the heart.
- Restrictive cardiomyopathy. This is a less common type of cardiomyopathy, in which the heart muscle of the ventricles becomes rigid. Restrictive cardiomyopathy affects the diastolic function of the heart, that is, it affects the period when the heart is relaxing between contractions. Since the heart cannot relax adequately between contractions, it is harder for the ventricles to fill with blood between heartbeats. This type of cardiomyopathy is usually the result of another disease.
- Arrhythmogenic right ventricular cardiomyopathy (ARVC). ARVC is very rare and is believed to be an inherited condition. With ARVC, heart muscle cells become disorganized and damaged and are replaced by fatty tissues. The damage appears to be a result of the body's inability to remove damaged cells. The damaged cells are replaced with fat, leading to abnormal electrical activity (arrhythmias) and abnormal heart contractions. ARVC is the most common cause of sudden death in athletes.
Causes & symptoms
Cardiomyopathy may be caused by many different factors, including viral infections (e.g., myocarditis ), heart attacks, alcoholism, long-term, severe high blood pressure, genetic neuromuscular diseases (e.g., muscular dystrophies and ataxias), genetic metabolic disorders, complications from AIDS, and other reasons that have not yet been identified (idiopathic cardiomyopathy). Cardiomyopathy caused by heart attacks (referred to as ischemic cardiomyopathy) results from scarring in the heart muscle. Larger scars or more numerous heart attacks increases the risk that ischemic cardiomyopathy will develop. Alcoholic cardiomyopathy usually develops about 10 years after sustained, heavy alcohol consumption. Other toxins that may cause cardiomyopathy include drugs and radiation exposure.
The major symptoms of cardiomyopathy include:
- shortness of breath
- temporary and brief loss of consciousness, especially after engaging in activity
- lightheadness, especially after engaging in activity
- decreased ability to tolerate physical exertion
- palpitations, that is, the sensation of feeling the heart beat
- chest pain (angina), whereby there is a feeling of sharp and unrelenting pressure in the middle of the chest (especially experienced by persons whose cardiomyopathy is a result of a previous heart attack )
- high blood pressure
Other symptoms that may be associated with cardiomyopathy include:
- abdominal swelling or enlargement
- swelling of legs or ankles
- low amount of urine during the daytime, but a need to urinate at night
- decreased alertness and difficulty concentrating
- loss of appetite
A complete physical examination and health history review by a health care provider is recommended if a person is suspected to have cardiomyopathy. The examination may reveal the presence of an irregular heartbeat, heart murmur, or other abnormal heart and breath sounds.
Various invasive and non-invasive tests are performed as diagnostic tools for cardiomyopathy. An echocardiogram is the most informative noninvasive test for diagnosing the type of cardiomyopathy and the degree of dysfunction in the heart muscle. High frequency sound waves produce moving images of the beating heart on a video screen, which allows the measurement of muscle thickness, size, pumping ability, degree of obstruction, chamber size, and heart valve movement.
The use of non-invasive radiation-based imaging procedures, such as chest radiography, computed tomography (CT), or magnetic resonance imaging (MRI) procedures show the size, shape, and structure of the heart. If dilated cardiomyopathy is suspected, one of these techniques is performed first to see if the heart is enlarged and whether there is any fluid accumulation in the lungs.
An electrocardiogram (EKG) is a non-invasive procedure where electrodes are placed on the person's limbs and chest wall to provide a graphic record of the electrical activity of the heart. This test can show the amount of heart enlargement and reveal abnormal heart rhythms. Children with a normal echocardiogram may have an abnormal EKG, indicating that they may be a carrier of the cardiomyopathy gene and may develop the disease later in life. A person may also wear a Holter monitor, which is an external device that continuously records heart rhythms. The monitor can identify irregular heart rhythms associated with dilated, hypertrophic, or restrictive cardiomyopathy.
Genetic studies may help in understanding the cause of cardiomyopathy, since the disease may be a symptom of another genetic disorder. If a child under the age of 4 has cardiomyopathy, metabolic screening should be performed, for certain metabolic disorders with cardiomyopathy as a symptom can be controlled with a change in diet, drug therapy, or by a bone marrow transplant, which may reduce or reverse the progression of the cardiomyopathy. Since cardiomyopathy can be inherited and present initially without signs or symptoms, relatives of a patient with the disease should be screened periodically for evidences of the disease.
Invasive procedures, which involve the use of anesthesia, are used to determine the severity of the disease. In the radionuclide ventriculogram procedure, a low-dose radioactive material is injected into a vein and flows to the heart. The heart is photographed with a special camera to assess the contraction and filling of the ventricles at rest and with activity. Cardiac catheterization involves insertion of thin, flexible plastic tubes (catheters) into the heart from a blood vessel in the groin area. A dye is then injected that can indicate blood pressures, blood flow within the heart, and blockages in the arteries. Although rarely used, a heart muscle biopsy, where the doctor removes a few, tiny pieces of the heart for laboratory studies, can aid in diagnosing possible infections in the heart or metabolic abnormalities. An electrophysiology study is similar to heart catheterization. Catheters with fine wires are inserted through veins in the groin area into the heart. Electrical stimuli applied through the wires can indicate abnormal conduction pathways, arrhythmias, effectiveness of drugs, and the need for an implanted defibrillator.
Although there is a long list of possible causes for cardiomyopathy, few are directly treatable or curable. Therefore, most therapy is directed towards treating the effects of the disease on the heart. If cardiomyopathy is diagnosed at an advanced stage, a critically ill patient will require immediate life-saving measures such as placement of a breathing tube and administration of medicines to improve heart function and blood pressure. Once the patient is stabilized, long-term therapy needs, such as oral medication, pacemakers, surgery, or heart transplantation, will be identified.
Initial treatments for cardiomyopathy for patients diagnosed in the earlier stages of cardiomyopathy include drug therapy to relieve heart failure, to decrease oxygen requirements and workload of the heart (by relaxing the arteries in the body), and to regulate abnormal heartbeats. Drugs that help the heart contract include digoxin for at-home use and dopamine, dobutamine, and milrinone for in-hospital use. Diuretics help relieve fluid overloads in heart failure. Vasodilators, ACE-inhibitors, and beta blockers dilate blood vessels in the body and lower blood pressure, thus reducing the workload for the heart. For patients at risk of developing blood clots, anticoagulation medication or blood thinners such as heparin or coumadin are prescribed along with diuretics such as Lasix and aldactone to relieve venous congestion. These drugs may result in side effects, so the patient must be carefully monitored to prevent complications.
When drugs are not effective or when arrhythmias require regulation, a pacemaker or a defibrillator may be implanted surgically into the patient. The procedures for implanting both devices involves placing a small mechanical device under the skin of the chest or abdomen with wire leads threaded through veins to the heart. A pacemaker is used to monitor and stabilize slow heartbeats, while a defibrillator ("an emergency room in the heart") detects and treats fast and potentially lethal heart rhythms. Since sudden death may occur in patients with cardiomyopathy, defibrillators are often recommended for persons who show evidence of arrhythmias.
For heart failure symptoms associated with restricted blood flow from the ventricles, septal myomectomy, which is considered major heart surgery, is sometimes recommended. This procedure involves surgical removal of the part of the thickened septal muscle that blocks the blood flow. In some cases, the mitral valve is replaced with an artificial valve. However, the procedure does not prevent sudden death due to hear arrhythmias nor does it stop the disease from progressing.
Since cardiomyopathy often becomes progressively worse, the heart can reach a state where it no longer responds to medication or to surgery. The treatment of "last resort" is a heart transplant, when the patient exhibits severe heart failure symptoms. A transplant can cure the symptoms of heart failure, but the surgery carries significant risks, such as infection, organ rejection, and side effects of required medications.
There are surgical procedures that can be implemented to sustain life until a transplant donor becomes available. Left Ventricular Assist Device (LVAD) provides mechanical circulatory support, while Dynamic Cardiomyoplasty is a procedure whereby a skeletal-muscular flap, created from a patient's chest muscle, is first taught to contract and then is wrapped around the heart to aid in contraction.
Alternative treatments are directed towards control of the effects of heart disease. Exercise, diet, nutrition, herbal therapies, stress reduction, and other life style changes (e.g., cessation of smoking ) can all be used to complement conventional treatments. Certain herbs such as fox glove (Digitalis purpurea ) and lily of the valley (Convallaria majalis ) contain cardiac glycosides that make them particularly potent and may cause dangerous side effects. Their use should be supervised only be a qualified medical herbalist, with the concurrence of the primary conventional health care provider. Even the use of less potent herbs that improve cardiac function, such as hawthorn (Crataegus laevigata ), should be approved by the conventional health care provider and administered under the supervision of a medical herbalist.
Long-term prognosis can be unpredictable, as there can be a wide range of severities and outcomes associated with the disease. There is no cure, but some symptoms and complications can be managed and controlled with medication and implantable devices or with a heart transplant.
Prevention of cardiomyopathy is focused on controlling risk factors for heart disease, which includes maintaining a healthy weight, exercising regularly, eating a well-balanced nutritious diet, and avoiding or minimizing smoking.
Arrhythmia— An abnormal rhythm or irregularity of the heartbeat. The heartbeat may either be too fast (tachycardia) or too slow (bradicardia). Arrhythmias may cause symptoms such as palpitation or light-headedness, but many have more serious consequences, including sudden death.
Congestive heart failure— Potentially lethal condition in which congestion develops in the lungs that is produced by a heart attack, poorly controlled or uncontrolled hypertension, or disease processes that weaken the heart
Hypertrophy— Literally means an increase in the muscle mass (or weight) of the heart.
Mitral valve leaflets— The mitral valve is made up of two valve leaflets (the anteromedial leaflet and the posterolateral leaflet) and a ring around the valve, known as the mitral valve annulus. The orientation of the two leaflets resembles a bishop's miter, which is where the valve receives its name.
Myocardium— The muscular wall of the heart located between the inner endocardial layer and the outer epicardial layer.
Noninvasive— Refers to tests that generally do not invade the integrity of the body, such as echocardiography or electrocardiography. (Cardiac cathetherization, on the other hand, in which catheters are introduced through blood vessels into the heart, is an example of an invasive test).
Septum (ventricular septum)— That portion of the heart wall that divides the right and left ventricles.
Ventricles— The two main (lower) pumping chambers of the heart; the right and left ventricles pump blood to the lungs and aorta, respectively.
Dilated Cardiomyopathy: A Medical Dictionary, Bibliography, and Annotated Research Guide to Internet Resources. San Diego, CA: Icon Health Publications, 2004.
Maron, Barry J., and Salberg, Lisa. Hypertrophic Cardiomyopathy: For Patients, Their Families, and Interested Physicians. Malden, MA: Futura Media Services, 2001.
Parker, J.M., and Parker, P.M. The Official Patient's Sourcebook on Dilated Cardiomyopathy. San Diego, CA: Icon Health Publications, 2002.
Ommen, Steve R., and Nishimura, Rick A. "A Physician's Guide to the Treatment of Hypertrophic Cardiomyopathy." HeartViews 1(10): 393-401. 〈http://www.mayoclinic.org/hypertrophic-cardiomyopathy/physiciansguide.html〉.
Hypertrophic Cardiomyopathy Association, P.O. Box 306 Hibernia NJ 07842. Telephone: (973) 983-7429; 〈http://www.4hcm.org/〉.
Cleveland Clinic Heart Center. 〈http://www.clevelandclinic.org/heartcenter/pub/guide/disease/hcm.asp〉.
National Heart, Blood, and Lung Institute, National Institutes of Health, NHLBI Health Information Center, P.O. Box 30105, Bethesda, MD 20824-0105. Telephone: (301) 592 8573; 〈http://www.nhlbi.nih.gov〉.
Heart Center Online. 〈http://www.heartcenteronline.com〉.
"Cardiomyopathy." Gale Encyclopedia of Medicine, 3rd ed.. . Encyclopedia.com. (July 10, 2018). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/cardiomyopathy
"Cardiomyopathy." Gale Encyclopedia of Medicine, 3rd ed.. . Retrieved July 10, 2018 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/cardiomyopathy
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The Chicago Manual of Style
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Cardiomyopathy is a type of heart disease in which the heart muscle is abnormally enlarged, thickened and/or stiffened. As a result, the heart muscle's ability to pump blood is usually impaired.
When the heart muscle enlarges and is unable to pump effectively, its function declines. This is called congestive heart failure. Congestive heart failure results in a reduction in oxygen delivery to the tissues and a backup of fluid into those tissues. Fluid in the lungs can cause shortness of breath with exertion and a need to sleep with the head elevated. Fluid buildup in other areas can manifest itself as swelling of the feet and ankles or swelling and pain in the liver. Congestive heart failure once carried a grim prognosis, but new advances in medical treatment have improved that prognosis significantly.
People with cardiomyopathy can develop an abrupt buildup of fluid in the lungs, called acute pulmonary edema. This is a medical emergency. In addition to intravenous medications that remove fluid, support blood pressure, and strengthen the heart's pumping function, acute pulmonary edema is also treated with oxygen and sometimes the temporary use of a respirator.
Almost anything that can damage the heart muscle fibers can produce cardiomyopathy and congestive heart failure. Long-standing high blood pressure, diabetes, heart attacks, alcohol, drugs, and certain viruses are all causes of cardiomyopathy.
In a person with cancer, cardiomyopathy and its symptoms are generally due to the adverse effects of treatment.
Among the causes of cardiomyopathy in cancer patients is radiation therapy to the chest, which is often employed for breast cancer , cancer of the esophagus or lymphoma . Children who receive radiation therapy to the spinal column can suffer late effects to their hearts. The radiation can damage the heart muscle, leading to cardiomyopathy and heart failure. It can also damage the coronary arteries, leading to angina or a heart attack.
More commonly, cardiomyopathy in a cancer patient is an adverse effect of chemotherapy . Among the chemotherapeutic drugs known to be toxic to the heart are:
- Mitomycin C
The drugs most frequently associated with cardiotoxicity are doxorubicin and daunorubicin, which are anthracyclines. The total cumulative dose of anthracyclines a person receives determines the likelihood of developing chronic cardiomyopathy. In a few cases, these agents will cause an acute cardiotoxic effect, with symptoms such as abnormal heart rhythms and electrocardiogram changes.
Patients receiving anthracyclines have nuclear imaging scans of their hearts before starting treatment, during treatment and after treatment, since the adverse effects can be delayed. These studies measure the heart's ejection fraction, which is the percentage of blood volume pumped with each heartbeat. A normal ejection fraction is around 60%. In other words, 60% of the blood that collects in the heart between heartbeats is pumped out with each beat. Anthracyclines can cause a significant reduction in ejection fraction and therefore in heart function.
Often used for colon, breast, and head and neck cancers , 5-fluorouracil can cause cardiotoxicity, mostly in those patients with existing coronary artery disease or those who are also receiving radiation therapy to the chest. Cyclophosphamide, often used in those who have had bone marrow transplants, is another cause of cardiomyopathy. The taxanes, paclitaxel and docetaxel, are newer agents often used for breast and ovarian cancers. Taxanes can cause slowing of the heart rate, but this is not usually serious or prolonged.
Trastuzumab is a monoclonal antibody used in some patients with breast cancer. About 30% of women have overexpression of human epidermal growth factor receptors, called HER-2, on the surface of their cancer cells. Trastuzumab selectively attacks those receptors. Heart muscle also has some HER-2 receptors, which is believed to be the reason that trastuzumab can cause cardiomyopathy. Trastuzumab is often used in conjunction with anthracyclines or taxanes, both of which have effects on the heart, and patients on these drugs must be carefully monitored for signs of heart disease.
The diagnosis of cardiomyopathy is made on the basis of the history and physical examination, along with tests of heart function. Occasionally, biopsies of the heart muscle are performed to confirm the diagnosis.
Other forms of damage to the heart can occur with cancer and its treatments. Some cancers can metastasize to the heart muscle or the valves within the heart. Cancers that spread to the pericardium, the outer lining of the heart, can induce fluid collections called pericardial effusions.
High-output cardiac failure is an unusual form of heart failure that results when the body senses a lowered total blood volume. This can occur with anemia , a side effect of many treatments, or with large tumors that have large numbers of blood vessels, drawing blood away from the general circulation.
Amyloidosis is a condition in which abnormal proteins are deposited in tissues throughout the body, including the heart. Amyloidosis is seen with multiple myeloma .
Abnormal heart rhythms can occur due to toxic effects of chemotherapeutic drugs and perhaps radiation treatments on the electrical conducting system of the heart.
The treatment of cardiomyopathy in cancer patients consists of removing the cause when possible and using cardiac medications to reduce symptoms.
Since the most common cause of cardiomyopathy in cancer patients is due to the use of anthracyclines, oncologists keep a careful record of the total dose administered to patients over the course of their treatment, and stop the drug before the known toxic dose has been reached.
Newer forms of anthracyclines have been formulated which are called liposome encapsulates. These have been shown to be less toxic to the heart and still effective against cancer. Administering anthracyclines weekly, rather than every three to four weeks, and giving the dose more slowly both seem to reduce the cardiac toxicity. The simultaneous administration of drugs that might protect the heart is under study, but their use is not yet recommended routinely.
The treatment of an established cardiomyopathy and heart failure due to cancer treatment is a combination of medications that are used for heart failure of any origin. One of these is digoxin, which improves the heart's pumping function in addition to other beneficial effects. Diuretics, often called water pills, flush water and salt from the body and are used to reduce swelling. Angiotensin-converting enzymes or ACE inhibitors comprise the third group of drugs useful for heart failure. These relax the arteries, which reduces the work that the heart must do to effectively pump blood. The fourth group of medications includes beta-blockers, which slow the heart rate and reduce its workload. This combination of medications has significantly improved the prognosis for people with heart failure.
Lifestyle changes can reduce symptoms of heart failure. Reducing salt and fluid intake and avoiding alcohol are beneficial. A judicious exercise plan can increase stamina without overtaxing a failing heart. Many people who have undergone cancer treatment also have coronary artery disease, which can aggravate the symptoms of heart failure caused by chemotherapy toxicity. Patients whose cancer prognosis is good can sometimes benefit from treatment of their coronary artery disease.
Some patients whose cancer is cured but whose cardiomyopathy progresses despite medication are candidates for heart transplant.
Alternative and complementary therapies
Naturopaths might prescribe hawthorn for symptoms of congestive heart failure. No studies have demonstrated either benefit or harm from this preparation.
Acupuncture and acupressure are sometimes beneficial in reducing symptoms of shortness of breath and may offer some relief to those with heart failure due to cardiomyopathy. The pressure point for the heart is said to be on the palm of the hand, over the bones between the fourth and fifth fingers.
Dodd, Marylin J. Managing the Side Effects of Chemotherapy and Radiation Therapy: A Guide for Patients and Their Families. San Francisco: University of California at San Francisco School of Nursing, 1996.
McKay, Judith, and Nancee Hirano. The Chemotherapy and Radiation Therapy Survival Guide (Chemotherapy and Radiation Therapy Survivor's Guide, 2nd Ed). Oakland: New Harbinger Publications, 1998.
Moore, Katen, and Libby Schmais. Living Well with Cancer: A Nurse Tells You Everything You Need to Know About Managing the Side Effects of Your Treatment. New York: Putnam Publishing Group, 2001.
Ginsburg, A.D. "Doxorubicin-induced Cardiomyopathy." New England Journal of Medicine 340, no. 8 (February, 1999): 654.
Heart Center Online Home Page. 6 June 2001 <http://www.heartcenteronline.com/> This website serves cardiologists and their patients and has sections on pericardiocentesis, pericarditis and tamponade.
Marianne Vahey, M.D.
Acute pulmonary edema
—An abrupt collection of fluid in the lungs due to failure of the heart muscle to pump blood properly.
Angiotensin converting enzyme inhibitors
—Medications that lower blood pressure and reduce the work load of the heart muscle.
—Medications that relax blood vessels and slow the heart rate.
Congestive heart failure
—A condition that results from inadequate pumping action of the heart muscle, causing fluid buildup in lungs and tissues.
—Medications, often called water pills, that eliminate excess water and salts from the body.
—The percentage of the blood sitting in the heart between heartbeats that gets pumped to the body with each heartbeat.
"Cardiomyopathy." Gale Encyclopedia of Cancer. . Encyclopedia.com. (July 10, 2018). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/cardiomyopathy-0
"Cardiomyopathy." Gale Encyclopedia of Cancer. . Retrieved July 10, 2018 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/cardiomyopathy-0
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"cardiomyopathy." A Dictionary of Nursing. . Encyclopedia.com. (July 10, 2018). http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/cardiomyopathy
"cardiomyopathy." A Dictionary of Nursing. . Retrieved July 10, 2018 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/cardiomyopathy
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"cardiomyopathy." A Dictionary of Food and Nutrition. . Encyclopedia.com. (July 10, 2018). http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/cardiomyopathy
"cardiomyopathy." A Dictionary of Food and Nutrition. . Retrieved July 10, 2018 from Encyclopedia.com: http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/cardiomyopathy