Cardiomyopathy

Cardiomyopathy is an ongoing disease process that damages the muscle wall ofthe lower chambers of the heart. About 50,000 Americans develop cardiomyopathy each year. Congestive cardiomyopathy is the most common form of cardiomyopathy. In congestive cardiomyopathy, also called dilated cardiomyopathy, the walls of the heart chambers stretch (dilate) to hold a greater volume of bloodthan normal. Another form of cardiomyopathy, hypertrophic cardiomyopathy, causes the walls of the heart's chambers to thicken abnormally.

Congestive cardiomyopathy is the final stage of many heart diseases and the most common condition resulting in congestive heart failure. It may becaused by a number of conditions, including coronary artery disease, infections, noninfectious inflammatory conditions, alcohol and other drugs or toxins,hypertension, nutritional and metabolic disorders, and pregnancy.

Infections caused by bacteria, viruses, and other microorganisms can involvethe heart, causing inflammation of the heart muscle (myocarditis). The inflammation may damage the heart muscle and cause congestive cardiomyopathy. In the United States, the coxsackievirus B is the most common cause of viral congestive cardiomyopathy.

Myocarditis can also be caused by noninfectious disorders. For example, the conditions sarcoidosis, granulomatous myocarditis, and Wegener's granulomatosis cause inflammation and tissue death in the heart muscle.

When the heart muscle is damaged, it cannot pump enough blood to meet the body's needs. Uninjured areas of the walls of the two lower heart chambers (called ventricles) stretch to make up for the lost pumping action. At first, theenlarged chambers allow more blood to be pumped with less force. The stretched muscle can also contract more forcefully. Over time, the heart muscle continues to stretch, ultimately becoming weaker. The heart is forced to work harder to pump blood by beating faster. Eventually it cannot keep up and blood backs up into the veins, legs, and lungs. When this happens, the condition is called congestive heart failure.

Congestive cardiomyopathy usually affects both ventricles. Blood backed up into the lungs from the left ventricle causes fluid to congest the lung tissue.This is called pulmonary edema. When the right ventricle fails to pump enough blood, blood backs up into the veins causing edema in the legs, feet, ankles, and abdomen.

Congestive cardiomyopathy is usually a chronic condition, developing gradually over time. Patients with early congestive cardiomyopathy may not have symptoms. The most common symptoms are fatigue and shortness of breath on exertion. Patients with more advanced congestive cardiomyopathy may also have chest or abdominal pains, extreme tiredness, dizziness, and swelling of the legs andankles. sudden cardiac death is not uncommon with this condition. It stems from irregular heart rhythms in the ventricles (ventricular arrhythmias).

When a patient is diagnosed with congestive cardiomyopathy, physicians try tofind out the cause. If coronary artery disease is not the culprit, in most other cases a cause is not identified. When a condition responsible for the congestive cardiomyopathy is diagnosed, treatment is aimed at correcting the underlying condition. Congestive cardiomyopathy caused by drinking excess alcohol or by drugs or toxins can be treated by eliminating the alcohol or toxin completely. In some cases, the heart may recover after the toxic substance isremoved from the body. Bacterial myocarditis is treated with an antibiotic toeliminate the bacteria.

There is no cure for idiopathic congestive cardiomyopathy. Medicines are given to reduce the workload of the heart and to relieve the symptoms. These include digitalis, diuretics, vasodilators, beta blockers, angiotensin convertingenzyme inhibitors (ACE inhibitors), and angiotensin receptor blockers. Whenthe heart muscle is damaged so severely that medicines cannot help, a heart transplant may be required.

Hypertrophic cardiomyopathy, also called idiopathic hypertrophic subaortic stenosis and asymmetrical septal hypertrophy, usually appears in young people, often in athletes. For this reason it is sometimes called athletic heart muscle disease. However, people of any age can develop hypertrophic cardiomyopathy.

The cause of hypertrophic cardiomyopathy is not known. In about one-half of cases, the disease is inherited. Hypertrophic cardiomyopathy is the result ofabnormal growth of the heart muscle cells. The wall between the heart's chambers (the septum) may become so thickened that it blocks the flow of blood through the lower left chamber (left ventricle). The thickened wall may push onthe heart valve between the two left heart chambers (mitral valve), making itleaky. The thickened muscle walls also prevent the heart from stretching asmuch as it should to fill with blood.

Often people with hypertrophic cardiomyopathy have no symptoms. Unfortunately, the first sign of the condition may be sudden death caused by an abnormal heart rhythm. The American Heart Association reports that 36% of young athletes who die suddenly have probable or definite hypertrophic cardiomyopathy. When symptoms do appear, they include shortness of breath on exertion, dizziness, fainting, fatigue, and chest pain.

Treatment of hypertrophic cardiomyopathy usually consists of taking medicinesand restricting strenuous exercise. Drugs called beta blockers and calcium channel blockers are usually prescribed. Antiarrhythmic drugs may also be given to prevent abnormal heart rhythms. If the medications do not help relieve symptoms, surgery to help improve blood flow in the heart chambers may help. Some patients have pacemakers and/or defibrillators implanted to help controlthe heart rate and rhythm. Pacemakers and defibrillators provide electrical impulses to the heart, which can return the heart beat to a normal rhythm. Ifthese treatment methods fail and a patient develops heart failure, a heart transplant may be necessary.

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