Text A. Dilated Congestive Cardiomyopathy

 

Dilated congestive cardiomyopathy is a group of heart disorders in which the ventricles enlarge but aren't able to pump enough blood for the body's needs, resulting in heart failure.

The most common identi­fiable cause of dilated congestive cardiomyopathy is widespread coronary artery disease. Such coronary artery disease results in inadequate blood supply to the heart muscle, which can lead to permanent injury. The remaining uninjured heart muscle then stretches to compensate for the lost pumping action. When this stretching doesn't adequately compensate, dilated conges­tive cardiomyopathy develops.

An acute inflammation of the heart muscle (myocarditis) from a viral infection may weaken the heart muscle and produce dilated congestive car­diomyopathy (sometimes called viral cardiomy­opathy). Certain chronic hormonal dis­orders such as diabetes and thyroid disease can eventually result in dilated congestive cardiomy­opathy. Dilated congestive cardiomyopathy also can be caused by drugs such as alcohol, cocaine, and antidepressants. Alcoholic cardiomyopathy may develop after about 10 years of heavy alcohol abuse. Rarely, pregnancy or connective tissue dis­eases such as rheumatoid arthritis may cause di­lated congestive cardiomyopathy.

Symptoms and Diagnosis

The usual first symptoms of dilated congestive cardiomyopathy—becoming short of breath on exertion and tiring easily—result from a weaken­ing of the heart's pumping action (heart failure). When cardiomyopathy results from an infection, the first symptoms may be a sudden fever and flulike symptoms. Whatever the cause, the heart rate speeds up, blood pressure is normal or low, fluid is retained in the legs and abdomen, and the lungs fill with fluid. The enlargement of the heart causes the heart valves to open and close im­properly, and those leading to the ventricles (the mitral and tricuspid valves) often leak. Improper valve closure causes murmurs, which a doctor can hear with a stethoscope. Damage to and stretching of the heart muscle may make the heart rhythm abnormally fast or slow. These abnormal­ities interfere further with the heart's pumping action.

The diagnosis is based on the symptoms and a physical examination. Electrocardiography (a test that examines the electrical activity of the heart) may show characteristic changes. Echocardiography (a test that uses ultrasound waves to create an image of the heart structures) and magnetic resonance imaging (MRI) may be used to confirm the diagnosis. If the diagnosis remains in doubt, a catheter that measures pressures is inserted into the heart for more precise evaluation. During catheterization, a tissue sample can be removed for microscopic examination (bi­opsy) to confirm the diagnosis and often to detect the cause.

Prognosis and Treatment

About 70 percent of people with dilated congestive cardiomyopathy die within 5 years of when their symptoms begin, and the prognosis worsens as the heart walls become thinner and heart function decreases. Abnormal heart rhythms also indicate a worse prognosis. Overall, men survive only half as long as women, and blacks half as long as whites. About 50 percent of the deaths are sudden, probably resulting from an abnormal heart rhythm.

Treating specific underlying causes such as al­cohol abuse or an infection can prolong life. If alcohol abuse is the cause, the person must ab­stain from alcohol. If a bacterial infection causes sudden inflammation of the heart muscle, it's treated with an antibiotic.

In a person with coronary artery disease, the poor blood supply may cause angina (chest pain caused by heart disease), requiring treatment with a nitrate, beta-blocker, or calcium channel blocker. Beta-blockers and calcium channel blockers may reduce the force of heart contrac­tions. Getting enough rest and sleep and avoiding stress help reduce strain on the heart.

Pooling of blood in the swollen heart may cause clots to form on the chamber walls. Anticoagulant drugs are usually given to prevent clotting. Most drugs used to prevent abnormal heart rhythms are prescribed in small doses, and the doses are adjusted in small increments because the drugs may reduce the force of heart contractions. Heart failure also is treated with drugs — an angiotensin converting enzyme inhibitor, often with a diuretic. However, unless a specific cause of the dilated congestive cardiomyopathy can be treated, the heart failure is likely to eventually be fatal. Be­cause of this poor prognosis, dilated congestive cardiomyopathy is the most common reason for heart transplants.

Notes:

improperly неправильно

abstain воздерживаться

adjust регулировать; приспосабливать

increment увеличение; прирост