Heart, disorders of

A wide range of disorders can disrupt the heart’s action. In general, genetic factors do not play a large part in causing heart disorders, however they do contribute to the hyperlipidaemias that predispose a person to atherosclerosis and coronary artery disease. Structural abnormalities in the heart are among the most common birth defects (see heart disease, congenital). Infections after birth may result in endocarditis or myocarditis. Tumours arising from the heart tissues are rare. They include noncancerous myxomas and cancerous sarcomas. The heart muscle may become thin and flabby from lack of protein and calories. Thiamine (vitamin B) deficiency, common in alcoholics, causes beriberi with congestive heart failure. Alcohol poisoning over many years may cause a type of cardiomyopathy. Obesity is an important factor in heart disease, probably through its effect on other risk factors, such as hypertension, diabetes, and cholesterol. The coronary arteries may become narrowed due to atherosclerosis, depriving areas of heart muscle of oxygen. The result may be angina pectoris or, eventually, a myocardial infarction. Some drugs, such as the anticancer drug doxorubicin, tricyclic antidepressants, and even drugs used to treat heart disease, may disturb the heartbeat or damage the heart muscle. Many common and serious heart disorders may be a complication of an underlying condition, such as cardiomyopathy or a congenital defect. Such disorders include cardiac arrhythmia, some cases of heart block, and heart failure. Cor pulmonale is a failure of the right side of the heart as a consequence of lung disease.