CMP

Any disease that affects the heart muscle, diminishing cardiac performance.

Cardiomyopathy caused by years of heavy alcohol abuse. Affected patients have enlarged hearts and left ventricular failure. Abstinence from alcohol may halt or reverse the course of the illness in some people.

Cardiomyopathy associated with enlargement of the left ventricle of the heart and congestive heart failure.

An autosomal dominant cardiomyopathy marked by excessive and disorganized growth of myofibrils, impaired filling of the heart (diastolic dysfunction), a reduction in the size of ventricular cavities, and, often, ventricular arrhythmias and sudden death. Examination of the heart by echocardiography or other modalities may show the enlargement of the heart to be most pronounced in the interventricular septum. Hypertrophy in that location may limit the flow of blood (and increase pressure gradients) from the left ventricle to the aorta. Abnormal anterior motion of the mitral valve during systole also may be found. These two findings are often designated on echocardiographic reports of patients with HCM by the abbreviation ASH-SAM (asymmetric septal hypertrophy–systolic anterior motion [of the mitral valve]). Other forms of HCM may affect only the cardiac apex or cause diffuse enlargement of the heart muscle. The mass of the left ventricle in HCM is > 500 g. See: illustration

Symptoms and Signs

Although patients may be asymptomatic for many years, they commonly report shortness of breath (particularly on exertion), fatigue, atypical chest pain (at rest and after meals), orthopnea, dizziness, and other symptoms of congestive heart failure after the heart muscle markedly enlarges. An S4 and a harsh crescendo-decrescendo systolic murmur, best heard at the left lower sternal border, may be present. Ventricular arrhythmias are common and may result in palpitations, syncope, or sudden death.

Treatment

Drug therapies include beta blocking and calcium channel blocking drugs (such as verapamil) to slow heart rate, control arrhythmias, and reduce myocardial oxygen demand. Anticoagulants and antiarrhythmic agents are also occasionally used. For patients with marked enlargement of the ventricular septum and high outflow tract pressure gradients (> 50 mm Hg), surgical removal of the enlarged muscle or ablation often produces favorable improvements in exercise tolerance and breathing.

Patient care

Strenuous physical exercise should be discouraged because it may produce breathlessness, presyncope, or frank loss of consciousness. If applicable, the patient should be encouraged to lose weight, stop smoking, and limit alcohol intake. An implanted cardioverter/defibrillator (ICD) may be required. The patient should be advised to report symptoms of chest pain, prolonged dyspnea, or syncope promptly. First-degree relatives of those affected should be referred for evaluation.

Cardiomyopathy of occult or uncertain cause, possibly due to viral infections, unrecognized toxic exposures, or a genetic predisposition, but not to ischemia, hypothyroidism, hypertension, valvular disease, or alcohol abuse.

Treatment

General supportive therapy includes rest, weight control, abstinence from tobacco, and moderate exercise at a level that does not cause symptoms. A salt-restricted diet is recommended. Therapy includes the use of vasodilators, such as ACE inhibitors, and diuretics like furosemide. Anticoagulants are important to prevent thrombus formation. IDC is a principal indication for cardiac transplant.

Enlargement of heart muscle resulting from long-standing or severe hypertension or aortic stenosis. Like all other forms of cardiomyopathy, the end result is heart failure.

Dilated cardiomyopathy occurring either in the last month of pregnancy or in the six months after delivery. Its cause is unknown, but it occurs more often in older and multiparous women.

Cardiomyopathy of unknown cause.

Cardiomyopathy associated with lack of flexibility of the ventricular walls. Common causes include amyloidosis, hemochromatosis, sarcoidosis, and other diseases in which the heart is infiltrated by foreign material or scarred.

Any cardiomyopathy in which the cause is either known or associated with a well-defined systemic disease. Included are cardiomyopathies associated with inflammation, toxic chemicals, metabolic abnormalities, and inherited muscle disorders.

Cardiac remodeling and dysfunction that results from a chronically increased heart rate, usually a supraventricular arrhythmia. It is treated with medications such as beta blockers that slow the heart rate.

Reversible dysfunction of the left ventricle. It may be the cause of transient heart failure that occurs after exceptionally stressful events. The heart in such instances takes on a rounded shape with a narrow neck, resembling a traditional Japanese lobster trap (takotsubo). It is informally called broken-heart syndrome.

A frequently ordered cluster of lab tests, comprising measurements of serum electrolytes (sodium, potassium, chloride, and calcium), renal function (blood urea nitrogen [BUN] and creatinine), acid-base balance (bicarbonate), liver functions, and glucose. The test is obtained by drawing a blood sample from a peripheral vein or, in critical care, from a central vein.