A form of cardiomyopathy ( heart disease ) involving enlargement of the heart muscle , which is out of proportion to any workload on the heart, with the enlargement interfering with the functioning of the heart.

Alternative Names

Cardiomyopathy - hypertrophic; IHSS; Idiopathic hypertrophic subaortic stenosis; Hypertensive hypertrophic cardiomyopathy

Causes, incidence, and risk factors

The heart enlargement of hypertrophic cardiomyopathy is often asymmetrical, affecting one side of the heart more than other parts of the heart. It may interfere with the functioning of the heart by narrowing the outflow of the ventricle and the size of the ventricular chamber, and by reducing the ability of the valves to function properly. The enlargement may in certain circumstances cause obstruction of the flow of blood out of the heart. The obstruction is worsened by situations that increase contraction of the heart (examples include stress , stimulation of the sympathetic nervous system, or medications such as digoxin) or situations that decrease return of blood to the heart (for example, dehydration or excessive use of diuretics). Two forms of the disease occur:

IHSS (idiopathic hypertrophic subaortic stenosis): an early form of the disease that is often diagnosed before the age of 40 and may occur before the age of 10. About half the cases are inherited with autosomal dominant transmission. The other half occur without known genetic inheritance. The

incidence is about 1 out of 10,000 people. The term "idiopathic" means there is no known cause.

An acquired form that occurs in elderly people with a history of

high blood pressure (hypertensive hypertrophic cardiomyopathy).

Signs and tests

Listening with a stethoscope may reveal abnormal heart sounds . Examining the chest by touching and tapping ( palpation and percussion ) may indicate enlargement of the heart or "double" heartbeat (bifid impulse). Left ventricular enlargement with normal or increased contractility, and obstruction of blood flow may be shown on:

echocardiography

(the most common test).

Doppler ultrasound

.

A

coronary angiography may be needed to confirm the diagnosis.

A

chest X-ray may or may not show changes.

An

ECG may indicate left ventricle enlargement, arrhythmias , MI , and/or ischemic changes.

A

heart biopsy may be helpful to distinguish hypertrophic cardiomyopathy from other diseases. Lab tests are not specifically diagnostic for hypertrophic cardiomyopathy, but tests may be used to rule out other suspected diseases.

Treatment

Treatment is aimed at control of symptoms. Hospitalization may be required until the condition is stabilized. Medications include beta-blockers. Calcium channel blockers such as verapamil may be added. Anti-arrhythmics may be used to prevent lethal arrhythmias . Surgical removal of part of the enlarged tissue may be helpful in severe cases.

Expectations (prognosis)

The outcome varies. Some affected individuals remain without symptoms for many years and have a normal life span. Patients with hypertrophic cardiomyopathy are at higher risk for sudden death than the normal population, and can be affected at a young age. Hypertrophic cardiomyopathy is, for example, a well publicized cause of sudden death in athletes. Some may deteriorate gradually or rapidly. There may be progression into dilated cardiomyopathy .

Complications

congestive heart failure

cardiac

arrhythmias , including lethal arrhythmias

dilated cardiomyopathy

Calling your health care provider

Call for an appointment with your health care provider if:

symptoms indicate hypertrophic cardiomyopathy may be present.

chest pain

,

palpitations , faintness , or other new or unexplained symptoms develop.

Prevention

Identify, by family history, which people are at high risk for the genetic form of the disease. Some patients with mild forms of hypertrophic cardiomyopathy are only diagnosed by screening echocardiograms because of their known family history. Treat known hypertension .