Hypertrophic Cardiomyopathy

Kypertrophic cardiomyopathy is a group of heart disorders in which the walls of the ventricles thicken.

Hypertrophic cardiomyopathy may occur as a birth defect. It also may occur in adults with acromegaly, a condition resulting from excessive growth hormone in the blood, or in people who have pheochromocytoma, a tumor that produces adrenaline. People with neurofibromatosis, a hereditary condition, may also develop hypertrophic cardiomyopathy.

Usually, any thickening of the muscular walls of the heart represents the muscle's reaction to an increased workload. Typical causes include high blood pressure, narrowing of the aortic valve (aortic valve stenosis), and other conditions that increase resistance to blood flow from the heart. But people who have hypertrophic cardiomyopa-thy don't have these conditions. Instead, the thickening in hypertrophic cardiomyopathy usu-ally results from an inherited genetic defect.

The heart becomes thicker and stiffer than nor-mal and more resistant to filling with blood from the lungs. One result is back pressure in the lung veins, which can cause fluid to accumulate in the lungs, so the person is chronically short of breath. Also, as the ventricle walls thicken, they may block the flow of blood, preventing the heart from filling properly.

Symptoms and Diagnosis

Symptoms include faintness, chest pain, palpitations produced by irregular heartbeats, and heart failure with shortness of breath. Sudden death may result from irregular heartbeats.

A doctor can usually identify hypertrophic cardiomyopathy by physical examination. For in-stance, the heart sounds heard through a stethoscope are usually characteristic.

The diagnosis usually is confirmed by an echocardiogram, electrocardiogram (ECG), or chest x-ray. Cardiac cath-eterization to measure pressures within the heart may be necessary if surgery is being considered.

Prognosis and Treatment

About 4 percent of people with hypertrophic cardiomyopathy die each year. Death is usually sudden. Death from chronic heart failure is less common. People who learn that they've inherited this disorder may wish to obtain genetic counseling when planning a family.

Treatment is aimed primarily at reducing the heart's resistance to filling with blood between heartbeats. Taken alone or together, beta-blockers and calcium channel blockers are the main treatment. Surgery to remove some heart muscle improves the outflow of blood from the heart, but it's performed only on people whose symptoms are incapacitating despite drug therapy. Surgery can relieve symptoms, but it doesn't lower the risk of death.

Before dental work or a surgical procedure, antibiotics may be given to reduce the risk of infection of the inside lining of the heart (infective endocarditis).