Hypertrophic Cardiomyopathy

Updated:Jul 6,2016

Hypertrophic cardiomyopathy (HCM) is very common and can affect people of any age. It affects men and women equally. It is a common cause of sudden cardiac arrest in young people, including young athletes.

Hypertrophic cardiomyopathy occurs if heart muscle cells enlarge and cause the walls of the ventricles (usually the left ventricle) to thicken. The ventricle size often remains normal, but the thickening may block blood flow out of the ventricle. If this happens, the condition is called obstructive hypertrophic cardiomyopathy.

Sometimes the septum, the wall that divides the left and right sides of the heart, thickens and bulges into the left ventricle. This can block blood flow out of the left ventricle. Then  the ventricle must work hard to pump blood. Symptoms can include chest pain, dizziness, shortness of breath, or fainting.

Hypertrophic cardiomyopathy also can affect the heart's mitral valve, causing blood to leak backward through the valve. Sometimes, the thickened heart muscle doesn't block blood flow out of the left ventricle. This is referred to as non-obstructive hypertrophic cardiomyopathy. The entire ventricle may thicken, or the thickening may happen only at the bottom of the heart. The right ventricle also may be affected.

In both obstructive and non-obstructive HCM, the thickened muscle makes the inside of the left ventricle smaller, so it holds less blood. The walls of the ventricle may stiffen, and as a result, the ventricle is less able to relax and fill with blood.

This can raise blood pressure in the ventricles and the blood vessels of the lungs. Changes also occur to the cells in the damaged heart muscle, which may disrupt the heart's electrical signals and lead to arrhythmias.

Some people who have HCM have no signs or symptoms, and the disease doesn't affect their lives. Others have severe symptoms and complications. They may have shortness of breath, serious arrhythmias or an inability to exercise.

It is rare, but some people with hypertrophic cardiomyopathy can have sudden cardiac arrest during very vigorous physical activity. The physical activity can trigger dangerous arrhythmias. Ask your doctor what types and amounts of physical activity are safe for you.

Other Names for Hypertrophic Cardiomyopathy

  • Asymmetric septal hypertrophy
  • Familial hypertrophic cardiomyopathy
  • Hypertrophic nonobstructive cardiomyopathy
  • Hypertrophic obstructive cardiomyopathy
  • Idiopathic hypertrophic subaortic stenosis (IHSS)

What causes hypertrophic cardiomyopathy?
Hypertrophic cardiomyopathy usually is inherited. It's caused by a change in some of the genes in heart muscle proteins. HCM also can develop over time because of high blood pressure or aging. Diseases such as diabetes or thyroid disease can cause hypertrophic cardiomyopathy. However, the cause of the disease isn't known.

This content was last reviewed March 2016.

Other Type of Cardiomyopathy:

Also in this section:

Source: National Heart, Lung, and Blood Institute, National Institutes of Health, U.S. Department of Health and Human Services 

Cardiomyopathy in Adults

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