Hypertrophic Cardiomyopathy

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Overview, Causes, & Risk Factors

In this condition, heart muscle becomes too thick to function properly. The thickening is often not symetrical, affecting one part of the heart more than others. It may interfere with the functioning of the heart by reducing the size of the ventricular chamber. It may also reduce the ability of the valves to work properly. The enlargement may, in some circumstances, obstruct the flow of blood out of the heart.

In addition, heart cells become tangled and jumbled up instead of maintaining their normal pattern. One consequence of the disarray of these cells is that the electrical impulses that normally run though the heart muscle cannot proceed normally, which can lead to abnormal heart rhythms (arrhythmias).

HCM is usually an inherited disorder, the consequence of several defects in the genes controlling heart muscle growth. The abnormal muscle growth usually occurs during periods of a person's rapid general growth, typically during adolescence.

Younger people are likely to have a more severe form of the disease, but HCM may be diagnosed in people of all ages. HCM among people over 60 years of age is often associated with mild hypertension (high blood pressure).

The prevalence of HCM in the general population is 0.2% - 0.5%, or 2 - 5 out of 1000 people.