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Hypertrophic cardiomyopathy    See images

Overview | Symptoms | Treatment | Prevention

Alternative names:

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

Definition:

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.

Causes and Risks

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:

1. 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.
2. An acquired form that occurs in elderly people with a history of high blood pressure (hypertensive hypertrophic cardiomyopathy).

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