Hypertrophic cardiomyopathy
Key points
- Cardiomyopathy - hypertrophic (HCM); IHSS; Idiopathic hypertrophic subaortic stenosis; Asymmetric septal hypertrophy (ASH).
- Hypertrophic cardiomyopathy (HCM) is a form of cardiomyopathy (disease of the heart muscle) involving thickening of the heart muscle.
- In this condition, heart muscle becomes too thick to function properly.
- Some patients with HCM have no symptoms, and may be unaware of their condition until it is detected during routine medical screening.
Alternative names
Cardiomyopathy - hypertrophic (HCM); IHSS; Idiopathic hypertrophic subaortic stenosis; Asymmetric septal hypertrophy (ASH).
Definition
Hypertrophic cardiomyopathy (HCM) is a form of cardiomyopathy (disease of the heart muscle) involving thickening of the heart muscle. This interferes with the function of the heart.
Causes, incidence, and 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 thickening of the heart muscle 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).
Symptoms
- chest pain
- fainting, especially during exercise
- light-headedness, especially after activity or exercise
- dizziness
- sensation of feeling heart beat (palpitations)
- shortness of breath
Additional symptoms that may occur are:
- fatigue, reduced activity tolerance
- shortness of breath when lying down
Some patients with HCM have no symptoms, and may be unaware of their condition until it is detected during routine medical screening.
Unfortunately, the first symptom of HCM among many young patients is sudden death, caused by severe arrhythmias. HCM is a major cause of death in young athletes who seem completely healthy but die during heavy exercise.
Written and revised by
David Cohen, M.D.
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