| Hypertrophic cardiomyopathy occurs when the heart muscle thickens abnormally. The thickening generally happens in the left ventricle, the heart's main pumping chamber. This type of cardiomyopathy can affect people of any age.
Hypertrophic cardiomyopathy can be obstructive or nonobstructive. In the obstructive type, the septum (the wall that divides the left and right sides of the heart) thickens and bulges into the left ventricle. This bulge blocks the flow of blood out of the ventricle. The ventricle must work much harder to pump blood past the blockage and out to the body. Symptoms can include chest pain, dizziness, shortness of breath, or fainting.
Obstructive hypertrophic cardiomyopathy also can affect the heart's mitral (MI-trul) valve, causing blood to leak backward through the valve.
In nonobstructive hypertrophic cardiomyopathy, the thickened heart muscle does not block the flow of blood out of the ventricle. The entire ventricle may become thicker (symmetric ventricular hypotrophy) or it may happen only at the bottom of the heart (apical hypertrophy). The right ventricle also may be affected.
In both kinds of hypertrophic cardiomyopathy, the thickened muscle makes the inside of the left ventricle smaller so that it holds less blood. The walls of the ventricles also may become stiff. As a result, they are less able to relax and fill with blood. This causes increased pressure in the ventricles and the blood vessels of the lungs. Changes also occur to the cells in the damaged heart muscle. This may interfere with the heart's electrical signals, leading to arrhythmias.
Some people with hypertrophic cardiomyopathy have no symptoms, and the condition does not affect their lives. Others have severe symptoms or develop complications such as serious arrhythmias. A few people with the condition have sudden cardiac arrest because of dangerous arrhythmias.
Hypertrophic cardiomyopathy can be inherited because of a gene mutation or develop over time because of high blood pressure or aging. Often, the cause is unknown.
Restrictive Cardiomyopathy | 
