Hypertrophic cardiomyopathy (HCM) is a form of cardiomyopathy, a condition in which the heart muscle to become thick. The thickening makes it harder for the heart to work.

Hypertrophic cardiomyopathy is often asymmetrical, meaning one part of the heart is thicker than the other parts. The condition is usually passed down through families (inherited). It is believed to be a result of several problems (defects) with the genes that control heart muscle growth.

Because hypertrophic cardiomyopathy causes the size of one of the heart chambers (ventricular chamber) to shrink, the heart must work harder to pump blood. The thickening of the heart muscle may complete block the normal flow of blood out of the heart. It may also make it harder for the heart valves to work. Heart valves help control the direction of blood flow.

Younger people are likely to have a more severe form of hypertrophic cardiomyopathy. However, the condition is seen in people of all ages. In people over age 60, hypertrophic cardiomyopathy is often associated with mild hypertension (high blood pressure).

• 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 have no symptoms, and may not even realize they have the condition until it is found during a routine medical exam.

Unfortunately, the first symptom of hypertrophic cardiomyopathy among many young patients is sudden death, caused by severely abnormal heart rhythms (arrhythmias). Hypertrophic cardiomyopathy is a major cause of death in young athletes who seem completely healthy but die during heavy exercise.

The health care provider will perform a physical exam and listen to the heart and lungs with a stethoscope. Listening with a stethoscope may reveal abnormal heart sounds or a murmur, which may change intensity with different body positions. The pulse in your arms and neck will be checked. The doctor may feel an abnormal heart beat in the chest.

Most frequently, however, nothing is found during a physical exam, and the exam is considered normal.

Tests used to diagnose heart muscle thickness, problems with blood flow, or leaky heart valves ( mitral valve regurgitation ) may include:

• Echocardiography (the most common test) with Doppler ultrasound
• Transesophageal echocardiogram (TEE)
• Chest x-ray
• ECG
• 24-hour Holter monitor (heart monitor)
• Cardiac catheterization

Blood tests may be done to rule out other possible diseases.

If you are diagnosed with hypertrophic cardiomyopathy, your health care provider may recommend that your close blood relatives (family members) be screened for the condition.