Cardiomyopathy is any disease of the heart muscle in which the heart loses its ability to pump blood effectively. In some instances, heart rhythm is disturbed and leads to arrhythmias (irregular heartbeats). There may be multiple causes of cardiomyopathy, including viral infections. Often, the exact cause of the muscle disease is never found.
Cardiomyopathy differs from many of the other disorders of the heart in several ways, including the following:
- Cardiomyopathy can, and often does, occur in the young.
- The condition affects about 50,000 Americans (adults and children).
- The condition tends to be progressive and sometimes worsens fairly quickly.
- It may be associated with diseases involving other organs, as well as the heart.
- Dilated cardiomyopathy is a leading cause for heart transplantation.
Viral infections that infect the heart are a major cause of cardiomyopathy. In some instances, cardiomyopathy is a result of another disease or its treatment, such as complex congenital (present at birth) heart disease, nutritional deficiencies, uncontrollable, fast heart rhythms, or certain types of chemotherapy for cancer. Sometimes, cardiomyopathy can be linked to a genetic abnormality. Other times, the cause is unknown. Three types of cardiomyopathy affect adults.
Hypertrophic cardiomyopathy occurs when the muscle mass of the left ventricle of the heart is thicker than normal, or the wall between the two ventricles (septum) becomes enlarged and obstructs the blood flow from the left ventricle. Because it prevents the heart from properly relaxing between beats, it fills with less blood, which limits the amount of blood pumped by the heart with each beat. A heart murmur may be heard, which is related to the obstruction below the aortic valve (valve between the left ventricle and the aorta).
- This is a rare disease and in most cases it is inherited.
- It can affect men and women of all ages, and symptoms can appear in childhood or adulthood
- Symptoms include shortness of breath on exertion, dizziness, fainting, and angina pectoris.
- Some patients experience cardiac arrhythmias, which may lead to sudden death.
Dilated cardiomyopathy is the most frequent form of non-ischemic cardiomyopathy. The cavity of the heart is enlarged and stretched (cardiac dilation) causing the heart to become weak and not pump normally.
- This occurs most often in middle-aged people and more often in men than women, but has been diagnosed in people of all ages, including children.
- Most patients develop congestive heart failure.
- Dilated cardiomyopathy can be caused by chronic, excessive consumption of alcohol along with dietary deficiencies.
- It occasionally occurs as a complication of pregnancy and childbirth.
- Other suggested causes are: various infections (mostly viral, which lead to an inflammation of the heart muscle, called myocarditis), toxins, and (rarely) heredity. Sometimes drugs used to treat a different medical condition can damage the heart and produce dilated cardiomyopathy. However, in most cases, a specific cause for the damage is never identified.
Restrictive cardiomyopathy, the least common type of cardiomyopathy in the US, occurs when the myocardium of the ventricles becomes excessively rigid, and the filling of the ventricles with blood between heart beats is impaired.
- It usually results from another disease, which occurs elsewhere in the body.
- Restrictive cardiomyopathy does not appear to be inherited, but some of the diseases that lead to the condition are genetically transmitted.
- Symptoms may include fatigue, swelling of the extremities, and difficulty breathing on exertion.