Cardiomyopathy – heart muscle disease

Cardiomyopathy – heart muscle disease

Cardiomyopathy means heart muscle disease. Three important varieties of heart muscle disease are:

Hypertrophic cardiomyopathy (HCM)

Dilated cardiomyopathy (DCM)

Restrictive cardiomyopathy (RCM)

In addition to this another rare variety may be seen occasionally is called arrhythmogenic right ventricular dysplasia/cardiomyopathy.

Hypertrophic cardiomyopathy (HCM)

HCM is an inherited heart muscle disease. It has an autosomal dominant inheritance. This means that 50% of first degree relatives (father, mother, brother, sister, son, daughter) have a chance of having the disease. Characteristic feature of the disease is gross thickening of the wall of the left ventricle. Usually the thickening is asymmetric and involves the partition between the two ventricles (interventricular septum) more than the rest of the left ventricle. Hence it is also called asymmetric septal hypertrophy. Undue thickening causes a defect in the relaxation of the ventricle. It also predisposes to heart rhythm abnormalities. The disease is an important cause of sudden death in young athletes. There is often associated leakage of the mitral valve and obstruction of blood flow from the left ventricle. Then it is called hypertrophic obstructive cardiomyopathy (HOCM).

Mild cases can be treated with medications. Very severe case may require surgery in which the excess thickening of the interventricular septum is removed by an operation called septal myectomy. Another method is to destroy a small amount of the extra muscle by guided injection of alcohol into the blood vessel supplying it (alcohol septal ablation). Patients who are prone for sudden death due to life threatening heart rhythm disorders can be protected by giving an implantable cardioverter defibrillator.

Dilated cardiomyopathy (DCM)

In DCM, the left ventricle becomes enlarged and muscle becomes flabby, with poor contraction. The heart is unable to pump enough blood to meet the demands of the body. Hence they go into heart failure. They can also have heart rhythm disorders. Sometimes clots can form in the flabby heart and move out to other parts of the body (embolism).

Restrictive cardiomyopathy (RCM)

In RCM, relaxation of the heart becomes restricted and the heart is unable to fill well. Infiltration of the heart with iron in a disease called hemochromatosis can cause restriction. A disease which was common in the developing world known as endomyocardial fibrosis was the most common variety of restrictive cardiomyopathy earlier. But now the disease is found only infrequently. They have swelling of the ankles and tummy due to excessive fluid collection.

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C)

ARVD/C is different from other varieties of cardiomyopathies in that the predominant manifestation is life threatening heart rhythm disorders. They present with palpitation and have a risk of sudden cardiac death. As the name indicates, the involvement is mainly the right ventricle, unlike other three cardiomyopathies which mostly involve the left ventricle (exception being endomyocardial fibrosis which involves mainly the right ventricle).