Arrhythmogenic Right Ventricular Cardiomyopathy
The article by Gemayel and colleagues provides an excellent summary of the clinical features of right ventricular cardiomyopathy (right ventricular dysplasia), a condition that occurs in about 1 in 5000 individuals. It is crucial to recognize this disease because it is one of the causes of sudden death.

The disease is caused by the replacement of myocytes, especially in the right ventricle, with fibrofatty tissue. Although the genes responsible for the disease have not been identified, the condition is inherited as an autosomal dominant trait, and 7 loci have been found on chromosome 14. The lethal ventricular arrhythmia is often precipitated by exercise-induced release of catecholamines.

Whereas early reports claimed the condition was a right ventricular disease, Gemayel points out that it may also involve the left ventricle. Because of that, the disease may cause biventricular heart failure. This may be diagnosed as idiopathic dilated cardiomyopathy.

The electrocardiogram may reveal epsilon waves in 30% of the patients and/or repolarization abnormality due to a posteriorly directed mean T wave vector in 54% of patients. The latter abnormality may not be a useful sign in young people because the normal child may exhibit a posteriorly directed T wave vector. The QRS duration may be longer in leads V₁ - V₃ than in lead V₆.

Computerized tomography and magnetic resonance imaging are thought to be superior procedures for identification of the condition.

Endocardial biopsy may identify the disease, but there is a danger of a negative result because the fatty tissue may occur in patches. Accordingly, a negative biopsy does not exclude the disease.

Although treatment includes the use of antiarrhythmic drugs, automatic implantable cardiac defibrillators appear to be superior to pharmacologic therapy.