Arrhythmogenic Right Ventricular Dysplasia

Hugh Calkins M.D., F.A.C.C.
Assoc. Professor of Medicine and Pediatrics
Director of Electrophysiology
Division of Cardiology
Johns Hopkins Hospital

Arrhythmogenic right ventricular dysplasia (ARVD) is a familial cardiomyopathy of unknown cause which is characterized by ventricular arrhythmias and replacement of right ventricular myocardium with fatty and fibrous tissue. It is estimated that ARVD occurs in 1 out of every 5000 persons.

ARVD most commonly comes to clinical attention in young men, with at least 80% of cases being diagnosed before the age of 40. The most common presenting symptoms are palpitations, syncope (transient loss of consciousness) and less commonly sudden cardiac death. These symptoms are caused by ventricular arrhythmias which result from the presence of the scarred myocardium. Although ARVD is a relatively uncommon cause of sudden cardiac death, it accounts for up to one fifth of all episodes of sudden cardiac death which occur in patients below the age of 35. Exercise has been identified as a common precipitant of the arrhythmias which occur in patients with ARVD.

Diagnosis of ARVD is often a very difficult task as there is no single test which can be used either to establish or exclude this diagnosis. However, the results of a careful history, physical examination, and a number of specific cardiac tests can be used to establish the diagnosis of ARVD. The present diagnostic criteria for ARVD are based on the presence of certain major and minor diagnostic criteria. The diagnosis of ARVD is established by the presence of 2 major criteria or 1 major criteria plus 2 minor criteria or 0 major criteria and 4 minor criteria.

The major criteria include: 1) the presence of structural abnormalities in the right ventricle, 2) abnormal myocardial tissue in the right ventricle with fatty infiltration, 3) repolarization abnormalities on the electrocardiogram with T wave inversion in leads V1 to V3 or beyond, 4) conduction abnormalities on the electrocardiogram such as a QRS duration >= 100 msec in V1, V2, or V3 or an epsilon wave, and 5) a family history of ARVD confirmed by autopsy results.

The minor criteria for ARVD include: 1) mild to moderate structural abnormalities of the right ventricle, 2) ECG abnormalities such as T wave inversion in V2 and V3 or late potentials on a signal averaged ECG, 3) ventricular arrhythmias such as sustained or nonsustained ventricular tachycardia with a left bundle morphology or more than 1000 PVCs per 24 hour, and 4) a family history or premature sudden cardiac death or ARVD.

Specific cardiac tests which are usually recommended in all patients with suspected ARVD include an electrocardiogram, a signal averaged electrocardiogram, an exercise stress test , an echocardiogram, a Holter monitor and a chest x-ray. In addition to these standard tests, many centers perform additional testing including cardiac Magnetic Resonance Imaging (M.R.I), a MUGA scan, cardiac catheterization with ventriculography, an endomyocardial biopsy, and/or an electrophysiology study.

The specific cause of ARVD remains poorly defined, however increasing evidence points towards a genetic cause. To date, abnormalities have been found among families with ARVD in five different locations of the genome (DNA map). The specific genes responsible for ARVD have not yet been identified. It is hoped that some day genetic testing can be used to establish the diagnosis of ARVD and also to guide treatment of this condition. Although there has been a great deal of progress made over the past 2 - 5 years, much work remains to be done.

There is not known curative treatment for ARVD. At the present time, treatment is normally directed at the patients ventricular arrhythmias with the primary goal of treatment being prevention of sudden cardiac death and other types of sustained arrhythmias which can cause lightheadedness or loss of consciousness. Many patients with ARVD are treated with an implantable defibrillator, which is a pacemaker like device which monitors the heart beat and automatically delivers a shock to the patient if a dangerous arrhythmia occurs. Other patients are treated with antiarrhythmic medications. In addition to these treatments for arrhythmias, it is generally advised that patients with ARVD avoid vigorous competitive athletics.

A large number of questions remain unanswered when it comes to ARVD. For example, it is unclear how rapidly the cardiomyopathy that affects the right ventricle progresses and whether medications and/or changes in activity level can alter the rate of progression. In is also unclear what specific genetic abnormalities cause ARVD and how a specific genetic abnormality can alter the rate of progression of the disease as well as the clinical course of the disease. For example, it is likely that some genetic forms of ARVD are highly lethal while others have a much more favorable course. There are also a large number of questions concerning what tests, short of genetic testing which is currently not available, are best at either diagnosing or excluding ARVD. Hopefully, over the next five years the answers to many of these questions will be determined.