ARVD/ARVC WEB PAGE

ARVD/ARVC Arrhythmogenic Right Ventricular Cardiomyopathy

Research at St.Georges Hospital Medical School, London United Kingdom.

e-mail to mnorman@sghms.ac.uk

DEFINITION

ARVD Arrhythmogenic Right Ventricular Dysplasia

ARVC Arrhythmogenic Right Ventricular Cardiomyopathy

The two terms are interchangeable when doctors talk about the disease.

Arrhythmogenic means generating an abnormal heart rhythm. It can lead to palpitations, dizziness, light headedness or blackouts. (For examples of rhythm disturbances see below).

Right .The disorder is characterised by fibrofatty replacement of the right side of the heart, in a particular part the ventricular myocardium (heart muscle). Distinctive yellow areas of fat are seen replacing the heart muscle (click here for link to ARVC pathology page) . It can occur on either side of the heart, but has a predilection for the right side, and for the larger chamber of the heart the right ventricle. Hence the term right ventricular.

Ventricular. There are two chambers to the heart. The ventricle is the larger chamber and receives blood from the smaller chamber the atrium. The atrium is the chamber collecting blood coming to the heart and the ventricle pumps blood away from the heart. On the right side of the heart blood comes back from the body to the heart. Blood is then pumped from the right ventricle to the lungs. From the lungs the blood returns after having become oxygenated to the left atrium and then ventricle and then pumped around the body. (For a diagrammatic explanation of the right versus left sides of the heart click here)

Dysplasia means a developmental problem

Cardiomyopathy means a heart muscle disease (with a genetically inherited basis) see link to family screening page for genetics.

In ARVD/ARVC doctors refer to the same condition. Essentially fat replaces the heart muscle. The reason the term Cardiomyopathy is being used is that there is a genetic basis to the disease. Families are seen with ARVC with an autosomal dominant inheritance pattern. This means there can be a 1 in 2 chance of inheriting the gene that causes ARVC. It does not mean however, that 1 in 2 people within a family will have ARVC. The reason is that although people may have the gene they do not have the disease. WHY?

 

We know from another heart muscle disease Hypertrophic Cardiomyopathy the genes responsible. When we test family members for the gene almost 1 in 2 can carry the gene, yet only 1 in 3 or 1 in 4 may have features of the disease. This reflects problems with an interplay of genetics and the environment. Some environmental factors and other genes can interact to amplify the charactereistics of the disease. It also reflects problems with current sensitivity for detecting the conditions with echocardiography and electrocardiography. It is likely there are silent gene carriers who do not have ARVC. Until the genes are known it may perhaps be sensible to repeat the screening tests on first and second degree relatives on a one or two yearly basis. One patient we have seen when initially screened had a normal ECG. Over a two-year follow up period the ECG progressively changed with features suggestive of ARVC in that the T wave in lead 2 became firstly fat and then inverted. The peak age for developing ARVC seems to be about 30, although cases have been described as young as 6 and as old as 70. Several chromosomes are linked with the disorder, chr14, chr1, chr2 and chr 17. It is hoped that over the next few years the genetic basis of the disease will be determined. At St.Georges Hospital Medical School ongoing work is trying to identify families with the condition so that correct treatment can be given and that the gene may be found. If you are someone with ARVC or are within a family with a relative with ARVC we would like to hear from you. An ongoing screening programme of families with ARVC is sponsored by the British Heart Foundation.

More details on ARVC family screening :

CLINICAL SCREENING

In terms of screening for the disease several tests are done, and it is importnat that all are done to add up a diagnostic score. They including an electrocardiogram, an echocardiogram, signal averaged ECG, exercise testing, Holter monitoring and cardiac MRI scans or biopsy.

Please see below for examples of these:

 

ARVC ECHOCARDIOGRAM enlarged right ventricle is seen in the top of the picture. The picture shows an echocardiogram,which is a form of ultrasound of the heart. The right ventricle is enlarged to 7cm (normal size 3cm). The left ventricle is of normal size.

 

 

The ECG in ARVC can show a characteristic feature, T wave inversion in the precordial leads, or incomplete right bundle branch block.

A cardiac MRI scan can show areas of fatty infiltration. In an MRI scan normal muscle appears grey and fatty tissue white. Below a scan of the heart using MRI has a similar orientation to the echo shown above. The right ventricle is at the top of the picture, the left ventricle at the bottom. As can be seen half of the wall of the right ventricle is replaced by fat in a young patient with ARVC.

 

 

ARVC can present with serious heart rhythm disturbance or even collapse. Patients may describe light-headedness, blackouts, especially on exercise. Below a 24hr tape recording of a patient with ARVC shows an abrupt change from the regular heart rhythm to a very fast heart rhythm called Ventricular Tachycardia. Although potentially a serious rhythm disorder it is usually controlled by beta-blockers in the majority of ARVC cases. Rarely people with ARVC have implantable defibrillators, a type of pacemaker, which senses the abnormal heart rhythm and delivers an internal electric current to correct the heart rhythm.