Arrhythmogenic right ventricular dysplasia is a type of arrhythmia (abnormal heart rhythm) caused by a disorder of heart muscle in which portions of the muscle in the right ventricle are replaced by fat and fibrosis (connective tissue). In some cases, this type of arrhythmia can be very dangerous, causing cardiac arrest and even sudden death. Although ARVD is an uncommon cause of sudden cardiac death, it accounts for up to one-fifth of sudden cardiac deaths in people less than 35 years of age and 3-4 percent of sudden cardiac deaths that occur during exercise or playing sports.
ARVD affects 1 in 1000 to 1 in 5,000 people. This incidence is higher in certain regions of the world such as Italy and Greece. ARVD is inherited in 30 to 50 percent of individuals and is usually transmitted from one affected parent to a child as a dominant disorder. This means that affected individuals have a 50 percent chance of passing the disorder on to their children. Many of the genes that cause ARVD affect proteins that bind certain heart muscle (myocardial) cells together called desmosomes. There are many different genes that can cause ARVD and it is likely that not all have been discovered.
Signs and Symptoms
The signs and symptoms of ARVD are caused by the abnormal heart rhythms.
The symptoms of ARVD typically first occur during the late teens or young adulthood. In fact, 80 percent of cases of ARVD are diagnosed in patients younger than 40 years of age. When a patient is diagnosed with ARVD, it is important that the patient's close relatives are informed and evaluated for the condition. Family member screening may detect the disease early and possibly prevent sudden death. There are laboratories that offer testing on a research basis only.
ARVD can be difficult to diagnose because there is no single, simple test that determines whether the condition is present. When ARVD is suspected, a careful evaluation including history and physical examination along with a variety of tests are often needed. These can include:
The treatment of ARVD is focused on controlling abnormal heart rhythms, preventing sudden death, and managing any symptoms of heart failure that may be present.
The first line of medical therapy is usually a beta-blocker, a medication that reduces the effect of adrenalin on the heart. The treatment of arrhythmias may include other medications, called antiarrhythmic drugs, which help to decrease the frequency and severity of abnormal heart rhythms. Potent antiarrhythmic drugs, such as sotalol and amiodarone, may be needed in select cases.
Many patients with ARVD also receive an implantable cardioverter defibrillator (ICD). This device monitors the heart rhythm and delivers an electrical shock or pacing to restore the normal rhythm if an abnormal rapid rhythm called ventricular tachycardia or ventricular fibrillation occurs. Some patients experience frequent arrhythmias despite medication. These patients may be helped by a heart catheterization procedure, called catheter ablation. A long thin wire (catheter) is inserted through the skin into a blood vessel and guided into the heart, where it is used to find the abnormal regions that are causing attacks of fast heart rhythm. These areas are then cauterized with an electrical current applied through the catheter. Ablation is not curative, but can improve symptoms.
Lifestyle modification is important to prevent symptoms. In general, vigorous exercise should be avoided as exercise has been shown to trigger arrhythmias in many patients with ARVD. In addition, stimulants such as nicotine, caffeine, and some cold and flu medications should be avoided or used only in moderation. Patients with heart failure symptoms are generally treated with medications called ACE inhibitors and diuretics. In very rare cases, heart transplantation can be required for uncontrollable arrhythmias and for severe congestive heart failure.