Arrhythmogenic right ventricular dysplasia (ARVD) is a genetic disease in which the muscle tissue in the lower-right chamber of the heart (right ventricle) degenerates and is replaced by fat. As a result, patients can develop dangerous abnormal heart rhythms (arrhythmias) or even go into cardiac arrest, particularly when under physical or emotional stress. Studies have shown that ARVD is a significant cause of sudden cardiac death among young athletes.

In some cases, symptoms appear in childhood and can quickly worsen. In most cases, however, symptoms do not appear until patients are in their 30s or 40s. By that time, ARVD may have progressed to heart failure.

There is no known cause or cure of ARVD, although there is a clear genetic link. Patients with ARVD have a 50 percent chance of passing the condition along to their children. Researchers are currently working to develop gene therapy to treat ARVD. In the meantime, treatment for ARVD is aimed at controlling the arrhythmias that could lead to a life-threatening cardiac event.

Support is available for ARVD patients and their families. Patients are encouraged to contact the ARVD Registry of North America for further information about the disease and about contacting others with the same condition. By registering as someone with ARVD, patients can also help researchers develop better treatments and diagnostic tools. The registry can be reached by calling 800-483-2662.

ARVD (arrhythmogenic right ventricular dysplasia) is a rare condition in which the muscle tissue in the lower-right chamber of the heart (right ventricle) degenerates and is replaced by fatty tissue. The left ventricle may be involved, but to a lesser extent. There are a number of theories to explain ARVD, including a problem in the body’s natural process of removing damaged cells (apoptosis). Alternative theories to explain ARVD include the conversion of healthy myocardial cells into fatty tissue for unknown reasons, inflammation (such as that caused by viral myocarditis) that destroys the myocardial cells, and the replacement of normal cells with fatty and fibrous cells during healing.

Whatever the cause, gradually the muscle in the right ventricle is replaced with fatty tissue and fibrous tissue. The damaged right ventricle cannot pump the normal amount of blood to the lungs for fresh oxygen. Over time, the disease can progress to heart failure. It can also cause dangerous abnormal heart rhythms (arrhythmias) that could result in sudden cardiac death, particularly when the person is under physical or emotional stress. ARVD is a significant cause of sudden cardiac death in young athletes. People with ARVD are also at increased risk for blood clots, which may form in the right ventricle in the case of more advanced disease.

ARVD is estimated to occur in one out of every 1,000 people and the disease is most likely under-diagnosed in the United States. The diease is most commonly diagnosed between the ages of 10 and 50, with typical diagnosis made around age 30. Patients with ARVD have a 50 percent chance of passing the condition along to their children. Although the exact genes that confer ARVD have not been identified, it is an autosomal dominant condition. The severity of the disease can differ among affected individuals, even in the same family. In other words, the signs, symptoms and age of onset of ARVD may not be the same between an affected parent and an affected child.

Once the genes are identified, it is hoped that a reliable blood test and gene therapy will be developed to help diagnose and treat ARVD as early as possible. It is very important to diagnose ARVD as early as possible to prevent sudden cardiac death.

People with ARVD may not show any signs or produce any symptoms until they go into cardiac arrest. This medical emergency can strike patients at any age, including children, and is more likely to occur when patients are physically active or very upset.

Many people with ARVD are unaware they have the disease until they reach their 30s or 40s and first begin to experience symptoms. About half of ARVD patients experience abnormal ventricular contractions (arrhythmia). The severity and nature of the arrhythmias depends on the extent of the disease. Symptoms might include pounding or galloping heartbeat (palpitations), dizziness, chest pains, fainting (syncope) and symptoms of heart failure, which include:

• Shortness of breath (dyspnea). This is one of the earliest symptoms of heart failure. The patient gets winded and fatigued more quickly than before, just by performing regular daily activities or even lying in bed. There is also decreased tolerance to exercise, and the muscles may feel weaker than before.
  
  
• Swelling (edema). Swelling of the legs is another common symptom of heart failure, though it can also be caused by unrelated conditions.
  
  
• Swollen neck veins.
  
  
• Abdominal discomfort. This includes swelling, pain or nausea.
  
  
• Mental confusion.
  
  
• Kidney malfunction or failure (in the later stages of heart failure).

In addition to these symptoms, the physician may also be able to detect signs of heart failure, which include: 

• An abnormal pulse
  
  
• An abnormal heart murmur
  
  
• A rapid heartbeat (tachycardia) or abnormal heart rhythms (arrhythmias)
  
  
• Swelling and fluid retention in the liver or gastrointestinal tract (in advanced stages of heart failure)
  
  
• Liver malfunction

Although diagnosing ARVD is difficult, it is hoped that a blood test will someday be developed to make diagnosis easier and more reliable. Early detection is vital because ARVD is a significant predictor of death.

Currently, diagnosis will begin with the physician asking questions about the patient’s personal and family medical history. The physician will be particularly interested in whether any family members were diagnosed with ARVD or had similar symptoms. Although not all ARVD patients have a family history, it has been shown that ARVD tends to run in families. A physical examination will also be performed. A number of noninvasive tests may be ordered, which generally include the following:

• Magnetic imaging resonance (MRI). A procedure that uses magnetic fields and a computer to produce high-resolution cross-sectional or three-dimensional images of the target area (e.g., the heart). An MRI can only offer limited information about how much heart muscle tissue is actually fat, and most centers have little experience in visualizing the right ventricle with MRI. A diagnosis of ARVD should not rely solely on MRI, according to the most recent disease protocols.
  
  
• Electrocardiogram (EKG). This painless test measures the electrical activity of the heart. Patients with ARVD often have specific EKG abnormalities that a physician will recognize. A special type of signal-averaged EKG may also be ordered. The signal-averaged EKG uses a computer to filter signals called “late potentials” to allow for a more detailed analysis of the heart’s electrical function. It may be used to assess the potential danger of ventricular arrhythmias (abnormal heart rhythms). If the EKG is normal while the patient happens to be in a medical facility, then the physician may order a Holter monitor to continuously monitor the heart’s electrical activity for 24 hours.

  
  

• Echocardiogram. This painless test uses sound waves to visualize the structures and functions of the heart. A moving image of the patient’s beating heart is played on a video screen, where a physician can study the heart’s thickness, size and function. An echocardiogram must be performed in a very specific way to get a good picture of the right ventricle, which lies under the breastbone.

In most cases, ARVD cannot be diagnosed simply from a noninvasive test. To make a clear diagnosis before beginning treatment, more invasive tests are generally performed, such as:

• Radionuclide angiography (RNA). Researchers have discovered that this test is the most reliable confirmation for ARVD. RNA uses a technique called radionuclide-imaging in which a tracer is introduced into the blood prior to testing. A special gamma camera is then used to view the tracer as it moves through the right ventricle, providing images of the function and blood flow within the heart.
  
  
• Multiple-gated acquisition scan (MUGA scan). This noninvasive test uses a radioactive tracer to measure the function of the ventricles. During a MUGA scan, electrodes are placed on the body to measure the heart’s electrical function at the same time the gamma camera measures the progress of the tracer through the heart and blood vessels.
  
  
• Cardiac catheterization with right ventriculogram. Another test sometimes used to look for any structural damage in the right ventricle. During this test, a long thin catheter is used to inject a special contrast dye into the ventricles. This dye is visible under x-ray, allowing the physician to assess the function of the right ventricle. This test is considered the best invasive diagnostic tool for ARVD. It is often conducted in conjunction with an electrophysiology study.
  
  
• Electrophysiology study (to assess for the presence of arrhythmias). During this test, a catheter is guided into the heart, where it stimulates the heart muscle with an electrical charge in order to identify the origin of the abnormal rhythm.
  
  
• Biopsy of the heart muscle tissue in the right ventricle. This test may be conducted to determine if any fat is present. This test is also performed with a catheter, which is tipped with a special instrument used to collect a small sample of heart tissue. Physicians generally prefer to take the tissue sample from the septum rather than puncturing the ventricle itself, but septum tissue is not necessarily a good indicator of the status of the right ventricle.

The goal of these tests is to determine whether the patient has at least two of the following major criteria needed to make a diagnosis of ARVD:

• A family history of ARVD that has been confirmed by autopsy.
  
  
• The presence of fatty tissue where there should be only heart muscle tissue.
  
  
• Severe structural damage to the right ventricle.
  
  
• A specific type of repolarization abnormality on the patient’s electrocardiogram (EKG).
  
  
• A specific type of conduction abnormality on the patient’s EKG.

Alternatively, the patient may be diagnosed with ARVD based on only one of the major criteria listed above and two minor criteria listed below. A diagnosis may also be made if the patient has no major criteria and four minor criteria. The minor criteria include:

• A suspected family history of ARVD or sudden cardiac death that has not been confirmed by autopsy.
  
  
• Mild to moderate structural damage to the right ventricle.
  
  
• Certain types of arrhythmias.
  
  
• Specific types of EKG abnormalities.

Treatment options for ARVD

There is currently no known strategy for treating ARVD itself, but treatments are available to control abnormal heart rhythms (arrhythmias) to help reduce the risk of sudden cardiac death.
The treatment of ARVD generally includes medications called antiarrhythmics and those who have elevated risk for sudden cardiac death frequently have an implantable cardioverter defibrillator (ICD) inserted. ICDs are typically recommended for an patients who have experienced serious ventricular arrhythmias, or those who are considered at high risk of certain arrhythmias (e.g., ventricular tachycardia, ventricular fibrillation). In some cases, radiofrequency ablation may be recommended in conjuction with other therapies. During this procedure, very targeted tissues in the heart are destroyed in an effort to reduce the risk of fatal tachyarrhythmias. Finally, a subset of patients with advanced disease may benefit from anticoagulation therapy to reduce the risk of blood clots.

All ARVD patients are urged to avoid excessive physical and emotional stress, including competitive sports, which could trigger a life-threatening cardiac event. However, some patients may be able to engage in recreational sports under the supervision of a physician. Individuals with ARVD should also use caution before taking prescription or over-the-counter medications. Cold and flu preparations that contain pseudoephedrine, a stimulant, can trigger arrhythmias, as can caffeine.

If the condition worsens and the patient develops heart failure, treatment will focus on the heart failure.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following ARVD-related questions:

1. Is there anything I may have done to cause this condition?
   
   
2. If I don’t meet all the diagnostic criteria, is it possible that I still have ARVD?
   
   
3. Is ARVD progressive? Will it get worse over time?
   
   
4. Is there any way to predict whether my child will get the disease or not? What about genetic screening?
   
   
5. How long will I be on antiarrhythmic therapy? Will I be restricted in exercise for the rest of my life?
   
   
6. Would abnormal EKG results suggest that I may have ARVD?
   
   
7. What over the counter medicines might trigger ARVD?
   
   
8. Should I limit my caffeine intake?
   
   
9. Is the ARVD responsible for my symptoms?
   
   

10. Are there any lifestyle/dietary choices I am making that may be worsening my disease? Is it in any way related to dietary fat?