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.