Physicians at Johns Hopkins, with colleagues around the globe, are seeking families to help them learn more about a rare heart condition that kills athletes and seems to run in families.

ARVD, or arrhythmogenic right ventricular dysplasia, occurs when the healthy heart muscle tissue of the right ventricle is replaced by fat and scar tissue. In a healthy person, electrical activation of the right ventricle proceeds in a rapid and organized fashion. But in the ARVD patient, the presence of abnormal tissue makes it possible for a potentially life-threatening "short-circuit" arrhythmia to occur.

The disorder, which affects one in 5,000 people, accounts for up to one-fifth of all cases of sudden cardiac death in people younger than 35. It is usually associated with vigorous exercise.

"The heart rapidly speeds up and patients die, a significant portion of them before they've ever been diagnosed," says Hugh Calkins, Hopkins' director of electrophysiology and a professor of medicine and pediatrics in the School of Medicine. "Getting the right diagnosis, through cardiac tests such as cardiac MRI, echocardiogram and a biopsy of heart tissue, is key."

Researchers throughout the world are collaborating with Johns Hopkins to determine the best approach to diagnose this potentially deadly condition and also to determine the genetic abnormalities that are responsible for it. At Hopkins and the University of Arizona, researchers are actively recruiting patients with possible ARVD for entry into the United States Multicenter ARVD Trial.

The cause of ARVD is not yet known, though increasing evidence points to a genetic cause, Calkins says. There is no cure, but many patients are treated with an implantable defibrillator, a pacemakerlike device that monitors the heart beat and automatically delivers a shock to the heart if a dangerous arrhythmia occurs. Others are managed with medications. Patients are generally advised to avoid strenuous competitive athletics.

For more information or to schedule an appointment for testing at Hopkins, contact Crystal Tichnell, genetic counselor for the program, at 410-502-7161 or ctichnell@jhmi.edu.