What's being called a "breakthrough" discovery of a genetic mutation may lead to the prevention of a type of sudden death in children.

The sudden death is caused by a rare disease known as catecholaminergic polymorphic ventricular tachycardia, or CPVT. This condition can cause a deadly arrhythmia, which is a change in the heart's normal beating pattern, in seemingly healthy children.

When it strikes, usually during physical exertion or mental or emotional stress, it can cause sudden death. But the good news is that Italian researchers have discovered that a mutation in a gene that controls the levels of calcium in heart cells appears to be responsible for CPVT.

"Catecholaminergic ventricular tachycardia is a life-threatening condition that effects children and adolescents," says Anthony Rossi, MD, "And the authors are to be congratulated on a breakthrough medical discovery that has significant clinical implications and will ultimately save lives.

"Children with this condition ... may present with relatively benign symptoms such as fainting," he tells WebMD. "Unfortunately, an electrocardiogram performed during routine screen will fail to detect this lethal rhythm disturbance." Rossi, who was not involved in the study, is medical director of the Cardiac Intensive Care Unit at Miami Children's Hospital in Florida.

Up until now, it has been difficult to diagnose because patients have normal EKGs and echocardiograms, which is a diagnostic test that uses high-frequency sound waves to create an image of the heart. But CPVT does not change the structure of the heart, so the problem cannot be seen when imaged.

While some children may have symptoms such as fainting, often they appear to be healthy and the first clue that something is wrong may be sudden death. But knowing that there is a genetic cause may now pave the way for screening high risk patients and taking preventive measures such as installing devices such as implantable defibrillators that correct the heartbeat or drugs such as beta-blockers, that can be used to prevent the rapid heartbeat.

The study, which was released before its Jan. 16, 2000 publication in Circulation: Journal of the American Heart Association because of its breakthrough information, was led by Silvia Priori, MD, PhD, who is chairman of the Molecular Cardiology and Electrophysiology Laboratories at the University of Pavia. She and her team looked at 12 patients who had a diagnosis of CPVT.

Five of the patients had family histories of a sibling who had fainting spells or who had died suddenly from cardiac arrest. In one case, a patient was diagnosed at age 30 when she started experiencing palpitations. Two of her sisters had died suddenly when they were 14 and 16 years old. When her family underwent genetic and other diagnostic tests, it was found that both she and four family members carried the mutation: all five of them developed arrhythmias when performing even moderate exercise.

The researchers believe that because of this mutation, people with CPVT are more sensitive to calcium. Emotional stress, physical activity, or anything that causes intense stimulation may lead to an overload of calcium and bring on severe arrhythmias.

"The genetic marker discovered will allow us to accurately define those children at risk for sudden death, institute the appropriate therapy, and save lives," says Rossi.

David Waight, MD, agrees. Once they're identified as having the genetic defect, he says, the patients may be treated prior to having any symptoms, and this is very important as some patients' first symptom will be sudden death.

"This report supports the general impression of many cardiologists that much of the disease seen in pediatric patients has a genetic origin that will be discovered with continued future investigation," he tells WebMD. Waight, who was not involved in the study, is a professor of pediatrics at the University of Chicago.

(From Excite.com)