WEDNESDAY, May 22, 2002 (HealthDayNews) -- A simple test can detect a genetic condition that causes sudden death in seemingly healthy people while they're exercising.
Mayo Clinic researchers say the hearts of people with the condition -- called long QT syndrome -- show a specific response when given epinephrine while being monitored with an electrocardiogram (ECG). Epinephrine, also known as adrenaline, quickens the heart rate after a person experiences a rapid empotional change like fear or anger.
In each beat, the heart has to electrically fire to tell the muscle to squeeze and then it has to reset itself. In people with long QT syndrome, the heart's electrical recharging process is longer than normal. That can be measured by what's called the QT interval on the ECG.
This test takes about an hour. The epinephrine is given intravenously, and the patient is fitted with defibrillator pads in case they have a heart emergency. More than 100 of these tests have been done so far without any problems.
The study looked at 37 patients genotyped with long QT syndrome in Mayo's Sudden Death Genomics Laboratory. The results were published in the May issue of the journal Mayo Clinic Proceedings.
The condition affects about 1-in-5,000 people.
Usually, people with long QT syndrome experience no heart problems. But swimming, intense exertion, or being startled or frightened can set it off, causing fainting spells, seizures or even death from a fatal irregular heart rhythm called ventricular fibrillation.
Those at risk for long QT syndrome include people who have fainting spells because of emotion, exercise or exertion; relatives of people with long QT syndrome; people who experience an unexplained near-drowning incident; and people with a family history of seizures or Sudden Infant Death Syndrome (SIDs).
These people should get an ECG, which can often detect the condition. People with long QT syndrome can lead normal lives, with some restrictions: They can't play competitive sports, they require daily medication and they should never swim alone.
More information
Here is an entire Internet site devoted to long QT syndrome.
