ABNORMALITIES OF THE CORRECTED QT INTERVAL IN FAMILIAL DYSAUTONOMIA -AN INDICATOR OF AUTONOMIC DYSFUNCTION

We report abnormalities in corrected QT intervals with changes in posi tion and after exercise in patients with familial dysautonomia and con firm the previously reported finding of abnormal heart rate and blood pressure responses. Prolonged corrected QT intervals (>440 msec) with lack of appropriate shortening with exercise is a noninvasive means of demonstrating an aberration in autonomic regulation of cardiac conduc tion.