EXERCISE-INDUCED NEURALLY-MEDIATED SYNCOPE

We describe a 16-year-old female referred for evaluation of syncope as sociated with competitive long distance running. She had experienced 4 episodes of syncope during competitive long distance racing. The sync ope associated with marked bradycardia and asystole was demonstrated b y head-up tilt testing without isoproterenol infusion. Oral propranolo l therapy failed to prevent the syncope. Oral disopyramide therapy, ho wever, prevented the syncope induced by both head-up tilt testing and competitive long distance racing. Caution should be urged in evaluatin g athletes with syncope, especially in the pediatric age group, becaus e the cause of the syncope may result from life-threatening disorders such as cardiomyopathy, long QT syndrome, or exercise-induced arrhythm ias. The head-up tilt test is an important diagnostic tool for the eva luation of exercise-associated syncope.