Neurally mediated syncope with an update on indications and usefulness of head-upright tilt table testing and pharmacologic therapy.

Neurally mediated episodes of hypotension and bradycardia (neurocardiogenic syncope) are a common cause of recurrent syncope. Clinically, these episodes may present as an isolated event with an identifiable stimulus, or manifest as a syndrome of recurrent idiopathic syncopal events. The technique of head-upright tilt table testing has emerged as a safe and effective modality to identify individuals with this disorder. The use of isoproterenol as an adjunct to tilt table testing is widely employed although controversial. Whereas the mechanism of neurally mediated syncope is incompletely understood, effective therapies are available. Multiple pharmacologic agents, either alone or in combination, have proven effective in preventing recurrent episodes. The role of cardiac pacing as therapy for a subgroup of patients who manifest severe bradycardia or asystole remains controversial as well. Additional study is necessary to further define the mechanism of neurally mediated syncope, provide new therapeutic strategies, and perhaps provide alternative diagnostic techniques.