Vasovagal syncope: current concepts in diagnosis and treatment.

Vasovagally mediated episodes of hypotension and bradycardia are thought to be common causes of recurrent unexplained syncope. Head-up tilt table testing, either alone or with a graded-dose infusion of isoproterenol, is a useful diagnostic test for identifying persons who are susceptible to vasovagal syncope. In addition to its diagnostic ability, tilt table testing may provide a means to assess the efficacy of preventive pharmacotherapy for syncope. Further study of tilt table testing is needed to increase understanding of vasovagal syncope and to better define the test's role in the diagnosis and management of this condition.