Determine the efficacy of midodrine, a selective alpha 1 adrenergic agonist, in preventing
neurally mediated syncope.
PROTOCOL OUTLINE: This is a randomized, double-blind, crossover, placebo-controlled study.
On day one, patients receive either midodrine or placebo. On day three, patients receive
the opposite drug.
PROTOCOL ENTRY CRITERIA:
--Disease Characteristics-- Diagnosis of neurally mediated syncope (vasovagal fainting)
Sudden fall in blood pressure AND Slowing of the heart AND Temporary loss of consciousness
AND Hemodynamic response to head up tilt --Prior/Concurrent Therapy-- No other concurrent
adrenergic agonist or antiagonist --Patient Characteristics-- Fertile patients must use
effective birth control