POST-MICTURITION SYNCOPE

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Abstract
Syncope immediately following micturition was noted in 3 healthy adult males. In one case, in the midst of a syncopal episode, atrial fibrillation with ventricular premature beats at a heart rate of 50/min was noted. These abnormalities spontaneously reverted to normal. Sinus arrest, nodal rhythm and T wave changes were observed in phase IV of Valsalva''s maneuver in the 3 patients but did not occur in a series of control subjects. These changes could be abolished by atropine. Evidence is offered that syncope following micturition and other clinical situations associated with straining is the result of excessive acetylcholine secretion in phase IV of the Valsalva maneuver. This causes cardiac arrest and subsequent arrhythmia in a heart sensitized by the diminished coronary flow of phase II.