Head-up tilt test for recurrent syncope in pilots

Syncope is defined as a sudden temporary loss of consciousness and postural tone that is associated with spontaneous recovery. Vasovagal or neurocardiogenic syncope is a common and usually benign cause of syncope. The mechanism may be cardioinhibitory, vasodepressor, or both. Diagnosis is usually made by a typical patient history with a definite trigger. Although vasovagal syncope is considered a benign condition, its occurrence in an aviator is worrisome, especially if recurrent and without a definite trigger. The head-up tilt test (HUTT) is used as a vasovagal syncope challenge test. A drop in BP and asystole during HUTT suggest a tendency to recurrent vasovagal syncope. We describe two military aviators with recurrent episodes of vasovagal syncope, one with definite triggers and one without. Both had positive HUTTs. The aviator with trigger-defined vasovagal syncope was disqualified from high-performance platforms due to his positive HUTT. The second case was disqualified from all platforms, irrespective of his HUTT result, because a definite trigger was not definable for all his syncopal episodes.