Syncope induced by tobacco smoking in the head-up position.

A 26-year-old man had a loss consciousness for a few minutes while smoking in the standing position, and was referred to hospital. No abnormalities were found in a computed tomography examination of his head, in a 24-h electrocardiogram or in an exercise tolerance test. The head-up tilt test (HUT) while tobacco smoking elicited a positive response in the tilted position, but the HUT without tobacco smoking was negative. The most noteworthy effect of tobacco smoking during the HUT was the high level of plasma epinephrine compared to the levels seen during supine smoking or the HUT alone. Syncope induced by tobacco smoking in the standing position is rare and the mechanism may be the same as that underlying neurally mediated syncope.