Hypotensive reactions on passive head-up tilt testing of hypertensive patients.

With the aid of a protracted passive postural test, the rate of occurrence and the variants of orthostatic hypotensive reactions in hypertensive patients were studied. Three hundred and eighty-two consecutive tilt tests in 161 hypertensive patients, 89.4% of whom were taking antihypertensive medications, were reviewed. Orthostatic hypotensive reactions were recognized in 33.8% of examinations. Thirty-one hypotensive episodes (8.1%) were associated with symptoms of cerebral ischemia, resulting in termination of the tilt test at a median of 5 min from onset (range 1-30 min). A survey of possible risk markers of symptomatic hypotensive reactions during tilt showed that increasing age was associated with significantly increased risk (P < 0.001), while gender, office blood pressure (BP), diabetes mellitus, ischemic heart disease, anxiety, history of syncope, and treatment with antihypertensive drugs were not. Asymptomatic orthostatic hypotension early in the course of the tilt test was a weak predictor of symptomatic hypotensive reactions later during the test (positive predictive value 17.4-33.3%). Among the 31 symptomatic hypotensive reactions, 10 were typical cases of orthostatic hypotension, four were typical vasovagal reactions, and 17 episodes were difficult to classify. The implications of symptomatic hypotensive reactions triggered by protracted head-up tilt in hypertensive patients are unknown and can only be elucidated in longitudinal studies.