Differences in autonomic balance in patients with cardioinhibitory and vasodepressor type of reflex syncope during head-up tilt test and active standing

Abstract

Objective. To improve the pathophysiological understanding of cardioinhibitory and vasodepressor reflex syncope, by evaluating orthostatic effects on electrical and hemodynamic variables. To unravel the pathogeneses further, we studied these effects during both the passive head-up tilt test and the active standing test. Background. The current knowledge of the compromised autonomic balance in patients with reflex syncope is limited. The orthostatic responses to head-up tilt test in cardioinhibitory and vasodepressor patients differ, suggesting different pathogeneses; however, the more physiological active standing test represents daily life situations better. Methods. We included 74 patients; 36 cardioinhibitory and 38 vasodepressor. Patients were compared with respect to vascular hemodynamics and heart rate variability during the change from supine to upright position. Resting electrolytes, brain natriuretic peptide (BNP), pro-atrial natriuretic peptide (pro-ANP), and the C-terminal of pro-vasopressin, c...