PurposeWe compared hemodynamic parameters between subjects with marked, intermediate and minimal cardioinhibition during vasovagal syncope.MethodsThe study included subjects with a decrease in... Show morePurposeWe compared hemodynamic parameters between subjects with marked, intermediate and minimal cardioinhibition during vasovagal syncope.MethodsThe study included subjects with a decrease in heart rate while experiencing a complete vasovagal syncope during tilt-table testing. The subjects were classified as having marked, intermediate or minimal cardioinhibition, based on tertile values of the decrease in heart rate. Hemodynamic parameters between these groups were compared before tilt in the supine position, shortly after tilt and during cardioinhibition.ResultsA total of 149 subjects with a median age of 43 (interquartile range 24–60) years were included in the study. Among the three groups with different levels of cardioinhibition, the highest heart rate was observed in subjects with marked cardioinhibition both before and shortly after tilt and at the start of cardioinhibition. The heart rate decrease in these subjects was both larger and faster compared to subjects with minimal and intermediate cardioinhibition.ConclusionSubjects with marked cardioinhibition have both a larger and faster decrease in heart rate compared to subjects with intermediate and minimal cardioinhibition, as early as from the start of cardioinhibition. Marked cardioinhibition is related to differences in hemodynamic profiles already present well before the start of cardioinhibition. Show less
BACKGROUND: Cardioinhibition may diminish with age, but the changing balance of cardioinhibition and vasodepression with age has not been quantified, leaving the mechanism of vasovagal syncope (VVS... Show moreBACKGROUND: Cardioinhibition may diminish with age, but the changing balance of cardioinhibition and vasodepression with age has not been quantified, leaving the mechanism of vasovagal syncope (VVS) in old age unclear .OBJECTIVES: This study sought to quantify age-related changes of vasodepression and cardioinhibition in tilt-induced VVS. METHODS: We studied 163 cases of tilt-induced WS, evoked using the Italian protocol with blood pressure, heart rate, and video-etectroencephalographic monitoring. Presyncope was excluded. Cardioinhibition was defined as the heart rate decrease before syncope; asystotic pauses (>= 3 seconds) were divided into early and late asystole, ie, beginning early enough to or too late to be the major cause of toss of consciousness. The log-ratio method was used to quantify contributions of cardioinhibition and vasodepression, assessed in 2 10-second periods before the onset of cardioinhibition and before syncope. RESULTS: With increasing age, cardioinhibition decreased, ie, heart rate decreased less and more slowly near syncope (P < 0.0001), white vasodepression increased. Asystotic pauses were less frequent in the older one-half of the group than the younger one-half (26% vs 57%; P < 0.00001), but when it did, late asystole occurred more often (58% vs 15%; P < 0.001). CONCLUSIONS: The shift toward less cardioinhibition and more vasodepression with increased age probably reflects a physiological shift in circulatory control. The weakening of cardioinhibition with age may detract from the efficacy of pacing in older patients with VVS. Cardioinhibition-vasodepression balance should be considered in pacing decisions in older subjects with VVS. (C) 2022 by the American College of Cardiology Foundation. Show less
