Hemodynamic significance of heart rate in neurally mediated syncope

Abstract

SummaryBackground: Vasovagal and vasodepressor syncope are used interchangeably in the literature to describe the common faint syndrome, now collectively named neurally mediated syncope. The significance of heart rate (HR) in these reflex-induced reactions remains unclear.Hypothesis: The study was undertaken to investigate the hemodynamic significance of HR in tilt-induced neurally mediated syncope.Methods: In all, 113 patients with syncope of unknown etiology were studied by head-up tilt test with invasive hemodynamic monitoring. Thirty-five patients (15 women, 20 men, age range 21 to 72 years) developed syncope and were enrolled for analysis. The hemodynamic data were compared between patients who developed bradycardia (vasovagal group, n = 15) and those without bradycardia (vasodepressor group, n = 20).Results: The baseline hemodynamic data (mean ± standard deviation) and the hemodynamic responses after 10-min headup tilt were similar between patients in the vasovagal and vasodepressor groups. During syncope, patients with vasovagal reaction developed hypotension and paradoxical bradycardia (HR = 52.4 ± 5.9 beats/min), while patients with vasodepressor reaction developed a precipitous drop in arterial blood pressure with inappropriate HR (105 ± 21 beats/min) compensation. Patients with vasovagal syncope manifested a significantly lower cardiac index and a significantly higher systemic

Head‐up tilt test provokes dynamic alterations in total peripheral resistance and cardiac output in children with vasovagal syncope

“…In VVS patients, the catecholamine content in the blood increases in the supine position, especially the adrenaline content (18,22,23). Chosy et al (22) also found that the level of catecholamine in urine was higher in patients with syncope, and Chan et al (23) found that the average resistance of the circulation was mainly controlled by the sympathetic nervous system. The content of noradrenaline and adrenaline in the serum of VVS patients has also been reported to be slightly higher than people without VVS in the supine position.…”

“…min/L, t = 3.861, p < 0.01). In VVS patients, the catecholamine content in the blood increases in the supine position, especially the adrenaline content . Chosy et al.…”