PMID: 11316131Apr 24, 2001Paper

Elevated parasympathetic nerve tone in isoproterenol-induced neurally mediated syncope during head-up tilt testing

Japanese Circulation Journal
A TakeiM Yokoyama

Abstract

To clarify the autonomic nerve mechanisms whereby isoproterenol induces vasovagal reaction, 32 patients with recurrent syncopal episodes of unknown origin underwent head-up tilt testing. Syncope was induced in 11 patients by a control tilt (control/+ group). The remaining 21 patients (control/- group) underwent the procedure during isoproterenol infusion. Syncope was induced in 13 (isoproterenol/+ group), but not in the remaining 8 patients (isoproterenol/- group). High-frequency component (HF) and low-frequency component (LF)/HF, which are indices of heart rate variability, were assessed for 2-min intervals at baseline (T1) during the initial phase (T2) and at the end (T3) of tilting in each test. The ratios of HF and LF/HF at T2/T1 and T3/T2 were calculated. The HF value at T3 in the control/+ group was greater than that in the control/- group (1.47+/-0.91 vs 0.75+/-0.34; p<0.05). The HF value at T3 in the isoproterenol/+ group was significantly greater than those in the isoproterenol/- group (1.19+/-1.04 vs 0.43+/-0.23; p<0.05). The HF value at T2 in the isoproterenol/+ tended to be greater than in the isoproterenol/- group (1.30+/-0.85 vs 0.66+/-0.53; p=0.07). The ratio of HF for T2/T1 in isoproterenol/+ was greater than in...Continue Reading

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Citations

Jul 24, 2002·Circulation Journal : Official Journal of the Japanese Circulation Society·Satoshi KoyamaKenjiro Kikuchi
Jan 28, 2003·Circulation Journal : Official Journal of the Japanese Circulation Society·Kenji HaradaSusumu Ito

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