Nonlinear Coupling Among Heart Rate,Blood Pressure,and Respiration in Patients Susceptible to Neuromediated Syncope |
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Authors: | F Censi G Calcagnini S Strano P Bartolini V Barbaro |
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Institution: | (1) Biomedical Engineering Laboratory, Instituto Superiore di Sanita, Roma, Italy;(2) Clinical Pathophysiology, La Sapienza University of Rome, Roma, Italy |
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Abstract: | The aim of this study is to evaluate the degree of coupling between the cardiovascular variability series and the respiration in subjects susceptible to neurally mediated syncope. Twenty-one informed patients susceptible to syncope and ten sex- and age-matched control subjects were enrolled in the study. ECG, respiration activity, and arterial blood pressure were simultaneously recorded at rest (controlled and free breathing) and during the 70° head-up TILT test (free breathing). The degree of nonlinear coupling among heart rate variability (HRV), blood pressure variability (BPV), and respiration was quantified by means of two indices according to a multivariate embedding-based approach. Eleven patients developed syncope during the TILT test. We found that during the late TILT phase, the TILT-positive group experienced a significant increase in nonlinear coupling respect to the mid TILT phase (p < 0.01, Wilcoxon nonparametric test for pair data) while the TILT-negative group did not (p < 0.01, Mann-Whitney U-test). If the proposed nonlinear coupling indexes can be considered expression of the coupling mechanisms involved in the vagal regulation of the cardiovascular system, an increase in vagal tone accompanied by a decrease in sympathetic activity seem to occur before a vasovagal event. © 2003 Biomedical Engineering Society.
PAC2003: 8719Hh, 8719Uv, 8719La |
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Keywords: | Multivariate embedding technique Heart rate variability Cardiorespiratory coordination |
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