title: Frequency domain assessment of the coupling strength between ventricular repolarization duration and heart period during graded head-up tilt.
abstract: We test the hypothesis that the degree of correlation between ventricular repolarization duration (VRD) and heart period (HP) carries information on cardiac autonomic regulation. The degree of correlation was assessed in the frequency domain using squared coherence function during an experimental protocol known to gradually induce a shift of sympathovagal balance toward sympathetic predominance (ie, graded head-up tilt). We observed a progressive decrease of squared coherence with tilt table inclination, thus confirming the working hypothesis. The VRD-HP uncoupling occurs in the high-frequency band, centered on the respiratory rate, thus suggesting that vagal withdrawal is responsible for the VRD-HP uncoupling.
authors: Department of Technologies for Health, Galeazzi Orthopedic Institute, University of Milan, Milan, Italy. alberto.porta@unimi.it
authors: Alberto
authors: A
authors: Porta
authors: Vlasta
authors: V
authors: Bari
authors: Fabio
authors: F
authors: Badilini
authors: Eleonora
authors: E
authors: Tobaldini
authors: Tomaso
authors: T
authors: Gnecchi-Ruscone
authors: Nicola
authors: N
authors: Montano
mesh_terms: D000328:Adult; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D013564:Sympathetic Nervous System / Q000503:physiopathology; D018667:Tilt-Table Test / Q000379:methods