Frequency domain assessment of the coupling strength between ventricular repolarization duration and heart period during graded head-up tilt

Alberto Porta, Vlasta Bari, Fabio Badilini, Eleonora Tobaldini, Tomaso Gnecchi-Ruscone, Nicola Montano

Research output: Contribution to journalArticle


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.

Original languageEnglish
Pages (from-to)662-668
Number of pages7
JournalJournal of Electrocardiology
Issue number6
Publication statusPublished - Nov 2011



  • Autonomic nervous system
  • Head-up tilt
  • Heart rate variability
  • QT variability
  • QT-R-R relation

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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