title: In vivo cardiac phase response curve elucidates human respiratory heart rate variability.
abstract: Recovering interaction of endogenous rhythms from observations is challenging, especially if a mathematical model explaining the behaviour of the system is unknown. The decisive information for successful reconstruction of the dynamics is the sensitivity of an oscillator to external influences, which is quantified by its phase response curve. Here we present a technique that allows the extraction of the phase response curve from a non-invasive observation of a system consisting of two interacting oscillators--in this case heartbeat and respiration--in its natural environment and under free-running conditions. We use this method to obtain the phase-coupling functions describing cardiorespiratory interactions and the phase response curve of 17 healthy humans. We show for the first time the phase at which the cardiac beat is susceptible to respiratory drive and extract the respiratory-related component of heart rate variability. This non-invasive method for the determination of phase response curves of coupled oscillators may find application in many scientific disciplines.
authors.affiliation: Institut für Pädagogik, Christian-Albrechts-Universität zu Kiel, Olshausenstrasse 75, 24118 Kiel, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Kralemann
authors.forename: Matthias
authors.initials: M
authors.lastname: Frühwirth
authors.forename: Arkady
authors.initials: A
authors.lastname: Pikovsky
authors.forename: Michael
authors.initials: M
authors.lastname: Rosenblum
authors.forename: Thomas
authors.initials: T
authors.lastname: Kenner
authors.forename: Jochen
authors.initials: J
authors.lastname: Schaefer
authors.forename: Maximilian
authors.initials: M
authors.lastname: Moser
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011674:Pulse; D012119:Respiration; D012815:Signal Processing, Computer-Assisted