Cardiovascular and cardiorespiratory coupling analyses: a review

Abstract

Recently, methods have been developed to analyse couplings in dynamic systems. In the field of medical analysis of complex cardiovascular and cardiorespiratory systems, there is growing interest in how insights may be gained into the interaction between regulatory mechanisms in healthy and diseased persons. The couplings within and between these systems can be linear or nonlinear. However, the complex mechanisms involved in cardiovascular and cardiorespiratory regulation very likely interact with each other in a nonlinear way. Recent advances in nonlinear dynamics and information theory have allowed the multivariate study of information transfer between time series. They therefore might be able to provide additional diagnostic and prognostic information in medicine and might, in particular, be able to complement traditional linear coupling analysis techniques. In this review, we describe the approaches (Granger causality, nonlinear prediction, entropy, symbolization, phase synchronization) most commonly applied to detect direct and indirect couplings between time series, especially focusing on nonlinear approaches. We will discuss their capacity to quantify direct and indirect couplings and the direction (driver–response relationship) of the considered interaction between different biological time series. We also give their basic theoretical background, their basic requirements for application, their main features and demonstrate their usefulness in different applications in the field of cardiovascular and cardiorespiratory coupling analyses.

Effects of slow and regular breathing exercise on cardiopulmonary coupling and blood pressure

“…However, as HR and BP can be affected by complex interactions through different feedback mechanisms [9,28], there are nonlinear interactions underlying the physiological feedback control systems [26,34,40]. Therefore, for the reliable investigation of CPC, signal analysis techniques capable of dealing with non-stationary and nonlinear signals should be adopted.…”

“…There is growing interest in investigating the interaction between cardiovascular and cardiorespiratory systems [34,40]. Analysis of cardiopulmonary coupling (CPC) provides information about the coupling dynamics between the cardiorespiratory systems [3], leading to improved knowledge of the interacting regulatory mechanisms under different physiological and pathophysiological conditions [34].…”

“…Analysis of cardiopulmonary coupling (CPC) provides information about the coupling dynamics between the cardiorespiratory systems [3], leading to improved knowledge of the interacting regulatory mechanisms under different physiological and pathophysiological conditions [34]. Amplitude and phase dynamics are two major aspects of the investigation for CPC, and amplitude dynamics was mainly considered in most of studies [3].…”

“…The change of phase dynamics during PB procedure, however, has rarely been explored simultaneously. As coupled oscillators interact both through their phases and amplitudes, analysis of phase dynamics has been used to investigate the strength and direction of CPC [3,27,30,34]. Compared with amplitude-based coupling analysis, phase dynamics are more sensitive to the subtle change of coupling strength [25].…”

Assessing causality in brain dynamics and cardiovascular control

“…Among the contributions covering the issue of assessing causality in the information domain, Schulz et al [21] review nonlinear methods for the estimation of the coupling strength along a specific time direction with special emphasis on those designed in the information domain and exploiting symbolization procedures. Marwan et al [22] propose a novel approach to the assessment of directionality in cardiorespiratory and cardiovascular interactions based on conditional probabilities of recurrences.…”