title: Disentangling cardiovascular control mechanisms during head-down tilt via joint transfer entropy and self-entropy decompositions.
abstract: A full decomposition of the predictive entropy (PE) of the spontaneous variations of the heart period (HP) given systolic arterial pressure (SAP) and respiration (R) is proposed. The PE of HP is decomposed into the joint transfer entropy (JTE) from SAP and R to HP and self-entropy (SE) of HP. The SE is the sum of three terms quantifying the synergistic/redundant contributions of HP and SAP, when taken individually and jointly, to SE and one term conditioned on HP and SAP denoted as the conditional SE (CSE) of HP given SAP and R. The JTE from SAP and R to HP is the sum of two terms attributable to SAP or R plus an extra term describing the redundant/synergistic contribution to the JTE. All quantities were computed during cardiopulmonary loading induced by -25° head-down tilt (HDT) via a multivariate linear regression approach. We found that: (i) the PE of HP decreases during HDT; (ii) the decrease of PE is attributable to a lessening of SE of HP, while the JTE from SAP and R to HP remains constant; (iii) the SE of HP is dominant over the JTE from SAP and R to HP and the CSE of HP given SAP and R is prevailing over the SE of HP due to SAP and R both in supine position and during HDT; (iv) all terms of the decompositions of JTE from SAP and R to HP and SE of HP due to SAP and R were not affected by HDT; (v) the decrease of the SE of HP during HDT was attributed to the reduction of the CSE of HP given SAP and R; (vi) redundancy of SAP and R is prevailing over synergy in the information transferred into HP both in supine position and during HDT, while in the HP information storage synergy and redundancy are more balanced. The approach suggests that the larger complexity of the cardiac control during HDT is unrelated to the baroreflex control and cardiopulmonary reflexes and may be related to central commands and/or modifications of the dynamical properties of the sinus node.
authors.affiliation: Department of Biomedical Sciences for Health, University of Milan Milan, Italy ; Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato Milan, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Porta
authors.affiliation: BIOtech, Department of Industrial Engineering, University of Trento Trento, Italy ; IRCS PAT-FBK Trento, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Faes
authors.affiliation: Department of Electronics Information and Bioengineering, Politecnico di Milano Milan, Italy ; Department of Emergency and Intensive Care, San Gerardo Hospital Monza, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Marchi
authors.affiliation: Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato Milan, Italy.
authors.forename: Vlasta
authors.initials: V
authors.lastname: Bari
authors.affiliation: IRCCS Fondazione Salvatore Maugeri Milan, Italy.
authors.forename: Beatrice
authors.initials: B
authors.lastname: De Maria
authors.affiliation: Department of Emergency, L. Sacco Hospital Milan, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Guzzetti
authors.affiliation: Department of Emergency, L. Sacco Hospital Milan, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Colombo
authors.affiliation: Department of Anesthesia and Intensive Care, IRCCS Humanitas Clinical and Research Center Rozzano, Italy.
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Raimondi
keywords: autonomic nervous system; baroreflex; blood pressure variability; cardiopulmonary coupling; heart rate variability; information dynamics; multivariate linear regression analysis