title: Cerebral Hemodynamics During Exercise and Recovery in Heart Transplant Recipients.
abstract: BACKGROUND
  The aims of this work were (1) to compare cerebral oxygenation-perfusion (COP), central hemodynamics, and peak oxygen uptake (V˙o2peak) in heart transplant recipients (HTRs) vs age-matched healthy controls (AMHCs) during exercise and recovery and (2) to study the relationships between COP, central hemodynamics, and V˙o2peak in HTRs and AMHCs.
  
  
  METHODS
  Twenty-six HTRs (3 women) and 27 AMHCs (5 women) were recruited. Maximal cardiopulmonary function (gas exchange analysis), cardiac hemodynamics (impedance cardiography), and left frontal COP (near-infrared spectroscopy) were measured continuously during and after a maximal ergocycle (Ergoline 800S, Bitz, Germany) test.
  
  
  RESULTS
  Compared with AMHCs, HTRs had lower V˙o2peak, maximal cardiac index (CImax), and maximal ventilatory variables (P < 0.05). COP was lower during exercise (oxyhemoglobin [ΔO2Hb], 50% and 75% of V˙O2peak, total hemoglobin [ΔtHb], 100% of V˙O2peak; P < 0.05), and recovery in HTRs (ΔO2Hb, minutes 2-5; ΔtHb, minutes 1-5; P < 0.05) compared with AMHCs. End-tidal pressure of CO2 was lower during exercise compared with that in AMHCs (P < 0.0001). In HTRs, CImax was positively correlated with exercise cerebral hemodynamics (R = 0.54-0.60; P < 0.01).
  
  
  CONCLUSIONS
  In HTRs, COP was reduced during exercise and recovery compared with that in AMHCs, potentially because of a combination of blunted cerebral vasodilation by CO2, cerebrovascular dysfunction, reduced cardiac function, and medication. The impaired V˙O2peak observed in HTRs was mainly caused by reduced maximal ventilation and CI. In HTRs, COP is impaired and is correlated with cardiac function, potentially impacting cognitive function. Therefore, we need to study which interventions (eg, exercise training) are most effective for improving or normalizing (or both) COP during and after exercise in HTRs.
authors.affiliation: Cardiovascular Prevention and Rehabilitation Centre (ÉPIC), Montréal Heart Institute and University of Montréal, Montréal, Québec, Canada; Research Center, Montreal Heart Institute and University of Montréal, Montréal, Québec, Canada; Department of Medicine, Faculty of Medicine, University of Montréal, Montréal, Québec, Canada. Electronic address: mathieu.gayda@icm-mhi.org.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Gayda
authors.affiliation: Cardiovascular Prevention and Rehabilitation Centre (ÉPIC), Montréal Heart Institute and University of Montréal, Montréal, Québec, Canada; Research Center, Montreal Heart Institute and University of Montréal, Montréal, Québec, Canada; Department of Medicine, Faculty of Medicine, University of Montréal, Montréal, Québec, Canada.
authors.forename: Audrey
authors.initials: A
authors.lastname: Desjardins
authors.affiliation: Cardiovascular Prevention and Rehabilitation Centre (ÉPIC), Montréal Heart Institute and University of Montréal, Montréal, Québec, Canada; Research Center, Montreal Heart Institute and University of Montréal, Montréal, Québec, Canada.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Lapierre
authors.affiliation: Laboratory, MOVE (EA6314), Faculty of Sport Sciences, Université de Poitiers, Poitiers, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Dupuy
authors.affiliation: Cardiovascular Prevention and Rehabilitation Centre (ÉPIC), Montréal Heart Institute and University of Montréal, Montréal, Québec, Canada; The School of Social Work, McGill University, Montréal, Québec, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Fraser
authors.affiliation: Department of Psychology, Perform Centre, Concordia University, Montréal, Québec, Canada; Research Centre, Institut Universitaire de Gériatrie de Montréal, Montréal, Québec, Canada.
authors.forename: Louis
authors.initials: L
authors.lastname: Bherer
authors.affiliation: Cardiovascular Prevention and Rehabilitation Centre (ÉPIC), Montréal Heart Institute and University of Montréal, Montréal, Québec, Canada; Research Center, Montreal Heart Institute and University of Montréal, Montréal, Québec, Canada; Department of Medicine, Faculty of Medicine, University of Montréal, Montréal, Québec, Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Juneau
authors.affiliation: Research Center, Montreal Heart Institute and University of Montréal, Montréal, Québec, Canada; Department of Medicine, Faculty of Medicine, University of Montréal, Montréal, Québec, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: White
authors.affiliation: CIC INSERM 1432, Plateforme d'Investigation Technologique, Dijon University Hospital, Dijon, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Gremeaux
authors.affiliation: Research Centre, Institut Universitaire de Gériatrie de Montréal, Montréal, Québec, Canada.
authors.forename: Véronique
authors.initials: V
authors.lastname: Labelle
authors.affiliation: Cardiovascular Prevention and Rehabilitation Centre (ÉPIC), Montréal Heart Institute and University of Montréal, Montréal, Québec, Canada; Research Center, Montreal Heart Institute and University of Montréal, Montréal, Québec, Canada; Department of Medicine, Faculty of Medicine, University of Montréal, Montréal, Québec, Canada.
authors.forename: Anil
authors.initials: A
authors.lastname: Nigam
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002540:Cerebral Cortex / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D016027:Heart Transplantation; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D020127:Recovery of Function; D066027:Transplant Recipients; D055815:Young Adult