title: Pulmonary oxygen uptake and heart rate kinetics during the six-minute walk test in transplant recipients.
abstract: BACKGROUND
  The effect of organ transplantation on arterial compliance, pulmonary oxygen uptake (VO2p) and heart rate kinetics during the 6-minute walk test (6-MWT) remains unknown.
  
  
  METHODS
  Twenty-two thoracic (heart and/or lung) organ transplant recipients (TOTR, 51+/-12 years) and 30 abdominal (kidney, kidney-pancreas, or liver) organ transplant recipients (AOTR, 46+/-11 years) from the 2006 Canadian Transplant Games, and 37 healthy controls (HC) completed a 6-MWT. VO2p, heart rate kinetics, and arterial compliance were determined.
  
  
  RESULTS
  The 6-MWT distance and highest VO2p were significantly lower in TOTR and AOTR versus HC. The highest 6-MWT heart rate was lower in TOTR (11%) and AOTR (13%) versus HC. VO2p kinetics were slower in TOTR (52+/-11 sec, P<or=0.001) and AOTR (45+/-24 sec, P<or=0.001) versus HC (28+/-9 sec). Heart rate kinetics were slower in TOTR (100+/-49 sec) versus AOTR (41+/-21 sec, P<or=0.001) and HC (34+/-21 sec, P<or=0.001), but not between AOTR and HC. Small and large artery compliance were 26% (P=0.007) and 19% (P=0.004) lower, respectively, in TOTR versus HC. Large artery compliance was 14% lower in TOTR versus AOTR (P=0.017). 6-MWT distance was significantly related to VO2p kinetics (r=-0.35) and the highest 6-MWT VO2p (r=0.72).
  
  
  CONCLUSIONS
  TOTR and AOTR have abnormal VO2p kinetics, which is secondary to prolonged heart rate kinetics and impaired vascular function in TOTR, but not AOTR.
authors.affiliation: Cardiovascular Therapeutic Exercise Laboratory, Faculty of Rehabilitation Medicine, Alberta Research Centre for Child Health Evidence, Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Corey R
authors.initials: CR
authors.lastname: Tomczak
authors.forename: Darren E R
authors.initials: DE
authors.lastname: Warburton
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Riess
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Jendzjowsky
authors.forename: Ben T
authors.initials: BT
authors.lastname: Esch
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Liang
authors.forename: Robert G
authors.initials: RG
authors.lastname: Haennel
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Haykowsky
mesh_terms: D000328:Adult; D000368:Aged; D001158:Arteries / Q000502:physiology; D016022:Case-Control Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D016027:Heart Transplantation / Q000502:physiology; D006801:Humans; D016030:Kidney Transplantation / Q000502:physiology; D016031:Liver Transplantation / Q000502:physiology; D016040:Lung Transplantation / Q000502:physiology; D008297:Male; D008875:Middle Aged; D016377:Organ Transplantation / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D016035:Pancreas Transplantation / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D016138:Walking / Q000502:physiology*