title: Cardio-vascular reserve index (CVRI) during exercise complies with the pattern assumed by the cardiovascular reserve hypothesis.
abstract: OBJECTIVE
  The Cardio-vascular reserve index (CVRI) had been empirically validated in diverse morbidities as a quantitative estimate of the reserve assumed by the cardiovascular reserve hypothesis. This work evaluates whether CVRI during exercise complies with the cardiovascular reserve hypothesis.
  
  
  METHODS
  Retrospective study based on a database of patients who underwent cardio-pulmonary exercise testing (CPX) for diverse indications.
  
  
  METHODS
  Patient's physiological measurements were retrieved at four predefined CPX stages (rest, anaerobic threshold, peak exercise and after 2min of recovery). CVRI was individually calculated retrospectively at each stage.
  
  
  RESULTS
  Mean CVRI at rest was 0.81, significantly higher (p<0.001) than at all other stages. CVRI decreased with exercise, reaching an average at peak exercise of 0.35, significant lower than at other stages (p<0.001) and very similar regardless of exercise capacity (mean CVRI 0.33-0.37 in 4 groups classified by exercise capacity, p>0.05). CVRI after 2min of recovery rose considerably, most in the group with the best exercise capacity and least in those with the lowest exercise capacity.
  
  
  CONCLUSIONS
  CVRI during exercise fits the pattern predicted by the cardiovascular reserve hypothesis. CVRI decreased with exercise reaching a minimum at peak exercise and rising with recovery. The CVRI nadir at peak exercise, similar across groups classified by exercise capacity, complies with the assumed exhaustion threshold. The clinical utility of CVRI should be further evaluated.
authors.affiliation: Lung Institute, Sheba Medical Center, Ramat-Gan, Israel; Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Segel
authors.affiliation: School of Electrical Engineering-Systems, Faculty of Engineering, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Ben-Zion
authors.initials: BZ
authors.lastname: Bobrovsky
authors.affiliation: Rabin Medical Center, Petach Tikva, Israel.
authors.forename: Itay E
authors.initials: IE
authors.lastname: Gabbay
authors.affiliation: Lung Institute, Sheba Medical Center, Ramat-Gan, Israel; Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
authors.forename: Issahar
authors.initials: I
authors.lastname: Ben-Dov
authors.affiliation: Lung Institute, Sheba Medical Center, Ramat-Gan, Israel.
authors.forename: Ronen
authors.initials: R
authors.lastname: Reuveny
authors.affiliation: Rabin Medical Center, Petach Tikva, Israel; Department of Epidemiology, School of Public Health, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel. Electronic address: ugabai@post.tau.ac.il.
authors.forename: Uri
authors.initials: U
authors.lastname: Gabbay
mesh_terms: D015308:Anaerobic Threshold / Q000502:physiology; D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D012189:Retrospective Studies
keywords: Anaerobic threshold; Cardio-pulmonary exercise testing (CPX); Cardio-vascular reserve hypothesis; Cardio-vascular reserve index (CVRI); Exercise capacity; Peak exercise