title: Postoperative exercise tolerance after aortic valve replacement by small-size prosthesis: functional consequence of small-size aortic prosthesis.
abstract: OBJECTIVE
  The objective of this study was to determine whether a small-size valve prosthesis contributes to exercise intolerance, as assessed by VO2 measurement during an exhaustive cycle ergometer exercise.
  
  
  BACKGROUND
  The determinants of exercise capacity after mechanical aortic replacement are not well known. The selection of small valve sizes has, however, been described as an independent predictor of exercise intolerance as assessed by exercise duration. Maximal oxygen uptake (VO2max) is a good index of exercise tolerance.
  
  
  METHODS
  Fourteen patients were eligible, with a mean age of 62 +/- 6 years. Before surgery, the mean left ventricular ejection fraction (LVEF) was 73 +/- 8%. Two valve types with small diameter (19 to 21 mm) were used: Medtronic Hall and St Jude Medical. A healthy sedentary control group (n = 14) paired for age, weight and size was constituted. After one year of follow-up, cardiorespiratory tests were performed. In addition, the gradients through the prostheses were determined by continuous pulse Doppler at rest and immediately after the cardiorespiratory test. RESULTS The exercise tolerance was not significantly different between the control group and patient group: VO2 peak (21.7 vs. 20.4 ml/kg/min; p = 0.42), workloads (115 vs. 93 W; p = 0.13) and ventilatory parameters were similar. The mean and peak gradients at rest and during exercise were not correlated with VO2max.
  
  
  CONCLUSIONS
  Valve replacement by small aortic prosthesis does not seem to be a factor of exercise intolerance as assessed by VO2max in patients without LVEF dysfunction before surgery.
authors.affiliation: Services de Cardiologie, Hopital Arnaud de Villeneuve, Montpellier, France.
authors.forename: P
authors.initials: P
authors.lastname: Becassis
authors.forename: M
authors.initials: M
authors.lastname: Hayot
authors.forename: J M
authors.initials: JM
authors.lastname: Frapier
authors.forename: F
authors.initials: F
authors.lastname: Leclercq
authors.forename: L
authors.initials: L
authors.lastname: Beck
authors.forename: J
authors.initials: J
authors.lastname: Brunet
authors.forename: E
authors.initials: E
authors.lastname: Arnaud
authors.forename: C
authors.initials: C
authors.lastname: Prefaut
authors.forename: P A
authors.initials: PA
authors.lastname: Chaptal
authors.forename: J M
authors.initials: JM
authors.lastname: Davy
authors.forename: P
authors.initials: P
authors.lastname: Messner-Pellenc
authors.forename: R
authors.initials: R
authors.lastname: Grolleau
mesh_terms: D000368:Aged; D000886:Anthropometry; D001021:Aortic Valve / Q000601:surgery*; D015150:Echocardiography, Doppler; D004867:Equipment Design; D005080:Exercise Test; D005260:Female; D006349:Heart Valve Diseases / Q000601:surgery*; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D010807:Physical Endurance; D011184:Postoperative Period; D013147:Spirometry