Postoperative exercise tolerance after aortic valve replacement by small-size prosthesis - Functional consequence of small-size aortic prosthesis

OBJECTIVES The objective of this study was to determine whether a small-siz e valve prosthesis contributes to exercise intolerance, as assessed by VO2 measurement during an exhaustive cycle ergometer exercise. BACKGROUNDS The determinants of exercise capacity after mechanical aortic r eplacement are not well known. The selection of small valve sizes has, howe ver, been described as an independent predictor of exercise intolerance as assessed by exercise duration. Maximal oxygen uptake (VO2, max) is a good i ndex 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: Medtro nic Hall and St Jude Medical. A healthy sedentary control group (n = 14) pa ired 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 imm ediately 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 sim ilar. The mean and peak gradients at rest and during exercise were not corr elated with VO2 max. CONCLUSIONS Valve replacement by small aortic prosthesis does not seem to b e a factor of exercise intolerance as assessed by VO2 max in patients witho ut LVEF dysfunction before surgery. (C) 2000 by the American College of Car diology.