RESUMEN
Seven female patients (age 27 to 53 yr) with significant mitral stenosis performed continuous, incremental, maximal treadmill exercise tests the day before and within 3-5 days after catheter-balloon valvuloplasty. Mitral valve area determined by the echo-Doppler method increased from 0.9 +/- 0.3 cm2 to 1.9 +/- 0.7 cm2 (p < 0.02). Mean left atrial pressure was reduced from 24 +/- 8 to 13 +/- 7 mmHg (p < 0.01) and mean pulmonary artery pressure from 36 +/- 13 to 28 +/- 10 mmHg (p < 0.02) with a non-significant increase in cardiac output from 3.6 +/- 1.2 to 4.0 +/- 1.7 l/min. After catheter-balloon valvuloplasty all patients reached a higher maximal workload during exercise, and mean value of oxygen consumption and pulmonary ventilation were significantly lower in submaximal workloads. The calculated ventilatory equivalent for oxygen was significantly reduced in submaximal and in maximal workloads after catheter-balloon valvuloplasty. Peak oxygen consumption and the ventilatory anaerobic threshold were not changed after catheter-balloon valvuloplasty (pre 15.59 +/- 2.72 vs post 16.90 +/- 3.44 and pre 12.10 +/- 2.55 vs post 12.62 +/- 2.71 ml/kg/min, respectively). We concluded that after catheter-balloon valvuloplasty the cost of breathing was reduced and the oxygen consumed was more effectively utilized during exercise. Increases in peak oxygen consumption and in ventilatory anaerobic threshold would require circulatory and metabolic adaptations in response to increased physical activity and were not observed when cardiopulmonary tests were performed early after catheter-balloon valvuloplasty.