RESUMEN
Surgical repair of tetralogy of Fallot (TOF) with reconstruction of the right ventricular (RV) outflow tract invariably results in pulmonary regurgitation. Chronic pulmonary regurgitation has been associated with RV dysfunction and decreased exercise performance. The present study assessed the influence of pulmonary valve replacement (PVR) for severe pulmonary regurgitation after previous TOF repair on cardiorespiratory exercise performance and RV function. Eighteen patients, between the ages of 8 and 18 years, underwent an exercise test and a cardiac magnetic resonance imaging scan at least 1 year after PVR. The exercise data were compared with those obtained from 24 age-matched normal controls and 27 age-matched patients with repaired TOF and a moderate degree of pulmonary regurgitation. A subgroup of 11 patients had an exercise test performed before and after PVR. Cardiopulmonary exercise performance was evaluated by determination of the ventilatory anaerobic threshold (VAT) and by the steepness of the slope of oxygen uptake versus exercise intensity (SVO2). After PVR there was a significant increase in VAT (86+/-11% before to 106.9+/-14% after, p = 0.03) and in SVO2 (1.71+/-0.47 to 2.3+/-0.39, p = 0.004). In patients examined after PVR, the VAT and SVO2 values were not significantly different from the values in the normal controls (104+/-15% [p>0.05] and 2.03+/-0.77 after PVR vs. 2.42+/-0.68 [p>0.25], respectively). In contrast, patients with repaired TOF and a moderate degree of pulmonary regurgitation had a significantly lower VAT (86+/-11%, p<0.05) and SVO2 (1.8+/-0.74 vs. 2.42+/-0.68, p<0.05) than normal controls. Magnetic resonance imaging studies revealed residual RV dilatation and dysfunction. However, there was no correlation between RV dilatation and RV dysfunction and aerobic exercise capacity. It is concluded that aerobic exercise capacity substantially improves after PVR for severe pulmonary regurgitation after previous TOF repair. Although the right ventricle remains significantly dilated and hypocontractile, there is no relation between RV function and exercise performance.