Spectrum of exercise intolerance in 45 patients with Ebstein's anomaly and observations on exercise tolerance in 11 patients after surgical repair.

To determine the effects of definitive operation for Ebstein's anomaly on rest and exercise cardiorespiratory function, cycle exercise studies were performed on 38 patients with Ebstein's anomaly before definitive operation and on 11 patients after operation. An atrial septal defect was present in 29 of the 38 preoperative patients and in none of the postoperative patients. Seven of the postoperative patients had tricuspid valvuloplasty and four had valve replacement. Exercise tolerance, as defined by maximal oxygen uptake, was significantly greater in patients after operation for Ebstein's anomaly than in the preoperative patients. However, exercise tolerance for preoperative patients without an atrial septal defect was similar to that for postoperative patients. Tricuspid valve repair or replacement appeared to affect favorably cardiac output response to exercise. Rest systemic arterial oxygen saturation increased from 88 to 95% and exercise saturation from 77 to 93% after operation. Rest ventilatory equivalent for oxygen decreased from 48 +/- 13 preoperatively to 37 +/- 6 postoperatively, and exercise ventilatory equivalent for oxygen decreased from 53 +/- 23 preoperatively to 38 +/- 6 postoperatively. Definitive operation (tricuspid valvuloplasty or replacement and atrial septal defect closure) for Ebstein's anomaly results in significant improvement of exercise tolerance, normalization of systemic arterial oxygen saturation and reduction of excess ventilation at rest and during exercise.