Cardiovascular abnormalities following surgery for left-to-right shunts. Observations in atrial septal defects, ventricular septal defects, and patent ductus arteriosus.

SUMMARY Seventy-two patients with left-to-right shunts were studied an average of 5 years after operation. Persistent residual shunts occurred in 24 of the 72 patients and were unsuspected clinically in 11. While significant residual shunts were usually suspected in the group with ventricular septal defects (VSD), residual shunts in the group with atrial septal defects (ASD) were frequently unsuspected. Abnormalities in pulmonary vascular reactivity as determined by excessive responses to hypoxia or exercise, or both, were noted in a significant number of cases of VSD and patent ductus arteriosus. Such unusual reactivity was not seen as frequently in the ASD group. Low cardiac output responses to exercise were noted in nearly half of the patients. These studies illustrate the importance of long-term follow-up hemodynamic studies on postoperative patients with left-to-right shunts and indicate the necessity for exercise and hypoxia studies in addition to resting observations. ALTHOUGH several studies have been published regarding patients who have undergone surgical closure of left-to-right shunts at the atrial, ventricular, and great vessel level, relatively little information is available regarding long-term follow-up hemo-dynamic data.1-5 Reports concerning hemody-namic responses to the stress of exercise and hypoxia are limited. The purposes of this postoperative evaluation of left-to-right shunts were (1) to Pulmonary vascular reactivity determine whether unsuspected residual shunting may occur in asymptomatic patients, (2) to assess the reactivity of the pulmonary vascular bed, and (3) to determine the adequacy of ventricular function as measured by cardiac output responses to exercise. Methods A total of 72 patients were studied from 6 months to 13 years after operation. Surgical correction had been carried out on 31 of the 72 patients for ventricular septal defects (VSD) an average of 3.1 years before this study, on 15 patients with patent ductus arteriosus (PDA), an average of 6.5 years before, and on 26 with atrial septal defects an average of 5.4 years (table 1). Initially, patients were selected who had undergone surgical correction 5 to 10 years previously.