The Effects of Surgical Abolition of Left-to-Right Shunts on the Pulmonary Vascular Dynamics of Patients with Pulmonary Hypertension

Abstract

The preoperative and postoperative pulmonary artery pressures, the ratios of pulmonary to systemic arterial pressure, and of pulmonary to systemic vascular resistance were compared in 29 patients with congenital heart disease, left-to-right shunts, and pulmonary hypertension. These patients averaged 21 years of age and the time interval between operation and the postoperative catheterization averaged 11 months. The mean pulmonary artery pressure and the pulmonary artery to systemic artery pressure ratio fell significantly in all 12 patients with extracardiac left-to-right shunts (patent ductus arteriosus and aortopulmonary septal defect) and fell to normal in 10 of them. The pulmonary vascular/systemic vascular resistance ratio was abnormally elevated in only one patient postoperatively. In the 17 patients with atrial and ventricular septal defects the decline in pulmonary artery pressure and in the pulmonary/systemic arterial pressure ratio was less striking than in the patients with extracardiac shunts. These indices were normal postoperatively in only two of the nine patients with atrial septal defects and in none of the eight patients with ventricular septal defects. No significant changes were noted after operation in the pulmonary/systemic vascular resistance ratios in any of the 17 patients with intracardiac left-to-right shunts. From these observations it appears likely that some regression of the abnormalities in the pulmonary vascular bed occurs during the first year after closure of an extracardiac left-to-right shunt. On the other hand, there was little physiologic evidence that such favorable changes followed operation in the patients with atrial or ventricular septal defects.