Residual right-to-left atrial shunt following surgical relief of pulmonary valvar stenosis.

Of 264 patients undergoing pulmonary valvotomy for pulmonary stenosis or atresia at the University of Minnesota, 23 had a right-to-left shunt preoperatively. In none was the atrial communication closed at the time of pulmonary valvotomy. At postoperative cardiac catheterization, no atrial level shunt was found in 19, indicating that effective closure of the communication had occurred. In the remaining 4, a right-to-left shunt persisted despite adequate relief of the stenosis. Each of the 4 has undergone subsequent closure of the atrial septal communication without difficulty.