Postoperative use of the hydrogen-sensitive, platinum-tipped electrode: Detection of residual left to right shunts

Seventy-seven patients submitted for surgical correction of left to right cardiac shunts were studied postoperatively by the hydrogen-sensitive, platinum-tipped electrode technic. The series was composed of atrial septal defects (51 patients), ventricular septal defects (20 patients) and a miscellaneous group (6 patients). Positive hydrogen electrode studies indicating persistent postoperative shunting were observed in 5 atrial septal defects (10%), 9 ventricular defects (45%) and 3 of the miscellaneous group. In this series, surgical closure of atrial septal defects was quite successful (90%), the results being better for secundum (94%) than for primum defects (60%). Operative closure of ventricular septal defects was less successful (55%) for either uncomplicated defects (60%) or those complicated by pulmonic stenosis (53%). In each of 8 patients results obtained from electrode studies were confirmed by catheterization or by further surgery. Twentytwo patients whose atrial defects were considered closed retained the split of the pulmonic second sound; therefore, this sign does not necessarily indicate a persistent shunt. It is concluded that the hydrogen-sensitive, platinum-tipped electrode technic offers a simple, sensitive and accurate method for evaluating operative success in the repair of various left to right cardiac shunts.