obtained before and after extracorporeal circulation and analyzed for radioactivity. It was found that there was no significant decrease in the radioactivity of the heart muscle obtained after extracorporeal circulation when compared with the radioactivity of the muscle samples obtained be¬ fore cardiopulmonary bypass. This indicates that the amount of radioactivity ( digoxin or its metabolites, or both ) in these muscle samples was not decreased by extracor¬ poreal circulation.Pediatrics 31:958 (June) 1963 Serial cardiac catheterization and angiocardiographic studies were performed on 14 patients, demonstrating spon¬ taneous functional closure of ventricular septal defects oc¬