SINCE September 1946, when Potts and Smith1introduced a new operative technic for the relief of cyanosis in patients with a tetralogy of Fallot, more than 350 children with various types of congenital heart disease have been operated on at the Children's Memorial Hospital in Chicago. The types of congenital heart disease encountered and the mortality following surgical intervention are shown in table 1. The most important factor in successful cardiac surgery is the recognition and appreciation of the physiologic and pathologic changes in these patients by both the surgeon and the anesthesiologist and the absolute confidence of these two in one another. The basic anesthetic technic that my colleagues and I have used in all types of cardiac surgery is fairly simple and has been discussed in greater detail in previous reports.2Anesthesia is administered through an endotracheal tube by the to and fro absorption technic, with