Physiologic Studies Early after Repair of Tetralogy of Fallot

Physiologic studies have been carried out during the first 3 days after intracardiac repair of tetralogy of Fallot. All patients survived. The ratio between systolic pressure in right ventricle and a systemic artery was 0.7 or less in all cases and did not vary significantly during the period of study. Residual left-to-right shunts of moderate degree were demonstrated in three patients (repaired with Teflon prostheses). In one of these three, no definite evidence of shunt could be found 2 weeks after operation. Additional abnormal circulatory pathways exist in these patients. Clear evidence was obtained of left-to-right shunting through aorticopulmonary collateral connections in one case. Systemic index was usually below normal or in the low normal range. It was usually lower on the second and third postoperative days than on the first postoperative day. Left atrial pressure was sometimes strikingly higher than right atrial pressure 30 minutes after repair, but not thereafter. Pulmonary vascular resistance was normal or slightly elevated. Gas exchange and management were adequate to maintain normal or near normal oxygen and carbon dioxide levels in arterial blood. Mild metabolic acidosis existed on the first 2 days, but had generally cleared by the third day. The implications of these data are discussed relative to ventricular function and performance, adequacy and technic of surgical repair, administration of blood after operation, and the state of preparedness in the lung and left ventricle in patients with tetralogy of Fallot.