Evaluation of the Appropriate Root Pressure for Maintaining Heartbeat during an Aortic Cross-clamp for Primary Repair of the Aortic Arch in Premature Infants with Associated Cardiac Anomalies

We developed a new cardiopulmonary bypass (CPB) method to minimize myocardial damage during aortic arch reconstruction. In this method, coronary flow and heartbeat were stabilized by maintaining the aortic root pressure with an adjusted preload of the ventricle during aortic cross-clamping. This study was performed to determine the appropriate root pressure to maintain the heartbeat without causing deterioration of ventricular function. Study 1. Under partial CPB, the ascending aorta was cross-clamped in 6 pigs (group 1). Experimental data at various systolic aortic root pressures was analysed to determine the appropriate root pressure. Study 2. In group 2 (control, n＝6), the aorta was not clamped, while in group 3 (n＝6), the aorta was cross-clamped for 60 min and the systolic aortic root pressure was maintained at the pressure determined in study 1. Study 1. The diastolic coronary flow was stabilized at values comparable to that before initiation of CPB (6.6±1.4ml/beat) when the systolic aortic root pressure was above 80mmHg. Intracardiac pressure and the myocardial oxygen consumption (MvO2) seemed to be acceptable when the systolic aortic root pressure was below 100mmHg. Therefore, 90mmHg was selected for study 2. Study 2. Perioperative cardiac function did not differ between the groups. We concluded that 90mmHg was the systolic aortic root pressure appropriate for this method.