Measurement of Residual Collateral Flow in Pulmonary Atresia with Major Aortopulmonary Collaterals.

Background. Pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries (MAPCAs) is a rare form of congenital heart disease characterized by the entirety of pulmonary blood flow originating from systemic vessels. This study measured the residual collateral flow after harvesting of the MAPCAs for surgical repair. Methods. The study enrolled 32 patients with pulmonary atresia with ventricular septal defect and MAPCAs who were undergoing their first surgical procedure. The median age was 6.8 months, and median weight was 5.7 kg. The patients had a mean of 4.2 +/- 0.7 MAPCAs. The cardiopulmonary bypass circuit was modified to contain a diversion loop in the left ventricular vent system to accurately measure residual collateral flow. During the period of aortic cross-clamp (for ventricular septal defect repair), the diversion loop was opened for 1-minute intervals, and the residual collateral flow collected. The systemic perfusion temperature was 25 degrees and flow rate was 100 mL . kg(-1) . min(-1). Results. The mean residual collateral flow was 5.5 mL . kg(-1) . min(-1) (range, 0.8 to 15.2 mL . kg(-1) . min(-1)). The corresponding calculated pulmonary blood flow-to- systemic blood flow ratio values ranged from 1.01 to 1.36. There was a significant correlation between residual collateral flow and preoperative saturation (p < 0.05). Conclusions. The data demonstrate a wide range of residual collateral flow values after harvesting of the MAPCAs. The amount of residual collateral flow was correlated with preoperative saturation. These results suggest that some patients at the higher end of this spectrum may require adjustments in pump flow to assure adequate systemic perfusion. (C) 2019 by The Society of Thoracic Surgeons