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

Abstract Background Pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries (PA/VSD/MAPCAs) is a rare form of congenital heart disease characterized by the entirety of pulmonary blood flow originating from systemic vessels. The purpose of this study was to measure the residual collateral flow following harvesting of the MAPCAs for surgical repair. Methods Thirty-two patients with PA/VSD/MAPCAs who were undergoing their first surgical procedure were enrolled in this study. 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 in order to accurately measure residual collateral flow. During the period of aortic cross-clamp (for VSD repair), the diversion loop was opened for one-minute intervals and the residual collateral flow collected. The systemic perfusion temperature was 25 degrees and flow rate was 100 ml/Kg/min. Results The mean residual collateral flow was 5.5 ml/Kg/min, with a range of 0.8 to 15.2 ml/Kg/min. The corresponding calculated Qp:Qs values ranged from 1.01 to 1.36. There was a significant correlation between residual collateral flow and pre-operative saturation (p Conclusions The data demonstrate a wide range of residual collateral flow following harvesting of the MAPCAs. The amount of residual collateral flow was correlated with pre-operative 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.