Preoperative total pulmonary blood flow predicts right ventricular pressure in patients early after complete repair of tetralogy of Fallot and pulmonary atresia with major aortopulmonary collateral arteries

Objective: The management of patients with tetralogy of Fallot (ToF) and pulmonary atresia (PA) with major aortopulmonary collateral arteries (MAPCAs) is challenging. Frequently it is difficult to predict whether complete repair with closure of the ventricular septal defect (VSD) will be tolerated. The aim of this study was to investigate whether measurements of preoperative pulmonary blood flow are associated with early postoperative outcome after VSD closure. Methods: In this retrospective study, the data from 10 patients who had undergone a cardiac magnetic resonance imaging study with flow measurements before attempted surgical complete repair were collected. Systemic blood flow (Qs) was calculated as the sum of descending aortic blood flow distal to the MAPCA origins and superior vena cava flow. Pulmonary blood flow (Qp) was measured either from the sum of the pulmonary flow (n = 7) or calculated as the difference between ascending aortic flow and Qs. Results: Preoperative Qp/Qs averaged 1.71 +/- 0.68 and correlated inversely with right ventricular systolic pressure (relative to systolic blood pressure, r= 0.75, P = .03) and positively with the total neopulmonary artery index (TNPAI, r = 0.66, P = .04), as measured by fluoroscopic angiography. Two children did not tolerate VSD closure. This was likely related to bronchial compression in 1 patient while the other had the lowest TNPAI and the lowest Qp/Qs of all patients. Conclusions: CMR provides not only anatomic but also functional information for surgical decision making in patients with ToF and PA with MAPCAs. Preoperative Qp/Qs is associated with postoperative right ventricular pressure and may be a marker of readiness for VSD closure.