Interstage management of pulmonary blood flow after the Norwood procedure with right ventricle-to-pulmonary artery conduit

OBJECTIVES Our goal was to assess the efficacy of managing pulmonary blood flow from the Norwood procedure with a right ventricle-to-pulmonary artery (RV–PA) conduit until stage 2 palliation (S2P). METHODS Among 48 consecutive patients undergoing the Norwood procedure between 2008 and 2018, 40 (83.3%) patients who survived to discharge were included in this study. The primary diagnosis was hypoplastic left heart syndrome in 28 (70%) patients and hypoplastic left heart syndrome variant in 12 (30%) patients. All patients received bilateral pulmonary artery banding. The median age and weight at the time of the Norwood procedure were 41 (25th–75th percentiles: 27–89) days and 3.2 (2.7–3.9) kg, respectively. In keeping with institutional strategy, S2P was undertaken when body weight exceeded 5.0 kg, and normal gross motor development was confirmed. RESULTS The RV–PA conduit was clipped in 28 (70%) patients during the perioperative period of the Norwood procedure, then partial unclipping was performed in 8 (20%) patients and full unclipping was performed in 20 (50%) patients. Before S2P, the median pulmonary-to-systemic blood flow ratio was 1.0 (0.7–1.3). The median age and weight at the time of S2P were 10.7 (9.0–12.9) months and 6.3 (5.5–7.1) kg, respectively. The survival rate 5 years after Norwood discharge was 85.3%. Pre-S2P pulmonary-to-systemic blood flow ratio was linearly correlated with greater interstage changes in systemic atrioventricular valve regurgitation (R2 = 0.223, P = 0.004). CONCLUSIONS Interstage management of pulmonary blood flow by RV–PA conduit clipping and gradual unclipping provided good interstage outcomes. The median pulmonary-to-systemic blood flow ratio could be controlled to 1.0 at pre-S2P catheter examination.