Early Experience With Percutaneous Pulmonary Blood Flow Restrictors to Allow Deferral of Norwood Surgery

<b>Background:</b> Deferral of the Stage 1 Norwood Palliation (S1P) for infants with hypoplastic left heart syndrome and high-risk features is sometimes accomplished using a hybrid approach involving external pulmonary artery (PA) banding. Recently, percutaneous restriction of pulmonary blood flow has been accomplished with off-label modification of microvascular plugs to delay surgery. <b>Methods:</b> This single-center, retrospective case series examines outcomes associated with PA flow restrictors (PAFR) in S1P candidates. Primary outcomes included death, extracorporeal membrane oxygenation, PA reintervention, and variation from expected pathway post bidirectional Glenn (BDG), which includes prolonged intubation (>24 h), persistent hypoxia (saturation <75%), or prolonged hospital length of stay (>14 days). <b>Results:</b> From December 2022 to March 2025, bilateral PAFRs were placed in 12 S1P-eligible neonates. Three patients died with flow restrictors before S1P. One patient developed progressive heart failure and underwent a heart transplant. The remaining eight patients underwent S1P with removal of flow restrictors and pulmonary arterioplasty at a median of 21 days postinsertion. Three patients required PA stents between S1P and BDG. Six patients have progressed to BDG, all with courses that significantly varied from the expected pathway, including three with early PA stenting and one patient who died due to sequelae of failed BDG circulation. <b>Conclusion:</b> Flow restrictors are an adjunct to the management of high-risk patients prior to S1P, allowing for evaluation of additional comorbidities. However, their use appears to be associated with an important rate of PA complications, resulting in significant variation from the expected clinical course and may impact quality of BDG circulation.