Late left pulmonary artery stenosis after the Norwood procedure is prevented by a modification in shunt construction

Background. Late left pulmonary artery (LPA) stenosis occurs commonly after the Norwood procedure, and complicates subsequent stages. Compression by the neoaorta and ductal stump may favor flow into the right pulmonary artery, resulting in LPA hypoplasia. We hypothesize that an early compromise of LPA flow contributes to late LPA stenosis, and have modified our shunt to compensate. Methods. We reviewed 34 consecutive neonates undergoing the Norwood procedure between 1999 and 2002, and morphometric data from angiograms obtained before the bidirectional cavopulmonary anastomosis (BD-CPA). The Norwood technique included an autologous arch reconstruction with or without augmentation, and a polytetrafluoroethylene Blalock-Taussig shunt (BTS). Starting February 2001, the distal shunt was modified from an end-to-side construction to an oblique anastomosis directed into the retroaortic LPA. Results. Norwood survival was 82%. LPA stenosis required plasty in 10 of 13 (77%) premodification survivors, and in 2 of 9 (22%) postmodification (p = 0.027). Bypass time was 151 ± 65 minutes with LPA plasty versus 95 ± 50 minutes without. Mortality (15% vs 0%), hospital stay (25 ± 35 vs 9 ± 6 days), and incidence of subsequent interventions were correspondingly higher with LPA stenosis. Ten of 13 patients (77%) with a BTS insertion point outside the central region of the pulmonary artery required LPA plasty, versus 2 of 9 (22%) with an insertion nearer to the center (p = 0.027). Conclusions. An oblique distal BTS anastomosis directed leftward onto the retroaortic pulmonary artery at the time of the Norwood procedure may prevent late LPA stenosis and its attendant morbidity. © 2005 by The Society of Thoracic Surgeons.