Background Survivors of the Norwood procedure may suffer neurodevelopmental impairment. Clinical trials to improve outcomes have focused primarily on methods of vital organ support during cardiopulmonary bypass. Methods In the Single Ventricle Reconstruction trial of the Norwood procedure with modified Blalock-Taussig shunt vs. right-ventricle-to-pulmonary-artery shunt, 14-month neurodevelopmental outcome was assessed using the Psychomotor Development Index (PDI) and Mental Development Index (MDI) of the Bayley Scales of Infant Development®-II. We used multivariable regression to identify risk factors for adverse outcome. Results Among 373 transplant-free survivors, 321 (86%) returned at age 14.3±1.1 (mean±SD) months. Mean PDI (74±19) and MDI (89±18) scores were lower than normative means (each P<.001). Neither PDI or MDI score was associated with type of Norwood shunt. Independent predictors of lower PDI score (R2= 26%) were clinical center (P=.003), birth weight<2.5 kg (P=.023), longer Norwood hospitalization (P<.001), and more complications between Norwood procedure discharge and age 12 months (P<.001). Independent risk factors for lower MDI score (R2= 34%) included center (P<.001), birth weight<2.5 kg (P=.04), genetic syndrome/anomalies (P=.04), lower maternal education (P=.04), longer mechanical ventilation after the Norwood procedure (P<.001), and more complications after Norwood discharge to age 12 months (P<.001). We found no significant relationship of PDI or MDI score to, perfusion type, other aspects of vital organ support (e.g. hematocrit, pH strategy), or cardiac anatomy. Conclusion Neurodevelopmental impairment in Norwood survivors is more highly associated with innate patient factors and overall morbidity in the first year than with intraoperative management strategies. Improved outcomes are likely to require interventions that occur outside the operating room.

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