Patient Population

All term (37-42 weeks gestation) newborns with pre- or post-natally diagnosed critical CHD admitted to the cardiac intensive care unit (CICU) at The Children’s Hospital of Philadelphia were screened for study inclusion and approached for participation as early as possible. Exclusion criteria included: birth weight less than 2 kg, a history of neonatal depression (e.g., 5 minute APGAR<5, cord blood pH<7.0, sepsis, or birth asphyxia), perinatal seizures, evidence of end-organ injury, pre-operative cardiac arrest, and significant pre-operative intracerebral hemorrhage such as grade 3 or 4 intraventricular hemorrhage. Infants with identified or suspected genetic syndromes were not excluded.