Antithrombin III Supplementation for Cardiopulmonary Bypass in Neonates

Single dose of antithrombin (recombinant) to be given prior to initiation of cardiopulmonary bypass. Intravenous dose determined by following formula: ATIII dose given to patient = \[(1.0 Units/mL - patient's measured ATIII concentration in Units/mL) X weight (kg) X 80 mL/kg\] X (1 mL/175 Units)

Single dose of placebo (0.9% NaCl) to be given prior to initiation of cardiopulmonary bypass. Intravenous dose determined by following formula: Placebo dose given to patient = \[(1.0 Units/mL - patient's measured ATIII concentration in Units/mL) X weight (kg) X 80 mL/kg\] X (1 mL/175 Units)