Antithrombin Enhancement May Improve Anticoagulation Efficiency in Infants Undergoing Cardiopulmonary Bypass for Cardiac Surgery

The primary objective of this study is: 1\. To evaluate the use of Antithrombin (AT) concentrate in infants less than one year of age undergoing cardiopulmonary bypass (CPB) for cardiac surgery The secondary objectives of this study are: 1. To determine if the administration of AT concentrate prior to heparinization will decrease the amount of heparin required to achieve optimal anticoagulation (as defined by anti-Xa levels) during CPB 2. To determine if a decrease in activation and consumption of coagulation proteins, platelets and subsequent fibrinolysis will result in improved haemostasis following CPB 3. To determine if there will be a reduction in postoperative bleeding and associated clinical complications