The second aim of this study will test the hypothesis that hemodilution to a HCT level of 35%, compared to a level of 25%, will be associated with better early postoperative cardiovascular status. The primary outcome measure will be serum lactate levels 1 hour after the surgery. Secondary outcome measures will include the following: 1) the duration of postoperative endotracheal intubation, ICU stay, and hospital stay; 2) serum lactate levels; 3) the PaO2/FiO2 ratio; 4) levels of circulating pro-inflammatory cytokines; and 5) the percent change in total body water, estimated by bioelectrical impedance. The structure of the study will allow assessment of whether 1-year outcomes can be predicted by perioperative variables other than the HCT strategies. Through the use of novel techniques such as NIRS and volumetric MRI, the study may also provide insight into mechanisms by which HCT and other perioperative variables affect the brain. The information obtained from this study should be broadly generalized to infants with other forms of congenital heart disease undergoing early repair and should have substantial impact on clinical practice.