This study evaluates the effect of heart-lung bypass on babies undergoing cardiac surgery. The investigators want to learn more about the inflammation that exposure to bypass creates in the body by studying markers of inflammation and cell injury in the bloodstream. Additionally, the investigators want to examine if these markers can predict which babies develop post-surgical complications. The hypothesis is that babies who undergo bypass will have higher levels of these markers than babies not exposed to bypass and that these markers will correlate with how the baby does clinically after surgery.