The study will be prospective. Patients who meet entry criteria will be randomized to receive corticosteroids versus placebo. Randomization will take into account biventricular versus univentricular repairs/palliations and whether the patients received intraoperative steroids. Patients will be compared with matched controls based on: diagnosis, +/- intraoperative steroids/phenoxybenzamine, cardiopulmonary bypass/cross clamp/circulatory arrest times and inotrope requirements. Those in the treatment arm will be dosed with hydrocortisone - stress dose (100mg/m2/dose daily x2, then taper with two days at half the original dose and one day at one quarter of the original dose) and then the steroids will be discontinued. Outcome data will include: heart rate, blood pressure, mixed venous oxygen saturation to assess cardiac output, blood cultures/infection/antibiotics (antibiotics as deemed necessary by the primary cardiologist), +/- gastrointestinal bleeding, time to discontinuing inotropic agents, time to extubation, length of intensive care unit admission and survival. Laboratory studies will be assessed before and 24 hours after the institution of steroids. The following labs are standard of care in the unit and will be assessed: glucose, electrolytes, blood urea nitrogen/creatinine, complete blood counts, lactate, arterial blood gases, cultures and stool guaiac. The following labs will be assessed in addition to regular monitoring: cortisol, adrenocorticotropin hormone and C reactive protein.