- Controls: 40 neonates with complex congenital heart disease undergoing cardiac surgery with CPB who received two doses of preoperative methylprednisolone (10mg/kg at eight hours and one hour prior to their operation). Data from this cohort has already been prospectively collected during the original pilot randomized control trial. Based on our clinical data over the past 8 years, the demographic and risk factors of the two cohorts will be very similar.