The goal of this proposal is to evaluate a simple modification of the standard selective cerebral perfusion protocol designed to increase perfusion to the lower body during aortic arch reconstructions. Essentially all children who undergo aortic arch reconstruction at Egleston hospital have either a femoral or umbilical artery catheter in place for routine monitoring. During selective cerebral perfusion, the descending thoracic aorta is clamped, so the lower body arterial line is not a useful monitor at that point. We propose to connect a pressure line from the cardiopulmonary bypass circuit to the lower body arterial catheter, allowing for increased perfusion of the lower body through the femoral/umbilical arterial catheter during selective cerebral perfusion We will monitor simultaneous near infra-red spectroscopy of the brain, flank, and thigh to determine the adequacy of oxygen delivery to the brain, kidney, and lower body musculature during the procedure. Near infra-red spectroscopy provides a measure of the oxygenation of hemoglobin in arterial, capillary, and venous blood within the path of an infra-red sensor. Blood samples will be collected before skin incision, at the end of the procedure, and at 3, 12, and 24 hours after arrival to the intensive care unit. Intestinal fatty acid binding protein (i-FABP) and c-reactive protein (CRP) serum levels will be measured at each timepoint as markers of intestinal ischemia and generalized inflammation respectively. The incidence of documented or suspected necrotizing enterocolitis prior to hospital discharge and the time required to achieve full enteral feeds will be recorded. Renal function will be assayed by the maximal change from preoperative to postoperative serum creatinine, normalized urine output per 12 hour period following surgery, total diuretic dose per day, and daily creatinine clearance for the first 3 days after surgery.