Modified Perfusion for Neonatal Aortic Arch Reconstruction

Overview

Even though the lower part of the body does receive some blood supply during Cardiopulmonary Bypass(CPB) surgery, it may not be enough. As a result of this lowered blood supply, there are complications associated with CPB and clamping of the aorta. These include complications with the stomach, intestines and kidneys. The hypotheses of this study are that increased lower body perfusion during aortic arch reconstruction will decrease intestinal ischemia and the incidence of necrotizing enterocolitis, improve renal function in the postoperative period, and shorten both intensive care unit and hospital length of stay. The purpose of this research study is to provide the lower part of the body and its organs with possibly more blood supply with a modified form of cardiopulmonary bypass and see if this additional blood supply helps to decrease complications of the kidney, stomach and intestines.

As the aorta is repaired, the child has no circulation to the body or brain. While short periods of circulatory arrest were well tolerated, a modified technique called selective cerebral perfusion was developed to maintain blood flow to the brain during aortic repairs so as to allow for less hurried repairs with less concern over brain ischemia and injury. Selective cerebral perfusion is designed to provide flow to the brain via the right carotid artery and collateral intracranial vessels while the aortic arch is isolated for repair. It is felt that collateral vessels also allow some perfusion of the lower body, but the adequacy of lower body perfusion during selective cerebral perfusion has not been well documented. While it is clear that some blood reaches the lower body, the incidence of renal and gastrointestinal complications following cardiac repairs involving aortic arch reconstructions remains significant. 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.