Histological Changes in Neonatal Kidneys after Cardiopulmonary Bypass and Deep Hypothermic Circulatory Arrest

Background: Renal failure after open-heart surgery is a serious complication resulting in increased mortality and morbidity. The aim of the study was to find out whether different strategies for open-heart surgery would result in renal histological differences in a neonatal animal model. Methods: The renal tissue of newborn piglets was examined after mild hypothermic cardiopulmonary bypass (CPB group; n = 10), deep hypothermic circulatory arrest (DHCA group; n = 8), instrumentation without extracorporeal circulation (sham; n = 3), and the data were compared with those of normal porcine neonatal kidneys (control: n=6). The severity of tissue damage was graded using a 4-point scoring system (0: normal morphology, 3: severe damage). Apoptotic cells and granulocytes were counted. Results: The histological score was higher in all groups compared with controls (p<0.05) and higher in the CPB group compared with the DHCA group (p<0.05). More apoptotic cells and granulocytes were found in the CPB group compared with controls and the DHCA group (p<0.05). Conclusions: Although changes in the kidney tissue of newborn piglets are detectable after any cardiac procedure, changes are more profound after cardiopulmonary bypass with mild hypothermia.