Histologic changes in kidneys of newborn piglets after cardiopulmonary bypass and deep hypothermic circulatory arrest

Introduction: Renal failure after open-heart surgery is a serious complication increasing postoperative mortality and morbidity. The reason may be pre-renal, renal, and post-renal. The aim of the study was to find out if diffent strategies for open-heart surgery result in renal histologic differences in a neonatal animal model.

Methods: Kidneys of newborn piglets were histologic examinated after application of mild hypothermic cardiopulmonary bypass (CPB group; n=10), deep hypothermic circulatory arrest (DHCA group; n=8), and after instrumentation without extracorporeal circulation (sham; n=3). The findings were compared with normal neonatal kidneys (control; n=6). Severity of tissue damage was scored by a 4-grade system (0: normal morphology, 3: severe damage) regarding tubular dilation, vacuoles, leucocyte infiltration, epithelial destruction, and interstitial edema. Additionally, apoptototic cells and granulocytes were counted.

Results: Histologic score was higher in all groups compared with control (p<0.05) and higher in CPB group compared with DHCA group (7.6±2.2 vs. 5.1±2.0; p<0.05). More apoptotic cells were found in CPB group compared with control (7.9±6.5 vs. 0.8±1.2, p<0.05) and DHCA group (7.9±6.5 vs. 1.9±0.8, p<0.05). Also the granulocytes counts were higher in CPB group compared with control (30.6±20.4 vs. 6.7±3.3, p<0.05) and DHCA group (30.6±20.4 vs. 13.25±7.8, p<0.05).

Conclusions: Our study revealed that although changes in the kidney tissue of newborn piglets are detected after any cardiac procedure this changes are more profound after application of mild hypothermic cardiopulmonary bypass.