The mechanism of Blood-brain barrier disturbance after cardiopulmonary bypass in cardiovascular surgery

在体外循环（CPB）后立即发现磁共振图像上明显的脑肿胀，可能是心血管手术后神经心理障碍的原因。在尸检患者中，由于体外循环引起的微栓塞可以在大脑中检测到脂质沉积，形成小毛细血管和小动脉扩张（SCADs）。这种脂质栓子可能来自于开心术吸血，成为脑肿胀的原因。但这种相互作用还没有被探索过。本研究旨在探讨兔模型开心术抽吸血回流血脑屏障的作用，以及血清S100b蛋白和神经元特异性烯醇化酶（NSE）浓度是否可作为心血管手术临床病例脑损伤的预测指标。动物研究。切开家兔胸骨，经左心室置输注管至升主动脉（肝素化后）。在右眼经颅多普勒监测下，纵膈腔增腔90 min后，将75 ml吸血回管内（n=6）。对照组（n=6）只插管。血脑屏障损伤（右脑）采用外渗埃文斯蓝测定。左侧脑在110℃下干燥24h，计算含水量。右脑的其余部分用作组织病理学评估。开心术回吸血时，TCD监测发现多发栓子，evans蓝明显外渗。水分含量不大于对照组。各组间MAP2染色差异有统计学意义，GFAP染色差异有统计学意义（增高）。人类的研究。测定18例常规CPB患者和7例选择性脑灌注（SCP）患者术中及术后7个时间点血中S100b和NSE含量。在手术野和细胞保存装置的血液中也检测了这些标记物的浓度。CPB组S100b均值（2.08±2.00 ng ml^<-1>）和SCP组S100b均值（1.46±0.77 ng ml^<-1>）分别在主动脉瓣脱落和SCP终止后最大。CPB组NSE均值（29.1±14.0 ng ml^<-1>）和SCP组NSE均值（31.2±13.6 ng ml^<-1>）分别在CPB终止后和手术结束时最大。3例患者出现脑并发症，但术中这些标志物的升高与其他患者没有区别。术野血中S100b蛋白和NSE浓度明显高于动脉血，而保存细胞装置内血液中S100b蛋白和NSE浓度未升高。返开心术将血液吸入升主动脉成为S100b蛋白和NSE污染及血脑屏障损伤的原因。少

Marked cerebral swelling visible on magnetic resonance images has been found immediately after cardiopulmonary bypass (CPB) and may be the cause of neuropsychological disorders after cardiovascular surgery. In autopsy patients, microembolization due to cardiopulmonary bypass can be detected in the brain as lipid deposits that create small capillary and arteriolar dilations (SCADs). This lipid emboli possibly come from cardiotomy suction blood and become the cause of cerebral swelling. But this interaction has not been explored. The purposes of this study are to examine the effect of returning the cardiotomy suction blood to the blood-brain barrier in rabbit model and whether serum concentrations of S100b protein and neuron specific enolase (NSE) are predictors of cerebral damage in clinical cases of cardiovascular surgery.Animal study. Sternotomy of the rabbit was done and infusion line was cannulated into the ascending aorta via left ventricle (after heparinization). The mediastinal c … More avity was manipulated for 90 min and 75 ml suction blood was returned into the cannula under transcranial Doppler monitor on right eye (n=6). Only cannulation was done in the control rabbits (n=6). The blood-brain barrier impairment (of the right side the brain) was evaluated with the measurement of extravasated evans blue. The left side brain was dried at 110℃ for 24hr and water content was calculated. The rest of the right side of the brain was used as histopathologic evaluation. During returning the cardiotomy suction blood, multiple emboli was detected on TCD monitor and the extravasation of evans blue occur significantly in this animal. The water content was not larger than control group. There was significant difference not in MAP2 staining but in GFAP staining (increase) between groups.Human study. S100b and NSE were measured in the blood obtained at 7 time points during and after operation in eighteen patients with conventional CPB and seven with selective cerebral perfusion (SCP). Concentrations of these markers were also examined in the blood of surgical field and cell saving device. The mean values of S100b in CPB group (2.08 ± 2.00 ng ml^<-1>) and SCP group (1.46 ± 0.77 ng ml^<-1>) were largest after aortic declamp and after termination of SCP, respectively. The mean values of NSE in CPB group (29.1±14.0 ng ml^<-1>) and SCP group (31.2 ±13.6 ng ml^<-1>) were largest after termination of CPB and at the end of operation, respectively. Three patients suffered from cerebral complications but the elevation of these markers during operation was indistinguishable from those in the other patients. S100b protein and NSE concentrations in the blood of surgical field were significantly larger than those in arterial blood, while these concentrations of the blood in cell saving device were not elevated.The maneuver of returning the cardiotomy suction blood into ascending aorta become the cause of contamination of S100b protein and NSE and impairment of blood-brain barrier. Less