缺血后处理对体外循环心脏瓣膜置换患者心电图的影响

Effects of ischemic postconditioning on reperfusion arrhythmia in patients undergoing heart valve replacement surgery

目的评价缺血后处理对体外循环(CPB)下心脏瓣膜置换术患者心电图的影响。方法择期行CPB下心脏瓣膜置换术患者40例,性别不限,年龄21~59岁,心功能分级Ⅱ或Ⅲ级,ASA分级Ⅱ或Ⅲ级,左室射血分数≥40%。采用随机数字表法,将患者分为2组(n=20):对照组(C组)和缺血后处理组(P组)。P组于升主动脉完全开放前5min时,先松开主动脉钳夹30s,再夹闭30s,连续3个循环,然后完全松开主动脉钳夹。分别于麻醉诱导后手术前(T1)、心脏复跳时(T2)和升主动脉开放10min(T3)、30min(T4)、45min(T5)以及术终(T6)和术后12h(T7)、24h(T8)记录患者心电图的变化。于升主动脉开放后45min时取右心耳心肌组织,Western blot和TUNEL法检测Akt、磷酸化Akt(p-Akt)及细胞色素C(Cyto-C)、Caspase-9、Bcl-2、Bax的蛋白表达和细胞凋亡情况,并计算Bcl-2与Bax表达的比值(Bcl-2/Bax)和凋亡指数(AI)。结果 C组T2~T8等时点再灌注心律失常如室性期前收缩(室早)、室性心动过速(室速)、心室纤颤(室颤)的发生率分别为30%、55%、40%,P组为15%、30%、20%,有显著减少(P<0.05);C组T2~T8再灌注心律失常评分(3.72±1.09)及∑ST-T抬高或下移幅度(3.8±1.23、3.4±1.17、3.1±1.12、2.7±0.97、2.3±0.92、2.1±0.86、1.8±0.79),P组分别为(2.3±0.86)和(2.1±0.91、1.9±0.85、1.8±0.67、1.6±0.59、1.2±0.49、1.0±0.43、0.9±0.41),均显著减少(P<0.05)。P组心肌组织Bax、Cyto-C、Caspase-9表达低于C组(5.8±2.2 vs.8.6±3.1、0.23±0.03 vs.0.31±0.09、0.35±0.06 vs.0.43±0.10),AI降低(8.1±2.1 vs.11.2±3.2),而Bcl-2/Bax比率(1.2±0.5 vs.0.7±0.3)和p-Akt(0.36±0.10 vs.0.27±0.04)、Bcl-2(6.2±3.4 vs.3.1±1.2)表达均上调(P<0.05)。结论缺血后处理可减轻CPB下心脏瓣膜置换术患者再灌注心律失常,产生心肌保护作用,其机制与抑制线粒体凋亡有关。

Objective To evaluate the effects of postconditioning on ECG in patients undergoing heart valve replacement patients under CPB.Methods Forty NYHAⅡorⅢ,ASAⅡorⅢpatients of both sexes,aged 21-59 years,scheduled for cardiac valve replacement,were divided into two groups(n=20 in each):control group(C group)and postconditioning(I-postC)group(P group).In P group,the procedure involved 5 min before opening the ascending aorta,aortic unclamping for 30 s,and cross-clamping for 30 s for three cycles,after which the ascending aorta was completely opened.C group was not treated.The changes of ECG in C and P groups were recorded at the time points of after anesthesia(T 1),heart rebeating(T 2),10 min after aortic declamping(T 3),30 min after aortic declamping(T 4),45 min after aortic declamping(T 5),end of ration(T 6),12 hours after operation(T 7),and 24 hours after operation(T 8).Myocardial tissues were obtained from right atrial appendage at T 5 to determine the expressions of Akt,p-Akt,Bcl-2,Bax,cytochrome C and caspase-9 and apoptosis by Western blot analysis and TUNEL assay.Bcl-2/Bax ratio and apoptosis index were calculated.Results The incidence rates of reperfusion arrhythmias(ventricular premature beat,ventricular tachycardia and ventricular fibrillation)at T 2 to T 8 in P group(15%,30%,20%)were lower than those in C group(30%,55%,40%).The scores for reperfusion arrhythmia and change of∑ST segments in ECG(elevation or depression)in P group(2.3±0.86;2.1±0.91,1.9±0.85,1.8±0.67,1.6±0.59,1.2±0.49,1.0±0.43,0.9±0.41)were lower than those in C group(3.72±1.09;3.8±1.23,3.4±1.17,3.1±1.12,2.7±0.97,2.3±0.92,2.1±0.86,1.8±0.79)at T 2 to T 8.The expressions of Bax,cytochrome C and Caspase-9 and apoptosis index were lower in P group(5.8±2.2,0.23±0.03,0.35±0.06,8.1±2.1)than in group C(8.6±3.1,0.31±0.09,0.43±0.1,11.2±3.2).The expressions of p-Akt and Bcl-2 and Bcl-2/Bax ratio were higher in P group(0.36±0.10,6.2±3.4;1.2±0.5)than in C group(0.27±0.04,3.1±1.2;0.7±0.3)(P<0.05).Conclusion Postconditioning can reduce reperfusion arrhythmias in patients undergoing cardiac valve replacement and produce myocardial protective effects.The mechanism is related to the inhibition of mitochondrial apoptosis.