体外循环不阻断升主动脉低温心室颤动左心室引流技术对心肌保护作用的实验研究

Experimental study of myocardial preservation with hypothermic ventricular fibrillation and left ventricular drainage during cardiopulmonary bypass without aortic cross-clamping

目的检测内皮素、NO、丙二醛和超氧化物歧化酶（SOD）血液学指标及心肌组织局部内皮素受体A（ETA）mRNA的表达，评价体外循环不阻断升主动脉低温心室颤动左心室引流技术对心肌的保护作用，探讨更好的心肌保护方式。方法建立体外循环动物模型，实验动物分为对照组（停跳组）及实验组（心室颤动组），体外循环前、体外循环1h、体外循环2h、体外循环结束后1h4个时间点分别抽取静脉血，同时于各时间点分别钻取左心室壁局部心肌组织100mg。测定血浆内皮素、NO、丙二醛和SOD水平。用逆转录聚合酶链反应方法检测心肌ETA mRNA的表达。结果随体外循环时间延长，2组内皮素、丙二醛水平均有升高。于体外循环2h和体外循环结束后1h两个时间点，对照组内皮素、丙二醛水平明显高于实验组[（70．27±7．03）ng／L比（56．53±12．11）ng／L，（106．36±6．61）ng／L比（72．71±12．72）ng／L；（4．71±1．31）μmol／L比（3．32±0．82）μmol／L，（8．27±1．99）μmol／L比（4．38±1．02）μmol／L，均P〈0．01]；2组NO、SOD平均呈下降趋势，但实验组下降和缓，在后两个时间点，对照组NO、SOD水平明显低于实验组[（28．57±9．20）μmol／L比（45．36±16．59）μmol／L，（12．14±7．03）μmol／L比47．50±17．18）μmol／L；（7．23±2．59）μg/L比（17．69±7．96）μg／L，（2．78±0．88）μg／L比（18．52±10．30）μg／L，P〈0．05或P〈0．01]；2组ETA mRNA的表达水平均有升高，对照组升高幅度比实验组要高，体外循环1h、2h和体外循环结束后1h差异明显[（0．35±0．01）比（0．28±0．05），（0．49±0．05）比（0．31±0．04），（0．67±0．05）比（0．38±0．07），P〈0．01]。结论体外循环不阻断升主动脉低温心室颤动左心室引流技术对心肌具有良好保护作用。

Objective To evaluate the protective effect of hypothermic ventricular fibrillation by analyzing the index endothelin, nitric oxide, malondiadehyde, superoxide dismutase （SOD） in blood and the expression of endothelin receptor A （ETA） mRNA in myocardium. Methods The animal model cardiopulmonary bypass （CPB） was estibalsed. Before CPB, at 1,2 hours of CPB and 1 hour after heart re-beating, blood from vein was withdrew and myocardium was taken from the left ventricle of each dog. The blood level of nitric oxide （ NO）, malondialdehyde （MDA）, endothelin and SOD were tested, as well as the expression of the local left ventricular ETA mRNA u- sing reverse transcriptase-polymerase chain reaction. Results The levels of endothelin, malondiadehyde in both groups were higher than normal. At 1, 2 hours of operation and 1 hour after heart beating, the endothelin, malondiadehyde level of control group were higher than those of experimental group [ （70.27 ± 7.03 ） ng/L vs （ 56.53 ± 12.11 ） ng/L, （ 106.36 ± 6.61 ）ng/L vs （72.71 ± 12.72） ng/L; （4.71 ± 1.31 ） μ mol/L vs （3.32 ± 0.82 ） μmoL/L, （ 8.27 ± 1.99 ）μmol/L vs （4.38 ± 1.02 ） μmol/L, P 〈 0.01 ]. The NO, SOD levels in both groups reduced but more significantly in control group. At 2 hours of operation and 1 hour after heart beating, the NO and SOD levels of experimental group were higher than those of control group [ （28.57 ±9.20） μmol/L vs （45.36 ± 16.59）μmoL/L, （ 12.14 ± 7.03 ） μmol/L vs （47.50 ± 17.18 ） μmol/L ; （ 7.23 ± 2.59 ） μg/L vs （ 17.69 ± 7.96 ） μg/L, （ 2.78 ± 0.88）μg/L vs （18.52 ± 10.30）μg/L,P 〈0.05 or P 〈0.01]. ETA mRNA showed an increase in both two groups. Compared to experimental group, the ETA mRNA level in control group at 1, 2 hours of operation and 1 hour after heart beating was significantly higher [ （ 0.35 ± 0.01 ） vs （ 0.28 ± 0.05 ）, （ 0.49 ± 0.05 ） vs （ 0.31 ± 0.04） ,（0.67 ±0.05）vs（0.38 ±0.07）,P〈0.01]. Conclusion Myocardium is protected effectively by hypothermic ventrieular fibrillation technique.