缺血后适应对急性心肌梗死二维结构与左心室收缩功能的影响

目的：应用超声心动图观察急诊经皮腔内冠状动脉成形术（PCI）后7 d、术后6个月心脏二维结构和左心室收缩功能的变化，评价缺血后适应对缺血心肌的影响。方法62例行PCI术的急性ST段抬高心肌梗死患者，随机分为对照组（30例）和缺血后适应组（32例）。对照组患者在再灌注后8 min内不作任何干预，缺血后适应组再灌注后1 min内以4～6 atm低压充盈球囊，阻断血流1 min，然后收缩球囊，开放血流1 min，反复4次。术后7 d、术后6个月，应用超声心动图评价心脏二维结构和左心室整体和节段收缩功能，评价参数包括左心房内径、左心室舒张末内径、左心室舒张末容积、心输出量、左心室射血分数（LVEF）、室壁运动计分指数（WMSI）。结果（1）两组患者年龄、性别、体重指数、临床特征包括“罪犯血管”、缺血时间、临床用药等均无显著差异（P＞0.05）。（2）术后7 d，后适应组与对照组左心房内径、左心室舒张末内径、左心室舒张末容积、心输出量、LVEF、WMSI各参数均无显著差异；术后6个月，后适应组LVEF显著提高[（56.35±8.44）%vs.（51.19±11.22）%，P＜0.05]，WMSI显著下降（1.20±0.09 vs.1.44±0.10，P＜0.01），左心房内径、左心室舒张末内径、左心室舒张末容积、心输出量与对照组无显著差异。（3）术后6个月与术后7 d比较，对照组术后6个月左心室舒张末内径增大[（55.64±7.42）mm vs.（51.60±6.19）mm，P＜0.05]，WMSI增加（1.44±0.10 vs.1.33±0.12，P＜0.01），LVEF下降，但无显著差异；后适应组术后6个月左心室舒张末容积增大[（118.62±20.84）ml vs.（106.21±24.40）ml，P＜0.05]，心输出量增加[（4.25±0.78）L/min vs.（3.87±0.66）L/min，P＜0.05]，WMSI下降（1.20±0.09 vs.1.28±0.10， P＜0.01），LVEF较前提高，但无显著差异。结论缺血后适应能改善再灌注术后6个月左心室整体和节段收缩功能，然而在临床的广泛应用，需要更大规模和更长期的随访研究来进一步肯定其有益作用。

Effect of ischemic postconditioning on two-dimensional structure and left ventricular contractile function after acute myocardial infarction

Objective To investigate the two-dimensional structure and left ventricular contractile function 7 days and 6 months after percutaneous coronary intervention（PCI） in patients with acute myocardial infarction to evaluate the effect of ischemic postconditioning on ischemic myocardium by echocardiography. Methods A total of 62 patients with ST-elevation myocardial infarction undergoing direct percutaneous coronary intervention were randomly assigned to ischemic postconditioned group （n=32） or control group （n=30）. In the control group, no additional intervention was performed during the first 8 min of reperfusion. In the ischemic postconditioned group, within 1 min of reflow, the angioplasty balloon was reinflated four times for 1 min using low-pressure （4-6 atm） inflations, each separated by 1 min of reflow. At 7 days and 6 months after angioplasty, two-dimensional structure and left ventricular global and regional contractile function were evaluated by echocardiography, the evaluated parameters including left atrial diameter, left ventricular end-diastolic diameter, left ventricular end-diastolic volume, cardiac output, left ventricular ejection fraction （LVEF） and wall motion score index（WMSI）. Results There were no significant intergroup differences in age, sex, body mass index or clinical characteristics, including ischaemia time, culprit artery and drug treatment （P〉0.05）. At 7 days, there were no significant differences in left atrial diameter, left ventricular end-diastolic diameter, left ventricular end-diastolic volume, cardiac output, LVEF or WMSI between the two groups. At 6 months, compared with the control group, LVEF was significantly improved in the ischemic postconditioned group （P〈0.05） and WMSI was significantly reduced in the ischemic postconditioned group （P〈0.01）. However, there were no significant differences between the two groups in the other measured parameters including left atrial diameter, left ventricular end-diastolic diameter, left ventricular end-diastolic volume and cardiac output. In the control group, left ventricular end-diastolic diameter significantly increased （P〈0.05） and WMSI significantly decreased （P〈0.01） at 6 months than at 7 days. However, there was no significant difference in the decreased LVEF at different time. In the ischemic postconditioned group, left ventricular end-diastolic volume （P〈0.05） and cardiac output （P〈0.05） significantly increased, WMSI significantly decreased （P〈0.01） at 6 months than at 7 days. However, there was no significant difference in the increased LVEF at different time. Conclusions Ischemic postconditioning is associated with improved left ventricular global and regional contractile function contractile function detectable 6 months after reperfusion following acute myocardial infarction. However, further studies with larger sample sizes and longer term follow-up are necessary to more fully investigate and understand the protective benefits of ischaemic postconditioning before widespread use of this technique in patients with acute myocardial infarction.