门控心肌单光子计算机断层显像评价缺血性心肌顿抑

Evaluation of Post-Ischemic Myocardial Stunning by Gated ^(99)Tc^m-MIBI SPECT Perfusion Imaging

目的:用门控心肌单光子计算机断层(SPECT)显像评价运动试验后缺血性心肌顿抑。方法:对108例临床疑诊冠心病的患者及30例冠心病低度可能的患者行运动试验后早期(5～15 min)、延迟(约1.5 h)及隔日静息门控99m锝—甲氧基异丁基异腈(MIBI)心肌SPECT显像,用QGS软件处理得到左心室射血分数、舒张末期容积、收缩末期容积,并对心肌灌注进行17节段5分法评分。根据心肌灌注显像将108例患者分为心肌缺血组(70例)和心肌显像正常组(38例),比较心肌缺血组、心肌显像正常组及冠心病低度可能组运动试验后早期、延迟及静息左心室射血分数、舒张末期容积、收缩末期容积的变化。结果:心肌缺血组患者运动试验后早期及延迟显像时左心室射血分数明显低于静息射血分数,差值分别为-4.1%、-3.6%,差异均有统计学意义(P均<0.05)。心肌缺血组运动试验后收缩末期容积较静息时增加,早期与静息收缩末期容积比值为1.28±0.43,延迟与静息收缩末期容积比值为1.25±0.31。三组患者舒张末期容积差异无统计意义(P均>0.05)。左心室射血分数下降及收缩末期容积扩张有很好的相关性,多因素回归分析显示SDS是左心室射血分数下降及收缩末期容积扩张的独立预测因子。心肌显像正常组及冠心病低度可能组无此变化。结论:在运动试验门控心肌SPECT显像中,心肌缺血患者常会出现心肌顿抑,表现为左心室功能的延迟恢复,即运动试验后左心室射血分数降低、收缩末期容积扩张。并且,心肌顿抑的发生与心肌缺血的严重程度密切相关,心肌缺血的数量是运动试验后左心室功能改变的独立预测因子。

Objective：To evaluate exercise-induced post-ischemic myocardial stunning by gated 99Tcm-MIBI SPECT perfusion imaging. Methods：A total of 108 patients with suspected coronary artery disease（CAD） and 30 patients with low likelihood CAD were examined by gated 99Tcm-MIBI SPECT perfusion imaging.Three data acquisitions were performed as early stage（5~15 min after exercise）,delayed stage（about 1.5 h after exercise） and resting stage（next day of exercise）.Left ventricular ejection fraction（EF） and volumes were calculated by QGS software,and the segmental perfusion was analyzed using a 5-point scale.According to myocardial perfusion imaging,108 suspected CAD patients were divided into Myocardial ischemia group,n=70 and Normal perfusion group,n=38,together with Low likelihood CAD group,we compared left ventricular EF,the end-diastolic volume（EDV） and end-systolic volume（ESV）at three stages in three groups. Results：In Myocardial ischemia group,post-exercise left ventricular EF at early stage and delayed stage were lower than that in resting stage,while the post-exercise ESV was higher than that in resting stage.The stress/rest ratios were 1.28±0.43 at early stage,and 1.25±0.31 at delayed stage.No significant differences in EDV at three stages among three groups.There was good correlation between decreased left ventricular EF and ESV dilation.Multivariate regression analysis indicated that summel defect score was the only independent predictor for left ventricular EF decreasing and ESV dilation.The same phenomenon was not found in Normal perfusion group and Low likelihood CAD group. Conclusion：The myocardial stunning is frequently found in ischemia patients by post-ischemic gated SPECT perfusion imaging as left ventricular EF decreasing and ESV dilation.The severity of myocardial stunning depends on the extent of ischemia.