心室短轴斑点追踪成像评价心肌梗死

Analysis of infarcted myocardial deformation based on speckle tracking imaging in two dimensional echocardiographic images

目的 采用超声心动图斑点追踪成像（STI）技术对心肌梗死心室短轴节段不同形式的运动进行评价。方法 分离结扎32只新西兰白兔冠状动脉前降支第一对角支造成前间隔及前壁心尖段心肌梗死，于梗死前正常状态及梗死后2周分别行超声心动图检查，应用STI技术分析左室短轴基底段及心尖段心室节段径向应变（RS）、圆周方向应变（CS）以及局部心肌旋转（Rot）。根据心肌梗死后左室射血分数（EF）下降的程度，将实验动物分为EF显著下降组及EF轻微下降组，分析RS、CS及Rot变化。结果心肌梗死后梗死段RS、CS以及Rot均下降；EF轻微下降组梗死段RS及Rot较正常时减低。结论STI能够评价左室短轴各个方向运动，心肌梗死后梗死段短轴各方向应变减低；整体EF无明显变化时，STI部分指标仍能敏感地检测出局部心肌收缩功能的变化。

Objective To assess the strain changes of infarcted myocardium by left ventricle（LV） short axis speckle tracking imaging（STI） in different directions. Methods The first diagonal branch of left anterior descending was ligated to induce acute myocardium infarction（AMI） in 32 New Zealand rabbits. Echocardiography was done at baseline （before AMI） and 2 weeks after AMI. Radial strain （RS）, circumferential strain（CS） and rotation degree（Rot） of regional myocardium were measured with STI on LV short axis mitral valve and apex views for each animal. All animals were divided into 2 groups according to the ejection fraction（EF） reduction after AMI： slight EF reduction group （〈 10%） and significant EF reduction group （〉 10%）. Results Compared with baseline, RS, CS and Rot of infarcted segments significantly decreased after AMI in all animals, and significantly different from non-infarcted normokinetic segments. Even in slight EF reduction group,RS and Rot depression could also be observed. Conclusions STI enables accurate analysis of regional systolic function by frame-by-frame tracking high intensity dots in two-dimensional echocardiographic images. Radial strain and rotation strain can sensitively detect the regional contraction changes.