超声二维斑点追踪显像评价兔左心室局部心肌梗死后心肌舒缩功能

Assessment of left ventricular regional myocardial systolic function of rabbits with acute myocardial infarction by speckle tracking imaging

目的应用超声斑点追踪技术(STI)研究兔左心室局部心肌梗死后心肌收缩及舒张功能。方法健康新西兰兔随机分为正常对照组(假开胸组)和急性心肌梗死(AMI)组(结扎左冠状动脉前降支,造成左心室前壁心肌梗死),于实验后3d分别采集两组动物左心室短轴二尖瓣口、乳头肌、心尖水平动态二维灰阶图像;应用STI技术分析左心室不同水平各节段心内膜下心肌径向应变率(SrR)、周向应变率(SrC)、旋转率(RotR)及扭转角度(Rot),并同步记录左心室压力指标。结果 (1)与正常对照组比较,AMI组,左心室舒张末期压,左室射血分数(LVEF)、左心室短轴缩短率(LVFS)、左心室压力最大上升和下降速度(Ldp/dtmax)明显降低,左心室舒张末期内径(LVEDd)、左心室舒张末期压(LVEDP)明显升高,差异有统计学意义(P<0.05)。(2)AMI组与正常对照组比较,AMI组局部梗死段SrR、SrC、RotR及Rot均下降。(3)AMI组梗死节段在3个水平间的SrR、SrC及RotR差异无统计学意义,规律消失。(4)STI所测得收缩期指标与dp/dtmax具有正相关(r=5.67,P<0.05),舒张期指标与LVEDP具有负相关(r=-5.06,P<0.05)。结论左心室扭转功能与LVdp/dtmax的相关性最强,左心室下壁对前壁心肌梗死的代偿作用最明显。

Objective To assess the left ventricular regional myocardial systolic and diastolic function of rabbits with acute myocardial infarction（AMI） by 2-dimensional ultrasound speckle-tracking imaging.Methods Twenty-four healthy rabbits were randomly divided into two groups： group of sham-operated,group of AMI（induced by ligation of left anterior descending coronary artery）.3 d after AMI,two-dimensional strain images were acquired from LV short-axis view（at the levels of mitral annulus,muscle papillary and apex）,radial strain rate（SrR）,circumference strain rate（SrC）,rotation rate（RotR） and rotation（Rot） of 3 levels in short-axis views were measured by speckle-tracking imaging.The left ventricular pressure curve was recorded simultaneously.Results（1） Compared with sham-operated group,rabbits had significantly lower LVEF,LVFS,LVSP and LVdp/dtmax,higher LVEDP and LVEDdin AMI group.（2） The SrR,SrC,RotR of AMI infarct segments among the three levels had no significant difference.Law of motion disappeared.（3） SrR,SrC,RotR and Rot of left ventricular anterior regional myocardial function and global myocardial function of three levels in short-axis views were lower.（4） The systolic indicators had a positive correlation with dp/dtmax,diastolic indices had negatively correlation with LVEDP,the regional and globe Rot had the best relevant with dp/dtmax.The Rot of inferior had the best relevant with dp/dtmax in non-infarcted segment.Conclusion The Rot has the best relevant with dp/dtmax.The inferior wall was on the most significant compensation.