Fu Qian, Xie Mingxing, Wang Jing, Wang Xinfang, Lv Qing, Lu Xiaofang, Fang Lingyun, Chang Long
Department of Medical Ultrasound, Huazhong University of Science and Technology, Wuhan 430022, China.
J Huazhong Univ Sci Technolog Med Sci. 2009 Dec;29(6):786-90. doi: 10.1007/s11596-009-0623-1. Epub 2009 Dec 29.
This study evaluated the change in regional left ventricular myocardial function in rats following acute occlusion of the left anterior descending coronary artery (LAD) by using two-dimensional speckle tracking imaging (2D-STI). Sixty Wistar rats were randomly divided into two groups, a myocardial infarction (MI) group, in which 50 rats were subjected to LAD occlusion for 30-45 min, and a sham-operated (SHAM) group that contained 10 rats serving as control. Echocardiography was performed at baseline and 1, 4 and 8 week(s) after the operation. High frequency two-dimensional images of left ventricular short axis at papillary muscle level were recorded. Peak systolic radial strain (PRS) and circumferential strain (PCS) were measured in the mid-ventricle in short-axis view by using EchoPAC workstation. Left ventricular internal diameter at diastole (LVIDd) and systole (LVIDs), fractional shortening (FS), ejection fraction (EF) and left ventricular mass (LVM) were measured by anatomical M-model echocardiography. Infarct size was measured using triphenyl tetrazolium chloride (TTC) staining 1 week and 8 weeks after the operation. Fibrosis of left ventricular myocardium was displayed using Van Gieson staining 1 week after the infarction. In terms of the TTC staining results, the left ventricle fell into three categories: infarcted, peri-infarcted and remote myocardial regions. Compared with those at baseline and in the SHAM group, (1) PRS and PCS in the infarcted, peri-infarcted and remote myocardial regions were significantly decreased in the MI group within 1 week after the operation (P<0.05) and the low levels lasted 8 weeks; (2) Compared with those at baseline, LVIDd, LVIDs, FS, EF and LVM in the MI group showed no significant difference 1 week after the operation (P>0.05). However, LVIDd, LVIDs and LVM were increased significantly 4 and 8 weeks after the operation (P<0.05), and FS and EF were decreased substantially (P<0.05). Van Gieson staining showed that fibrosis developed in all the three myocardial regions to varying degrees. It is concluded that 2D-STI is non-invasive and can be used to assess regional function of myocardium with different blood supply in rats following acute occlusion of the LAD, and can be used as a sensitive and reliable means to follow up the process of left ventricular remodeling.
本研究采用二维斑点追踪成像（2D-STI）评估大鼠左冠状动脉前降支（LAD）急性闭塞后左心室局部心肌功能的变化。将60只Wistar大鼠随机分为两组，即心肌梗死（MI）组（50只大鼠接受LAD闭塞30 - 45分钟）和假手术（SHAM）组（10只大鼠作为对照）。在基线以及术后1周、4周和8周进行超声心动图检查。记录乳头肌水平左心室短轴的高频二维图像。使用EchoPAC工作站在短轴视图的心室中部测量峰值收缩期径向应变（PRS）和圆周应变（PCS）。通过解剖M型超声心动图测量舒张末期左心室内径（LVIDd）、收缩末期左心室内径（LVIDs）、缩短分数（FS）、射血分数（EF）和左心室质量（LVM）。在术后1周和8周使用氯化三苯基四氮唑（TTC）染色测量梗死面积。梗死1周后使用Van Gieson染色显示左心室心肌纤维化情况。根据TTC染色结果，左心室分为梗死区、梗死周边区和远隔心肌区三类。与基线和SHAM组相比，（1）MI组术后1周内梗死区、梗死周边区和远隔心肌区的PRS和PCS显著降低（P<0.05），且低水平持续8周；（2）与基线相比，MI组术后1周LVIDd、LVIDs、FS、EF和LVM无显著差异（P>0.05）。然而，术后4周和8周LVIDd、LVIDs和LVM显著增加（P<0.05），FS和EF显著降低（P<0.05）。Van Gieson染色显示所有三个心肌区域均出现不同程度的纤维化。结论是2D-STI是非侵入性的，可用于评估大鼠LAD急性闭塞后不同血供区域的心肌功能，并且可作为随访左心室重构过程的敏感可靠手段。
