Assessment of Regional Left Ventricular Myocardial Function in Rats after Acute Occlusion of Left Anterior Descending Artery by Two-dimensional Speckle Tracking Imaging / 华中科技大学学报（医学）（英德文版）

ABSTRACT

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 ventrieular 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 categoriesinfarcted,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 myoeardium 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.