宽高频超声对大鼠心肌梗死模型左心室形态结构变化的分型研究

目的探讨不同病理分型大鼠心肌梗死模型左心室形态结构变化的超声表现。方法对48只SD大鼠实施开胸手术,其中41例结扎左冠状动脉前降支(LAD)(实验组),7例假手术组仅打开心包膜。术后4周采用10~22MHz的宽高频超声测定左心室形态、结构和功能,并与病理结果进行比较分析。结果按照心肌梗死的轻、中、重度病理分类,不同梗死程度的左心室形态在二维超声显像中表现为短轴和长轴的不同变化;心肌梗死大鼠左心室内腔和肌壁的几何形态失真,表现为梗死部位即瘢痕组织部位肌壁薄、回声增强且不均匀;斑痕组织的部位、大小与病变程度相关,并与病理改变相一致。轻、中、重度心肌梗死模型心肌前壁均变薄,中度涉及侧壁,重度后壁亦有改变。随着心肌梗死程度的加重,左心室缩短分数逐渐下降。结论经胸宽高频超声心动图可以在大鼠心脏的短轴和长轴切面直接显示心肌梗死发生的部位、范围和程度,准确评价大鼠左心室形态结构和功能变化。

Evaluation of left ventricular structure and function types in rat heart myocardial infarction model using wideband high frequency echocardiography

Objective To study the method using wideband and high frequency ultrasound determining the degree and type of rat heart myocardial infarction (MI). Methods Chest open surgery was performed in 48 cases of SD rats, of these, the left anterior descending (LAD) coronary artery of 41 rats were ligated as study group; and the remaining 7 rats were kept as a sham group without ligation of LAD while open chest. Four weeks after the surgery, the rats were checked on echocardiography with a 10-22 MHz frequency transducer to measure the myocardial infarction (MI) size of the left ventricle (LV). The rats were then sacrificed and the hearts were sliced and stained with Masson Trichrome method to compare the changes of echo images with pathology. Results There were different changes in the B-mode images and M-mode images according to the type of MI. The anterior wall of LV was thinner in small, moderate and large size MI; the anterior and lateral wall were thinner in moderate and large size MI respectively; in large size MI, the posterior wall, anterior and lateral wall were all thinner. The infarcted region was echogenic and heterogeneous in texture, and the endocardial shape was deformed with the degree of MI both in short axis and long axis section of the LV. The position and size of infarction was coincident with pathological changes. The fraction shortening (FS) value from M-mode was gradually reduced from small size to large size of MI. Conclusions Transthoracic wideband, high frequency ultrasound may detect the LV structure, texture and heart functions of rat MI model in short axis and long axis clearly and it can evaluate the MI position, size and degree accurately.