不同时间段心肌梗死大鼠左心室心肌力学改变特点的斑点追踪显像研究

Assessment of left ventricular time-related deformations in post-infarction rats by ultrasound speckle tracking imaging

目的 应用斑点追踪技术评价心肌梗死大鼠不同时间段左室心肌形变及功能变化规律及特点.方法 选取同年龄健康成年SD大鼠20只,结扎大鼠前降支近端建立心肌梗死模型.将心功能符合要求且心肌梗死后仍存活的15只心肌梗死大鼠按照不同观察时间点分为术前对照、心肌梗死1d、4周和8周共4组.分别测量乳头肌短轴水平径向应变率（radial strain rate,SRrad）和圆周应变率（circumferential strain rate,SRcir）的收缩期峰值（SRrad-S和SRcir-S）,舒张早期峰值应变率（SRrad-E和SRcir-E）,舒张晚期峰值应变率（SRrad-A和SRcir-A）.测量左室二维超声指标.结果 心肌梗死1d组SRrad-S、SRradE、SRcir-S及SRcir-E在前壁和侧壁较心肌梗死前相应节段降低.心肌梗死4周组SRrad、SRcir在各节段较心肌梗死前各相应节段均降低.心肌梗死8周组左室心肌各节段SRrad、SRcir与心肌梗死4周组比较差异无统计学意义.结论 斑点追踪技术可以量化评价心肌梗死大鼠重构心肌的形变特点,有望为研究缺血性心脏疾病的病理变化特点提供新的技术支持.

Objective To evaluate left ventricular （LV） remodeling and function after acute myocardial infarction （MI） in rats using speckle tracking imaging （STI）. Methods The left anterior descending coronary was ligated to induce MI in twenty normal rats. One day after creation of MI, fifty survivals based on the diagnostic criteria of MI were divided into 4 groups as follows：pre-infarction, 1 day,4weeks,and 8 weeks after MI. Echocardiography was performed to evaluate the changes of left ventricularfunction in rats. M-mode and two-dimensional cross-sectional echocardiography data were acquired at the papillary muscle level and digitally stored for further analysis. Circumferential strain rate（SRcir） and radial strain rate（SRrad） indexes were measured by STI software for each animal. Results One day after MI,indexes of SRcir and SRrad in anterior and lateral segments were significantly decreased （P 〈0.01, for both）. Four weeks after MI,compared with baseline,SRrad and SRcir were decreased in all segments （ P 〈0.01）. Eight weeks after MI, however, SRrad and SRcir showed no significant difference compared with 4weeks group. Conclusions STI can correctly identify LV dysfunction in rats and can be used for serial assessment of cardiac remodeling in rats models.