心肌梗死与室壁瘤心肌力学重构规律的斑点追踪显像比较研究

Assessment of the difference of myocardium strain between myocadial infarction and ventricular aneurysm by two-dimensional speckle-tracking imaging in rabbits

目的应用二维超声斑点追踪技术（2D-STI）比较兔梗死心肌与室壁瘤心肌力学重构的规律和特点。方法26只健康新西兰白兔，6只作为对照组，20只作为实验组，结扎左前降支及左回旋支制作室壁瘤模型，饲养4周后，根据超声及病理学检查有无室壁瘤形成将实验组分为心肌梗死组和室壁瘤组，应用2D-ST1分别测量并分析左室短轴观心尖水平各节段径向应变率（radialstrainrate，SrR）和圆周应变率（circumferentialstrainrate，SrC）的收缩期峰值（SrR—S、SrC—s）、舒张早期应变率峰值（SrR—E、SrC—E）及舒张晚期应变率峰值（SrR—A、SrC—A），并计算各节段应变率下降百分比。结果①与对照组比较，心肌梗死组及室壁瘤组各节段收缩期及舒张期径向应变率及圆周应变率均降低，以室壁瘤组下降显著（P〈0．05）。②与心肌梗死组比较，室壁瘤组各节段收缩期及舒张期径向应变率及圆周应变率下降百分比增大，以前壁、侧壁SrR—S、SrC—S下降百分比较显著（Pd0．05）。③前壁、侧壁SrR—S、SrC—S下降百分比与左室射血分数有较好的直线相关关系，r分别为0．82、0．72、0．75、0．71。④ROC曲线分析显示，以应变率下降百分比值60％为临界点，前壁、侧壁SrC—S及SrR—S下降百分比诊断室壁瘤的特异性分别为73．60％、78．20％、69．70％、83．30％，灵敏性分别为83．30％、84．40％、83．30％、67．70％。结论室壁瘤形成后心肌力学重构以前壁及侧壁为主，前壁及侧壁收缩期心肌应变率下降百分比可作为室壁瘤心肌重构和反映心功能下降的一个重要力学指标。

Objective To evaluate the difference of myocardium strain between myocadial infarction and ventricular aneurysm （VA） by two-dimensional speckle-tracking imaging in rabbits. Methods 26 healthy New Zealand white rabbits were enrolled in this study,6 were put into the control group and 20 in the experimental group, models of myocardial infarction concomitant with VA were prepared by the ligation of the middle segment of left anterior descending artery and left circumflex artery. At 4 weeks after the procedure, according to the pathological inspect and echocardiography for whether VA formed, the experimental animals were divided into the VA group and the myoeadial infarction group. Echocardiography was performed to measure the LV cavity size and cardiac function. Radial strain rate （SrR） and circumferential strain rate（SrC） indexes were measured by 2D-STI software for each animal at the level of apex in left ventrieular short-axis view, and then calculated the strain rate decrease percentage in each segment. Results l）Compared with the control group, SrR-S, SrR-E, SrR-A, SrC-S, SrC-E, SrC-A in all segments were reduced significantly in the VA group and the myocadial infarction group （ P〈 0.05）, the VA group was the most significant. 2）Compared with the myocadial infarction group, the strain rate decrease percentage of SrR-S,SrR-E, SrR-A, SrC-S, SrC-E, SrC-A in all segment had significant in the VA group. Comparison between the each section, the strain rate decrease percentage SrRSateral wall SrC-Santeri Ⅱ, SrC-Slateral wall were the most significant. 3）There were the tighter relationship betweenthe strain rate decrease percentage of SrC Santeri 11, SrR-Sla, SrC-Sla wall and left ventricular ejection fraction （ r = 0.82,0.72,0.75,0.71, repectively, all P 〈0.05 ）. 4） The ROC curve analysis showed that when the strain rate decrease percentage was 60% as the critical point,the strain rate decrease percentage of SrC-Santri ii, SrC-Sl,toral , SrR-So, SrR-Sl, wall had a sensitivity of 83.30 X, 84.40%, 83.30%, 67.70% and a specificity was 73.60%, 78.20%,0, 69.70%, 83.30% for prognosis ventricular aneurysm, repectively. Conclusions After ventrieular aneurysm formation, anterior and lateral wall myocardial strain were give priority to the myocardial mechanics reconstruction, thus systolic myocardial strain rate decrease percentage can be important indicator of infarction myocardial developing into ventricular aneurysm.