二维斑点追踪成像技术评价实验性大鼠慢性心力衰竭模型左心室径向收缩功能

目的 探讨二维斑点追踪成像(2D-STI)技术定量评价实验性大鼠慢性心力衰竭模型的左心室心肌径向收缩功能的价值.方法 SD大鼠40只,随机分为手术组(n=25)和假手术组(n=15),分别于术前、术后2、4、8周行超声心动图检查.于左心室腱索水平测量左心室舒张末期内径(LVEDd)、收缩末期内径(LVEDs),舒张末期室间隔(IVST),后壁厚度(PWT),计算短轴缩短率(FS)及射血分数(EF).采集并储存清晰的高帧频左心室乳头肌短轴动态图像.应用二维应变软件脱机分析左心室6节段的收缩期峰值径向应变(PRS)及整体径向应变(GPRS).比较各指标在手术组不同观察时点、手术组与假手术组同一观察时点的差异.结果 与术前及假手术组同一观察时点比较,术后2周手术组各测值差异无统计学意义(P均＞0.05)；术后4周,手术组IVST、PWT增厚(P均＜0.05),各节段PRS及GPRS减低(P均＜0.05)；术后8周,手术组LVEDd、LVEDs测值较之前各观察时点增大,FS、EF值较前明显减低,各节段PRS及GPRS减低(P均＜0.05),IVST、PWT较术前、术后2周及同一观察时点假手术组增厚(P均＜0.05),但与手术组术后4周比较差异无统计学意义(P均＞0.05).重复性测量显示PRS组间及组内测值比较均有较高一致性.结论 2D-STI能观察后负荷增加导致左心室心肌纤维径向重构与收缩功能变化的进展过程,是评价实验性大鼠慢性心力衰竭左心功能的有效方法.

Assessment of left ventricular radial systolic function of rat models with chronic heart failure by two-dimensional speckle tracking imaging

Objective To investigate the value of two-dimensional speckle tracking imaging (2D-STI) in the assessment of left ventricular radial function of rat models with chronic heart failure (CHF). Methods Totally 40 SD rats were randomly divided into two groups, i.e. operation group (n=25) and sham-surgical group (n=15). Left ventricular end diastolic dimension (LVEDd), left ventricular end systolic dimension (LVEDs), interventricular septal thickness (IVST), posterior wall thickness (PWT), fraction shortening (FS) and ejection fraction (EF) were measured at the left ventricular chordate level before operation and 2, 4 and 8 weeks after operation with M-mode echocardiography. High frame rate dynamic 2D images were recorded from the left ventricular short-axis views at the papillary muscle level. Peak systolic radial strains (PRS) of 6 segments and global peak radial strain (G_PRS) were measured with 2D-STI. All the parameters were compared between the two groups at the same time points, and the changes of values were observed in each group at the different time points. Results Compared with the values of pro-surgical and sham-surgical group at the same time point, there was no significant difference of each value in 2 weeks after operation (all P>0.05). Four weeks after operation, IVST, PWT in operation group increased, but PRS and G_PRS decreased (all P<0.05). Eight weeks after operation, LVEDd and LVEDs in operation group were larger, while FS and EF were lower than before operation and sham-surgical group (all P<0.05), PRS and G_PRS decreased compared with before operation and sham-surgical group (all P<0.05), IVST, PWT were thicken than those in before operation, 2 weeks after operation and sham-surgical group (all P<0.05), but not significantly different with those of 4 weeks after operation (all P>0.05). PRS obtained in intra- and inter-group both showed high agreement. Conclusion 2D-STI can observe left ventricular myocardial fibers radial remodeling and the progress of contraction function changes induced by after-load increasing. It is an efficient method to evaluate left ventricular function in CHF rat models.