Liao Shu-sheng, Ruan Qin-yun, Lin Mei-yan, Yan Lei
Department of Ultrasound, the First Affiliated Hospital of Fujian Medical University, Fuzhou 350005, China.
Cardiovasc Ultrasound. 2012 Apr 3;10:17. doi: 10.1186/1476-7120-10-17.
Two-dimensional strain echocardiography (2DSE) technique has enabled accurate quantification of regional myocardial function. This experimental study was aimed to investigate the value of 2DSE in detection of segmental regional myocardial dysfunction induced by fibrosis following myocardial infarction in a small animal (rat) model.
A rat model of myocardial infarction was established by ligation of the proximal left anterior descending coronary artery in 17 SD rats. Regional myocardial function was detected by 2DSE at baseline and 4-weeks post-infarction, including end-systolic radial strain and strain rate (SR and SrR) and end-systolic circumferential strain and strain rate (SC and SrC) of each of six segments at papillary level. According to the size of scar found by histologic Masson staining, the optimal cutoff points of parameters for detecting scar area were analyzed and the sensitivity and specificity of every parameter to detect myocardial scar were obtained using ROC.
(1) Comparing with parameters measured at baseline, there were significant decreases in SR, SrR, SC and SrC of each segment at 4 weeks post-infarction, with the worst in the infarct area (32.90 ± 8.79 vs 11.18 ± 3.89, 6.28 ± 1.35 vs 3.18 ± 0.47, -14.46 ± 2.21 vs -6.30 ± 2.17 and 4.93 ± 0.95 vs 2.59 ± 1.16, respectively) (all P < 0.05). (2)By 4 weeks, the myocardium of infarct area (anteroseptum, anterior and anterolateral) had fibrosis (31.33 ± 9.89, 73.42 ± 13.21 and 13.99 ± 3.24%, respectively) with minimal fibrosis in inferoseptal segment (0.32 ± 0.19%), no fibrosis was found in the inferior and inferolateral segments. (3)Significant negative correlations were found between the size of segmental scar and 2DSE parameters (r-value -0.61 ~ -0.80, all P < 0.01) with the strongest correlation in SR. SR less than 10% has 84% sensitivity and 98% specificity for detecting segments of scar area greater than 30% with AUC = 0.97.
2DSE is able to assess regional myocardial dysfunction in a rat model of myocardial infarction and has high accuracy in detecting infarct segments with scar area greater than 30%.
二维应变超声心动图（2DSE）技术能够准确量化局部心肌功能。本实验研究旨在探讨2DSE在小动物（大鼠）模型中检测心肌梗死后纤维化所致节段性局部心肌功能障碍的价值。
通过结扎17只SD大鼠的左冠状动脉前降支近端建立心肌梗死大鼠模型。在基线和梗死后4周通过2DSE检测局部心肌功能，包括乳头肌水平六个节段各自的收缩末期径向应变和应变率（SR和SrR）以及收缩末期圆周应变和应变率（SC和SrC）。根据组织学Masson染色发现的瘢痕大小，分析检测瘢痕面积参数的最佳截断点，并使用ROC获得每个参数检测心肌瘢痕的敏感性和特异性。
（1）与基线测量参数相比，梗死后4周各节段的SR、SrR、SC和SrC均显著降低，梗死区域最差（分别为32.90±8.79对11.18±3.89、6.28±1.35对3.18±0.47、-14.46±2.21对-6.30±2.17和4.93±0.95对2.59±1.16）（均P<0.05）。（2）到4周时，梗死区域（前间隔、前壁和前侧壁）的心肌出现纤维化（分别为31.33±9.89、73.42±13.21和13.99±3.24%），下间隔节段纤维化最少（0.32±0.19%），下壁和下侧壁未发现纤维化。（3）节段性瘢痕大小与2DSE参数之间存在显著负相关（r值为-0.61~-0.80，均P<0.01），SR相关性最强。SR小于10%对检测瘢痕面积大于30%的节段具有84%的敏感性和98%的特异性，AUC=0.97。
2DSE能够评估心肌梗死大鼠模型中的局部心肌功能障碍，对检测瘢痕面积大于30%的梗死节段具有较高准确性。
