用~99Tc^m-MIBI心肌显像评价犬急性心肌梗死后早期左室重构

Evaluation of early left ventricular remodeling in acute myocardial infarction dog model using ~99TC^m-MIBI myocardial imaging

目的使用^(99)Tc^m-甲氧基异丁基异腈(MIBI)心肌显像观察犬实验性急性心肌梗死(AMI)后6 h 内左心室形态、功能等早期重构变化。方法杂种犬24条,分为手术组16条,假手术组8条。手术组犬在麻醉下开胸打开心包,结扎冠状动脉左前降支(LAD)主干建成 AMI 模型。即刻按体重静脉注射^(99)Tc^m-MIBI 37～55.5 MBq/kg。结扎 LAD 后[21.87±11.03(14～48)]min 开始行首次显像,并连续采集6 h。假手术组手术过程同上,但不结扎冠状动脉 LAD。仪器为 ADAC VertexDual-head SPECT 仪。结果结扎后首次显像即可观察到左心室前壁、心尖部放射性缺损或明显减低,左室整体扩张变形、梗死区膨胀无室壁运动。QGS 软件计算手术组舒张末期容积(EDV)、收缩末期容积(ESV)分别为(48.73±12.74)、(32.57±8.10)ml,与假手术组[分别为(36.88±11.12)、(24.93±7.25)ml]相比差异有显著性(t=5.24、3.50,P<0.01);左室射血分数(LVEF)为(33.64±6.05)%与假手术组[(32.40±9.20)%]比较差异无显著性(t=0.95,P>0.05)。结扎 LAD 后6 h内 EDV、ESV 仍增大,而 LVEF 无明显变化。结论 ^(99)TC^m-MIBI 心肌显像可在 AMI 后早期(最早14min)就观察到左心形态、大小及功能改变等早期左室重构的发生,并可随时间进展了解 AMI 后心功能受损情况,是研究 AMI 后左室重构的有用方法。

Objective To observe early morphologic and functional remodeling in left ventricle by ^99Tc^m-methoxyisobutylisonitrile （MIBI） myocardial imaging within 6 h in experimental acute myocardial infarction （AMI） dog model. Methods Twenty-four dogs were divided into operated （ n = 16 ） and pseudooperated（ n = 8） group. In operated group, the main trunks of left anterior descending （LAD） coronary arteries were ligated under general anesthesia and AMI models were established. ^99Tc^m-MIBI was given intravenously with a dose of 37 - 55.5 MBq/kg ,^99Tc^m-MIBI myocardial imaging was performed with ADAC Vertex Dual-head SPECT. Eight dogs pseudo-operated served as controls. The first acquisition was started at [ 21. 87 ± 11.03 （ 14 - 48） ] rain after ligation, then the following acquisition was kept for 6 h. Results Typical defects were found at the anterior walls and apexes of left ventricles in all dogs after LAD ligation, beginning with the first acquisition; global dilatation and distortion of left ventricles were also found. The QGS software quantitative data of end-diastolic volume （EDV） and end-systolic volume （ESV） in operated group [ （48.73 ± 12.74） and （32.57 ± 8.10） ml ] were significantly increased compared with pseudo-operated group＇[（36.88±11.12） and （24.93±7.25） ml; t =5.24, 3.50; all P〈0.011. There was no significant difference in the values of LVEF between the two groups [ （ 33.64 ± 6.05 ） % and （ 32.40 ± 9.20） % , t =0.95, P 〉0. 05 ]. EDV and ESV were increased during the 6 h after ligation, while LVEF had no significant change. Conclusions Left ventricular remodeling may be visualized as early as 14 rain after LAD ligation by ^99Tc^m-MIBI myocardial imaging; the changes of left ventricular morphology and function occurre with time. Thereby ^99Tc^m-MIBI myocardial imaging is an effective method for studying left ventricular remodeling, and observation of ventricular injury progress with time.