门控心肌灌注和心肌代谢显像动态评价小型猪室壁瘤形成后左心室功能和重构变化的实验研究

摘要

目的：建立小型猪室壁瘤模型，应用门控心肌灌注和心肌代谢显像动态评价室壁瘤形成过程中左心室心肌灌注、左心室整体功能及局部功能的变化，并探讨室壁瘤大小（呈反向运动或无运动的心肌节段数）与左心室功能[左心室射血分数（LVEF）]及左心室重构程度[左心室收缩末期容积（LVESV）和舒张末期容积(LVEDV)]的关系。方法：中华小型猪16只，雌雄不限，采用结扎钝缘支远端，阻断回旋支供应心尖部血流，并在冠状动脉左前降支第一对角支分叉处以下1 cm处放置Ameroid 环的方法建立模型，并在建模后的不同阶段（1 W、4 W、8 W）采用门控心肌灌注和心肌代谢显像动态观测心肌灌注减低程度和范围、室壁瘤形成情况以及LVEF、LVEDV、 LVESV等变化情况，并分析各指标间的相关性。结果：5头猪术中死亡，2头于术后第1周显像前死亡。6头猪在第8周末证实有室壁瘤形成，以病理结果为金标准。9头猪成功完成动态显像。显像结果为，在第1周（基础）有4头猪形成心尖部大室壁瘤，2头猪形成心尖部小室壁瘤，3头猪无室壁瘤形成。大室壁瘤猪第4周及第8周显像结果提示灌注受损范围及程度不断增加，室壁瘤逐渐增大，LVESV和LVEDV不断增加，而LVEF逐渐下降；而小室壁瘤或无室壁瘤猪的动态观察结果显示，以上指标均趋于相对稳定；另外，室壁瘤大小与LVEF、LVEDV和LVESV均呈较好的相关性（r 值分别为-0.726、0.855和0.825，P均<0.05）。结论：在室壁瘤形成的初期，当心肌灌注受损范围及程度比较严重时，容易形成大的室壁瘤，左心室整体功能受损程度和左心室重构程度随时间延长将逐渐加重，预后不良。反之，不形成或形成小的室壁瘤，预后较好，随时间变化均无明显心室重构。提示在急性期形成室壁瘤的大小可以在早期预测左心室整体收缩功能及左心室重构程度的发展趋势。%Objective: To dynamically evaluate left ventricular perfusion, global and local functional changes during left ventricular aneurysm (LVA) formation and to explore the relationship between the size of LVA and LVEF, LVESV, LVEDV by gated99mTc-MIBI SPECT (GSPECT) and gated18F-FDG PET metabolic (GPET) imaging in experimental pigs. Methods: LVA model was established by occlusion of left circumlfex artery (LCX) and placing an Ameroid constrictor at the proximal end of left anterior descending artery (LAD) in a total of 16 Chinese mini-pigs. At the 1st, 4th and 8th weeks of surgery, the changes of total perfusion defect (TPD), LVA formation and LVEF, LVESV, LVEDV were dynamically evaluated by GSPECT and GPET; the relationships between the size of LVA and LVEF, LVESV, LVEDV were analyzed respectively.Results: There were 5 pigs died in surgery and 2 died at the 1st week of modeling. According to golden (pathological) standard, 9 animals successfully ifnished the dynamic imaging study. At the 1st week of (basic) modeling, 4 animals formed large LVA, 2 formed small LVA at the apex and 3 without LVA formation. At the 4th and 8th weeks of modeling, dynamic imaging presented that the animals with large LVA had gradually increased range and degree of perfusion defect, LVEDV, LVESV, while gradually decreased LVEF; the above indexes were relatively stable in animals with small or none LVA. In addition, the size of LVA was related to LVEF (r=-7.26), LVEDV (r=0.855) and LVESV (r=0.825), allP<0.05. Conclusion: In experimental pigs, at the beginning of LVA formation, large range and severe perfusion defect may cause large aneurysm, the LV functional damage and remodeling may gradually increase and the prognosis is poor; in contrast, the animals with small or none LVA have better prognosis and usually without ventricular remodeling; which implies that in acute phase of LVA formation, the size of aneurysm may predict the trend of global LV systolic function and remodeling at the early stage.