适于影像学研究的猪慢性心肌缺血模型的制备

Establishment of swine model of chronic myocardial ischemia suitable for medical imaging

目的建立适于影像学研究的猪慢性心肌缺血模型。方法家猪10只,开胸手术游离冠状动脉左回旋支,在左旋支近段放置塑料Ameroid缩窄环,以建立左旋支慢性狭窄的心肌缺血模型。模型建立后5～6周内每周1次行冠状动脉造影和心脏MRI、超声及SPECT检查。以冠状动脉造影结果作为评价冠状动脉狭窄程度的标准。结果 10只家猪中2只术后早期死亡,8只成功建立慢性心肌缺血模型并存活至实验完成,共计行影像检查38例次,其中35例次满足图像分析。术后第1周,冠脉造影见左回旋支轻度狭窄,随术后时间延长,狭窄程度逐渐加重。术后第3周1只动物回旋支狭窄达90%,术后第5周4只动物狭窄达90%,第6周其余3只动物达90%。MRI扫描可见左室侧壁和后壁变薄,延迟灌注扫描见明显强化,超声及SPECT可见左室运动减弱,功能降低,缺血节段室壁灌注量降低甚至缺损。结论应用塑料Ameroid缩窄环可以成功制备慢性心肌缺血的动物模型,并适用于各种影像学方法观察冠状动脉渐进性狭窄过程中左室结构及心功能的变化。

Objective To establish a swine model of chronic myocardial ischemia for medical imaging research. Methods Ten pigs （20 to 26 kg） were sedated with an intramuscular injection of telazol （5 mg/kg）. Thoracotomy was performed through the fourth left intercostal space. The pericardium was opened and an ameroid constrictor was placed around the proximal left circumflex artery （LCX） just distal to the main stem of the left coronary artery matching the size of the vessel. Animals received medical imaging examinations,including coronary angiography,cardiac MRI,echocardiography and cardiac SPECT once a week within 5 to 6 weeks after the surgery. The degree of coronary artery stenosis was evaluated according to the results of coronary angiography. Results Of the 10 pigs,2 died at the early stage after surgery,and the left 8 were successfully induced to have chronic myocardial ischemia. The mild stenosis of LCX was found in 1 week after surgery,and the longer after surgery,the more serious stenosis of LCX was found. Ninety percent stenosis of LCX was found in 1,4 and 3 pigs respectively in 3,5 and 6 weeks after surgery. Thin lateral and posterior wall of left ventricle was found in plain MRI,which showing marked enhancement in delayed MRI perfusion scan. Echocardiography and SPECT showed motion weakness,function reduction and perfusion decrease or defects of ischemic segments of left ventricle. Conclusion The animal model of chronic myocardial ischemia can be successfully established with ameroid constrictor in pigs,which is an ideal model for medical imaging research.