以球囊封堵法建立猪心肌梗死模型的可行性研究

Feasibility study of establishing a swine myocardial infarction model by balloon occlusion method

背景:国外20世纪90年代开始采用球囊封堵建立闭胸式心肌梗死动物模型,但术中室颤及血栓形成等因素降低了制作心肌梗死动物模型的成功率。目前国内建立球囊封堵闭胸式心肌梗死大动物模型的报道较少。目的:应用球囊封堵法建立闭胸式猪心肌梗死模型,探索提高建模成功率的方法。设计、时间及地点:随机对照动物实验,病理观察,于2008-07/2009-05在昆明医学院第一附属医院心内科及昆明医学院病理教研室完成。材料:8～11月龄健康滇南小耳猪15只,体质量19～25kg,随机数字表分为3组:假手术组、缺血再灌注组、缺血后处理组,每组5只。方法:冠脉封堵后和再灌注期预防性静滴利多卡因1.0～2.0mg/kg,以减少恶性心律失常的发生率,使用肝素防治血栓形成,在X射线监控下将球囊导管送至冠状动脉左前降支第一对角支的远端,假手术组只放置球囊至冠状动脉左前降支,不封堵;缺血再灌注组行球囊充气堵闭冠状动脉左前降支60min后撤除球囊;缺血后处理组行球囊充气堵闭冠状动脉左前降支60min后,球囊放气30s,充气30s(循环8次)后撤除球囊。主要观察指标:行冠脉造影、心电图及心肌酶检测评价心肌梗死模型的建立情况。3d后行心肌三氯四氮唑染色及病理学检查验证心肌梗死。结果:假手术组猪全部存活;缺血再灌注组4只成功建立心肌梗死模型,1只死于顽固性室颤;缺血后处理组全部成功建立心肌梗死模型。堵闭左前降支远端后,心电图V1～3导联上ST段抬高,有病理性Q波形成;心肌酶谱演变过程与人体心肌梗死过程基本一致。心肌梗死部位分别位于心尖、左心室前壁、前间隔部。三氯四氮唑染色后正常心肌呈砖红色,梗死区心肌颜色暗淡,呈灰白色;病理学检查显示,梗死区心肌正常结构破坏,胞浆浓缩,染色加深,横纹消失,核浓缩、溶解、碎裂,梗死区内有较多的红细胞,梗死区周围有较多肉芽组织增生及大量炎性细胞浸润。结论:球囊封堵冠脉建立猪闭胸式心肌梗死模型对动物创伤性小,且最为接近临床实际的过程,术中使用利多卡因及肝素防治心律失常及血栓形成是成功建立该模型的有效方法,缺血后处理可能是提高建模成功率的因素之一。

BACKGROUND： In 1990s, overseas researchers use balloon occlusion method for establishing closed-chest animal models of myocardial infarction. But, ventricular fibrillation and thrombosis of intraoperative factors reduce the success rate of establishing the models. Currently, there are a few reports on establishing the large animal models. OBJECTIVE： We used balloon occlusion method for establishing closed-chest swine models of myocardial infarction, and explored ways to improve the success rate of modeling. DESIGN, TIME AND SETTING： The randomized controlled animal study of pathology observation was performed at the Department of Cardiology, First Affiliated Hospital of Kunming Medical College and Research Room of Pathology, Kunming Medical College from July 2008 to May 2009. MATERIALS： Fifteen Diannan small-ear pigs weighing 19-25 kg, aged 8 11 months, were divided into three groups： sham operation group, ischemia-reperfusion group, and ischemic postconditioning group, with 5 pigs in each group. METHODS： After the coronary occlusion and reperfusion period, the prophylactic use of lidocaine （1.0-2.0 mg/kg） infusion to control arrhythmia, and use of heparin to prevent and treat the thrombosis. A balloon catheter was positioned in the distal end of the first diagonal branch of the left anterior descending （LAD） artery under fluoroscopic guidance. In the sham operation group, the balloon was only placed to the LAD, did not block coronary artery. In the ischemia-reperfusion group, inflatable balloon occlusion was done for 60 minutes in the LAD after the balloon removed. In ischemic postconditioning group, after the balloon was inflated and occluded the LAD for 60 minutes, ischemic postconditioning was elicited by eight cycles of 30-second reperfusion, followed by 30-second reocclusion. MAIN OUTCOME MEASURES： Coronary angiography, electrocardiogram （ECG） and cardiac enzymes test was conducted to evaluate models of myocardial infarction. After three days, cardiac 2,3,5-triphenyltetrazolium chloride （TTC） staining and pathological examination was done to verify myocardial infarction. RESULTS： In the sham operation group, all pigs survived. In the ischemia-reperfusion group, 4 pig models of myocardial infarction were successfully established, and one died of refractory ventricular fibrillation. In the ischemic postconditioning group, models of myocardial infarction after ischemia were successfully established. Following distal left anterior descending artery occlusion, the ECG leads V1 3 on the ST-segment elevation, the sick rational Q-wave formed; myocardial enzyme evolution of myocardial infarction in the human body was basically the same process. The site of myocardial infarction, basically the same parts, was located in apical, left ventricular anterior wall, and the former interval. TTC staining was normal myocardium brick red, myocardial infarct area appeared pale; pathological examination revealed a normal structure of myocardial infarct damage, cytoplasm condensed, dyeing deepening, transverse striations disappeared, nuclear enrichment, dissolution, fragmentation, many erythrocytes around the infarct area with abundant granulation tissue and a large infiltration of inflammatory cells. CONCLUSION： The described model presents a less invasion to the animals, and is the closest to the process of clinical practice. intraoperative use of lidocaine and heparin for controlling arrhythmia and thrombosis of the models is successfully established as an effective manner. Ischemic postconditioning may be one of the factors for improving the modeling success rate.