犬心肌梗塞后围术期心脏功能与超微结构的变化

Changes of perioperative cardiac function and ultrastructure in dogs after myocardial infarction

探讨围手术期心肌缺血的发生机制。方法杂种犬１５只均分为三组：Ⅰ组：对照组。Ⅱ组：心梗模型组。Ⅲ组：心梗＋胃大部切除组；心梗后二周行胃大部切除术，观察心功能、心肌超微结构及心肌血管内皮生长因子（ＶＥＧＦ）ｍＲＮＡ的表达水平。结果Ⅲ组手术引起ＬＶ＋ｄＰ／ｄｔｍａｘ和ＣＩ下降，而同时ＬＶＥＤＦ、ＦＣＷＰ、ＴＰＲ及Ｔ值升高。心梗使ＶＥＧＦｍＲＮＡ表达增高，手术使心肌出现收缩带坏死、脂滴增加、线粒体空泡变，ＶＥＧＦｍＲＮＡ表达进一步增高。结论心梗后行胃大部分切除可导致左室舒缩功能障碍、心肌缺血及心肌ＶＥＧＦｍＲＮＡ表达增高是研究围手术期心肌缺血较好的动物模型。

Objective To investigate the pathogenesis of myocardial infarction (MI) as a major risk factor of perioperative mortality in non-cardiac operation by establishing the animal model. Methods Fifteen mongrel dogs were randomized for three groups: Group I ; control; Group I (MI) , their heart samples were taken two week. after ligation of left anterior descending coronary artery , Group Ⅲ(MI+partial gastrectomy) : two weeks after MI partial gastrectomy was performed , and their hemodynamics on pre-and postoperation were examined. Then vascular endothelial growth factor (VEGF) mRNA expression levels and ultrastructure of myocardial cells were observed in all of the heart samples in three groups. Results The operation decreased the maximal rate of left ventricular pressure rise (LV+dP/dtmax) and cardiac index while increased left ventricular end diastolic pressure , time course of isovolumic pressure and total periph- eral resistance. Under electron microscope , contracted band necrosis , increased amount of lipid droplets and vacuolar degenerated mitochondria were discovered in Group Ⅲ. In situ hybridization it was found that the level of VEGF mR- NA expression was increased in Group Ⅱ, and further increased in Group Ⅲ. Conclusion . Partial gastrectomy per- formed after myocardial infarction in dogs is a fair animal model for examining perioperative myocardial ischemia. It may produce left ventricular systolic and diastolic dysfunction , induce myocardial ischemia and increase VEGF mRNA expression in myocardium.