Coronary Microthrombosis: Experimental And Clinical Studies

Part I The establishment of a new model of rat coronary microthrombosisBACKGROUND AND OBJECTIVE: Appearance of minor myocardial infarction after interventional treatment is not uncommon.The aim of this study is to develop a new model of minor myocardial infarction based on endothelial damage and thrombotic occlusion in coronary arteries, leading to small myocardial infarcts in rats. METHODS: A total of 120 male Sprague-Dawley rats were used in this study. Rats were anesthetized with ketamine and devided in two groups(sodium laurate group,n=88;microspheres group,n=32).In sodium laurate(SL) group,200 ug of sodium laurate was injected into the coronary artery,while in microspheres(MS) group,different amount of microspheres(42um in diameter) were injected into the coronary artery. The thrombus induction and consequent of endothelial damage in SL group were examined by histopathological analyses and electron microscope.The MBF of the left ventricule was examined by colored microspheres. RESULTS: Three hours after the injection of sodium laurate, microscopic examination of Carstairs Stain sections(n=8) revealed that microthrombi containing fibrin strands obstructed the perforating arteries in the myocardium. Under a transmission electron microscope (n=5), endothelial cells appeared exfoliated and the vascular lumen was obstructed by thrombus composed of degranulated platelets, fibrin, leukocytes, and erythrocytes. Multiple small myocardial infarcts were observed in the heart. MBF of the left ventricule was significantly decreased compared with control(3.31.3ml/g/min vs 2.51.2ml/g/min,P<0.01).LVEF was also decreased from 96.332.21 to 74.169.23 in the 1st operation day,P<0.05.Serial slice of the formalin embedded tissue showed that the size of the thrombi induced by sodium laurate was about 150×150×45μm.Compared with MS group,the micronecrosis is comparable while the inflammatory cells infiltration and endothelium injury are more sever in SL group. CONCLUSIONS: We nd treatment of minor myocardial infarction which is commonly seen in intpresent a new model of minor myocardial infarction in rats in which the small coronary arteries are occluded by microthrombi. This model is useful for the investigation of the pathophysiology aerventional therapy.Key words: microthrombosis;myocardial infarction;sodium laurate; MBF...