Establishment And Study Of Bama Minipigs Acute Myocardial Infarction Model By Reperfusion Following Left Circumflex Occlusion

Objective: To establish a stable,reliable and good repeatability Bama minipigs model of acute myocardial infarction and pharmacodynamics study.Methods: About 3 months male minipigs were selected and divided into model group and aspirin group,each group of six,in addition,the other one animal are spare.Be under anaesthetic,the silicone vascular occlusion(SVO)was set in the left circumflex artery(LCX)in all animals,the silicone vascular occluder was occluded for 1 hour while the animals remained conscious followed by reperfusion.The animals that were successfully modeled were given by oral sodium chloride injection or aspirin in 5-10 min after the reperfusion.The cardiac ischemia and infarction condition was confirmed by an electrocardiogram(ECG)telemetry system during the modeling.The drug was given twice a day for 14 consecutive days from the day(D1)of coronary artery occlusion.ECG tests were performed on D15 and D30 after the first injection with a cardiac magnetic resonance imaging(MRI)on Day 30.The animals were then euthanized on D30 or the next day under general anesthesia.Five cross-sections of the heart at a thickness of five mm each were resected and incubated in TTC solution at 37 C° for 10 min.All five sections were placed on a plastic board after staining and photographed with a ruler to measure the area of infarct and the transmural thickness of the left ventricle.The five sections were then preserved in 10% neutral buffered formalin for fixation.The second section from all animals was prepared for routine Hematoxylin and eosin(HE)staining,a pathologist conducted histopathological examinations.Results: The thirteen animals were used for acute myocardial infarction model,among them one animals were forsook by the more left circumflex artery branches,one animal died during the modeling,the rest of eleven animals successfully completed the study.The ST segment was elevated after coronary artery occlusion,and continued to drive up after reperfusion,and push up more than 0.1 mV,T wave peaked,and Q wave was pathologic,indicating cardiac ischemia and myocardial infarction and thus proving the success of the modeling.Compared with model group,there were no statistical differences(P>0.05)in the myocardial infarction rate and thickness ratio(thickness ratio = the thickest thickness of the unaffected area/the thickness of the thinnest infarct area)in the aspirin group animals,but there was a slight trend of decrease,there were no statistical differences(P>0.05)in the myocardial fibrosis/necrosis by HE staining and ejection fraction.Conclusion: The acute myocardial infarction model of Bama minipigs were successfully constructed by using the silicone vascular occlusion occluding and re-perfusing coronary artery,which had the advantages of new technology,easy operation,animals awake,high success rate,stable,reliable,as well as good repeatability,and similar to the clinic pathologic characteristic of acute myocardial infarction,could become well as the clinical study of acute myocardial infarction of animal model.During the study,the aspirin could slightly reduce the degree of myocardial infarction and insignificant improve myocardial pathology and heart function.