Establishing a model of acute myocardial infarction in rats without artificial ventilation

Objective To establish a model of acute myocardial infarction in rats without artificial ventilation.Methods After anesthesia,left thoracotomy was performed in 30 adult SD rats by blunt dissection of intercostal muscles of the fourth intercostal space,and the left anterior descending(LAD) coronary artery was ligated to establish a model of myocardial infarction under spontaneous breathing condition.Changes of electrocardiography were recorded during the operation and 1 day,3 days,1 week and 2 weeks after model establishment.Histomorphological changes of the heart were observed under thoracotomy 2 weeks after operation.Pale appearance in ischemic myocardium would suggest the successful establishment of myocardial infarction and eight models were killed to determine pathological changes of myocardial infarction by HE staining.Results Twenty-five models of myocardial infarction were successfully established with a survival rate of 83.33% 2 weeks after operation.After ligation of LAD,the ST segment elevated and the pathological Q wave appeared after 30 min.Two weeks after establishment of myocardial infarction model,ischemic myocardium showed pale appearance and the motion of ventricular wall became weaker.HE staining revealed that cardiomyocytes disappeared and were replaced by fibrous tissues and collagen.Remnant cardiomyocytes were arranged disorderly and myofibers were fractured,with interstitial damage and fibrous tissue hyperplasia.Conclusion By this method,a model of acute myocardial infarction in rats can be established simply and effectively without using artificial ventilation.