| Purpose: To explore simple and effective method for the preparation of rabbit myocardial infarction so as to pursue a kind of quick, high efficient, and correct examining method for the diagnosis and of rabbit myocardial infarction so as to lay foundation for the further researching of experimental analysis of this research group and provide important value for customized clinical treatment.Objective: 50 Japanese white rabbits were randomly divided into two groups, that is, the group with myocardial infarction and the group of sham control. The animals in both groups had thoracotomy without the need to have endotracheal intubation and ventilator and the rabbit pleurals were retained complete. The left anterior descending coronary arteries in the group of myocardial infarction were ligatured, and in the group of sham control the same positions were only threaded but without ligation after the opening of the chest. The changes of diagnostic indexes like the electrocardiogram, serum myocardial enzyme, composite ultrasonic cardiogram (two-dimensional echocardiography, M-typed echocardiography, two-dimensional speckle tracking imaging, and real-time myocardial contrast echocardiography) 30 min,2h,6h,1d, and 1w before and after the operation on the two groups of animals. The hearts were taken out 30 min,2h,6h,1d, and 1w after the ligation of the coronary arteries, then the hearts were cut into slices along brachyaxis and then HE and MAS SON dying were conducted so as to observe the status of pathological changes of the rabbit myocardium with myocardial infarction at different time section and compare them with the results of the examinations on the electrocardiogram, serum myocardial enzyme, and compound ultrasonic cardiogram.Results:1 General status:Five rabbits died in the group with myocardial infarction with a survival rate of 80%; while in the group with sham control two rabbits died with a survival rate of 92%.2 Electrocardiogram: The heart rates of the rabbits changed after the modeling in the group with myocardial infarction and the group of sham control, but the differences are of no statistical meaning (P>0.05), and no obvious arrhythmia appeared during the process of the operation. The electrocardiographic wave changed immediately after the ligation of coronary artery of the rabbits in the group with myocardial infarction, and it mainly had lowered ST section within 30 minutes, sometimes it could be seen that the T waves were negatively and positively dual-directional, and the lifting of the ST section was not obvious; ST lifting as well as highly rising T wave may be seen frequently 2 hours after the operation as the typical characters of electrocardiogram on myocardial infarction, and pathologic Q Wave could be seen on the electrocardiograms of some rabbits with myocardial infarction one day and one week after the operation. The electrocardiograms before and after the modeling of the rabbits in the group of sham control did not had significant changes, and only some ST sections of were lifted at the moment when the hearts were dragged after threading, and after the loosening the electrocardiogram became normal.3 Serum myocardial enzymes: One-way variance analyses were conducted on the results of the serum myocardial enzyme 30 min,2h,6h,1d and 1w before and after the modeling of the rabbits in the group with myocardial infarction, and the differences in CK, CK-MB, and AST were of statistical meaning (P<0.05). The risings of the serum myocardial enzyme were mostly obvious 6 hours and one day after the operation, while significant differences existed compared to that of the group in sham control in the same time period (P<0.05), and the serum myocardial enzyme is significantly higher than that of the group with sham control in the same time period. Although the serum myocardial enzymes of some rabbits in the group of sham control had been lifted temporarily, the changes were not significant and they returned to the normal level six hours after the operation.4 Composite ultrasonic cardiogram:Regional wall motion abnormality was seen in some rabbits with myocardial infarction 30 min,1 h, and 2 h after the modeling of the two dimensional and M-typed ultrasonic cardiogram, and the cardiac functions were almost not changed compared to that before the operation (P>0.05); and it could be seen that the motions of the anterior septum and the left ventricular wall of the rabbit with myocardial infarction were significantly reduced and gradually become stiff with the scope gradually expanded and the function of the heart function of the rabbit were significantly reduced (P＜0.05).The speckle-tracking imaging technology could quantitatively comment on the status of the regional wall motion, and it was found that the motion of part of the ventricular wall of the rabbits with myocardial infarction had been significantly changed 30 minutes after the operation, which was of statistical meaning compared to that before the operation (P＜0.05). With the extension of time, the number of the abnormal segments increased gradually, and the sensitivity was excellent than the traditional two-dimensional ultrasonography. It was found after real-time myocardial contrast echocardiography that the contrast between the harmed sections and unharmed sections of the rabbits in the group with myocardial infarction was significantly enhanced with the antetheca and the anterior septum having changed most significantly. No significant changes had taken place in the various indexes of the echocardiographies of the rabbits in the group of sham control before and after the operation through dynamic observation.5 Histopathology: It had been proved by HE and MASSON dying on the rabbits in the group with myocardial infarction that there were pathological findings of myocardial infarction and with the elapsing of time the infarction was increasingly deteriorated with the infarct size growing larger. During the early period of the myocardium (30 min and 2 h after the operation) only scattered small infarctions could be seen, while in the middle period of the myocardium (6 hours after the operation) significant pathological changes of myocardial infarction could be seen, and there were swollen cardiomyocytes arranged disorderly in the area of the infarction with some of them dissolved and broken. In addition, some cell nucleus were swollen and loosened with neutrophile granulocytes could be seen in adjacent areas. In the last period of myocardium (one day and one week after the operation) a lot of cell nucleus were broken, dissolved and disappeared with the myocardial tissues becoming coagulation necrosis.Conclusion: The myocardial infarction animal models could be successively established through the ligation of left anterior descending branches of the artery coronaries of the rabbits, and technologies like electrocardiogram, serum myocardial enzyme, and composite ultrasonic cardiogram were combined for observation, through which we could correctly and sensitively diagnose for myocardial infarction, judge the degrees of myocardial infarction, lay foundation for further analysis by this researching group on coronary heart disease and provide important value for customized clinical treatment by the physicians. |
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