Pathological observation of acute myocardial infarction in Chinese miniswine.

The acute myocardial infarction (AMI) model in Chinese miniswine was built by percutaneous coronary artery occlusion. Pathological observation of AMI was performed, and the expression of tumor necrosis factor alpha (TNF-α) in the infarct sites was detected at different days after modeling in Chinese miniswine. The experimental findings may be used as the basis for blood flow reconstruction and intervention after AMI. Seven experimental Chinese miniswine were subjected to general anesthesia and Seldinger right femoral artery puncture. After coronary angiography, the gelfoam was injected via the microtube to occlude the obtuse marginal branch (OM branch). At 1 d, 3 d, 5 d, 7 d, 10 d, 14 d and 17 d after modeling, hetatoxylin-eosin (HE) staining was performed to observe the pathological changes and to detect the expression of TNF-α in the myocardial tissues. Cytoplasmic acidophilia of the necrotic myocardial tissues at 1 d after modeling was enhanced, and cytoplasmic granules were formed; at 3 d, the margins of the necrotic myocardial tissues were infiltrated by a large number of inflammatory cells; at 5 d, the nuclei of the necrotic myocardial cells were fragmented; at 7 d, extensive granulation tissues were formed at the margin of the necrotic myocardial tissues; at 10 d, part of the granulation tissues were replaced by fibrous scar tissues; at 14-17 d, all granulation tissues were replaced by fibrous scar tissues. Immunohistochemical detection indicated that no TNF-α expression in normal myocardial tissues. The TNF-α expression was first detected at 3 d in the necrotic myocardial tissues and then increased at 5 d and 7 d. After reaching the peak at 10 d, the expression began to decrease at 14 d and the decrease continued at 17 d. Coronary angiography showed the disappearance of blood flow at the distal end of OM branch occluded by gelfoam, indicating that AMI model was constructed successfully. The repair of the infarcted myocardium began at 10-17 d after modeling with safe blood flow reconstruction. TNF-α expression in the infarcted myocardium was the highest at 10 d, which can be explained by inflammation and repair of the infarcted myocardium.