| PART â… : Establishment of minimal-invasive Chinese Miniswine Model of Myocardial Infarction by Catheterization Balloon in Coronary ArteryAim To explore and develop a Chinese Miniswine model of myocardial infarction (MI) by coronary occlusion with angioplasty Catheterization balloon. Methods After anesthesia, 20 mm or 25 mm angioplasty Catheterization balloon was positioned in the distal of the second Diagnonal branch of left anterior descending (LAD) through femoral artery or carotid artery on the hearts in 20 Chinese Minis wines. The balloon was inflated and occluded the LAD for 120 min after precondition with 4~5 myocardial ischemia. Electrocardiography and Blood pressure were monitored. Ultrasoundgraphy, LDH, CK, CK-MB and Coronary angiography were also investigated to confirm AMI. Results eighteen out of twenty pigs underwent successful induction of AMI, but one pig died in the period of postoperation 20 days, two pigs died from ventricular fibrillation during 60 ~ 100 min after operation. AMI was confirmed by dynamic changes of electrocardiography , LDH, CK, CK-MB and further pathology. Regional wall motion abnormalities were found by two dimensional echocardiography preoperation and 1 h, 1 day , 2 days and 2 weeks in all pigs after operation. Conclusions A minimal-invasive swine model of AMI by usingangioplasty Catheterization balloon technique is feasible and relatively effective.PART II : Establishment of a Miniswine Model during perioperative period with thoracotomy after Old Myocardial InfarctionAim: A greater numbers of patients are presenting for surgery with ageing-related, preexisting conditions that place them at greater risk of an adverse outcome, such as cardiac or pulmonary disease. Adverse cardiovascular events are thinked major causes of morbidity and mortality after undergoing surgery. Chinese miniswines with minimal-invasively induced myocardial infarction were used for the experiments. To establish the miniswine model of perioperative period of thoracotomy with old myocardial infarction, and observate marker proving the model. Methods: 8Chinese miniswines with weight 30 ~ 40 kg were divided into two groups. Understerile condition, a left thoracotomy of 10-12 cm was performed through the fourth intercostal space. The pericardium was opened and the left anterior descending of left coronary artery was dissociated free. After thoracotomy, the effects of surgery was observed during postoperative 7 days. Electrocardiography, Ultrasoundgraphy , LDH, CK, CK-MB and blood gas were also investigated to confirm the effects of the perioperative period at preoperative and during postoperative period of 1 , 3 , 7 days, and then the appearance of the heart was observed. Furthermore, myocardial samples were obtained. Results: During preoperative and postoperative of 1 , 3 and 7 days in 5 pigs, Cardiac injury and cardiac dysfunction were confirmed by dynamic changes of electrocardiography , echocardiography, LDH, CK, CK-MB. Pathology and regional wall motion abnormalities were found by two dimensional echocardiography technique. Hypoxemia and retention of carbon dioxide were failed to find. The mortality of ainmals during perioperative period was 20%. Perioperative ischemia and MI may be a major factor of morbidity and mortality after surgery. A miniswine model was established successfully in perioperative period of thoracotomy after myocardial infarction. Conclusions: A miniswine model of perioperative period ofthoracotomy with old myocardial infarction was successfully established. Cardiac function were assessed by two dimensional echocardiography and myocardial injury were measured by myocardial enzyme markers and confirmed by cardiac pathological inspection.PART El Cardiac Protective Effect of Endogenous Heme Oxygenase-1 on a Chinese Miniswine Model of Old Myocardial Infarction during Preioperative Period of ThoracotomyAim: Observing the relationship of cardiac function and HO-1 expression in the myocardium in a Chinese miniswine model of old myocardial infarction during preioperative period of thoracotomy treated with special inducer and inhibitor ofheme oxygenase-1. Methods The 17 Chinese miniswines of weight 30-40 kg withold myocardial infarction were selected and thoracotomized. Those animals were randomly divided into four groups. 1) Myocardial infarction group protocol (MIG, n=3) or Control group: Opened thorax and obtained myocardial samples;2) Preioperative period group protocol (PG, n=4): the procedure of thoracotomy and obtaining myocardial samples is same as MIG, after 7 days postoperative;3) Hemin treated group (PHG, n=4): similar to PG, preioperative period treated with Hemin;4) ZnPPIX treated group (PZG, n=6): similar to PG, Preioperative period treated with ZnPPIX. After thoracotomy, the effects of surgery was observed during postoperative 1 ,3,7 days.Electrocardiography,Ultrasoundgraphy, LDH, CK, CK-MB and Blood gas were investigated. The samples were examined with pathological methods and the areas of myocardial infarction were calculated. Results The values of cardiac function in PG were significantly lower than that in MIG and PHG (p<0.01), while higher in PG than that in PZG (p<0.05). The enzyme markers of myocardial damage in PG were remarkably less than those of PZG (p<0.05), but those of MIG and PHG almost were unchanged (p<0.01). The damage of myocardial structure in PHG was reduced inMIG but aggravated obviously in PZG. Expression of localization HO-1 protein in myocardium showed the intense staining in interstitial spaces and myocytes of perivascular region in groups of MIG, PHG and PG. The expression of myocardial HO-1 protein and mRNA in PHG were enhanced prominently (p<0.01), as a contrast, down regulation of myocardial HO-1 protein and mRNA in PZG (p<0.01) was observed. HO-1 expression in PG was lower than those of MIG (p<0.01). Conclusion Cardiac function and structure in the miniswine with myocardial infarction during perioperative period were deteriorated , which is closely associated with the inhibiting of expression of myocardial endogenous HO-1 protein and mRNA . This sort during perioperative period was ameliorated by endogenous HO-1 upregulated. It is suggests that the myocardial endogenous HO-1 may have cardiac protective role of the miniswine with old myocardial infarction during perioperative period.
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