| Objectives: Along with the improvement of people's living standard and life prolonging, angiocardiopathy has already become one of the most important harmful factors to human health, and along with the rapid growth of coronary heart disease. Currently, treatments of coronary heart disease include PTCA, CABG, pharmacotherapy, diotherapy and gene therapy and so on. Coronary Artery Bypass Graft (CABG) is one of the most effective way of treating coronary heart disease. Graft mainly comes from the body of people's internal mammary artery (IMA) , radial artery , Saphenous vein and so on. Whereas, Saphenous vein graft is still the main resources of grafts in current surgery. However, in CABG, due to injure of improper surgical technic on vascular endothelial cells(VEC) and continuous pathological changes of coronary vascular itself, many factors will lead to the restenosis of grafts, such as partial or extensive intimal phenotype changes of coronary arteries and grafts after the operation , proliferation, thrombosis, atherosclerosis, abnormal activation of coagulation system, VSMC proliferation and migration, lipidosis and so on. How to increase the patency rate of grafts in short and long-term after operation is the focus in today's research areas of cardiac surgery. To explore the effective way of regulation and control of the changes in structures and functions of Coronary vasculars and Grafts after operation is the current major task.By comparing several different kind of preservation solutions of their protective effects for vein graft, this study is to find a more ideal graft preservative solution to enhance the short and long-term patency rate of grafts, to provide experimental basis for clinical application, to improve patients' life quality with coronary heart disease over the past, long-term survival, and to avoid another CABG surgery.Methods: This experiment is to study the different protective effects of graft preservation solution on rabbit external jugular vein, which provides strong evidence for the selection of graft protective solution in clinical CABG surgery. The process of this experiment imitated the one of human CABG bypass surgery, and adopted the animal model by transplanting the external jugular vein - common carotid artery bypass graft of healthy New Zealand rabbits. The 30 healthy New Zealand rabbits (offered by Animal Experimental Center of Hebei Medical University) were randomly divided into 3 protective solution groups (heparinzed saline group, papaverine group, Ligustrazine Hydrochloride group). Besides, during the operating process, different vascular bridge protective solutions were selected to interfere the constructive process of rabbit's external jugular vein - common carotid artery. The preserved part of the external jugular vein was distended by above 3 different solutions with 50mmHg pressure two times and then was stored in 3 different solutions for 1 hour, and later was brought to observe the ultrastructural changes of grafts under transmission electron microscope. The rest part of external jugular vein joined common carotid artery, the central part of re-graft body was harvested 2 weeks after. morphological changes of grafts were observed by light microscope, and ultrastructural changes of grafts were observed by transmission electron microscope. Image-Pro Plus 6.0 Biomedical Image Analysis System was adopted to measure the difference in thickness of lumen stenosis among 3 different groups. The analysis of differences between groups were conducted by SPSS16.0. All these were to conclude the efficacy of different treatment groups.Results: In experiment process, due to accidental death of an anesthesia, the death New Zealand rabbit belongs to the group of papaverine protection solution, the rest 29 rabbits have survived 2 weeks after the operation and remain healthy. The vein grafts were unobstructed when harvest. And remove the vein grafts from the survived 29 experimental animals 2 weeks later. 1 Compared with heparin protective solution group and papaverine protective solution, tetramethylpyrazine protective solution group has no obvious periductal inflammation in vein graft wall, no obvious fibrosis, nor proliferative reaction in both endangium and VSMC.The lumen stenosis of grafts derives from the ratio of luminal hyperplasia thickness and luminal thickness (L1/L2), and statistical analysis of differences among each groups are the followings: the comparison value P<0.05 among heparin protective solution group, papaverive protection solution group and tetramethylpyrazine protective solution group has shown that there was obvious differences; the comparison value P>0.05 between heparin protective solution group and tetramethylpyrazine protective solution group indicated that it was meaningless in statistics.2 The comparison of PCNA positive cells rate, the statistical analysis of differences among each groups are the followings: the comparison result of heparin protective solution group and papaverine protective solution group has shown that P>0.05, which indicated that it was meaningless in statistics; whereas, when heparin protective solution group and papaverine protective solution group are compared with tetramethylpyrazine protective solution group, the result has shown an obvious difference which is P<0.05.3 After CABG surgery, structural changes of grafts in tetramethylpyrazine protective solution group has obvious difference than in heparin protective solution group and in papaverine protective solution group. Light microscopy and transmission electron microscopy observations have shown that protected by tetramethylpyrazine, the intima structure of grafts' vessel wall is relatively complete, the hyperplasia in intima and VSMC is not obvious, nor the sub-structural changes in VEC, besides, the shape and sub-structure of VSMC is normal, and vacuolization to a lesser extent.Conclusions: CABG invasive operation is harm for grafts' vascular endothelial cell, which may cause several secondary chain reaction. This is the main nosogenesis of graft restenosis. Tetramethylpyrazine has protective, regulative and control function for VEC. To adopt protective function of tetramethylpyrazine for grafts into CABG surgery, is an effective way to keep down the damage of VEC, to promote the normal repair and regeneration, to limit the phenotypic change of regenerated VEC, to inhibit the start of inflammatory response after injury, to stop the formation of thrombus and VSMC's reactive migration and proliferation, and to suppress the fibrosis of vessel wall. Thereby, stop the chain reaction caused by the damage of grafts VEC after CABG surgery. It has obvious effect for graft restenosis after CABG surgery.
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