Hemodynamic Analysis Used In Coronary Artery Bypass Grafting Surgery

Background:Coronary Artery Bypass Graft(CABG)is currently the usual method for the treatment of coronary artery stenosis.However,due to the different parameters such as the location?degree and number of the stenosis,there is no uniform standard for the bypass.Bypass graft vessel adopt the Saphenous Vein Graft(SVG)single or sequential.There is a lot of controversy.We undertook a systematic review and meta-analysis of randomized controlled trials studies to compare the midterm or long-term patency and occurrence of adverse events of single or sequential vein grafts.On the other hand,Studies have shown that hemodynamic conditions are closely related to the effectiveness of the graft.Therefore,we use the computational fluid dynamics(CFD)simulation method to perform simulation on different surgical methods.By analyzing and comparing the different of hemodynamics,different surgical methods were evaluated.Method:First:A comprehensive search strategy was run in PubMed,Embase,the Cochrane Library,and the Chinese Biomedical Literature Database.Inclusion criteria were as follows:(1)two cohorts of patients received sequential and single saphenous vein grafting,respectively;(2)prospective or retrospective randomized controlled trials design;and(3)graft patency examined by angiography or ultrafast computed tomography.Two researchers independently performed the literature search,data extraction,and quality assessment.Second:The patient CT images were obtained and a three-dimensional model reconstruction.Using virtual surgery technology,SVG virtual bypass surgery was performed on this model.Three different surgical models were constructed and divided into model 1 single bypass;model2 parallel anastomosis sequential bypass;model3 vertical anastomosis sequential bypass.The model was simulated to obtain key hemodynamic indicatorsResults:1?562 papers were identified by searching titles related to vein grafts and the whole passage of 41 papers were reviewed which led to the identification of 16 papers finally.The occlusion rate of sequential graft is significantly lower than single graft(P<0.00001)and the relative risk of sequential graft to single graft is OR=0.57,95%CI:0.50?0.65.With regard to the occurrence of adverse events,the myocardial infarction in sequential vein grafting group is significantly lower than single group.2?By simulating three different surgical methods,the total flow model 1 was 0.000921,the model 2 was 0.000711,the model 3 was 0.000682,The flow rate of single graft was larger than sequential anastomosis,but there was no significant difference between the two kinds of sequential.3?The average wall shear stress(WSS)of the SVG was 0.35,1.45,and 1.26 Pa,respectively.The proportion of low WSS in SVG vessels was 82.23%,40.1%,and 46.23%,respectively.The WSS of the single bypass graft is the lowest and the low WSS area is the highest,while the WSS of the two sequential bypass graft is similar,and the sequential bypass graft of the vertical anastomosis has a larger low WSS area.4?The average deformation of the model 1,2,and 3 grafting vessels was 9.8 mm,10.4 mm and 12.6 mm,respectively.The deformation distribution of the three surgical schemes were similar,and the larger type variables appeared in the upper part of the aorta.At the same time,the overall deformation of the three surgical schemes were more uniform.Models 2 and 3,the two sequential bridges,are slightly higher in terms of integral variables than in individual bridges.At the same time,the shape variables of the vessels around the anastomosis of the two schemes are very small compared with other places.5?The oscillatory shear index of three different bypass grafts is different.The whole oscillatory shear index of the single bypass graft is very small,while the two types of sequential bypass graft have obvious high oscillatory shear index region.The area with high oscillatory shear index on the sequential bridge with parallel anastomosis is concentratedin the position of the transplanting,while the area with the high oscillatory shear index on the the vertical anastomosis is concentrated in the anastomotic area.6?The average vonmises stress of the model 1,2,and 3 grafting vessels was 5020 Pa,6020 Pa,4900 Pa.The equivalent stress of the three bypass is very low,which indicates that there is no excessive stress load on the bypass graft.Most of the stress loads are distributed on the aortic.There is no significant difference in the paradigm equivalent stress among the three.Conclusion:1?In this study,the meta-analysis was used to analyze the published prospective RCT research.On the whole,the effect of sequential graft is better than the single.The perioperative mortality,the occlusive rate of bypass graft and the incidence of myocardial infarction had obvious advantages,but there was no significant difference in the incidence of stroke.There is no increase of death with myocardial infarction on sequential groups.2?From the simulation mechanical analysis of two different anastomosis modes,it can be seen that parallel anastomosis is better.In theory,intimal hyperplasia may cause anastomotic stenosis.Although the wall shear stress is high in parallel anastomosis,it is not on the anastomosis.Therefore,the mechanical results can be better by adjusting the angle of graft.The surgery may become difficultly and require longer vein.3?The short-term patency of different bypass grafts have no significant difference.However,due to the difference between hemodynamic environment and structural mechanics,there are difference in medium-and long-term effectiveness.