Study On Hemodynamic Characteristics Simulation And Endothelial Response Of Intracranial Aneurysm Complicated With Arterial Stenosis

Intracranial aneurysm is a pathological expansion of cerebral vessels.Clinical data show that intracranial aneurysm is often accompanied by a certain degree of proximal artery stenosis.The occurrence and growth of intracranial aneurysms are believed to be caused by the interaction between hemodynamics and cellular biological factors.Abnormal hemodynamics,especially abnormal Wall Shear Stress(WSS),has an important influence on the occurrence and development of aneurysms.It is still unclear how arterial stenosis leads to arterial dilation after stenosis,and how stenosis induced flow stimulation affects the morphology and function of vascular Endothelial Cells(ECs),as well as the hemodynamic characteristics of aneurysms.If the hemodynamic factors can be combined with biological factors of vascular biological tissue,it will be helpful to explain the cause of coexistence of aneurysm and vascular stenosis,provide a deeper understanding of the related mechanism of aneurysm occurrence and development,provide new guidance for the prevention and intervention of aneurysm.In this paper,the hemodynamic characteristics of four straight vessels with different stenosis degree were analyzed by numerical simulation and flow experiment,and the wall shear stress distribution of different stenosis degree was determined.Furthermore,the in vitro transparent silica gel narrow straight vessels were fabricated based on the geometric model of numerical simulation,and the endothelialized silica gel vessel model was constructed by cultivating ECs on the inner wall of silica gel vessels,and the flow shear stimulation experiment was carried out on the ECs layer of the inner wall of silica gel tube.The response of ECs morphology and inflammatory factor expression to flow shear was analyzed by combining shear experiment results and numerical simulation WSS results.The results showed that with the increase of vascular stenosis,more obvious jet flow appeared.In the narrow downstream vortex region,the ECs shape was irregular,and the intercellular gap at the high WSS position increased.The expression of inflammatory factor MMP-9 and NF-κB did not differ significantly between 0% and 30% vessels.The expression of MMP-9 and NF-κB increased significantly when the arterial stenosis was 70%,which was associated with the high WSS region in the numerical simulation.Changes in WSS caused by different strictures lead to differences in ECs morphology and gene expression,while high strictures can directly increase the expression of inflammatory factors.Further,in view of the individuation of intracranial aneurysms with proximal vascular stenosis model,Artificially alter the degree of stenosis in stenotic vessels,got four different degree of proximal vascular stenosis of intracranial aneurysm model,the two-dimensional fluid-structure coupling simulation and analyses the influence of vascular stenosis aneurysm hemodynamic characteristics and the influence of the tumors had wall deformation.The main results show that the aneurysm cervical wall deformation is the largest due to the effect of narrow jet flow.The greater the degree of proximal stenosis,the greater the impact strength of the jet on the neck of the aneurysm,resulting in an increase in the displacement of the tumor wall,which may increase the risk of aneurysm neck rupture.In this paper,the effects of vascular stenosis on the morphology,function of vascular ECs and the hemodynamic characteristics of aneurysms were explored through numerical simulation binding biological experiment,which is helpful to understand the coexistence of aneurysms and stenosis,the related mechanism of aneurysm occurrence and development,as well as provide guidance for the prevention and intervention of aneurysms.