Aneurysm Of The Hemodynamic Analysis

Subarachnoid hemorrhage caused by rupture of cerebral aneurysm is a serious cerebrovascular disease endangering people's health. Surgical clipping and endovascular embolization are the most common methods of treating cerebral aneurysm. The evolution of an aneurysm may be affected by variety of factors, but it is universally accepted that hemodynamic factors are thought to have very close relationships with the natural history of cerebral aneurysm. In addition, intra-aneurismal hemodynamic factors are also used to optimize and evaluate the endovascular treatment of individual aneurysms in the clinical setting.We presented a new fluid-structure interaction (FSI) computational modeling of cerebral aneurysm based on summarizing the advantages of previous computational models. The results obtained with this new computational model were compared with the results obtained with the previous computational models. The comparison of the results shows that this new computational model can be used for not only analyzing local fluid-structure interaction between blood flow and aneurismal wall deformation but also describing complex blood flow patterns in the upstream parent artery, which are beneficial to give a more accurate prediction of wall shear stress (WSS) on the aneurismal wall.By collaborating with interventional neuroradiology service, we used this new FSI computational model to analyze aneurismal wall deformation, wall stress and wall shear stress in 18 patient-specific cerebral aneurysms with daughter aneurysms, with special emphasis on comparing the hemodynamic differences between aneurysm and daughter aneurysm. The results demonstrate two reasons interpreting clinical observation that the appearance of daughter aneurysm is strongly correlated with an increased risk of aneurismal future rupture:One is that WSS is relatively low on the daughter aneurismal wall; The other is that wall deformation is relatively high on the daughter aneurysm.The surface geometric data of three different cerebral stents were reconstructed by using both Computer Aided Design software and ultra-high-resolution Micro-CT, and the process of endovascular occluding aneurysms with coils was modeled as a porous medium, with porosity decreasing as coils were inserted. Numerical simulation have been done to understand the patient-specific intra-aneurismal hemodynamic alterations caused by endovascular treatment. Firstly, Silk stent and EZ stent were used to study the sensitivity of the calculations with respect to stent modeling, and comparisons of the flow fields obtained by modeling the entire stent and only the portion that cover the neck were carried out. The comparison of the results shows that for Silk stent, the flow patterns and wall shear stress distributions obtained with the entire stent model are in good agreement with those obtained with partial stent model, however for EZ stent, the hemodynamic differences obtained with these two stent model are very obvious. Secondly, the effects of different stent design on hemodynamic of different aneurysms were investigated. We find that different alterations of the hemodynamics caused by deploying stent largely depend on the original blood flow patterns of the aneurysm and stent design. In the end, hemodynamic comparisons of surgical outcome of aneurysm treated by stent-assisted coil embolization and stent without coil embolization were carried out. The comparison of the results shows that two different treatment strategies for cerebral aneurysm can produce different alterations of the hemodynamics for the same patient. Based on the previous experience in clinical research, these alterations may play a important role in predicting outcomes for endovascular treating aneurysm. Therefore we think it is feasible and necessary for the optimization of the therapeutic option to use computational hemodynamic.In the experimental studies, the measurement of blood velocity distribution was conducted using an in vitro silicone model of carotid artery stenosis with particle imaging velocimetry. The experimental results are found to be remarkably similar with our numerical simulation results,which validate numerical simulation software and meshing method in our study.