支架置入前脑动脉瘤血流场的特性分析

Blood flow field characteristics of cerebral aneurysm before stent implantation

BACKGROUND: Cerebral aneurysm is a kind of mortal hemangioma, and its treatments such as endovascular embolization and clipping both cause high postoperative recurrence rate and mortality. So the stent implantation for cerebral aneurysm is coming into being.OBJECTTVE: To evaluate the hemodynamic parameters after stent implantation into cerebral aneurysm and to provide a novel feasible strategy for clinical treatment. METHODS: A retrospective analysis was preformed based on the CT image data of 11 patients with cerebral aneurysm from the Affiliated Hospital of Xinjiang Medical University. Firstly, the flexible and solid model of cerebral aneurysm was established by the MIMICS and reverse engineering. Secondly, the matching stent model was implanted into the cerebral aneurysm, and then the blood flow structure of cerebral aneurysm was analyzed by the fluid dynamics theory and the Fluent with the method of two-way flow solid coupling. Finally, comparative analysis of the kinetic parameters of cerebral aneurysm before and after implantation, including wall pressure, blood velocity, path line of the blood flow, wall shear stress, wall deformation was conducted, and blood flow characteristics after stent implantation were analyzed under different entrance velocity. RESULTS AND CONCLUSION: After implantation, the wall surface pressure was reduced about 61.1%; the blood flow velocity around the stent and the inside of the cerebral aneurysm was decelerated obviously; under setting 2 000 lines of blood flow, the number of path line of blood flow into the cerebral aneurysm reduced about 75.0%, the maximum wall shear stress decreased about 79.3%, and the maximum wall deformation reduced to a lower level. The entrance velocity was respectively v1=0.1 m/s, v2=0.2 m/s, v3=0.3 m/s and the wall pressure was in a gradient ascent; the wall shear stress increased with the velocity, meanwhile, τzou (left neck of aneurysm) <τzhong (aneurysm )< τyou (right neck of aneurysm). The path lines of blood flow mainly concentrated in the top of the aneurysm, and the blood velocity markedly affected the surface deformation. These results indicate that main hemodynamic parameters are obviously improved after stent implantation into cerebral aneurysm, and the blood velocity should never be neglectful in the treatment process.