[Hemodynamic analyses of large intracranial aneurysms].

OBJECTIVE: To simulate the computational hemodynamics of large intracranial aneurysms and analyze the hemodynamics of three types of large intracranial aneurysms. METHODS: A total of 32 patient-specific models of large intracranial aneurysms were constructed with the data of DSA (digital subtraction angiography). According to the location of outflow vessel, plane of main vortex and impact zone, large intracranial aneurysms were classified into type A (outflow vessel in the plane of main vortex), type B1 (outflow vessel out of plane of main vortex, impact zone at the lateral wall of aneurysm) and type B2 (outflow vessel out of plane of main vortex, impact zone at the dome of aneurysm). Blood flow was assumed to be laminar and incompressible and blood Newtonian fluid. The time-dependent pulsatile boundary condition was deployed at inlet. CFD ICEM and Fluent software packages were used to simulate the computational hemodynamics of large intracranial aneurysms. RESULTS: The distributions of hemodynamic variables during the cardiac cycle were analyzed for wall shear stress, velocity and streamlines. The velocity ratio (ratio of aneurysmal flow velocity to parent artery flow velocity) of type A, B1 and B2 was 0.186 ± 0.019, 0.706 ± 0.077 and 0.208 ± 0.041 respectively. The wall shear stress ratio (ratio of aneurysmal wall shear stress to parent artery wall shear stress) of types A, B1 and B2 was 0.081 ± 0.029, 1.019 ± 0.139 and 0.103 ± 0.031 respectively. The flow velocity and wall shear stress were the highest in type B1 group, followed by those in type B2 group and the lowest in type A group. CONCLUSION: As reflected by the location of impact zone, the location of outflow vessel and inflow-angle can influence the level of blood flow in aneurysm sac.