The Image And Curve Analysis Of Hemodynamic Numerical Simulation Of Intracranial Aneurysms And Its Clinical Significance

Objective To investigate the hemodynamic characteristics of intracranial aneurysms and analysis the possible mechanism of growth and rupture of intracranial aneurysms by numerical simulation.Methods Some images of experimental terminal and lateral aneurysms are handled by some image processing software such as Photoshop , Matlab, Gambit and so on . The profiles meshed by some computational fluid dynamics software (Gambit and Fluent) are used to simulate the blood flow.Results Vertex flow comes to form across the inlet at the bifurcation of terminal aneurysms and the neck of lateral aneurysms in unsteady condition. The blood velocity decreases and comes into be nearly stagnant when it across the aneurysm neck and vortex comes into being inside aneurysm. And it is very slow and sometime its value is near zero at the distal end of aneurysm. The wall shear stress formed under the impact of blood flow is most prominent in the neck of aneurysms than other locations and is weak in the aneurismal wall. Its direction is changed. The pressure at the distal end is higher than other location in terminal aneurysm. But it is the lower than the neck and parent artery in lateral aneurysms. At any moment, the pressure is not the same in whole flow field. The blood velocity , wall shear stress and pressure are all have a sharp change at the period of the beginning to the 0.55T in every cardiac cycle. Their change is simultaneous.Conclusion The blood velocity , wall shear stress and pressure are the risk factors for the growth and rupture of aneurysms. The rupture always happens in the distal end of aneurysms but the blood velocity is very slow at the location. Maybe the aneurismal wall oscillation lead to rupture. The wall shear stress is most prominent in the neck of aneurysms which injures the endothelium of the neck of aneurysm and the aneurysm grows. The pressure in inside is higher than the neck and parent vessel in terminal aneurysm and it has a acute change in 0-0.55T which may lead to rupture. In the same condition the pressure is higher in terminal aneurysms than lateral aneurysms. So the former is more possible to rupture. During the period of 0-0.55T, the blood velocity , wall shear stress and pressure all have a sharp and simultaneouschange in every cardiac cycle. So this period is a risk time window for aneurysm growth and rupture.