动脉瘤的血流动力学数值模拟初步分析

目的数值模拟分析动脉瘤的血流压力、速度和切应力3个指标特点,探讨动脉瘤生长、破裂的可能机制。方法采用动脉瘤的医学影像结合计算流体力学(CFD)软件,对动脉瘤内血液流动进行数值模拟。结果 (1)流场压力呈周期性变化,压力剧烈变化的时间窗为0～0．62T,与速度剧烈变化时间窗一致,动脉瘤内各处压力周期变化与流场的周期变化一致,每一个具体的时刻流场压力分布不均衡;(2)脉动状态下,每个心动周期里,在0 ～0．4T内,速度变化最剧烈,在动脉分叉处形成涡运动,通过瘤颈进入动脉瘤内时,血流速度骤减,在动脉瘤中央形成涡,速度逐渐减小并可能静止,瘤顶血流速度很小甚至静止;(3)动脉瘤内,整个心动周期里切应力几乎都在迅速的变化,与血流速度的急剧变化的时间一致,切应力存在于瘤颈,瘤壁为零。结论 3个指标(压力、速度、切应力) 是导致瘤颈内皮损伤、瘤生长、扩大的重要危险因子。数值模拟能较好反映动脉瘤血液流动过程,能够帮助认识动脉瘤的病理生理机制和指导临床治疗。

Heamodynamic numerical simulation analysis of intracranial aneurysms

Objective To investigate the hemodynamic characteristics of intracranial aneurysms and analysis the possible mechanisms of growth and rupture of intracranial aneurysms. Methods Some images of intracranial a-neurysms were handled by some image processing software. The profile meshed by some computational fluid dynamics (CFD) software were used to simulate the flow. Results From the beginning to the 0. 62T in every cardiac cycle,the pressure has a sharp change. And this time was coincidence with the time velocity acutely changes. The periodical change of pressure in aneurysm was consistent to the pressure change of whole flow field. At any moment ,the pressure was not the same in whole flow field. The pressure had a remarkable change. And this time was coincidence with the time velocity acutely changes. The periodical change of pressure in aneurysm was consistent to the pressure change of whole flow field. At any moment,the pressure was not the same in whole flow field. The wall shear stress of aneurysm had a quite sharp change in a whole cardiac cycle and it had a acute change during the period of 0~0. 55T. This time is coincidence with the time velocity acutely changes. The wall shear stress exited in the neck of aneurysm,not in the wall of aneurysm. Conclusion The three indexs (pressure, velocity, wall shear stress) is risk factors which will make the aneurysm rupture. CFD simulation is good for comprehending hemodynamic and pathophysiological mechanisms as well as clinical treatment of intracranial aneurysms.