Pulsatile Flow Effects on the Hemodynamics of Intracranial Aneurysms
Pulsatile Flow Effects on the Hemodynamics of Intracranial Aneurysms
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DOI：
10.1115/1.4002702
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发表时间：
2010-11-01
影响因子：
1.7
通讯作者：
Sotiropoulos, Fotis
中科院分区：
文献类型：
--
作者：
Le, Trung B.;Borazjani, Iman;Sotiropoulos, Fotis
采用高分辨率数值模拟方法，系统研究了来流波形对解剖侧壁颅内动脉瘤模型血流动力学和壁面切应力模式的影响。通过适当地缩放典型的人体波形来构造各种波形，使得波形最大值和时间平均雷诺数、Womersley数（α）和脉动指数（PI）在人体生理范围内系统地变化。我们表明，波形PI是支配动脉瘤颈部的涡流动力学和圆顶内的流动模式的关键参数。在低PI下，圆顶中的流动类似于驱动腔流动，其特征在于准静态剪切层，该剪切层从圆顶内的再循环流动中描绘出载瘤动脉流动。另一方面，在高PI下，血流主要由涡环形成、穿过瘤颈的输送以及动脉瘤圆顶远端壁处的冲击和破裂所控制。我们进一步表明，动脉瘤圆顶上的壁面剪切应力场的空间和时间特征与颈部的涡旋动力学密切相关。最后，我们认为，之间的比率的平均流量通过颈部和涡环形成的时间尺度的运输的特征时间尺度可以用来预测一个给定的侧壁动脉瘤模型的临界值的波形PI的血液动力学将从腔模式过渡到涡环模式。[DOI 10.1115/1.4002702]
High-resolution numerical simulations are carried out to systematically investigate the effect of the incoming flow waveform on the hemodynamics and wall shear stress patterns of an anatomic sidewall intracranial aneurysm model. Various wave forms are constructed by appropriately scaling a typical human waveform such that the waveform maximum and time-averaged Reynolds numbers, the Womersley number (alpha), and the pulsatility index (PI) are systematically varied within the human physiologic range. We show that the waveform PI is the key parameter that governs the vortex dynamics across the aneurysm neck and the flow patterns within the dome. At low PI, the flow in the dome is similar to a driven cavity flow and is characterized by a quasi-stationary shear layer that delineates the parent artery flow from the recirculating flow within the dome. At high PI, on the other hand, the flow is dominated by vortex ring formation, transport across the neck, and impingement and breakdown at the distal wall of the aneurysm dome. We further show that the spatial and temporal characteristics of the wall shear stress field on the aneurysm dome are strongly correlated with the vortex dynamics across the neck. We finally argue that the ratio between the characteristic time scale of transport by the mean flow across the neck and the time scale of vortex ring formation can be used to predict for a given sidewall aneurysm model the critical value of the waveform PI for which the hemodynamics will transition from the cavity mode to the vortex ring mode. [DOI:10.1115/1.4002702]