Alastruey J, Parker K H, Peiró J, Byrd S M, Sherwin S J
Department of Aeronautics, South Kensington Campus, Imperial College London, SW7 2AZ, UK.
J Biomech. 2007;40(8):1794-805. doi: 10.1016/j.jbiomech.2006.07.008. Epub 2006 Oct 11.
Blood flow in the circle of Willis (CoW) is modelled using the 1-D equations of pressure and flow wave propagation in compliant vessels. The model starts at the left ventricle and includes the largest arteries that supply the CoW. Based on published physiological data, it is able to capture the main features of pulse wave propagation along the aorta, at the brachiocephalic bifurcation and throughout the cerebral arteries. The collateral ability of the complete CoW and its most frequent anatomical variations is studied in normal conditions and after occlusion of a carotid or vertebral artery (VA). Our results suggest that the system does not require collateral pathways through the communicating arteries to adequately perfuse the brain of normal subjects. The communicating arteries become important in cases of missing or occluded vessels, the anterior communicating artery (ACoA) being a more critical collateral pathway than the posterior communicating arteries (PCoAs) if an internal carotid artery (ICA) is occluded. Occlusions of the VAs proved to be far less critical than occlusions of the ICAs. The worst scenario in terms of reduction in the mean cerebral outflows is a CoW without the first segment of an anterior cerebral artery combined with an occlusion of the contralateral ICA. Furthermore, in patients without any severe occlusion of a carotid or VA, the direction of flow measured at the communicating arteries corresponds to the side of the CoW with an absent or occluded artery. Finally, we study the effect of partial occlusions of the communicating arteries on the cerebral flows, which again confirms that the ACoA is a more important collateral pathway than the PCoAs if an ICA is occluded.
使用顺应性血管中压力和血流波传播的一维方程对 Willis 环（CoW）中的血流进行建模。该模型从左心室开始，包括为 CoW 供血的最大动脉。基于已发表的生理数据，它能够捕捉沿主动脉、在头臂干分叉处以及整个脑动脉中脉搏波传播的主要特征。在正常情况下以及在颈内动脉或椎动脉（VA）闭塞后，研究了完整 CoW 的侧支循环能力及其最常见的解剖变异。我们的结果表明，该系统不需要通过交通动脉的侧支途径来充分灌注正常受试者的大脑。在血管缺失或闭塞的情况下，交通动脉变得很重要，如果颈内动脉（ICA）闭塞，前交通动脉（ACoA）比后交通动脉（PCoA）是更关键的侧支途径。事实证明，VA 闭塞的严重性远低于 ICA 闭塞。就平均脑血流量减少而言，最糟糕的情况是 CoW 没有大脑前动脉的第一段并伴有对侧 ICA 闭塞。此外，在没有任何颈内动脉或 VA 严重闭塞的患者中，在交通动脉处测量的血流方向与 CoW 中动脉缺失或闭塞的一侧相对应。最后，我们研究了交通动脉部分闭塞对脑血流的影响，这再次证实，如果 ICA 闭塞，ACoA 是比 PCoA 更重要的侧支途径。
