Ferrández A, David T, Bamford J, Scott J, Guthrie A
School of Mechanical Engineering, The University of Leeds, Leeds, UK.
Comput Methods Biomech Biomed Engin. 2000;4(1):1-26. doi: 10.1080/10255840008907996.
A two-dimensional, steady state model of the circle of Willis has been developed. To simulate the peripheral resistance of the cerebrovascular tree, blocks of porous media were used. Their effective resistance was kept constant, disregarding the effects of arterial auto-regulation. The model was then used to simulate different common abnormalities of the circle of Willis while a range of varying boundary conditions was imposed to the right internal carotid artery (ICA). The total flux was tabulated and compared favourably with both clinical measurements and other models of the circle of Willis. Relevant fluid dynamics effects were also observed and analysed. The present model demonstrates that the use of CFD can produce physiological results if the appropriate boundary conditions are used. We can provide clinicians with a priority list of the severity of the flux reduction for the considered abnormalities for different degrees of stenosis of the right ICA. From this study it is apparent that the redistribution of blood via the circle of Willis is mainly driven by changes in the vascular resistance of the brain rather than in the local arterial geometry. The use of valid peripheral resistances allows for a more realistic model of the circle of Willis but also highlights the need for more accurate means to estimate the vascular resistance of a patient.
已经建立了 Willis 环的二维稳态模型。为了模拟脑血管树的外周阻力，使用了多孔介质块。在忽略动脉自身调节作用的情况下，其有效阻力保持恒定。然后，在对右侧颈内动脉（ICA）施加一系列不同边界条件的同时，使用该模型模拟 Willis 环的不同常见异常情况。对总流量进行了列表，并与临床测量结果以及 Willis 环的其他模型进行了良好的比较。还观察和分析了相关的流体动力学效应。本模型表明，如果使用适当的边界条件，计算流体动力学（CFD）的应用可以产生生理学结果。对于右侧 ICA 不同程度的狭窄，我们可以为临床医生提供一份关于所考虑异常情况下流量减少严重程度的优先级列表。从这项研究中可以明显看出，通过 Willis 环的血液重新分布主要是由脑血管阻力的变化驱动的，而不是局部动脉几何形状的变化。使用有效的外周阻力可以建立更真实的 Willis 环模型，但也突出了需要更准确的方法来估计患者血管阻力的必要性。
