动脉分岔血管内膜增生过程的数值模拟

内膜增生从发生到阻塞血管是一个复杂的变化过程,在这个过程中,内膜的增生、血管腔体形状的改变和血流动力学之间是相互影响的。为了研究这些变化,本文提出一种单元填充方法数值模拟了三维颈动脉分岔血管在低切应力作用下血管内膜增生的过程。该方法既可以克服节点移动方法所不可避免的内膜增生的不连续性,也可以避免网格重划分的困难。结果发现,如果单纯以切应力阈值作为内膜增生的判据,低切应力的作用将无法导致血管完全阻塞,但内膜增生和血流动力学之间的相互影响是可以通过数值方法进行模拟的。在本数值模拟中,内膜增生的过程分为"增厚"(先)和"扩展"(后)两个阶段,最大狭窄率为34.4%,发生在距血管分岔5mm处动脉窦的外侧壁面。其发生位置和形状与临床观察吻合。

Numerical simulation of intimal thickening in a bifurcating artery

Intimal thickening is a complicated process from plaque formation to artery-obstructed.In this process,intimal thickening,the change of artery geometry and hemo-dynamics are interacted.A new numerical skill named "Cell-filled method" is applied to simulate the process of intimal thickening in a carotid bifurcation under critical low wall shear stress condition.The new method can overcome the limitation of previous methods,such as the discontinuous of simulation and the trouble of model re-meshing.Results showed that the artery can't be obstructed if the low wall shear stress was chosen as the criterion of intimal thickening,but the interaction among intimal thickening,the change of artery geometry and hemo-dynamics is notable and can be simulated numerically.It was observed numerically that the process of intimal thickening includes two stages of "thickening" and "spreading".The most severe stenosis,which straitness ratio is 34.4%,occurs at the outside wall of sinus and at a distance of 5mm from bifurcation section.The location of intimal thickening and plaque shape are agreed with clinical observation.