颈内动脉狭窄致Willis环代偿功能失效的血流动力学机理研究

Willis circle is an important physical structure for preventing cerebral ischemia. However, in patients with internal carotid artery (ICA) stenosis, the incidence of stroke caused by cerebral ischemia is high, indicating the compensatory ability of Willis circle is invalidated in part of these patients. The mechanism study on the invalidation of compensatory ability has important implications for preventing the occurence of stroke. The reasons are inferred as follow: the variability of structure and compensatory ability of Willis circle may differ between the normal and patients with ICA stenosis; the compensatory ability is weakened with the development of ICA stenosis; the collateral circulation of Willis circle may influence the hemodynamics in ICA, and further intensify the stenosis. Aiming at the three possible reasons, the study includes: 1. based on clinical image of Willis circle, assessing the variability of the structure and compensatory ability of Willis circle between the normal and patients with ICA stenosis; 2. evaluating the variation of compensatory ability with lumped parameter model of Willis circle during the development process of ICA stenosis; 3. building the multi-scale model with the coupling between lumped parameter of Willis circle and 3D hemodynamics in ICA, to study the effect of collateral circulation of Willis circle on the development of ICA stenosis. It is the innovation of the study that considering the interaction between the compensatory ability of Willis circle and the development of ICA stenosis, which may provide new ideas for controlling of the development of stenosis.

Willis环是预防脑缺血的重要生理结构。颈内动脉狭窄的病人中，脑缺血导致的脑卒中发病率很高，说明Willis环的代偿功能在部分病人中失效了。研究其失效的机理对于预防脑卒中具有重要意义。推测其原因有：颈内动脉狭窄病人与正常人的Willis环结构及功能变异性存在差异；Willis环代偿功能随狭窄的发展而减弱；Willis环的侧支循环可能会影响颈内动脉的血流动力学，加剧狭窄的发展。本项目针对上述可能原因开展研究：基于临床Willis环影像，评估颈内动脉狭窄病人与正常人的Willis环结构及功能变异性的差异；用Willis环的集中参数模型评价其代偿功能在狭窄发展过程中的变化；建立Willis环集中参数和颈内动脉三维血流动力学耦合的多尺度模型，研究Willis环侧支循环对狭窄发展的影响。本项目的创新之处在于研究了Willis环代偿功能与颈内动脉狭窄发展的相互影响，为控制狭窄的发展提供新的思路。

Willis环是预防脑缺血的重要生理结构。颈内动脉狭窄的病人中，脑缺血导致的脑卒中发病率很高，说明Willis的代偿功能在部分病人中失效了。研究其失效的机理对于预防脑卒中具有重要意义。本课题完成了90例样本的脑动脉MR临床数据采集，其中包括颈内动脉狭窄样本75例，正常样本15例，构建了个性化的三维Willis环几何模型，并分析了它们的流场特点；构建了集中参数模型，对Willis环在颈内动脉狭窄病人中的代偿功能进行了模拟，揭示了不同结构Willis环的代偿功能随颈内动脉狭窄发展的变化规律；研究了外周动脉压力脉搏波的采集方法，以及压力脉搏波波形与头颈部动脉狭窄的相关性，初步探索了利用外周压力脉搏波进行头颈部狭窄检测的技术和设备。工作发表论文5篇，另有2篇论文已投出，申请专利4项，其中1项已获得授权。上述研究阐明了Willis环结构的重要性，可为颈内动脉狭窄患者治疗方案的制定提供指导。