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Research on Optimum Design of Stent Used for Interventional Treatment Apparatus of Aneurysms

动脉瘤介入治疗器械支架优化设计研究

基本信息

批准号：
14580838
负责人：
BANDO Kiyoshi
金额：
$ 2.3万
依托单位：
Kansai University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

For the purpose of optimum design of stent used for the treatment of aneurysms, numerical simulations were performed to obtain the design criterion. Saccular aneurysm was chose as a model aneurysm and stent was located in the parent artery at the neck of the aneurysm. Then, the speed of blood flow in the aneurysm decreases and it is expected that thrombus generates on the inner wall of aneurysm, resulting in hardening of the aneurysm wall and prevention of aneurysm growth and rupture. The following results were obtained from the calculation results. (1)When the flow becomes maximum in the aneurysm, it enters the aneurysm from upstream side of the aneurysm neck, flows along the inner wall of the aneurysm, and discharges from downstream side of aneurysm neck. (2)The pressure in the aneurysm becomes almost uniform, but the pressure pulsates with time having average the value of upstream and downstream sides of the aneurysm. (3)The driving forces of flow in the aneurysm is pressure differe … More nce between upstream and downstream sides in the aneurysm and momentum of flow in the boundary layer of the parent artery which impinges on the stent filaments and then deflects from axial to radial direction. (4)The generation of the thrombus can be judged based on the wall shear rate of the blood flow. In order to check the effectiveness of the placement of the stent, flow measurement near the stent filaments and in the aneurysm is necessary. We have developed cathetertype LDV-sensor having 100μ m in outer diameter for measuring the local blood flow velocity in blood vessels. By inserting this sensor across the stent into the aneurysm, it is possible to measure the local flow velocity in the aneurysm. Numerical simulation of flow around this sensor was performed to estimate measurement error due to the existence of the sensor in the flow field which is to be measured. Furthermore, it is known that the blood viscosity increases in the region where the flow velocity is low. This is due to non-Newtonian rheological behavior of the blood in the low flow region. Therefore, in order to estimate the effect of the stent with high accuracy, accurate modeling of the rheology of blood flow is necessary by solving the coupled problem between the deformation of the red blood cell and plasma flow around it. A coupled analysis by using immersed boundary method was proposed and the effectiveness of the method was confirmed by numerical simulations. Less

为了优化动脉瘤支架的设计，对支架进行了数值模拟，得到了支架的设计准则。选择囊状动脉瘤作为模型动脉瘤，支架位于载瘤动脉瘤颈处。然后，动脉瘤中的血流速度降低，并且预期在动脉瘤的内壁上产生血栓，导致动脉瘤壁硬化并防止动脉瘤生长和破裂。从计算结果中获得以下结果。（1）在动脉瘤内流量达到最大时，从动脉瘤颈的上游侧进入动脉瘤内，沿着动脉瘤的内壁流动，从动脉瘤颈的下游侧排出。（2）动脉瘤内的压力变得几乎均匀，但压力随着时间脉动，使动脉瘤的上游侧和下游侧的值平均。（3）动脉瘤内的流动动力是压力差， ...更多信息动脉瘤中上游侧和下游侧之间的动量以及载瘤动脉边界层中的流动动量，该流动动量冲击支架细丝，然后从轴向偏转到径向。（4）根据血流的壁面剪切率可以判断血栓的产生。为了检查支架放置的有效性，必须测量支架细丝附近和动脉瘤内的流量。我们研制了外径为100μ m的导管式LDV传感器，用于测量血管中局部血流速度。通过将该传感器穿过支架插入动脉瘤中，可以测量动脉瘤中的局部流速。对该传感器周围的流场进行了数值模拟，以估计由于传感器存在于待测流场中而引起的测量误差。此外，已知血液粘度在流速低的区域中增加。这是由于血液在低流量区域中的非牛顿流变行为。因此，为了更准确地评估支架的效果，需要通过求解红细胞变形与血浆流动之间的耦合问题，对血液流变学进行精确建模，提出了一种基于浸入边界法的耦合分析方法，并通过数值模拟验证了该方法的有效性。少