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The Prospective Study on the macro-microscopic intra-aneurysmal flow causing the rupture

宏观微观动脉瘤内血流引起破裂的前瞻性研究

基本信息

批准号：
15360101
负责人：
TANISHITA Kazuo
金额：
$ 9.41万
依托单位：
Keio University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15360101/
关键词：
Biomechanics Cerebral aneurysm Prospective study Realistic model Fluid mechanics Risk factor Vessel structure CT画像 LDV PIV 血行力学

项目摘要

Cerebral aneurysms have a variety of complicated shapes, and it greatly influences on blood flow structure. However, it is almost impossible to measure directly in vivo blood flow in detail. Instead, model experiment would be more appropriate to evaluate the detailed flow structure. In our present study, we built anatomically realistic models of cerebral aneurysm, measured detailed flow structure, and discussed the influence of geometric features and blood flow structure of cerebral aneurysms on the rupture.We built realistic cerebral aneurysm models by photoforming method based on computed tomography images. The flow waveform in the parent arteries was completely simulated to the physiological pulsatile flow in cerebral arteries by setting Reynolds number and frequency parameter. We measured velocity profiles with particle image velocimetry and laser Doppler velocimeter.Intra-aneurysmal flow was classified into two patterns. One consists of single circulating flow along the wall, and the other consists of circulating flow and low-velocity recirculating flow in bleb. Ruptured cerebral aneurysm model had the latter flow pattern. Furthermore, wall shear stress had a peak of 5.1 Pa in the ruptured cerebral aneurysms model, which was the highest in the employed models. The recirculating flow and high wall shear stress in bleb seem to be associated with the rupture of cerebral aneurysms, and that was influenced mainly by aspect ratio of aneurysm and neck-parent artery area ratio as a geometric parameter.We also compared the distribution of WSS and the extent of degeneration of arterial wall tissues and suggested that low wall shear stress seen in the local portion of the bifurcation contributed to the degenerative changes followed by formation of cerebral aneurysms.

脑动脉瘤形态复杂，对血流结构影响较大。然而，直接测量体内血流量几乎是不可能的。相反，模型试验更适合用来评价详细的流动结构。在本研究中，我们建立了脑动脉瘤的解剖真实感模型，测量了详细的血流结构，讨论了脑动脉瘤的几何特征和血流结构对破裂的影响，并基于CT图像采用光成型法建立了逼真的脑动脉瘤模型。通过设置雷诺数和频率参数，将载瘤动脉的血流波形完全模拟为脑动脉的生理脉动流。我们用粒子图像测速仪和激光多普勒测速仪测量了血流速度分布。一种是沿壁面的单循环流动，另一种是气泡内的循环流动和低速再循环流动。破裂脑动脉瘤模型为后一种血流模式。此外，破裂脑动脉瘤模型的壁切应力峰值为5.1pA，是所用模型中最高的。脑动脉瘤破裂主要受动脉瘤的长径比和颈-载瘤动脉面积比的影响。我们还比较了WSS的分布和动脉壁组织的退变程度，认为分叉处局部的低壁剪应力是导致脑动脉瘤形成的退行性改变的原因。