Feng Yixiang, Wada Shigeo, Tsubota Ken-Ichi, Yamaguchi Takami
Dept. of Bioeng. & Robotics, Tohoku Univ., Sendai.
Conf Proc IEEE Eng Med Biol Soc. 2005;2006:607-10. doi: 10.1109/IEMBS.2005.1616486.
Hemodynamic stresses are known to degenerate the arterial wall and be involved in the pathogenesis of intracranial aneurysm formation and development. The present study simulates the formation and growth of aneurysms by focusing on the interplay between the wall shear stress, degeneration of the mechanical wall properties, and the wall deformation. We construct numerical aneurysm models arisen from both straight and curved arteries, and we hypothesize that high local wall shear stress larger than a certain threshold value will lead to a linear decrease in the mechanical property of the vessel wall. The degeneration of vessel wall leads to wall deformation and redistribution of the wall shear stress, which in turn leads to further degeneration of the wall. Development of aneurysm is observed in both the straight and curved models. In the straight model, the growth of aneurysm is small and mainly at the distal neck region, and the aneurysm stops growing after several steps. In contrast, in the curved model, the aneurysm continues to grow in height and width. Our computer simulation shows that even if the wall shear stress inside a saccular aneurysm is low, aneurysm development can occur due to degeneration of the wall distal and proximal to the aneurysm. The interaction between the geometry change and the wall degeneration is key to the development of aneurysms. The method demonstrates the potential utility of model-based numerical methods in the investigation of developmental biology of intracranial aneurysms.
已知血流动力学应力会使动脉壁退化，并参与颅内动脉瘤形成和发展的发病机制。本研究通过关注壁面剪应力、机械壁特性退化和壁面变形之间的相互作用，模拟了动脉瘤的形成和生长。我们构建了由直管和弯管产生的数值动脉瘤模型，并假设高于某个阈值的高局部壁面剪应力将导致血管壁机械性能呈线性下降。血管壁的退化导致壁面变形和壁面剪应力的重新分布，进而导致壁面进一步退化。在直管和弯管模型中均观察到动脉瘤的发展。在直管模型中，动脉瘤的生长较小，主要发生在远端颈部区域，经过几步后动脉瘤停止生长。相比之下，在弯管模型中，动脉瘤在高度和宽度上持续生长。我们的计算机模拟表明，即使囊状动脉瘤内的壁面剪应力较低，由于动脉瘤远端和近端壁面的退化，仍可能发生动脉瘤发展。几何形状变化与壁面退化之间的相互作用是动脉瘤发展的关键。该方法证明了基于模型的数值方法在颅内动脉瘤发育生物学研究中的潜在效用。
