Asymmetrical oscillation of a bubble confined inside a micro pseudoelastic blood vessel and the corresponding vessel wall stresses
Asymmetrical oscillation of a bubble confined inside a micro pseudoelastic blood vessel and the corresponding vessel wall stresses
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DOI：
10.1016/j.ijsolstr.2007.04.005
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发表时间：
2007-11-01
影响因子：
3.6
通讯作者：
Hu, Hongping
中科院分区：
文献类型：
--
作者：
Gao, Farong;Hu, Yuantai;Hu, Hongping
本文详细研究了初始半径与气泡相当的可变形伪弹性容器内微气泡的不对称振荡。与无约束环境下的对称振荡不同，在伪弹性容器约束下的振荡气泡逐渐从球体变成椭球体（这被称为不对称效应），并导致血管壁内的应力大大增加。考虑了惯性效应、周向刚度和预存血压对气泡不对称振荡的影响。计算结果表明，容器壁周向刚度越大，容器壁内应力幅值越大，频率越高，其中应力幅值和相关频率是确定循环加载破坏事件的两个最主要参数，这在材料科学界是众所周知的。在容器壁厚度减小的情况下，以及在填充容器的液体中增加预先存在的压力的情况下，也得到了类似的结果。这些结论支持了这样一种观点，即不对称效应是那些血管壁较薄（如毛细血管和小血管）的临床损伤的主要机制之一，也是老年人和高血压患者在冲击波碎石和其他涉及冲击波的医疗程序（如超声辅助胶囊化药物递送）中风险较高的主要机制之一。(C) 2007 Elsevier Ltd.版权所有。
Asymmetrical oscillation of a micro-bubble confined inside a deformable pseudoelastic vessel with comparable initial radius with the bubble is studied in detail. Unlike the symmetric oscillation in an unconstrained environment, the oscillating bubble under the constraint of a pseudoelastic vessel gradually becomes as an ellipsoid from a sphere (this is called asymmetrical effect), and leads to substantially larger stresses within the vessel wall. Influence of inertial effect, circumferential stiffness and pre-existing blood pressure on bubble's asymmetrical oscillation are taken into account in the paper. Computational results show that a vessel wall with larger circumferential stiffness corresponds to larger stress amplitude with higher frequency within the wall, where the stress amplitude and the pertinent frequency are the two most dominating parameters in determining the failure event under cyclic loading, as well known in the community of materials science. Similar results have been obtained for the case of decreasing in thickness of vessel walls, and for the case of increasing pre-existing pressure in the liquid filling the vessel. These conclusions support the notion that the asymmetric effect is one of the primary mechanisms for the clinical injuries of those with thinner vessel walls, such as capillary and small blood vessels, and for the higher risk of elder and hypertension patients in the shock-wave lithotripsy and other medical procedures involving shock waves, such as ultrasound-assisted encapsulated drug delivery. (C) 2007 Elsevier Ltd. All rights reserved.