Tubaldi Eleonora, Païdoussis Michael P, Amabili Marco
Mem. ASME Department of Mechanical Engineering, McGill University, Macdonald Engineering Building, 817 Sherbrooke Street West, Montreal, QC H3A 0C3, Canada e-mail: .
Professor Fellow ASME Department of Mechanical Engineering, McGill University, Macdonald Engineering Building, 817 Sherbrooke Street West, Montreal, QC H3A 0C3, Canada e-mail: .
J Biomech Eng. 2018 Jun 1;140(6). doi: 10.1115/1.4039284.
This study addresses the dynamic response to pulsatile physiological blood flow and pressure of a woven Dacron graft currently used in thoracic aortic surgery. The model of the prosthesis assumes a cylindrical orthotropic shell described by means of nonlinear Novozhilov shell theory. The blood flow is modeled as Newtonian pulsatile flow, and unsteady viscous effects are included. Coupled fluid-structure Lagrange equations for open systems with wave propagation subject to pulsatile flow are applied. Physiological waveforms of blood pressure and velocity are approximated with the first eight harmonics of the corresponding Fourier series. Time responses of the prosthetic wall radial displacement are considered for two physiological conditions: at rest (60 bpm) and at high heart rate (180 bpm). While the response at 60 bpm reproduces the behavior of the pulsatile pressure, higher harmonics frequency contributions are observed at 180 bpm altering the shape of the time response. Frequency-responses show resonance peaks for heart rates between 130 bpm and 200 bpm due to higher harmonics of the pulsatile flow excitation. These resonant peaks correspond to unwanted high-frequency radial oscillations of the vessel wall that can compromise the long-term functioning of the prosthesis in case of significant physical activity. Thanks to this study, the dynamic response of Dacron prostheses to pulsatile flow can be understood as well as some possible complications in case of significant physical activity.
本研究探讨了目前用于胸主动脉手术的编织涤纶人工血管对搏动性生理血流和压力的动态响应。该假体模型采用非线性诺沃日洛夫壳体理论描述的圆柱形正交各向异性壳体。血流被建模为牛顿脉动流，并考虑了非定常粘性效应。应用了适用于具有波动传播的开放系统、受脉动流作用的流固耦合拉格朗日方程。血压和速度的生理波形用相应傅里叶级数的前八个谐波近似。考虑了两种生理条件下人工血管壁径向位移的时间响应：静息状态（60次/分钟）和高心率状态（180次/分钟）。虽然60次/分钟时的响应再现了脉动压力的行为，但在180次/分钟时观察到更高谐波频率的贡献改变了时间响应的形状。频率响应显示，由于脉动流激励的更高谐波，心率在130次/分钟至200次/分钟之间时出现共振峰。这些共振峰对应于血管壁不必要的高频径向振荡，在剧烈体力活动时可能会损害假体的长期功能。通过这项研究，可以了解涤纶假体对脉动流的动态响应以及剧烈体力活动时可能出现的一些并发症。
