A Computational Method for Analyzing the Biomechanics of Arterial Bruits

Abstract

A computational framework consisting of a one-way coupled hemodynamic-acoustic method and a wave-decomposition based postprocessing approach is developed to investigate the biomechanics of arterial bruits. This framework is then applied for studying the effect of the shear wave on the generation and propagation of bruits from a modeled stenosed artery. The blood flow in the artery is solved by an immersed boundary method (IBM) based incompressible flow solver. The sound generation and propagation in the blood volume are modeled by the linearized perturbed compressible equations, while the sound propagation through the surrounding tissue is modeled by the linear elastic wave equation. A decomposition method is employed to separate the acoustic signal into a compression/longitudinal component (curl free) and a shear/transverse component (divergence free), and the sound signals from cases with and without the shear modulus are monitored on the epidermal surface and are analyzed to reveal the influence of the shear wave. The results show that the compression wave dominates the detected sound signal in the immediate vicinity of the stenosis, whereas the shear wave has more influence on surface signals further downstream of the stenosis. The implications of these results on cardiac auscultation are discussed.

Computational Modeling and Analysis of Murmurs Generated by Modeled Aortic Stenoses

“…Zhu et al [11] already demonstrated through a classic vector decomposition that the shear waves had a significant impact on the spectra of the murmurs and acoustic energy distribution on the epidermal surface, and inclusion of this effect in our study should lead to more realistic modeling of murmur propagation.…”

“…5) that the outlet of the aorta is not a source location. Also, based on the previous study [10,11], compression waves are convenient for predicting the source location due to its long wave length and better directionality.…”

“…The understanding of the causal mechanism(s) can be facilitated by studying the coupled physics of hemodynamics and elastic wave propagation that are implicated in the generation and propagation of the murmurs. The generation of stenosis related murmurs has been studied extensively [1,[10][11][12][13], where it was concluded that the murmurs were generated by the abnormal pressure fluctuations at the vessel wall.…”

“…The propagation of the elastic waves inside the body, which is the focus of this paper, has also been studied by many researchers [4,10,11,[14][15][16]. Previous studies focused mainly on two aspects of the murmurs.…”

A Coupled CFD-FEA study of the Sound Generated in a Stenosed Artery and Transmitted Through Tissue Layers

“…Thus, virtual Echocardiography (ECHO) and Phonocardiography (PCG) can *Corresponding author. C serve as a bridge between clinical data and computational hemodynamic results [27,28]. These virtual ECHO and PCG can be used for rapid validation of computational results by comparing to the actual cardiographic data, and furthermore, such comparisons will allow us to calibrate a given patientspecific, computational heart model.…”