Computational hemodynamics and hemoacoustic study on carotid bifurcation: Effect of stenosis and branch angle

Abstract

Investigation of sound-signal-based noninvasive diagnosis of arterial stenosis is an active area of research. This study focuses on computational investigation of hemodynamic and hemoacoustic parameters within the carotid bifurcation. The objective is to analyze the effect of 40 distinct geometric configurations on indicative sound signals, useful for understanding the feasibility of stethoscope-based diagnosis of stenosis. The study employs an in-house flow-solver based on the semi-implicit pressure-projection method on a curvilinear grid. Physiological condition-based pulsatile flow waveforms and three-element Windkessel model-based pressure are utilized at the inlet and outlets of the bifurcating carotid artery. The research involves assessment of parameters like wall shear stress (WSS) and integrated pressure force rate (IPFR) fast Fourier transform (FFT) spectrum. Geometric configurations are varied based on stenosis level S (0, 45%, 60%, and 70%), bifurcation angle BA (30°, 40°, 50°, and 65°), and length of stenosis L (1, 1.5, and 2). In the investigated geometries, WSS exhibits a distinct behavior, reaching a peak at stenosis and subsequently transitioning to a negative value. Furthermore, IPFR-spectrum analysis reveals distinguishable frequencies for S≥ 40%, hinting at the potential for stethoscope-based diagnosis. A novel correlation between the cutoff frequencies of IPFR FFT-spectrum and arterial geometry is established, which reflect the influence of artery geometry on sound signals. Computational fluid dynamics (CFD)-based flow-visualization approach is proposed to calculate characteristic frequencies, which are close to IPFR spectrum frequencies. Our study contributes to a framework for potential sound-based classification of plaque-induced constrictions.