Computational Modeling and Analysis of Murmurs Generated by Modeled Aortic Stenoses

Abstract

In this study, coupled hemodynamic–acoustic simulations are employed to study the generation and propagation of murmurs associated with aortic stenoses where the aorta with a stenosed aortic valve is modeled as a curved pipe with a constriction near the inlet. The hemodynamics of the poststenotic flow is investigated in detail in our previous numerical study (Zhu et al., 2018, “Computational Modelling and Analysis of Haemodynamics in a Simple Model of Aortic Stenosis,” J. Fluid Mech., 851, pp. 23–49). The temporal history of the pressure on the aortic lumen is recorded during the hemodynamic study and used as the murmur source in the acoustic simulations. The thorax is modeled as an elliptic cylinder and the thoracic tissue is assumed to be homogeneous, linear and viscoelastic. A previously developed high-order numerical method that is capable of dealing with immersed bodies is applied in the acoustic simulations. To mimic the clinical practice of auscultation, the sound signals from the epidermal surface are collected. The simulations show that the source of the aortic stenosis murmur is located at the proximal end of the aortic arch and that the sound intensity pattern on the epidermal surface can predict the source location of the murmurs reasonably well. Spectral analysis of the murmur reveals the disconnect between the break frequency obtained from the flow and from the murmur signal. Finally, it is also demonstrated that the source locations can also be predicted by solving an inverse problem using the free-space Green's function. The implications of these results for cardiac auscultation are discussed.

A 3D scaling law for supravalvular aortic stenosis suited for stethoscopic auscultations

“…10 . For high stenosis, the flow is dominated by a jet emanating from the stenotic region, consistent with the literature (Zhu et al [57] , [55] ). This jet-dominated flow renders a distinction between the evolving vortical structures rather difficult across the modeled domain.…”

“…The analysis of simulated bruits was elaborated on in several other computational studies (e.g., Tse et al [54] , Zhu et al [55] , and Bailoor et al [26] ). All these studies rely on the concept of the break frequency , i.e., a frequency that marks a sudden change in spectral power trends, consistent with in-vitro and clinical phonoangiography.…”

Cardiovascular fluid dynamics: a journey through our circulation

“…2013). The flow through asymmetrically calcified or stenosed valves has been shown to develop into a jet that impinges on the aortic wall, where the curvature of the aortic arch introduced helical Dean vortex flows, intermittent turbulent stresses and audible sounds called murmurs (Zhu, Seo & Mittal 2018, 2019; Bailoor et al. 2021).…”

Computational Methods for Fluid-Structure Interaction Simulation of Heart Valves in Patient-Specific Left Heart Anatomies

“…Doctors have been using stethoscopes to diagnose heart diseases because abnormal heart sounds are associated with various conditions [143]. This association has motivated the study of the sound generation process (acoustics) [144] in valvular murmurs. Furthermore, attempts have been made to couple electro-mechanical models of heart tissues with blood flows [7,31].…”