Spectral Decomposition of the Flow and Characterization of the Sound Signals through Stenoses with Different Levels of Severity

Abstract

Treatments of atherosclerosis depend on the severity of the disease at the diagnosis time. Non-invasive diagnosis techniques, capable of detecting stenosis at early stages, are essential to reduce associated costs and mortality rates. We used computational fluid dynamics and acoustics analysis to extensively investigate the sound sources arising from high-turbulent fluctuating flow through stenosis. The frequency spectral analysis and proper orthogonal decomposition unveiled the frequency contents of the fluctuations for different severities and decomposed the flow into several frequency bandwidths. Results showed that high-intensity turbulent pressure fluctuations appeared inside the stenosis for severities above 70%, concentrated at plaque surface, and immediately in the post-stenotic region. Analysis of these fluctuations with the progression of the stenosis indicated that (a) there was a distinct break frequency for each severity level, ranging from 40 to 230 Hz, (b) acoustic spatial-frequency maps demonstrated the variation of the frequency content with respect to the distance from the stenosis, and (c) high-energy, high-frequency fluctuations existed inside the stenosis only for severe cases. This information can be essential for predicting the severity level of progressive stenosis, comprehending the nature of the sound sources, and determining the location of the stenosis with respect to the point of measurements.

Data-Driven Discovery of Anomaly-Sensitive Parameters from Uvula Wake Flows Using Wavelet Analyses and Poincaré Maps

“…The observation that the anomaly sensitivity differs among probe sites provides an opportunity to use multiple probes in a synergic way to localize the source or quantify the source severity. A similar concept has also recently been pursued by Khalili et al, who characterized sound signals through stenosis using spectral decomposition, with the aim to localize the stenosis with points of measurement [70].…”

Advances in Multivariate and Multiscale Physiological Signal Analysis

“…In the early diagnosis of stenosis, a comprehensive study of acoustic pressure, flow fluctuations, and sound features related to stenosis progression was reported in [ 24 ]. The authors highlighted a relevant relationship between the severity level of stenosis progression and the frequency content of high-turbulence pressure fluctuations.…”