The cervical bruit: Sound spectral analysis related to severity of carotid arterial disease

Abstract

Summary:Cervical bruits may signal the presence of highgrade narrowing of arterial supply to the brain. Previous small studies have suggested that severe arterial stenosis may produce bruits that persist longer and contain a greater proportion of higher-frequency sound spectral components. This study included 96 patients referred for duplex/Doppler testing after cervical bruits had been detected. With the use of a stethoscope equipped with wireless communication to an ordinary handheld computer, we recorded these bruits, analyzed peak sound frequencies and the durations of sound persistence ≥ 200 Hz, and correlated them with Doppler velocities. Overall, the durations and peak frequencies within the bruits correlated significantly with the peak Doppler derived velocities, that is, severity of arterial obstruction. In the presence of high-grade arterial stenosis (peak Doppler velocity ≥ 200 cm/s), bruits regularly possessed either high peak frequencies or prolonged signal durations with a sensitivity approaching 90%. Bruits containing lower and nonsustained peak frequencies were uncommonly associated with severe arterial obstruction. Only well-transmitted bruits with frequencies reaching 200 Hz could be analyzed satisfactorily. In conclusion, we confirm earlier observations that peak frequencies and duration of arterial bruits correlate significantly with severity of underlying arterial obstruction. Equipment used is inexpensive, convenient, and portable. This method provides an objective means for confirming and quantifying subjective auditory impressions of bruits gained at the bedside. It can provide assistance in selecting patients for further testing and as a means for serial followup of individuals with known disease.

An in vitro acoustic analysis and comparison of popular stethoscopes

“…The full spectrum pink noise samples were divided into frequency ranges derived from the literature5–24 to assess the performance of each stethoscope for specific clinical conditions (Table 2). To accomplish this, BIO and AMB recordings were duplicated and then band-pass filtered into each range.…”

<p>Auscultation System for Acquisition of Vascular Sounds – Towards Sound-Based Monitoring of the Carotid Artery</p>

“…[10][11][12] The majority of studies and common guidelines on the management of atherosclerotic vascular disease agree on the value of carotid bruit sounds as an indicator for CS and a justification for further diagnostic imaging. [12][13][14] In contrast to today's simple evaluation of the presence of such bruits, recent developments in sensor technology, signal processing and machine learning potentially allow a more specific assessment of the sounds along with associated pathology related characteristics. Periodically performed auscultation measurements, preferably in a point-of-care or home-based fashion could provide a cost-effective and simple alternative to the previously mentioned expensive diagnostic imaging.…”

Computer Assisted Auscultation System for Phonoangiography of the Carotid Artery

“…Since it is possible to hear these changes, it should also be possible to measure and objectively quantify vascular sounds over a period of time. Dynamical changes in the flow and the sound signals can for example be associated with a pathological narrowing of the vessel and further indicate the need for additional diagnostic investigations [7].…”