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Noninvasive Diagnosis Using Sounds Originating from within the Body
Published in Robert B. Northrop, Non-Invasive Instrumentation and Measurement in Medical Diagnosis, 2017
There are many endogenous sources of acoustic energy that have diagnostic significance. These include, but are not limited to, heart sounds (valves leaking, blood turbulence, pericardial friction rub), the lungs (rales, rhonchi, squeaks, crepitations, gurgling, pleural friction rub, silence), arteries (bruit, also known as turbulence sounds caused by a stenosis, or narrowing of a blood vessel), stomach and intestines (sounds of digestion, borborygmi), joints (arthritic friction rub, tendon snap, etc.), and the inner ear (otoacoustic emissions [OAEs]). The absence of sounds can also have diagnostic significance. Most of these sounds have acoustic spectral energy in the lowest range of human hearing as well as at audible low frequencies. Some of these sounds have origin in the elastic vibrations of dense connective tissues, or vibrations induced in elastic artery walls by blood turbulence, or vibrations induced by blood passing through small apertures. All such sound vibrations propagate through the body's tissues with losses, reflections, and refractions to the skin, in which perpendicular vibrations are introduced.
Cardiovascular system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
A noise on auscultation (listening with a stethoscope) of the neck is called a bruit and may be due to transmission of sound from a cardiac cause or from turbulent flow in the carotid arteries. Echocardiography and/or carotid ultrasound may be used to determine the origin of the sound and the severity of any carotid stenosis if that is the cause. The benefit of surgery for asymptomatic carotid stenosis, however, is less well established than for patients who have had TIA or stroke.
Carotid hemodynamic response to external pressure and comparison with induced-stenosis progression: a fluid-structure interaction study
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Kshitij Shakya, Dalchand Ahirwar, P. M. Nabeel, Shubhajit Roy Chowdhury
Applying external pressure over the healthy artery has not been compared yet with the stenosis developing within the lumen of the arterial wall. The application of external pressure on the common carotid artery (CCA) generally occurs when performing carotid ultrasound, using a tonometer to measure pulse wave velocity and sometimes detecting and analysing bruit using a stethoscope. In a study, the impact of external compression by the ultrasound probe was studied on CCA (Chayer et al. 2022). The deformation in the CCA appears to be somewhat bell-shaped. There are several indirect studies to simulate the stenosis by inducing a change in the shape of the geometry, one such study did the computational analysis by applying the lattice Boltzmann method to the regular and irregular shaped stenosis (Sakthivel and Anupindi 2021). A comparison was done between 3 -CFD and 0D branch pulmonary artery stenosis model by Pewowaruk et al. (2021). Typically blood flow interacts with the artery wall following the FSI. It was shown by Failer et al. (2021) that FSI might describe more clinical outcomes than the rigid stenosed artery. Computational modelling also provides flexibility in choosing the blood rheology model according to the diseased arteries and other clinical perspectives. This kind of study was done by Liu et al. (2021a) to compare the effect of Newtonian blood flow with non-Newtonian blood flow in the stenosed artery.