Computational Modeling and Analysis of Murmurs Generated by Modeled Aortic Stenoses

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Chi Zhu ◽  
Jung-Hee Seo ◽  
Rajat Mittal
Keyword(s):  
Aortic Stenosis ◽  
Numerical Study ◽  
Computational Modelling ◽  
Sound Intensity ◽  
Elliptic Cylinder ◽  
Intensity Pattern ◽  
Modeling And Analysis ◽  
Curved Pipe ◽  
Epidermal Surface ◽  
History Of

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.

Computational modelling and analysis of haemodynamics in a simple model of aortic stenosis

2018 ◽  
Vol 851 ◽  
pp. 23-49 ◽  
Author(s):  
Chi Zhu ◽  
Jung-Hee Seo ◽  
Rajat Mittal
Keyword(s):  
Simple Model ◽  
Aortic Stenosis ◽  
Secondary Flow ◽  
Pressure Fluctuation ◽  
Computational Modelling ◽  
Maximum Pressure ◽  
Cardiac Auscultation ◽  
Curved Pipe ◽  
Free Jet ◽  
Wall Pressure Fluctuation

In a study motivated by considerations associated with heart murmurs and cardiac auscultation, numerical simulations are used to analyse the haemodynamics in a simple model of an aorta with an aortic stenosis. The aorta is modelled as a curved pipe with a$180^{\circ }$turn, and three different stenoses with area reductions of 50 %, 62.5 % and 75 % are examined. A uniform steady inlet velocity with a Reynolds number of 2000 is used for all of the cases and direct numerical simulation is employed to resolve the dynamics of the flow. The poststenotic flow is dominated by the jet that originates from the stenosis as well as the secondary flow induced by the curvature, and both contribute significantly to the flow turbulence. On the anterior surface of the modelled aorta, the location with maximum pressure fluctuation, which may be considered as the source location for the murmurs, is found to be located around$60^{\circ }$along the aortic arch, and this location is relatively insensitive to the severity of the stenosis. For all three cases, this high-intensity wall pressure fluctuation includes contributions from both the jet and the secondary flow. Spectral analysis shows that for all three stenoses, the Strouhal number of the vortex shedding of the jet shear layer is close to 0.93, which is higher than the shedding frequency of a corresponding free jet or a jet confined in a straight pipe. This frequency also appears in the pressure spectra at the location postulated as the source of the murmurs, in the form of a ‘break frequency.’ The implications of these findings for cardiac auscultation-based diagnosis of aortic stenosis are also discussed.

scholarly journals Steady and unsteady flow of non-newtonian fluid in curved pipe with triangular

2006 ◽  
Vol 3 (3) ◽  
pp. 470-480
Author(s):  
Baghdad Science Journal
Keyword(s):  
Unsteady Flow ◽  
Pressure Gradient ◽  
Secondary Flow ◽  
Cross Section ◽  
Numerical Study ◽  
Equations Of Motion ◽  
Curved Pipe ◽  
First Case ◽  
Stable Flow ◽  
Flow Cross

This paper deals with numerical study of the flow of stable and fluid Allamstqr Aniotina in an area surrounded by a right-angled triangle has touched particularly valuable secondary flow cross section resulting from the pressure gradient In the first case was analyzed stable flow where he found that the equations of motion that describe the movement of the fluid

scholarly journals What is the role of computational models in Cognitive Science? A quantitative and qualitative analysis of the history of the TRACE model of speech segmentation

2019 ◽  
Author(s):  
Manisha Chawla ◽  
Richard Shillcock
Keyword(s):  
Qualitative Analysis ◽  
Cognitive Science ◽  
Computational Models ◽  
Computational Modelling ◽  
Speech Segmentation ◽  
Cognitive Modelling ◽  
Trace Model ◽  
History Of ◽  
Central Paradigm

Implemented computational models are a central paradigm of Cognitive Science. How do cognitive scientists really use such models? We take the example of one of the most successful and influential cognitive models, TRACE (McClelland & Elman, 1986), and we map its impact on the field in terms of published, electronically available documents that cite the original TRACE paper over a period of 25 years since its publication. We draw conclusions about the general status of computational cognitive modelling and make critical suggestions regarding the nature of abstraction in computational modelling.

scholarly journals Natural History of Very Severe Aortic Stenosis

Circulation ◽  
2010 ◽  
Vol 121 (1) ◽  
pp. 151-156 ◽  
Author(s):  
Raphael Rosenhek ◽  
Robert Zilberszac ◽  
Michael Schemper ◽  
Martin Czerny ◽  
Gerald Mundigler ◽  
...  
Keyword(s):  
Natural History ◽  
Aortic Stenosis ◽  
Severe Aortic Stenosis ◽  
History Of

Abstract 13454: The Impact of Prior Stroke on the Outcome of Patients With Severe Aortic Stenosis Undergoing Transcatheter Aortic Valve Replacement

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Romain Didier ◽  
Edward Koifman ◽  
Sarkis Kiramijyan ◽  
Smita Negi ◽  
Ricardo Escarcega ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Stenosis ◽  
Aortic Valve Replacement ◽  
Severe Aortic Stenosis ◽  
Minor Stroke ◽  
Post Procedure ◽  
Cerebrovascular Events ◽  
History Of ◽  
The Impact ◽  
Prior Stroke

Introduction: Prior stroke has been identified as an independent correlate for post-procedure cerebrovascular events (CVE) in aortic stenosis (AS) patients undergoing surgical aortic valve replacement (SAVR). The present study aimed to evaluate the impact of prior cerebrovascular events on outcome in AS patients undergoing TAVR. Methods: Patients with severe AS undergoing TAVR between May 2007-March 2015 were included and categorized to patients with and without prior CVE defined as stroke and transit ischemic attack. Baseline, procedural characteristics, in-hospital outcomes, 1-month and 1-year mortality were compared, in accordance with the VARC-2 consensus. Results: A cohort of 662 consecutive patients with severe AS undergoing TAVR was included in the analysis. Of these, 120 patients had prior CVE, and 542 without. Balloon expandable valve was used in 70.7% and self-expandable valve in 29.3% of the patients. Trans-femoral access was used in 78% (571), and pre-TAVR balloon aortic valvuloplasty was performed in 87% (574). Patients with prior CVE had a higher mean STS score compared to those without prior CVE (10.1% versus 8.8%, respectively; p=0,006) and demonstrated higher rates of atherosclerotic disease involving the coronary, peripheral and carotid arteries. In-hospital minor stroke occurred more often in patients with prior CVE vs. those without CVE (3.3% vs. 0.7%; p=0.04). However, similar mortality rates were recorded at 1, 6, and 12 months (figure 1), and there were no significant differences in major stroke, bleeding, or post-procedure hospital stay between both groups. Conclusions: Prior history of CVE infers a higher risk for in-hospital minor stroke, yet no impact on other outcomes post TAVR. Patients with and without a history of prior CVE with severe aortic stenosis will similarly benefit from TAVR. Therefore, a history of CVE should not be considered an exclusion criterion.

scholarly journals 776 A History of Cancer Does Not Predict Long Term Mortality in Patients With Severe Aortic Stenosis

2020 ◽  
Vol 29 ◽  
pp. S386
Author(s):  
A. Murphy ◽  
R. Subramanian ◽  
A. Enayati ◽  
A. Koshy ◽  
P. Kunniardy ◽  
...  
Keyword(s):  
Aortic Stenosis ◽  
Severe Aortic Stenosis ◽  
History Of ◽  
History Of Cancer ◽  
Long Term Mortality
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