12 results on '"fluid-structure interaction modeling"'
Search Results
2. Computational Assessment of Valvular Dysfunction in Discrete Subaortic Stenosis: A Parametric Study.
- Author
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Shar, Jason A., Keswani, Sundeep G., Grande-Allen, K. Jane, and Sucosky, Philippe
- Abstract
Purpose: Discrete subaortic stenosis (DSS) is a left-ventricular outflow tract (LVOT) obstruction caused by a membranous lesion. DSS is associated with steep aortoseptal angles (AoSAs) and is a risk factor for aortic regurgitation (AR). However, the etiology of AR secondary to DSS remains unknown. This study aimed at quantifying computationally the impact of AoSA steepening and DSS on aortic valve (AV) hemodynamics and AR. Methods: An LV geometry reconstructed from cine-MRI data was connected to an AV geometry to generate a unified 2D LV-AV model. Six geometrical variants were considered: unobstructed (CTRL) and DSS-obstructed LVOT (DSS), each reflecting three AoSA variations (110°, 120°, 130°). Fluid-structure interaction simulations were run to compute LVOT flow, AV leaflet dynamics, and regurgitant fraction (RF). Results: AoSA steepening and DSS generated vortex dynamics alterations and stenotic flow conditions. While the CTRL-110° model generated the highest degree of leaflet opening asymmetry, DSS preferentially altered superior leaflet kinematics, and caused leaflet-dependent alterations in systolic fluttering. LVOT steepening and DSS subjected the leaflets to increasing WSS overloads (up to 94% increase in temporal shear magnitude), while DSS also increased WSS bidirectionality on the inferior leaflet belly (+ 0.30-point in oscillatory shear index). Although AoSA steepening and DSS increased diastolic transvalvular backflow, regurgitant fractions (RF < 7%) remained below the threshold defining clinical mild AR. Conclusions: The mechanical interactions between AV leaflets and LVOT steepening/DSS hemodynamic derangements do not cause AR. However, the leaflet WSS abnormalities predicted in those anatomies provide new support to a mechanobiological etiology of AR secondary to DSS. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
3. Ultrasound-Based Fluid-Structure Interaction Modeling of Abdominal Aortic Aneurysms Incorporating Pre-stress.
- Author
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Fonken, Judith H. C., Maas, Esther J., Nievergeld, Arjet H. M., van Sambeek, Marc R. H. M., van de Vosse, Frans N., and Lopata, Richard G. P.
- Subjects
FLUID-structure interaction ,ABDOMINAL aortic aneurysms ,AORTIC rupture ,SHEARING force ,BLOOD pressure - Abstract
Currently, the prediction of rupture risk in abdominal aortic aneurysms (AAAs) solely relies on maximum diameter. However, wall mechanics and hemodynamics have shown to provide better risk indicators. Patient-specific fluid-structure interaction (FSI) simulations based on a non-invasive image modality are required to establish a patient-specific risk indicator. In this study, a robust framework to execute FSI simulations based on time-resolved three-dimensional ultrasound (3D+t US) data was obtained and employed on a data set of 30 AAA patients. Furthermore, the effect of including a pre-stress estimation (PSE) to obtain the stresses present in the measured geometry was evaluated. The established workflow uses the patient-specific 3D+t US-based segmentation and brachial blood pressure as input to generate meshes and boundary conditions for the FSI simulations. The 3D+t US-based FSI framework was successfully employed on an extensive set of AAA patient data. Omitting the pre-stress results in increased displacements, decreased wall stresses, and deviating time-averaged wall shear stress and oscillatory shear index patterns. These results underline the importance of incorporating pre-stress in FSI simulations. After validation, the presented framework provides an important tool for personalized modeling and longitudinal studies on AAA growth and rupture risk. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
4. Ultrasound-Based Fluid-Structure Interaction Modeling of Abdominal Aortic Aneurysms Incorporating Pre-stress
- Author
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Judith H. C. Fonken, Esther J. Maas, Arjet H. M. Nievergeld, Marc R. H. M. van Sambeek, Frans N. van de Vosse, and Richard G. P. Lopata
- Subjects
abdominal aortic aneurysms ,patient-specific ,fluid-structure interaction modeling ,rupture risk ,pre-stress estimation ,wall mechanics ,Physiology ,QP1-981 - Abstract
Currently, the prediction of rupture risk in abdominal aortic aneurysms (AAAs) solely relies on maximum diameter. However, wall mechanics and hemodynamics have shown to provide better risk indicators. Patient-specific fluid-structure interaction (FSI) simulations based on a non-invasive image modality are required to establish a patient-specific risk indicator. In this study, a robust framework to execute FSI simulations based on time-resolved three-dimensional ultrasound (3D+t US) data was obtained and employed on a data set of 30 AAA patients. Furthermore, the effect of including a pre-stress estimation (PSE) to obtain the stresses present in the measured geometry was evaluated. The established workflow uses the patient-specific 3D+t US-based segmentation and brachial blood pressure as input to generate meshes and boundary conditions for the FSI simulations. The 3D+t US-based FSI framework was successfully employed on an extensive set of AAA patient data. Omitting the pre-stress results in increased displacements, decreased wall stresses, and deviating time-averaged wall shear stress and oscillatory shear index patterns. These results underline the importance of incorporating pre-stress in FSI simulations. After validation, the presented framework provides an important tool for personalized modeling and longitudinal studies on AAA growth and rupture risk.
- Published
- 2021
- Full Text
- View/download PDF
5. Corrigendum: Ultrasound-Based Fluid-Structure Interaction Modeling of Abdominal Aortic Aneurysms Incorporating Pre-Stress.
- Author
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Fonken, Judith H. C., Maas, Esther J., Nievergeld, Arjet H. M., van Sambeek, Marc R. H. M., van de Vosse, Frans N., and Lopata, Richard G. P.
- Subjects
ABDOMINAL aortic aneurysms ,FLUID-structure interaction - Abstract
Graph: FIGURE 10 Visualization of the oscillatory shear index (OSI) resulting from the FSI simulations with and without PSE, and the difference in OSI for patients S1, M6, and L8. Keywords: abdominal aortic aneurysms; patient-specific; fluid-structure interaction modeling; rupture risk; prestress estimation; wall mechanics; hemodynamics EN abdominal aortic aneurysms patient-specific fluid-structure interaction modeling rupture risk prestress estimation wall mechanics hemodynamics 1 3 3 04/21/22 20220419 NES 220419 In the original article, there was an error in the calculation of the Oscillatory Shear Index (OSI). Abdominal aortic aneurysms, rupture risk, patient-specific, fluid-structure interaction modeling, hemodynamics, prestress estimation, wall mechanics. [Extracted from the article]
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- 2022
- Full Text
- View/download PDF
6. Comparative quantification of primary mitral regurgitation by computer modeling and simulated echocardiography.
- Author
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Wenbin Mao, Caballero, Andrés, Hahn, Rebecca T., and Wei Sun
- Subjects
- *
COMPUTER simulation , *ECHOCARDIOGRAPHY , *MITRAL valve insufficiency , *DOPPLER effect , *AORTIC valve , *CORRECTION factors - Abstract
Clinical investigations have demonstrated that mitral regurgitation (MR) quantification using echocardiography (echo) may significantly underestimate or overestimate the regurgitant volume, especially for two-dimensional (2D) echo. Computer modeling and simulated echo were conducted to evaluate the fundamental assumptions in the echo quantification of primary MR that is due to posterior mitral leaflet prolapse. The theoretical flaw of the proximal isovelocity surface area (PISA) method originates from the assumption that the MR flow rate is the product of the isovelocity surface area and aliasing velocity, which is only valid when the velocity vectors are perpendicular to the isovelocity surface. Other factors such as the Doppler angle effect, the view planes of 2D echo, and the single time instant of PISA were also analyzed. We find that the hemielliptic PISA method gives the smallest error for moderate and severe MR cases compared with other PISA methods. Compared with the PISA method, the volumetric technique (VT) is theoretically more robust. By considering correction factors that are caused by nonflat velocity profiles and the closing volume of the aortic valve, the accuracy of the VT method can be significantly improved. The corrected volumetric technique provides more accurate results compared with the PISA methods, especially for mild MR. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
7. Corrigendum: Ultrasound-Based Fluid-Structure Interaction Modeling of Abdominal Aortic Aneurysms Incorporating Pre-Stress
- Author
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Fonken, Judith H.C., Maas, Esther J., Nievergeld, Arjet H.M., van Sambeek, Marc R.H.M., van de Vosse, Frans N., Lopata, Richard G.P., Fonken, Judith H.C., Maas, Esther J., Nievergeld, Arjet H.M., van Sambeek, Marc R.H.M., van de Vosse, Frans N., and Lopata, Richard G.P.
- Abstract
The corrected Figure 11 appears below. A correction has been made to 3. Results, “3.3 Fluid Domain”. The corrected section appears below: “For three representative patients, the TAWSS and OSI resulting from the FSI-PSE and FSInoPSE simulations, and the corresponding spatial differences, are visualized in Figures 9, 10, respectively. These figures show that high TAWSS values mainly occur in the neck of the AAA and at the proximal and distal ends of the aneurysm region. High OSI values are mainly observed in the aneurysm regions, whereas the TAWSS is relatively low in this region. For patient S1, a clear difference in TAWSS and OSI patterns can be seen when the PSE is omitted, which is also reflected in the difference plots. For patient M6, the TAWSS patterns appear highly similar, whereas the OSI patterns do differ slightly. For the TAWSS, the difference plot does show differences, especially in the low TAWSS regions. For patient L8, both TAWSS and OSI patterns appear highly similar. However, the difference plots show some noticeable differences. For both TAWSS and OSI values, no clear decrease or increase was observed when the PSE was omitted, which is confirmed by Figures 11A,B, respectively. For the FSI-PSE simulations, the TAWSS for the moderate and large groups was significantly decreased compared to the small group. Furthermore, the difference in OSI between the small and large groups was significant. For the FSInoPSE simulations, only the difference in TAWSS between the small and large group was significant. The OSI for the moderate and large groups was significantly decreased compared to the small group. Figure 11C shows that the overall average difference in 1st percentile TAWSS equals 3.0%, whereas the overall average absolute spatial difference equals 6.5%. The difference in 1st percentile TAWSS value for the moderate and large groups were significantly increased compared to the small group. The overall average difference in 99th percentile OSI values i
- Published
- 2022
8. Ultrasound-Based Fluid-Structure Interaction Modeling of Abdominal Aortic Aneurysms Incorporating Pre-stress
- Author
-
Fonken, Judith H.C., Maas, Esther J., Nievergeld, Arjet H.M., van Sambeek, Marc R.H.M., van de Vosse, Frans N., Lopata, Richard G.P., Fonken, Judith H.C., Maas, Esther J., Nievergeld, Arjet H.M., van Sambeek, Marc R.H.M., van de Vosse, Frans N., and Lopata, Richard G.P.
- Abstract
Currently, the prediction of rupture risk in abdominal aortic aneurysms (AAAs) solely relies on maximum diameter. However, wall mechanics and hemodynamics have shown to provide better risk indicators. Patient-specific fluid-structure interaction (FSI) simulations based on a non-invasive image modality are required to establish a patient-specific risk indicator. In this study, a robust framework to execute FSI simulations based on time-resolved three-dimensional ultrasound (3D+t US) data was obtained and employed on a data set of 30 AAA patients. Furthermore, the effect of including a pre-stress estimation (PSE) to obtain the stresses present in the measured geometry was evaluated. The established workflow uses the patient-specific 3D+t US-based segmentation and brachial blood pressure as input to generate meshes and boundary conditions for the FSI simulations. The 3D+t US-based FSI framework was successfully employed on an extensive set of AAA patient data. Omitting the pre-stress results in increased displacements, decreased wall stresses, and deviating time-averaged wall shear stress and oscillatory shear index patterns. These results underline the importance of incorporating pre-stress in FSI simulations. After validation, the presented framework provides an important tool for personalized modeling and longitudinal studies on AAA growth and rupture risk.
- Published
- 2021
9. Bicuspid aortic valve hemodynamics induces abnormal medial remodeling in the convexity of porcine ascending aortas.
- Author
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Atkins, Samantha, Cao, Kai, Rajamannan, Nalini, and Sucosky, Philippe
- Subjects
- *
AORTIC valve , *MITRAL valve , *HEMODYNAMICS , *TISSUE remodeling , *DEGENERATION (Pathology) , *FLUID-structure interaction - Abstract
The type-I bicuspid aortic valve (BAV), which differs from the normal tricuspid aortic valve (TAV) most commonly by left-right coronary cusp fusion, is frequently associated with secondary aortopathies. While BAV aortic dilation has been linked to a genetic predisposition, hemodynamics has emerged as a potential alternate etiology. However, the link between BAV hemodynamics and aortic medial degeneration has not been established. The objective of this study was to compare the regional wall shear stresses (WSS) in a TAV and BAV ascending aorta (AA) and to isolate ex vivo their respective impact on aortic wall remodeling. The WSS environments generated in the convex region of a TAV and BAV AA were predicted through fluid-structure interaction (FSI) simulations in an aorta model subjected to both valvular flows. Remodeling of porcine aortic tissue exposed to TAV and BAV AA WSS for 48 h in a cone-and-plate bioreactor was investigated via immunostaining, immunoblotting and zymography. FSI simulations revealed the existence of larger and more unidirectional WSS in the BAV than in the TAV AA convexity. Exposure of normal aortic tissue to BAV AA WSS resulted in increased MMP-2 and MMP-9 expressions and MMP-2 activity but similar fibrillin-1 content and microfibril organization relative to the TAV AA WSS treatment. This study confirms the sensitivity of aortic tissue to WSS abnormalities and demonstrates the susceptibility of BAV hemodynamic stresses to focally mediate aortic medial degradation. The results provide compelling support to the important role of hemodynamics in BAV secondary aortopathy. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
10. Significance of aortoseptal angle anomalies to left ventricular hemodynamics and subaortic stenosis: A numerical study.
- Author
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Shar JA, Keswani SG, Grande-Allen KJ, and Sucosky P
- Subjects
- Constriction, Pathologic, Diagnostic Imaging, Humans, Stress, Mechanical, Heart Ventricles diagnostic imaging, Hemodynamics
- Abstract
Purpose: Discrete subaortic stenosis (DSS) is an obstructive cardiac disease caused by a membranous lesion in the left ventricular (LV) outflow tract (LVOT). Although its etiology is unknown, the higher prevalence of DSS in LVOT anatomies featuring a steep aortoseptal angle (AoSA) suggests a potential role for hemodynamics. Therefore, the objective of this study was to quantify the impact of AoSA steepening on the LV three-dimensional (3D) hemodynamic stress environment., Methods: A 3D LV model reconstructed from cardiac cine-magnetic resonance imaging was connected to four LVOT geometrical variations spanning the clinical AoSA range (115°-160°). LV hemodynamic stresses were characterized in terms of cycle-averaged pressure, temporal shear magnitude (TSM), and oscillatory shear index. The wall shear stress (WSS) topological skeleton was further analyzed by computing the scaled divergence of the WSS vector field., Results: AoSA steepening caused an increasingly perturbed subaortic flow marked by LVOT flow skewness and complex 3D secondary flow patterns. These disturbances generated WSS overloads (>45% increase in TSM vs. 160° model) on the inferior LVOT wall, and increased WSS contraction (>66% decrease in WSS divergence vs. 160° model) in regions prone to DSS membrane formation., Conclusions: AoSA steepening generated substantial hemodynamic stress abnormalities in LVOT regions prone to DSS formation. Further studies are needed to assess the possible impact of such mechanical abnormalities on the tissue and cellular responses., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)
- Published
- 2022
- Full Text
- View/download PDF
11. Computational assessment of bicuspid aortic valve wall-shear stress: implications for calcific aortic valve disease.
- Author
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Chandra, Santanu, Rajamannan, Nalini, and Sucosky, Philippe
- Subjects
- *
MITRAL valve , *AORTIC valve diseases , *HEMODYNAMICS , *BIOMECHANICS research , *RESEARCH - Abstract
The bicuspid aortic valve (BAV) is associated with a high prevalence of calcific aortic valve disease (CAVD). Although abnormal hemodynamics has been proposed as a potential pathogenic contributor, the native BAV hemodynamic stresses remain largely unknown. Fluid-structure interaction models were designed to quantify the regional BAV leaflet wall-shear stress over the course of CAVD. Systolic flow and leaflet dynamics were computed in two-dimensional tricuspid aortic valve (TAV) and type-1 BAV geometries with different degree of asymmetry (10 and 16% eccentricity) using an arbitrary Lagrangian-Eulerian approach. Valvular performance and regional leaflet wall-shear stress were quantified in terms of valve effective orifice area (EOA), oscillatory shear index (OSI) and temporal shear magnitude (TSM). The dependence of those characteristics on the degree of leaflet calcification was also investigated. The models predicted an average reduction of 49% in BAV peak-systolic EOA relative to the TAV. Regardless of the anatomy, the leaflet wall-shear stress was side-specific and characterized by high magnitude and pulsatility on the ventricularis and low magnitude and oscillations on the fibrosa. While the TAV and non-coronary BAV leaflets shared similar shear stress characteristics, the base of the fused BAV leaflet fibrosa exhibited strong abnormalities, which were modulated by the degree of calcification (6-fold, 10-fold and 16-fold TSM increase in the normal, mildly and severely calcified BAV, respectively, relative to the normal TAV). This study reveals the existence of major differences in wall-shear stress pulsatility and magnitude on TAV and BAV leaflets. Given the ability of abnormal fluid shear stress to trigger valvular inflammation, the results support the existence of a mechano-etiology of CAVD in the BAV. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
12. Comparative quantification of primary mitral regurgitation by computer modeling and simulated echocardiography.
- Author
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Mao W, Caballero A, Hahn RT, and Sun W
- Subjects
- Blood Flow Velocity, Humans, Image Interpretation, Computer-Assisted, Mitral Valve diagnostic imaging, Mitral Valve Insufficiency diagnostic imaging, Computer Simulation, Echocardiography, Mitral Valve physiopathology, Mitral Valve Insufficiency physiopathology, Models, Cardiovascular
- Abstract
Clinical investigations have demonstrated that mitral regurgitation (MR) quantification using echocardiography (echo) may significantly underestimate or overestimate the regurgitant volume, especially for two-dimensional (2D) echo. Computer modeling and simulated echo were conducted to evaluate the fundamental assumptions in the echo quantification of primary MR that is due to posterior mitral leaflet prolapse. The theoretical flaw of the proximal isovelocity surface area (PISA) method originates from the assumption that the MR flow rate is the product of the isovelocity surface area and aliasing velocity, which is only valid when the velocity vectors are perpendicular to the isovelocity surface. Other factors such as the Doppler angle effect, the view planes of 2D echo, and the single time instant of PISA were also analyzed. We find that the hemielliptic PISA method gives the smallest error for moderate and severe MR cases compared with other PISA methods. Compared with the PISA method, the volumetric technique (VT) is theoretically more robust. By considering correction factors that are caused by nonflat velocity profiles and the closing volume of the aortic valve, the accuracy of the VT method can be significantly improved. The corrected volumetric technique provides more accurate results compared with the PISA methods, especially for mild MR. NEW & NOTEWORTHY We evaluate the accuracy of common echocardiography techniques for the quantification of primary mitral regurgitations using computer modeling. The hemielliptic proximal isovelocity surface area (PISA) method gives the smallest error (within 15%) for moderate and severe mitral regurgitation cases compared with other PISA methods. The volumetric method is theoretically more robust than the PISA method. The accuracy of the volumetric method can be improved by a correction factor around 0.7 because of the nonflat velocity profiles and the closing volume of the aortic valve.
- Published
- 2020
- Full Text
- View/download PDF
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