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Raviol J, Plet G, Hasegawa R, Yu K, Kosukegawa H, Ohta M, Magoariec H, Pailler-Mattei C. Towards the mechanical characterisation of unruptured intracranial aneurysms: Numerical modelling of interactions between a deformation device and the aneurysm wall. J Mech Behav Biomed Mater 2024; 153:106469. [PMID: 38402693 DOI: 10.1016/j.jmbbm.2024.106469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 02/13/2024] [Accepted: 02/15/2024] [Indexed: 02/27/2024]
Abstract
Intracranial aneurysm is a critical pathology related to the arterial wall deterioration. This work is an essential aspect of a large scale project aimed at providing clinicians with a non-invasive patient-specific decision support tool regarding the rupture risk assessment. A machine learning algorithm links the aneurysm shape observed and a database of UIA clinical images associated with in vivo wall mechanical properties and rupture characterisation. The database constitution is derived from a device prototype coupled with medical imaging. It provides the mechanical characterisation of the aneurysm from the wall deformation obtained by inverse analysis based on the variation of luminal volume. Before performing in vivo tests of the device on small animals, a numerical model was built to quantify the device's impact on the aneurysm wall under natural blood flow conditions. As the clinician will never be able to precisely situate the device, several locations were considered. In preparation for the inverse analysis procedure, artery material laws of increasing complexity were studied (linear elastic, hyper elastic Fung-like). Considering all the device locations and material laws, the device induced relative displacements to the Systole peak (worst case scenario with the highest mechanical stimulus linked to the blood flow) ranging from 375 μm to 1.28 mm. The variation of luminal volume associated with the displacements was between 0.95 % and 4.3 % compared to the initial Systole volume of the aneurysm. Significant increase of the relative displacements and volume variations were found with the study of different cardiac cycle moments between the blood flow alone and the device application. For forthcoming animal model studies, Spectral Photon CT Counting, with a minimum spatial resolution of 250 μm, was selected as the clinical imaging technique. Based on this preliminary study, the displacements and associated volume variations (baseline for inverse analyse), should be observable and exploitable.
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Affiliation(s)
- J Raviol
- Laboratoire de Tribologie et Dynamique des Systèmes, CNRS UMR 5513, Université de Lyon, École Centrale de Lyon, France
| | - G Plet
- Laboratoire de Tribologie et Dynamique des Systèmes, CNRS UMR 5513, Université de Lyon, École Centrale de Lyon, France
| | - R Hasegawa
- Graduate School of Engineering, Tohuku University, 980-8579, Sendai Miyagi, Japan; Institute of Fluid Science, Tohuku University, 980-8577, Sendai Miyagi, Japan
| | - K Yu
- Institute of Fluid Science, Tohuku University, 980-8577, Sendai Miyagi, Japan
| | - H Kosukegawa
- Institute of Fluid Science, Tohuku University, 980-8577, Sendai Miyagi, Japan
| | - M Ohta
- Institute of Fluid Science, Tohuku University, 980-8577, Sendai Miyagi, Japan; ElyT MaX, CNRS UMI 3537, Université de Lyon, Tohoku University, France, Japan
| | - H Magoariec
- Laboratoire de Tribologie et Dynamique des Systèmes, CNRS UMR 5513, Université de Lyon, École Centrale de Lyon, France
| | - C Pailler-Mattei
- Laboratoire de Tribologie et Dynamique des Systèmes, CNRS UMR 5513, Université de Lyon, École Centrale de Lyon, France; ISPB-Faculté de Pharmacie, Université Claude Bernard Lyon 1, Université de Lyon, France.
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Szafron JM, Heng EE, Boyd J, Humphrey JD, Marsden AL. Hemodynamics and Wall Mechanics of Vascular Graft Failure. Arterioscler Thromb Vasc Biol 2024; 44:1065-1085. [PMID: 38572650 PMCID: PMC11043008 DOI: 10.1161/atvbaha.123.318239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 03/12/2024] [Indexed: 04/05/2024]
Abstract
Blood vessels are subjected to complex biomechanical loads, primarily from pressure-driven blood flow. Abnormal loading associated with vascular grafts, arising from altered hemodynamics or wall mechanics, can cause acute and progressive vascular failure and end-organ dysfunction. Perturbations to mechanobiological stimuli experienced by vascular cells contribute to remodeling of the vascular wall via activation of mechanosensitive signaling pathways and subsequent changes in gene expression and associated turnover of cells and extracellular matrix. In this review, we outline experimental and computational tools used to quantify metrics of biomechanical loading in vascular grafts and highlight those that show potential in predicting graft failure for diverse disease contexts. We include metrics derived from both fluid and solid mechanics that drive feedback loops between mechanobiological processes and changes in the biomechanical state that govern the natural history of vascular grafts. As illustrative examples, we consider application-specific coronary artery bypass grafts, peripheral vascular grafts, and tissue-engineered vascular grafts for congenital heart surgery as each of these involves unique circulatory environments, loading magnitudes, and graft materials.
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Affiliation(s)
- Jason M Szafron
- Departments of Pediatrics (J.M.S., A.L.M.), Stanford University, CA
| | - Elbert E Heng
- Cardiothoracic Surgery (E.E.H., J.B.), Stanford University, CA
| | - Jack Boyd
- Cardiothoracic Surgery (E.E.H., J.B.), Stanford University, CA
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT (J.D.H.)
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Raviol J, Plet G, Langlois JB, Si-Mohamed S, Magoariec H, Pailler-Mattei C. In vivo mechanical characterization of arterial wall using an inverse analysis procedure: application on an animal model of intracranial aneurysm. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231936. [PMID: 38633347 PMCID: PMC11022001 DOI: 10.1098/rsos.231936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/19/2024] [Accepted: 02/24/2024] [Indexed: 04/19/2024]
Abstract
Intracranial aneurysm is a pathology related to the deterioration of the arterial wall. This work is an essential part of a large-scale project aimed at providing clinicians with a non-invasive patient-specific decision support tool to facilitate the rupture risk assessment. It will lean on the link between the aneurysm shape clinically observed and a database derived from the in vivo mechanical characterization of aneurysms. To supply this database, a deformation device prototype of the arterial wall was developed. Its use coupled with medical imaging (spectral photon-counting computed tomography providing a spatial resolution down to 250 μm) is used to determine the in vivo mechanical properties of the wall based on the inverse analysis of the quantification of the wall deformation observed experimentally. This study presents the in vivo application of this original procedure to an animal model of aneurysm. The mechanical properties of the aneurysm wall identified were consistent with the literature, and the errors between the numerical and experimental results were less than 10%. Based on these parameters, this study allows the assessment of the aneurysm stress state for a known solicitation and points towards the definition of a rupture criterion.
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Affiliation(s)
- J. Raviol
- Ecole Centrale de Lyon, CNRS, ENTPE, LTDS, UMR 5513, Écully69130, France
| | - G. Plet
- Ecole Centrale de Lyon, CNRS, ENTPE, LTDS, UMR 5513, Écully69130, France
| | | | - S. Si-Mohamed
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, F69621, Villeurbanne69100, France
- Département de Radiologie, Hôpital Louis Pradel, Hospices Civils de Lyon, Bron69677, France
| | - H. Magoariec
- Ecole Centrale de Lyon, CNRS, ENTPE, LTDS, UMR 5513, Écully69130, France
| | - C. Pailler-Mattei
- Ecole Centrale de Lyon, CNRS, ENTPE, LTDS, UMR 5513, Écully69130, France
- Université de Lyon, Université Claude Bernard Lyon 1, ISPB-Faculté de Pharmacie, Lyon69008, France
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Pan F, Mori N, Mugikura S, Ohta M, Anzai H. The influence of blood velocity and vessel geometric parameters on wall shear stress. Med Eng Phys 2024; 124:104112. [PMID: 38418022 DOI: 10.1016/j.medengphy.2024.104112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 11/16/2023] [Accepted: 01/18/2024] [Indexed: 03/01/2024]
Abstract
Vascular geometry was proposed to be one risk factor of atherosclerosis (AS). When developing this hypothesis, the discussion of geometry-wall shear stress (WSS) has often been included. However, further exploration on how various geometric parameters were affecting WSS was needed. The purpose of this study was to investigate the influence degree of vessel geometric parameters and blood velocity on WSS. A computational fluid dynamics (CFD) analyses of the vertebral and basilar arteries (VA and BA, respectively) was used. Twenty patients with no plaques or vessel wall thickening at the VA and BA were included. CFD analyses using both specific vessel models and flow conditions measured by ultrasound Doppler were performed. Subsequently, CFD results were post-processed with multiple linear regression to investigate numerical correlations between geometrical and flow parameters and WSS. The results of the multiple linear regression analysis further demonstrated that the BA proximal velocity was the most influential factor positively influencing BA WSS. The lower the WSS was, the stronger the influence brought by BA average diameter would be. The regression demonstrated that the contributions brought by average diameter and proximal velocity in lower WSS regions were lower than that in higher WSS regions. Tortuosity was only positively correlated with 97.5th WSS percentile, and vessel length and curvature showed no correlation with WSS. This study quantified the influence degree of BA morphology and flow velocity on WSS, which may have practical implications for predicting hemodynamic risks.
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Affiliation(s)
- Fangjia Pan
- Graduate school of Biomedical Engineering, Tohoku University, Sendai, Japan; Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Naoko Mori
- Department of Radiology, Akita University Graduate School of Medicine, Akita, Japan
| | - Shunji Mugikura
- Department of Diagnostic Radiology, Graduate School of Medicine, Tohoku University, Sendai, Japan; Division of Image Statistics, Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan
| | - Makoto Ohta
- Institute of Fluid Science, Tohoku University, Sendai, Japan; ELyTMaX IRL3757, CNRS, Univ Lyon, INSA Lyon, Centrale Lyon, Tohoku University, Université Claude Bernard Lyon 1, Sendai, Japan
| | - Hitomi Anzai
- Institute of Fluid Science, Tohoku University, Sendai, Japan.
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Hugenroth K, Krooß F, Hima F, Strudthoff L, Kopp R, Arens J, Kalverkamp S, Steinseifer U, Neidlin M, Spillner J. Inflow from a Cardiopulmonary Assist System to the Pulmonary Artery and Its Implications for Local Hemodynamics-a Computational Fluid Dynamics Study. J Cardiovasc Transl Res 2023; 16:842-851. [PMID: 36662482 PMCID: PMC10480287 DOI: 10.1007/s12265-022-10349-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 12/19/2022] [Indexed: 01/21/2023]
Abstract
When returning blood to the pulmonary artery (PA), the inflow jet interferes with local hemodynamics. We investigated the consequences for several connection scenarios using transient computational fluid dynamics simulations. The PA was derived from CT data. Three aspects were varied: graft flow rate, anastomosis location, and inflow jet path length from anastomosis site to impingement on the PA wall. Lateral anastomosis locations caused abnormal flow distribution between the left and right PA. The central location provided near-physiological distribution but induced higher wall shear stress (WSS). All effects were most pronounced at high graft flows. A central location is beneficial regarding flow distribution, but the resulting high WSS might promote detachment of local thromboembolisms or influence the autonomic nervous innervation. Lateral locations, depending on jet path length, result in lower WSS at the cost of an unfavorable flow distribution that could promote pulmonary vasculature changes. Case-specific decisions and further research are necessary.
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Affiliation(s)
- Kristin Hugenroth
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Aachen, Germany.
| | - Felix Krooß
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Flutura Hima
- Department of Thoracic and Cardiovascular Surgery, Medical Faculty, University Hospital, RWTH Aachen University, Aachen, Germany
| | - Lasse Strudthoff
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Rüdger Kopp
- Department of Intensive Care Medicine and Intermediate Care, Medical Faculty, University Hospital, RWTH Aachen University, Aachen, Germany
| | - Jutta Arens
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Sebastian Kalverkamp
- Department of Thoracic and Cardiovascular Surgery, Medical Faculty, University Hospital, RWTH Aachen University, Aachen, Germany
| | - Ulrich Steinseifer
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Michael Neidlin
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Jan Spillner
- Department of Thoracic and Cardiovascular Surgery, Medical Faculty, University Hospital, RWTH Aachen University, Aachen, Germany
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Sadeghi R, Tomka B, Khodaei S, Daeian M, Gandhi K, Garcia J, Keshavarz-Motamed Z. Impact of extra-anatomical bypass on coarctation fluid dynamics using patient-specific lumped parameter and Lattice Boltzmann modeling. Sci Rep 2022; 12:9718. [PMID: 35690596 PMCID: PMC9188592 DOI: 10.1038/s41598-022-12894-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 04/11/2022] [Indexed: 01/28/2023] Open
Abstract
Accurate hemodynamic analysis is not only crucial for successful diagnosis of coarctation of the aorta (COA), but intervention decisions also rely on the hemodynamics assessment in both pre and post intervention states to minimize patient risks. Despite ongoing advances in surgical techniques for COA treatments, the impacts of extra-anatomic bypass grafting, a surgical technique to treat COA, on the aorta are not always benign. Our objective was to investigate the impact of bypass grafting on aortic hemodynamics. We investigated the impact of bypass grafting on aortic hemodynamics using a patient-specific computational-mechanics framework in three patients with COA who underwent bypass grafting. Our results describe that bypass grafting improved some hemodynamic metrics while worsened the others: (1) Doppler pressure gradient improved (decreased) in all patients; (2) Bypass graft did not reduce the flow rate substantially through the COA; (3) Systemic arterial compliance increased in patients #1 and 3 and didn't change (improve) in patient 3; (4) Hypertension got worse in all patients; (5) The flow velocity magnitude improved (reduced) in patient 2 and 3 but did not improve significantly in patient 1; (6) There were elevated velocity magnitude, persistence of vortical flow structure, elevated turbulence characteristics, and elevated wall shear stress at the bypass graft junctions in all patients. We concluded that bypass graft may lead to pseudoaneurysm formation and potential aortic rupture as well as intimal hyperplasia due to the persistent abnormal and irregular aortic hemodynamics in some patients. Moreover, post-intervention, exposures of endothelial cells to high shear stress may lead to arterial remodeling, aneurysm, and rupture.
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Affiliation(s)
- Reza Sadeghi
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, Canada ON
| | - Benjamin Tomka
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, Canada ON
| | - Seyedvahid Khodaei
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, Canada ON
| | - MohammadAli Daeian
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, Canada ON
| | - Krishna Gandhi
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, Canada ON
| | - Julio Garcia
- grid.489011.50000 0004 0407 3514Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute of Alberta, Calgary, AB Canada ,grid.22072.350000 0004 1936 7697Department of Radiology, University of Calgary, Calgary, AB Canada ,grid.22072.350000 0004 1936 7697Department of Cardiac Sciences, University of Calgary, Calgary, AB Canada ,grid.413571.50000 0001 0684 7358Alberta Children’s Hospital Research Institute, Calgary, AB Canada
| | - Zahra Keshavarz-Motamed
- grid.25073.330000 0004 1936 8227Department of Mechanical Engineering, McMaster University, Hamilton, Canada ON ,grid.25073.330000 0004 1936 8227School of Biomedical Engineering, McMaster University, Hamilton, ON Canada ,grid.25073.330000 0004 1936 8227School of Computational Science and Engineering, McMaster University, Hamilton, ON Canada
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Chi Z, Beile L, Deyu L, Yubo F. Application of multiscale coupling models in the numerical study of circulation system. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2022. [DOI: 10.1016/j.medntd.2022.100117] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Tran K, Yang W, Marsden A, Lee JT. Patient-specific computational flow modelling for assessing hemodynamic changes following fenestrated endovascular aneurysm repair. JVS Vasc Sci 2021; 2:53-69. [PMID: 34258601 PMCID: PMC8274562 DOI: 10.1016/j.jvssci.2020.11.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Objective This study aimed to develop an accessible patient-specific computational flow modelling pipeline for evaluating the hemodynamic performance of fenestrated endovascular aneurysm repair (fEVAR), with the hypothesis that computational flow modelling can detect aortic branch hemodynamic changes associated with fEVAR graft implantation. Methods Patients who underwent fEVAR for juxtarenal aortic aneurysms with the Cook ZFEN were retrospectively selected. Using open-source SimVascular software, preoperative and postoperative visceral aortic anatomy was manually segmented from computed tomography angiograms. Three-dimensional geometric models were then discretized into tetrahedral finite element meshes. Patient-specific pulsatile in-flow conditions were derived from known supraceliac aortic flow waveforms and adjusted for patient body surface area, average resting heart rate, and blood pressure. Outlet boundary conditions consisted of three-element Windkessel models approximated from physiologic flow splits. Rigid wall flow simulations were then performed on preoperative and postoperative models with the same inflow and outflow conditions. We used SimVascular's incompressible Navier-Stokes solver to perform blood flow simulations on a cluster using 72 cores. Results Preoperative and postoperative flow simulations were performed for 10 patients undergoing fEVAR with a total of 30 target vessels (20 renal stents, 10 mesenteric scallops). Postoperative models required a higher mean number of mesh elements to reach mesh convergence (3.2 ± 1.8 × 106 vs 2.6 ± 1.1 × 106; P = .005) with a longer mean computational time (10.3 ± 6.3 hours vs 7.8 ± 3.5 hours; P = .04) compared with preoperative models. fEVAR was associated with small but statistically significant increases in mean peak proximal aortic arterial pressure (140.3 ± 11.0 mm Hg vs 136.9 ± 8.7 mm Hg; P = .02) and peak renal artery pressure (131.6 ± 14.8 mm Hg vs 128.9 ± 11.8 mm Hg; P = .04) compared with preoperative simulations. No differences were observed in peak pressure in the celiac, superior mesenteric, or distal aortic arteries (P = .17-.96). When measuring blood flow, the only observed difference was an increase in peak renal flow rate after fEVAR (17.5 ± 3.8 mL/s vs 16.9 ± 3.5 mL/s; P = .04). fEVAR was not associated with changes in the mean pressure or the mean flow rate in the celiac, superior mesenteric, or renal arteries (P = .06-.98). Stenting of the renal arteries did not induce significant changes time-averaged wall shear stress in the proximal renal artery (23.4 ± 8.1 dynes/cm2 vs 23.2 ± 8.4 dynes/cm2; P = .98) or distal renal artery (32.7 ± 13.9 dynes/cm2 vs 29.6 ± 11.8 dynes/cm2; P = .23). In addition, computational visualization of cross-sectional velocity profiles revealed low flow disturbances associated with protrusion of renal graft fabric into the aortic lumen. Conclusions In a pilot study involving a selective cohort of patients who underwent uncomplicated fEVAR, patient-specific flow modelling was a feasible method for assessing the hemodynamic performance of various two-vessel fenestrated device configurations and revealed subtle differences in computationally derived peak branch pressure and blood flow rates. Structural changes in aortic flow geometry after fEVAR do not seem to affect computationally estimated renovisceral branch perfusion or wall shear stress adversely. Additional studies with invasive angiography or phase contrast magnetic resonance imaging are required to clinically validate these findings. (JVS–Vascular Science 2021;2:53-69.) Clinical Relevance Using a computational flow modelling for assessing the hemodynamic performance of fenestrated endovascular aneurysm repair (fEVAR), this real-world, patient-specific study included 10 participants and found that structural changes in aortic flow geometry after fEVAR did not seem to adversely impact estimated renal or visceral branch perfusion metrics (eg, peak and mean arterial pressure and flow rates) or wall shear stress. These findings overall support the ongoing clinical use of commercially available fEVAR devices for repair of juxtarenal aortic aneurysms, and provides a computational framework for future evaluation of fEVAR configurations in a preoperative or postoperative settings.
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Affiliation(s)
- Kenneth Tran
- Division of Vascular Surgery, Stanford University.,Cardiovascular Institute, Stanford University
| | - Weiguang Yang
- Department of Pediatrics (Cardiology), Stanford University
| | - Alison Marsden
- Department of Pediatrics (Cardiology), Stanford University.,Department of Bioengineering, Stanford University
| | - Jason T Lee
- Division of Vascular Surgery, Stanford University.,Cardiovascular Institute, Stanford University
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Sharzehee M, Seddighi Y, Sprague EA, Finol EA, Han HC. A Hemodynamic Comparison of Myocardial Bridging and Coronary Atherosclerotic Stenosis: A Computational Model With Experimental Evaluation. J Biomech Eng 2021; 143:031013. [PMID: 33269788 DOI: 10.1115/1.4049221] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Indexed: 11/08/2022]
Abstract
Myocardial bridging (MB) and coronary atherosclerotic stenosis can impair coronary blood flow and may cause myocardial ischemia or even heart attack. It remains unclear how MB and stenosis are similar or different regarding their impacts on coronary hemodynamics. The purpose of this study was to compare the hemodynamic effects of coronary stenosis and MB using experimental and computational fluid dynamics (CFD) approaches. For CFD modeling, three MB patients with different levels of lumen obstruction, mild, moderate, and severe were selected. Patient-specific left anterior descending (LAD) coronary artery models were reconstructed from biplane angiograms. For each MB patient, the virtually healthy and stenotic models were also simulated for comparison. In addition, an in vitro flow-loop was developed, and the pressure drop was measured for comparison. The CFD simulations results demonstrated that the difference between MB and stenosis increased with increasing MB/stenosis severity and flowrate. Experimental results showed that increasing the MB length (by 140%) only had significant impact on the pressure drop in the severe MB (39% increase at the exercise), but increasing the stenosis length dramatically increased the pressure drop in both moderate and severe stenoses at all flow rates (31% and 93% increase at the exercise, respectively). Both CFD and experimental results confirmed that the MB had a higher maximum and a lower mean pressure drop in comparison with the stenosis, regardless of the degree of lumen obstruction. A better understanding of MB and atherosclerotic stenosis may improve the therapeutic strategies in coronary disease patients and prevent acute coronary syndromes.
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Affiliation(s)
- Mohammadali Sharzehee
- Department of Mechanical Engineering, The University of Texas at San Antonio, San Antonio, TX 78249
| | - Yasamin Seddighi
- Department of Mechanical Engineering, The University of Texas at San Antonio, San Antonio, TX 78249
| | - Eugene A Sprague
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229
| | - Ender A Finol
- Department of Mechanical Engineering, The University of Texas at San Antonio, San Antonio, TX 78249
| | - Hai-Chao Han
- Department of Mechanical Engineering, The University of Texas at San Antonio, San Antonio, TX 78249
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Poelma C. Measurement in opaque flows: a review of measurement techniques for dispersed multiphase flows. ACTA MECHANICA 2020; 231:2089-2111. [PMID: 32549583 PMCID: PMC7271021 DOI: 10.1007/s00707-020-02683-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 03/17/2020] [Indexed: 06/11/2023]
Abstract
A review is presented of measurement techniques to characterise dispersed multiphase flows, which are not accessible by means of conventional optical techniques. The main issues that limit the accuracy and effectiveness of optical techniques are briefly discussed: cross-talk, a reduced signal-to-noise ratio, and (biased) data drop-out. Extensions to the standard optical techniques include the use of fluorescent tracers, refractive index matching, ballistic imaging, structured illumination, and optical coherence tomography. As the first non-optical technique, a brief discussion of electrical capacitance tomography is given. While truly non-invasive, it suffers from a low resolving power. Ultrasound-based techniques have rapidly evolved from Doppler-based profiling to recent 2D approaches using feature tracking. The latter is also suitable for time-resolved flow studies. Magnetic resonance velocimetry can provide time-averaged velocity fields in 3D for the continuous phase. Finally, X-ray imaging is demonstrated to be an important tool to quantify local gas fractions. While potentially very powerful, the impact of the techniques will depend on the development of acquisition and measurement protocols for fluid mechanics, rather than for clinical imaging. This requires systematic development, aided by careful validation experiments. As theoretical predictions for multiphase flows are sparse, it is important to formulate standardised 'benchmark' flows to enable this validation.
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Affiliation(s)
- Christian Poelma
- Multiphase Systems (3ME-P&E), Delft University of Technology, Leeghwaterstraat 21, 2628 CA Delft, The Netherlands
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11
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Xie X, Li Y, Xie S. Computation of hemodynamics in eccentric coronary stenosis: A morphological parametric study. Technol Health Care 2018; 26:229-238. [PMID: 29660973 DOI: 10.3233/thc-160529] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Flow recirculation occurs in eccentric coronary stenosis, which can lead to adverse outcome. The complex local geodesic patterns of eccentric stenosis are critical factors in determining the flow characteristics in post-stenotic flow. OBJECTIVE The main objective of this study is to relate the relationship between the detailed morphological parameters in eccentric coronary stenosis and the post-stenotic flow characteristics. METHODS Several idealized eccentric coronary stenosis models with variable morphological parameters are created to conduct a series of computational fluid dynamics analysis. The impact of four specific lesion morphological parameters, eccentricity index (EI), diameter stenosis (DS), stenosis length (SL) and shape of lesion, are investigated. RESULTS When EI is small (< 0.33), the length of recirculation zones would increase as EI increase; while when EI is large (> 0.33), it would decreased as EI increase; Larger magnitude of retrograde flow occurs in models with smaller EIs. Both the recirculation zone length and maximum shear rate increase significantly as DS increases. Increase of SL will lead to increase of recirculation zone length. Higher maximum shear rate and larger recirculation zone are observed in models with sharper stenosis shape. CONCLUSIONS Except DS, the detailed geometry patterns (EI, SL and shape of the stenosis) also have great impact on post-stenotic flow behaviors in eccentric coronary stenosis.
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Hessenthaler A, Gaddum NR, Holub O, Sinkus R, Röhrle O, Nordsletten D. Experiment for validation of fluid-structure interaction models and algorithms. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33:e2848. [PMID: 27813272 PMCID: PMC5600002 DOI: 10.1002/cnm.2848] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 10/22/2016] [Accepted: 10/25/2016] [Indexed: 05/30/2023]
Abstract
In this paper a fluid-structure interaction (FSI) experiment is presented. The aim of this experiment is to provide a challenging yet easy-to-setup FSI test case that addresses the need for rigorous testing of FSI algorithms and modeling frameworks. Steady-state and periodic steady-state test cases with constant and periodic inflow were established. Focus of the experiment is on biomedical engineering applications with flow being in the laminar regime with Reynolds numbers 1283 and 651. Flow and solid domains were defined using computer-aided design (CAD) tools. The experimental design aimed at providing a straightforward boundary condition definition. Material parameters and mechanical response of a moderately viscous Newtonian fluid and a nonlinear incompressible solid were experimentally determined. A comprehensive data set was acquired by using magnetic resonance imaging to record the interaction between the fluid and the solid, quantifying flow and solid motion.
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Affiliation(s)
- A. Hessenthaler
- Institute of Applied Mechanics (CE)University of StuttgartPfaffenwaldring 770569 StuttgartGermany
| | - N. R. Gaddum
- Division of Imaging Sciences and Biomedical EngineeringKing's College London, 4th Floor, Lambeth Wing St. Thomas Hospital LondonSE1 7EHUK
| | - O. Holub
- Division of Imaging Sciences and Biomedical EngineeringKing's College London, 4th Floor, Lambeth Wing St. Thomas Hospital LondonSE1 7EHUK
| | - R. Sinkus
- Division of Imaging Sciences and Biomedical EngineeringKing's College London, 4th Floor, Lambeth Wing St. Thomas Hospital LondonSE1 7EHUK
| | - O. Röhrle
- Institute of Applied Mechanics (CE)University of StuttgartPfaffenwaldring 770569 StuttgartGermany
| | - D. Nordsletten
- Division of Imaging Sciences and Biomedical EngineeringKing's College London, 4th Floor, Lambeth Wing St. Thomas Hospital LondonSE1 7EHUK
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13
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Numerical Assessment of Novel Helical/Spiral Grafts with Improved Hemodynamics for Distal Graft Anastomoses. PLoS One 2016; 11:e0165892. [PMID: 27861485 PMCID: PMC5115668 DOI: 10.1371/journal.pone.0165892] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 10/19/2016] [Indexed: 11/19/2022] Open
Abstract
In the present work, numerical simulations were conducted for a typical end-to-side distal graft anastomosis to assess the effects of inducing secondary flow, which is believed to remove unfavourable flow environment. Simulations were carried out for four models, generated based on two main features of 'out-of-plane helicity' and 'spiral ridge' in the grafts as well as their combination. Following a qualitative comparison against in vitro data, various mean flow and hemodynamic parameters were compared and the results showed that helicity is significantly more effective in inducing swirling flow in comparison to a spiral ridge, while their combination could be even more effective. In addition, the induced swirling flow was generally found to be increasing the wall shear stress and reducing the flow stagnation and particle residence time within the anastomotic region and the host artery, which may be beneficial to the graft longevity and patency rates. Finally, a parametric study on the spiral ridge geometrical features was conducted, which showed that the ridge height and the number of spiral ridges have significant effects on inducing swirling flow, and revealed the potential of improving the efficiency of such designs.
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14
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Heidari Pahlavian S, Bunck AC, Thyagaraj S, Giese D, Loth F, Hedderich DM, Kröger JR, Martin BA. Accuracy of 4D Flow Measurement of Cerebrospinal Fluid Dynamics in the Cervical Spine: An In Vitro Verification Against Numerical Simulation. Ann Biomed Eng 2016; 44:3202-3214. [PMID: 27043214 PMCID: PMC5050060 DOI: 10.1007/s10439-016-1602-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 03/29/2016] [Indexed: 11/30/2022]
Abstract
Abnormal alterations in cerebrospinal fluid (CSF) flow are thought to play an important role in pathophysiology of various craniospinal disorders such as hydrocephalus and Chiari malformation. Three directional phase contrast MRI (4D Flow) has been proposed as one method for quantification of the CSF dynamics in healthy and disease states, but prior to further implementation of this technique, its accuracy in measuring CSF velocity magnitude and distribution must be evaluated. In this study, an MR-compatible experimental platform was developed based on an anatomically detailed 3D printed model of the cervical subarachnoid space and subject specific flow boundary conditions. Accuracy of 4D Flow measurements was assessed by comparison of CSF velocities obtained within the in vitro model with the numerically predicted velocities calculated from a spatially averaged computational fluid dynamics (CFD) model based on the same geometry and flow boundary conditions. Good agreement was observed between CFD and 4D Flow in terms of spatial distribution and peak magnitude of through-plane velocities with an average difference of 7.5 and 10.6% for peak systolic and diastolic velocities, respectively. Regression analysis showed lower accuracy of 4D Flow measurement at the timeframes corresponding to low CSF flow rate and poor correlation between CFD and 4D Flow in-plane velocities.
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Affiliation(s)
- Soroush Heidari Pahlavian
- Conquer Chiari Research Center, The University of Akron, Akron, OH, USA
- Department of Mechanical Engineering, The University of Akron, Akron, OH, USA
| | - Alexander C Bunck
- Department of Radiology, University Hospital of Cologne, Cologne, Germany
- Department of Radiology, University Hospital of Muenster, Muenster, Germany
| | - Suraj Thyagaraj
- Conquer Chiari Research Center, The University of Akron, Akron, OH, USA
- Department of Mechanical Engineering, The University of Akron, Akron, OH, USA
| | - Daniel Giese
- Department of Radiology, University Hospital of Cologne, Cologne, Germany
| | - Francis Loth
- Conquer Chiari Research Center, The University of Akron, Akron, OH, USA
- Department of Mechanical Engineering, The University of Akron, Akron, OH, USA
| | - Dennis M Hedderich
- Department of Radiology, University Hospital of Cologne, Cologne, Germany
| | - Jan Robert Kröger
- Department of Radiology, University Hospital of Muenster, Muenster, Germany
| | - Bryn A Martin
- Department of Biological Engineering, The University of Idaho, 875 Perimeter Drive MS 0904, Moscow, ID, 83844-0904, USA.
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15
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Hosotani K, Ono A, Takeuchi K, Hashiguchi Y, Nagahata T. Flow visualization of simple pipe and channel flows obtained by MRI time-slip method. J Vis (Tokyo) 2016. [DOI: 10.1007/s12650-016-0395-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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16
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Ren X, Qiao A, Song H, Song G, Jiao L. Influence of Bifurcation Angle on In-Stent Restenosis at the Vertebral Artery Origin: A Simulation Study of Hemodynamics. J Med Biol Eng 2016. [DOI: 10.1007/s40846-016-0155-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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17
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The Numerical Study of the Hemodynamic Characteristics in the Patient-Specific Intracranial Aneurysms before and after Surgery. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2016; 2016:4384508. [PMID: 27274764 PMCID: PMC4871964 DOI: 10.1155/2016/4384508] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Revised: 03/23/2016] [Accepted: 04/10/2016] [Indexed: 02/06/2023]
Abstract
The patient-specific pre- and postsurgery cerebral arterial geometries in the study were reconstructed from computed tomography angiography (CTA). Three-dimensional computational fluid dynamics models were used to investigate the hemodynamic phenomena in the cerebral arteries before and after surgery of the aneurysm under realistic conditions. CFD simulations for laminar flow of incompressible Newtonian fluid were conducted by using commercial software, ANSYS v15, with the rigid vascular wall assumption. The study found that the flow patterns with the complex vortical structures inside the aneurysm were similar. We also found that the inflow jet streams were coming strongly in aneurysm sac in the presurgery models, while the flow patterns in postsurgery models were quite different from those in presurgery models. The average wall shear stress after surgery for model 1 was approximately three times greater than that before surgery, while it was about twenty times greater for model 2. The area of low WSS in the daughter saccular aneurysm region in model 2 is associated with aneurysm rupture. Thus the distribution of WSS in aneurysm region provides useful prediction for the risk of aneurysm rupture.
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18
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A High Performance Pulsatile Pump for Aortic Flow Experiments in 3-Dimensional Models. Cardiovasc Eng Technol 2016; 7:148-58. [PMID: 26983961 DOI: 10.1007/s13239-016-0260-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 03/03/2016] [Indexed: 10/22/2022]
Abstract
Aortic pathologies such as coarctation, dissection, and aneurysm represent a particularly emergent class of cardiovascular diseases. Computational simulations of aortic flows are growing increasingly important as tools for gaining understanding of these pathologies, as well as for planning their surgical repair. In vitro experiments are required to validate the simulations against real world data, and the experiments require a pulsatile flow pump system that can provide physiologic flow conditions characteristic of the aorta. We designed a newly capable piston-based pulsatile flow pump system that can generate high volume flow rates (850 mL/s), replicate physiologic waveforms, and pump high viscosity fluids against large impedances. The system is also compatible with a broad range of fluid types, and is operable in magnetic resonance imaging environments. Performance of the system was validated using image processing-based analysis of piston motion as well as particle image velocimetry. The new system represents a more capable pumping solution for aortic flow experiments than other available designs, and can be manufactured at a relatively low cost.
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19
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Fan T, Lu Y, Gao Y, Meng J, Tan W, Huo Y, Kassab GS. Hemodynamics of left internal mammary artery bypass graft: Effect of anastomotic geometry, coronary artery stenosis, and postoperative time. J Biomech 2016; 49:645-652. [DOI: 10.1016/j.jbiomech.2016.01.031] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Revised: 01/02/2016] [Accepted: 01/28/2016] [Indexed: 01/22/2023]
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20
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Simulations of Magnetohemodynamics in Stenosed Arteries in Diabetic or Anemic Models. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2016; 2016:8123930. [PMID: 27057205 PMCID: PMC4785248 DOI: 10.1155/2016/8123930] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 01/11/2016] [Accepted: 01/19/2016] [Indexed: 11/18/2022]
Abstract
Pulsatile flow simulations of non-Newtonian blood flow in an axisymmetric multistenosed artery, subjected to a static magnetic field, are performed using FLUENT. The influence of artery size and magnetic field intensity on transient wall shear stress, mean shear stress, and pressure drop is investigated. Three different types of blood, namely, healthy, diabetic, and anemic are considered. It is found that using Newtonian viscosity model of blood in contrast to Carreau model underestimates the pressure drop and wall shear stress by nearly 34% and 40%, respectively. In addition, it is found that using a magnetic field increases the pressure drop by 15%. Generally, doubling the artery diameter reduces the wall shear stress approximately by 1.6 times. Also increasing the stenosis level from moderate to severe results in reduction of the shear stress by 1.6 times. Furthermore, doubling the diameter of moderately stenosed artery results in nearly 3-fold decrease in pressure drop. It is also found that diabetic blood results in higher shear stress and greater pressure drop in comparison to healthy blood, whereas anemic blood has a decreasing effect on both wall shear stress and pressure drop in comparison to healthy blood.
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21
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Syed H, Unnikrishnan VU, Olcmen S. Characteristics of time-varying intracranial pressure on blood flow through cerebral artery: A fluid–structure interaction approach. Proc Inst Mech Eng H 2015; 230:111-21. [DOI: 10.1177/0954411915619952] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 11/03/2015] [Indexed: 01/12/2023]
Abstract
Elevated intracranial pressure is a major contributor to morbidity and mortality in severe head injuries. Wall shear stresses in the artery can be affected by increased intracranial pressures and may lead to the formation of cerebral aneurysms. Earlier research on cerebral arteries and aneurysms involves using constant mean intracranial pressure values. Recent advancements in intracranial pressure monitoring techniques have led to measurement of the intracranial pressure waveform. By incorporating a time-varying intracranial pressure waveform in place of constant intracranial pressures in the analysis of cerebral arteries helps in understanding their effects on arterial deformation and wall shear stress. To date, such a robust computational study on the effect of increasing intracranial pressures on the cerebral arterial wall has not been attempted to the best of our knowledge. In this work, fully coupled fluid–structure interaction simulations are carried out to investigate the effect of the variation in intracranial pressure waveforms on the cerebral arterial wall. Three different time-varying intracranial pressure waveforms and three constant intracranial pressure profiles acting on the cerebral arterial wall are analyzed and compared with specified inlet velocity and outlet pressure conditions. It has been found that the arterial wall experiences deformation depending on the time-varying intracranial pressure waveforms, while the wall shear stress changes at peak systole for all the intracranial pressure profiles.
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Affiliation(s)
- Hasson Syed
- Department of Aerospace Engineering and Mechanics, The University of Alabama, Tuscaloosa, AL, USA
| | - Vinu U Unnikrishnan
- Department of Aerospace Engineering and Mechanics, The University of Alabama, Tuscaloosa, AL, USA
| | - Semih Olcmen
- Department of Aerospace Engineering and Mechanics, The University of Alabama, Tuscaloosa, AL, USA
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22
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DOUTEL E, CARNEIRO J, OLIVEIRA MSN, CAMPOS JBLM, MIRANDA JM. FABRICATION OF 3D MILI-SCALE CHANNELS FOR HEMODYNAMIC STUDIES. J MECH MED BIOL 2015. [DOI: 10.1142/s0219519415500049] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
3D mili-scale channel representing simplified anatomical models of blood vessels were constructed in polidimethylsiloxane (PDMS). The objective was to obtain a sequential method to fabricate transparent PDMS models from a mold produced by rapid prototyping. For this purpose, two types of casting methods were compared, a known lost-wax casting method and a casting method using sucrose. The channels fabricated by both casting methods were analyzed by Optical Microscopy, Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). The lost-wax method is not ideal since the channels become contaminated during the removal process. The models produced with the lost-sucrose casting method exhibit much better optical characteristics. These models are transparent with no visible contamination, since the removing process is done by dissolution at room temperature rather than melting. They allow for good optical access for flow visualization and measurement of the velocity field by micro-Particle Image Velocimetry (μPIV). The channels fabricated by the lost-sucrose casting method were shown to be suitable for future hemodynamic studies using optical techniques.
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Affiliation(s)
- E. DOUTEL
- Centro de Estudos de Fenómenos de Transporte, Departamento de Engenharia Química, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
| | - J. CARNEIRO
- Centro de Estudos de Fenómenos de Transporte, Departamento de Engenharia Química, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
| | - M. S. N. OLIVEIRA
- Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow G1 1XJ, UK
| | - J. B. L. M. CAMPOS
- Centro de Estudos de Fenómenos de Transporte, Departamento de Engenharia Química, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
| | - J. M. MIRANDA
- Centro de Estudos de Fenómenos de Transporte, Departamento de Engenharia Química, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal
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23
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Chaudhury RA, Herrmann M, Frakes DH, Adrian RJ. Length and time for development of laminar flow in tubes following a step increase of volume flux. EXPERIMENTS IN FLUIDS 2015; 56:22. [DOI: 10.1007/s00348-014-1886-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/19/2023]
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24
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Xie X, Wang Y, Zhu H, Zhou J. Computation of Hemodynamics in Tortuous Left Coronary Artery: A Morphological Parametric Study. J Biomech Eng 2014; 136:101006. [PMID: 25048524 DOI: 10.1115/1.4028052] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 07/22/2014] [Indexed: 12/13/2022]
Abstract
Coronary tortuosity (CT) would alter the local wall shear stress (WSS) and may become a risk factor for atherosclerosis. Here we performed a systematic computational study to relate CT morphological parameters to abnormal WSS, which is a predisposing factor to the formation of atherosclerotic lesions. Several idealized left coronary artery (LCA) models were created to conduct a series of morphological parametric studies, in which we concentrate on three specific morphological parameters, the center line radius (CLR), the bend angle (BA), and the length between two adjust bends (LBB). The time averaged WSS (TAWSS), the oscillatory shear index (OSI), and the time averaged WSS gradient (WSSGnd) were explored by using the computational fluid dynamics (CFD) method, in order to determine susceptible sites for the onset of early atherosclerosis. In addition, two realistic LCA models were reconstructed to further validate the finding's credibility. The CLR and LBB had great impact on the distributions of WSS-derived parameters, while the BA had minor impact on the hemodynamic of the tortuous arteries. Abnormal regions with low TAWSS (TAWSS < 0.5 Pa), high OSI (OSI > 0.1) and high WSSGnd (WSSGnd > 8) were observed at the inner wall of bend sections in the models with small CLR or small LBB. These findings were also confirmed in the realistic models. Severe CT with small CLR or LBB would lead to the formation of abnormal WSS regions at the bend sections and providing these regions with favorable conditions for the onset and/or progression of atherosclerosis.
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Affiliation(s)
- Xinzhou Xie
- Department of Electronic Engineering, Fudan University, Shanghai 200433, China e-mail:
| | - Yuanyuan Wang
- Department of Electronic Engineering, Fudan University, Shanghai 200433, China
- Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention of Shanghai, Shanghai 200433, China e-mail:
| | - Hongmin Zhu
- Department of Cardiology, Sixth People's Hospital, Jiao Tong University, Shanghai 200233, China e-mail:
| | - Jingmin Zhou
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai 200032, China e-mail:
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25
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Kung E, Kahn AM, Burns JC, Marsden A. In Vitro Validation of Patient-Specific Hemodynamic Simulations in Coronary Aneurysms Caused by Kawasaki Disease. Cardiovasc Eng Technol 2014; 5:189-201. [PMID: 25050140 DOI: 10.1007/s13239-014-0184-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
To perform experimental validation of computational fluid dynamics (CFD) applied to patient specific coronary aneurysm anatomy of Kawasaki disease. We quantified hemodynamics in a patient-specific coronary artery aneurysm physical phantom under physiologic rest and exercise flow conditions. Using phase contrast MRI (PCMRI), we acquired 3-component flow velocity at two slice locations in the aneurysms. We then performed numerical simulations with the same geometry and inflow conditions, and performed qualitative and quantitative comparisons of velocities between experimental measurements and simulation results. We observed excellent qualitative agreement in flow pattern features. The quantitative spatially and temporally varying differences in velocity between PCMRI and CFD were proportional to the flow velocity. As a result, the percent discrepancy between simulation and experiment was relatively constant regardless of flow velocity variations. Through 1D and 2D quantitative comparisons, we found a 5-17% difference between measured and simulated velocities. Additional analysis assessed wall shear stress differences between deformable and rigid wall simulations. This study demonstrated that CFD produced good qualitative and quantitative predictions of velocities in a realistic coronary aneurysm anatomy under physiological flow conditions. The results provide insights on factors that may influence the level of agreement, and a set of in vitro experimental data that can be used by others to compare against CFD simulation results. The findings of this study increase confidence in the use of CFD for investigating hemodynamics in the specialized anatomy of coronary aneurysms. This provides a basis for future hemodynamics studies in patient-specific models of Kawasaki disease.
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Affiliation(s)
- Ethan Kung
- Mechanical and Aerospace Engineering Department, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0411, USA
| | - Andrew M Kahn
- Departments of Medicine and Pediatrics, University of California San Diego School of Medicine, San Diego, CA, USA
| | - Jane C Burns
- Departments of Medicine and Pediatrics, University of California San Diego School of Medicine, San Diego, CA, USA ; Kawasaki Disease Research Center, Rady Children's Hospital, San Diego, CA, USA
| | - Alison Marsden
- Mechanical and Aerospace Engineering Department, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0411, USA
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26
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GAO ZHEN, YANG LIN, LU GANG, DAI PEIDONG, ZHANG XIAOLONG, ZHANG TIANYU, CHI FANGLU. A PARAMETRIC NUMERICAL INVESTIGATION OF LOCAL HAEMODYNAMICS IN THE END-TO-SIDE ANASTOMOSIS OF CERVICAL-TO-PETROUS BYPASS BASED ON REAL GEOMETRY OF INTERNAL CAROTID ARTERY. J MECH MED BIOL 2014. [DOI: 10.1142/s0219519414500201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bypass reconstructed from the cervical segment of internal carotid artery (ICA) to its petrous segment allows high-volume bypass flow without any risk of intracranial dissection. The purpose of this study was to investigate the geometric effect on the end-to-side anastomosis of cervical-to-petrous bypass, for its close relationship to local haemodynamic and the long-term performance of bypass. We focused on two controllable geometric parameters: diameter ratio (Φ) and angle (α) between the graft and host arteries. Different models covering a range of Φ (0.75, 1 and 1.25) and α (30°, 45°, 60° and 90°) were constructed based on real geometry of human ICA. Numerical simulations of blood flow were performed in physiological flow condition. The flow patterns, flow distributions, time-average wall shear stress (TAWSS) and oscillatory shear index (OSI) in different models were compared. Our results showed geometric factors have influence on both the local haemodynamic parameters and the flow velocity through downstream branches. Of models with different geometric parameters, the model with Φ ≥ 1 or α = 45° were the most optimized considering haemodynamic performance.
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Affiliation(s)
- ZHEN GAO
- Department of Otology & Skull Base Surgery, Eye and ENT Hospital, Fudan University, Shanghai 200031, China
| | - LIN YANG
- Research Center, Eye and ENT Hospital, Fudan University, Shanghai 200031, China
| | - GANG LU
- Department of Radiography, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - PEI-DONG DAI
- Research Center, Eye and ENT Hospital, Fudan University, Shanghai 200031, China
| | - XIAO-LONG ZHANG
- Department of Radiography, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - TIAN-YU ZHANG
- Department of Otology & Skull Base Surgery, Eye and ENT Hospital, Fudan University, Shanghai 200031, China
| | - FANG-LU CHI
- Department of Otology & Skull Base Surgery, Eye and ENT Hospital, Fudan University, Shanghai 200031, China
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27
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Lee CJ, Srinivas K, Qian Y. Three-dimensional hemodynamic design optimization of stents for cerebral aneurysms. Proc Inst Mech Eng H 2014; 228:213-24. [DOI: 10.1177/0954411914523405] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Flow-diverting stents occlude aneurysms by diverting the blood flow from entering the aneurysm sac. Their effectiveness is determined by the thrombus formation rate, which depends greatly on stent design. The aim of this study was to provide a general framework for efficient stent design using design optimization methods, with a focus on stent hemodynamics as the starting point. Kriging method was used for completing design optimization. Three different cases of idealized stents were considered, and 40–60 samples from each case were evaluated using computational fluid dynamics. Using maximum velocity and vorticity reduction as objective functions, the optimized designs were identified from the samples. A number of optimized stent designs have been found from optimization, which revealed that a combination of high pore density and thin struts is desired. Additionally, distributing struts near the proximal end of aneurysm neck was found to be effective. The success of the methods and framework devised in this study offers a future possibility of incorporating other disciplines to carry out multidisciplinary design optimization.
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Affiliation(s)
- Chang-Joon Lee
- The Australian School of Advanced Medicine, Macquarie University, Sydney, NSW, Australia
| | - Karkenahalli Srinivas
- The Australian School of Advanced Medicine, Macquarie University, Sydney, NSW, Australia
| | - Yi Qian
- The Australian School of Advanced Medicine, Macquarie University, Sydney, NSW, Australia
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28
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Lee CJ, Zhang Y, Takao H, Murayama Y, Qian Y. A fluid-structure interaction study using patient-specific ruptured and unruptured aneurysm: the effect of aneurysm morphology, hypertension and elasticity. J Biomech 2013; 46:2402-10. [PMID: 23962529 DOI: 10.1016/j.jbiomech.2013.07.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 07/17/2013] [Accepted: 07/18/2013] [Indexed: 10/26/2022]
Abstract
Fluid-structure interaction (FSI) simulations using five patient-specific aneurysm geometries are carried out to investigate the difference between ruptured and unruptured aneurysms. Two different blood pressure conditions (normal and hypertension, for all cases), and two different values of elastic modulus (1 and 2MPa, for two cases) are tested. Ruptured aneurysms (RA) generally displayed larger displacement at the dome, lower area-average WSS and higher von Mises stress than unruptured aneurysms (URA) regardless of elasticity or blood pressure condition. RAs had a longitudinal expansion whereas URAs had a radial expansion, which was the key difference between the two types. The difference in expansion pattern may be one of the keys to explaining aneurysm rupture, and further analysis is required in the future to confirm this theory.
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Affiliation(s)
- C J Lee
- The Australian School of Advanced Medicine, Macquarie University, Sydney, Australia
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29
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Carr IA, Nemoto N, Schwartz RS, Shadden SC. Size-dependent predilections of cardiogenic embolic transport. Am J Physiol Heart Circ Physiol 2013; 305:H732-9. [PMID: 23792681 DOI: 10.1152/ajpheart.00320.2013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
While it is intuitively clear that aortic anatomy and embolus size could be important determinants for cardiogenic embolic stroke risk and stroke location, few data exist confirming or characterizing this hypothesis. The objective of this study is to use medical imaging and computational modeling to better understand if aortic anatomy and embolus size influence predilections for cardiogenic embolic transport and right vs. left hemisphere propensity. Anatomically accurate models of the human aorta and branch arteries to the head were reconstructed from computed tomography (CT) angiography of 10 patients. Blood flow was modeled by the Navier-Stokes equations using a well-validated flow solver with physiologic inflow and boundary conditions. Embolic particulate was released from the aortic root and tracked through the common carotid and vertebral arteries for a range of particle sizes. Cardiogenic emboli reaching the carotid and vertebral arteries appeared to have a strong size-destination relationship that varied markedly from expectations based on blood distribution. Observed trends were robust to modeling parameters. A patient's aortic anatomy appeared to significantly influence the probability a cardiogenic particle becomes embolic to the head. Right hemisphere propensity appeared dominant for cardiogenic emboli, which has been confirmed clinically. The predilections discovered through this modeling could represent an important mechanism underlying cardiogenic embolic stroke etiology.
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Affiliation(s)
- Ian A Carr
- Mechanical, Materials and Aerospace Engineering, Illinois Institute of Technology, Chicago, Illionis
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Xie X, Wang Y, Zhou H. Impact of coronary tortuosity on the coronary blood flow: a 3D computational study. J Biomech 2013; 46:1833-41. [PMID: 23777815 DOI: 10.1016/j.jbiomech.2013.05.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 04/22/2013] [Accepted: 05/07/2013] [Indexed: 01/11/2023]
Abstract
Tortuous coronary arteries are commonly observed but the etiology and clinical importance are still unclear. Hemodynamic factors are vital modulators of the vascular structure and a full understanding of hemodynamic changes caused by the coronary tortuosity (CT) is meaningful for clinical researches. A three-dimensional computational fluid dynamic study was conducted to evaluate hemodynamic changes caused by the CT. Six idealized small sections of the left anterior descending coronary artery (LAD) with different levels of tortuosity were employed. The dynamic vessel motion was added to the three-dimensional tortuous coronary models to make the computational results more realistic. The rest and exercise conditions were modeled by specifying proper boundary conditions. Results showed that a low and oscillated wall shear stress (WSS) region was formed at the inner wall downstream of the bend section when the bend angle was larger than 120°. The resistance of the coronary arteries increased up to 92% due to the CT during exercise. A maximum increase of 96% was observed in the mean diastole driving pressure for the CT model as compared to the non-tortuous model during exercise. This study indicated that the severe CT may be a risk factor for atherosclerosis and may make the regulation of the blood flow ineffective during exercise.
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Affiliation(s)
- Xinzhou Xie
- Department of Electronic Engineering, Fudan University, No. 220 Handan Road, Shanghai, China
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Lee CJ, Zhang Y, Takao H, Murayama Y, Qian Y. The influence of elastic upstream artery length on fluid-structure interaction modeling: a comparative study using patient-specific cerebral aneurysm. Med Eng Phys 2013; 35:1377-84. [PMID: 23664305 DOI: 10.1016/j.medengphy.2013.03.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 01/15/2013] [Accepted: 03/13/2013] [Indexed: 10/26/2022]
Abstract
Fluid-structure interaction (FSI) simulations using a patient-specific geometry are carried out to investigate the influence the length of elastic parent artery and the position of constraints in the solid domain on the accuracy of patient-specific FSI simulations. Three models are tested: Long, Moderate, and Short, based on the length of the elastic parent artery. All three models use same wall thickness (0.5 mm) and the elastic modulus (5 MPa). The maximum mesh displacement is the largest for the Long model (0.491 mm) compared to other models (0.3 mm for Moderate, and 0.132 mm for Short). The differences of hemodynamic and mechanical variables, aneurysm volume and cross-sectional area between three models are all found to be minor. In addition, the Short model takes the least amount of computing time of the three models (11h compared to 21 h for Long and 19 h for Moderate). The present results indicate that the use of short elastic upstream artery can shorten the time required for pati ent-specific FSI simulations without impacting the overall accuracy of the results.
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Affiliation(s)
- C J Lee
- The Australian School of Advanced Medicine, Macquarie University, Sydney, Australia
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Knobloch V, Binter C, Gülan U, Sigfridsson A, Holzner M, Lüthi B, Kozerke S. Mapping mean and fluctuating velocities by Bayesian multipoint MR velocity encoding-validation against 3D particle tracking velocimetry. Magn Reson Med 2013; 71:1405-15. [PMID: 23670993 DOI: 10.1002/mrm.24785] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 03/01/2013] [Accepted: 04/04/2013] [Indexed: 11/06/2022]
Abstract
PURPOSE To validate Bayesian multipoint MR velocity encoding against particle tracking velocimetry for measuring velocity vector fields and fluctuating velocities in a realistic aortic model. METHODS An elastic cast of a human aortic arch equipped with an 80 or 64% stenotic section was driven by a pulsatile pump. Peak velocities and peak turbulent kinetic energies of more than 3 m/s and 1000 J/m(3) could be generated. Velocity vector fields and fluctuating velocities were assessed using Bayesian multipoint MR velocity encoding with varying numbers of velocity encoding points and particle tracking velocimetry in the ascending aorta. RESULTS Velocities and turbulent kinetic energies measured with 5-fold k-t undersampled 10-point MR velocity encoding and particle tracking velocimetry were found to reveal good correlation with mean differences of -4.8 ± 13.3 cm/s and r(2) = 0.98 for velocities and -21.8 ± 53.9 J/m(3) and r(2) = 0.98 for turbulent kinetic energies, respectively. Three-dimensional velocity patterns of fast flow downstream of the stenoses and regions of elevated velocity fluctuations were found to agree well. CONCLUSION Accelerated Bayesian multipoint MR velocity encoding has been demonstrated to be accurate for assessing mean and fluctuating velocities against the reference standard particle tracking velocimetry. The MR method holds considerable potential to map velocity vector fields and turbulent kinetic energies in clinically feasible exam times of <15 min.
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Affiliation(s)
- Verena Knobloch
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
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34
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Bockman MD, Kansagra AP, Shadden SC, Wong EC, Marsden AL. Fluid Mechanics of Mixing in the Vertebrobasilar System: Comparison of Simulation and MRI. Cardiovasc Eng Technol 2012. [DOI: 10.1007/s13239-012-0112-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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35
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Owida AA, Do H, Morsi YS. Numerical analysis of coronary artery bypass grafts: an over view. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2012; 108:689-705. [PMID: 22217920 DOI: 10.1016/j.cmpb.2011.12.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 09/19/2011] [Accepted: 12/10/2011] [Indexed: 05/31/2023]
Abstract
Arterial bypass grafts tend to fail after some years due to the development of intimal thickening (restenosis). Non-uniform hemodynamics following a bypass operation contributes to restenosis and bypass failure can occur due to the focal development of anastomotic intimal hyperplasia. Additionally, surgical injury aggravated by compliance mismatch between the graft and artery has been suggested as an initiating factor for progress of wall thickening along the suture line Vascular grafts that are small in diameter tend to occlude rapidly. Computational fluid dynamics (CFD) methods have been effectively used to simulate the physical and geometrical parameters characterizing the hemodynamics of various arteries and bypass configurations. The effects of such changes on the pressure and flow characteristics as well as the wall shear stress during a cardiac cycle can be simulated. Recently, utilization of fluid and structure interactions have been used to determine fluid flow parameters and structure forces including stress and strains relationships under steady and transient conditions. In parallel to this, experimental diagnostics techniques such as Laser Doppler Anemometry, Particle Image Velocimetry, Doppler Guide wire and Magnetic Resonance Imaging have been used to provide essential information and to validate the numerical results. Moreover, clinical imaging techniques such as magnetic resonance or computed tomography have assisted considerably in gaining a detailed patient-specific picture of the blood flow and structure dynamics. This paper gives a review of recent numerical investigations of various configurations of coronary artery bypass grafts (CABG). In addition, the paper ends with a summary of the findings and the future directions.
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Affiliation(s)
- Amal Ahmed Owida
- Biomechanics and Tissue Engineering Group, Swinburne University of Technology, Hawthorn, Melbourne, Victoria, Australia
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36
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Marshall I. Targeted particle tracking in computational models of human carotid bifurcations. J Biomech Eng 2012; 133:124501. [PMID: 22206428 DOI: 10.1115/1.4005470] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A significant and largely unsolved problem of computational fluid dynamics (CFD) simulation of flow in anatomically relevant geometries is that very few calculated pathlines pass through regions of complex flow. This in turn limits the ability of CFD-based simulations of imaging techniques (such as MRI) to correctly predict in vivo performance. In this work, I present two methods designed to overcome this filling problem, firstly, by releasing additional particles from areas of the flow inlet that lead directly to the complex flow region ("preferential seeding") and, secondly, by tracking particles both "downstream" and "upstream" from seed points within the complex flow region itself. I use the human carotid bifurcation as an example of complex blood flow that is of great clinical interest. Both idealized and healthy volunteer geometries are investigated. With uniform seeding in the inlet plane (in the common carotid artery (CCA)) of an idealized bifurcation geometry, approximately half the particles passed through the internal carotid artery (ICA) and half through the external carotid artery. However, of those particles entering the ICA, only 16% passed directly through the carotid bulb region. Preferential seeding from selected regions of the CCA was able to increase this figure to 47%. In the second method, seeding of particles within the carotid bulb region itself led to a very high proportion (97%) of pathlines running from CCA to ICA. Seeding of particles in the bulb plane of three healthy volunteer carotid bifurcation geometries led to much better filling of the bulb regions than by particles seeded at the inlet alone. In all cases, visualization of the origin and behavior of recirculating particles led to useful insights into the complex flow patterns. Both seeding methods produced significant improvements in filling the carotid bulb region with particle tracks compared with uniform seeding at the inlet and led to an improved understanding of the complex flow patterns. The methods described may be combined and are generally applicable to CFD studies of fluid and gas flow and are, therefore, of relevance in hemodynamics, respiratory mechanics, and medical imaging science.
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Affiliation(s)
- Ian Marshall
- Medical Physics and Medical Engineering, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, EH16 5SB, UK.
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Markl M, Geiger J, Jung B, Hirtler D, Arnold R. Noninvasive evaluation of 3D hemodynamics in a complex case of single ventricle physiology. J Magn Reson Imaging 2012; 35:933-7. [PMID: 22271353 DOI: 10.1002/jmri.22861] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 09/30/2011] [Indexed: 11/08/2022] Open
Abstract
We report the comprehensive evaluation of the complex hemodynamics in a rare case of a pediatric patient after repair of congenital heart disease with multiple abnormalities including hypoplastic left heart, double outlet right ventricle, transposition of great arteries, ventricular septal defect, aortic coarctation, and total cavopulmonary connection. Based on a single measurement, whole-heart flow-sensitive 4D magnetic resonance imaging (MRI) was able to demonstrate a number of regional flow alterations such as poststenotic helix formation and asymmetric flow distributions for the double arterial outlet and to the left and right lungs. Our findings illustrate the potential role of flow-sensitive 4D MRI as a noninvasive and radiation-free technique for the frequent postinterventional follow-up in these pediatric patients.
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Affiliation(s)
- Michael Markl
- Department of Radiology, Medical Physics, University Medical Center, Freiburg, Germany.
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Torii R, Xu XY, El-Hamamsy I, Mohiaddin R, Yacoub MH. Computational biomechanics of the aortic root. ACTA ACUST UNITED AC 2011. [DOI: 10.5339/ahcsps.2011.16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Ryo Torii
- 1Qatar Cardiovascular Research Center, Doha,
Qatar
- 2Harefield Heart Science Centre, Imperial College London, Harefield,
UK
- 5Department of Chemical Engineering,
Imperial College London, London, UK
| | - Xiao Yun Xu
- 5Department of Chemical Engineering,
Imperial College London, London, UK
| | - Ismail El-Hamamsy
- 4Department of Cardiac Surgery, Montreal
Heart Institute, Montreal, Canada
| | - Raad Mohiaddin
- 3Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital and
Imperial College London, London, UK
| | - Magdi H. Yacoub
- 1Qatar Cardiovascular Research Center, Doha,
Qatar
- 2Harefield Heart Science Centre, Imperial College London, Harefield,
UK
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In vivo validation of numerical prediction for turbulence intensity in an aortic coarctation. Ann Biomed Eng 2011; 40:860-70. [PMID: 22016327 DOI: 10.1007/s10439-011-0447-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Accepted: 10/13/2011] [Indexed: 10/16/2022]
Abstract
This paper compares numerical predictions of turbulence intensity with in vivo measurement. Magnetic resonance imaging (MRI) was carried out on a 60-year-old female with a restenosed aortic coarctation. Time-resolved three-directional phase-contrast (PC) MRI data was acquired to enable turbulence intensity estimation. A contrast-enhanced MR angiography (MRA) and a time-resolved 2D PCMRI measurement were also performed to acquire data needed to perform subsequent image-based computational fluid dynamics (CFD) modeling. A 3D model of the aortic coarctation and surrounding vasculature was constructed from the MRA data, and physiologic boundary conditions were modeled to match 2D PCMRI and pressure pulse measurements. Blood flow velocity data was subsequently obtained by numerical simulation. Turbulent kinetic energy (TKE) was computed from the resulting CFD data. Results indicate relative agreement (error ≈10%) between the in vivo measurements and the CFD predictions of TKE. The discrepancies in modeled vs. measured TKE values were within expectations due to modeling and measurement errors.
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40
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Kung EO, Les AS, Medina F, Wicker RB, McConnell MV, Taylor CA. In vitro validation of finite-element model of AAA hemodynamics incorporating realistic outlet boundary conditions. J Biomech Eng 2011; 133:041003. [PMID: 21428677 DOI: 10.1115/1.4003526] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The purpose of this study is to validate numerical simulations of flow and pressure in an abdominal aortic aneurysm (AAA) using phase-contrast magnetic resonance imaging (PCMRI) and an in vitro phantom under physiological flow and pressure conditions. We constructed a two-outlet physical flow phantom based on patient imaging data of an AAA and developed a physical Windkessel model to use as outlet boundary conditions. We then acquired PCMRI data in the phantom while it operated under conditions mimicking a resting and a light exercise physiological state. Next, we performed in silico numerical simulations and compared experimentally measured velocities, flows, and pressures in the in vitro phantom to those computed in the in silico simulations. There was a high degree of agreement in all of the pressure and flow waveform shapes and magnitudes between the experimental measurements and simulated results. The average pressures and flow split difference between experiment and simulation were all within 2%. Velocity patterns showed good agreement between experimental measurements and simulated results, especially in the case of whole-cycle averaged comparisons. We demonstrated methods to perform in vitro phantom experiments with physiological flows and pressures, showing good agreement between numerically simulated and experimentally measured velocity fields and pressure waveforms in a complex patient-specific AAA geometry.
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Affiliation(s)
- Ethan O Kung
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
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Kung EO, Les AS, Figueroa CA, Medina F, Arcaute K, Wicker RB, McConnell MV, Taylor CA. In vitro validation of finite element analysis of blood flow in deformable models. Ann Biomed Eng 2011; 39:1947-60. [PMID: 21404126 DOI: 10.1007/s10439-011-0284-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Accepted: 02/21/2011] [Indexed: 11/26/2022]
Abstract
The purpose of this article is to validate numerical simulations of flow and pressure incorporating deformable walls using in vitro flow phantoms under physiological flow and pressure conditions. We constructed two deformable flow phantoms mimicking a normal and a restricted thoracic aorta, and used a Windkessel model at the outlet boundary. We acquired flow and pressure data in the phantom while it operated under physiological conditions. Next, in silico numerical simulations were performed, and velocities, flows, and pressures in the in silico simulations were compared to those measured in the in vitro phantoms. The experimental measurements and simulated results of pressure and flow waveform shapes and magnitudes compared favorably at all of the different measurement locations in the two deformable phantoms. The average difference between measured and simulated flow and pressure was approximately 3.5 cc/s (13% of mean) and 1.5 mmHg (1.8% of mean), respectively. Velocity patterns also showed good qualitative agreement between experiment and simulation especially in regions with less complex flow patterns. We demonstrated the capabilities of numerical simulations incorporating deformable walls to capture both the vessel wall motion and wave propagation by accurately predicting the changes in the flow and pressure waveforms at various locations down the length of the deformable flow phantoms.
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Affiliation(s)
- Ethan O Kung
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, CA 94305, USA
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Development of A Physical Windkessel Module to Re-Create In-Vivo Vascular Flow Impedance for In-Vitro Experiments. Cardiovasc Eng Technol 2010; 2:2-14. [PMID: 26316899 DOI: 10.1007/s13239-010-0030-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE To create and characterize a physical Windkessel module that can provide realistic and predictable vascular impedances for in-vitro flow experiments used for computational fluid dynamics validation, and other investigations of the cardiovascular system and medical devices. METHODS We developed practical design and manufacturing methods for constructing flow resistance and capacitance units. Using these units we assembled a Windkessel impedance module and defined its corresponding analytical model incorporating an inductance to account for fluid momentum. We tested various resistance units and Windkessel modules using a flow system, and compared experimental measurements to analytical predictions of pressure, flow, and impedance. RESULTS The resistance modules exhibited stable resistance values over wide ranges of flow rates. The resistance value variations of any particular resistor are typically within 5% across the range of flow that it is expected to accommodate under physiologic flow conditions. In the Windkessel impedance modules, the measured flow and pressure waveforms agreed very favorably with the analytical calculations for four different flow conditions used to test each module. The shapes and magnitudes of the impedance modulus and phase agree well between experiment and theoretical values, and also with those measured in-vivo in previous studies. CONCLUSIONS The Windkessel impedance module we developed can be used as a practical tool to provide realistic vascular impedance for in-vitro cardiovascular studies. Upon proper characterization of the impedance module, its analytical model can accurately predict its measured behavior under different flow conditions.
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Markl M, Wegent F, Zech T, Bauer S, Strecker C, Schumacher M, Weiller C, Hennig J, Harloff A. In Vivo Wall Shear Stress Distribution in the Carotid Artery. Circ Cardiovasc Imaging 2010; 3:647-55. [PMID: 20847189 DOI: 10.1161/circimaging.110.958504] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Michael Markl
- From the Department of Radiology (M.M., S.B., J.H.), Medical Physics; Department of Neurology (F.W., T.Z., C.S., C.W., A.H.); and Department of Neuroradiology (M.S.), University Hospital Freiburg, Freiburg, Germany
| | - Felix Wegent
- From the Department of Radiology (M.M., S.B., J.H.), Medical Physics; Department of Neurology (F.W., T.Z., C.S., C.W., A.H.); and Department of Neuroradiology (M.S.), University Hospital Freiburg, Freiburg, Germany
| | - Timo Zech
- From the Department of Radiology (M.M., S.B., J.H.), Medical Physics; Department of Neurology (F.W., T.Z., C.S., C.W., A.H.); and Department of Neuroradiology (M.S.), University Hospital Freiburg, Freiburg, Germany
| | - Simon Bauer
- From the Department of Radiology (M.M., S.B., J.H.), Medical Physics; Department of Neurology (F.W., T.Z., C.S., C.W., A.H.); and Department of Neuroradiology (M.S.), University Hospital Freiburg, Freiburg, Germany
| | - Christoph Strecker
- From the Department of Radiology (M.M., S.B., J.H.), Medical Physics; Department of Neurology (F.W., T.Z., C.S., C.W., A.H.); and Department of Neuroradiology (M.S.), University Hospital Freiburg, Freiburg, Germany
| | - Martin Schumacher
- From the Department of Radiology (M.M., S.B., J.H.), Medical Physics; Department of Neurology (F.W., T.Z., C.S., C.W., A.H.); and Department of Neuroradiology (M.S.), University Hospital Freiburg, Freiburg, Germany
| | - Cornelius Weiller
- From the Department of Radiology (M.M., S.B., J.H.), Medical Physics; Department of Neurology (F.W., T.Z., C.S., C.W., A.H.); and Department of Neuroradiology (M.S.), University Hospital Freiburg, Freiburg, Germany
| | - Jürgen Hennig
- From the Department of Radiology (M.M., S.B., J.H.), Medical Physics; Department of Neurology (F.W., T.Z., C.S., C.W., A.H.); and Department of Neuroradiology (M.S.), University Hospital Freiburg, Freiburg, Germany
| | - Andreas Harloff
- From the Department of Radiology (M.M., S.B., J.H.), Medical Physics; Department of Neurology (F.W., T.Z., C.S., C.W., A.H.); and Department of Neuroradiology (M.S.), University Hospital Freiburg, Freiburg, Germany
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Kumar A, Patton DJ, Friedrich MG. The emerging clinical role of cardiovascular magnetic resonance imaging. Can J Cardiol 2010; 26:313-22. [PMID: 20548977 DOI: 10.1016/s0828-282x(10)70396-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Starting as a research method little more than a decade ago, cardiovascular magnetic resonance (CMR) imaging has rapidly evolved to become a powerful diagnostic tool used in routine clinical cardiology. The contrast in CMR images is generated from protons in different chemical environments and, therefore, enables high-resolution imaging and specific tissue characterization in vivo, without the use of potentially harmful ionizing radiation.CMR imaging is used for the assessment of regional and global ventricular function, and to answer questions regarding anatomy. State-of-the-art CMR sequences allow for a wide range of tissue characterization approaches, including the identification and quantification of nonviable, edematous, inflamed, infiltrated or hypoperfused myocardium. These tissue changes are not only used to help identify the etiology of cardiomyopathies, but also allow for a better understanding of tissue pathology in vivo. CMR tissue characterization may also be used to stage a disease process; for example, elevated T2 signal is consistent with edema and helps differentiate acute from chronic myocardial injury, and the extent of myocardial fibrosis as imaged by contrast-enhanced CMR correlates with adverse patient outcome in ischemic and nonischemic cardiomyopathies.The current role of CMR imaging in clinical cardiology is reviewed, including coronary artery disease, congenital heart disease, nonischemic cardiomyopathies and valvular disease.
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Affiliation(s)
- Andreas Kumar
- Stephenson CMR Centre at the Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
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45
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Tuning Multidomain Hemodynamic Simulations to Match Physiological Measurements. Ann Biomed Eng 2010; 38:2635-48. [DOI: 10.1007/s10439-010-0011-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Accepted: 03/11/2010] [Indexed: 10/19/2022]
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46
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Les AS, Yeung JJ, Schultz GM, Herfkens RJ, Dalman RL, Taylor CA. Supraceliac and Infrarenal Aortic Flow in Patients with Abdominal Aortic Aneurysms: Mean Flows, Waveforms, and Allometric Scaling Relationships. Cardiovasc Eng Technol 2010; 1. [PMID: 24324530 DOI: 10.1007/s13239-010-0004-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE Hemodynamic forces are thought to play a critical role in abdominal aortic aneurysm (AAA) growth. In silico and in vitro simulations can be used to study these forces, but require accurate aortic geometries and boundary conditions. Many AAA simulations use patient-specific geometries, but utilize inlet boundary conditions taken from a single, unrelated, healthy young adult. METHODS In this study, we imaged 43 AAA patients using a 1.5 T MR scanner. A 24-frame cardiac-gated one-component phase-contrast magnetic resonance imaging sequence was used to measure volumetric flow at the supraceliac (SC) and infrarenal (IR) aorta, where flow information is typically needed for simulation. For the first 36 patients, individual waveforms were interpolated to a 12-mode Fourier curve, peak-aligned, and averaged. Allometric scaling equations were derived from log-log plots of mean SC and IR flow vs. body mass, height, body surface area (BSA), and fat-free body mass. The data from the last seven patients were used to validate our model. RESULTS Both the SC and IR averaged waveforms had the biphasic shapes characteristic of older adults, and mean SC and IR flows over the cardiac cycle were 51.2 ± 10.3 and 17.5 ± 5.44 mL/s, respectively. Linear regression of the log-log plots revealed that BSA was most strongly predictive of mean SC (R2 = 0.29) and IR flow (R2 = 0.19), with the highest combined R2. When averaged, the measured and predicted waveforms for the last seven patients agreed well. CONCLUSIONS We present a method to estimate SC and IR mean flows and waveforms for AAA simulation.
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Affiliation(s)
- Andrea S Les
- Department of Bioengineering, Stanford University, Stanford, CA, USA
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47
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Taylor CA, Steinman DA. Image-Based Modeling of Blood Flow and Vessel Wall Dynamics: Applications, Methods and Future Directions. Ann Biomed Eng 2010; 38:1188-203. [DOI: 10.1007/s10439-010-9901-0] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 01/02/2010] [Indexed: 10/19/2022]
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48
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Jonášová A, Vimmr J. Numerical simulation of non-Newtonian blood flow in bypass models. ACTA ACUST UNITED AC 2009. [DOI: 10.1002/pamm.200810179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
Advances in numerical methods and three-dimensional imaging techniques have enabled the quantification of cardiovascular mechanics in subject-specific anatomic and physiologic models. Patient-specific models are being used to guide cell culture and animal experiments and test hypotheses related to the role of biomechanical factors in vascular diseases. Furthermore, biomechanical models based on noninvasive medical imaging could provide invaluable data on the in vivo service environment where cardiovascular devices are employed and on the effect of the devices on physiologic function. Finally, patient-specific modeling has enabled an entirely new application of cardiovascular mechanics, namely predicting outcomes of alternate therapeutic interventions for individual patients. We review methods to create anatomic and physiologic models, obtain properties, assign boundary conditions, and solve the equations governing blood flow and vessel wall dynamics. Applications of patient-specific models of cardiovascular mechanics are presented, followed by a discussion of the challenges and opportunities that lie ahead.
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Affiliation(s)
- C.A. Taylor
- Department of Bioengineering, Stanford University, Stanford, California;
| | - C.A. Figueroa
- Department of Bioengineering, Stanford University, Stanford, California;
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3D flow study in a mildly stenotic coronary artery phantom using a whole volume PIV method. Med Eng Phys 2008; 30:1193-200. [DOI: 10.1016/j.medengphy.2008.02.012] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 02/26/2008] [Accepted: 02/26/2008] [Indexed: 11/15/2022]
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