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Johnston L, Allen R, Mason A, Kazakidi A. Morphological characterisation of pediatric Turner syndrome aortae: Insights from a small cohort study. Med Eng Phys 2023; 120:104045. [PMID: 37838399 DOI: 10.1016/j.medengphy.2023.104045] [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: 01/19/2023] [Revised: 08/23/2023] [Accepted: 08/28/2023] [Indexed: 10/16/2023]
Abstract
Cardiovascular disease is widespread in girls and women living with Turner syndrome (TS). Despite this prevalence, cardiovascular risk evaluation using the current guidelines has seen life-threatening aortic events occurring at dimensions classified within the normal threshold. In this study, we characterized the three-dimensional aortic geometries of Turner syndrome children and their age-matched healthy counterparts to evaluate various morphological parameters. Turner syndrome girls had overall greater values in ten out of fifteen parameters examined (p > 0.05), when compared to healthy children: the aortic arch height and width; the ascending aorta, aortic arch (2 locations), and descending aorta diameters; the ratio of the ascending to descending aorta diameter; average curvature; average torsion; and average curvature-torsion score. Additionally, significant associations were found in the TS group: body surface area and both arch height (p = 0.03) and arch height to width ratio (p = 0.05), and aortic arch diameter and both body surface area (p = 0.04) and weight (p = 0.04). The new information resulting from this small cohort study contributes to an improved understanding of the morphological parameters affecting the hemodynamic environment in TS, and the clinical assessment of the increased cardiovascular risk in this population.
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Affiliation(s)
- Lauren Johnston
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK
| | - Ruth Allen
- Department of Radiology, Royal Hospital for Children, Glasgow, UK
| | - Avril Mason
- Department of Paediatric Endocrinology, Royal Hospital for Children, Queen Elizabeth University Hospital, Glasgow, UK
| | - Asimina Kazakidi
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK.
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Black SM, Maclean C, Barrientos PH, Ritos K, Kazakidi A. Reconstruction and Validation of Arterial Geometries for Computational Fluid Dynamics Using Multiple Temporal Frames of 4D Flow-MRI Magnitude Images. Cardiovasc Eng Technol 2023; 14:655-676. [PMID: 37653353 PMCID: PMC10602980 DOI: 10.1007/s13239-023-00679-x] [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: 05/16/2022] [Accepted: 08/08/2023] [Indexed: 09/02/2023]
Abstract
PURPOSE Segmentation and reconstruction of arterial blood vessels is a fundamental step in the translation of computational fluid dynamics (CFD) to the clinical practice. Four-dimensional flow magnetic resonance imaging (4D Flow-MRI) can provide detailed information of blood flow but processing this information to elucidate the underlying anatomical structures is challenging. In this study, we present a novel approach to create high-contrast anatomical images from retrospective 4D Flow-MRI data. METHODS For healthy and clinical cases, the 3D instantaneous velocities at multiple cardiac time steps were superimposed directly onto the 4D Flow-MRI magnitude images and combined into a single composite frame. This new Composite Phase-Contrast Magnetic Resonance Angiogram (CPC-MRA) resulted in enhanced and uniform contrast within the lumen. These images were subsequently segmented and reconstructed to generate 3D arterial models for CFD. Using the time-dependent, 3D incompressible Reynolds-averaged Navier-Stokes equations, the transient aortic haemodynamics was computed within a rigid wall model of patient geometries. RESULTS Validation of these models against the gold standard CT-based approach showed no statistically significant inter-modality difference regarding vessel radius or curvature (p > 0.05), and a similar Dice Similarity Coefficient and Hausdorff Distance. CFD-derived near-wall hemodynamics indicated a significant inter-modality difference (p > 0.05), though these absolute errors were small. When compared to the in vivo data, CFD-derived velocities were qualitatively similar. CONCLUSION This proof-of-concept study demonstrated that functional 4D Flow-MRI information can be utilized to retrospectively generate anatomical information for CFD models in the absence of standard imaging datasets and intravenous contrast.
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Affiliation(s)
| | - Craig Maclean
- Research and Development, Terumo Aortic, Glasgow, UK
| | - Pauline Hall Barrientos
- Clinical Physics, Queen Elizabeth University Hospital, NHS Greater Glasgow & Clyde, Glasgow, UK
| | - Konstantinos Ritos
- Department of Mechanical and Aerospace Engineering, Glasgow, UK
- Department of Mechanical Engineering, University of Thessaly, Volos, Greece
| | - Asimina Kazakidi
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK.
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Black SM, Maclean C, Hall Barrientos P, Ritos K, McQueen A, Kazakidi A. Calibration of patient-specific boundary conditions for coupled CFD models of the aorta derived from 4D Flow-MRI. Front Bioeng Biotechnol 2023; 11:1178483. [PMID: 37251565 PMCID: PMC10210162 DOI: 10.3389/fbioe.2023.1178483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 04/21/2023] [Indexed: 05/31/2023] Open
Abstract
Introduction: Patient-specific computational fluid dynamics (CFD) models permit analysis of complex intra-aortic hemodynamics in patients with aortic dissection (AD), where vessel morphology and disease severity are highly individualized. The simulated blood flow regime within these models is sensitive to the prescribed boundary conditions (BCs), so accurate BC selection is fundamental to achieve clinically relevant results. Methods: This study presents a novel reduced-order computational framework for the iterative flow-based calibration of 3-Element Windkessel Model (3EWM) parameters to generate patient-specific BCs. These parameters were calibrated using time-resolved flow information derived from retrospective four-dimensional flow magnetic resonance imaging (4D Flow-MRI). For a healthy and dissected case, blood flow was then investigated numerically in a fully coupled zero dimensional-three dimensional (0D-3D) numerical framework, where the vessel geometries were reconstructed from medical images. Calibration of the 3EWM parameters was automated and required ~3.5 min per branch. Results: With prescription of the calibrated BCs, the computed near-wall hemodynamics (time-averaged wall shear stress, oscillatory shear index) and perfusion distribution were consistent with clinical measurements and previous literature, yielding physiologically relevant results. BC calibration was particularly important in the AD case, where the complex flow regime was captured only after BC calibration. Discussion: This calibration methodology can therefore be applied in clinical cases where branch flow rates are known, for example, via 4D Flow-MRI or ultrasound, to generate patient-specific BCs for CFD models. It is then possible to elucidate, on a case-by-case basis, the highly individualized hemodynamics which occur due to geometric variations in aortic pathology high spatiotemporal resolution through CFD.
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Affiliation(s)
- Scott MacDonald Black
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, United Kingdom
| | - Craig Maclean
- Research and Development, Terumo Aortic, Glasgow, United Kingdom
| | - Pauline Hall Barrientos
- Clinical Physics, Queen Elizabeth University Hospital, NHS Greater Glasgow and Clyde, Glasgow, United Kingdom
| | - Konstantinos Ritos
- Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow, United Kingdom
- Department of Mechanical Engineering, University of Thessaly, Volos, Greece
| | - Alistair McQueen
- Department of Biomedical Engineering, University of Glasgow, Glasgow, United Kingdom
| | - Asimina Kazakidi
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, United Kingdom
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Anbazhakan S, Rios Coronado PE, Sy-Quia ANL, Seow LW, Hands AM, Zhao M, Dong ML, Pfaller MR, Amir ZA, Raftrey BC, Cook CK, D’Amato G, Fan X, Williams IM, Jha SK, Bernstein D, Nieman K, Pașca AM, Marsden AL, Horse KR. Blood flow modeling reveals improved collateral artery performance during the regenerative period in mammalian hearts. NATURE CARDIOVASCULAR RESEARCH 2022; 1:775-790. [PMID: 37305211 PMCID: PMC10256232 DOI: 10.1038/s44161-022-00114-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 07/07/2022] [Indexed: 06/13/2023]
Abstract
Collateral arteries bridge opposing artery branches, forming a natural bypass that can deliver blood flow downstream of an occlusion. Inducing coronary collateral arteries could treat cardiac ischemia, but more knowledge on their developmental mechanisms and functional capabilities is required. Here we used whole-organ imaging and three-dimensional computational fluid dynamics modeling to define spatial architecture and predict blood flow through collaterals in neonate and adult mouse hearts. Neonate collaterals were more numerous, larger in diameter and more effective at restoring blood flow. Decreased blood flow restoration in adults arose because during postnatal growth coronary arteries expanded by adding branches rather than increasing diameters, altering pressure distributions. In humans, adult hearts with total coronary occlusions averaged 2 large collaterals, with predicted moderate function, while normal fetal hearts showed over 40 collaterals, likely too small to be functionally relevant. Thus, we quantify the functional impact of collateral arteries during heart regeneration and repair-a critical step toward realizing their therapeutic potential.
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Affiliation(s)
- Suhaas Anbazhakan
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- These authors contributed equally
| | - Pamela E. Rios Coronado
- Department of Biology, Stanford University, Stanford, CA 94305, USA
- These authors contributed equally
| | | | - Lek Wei Seow
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Aubrey M. Hands
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Mingming Zhao
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, 94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Melody L. Dong
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Martin R. Pfaller
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, 94305
| | - Zhainib A. Amir
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Brian C. Raftrey
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | | | - Gaetano D’Amato
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Xiaochen Fan
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Ian M. Williams
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Sawan K. Jha
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Daniel Bernstein
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, 94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Koen Nieman
- Departments of Cardiovascular Medicine and Radiology, School of Medicine, Stanford University, Stanford, CA, 94305, USA
| | - Anca M. Pașca
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, 94305
| | - Alison L. Marsden
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, 94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Kristy Red Horse
- Department of Biology, Stanford University, Stanford, CA 94305, USA
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
- Howard Hughes Medical Institute, Stanford, CA, 94305, USA
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Bazzi MS, Balouchzadeh R, Pavey SN, Quirk JD, Yanagisawa H, Vedula V, Wagenseil JE, Barocas VH. Experimental and Mouse-Specific Computational Models of the Fbln4 SMKO Mouse to Identify Potential Biomarkers for Ascending Thoracic Aortic Aneurysm. Cardiovasc Eng Technol 2022; 13:558-572. [PMID: 35064559 PMCID: PMC9304450 DOI: 10.1007/s13239-021-00600-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 11/28/2021] [Indexed: 11/02/2022]
Abstract
PURPOSE To use computational methods to explore geometric, mechanical, and fluidic biomarkers that could correlate with mouse lifespan in the Fbln4SMKO mouse. Mouse lifespan was used as a surrogate for risk of a severe cardiovascular event in cases of ascending thoracic aortic aneurysm. METHODS Image-based, mouse-specific fluid-structure-interaction models were developed for Fbln4SMKO mice (n = 10) at ages two and six months. The results of the simulations were used to quantify potential biofluidic biomarkers, complementing the geometrical biomarkers obtained directly from the images. RESULTS Comparing the different geometrical and biofluidic biomarkers to the mouse lifespan, it was found that mean oscillatory shear index (OSImin) and minimum time-averaged wall shear stress (TAWSSmin) at six months showed the largest correlation with lifespan (r2 = 0.70, 0.56), with both correlations being positive (i.e., mice with high OSImean and high TAWSSmin tended to live longer). When change between two and six months was considered, the change in TAWSSmin showed a much stronger correlation than OSImean (r2 = 0.75 vs. 0.24), and the correlation was negative (i.e., mice with increasing TAWSSmin over this period tended to live less long). CONCLUSION The results highlight potential biomarkers of ATAA outcomes that can be obtained through noninvasive imaging and computational simulations, and they illustrate the potential synergy between small-animal and computational models.
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Affiliation(s)
- Marisa S Bazzi
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Ramin Balouchzadeh
- Department of Mechanical Engineering & Materials Science, Washington University, St. Louis, MO, 63110, USA
| | - Shawn N Pavey
- Department of Mechanical Engineering & Materials Science, Washington University, St. Louis, MO, 63110, USA
| | - James D Quirk
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Hiromi Yanagisawa
- Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Japan
| | - Vijay Vedula
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Jessica E Wagenseil
- Department of Mechanical Engineering & Materials Science, Washington University, St. Louis, MO, 63110, USA
| | - Victor H Barocas
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, 55455, USA.
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Patient-specific computational haemodynamics associated with the surgical creation of an arteriovenous fistula. Med Eng Phys 2022; 105:103814. [DOI: 10.1016/j.medengphy.2022.103814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 05/03/2022] [Accepted: 05/04/2022] [Indexed: 11/22/2022]
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Boumpouli M, Sauvage EL, Capelli C, Schievano S, Kazakidi A. Characterization of Flow Dynamics in the Pulmonary Bifurcation of Patients With Repaired Tetralogy of Fallot: A Computational Approach. Front Cardiovasc Med 2021; 8:703717. [PMID: 34660711 PMCID: PMC8514754 DOI: 10.3389/fcvm.2021.703717] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 09/07/2021] [Indexed: 11/18/2022] Open
Abstract
The hemodynamic environment of the pulmonary bifurcation is of great importance for adult patients with repaired tetralogy of Fallot (rTOF) due to possible complications in the pulmonary valve and narrowing of the left pulmonary artery (LPA). The aim of this study was to computationally investigate the effect of geometrical variability and flow split on blood flow characteristics in the pulmonary trunk of patient-specific models. Data from a cohort of seven patients was used retrospectively and the pulmonary hemodynamics was investigated using averaged and MRI-derived patient-specific boundary conditions on the individualized models, as well as a statistical mean geometry. Geometrical analysis showed that curvature and tortuosity are higher in the LPA branch, compared to the right pulmonary artery (RPA), resulting in complex flow patterns in the LPA. The computational analysis also demonstrated high time-averaged wall shear stress (TAWSS) at the outer wall of the LPA and the wall of the RPA proximal to the junction. Similar TAWSS patterns were observed for averaged boundary conditions, except for a significantly modified flow split assigned at the outlets. Overall, this study enhances our understanding about the flow development in the pulmonary bifurcation of rTOF patients and associates some morphological characteristics with hemodynamic parameters, highlighting the importance of patient-specificity in the models. To confirm these findings, further studies are required with a bigger cohort of patients.
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Affiliation(s)
- Maria Boumpouli
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, United Kingdom
| | - Emilie L. Sauvage
- Institute of Cardiovascular Science and Great Ormond Street Hospital for Children, NHS Foundation Trust, University College London, London, United Kingdom
| | - Claudio Capelli
- Institute of Cardiovascular Science and Great Ormond Street Hospital for Children, NHS Foundation Trust, University College London, London, United Kingdom
| | - Silvia Schievano
- Institute of Cardiovascular Science and Great Ormond Street Hospital for Children, NHS Foundation Trust, University College London, London, United Kingdom
| | - Asimina Kazakidi
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, United Kingdom
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Effect of Subject-Specific, Spatially Reduced, and Idealized Boundary Conditions on the Predicted Hemodynamic Environment in the Murine Aorta. Ann Biomed Eng 2021; 49:3255-3266. [PMID: 34528150 DOI: 10.1007/s10439-021-02851-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 08/06/2021] [Indexed: 10/20/2022]
Abstract
Mouse models of atherosclerosis have become effective resources to study atherogenesis, including the relationship between hemodynamics and lesion development. Computational methods aid the prediction of the in vivo hemodynamic environment in the mouse vasculature, but careful selection of inflow and outflow boundary conditions (BCs) is warranted to promote model accuracy. Herein, we investigated the impact of animal-specific versus reduced/idealized flow boundary conditions on predicted blood flow patterns in the mouse thoracic aorta. Blood velocities were measured in the aortic root, arch branch vessel, and descending aorta in ApoE-/- mice using phase-contrast MRI. Computational geometries were derived from micro-CT imaging and combinations of high-fidelity or reduced/idealized MR-derived BCs were applied to predict the bulk flow field and hemodynamic metrics (e.g., wall shear stress, WSS; cross-flow index, CFI). Results demonstrate that pressure-free outlet BCs significantly overestimate outlet flow rates as compared to measured values. When compared to models that incorporate 3-component inlet velocity data [[Formula: see text]] and time-varying outlet mass flow splits [[Formula: see text]] (i.e., high-fidelity model), neglecting in-plane inlet velocity components (i.e., [Formula: see text])) leads to errors in WSS and CFI values ranging from 10 to 30% across the model domain whereas the application of a steady outlet mass flow splits results in negligible differences in these hemodynamics metrics. This investigation highlights that 3-component inlet velocity data and at least steady mass flow splits are required for accurate predictions of flow patterns in the mouse thoracic aorta.
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Rafiei D, Abazari MA, Soltani M, Alimohammadi M. The effect of coarctation degrees on wall shear stress indices. Sci Rep 2021; 11:12757. [PMID: 34140562 PMCID: PMC8211800 DOI: 10.1038/s41598-021-92104-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 06/03/2021] [Indexed: 02/05/2023] Open
Abstract
Coarctation of the aorta (CoA) is a congenital tightening of the proximal descending aorta. Flow quantification can be immensely valuable for an early and accurate diagnosis. However, there is a lack of appropriate diagnostic approaches for a variety of cardiovascular diseases, such as CoA. An accurate understanding of the disease depends on measurements of the global haemodynamics (criteria for heart function) and also the local haemodynamics (detailed data on the dynamics of blood flow). Playing a significant role in clinical processes, wall shear stress (WSS) cannot be measured clinically; thus, computation tools are needed to give an insight into this crucial haemodynamic parameter. In the present study, in order to enable the progress of non-invasive approaches that quantify global and local haemodynamics for different CoA severities, innovative computational blueprint simulations that include fluid-solid interaction models are developed. Since there is no clear approach for managing the CoA regarding its severity, this study proposes the use of WSS indices and pressure gradient to better establish a framework for treatment procedures in CoA patients with different severities. This provides a platform for improving CoA therapy on a patient-specific level, in which physicians can perform treatment methods based on WSS indices on top of using a mere experience. Results show how severe CoA affects the aorta in comparison to the milder cases, which can give the medical community valuable information before and after any intervention.
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Affiliation(s)
- Deniz Rafiei
- Department of Mechanical Engineering, K. N. Toosi Univeristy of Technology, Tehran, Iran
| | - Mohammad Amin Abazari
- Department of Mechanical Engineering, K. N. Toosi Univeristy of Technology, Tehran, Iran
| | - M Soltani
- Department of Mechanical Engineering, K. N. Toosi Univeristy of Technology, Tehran, Iran
- Department of Electrical and Computer Engineering, Faculty of Engineering, School of Optometry and Vision Science, Faculty of Science, University of Waterloo, Waterloo, Canada
- Advanced Bioengineering Initiative Center, Multidisciplinary International Complex, K. N. Toosi University of Technology, Tehran, Iran
- Centre for Biotechnology and Bioengineering (CBB), University of Waterloo, Waterloo, ON, Canada
- Cancer Biology Research Center, Cancer Institute of Iran, Tehran University of Medical Sciences, Tehran, Iran
| | - Mona Alimohammadi
- Department of Mechanical Engineering, K. N. Toosi Univeristy of Technology, Tehran, Iran.
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Han L, Ren Q, Lian J, Luo L, Liu H, Ma T, Li X, Deng X, Liu X. Numerical analysis of the hemodynamics of rat aorta based on magnetic resonance imaging and fluid-structure interaction. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3457. [PMID: 33750033 DOI: 10.1002/cnm.3457] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 03/14/2021] [Indexed: 06/12/2023]
Abstract
Murine models have been widely used to investigate the mechanobiology of aortic atherosclerosis and dissections, which develop preferably at different anatomic locations of aorta. Based MRI and finite element analysis with fluid-structure interaction, we numerically investigated factors that may affect the blood flow and structural mechanics of rat aorta. The results indicated that aortic root motion greatly increases time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), displacement of the aorta, and enhances helical flow pattern but has limited influence on effective stress, which is highly modulated by blood pressure. Moreover, the influence of the motion component on these indicators is different with axial motion more obvious than planar motion. Surrounding fixation of the intercostal arteries and the branch vessels on aortic arch would reduce the influence of aortic root motion. The compliance of the aorta has different influences at different regions, leading to decrease in TAWSS and helical flow, increase in OSI, RRT at the aortic arch, but has reversed effects on the branch vessels. When compared with the steady flow, the pulsatile blood flow would obviously increase the WSS, the displacement, and the effective stress in most regions. In conclusion, to accurately quantify the blood flow and structural mechanics of rat aorta, the motion of the aortic root, the compliance of aortic wall, and the pulsation of blood flow should be considered. However, when only focusing on the effective stress in rat aorta, the motion of the aortic root may be neglected.
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Affiliation(s)
- Longzhu Han
- Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Quan Ren
- Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Jianxiu Lian
- Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Liyi Luo
- School of Instrumentation Science & Opto-electronics Engineering, Beihang University, Beijing, China
| | - Huawei Liu
- Department of Stomatology, Chinese PLA General Hospital, Beijing, China
| | - Tianxiang Ma
- Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Xin Li
- Miyun Hospital, Peking University First Hospital, Beijing, China
| | - Xiaoyan Deng
- Artificial Intelligence Key Laboratory of Sichuan Province, School of Automation and Information Engineering, Sichuan University of Science and Engineering, Zigong, China
| | - Xiao Liu
- Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China
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11
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Johnston L, Allen R, Hall Barrientos P, Mason A, Kazakidi A. Hemodynamic Abnormalities in the Aorta of Turner Syndrome Girls. Front Cardiovasc Med 2021; 8:670841. [PMID: 34141729 PMCID: PMC8203817 DOI: 10.3389/fcvm.2021.670841] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 05/06/2021] [Indexed: 01/15/2023] Open
Abstract
Congenital abnormalities in girls and women with Turner syndrome (TS), alongside an underlying predisposition to obesity and hypertension, contribute to an increased risk of cardiovascular disease and ultimately reduced life expectancy. We observe that children with TS present a greater variance in aortic arch morphology than their healthy counterparts, and hypothesize that their hemodynamics is also different. In this study, computational fluid dynamic (CFD) simulations were performed for four TS girls, and three age-matched healthy girls, using patient-specific inlet boundary conditions, obtained from phase-contrast MRI data. The visualization of multidirectional blood flow revealed an increase in vortical flow in the arch, supra-aortic vessels, and descending aorta, and a correlation between the presence of aortic abnormalities and disturbed flow. Compared to the relatively homogeneous pattern of time-averaged wall shear stress (TAWSS) on the healthy aortae, a highly heterogeneous distribution with elevated TAWSS values was observed in the TS geometries. Visualization of further shear stress parameters, such as oscillatory shear index (OSI), normalized relative residence time (RRTn), and transverse WSS (transWSS), revealed dissimilar heterogeneity in the oscillatory and multidirectional nature of the aortic flow. Taking into account the young age of our TS cohort (average age 13 ± 2 years) and their obesity level (75% were obese or overweight), which is believed to accelerate the initiation and progression of endothelial dysfunction, these findings may be an indication of atherosclerotic disease manifesting earlier in life in TS patients. Age, obesity and aortic morphology may, therefore, play a key role in assessing cardiovascular risk in TS children.
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Affiliation(s)
- Lauren Johnston
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, United Kingdom
| | - Ruth Allen
- Department of Radiology, Royal Hospital for Children, Glasgow, United Kingdom
| | | | - Avril Mason
- Department of Paediatric Endocrinology, Royal Hospital for Children, Queen Elizabeth University Hospital, Glasgow, United Kingdom
| | - Asimina Kazakidi
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, United Kingdom
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Andelovic K, Winter P, Jakob PM, Bauer WR, Herold V, Zernecke A. Evaluation of Plaque Characteristics and Inflammation Using Magnetic Resonance Imaging. Biomedicines 2021; 9:185. [PMID: 33673124 PMCID: PMC7917750 DOI: 10.3390/biomedicines9020185] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 12/19/2022] Open
Abstract
Atherosclerosis is an inflammatory disease of large and medium-sized arteries, characterized by the growth of atherosclerotic lesions (plaques). These plaques often develop at inner curvatures of arteries, branchpoints, and bifurcations, where the endothelial wall shear stress is low and oscillatory. In conjunction with other processes such as lipid deposition, biomechanical factors lead to local vascular inflammation and plaque growth. There is also evidence that low and oscillatory shear stress contribute to arterial remodeling, entailing a loss in arterial elasticity and, therefore, an increased pulse-wave velocity. Although altered shear stress profiles, elasticity and inflammation are closely intertwined and critical for plaque growth, preclinical and clinical investigations for atherosclerosis mostly focus on the investigation of one of these parameters only due to the experimental limitations. However, cardiovascular magnetic resonance imaging (MRI) has been demonstrated to be a potent tool which can be used to provide insights into a large range of biological parameters in one experimental session. It enables the evaluation of the dynamic process of atherosclerotic lesion formation without the need for harmful radiation. Flow-sensitive MRI provides the assessment of hemodynamic parameters such as wall shear stress and pulse wave velocity which may replace invasive and radiation-based techniques for imaging of the vascular function and the characterization of early plaque development. In combination with inflammation imaging, the analyses and correlations of these parameters could not only significantly advance basic preclinical investigations of atherosclerotic lesion formation and progression, but also the diagnostic clinical evaluation for early identification of high-risk plaques, which are prone to rupture. In this review, we summarize the key applications of magnetic resonance imaging for the evaluation of plaque characteristics through flow sensitive and morphological measurements. The simultaneous measurements of functional and structural parameters will further preclinical research on atherosclerosis and has the potential to fundamentally improve the detection of inflammation and vulnerable plaques in patients.
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Affiliation(s)
- Kristina Andelovic
- Institute of Experimental Biomedicine, University Hospital Würzburg, 97080 Würzburg, Germany
- Experimental Physics V, University of Würzburg, 97074 Würzburg, Germany; (P.W.); (P.M.J.); (V.H.)
| | - Patrick Winter
- Experimental Physics V, University of Würzburg, 97074 Würzburg, Germany; (P.W.); (P.M.J.); (V.H.)
- Internal Medicine I, Cardiology, University Hospital Würzburg, 97080 Würzburg, Germany;
| | - Peter Michael Jakob
- Experimental Physics V, University of Würzburg, 97074 Würzburg, Germany; (P.W.); (P.M.J.); (V.H.)
| | - Wolfgang Rudolf Bauer
- Internal Medicine I, Cardiology, University Hospital Würzburg, 97080 Würzburg, Germany;
| | - Volker Herold
- Experimental Physics V, University of Würzburg, 97074 Würzburg, Germany; (P.W.); (P.M.J.); (V.H.)
| | - Alma Zernecke
- Institute of Experimental Biomedicine, University Hospital Würzburg, 97080 Würzburg, Germany
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13
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Qiu P, Liu J, Chen Y, Zha B, Ye K, Qin J, Hao P, Kang J, Zhang C, Zhu H, Lu X. Changes in aortic arch geometry and the risk for Stanford B dissection. J Thorac Dis 2020; 12:7193-7201. [PMID: 33447408 PMCID: PMC7797824 DOI: 10.21037/jtd-20-1643] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background The increase in aortic diameter is not closely associated with type B aortic dissection (TBAD); morphological risk factors other than aortic diameter may help to better identify patients at risk for TBAD. The purpose of this study was to investigate possible morphological factors associated with the occurrence of TBAD. Methods This study was a retrospective, multicenter, cross-sectional study. We collected 94 patients with TBAD as the TBAD group and 534 patients with healthy aortas as the healthy control group. Morphometric data were collected on three-dimensional models of the thoracic aorta. A propensity score matching (PSM) analysis was conducted to reduce the potential for confounding by baseline factors. Results The number of patients in the TBAD group was 75 after PSM. Longer lengths of the aortic arch (28.00±7.42 vs. 25.14±7.11 cm) were observed in patients with TBAD. The width (80.04±17.27 vs. 71.73±15.55 mm) and height (24.92±11.39 vs. 19.37±10.10 mm) of the aortic arch in patients with TBAD were both larger than those of healthy controls. The morphological changes associated with the occurrence of type B acute dissection were most pronounced in the geometry of the aortic arch. Conclusions This study demonstrates that TBAD was associated with longer lengths of aortic arch and with larger arch height and width.
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Affiliation(s)
- Peng Qiu
- Department of Vascular Surgery, Shanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Junchao Liu
- Department of Vascular Surgery, Shanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yuqian Chen
- School of Public Economics and Administration, Shanghai University of Finance and Economics, Shanghai, China
| | - Binshan Zha
- Department of Vascular and Thyroid Surgery, Department of General Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Kaichuang Ye
- Department of Vascular Surgery, Shanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jinbao Qin
- Department of Vascular Surgery, Shanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Peipei Hao
- Department of Radiology, the Affiliated Tongji Hospital of Tongji University, Shanghai, China
| | - Jiwen Kang
- Department of Radiology, Shanghai Jiading Kangqiao Hospital, Shanghai, China
| | - Chao Zhang
- Department of Radiology, Yijishan Hospital Affiliated to Wannan Medical College, Wuhu, China
| | - Huagang Zhu
- Department of Vascular and Thyroid Surgery, Department of General Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Xinwu Lu
- Department of Vascular Surgery, Shanghai Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
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14
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Dazzi M, Rowland EM, Mohri Z, Weinberg PD. 3D confocal microscope imaging of macromolecule uptake in the intact brachiocephalic artery. Atherosclerosis 2020; 310:93-101. [PMID: 32861514 PMCID: PMC7534415 DOI: 10.1016/j.atherosclerosis.2020.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 06/20/2020] [Accepted: 07/02/2020] [Indexed: 10/25/2022]
Abstract
BACKGROUND AND AIMS Elevated uptake of plasma macromolecules by the arterial wall is an early event in atherogenesis. Existing optical techniques for detecting macromolecular tracers in the wall have poor depth penetration and hence require en face imaging of flattened arterial segments. Imaging uptake in undistorted curved and branched vessels would be useful in understanding disease development. METHODS Depth penetration was increased by applying optical clearing techniques. The rat aorto-brachiocephalic junction was imaged intact by confocal microscopy after it had been exposed to circulating rhodamine-labelled albumin in vivo, fixed in situ, excised and then cleared with benzyl alcohol/benzyl benzoate. Tracer uptake was mapped onto a 3D surface mesh of the arterial geometry. RESULTS Tracer fluorescence was detectable throughout the wall closest to the objective lens and, despite a vessel diameter of c. 1 mm, in the wall on the other side of the artery, across the lumen. By tile scanning, tracer concentrations were mapped in the aorta, the brachiocephalic artery and their junction without opening or flattening either vessel. Optical clearing was also shown to be compatible with immunofluorescent staining and imaging of experimental atherosclerosis. CONCLUSIONS The technique obviates the need for labour-intensive sample preparation associated with standard en face imaging. More importantly, it preserves arterial geometry, facilitating co-localisation of uptake maps with maps of biomechanical factors, which typically exist on 3D surface meshes. It will permit the correlation of haemodynamic wall shear stress with macromolecule permeability more accurately in regions of high curvature or branching, such as in the coronary arteries.
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Affiliation(s)
- Marta Dazzi
- Department of Bioengineering, Imperial College London, London, SW7 2AZ, UK
| | - Ethan M Rowland
- Department of Bioengineering, Imperial College London, London, SW7 2AZ, UK
| | - Zahra Mohri
- Department of Bioengineering, Imperial College London, London, SW7 2AZ, UK
| | - Peter D Weinberg
- Department of Bioengineering, Imperial College London, London, SW7 2AZ, UK.
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15
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Boumpouli M, Danton MHD, Gourlay T, Kazakidi A. Blood flow simulations in the pulmonary bifurcation in relation to adult patients with repaired tetralogy of Fallot. Med Eng Phys 2020; 85:123-138. [PMID: 33081959 DOI: 10.1016/j.medengphy.2020.09.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 07/01/2020] [Accepted: 09/25/2020] [Indexed: 10/23/2022]
Abstract
Understanding the haemodynamic environment of the pulmonary bifurcation is important in adults with repaired conotruncal congenital heart disease. In these patients, dysfunction of the pulmonary valve and narrowing of the branch pulmonary arteries are common and can have serious clinical consequences. The aim of this study was to numerically investigate the underlying blood flow characteristics in the pulmonary trunk under a range of simplified conditions. For that, an in-depth analysis was conducted in idealised two-dimensional geometries that facilitate parametric investigation of healthy and abnormal conditions. Subtle variations in morphology influenced the haemodynamic environment and wall shear stress distribution. The pressure in the left pulmonary artery was generally higher than that in the right and main arteries, but was markedly reduced in the presence of a local stenosis. Different downstream pressure conditions altered the branch flow ratio, from 50:50% to more realistic 60:40% ratios in the right and left pulmonary artery, respectively. Despite some simplifications, this study highlights some previously undocumented aspects of the flow in bifurcating geometries, by clarifying the role of the stagnation point location on wall shear stress and differential branch pressures. In addition, measurements of the mean pressure ratios in the pulmonary bifurcation are discussed in the context of a new haemodynamic index which could potentially contribute to the assessment of left pulmonary artery stenosis in tetralogy of Fallot patients. Further studies are required to confirm the results in patient-specific models with personalised physiological flow conditions.
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Affiliation(s)
- Maria Boumpouli
- Department of Biomedical Engineering, University of Strathclyde, 106 Rottenrow East, Glasgow G4 0NW, United Kingdom
| | - Mark H D Danton
- Department of Biomedical Engineering, University of Strathclyde, 106 Rottenrow East, Glasgow G4 0NW, United Kingdom; Scottish Adult Congenital Cardiac Service, Golden Jubilee National Hospital, Clydebank G81 4DY, United Kingdom
| | - Terence Gourlay
- Department of Biomedical Engineering, University of Strathclyde, 106 Rottenrow East, Glasgow G4 0NW, United Kingdom
| | - Asimina Kazakidi
- Department of Biomedical Engineering, University of Strathclyde, 106 Rottenrow East, Glasgow G4 0NW, United Kingdom.
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16
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Douglas G, Mehta V, Al Haj Zen A, Akoumianakis I, Goel A, Rashbrook VS, Trelfa L, Donovan L, Drydale E, Chuaiphichai S, Antoniades C, Watkins H, Kyriakou T, Tzima E, Channon KM. A key role for the novel coronary artery disease gene JCAD in atherosclerosis via shear stress mechanotransduction. Cardiovasc Res 2020; 116:1863-1874. [PMID: 31584065 PMCID: PMC7449560 DOI: 10.1093/cvr/cvz263] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 09/13/2019] [Accepted: 10/02/2019] [Indexed: 12/11/2022] Open
Abstract
AIMS Genome-wide association studies (GWAS) have consistently identified an association between coronary artery disease (CAD) and a locus on chromosome 10 containing a single gene, JCAD (formerly KIAA1462). However, little is known about the mechanism by which JCAD could influence the development of atherosclerosis. METHODS AND RESULTS Vascular function was quantified in subjects with CAD by flow-mediated dilatation (FMD) and vasorelaxation responses in isolated blood vessel segments. The JCAD risk allele identified by GWAS was associated with reduced FMD and reduced endothelial-dependent relaxations. To study the impact of loss of Jcad on atherosclerosis, Jcad-/- mice were crossed to an ApoE-/- background and fed a high-fat diet from 6 to16 weeks of age. Loss of Jcad did not affect blood pressure or heart rate. However, Jcad-/-ApoE-/- mice developed significantly less atherosclerosis in the aortic root and the inner curvature of the aortic arch. En face analysis revealed a striking reduction in pro-inflammatory adhesion molecules at sites of disturbed flow on the endothelial cell layer of Jcad-/- mice. Loss of Jcad lead to a reduced recovery perfusion in response to hind limb ischaemia, a model of altered in vivo flow. Knock down of JCAD using siRNA in primary human aortic endothelial cells significantly reduced the response to acute onset of flow, as evidenced by reduced phosphorylation of NF-КB, eNOS, and Akt. CONCLUSION The novel CAD gene JCAD promotes atherosclerotic plaque formation via a role in the endothelial cell shear stress mechanotransduction pathway.
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MESH Headings
- Animals
- Aorta/metabolism
- Aorta/physiopathology
- Aortic Diseases/genetics
- Aortic Diseases/metabolism
- Aortic Diseases/physiopathology
- Aortic Diseases/prevention & control
- Atherosclerosis/genetics
- Atherosclerosis/metabolism
- Atherosclerosis/physiopathology
- Atherosclerosis/prevention & control
- Cell Adhesion Molecules/genetics
- Cell Adhesion Molecules/metabolism
- Cells, Cultured
- Coronary Artery Disease/genetics
- Coronary Artery Disease/metabolism
- Coronary Artery Disease/physiopathology
- Coronary Circulation
- Coronary Vessels/metabolism
- Coronary Vessels/physiopathology
- Disease Models, Animal
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/physiopathology
- Genome-Wide Association Study
- Hindlimb/blood supply
- Humans
- Ischemia/genetics
- Ischemia/metabolism
- Ischemia/physiopathology
- Male
- Mechanotransduction, Cellular
- Mice, Inbred C57BL
- Mice, Knockout, ApoE
- NF-kappa B/metabolism
- Nitric Oxide Synthase Type III/metabolism
- Phosphorylation
- Plaque, Atherosclerotic
- Proto-Oncogene Proteins c-akt
- Stress, Mechanical
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Affiliation(s)
- Gillian Douglas
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Vedanta Mehta
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Ayman Al Haj Zen
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
- College of Health and Life Sciences, Hamad Bin Khalifa University, Education City, Qatar Foundation, Doha, Qatar
| | - Ioannis Akoumianakis
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Anuj Goel
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Victoria S Rashbrook
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Lucy Trelfa
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Lucy Donovan
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Edward Drydale
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Surawee Chuaiphichai
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Charalambos Antoniades
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Theodosios Kyriakou
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Ellie Tzima
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Keith M Channon
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, BHF Centre of Research Excellence, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
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17
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Pirola S, Jarral OA, O'Regan DP, Asimakopoulos G, Anderson JR, Pepper JR, Athanasiou T, Xu XY. Computational study of aortic hemodynamics for patients with an abnormal aortic valve: The importance of secondary flow at the ascending aorta inlet. APL Bioeng 2018; 2:026101. [PMID: 31069298 PMCID: PMC6481743 DOI: 10.1063/1.5011960] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 02/06/2018] [Indexed: 12/05/2022] Open
Abstract
Blood flow in the aorta is helical, but most computational studies ignore the presence of secondary flow components at the ascending aorta (AAo) inlet. The aim of this study is to ascertain the importance of inlet boundary conditions (BCs) in computational analysis of flow patterns in the thoracic aorta based on patient-specific images, with a particular focus on patients with an abnormal aortic valve. Two cases were studied: one presenting a severe aortic valve stenosis and the other with a mechanical valve. For both aorta models, three inlet BCs were compared; these included the flat profile and 1D through-plane velocity and 3D phase-contrast magnetic resonance imaging derived velocity profiles, with the latter being used for benchmarking. Our results showed that peak and mean velocities at the proximal end of the ascending aorta were underestimated by up to 41% when the secondary flow components were neglected. The results for helical flow descriptors highlighted the strong influence of secondary velocities on the helical flow structure in the AAo. Differences in all wall shear stress (WSS)-derived indices were much more pronounced in the AAo and aortic arch (AA) than in the descending aorta (DAo). Overall, this study demonstrates that using 3D velocity profiles as inlet BC is essential for patient-specific analysis of hemodynamics and WSS in the AAo and AA in the presence of an abnormal aortic valve. However, predicted flow in the DAo is less sensitive to the secondary velocities imposed at the inlet; hence, the 1D through-plane profile could be a sufficient inlet BC for studies focusing on distal regions of the thoracic aorta.
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Affiliation(s)
- S Pirola
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
| | - O A Jarral
- Department of Surgery and Cancer, Imperial College London, St. Mary's Hospital, London W2 1NY, United Kingdom
| | - D P O'Regan
- Institute of Clinical Science, Imperial College London, Hammersmith Hospital, London W12 0HS, United Kingdom
| | - G Asimakopoulos
- Royal Brompton and Harefield NHS Foundation Trust, Sydney Street, London SW3 6NP, United Kingdom
| | - J R Anderson
- Hammersmith Hospital, Imperial College Healthcare NHS Trust, Du Cane Road, London W12 0HS, United Kingdom
| | - J R Pepper
- Royal Brompton and Harefield NHS Foundation Trust, Sydney Street, London SW3 6NP, United Kingdom
| | - T Athanasiou
- Department of Surgery and Cancer, Imperial College London, St. Mary's Hospital, London W2 1NY, United Kingdom
| | - X Y Xu
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
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18
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Chen Z, Yu H, Shi Y, Zhu M, Wang Y, Hu X, Zhang Y, Chang Y, Xu M, Gao W. Vascular Remodelling Relates to an Elevated Oscillatory Shear Index and Relative Residence Time in Spontaneously Hypertensive Rats. Sci Rep 2017; 7:2007. [PMID: 28515420 PMCID: PMC5435712 DOI: 10.1038/s41598-017-01906-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 04/03/2017] [Indexed: 01/25/2023] Open
Abstract
Haemodynamic disorders are common clinical findings in hypertension and lead to adverse cardiovascular events. However, the haemodynamic conditions in hypertension models are poorly understood. This study aimed to observe the characteristics of haemodynamics in spontaneously hypertensive rats (SHRs) and antihypertensive-treated SHRs. Twenty-four adult male SHRs and Wistar-Kyoto rats (WKYs) were randomly divided into four groups and treated for 7 days as follows: WKY-CON (WKYs + saline), WKY-NIF (WKYs + nifedipine, 50 mg/kg/day), SHR-CON (SHRs + saline), and SHR-NIF (SHRs + nifedipine). Aortic computational fluid dynamics (CFD) models were simulated to obtain the haemodynamic parameters. We found that in the hypertensive (SHR-CON) and blood pressure-controlled (SHR-NIF) groups, the oscillatory shear index (OSI) and relative residence time (RRT), which are key haemodynamics indices, were markedly elevated. Furthermore, there was a correlation between both the elevated OSI and RRT with the vascular wall thickening in regions near the inner wall of the aortic arch. Our research demonstrates that haemodynamics remains disturbed even if the blood pressure is normalized. In addition, vascular remodelling may play an important role in maintaining elevated OSI and RRT values.
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Affiliation(s)
- Zhiyan Chen
- Department of Cardiology, Peking University Third Hospital and Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, 100191, China
| | - Haiyi Yu
- Department of Cardiology, Peking University Third Hospital and Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, 100191, China
| | - Yue Shi
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China
| | - Minjia Zhu
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China
| | - Yueshen Wang
- Department of Cardiology, Peking University Third Hospital and Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, 100191, China
| | - Xi Hu
- Department of Cardiology, Peking University Third Hospital and Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, 100191, China
| | - Youyi Zhang
- Department of Cardiology, Peking University Third Hospital and Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, 100191, China
| | - Yu Chang
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China.
| | - Ming Xu
- Department of Cardiology, Peking University Third Hospital and Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, 100191, China.
| | - Wei Gao
- Department of Cardiology, Peking University Third Hospital and Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, 100191, China.
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19
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Miyazaki S, Itatani K, Furusawa T, Nishino T, Sugiyama M, Takehara Y, Yasukochi S. Validation of numerical simulation methods in aortic arch using 4D Flow MRI. Heart Vessels 2017; 32:1032-1044. [PMID: 28444501 PMCID: PMC5519664 DOI: 10.1007/s00380-017-0979-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 04/14/2017] [Indexed: 11/20/2022]
Abstract
Computational fluid dynamics (CFD) are the gold standard in studying blood flow dynamics. However, CFD results are dependent on the boundary conditions and the computation model. The purpose of this study was to validate CFD methods using comparison with actual measurements of the blood flow vector obtained with four-dimensional (4D) flow magnetic resonance imaging (MRI). 4D Flow MRI was performed on a healthy adult and a child with double-aortic arch. The aortic lumen was segmented to visualize the blood flow. The CFD analyses were performed for the same geometries based on three turbulent models: laminar, large eddy simulation (LES), and the renormalization group k–ε model (RNG k–ε). The flow-velocity vector components, namely the wall shear stress (WSS) and flow energy loss (EL), of the MRI and CFD results were compared. The flow rate of the MRI results was underestimated in small vessels, including the neck vessels. Spiral flow in the ascending aorta caused by the left ventricular twist was observed by MRI. Secondary flow distal to the aortic arch was well realized in both CFD and MRI. The average correlation coefficients of the velocity vector components of MRI and CFD for the child were the highest for the RNG k–ε model (0.530 in ascending aorta, 0.768 in the aortic arch, 0.584 in the descending aorta). The WSS and EL values of MRI were less than half of those of CFD, but the WSS distribution patterns were quite similar. The WSS and EL estimates were higher in RNG k–ε and LES than in the laminar model because of eddy viscosity. The CFD computation realized accurate flow distal to the aortic arch, and the WSS distribution was well simulated compared to actual measurement using 4D Flow MRI. However, the helical flow was not simulated in the ascending aorta. The accuracy was enhanced by using the turbulence model, and the RNG k–ε model showed the highest correlation with 4D Flow MRI.
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Affiliation(s)
- Shohei Miyazaki
- Cardio Flow Design, Inc., Chiyoda, Tokyo, Japan.,Department of Cardiovascular Surgery, Kyoto Prefectural University of Medicine, 1-5 Hangi-cho, Shimogamo, Sakyo-ku, Kyoto, 606-8522, Japan
| | - Keiichi Itatani
- Cardio Flow Design, Inc., Chiyoda, Tokyo, Japan. .,Department of Cardiovascular Surgery, Kyoto Prefectural University of Medicine, 1-5 Hangi-cho, Shimogamo, Sakyo-ku, Kyoto, 606-8522, Japan.
| | | | | | - Masataka Sugiyama
- Department of Radiology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Yasuo Takehara
- Department of Radiology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Satoshi Yasukochi
- Department of Pediatric Cardiology, Nagano Children's Hospital, Azumino, Nagano, Japan
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Bowden N, Bryan MT, Duckles H, Feng S, Hsiao S, Kim HR, Mahmoud M, Moers B, Serbanovic-Canic J, Xanthis I, Ridger VC, Evans PC. Experimental Approaches to Study Endothelial Responses to Shear Stress. Antioxid Redox Signal 2016; 25:389-400. [PMID: 26772071 DOI: 10.1089/ars.2015.6553] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
SIGNIFICANCE Shear stress controls multiple physiological processes in endothelial cells (ECs). RECENT ADVANCES The response of ECs to shear has been studied using a range of in vitro and in vivo models. CRITICAL ISSUES This article describes some of the experimental techniques that can be used to study endothelial responses to shear stress. It includes an appraisal of large animal, rodent, and zebrafish models of vascular mechanoresponsiveness. It also describes several bioreactors to apply flow to cells and physical methods to separate mechanoresponses from mass transport mechanisms. FUTURE DIRECTIONS We conclude that combining in vitro and in vivo approaches can provide a detailed mechanistic view of vascular responses to force and that high-throughput systems are required for unbiased assessment of the function of shear-induced molecules. Antioxid. Redox Signal. 25, 389-400.
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Affiliation(s)
- Neil Bowden
- 1 Department of Infection, Immunity and Cardiovascular Disease and INSIGNEO Institute of in silico Medicine, Sheffield, United Kingdom
| | - Matthew T Bryan
- 1 Department of Infection, Immunity and Cardiovascular Disease and INSIGNEO Institute of in silico Medicine, Sheffield, United Kingdom
| | - Hayley Duckles
- 1 Department of Infection, Immunity and Cardiovascular Disease and INSIGNEO Institute of in silico Medicine, Sheffield, United Kingdom
| | - Shuang Feng
- 1 Department of Infection, Immunity and Cardiovascular Disease and INSIGNEO Institute of in silico Medicine, Sheffield, United Kingdom
| | - Sarah Hsiao
- 1 Department of Infection, Immunity and Cardiovascular Disease and INSIGNEO Institute of in silico Medicine, Sheffield, United Kingdom
| | - Hyejeong Rosemary Kim
- 1 Department of Infection, Immunity and Cardiovascular Disease and INSIGNEO Institute of in silico Medicine, Sheffield, United Kingdom .,2 The Bateson Centre, University of Sheffield , Sheffield, United Kingdom
| | - Marwa Mahmoud
- 1 Department of Infection, Immunity and Cardiovascular Disease and INSIGNEO Institute of in silico Medicine, Sheffield, United Kingdom
| | - Britta Moers
- 1 Department of Infection, Immunity and Cardiovascular Disease and INSIGNEO Institute of in silico Medicine, Sheffield, United Kingdom
| | - Jovana Serbanovic-Canic
- 1 Department of Infection, Immunity and Cardiovascular Disease and INSIGNEO Institute of in silico Medicine, Sheffield, United Kingdom .,2 The Bateson Centre, University of Sheffield , Sheffield, United Kingdom
| | - Ioannis Xanthis
- 1 Department of Infection, Immunity and Cardiovascular Disease and INSIGNEO Institute of in silico Medicine, Sheffield, United Kingdom
| | - Victoria C Ridger
- 1 Department of Infection, Immunity and Cardiovascular Disease and INSIGNEO Institute of in silico Medicine, Sheffield, United Kingdom
| | - Paul C Evans
- 1 Department of Infection, Immunity and Cardiovascular Disease and INSIGNEO Institute of in silico Medicine, Sheffield, United Kingdom .,2 The Bateson Centre, University of Sheffield , Sheffield, United Kingdom
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21
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Luong L, Duckles H, Schenkel T, Mahmoud M, Tremoleda JL, Wylezinska-Arridge M, Ali M, Bowden NP, Villa-Uriol MC, van der Heiden K, Xing R, Gijsen FJ, Wentzel J, Lawrie A, Feng S, Arnold N, Gsell W, Lungu A, Hose R, Spencer T, Halliday I, Ridger V, Evans PC. Heart rate reduction with ivabradine promotes shear stress-dependent anti-inflammatory mechanisms in arteries. Thromb Haemost 2016; 116:181-90. [PMID: 27075869 DOI: 10.1160/th16-03-0214] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 03/28/2016] [Indexed: 01/24/2023]
Abstract
Blood flow generates wall shear stress (WSS) which alters endothelial cell (EC) function. Low WSS promotes vascular inflammation and atherosclerosis whereas high uniform WSS is protective. Ivabradine decreases heart rate leading to altered haemodynamics. Besides its cardio-protective effects, ivabradine protects arteries from inflammation and atherosclerosis via unknown mechanisms. We hypothesised that ivabradine protects arteries by increasing WSS to reduce vascular inflammation. Hypercholesterolaemic mice were treated with ivabradine for seven weeks in drinking water or remained untreated as a control. En face immunostaining demonstrated that treatment with ivabradine reduced the expression of pro-inflammatory VCAM-1 (p<0.01) and enhanced the expression of anti-inflammatory eNOS (p<0.01) at the inner curvature of the aorta. We concluded that ivabradine alters EC physiology indirectly via modulation of flow because treatment with ivabradine had no effect in ligated carotid arteries in vivo, and did not influence the basal or TNFα-induced expression of inflammatory (VCAM-1, MCP-1) or protective (eNOS, HMOX1, KLF2, KLF4) genes in cultured EC. We therefore considered whether ivabradine can alter WSS which is a regulator of EC inflammatory activation. Computational fluid dynamics demonstrated that ivabradine treatment reduced heart rate by 20 % and enhanced WSS in the aorta. In conclusion, ivabradine treatment altered haemodynamics in the murine aorta by increasing the magnitude of shear stress. This was accompanied by induction of eNOS and suppression of VCAM-1, whereas ivabradine did not alter EC that could not respond to flow. Thus ivabradine protects arteries by altering local mechanical conditions to trigger an anti-inflammatory response.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Paul C Evans
- Prof. Paul Evans, Department of Cardiovascular Science, Faculty of Medicine, Dentistry & Health, University of Sheffield, Medical School, Beech Hill Road, Sheffield S10 2RX, UK, Tel.: +44 114 271 2591, Fax: +44 114 271 1863, E-mail:
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22
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Osmanagic-Myers S, Rus S, Wolfram M, Brunner D, Goldmann WH, Bonakdar N, Fischer I, Reipert S, Zuzuarregui A, Walko G, Wiche G. Plectin reinforces vascular integrity by mediating crosstalk between the vimentin and the actin networks. J Cell Sci 2015; 128:4138-50. [PMID: 26519478 PMCID: PMC4712781 DOI: 10.1242/jcs.172056] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 10/01/2015] [Indexed: 12/13/2022] Open
Abstract
Mutations in the cytoskeletal linker protein plectin result in multisystemic diseases affecting skin and muscle with indications of additional vascular system involvement. To study the mechanisms underlying vascular disorders, we established plectin-deficient endothelial cell and mouse models. We show that apart from perturbing the vimentin cytoskeleton of endothelial cells, plectin deficiency leads to severe distortions of adherens junctions (AJs), as well as tight junctions, accompanied by an upregulation of actin stress fibres and increased cellular contractility. Plectin-deficient endothelial cell layers were more leaky and showed reduced mechanical resilience in fluid-shear stress and mechanical stretch experiments. We suggest that the distorted AJs and upregulated actin stress fibres in plectin-deficient cells are rooted in perturbations of the vimentin cytoskeleton, as similar phenotypes could be mimicked in wild-type cells by disruption of vimentin filaments. In vivo studies in endothelium-restricted conditional plectin-knockout mice revealed significant distortions of AJs in stress-prone aortic arch regions and increased pulmonary vascular leakage. Our study opens a new perspective on cytoskeleton-controlled vascular permeability, where a plectin-organized vimentin scaffold keeps actomyosin contractility ‘in-check’ and maintains AJ homeostasis. Summary: Plectin-arranged vimentin scaffolds keep actomyosin contractility ‘in-check’ and maintain cell–cell junction homeostasis, providing a new perspective on cytoskeleton-controlled vascular permeability.
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Affiliation(s)
- Selma Osmanagic-Myers
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Stefanie Rus
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Michael Wolfram
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Daniela Brunner
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Wolfgang H Goldmann
- Department of Physics, Friedrich-Alexander-University of Erlangen-Nuremberg, 91052 Erlangen, Germany
| | - Navid Bonakdar
- Department of Physics, Friedrich-Alexander-University of Erlangen-Nuremberg, 91052 Erlangen, Germany
| | - Irmgard Fischer
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Siegfried Reipert
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Aurora Zuzuarregui
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Gernot Walko
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Gerhard Wiche
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
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23
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Van Doormaal M, Zhou YQ, Zhang X, Steinman DA, Mark Henkelman R. Inputs for Subject-Specific Computational Fluid Dynamics Simulation of Blood Flow in the Mouse Aorta. J Biomech Eng 2014; 136:101008. [DOI: 10.1115/1.4028104] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 07/30/2014] [Indexed: 11/08/2022]
Abstract
Mouse models are an important way for exploring relationships between blood hemodynamics and eventual plaque formation. We have developed a mouse model of aortic regurgitation (AR) that produces large changes in plaque burden with charges in hemodynamics [Zhou et al., 2010, "Aortic Regurgitation Dramatically Alters the Distribution of Atherosclerotic Lesions and Enhances Atherogenesis in Mice," Arterioscler. Thromb. Vasc. Biol., 30(6), pp. 1181–1188]. In this paper, we explore the amount of detail needed for realistic computational fluid dynamics (CFD) calculations in this experimental model. The CFD calculations use inputs based on experimental measurements from ultrasound (US), micro computed tomography (CT), and both anatomical magnetic resonance imaging (MRI) and phase contrast MRI (PC-MRI). The adequacy of five different levels of model complexity (a) subject-specific CT data from a single mouse; (b) subject-specific CT centerlines with radii from US; (c) same as (b) but with MRI derived centerlines; (d) average CT centerlines and averaged vessel radius and branching vessels; and (e) same as (d) but with averaged MRI centerlines) is evaluated by demonstrating their impact on relative residence time (RRT) outputs. The paper concludes by demonstrating the necessity of subject-specific geometry and recommends for inputs the use of CT or anatomical MRI for establishing the aortic centerlines, M-mode US for scaling the aortic diameters, and a combination of PC-MRI and Doppler US for estimating the spatial and temporal characteristics of the input wave forms.
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Affiliation(s)
- Mark Van Doormaal
- Mouse Imaging Centre, Hospital for Sick Children, 25 Orde Street, Toronto, ON M5T 3H7, Canada
| | - Yu-Qing Zhou
- Mouse Imaging Centre, Hospital for Sick Children, 25 Orde Street, Toronto, ON M5T 3H7, Canada e-mail:
| | - Xiaoli Zhang
- Mouse Imaging Centre, Hospital for Sick Children, 25 Orde Street, Toronto, ON M5T 3H7, Canada e-mail:
| | - David A. Steinman
- Mechanic and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, ON M5S 3G8, Canada e-mail:
| | - R. Mark Henkelman
- Mem. ASME Mouse Imaging Centre, Hospital for Sick Children, 25 Orde Street, Toronto, ON M5T 3H7, Canada e-mail:
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24
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Le VP, Yamashiro Y, Yanagisawa H, Wagenseil JE. Measuring, reversing, and modeling the mechanical changes due to the absence of Fibulin-4 in mouse arteries. Biomech Model Mechanobiol 2014; 13:1081-95. [PMID: 24526456 DOI: 10.1007/s10237-014-0556-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 01/27/2014] [Indexed: 11/28/2022]
Abstract
Mice with a smooth muscle cell (SMC)-specific deletion of Fibulin-4 (SMKO) show decreased expression of SMC contractile genes, decreased circumferential compliance, and develop aneurysms in the ascending aorta. Neonatal administration of drugs that inhibit the angiotensin II pathway encourages the expression of contractile genes and prevents aneurysm development, but does not increase compliance in SMKO aorta. We hypothesized that multidimensional mechanical changes in the aorta and/or other elastic arteries may contribute to aneurysm pathophysiology. We found that the SMKO ascending aorta and carotid artery showed mechanical changes in the axial direction. These changes were not reversed by angiotensin II inhibitors, hence reversing the axial changes is not required for aneurysm prevention. Mechanical changes in the circumferential direction were specific to the ascending aorta; therefore, mechanical changes in the carotid do not contribute to aortic aneurysm development. We also hypothesized that a published model of postnatal aortic growth and remodeling could be used to investigate mechanisms behind the changes in SMKO aorta and aneurysm development over time. Dimensions and mechanical behavior of adult SMKO aorta were reproduced by the model after modifying the initial component material constants and the aortic dilation with each postnatal time step. The model links biological observations to specific mechanical responses in aneurysm development and treatment.
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Affiliation(s)
- Victoria P Le
- Department of Biomedical Engineering, Saint Louis University, St. Louis, MO, USA
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25
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26
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The impact of MRI-based inflow for the hemodynamic evaluation of aortic coarctation. Ann Biomed Eng 2013; 41:2575-87. [PMID: 23907337 DOI: 10.1007/s10439-013-0879-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 07/24/2013] [Indexed: 10/26/2022]
Abstract
Aortic coarctation (CoA) accounting for 3-11% of congenital heart disease can be successfully treated. Long-term results, however, have revealed decreased life expectancy associated with abnormal hemodynamics. Accordingly, an assessment of hemodynamics is the key factor in treatment decisions and successful long-term results. In this study, 3D angiography whole heart (3DWH) and 4D phase-contrast magnetic resonance imaging (MRI) data were acquired. Geometries of the thoracic aorta with CoAs were reconstructed using ZIB-Amira software. X-ray angiograms were used to evaluate the post-treatment geometry. Computational fluid dynamics models in three patients were created to simulate pre- and post-treatment situations using the FLUENT program. The aim of the study was to investigate the impact of the inlet velocity profile (plug vs. MRI-based) with a focus on the peak systole pressure gradient and wall shear stress (WSS). Results show that helical flow at the aorta inlet can significantly affect the assessment of pressure drop and WSS. Simplified plug inlet velocity profiles significantly (p < 0.05) overestimate the pressure drop in pre- and post-treatment geometries and significantly (p < 0.05) underestimate surface-averaged WSS. We conclude that the use of the physiologically correct but time-expensive 4D MRI-based in vivo velocity profile in CFD studies may be an important step towards a patient-specific analysis of CoA hemodynamics.
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27
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Markl M, Brendecke SM, Simon J, Barker AJ, Weiller C, Harloff A. Co-registration of the distribution of wall shear stress and 140 complex plaques of the aorta. Magn Reson Imaging 2013; 31:1156-62. [PMID: 23773622 DOI: 10.1016/j.mri.2013.05.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2012] [Revised: 05/01/2013] [Accepted: 05/04/2013] [Indexed: 11/17/2022]
Abstract
Previous studies provide evidence that atherosclerosis develops in vascular regions exposed to low wall shear stress (WSS) and high oscillatory shear index (OSI). 4D flow MRI was analyzed in 70 stroke patients with complex plaques (≥4 mm thickness, ulcerated or superimposed thrombi) and in 12 young healthy volunteers. The segmental distribution of peak systolic WSSsystole and OSI was quantified in analysis planes positioned directly at the location of 140 complex plaques found in the 70 patients. In addition, WSSsystole and OSI were evaluated in 8 standard analysis planes distributed along the aorta. Complex plaques were predominantly found at the inner curvature of the aortic arch and of the descending aorta. High OSI was co-located with the segments mostly affected by complex plaque while WSSsystole demonstrated a homogenous distribution. In standard analysis planes, patients demonstrated significantly (p<0.01) altered distribution of wall parameters compared to volunteers (reduced WSSsystole in 91% of aortic wall segments, increased OSI in 48% of segments). OSI distribution was asymmetric with higher values at the inner curvature of the aorta. While WSS and OSI showed expected changes in patients compared to healthy controls, their distribution pattern at complex plaques indicated a more complex and heterogeneous relationship than previously anticipated.
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Affiliation(s)
- Michael Markl
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
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28
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Jeong W, Han MH, Rhee K. Effects of framing coil shape, orientation, and thickness on intra-aneurysmal flow. Med Biol Eng Comput 2013; 51:981-90. [DOI: 10.1007/s11517-013-1073-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 03/29/2013] [Indexed: 11/30/2022]
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29
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Fibromodulin Deficiency Reduces Low-Density Lipoprotein Accumulation in Atherosclerotic Plaques in Apolipoprotein E–Null Mice. Arterioscler Thromb Vasc Biol 2013. [DOI: 10.1161/atvbaha.112.300723] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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