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Lo SCY, McCullough JWS, Xue X, Coveney PV. Uncertainty quantification of the impact of peripheral arterial disease on abdominal aortic aneurysms in blood flow simulations. J R Soc Interface 2024; 21:20230656. [PMID: 38593843 PMCID: PMC11003782 DOI: 10.1098/rsif.2023.0656] [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: 11/07/2023] [Accepted: 03/05/2024] [Indexed: 04/11/2024] Open
Abstract
Peripheral arterial disease (PAD) and abdominal aortic aneurysms (AAAs) often coexist and pose significant risks of mortality, yet their mutual interactions remain largely unexplored. Here, we introduce a fluid mechanics model designed to simulate the haemodynamic impact of PAD on AAA-associated risk factors. Our focus lies on quantifying the uncertainty inherent in controlling the flow rates within PAD-affected vessels and predicting AAA risk factors derived from wall shear stress. We perform a sensitivity analysis on nine critical model parameters through simulations of three-dimensional blood flow within a comprehensive arterial geometry. Our results show effective control of the flow rates using two-element Windkessel models, although specific outlets need attention. Quantities of interest like endothelial cell activation potential (ECAP) and relative residence time are instructive for identifying high-risk regions, with ECAP showing greater reliability and adaptability. Our analysis reveals that the uncertainty in the quantities of interest is 187% of that of the input parameters. Notably, parameters governing the amplitude and frequency of the inlet velocity exert the strongest influence on the risk factors' variability and warrant precise determination. This study forms the foundation for patient-specific simulations involving PAD and AAAs which should ultimately improve patient outcomes and reduce associated mortality rates.
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Affiliation(s)
- Sharp C. Y. Lo
- Centre for Computational Science, University College London, London, UK
| | | | - Xiao Xue
- Centre for Computational Science, University College London, London, UK
| | - Peter V. Coveney
- Centre for Computational Science, University College London, London, UK
- Advanced Research Computing Centre, University College London, London, UK
- Informatics Institute, Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands
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2
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Guerrero-Hurtado M, Garcia-Villalba M, Gonzalo A, Martinez-Legazpi P, Kahn AM, McVeigh E, Bermejo J, del Alamo JC, Flores O. Efficient multi-fidelity computation of blood coagulation under flow. PLoS Comput Biol 2023; 19:e1011583. [PMID: 37889899 PMCID: PMC10659216 DOI: 10.1371/journal.pcbi.1011583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 11/20/2023] [Accepted: 10/09/2023] [Indexed: 10/29/2023] Open
Abstract
Clot formation is a crucial process that prevents bleeding, but can lead to severe disorders when imbalanced. This process is regulated by the coagulation cascade, a biochemical network that controls the enzyme thrombin, which converts soluble fibrinogen into the fibrin fibers that constitute clots. Coagulation cascade models are typically complex and involve dozens of partial differential equations (PDEs) representing various chemical species' transport, reaction kinetics, and diffusion. Solving these PDE systems computationally is challenging, due to their large size and multi-scale nature. We propose a multi-fidelity strategy to increase the efficiency of coagulation cascade simulations. Leveraging the slower dynamics of molecular diffusion, we transform the governing PDEs into ordinary differential equations (ODEs) representing the evolution of species concentrations versus blood residence time. We then Taylor-expand the ODE solution around the zero-diffusivity limit to obtain spatiotemporal maps of species concentrations in terms of the statistical moments of residence time, [Formula: see text], and provide the governing PDEs for [Formula: see text]. This strategy replaces a high-fidelity system of N PDEs representing the coagulation cascade of N chemical species by N ODEs and p PDEs governing the residence time statistical moments. The multi-fidelity order (p) allows balancing accuracy and computational cost providing a speedup of over N/p compared to high-fidelity models. Moreover, this cost becomes independent of the number of chemical species in the large computational meshes typical of the arterial and cardiac chamber simulations. Using a coagulation network with N = 9 and an idealized aneurysm geometry with a pulsatile flow as a benchmark, we demonstrate favorable accuracy for low-order models of p = 1 and p = 2. The thrombin concentration in these models departs from the high-fidelity solution by under 20% (p = 1) and 2% (p = 2) after 20 cardiac cycles. These multi-fidelity models could enable new coagulation analyses in complex flow scenarios and extensive reaction networks. Furthermore, it could be generalized to advance our understanding of other reacting systems affected by flow.
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Affiliation(s)
| | | | - Alejandro Gonzalo
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, United States of America
| | - Pablo Martinez-Legazpi
- Department of Mathematical Physics and Fluids, Facultad de Ciencias, Universidad Nacional de Educación a Distancia, UNED, Spain
- CIBERCV, Madrid, Spain
| | - Andrew M. Kahn
- Division of Cardiovascular Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Elliot McVeigh
- Division of Cardiovascular Medicine, University of California San Diego, La Jolla, California, United States of America
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States of America
- Department of Radiology, University of California San Diego, La Jolla, California, United States of America
| | - Javier Bermejo
- CIBERCV, Madrid, Spain
- Hospital General Universitario Gregorio Marañón, Madrid, Spain
- Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
- Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
| | - Juan C. del Alamo
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, United States of America
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington, United States of America
- Division of Cardiology, University of Washington, Seattle, Washington, United States of America
| | - Oscar Flores
- Department of Aerospace Engineering, Universidad Carlos III de Madrid, Leganés, Spain
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3
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Guerrero-Hurtado M, Garcia-Villalba M, Gonzalo A, Martinez-Legazpi P, Kahn AM, McVeigh E, Bermejo J, Del Alamo JC, Flores O. Efficient multi-fidelity computation of blood coagulation under flow. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.29.542763. [PMID: 37398367 PMCID: PMC10312426 DOI: 10.1101/2023.05.29.542763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Clot formation is a crucial process that prevents bleeding, but can lead to severe disorders when imbalanced. This process is regulated by the coagulation cascade, a biochemical network that controls the enzyme thrombin, which converts soluble fibrinogen into the fibrin fibers that constitute clots. Coagulation cascade models are typically complex and involve dozens of partial differential equations (PDEs) representing various chemical species' transport, reaction kinetics, and diffusion. Solving these PDE systems computationally is challenging, due to their large size and multi-scale nature. We propose a multi-fidelity strategy to increase the efficiency of coagulation cascade simulations. Leveraging the slower dynamics of molecular diffusion, we transform the governing PDEs into ordinary differential equations (ODEs) representing the evolution of species concentrations versus blood residence time. We then Taylor-expand the ODE solution around the zero-diffusivity limit to obtain spatiotemporal maps of species concentrations in terms of the statistical moments of residence time, , and provide the governing PDEs for . This strategy replaces a high-fidelity system of N PDEs representing the coagulation cascade of N chemical species by N ODEs and p PDEs governing the residence time statistical moments. The multi-fidelity order( p ) allows balancing accuracy and computational cost, providing a speedup of over N/p compared to high-fidelity models. Using a simplified coagulation network and an idealized aneurysm geometry with a pulsatile flow as a benchmark, we demonstrate favorable accuracy for low-order models of p = 1 and p = 2. These models depart from the high-fidelity solution by under 16% ( p = 1) and 5% ( p = 2) after 20 cardiac cycles. The favorable accuracy and low computational cost of multi-fidelity models could enable unprecedented coagulation analyses in complex flow scenarios and extensive reaction networks. Furthermore, it can be generalized to advance our understanding of other systems biology networks affected by blood flow.
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Belkacemi D, Tahar Abbes M, Al-Rawi M, Al-Jumaily AM, Bachene S, Laribi B. Intraluminal Thrombus Characteristics in AAA Patients: Non-Invasive Diagnosis Using CFD. Bioengineering (Basel) 2023; 10:bioengineering10050540. [PMID: 37237609 DOI: 10.3390/bioengineering10050540] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 04/24/2023] [Accepted: 04/25/2023] [Indexed: 05/28/2023] Open
Abstract
Abdominal aortic aneurysms (AAA) continue to pose a high mortality risk despite advances in medical imaging and surgery. Intraluminal thrombus (ILT) is detected in most AAAs and may critically impact their development. Therefore, understanding ILT deposition and growth is of practical importance. To assist in managing these patients, the scientific community has been researching the relationship between intraluminal thrombus (ILT) and hemodynamic parameters wall shear stress (WSS) derivatives. This study analyzed three patient-specific AAA models reconstructed from CT scans using computational fluid dynamics (CFD) simulations and a pulsatile non-Newtonian blood flow model. The co-localization and relationship between WSS-based hemodynamic parameters and ILT deposition were examined. The results show that ILT tends to occur in regions of low velocity and time-averaged WSS (TAWSS) and high oscillation shear index (OSI), endothelial cell activation potential (ECAP), and relative residence time (RRT) values. ILT deposition areas were found in regions of low TAWSS and high OSI independently of the nature of flow near the wall characterized by transversal WSS (TransWSS). A new approach is suggested which is based on the estimation of CFD-based WSS indices specifically in the thinnest and thickest ILT areas of AAA patients; this approach is promising and supports the effectiveness of CFD as a decision-making tool for clinicians. Further research with a larger patient cohort and follow-up data are needed to confirm these findings.
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Affiliation(s)
- Djelloul Belkacemi
- Mechanics and Energetics Laboratory, Hassiba Ben Bouali University, Chlef 02000, Algeria
- Unité de Développement des Equipements Solaires UDES, CDER, Bousmail, Tipaza 42415, Algeria
| | - Miloud Tahar Abbes
- Mechanics and Energetics Laboratory, Hassiba Ben Bouali University, Chlef 02000, Algeria
| | - Mohammad Al-Rawi
- Center for Engineering and Industrial Design, Waikato Institute of Technology, Hamilton 3240, New Zealand
| | - Ahmed M Al-Jumaily
- Institute of Biomedical Technologies, Auckland University of Technology, Auckland 1010, New Zealand
| | - Sofiane Bachene
- Radiologie, Centre d'Imagerie Médicale, Cheraga, Algiers 16000, Algeria
| | - Boualem Laribi
- FIMA Laboratory, Department of Technology, Djilali Bounaama University, Khemis Miliana 44225, Algeria
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Mutlu O, Salman HE, Al-Thani H, El-Menyar A, Qidwai UA, Yalcin HC. How does hemodynamics affect rupture tissue mechanics in abdominal aortic aneurysm: Focus on wall shear stress derived parameters, time-averaged wall shear stress, oscillatory shear index, endothelial cell activation potential, and relative residence time. Comput Biol Med 2023; 154:106609. [PMID: 36724610 DOI: 10.1016/j.compbiomed.2023.106609] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 01/19/2023] [Accepted: 01/22/2023] [Indexed: 01/24/2023]
Abstract
An abdominal aortic aneurysm (AAA) is a critical health condition with a risk of rupture, where the diameter of the aorta enlarges more than 50% of its normal diameter. The incidence rate of AAA has increased worldwide. Currently, about three out of every 100,000 people have aortic diseases. The diameter and geometry of AAAs influence the hemodynamic forces exerted on the arterial wall. Therefore, a reliable assessment of hemodynamics is crucial for predicting the rupture risk. Wall shear stress (WSS) is an important metric to define the level of the frictional force on the AAA wall. Excessive levels of WSS deteriorate the remodeling mechanism of the arteries and lead to abnormal conditions. At this point, WSS-related hemodynamic parameters, such as time-averaged WSS (TAWSS), oscillatory shear index (OSI), endothelial cell activation potential (ECAP), and relative residence time (RRT) provide important information to evaluate the shear environment on the AAA wall in detail. Calculation of these parameters is not straightforward and requires a physical understanding of what they represent. In addition, computational fluid dynamics (CFD) solvers do not readily calculate these parameters when hemodynamics is simulated. This review aims to explain the WSS-derived parameters focusing on how these represent different characteristics of disturbed hemodynamics. A representative case is presented for spatial and temporal formulation that would be useful for interested researchers for practical calculations. Finally, recent hemodynamics investigations relating WSS-related parameters with AAA rupture risk assessment are presented. This review will be useful to understand the physical representation of WSS-related parameters in cardiovascular flows and how they can be calculated practically for AAA investigations.
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Affiliation(s)
- Onur Mutlu
- Biomedical Research Center, Qatar University, Doha, Qatar
| | - Huseyin Enes Salman
- Department of Mechanical Engineering, TOBB University of Economics and Technology, Ankara, Turkey
| | - Hassan Al-Thani
- Department of Surgery, Trauma and Vascular Surgery, Hamad General Hospital, Hamad Medical Corporation, P.O. Box 3050, Doha, Qatar
| | - Ayman El-Menyar
- Department of Surgery, Trauma and Vascular Surgery, Hamad General Hospital, Hamad Medical Corporation, P.O. Box 3050, Doha, Qatar; Clinical Medicine, Weill Cornell Medical College, Doha, Qatar
| | - Uvais Ahmed Qidwai
- Department of Computer Science Engineering, Qatar University, Doha, Qatar
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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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Hossack M, Fisher R, Torella F, Madine J, Field M, Akhtar R. Micromechanical and Ultrastructural Properties of Abdominal Aortic Aneurysms. Artery Res 2022. [DOI: 10.1007/s44200-022-00011-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
AbstractAbdominal aortic aneurysms are a common condition of uncertain pathogenesis that can rupture if left untreated. Current recommended thresholds for planned repair are empirical and based entirely on diameter. It has been observed that some aneurysms rupture before reaching the threshold for repair whilst other larger aneurysms do not rupture. It is likely that geometry is not the only factor influencing rupture risk. Biomechanical indices aiming to improve and personalise rupture risk prediction require, amongst other things, knowledge of the material properties of the tissue and realistic constitutive models. These depend on the composition and organisation of the vessel wall which has been shown to undergo drastic changes with aneurysmal degeneration, with loss of elastin, smooth muscle cells, and an accumulation of isotropically arranged collagen. Most aneurysms are lined with intraluminal thrombus, which has an uncertain effect on the underlying vessel wall, with some authors demonstrating a reduction in wall stress and others a reduction in wall strength. The majority of studies investigating biomechanical properties of ex vivo abdominal aortic aneurysm tissues have used low-resolution techniques, such as tensile testing, able to measure the global material properties at the macroscale. High-resolution engineering techniques such as nanoindentation and atomic force microscopy have been modified for use in soft biological tissues and applied to vascular tissues with promising results. These techniques have the potential to advance the understanding and improve the management of abdominal aortic aneurysmal disease.
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Philip NT, Patnaik BSV, Sudhir BJ. Hemodynamic simulation of abdominal aortic aneurysm on idealised models: Investigation of stress parameters during disease progression. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 213:106508. [PMID: 34800807 DOI: 10.1016/j.cmpb.2021.106508] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 10/25/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND AND OBJECTIVE Analysis and prediction of rupture risk of abdominal aortic aneurysms (AAA) facilitates planning for surgical interventions and assessment of plausible treatment modalities. Present approach of using maximum diameter criterion, is giving way to hemodynamic and bio-mechanical based predictors in conjunction with Computational fluid dynamic (CFD) simulations. Detailed studies on hemodynamic and bio-mechanical parameters at the stage of maximum growth/rupture is of practical importance to the clinical community. However, understanding the changes in these parameters at different stages of growth, will be useful for clinicians, in planning routine monitoring to reduce the risk of sudden rupture. This is particularly useful in medical resource starved nations. Present study investigates the hemodynamic and bio-mechanical changes occurring during the growth stages of aortic aneurysms using fluid structure interaction (FSI) studies. METHOD Six idealized fusiform aneurysm models spanning high (shorter) and low (longer) values of the shape index (DHr), have been analysed at three different stages of growth viz, a Dmax of 3.5cm, 4.25cm, 5cm. Pulsatile Newtonian blood flow, passing through an elastic arterial vessel wall with uniform thickness is assumed. Two-way coupled fluid structure interaction have been employed for the numerical simulation of blood flow dynamics and arterial wall mechanics. RESULTS Wall shear stress (WSS) parameters and vonmises stress indicators, co-relating rupture and thrombus formation, have been extracted and reported, at each growth stage. When the aneurysm progresses in diameter, the areas recording abnormally low TAWSS, as well as areas of high/low OSI were found to increase at different rates for shorter and longer aneurysms. Moreover, drastic increase in the maximum wall stresses (MWS) and wall displacement were observed as the aneurysm approached the critical diameter. CONCLUSION Hemodynamic predictors were found to be highly dependent on the shape index (DHr), when the aneurysm was small, whereas significant influence of DHr on the wall stresses happens, as the aneurysm approaches the critical diameter. Inconsistent variation of these indicators exhibited by shorter aneurysms (high DHr) at different growth stages, demands routine monitoring (using scans), of such aneurysms, to prevent unexpected rupture.
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Affiliation(s)
- Nimmy Thankom Philip
- Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai, 600036, India
| | - B S V Patnaik
- Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai, 600036, India
| | - B J Sudhir
- Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, 695011, Kerala.
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Boyd AJ. Intraluminal thrombus: Innocent bystander or factor in abdominal aortic aneurysm pathogenesis? JVS Vasc Sci 2021; 2:159-169. [PMID: 34617066 PMCID: PMC8489244 DOI: 10.1016/j.jvssci.2021.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 02/20/2021] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Abdominal aortic aneurysms (AAAs) represent a complex multifactorial hemodynamic, thrombotic, and inflammatory process that can ultimately result in aortic rupture and death. Despite improved screening and surgical management of AAAs, the mortality rates have remained high after rupture, and little progress has occurred in the development of nonoperative treatments. Intraluminal thrombus (ILT) is present in most AAAs and might be involved in AAA pathogenesis. The present review examined the latest clinical and experimental evidence for possible involvement of the ILT in AAA growth and rupture. METHODS A literature review was performed after a search of the PubMed database from 2012 to June 2020 using the terms "abdominal aortic aneurysm" and "intraluminal thrombus." RESULTS The structure, composition, and hemodynamics of ILT formation and propagation were reviewed in relation to the hemostatic and proteolytic factors favoring ILT deposition. The potential effects of the ILT on AAA wall degeneration and rupture, including a review of the current controversies regarding the position, thickness, and composition of ILT, are presented. Although initially potentially protective against increased wall stress, increasing evidence has shown that an increased volume and greater age of the ILT have direct detrimental effects on aortic wall integrity, which might predispose to an increased rupture risk. CONCLUSIONS ILT does not appear to be an innocent bystander in AAA pathophysiology. However, its exact role remains elusive and controversial. Despite computational evidence of a possible protective role of the ILT in reducing wall stress, increasing evidence has shown that the ILT promotes AAA wall degeneration in humans and in animal models. Further research, with large animal models and with more chronic ILT is crucial for a better understanding of the role of the ILT in AAAs and for the potential development of targeted therapies to slow or halt AAA progression.
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Affiliation(s)
- April J. Boyd
- Department of Vascular Surgery, University of Manitoba, Winnipeg, Manitoba, Canada
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10
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Computational Fluid Dynamics Modeling of Hemodynamic Parameters in the Human Diseased Aorta: A Systematic Review. Ann Vasc Surg 2020; 63:336-381. [DOI: 10.1016/j.avsg.2019.04.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 03/09/2019] [Accepted: 04/18/2019] [Indexed: 02/07/2023]
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11
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Joly F, Soulez G, Lessard S, Kauffmann C, Vignon-Clementel I. A Cohort Longitudinal Study Identifies Morphology and Hemodynamics Predictors of Abdominal Aortic Aneurysm Growth. Ann Biomed Eng 2019; 48:606-623. [DOI: 10.1007/s10439-019-02375-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 09/24/2019] [Indexed: 12/19/2022]
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12
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Moulakakis KG, Kakisis J, Gonidaki E, Lazaris AM, Tsangaris S, Geroulakos G, Manopoulos C. Comparison of Fluid Dynamics Variations Between Chimney and Fenestrated Endografts for Pararenal Aneurysms Repair: A Patient Specific Computational Study as Motivation for Clinical Decision-Making. Vasc Endovascular Surg 2019; 53:572-582. [PMID: 31382837 DOI: 10.1177/1538574419867531] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND-AIM Limited data exist concerning the fluid dynamic changes induced by endovascular aortic repair with fenestrated and chimney graft modalities in pararenal aneurysms. We aimed to investigate and compare the wall shear stress (WSS) and flow dynamics for the branch vessels before and after endovascular aortic repair with fenestrated and chimney techniques. METHODS Modeling was done for patient specific pararenal aortic aneurysms employing fenestrated and chimney grafts (Materialise Mimics 10.0) before and after the endovascular procedure, using computed tomography scans of patients. Surface and spatial grids were created using the ANSYS CFD meshing software 2019 R2. Assessment of blood flow, streamlines, and WSS before and after aneurysm repair was performed. RESULTS The endovascular repair with chimney grafts leaded to a 43% to 53% reduction in perfusion in renal arteries. In fenestrated reconstruction, we observed a 15% reduced perfusion in both renal arteries. In both cases, we observed a decrease in the recirculation phenomena of the aorta after endovascular repair. Concerning the grafts of the renal arteries, we observed in both the transverse and longitudinal axes low WSS regions with simultaneous recirculation of the flow 1 cm distal to the ostium sites in both aortic graft models. High WSS regions appeared in the sites of ostium. CONCLUSIONS We observed reduced renal perfusion in chimney grafts compared to fenestrated grafts, probably caused by the long and kinked characteristics of these devices.
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Affiliation(s)
- Konstantinos G Moulakakis
- 1 Department of Vascular Surgery, Medical School, National and Kapodistrian University of Athens, Attikon University Hospital, Athens, Greece
| | - John Kakisis
- 1 Department of Vascular Surgery, Medical School, National and Kapodistrian University of Athens, Attikon University Hospital, Athens, Greece
| | - Eleni Gonidaki
- 2 Biofluid Mechanics and Biomedical Engineering Laboratory, Fluids Section, School of Mechanical Engineering, National Technical University of Athens, Greece
| | - Andreas M Lazaris
- 1 Department of Vascular Surgery, Medical School, National and Kapodistrian University of Athens, Attikon University Hospital, Athens, Greece
| | - Sokrates Tsangaris
- 2 Biofluid Mechanics and Biomedical Engineering Laboratory, Fluids Section, School of Mechanical Engineering, National Technical University of Athens, Greece
| | - George Geroulakos
- 1 Department of Vascular Surgery, Medical School, National and Kapodistrian University of Athens, Attikon University Hospital, Athens, Greece
| | - Christos Manopoulos
- 2 Biofluid Mechanics and Biomedical Engineering Laboratory, Fluids Section, School of Mechanical Engineering, National Technical University of Athens, Greece
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Salman HE, Ramazanli B, Yavuz MM, Yalcin HC. Biomechanical Investigation of Disturbed Hemodynamics-Induced Tissue Degeneration in Abdominal Aortic Aneurysms Using Computational and Experimental Techniques. Front Bioeng Biotechnol 2019; 7:111. [PMID: 31214581 PMCID: PMC6555197 DOI: 10.3389/fbioe.2019.00111] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 05/02/2019] [Indexed: 11/13/2022] Open
Abstract
Abdominal aortic aneurysm (AAA) is the dilatation of the aorta beyond 50% of the normal vessel diameter. It is reported that 4-8% of men and 0.5-1% of women above 50 years of age bear an AAA and it accounts for ~15,000 deaths per year in the United States alone. If left untreated, AAA might gradually expand until rupture; the most catastrophic complication of the aneurysmal disease that is accompanied by a striking overall mortality of 80%. The precise mechanisms leading to AAA rupture remains unclear. Therefore, characterization of disturbed hemodynamics within AAAs will help to understand the mechanobiological development of the condition which will contribute to novel therapies for the condition. Due to geometrical complexities, it is challenging to directly quantify disturbed flows for AAAs clinically. Two other approaches for this investigation are computational modeling and experimental flow measurement. In computational modeling, the problem is first defined mathematically, and the solution is approximated with numerical techniques to get characteristics of flow. In experimental flow measurement, once the setup providing physiological flow pattern in a phantom geometry is constructed, velocity measurement system such as particle image velocimetry (PIV) enables characterization of the flow. We witness increasing number of applications of these complimentary approaches for AAA investigations in recent years. In this paper, we outline the details of computational modeling procedures and experimental settings and summarize important findings from recent studies, which will help researchers for AAA investigations and rupture mechanics.
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Affiliation(s)
| | - Burcu Ramazanli
- Department of Mechanical Engineering, Middle East Technical University, Ankara, Turkey
| | - Mehmet Metin Yavuz
- Department of Mechanical Engineering, Middle East Technical University, Ankara, Turkey
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14
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Strongly Coupled Morphological Features of Aortic Aneurysms Drive Intraluminal Thrombus. Sci Rep 2018; 8:13273. [PMID: 30185838 PMCID: PMC6125404 DOI: 10.1038/s41598-018-31637-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 08/15/2018] [Indexed: 01/13/2023] Open
Abstract
Over 75% of abdominal aortic aneurysms harbor an intraluminal thrombus, and increasing evidence suggests that biologically active thrombus contributes to the natural history of these potentially lethal lesions. Thrombus formation depends on the local hemodynamics, which in turn depends on morphological features of the aneurysm and near vasculature. We previously presented a hemodynamically motivated “thrombus formation potential” that predicts where and when thrombus might form. Herein, we combine detailed studies of the three-dimensional hemodynamics with methods of sparse grid collocation and interpolation via kriging to examine roles of five key morphological features of aneurysms on thrombus formation: lesion diameter, axial position, length, curvature, and renal artery position. Computational simulations suggest that maximum diameter is a key determinant of thrombogenicity, but other morphological features modulate this dependence. More distally located lesions tend to have a higher thrombus formation potential and shorter lesions tend to have a higher potential than longer lesions, given the same aneurysmal dilatation. Finally, movement of vortical structures through the infrarenal aorta and lesion can significantly affect thrombogenicity. Formation of intraluminal thrombus within an evolving abdominal aortic aneurysm thus depends on coupled morphological features, not all intuitive, and computational simulations can be useful for predicting thrombogenesis.
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15
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Kemmerling EMC, Peattie RA. Abdominal Aortic Aneurysm Pathomechanics: Current Understanding and Future Directions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1097:157-179. [DOI: 10.1007/978-3-319-96445-4_8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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16
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Virag L, Wilson JS, Humphrey JD, Karšaj I. Potential biomechanical roles of risk factors in the evolution of thrombus-laden abdominal aortic aneurysms. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33:10.1002/cnm.2893. [PMID: 28447404 PMCID: PMC5658277 DOI: 10.1002/cnm.2893] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 02/23/2017] [Accepted: 04/23/2017] [Indexed: 05/22/2023]
Abstract
Abdominal aortic aneurysms (AAAs) typically harbour an intraluminal thrombus (ILT), yet most prior computational models neglect biochemomechanical effects of thrombus on lesion evolution. We recently proposed a growth and remodelling model of thrombus-laden AAAs that introduced a number of new constitutive relations and associated model parameters. Because values of several of these parameters have yet to be elucidated by clinical data and could vary significantly from patient to patient, the aim of this study was to investigate the possible extent to which these parameters influence AAA evolution. Given that some of these parameters model potential effects of factors that influence the risk of rupture, this study also provides insight into possible roles of common risk factors on the natural history of AAAs. Despite geometrical limitations of a cylindrical domain, findings support current thought that smoking, hypertension, and female sex likely increase the risk of rupture. Although thrombus thickness is not a reliable risk factor for rupture, the model suggests that the presence of ILT may have a destabilizing effect on AAA evolution, consistent with histological findings from human samples. Finally, simulations support two hypotheses that should be tested on patient-specific geometries in the future. First, ILT is a potential source of the staccato enlargement observed in many AAAs. Second, ILT can influence rupture risk, positively or negatively, via competing biomechanical (eg, stress shielding) and biochemical (ie, proteolytic) effects. Although further computational and experimental studies are needed, the present findings highlight the importance of considering ILT when predicting aneurysmal enlargement and rupture risk.
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Affiliation(s)
- Lana Virag
- Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Zagreb, Croatia
| | - John S. Wilson
- Department of Radiology, Emory University, Atlanta, GA, USA
| | - Jay D. Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, USA
| | - Igor Karšaj
- Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Zagreb, Croatia
- Address for Correspondence: Igor Karšaj, Ph.D., Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, Zagreb, 10000, Croatia, Phone: +38516168125,
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17
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Large eddy simulations of blood dynamics in abdominal aortic aneurysms. Med Eng Phys 2017; 47:38-46. [PMID: 28709929 DOI: 10.1016/j.medengphy.2017.06.030] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 06/02/2017] [Accepted: 06/14/2017] [Indexed: 02/07/2023]
Abstract
We study the effects of transition to turbulence in abdominal aortic aneurysms (AAA). The presence of transitional effects in such districts is related to the heart pulsatility and the sudden change of diameter of the vessels, and has been recorded by means of clinical measures as well as of computational studies. Here we propose, for the first time, the use of a large eddy simulation (LES) model to accurately describe transition to turbulence in realistic scenarios of AAA obtained from radiological images. To this aim, we post-process the obtained numerical solutions to assess significant quantities, such as the ensemble-averaged velocity and wall shear stress, the standard deviation of the fluctuating velocity field, and vortical structures educed via the so-called Q-criterion. The results demonstrate the suitability of the considered LES model and show the presence of significant transitional effects around the impingement region during the mid-deceleration phase.
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18
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Di Achille P, Tellides G, Humphrey J. Hemodynamics-driven deposition of intraluminal thrombus in abdominal aortic aneurysms. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33:10.1002/cnm.2828. [PMID: 27569676 PMCID: PMC5332472 DOI: 10.1002/cnm.2828] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 07/06/2016] [Accepted: 08/25/2016] [Indexed: 05/18/2023]
Abstract
Accumulating evidence suggests that intraluminal thrombus plays many roles in the natural history of abdominal aortic aneurysms. There is, therefore, a pressing need for computational models that can describe and predict the initiation and progression of thrombus in aneurysms. In this paper, we introduce a phenomenological metric for thrombus deposition potential and use hemodynamic simulations based on medical images from 6 patients to identify best-fit values of the 2 key model parameters. We then introduce a shape optimization method to predict the associated radial growth of the thrombus into the lumen based on the expectation that thrombus initiation will create a thrombogenic surface, which in turn will promote growth until increasing hemodynamically induced frictional forces prevent any further cell or protein deposition. Comparisons between predicted and actual intraluminal thrombus in the 6 patient-specific aneurysms suggest that this phenomenological description provides a good first estimate of thrombus deposition. We submit further that, because the biologically active region of the thrombus appears to be confined to a thin luminal layer, predictions of morphology alone may be sufficient to inform fluid-solid-growth models of aneurysmal growth and remodeling.
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Affiliation(s)
- P. Di Achille
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - G. Tellides
- Department of Surgery, Yale School of Medicine, New Haven, CT, USA
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, USA
| | - J.D. Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, USA
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19
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Kelsey LJ, Powell JT, Norman PE, Miller K, Doyle BJ. A comparison of hemodynamic metrics and intraluminal thrombus burden in a common iliac artery aneurysm. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33:e2821. [PMID: 27509188 DOI: 10.1002/cnm.2821] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 06/06/2016] [Accepted: 07/02/2016] [Indexed: 06/06/2023]
Abstract
Aneurysms of the common iliac artery (CIAA) are typically found in association with an abdominal aortic aneurysm (AAA). Isolated CIAAs, in the absence of an AAA, are uncommon. Similar to AAAs, CIAA may develop intraluminal thrombus (ILT). As isolated CIAAs have a contralateral common iliac artery for comparison, they provide an opportunity to study the hemodynamic mechanisms behind ILT formation. In this study, we compared a large isolated CIAA and the contralateral iliac artery using computational fluid dynamics to determine if hemodynamic metrics correlate with the location of ILT. We performed a comprehensive computational fluid dynamics study and investigated the residence time of platelets and monocytes, velocity fields, time-averaged wall shear stress, oscillatory shear index, and endothelial cell activation potential. We then correlated these data to ILT burden determined with computed tomography. We found that high cell residence times, low time-averaged wall shear stress, high oscillatory shear index, and high endothelial cell activation potential all correlate with regions of ILT development. Our results show agreement with previous hypotheses of thrombus formation in AAA and provide insights into the computational hemodynamics of iliac artery aneurysms.
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Affiliation(s)
- Lachlan J Kelsey
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Perth, WA, Australia
- Intelligent Systems for Medicine Laboratory, School of Mechanical and Chemical Engineering, The University of Western Australia, Crawley, WA, Australia
| | - Janet T Powell
- Vascular Surgery Research Group, Imperial College London, London, UK
| | - Paul E Norman
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Perth, WA, Australia
- School of Surgery, The University of Western Australia, Crawley, WA, Australia
| | - Karol Miller
- Intelligent Systems for Medicine Laboratory, School of Mechanical and Chemical Engineering, The University of Western Australia, Crawley, WA, Australia
- Institute of Mechanics and Advanced Materials, Cardiff University, Cardiff, UK
| | - Barry J Doyle
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Perth, WA, Australia
- School of Mechanical and Chemical Engineering, The University of Western Australia, Crawley, WA, Australia
- British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK
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20
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Lozowy RJ, Kuhn DCS, Ducas AA, Boyd AJ. The Relationship Between Pulsatile Flow Impingement and Intraluminal Thrombus Deposition in Abdominal Aortic Aneurysms. Cardiovasc Eng Technol 2016; 8:57-69. [DOI: 10.1007/s13239-016-0287-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 11/07/2016] [Indexed: 11/28/2022]
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21
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Aramburu J, Antón R, Borro D, Rivas A, Larraona GS, Ramos JC, Finol EA. A methodology for assessing local bifurcated blood vessel shape variations. Biomed Phys Eng Express 2016. [DOI: 10.1088/2057-1976/2/1/015001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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22
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Tong J, Holzapfel GA. Structure, Mechanics, and Histology of Intraluminal Thrombi in Abdominal Aortic Aneurysms. Ann Biomed Eng 2015; 43:1488-501. [DOI: 10.1007/s10439-015-1332-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 05/06/2015] [Indexed: 01/08/2023]
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23
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Zhang P, Liu X, Sun A, Fan Y, Deng X. Hemodynamic insight into overlapping bare-metal stents strategy in the treatment of aortic aneurysm. J Biomech 2015; 48:2041-6. [PMID: 25911250 DOI: 10.1016/j.jbiomech.2015.03.028] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 03/18/2015] [Accepted: 03/22/2015] [Indexed: 10/23/2022]
Abstract
Clinical trials have shown overlapping bare-metal stents provoke effective thrombus clot within the aneurysm sac and shrinkage of the aneurysm by directly regulating the hemodynamics. To gain insight into the hemodynamic mechanism of the technique, three cases of simplified thoracic aortic aneurysm models (with no stent, a single stent and two overlapped stents deployed within the aneurysm sac) were studied and compared in terms of time-varying velocity and shear rate, time-averaged wall shear stress (TAWSS), oscillating shear index (OSI) and relative residence time (RRT). The results demonstrated that the overlapping stents' strategy was more effective in reducing the velocity of blood flow within the aneurysm, especially for the area near the aneurysm wall. Stenting induced a dramatic change trend of shear rate during the cardiac cycle, in which a very high shear rate (>10,000 s(-1)) during the systole and a quite low shear rate (<1000 s(-1)) during the diastole were observed, respectively. Moreover, reduced TAWSS and OSI and elevated RRT values were observed on the aneurysm wall after stent placement. The effects of stenting on the shear rate, TAWSS, OSI and RRT in the aneurysm would be significantly enhanced by two overlapped stents. The present findings therefore indicated that, the overlapping bare-metal stents can isolate the aneurysm effectively and may create a favorable hemodynamic environment provoking platelets activation and aggregation within the aneurysm, which may promote thrombus formation/growth there, hence contribute to degradation of the aneurysm.
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Affiliation(s)
- Peng Zhang
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Xiao Liu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China.
| | - Anqiang Sun
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Yubo Fan
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Xiaoyan Deng
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China.
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24
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Raptis A, Xenos M, Dimas S, Giannoukas A, Labropoulos N, Bluestein D, Matsagkas MI. Effect of macroscale formation of intraluminal thrombus on blood flow in abdominal aortic aneurysms. Comput Methods Biomech Biomed Engin 2015; 19:84-92. [DOI: 10.1080/10255842.2014.989389] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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25
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Arzani A, Suh GY, Dalman RL, Shadden SC. A longitudinal comparison of hemodynamics and intraluminal thrombus deposition in abdominal aortic aneurysms. Am J Physiol Heart Circ Physiol 2014; 307:H1786-95. [PMID: 25326533 DOI: 10.1152/ajpheart.00461.2014] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Abdominal aortic aneurysm (AAA) is often accompanied by in traluminal thrombus (ILT), which complicates AAA progression and risk of rupture. Patient-specific computational fluid dynamics modeling of 10 small human AAA was performed to investigate relations between hemodynamics and ILT progression. The patients were imaged using magnetic resonance twice in a 2- to 3-yr interval. Wall content data were obtained by a planar T1-weighted fast spin echo black-blood scan, which enabled quantification of thrombus thickness at midaneurysm location during baseline and followup. Computational simulations with patient-specific geometry and boundary conditions were performed to quantify the hemodynamic parameters of time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and mean exposure time at baseline. Spatially resolved quantifications of the change in ILT thickness were compared with the different hemodynamic parameters. Regions of low OSI had the strongest correlation with ILT growth and demonstrated a statistically significant correlation coefficient. Prominent regions of high OSI (>0.4) and low TAWSS (<1 dyn/cm(2)) did not appear to coincide with locations of thrombus deposition.
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Affiliation(s)
- Amirhossein Arzani
- Mechanical Engineering, University of California, Berkeley, California; and
| | - Ga-Young Suh
- Division of Vascular Surgery, Stanford University, Stanford, California
| | - Ronald L Dalman
- Division of Vascular Surgery, Stanford University, Stanford, California
| | - Shawn C Shadden
- Mechanical Engineering, University of California, Berkeley, California; and
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26
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Deplano V, Knapp Y, Bailly L, Bertrand E. Flow of a blood analogue fluid in a compliant abdominal aortic aneurysm model: experimental modelling. J Biomech 2014; 47:1262-9. [PMID: 24612986 DOI: 10.1016/j.jbiomech.2014.02.026] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 02/18/2014] [Accepted: 02/18/2014] [Indexed: 10/25/2022]
Abstract
The aim of this work is to develop a unique in vitro set-up in order to analyse the influence of the shear thinning fluid-properties on the flow dynamics within the bulge of an abdominal aortic aneurysm (AAA). From an experimental point of view, the goals are to elaborate an analogue shear thinning fluid mimicking the macroscopic blood behaviour, to characterise its rheology at low shear rates and to propose an experimental device able to manage such an analogue fluid without altering its feature while reproducing physiological flow rate and pressure, through compliant AAA. Once these experimental prerequisites achieved, the results obtained in the present work show that the flow dynamics is highly dependent on the fluid rheology. The main results point out that the propagation of the vortex ring, generated in the AAA bulge, is slower for shear thinning fluids inducing a smaller travelled distance by the vortex ring so that it never impacts the anterior wall in the distal region, in opposition to Newtonian fluids. Moreover, scalar shear rate values are globally lower for shear thinning fluids inducing higher maximum stress values than those for the Newtonian fluids. Consequently, this work highlights that a Newtonian fluid model is finally inadequate to obtain a reliable prediction of the flow dynamics within AAA.
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Affiliation(s)
- Valérie Deplano
- Aix-Marseille Université, CNRS, Centrale Marseille, IRPHE UMR 7342, F-13384 Marseille, France.
| | - Yannick Knapp
- Université d׳Avignon, LAPEC EA4278, F-84000 Avignon, France
| | - Lucie Bailly
- Aix-Marseille Université, CNRS, Centrale Marseille, IRPHE UMR 7342, F-13384 Marseille, France
| | - Eric Bertrand
- Aix-Marseille Université, CNRS, Centrale Marseille, IRPHE UMR 7342, F-13384 Marseille, France
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27
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Wilson JS, Virag L, Di Achille P, Karsaj I, Humphrey JD. Biochemomechanics of intraluminal thrombus in abdominal aortic aneurysms. J Biomech Eng 2013; 135:021011. [PMID: 23445056 DOI: 10.1115/1.4023437] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Most computational models of abdominal aortic aneurysms address either the hemodynamics within the lesion or the mechanics of the wall. More recently, however, some models have appropriately begun to account for the evolving mechanics of the wall in response to the changing hemodynamic loads. Collectively, this large body of work has provided tremendous insight into this life-threatening condition and has provided important guidance for current research. Nevertheless, there has yet to be a comprehensive model that addresses the mechanobiology, biochemistry, and biomechanics of thrombus-laden abdominal aortic aneurysms. That is, there is a pressing need to include effects of the hemodynamics on both the development of the nearly ubiquitous intraluminal thrombus and the evolving mechanics of the wall, which depends in part on biochemical effects of the adjacent thrombus. Indeed, there is increasing evidence that intraluminal thrombus in abdominal aortic aneurysms is biologically active and should not be treated as homogeneous inert material. In this review paper, we bring together diverse findings from the literature to encourage next generation models that account for the biochemomechanics of growth and remodeling in patient-specific, thrombus-laden abdominal aortic aneurysms.
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Affiliation(s)
- J S Wilson
- Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA
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28
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Hardman D, Doyle BJ, Semple SIK, Richards JMJ, Newby DE, Easson WJ, Hoskins PR. On the prediction of monocyte deposition in abdominal aortic aneurysms using computational fluid dynamics. Proc Inst Mech Eng H 2013; 227:1114-24. [DOI: 10.1177/0954411913494319] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In abdominal aortic aneurysm disease, the aortic wall is exposed to intense biological activity involving inflammation and matrix metalloproteinase–mediated degradation of the extracellular matrix. These processes are orchestrated by monocytes and rather than affecting the aorta uniformly, damage and weaken focal areas of the wall leaving it vulnerable to rupture. This study attempts to model numerically the deposition of monocytes using large eddy simulation, discrete phase modelling and near-wall particle residence time. The model was first applied to idealised aneurysms and then to three patient-specific lumen geometries using three-component inlet velocities derived from phase-contrast magnetic resonance imaging. The use of a novel, variable wall shear stress-limiter based on previous experimental data significantly improved the results. Simulations identified a critical diameter (1.8 times the inlet diameter) beyond which significant monocyte deposition is expected to occur. Monocyte adhesion occurred proximally in smaller abdominal aortic aneurysms and distally as the sac expands. The near-wall particle residence time observed in each of the patient-specific models was markedly different. Discrete hotspots of monocyte residence time were detected, suggesting that the monocyte infiltration responsible for the breakdown of the abdominal aortic aneurysm wall occurs heterogeneously. Peak monocyte residence time was found to increase with aneurysm sac size. Further work addressing certain limitations is needed in a larger cohort to determine clinical significance.
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Affiliation(s)
- David Hardman
- Centre for Cardiovascular Science, Queens Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - Barry J Doyle
- Centre for Cardiovascular Science, Queens Medical Research Institute, The University of Edinburgh, Edinburgh, UK
- Intelligent Systems for Medicine Laboratory, School of Mechanical and Chemical Engineering, The University of Western Australia, Crawley, WA, Australia
| | - Scott IK Semple
- Centre for Cardiovascular Science, Queens Medical Research Institute, The University of Edinburgh, Edinburgh, UK
- Clinical Research Imaging Centre, The University of Edinburgh, Edinburgh, UK
| | - Jennifer MJ Richards
- Centre for Cardiovascular Science, Queens Medical Research Institute, The University of Edinburgh, Edinburgh, UK
- Clinical Research Imaging Centre, The University of Edinburgh, Edinburgh, UK
- Centre of Clinical and Surgical Sciences (Surgery), The University of Edinburgh, Edinburgh, UK
| | - David E Newby
- Centre for Cardiovascular Science, Queens Medical Research Institute, The University of Edinburgh, Edinburgh, UK
- Clinical Research Imaging Centre, The University of Edinburgh, Edinburgh, UK
| | - William J Easson
- Institute for Materials and Processes, School of Engineering and Electronics, The University of Edinburgh, Edinburgh, UK
| | - Peter R Hoskins
- Centre for Cardiovascular Science, Queens Medical Research Institute, The University of Edinburgh, Edinburgh, UK
- Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick, Ireland
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