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Risk Factors and Mouse Models of Abdominal Aortic Aneurysm Rupture. Int J Mol Sci 2020; 21:ijms21197250. [PMID: 33008131 PMCID: PMC7583758 DOI: 10.3390/ijms21197250] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 08/19/2020] [Accepted: 08/28/2020] [Indexed: 02/07/2023] Open
Abstract
Abdominal aortic aneurysm (AAA) rupture is an important cause of death in older adults. In clinical practice, the most established predictor of AAA rupture is maximum AAA diameter. Aortic diameter is commonly used to assess AAA severity in mouse models studies. AAA rupture occurs when the stress (force per unit area) on the aneurysm wall exceeds wall strength. Previous research suggests that aortic wall structure and strength, biomechanical forces on the aorta and cellular and proteolytic composition of the AAA wall influence the risk of AAA rupture. Mouse models offer an opportunity to study the association of these factors with AAA rupture in a way not currently possible in patients. Such studies could provide data to support the use of novel surrogate markers of AAA rupture in patients. In this review, the currently available mouse models of AAA and their relevance to the study of AAA rupture are discussed. The review highlights the limitations of mouse models and suggests novel approaches that could be incorporated in future experimental AAA studies to generate clinically relevant results.
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Mix DS, Yang L, Johnson CC, Couper N, Zarras B, Arabadjis I, Trakimas LE, Stoner MC, Day SW, Richards MS. Detecting Regional Stiffness Changes in Aortic Aneurysmal Geometries Using Pressure-Normalized Strain. ULTRASOUND IN MEDICINE & BIOLOGY 2017; 43:2372-2394. [PMID: 28728780 PMCID: PMC5562537 DOI: 10.1016/j.ultrasmedbio.2017.06.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 04/26/2017] [Accepted: 06/02/2017] [Indexed: 06/07/2023]
Abstract
Transabdominal ultrasound elasticity imaging could improve the assessment of rupture risk for abdominal aortic aneurysms by providing information on the mechanical properties and stress or strain states of vessel walls. We implemented a non-rigid image registration method to visualize the pressure-normalized strain within vascular tissues and adapted it to measure total strain over an entire cardiac cycle. We validated the algorithm's performance with both simulated ultrasound images with known principal strains and anatomically accurate heterogeneous polyvinyl alcohol cryogel vessel phantoms. Patient images of abdominal aortic aneurysm were also used to illustrate the clinical feasibility of our imaging algorithm and the potential value of pressure-normalized strain as a clinical metric. Our results indicated that pressure-normalized strain could be used to identify spatial variations in vessel tissue stiffness. The results of this investigation were sufficiently encouraging to warrant a clinical study measuring abdominal aortic pressure-normalized strain in a patient population with aneurysmal disease.
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Affiliation(s)
- Doran S Mix
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA; Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA.
| | - Ling Yang
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - Camille C Johnson
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
| | - Nathan Couper
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA; Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - Ben Zarras
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - Isaac Arabadjis
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
| | - Lauren E Trakimas
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA
| | - Michael C Stoner
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA
| | - Steven W Day
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
| | - Michael S Richards
- Division of Vascular Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York, USA; Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, New York, USA
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Conlisk N, Forsythe RO, Hollis L, Doyle BJ, McBride OMB, Robson JMJ, Wang C, Gray CD, Semple SIK, MacGillivray T, van Beek EJR, Newby DE, Hoskins PR. Exploring the Biological and Mechanical Properties of Abdominal Aortic Aneurysms Using USPIO MRI and Peak Tissue Stress: A Combined Clinical and Finite Element Study. J Cardiovasc Transl Res 2017; 10:489-498. [PMID: 28808955 PMCID: PMC5722953 DOI: 10.1007/s12265-017-9766-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 08/04/2017] [Indexed: 01/15/2023]
Abstract
Inflammation detected through the uptake of ultrasmall superparamagnetic particles of iron oxide (USPIO) on magnetic resonance imaging (MRI) and finite element (FE) modelling of tissue stress both hold potential in the assessment of abdominal aortic aneurysm (AAA) rupture risk. This study aimed to examine the spatial relationship between these two biomarkers. Patients (n = 50) > 40 years with AAA maximum diameters > = 40 mm underwent USPIO-enhanced MRI and computed tomography angiogram (CTA). USPIO uptake was compared with wall stress predictions from CTA-based patient-specific FE models of each aneurysm. Elevated stress was commonly observed in areas vulnerable to rupture (e.g. posterior wall and shoulder). Only 16% of aneurysms exhibited co-localisation of elevated stress and mural USPIO enhancement. Globally, no correlation was observed between stress and other measures of USPIO uptake (i.e. mean or peak). It is suggested that cellular inflammation and stress may represent different but complimentary aspects of AAA disease progression.
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Affiliation(s)
- Noel Conlisk
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK. .,School of Clinical Sciences, The University of Edinburgh, Edinburgh, UK. .,Institute for Bioengineering, The University of Edinburgh, Faraday Building, The King's Buildings, Mayfield Road, Edinburgh, EH9 3JL, UK.
| | - Rachael O Forsythe
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK.,School of Clinical Sciences, The University of Edinburgh, Edinburgh, UK.,Clinical Research Imaging Centre, The University of Edinburgh, Edinburgh, UK
| | - Lyam Hollis
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK
| | - Barry J Doyle
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK.,Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Perth, Australia.,School of Mechanical and Chemical Engineering, The University of Western Australia, Perth, Australia
| | - Olivia M B McBride
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK.,School of Clinical Sciences, The University of Edinburgh, Edinburgh, UK.,Clinical Research Imaging Centre, The University of Edinburgh, Edinburgh, UK
| | - Jennifer M J Robson
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK.,School of Clinical Sciences, The University of Edinburgh, Edinburgh, UK
| | - Chengjia Wang
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK.,Clinical Research Imaging Centre, The University of Edinburgh, Edinburgh, UK
| | - Calum D Gray
- Clinical Research Imaging Centre, The University of Edinburgh, Edinburgh, UK
| | - Scott I K Semple
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK.,Clinical Research Imaging Centre, The University of Edinburgh, Edinburgh, UK
| | - Tom MacGillivray
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK.,Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh, UK
| | - Edwin J R van Beek
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK.,Clinical Research Imaging Centre, The University of Edinburgh, Edinburgh, UK
| | - David E Newby
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK.,Clinical Research Imaging Centre, The University of Edinburgh, Edinburgh, UK
| | - Peter R Hoskins
- Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh, UK.,Institute for Bioengineering, The University of Edinburgh, Faraday Building, The King's Buildings, Mayfield Road, Edinburgh, EH9 3JL, UK
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Metaxa E, Kontopodis N, Vavourakis V, Tzirakis K, Ioannou CV, Papaharilaou Y. The influence of intraluminal thrombus on noninvasive abdominal aortic aneurysm wall distensibility measurement. Med Biol Eng Comput 2014; 53:299-308. [PMID: 25548097 DOI: 10.1007/s11517-014-1235-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 12/15/2014] [Indexed: 01/24/2023]
Abstract
Abdominal aortic aneurysm wall distensibility can be estimated by measuring pulse pressure and the corresponding sac volume change, which can be obtained by measuring wall displacement. This approach, however, may introduce error if the role of thrombus in assisting the wall in bearing the pulse pressure loading is neglected. Our aim was to introduce a methodology for evaluating and potentially correcting this error in estimating distensibility. Electrocardiogram-gated computed tomography images of eleven patients were obtained, and the volume change between diastole and systole was measured. Using finite element procedures, we determined the equivalent pulse pressure loading that should be applied to the wall of a model where thrombus was digitally removed, to yield the same sac volumetric increase caused by applying the luminal pulse pressure to the model with thrombus. The equivalent instead of the measured pulse pressure was used in the distensibility expression. For a relative volumetric thrombus deposition (V ILT) of 50 %, a 62 % distensibility underestimation resulted when thrombus role was neglected. A strong linear correlation was observed between distensibility underestimation and V ILT. To assess the potential value of noninvasive wall distensibility measurement in rupture risk stratification, the role of thrombus on wall loading should be further investigated.
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Affiliation(s)
- Eleni Metaxa
- Foundation for Research and Technology-Hellas, Institute of Applied and Computational Mathematics, Nikolaou Plastira 100, Vassilika Vouton, 70013, Heraklion, Crete, Greece
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WANG XIAOHONG, LI XIAOYANG. COMPUTER-BASED MECHANICAL ANALYSIS OF STENOSED ARTERY WITH THROMBOTIC PLAQUE: THE INFLUENCES OF IMPORTANT PHYSIOLOGICAL PARAMETERS. J MECH MED BIOL 2012. [DOI: 10.1142/s0219519412500698] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The thrombus is the inappropriate activation of hemostasis in vascular system. In this paper, biomechanical factors affecting the behaviors of artery with intraluminal thrombus were studies. Results indicated that heart rate and blood viscosity had strong impact on the compliance of the stenosis artery and flow pattern. The alteration in blood viscosity had stronger influence than cardiac cycle on the volume change of the fluid region surrounded by thrombus. von Mises stress measured at the thinnest region of the plaque had the largest time-averaged value. The alteration of these parameters could potentially lead to stress redistribution at intraluminal thrombus.
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Affiliation(s)
- XIAOHONG WANG
- Biomechanical Research Laboratory, Center of Engineering Mechanics, Beijing University of Technology, No.100 Pingleyuan, Chaoyang District, Beijing, P. R. China
| | - XIAOYANG LI
- Biomechanical Research Laboratory, Center of Engineering Mechanics, Beijing University of Technology, No.100 Pingleyuan, Chaoyang District, Beijing, P. R. China
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Humphrey JD, Holzapfel GA. Mechanics, mechanobiology, and modeling of human abdominal aorta and aneurysms. J Biomech 2012; 45:805-14. [PMID: 22189249 PMCID: PMC3294195 DOI: 10.1016/j.jbiomech.2011.11.021] [Citation(s) in RCA: 187] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2011] [Indexed: 12/25/2022]
Abstract
Biomechanical factors play fundamental roles in the natural history of abdominal aortic aneurysms (AAAs) and their responses to treatment. Advances during the past two decades have increased our understanding of the mechanics and biology of the human abdominal aorta and AAAs, yet there remains a pressing need for considerable new data and resulting patient-specific computational models that can better describe the current status of a lesion and better predict the evolution of lesion geometry, composition, and material properties and thereby improve interventional planning. In this paper, we briefly review data on the structure and function of the human abdominal aorta and aneurysmal wall, past models of the mechanics, and recent growth and remodeling models. We conclude by identifying open problems that we hope will motivate studies to improve our computational modeling and thus general understanding of AAAs.
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Affiliation(s)
- J D Humphrey
- Department of Biomedical Engineering and Vascular Biology and Therapeutics Program, Malone Engineering Center, Yale University, New Haven, CT 06520-8260, USA.
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Molony DS, Callanan A, Kavanagh EG, Walsh MT, McGloughlin TM. Fluid-structure interaction of a patient-specific abdominal aortic aneurysm treated with an endovascular stent-graft. Biomed Eng Online 2009; 8:24. [PMID: 19807909 PMCID: PMC2764714 DOI: 10.1186/1475-925x-8-24] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Accepted: 10/06/2009] [Indexed: 11/21/2022] Open
Abstract
Background Abdominal aortic aneurysms (AAA) are local dilatations of the infrarenal aorta. If left untreated they may rupture and lead to death. One form of treatment is the minimally invasive insertion of a stent-graft into the aneurysm. Despite this effective treatment aneurysms may occasionally continue to expand and this may eventually result in post-operative rupture of the aneurysm. Fluid-structure interaction (FSI) is a particularly useful tool for investigating aneurysm biomechanics as both the wall stresses and fluid forces can be examined. Methods Pre-op, Post-op and Follow-up models were reconstructed from CT scans of a single patient and FSI simulations were performed on each model. The FSI approach involved coupling Abaqus and Fluent via a third-party software - MpCCI. Aneurysm wall stress and compliance were investigated as well as the drag force acting on the stent-graft. Results Aneurysm wall stress was reduced from 0.38 MPa before surgery to a value of 0.03 MPa after insertion of the stent-graft. Higher stresses were seen in the aneurysm neck and iliac legs post-operatively. The compliance of the aneurysm was also reduced post-operatively. The peak Post-op axial drag force was found to be 4.85 N. This increased to 6.37 N in the Follow-up model. Conclusion In a patient-specific case peak aneurysm wall stress was reduced by 92%. Such a reduction in aneurysm wall stress may lead to shrinkage of the aneurysm over time. Hence, post-operative stress patterns may help in determining the likelihood of aneurysm shrinkage post EVAR. Post-operative remodelling of the aneurysm may lead to increased drag forces.
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Affiliation(s)
- David S Molony
- Centre for Applied Biomedical Engineering Research, Department of Mechanical and Aeronautical Engineering and Materials and Surface Science Institute, University of Limerick, Ireland.
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