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Lee W, Cho SW, Allahwala UK, Bhindi R. Numerical study to identify the effect of fluid presence on the mechanical behavior of the stents during coronary stent expansion. Comput Methods Biomech Biomed Engin 2020; 23:744-754. [PMID: 32427003 DOI: 10.1080/10255842.2020.1763967] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
In this study, structural analysis and one-way fluid-structure interaction (FSI) analysis were performed to identify the effect of fluid presence on the mechanical behavior of the stents during stent expansion. An idealized vessel model with stenosis was used for simulation, and stents made of metal and polymer were assumed, respectively. The bilinear model was applied to the stents, and the Mooney-Rivlin model was applied to the arterial wall and plaque. The blood used in the FSI analysis was assumed to be a non-Newtonian fluid. As a result of all numerical simulations, the von Mises stress, the first principal stress and the displacement were calculated as the mechanical behaviors. Through the comparison of the results of the structural analysis with those of the one-way FSI analysis, our results indicated the fluid had no significant influence on the expansion of the metal stent. However, it was found that the expansion of the polymer stent affected by the presence of fluid. These findings meant the one-way FSI technique was suggested to achieve an accurate analysis when targeting a polymer stent for numerical simulation.
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Affiliation(s)
- Wookjin Lee
- Department of Cardiology, Kolling Institute of Medical Research, Northern Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Seong Wook Cho
- School of Mechanical Engineering, Chung-Ang University, Seoul, South Korea
| | - Usaid K Allahwala
- Department of Cardiology, Royal North Shore Hospital, University of Sydney, Sydney, NSW, Australia
| | - Ravinay Bhindi
- Department of Cardiology, Royal North Shore Hospital, University of Sydney, Sydney, NSW, Australia
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The processing of Mg alloy micro-tubes for biodegradable vascular stents. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2014; 48:400-7. [PMID: 25579940 DOI: 10.1016/j.msec.2014.12.024] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Revised: 11/21/2014] [Accepted: 12/05/2014] [Indexed: 11/23/2022]
Abstract
In this study, through a combination of hot extrusion, cold rolling and drawing, three Mg alloys, Mg-Nd-Zn-Zr (abbr. JDBM), AZ31 and WE43, were successfully fabricated into the high-quality micro-tubes with 3.00mm outer diameter and 180μm thickness for biodegradable stents. This processing method overcame the shortcoming of the poor workability of Mg alloys and could be applied to fabricate sufficiently long tubes with low dimensional errors within 2.8%. Microstructure observation demonstrated that the as-annealed JDBM, AZ31 and WE43 micro-tubes had more uniformly distributed grains with an average size of 10.9μm, 12.9μm and 15.0μm, respectively. Tensile mechanical test results showed that the as-annealed JDBM, AZ31 and WE43 micro-tubes respectively exhibited the yield strength of 123MPa, 172MPa and 113MPa, and significantly different breaking elongation of 26%, 16% and 10%. The following SEM observation showed microvoid coalescence, quasi-cleavage and cleavage fracture, respectively. In addition, EBSD analyses revealed that the as-annealed AZ31 tubes had a strong texture component 21¯1¯0 with a low Schmid factor for basal slip, while JDBM and WE43 tubes respectively exhibited weak textures 101¯0 and 101¯0+202¯1 with a similarly high Schmid factor for basal slip.
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Grogan J, Leen S, McHugh P. Influence of statistical size effects on the plastic deformation of coronary stents. J Mech Behav Biomed Mater 2013; 20:61-76. [DOI: 10.1016/j.jmbbm.2012.12.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 12/13/2012] [Accepted: 12/17/2012] [Indexed: 10/27/2022]
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Chen D, Müller-Eschner M, Rengier F, Kotelis D, Böckler D, Ventikos Y, Xu Y, Zeng Y, Peng Y, von Tengg-Kobligk H. A Preliminary Study of Fast Virtual Stent-Graft Deployment: Application to Stanford Type B Aortic Dissection. INT J ADV ROBOT SYST 2013. [DOI: 10.5772/55269] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Aortic dissection is the result of blood intruding into the layers of the aortic wall creating a duplicate channel along the aortic course. This considerably changes aortic morphology and thereby alters blood flow, inducing severe pathological conditions. Endovascular stent-graft placement has become an accepted treatment option for complicated Stanford type B aortic dissection. Stent-graft deployment aims to cover the primary entry, preventing most of the inflow to the false lumen, thereby promoting false lumen thrombosis and true lumen expansion. In recent years the application of this treatment has increased continuously. However, a fast and reasonable prediction for the released stent-graft and the resulting aortic remodelling prior to intervention is still lacking. In this paper, we propose a preliminary study on the fast virtual stent-graft deployment algorithm based on contact mechanics, spring analogy and deformable meshes. By virtually releasing a stent-graft in a patient-specific model of an aortic dissection type Stanford B, we simulate the interaction between the expanding stent-graft and the vessel wall (with low computational cost), and estimate the post-interventional configuration of the true lumen. This preliminary study can be finished within minutes and the results present good consistency with the post-interventional computed tomography angiography. It therefore confirms the feasibility and rationality of this algorithm, encouraging further research on this topic, which may provide more accurate results and could assist in medical decision-making.
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Affiliation(s)
- Duanduan Chen
- School of Life Science, Beijing Institute of Technology, China
| | - Matthias Müller-Eschner
- Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Germany
| | - Fabian Rengier
- Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Germany
| | - Drosos Kotelis
- Department of Vascular Surgery, University Hospital Heidelberg, Germany
| | - Dittmar Böckler
- Department of Vascular Surgery, University Hospital Heidelberg, Germany
| | - Yiannis Ventikos
- Department of Engineering Science & Institute of Biomedical Engineering, University of Oxford, UK
| | - Yong Xu
- General Hospital of Chinese PLA, China
| | - Yanjun Zeng
- Biomechanics and Medical Information Institute, Beijing University of Technology, China
| | - Yuhua Peng
- School of Life Science, Beijing Institute of Technology, China
| | - Hendrik von Tengg-Kobligk
- Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Germany
- Radiology, German Cancer Research Center (dkfz), Heidelberg, Germany
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Fatigue life assessment of cardiovascular balloon-expandable stents: A two-scale plasticity–damage model approach. J Mech Behav Biomed Mater 2012; 15:78-92. [DOI: 10.1016/j.jmbbm.2012.06.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 06/19/2012] [Indexed: 11/17/2022]
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Diehm N, Sin S, Hoppe H, Baumgartner I, Büchler P. Computational Biomechanics to Simulate the Femoropopliteal Intersection During Knee Flexion: A Preliminary Study. J Endovasc Ther 2011; 18:388-96. [DOI: 10.1583/10-3337.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Martin D, Boyle FJ. Computational structural modelling of coronary stent deployment: a review. Comput Methods Biomech Biomed Engin 2011; 14:331-48. [DOI: 10.1080/10255841003766845] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Hale P, Turgeon S, Horny P, Lewis F, Brack N, Van Riessen G, Pigram P, Mantovani D. X-ray photoelectron emission microscopy and time-of-flight secondary ion mass spectrometry analysis of ultrathin fluoropolymer coatings for stent applications. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:7897-7905. [PMID: 18616223 DOI: 10.1021/la8002788] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Fluoropolymer plasma coatings have been investigated for application as stent coatings due to their chemical stability, conformability, and hydrophobic properties. The challenge resides in the capacity for these coatings to remain adherent, stable, and cohesive after the in vivo stent expansion, which can generate local plastic deformation of up to 25%. Plasma-coated samples have been prepared by a multistep process on 316L stainless steel substrates, and some coated samples were plastically deformed to mimic a stent expansion. Analyses were then performed by X-ray photoelectron spectroscopy (XPS), X-ray photoelectron emission microscopy (X-PEEM), and time-of-flight secondary ion mass spectrometry (TOF-SIMS) to determine the chemical and physical effects of such a deformation on both the coating and the interfacial region. While XPS analyses always showed a continuous coating with no significant effect of the deformation, TOF-SIMS and near-edge X-ray absorption fine structure (derived from X-PEEM) data indicated the presence of a certain density of porosity and pinholes in all coatings as well as sparse fissures and molecular fragmentation in the deformed ones. The smallness of the area fraction affected by the defects and the subtlety of the chemical changes could only be evidenced through the higher chemical sensitivity of these latter techniques.
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Affiliation(s)
- Penelope Hale
- Laboratory for Biomaterials and Bioengineering, Department of Materials Engineering & University Hospital Research Center, Laval University, Quebec City, Quebec G1K 7P4, Canada
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Harewood FJ, McHugh PE. Modeling of Size Dependent Failure in Cardiovascular Stent Struts under Tension and Bending. Ann Biomed Eng 2007; 35:1539-53. [PMID: 17503185 DOI: 10.1007/s10439-007-9326-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Accepted: 05/02/2007] [Indexed: 11/25/2022]
Abstract
Cardiovascular stents are cylindrical mesh-like metallic structures that are used to treat atherosclerosis. The thickness of stent struts are typically in the range of 50-150 microm. At this microscopic size scale, the tensile failure strain has been shown to be size dependent. Micromechanically representative computational models have captured this size effect in tension. In this paper polycrystalline models incorporating material fracture are used to investigate size effects for realistic stent strut geometries and loading modes. The specific loading a stent undergoes during deployment is uniquely captured and the implications for stent design are considered. Fracture analysis is also performed, identifying trends in terms of strut thickness and loading type. The results show, in addition to the size effect in tension, further size effects in different loading conditions. The results of the loading analyses are combined to produce a tension and bending failure graph. This design safety diagram is presented as a tool to predict failure of stent struts. This study is particularly significant given the current interest in producing smaller stents.
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Affiliation(s)
- F J Harewood
- Department of Mechanical and Biomedical Engineering, National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Ireland
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Murphy BP, Cuddy H, Harewood FJ, Connolley T, McHugh PE. The influence of grain size on the ductility of micro-scale stainless steel stent struts. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2006; 17:1-6. [PMID: 16389466 DOI: 10.1007/s10856-006-6323-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Accepted: 05/24/2005] [Indexed: 05/06/2023]
Abstract
Vascular stents are used to restore blood flow in stenotic arteries, and at present the implantation of a stent is the preferred revascularisation method for treating coronary artery disease, as the introduction of drug eluting stents (DESs) has lead to a significant improvement in the clinical outcome of coronary stenting. However the mechanical limits of stents are being tested when they are deployed in severe cases. In this study we aimed to show (by a combination of experimental tests and crystal plasticity finite element models) that the ductility of stainless steel stent struts can be increased by optimising the grain structure within micro-scale stainless steel stent struts. The results of the study show that within the specimen size range 55 to 190 microm ductility was not dependent on the size of the stent strut when the grain size maximised. For values of the ratio of cross sectional area to characteristic grain length less than 1,000, ductility was at a minimum irrespective of specimen size. However, when the ratio of cross sectional area to characteristic grain length becomes greater than 1,000 an improvement in ductility occurs, reaching a plateau when the ratio approaches a value characteristic of bulk material properties. In conclusion the ductility of micro-scale stainless steel stent struts is sensitive to microstructure and can be improved by reducing the grain size.
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Affiliation(s)
- B P Murphy
- National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Ireland.
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Mackerle J. Finite element modelling and simulations in cardiovascular mechanics and cardiology: A bibliography 1993–2004. Comput Methods Biomech Biomed Engin 2005; 8:59-81. [PMID: 16154871 DOI: 10.1080/10255840500141486] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The paper gives a bibliographical review of the finite element modelling and simulations in cardiovascular mechanics and cardiology from the theoretical as well as practical points of views. The bibliography lists references to papers, conference proceedings and theses/dissertations that were published between 1993 and 2004. At the end of this paper, more than 890 references are given dealing with subjects as: Cardiovascular soft tissue modelling; material properties; mechanisms of cardiovascular components; blood flow; artificial components; cardiac diseases examination; surgery; and other topics.
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Affiliation(s)
- Jaroslav Mackerle
- Department of Mechanical Engineering, Linköping Institute of Technology, Sweden.
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