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He S, Wei L, Wang G, Pugno NM, Chen Q, Li Z. In Silico Evaluation of In Vivo Degradation Kinetics of Poly(Lactic Acid) Vascular Stent Devices. J Funct Biomater 2024; 15:135. [PMID: 38786646 PMCID: PMC11122488 DOI: 10.3390/jfb15050135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/09/2024] [Accepted: 05/11/2024] [Indexed: 05/25/2024] Open
Abstract
Biodegradable vascular stents (BVS) are deemed as great potential alternatives for overcoming the inherent limitations of permanent metallic stents in the treatment of coronary artery diseases. The current study aimed to comprehensively compare the mechanical behaviors of four poly(lactic acid) (PLA) BVS designs with varying geometries via numerical methods and to clarify the optimal BVS selection. Four PLA BVS (i.e., Absorb, DESolve, Igaki-Tamai, and Fantom) were first constructed. A degradation model was refined by simply including the fatigue effect induced by pulsatile blood pressures, and an explicit solver was employed to simulate the crimping and degradation behaviors of the four PLA BVS. The degradation dynamics here were characterized by four indices. The results indicated that the stent designs affected crimping and degradation behaviors. Compared to the other three stents, the DESolve stent had the greatest radial stiffness in the crimping simulation and the best diameter maintenance ability despite its faster degradation; moreover, the stent was considered to perform better according to a pilot scoring system. The current work provides a theoretical method for studying and understanding the degradation dynamics of the PLA BVS, and it could be helpful for the design of next-generation BVS.
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Affiliation(s)
- Shicheng He
- Biomechanics Laboratory, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Lingling Wei
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230601, China
| | - Guixue Wang
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing 400030, China
| | - Nicola M. Pugno
- Laboratory for Bioinspired, Bionic, Nano, Meta Materials and Mechanics, University of Trento, Via Mesiano 77, 38123 Trento, Italy
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Qiang Chen
- Biomechanics Laboratory, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Zhiyong Li
- Biomechanics Laboratory, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
- School of Mechanical, Medical and Process Engineering, Queensland University of Technology, Brisbane, QLD 4001, Australia
- Faculty of Sports Science, Ningbo University, Ningbo 315211, China
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2
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Abaei AR, Shine CJ, Vaughan TJ, Ronan W. An integrated mechanical degradation model to explore the mechanical response of a bioresorbable polymeric scaffold. J Mech Behav Biomed Mater 2024; 152:106419. [PMID: 38325169 DOI: 10.1016/j.jmbbm.2024.106419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/17/2024] [Accepted: 01/23/2024] [Indexed: 02/09/2024]
Abstract
Simulation of bioresorbable medical devices is hindered by the limitations of current material models. Useful simulations require that both the short- and long-term response must be considered; existing models are not physically-based and provide limited insight to guide performance improvements. This study presents an integrated degradation framework which couples a physically-based degradation model, which predicts changes in both crystallinity (Xc) and molecular weight (Mn), with the results of a micromechanical model, which predicts the effective properties of the semicrystalline polymer. This degradation framework is used to simulate the deployment of a bioresorbable PLLA (Poly (L-lactide) stent into a mock vessel and the subsequent mechanical response during degradation under different diffusion boundary conditions representing neointimal growth. A workflow is established in a commercial finite element code that couples both the immediate and long-term responses. Clinically relevant lumen loss is reported and used to compare different responses and the effect of neo-intimal tissue regrowth post-implantation on degradation and on the mechanical response is assessed. In addition, the effects of possible changes in Xc, which could occur during processing and stent deployment, are explored.
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Affiliation(s)
- A R Abaei
- Biomechanics Research Centre (BMEC), Biomedical Engineering, School of Engineering, University of Galway, Ireland
| | - Connor J Shine
- Biomechanics Research Centre (BMEC), Biomedical Engineering, School of Engineering, University of Galway, Ireland
| | - T J Vaughan
- Biomechanics Research Centre (BMEC), Biomedical Engineering, School of Engineering, University of Galway, Ireland
| | - W Ronan
- Biomechanics Research Centre (BMEC), Biomedical Engineering, School of Engineering, University of Galway, Ireland.
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3
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Collins CP, Leng J, Fu R, Ding Y, Ameer G, Sun C. Investigation of 3D Printed Bioresorbable Vascular Scaffold Crimping Behavior. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.26.564253. [PMID: 37961598 PMCID: PMC10634898 DOI: 10.1101/2023.10.26.564253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
The rise in additive manufacturing (AM) offers myriad opportunities for 3D-printed polymeric vascular scaffolds, such as customization and on-the-spot manufacturing, in vivo biodegradation, incorporation of drugs to prevent restenosis, and visibility under X-ray. To maximize these benefits, informed scaffold design is critical. Polymeric bioresorbable vascular scaffolds (BVS) must undergo significant deformation prior to implantation in a diameter-reduction process known as crimping which enables minimally invasive surgery. Understanding the behavior of vascular scaffolds in this step provides twofold benefits: first, it ensures the BVS is able to accommodate stresses occurring during this process to prevent failure, and further, it provides information on the radial strength of the BVS, a key metric to understanding its post-implant performance in the artery. To capitalize on the fast manufacturing speed AM provides, a low time cost solution for understanding scaffold performance during this step is necessary. Through simulation of the BVS crimping process in ABAQUS using experimentally obtained bulk material properties, we have developed a qualitative analysis tool which is capable of accurately comparing relative performance trends of varying BVS designs during crimping in a fraction of the time of experimental testing, thereby assisting in the integration of informed design into the additive manufacturing process.
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Liu W, Huang J, He S, Du R, Shi W, Wang Y, Du D, Du Y, Liu Q, Wang Y, Wang G, Yin T. Senescent endothelial cells' response to the degradation of bioresorbable scaffold induces intimal dysfunction accelerating in-stent restenosis. Acta Biomater 2023; 166:266-277. [PMID: 37211308 DOI: 10.1016/j.actbio.2023.05.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 05/16/2023] [Accepted: 05/16/2023] [Indexed: 05/23/2023]
Abstract
Atherosclerotic cardiovascular disease is a typical age-related disease accompanied by stiffening arteries. We aimed to elucidate the influence of aged arteries on in-stent restenosis (ISR) after the implantation of bioresorbable scaffolds (BRS). Histology and optical coherence tomography showed increased lumen loss and ISR in the aged abdominal aorta of Sprague-Dawley rats, with apparent scaffold degradation and deformation, which induce lower wall shear stress (WSS). This was also the case at the distal end of BRS, where the scaffolds degraded faster, and significant lumen loss was followed by a lower WSS. In addition, early thrombosis, inflammation, and delayed re-endothelialization were presented in the aged arteries. Degradation of BRS causes more senescent cells in the aged vasculature, increasing endothelial cell dysfunction and the risk of ISR. Thus, profoundly understanding the mechanism between BRS and senescent cells may give a meaningful guide for the age-related scaffold design. STATEMENT OF SIGNIFICANCE: The degradation of bioresorbable scaffolds aggravates senescent endothelial cells and a much lower wall shear stress areas in the aged vasculature, lead to intimal dysfunction and increasing in-stent restenosis risk. Early thrombosis and inflammation, as well as delayed re-endothelialization, are presented in the aged vasculature after bioresorbable scaffolds implantation. Age stratification during the clinical evaluation and senolytics in the design of new bioresorbable scaffolds should be considered, especially for old patients.
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Affiliation(s)
- Wanling Liu
- Key Laboratory of Biorheological and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Modern Life Science Experiment Teaching Center, Bioengineering College of Chongqing University, Chongqing 400030, PR China
| | - Junyang Huang
- Key Laboratory of Biorheological and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Modern Life Science Experiment Teaching Center, Bioengineering College of Chongqing University, Chongqing 400030, PR China
| | - Shicheng He
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Ruolin Du
- Key Laboratory of Biorheological and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Modern Life Science Experiment Teaching Center, Bioengineering College of Chongqing University, Chongqing 400030, PR China
| | - Wen Shi
- Key Laboratory of Biorheological and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Modern Life Science Experiment Teaching Center, Bioengineering College of Chongqing University, Chongqing 400030, PR China
| | - Yang Wang
- Key Laboratory of Biorheological and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Modern Life Science Experiment Teaching Center, Bioengineering College of Chongqing University, Chongqing 400030, PR China
| | - Dingyuan Du
- Department of Traumatology, and Department of Cardiothoracic Surgery, Chongqing University Central Hospital, Chongqing Emergency Medical Center, Chongqing 400014, China
| | - Yan Du
- Ultrasonography Department, Chongqing University Central Hospital, Chongqing Emergency Medical Center, Chongqing 400014, China
| | - Qing Liu
- Beijing Advanced Medical Technologies Inc., Beijing 102609, China
| | - Yazhou Wang
- School of Medicine, Chongqing University, Chongqing 400044, PR China.
| | - Guixue Wang
- Key Laboratory of Biorheological and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Modern Life Science Experiment Teaching Center, Bioengineering College of Chongqing University, Chongqing 400030, PR China.
| | - Tieying Yin
- Key Laboratory of Biorheological and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Modern Life Science Experiment Teaching Center, Bioengineering College of Chongqing University, Chongqing 400030, PR China.
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5
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He R, Zhao L, Silberschmidt VV. Effect of balloon pre-dilation on performance of self-expandable nitinol stent in femoropopliteal artery. Biomech Model Mechanobiol 2023; 22:189-205. [PMID: 36282361 PMCID: PMC9957922 DOI: 10.1007/s10237-022-01641-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 09/19/2022] [Indexed: 11/24/2022]
Abstract
Balloon pre-dilation is usually performed before implantation of a nitinol stent in a femoropopliteal artery in a case of severe blockage or calcified plaque. However, its effect on performance of the nitinol stent in a diseased femoropopliteal artery has not been studied yet. This study compares the outcomes of stenting with pre-dilation and without it by modelling the entire processes of stent deployment. Fatigue deformation of the implanted stent is also modelled under diastolic-systolic blood pressure, repetitive bending, torsion, axial compression and their combination. Reduced level of stress in the stent occurs after stenting with pre-dilation, but causing the increased damage in the media layer, i.e. the middle layer of the arterial wall. Generally, pre-dilation increases the risk of nitinol stent's fatigue failure. Additionally, the development of in-stent restenosis is predicted based on the stenting-induced tissue damage in the media layer, and no severe mechanical irritation is induced to the media layer by pre-dilation, stent deployment or fatigue loading.
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Affiliation(s)
- Ran He
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Epinal Way, Loughborough, LE11 3TU, UK.
| | - Liguo Zhao
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Epinal Way, Loughborough, LE11 3TU UK ,College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016 People’s Republic of China
| | - Vadim V. Silberschmidt
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Epinal Way, Loughborough, LE11 3TU UK
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6
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In silico evaluation of additively manufactured 316L stainless steel stent in a patient-specific coronary artery. Med Eng Phys 2022; 109:103909. [DOI: 10.1016/j.medengphy.2022.103909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 10/04/2022] [Accepted: 10/13/2022] [Indexed: 11/11/2022]
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Fegan KL, Green NC, Britton MM, Iqbal AJ, Thomas-Seale LEJ. Design and Simulation of the Biomechanics of Multi-Layered Composite Poly(Vinyl Alcohol) Coronary Artery Grafts. Front Cardiovasc Med 2022; 9:883179. [PMID: 35833186 PMCID: PMC9272978 DOI: 10.3389/fcvm.2022.883179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 06/01/2022] [Indexed: 11/25/2022] Open
Abstract
Coronary artery disease is among the primary causes of death worldwide. While synthetic grafts allow replacement of diseased tissue, mismatched mechanical properties between graft and native tissue remains a major cause of graft failure. Multi-layered grafts could overcome these mechanical incompatibilities by mimicking the structural heterogeneity of the artery wall. However, the layer-specific biomechanics of synthetic grafts under physiological conditions and their impact on endothelial function is often overlooked and/or poorly understood. In this study, the transmural biomechanics of four synthetic graft designs were simulated under physiological pressure, relative to the coronary artery wall, using finite element analysis. Using poly(vinyl alcohol) (PVA)/gelatin cryogel as the representative biomaterial, the following conclusions are drawn: (I) the maximum circumferential stress occurs at the luminal surface of both the grafts and the artery; (II) circumferential stress varies discontinuously across the media and adventitia, and is influenced by the stiffness of the adventitia; (III) unlike native tissue, PVA/gelatin does not exhibit strain stiffening below diastolic pressure; and (IV) for both PVA/gelatin and native tissue, the magnitude of stress and strain distribution is heavily dependent on the constitutive models used to model material hyperelasticity. While these results build on the current literature surrounding PVA-based arterial grafts, the proposed method has exciting potential toward the wider design of multi-layer scaffolds. Such finite element analyses could help guide the future validation of multi-layered grafts for the treatment of coronary artery disease.
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Affiliation(s)
- Katie L. Fegan
- Physical Sciences for Health Centre for Doctoral Training, University of Birmingham, Birmingham, United Kingdom
- Department of Mechanical Engineering, University of Birmingham, Birmingham, United Kingdom
| | - Naomi C. Green
- Department of Mechanical Engineering, University of Birmingham, Birmingham, United Kingdom
| | - Melanie M. Britton
- School of Chemistry, College of Engineering and Physical Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Asif J. Iqbal
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, United Kingdom
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8
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Hoddy B, Ahmed N, Al-Lamee K, Bullett N, Curzen N, Bressloff NW. Investigating the Equivalent Plastic Strain in a Variable Ring Length and Strut Width Thin-Strut Bioresorbable Scaffold. Cardiovasc Eng Technol 2022; 13:899-914. [PMID: 35819580 PMCID: PMC9750924 DOI: 10.1007/s13239-022-00625-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 04/18/2022] [Indexed: 01/27/2023]
Abstract
PURPOSE The ArterioSorb[Formula: see text] bioresorbable scaffold (BRS) developed by Arterius Ltd is about to enter first in man clinical trials. Previous generations of BRS have been vulnerable to brittle fracture, when expanded via balloon inflation in-vivo, which can be extremely detrimental to patient outcome. Therefore, this study explores the effect of variable ring length and strut width (as facilitated by the ArterioSorb[Formula: see text] design) on fracture resistance via analysis of the distribution of equivalent plastic strain in the scaffold struts post expansion. Scaffold performance is also assessed with respect to side branch access, radial strength, final deployed diameter and percentage recoil. METHODS Finite element analysis was conducted of the crimping, expansion and radial crushing of five scaffold designs comprising different variations in ring length and strut width. The Abaqus/Explicit (DS SIMULIA) solution method was used for all simulations. Direct comparison between in-silico predictions and in-vitro measurements of the performance of the open cell variant of the ArterioSorb[Formula: see text] were made. Paths across the width of the crown apex and around the scaffold rings were defined along which the plastic strain distribution was analysed. RESULTS The in-silico results demonstrated good predictions of final shape for the baseline scaffold design. Percentage recoil and radial strength were predicted to be, respectively, 2.8 and 1.7 times higher than the experimentally measured values, predominantly due to the limitations of the anisotropic elasto-plastic material property model used for the scaffold. Average maximum values of equivalent plastic strain were up to 2.4 times higher in the wide strut designs relative to the narrow strut scaffolds. As well as the concomitant risk of strut fracture, the wide strut designs also exhibited twisting and splaying behaviour at the crowns located on the scaffold end rings. Not only are these phenomena detrimental to the radial strength and risk of strut fracture but they also increase the likelihood of damage to the vessel wall. However, the baseline scaffold design was observed to tolerate significant over expansion without inducing excessive plastic strains, a result which is particularly encouraging, due to post-dilatation being commonplace in clinical practice. CONCLUSION Therefore, the narrow strut designs investigated herein, are likely to offer optimal performance and potentially better patient outcomes. Further work should address the material modelling of next generation polymeric BRS to more accurately capture their mechanical behaviour. Observation of the in-vitro testing indicates that the ArterioSorb[Formula: see text] BRS can tolerate greater levels of over expansion than anticipated.
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Affiliation(s)
- Ben Hoddy
- grid.5491.90000 0004 1936 9297Computational Engineering and Design Research Group, University of Southampton, Southampton, UK
| | - Naveed Ahmed
- grid.498018.c0000 0004 0581 8370Arterius Ltd, Leeds, UK
| | | | - Nial Bullett
- grid.498018.c0000 0004 0581 8370Arterius Ltd, Leeds, UK
| | - Nick Curzen
- grid.430506.40000 0004 0465 4079Coronary Research Group, Southampton University Hospitals NHS Trust, Southampton, UK ,grid.5491.90000 0004 1936 9297Faculty of Medicine, University of Southampton, Southampton, UK
| | - Neil W. Bressloff
- grid.5491.90000 0004 1936 9297Computational Engineering and Design Research Group, University of Southampton, Southampton, UK
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He R, Zhao L, Silberschmidt VV, Feng J, Serracino-Inglott F. Personalised nitinol stent for focal plaques: Design and evaluation. J Biomech 2021; 130:110873. [PMID: 34883344 DOI: 10.1016/j.jbiomech.2021.110873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/01/2021] [Accepted: 11/16/2021] [Indexed: 10/19/2022]
Abstract
The purpose of this study is to develop personalised nitinol stents for arteries with one and two opposite focal plaques. Novel designs are evaluated through comparison with a commercial stent design, in terms of lumen gain and shape as well as stress levels in the media layer after stenting. METHODS Personalised stents are developed for arteries with one and two opposite focal plaques, based on medical imaging of patients and computer simulations. In silico analysis is then carried out for assessment of stent performance in the diseased arteries. RESULTS Personalised designs significantly increase the lumen gain, reduce the stresses in the media layer, and improve the lumen shape compared to the commercial nitinol stent. CONCLUSION The personalised designs show outstanding performance compared to the commercial stent. SIGNIFICANCE This pilot study proves that personalised nitinol stents are able to deliver desirable treatment outcomes.
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Affiliation(s)
- Ran He
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Epinal Way, Loughborough LE11 3TU, UK.
| | - Liguo Zhao
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Epinal Way, Loughborough LE11 3TU, UK
| | - Vadim V Silberschmidt
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Epinal Way, Loughborough LE11 3TU, UK
| | - Jiling Feng
- Department of Engineering, Manchester Metropolitan University, Manchester M15 6BH, UK
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10
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Tidwell K, Harriet S, Barot V, Bauer A, Vaughan MB, Hossan MR. Design and Analysis of a Biodegradable Polycaprolactone Flow Diverting Stent for Brain Aneurysms. Bioengineering (Basel) 2021; 8:bioengineering8110183. [PMID: 34821749 PMCID: PMC8614946 DOI: 10.3390/bioengineering8110183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/31/2021] [Accepted: 11/09/2021] [Indexed: 11/21/2022] Open
Abstract
The flow diverting stent (FDS) has become a promising endovascular device for the treatment of aneurysms. This research presents a novel biodegradable and non-braided Polycaprolactone (PCL) FDS. The PCL FDS was designed and developed using an in-house fabrication unit and coated on two ends with BaSO4 for angiographic visibility. The mechanical flexibility and quality of FDS surfaces were examined with the UniVert testing machine, scanning electron microscope (SEM), and 3D profilometer. Human umbilical vein endothelial cell (HUVEC) adhesion, proliferation, and cell morphology studies on PCL FDS were performed. The cytotoxicity and NO production by HUVECs with PCL FDS were also conducted. The longitudinal tensile, radial, and bending flexibility were found to be 1.20 ± 0.19 N/mm, 0.56 ± 0.11 N/mm, and 0.34 ± 0.03 N/mm, respectively. The FDS was returned to the original shape and diameter after repeated compression and bending without compromising mechanical integrity. Results also showed that the proliferation and adhesion of HUVECs on the FDS surface increased over time compared to control without FDS. Lactate dehydrogenase (LDH) release and NO production showed that PCL FDS were non-toxic and satisfactory. Cell morphology studies showed that HUVECs were elongated to cover the FD surface and developed an endothelial monolayer. This study is a step forward toward the development and clinical use of biodegradable flow diverting stents for endovascular treatment of the aneurysm.
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Affiliation(s)
- Kaitlyn Tidwell
- Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA; (K.T.); (S.H.); (V.B.)
| | - Seth Harriet
- Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA; (K.T.); (S.H.); (V.B.)
| | - Vishal Barot
- Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA; (K.T.); (S.H.); (V.B.)
| | - Andrew Bauer
- Department of Neurosurgery, University of Oklahoma-Health Science Center, Oklahoma City, OK 73104, USA;
| | - Melville B. Vaughan
- Department of Biology, University of Central Oklahoma, Edmond, OK 73034, USA;
- Center of Interdisciplinary Biomedical Education and Research, University of Central Oklahoma, Edmond, OK 73034, USA
| | - Mohammad R. Hossan
- Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA; (K.T.); (S.H.); (V.B.)
- Center of Interdisciplinary Biomedical Education and Research, University of Central Oklahoma, Edmond, OK 73034, USA
- Correspondence: ; Tel.: +1-405-975-5295
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11
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Fiuza C, Polak-Kraśna K, Antonini L, Petrini L, Carroll O, Ronan W, Vaughan TJ. An experimental investigation into the physical, thermal and mechanical degradation of a polymeric bioresorbable scaffold. J Mech Behav Biomed Mater 2021; 125:104955. [PMID: 34749206 DOI: 10.1016/j.jmbbm.2021.104955] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 10/22/2021] [Accepted: 11/01/2021] [Indexed: 12/01/2022]
Abstract
This study presents a comprehensive evaluation of the mechanical, micro-mechanical and physical properties of Reva Medical Fantom Encore Bioresorbable Scaffolds (BRS) subjected to a thermally-accelerated degradation protocol. The Fantom Encore BRS were immersed in phosphate buffered saline solution at 50 °C for 112 days with radial compression testing, nanoindentation, differential scanning calorimetry, gel permeation chromatography and mass loss characterisation performed at consecutive time points. In the initial stages of degradation (Days 0-21), the Fantom Encore BRS showed increases in radial strength and stiffness, despite a substantial reduction in in molecular weight, with a slight increase in the melt temperature also observed. In the second phase (Days 35-54), the radial strength of the BRS samples were maintained despite a continued loss in molecular weight. However, during this phase, the ductility of the stent showed a reduction, with stent fracture occurring earlier in the crimp process and with lower amounts of plastic deformation evident under visual examination post-fracture. In the final phase (Days 63-112), the load-bearing capacity of the Fantom Encore BRS showed continued reduction, with decreases in radial stiffness and strength, and drastic reduction in the work-to-fracture of the devices. Throughout each phase, there was a steady increase in the relative crystallinity, with limited mass loss until day 112 and only minor changes in glass transition and melt temperatures. Limited changes were observed in nano-mechanical properties, with measured local elastic moduli and hardness values remaining largely similar throughout degradation. Given that the thermally-accelerated in vitro conditions represented a four-fold acceleration of physiological conditions, these results suggest that the BRS scaffolds could exhibit substantially brittle behaviour after ∼ one year of implantation.
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Affiliation(s)
- Constantino Fiuza
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland
| | - Katarzyna Polak-Kraśna
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland
| | - Luca Antonini
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milano, Italy
| | - Lorenza Petrini
- Department of Civil and Environmental Engineering, Politecnico di Milano, Milano, Italy
| | - Oliver Carroll
- CÚRAM, Centre for Research in Medical Devices, Biomedical Sciences, National University of Ireland Galway, Galway, Ireland
| | - William Ronan
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland
| | - Ted J Vaughan
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland.
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12
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Antonini L, Poletti G, Mandelli L, Dubini G, Pennati G, Petrini L. Comprehensive computational analysis of the crimping procedure of PLLA BVS: effects of material viscous-plastic and temperature dependent behavior. J Mech Behav Biomed Mater 2021; 123:104713. [PMID: 34365099 DOI: 10.1016/j.jmbbm.2021.104713] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 07/06/2021] [Accepted: 07/08/2021] [Indexed: 10/20/2022]
Abstract
Recently, researchers focused their attention on the use of polymeric bioresorbable vascular scaffolds (BVSs) as alternative to permanent metallic drug-eluting stents (DESs) for the treatment of atherosclerotic coronary arteries. Due to the different mechanical properties, polymeric stents, if compared to DESs, are characterized by larger strut size and specific design. It implies that during the crimping phase, BVSs undergo higher deformation and the packing of the struts, making this process potentially critical for the onset of damage. In this work, a computational study on the crimping procedure of a PLLA stent, inspired by the Absorb GT1 (Abbott Vascular) design, is performed, with the aim of evaluating how different strategies (loading steps, velocities and temperatures) can influence the results in terms of damage risk and final crimped diameter. For these simulations, an elastic-viscous-plastic model was adopted, based on experimental results, obtained from tensile testing of PLLA specimens loaded according to ad hoc experimental protocols. Furthermore, the results of these simulations were compared with those obtained by neglecting strain rate and temperature dependence in the material model (as often done in the literature), showing how this lead to significant differences in the prediction of the crimped diameter and internal stress state.
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Affiliation(s)
- Luca Antonini
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Gianluca Poletti
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Lorenzo Mandelli
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Gabriele Dubini
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Giancarlo Pennati
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Lorenza Petrini
- Department of Civil and Environmental Engineering, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
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Antonini L, Berti F, Isella B, Hossain D, Mandelli L, Pennati G, Petrini L. From the real device to the digital twin: A coupled experimental-numerical strategy to investigate a novel bioresorbable vascular scaffold. PLoS One 2021; 16:e0252788. [PMID: 34086820 PMCID: PMC8177663 DOI: 10.1371/journal.pone.0252788] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 05/21/2021] [Indexed: 11/26/2022] Open
Abstract
The purpose of this work is to propose a workflow that couples experimental and computational activities aimed at developing a credible digital twin of a commercial coronary bioresorbable vascular scaffold when direct access to data about material mechanical properties is not possible. Such a situation is be faced when the manufacturer is not involved in the study, thus directly investigating the actual device is the only source of information available. The object of the work is the Fantom® Encore polymeric stent (REVA Medical) made of Tyrocore™. Four devices were purchased and used in mechanical tests that are easily reproducible in any mechanical laboratory, i.e. free expansion and uniaxial tension testing, the latter performed with protocols that emphasized the rate-dependent properties of the polymer. Given the complexity of the mechanical behaviour observed experimentally, it was chosen to use the Parallel Rehological Framework material model, already used in the literature to describe the behaviour of other polymers, such as PLLA. Calibration of the material model was based on simulations that replicate the tensile test performed on the device. Given the high number of material parameters, a plan of simulations was done to find the most suitable set, varying each parameter value in a feasible range and considering a single repetitive unit of the stent, neglecting residual stresses generated by crimping and expansion. This strategy resulted in a significant reduction of computational cost. The performance of the set of parameters thus identified was finally evaluated considering the whole delivery system, by comparing the experimental results with the data collected simulating free expansion and uniaxial tension testing. Moreover, radial force testing was numerically performed and compared with literature data. The obtained results demonstrated the effectiveness of the digital twin development pipeline, a path applicable to any commercial device whose geometric structure is based on repetitive units.
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Affiliation(s)
- Luca Antonini
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milano, Italy
| | - Francesca Berti
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milano, Italy
| | - Benedetta Isella
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milano, Italy
| | - Dipok Hossain
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milano, Italy
| | - Lorenzo Mandelli
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milano, Italy
| | - Giancarlo Pennati
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Milano, Italy
| | - Lorenza Petrini
- Department of Civil and Environmental Engineering, Politecnico di Milano, Milano, Italy
- * E-mail:
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14
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Polak-Kraśna K, Abaei AR, Shirazi RN, Parle E, Carroll O, Ronan W, Vaughan TJ. Physical and mechanical degradation behaviour of semi-crystalline PLLA for bioresorbable stent applications. J Mech Behav Biomed Mater 2021; 118:104409. [PMID: 33836301 DOI: 10.1016/j.jmbbm.2021.104409] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 01/07/2021] [Accepted: 02/13/2021] [Indexed: 11/19/2022]
Abstract
This study presents a systematic evaluation of the physical, thermal and mechanical performance of medical-grade semi-crystalline PLLA undergoing thermally-accelerated degradation. Samples were immersed in phosphate-buffered saline solution at 50 °C for 112 days and mass loss, molecular weight, thermal properties, degree of crystallinity, FTIR and Raman spectra, tensile elastic modulus, yield stress and failure stress/strain were evaluated at consecutive time points. Samples showed a consistent reduction in molecular weight and melting temperature, a consistent increase in percent crystallinity and limited changes in glass transition temperature and mass loss. At day 49, a drastic reduction in tensile failure strain was observed, despite the fact that elastic modulus, yield and tensile strength of samples were maintained. Brittleness increase was followed by rapid increase in degradation rate. Beyond day 70, samples became too brittle to test indicating substantial deterioration of their load-bearing capacity. This study also presents a computational micromechanics framework that demonstrates that the elastic modulus of a semi-crystalline polymer undergoing degradation can be maintained, despite a reducing molecular weight through compensatory increases in percent crystallinity. This study presents novel insight into the relationship between physical properties and mechanical performance of medical-grade PLLA during degradation and could have important implications for design and development of bioresorbable stents for vascular applications.
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Affiliation(s)
- Katarzyna Polak-Kraśna
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland.
| | - Ali Reza Abaei
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland
| | - Reyhaneh Neghabat Shirazi
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland
| | - Eoin Parle
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland
| | - Oliver Carroll
- CÚRAM, Centre for Research in Medical Devices, Biomedical Sciences, National University of Ireland Galway, Galway, Ireland
| | - William Ronan
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland
| | - Ted J Vaughan
- Biomechanics Research Centre (BioMEC), Biomedical Engineering, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland.
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A computational study of fatigue resistance of nitinol stents subjected to walk-induced femoropopliteal artery motion. J Biomech 2021; 118:110295. [PMID: 33578053 DOI: 10.1016/j.jbiomech.2021.110295] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 01/20/2021] [Accepted: 01/23/2021] [Indexed: 11/21/2022]
Abstract
Fatigue resistance of nitinol stents implanted in femoropopliteal arteries is a critical issue because of their harsh biomechanical environment. Limb flexions due to daily walk expose the femoropopliteal arteries and, subsequently, the implanted stents to large cyclic deformations, which may lead to fatigue failure of the smart self-expandable stents. For the first time, this paper utilised the up-to-date measurements of walk-induced motion of a human femoropopliteal artery to investigate the fatigue behaviour of nitinol stent after implantation. The study was carried out by modelling the processes of angioplasty, stent crimping, self-expansion and deformation under diastolic-systolic blood pressure, repetitive bending, torsion and axial compression as well as their combination. The highest risk of fatigue failure of the nitinol stent occurs under a combined loading condition, with the bending contributing the most, followed by compression and torsion. The pulsatile blood pressure alone hardly causes any fatigue failure of the stent. The work is significant for understanding and improving the fatigue performance of nitinol stents through innovative design and procedural optimisation.
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16
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Lin S, Dong P, Zhou C, Dallan LAP, Zimin VN, Pereira GTR, Lee J, Gharaibeh Y, Wilson DL, Bezerra HG, Gu L. Degradation modeling of poly-l-lactide acid (PLLA) bioresorbable vascular scaffold within a coronary artery. NANOTECHNOLOGY REVIEWS 2020; 9:1217-1226. [PMID: 34012762 PMCID: PMC8130847 DOI: 10.1515/ntrev-2020-0093] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
In this work, a strain-based degradation model was implemented and validated to better understand the dynamic interactions between the bioresorbable vascular scaffold (BVS) and the artery during the degradation process. Integrating the strain-modulated degradation equation into commercial finite element codes allows a better control and visualization of local mechanical parameters. Both strut thinning and discontinuity of the stent struts within an artery were captured and visualized. The predicted results in terms of mass loss and fracture locations were validated by the documented experimental observations. In addition, results suggested that the heterogeneous degradation of the stent depends on its strain distribution following deployment. Degradation is faster at the locations with higher strains and resulted in the strut thinning and discontinuity, which contributes to the continuous mass loss, and the reduced contact force between the BVS and artery. A nonlinear relationship between the maximum principal strain of the stent and the fracture time was obtained, which could be transformed to predict the degradation process of the BVS in different mechanical environments. The developed computational model provided more insights into the degradation process, which could complement the discrete experimental data for improving the design and clinical management of the BVS.
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Affiliation(s)
- Shengmao Lin
- School of Civil Engineering and Architecture, Xiamen University of Technology, Xiamen, Fujian, 361024, China
| | - Pengfei Dong
- Department of Biomedical and Chemical Engineering, Florida Institute of Technology, Melbourne, FL 32901, United States of America
| | - Changchun Zhou
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, 610064, China
| | - Luis Augusto P Dallan
- Cardiovascular Imaging Core Laboratory, Harrington Heart & Vascular Institute, University Hospitals Cleveland Medical Center, Cleveland, OH 44106, United States of America
| | - Vladislav N Zimin
- Cardiovascular Imaging Core Laboratory, Harrington Heart & Vascular Institute, University Hospitals Cleveland Medical Center, Cleveland, OH 44106, United States of America
| | - Gabriel T R Pereira
- Cardiovascular Imaging Core Laboratory, Harrington Heart & Vascular Institute, University Hospitals Cleveland Medical Center, Cleveland, OH 44106, United States of America
| | - Juhwan Lee
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America
| | - Yazan Gharaibeh
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America
| | - David L Wilson
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America
| | - Hiram G Bezerra
- Interventional Cardiology Center, Heart and Vascular Institute, University of South Florida, Tampa, FL 33606, United States of America
| | - Linxia Gu
- Department of Biomedical and Chemical Engineering, Florida Institute of Technology, Melbourne, FL 32901, United States of America
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17
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Multimodal Loading Environment Predicts Bioresorbable Vascular Scaffolds' Durability. Ann Biomed Eng 2020; 49:1298-1307. [PMID: 33123828 DOI: 10.1007/s10439-020-02673-z] [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] [Received: 06/05/2020] [Accepted: 10/21/2020] [Indexed: 10/23/2022]
Abstract
Bioresorbable vascular scaffolds were considered the fourth generation of endovascular implants deemed to revolutionize cardiovascular interventions. Yet, unexpected high risk of scaffold thrombosis and post-procedural myocardial infractions quenched the early enthusiasm and highlighted the gap between benchtop predictions and clinical observations. To better understand scaffold behavior in the mechanical environment of vessels, animal, and benchtop tests with multimodal loading environment were conducted using industrial standard scaffolds. Finite element analysis was also performed to study the relationship among structural failure, scaffold design, and load types. We identified that applying the combination of bending, axial compression, and torsion better reflects incidence observed in-vivo, far more than tranditional single mode loads. Predication of fracture locations is also more accurate when at least bending and axial compression are applied during benchtop tests (>60% fractures at connected peak). These structural failures may be initiated by implantation-induced microstructural damages and worsened by cyclic loads from the beating heart. Ignoring the multi-modal loading environment in benchtop fatigue tests and computational platforms can lead to undetected potential design defects, calling for redefining consensus evaluation strategies for scaffold performance. With the robust evaluation strategy presented herein, which exploits the results of in-vivo, in-vitro and in-silico investigations, we may be able to compare alternative designs of prototypes at the early stages of device development and optimize the performance of endovascular implants according to patients-specific vessel dynamics and lesion configurations in the future.
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Wu YL, D’Amato AR, Yan AM, Wang RQ, Ding X, Wang Y. Three-Dimensional Printing of Poly(glycerol sebacate) Acrylate Scaffolds via Digital Light Processing. ACS APPLIED BIO MATERIALS 2020; 3:7575-7588. [DOI: 10.1021/acsabm.0c00804] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Yen-Lin Wu
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853-0001, United States
| | - Anthony R. D’Amato
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853-0001, United States
| | - Alice M. Yan
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14853-0001, United States
| | - Richard Q. Wang
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14853-0001, United States
| | - Xiaochu Ding
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853-0001, United States
| | - Yadong Wang
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853-0001, United States
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He R, Zhao L, Silberschmidt V, Liu Y, Vogt F. Patient-specific modelling of stent overlap: Lumen gain, tissue damage and in-stent restenosis. J Mech Behav Biomed Mater 2020; 109:103836. [DOI: 10.1016/j.jmbbm.2020.103836] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 03/09/2020] [Accepted: 04/26/2020] [Indexed: 10/24/2022]
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Mechanistic evaluation of long-term in-stent restenosis based on models of tissue damage and growth. Biomech Model Mechanobiol 2020; 19:1425-1446. [PMID: 31912322 PMCID: PMC7502446 DOI: 10.1007/s10237-019-01279-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 12/17/2019] [Indexed: 02/06/2023]
Abstract
Development and application of advanced mechanical models of soft tissues and their growth represent one of the main directions in modern mechanics of solids. Such models are increasingly used to deal with complex biomedical problems. Prediction of in-stent restenosis for patients treated with coronary stents remains a highly challenging task. Using a finite element method, this paper presents a mechanistic approach to evaluate the development of in-stent restenosis in an artery following stent implantation. Hyperelastic models with damage, verified with experimental results, are used to describe the level of tissue damage in arterial layers and plaque caused by such intervention. A tissue-growth model, associated with vessel damage, is adopted to describe the growth behaviour of a media layer after stent implantation. Narrowing of lumen diameter with time is used to quantify the development of in-stent restenosis in the vessel after stenting. It is demonstrated that stent designs and materials strongly affect the stenting-induced damage in the media layer and the subsequent development of in-stent restenosis. The larger the artery expansion achieved during balloon inflation, the higher the damage introduced to the media layer, leading to an increased level of in-stent restenosis. In addition, the development of in-stent restenosis is directly correlated with the artery expansion during the stent deployment. The correlation is further used to predict the effect of a complex clinical procedure, such as stent overlapping, on the level of in-stent restenosis developed after percutaneous coronary intervention.
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Finite element evaluation of artery damage in deployment of polymeric stent with pre- and post-dilation. Biomech Model Mechanobiol 2019; 19:47-60. [PMID: 31317295 PMCID: PMC7005093 DOI: 10.1007/s10237-019-01194-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 06/21/2019] [Indexed: 12/02/2022]
Abstract
Using finite element method, this paper evaluates damage in an arterial wall and plaque caused by percutaneous coronary intervention. Hyperelastic damage models, calibrated with experimental results, are used to describe stress–stretch responses of arterial layers and plaque; these models are capable to simulate softening behaviour of the tissue due to damage. Abaqus CAE is employed to create the finite element models for the artery wall (with media and adventitia layers), a symmetric uniform plaque, a bioresorbable polymeric stent and a tri-folded expansion balloon. The effect of percutaneous coronary intervention on vessel damage is investigated by simulating the processes of vessel pre-dilation, stent deployment and post-stenting dilation. Energy dissipation density is used to assess the extent of damage in the tissue. Softening of the plaque and the artery, due to the pre-dilation-induced damage, can facilitate the subsequent stent deployment process. The plaque and the artery experienced heterogeneous damage behaviour after the stent deployment, caused by non-uniform deformation. The post-stenting dilation was effective to achieve a full expansion of the stent, but caused additional damage to the artery. The continuous and discontinuous damage models yielded similar results in the percutaneous coronary intervention simulations, while the incorporation of plaque rupture affected the simulated outcomes of stent deployment. The computational evaluation of the artery damage can be potentially used to assess the risk of in-stent restenosis after percutaneous coronary intervention.
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Gao Y, Wang L, Gu X, Chu Z, Guo M, Fan Y. A quantitative study on magnesium alloy stent biodegradation. J Biomech 2018; 74:98-105. [DOI: 10.1016/j.jbiomech.2018.04.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 03/14/2018] [Accepted: 04/14/2018] [Indexed: 11/26/2022]
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