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Yu Y, Xiong Y, Li T, Zhou J, Yan W, Xiong Y, Chen Y, Fu P. Risk factors for in-stent restenosis in maintenance hemodialysis patients with central venous occlusive disease and biomechanical assessment of stents. J Vasc Access 2024; 25:943-952. [PMID: 36540050 DOI: 10.1177/11297298221139640] [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] [Indexed: 02/17/2024] Open
Abstract
OBJECTIVES To investigate the risk factors and biomechanical mechanisms of in-stent restenosis (ISR) in central venous occlusive disease (CVOD). PATIENTS AND METHODS This retrospective study consecutively included 77 maintenance hemodialysis (MHD) patients with CVOD who received the first percutaneous transluminal angioplasty with stenting (PTS) due to symptomatic CVOD in a tertiary hospital. The mean age was 59.7 ± 14.0 years, and 51.9% of patients were male. The clinical characteristics, occurrence of ISR and patency rates were recorded. Finite element method was applied to assess the biomechanical properties of stents. RESULTS Among 77 patients with a mean CVS score of 8.0 ± 2.8, 20.8%, 62.3%, and 16.9% of patients had the main vein of CVOD in the subclavian vein, brachiocephalic vein, and superior vena cava, respectively. A total of 72 (93.5%) patients received successful PTS treatment, for which the stents implanted were mainly Fluency covered stent (48.6%) and SMART bare stent (31.9%). During 15 (10-24)-months of follow-up, ISR occurred in 36.1% of the 72 patients. The primary and assisted primary patency rates at 6, 12, and 18 months were 78%, 56%, 42% and 95%, 90%, 87%, respectively. A prolonged dialysis vintage was an independent risk factor for ISR, yet the stent type or the main vein location was not correlated with ISR. Among three laser-engraving stents, the SMART stent was the best in terms of flexibility, stress, and strain on stents but worst in stress or strain on vessels. The Luminexx stent was the best in radial force and worst in stress or strain on stents. The Vici stent was the best in stress and strain on vessels and worst in radial force and flexibility. CONCLUSIONS An unsatisfactory comprehensive biomechanical performance from configurations rooted in existing stents may account for the high incidence of ISR in CVOD.
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Affiliation(s)
- Yang Yu
- Kidney Research Laboratory, Division of Nephrology, West China Hospital of Sichuan University, Chengdu, China
- Interventional Therapy Center, West China Hospital of Sichuan University, Chengdu, China
| | - Yuqin Xiong
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China
| | - Tao Li
- College of Mechanical Engineering, Sichuan University, Chengdu, China
| | - Jingyuan Zhou
- Department of Applied Mechanics, Sichuan University, Chengdu, China
| | - Weijie Yan
- Division of Radiology, West China Hospital of Sichuan University, Chengdu, China
| | - Yan Xiong
- College of Mechanical Engineering, Sichuan University, Chengdu, China
| | - Yu Chen
- Department of Applied Mechanics, Sichuan University, Chengdu, China
| | - Ping Fu
- Kidney Research Laboratory, Division of Nephrology, West China Hospital of Sichuan University, Chengdu, China
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Forkmann C, Pritsch M, Baumann-Zumstein P, Lootz D, Joner M. In vivo chronic scaffolding force of a resorbable magnesium scaffold. J Biomech 2024; 164:111988. [PMID: 38364489 DOI: 10.1016/j.jbiomech.2024.111988] [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: 10/19/2023] [Revised: 01/31/2024] [Accepted: 02/05/2024] [Indexed: 02/18/2024]
Abstract
The aim of this study is to qualitatively characterize the in vivo chronic scaffolding force of the Magmaris® Resorbable Magnesium Scaffold (RMS). This important parameter of scaffolds must be balanced between sufficient radial support during the healing period of the vessel and avoidance of long-term vessel caging. A finite element model was established using preclinical animal data and used to predict the device diameter and scaffolding force up to 90 days after implantation. To account for scaffold resorption, it included backbone degradation as well as formation of discontinuities as observed in vivo. The predictions of the model regarding acute recoil and chronic development of the device diameter were in good agreement with the preclinical data, supporting the validity of the model. It was found that after 28 and 90 days, the Magmaris® RMS retained 90 % and 47 % of its initial scaffolding force, respectively. The reduction in scaffolding force was mainly driven by discontinuities in the meandering segments. Finite element analysis combined with preclinical data is a reliable method to characterize the chronic scaffolding force.
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Affiliation(s)
| | | | | | - Daniel Lootz
- Biotronik AG, Ackerstraße 6, 8180 Bülach, Switzerland.
| | - Michael Joner
- German Heart Center Munich, Lazarettstraße 36, 80636 München, Germany.
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3
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Bernini M, Hellmuth R, Dunlop C, Ronan W, Vaughan TJ. Recommendations for finite element modelling of nickel-titanium stents-Verification and validation activities. PLoS One 2023; 18:e0283492. [PMID: 37556457 PMCID: PMC10411813 DOI: 10.1371/journal.pone.0283492] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 03/11/2023] [Indexed: 08/11/2023] Open
Abstract
The objective of this study is to present a credibility assessment of finite element modelling of self-expanding nickel-titanium (Ni-Ti) stents through verification and validation (VV) activities, as set out in the ASME VV-40 standard. As part of the study, the role of calculation verification, model input sensitivity, and model validation is examined across three different application contexts (radial compression, stent deployment in a vessel, fatigue estimation). A commercially available self-expanding Ni-Ti stent was modelled, and calculation verification activities addressed the effects of mesh density, element integration and stable time increment on different quantities of interests, for each context of use considered. Sensitivity analysis of the geometrical and material input parameters and validation of deployment configuration with in vitro comparators were investigated. Results showed similar trends for global and local outputs across the contexts of use in response to the selection of discretization parameters, although with varying sensitivities. Mesh discretisation showed substantial variability for less than 4 × 4 element density across the strut cross-section in radial compression and deployment cases, while a finer grid was deemed necessary in fatigue estimation for reliable predictions of strain/stress. Element formulation also led to substantial variation depending on the chosen integration options. Furthermore, for explicit analyses, model results were highly sensitive to the chosen target time increment (e.g., mass scaling parameters), irrespective of whether quasistatic conditions were ensured (ratios of kinetic and internal energies below 5%). The higher variability was found for fatigue life simulation, with the estimation of fatigue safety factor varying up to an order of magnitude depending on the selection of discretization parameters. Model input sensitivity analysis highlighted that the predictions of outputs such as radial force and stresses showed relatively low sensitivity to Ni-Ti material parameters, which suggests that the calibration approaches used in the literature to date appear reasonable, but a higher sensitivity to stent geometry, namely strut thickness and width, was found. In contrast, the prediction of vessel diameter following deployment was least sensitive to numerical parameters, and its validation with in vitro comparators offered a simple and accurate (error ~ 1-2%) method when predicting diameter gain, and lumen area, provided that the material of the vessel is appropriately characterized and modelled.
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Affiliation(s)
- Martina Bernini
- Biomechanics Research Centre (BioMEC), College of Science and Engineering, University of Galway, Galway, Ireland
- Vascular Flow Technologies, Dundee, United Kingdom
| | | | - Craig Dunlop
- Vascular Flow Technologies, Dundee, United Kingdom
| | - William Ronan
- Biomechanics Research Centre (BioMEC), College of Science and Engineering, University of Galway, Galway, Ireland
| | - Ted J. Vaughan
- Biomechanics Research Centre (BioMEC), College of Science and Engineering, University of Galway, Galway, Ireland
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4
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Evaluation of coronary stents: A review of types, materials, processing techniques, design, and problems. Heliyon 2023; 9:e13575. [PMID: 36846695 PMCID: PMC9950843 DOI: 10.1016/j.heliyon.2023.e13575] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 01/22/2023] [Accepted: 02/02/2023] [Indexed: 02/11/2023] Open
Abstract
In the world, one of the leading causes of death is coronary artery disease (CAD). There are several ways to treat this disease, and stenting is currently the most appropriate way in many cases. Nowadays, the use of stents has rapidly increased, and they have been introduced in various models, with different geometries and materials. To select the most appropriate stent required, it is necessary to have an analysis of the mechanical behavior of various types of stents. The purpose of this article is to provide a complete overview of advanced research in the field of stents and to discuss and conclude important studies on different topics in the field of stents. In this review, we introduce the types of coronary stents, materials, stent processing technique, stent design, classification of stents based on the mechanism of expansion, and problems and complications of stents. In this article, by reviewing the biomechanical studies conducted in this field and collecting and classifying their results, a useful set of information has been presented to continue research in the direction of designing and manufacturing more efficient stents, although the clinical-engineering field still needs to continue research to optimize the design and construction. The optimum design of stents in the future is possible by simulation and using numerical methods and adequate knowledge of stent and artery biomechanics.
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InSilc Computational Tool for In Silico Optimization of Drug-Eluting Bioresorbable Vascular Scaffolds. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2022; 2022:5311208. [PMID: 36105243 PMCID: PMC9467806 DOI: 10.1155/2022/5311208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 08/12/2022] [Accepted: 08/17/2022] [Indexed: 11/17/2022]
Abstract
Stents made by different manufacturers must meet the requirements of standard in vitro mechanical tests performed under different physiological conditions in order to be validated. In addition to in vitro research, there is a need for in silico numerical simulations that can help during the stent prototyping phase. In silico simulations have the ability to give the same stent responses as well as the potential to reduce costs and time needed to carry out experimental tests. The goal of this paper is to show the achievements of the computational platform created as a result of the EU-funded project InSilc, used for numerical testing of most standard tests for validation of preproduction bioresorbable vascular scaffolds (BVSs). Within the platform, an ad hoc simulation protocol has been developed based on the finite element (FE) analysis program PAK and user interface software CAD Field and Solid. Two different designs of two different stents have been numerically simulated using this integrated tool, and the results have been demonstrated. The following standard tests have been performed: longitudinal tensile strength, local compression, kinking, and flex 1-3. Strut thickness and additional pocket holes (slots) in two different scaffolds have been used as representative parameters for comparing the mechanical characteristics of the stents (AB-BVS vs. AB-BVS-thinner and PLLA-prot vs. PLLA-plot-slot). The AB-BVS-thinner prototype shows better overall stress distribution than the AB-BVS, while the PLLA-prot shows better overall stress distribution in comparison to the PLLA-plot-slot. In all cases, the values of the maximum effective stresses are below 220 MPa—the value obtained by in vitro experiment. Despite the presented results, additional considerations should be included before the proposed software can be used as a validation tool for stent prototyping.
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Yao J, Bosi GM, Burriesci G, Wurdemann H. Computational Analysis of Balloon Catheter Behaviour at Variable Inflation Levels. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2022; 2022:3015-3019. [PMID: 36083934 DOI: 10.1109/embc48229.2022.9871164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Aortic valvuloplasty is a minimally invasive procedure for the dilatation of stenotic aortic valves. Rapid ventricular pacing is an established technique for balloon stabilization during this procedure. However, low cardiac output due to the pacing is one of the inherent risks, which is also associated with several potential complications. This paper proposes a numerical modelling approach to understand the effect of different inflation levels of a valvuloplasty balloon catheter on the positional instability caused by a pulsating blood flow. An unstretched balloon catheter model was crimped into a tri-folded configuration and inflated to several levels. Ten different inflation levels were then tested, and a Fluid-Structure Interaction model was built to solve interactions between the balloon and the blood flow modelled in an idealised aortic arch. Our computational results show that the maximum displacement of the balloon catheter increases with the inflation level, with a small step at around 50% inflation and a sharp increase after reaching 85% inflation. This work represents a substantial progress towards the use of simulations to solve the interactions between a balloon catheter and pulsating blood flow.
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7
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Bernini M, Colombo M, Dunlop C, Hellmuth R, Chiastra C, Ronan W, Vaughan TJ. Oversizing of self-expanding nitinol vascular stents – A biomechanical investigation in the superficial femoral artery. J Mech Behav Biomed Mater 2022; 132:105259. [DOI: 10.1016/j.jmbbm.2022.105259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 04/20/2022] [Accepted: 04/29/2022] [Indexed: 10/18/2022]
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8
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Wu X, Lunardi M, Elkoumy A, Huang J, Kan J, Chen S, Tu S. A novel angiography-based computational modelling for assessing the dynamic stress and quantitative fatigue fracture risk of the coronary stents immediately after implantation: Effects of stent materials, designs and target vessel motions. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2022. [DOI: 10.1016/j.medntd.2022.100121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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9
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Kokkinos C, Drakoulas G, Fotiadis D, Kokkinos S, Loukas K, Moulas AN, Semertzioglou A. FEA of Drug-Eluting Stents and Sensitivity Analysis of a Continuum Damage Model for the Degradation of PLGA Coating. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:4324-4328. [PMID: 34892178 DOI: 10.1109/embc46164.2021.9630612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Drug-Eluting Stents (DES) are commonly used in coronary angioplasty operations as a solution against artery stenosis and restenosis. Computational Bioengineering allows for the in-silico analysis of their performance. The scope of this work is to develop a DES Digital Twin, focusing on the mechanical integrity of its biodegradable coating throughout the operational lifecycle. The implementation leverages the Finite Element Method (FEM) to compute the developed mechanical stress field on the DES during the inflation/deflation stage, followed by the degradation of the polymer-based coating. The simulation of the degradation process is based on a Continuum Damage Mechanics (CDM) model that considers bulk degradation. The CDM algorithm is implemented on the NX Nastran solver through a user-defined material (UMAT) subroutine. For benchmarking purposes and to compare with the baseline design of the BioCoStent project, this conceptual study implements an alternative stent design, to study the effect of the geometry on the developed stresses. Additionally, the effect of the degradation rate on the polymer-based coating's lifecycle is studied via sensitivity analysis.
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10
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Milosevic M, Anic M, Nikolic D, Geroski V, Milicevic B, Kojic M, Filipovic N. Application of in silico Platform for the Development and Optimization of Fully Bioresorbable Vascular Scaffold Designs. FRONTIERS IN MEDICAL TECHNOLOGY 2021; 3:724062. [PMID: 35047953 PMCID: PMC8757700 DOI: 10.3389/fmedt.2021.724062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 09/08/2021] [Indexed: 11/29/2022] Open
Abstract
Bioresorbable vascular scaffolds (BVS), made either from polymers or from metals, are promising materials for treating coronary artery disease through the processes of percutaneous transluminal coronary angioplasty. Despite the opinion that bioresorbable polymers are more promising for coronary stents, their long-term advantages over metallic alloys have not yet been demonstrated. The development of new polymer-based BVS or optimization of the existing ones requires engineers to perform many very expensive mechanical tests to identify optimal structural geometry and material characteristics. in silico mechanical testing opens the possibility for a fast and low-cost process of analysis of all the mechanical characteristics and also provides the possibility to compare two or more competing designs. In this study, we used a recently introduced material model of poly-l-lactic acid (PLLA) fully bioresorbable vascular scaffold and recently empowered numerical InSilc platform to perform in silico mechanicals tests of two different stent designs with different material and geometrical characteristics. The result of inflation, radial compression, three-point bending, and two-plate crush tests shows that numerical procedures with true experimental constitutive relationships could provide reliable conclusions and a significant contribution to the optimization and design of bioresorbable polymer-based stents.
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Affiliation(s)
- Miljan Milosevic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Institute for Information Technologies, University of Kragujevac, Kragujevac, Serbia
- Faculty of Information Technologies, Belgrade Metropolitan University, Belgrade, Serbia
| | - Milos Anic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Faculty of Engineering, University of Kragujevac, Kragujevac, Serbia
| | - Dalibor Nikolic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Institute for Information Technologies, University of Kragujevac, Kragujevac, Serbia
| | - Vladimir Geroski
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Faculty of Engineering, University of Kragujevac, Kragujevac, Serbia
| | - Bogdan Milicevic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Faculty of Engineering, University of Kragujevac, Kragujevac, Serbia
| | - Milos Kojic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX, United States
- Serbian Academy of Sciences and Arts, Belgrade, Serbia
| | - Nenad Filipovic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
- Faculty of Engineering, University of Kragujevac, Kragujevac, Serbia
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Marvi-Mashhadi M, Ali W, Li M, González C, LLorca J. Simulation of corrosion and mechanical degradation of additively manufactured Mg scaffolds in simulated body fluid. J Mech Behav Biomed Mater 2021; 126:104881. [PMID: 34702672 DOI: 10.1016/j.jmbbm.2021.104881] [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: 06/27/2021] [Revised: 08/28/2021] [Accepted: 10/02/2021] [Indexed: 10/20/2022]
Abstract
A simulation strategy based in the finite element model was developed to model the corrosion and mechanical properties of biodegradable Mg scaffolds manufactured by laser power bed fusion after immersion in simulated body fluid. Corrosion was simulated through a phenomenological, diffusion-based model which can take into account pitting. The elements in which the concentration of Mg was below a certain threshold (representative of the formation of Mg(OH)2) after the corrosion simulation were deleted for the mechanical simulations, in which Mg was assumed to behave as an isotropic, elastic-perfectly plastic solid and fracture was introduced through a ductile failure model. The parameters of the models were obtained from previous experimental results and the numerical predictions of the strength and fracture mechanisms of WE43 Mg alloy porous scaffolds in the as-printed condition and after immersion in simulated body fluid were in good agreement with the experimental results. Thus, the simulation strategy is able to assess the effect of corrosion on the mechanical behavior of biodegradable scaffolds, which is critical for design of biodegradable scaffolds for biomedical applications.
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Affiliation(s)
| | - Wahaaj Ali
- Carlos III University of Madrid, Av. de La Universidad 30, 28911, Leganés, Madrid, Spain; IMDEA Materials Institute, C/Eric Kandel 2, 28906, Getafe, Madrid, Spain
| | - Muzi Li
- IMDEA Materials Institute, C/Eric Kandel 2, 28906, Getafe, Madrid, Spain
| | - Carlos González
- IMDEA Materials Institute, C/Eric Kandel 2, 28906, Getafe, Madrid, Spain; Department of Materials Science, Polytechnic University of Madrid, 28040, Madrid, Spain
| | - Javier LLorca
- IMDEA Materials Institute, C/Eric Kandel 2, 28906, Getafe, Madrid, Spain; Department of Materials Science, Polytechnic University of Madrid, 28040, Madrid, Spain.
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12
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Antonini L, Mandelli L, Berti F, Pennati G, Petrini L. Validation of the computational model of a coronary stent: a fundamental step towards in silico trials. J Mech Behav Biomed Mater 2021; 122:104644. [PMID: 34186285 DOI: 10.1016/j.jmbbm.2021.104644] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 04/22/2021] [Accepted: 06/09/2021] [Indexed: 11/30/2022]
Abstract
The proof of the reliability of a numerical model is becoming of paramount importance in the era of in silico clinical trials. When dealing with a coronary stenting procedure, the virtual scenario should be able to replicate the real device, passing through the different stages of the procedure, which has to maintain the atherosclerotic vessel opened. Nevertheless, most of the published studies adopted commercially resembling geometries and generic material parameters, without a specific validation of the employed numerical models. In this work, a workflow for the generation and validation of the computational model of a coronary stent was proposed. Possible sources of variability in the results, such as the inter-batches variability in the material properties and the choice of proper simulation strategies, were accounted for and discussed. Then, a group of in vitro tests, representative of the device intended use was used as a comparator to validate the model. The free expansion simulation, which is the most used simulation in the literature, was shown to be only partially useful for stent model validation purposes. On the other hand, the choice of proper additional experiments, as the suggested uniaxial tensile tests on the stent and deployment tests into a deformable tube, could provide further suitable information to prove the efficacy of the numerical approach.
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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.
| | - 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.
| | - Francesca Berti
- 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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Computational and experimental mechanical performance of a new everolimus-eluting stent purpose-built for left main interventions. Sci Rep 2021; 11:8728. [PMID: 33888765 PMCID: PMC8062511 DOI: 10.1038/s41598-021-87908-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 04/06/2021] [Indexed: 12/31/2022] Open
Abstract
Left main (LM) coronary artery bifurcation stenting is a challenging topic due to the distinct anatomy and wall structure of LM. In this work, we investigated computationally and experimentally the mechanical performance of a novel everolimus-eluting stent (SYNERGY MEGATRON) purpose-built for interventions to large proximal coronary segments, including LM. MEGATRON stent has been purposefully designed to sustain its structural integrity at higher expansion diameters and to provide optimal lumen coverage. Four patient-specific LM geometries were 3D reconstructed and stented computationally with finite element analysis in a well-validated computational stent simulation platform under different homogeneous and heterogeneous plaque conditions. Four different everolimus-eluting stent designs (9-peak prototype MEGATRON, 10-peak prototype MEGATRON, 12-peak MEGATRON, and SYNERGY) were deployed computationally in all bifurcation geometries at three different diameters (i.e., 3.5, 4.5, and 5.0 mm). The stent designs were also expanded experimentally from 3.5 to 5.0 mm (blind analysis). Stent morphometric and biomechanical indices were calculated in the computational and experimental studies. In the computational studies the 12-peak MEGATRON exhibited significantly greater expansion, better scaffolding, smaller vessel prolapse, and greater radial strength (expressed as normalized hoop force) than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY (p < 0.05). Larger stent expansion diameters had significantly better radial strength and worse scaffolding than smaller stent diameters (p < 0.001). Computational stenting showed comparable scaffolding and radial strength with experimental stenting. 12-peak MEGATRON exhibited better mechanical performance than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY. Patient-specific computational LM stenting simulations can accurately reproduce experimental stent testing, providing an attractive framework for cost- and time-effective stent research and development.
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Filipovic N, Nikolic D, Isailovic V, Milosevic M, Geroski V, Karanasiou G, Fawdry M, Flanagan A, Fotiadis D, Kojic M. In vitro and in silico testing of partially and fully bioresorbable vascular scaffold. J Biomech 2020; 115:110158. [PMID: 33360181 DOI: 10.1016/j.jbiomech.2020.110158] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 11/24/2020] [Accepted: 11/25/2020] [Indexed: 11/28/2022]
Abstract
Coronary artery disease (CAD), one of the leading causes of death globally, occurs due to the growth of atherosclerotic plaques in the coronary arteries, causing lesions which restrict the flow of blood to the myocardium. Percutaneous transluminal coronary angioplasty (PTCA), including balloon angioplasty and coronary stent deployment is a standard clinical invasive treatment for CAD. Coronary stents are delivered using a balloon catheter inserted across the lesion. The balloon is inflated to a nominal pressure, opening the occluded artery, deploying the stent and improving the flow of blood to the myocardium. All stent manufacturers have to perform standard in vitro mechanical testing under different physiological conditions. In this study, partially and fully bioresorbable vascular scaffolds (BVS) from Boston Scientific Limited have been examined in vitro and in silico for three different test methods: inflation, radial compression and crush resistance. We formulated a material model for poly-L-lactic acid (PLLA) and implemented it into our in-house software tool. A comparison of the different experimental results is presented in the form of graphs showing displacement-force curves, diameter - load curves or diameter - pressure curves. There is a strong correlation between simulation and real experiments with a coefficient of determination (R2) > 0.99 and a correlation coefficient (R) > 0.99. This preliminary study has shown that in-silico tests can mimic the applicable ISO standards for mechanical in vitro stent testing, providing the opportunity to use data generated using in-silico testing to partially or fully replacing the mechanical testing required for regulatory submission.
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Affiliation(s)
- Nenad Filipovic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia; Faculty of Engineering, University of Kragujevac, Serbia.
| | - Dalibor Nikolic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia; Faculty of Engineering, University of Kragujevac, Serbia
| | - Velibor Isailovic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia; Faculty of Engineering, University of Kragujevac, Serbia
| | - Miljan Milosevic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia; Faculty of Engineering, University of Kragujevac, Serbia
| | - Vladimir Geroski
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia; Faculty of Engineering, University of Kragujevac, Serbia
| | | | | | | | | | - Milos Kojic
- Bioengineering Research and Development Center, BioIRC, Kragujevac, Serbia
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A Smart Stent for Monitoring Eventual Restenosis: Computational Fluid Dynamic and Finite Element Analysis in Descending Thoracic Aorta. MACHINES 2020. [DOI: 10.3390/machines8040081] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Even though scientific studies of smart stents are extensive, current smart stents focus on pressure sensors. This paper presents a novel implantable biocompatible smart stent for monitoring eventual restenosis. The device is comprised of a metal mesh structure, a biocompatible and adaptable envelope, and pair-operated ultrasonic sensors for restenosis monitoring through flow velocity. Aside from continuous monitoring of restenosis post-implantation, it is also important to evaluate whether the stent design itself causes complications such as restenosis or thrombosis. Therefore, computational fluid dynamic (CFD) analysis before and after stent implantation were carried out as well as finite element analysis (FEA). The proposed smart stent was put in the descending thoracic section of a virtually reconstructed aorta that comes from a computed tomography (CT) scan. Blood flow velocity showed that after stent implantation, there is not liquid retention or vortex generation. In addition, blood pressures after stent implantation were within the normal blood pressure values. The stress and the factor of safety (FOS) analysis showed that the stress values reached by the stent are very far from the yield strength limit of the materials and that the stent is stiff enough to support the applied loads exported from the CFD results.
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16
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Tribological Characteristics of Human Vascular Smooth Muscle Cells: The Implication of Disease State on Friction. ACTA ACUST UNITED AC 2020. [DOI: 10.1016/j.biotri.2020.100122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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17
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Bukala J, Buszman PP, Małachowski J, Mazurkiewicz L, Sybilski K. Experimental Tests, FEM Constitutive Modeling and Validation of PLGA Bioresorbable Polymer for Stent Applications. MATERIALS 2020; 13:ma13082003. [PMID: 32344744 PMCID: PMC7215386 DOI: 10.3390/ma13082003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 04/20/2020] [Accepted: 04/21/2020] [Indexed: 02/04/2023]
Abstract
The use of bioresorbable polymers such as poly(lactic-co-glycolic acid) (PLGA) in coronary stents can hypothetically reduce the risk of complications (e.g., restenosis, thrombosis) after percutaneous coronary intervention. However, there is a need for a constitutive modeling strategy that combines the simplicity of implementation with strain rate dependency. Here, a constitutive modeling methodology for PLGA comprising numerical simulation using a finite element method is presented. First, the methodology and results of PLGA experimental tests are presented, with a focus on tension tests of tubular-type specimens with different strain rates. Subsequently, the constitutive modeling methodology is proposed and described. Material model constants are determined based on the results of the experimental tests. Finally, the developed methodology is validated by experimental and numerical comparisons of stent free compression tests with various compression speeds. The validation results show acceptable correlation in terms of both quality and quantity. The proposed and validated constitutive modeling approach for the bioresorbable polymer provides a useful tool for the design and evaluation of bioresorbable stents.
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Affiliation(s)
- Jakub Bukala
- Institute of Mechanics and Computational Engineering, Faculty of Mechanical Engineering, Military University of Technology, Gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland; (J.B.); (L.M.); (K.S.)
| | - Piotr P. Buszman
- Center for Cardiovascular Research and Development American Heart of Poland, Czajek 41, 40-534 Katowice, Poland;
- Department of Cardiology, Andrzej Frycz-Modrzewski Kraków University, Gustawa Herlinga-Grudzińskiego 1, 30-705 Cracow, Poland
| | - Jerzy Małachowski
- Institute of Mechanics and Computational Engineering, Faculty of Mechanical Engineering, Military University of Technology, Gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland; (J.B.); (L.M.); (K.S.)
- Correspondence: ; Tel.: +48-261-839-140
| | - Lukasz Mazurkiewicz
- Institute of Mechanics and Computational Engineering, Faculty of Mechanical Engineering, Military University of Technology, Gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland; (J.B.); (L.M.); (K.S.)
| | - Kamil Sybilski
- Institute of Mechanics and Computational Engineering, Faculty of Mechanical Engineering, Military University of Technology, Gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland; (J.B.); (L.M.); (K.S.)
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Future Balloon-Expandable Stents: High or Low-Strength Materials? Cardiovasc Eng Technol 2019; 11:188-204. [PMID: 31836964 DOI: 10.1007/s13239-019-00450-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 12/07/2019] [Indexed: 10/25/2022]
Abstract
PURPOSE Recent progress in material science allows researchers to use novel materials with enhanced capabilities like optimum biodegradability, higher strength, and flexibility in the design of coronary stents. Considering the wide range of mechanical properties of existing and newfangled materials, finding the influence of variations in mechanical properties of stent materials is critical for developing a practical design. METHODS The sensitivity of stent functional characteristics to variations in its material plastic properties is obtained through FEM modeling. Balloon-expandable coronary stent designs: Absorb BVS, and Xience are examined for artificial and commercial polymeric, and metallic materials, respectively. Standard tests including (1) the crimping process followed by stent implantation in an atherosclerotic artery and (2) the three-point bending test, have been simulated according to ASTM standards. RESULTS In Absorb BVS, materials with higher yield stress than PLLA have similar residual deflection and maximum bending force to PLLA, which is not the case for Xience stent and Co-Cr. Moreover, elevated yield stress significantly reduces stent flexibility only in Xience stent. For both stents, with different degree of influence, an increase in yield or ultimate stress improves stent radial strength and stiffness and reduces arterial stress and plastic strain of stent, which consequently enhances the stent mechanical performance. Contrarily, yield or ultimate stress elevation increases stent recoil which adversely affects stent performance. CONCLUSION Using high-strength materials has a double-edged sword effect on the stent performance and existing uncertainty in the precise estimate of stent mechanical properties adversely affects the reliability of numerical models' predictions.
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Karanasiou GS, Rigas GA, Kyriakidis SK, Tachos NS, Sakellarios AI, Fotiadis DI. InSilc: 3D Reconstruction and plaque characterization tool. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2019; 2018:4528-4531. [PMID: 30441358 DOI: 10.1109/embc.2018.8513126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Coronary artery disease (CAD) is the leading cause of mortality in Europe and worldwide. Atherosclerosis is the most common pathologic process that is highly related with CAD, while the implantation of drug-eluting Bioresorbable Vascular Scaffolds (BVS) is the most promising procedure for treating patients with CAD. InSilc is an textbfin silico clinical trial (ISCT) platform for the development and assessment of drugeluting BVS. The InSilc platform provides insight in the performance of drug-eluting BVS in their short term and medium/long term through the Mechanical Modelling Module, the Deployment Module, the Fluid Dynamics Module, the Myocardial Perfusion Module, the Drug-delivery Module and the Degradation Module. In order for the aforementioned modules to be developed, the utilization of the reconstructed patient specific arterial segment and the BVS design are required, which is achieved through the 3D reconstruction and plaque characterization tool.In this study, the overall architecture of the InSilc platform is presented with special emphasis on the 3D reconstruction and plaque characterization tool. The tool will be able to implement different medical image processing workflows. The workflows will require minimum user intervention in order to be used in large scale clinical trials.
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20
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Alam ST, Ansari A, Urooj S, Aldobali M. A Review based on Biodegradable and Bioabsorbable Stents for Coronary Artery Disease. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.procs.2019.05.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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21
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Li S, Lei L, Hu Y, Zhang Y, Zhao S, Zhang J. A fully coupled framework for in silico investigation of in-stent restenosis. Comput Methods Biomech Biomed Engin 2018; 22:217-228. [PMID: 30596516 DOI: 10.1080/10255842.2018.1545017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Finite element analysis (FEA) can be implemented along with Agent-based model (ABM) to investigate the biomechanical and mechanobiological mechanisms of pathophysiological processes. However, traditional ABM-FEA approaches are often partially coupled and lack the feedback responses from biological analysis. To overcome this problem, a fully coupled ABM-FEA framework is developed in this paper by linking the macro-scale and cell-scale modules bi-directionally. Numerical studies of the in-stent restenosis process are conducted using the proposed approach and comparisons are made between the two types of frameworks. A reduction in lumen loss rate, which is possibly caused by the time-varying stresses, is observed in the fully coupled simulations. The re-endothelialisation process is also simulated under different frameworks and the simulation results show strong inhibition of endothelial cells to vascular restenosis. The proposed method is proved to be effective to explain the biomechanical-mechanobiological coupling characteristics of the restenosis problem and can be utilized for stent design and optimization.
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Affiliation(s)
- Shibo Li
- a Shenzhen Key Laboratory of Minimally Invasive Surgical Robotics and System , Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences , Shenzhen , China
| | - Long Lei
- a Shenzhen Key Laboratory of Minimally Invasive Surgical Robotics and System , Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences , Shenzhen , China
| | - Ying Hu
- a Shenzhen Key Laboratory of Minimally Invasive Surgical Robotics and System , Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences , Shenzhen , China
| | - Yanfang Zhang
- b Department of Interventional Radiology , Shenzhen People's Hospital , Shenzhen , China
| | - Shijia Zhao
- a Shenzhen Key Laboratory of Minimally Invasive Surgical Robotics and System , Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences , Shenzhen , China
| | - Jianwei Zhang
- c TAMS, Department of Informatics , University of Hamburg , Hamburg , Germany
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22
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Karanasiou GS, Tachos NS, Sakellarios A, Michalis LK, Conway C, Edelman ER, Fotiadis DI. In silico assessment of the effects of material on stent deployment. PROCEEDINGS. IEEE INTERNATIONAL SYMPOSIUM ON BIOINFORMATICS AND BIOENGINEERING 2018; 2017:462-467. [PMID: 30079407 DOI: 10.1109/bibe.2017.00-11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Coronary stents are expandable scaffolds that are used to widen occluded diseased arteries and restore blood flow. Because of the strain they are exposed to and forces they must resist as well as the importance of surface interactions, material properties are dominant. Indeed, a common differentiating factors amongst commercially available stents is their material. Several performance requirements relate to stent materials including radial strength for adequate arterial support post-deployment. This study investigated the effect of the stent material in three finite element models using different stents made of: (i) Cobalt-Chromium (CoCr), (ii) Stainless Steel (SS316L), and (iii) Platinum Chromium (PtCr). Deployment was investigated in a patient specific arterial geometry, created based on a fusion of angiographic data and intravascular ultrasound images. In silico results show that: (i) the maximum von Mises stress occurs for the CoCr, however the curved areas of the stent links present higher stresses compared to the straight stent segments for all stents, (ii) more areas of high inner arterial stress exist in the case of the CoCr stent deployment, (iii) there is no significant difference in the percentage of arterial stress volume distribution among all models.
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Affiliation(s)
- Georgia S Karanasiou
- Department of Biomedical Research, Institute of Molecular Biology and Biotechnology, FORTH Ioannina, Greece,
| | - Nikolaos S Tachos
- Department of Biomedical Research, Institute of Molecular Biology and Biotechnology, FORTH Ioannina, Greece
| | - Antonios Sakellarios
- Department of Biomedical Research, Institute of Molecular Biology and Biotechnology, FORTH Ioannina, Greece
| | - Lampros K Michalis
- Department of Cardiology, Medical School, University of Ioannina, Ioannina, Greece
| | - Claire Conway
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, CBSET, Lexington, MA, USA.
| | - Elazer R Edelman
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MACBSET, Lexington, MA, USA.
| | - Dimitrios I Fotiadis
- University of Ioannina, Department of Materials Science, Unit of Medical Technology and Intelligent Information Systems
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23
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Owen B, Bojdo N, Jivkov A, Keavney B, Revell A. Structural modelling of the cardiovascular system. Biomech Model Mechanobiol 2018; 17:1217-1242. [PMID: 29911296 PMCID: PMC6154127 DOI: 10.1007/s10237-018-1024-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 04/25/2018] [Indexed: 02/02/2023]
Abstract
Computational modelling of the cardiovascular system offers much promise, but represents a truly interdisciplinary challenge, requiring knowledge of physiology, mechanics of materials, fluid dynamics and biochemistry. This paper aims to provide a summary of the recent advances in cardiovascular structural modelling, including the numerical methods, main constitutive models and modelling procedures developed to represent cardiovascular structures and pathologies across a broad range of length and timescales; serving as an accessible point of reference to newcomers to the field. The class of so-called hyperelastic materials provides the theoretical foundation for the modelling of how these materials deform under load, and so an overview of these models is provided; comparing classical to application-specific phenomenological models. The physiology is split into components and pathologies of the cardiovascular system and linked back to constitutive modelling developments, identifying current state of the art in modelling procedures from both clinical and engineering sources. Models which have originally been derived for one application and scale are shown to be used for an increasing range and for similar applications. The trend for such approaches is discussed in the context of increasing availability of high performance computing resources, where in some cases computer hardware can impact the choice of modelling approach used.
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Affiliation(s)
- Benjamin Owen
- School of Mechanical, Aerospace and Civil Engineering, University of Manchester, George Begg Building, Manchester, M1 3BB, UK.
| | - Nicholas Bojdo
- School of Mechanical, Aerospace and Civil Engineering, University of Manchester, George Begg Building, Manchester, M1 3BB, UK
| | - Andrey Jivkov
- School of Mechanical, Aerospace and Civil Engineering, University of Manchester, George Begg Building, Manchester, M1 3BB, UK
| | - Bernard Keavney
- Division of Cardiovascular Sciences, University of Manchester, AV Hill Building, Manchester, M13 9PT, UK
| | - Alistair Revell
- School of Mechanical, Aerospace and Civil Engineering, University of Manchester, George Begg Building, Manchester, M1 3BB, UK
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24
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Prithipaul PKM, Kokkolaras M, Pasini D. Assessment of structural and hemodynamic performance of vascular stents modelled as periodic lattices. Med Eng Phys 2018; 57:11-18. [PMID: 29759946 DOI: 10.1016/j.medengphy.2018.04.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 03/17/2018] [Accepted: 04/16/2018] [Indexed: 11/16/2022]
Abstract
This work considers vascular stents with tubular geometry assumed to follow a periodic arrangement of repeating unit cells. Structural and hemodynamic metrics are presented to assess alternative stent geometries, each defined by the topology of the unit cell. Structural metrics include foreshortening, elastic recoil and radial stiffness, whereas hemodynamic performance is described by a wall shear stress index quantifying the impact of in-stent restenosis. A representative volume element (RVE) modelling approach is used, and results are compared to those obtained from full simulations of entire stents. We demonstrate that the RVE approach can be used to quantify the impact of the topology of the repeating unit on the structural and hemodynamic properties of a stent, and thus support clinicians in making proper choices among alternative stent geometries.
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Affiliation(s)
- Purnendu K M Prithipaul
- Department of Mechanical Engineering, McGill University, 817 Sherbrook St. West, Montreal, Quebec, H3A 0C3, Canada.
| | - Michael Kokkolaras
- Department of Mechanical Engineering, McGill University, 817 Sherbrook St. West, Montreal, Quebec, H3A 0C3, Canada.
| | - Damiano Pasini
- Department of Mechanical Engineering, McGill University, 817 Sherbrook St. West, Montreal, Quebec, H3A 0C3, Canada.
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25
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Gosling RC, Morris PD, Lawford PV, Hose DR, Gunn JP. Predictive Physiological Modeling of Percutaneous Coronary Intervention - Is Virtual Treatment Planning the Future? Front Physiol 2018; 9:1107. [PMID: 30154734 PMCID: PMC6103238 DOI: 10.3389/fphys.2018.01107] [Citation(s) in RCA: 2] [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: 04/13/2018] [Accepted: 07/23/2018] [Indexed: 01/10/2023] Open
Abstract
Computational modeling has been used routinely in the pre-clinical development of medical devices such as coronary artery stents. The ability to simulate and predict physiological and structural parameters such as flow disturbance, wall shear-stress, and mechanical strain patterns is beneficial to stent manufacturers. These methods are now emerging as useful clinical tools, used by physicians in the assessment and management of patients. Computational models, which can predict the physiological response to intervention, offer clinicians the ability to evaluate a number of different treatment strategies in silico prior to treating the patient in the cardiac catheter laboratory. For the first time clinicians can perform a patient-specific assessment prior to making treatment decisions. This could be advantageous in patients with complex disease patterns where the optimal treatment strategy is not clear. This article reviews the key advances and the potential barriers to clinical adoption and translation of these virtual treatment planning models.
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Affiliation(s)
- Rebecca C. Gosling
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
- Department of Cardiology, Sheffield Teaching Hospitals NHS Foundation Trust, Northern General Hospital, Sheffield, United Kingdom
- INSIGNEO Institute for in Silico Medicine, Sheffield, United Kingdom
- *Correspondence: Rebecca C. Gosling,
| | - Paul D. Morris
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
- Department of Cardiology, Sheffield Teaching Hospitals NHS Foundation Trust, Northern General Hospital, Sheffield, United Kingdom
- INSIGNEO Institute for in Silico Medicine, Sheffield, United Kingdom
- These authors have contributed equally to this work and are joint first authors
| | - Patricia V. Lawford
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
- INSIGNEO Institute for in Silico Medicine, Sheffield, United Kingdom
| | - D. Rodney Hose
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
- INSIGNEO Institute for in Silico Medicine, Sheffield, United Kingdom
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway
| | - Julian P. Gunn
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
- Department of Cardiology, Sheffield Teaching Hospitals NHS Foundation Trust, Northern General Hospital, Sheffield, United Kingdom
- INSIGNEO Institute for in Silico Medicine, Sheffield, United Kingdom
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26
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Bukala J, Kwiatkowski P, Malachowski J. Numerical analysis of crimping and inflation process of balloon-expandable coronary stent using implicit solution. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33. [PMID: 28425201 DOI: 10.1002/cnm.2890] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 03/01/2017] [Accepted: 04/15/2017] [Indexed: 06/07/2023]
Abstract
The paper presents an applied methodology for numerical finite element analysis of coronary stent crimping and the free inflation process with the use of a folded noncompliant angioplasty balloon. The use of an implicit scheme is considered as the most original part of the work, as an explicit finite element procedure is very often preferred. Hitherto, when the implicit solution was used for the finite element solution, the simulated issue was largely simplified. Therefore, the authors focused on the modelling methodology with minimum possible simplification, ie, a full load path (compression and inflation in single analysis), solid element discretization, and sophisticated contact models (bodies with highly different stiffness). The obtained results are partially compared with experimental data (radial force during the crimping procedure) and present satisfactory compliance. The authors believe that presented methodology allow for significant improvement of the obtained results, as well as potential extension of the research scope, compared to previous efforts performed using the explicit integration scheme. Moreover, the presented methodology is believed to be suitable for sensitivity and optimization studies.
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Affiliation(s)
- Jakub Bukala
- Department of Mechanics and Applied Computer Science, Military University of Technology, Gen. Sylwestra Kaliskiego 2, Warsaw, 00-908, Poland
| | - Piotr Kwiatkowski
- Clinical Department of Interventional Cardiology, Central Clinical Hospital Ministry of Interior, Woloska 137, Warsaw, 02-507, Poland
| | - Jerzy Malachowski
- Department of Mechanics and Applied Computer Science, Military University of Technology, Gen. Sylwestra Kaliskiego 2, Warsaw, 00-908, Poland
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27
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Fan Z, Liu X, Sun A, Zhang N, Fan Z, Fan Y, Deng X. Effect of longitudinal anatomical mismatch of stenting on the mechanical environment in human carotid artery with atherosclerotic plaques. Med Eng Phys 2017; 48:114-119. [DOI: 10.1016/j.medengphy.2017.06.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 05/23/2017] [Accepted: 06/02/2017] [Indexed: 12/01/2022]
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28
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Conway C, McGarry JP, Edelman ER, McHugh PE. Numerical Simulation of Stent Angioplasty with Predilation: An Investigation into Lesion Constitutive Representation and Calcification Influence. Ann Biomed Eng 2017; 45:2244-2252. [PMID: 28488215 DOI: 10.1007/s10439-017-1851-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 05/05/2017] [Indexed: 11/30/2022]
Abstract
It is acceptable clinical practice to predilate a severely occluded vessel to allow better positioning of endovascular stents, and while the impact of this intervention has been examined for aggregate response in animals there has been no means to examine whether there are specific vessels that might benefit. Finite element methods offer the singular ability to explore the mechanical response of arteries with specific pathologic alterations in mechanics to stenting and predilation. We examined varying representations of atherosclerotic tissue including homogeneous and heterogeneous dispersion of calcified particles, and elastic, pseudo-elastic, and elastic-plastic constitutive representations of bulk atherosclerotic tissue. The constitutive representations of the bulk atherosclerotic tissue were derived from experimental test data and highlight the importance of accounting for testing mode of loading. The impact of arterial predilation is presented and, in particular, its effect on intimal predicted damage, atherosclerotic tissue von Mises and maximum principal stresses, and luminal deformation was dependent on the type of constitutive representation of diseased tissue, particularly in the presence of calcifications.
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Affiliation(s)
- C Conway
- Biomechanics Research Centre (BMEC), Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway, Ireland.
- Institute for Medical Engineering and Science (IMES), Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - J P McGarry
- Biomechanics Research Centre (BMEC), Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway, Ireland
| | - E R Edelman
- Institute for Medical Engineering and Science (IMES), Massachusetts Institute of Technology, Cambridge, MA, USA
- Cardiovascular Division, Harvard Medical School, Brigham and Women's Hospital, Boston, MA, USA
| | - P E McHugh
- Biomechanics Research Centre (BMEC), Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway, Ireland
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29
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Boland EL, Grogan JA, McHugh PE. Computational Modeling of the Mechanical Performance of a Magnesium Stent Undergoing Uniform and Pitting Corrosion in a Remodeling Artery. J Med Device 2017. [DOI: 10.1115/1.4035895] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Coronary stents made from degradable biomaterials such as magnesium alloy are an emerging technology in the treatment of coronary artery disease. Biodegradable stents provide mechanical support to the artery during the initial scaffolding period after which the artery will have remodeled. The subsequent resorption of the stent biomaterial by the body has potential to reduce the risk associated with long-term placement of these devices, such as in-stent restenosis, late stent thrombosis, and fatigue fracture. Computational modeling such as finite-element analysis has proven to be an extremely useful tool in the continued design and development of these medical devices. What is lacking in computational modeling literature is the representation of the active response of the arterial tissue in the weeks and months following stent implantation, i.e., neointimal remodeling. The phenomenon of neointimal remodeling is particularly interesting and significant in the case of biodegradable stents, when both stent degradation and neointimal remodeling can occur simultaneously, presenting the possibility of a mechanical interaction and transfer of load between the degrading stent and the remodeling artery. In this paper, a computational modeling framework is developed that combines magnesium alloy degradation and neointimal remodeling, which is capable of simulating both uniform (best case) and localized pitting (realistic) stent corrosion in a remodeling artery. The framework is used to evaluate the effects of the neointima on the mechanics of the stent, when the stent is undergoing uniform or pitting corrosion, and to assess the effects of the neointimal formation rate relative to the overall stent degradation rate (for both uniform and pitting conditions).
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Affiliation(s)
- Enda L. Boland
- Biomechanics Research Centre (BMEC), Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway H91 HX31, Ireland e-mail:
| | - James A. Grogan
- Biomechanics Research Centre (BMEC), Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway H91 HX31, Ireland
| | - Peter E. McHugh
- Professor Biomechanics Research Centre (BMEC), Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway H91 HX31, Ireland e-mail:
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30
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Simão M, Ferreira JM, Mora-Rodriguez J, Ramos HM. Structural analysis of two different stent configurations. Comput Methods Biomech Biomed Engin 2017; 20:869-883. [DOI: 10.1080/10255842.2017.1306058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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31
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Stents: Biomechanics, Biomaterials, and Insights from Computational Modeling. Ann Biomed Eng 2017; 45:853-872. [PMID: 28160103 DOI: 10.1007/s10439-017-1806-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/28/2017] [Indexed: 01/02/2023]
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32
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SHEN XIANG, DENG YONGQUAN, XIE ZHONGMIN, JI SONG. ASSESSMENT OF CORONARY STENT DEPLOYMENT IN TAPERED ARTERIES: IMPACT OF ARTERIAL TAPERING. J MECH MED BIOL 2016. [DOI: 10.1142/s0219519416400157] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Coronary stents are used to prop open blocked arteries in order to restore normal blood flow. A major setback in this technology is in-stent restenosis (ISR), which gravely limits the clinical success of stents, especially in tapered vessels. The present study used the finite element method to study the effects of arterial tapering on the biomechanical behavior of both stents and vessels during stent deployment inside tapered arteries. The effect of arterial tapering was demonstrated by a combination of corresponding tapered arteries with various tapering angles, including a straight artery case for comparison. Results indicated that an increase of vessel tapering led to an increase in stent radial recoil, stent tapering following expansion, and von Mises stresses on vessels. However, an increase of vessel tapering also led to a decrease in stent foreshortening. The analysis provides suggestions for clinical application in tapered vessels. The finite element method evaluated mechanical stent behavior in tapered vessels, and can help designers to optimize the design of stents for tapered vessels.
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Affiliation(s)
- XIANG SHEN
- School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
| | - YONG-QUAN DENG
- School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
| | - ZHONG-MIN XIE
- School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
| | - SONG JI
- School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
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33
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Antoniadis AP, Mortier P, Kassab G, Dubini G, Foin N, Murasato Y, Giannopoulos AA, Tu S, Iwasaki K, Hikichi Y, Migliavacca F, Chiastra C, Wentzel JJ, Gijsen F, Reiber JH, Barlis P, Serruys PW, Bhatt DL, Stankovic G, Edelman ER, Giannoglou GD, Louvard Y, Chatzizisis YS. Biomechanical Modeling to Improve Coronary Artery Bifurcation Stenting. JACC Cardiovasc Interv 2015; 8:1281-1296. [DOI: 10.1016/j.jcin.2015.06.015] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 06/05/2015] [Accepted: 06/18/2015] [Indexed: 02/04/2023]
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34
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Design Optimisation of Coronary Artery Stent Systems. Ann Biomed Eng 2015; 44:357-67. [DOI: 10.1007/s10439-015-1373-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/23/2015] [Indexed: 10/23/2022]
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35
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Local blood flow patterns in stented coronary bifurcations: an experimental and numerical study. J Appl Biomater Funct Mater 2015; 13:e116-26. [PMID: 25589159 DOI: 10.5301/jabfm.5000217] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2014] [Indexed: 11/20/2022] Open
Abstract
PURPOSE Despite the atheroprone environment of blood flow in coronary bifurcations, limited quantitative information is available on the hemodynamics occurring in these geometries, both before and after their treatment with endovascular stents. Previous studies have focused on computational fluid dynamics (CFD) analyses and have bypassed the challenges associated with experimentally representing the flow environment, providing no means for validation. This study analyzed steady flow conditions in 3 bifurcation angles and 4 different single- and double-stenting procedures, which are used clinically in coronary bifurcations. METHODS The numerical aspect of this study utilized geometries derived from CAD models (nonstented cases) and finite element simulations (stented cases). Digital particle image velocimetry (DPIV) testing was conducted within compliant bifurcating models for which an uncertainty analysis was performed at each measurement location for CFD validation purposes. Results were analyzed in terms of velocity magnitude contour maps and axial velocity profiles at several locations in the bifurcated vessels. RESULTS AND CONCLUSIONS Qualitatively, the 2 approaches showed agreement in the bulk flow patterns. However, the velocity computed with CFD was outside the DPIV uncertainty estimates, which can be attributed to the intrinsic difference and modeling assumptions of the 2 approaches. The findings reveal that wider bifurcation angles and double-stenting procedures are both characterized by increased areas of low flow and recirculation. Additionally, inferior performance in terms of viscous and wall shear stresses was observed in double-stented cases.
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36
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Sinclair MD, Lee J, Cookson AN, Rivolo S, Hyde ER, Smith NP. Measurement and modeling of coronary blood flow. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2015; 7:335-56. [PMID: 26123867 DOI: 10.1002/wsbm.1309] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 05/19/2015] [Accepted: 05/21/2015] [Indexed: 01/10/2023]
Abstract
Ischemic heart disease that comprises both coronary artery disease and microvascular disease is the single greatest cause of death globally. In this context, enhancing our understanding of the interaction of coronary structure and function is not only fundamental for advancing basic physiology but also crucial for identifying new targets for treating these diseases. A central challenge for understanding coronary blood flow is that coronary structure and function exhibit different behaviors across a range of spatial and temporal scales. While experimental studies have sought to understand this feature by isolating specific mechanisms, in tandem, computational modeling is increasingly also providing a unique framework to integrate mechanistic behaviors across different scales. In addition, clinical methods for assessing coronary disease severity are continuously being informed and updated by findings in basic physiology. Coupling these technologies, computational modeling of the coronary circulation is emerging as a bridge between the experimental and clinical domains, providing a framework to integrate imaging and measurements from multiple sources with mathematical descriptions of governing physical laws. State-of-the-art computational modeling is being used to combine mechanistic models with data to provide new insight into coronary physiology, optimization of medical technologies, and new applications to guide clinical practice.
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Affiliation(s)
- Matthew D Sinclair
- Division of Imaging Sciences and Biomedical Engineering, British Heart Foundation (BHF) Centre of Excellence, King's College London, London, UK
| | - Jack Lee
- Division of Imaging Sciences and Biomedical Engineering, British Heart Foundation (BHF) Centre of Excellence, King's College London, London, UK
| | - Andrew N Cookson
- Division of Imaging Sciences and Biomedical Engineering, British Heart Foundation (BHF) Centre of Excellence, King's College London, London, UK
| | - Simone Rivolo
- Division of Imaging Sciences and Biomedical Engineering, British Heart Foundation (BHF) Centre of Excellence, King's College London, London, UK
| | - Eoin R Hyde
- Division of Imaging Sciences and Biomedical Engineering, British Heart Foundation (BHF) Centre of Excellence, King's College London, London, UK
| | - Nicolas P Smith
- Division of Imaging Sciences and Biomedical Engineering, British Heart Foundation (BHF) Centre of Excellence, King's College London, London, UK.,Department of Engineering, University of Auckland, Auckland, New Zealand
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37
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SHEN XIANG, XIE ZHONGMIN, SUN YANGYANG, WU BOBO. BALLOON-EXPANDABLE STENTS EXPANSION IN TAPERED VESSELS AND THEIR INTERACTIONS. J MECH MED BIOL 2014. [DOI: 10.1142/s0219519414400132] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In-stent restenosis (ISR) after stent implantation, especially in tapered vessels, remains an obstacle in the long-term benefits of stenting. In the present study, a finite element method (FEM) was employed to investigate the expansion process of balloon-expandable stents in tapered vessels (the TV model) and their interactions. For comparison, a numerical model of the same stent deployment in a straight vessel was also investigated. Results showed that in the TV model, the peak tissue stresses took place at the distal end of the tapered vessel. The node displacements of the stent's proximal and distal ends remained consistent before the stent contacted the tapered vessel, while the proximal end was larger than the distal end after the stent contacted the tapered vessel. The regions of maximum stresses in the stent after expansion were concentrated in the corners of the diamond cells of the stent's proximal end. The investigation provided some interpretations of the clinical observations in tapered vessels and also provided stent design proposals for tapered vessels. The FEM quantified the mechanical properties of stents in tapered vessels, and can help clinicians select appropriate stents, assist designers in pretests and create new stents made especially for tapered vessels.
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Affiliation(s)
- XIANG SHEN
- School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
| | - ZHONG-MIN XIE
- School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
| | - YANG-YANG SUN
- School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
| | - BO-BO WU
- School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
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38
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Morlacchi S, Pennati G, Petrini L, Dubini G, Migliavacca F. Influence of plaque calcifications on coronary stent fracture: a numerical fatigue life analysis including cardiac wall movement. J Biomech 2014; 47:899-907. [PMID: 24468208 DOI: 10.1016/j.jbiomech.2014.01.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2014] [Indexed: 10/25/2022]
Abstract
Coronary stent fracture is still an unresolved issue in the field of minimally invasive cardiovascular interventions due to its high rate of incidence and uncertain clinical consequences. Recent studies, based on clinical data, proved that there are several factors which can be identified as independently responsible of coronary stent fracture. Among these, calcifications, which increase the local stiffness and heterogeneity of atherosclerotic plaques, seem to play a major role. From a mechanical point of view, stent fracture in coronary arteries is triggered by the cyclic loading of pulsatile blood pressure combined with the movement of cardiac wall. In this context, this study aims at simulating the stent expansion in a model of epicardial atherosclerotic coronary artery and correlating the effects of cyclic blood pressure and cardiac wall movement on the stent fatigue resistance. Two ideal cases of atherosclerotic plaques were modelled: the first one included a localised plaque calcification; the latter one did not include such calcification. Results of stress/strain and fatigue analyses confirmed the influence of the plaque calcification on potential fracture of the devices. In addition, the effects of cardiac wall movement were quantified as more dangerous causes of the stent fatigue fracture with respect to the internal blood pressure oscillations. In conclusion, this study demonstrates the increased risk of coronary stent fracture associated to the presence of localised plaque calcifications. This work also suggests the necessity of more realistic biomechanical models which takes into account the heterogeneity of atherosclerotic plaques in order to assess the mechanical performances of coronary stents.
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Affiliation(s)
- Stefano Morlacchi
- Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Milano, Italy; Department of Mechanical Engineering, University of Sheffield, Sheffield, UK
| | - Giancarlo Pennati
- 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
| | - Gabriele Dubini
- Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Milano, Italy
| | - Francesco Migliavacca
- Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Milano, Italy.
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39
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Bowen PK, Drelich J, Goldman J. A new in vitro–in vivo correlation for bioabsorbable magnesium stents from mechanical behavior. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2013; 33:5064-70. [DOI: 10.1016/j.msec.2013.08.042] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Revised: 07/31/2013] [Accepted: 08/29/2013] [Indexed: 01/31/2023]
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40
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Martin D, Boyle F. Finite element analysis of balloon-expandable coronary stent deployment: influence of angioplasty balloon configuration. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2013; 29:1161-1175. [PMID: 23696255 DOI: 10.1002/cnm.2557] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 03/09/2013] [Accepted: 04/12/2013] [Indexed: 06/02/2023]
Abstract
Today, the majority of coronary stents are balloon-expandable and are deployed using a balloon-tipped catheter. To improve deliverability, the membrane of the angioplasty balloon is typically folded about the catheter in a pleated configuration. As such, the deployment of the angioplasty balloon is governed by the material properties of the balloon membrane, its folded configuration and its attachment to the catheter. Despite this observation, however, an optimum strategy for modelling the configuration of the angioplasty balloon in finite element studies of coronary stent deployment has not been identified, and idealised models of the angioplasty balloon are commonly employed in the literature. These idealised models often neglect complex geometrical features, such as the folded configuration of the balloon membrane and its attachment to the catheter, which may have a significant influence on the deployment of a stent. In this study, three increasingly sophisticated models of a typical semi-compliant angioplasty balloon were employed to determine the influence of angioplasty balloon configuration on the deployment of a stent. The results of this study indicate that angioplasty balloon configuration has a significant influence on both the transient behaviour of the stent and its impact on the mechanical environment of the coronary artery.
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Affiliation(s)
- David Martin
- Department of Mechanical Engineering, Dublin Institute of Technology, Ireland
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41
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Wu W, Chen S, Gastaldi D, Petrini L, Mantovani D, Yang K, Tan L, Migliavacca F. Experimental data confirm numerical modeling of the degradation process of magnesium alloys stents. Acta Biomater 2013; 9:8730-9. [PMID: 23128160 DOI: 10.1016/j.actbio.2012.10.035] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 09/29/2012] [Accepted: 10/28/2012] [Indexed: 11/30/2022]
Abstract
Biodegradable magnesium alloy stents (MAS) could present improved long-term clinical performances over commercial bare metal or drug-eluting stents. However, MAS were found to show limited mechanical support for diseased vessels due to fast degradation. Optimizing stent design through finite element analysis (FEA) is an efficient way to improve such properties. Following previous FEA works on design optimization and degradation modeling of MAS, this work carried out an experimental validation for the developed FEA model, thus proving its practical applicability of simulating MAS degradation. Twelve stent samples of AZ31B were manufactured according to two MAS designs (an optimized one and a conventional one), with six samples of each design. All the samples were balloon expanded and subsequently immersed in D-Hanks' solution for a degradation test lasting 14 days. The experimental results showed that the samples of the optimized design had better corrosion resistance than those of the conventional design. Furthermore, the degradation process of the samples was dominated by uniform and stress corrosion. With the good match between the simulation and the experimental results, the work shows that the FEA numerical modeling constitutes an effective tool for design and thus the improvement of novel biodegradable MAS.
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Affiliation(s)
- Wei Wu
- Laboratory of Biological Structure Mechanics, Structural Engineering Department, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133 Milan, Italy.
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42
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Morlacchi S, Colleoni SG, Cárdenes R, Chiastra C, Diez JL, Larrabide I, Migliavacca F. Patient-specific simulations of stenting procedures in coronary bifurcations: two clinical cases. Med Eng Phys 2013; 35:1272-81. [PMID: 23428836 DOI: 10.1016/j.medengphy.2013.01.007] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 12/03/2012] [Accepted: 01/21/2013] [Indexed: 10/27/2022]
Abstract
Computational simulations of stenting procedures in idealized geometries can only provide general guidelines and their use in the patient-specific planning of percutaneous treatments is inadequate. Conversely, image-based patient-specific tools that are able to realistically simulate different interventional options might facilitate clinical decision-making and provide useful insights on the treatment for each individual patient. The aim of this work is the implementation of a patient-specific model that uses image-based reconstructions of coronary bifurcations and is able to replicate real stenting procedures following clinical indications. Two clinical cases are investigated focusing the attention on the open problems of coronary bifurcations and their main treatment, the provisional side branch approach. Image-based reconstructions are created combining the information from conventional coronary angiography and computed tomography angiography while structural finite element models are implemented to replicate the real procedure performed in the patients. First, numerical results show the biomechanical influence of stents deployment in the coronary bifurcations during and after the procedures. In particular, the straightening of the arterial wall and the influence of two overlapping stents on stress fields are investigated here. Results show that a sensible decrease of the vessel tortuosity occurs after stent implantation and that overlapping devices result in an increased stress state of both the artery and the stents. Lastly, the comparison between numerical and image-based post-stenting configurations proved the reliability of such models while replicating stent deployment in coronary arteries.
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Affiliation(s)
- Stefano Morlacchi
- Laboratory of Biological Structure Mechanics (LaBS), Chemistry, Materials and Chemical Engineering Department Giulio Natta, Politecnico di Milano, Italy.
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43
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Morlacchi S, Migliavacca F. Modeling stented coronary arteries: where we are, where to go. Ann Biomed Eng 2012; 41:1428-44. [PMID: 23090621 DOI: 10.1007/s10439-012-0681-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 10/16/2012] [Indexed: 01/09/2023]
Abstract
In the last two decades, numerical models have become well-recognized and widely adopted tools to investigate stenting procedures. Due to limited computational resources and modeling capabilities, early numerical studies only involved simplified cases and idealized stented arteries. Nowadays, increased computational power allows for numerical models to meet clinical needs and include more complex cases such as the implantation of multiple stents in bifurcations or curved vessels. Interesting progresses have been made in the numerical modeling of stenting procedures both from a structural and a fluid dynamics points of view. Moreover, in the drug eluting stents era, new insights on drug elution capabilities are becoming essential in the stent development. Lastly, image-based methods able to reconstruct realistic geometries from medical images have been proposed in the recent literature aiming to better describe the peculiar anatomical features of coronary vessels and increase the accuracy of the numerical models. In this light, this review provides a comprehensive analysis of the current state-of-the-art in this research area, discussing the main methodological advances and remarkable results drawn from a number of significant studies.
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Affiliation(s)
- Stefano Morlacchi
- Laboratory of Biological Structure Mechanics, Structural Engineering Department, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milan, Italy.
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44
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A Computational Test-Bed to Assess Coronary Stent Implantation Mechanics Using a Population-Specific Approach. Cardiovasc Eng Technol 2012. [DOI: 10.1007/s13239-012-0104-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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45
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Rossi F, Casalini T, Raffa E, Masi M, Perale G. Bioresorbable Polymer Coated Drug Eluting Stent: A Model Study. Mol Pharm 2012; 9:1898-910. [DOI: 10.1021/mp200573f] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Filippo Rossi
- Department
of Chemistry, Materials and Chemical Engineering
“Giulio Natta”, Politecnico di Milano, Via Mancinelli 7, 20131 Milano, Italy
| | - Tommaso Casalini
- Department
of Chemistry, Materials and Chemical Engineering
“Giulio Natta”, Politecnico di Milano, Via Mancinelli 7, 20131 Milano, Italy
| | - Edoardo Raffa
- Department
of Chemistry, Materials and Chemical Engineering
“Giulio Natta”, Politecnico di Milano, Via Mancinelli 7, 20131 Milano, Italy
| | - Maurizio Masi
- Department
of Chemistry, Materials and Chemical Engineering
“Giulio Natta”, Politecnico di Milano, Via Mancinelli 7, 20131 Milano, Italy
| | - Giuseppe Perale
- Department
of Chemistry, Materials and Chemical Engineering
“Giulio Natta”, Politecnico di Milano, Via Mancinelli 7, 20131 Milano, Italy
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46
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Masoumi Khalil Abad E, Pasini D, Cecere R. Shape optimization of stress concentration-free lattice for self-expandable Nitinol stent-grafts. J Biomech 2012; 45:1028-35. [PMID: 22304844 DOI: 10.1016/j.jbiomech.2012.01.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 12/31/2011] [Accepted: 01/01/2012] [Indexed: 11/19/2022]
Abstract
In a mechanical component, stress-concentration is one of the factors contributing to reduce fatigue life. This paper presents a design methodology based on shape optimization to improve the fatigue safety factor and increase the radial stiffness of Nitinol self-expandable stent-grafts. A planar lattice free of stress concentrators is proposed for the synthesis of a stent with smooth cell shapes. Design optimization is systematically applied to minimize the curvature and reduce the bending strain of the elements defining the lattice cells. A novel cell geometry with improved fatigue life and radial supportive force is introduced for Nitinol self-expandable stent-grafts used for treating abdominal aortic aneurism. A parametric study comparing the optimized stent-graft to recent stent designs demonstrates that the former exhibits a superior anchoring performance and a reduction of the risk of fatigue failure.
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47
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Morlacchi S, Chiastra C, Gastaldi D, Pennati G, Dubini G, Migliavacca F. Sequential Structural and Fluid Dynamic Numerical Simulations of a Stented Bifurcated Coronary Artery. J Biomech Eng 2011; 133:121010. [DOI: 10.1115/1.4005476] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Despite their success, stenting procedures are still associated to some clinical problems like sub-acute thrombosis and in-stent restenosis. Several clinical studies associate these phenomena to a combination of both structural and hemodynamic alterations caused by stent implantation. Recently, numerical models have been widely used in the literature to investigate stenting procedures but always from either a purely structural or fluid dynamic point of view. The aim of this work is the implementation of sequential structural and fluid dynamic numerical models to provide a better understanding of stenting procedures in coronary bifurcations. In particular, the realistic geometrical configurations obtained with structural simulations were used to create the fluid domains employed within transient fluid dynamic analyses. This sequential approach was applied to investigate the final kissing balloon (FKB) inflation during the provisional side branch technique. Mechanical stresses in the arterial wall and the stent as well as wall shear stresses along the arterial wall were examined before and after the FKB deployment. FKB provoked average mechanical stresses in the arterial wall almost 2.5 times higher with respect to those induced by inflation of the stent in the main branch only. Results also enlightened FKB benefits in terms of improved local blood flow pattern for the side branch access. As a drawback, the FKB generates a larger region of low wall shear stress. In particular, after FKB the percentage of area characterized by wall shear stresses lower than 0.5 Pa was 79.0%, while before the FKB it was 62.3%. For these reasons, a new tapered balloon dedicated to bifurcations was proposed. The inclusion of the modified balloon has reduced the mechanical stresses in the proximal arterial vessel to 40% and the low wall shear stress coverage area to 71.3%. In conclusion, these results show the relevance of the adopted sequential approach to study the wall mechanics and the hemodynamics created by stent deployment.
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Affiliation(s)
- Stefano Morlacchi
- Laboratory of Biological Structure Mechanics, Structural Engineering Department, Politecnico di Milano, 20133 Milan, Italy; Department of Bioengineering, Politecnico di Milano, 20133 Milan, Italy
| | - Claudio Chiastra
- Laboratory of Biological Structure Mechanics, Structural Engineering Department, Politecnico di Milano, 20133 Milan, Italy; Department of Bioengineering, Politecnico di Milano, 20133 Milan, Italy
| | - Dario Gastaldi
- Laboratory of Biological Structure Mechanics, Structural Engineering Department, Politecnico di Milano, 20133 Milan, Italy
| | - Giancarlo Pennati
- Laboratory of Biological Structure Mechanics, Structural Engineering Department, Politecnico di Milano, 20133 Milan, Italy
| | - Gabriele Dubini
- Laboratory of Biological Structure Mechanics, Structural Engineering Department, Politecnico di Milano, 20133 Milan, Italy
| | - Francesco Migliavacca
- Laboratory of Biological Structure Mechanics, Structural Engineering Department, Politecnico di Milano, 20133 Milan, Italy
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