Mechanical properties and in vitro degradation of bioabsorbable self-expanding braided stents

Nuutinen, Juha‐Pekka; Clerc, Claude; Reinikainen, Raija; Törmälä, Pertti

doi:10.1163/156856203763572707

Cited by 48 publications

(34 citation statements)

References 19 publications

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“…Zilberman et al [24] reported a loss in radial compression strength for their PLLA stent designs with degradation time, which is also associated with reductions in elastic modulus and yield strain of the PLLA fibres. Nuutinen et al [25] carried out in vitro tests of a woven fibre polymeric braided stent subjected to radial compression in a pressurized chamber. The stent design did not perform well enough when made of biodegradable polymer, and the collapse pressure was still lower than its metal counterpart even with thicker fibres.…”

Section: Degradation Behaviourmentioning

confidence: 99%

Research into biodegradable polymeric stents: a review of experimental and modelling work

Qiu¹,

Zhao²

2018

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Bioresorbable stents (BRSs) are regarded as the next-generation medical devices to treat blocked or diseased arteries.The use of BRSs aims to reduce the risk of late stent thrombosis and long-term tissue inflammation associated with permanent metallic stents. BRSs are designed to relieve symptoms immediately and also provide mechanical support for an appropriate time period before they are fully absorbed by human body. To promote clinical adoption of BRSs or even to substitute metallic stents, the mechanical performance of BRSs needs to be thoroughly investigated and quantitatively characterised, especially over the full period of degradation. This paper offers a review of current research status of polymeric BRSs, covering both experimental and modelling work. Review of experimental studies highlighted the effects of stent designs and materials on the behaviour of polymeric BRSs. Computational work was able to simulate crimping, expansion and degradation of polymeric BRSs and the results were useful for performance assessment. In summary, the development of polymeric BRSs is still at an early stage, and further research is urgently required for a better understanding and control of their mechanical performance.

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Section: Degradation Behaviourmentioning

confidence: 99%

Research into biodegradable polymeric stents: a review of experimental and modelling work

Qiu¹,

Zhao²

2018

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“…Results showed that a successful biodegradable stent could be achieved by carefully balancing the mechanical properties of PLLA fibres and geometrical design of stents. Nuutinen et al [11] conducted in vitro tests of a woven fibre polymeric braided stent subjected to radial compression. The performance of such stents was not as good as metal ones, and the collapse pressure was found lower, even for thicker PLLA fibres.…”

Section: Introductionmentioning

confidence: 99%

Crimping and deployment of metallic and polymeric stents -- finite element modelling

Schiavone¹,

Qiu²,

Zhao³

2017

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How to cite this article: Schiavone A, Qiu TY, Zhao LG. Crimping and deployment of metallic and polymeric stents --finite element modelling. Vessel Plus 2017;1:12-21.Aim: This paper aims to compare the mechanical performance of metallic (Xience) and bioresorbable polymeric (Elixir) stents during the process of crimping and deployment. Methods: Finite element software ABAQUS was used to create the geometrical models and meshes for the balloon, stent and diseased artery. To simulate the crimping of stents, 12 rigid plates were generated around the stent and subjected to radially enforced displacement. The deployment of both stents was simulated by applying internal pressure to the balloon, where hard contacts were defined between balloon, stent and diseased artery. Results: Elixir stent exhibited a lower expansion rate than Xience stent during deployment. The stent diameter achieved after balloon deflation was found smaller for Elixir stent due to higher recoiling. Lower level of stresses was found in the plaque and artery when expanded by Elixir stent. Reduced expansion, increased dogboning and decreased vessel stresses were obtained when considering the crimping-generated residual stresses in the simulations. Conclusion: There is a challenge for polymeric stents to match the mechanical performance of metallic stents. However, polymeric stents impose lower stresses to the artery system due to less property mismatch between polymers and arterial tissues, which could be clinically beneficial. Key words:Polymeric stents, metallic stents, finite element, crimping, deployment ABSTRACTArticle history:

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“…This is because for an applied strain in the z direction, it is not possible for the main chain elements to avoid strain since the chains are physically elongated in the z direction. [18][19][20]. If a single crystal had a Young's modulus of 3x this value, at 0K the Young's modulus in the direction of the polymer chains may be expected to be between 54GPa (3x3x6GPa) and 192GPa (8x3x8GPa).…”

Section: Afem Program Setup and Polymer Structuresmentioning

confidence: 99%

An atomic finite element model for biodegradable polymers. Part 1. Formulation of the finite elements

Gleadall

Pan

Ding

et al. 2015

Journal of the Mechanical Behavior of Biomedical Materials

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Molecular dynamics (MD) simulations are widely used to analyse materials at the atomic scale. However, MD has high computational demands, which may inhibit its use for simulations of structures involving large numbers of atoms such as amorphous polymerstructures. An atomic-scale finite element method (AFEM) is presented in this study with significantly lower computational demands than MD. Due to the reduced computational demands, AFEM is suitable for the analysis of Young's modulus of amorphous polymer structures. This is of particular interest when studying the degradation of bioresorbable polymers, which is the topic of an accompanying paper. AFEM is derived from the interatomic potential energy functions of an MD force field. The nonlinear MD functions were adapted to enable static linear analysis. Finite element formulations were derived to 2 represent interatomic potential energy functions between two, three and four atoms.Validation of the AFEM was conducted through its application to atomic structures for crystalline and amorphous poly(lactide).

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Mechanical properties and in vitro degradation of bioabsorbable self-expanding braided stents

Cited by 48 publications

References 19 publications

Research into biodegradable polymeric stents: a review of experimental and modelling work

Research into biodegradable polymeric stents: a review of experimental and modelling work

Crimping and deployment of metallic and polymeric stents -- finite element modelling

An atomic finite element model for biodegradable polymers. Part 1. Formulation of the finite elements

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