A finite element investigation on design parameters of bare and polymer-covered self-expanding wire braided stents

McKenna, Ciara G.; Vaughan, Ted J.

doi:10.1016/j.jmbbm.2020.104305

“…In theory, covered stents promise reduced restenosis [12], with the cover acting as a mechanical barrier to tissue in-growth, yet this doesn't consistently translate into reliable clinical outcomes in small-diameter applications [39]. While numerous clinical studies have investigated the superiority of bare-metal or covered stents [13,14,16,40], relatively few experimental or computational studies have attempted to explain the mechanical implication of stent covering to give more context to this problem [26][27][28]. Previously, it was shown that the addition of thin polymer covers to wire braided stents resulted in substantially stiffer radial and axial responses (up to ten-fold for a 25μm cover) [28].…”

Section: Discussionmentioning

confidence: 99%

“…While numerous clinical studies have investigated the superiority of bare-metal or covered stents [13,14,16,40], relatively few experimental or computational studies have attempted to explain the mechanical implication of stent covering to give more context to this problem [26][27][28]. Previously, it was shown that the addition of thin polymer covers to wire braided stents resulted in substantially stiffer radial and axial responses (up to ten-fold for a 25μm cover) [28]. is relatively compliant (E=91MPa), we still observed substantial increases in max radial force when the device was crimped to 2mm diameter, which could have implications in deliverability and crimping onto a catheter.…”

Section: Discussionmentioning

confidence: 99%

“…Our recent studies on covered braided stents showed that the addition of a cover led to substantial increases in both radial and axial stiffness, by altering the fundamental deformation mechanisms involved in these wire-based stent configurations [27,28]. Other studies on the mechanics of covered stents are limited, with research in this area mainly focussing on large stent-grafts with separated wire rings intended for abdominal artery aneurysms [29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

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A Computational Framework Examining the Mechanical Behaviour of Bare and Polymer-Covered Self-Expanding Laser-Cut Stents

McKenna

¹

,

Vaughan

²

2021

Cardiovasc Eng Tech

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Polymer covered stents have demonstrated promising clinical outcomes with improved patency rates compared to traditional bare-metal stents, however little is known on the mechanical implication of stent covering. In the present work, a combined experimental-computational investigation was carried out to determine the role of a polymeric cover on the biomechanical performance of self-expanding laser-cut stents. Experimental bench top tests were conducted on bare and covered versions of a commercial stent to evaluate the radial, axial and bending response. In parallel, a computational framework with a novel covering strategy was developed that accurately predicts stent mechanical performance, and provides further insight into covered stent mechanics by considering different stent geometries and polymer materials. Results show that stent covering causes increased initial axial stiffness and substantial radial stiffening at small crimp diameters as the cover folds and self-contacts. It was also shown that use of a stiffer polymeric covering material caused significant alterations to the radial and axial response, highlighting the importance of considering the mechanical properties of the combined cover and stent.

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“…In theory, covered stents promise reduced restenosis [12], with the cover acting as a mechanical barrier to tissue in-growth, yet this doesn't consistently translate into reliable clinical outcomes in small-diameter applications [39]. While numerous clinical studies have investigated the superiority of bare-metal or covered stents [13,14,16,40], relatively few experimental or computational studies have attempted to explain the mechanical implication of stent covering to give more context to this problem [26][27][28]. Previously, it was shown that the addition of thin polymer covers to wire braided stents resulted in substantially stiffer radial and axial responses (up to ten-fold for a 25μm cover) [28].…”

Section: Discussionmentioning

confidence: 99%

“…While numerous clinical studies have investigated the superiority of bare-metal or covered stents [13,14,16,40], relatively few experimental or computational studies have attempted to explain the mechanical implication of stent covering to give more context to this problem [26][27][28]. Previously, it was shown that the addition of thin polymer covers to wire braided stents resulted in substantially stiffer radial and axial responses (up to ten-fold for a 25μm cover) [28]. is relatively compliant (E=91MPa), we still observed substantial increases in max radial force when the device was crimped to 2mm diameter, which could have implications in deliverability and crimping onto a catheter.…”

Section: Discussionmentioning

confidence: 99%

A computational framework examining the mechanical behaviour of bare and polymer-covered self-expanding laser-cut stents

McKenna¹,

Vaughan²

2021

Preprint

Self Cite

0

View full text Add to dashboard Cite

Polymer covered stents have demonstrated promising clinical outcomes with improved patency rates compared to traditional bare-metal stents, however little is known on the mechanical implication of stent covering. In the present work, a combined experimental-computational investigation was carried out to determine the role of a polymeric cover on the biomechanical performance of self-expanding laser-cut stents. Experimental bench top tests were conducted on bare and covered versions of a commercial stent to evaluate the radial, axial and bending response. In parallel, a computational framework with a novel covering strategy was developed that accurately predicts stent mechanical performance, and provides further insight into covered stent mechanics by considering different stent geometries and polymer materials. Results show that stent covering causes increased initial axial stiffness and substantial radial stiffening at small crimp diameters as the cover folds and self-contacts. It was also shown that use of a stiffer polymeric covering material caused significant alterations to the radial and axial response, highlighting the importance of considering the mechanical properties of the combined cover and stent.

show abstract