A numerical framework for the mechanical analysis of dual-layer stents in intracranial aneurysm treatment.

Dual-layer stents and multi-layer stents represent a new paradigm in endovascular interventions. Multi-layer stents match different stent designs in order to offer auxiliary functions. For example, dual-layer stents used in the endovascular treatment of intracranial aneurysms, like the FRED(TM) (MicroVention, CA) stent, combine a densely braided inner metallic mesh with a loosely braided outer mesh. The inner layer is designed to divert blood flow, whereas the outer one ensures microvessels branching out of the main artery remain patent. In this work, the implemented finite element (FE) analysis identifies the key aspects of dual-stent mechanics. In particular, dual-layer stents used in the treatment of intracranial aneurysms require the ability to conform to very narrow passages in their closed configuration, while at the same time they have to provide support and stability once deployed. This study developed a numerical framework for the analysis of dual-layer stents for endovascular intracranial aneurysm treatment. Our results were validated against analytical methods. For the designs considered, we observed that foreshortening was in average 37.5%±2.5%, and that doubling the number of wires in the outer stent increased bending moment by 23%, while halving the number of wires of the inner stent reduced von Mises stress by 2.3%. This framework can be extended to the design optimization of multi-layer stents used in other endovascular treatments.

[1]  Rainald Löhner,et al.  Simulation of intracranial aneurysm stenting: Techniques and challenges , 2009 .

[2]  Suncica Canic,et al.  Mathematical Modeling of Vascular Stents * , 2010 .

[3]  Suncica Canic,et al.  Mathematical Model analysis of Wallstent and Aneurx: dynamic responses of bare-metal endoprosthesis compared with those of stent-graft. , 2005, Texas Heart Institute journal.

[4]  F. D. Whitcher,et al.  Simulation of in vivo loading conditions of nitinol vascular stent structures , 1997 .

[5]  O. Diaz,et al.  Treatment of 14 intracranial aneurysms with the FRED system , 2013, Journal of NeuroInterventional Surgery.

[6]  P. J. Thompson,et al.  Assessment of wrought ASTM F1058 cobalt alloy properties for permanent surgical implants. , 1997, Journal of biomedical materials research.

[7]  C. Redmond,et al.  Cardiovascular Diseases in the United States , 1972 .

[8]  Alejandro F. Frangi,et al.  Fast virtual deployment of self-expandable stents: Method and in vitro evaluation for intracranial aneurysmal stenting , 2012, Medical Image Anal..

[9]  Hiroyuki Kosukegawa,et al.  High Fidelity Virtual Stenting (HiFiVS) for Intracranial Aneurysm Flow Diversion: In Vitro and In Silico , 2013, Annals of Biomedical Engineering.

[10]  E. Sacco,et al.  Finite-element Analysis of a Stenotic Artery Revascularization Through a Stent Insertion , 2001 .

[11]  P Segers,et al.  Virtual evaluation of stent graft deployment: a validated modeling and simulation study. , 2012, Journal of the mechanical behavior of biomedical materials.

[12]  K. Safranow,et al.  Initial experience with implantation of novel dual layer flow-diverter device FRED , 2013, Wideochirurgia i inne techniki maloinwazyjne = Videosurgery and other miniinvasive techniques.

[13]  Caitríona Lally,et al.  Determination of the influence of stent strut thickness using the finite element method: implications for vascular injury and in-stent restenosis , 2009, Medical & Biological Engineering & Computing.

[14]  F. Castro,et al.  Pulsatile flow in coronary bifurcations for different stenting techniques , 2014 .

[15]  C. Clerc,et al.  A study of the geometrical and mechanical properties of a self-expanding metallic stent--theory and experiment. , 1993, Journal of applied biomaterials : an official journal of the Society for Biomaterials.

[16]  D. Nichols,et al.  Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment , 2003, The Lancet.

[17]  Olav Jansen,et al.  Treatment of intracranial broad-neck aneurysms with a new self-expanding stent and coil embolization. , 2004, AJNR. American journal of neuroradiology.

[18]  J. Pruvo,et al.  Flow-Diverter Stent for the Endovascular Treatment of Intracranial Aneurysms: A Prospective Study in 29 Patients With 34 Aneurysms , 2010, Stroke.

[19]  Adnan H Siddiqui,et al.  Computer modeling of deployment and mechanical expansion of neurovascular flow diverter in patient-specific intracranial aneurysms. , 2012, Journal of biomechanics.

[20]  Giuseppe Vairo,et al.  Analisi del comportamento biomeccanico di stent: un approccio agli elementi finiti (in italian) - Analysis of stent biomechanics: A finite element approach , 2006 .

[21]  G. Duckwiler,et al.  Endovascular occlusion of intracranial aneurysms with electrically detachable coils: correlation of aneurysm neck size and treatment results. , 1994, AJNR. American journal of neuroradiology.

[22]  Pascal Verdonck,et al.  Virtual optimization of self-expandable braided wire stents. , 2009, Medical engineering & physics.

[23]  A. Divani,et al.  Intracranial Aneurysms: Review of Current Treatment Options and Outcomes , 2011, Front. Neur..