Durability of Nickel-Titanium endovascular devices for peripheral applications

Nickel-Titanium belongs to the shape memory alloys and it is widely used in many biomedical fields. Its temperature dependent property of pseudo-elasticity allows to design self-expandable devices, highly convenient for mini-invasive deployments. Peripheral stents are subjected in vivo to a complex state of cyclic solicitations due to blood pulsation and leg movements, which may induce weakening in the material and fatigue failure. The role of stent fracture, which can influence in-stent restenosis, is nowadays under investigation. Several computational modelling approaches have been proposed to understand the interaction between stent and vessel during leg movements, while others studied the local response of the stent disregarding the global biomechanical environment. In this paper, a multiscale numerical approach, also coupled with some experiments, is proposed with the aim of considering all the factors influencing the performance of a peripheral stent and offering good results in terms of fracture predictability.