Anagrafe della ricerca

The problem Lower limb peripheral artery disease (PAD) is an atherosclerotic disease that causes severe complications such as leg ulceration, gangrene and amputation. PAD affects more than 230 million people worldwide. Its prevalence is expected to dramatically increase, fueled by the aging population and the surge in diabetes and obesity in developed countries. Endovascular procedures - in particular, the implantation of self-expanding Nickel-Titanium (NiTi) stents - represent the most recurrent treatment solution due to the low morbidity and rapid recovery they offer, with an estimated rise of the global PAD stent market from $3.5bn (2021) to $5.3bn (2028). Self-expanding NiTi stents elastically resume their initial shape after being released from the catheter and accommodate the multiple cyclic deformation modes characterizing femoral arteries. Despite the wide use of stents, failure rates are unacceptably high. In-stent restenosis (ISR), which progressively leads to lumen re-narrowing, remains the main limitation, with incidence rate of ~15-32%. The challenge ISR is promoted by systemic, biological and biomechanical factors. Significant research efforts have been made to improve the stent design and biomechanical behavior in order to reduce ISR incidence. In particular, computational simulations have been used as an efficient tool to characterize and optimize the stent design, with great returns in terms of time and costs. To date, several computational frameworks based on structural mechanics simulations have been proposed to optimize the stent mechanical performance, but without complete success. Hence, new design tools are being sought to improve the device performance. In this context, topology optimization (TO) is an attractive approach, as it can optimize the device design with respect to a given performance index under a set of loads and constrains. However, TO has been rarely used to design stents. The solution The RESET project aims to develop a computational framework based on TO for the design of innovative femoral artery stents with improved mechanical and fluid dynamic features for providing enhanced treatment of lower limb PAD. RESET objectives are: i) defining new 2D stent cells by multiphysics (i.e. structural mechanics and fluid dynamics) TO; ii) creating new 3D stent designs based on the optimized obtained 2D cells and NiTi material properties selected by material optimization process; iii) assessing the manufacturability and biomechanical performance of the developed stents using computer simulations validated by in vitro tests. The RESET solution can support stent manufactures during the pre-clinical assessment phase, enabling the creation of improved devices with potentially superior clinical outcomes. This may ultimately result in a more sustainable healthcare system and in the improvement of the patient quality of life, social inclusion and productivity.