Crimping Process Investigation to Enable Informed Design of 3D Printed Bioresorbable Vascular Scaffolds

With cases of coronary and peripheral artery disease on the rise, vascular stenting has become a popular procedure which is crucial to the health of millions of patients across the United States and more across the globe. In the past several decades, the field has seen a shift from bare metal and metal drug eluting stents to bioresorbable vascular scaffolds (BVS) with the goal of addressing restenosis, thrombosis, and stent migration concerns. These BVS utilize polymeric materials to degrade over time <i>in vivo</i>, and as a result, have drastically different mechanical responses to deformation than the preceding metal stents. As such, additional consideration of the BVS mechanical deformation response both prior to and post-deployment is important to enhancing the performance of these polymeric scaffolds <i>in vivo</i>. The crimping process, or diameter reduction of the stent or BVS prior to deployment, marks the first time after manufacturing that the scaffold must undergo a significant amount of mechanical deformation. As it is also an easy deformation step to monitor, crimping serves as a good baseline for understanding the mechanical response of BVS. Simulation of this step can not only provide information on BVS radial force as a function of diameter to mimic results from experimental testing, but can also give additional information on the response of the BVS as it undergoes this deformation in a fraction of the time required in experiment. This allows for a time-effective solution to enable understanding of both the deformation of different scaffold designs and the deformation of scaffolds with different material additives incorporated, like those utilized to enable visibility of the BVS when imaged <i>in vivo</i>. Here, we utilize a finite element crimping simulation in ABAQUS to rapidly reproduce experimentally validated qualitative design comparisons between several designs of 3D printed bioresorbable vascular scaffolds made of a previously developed citrate-based polymer, taking into consideration both the properties of the base polymeric material and the properties of the polymeric material with a radiopaque additive. By doing so, it is possible to harness the advantages of additive manufacturing to allow for more optimal bioresorbable vascular scaffold design and production, simultaneously elucidating the relationship between material, structure, and mechanical response of scaffolds.