Stress - strain simulations for optimising the design of shape - memory polymer based annuloplasty rings

Abstract

Shape-memory polymers are active materials that provide a mechanical response to temperature changes. They have a high capability for recovering from deformations (much greater than shown by shape-memory alloys) which combined with a lower density and cost has favoured the appearance of numerous applications for manufacturing actuators, especially for the aeronautics, automobile and medical industries. Among the medical devices under development that endorse the advantages of using these polymers, the most notable are self-expanding stents, thrombectomy devices, "intelligent" sutures, drug release devices and active catheters. On addition active annuloplasty rings, based on the properties of these materials, for treating mitral valve insufficiency are being developed by our team at Universidad Politécnica de Madrid. However current limitations related to stress recovery are restricting the industrial impact of these active polymers. We believe that using simulations tools for precisely studying how the active implant acts on the surrounding tissue can help designing new implants that benefit from the properties of shape-memory polymers. The main results of our stress-strain simulations, carried out to analyze the viability of using shapememory polymer based annuloplasty rings for reducing mitral valve annulus, are explained in this work with promising conclusions.