Finite Element Stent Modeling for the Postoperative Analysis of Transcatheter Aortic Valve Implantation

In order to evaluate the performance of stents used in transcatheter aortic valve implantation (TAVI), finite element simulations are setup to reconstruct patient-specific contact forces between implant and its surrounding tissue. Previous work used structural beam elements to setup a numerical model of the CoreValve stent used in TAVI and developed a procedure for implementing kinematic boundary conditions from noisy computer tomography (CT) scanning data. This study evaluates element size selection and quantitatively investigates the choice of a linear elastic constitutive model for the Nitinol stent under physiological loading conditions. It is shown that this simplification leads to reliable results and enables a huge reduction in computation time. Further, the procedure used to compensate for noisy postoperative CT data is tested by adding artificial noise. It is concluded that for physiologically relevant loading ranges, the procedure yields convergent results and successfully eliminates the influence of the noise.