Development and validation of a numerical model for the investigation of transcatheter aortic valve implantations

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Transcatheter aortic valve implantation is a minimal-invasive alternative for high-risk patients with severe aortic stenosis when open-heart surgery carries to much risk. Because of missing long-term experience and existing complications during and after the intervention, this rather new approach is not a replacement of the classic surgical procedure. Paravalvular aortic regurgitation due to malposition of the prosthesis is the most frequent complication. Current studies, however, are only based on empirical data of clinical outcomes.The aim of this project is the development and experimental in-vitro validation of a novel simulation model which makes the systematic study of potential complications possible. One of the main tasks is the modeling of the fluid-structure-interactions of the blood flow and the heart valve leaflets. An extensive numerical analysis of the mesh, the material properties, the boundary conditions, the coupling and the turbulence are indispensable with respect to accuracy and stability of the solution process. For this purpose, in vitro tests are performed to validate the numerical model and make adjustments as needed. By using the validated simulation model, the effects of malpositioning of the prosthesis can subsequently be evaluated. Patient specific geometries of the heart and surrounding vessels are created based on medical imaging data from patients suffering from severe aortic stenosis. The prosthesis is virtually implanted at different locations. The sensitivity of the implantation site on paravalvular leakage is evaluated in close cooperation with a clinical partner. The long-term aim of this research project is the development of a methodology that objectifies the decision making of the doctors in charge about possible strategies of the intervention (e.g. choice of implantation site and prosthesis size) in order to optimize the outcome of the treatment.