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Projekt Druckansicht

Entwicklung und Validierung eines numerischen Modells zur Untersuchung von Transkatheter-Aortenklappenimplantationen

Fachliche Zuordnung Medizinische Physik, Biomedizinische Technik
Förderung Förderung von 2014 bis 2021
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 237767598
 
Erstellungsjahr 2022

Zusammenfassung der Projektergebnisse

Aortic valve diseases, especially aortic stenosis, is an increasing issue in the elderly population. One treatment option is the minimally invasive implantation of a transcatheter heart valve prosthesis by means of a catheter. The goal of the project was to develop a fully coupled fluid structure interaction model to analyse the flow field behind the heart valve prosthesis. In the scope of the project an innovative computational model was developed that can be applied to any prosthesis design to study the resulting flow field. The main novelty of the project is the development of a fully coupled ICFD FSI model for the transcatheter aortic CoreValve prosthesis. This goes beyond the state of the art, which uses mostly the ALE FSI method for modelling of the aortic flow. Unfortunately, this ALE method has limitations. First, the fluid mesh size plays an important role in the size of the velocity gradient. This method does not account for the boundary layer effect and as result, the velocity gradient is strongly dependent on the mesh size, e.g. a larger mesh size results in a larger gradient area and a smaller mesh size in a smaller area. Second, the stent of the prosthesis was excluded in the FSI simulations due to much higher computational costs. Third, the ALE approach need to be modelled with hexahedral elements. Unfortunately, the patient’s anatomy models are modelled with triangular elements, which are incompatible to this approach. The fully coupled ICFD FSI approach looks very promising in modelling the flow in detail, because smaller mesh sizes can be used. This leads to a high resolution velocity field, where small backflow areas and vortices can be seen. Unfortunately, as the volume fluid mesh is built from the surface meshes, the cost of building high quality meshes is high. As this method is relatively new, some issues with the solver versions occurred and a developer version was used, which fixed some problems. Some limitations remained as only a zero pressure boundary condition could be applied at the outlet. Further, only the RANS turbulence model worked with this solver. The stent was also excluded from the simulation due to enormous computational costs. The boundary layer mesh at the aortic wall could not be used as in the small gap between skirt and aortic wall would occur high leakage flow. Future work will include patient-specific simulations including the geometries in WP3 and considering calcification patterns, neo-sinus washout and the effect of implant height on paravalvular leakage and coronary flow.

Projektbezogene Publikationen (Auswahl)

 
 

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