Investigations of flow alteration of commissural misalignment of TAVR using Particle Image Velocimetry

Due to the raising number of TAVR implantations (transcatheter aortic valve replacement), tests for durability and prevention of associated diseases are becoming increasingly important. Not only the anatomy but also the positioning of the TAVR is decisive for its clinical performance. A misalignment in the circumferential direction can influence the flow in the sinus and thus inhibit the blood supply of the coronary arteries and influence the thrombosis potential. Therefore, the modification of the flow field is investigated in this study. For the characterization of the flow fields the measuring method of digital particle image velocimetry is used. A hydraulic circulation model is used to generate physiological flow and pressure conditions. Additionally, an aortic root model with Sinus Valsalvae, which represents the implantation environment, was developed. A prototype of a TAVR was implanted aligned to the commissure lines of the native valve leaflets on the one hand, and misaligned by 60 degree to the commissure of the native valves on the other hand. By determining the velocity vector fields, it could be shown that implantation of the TAVR with a commissureal misalignment influences the flow around the leaflets. A comparison of the flow fields shows that different recirculation areas occur. This is also indicated by a comparison of the mean velocities in the sinus and the observed shear rates. The influence of the altered flow field on the thrombosis and hemolysis potential should be investigated in future studies.