Influence of TAVR-dilatation concepts on hydrodynamic properties under pulsatile flow

Abstract Transcatheter aortic valve implantation (TAVI) for aortic valve stenosis can be seen as a disruptive technology that has become the standard treatment for previously inoperable patients over the past 15 years. A key component of the development process for new transcatheter aortic valve replacements (TAVR) is the hydrodynamic testing as part of real-time functional testing. Although, fundamental requirements, necessary testing methods, as well as functional environments, physiological and pathophysiological stress situations, are defined, resulting testing parameter ranges are only estimated. For this reason, two clinically established TAVR were tested in different parameter settings representing different characteristic load situations on a patient. In fact, the two TAVR with different dilatation concepts were tested under different cardiac outputs (CO) and the resulting effective orifice area (EOA), the closing and the leakage volume was measured and evaluated according to ISO 5840-3:2021. Regarding the two TAVR designs, it can be shown that the high radial force of the Lotus Valve contributes to an improvement in the sealing effectiveness of the TAVR. This is because the annulus can be pushed outward by the stent resulting in a better fit between the TAVR and the vessel wall. Additionally, the lamellar skirt of the Lotus Valve also appears to contribute to improved sealing. In the presented experiments, the smooth abluminal- mounted pericardial skirt of the Evolut PRO bioprosthesis does not seem to contribute to additional sealing. The developed test procedure aims to contribute to the establishment of new in vitro standards. Future work must involve applying the testing methods to additional clinically established TAVR as well as new developments.