Impact of aortic root geometry on hydrody-namic performance of transcatheter aortic valve prostheses

Abstract

Assessment of hydrodynamic performance of transcatheter aortic valve prostheses (TAVP) in vitro is essentially in the fields of development and approval of novel implants. For the prediction of clinical performance, in vitro testing of TAVP allows for benchmarking of different devices, likewise. In addition to the implant itself, also the testing environment has a crucial influence on leaflet dynamics and quantitative test results like effective orifice area (EOA) or aortic regurgitation.Therefore, within the current study we developed simplified physiological and pathophysiological vessel models of the aortic root as a tool for in vitro hydrodynamic testing of TAVP in idealized and worst case conditions. We used 3D printing and silicone cast molding for manufacturing of aortic root models with variable degree of stenosis. Design of aortic roots with normal, mild and severe stenosis was developed according to Reul et al. For manufacturing of tripartite casting molds, a 3D printer was used. Both outer mold parts and the mold core were manufactured from polylactide filament and water soluble polyvinylalcohol filament, respectively. In vitro hydrodynamic performance testing of an exemplary commercially available TAVP implanted in different aortic root models was conducted according to DIN EN ISO 5840-3:2013, using a pulse duplicator system.Manufactured aortic root models were highly transparent, dimensionally stable and therefore suitable for hydrodynamic testing of TAVP. Both, EOA and regurgitant fraction increased with increasing degree of stenosis from 1.6 ± 0.1 cm² to 1.8 ± 0.1 cm² and 8.6 ± 6.5% to 20.2 ± 4.2% (n = 30 cycles), respectively.We successfully developed a testing environment enabling sophisticated evaluation of hydrodynamic performance of TAVR in pathophysiological worst case conditions.