Abstract
Abstract To assess the hydrodynamic performance of transcatheter aortic valve prostheses (TAVP), in vitro test using pulse duplicators is required. Test conditions as well as minimum performance criteria are specified in ISO 5840- 3:2013 and ISO 5840-3:2019-draft. In the 2019 published draft, modifications regarding hydrodynamic testing are proposed. Among others, the geometrical configuration of the fixation has changed, with the intention to improve the anatomical representation as well as the comparability of results from different test laboratories. We analyzed the consequences of altered annulus fixations regarding native leaflets as well as a step in the proximal area of the protheses to prevent their migration. The analyses were conducted with regard to the degree of calcification of the annulus ring on hydrodynamic parameters. By using 3D stereolithography printing technology, molds for casting of silicone elastomer of annulus models with and without native leaflets were manufactured. A modular system enabled us to use the same annulus ring to model the degree of calcification as well as different step sizes. We performed in vitro hydrodynamic testing according to ISO 5840-3:2019-draft of a selfexpandable valve prototype with porcine pericardial leaflets by using a commercially available pulse duplicator system. As expected, regurgitation increases with increasing degree of calcification, whereby the use of a step has no influence on the backflow of fluid during diastole. The effective orifice area (EOA) of the valve showed a clear tendency with respect to radial protrusion of the step. The EOA decreased as the radial protrusion increased. We also present a suggestion to prevent migration without affecting the general test results, by using a novel step design. We also found that the novel annulus model with native leaflet drastically reduced the regurgitation.
Highlights
Transcatheter heart valve prostheses (TAVP) are used to treat valve stenosis and insufficiency
In order to predict the clinical performance of the TAVP, their hydrodynamic characteristics are tested in vitro by using pulse duplicator systems
The fixation, called aortic fixture or annuls model, is intended to mimic the anatomical features of the human annulus region. This includes the implantation diameter, the annulus thickness and leaflet geometry. Comparing to the former aortic fixture design, the novel design differs in modelling a native leaflet configuration as well as a nodule as pathological alteration caused by plaque or calcification
Summary
Transcatheter heart valve prostheses (TAVP) are used to treat valve stenosis and insufficiency. In order to predict the clinical performance of the TAVP, their hydrodynamic characteristics are tested in vitro by using pulse duplicator systems. Pulse duplicator systems simulate the left heart circulatory system with clinically relevant pulsatile characteristics These testing systems are wellestablished and are accepted as gold standard for in vitro hydrodynamic performance characterization [2]. The fixation, called aortic fixture or annuls model, is intended to mimic the anatomical features of the human annulus region. This includes the implantation diameter, the annulus thickness and leaflet geometry. Jan Oldenburg et al, Impact of aortic annulus geometry according to ISO 5840:2019 (draft) on hydrodynamic performance of transcatheter aortic valve prostheses — 2 occur. A customized anti-migration step was designed and manufactured, see Figure 2
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