Abstract
Abstract The implantation of transcatheter aortic valve prostheses (TAVP) for therapy of aortic valve stenosis shows more and more clinically non-inferiority results compared to surgical valve replacement in intermediate and low risk patients. Commonly clinically used TAVP are manufactured from chemically fixed xenograft leaflet material, e.g. bovine or porcine pericardium. While the clinical use of TAVP currently extends, challenges concerning valve durability and leaflet calcification have to be addressed. In this regard, artificial leaflet materials represent a promising option for a next generation of TAVP. As a first step for the development of TAVP from polymeric nonwoven, the aim of this study was to determine the influence of leaflet geometry on hydrodynamic performance of TAVP prototypes. Based on a parametric model of the valve leaflets, we varied the curvature of the belly line forming the leaflet coaptation area from an initial, quite concave, leaflet geometry with a value of 0.5° to an almost straight geometry for the leaflets with a value 0.15°. Manufacturing of TAVP prototypes was conducted by means of electrospinning technique with a polycarbonate based silicone elastomer. Hydrodynamic characterization according to ISO 5840-3 standards was performed using a pulse duplicator system with a heart rate of 70 BPM, systolic duration of 35%, mean aortic pressure of 100 mmHg and a stroke volume of 96 ml. Cardiac output as well as mean transaortic pressure gradient, closing volume, leakage volume and regurgitation were measured to compare the different leaflet geometries. To summarize, the curvature of the leaflets’ belly has a crucial impact on TAVP hydrodynamics under physiological test conditions. In particular, the opening and closing behavior is strongly influenced by a steeper curvature leading to larger closing volumes and higher regurgitant fractions. Further studies are planned to identify an optimum with respect to leaflet material selection, leaflet geometry and hydrodynamic properties of TAVP.
Highlights
Transcatheter aortic valve implantation (TAVI) has become the treatment of choice for inoperable or high-risk patients with symptomatic aortic valve stenosis [1]
The transcatheter aortic valve prostheses (TAVP) prototypes were implanted into silicone rings by hand without loading and release from a delivery catheter system and hydrodynamic in vitro testing according to ISO 58403:2103 was performed
In the following we describe the influence of valve geometry on the opening and closing behavior and the characteristic hydrodynamic properties of the TAVP prototypes
Summary
Transcatheter aortic valve implantation (TAVI) has become the treatment of choice for inoperable or high-risk patients with symptomatic aortic valve stenosis [1]. Challenges concerning valve durability and leaflet calcification have to be addressed when thinking about implanting TAVP into younger patient collectives [3]. As well as non-calcific tissue degeneration, is synergistically leading to bioprosthetic failure, no matter if a surgical valve prosthesis (SVP) or TAVP was used for implantation [4]. In this regard, artificial leaflet materials such as polymers represent a promising option for a generation of SVP or TAVP with extended durability [5]. The introduction of the electrospinning technique to fabricate polymeric nonwoven structures led to an upsurge in the field of polymeric heart valve development [7, 8]
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