Abstract
Abstract The loading situation of the aortic valve is complex, complicating the identification of innovative approaches for heart valve leaflet materials, e.g. for transcatheter aortic valve implantation (TAVI). Materials engineering experiments allow for screening of materials but especially for durability testing, the consideration of physiological loads is vital/critical for the suitability-assessment of innovative leaflet materials. For this reason, a framework structure for the testing of leaflet materials in physiological loading (TAVI-Mimic) was developed. The exemplary use case for the TAVI-Mimic was a test for calcification propensity of pericardium during durability testing. The TAVI-Mimic was designed as a fourparted frame, based on previous work of our group. The leaflet material can be attached between inner and outer shells without sewing. In a second step, the TAVI-Mimic was optimized regarding radial load-deformation in comparison to a commercial TAVI by means of finite element analysis (FEA) and hydrodynamic characterization in a pulse duplicator system. Mechanical properties dependent on water uptake of different materials for 3D-printing of the TAVI-Mimic were investigated. After optimization, TAVI-Mimics were equipped with glutaraldehyde-fixated pericardial tissue and prototypes were calcified by using a heart valve durability tester and a metastable calcification-liquid, developed in earlier studies. The development of the TAVI-Mimic using FEA and experiments was successful, leading to a radial load dependent deformation of 0.6 mm which correlates with commercial TAVI. Two methacrylic photopolymers were identified for 3D-printing of the TAVI-Mimic and prototypes attached with pericardial tissue were manufactured. Pericardium TAVI-Mimics were calcified in vitro for one week and an average calciumphosphate precipitate of 0.34- 0.54 mg/cm² was measured. The optimization of the TAVR-Mimic led to an improved load-dependent behaviour compared to a commercial prosthesis while testing. The calcification method, combining the TAVI-Mimic, the metastable calcification solution and the durability tester enabled a successfully calcification of pericardial tissue, approaching the in vivo situation.
Highlights
Clinical studies like the PARTNER 2A and the Sapien 3 have confirmed that transcatheter aortic valve implantation (TAVI) shows superior results compared to aortic valve surgery applied at patients who belonging to a medium risk or younger age group [1]
The hydrodynamic testing of the existing TAVI-Mimic using a pulse duplicator system resulted in a value of 0.03 ± 0.05 mm for the radial load dependent deformation
With the applied optimization steps, the TAVI-Mimic became more elastic and the radial load dependent deformation was adapted to physiological loading conditions
Summary
Clinical studies like the PARTNER 2A and the Sapien 3 have confirmed that TAVI shows superior results compared to aortic valve surgery applied at patients who belonging to a medium risk or younger age group [1]. Newly developed the transcatheter aortic valve prostheses (TAVP), currently designed for a lifetime of at least ten years, have to last much longer than this period. Previous investigations showed that the type and the velocity of the calcification process depend on material stress during the cyclic valve opening-closing processes [2, 3]. For this reason, when developing generation TAVP with increased durability for a time period longer than ten years it is necessary to at least screen innovative leaflet materials concerning calcification tendency and in a step develop anti-calcification-strategies to inhibit future valve restenosis. Material screening is an iterative process; it is not suitable to manufacture a TAVP at any time
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
