Leaflet Kinematics Of Novel Fully Polymeric Heart Valves
Caroline C. Smid1, Georgios A. Pappas1, Volkmar Falk2, Nikola Cesarovic3, Paolo Ermanni1.
1CMASLab ETH Zurich, Zurich, Switzerland, 2Deutsches Herzzentrum Berlin, Klinik für Kardiovaskuläre Chirurgie, Charité Universitätsmedizin Berlin, Berlin, Germany, 3Translational Cardiovascular Technologies, ETH Zürich, Zurich, Switzerland.
BACKGROUND: Despite decades of research, it remains challenging for artificial heart valves to match hemodynamic and durability of their native counterparts. Given that the available materials that resemble the compliance of the natural leaflet tissue have limited durability, we are investigating potentially more durable, higher stiffness (up to 300 times) materials. Thus, the objective of this study is to evaluate and propose the route for engineering leaflet designs instead of making them biomimetic.
METHODS: Six different aortic leaflet designs are investigated in a semi-experimental approach with lean simulations and their performance was compared. The first design (reference) is mimicking a natural leaflet shape while the others are novel designs with varying geometries. All designs are investigated for both soft polyurethane leaflets (13.3 MPa, tissue equivalent) and a thickness of 150 μm as a baseline, as well as stiff leaflets (2.5 - 4.4 GPa) and a thickness of 33 μm. The various leaflet designs are initially evaluated with a rigid exemplary stent (inner diameter of 21.8 mm). Hydrodynamic tests are conducted with an in-house pulse duplicator, which provides the pressure and flow tracing as well as the orifice area measurement over a full cardiac cycle. Moreover, simulations using finite element analysis were performed where a uniform pressure is applied to the ventricular side of the leaflets, yielding the orifice area over the applied pressure. RESULTS: Simulations showed that proposed new leaflet designs, especially with the stiff leaflets, open at a significantly lower pressure than the reference design. However, a smaller maximum orifice area (about 9% for soft and 20% for stiff leaflets) is found for the new designs. Similar trends could be confirmed in the pulse duplicator experiments. These results suggest that the new designs have higher responsiveness attributed to reduced flexural stiffness (for the given stiff material) and that the orifice area is mainly shape-dependent and has a rather low stiffness dependence.
CONCLUSIONS: This study yields promising valve leaflet designs tailored to new materials that could fulfill both hemodynamic and durability requirements. Moreover, non-biomimetic designs increase the design space and have a lot of potential, particularly for atrioventricular valves.
Back to 2023 Abstracts