Novel 3D-printed Aortic Valves Made From Silicone - A Computational Study Of Valve Performance
Pascal Corso1, Fergal B. Coulter2, Maria G. Ch. Nestola3, André R. Studart2, Dominik Obrist1.
1University of Bern, Bern, Switzerland, 2ETH Zurich, Zurich, Switzerland, 3Università della Svizerra italiana, Lugano, Switzerland.
OBJECTIVE - Improving artificial valve design is of paramount importance considering that they still present several limitations as to their haemodynamic performance and durability. A new technology using additive manufacturing has been recently developed to produce customised bioinspired valves made from silicone. In this study, we intend to investigate the influence of the leaflet shape and the manufacturing material on the leaflets’ motion as well as on flow turbulence. METHODS - The study relies on the numerical simulations of the coupled blood and valve motion based on (i) a finite-element formulation for the elastodynamics equation, (ii) a high-order finite-difference formulation for the Navier-Stokes equations, (iii) a variational approach for the transfer of information between the fluid and the structure. The leaflets’ constitutive relations are the Holzapfel-Gasser-Ogden (HGO) model fitted to match bovine pericardium data and the hyperelastic Mooney-Rivlin model fitted to match silicone stress-strain curves. RESULTS - The comparison of the vortical structures in the flow between a model of an Edwards Intuity Elite bioprosthetic aortic valve (BAV) and a new model of 3D-printed valve shows that the vortical intensity is higher when silicones stiffer than the pre-treated bovine pericardial tissue are used. We also note from the Figure that even though the effective orifice area (EOA) is about 10% narrower during the opening phase for the valve made from silicone, the trilobal EOA is still 50% larger than the triangular EOA simulated for the BAV. Finally, it is shown from the graph that unlike changes in the shape of the leaflets, changes in the material properties do not play a determinant role in suppressing the fluttering motion. CONCLUSIONS - This work brings new insights on the performance of novel 3D-printed valves from advanced analyses of computational simulation results. 
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