Valve-in-Valve Deployment and its Effect on Leaflet Thrombosis – A Biomechanical Numerical Model

Valve-in-valve (ViV) placement is an emergent treatment option for degenerated bioprosthetic aortic valves where a transcatheter aortic valve (TAV) is implanted inside the failed surgical valve. Reduced leaflet motion as a result of hypo-attenuated leaflet thickening (HALT) was recently diagnosed by high-resolution CT scans in bioprosthetic aortic valves in general, with highest occurrence after ViV placement. Leaflets thrombosis, as a result of flow stagnation near the leaflets due to valve confinement, was suggested as the cause. Only complete or no confinements, where the TAV valve is surrounded by surgical leaflets, were accounted for in previous studies of HALT post-ViV. This research aims to explore and compare deployments of the latest version of TAV devices inside a surgical bioprosthetic valve and to assess the partial confinement influence on the hemodynamics near the ViV’s region. To simulate ViV procedure, deployments of latest generation transcatheter valve devices in a surgical valve were modeled by finite element analysis. The percentage of leaflets confinement was calculated. Complete confinement was found after intra-annular deployment while partial confinement was found after supra-annular deployment, creating a pocket with 60.3% of the leaflet size. These “pockets” are suspected as regions of flow stagnation that can lead to thrombus formation. Partial confinement configuration can help evaluating the risks for leaflets thrombosis in various deployment locations. The post-procedural configurations are now being used for hemodynamic models of the flow through them and will be solved by fluid structure interaction analysis.