Simulated Transcatheter Aortic Valve Flow- Implications of Elliptical Deployment and Under‐Expansion at the Aortic Annulus.pdf

<div>Clinical use of transcatheter aortic valves</div><div>(TAVs) has been associated with abnormal deployment,</div><div>including oval deployment and under-expansion when</div><div>placed into calcified aortic annuli. In this study, we performed an integrated computational and experimental</div><div>investigation to quantify the impact of abnormal deployment</div><div>at the aortic annulus on TAV hemodynamics. A size</div><div>23 mm generic TAV computational model, developed and</div><div>published previously, was subjected to elliptical deployment</div><div>at the annulus with eccentricity levels up to 0.68 and</div><div>to under-expansion of the TAV at the annulus by up to</div><div>25%. The hemodynamic performance was quantified for</div><div>each TAV deployment configuration. TAV opening geometries were fabricated using stereolithography and then subjected to steady forward flow testing in accordance</div><div>with ISO-5840. Centerline pressure profiles were compared to validate the computational model. Our findings</div><div>show that slight ellipticity of the TAV may not lead to</div><div>degeneration of hydrodynamic performance. However,</div><div>under large ellipticity, increases in transvalvular pressure</div><div>gradients were observed. Under-expanded deployment has</div><div>a much greater negative effect on the TAV hemodynamics</div><div>compared with elliptical deployment. The maximum turbulent</div><div>viscous shear stress (TVSS) values were found to be</div><div>significantly larger in under-expanded TAVs. Although</div><div>the maximum value of TVSS was not large enough to</div><div>cause hemolysis in all cases, it may cause platelets activation, especially for under-expanded deployments.</div>