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

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