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.