An in vitro evaluation of the impact of eccentric deployment on transcatheter aortic valve hemodynamics

Abstract

Patients with aortic stenosis present with calcium deposits on the native aortic valve, which can result in nonconcentric expansion of Transcatheter Aortic Valve Replacement (TAVR) stents. The objective of this study is to evaluate whether eccentric deployment of TAVRs lead to turbulent blood flow and blood cell damage. Particle Image Velocimetry was used to quantitatively characterize fluid velocity fields, shear stress and turbulent kinetic energy downstream of TAVRs deployed in circular and eccentric orifices representative of deployed TAVRs in vivo. Effective orifice area (EOA) and mean transvalvular pressure gradient (TVG) values did not differ substantially in circular and eccentric deployed valves, with only a minor decrease in EOA observed in the eccentric valve (2.0 cm2 for circular, 1.9 cm2 for eccentric). Eccentric deployed TAVR lead to asymmetric systolic jet formation, with increased shear stresses (circular = 97 N/m2 vs. eccentric = 119 N/m2) and regions of turbulence intensity (circular = 180 N/m2 vs. eccentric = 230 N/m2) downstream that was not present in the circular deployed TAVR. The results of this study indicate that eccentric deployment of TAVRs can lead to altered flow characteristics and may potentially increase the hemolytic potential of the valve, which were not captured through hemodynamic evaluation alone. © 2014 Biomedical Engineering Society.