Comparison of performance of self-expanding and balloon-expandable transcatheter aortic valves

Objective: To evaluate the flow dynamics of self-expanding and balloon-expandable transcatheter aortic valves pertaining to turbulence and pressure recovery. Transcatheter aortic valves are characterized by different designs that have different valve performance and outcomes.

Methods: Assessment of transcatheter aortic valves was performed using self-expanding devices (26-mm Evolut [Medtronic], 23-mm Allegra [New Valve Technologies], and small Acurate neo [Boston Scientific]) and a balloon-expandable device (23-mm Sapien 3 [Edwards Lifesciences]). Particle image velocimetry assessed the flow downstream. A Millar catheter was used for pressure recovery calculation. Velocity, Reynolds shear stresses, viscous shear stress, and pressure gradients were calculated.

Results: The maximal velocity at peak systole obtained with the Evolut R, Sapien 3, Acurate neo, and Allegra was 2.12 ± 0.19 m/sec, 2.41 ± 0.06 m/sec, 2.99 ± 0.10 m/sec, and 2.45 ± 0.08 m/sec, respectively (P < .001). Leaflet oscillations with the flow were clear with the Evolut R and Acurate neo. The Allegra shows the minimal range of Reynolds shear stress magnitudes (up to 320 Pa), and Sapien 3 the maximal (up to 650 Pa). The Evolut had the smallest viscous shear stress magnitude range (up to 3.5 Pa), and the Sapien 3 the largest (up to 6.2 Pa). The largest pressure drop at the vena contracta occurred with the Acurate neo transcatheter aortic valve with a pressure gradient of 13.96 ± 1.35 mm Hg. In the recovery zone, the smallest pressure gradient was obtained with the Allegra (3.32 ± 0.94 mm Hg).

Conclusions: Flow dynamics downstream of different transcatheter aortic valves vary significantly depending on the valve type, despite not having a general trend depending on whether or not valves are self-expanding or balloon-expandable. Deployment design did not have an influence on flow dynamics.