Gradient and pressure recovery of a self-expandable transcatheter aortic valve depends on ascending aorta size: In vitro study

Objective: In this study we aimed to understand the role of interaction of the Medtronic Evolut R transcatheter aortic valve with the ascending aorta (AA) by evaluating the performance of the valve and the pressure recovery in different AA diameters with the same aortic annulus size. Methods: A 26-mm Medtronic Evolut R valve was tested using a left heart simulator in aortic root models of different AA diameter (D): small (D = 23 mm), medium (D = 28 mm), and large (D = 34 mm) under physiological conditions. Measurements of pressure from upstream to downstream of the valve were performed using a catheter at small intervals to comprehensively assess pressure gradient and pressure recovery. Results: In the small AA, the measured peak and mean pressure gradient at vena contracta were 11.5 ± 0.5 mm Hg and 7.8 ± 0.4 mm Hg, respectively, which was higher (P \u3c .01) compared with the medium (8.1 ± 0.4 mm Hg and 5.2 ± 0.4 mm Hg) and large AAs (7.4 ± 1.0 mm Hg and 5.4 ± 0.6 mm Hg). The net pressure gradient was lower for the case with the medium AA (4.1 ± 1.2 mm Hg) compared with the small AA (4.7 ± 0.8 mm Hg) and large AA (6.1 ± 1.4 mm Hg; P \u3c .01). Conclusions: We have shown that small and large AAs can increase net pressure gradient, because of the direct interaction of the Medtronic Evolut R stent with the AA (in small AA) and introducing higher level of turbulence (in large AA). AA size might need to be considered in the selection of an appropriate device for transcatheter aortic valve replacement

Neosinus and Sinus Flow After Self-Expanding and Balloon-Expandable Transcatheter Aortic Valve Replacement

OBJECTIVES: The aim of this study was to evaluate flow dynamics in the aortic sinus and the neosinus (NS) after transcatheter heart valve (THV) implantation in valve-in-valve (ViV). BACKGROUND: Leaflet thrombosis may occur on THVs and affect performance and durability. Differences in flow dynamics may affect the risk for leaflet thrombosis. METHODS: Hemodynamic assessment following THV implantation in a surgical aortic valve was performed in a left heart simulator under pulsatile physiological conditions. Assessment was performed using a 23-mm polymeric surgical aortic valve (not diseased) and multiple THV platforms, including self-expanding devices (26-mm Evolut, 23-mm Allegra, small ACURATE neo) and a balloon-expandable device (23-mm SAPIEN 3). Particle image velocimetry was performed to assess flow in the sinus and NS. Sinus and NS washout, shear stress, and velocity were calculated. RESULTS: Sinus and NS washout was fastest and approximately 1 cardiac cycle for each with the Evolut, ACURATE neo, and Allegra compared with the SAPIEN 3, with washout in 2 and 3 cardiac cycles, respectively. The Allegra showed the largest shear stress distribution in the sinus, followed by the SAPIEN 3. In the NS, all 4 valves showed equal likelihoods of occurrence of shear stress \u3c1 Pa, but the Allegra showed the highest likelihoods of occurrence for shear stress \u3e1 Pa. The velocities in the sinus and NS were 0.05, 0.078, 0.080, and 0.075 m/s for Evolut, SAPIEN 3, ACURATE neo, and Allegra ViV, respectively. CONCLUSIONS: Sinus and NS flow dynamics differ substantially among THVs after ViV. Self-expanding supra-annular valves seem to have faster washouts compared with an equivalent-size balloon-expandable THV