In-vitro investigation of the hemodynamics of the Edwards Sapien transcatheter heart valve

Abstract

Background and aim of the study: The study aim was to evaluate the hemodynamic performance of the Sapien transcatheter heart valve (THV) in the ascending aorta, and its influence on the aortic wall in an in-vitro set-up.

Methods: A two-dimensional particle image velocimetry (2D-PIV) study was conducted to evaluate the hemodynamic performance of the Edwards Sapien THV in the aortic flow field (image rate 15 Hz). The prosthesis (diameter 23 mm) was placed inside a mock aorta under pulsatile flow conditions. The velocities, shear strength, vorticity and strain rate were obtained and calculated with a fixed frequency (70 Hz) at constant stroke volume (70 ml).

Results: The Sapien THV showed a jet flow-type profile with a maximum velocity of 0.87 +/- 0.16 m/s during peak flow phase (PFP). The jet flow was surrounded by ambilateral vortices with a higher percentage of counterclockwise than clockwise vorticity (335 +/- 66/s versus 277 +/- 44.1/s), analogous to the strain rate (261 +/- 55/s for elongation versus -168 +/- 25/s for contraction). The maximum shear strength was 26,284 +/- 11,550/s2, while the point-of-interest analysis revealed a higher velocity for the bottom aortic wall compared to the upper aortic wall (0.25 +/- 0.05 m/s versus 0.30 +/- 0.04 m/s; p = 0.014). All values were lower during the acceleration and deceleration phases compared to PFP.

Conclusion: The peak flow of the Sapien THV seems to be slightly higher than that of the native aortic valve, thus imitating near-physiological conditions. That the shear strength, vorticity and strain rate were high during peak flow phase, but low during other phases, might also have an influence on the aortic wall.