The Effects of Positioning of Transcatheter Aortic Valves on Fluid Dynamics of the Aortic Root

Transcatheter aortic valve implantation is a novel treatment for severe aortic valve stenosis. Due to the recent use of this technology and the procedural variability, there is very little data that quantify the hemodynamic consequences of variations in valve placement. Changes in aortic wall stresses and fluid retention in the sinuses of Valsalva can have a significant effect on the clinical response a patient has to the procedure. By comprehensively characterizing complex flow in the sinuses of Valsalva using digital particle image velocimetry and an advanced heart-flow simulator, various positions of a deployed transcatheter valve with respect to a bioprosthetic aortic valve (valve-in-valve) were tested in vitro. Displacements of the transcatheter valve were axial and directed below the simulated native valve annulus. It was determined that for both blood residence time and aortic Reynolds stresses, it is optimal to have the annulus of the transcatheter valve deployed as close to the aortic valve annulus as possible. Copyright © 2014 by the American Society for Artificial Internal

Haemodynamic Issues with Transcatheter Aortic Valve Implantation

Transcatheter aortic valves are typically implanted inside the native (or failed bioprosthetic’s) leaflets, permanently forcing the old leaflets open into a pseudo-cylindrical condition. Due to the passive nature of heart valves, the dynamics of the surrounding fluid environment is critical to their optimum performance. Following intervention, the haemodynamics of the region would ideally be returned to their healthy, physiological state, but major alterations are currently inevitable, such as increased peak flow velocity, the presence of stagnation regions, and increased haemolytic fluid environments. These leaflets reduce the volume of and restrict the flow into the Valsalva’s sinuses, and minimise the development of vortices and associated flow structures, which would aid washout and valve closure. Despite these differences to the healthy condition, implantation of these devices offers much improved flow from that of a moderately stenotic valve, with reduced transvalvular systolic pressure drop, peak blood velocity, and shear stress, which normally outweighs the disadvantages highlighted above, especially for high-risk patients