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

Abstract

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 quantifies 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.

Proof of concept of FOLDAVALVE, a novel 14 Fr totally repositionable and retrievable transcatheter aortic valve

“…By using a streamlined delivery system that excludes the leaflets from stent crimping and capitalising on a design with a physiologic flow profile 13 , FOLDAVALVE holds the promise of being a durable valve with excellent haemodynamics and, due to its low profile, a reduced rate of procedure-associated bleeding.…”

Emerging Trends in Heart Valve Engineering: Part IV. Computational Modeling and Experimental Studies

“…7). 17,26,[45][46][47]64,66,68,76,77,88,91,97,98,103,130,138 However, PIV methods were mainly two dimensional until Bru¨cker introduced Stereo-PIV based on the use of two digital cameras and PIV algorithms to study the flow past artificial heart valves. 21 The testing requirements for performing stereo-PIV for characterizing the flow through mechanical heart valves has been well described by Morbiducci et al 115 Another breakthrough in PIV was the development of defocusing digital particle image velocimetry (D-DPIV).…”

“…45 This allows for a quantitative assessment of the hemolytic and thrombogenic potential of the valve design in each position of intended use. 66,82 IN VITRO CORROSION TESTING Similar to other implantable devices, heart valves are also subjected to corrosion, particularly the transcatheter heart valves that are enclosed by a metal stent. Degradation of the heart valve due to a reaction with its environment may cause catastrophic damage.…”

“…Finally, flow visualization can be accomplished by many imaging modalities, with particle image velocimetry (PIV) being a popular example. 45,66,81 By incorporating PIV, investigators can use pulsatile flows and quantify with a high degree of accuracy fluid dynamics such as shear stresses and turbulent shear stresses. 45 This allows for a quantitative assessment of the hemolytic and thrombogenic potential of the valve design in each position of intended use.…”

Emerging Trends in Heart Valve Engineering: Part II. Novel and Standard Technologies for Aortic Valve Replacement

“…5). 38 The valve is composed of a self-expanding Nitinol stent surrounding porcine or bovine pericardial leaflets. During delivery, the leaflets are kept outside of the stent and then fold back into the stent forming a trileaflet valve when the stent is expanded.…”