Sinus Hemodynamics Variation with Tilted Transcatheter Aortic Valve Deployments

Abstract

Leaflet thrombosis is a complication associated with transcatheter aortic valve (TAV) replacement (TAVR) correlated with sinus flow stasis. Sinus hemodynamics are important because they dictate shear stress and washout necessary to avoid stasis on TAV leaflets. Sinus flow is controlled by TAV axial deployment position but little is known regarding TAV axis misalignment effect. This study aims to elucidate TAV angular misalignment with respect to aortic root axis effect on sinus flow stasis potentially leading to leaflet thrombosis. Sinus hemodynamics were assessed in vitro using particle-image velocimetry in three different angular misalignments with respect to aorta axis: untilted, tilted away from the sinus and tilted towards sinus. A 26 mm Edwards SAPIEN3 was implanted in a 3D printed model of an anatomically realistic aortic root. TAV hemodynamics, sinus vortex tracking, leaflet shear stress probability density functions, and sinus blood time to washout were calculated. While pressure gradients differed insignificantly, blood velocity and vorticity decreased significantly in both tilted cases sinuses. Shear stress probability near the leaflet decreases with tilt indicating stasis. TAV tilted away from the sinus is the most unfavorable scenario with poor washout. TAV axial misalignment adds to factors list that could influence leaflet thrombosis risk through modifying sinus hemodynamics and washout.

Development of Tissue Engineered Heart Valves for Percutaneous Transcatheter Delivery in a Fetal Ovine Model

“…A hemodynamic evaluation of the prototype TEHV was performed using a dedicated right heart pulse duplicator, similar to previous studies ( 15 , 16 , 17 ). Briefly, the pulse duplicator was composed of a reservoir to mimic atrial function, a bladder pump controlled by compressed air to simulate ventricular function, and a mechanical valve between the reservoir and the pump that functioned as an atrioventricular valve.…”

“…The cardiac output was set at 0.5 l/min with a pulmonary artery pressure of 28/4 mm Hg, and the heart rate was set at 90 beats/min ( 18 , 19 , 20 ). One hundred consecutive cycles of flow rate and transvalvular pressure gradient (PG), measured using pressure transducers (Validyne Engineering Corp., Northridge, California), were acquired at a sampling frequency of 100 Hz, in accordance with previous studies ( 16 , 21 , 22 ). From these data, common measures of in vitro valve performance, including effective orifice area (EOA), regurgitant fraction (RF), and pinwheeling index, were computed.…”

Principles of TAVR valve design, modelling, and testing

“…ISO 5840–3 N.4.3.5 outlines the need for characterizing the THV flow field which has been extensively developed in literature with digital particle image velocimetry (DPIV) [40, 61, 62, 63, 64, 65, 102, 103, 104, 105, 106, 107, 108]. DPIV allows quantitative analysis of the flow field velocity, shear and particle residence times, which are critical for predicting risks of thrombosis (Figure 7).…”

“…The results show increased shear stresses and increased turbulence which may influence hemolysis, which cannot be characterized by traditional hydrodynamics. Studies of sinus stasis times, or particle residence times in the aortic sinus are often performed with DPIV experiments [61, 63, 65, 102, 104, 105, 107]. These studies commonly focus on the positioning of the TAVR valve, at supra-annular and sub-annular alignments, and its influence of the hydrodynamics.…”

2020 ABME Paper Awards

“…Each year, the top papers in Annals of Biomedical Engineering (ABME) are selected for editorial awards that are presented at the annual Biomedical Engineering Society (BMES) meeting. During the 2020 BMES Virtual Annual Meeting, a total of five awards were presented: two awards for the most citations, 3,8 one award for the most downloads, 9 and two editor's choice awards. 2,7 These papers were selected from a total of 185 papers published in 2019.…”