Laser Doppler anemometry measurements of steady flow through two bi-leaflet prosthetic heart valves

Abstract

IntroductionIn vitro hydrodynamic characterization of prosthetic heart valves provides important information regarding their operation, especially if performed by noninvasive techniques of anemometry. Once velocity profiles for each valve are provided, it is possible to compare them in terms of hydrodynamic performance. In this first experimental study using laser doppler anemometry with mechanical valves, the simulations were performed at a steady flow workbench.Objective To compare unidimensional velocity profiles at the central plane of two bi-leaflet aortic prosthesis from St. Jude (AGN 21 - 751 and 21 AJ - 501 models) exposed to a steady flow regime, on four distinct sections, three downstream and one upstream. MethodsTo provide similar conditions for the flow through each prosthesis by a steady flow workbench (water, flow rate of 17L/min. ) and, for the same sections and sweeps, to obtain the velocity profiles of each heart valve by unidimensional measurements. ResultsIt was found that higher velocities correspond to the prosthesis with smaller inner diameter and instabilities of flow are larger as the section of interest is closer to the valve. Regions of recirculation, stagnation of flow, low pressure, and flow peak velocities were also found. Conclusions Considering the hydrodynamic aspect and for every section measured, it could be concluded that the prosthesis model AGN 21 - 751 (RegentTM) is superior to the 21 AJ - 501 model (Master Series). Based on the results, future studies can choose to focus on specific regions of the these valves.

Effect of the bileaflet inlet valve angle on the flow of a pediatric ventricular assist device: Experimental analysis

“…The velocity profiles of bileaflet valves have been measured with LDA and PIV since the beginning of the millennium. 21,[37][38][39] These measurements were focused on the velocity profiles of only one leaflet or in an area after the valves, which did not account for the details of the flow closest to the valve's moving parts. Furthermore, the assumption of a Poiseuille velocity profile is not valid for the downstream flow due to PVAD complex internal geometry.…”

Synchrotron x-ray radiography, fluorescence, and imaging of coaxial rocket injector sprays

“…Instead fully oscillatory flow through the system was observed, though high degrees to laminar flow was always maintained (Mücke et al (2013)). Similar biological studies into the in vitro hydrodynamic characterization of prosthetic heart valves (Bazan et al (2013)) have also been performed demonstrating the progression of LDA from lab experiment to truly in-vitro experimentation on biological devices.…”

Investigação do escoamento no dispositivo de assistência ventricular pediátrico do Incor por velocimetria de imagem de partículas resolvida no tempo.

“…Essas medidas concentravam-se nos perfis de apenas um dos folhetos ou de uma área após a saída das válvulas, o que nem sempre representava os detalhes do escoamento mais próximo e em cada região por onde o fluido poderia passar. Os perfis de velocidade da válvula 21AJ-501, utilizada nas medições PIV, foram medidos com LDA porBazan et al (2013) a 30 mm a montante e a 8, 20 e 32 mm a jusante do centro válvula (Figura 147). Após o fluido passar pela válvula, o escoamento apresenta três picos de velocidade, dois deles são semelhantes e ocorrem entre o anel da válvula e o folheto mais próximo.…”