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Computer simulation of left ventricular filling flow: determinants of wave propagation velocity

By Jan Vierendeels, Kristiaan Riemslagh, Erik Dick and Pascal Verdonck

Abstract

A 2D axisymmetrical computer model is developed describing left ventricular (LV) flow during filling. The unsteady Navier-Stokes equations in a LV geometry with moving walls are solved. The relaxation and compliance of the LV wall and the fluid-wall interaction are taken into account. The method is used to simulate the filling of a canine heart. The computed results show intraventricular flow and pressure patterns during filling. Vortices are formed during the acceleration phases of the filling waves. During the deceleration phases they are amplified and convected into the ventricle. The vortices can be recognized on the calculated 2D colour echocardiograms. The vortex formation is an experimentally observed phenomenon (Bellhouse 1972, Lee and Talbot 1979, Steen and Steen 1994). From a calculated colour M-mode Doppler echocardiogram, it can be seen that both early and atrial filling waves travel from base to apex. The maximal blood velocity during the early filling wave of the reference simulation is 70 cm/s and the wave propagation velocity (WPV) of the filling wave, which corresponds with the propagation of a ring vortex, is 45 cm/s. The ratio is 1.56. This hemodynamic behaviour was also observed in vitro (Steen and Steen 1994) and in vivo (Brun et al. 1992, Stugaard et al. 1994, Takatsuji et al. 1996, Greenberg et al 1996). Slower relaxation, higher LV stiffness and higher preload result in a smaller WPV for a given peak E velocity. Higher peak E velocity results in a higher WPV. These findings are in correspondance with in vive measurements (Garcia et al. 1997)

Topics: Technology and Engineering, biomedical engineering, Partial Differential Equations, CFD, M-MODE DOPPLER, PRESSURE-GRADIENTS, ECHOCARDIOGRAPHY, FLUID, HEART
Publisher: Society for Computer Simulation
Year: 2000
OAI identifier: oai:archive.ugent.be:400944
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