Computer simulation of left ventricular filling flow: impact study on echocardiograms

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. 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 is 70 cm/s and the propagation velocity of the filling wave which corresponds with the propagation of a ring vortex, is 45 cm/s. The ratio is 1.56. Slower relaxation and higher LV stiffness result in a slower wave propagation.