LEFT VENTRICULAR INFLOW PATTERNS AND MITRAL VALVE MOTION: ANIMAL STUDIES AND COMPUTER ANALYSIS.

These studies serve to unite the three theories of flow patterns and valve closure: vortices, breaking jets and chordae tension. When the jet of ventricular filling decelerates, it becomes incorporated into an expanding vortex system which sweeps the valve toward closure. The valve leaflets participate in vortex formation, and tension on the chordae and commissural tissue is necessary to hold the leaflets in an appropriate position for the interaction to occur. Finally, the momentum of the fluid which has been accelerated by the atrial contraction preceding ventricular systole serves to insure an insignificant amount of backflow with valve closure. Only the fluid on the atrial side of the stagnation point will appear to regurgitate through the annulus; no retrograde flow passes the cusp tips. Finally, the effective orifice area of the jet is determined by the vena contracta, which in turn is determined by the annulus and funnel shape of the valve. Thus, the distance between the valve tips only partly influences the amount and velocity of the atrioventricular flow.