A Computational Fluid Mechanical Study on the Effects of Opening and Closing of the Mitral Orifice on a Transmitral Flow Velocity Profile and an Early Diastolic Intraventricular Flow

A computational fluid dynamics study of intraventricular flow during early diastole is carried out to examine the effect of a change in the size of the mitral orifice due to opening and closing of the mitral valve on the flow evolution in the left ventricle during early diastole. It is found that a velocity profile of a transmitral flow with maximum velocity locating at the center of the mitral orifice is generated by gradual opening of the mitral orifice, and it remains even after the mitral orifice has fully opened. This transmitral flow causes the development of a vortex ring extending from the anterior to the posterior side of the left ventricle. The vortex ring keeps the main inflow to stream linearly toward the ventricular apex. Such a flow pattern produces an elongated shape of an aliasing area in a color M-mode Doppler echocardiogram obtained clinically. It is, therefore, considered that although opening and closing of the mitral orifice occur with a short period, they play an important role in characterizing intraventricular flow during early diastole.