Colour Doppler of mitral flow on echocardiography with colour flow mapping (CFM) from the apical four chamber view. The left frame is in diastole when the mitral valve is open and there is a forward flow from the left atrium into the left ventricle. The flow is predominantly reddish, though there is an area of variance in the middle with yellowish and greenish colour. This indicates that the flow velocity in that region is above the Nyquist limit, which in this case is 61 cm/s as seen from the colour bar at the top right corner. The right frame shows the mitral valve in a closed position indicating systole and there is a small regurgitant jet of high velocity which is bluish mosaic coloured. Bluish colour indicates a reverse flow away from the transducer. The flow is from the left ventricle to the left atrium. The jet area is quite small compared to that of the left atrium, indicating that the volume of regurgitation is low. There is no significant dilatation of the left atrium or the left ventricle as the regurgitation is not sufficient to produce volume overloading of the left sided chambers.