MR jet is seen as a mosaic area within the left atrium within the color flow mapping frame. Mosaic color is due to aliasing as the MR jet velocity is much above aliasing velocity of the system. Severity of the mitral regurgitation can be assessed by the extent to which the jet extends into the left atrium. Other measures are the area of the jet, especially in comparison with the area of the left atrium. Larger the ratio, more severe the mitral regurgitation. AML is seen in the closed position between the LA and LV indicating that it is a systolic frame.
Vena contracta is the narrowest portion of the MR jet at or just beyond the regurgitant orifice. It is an accurate indicator of severity of MR, but being a small absolute value, measurement errors can be magnified. Vena contracta gives an estimate of the effective regurgitant orifice. This is best measured in the parasternal long axis view. In apical four chamber view, inherent limitation of lateral resolution makes measurement of vena contracta erroneous.
