Vena contracta measurement. The VC (white arrows) of the MR jet is measured from parasternal long axis view as the narrowest width of the proximal jet at the level of or just distal to the leaflet tips. In this view, the image is zoomed into the area of the VC (arrows), with sector size and depth selected to optimize color Doppler resolution. Magnification is essential to correct grading of MR severity by the VC method because small changes in the measurement may affect severity grade. VC = vena contracta.