Calculation of EROA by PISA method. In this apical four chamber view, the PISA region is displayed from a magnified apical view, and the hemispheric PISA radius R is shown between the crosshairs. Note the change of the color Doppler scale, with a baseline shift in the direction of the MR jet (e.g. “down” in this example). The aliasing velocity is 30.8 cm/s. EROA can be calculated as the product of 2πR2 x Aliasing Velocity ÷ Peak Velocity of MR (peak velocity not shown). The vena contracta is indicated as the distance between the two arrows. EROA = effective regurgitant orifice area; PISA = proximal isovelocity surface area.