Effective Regurgitant Orifice by PISA in Aortic Regurgitation
FormulaERO = 2 * pi * r² * VA * (α / 180) / (VMAX * 100)
How to get Effective Regurgitant Orifice by PISA.
Obtain a Zoomed CFD of the AV in the Deep Transgastric view. In AR, a PISA formation will occur. The distance from the center of the PISA formation to it's first aliasing velocity edge (where the color shifts from blue to red) is the radius of the PISA formation.
Note the aliasing velocity. The aliasing velocity is the velocity where if the flow exceeds this velocity the flow will be displayed with colors from the opposite scale.
Obtain a continuous wave doppler (CWD) of the aortic valve. The CWD of the mitral valve will yield a flow profile where, utilizing the calipers (or you can trace it) to show the peak velocity.
Obtain an angle of the PISA formation: The angle at the mitral valve is typically 120 degrees, whereas the angle for the aortic valve is typically 180 degrees.
Determine the ERO and the Severity of the Aortic Regurgitation