How to get an MVA by PISA.
Step 1: Obtain a Zoomed CFD of the MV in the mid esophageal view. If there is a sufficiently stenosed mitral valve, 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.
Step 2: 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.
Step 3: Obtain a continuous wave doppler (CWD) of the mitral 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.
Step 4: Obtain an angle of the PISA formation: The angle at the mitral valve is typically 120 degrees, whereas the angle for the aortic valve (for aortic stenosis calculations) is typically 180 degrees.