Fig. 13. Proximal isovelocity surface area (PISA) method in mitral stenosis: steps 1-5 (Continued).
An extension of the continuity principle is to use the proximal isovelocity surface area to calculate the MVA. Here, the point of "comparison" is changed from the aortic or pulmonic outflow tracts, for example, to the point proximal to the MV in the LA where color Doppler flow aliases in the shape of a hemisphere (Figs. 12 and 13; please see companion DVD for corresponding video
Mitral Valve Area:
PISA Method lyjM&i
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