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ECHONOMY
Tools for Echocardiographic Calculations

Muhamed Saric, MD, PhD
New York University
 

PISA

Purpose

To calculate effective orifice area (EOA) of an orifice assumed to be circular in shape and located on a planar surface. The PISA method can be used to calculate the area of a stenotic, regurgitant or shunt orifice. Once the EOA is known, one can calculate the stroke volume across the orifice; in regurgitant lesion, this the regurgitant volume.

Technical Hints

If you shift the baseline of the Nyquist color scale, the upper and the lower Nyquist limits will not be the same. In such instances, use the Nyquist limit that is in the direction of measured flow. Anagle correcton is used for mitral stenosis only.

Calculator

PISA radius (r):  

 cm

Aliasing velocity (Valias; Nyquist limit)

 cm/sec

Maximum velocity (Vmax):

 cm/sec

PISA angle:

 degrees

     
Velocity-time integral  cm
 

Answers

EOA (uncorrected)  cm2
Regurgitant volume  mL

EOA (angle corrected):

 cm2

Formulae

EOA = 2 * pi * r2 * (Valias / Vmax)

Regurgitant volume = EOA * VTI

References

Mitral stenosis: Circulation 1993;88:1157-65
Atrial septal defect: Circulation 1993;87:1591-1603
Tricuspid regurgitation: Am Heart J 1994;127:1354-62
Mitral regurgitation: J Am Coll Cardiol 1995;25:703-709
Aortic regurgitation:  J Am Coll Cardiol 1998;32:1032-1039