Quantify mitral regurgitation from proximal isovelocity surface area (PISA) measurements with the ASE PISA equation, plus ASE 2017 severity grading.
Regurgitant flow = 2 × π × r² × V_aliasing (mL/s)EROA = (2 × π × r² × V_aliasing) / V_max (cm²)
Per Zoghbi et al., J Am Soc Echocardiogr 2017. Values exactly on a boundary count upward: 0.20 is moderate, 0.40 is severe.
Severity grading must be integrative (vena contracta, pulmonary vein flow, chamber sizes, clinical context) — never from EROA alone.
EROA = (2 x pi x r squared x V_aliasing) / V_max. Worked example: PISA radius r = 0.9 cm, aliasing velocity = 40 cm/s, peak MR velocity = 500 cm/s. Regurgitant flow = 2 x pi x 0.81 x 40 = 203.58 mL/s. EROA = 203.58 / 500 = 0.41 cm2 (exact 0.4072), which is severe by ASE criteria.
For primary MR (ASE 2017, Zoghbi et al.): mild EROA below 0.20 cm2, moderate 0.20-0.39 cm2, severe 0.40 cm2 or higher. Companion regurgitant-volume cutoffs: mild below 30 mL, moderate 30-59 mL, severe 60 mL or higher. Values exactly on a boundary count upward: 0.20 is moderate, 0.40 is severe.
From the ASE 'Equations You Should Know' review: r = 0.54 cm, aliasing velocity = 32 cm/s, peak velocity = 439 cm/s gives EROA = 0.13 cm2 (exact 0.1336), which is mild.
RVol = EROA x VTI of the MR jet. Example: EROA 0.4072 cm2 with an MR VTI of 150 cm gives RVol = 61.07 mL, which is severe (60 mL or higher).
PISA assumes a hemispheric, circular orifice. It is less accurate with non-circular or crescent-shaped orifices (common in secondary MR, where it can underestimate), eccentric jets, multiple jets, non-holosystolic MR, and flow constrained by nearby walls. It measures peak instantaneous flow and assumes peak flow and peak jet velocity occur at the same time.
Raising the aliasing velocity shrinks the measured PISA radius, but the product 2 x pi x r squared x Va stays approximately constant, so EROA is roughly unchanged. Example: r = 0.7 cm, Va = 60 cm/s, Vmax = 550 cm/s gives EROA = 0.34 cm2 (exact 0.3359, moderate) with flow 184.73 mL/s.
No. This tool is for education only and is not medical advice. EROA quantification must be performed and interpreted by a qualified cardiologist as part of a complete echocardiographic study.
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