EROA Mitral Regurgitation Calculator

What Is EROA in Mitral Regurgitation?

Effective regurgitant orifice area (EROA) quantifies the size of the leak through an incompetent mitral valve during systole. Echocardiography uses the proximal isovelocity surface area (PISA) method to estimate regurgitant flow and convert it into EROA, regurgitant volume, and volume flow rate. These values help grade mitral regurgitation severity and guide follow-up or surgical referral. For related cardiac echo tools, see the Doppler Echo Cardiac Output Calculator and Cardiac Output Calculator.

PISA Method and Formulas

PISA assumes a hemispheric flow convergence zone around the regurgitant orifice. Volume flow rate (VFR) through that surface is:

VFR = 2 × π × r² × Va

where r is the PISA radius in centimeters and Va is the aliasing velocity in cm/s. EROA equals VFR divided by the peak regurgitant jet velocity (Vmax):

EROA = VFR / Vmax

Regurgitant volume per beat is EROA multiplied by the regurgitant jet velocity-time integral (VTI):

Rvol = EROA × VTI

Interpreting Severity

ACC/AHA guidelines commonly classify severe mitral regurgitation when EROA is at least 0.4 cm² or regurgitant volume is at least 60 mL per beat. Values below those thresholds may represent mild or moderate disease, though symptoms, left ventricular size, and jet morphology also matter. This calculator provides quantitative echo estimates only and does not replace clinical judgment.