Home›Calculators›Health›EROA (Mitral Regurgitation) Calculator

EROA (Mitral Regurgitation) Calculator

Health

Calculate the effective regurgitant orifice area (EROA) for mitral regurgitation using the PISA method, with ASE severity bands for mild, moderate, and severe.

Reviewed by the thecalcu.com team · Last updated July 28, 2026

PISA Radius
cm
Aliasing Velocity
cm/s
Peak MR Jet Velocity
cm/s

EROA

0cm²

Severity (ASE)

—

Not a substitute for clinical interpretation. PISA-derived EROA should be reviewed alongside the full echocardiographic study by a qualified healthcare provider.

What is a EROA Calculator?

The EROA Calculator computes the effective regurgitant orifice area for mitral regurgitation using the PISA (proximal isovelocity surface area) method, a standard non-invasive echocardiographic technique. It combines the PISA radius, the color Doppler aliasing velocity setting, and the peak mitral regurgitant jet velocity into a single area measurement, then classifies severity per American Society of Echocardiography (ASE) guidelines.

Enter your PISA radius, aliasing velocity, and peak MR jet velocity below to see your calculated EROA and severity classification. For a related forward-flow Doppler calculation, see the Doppler Echo Cardiac Output Calculator; for valve area in stenotic disease, see the Gorlin Formula Calculator.

Why Use an EROA Calculator?

The PISA-based EROA formula involves squaring a radius, multiplying by pi and two separate velocity values, and dividing, arithmetic that's simple in principle but easy to fumble under time pressure or when double-checking a report. This calculator performs the full calculation instantly and shows each intermediate step.

It's useful for reviewing an echocardiogram report's underlying PISA numbers, or for sonography and cardiology fellows practicing the standard EROA calculation.

Who Should Use This Calculator?

Cardiac sonographers, cardiology fellows, and nursing students learning echocardiography can use this calculator to check worked EROA examples against measured PISA radius and velocity values. Patients reviewing their own echocardiogram report who want to understand how their mitral regurgitation severity grade was derived may also find this a useful educational reference.

This calculator is for informational and educational purposes only. It is not a substitute for a qualified sonographer's or cardiologist's clinical interpretation of an actual echocardiographic study, always discuss your specific results and treatment options with a healthcare provider.

What Insights Does the EROA Calculator Give You?

EROA is the primary result, the calculated effective regurgitant orifice area in square centimeters, based on your PISA measurements.

Severity translates that area into a plain-language mild, moderate, or severe classification for mitral regurgitation, using the published ASE echocardiography severity thresholds.

How to use this EROA Calculator calculator

  1. Enter your PISA Radius in centimeters, as measured on the color Doppler image.
  2. Enter your Aliasing Velocity in cm/s, the Nyquist limit setting used during the study.
  3. Enter your Peak MR Jet Velocity in cm/s, from the continuous-wave Doppler tracing.
  4. Review your calculated EROA and Severity classification.
Show formula & methodology ↓Show less ↑

Formula & Methodology

EROA (cm²) = (2 × π × PISA radius² × Aliasing velocity) ÷ Peak MR jet velocity

Severity bands per ASE valve regurgitation guidelines: under 0.20 cm² is mild, 0.20 to 0.39 cm² is moderate, and 0.40 cm² or higher is severe mitral regurgitation.

Worked example: A PISA radius of 0.8 cm, aliasing velocity of 40 cm/s, and peak MR jet velocity of 500 cm/s gives EROA = (2π × 0.8² × 40) ÷ 500 = (2π × 0.64 × 40) ÷ 500 ≈ 160.8 ÷ 500 ≈ 0.32 cm², placing this result in the moderate mitral regurgitation category per ASE severity thresholds.

Frequently Asked Questions

What does EROA stand for and measure?
EROA stands for effective regurgitant orifice area, a measure of the functional size of the opening through which blood leaks backward across a leaking mitral valve. It's calculated using the PISA (proximal isovelocity surface area) method during echocardiography and is a key metric for grading mitral regurgitation severity.
What is the PISA method?
PISA is an echocardiographic technique that measures the hemispherical shell of accelerating blood flow (the isovelocity surface area) as it converges toward a regurgitant valve opening. The radius of this hemisphere at a known aliasing velocity, combined with the peak regurgitant jet velocity, allows calculation of the effective regurgitant orifice area.
What is aliasing velocity and why does it matter?
Aliasing velocity is the Nyquist limit setting on the color Doppler display at which flow direction appears to reverse color, creating the visible PISA hemisphere boundary. It's typically set between 30 and 40 cm/s for mitral regurgitation assessment, and this exact value is required as an input to the EROA formula.
What do the EROA severity categories mean?
Following American Society of Echocardiography (ASE) guidelines, an EROA under 0.20 cm² is classified as mild mitral regurgitation, 0.20 to 0.39 cm² as moderate, and 0.40 cm² or higher as severe. These thresholds help guide decisions about monitoring frequency and potential valve intervention.
Why does peak MR velocity appear in the denominator of the formula?
The regurgitant flow rate calculated from the PISA hemisphere must equal the effective regurgitant orifice area multiplied by the peak velocity of blood passing through that orifice, so dividing the flow rate by peak velocity isolates the orifice area itself. This follows directly from the basic principle that flow equals area times velocity.
Is EROA the only measure of mitral regurgitation severity?
No, EROA is one of several quantitative parameters used alongside regurgitant volume, regurgitant fraction, vena contracta width, and qualitative color Doppler jet assessment to comprehensively grade mitral regurgitation severity. Echocardiographers typically integrate multiple parameters rather than relying on EROA alone.
Does this calculator work for aortic or tricuspid regurgitation too?
The PISA method and formula structure are conceptually similar across valve types, but the specific velocity ranges and severity thresholds used in this calculator are calibrated for mitral regurgitation specifically. Aortic and tricuspid regurgitation severity grading uses different established thresholds.
How sensitive is EROA to measurement error in PISA radius?
Because PISA radius is squared in the EROA formula, small measurement errors in radius are amplified more than proportional errors in aliasing velocity or peak MR velocity. Careful, reproducible PISA radius measurement from an optimized color Doppler image is considered the most important technical factor for an accurate result.
Can this calculator replace a formal echocardiogram report?
No, this calculator is for informational and educational purposes only and simply performs the standard PISA-based EROA calculation from values you enter. Actual measurement of PISA radius, aliasing velocity, and peak MR velocity requires a properly performed echocardiogram interpreted by a qualified sonographer or cardiologist.
How does this relate to the Doppler Echo Cardiac Output Calculator?
The [Doppler Echo Cardiac Output Calculator](/doppler-echo-cardiac-output-calculator/) uses a similar Doppler flow-velocity approach but focuses on total forward cardiac output through the LVOT rather than backward regurgitant flow across the mitral valve. Both tools rely on the same underlying flow-equals-area-times-velocity principle.
How does this relate to the Gorlin Formula Calculator?
The [Gorlin Formula Calculator](/gorlin-formula-calculator/) calculates valve area for stenotic (narrowed) valves using invasive catheterization data, while this calculator calculates the effective regurgitant orifice area for a leaking valve using non-invasive echocardiography. They address opposite types of valve dysfunction using different methods.
Also known as
PISA method calculatoreffective regurgitant orifice area calculatormitral regurgitation severity calculatorPISA mitral regurgitation calculatorEROA mitral valve calculator