# EROA Calculator (Effective Regurgitant Orifice Area)

URL: https://speedycalculator.com/calculators/health/eroa/
Last updated: 2026-10-30

> The EROA calculator estimates the effective regurgitant orifice area of a leaking mitral valve with either the PISA method or the volumetric method (mitral minus aortic stroke volume), and gives the regurgitant volume and fraction.

## Inputs

- Method
- PISA radius (cm, mm)
- Aliasing velocity (cm/s)
- Peak MR velocity (cm/s)
- Mitral annulus diameter (cm, mm)
- Mitral inflow VTI (cm)
- LVOT diameter (cm, mm)
- LVOT VTI (cm)
- MR VTI (cm)

## Results

- Mitral stroke volume
- LVOT stroke volume
- EROA
- Regurgitant volume
- Regurgitant fraction

## Formula

```
PISA: EROA = 2πr² × Va ÷ peak MR velocity
Volumetric: RVol = SV(mitral) − SV(LVOT); EROA = RVol ÷ MR VTI
Regurgitant fraction = RVol ÷ SV(mitral) × 100
```

## Explanation

EROA is the size of the hole through which blood leaks back. It is the most robust single measure of regurgitation severity because it depends less on blood pressure and heart rate than jet size.

### How to use the EROA Calculator

- **Method**
- **PISA radius**
- **Aliasing velocity**
- **Peak MR velocity**
- **Mitral annulus diameter**
- **Mitral inflow VTI**
- **LVOT diameter**
- **LVOT VTI**
- **MR VTI**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Choose the method. For volumetric, enter mitral annulus diameter and VTI, LVOT diameter and VTI, and MR VTI.

### Inputs explained

FieldWhat to enterMethodChoose one: PISA, VolumetricPISA radiusUnits: cm, mmAliasing velocityIn cm/sPeak MR velocityIn cm/sMitral annulus diameterUnits: cm, mmMitral inflow VTIIn cmLVOT diameterUnits: cm, mmLVOT VTIIn cmMR VTIIn cm

### What each result means

- **Mitral stroke volume** = pi×([Mitral annulus diameter]÷2)^2×[Mitral inflow VTI]
- **LVOT stroke volume** = pi×([LVOT diameter]÷2)^2×[LVOT VTI]
- **Regurgitant volume** = [EROA]×[MR VTI]
- **Regurgitant fraction** = [Regurgitant volume]÷([LVOT stroke volume] + [Regurgitant volume])×100

### Example values

How the main result changes when **PISA radius** changes and everything else stays at the example values above:

PISA radius (cm)EROA (cm²)0.450.10.6750.230.90.411.130.641.350.921.81.63
*Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.*

## Worked example

Inputs — Method: PISA; PISA radius: 0.9 cm; Aliasing velocity: 40 cm/s; Peak MR velocity: 500 cm/s; MR VTI: 150 cm.

Results — Mitral stroke volume = 121 mL; LVOT stroke volume = 62 mL; **EROA = 0.41 cm²**; Regurgitant volume = 61 mL; Regurgitant fraction = 49 %.

## Key terms

- **EROA**: Effective regurgitant orifice area.
- **RVol**: Regurgitant volume.

## FAQ

**What is a severe EROA?**
0.40 cm² or more for primary mitral regurgitation.

**What regurgitant fraction is severe?**
50% or more.

**Which method is better?**
PISA is quicker; the volumetric method helps when PISA is unreliable, such as with eccentric jets.


## Sources

- [Zoghbi WA et al. Recommendations for noninvasive evaluation of native valvular regurgitation. J Am Soc Echocardiogr, 2017](https://pubmed.ncbi.nlm.nih.gov/28314623/)