PISA Calculator — Mitral Regurgitation EROA
The PISA method uses colour Doppler echocardiography to estimate the Effective Regurgitant Orifice Area (EROA) and regurgitant volume of the mitral valve, which determine the severity of mitral regurgitation (MR).
cm
cm/s
cm/s
cm
Larger EROA = more severe regurgitation
- 1
PISA surface area (2π r²)
2 × π × 0.8² = 2 × π × 0.64 = 4.021 - 2
Flow rate at PISA shell (× Va)
4.021 × 40 cm/s = 160.85Flow rate (mL/s) = hemisphere area × aliasing velocity. - 3
EROA in cm² (flow rate ÷ Vmax)
160.85 ÷ 500 = 0.3217 - 4
EROA in mm² (× 100)
0.3217 × 100 = 32.2
How does this calculator work?
PISA: EROA = 2π r² × Va / Vmax. Enter PISA radius (cm), aliasing velocity (cm/s), peak MR velocity (cm/s) and optionally MR VTI (cm). Outputs EROA in mm², regurgitant volume (mL) and MR severity grade per 2014 AHA/ACC guidelines (mild <20 mm², moderate 20–39 mm², severe ≥40 mm²).
Formula
How this is calculated
When blood leaks backward through an incompetent mitral valve, it converges toward the regurgitant orifice in concentric hemispheric shells of increasing velocity — the Proximal Isovelocity Surface Area. By colour Doppler, a velocity alias (colour flip) appears at radius r from the orifice. The flow rate crossing that hemisphere is Q = 2π r² × Va, where Va is the aliasing velocity (Nyquist limit) set on the machine.
Assuming flow continuity, this same flow rate passes through the regurgitant orifice. The EROA is therefore Q divided by the peak regurgitant jet velocity Vmax measured by continuous-wave Doppler: EROA = (2π r² × Va) / Vmax. EROA in cm² × 100 = mm².
The regurgitant volume (RVol, in mL) equals EROA multiplied by the velocity-time integral (VTI) of the MR jet: RVol = EROA × VTI. Grading follows the 2014 AHA/ACC Guideline: mild MR is EROA < 20 mm² and RVol < 30 mL; moderate is 20–39 mm² / 30–59 mL; severe is EROA ≥ 40 mm² or RVol ≥ 60 mL. The method assumes a hemispheric PISA shape and steady laminar flow at the convergence zone; eccentric jets, subvalvular apparatus obstruction and atrial fibrillation reduce accuracy.
Frequently asked questions
Set the colour Doppler baseline toward the mitral regurgitation jet to lower the Nyquist limit (typically 25–45 cm/s). The alias (colour shift) appears as a hemisphere of radius r on the atrial side of the valve — measure r from the leaflet coaptation point to the first aliasing boundary in the zoomed image.
A Nyquist limit of 30–40 cm/s gives PISA radii that are easy to measure; higher limits produce smaller radii and are sometimes preferred for large PISA shells. Whatever Nyquist limit you select, enter that value as Va in this calculator.
Yes — the same hemispheric flow-convergence principle applies. For tricuspid regurgitation (TR) and aortic regurgitation (AR), a similar formula is used, but the severity grading thresholds differ. This calculator is set up for MR grading per the 2014 AHA/ACC valvular guidelines.
Also known as
TG we-Calculate Editorial Team. (2026). PISA Calculator — Mitral Regurgitation EROA [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/pisa-calculator
TG we-Calculate Editorial Team. "PISA Calculator — Mitral Regurgitation EROA." TG we-Calculate. 2026. https://we-calculate.com/calculator/pisa-calculator.
TG we-Calculate Editorial Team, "PISA Calculator — Mitral Regurgitation EROA," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/pisa-calculator
@misc{wecalculate_pisa_calculator, title = {PISA Calculator — Mitral Regurgitation EROA}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/pisa-calculator}}, year = {2026}, note = {TG we-Calculate} }
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