Aortic Valve Area Calculator
Calculate aortic valve area using the Gorlin formula or continuity equation. Classify aortic stenosis severity with AVAI indexing.
PISA Calculator — Proximal Isovelocity Surface Area
Use the 2D PISA method to estimate EROA and regurgitant volume for valvular regurgitation in a structured echocardiography worksheet.
⚠️ Medical Disclaimer: This calculator is for educational and clinical decision support only. All measurements should be verified by trained echocardiographers. Treatment decisions require comprehensive evaluation.
Measured at color flow aliasing boundary
Usually 30–40 cm/s
From CW Doppler
For regurgitant fraction estimate
PISA Flow Rate⧉
203.6 mL/s
PISA area: 5.09 cm²
EROA⧉
0.41 cm²
Effective Regurgitant Orifice Area
Regurgitant Volume⧉
61 mL
Per beat
Regurgitant Fraction⧉
43%
Estimated from VTI ratio
Severity Grade⧉
Severe
EROA 0.41 cm², RVol 61 mL
Heart Rate⧉
72 bpm
Cardiac output factor: ~4.4 L/min regurgitant
Severity: Severe Regurgitation
EROA = 0.41 cm² | Regurgitant Volume = 61 mL
Mitral Regurgitation Severity (ASE/ACC Guidelines)
| Parameter | Mild | Moderate | Severe |
|---|---|---|---|
| EROA (cm²) | < 0.20 | 0.20–0.39 | ≥ 0.40 |
| Regurgitant Volume (mL) | < 30 | 30–59 | ≥ 60 |
| Regurgitant Fraction (%) | < 30 | 30–49 | ≥ 50 |
| Vena Contracta (cm) | < 0.3 | 0.3–0.69 | ≥ 0.7 |
PISA Method Steps
| Step | Measurement | How |
|---|---|---|
| 1 | Aliasing velocity | Shift color baseline to get hemispheric convergence zone |
| 2 | PISA radius | Measure from aliasing boundary to regurgitant orifice |
| 3 | Peak velocity | CW Doppler through regurgitant jet |
| 4 | VTI | Trace CW Doppler envelope |
| 5 | Calculate | EROA = 2πr²×Va ÷ Vmax |
Planning notes, formulas, and examples
About the PISA Calculator — Proximal Isovelocity Surface Area
The Proximal Isovelocity Surface Area (PISA) method is a quantitative echocardiographic technique used to assess the severity of valvular regurgitation. By measuring the flow convergence zone proximal to a regurgitant orifice, clinicians can calculate the Effective Regurgitant Orifice Area (EROA) and regurgitant volume — key parameters for grading regurgitation severity.
The PISA method is based on the principle of conservation of mass: as blood accelerates toward a regurgitant orifice, it forms concentric hemispheric shells of increasing velocity. At the aliasing boundary visible on color Doppler, the velocity equals the Nyquist limit, and the radius of this hemisphere can be measured to calculate instantaneous flow rate.
This calculator applies the standard PISA formula to compute flow rate, EROA, and regurgitant volume for mitral, aortic, and tricuspid valves. Results are graded according to ASE/ACC guidelines for regurgitation severity. While PISA is most validated for mitral regurgitation with a circular orifice, it is widely used across all valves with appropriate clinical judgment.
When This Page Helps
The PISA method gives a quantitative way to summarize regurgitation severity that can be reviewed alongside the rest of the echo. This page is most useful when it keeps the multi-step PISA arithmetic transparent rather than leaving the calculation buried in manual notes.
How to Use the Inputs
- Select the valve being evaluated (mitral, aortic, or tricuspid).
- Enter the PISA radius measured from the aliasing boundary to the regurgitant orifice on zoomed color Doppler.
- Enter the aliasing velocity (Nyquist limit) from your color Doppler settings, typically 30–40 cm/s.
- Enter the peak regurgitant velocity from continuous-wave Doppler through the regurgitant jet.
- Enter the regurgitant jet VTI (velocity-time integral) traced from the CW Doppler envelope.
- Optionally enter mitral inflow VTI for regurgitant fraction estimation.
- Review EROA, regurgitant volume, and severity grade against ASE guidelines.
Formula used
PISA Flow Rate = 2π × r² × Va (mL/s)
EROA = PISA Flow Rate ÷ Peak Regurgitant Velocity (cm²)
Regurgitant Volume = EROA × Regurgitant VTI (mL)
Where r = PISA radius (cm), Va = aliasing velocity (cm/s)Example Calculation
Result: EROA = 0.41 cm², Regurgitant Volume = 61 mL — Severe mitral regurgitation
With PISA radius 0.9 cm and aliasing velocity 40 cm/s, PISA flow = 2π × 0.81 × 40 = 203.6 mL/s. EROA = 203.6 ÷ 500 = 0.41 cm². Regurgitant volume = 0.41 × 150 = 61 mL. Both EROA ≥ 0.40 and RVol ≥ 60 indicate severe MR.
Tips & Best Practices
- Zoom into the regurgitant orifice to maximize PISA radius measurement accuracy.
- Reduce the aliasing velocity (shift baseline) to enlarge the hemispheric convergence zone for easier measurement.
- Measure at the time of peak regurgitant velocity for the most accurate instantaneous calculation.
- For functional MR with an elliptical orifice, PISA may underestimate severity — consider 3D PISA or MRI.
- Average measurements from 3–5 beats (more if atrial fibrillation) for reliable results.
What The PISA Method Measures
PISA estimates regurgitant flow by measuring the color-Doppler flow-convergence radius at the aliasing boundary, then converting that into flow rate, EROA, and regurgitant volume. It is most widely used for mitral regurgitation, but the same basic logic can be applied to other valves with caution.
Why Interpretation Still Has Limits
The calculation assumes a roughly hemispheric convergence zone and a geometry that is often only approximate in real patients. Eccentric jets, noncircular orifices, tethered leaflets, poor alignment, and beat-to-beat variation can all change the estimate.
Best Use
Use this worksheet to keep the PISA numbers together and to compare them with the rest of the echocardiographic assessment. Final grading should still be integrative rather than based on PISA alone.
Sources & Methodology
Last updated:
Methodology
This page applies the conventional 2D PISA workflow by calculating hemispheric flow rate from the PISA radius and aliasing velocity, then dividing by peak regurgitant velocity to estimate EROA and multiplying by regurgitant VTI to estimate regurgitant volume. It is best read as an echocardiography worksheet that keeps the main calculations together.
PISA has known limitations. Nonhemispheric flow convergence, eccentric jets, noncircular regurgitant orifices, and beat-to-beat variation can all change the estimate, so the output should be interpreted with the rest of the echocardiographic assessment rather than used as a stand-alone severity decision.
Sources
- Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation (American Society of Echocardiography) — ASE guideline covering integrative grading of native valvular regurgitation and the role of PISA-derived EROA and regurgitant volume.
- Effective mitral regurgitant orifice area: clinical use and pitfalls of the proximal isovelocity surface area method (PubMed / Journal of the American College of Cardiology) — Classic paper describing clinical use and pitfalls of the PISA method.
Frequently Asked Questions
PISA stands for Proximal Isovelocity Surface Area. It is a method of quantifying regurgitant flow by measuring the hemispheric convergence zone on color Doppler imaging proximal to a regurgitant orifice.
PISA is well-validated for mitral regurgitation with circular orifices and correlates well with cardiac MRI. Accuracy decreases with eccentric jets, non-circular orifices, or when the convergence zone is not truly hemispheric.
Effective Regurgitant Orifice Area is the cross-sectional area of the regurgitant orifice through which blood flows backward. It is the single best quantitative parameter for grading regurgitation severity.
PISA is recommended as a primary quantitative method for mitral regurgitation. For aortic regurgitation, use pressure half-time and holodiastolic flow reversal. PISA can supplement any valve assessment.
Shift the color Doppler baseline to achieve aliasing at 30–40 cm/s. This creates a well-defined hemispheric convergence zone. Lower velocities produce larger, easier-to-measure hemispheres.
Limitations include: assumption of a hemispheric convergence zone (may be constrained by walls), assumption of a circular orifice (may be crescentic in functional MR), difficulty measuring when the jet is eccentric, and flow entrainment artifacts.
More in this topic
Mitral Valve Area Calculator
Calculate mitral valve area using pressure half-time, Gorlin formula, or planimetry. Classify mitral stenosis severity with indexed MVA.
Effective Regurgitant Orifice Area (EROA) Calculator
Calculate EROA via PISA or volumetric method for mitral and aortic regurgitation severity grading. Includes regurgitant volume, fraction, and ASE severity tables.