Proximal Isovelocity Surface Area (PISA)
Enter aliasing velocity and PISA radius to obtain regurgitant flow. Add jet velocity and VTI to derive effective regurgitant orifice area and regurgitant volume.
Nyquist limit after baseline shift (typically 20–40 cm/s).
Measure from orifice to first aliasing boundary at peak regurgitation.
Continuous-wave Doppler peak velocity across the regurgitant jet.
Optional: integrates CW Doppler velocities to yield regurgitant volume.
How to Use This Calculator
Optimise colour Doppler
Lower the aliasing velocity, shift the baseline, and zoom on the regurgitant orifice to obtain a hemispheric flow convergence zone.
Measure PISA radius at peak flow
Use mid-systole for mitral regurgitation or valve-specific timing. Enter aliasing velocity and radius for flow calculation.
Add Doppler data for full quantification
Jet velocity yields EROA; adding jet VTI provides regurgitant volume to classify severity and guide interventions.
Formula
Regurgitant flow rate (mL/s) = 2π × r² × Va
EROA (cm²) = Regurgitant flow ÷ Peak regurgitant velocity
Regurgitant volume (mL/beat) = EROA × Regurgitant jet VTI
r = PISA radius (cm); Va = aliasing velocity (cm/s). Adjust for non-hemispheric geometry with correction factors when needed.
Full Description
The PISA method quantifies regurgitation by analysing concentric shells of equal velocity proximal to a regurgitant orifice. By measuring the aliasing velocity and radius of the convergence hemisphere, clinicians estimate instantaneous flow rate and derive effective orifice area. This technique is widely used for mitral and tricuspid regurgitation, though corrections are required for eccentric jets, noncircular orifices, or high-velocity convergence. Combining PISA with vena contracta, quantitative Doppler, and imaging provides comprehensive severity assessment.
Frequently Asked Questions
What if the convergence zone is not hemispheric?
Apply angle correction or use 3D transesophageal echocardiography/cardiac MRI for more accurate assessment.
Can I use PISA for tricuspid or pulmonic regurgitation?
Yes, but severity cutoffs differ. Severe TR typically corresponds to EROA ≥0.40 cm² with larger regurgitant volumes than mitral lesions.
How many beats should be averaged?
Average 3–5 beats; in atrial fibrillation average ≥5 beats to account for cycle length variation.
Does blood pressure affect PISA measurements?
Afterload influences regurgitant orifice size. Record blood pressure during assessment and interpret alongside clinical context.