PISA Calculator
Proximal Isovelocity Surface Area for echocardiographic assessment
PISA Parameters
📋 PISA Measurement Guide
- • Measure PISA radius from vena contracta to furthest edge of the hemisphere
- • Use color Doppler to visualize the convergence zone
- • Optimize Nyquist limit to clearly define the aliasing boundary
- • Measure at the point of maximum PISA in a single plane
Distance from vena contracta to aliasing boundary
Nyquist limit velocity at radius r
Peak MR velocity by continuous-wave Doppler
VTI of mitral regurgitant jet
PISA Calculation Results
Mitral Regurgitation Severity
Clinical Example
Case: 65-year-old with Mitral Regurgitation
Echo Findings:
- • PISA radius: 0.9 cm
- • Aliasing velocity: 40 cm/s
- • Peak MR velocity: 500 cm/s
- • VTI of MR jet: 18 cm
Calculated Results:
- • PISA: 5.09 cm²
- • ERO: 40.7 mm² (0.41 cm²)
- • Regurgitant Volume: 73.3 ml/beat
- • Assessment: Severe MR
PISA Formulas
Basic PISA
PISA = 2πr²
Volume Flow Rate
VFR = 2πr² × Vr
ERO
ERO = VFR / Vmax
Regurgitant Volume
RVol = ERO × VTI
MVA (Stenosis)
MVA = (2πr² × Vr × α/180) / Vmax
Severity Classification
Mitral Regurgitation
Mitral Stenosis
🔧 Technical Tips
Optimization
- • Lower Nyquist limit to enhance PISA visualization
- • Use multiple views to find maximum PISA
- • Ensure proper beam alignment
Common Pitfalls
- • Eccentric jets may underestimate severity
- • Multiple jets require separate measurements
- • Poor image quality affects accuracy
⚕️ Medical Disclaimer
This calculator is for educational purposes only and should not replace clinical judgment.
PISA measurements require proper echocardiographic technique and should be interpreted by qualified personnel.
Always consider multiple parameters and clinical context for valve assessment.
Understanding PISA Method
What is PISA?
PISA (Proximal Isovelocity Surface Area) is an echocardiographic method used to quantify valve regurgitation and stenosis based on the flow convergence principle.
Physical Principles
- •Based on conservation of mass and continuity equation
- •Blood accelerates as it approaches an orifice
- •Forms hemispheric isovelocity surfaces
- •Color Doppler aliasing defines velocity boundaries
Clinical Applications
Mitral Regurgitation
- • Quantifies regurgitant volume and orifice area
- • Less dependent on loading conditions
- • Useful for surgical decision-making
Mitral Stenosis
- • Calculates mitral valve area
- • Alternative to pressure half-time method
- • Especially useful in irregular rhythms
Other Applications
- • Aortic regurgitation assessment
- • Tricuspid regurgitation quantification
- • Shunt flow calculations
Important Considerations
Assumptions:
- • Hemispheric flow convergence
- • Centrally directed jet
- • Uniform velocity at radius r
- • No significant acceleration proximal to PISA
Limitations:
- • Eccentric jets may not form perfect hemispheres
- • Multiple jets require separate calculations
- • Angle correction needed for non-central jets
- • Technical expertise required for accurate measurements