PISA Calculator
Assess mitral valve regurgitation severity and mitral valve area using the PISA echocardiography method. Free online PISA calculator for cardiologists and sonographers.
About This Calculator
The PISA (Proximal Isovelocity Surface Area) Calculator is a specialized echocardiography tool for assessing mitral valve regurgitation and stenosis severity. Based on the Doppler ultrasound principle of flow convergence, this calculator helps cardiologists, sonographers, and cardiology trainees quantify mitral valve dysfunction using the validated PISA method.
Our calculator computes the proximal isovelocity surface area (PISA = 2πr²), volume flow rate (VFR = PISA × Vr), effective regurgitant orifice area (ERO = VFR / Vmax), regurgitant volume (RVol = ERO × VTI), and mitral valve area (MVA = 2πr² × Vr × α/180 / Vmax). Results include automated severity classification for both mitral regurgitation (Mild, Mild-Moderate, Moderate-Severe, Severe based on ERO and RVol thresholds) and mitral stenosis (Normal, Mild, Moderate, Severe based on MVA).
How the PISA Method Works
The PISA method leverages the Venturi effect — blood accelerates as it approaches a narrowed orifice, creating a hemispheric flow convergence zone visible on color Doppler. By measuring the radius of this hemisphere (r) and the aliasing velocity (Vr), the calculator determines the flow rate through the orifice. Combined with the peak mitral velocity (Vmax) from continuous-wave Doppler, it quantifies the effective regurgitant orifice area — the gold-standard parameter for regurgitation severity.
Clinical Application
The PISA calculator is used in echocardiography labs worldwide for: grading mitral regurgitation severity per ASE guidelines, calculating mitral valve area in rheumatic mitral stenosis, monitoring disease progression, pre-operative planning for mitral valve surgery or transcatheter edge-to-edge repair (TEER), and serial follow-up of known mitral valve disease.
Methodology Note
The calculator uses standard formulas from the American Society of Echocardiography (ASE) guidelines for native valvular regurgitation. PISA = 2πr² assumes a hemispheric flow convergence. For mitral stenosis, the angle correction factor (α/180) accounts for the leaflet opening angle. All calculations use the simplifying assumption of a hemispheric PISA, though in practice the shape may vary with orifice geometry and flow conditions.
Frequently Asked Questions
What is the PISA method in echocardiography?
PISA stands for Proximal Isovelocity Surface Area, an echocardiographic method used to assess mitral valve regurgitation and stenosis. It measures the hemisphere of accelerating blood flow approaching the mitral orifice using Doppler ultrasound, enabling calculation of the effective regurgitant orifice area (EROA), regurgitant volume, and mitral valve area (MVA).
How is PISA measured during an echo?
To measure PISA, the sonographer visualizes the flow convergence zone proximal to the mitral valve using color Doppler. The PISA radius (r) is measured from the vena contracta to the farthest edge of the PISA hemisphere. The aliasing velocity (Vr) is set by the Nyquist limit, and the peak mitral velocity (Vmax) is obtained by continuous-wave Doppler. The angle between mitral leaflets (α) is measured for mitral stenosis calculations.
How is mitral regurgitation severity classified using PISA?
Mitral regurgitation severity is classified by ERO (effective regurgitant orifice area): Mild (ERO < 0.20 cm² or < 20 mm²), Mild-Moderate (0.20-0.29 cm²), Moderate-Severe (0.30-0.39 cm²), and Severe (ERO ≥ 0.40 cm² or ≥ 40 mm²). Regurgitant volume (RVol) is also used: Mild (< 30 mL/beat), Mild-Moderate (30-44 mL/beat), Moderate-Severe (45-59 mL/beat), and Severe (≥ 60 mL/beat).
How is mitral stenosis severity classified by MVA?
Mitral stenosis severity based on mitral valve area (MVA) is classified as: Normal (4.0-5.0 cm²), Mild Stenosis (MVA > 1.5 cm²), Moderate Stenosis (MVA 1.0-1.5 cm²), and Severe Stenosis (MVA < 1.0 cm²). The PISA method calculates MVA using the formula MVA = (2πr² × Vr × α/180) / Vmax, where α is the angle between mitral leaflets.
What is the difference between ERO and RVol?
ERO (Effective Regurgitant Orifice area) represents the anatomic regurgitant orifice size in cm² or mm², indicating the severity of the valve leak. RVol (Regurgitant Volume) is the volume of blood that regurgitates per heartbeat in mL/beat. RVol depends on both the orifice size and the duration of regurgitation (velocity time integral). ERO is calculated as VFR / Vmax, and RVol is ERO × VTI.
What inputs are needed for the PISA calculator?
The PISA calculator requires: Peak Mitral Velocity (Vmax in cm/s) from continuous-wave Doppler, PISA Radius (r in cm) measured from vena contracta to the PISA edge, Aliasing Velocity (Vr in cm/s) from color Doppler Nyquist limit. Optional inputs for additional results: α Angle (degrees between mitral leaflets, for MVA calculation) and Velocity Time Integral (VTI in cm, for regurgitant volume calculation).
What is a normal mitral valve area?
A normal mitral valve area (MVA) is 4.0 to 5.0 cm². Mild mitral stenosis is defined as MVA > 1.5 cm², moderate stenosis as MVA 1.0-1.5 cm², and severe stenosis as MVA < 1.0 cm². The PISA method is one of several echocardiographic techniques used to calculate MVA, alongside planimetry and pressure half-time methods.
Can the PISA calculator replace a cardiologist assessment?
No, the PISA calculator is an educational and reference tool for healthcare professionals. It should not replace a comprehensive echocardiographic assessment by a qualified cardiologist. Clinical decisions about mitral valve disease management require integration of multiple parameters including symptoms, hemodynamics, exercise testing, and other imaging modalities. Always consult a physician for medical decisions.