PISA Calculator

The calculations rely on established hydrodynamic principles applied in echocardiography. The core formulas utilized by this tool are:

PISA (Proximal Isovelocity Surface Area): PISA = 2 * π * (r^2)

VFR (Regurgitant Flow Rate): VFR = 2 * π * (r^2) * Vr

ERO (Effective Regurgitant Orifice): ERO = (VFR * 100) / Vmax

RVol (Regurgitant Volume): RVol = (ERO / 100) * VTI

MVA (Mitral Valve Area): Mva = (2 * π * (r^2) * Vr * (α / 180)) / Vmax

Here, r represents the aliasing radius, Vr is the aliasing velocity, Vmax is the peak velocity of the regurgitant jet, VTI is the velocity-time integral, and α is the angle correction factor when applicable.

Consider a clinical echocardiogram evaluation with the following input parameters: Aliasing radius (r) = 0.4 cm, Aliasing velocity (Vr) = 25 cm/s, Peak velocity (Vmax) = 250 cm/s, and Velocity-Time Integral (VTI) = 90 cm. First, calculate the Proximal Isovelocity Surface Area (PISA): PISA = 2 * π * (0.4)^2 = 2 * 3.1416 * 0.16 = 1.005 cm^2. Next, calculate the Regurgitant Flow Rate (VFR): VFR = 2 * π * (0.4)^2 * 25 = 1.005 * 25 = 25.13 cm^3/s. Then, find the Effective Regurgitant Orifice (ERO): ERO = (25.13 * 100) / 250 = 10.05 mm^2. Finally, determine Regurgitant Volume (RVol): RVol = (10.05 / 100) * 90 = 9.04 mL. This comprehensive breakdown allows practitioners to verify every stage of the fluid dynamic assessment.

Ensure that all linear measurements, such as the aliasing radius, are recorded in consistent units (centimeters) before entering them into the calculator to prevent magnitude errors. Always optimize the Nyquist limit on your echocardiography machine to capture a clean, hemispheric aliasing boundary for the most accurate radius measurement. Finally, cross-verify automated ultrasound machine readings with manual calculator inputs during complex or eccentric regurgitant jet evaluations.