Assessment degree of Mitral Regurgitation by Flow convergence method (PISA)
The radius of the proximal zone (PISA - Proximal Isovelosity surface Area) is a parameter characterizing the severity of regurgitation, determined on color Doppler. PISA is part of the color spectrum on the ventricular side of the mitral valve.
Formation of the flow of regurgitation begins before entering the left atrium. The more regurgitation, the more area PISA occupies in the left ventricle. To measure the radius of the proximal zone, the regurgitation flow velocity must exceed the Nyquist limit and turn red. To do this, we need to increases the image size and decrease the Nyquist limit.
PISA is made up of several layers. Each of them corresponds to a certain flow rate. Based on the assumption that all of the regurgitation flow will be on the other side of the valve and based on the principle of mass invariance, the volumetric regurgitation rate can be calculated.
r - the radius of the proximal zone of the flow of regurgitation. Vr - Minimum speed when the Doppler spectrum is distorted (exceeds the Nyquist limit).
The area of the regurgitation orifice is calculated by the following formula:
Vmax - Maximum regurgitation flow rate. V r- Nyquist limit.
Measurement can be divided into the next stages:
- Align insonation beam with the flow, usually in apical views; zoomed view
- Lower the color Doppler baseline in the direction of the jet.
- Look for the hemispheric shape to guide the best low Nyquist limit
- Look for need for angle correction if flow convergence zone is nonplanar
- Measure PISA radius at roughly the same time as CW jet peak velocity
Degree of Mitral Regurgitation by EROA (cm2)
- Mild < 0.20
- Mild-Moderate 0.20 - 0.29
- Moderate-severe 0.30 - 0.39
- Severe > 0.40
Apical 4 Chamber view. Color Doppler. Degree of Mitral Regurgitation by Proximal Isovelocity Surface Area (PISA). Simulation By Echocardiography Online Simulator MyEchocardiography.com
Apical 4 Chamber view. Color Doppler. Degree of Mitral Regurgitation by Proximal Isovelocity Surface Area (PISA). Zoomed image. Simulation By Echocardiography Online Simulator MyEchocardiography.com
PISA radius (r)
Apical 4 Chamber view, CW Doppler. Mitral Regurgitation Vmax (maximum velocity) Assessment. Simulation By Echocardiography Online Simulator MyEchocardiography.com
ASE Guideline for Assessment degree of Mitral regurgitation
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