MR PISA Calculator

 

The Proximal Isovelocity Surface Area or PISA method or calculation of MR assumes that there is flow convergence in systole around one leaking orifice of the mitral valve. As such we can assume blood flow converges in a hemispherical shape as it goes from the left ventricle toward the left atrium in someone with a single central jet of MR.
We can then use the continuity equation by using the area of the hemisphere of flow convergence and its velocity to calculate the area of the effective regurgitant orifiace area (EROA), since we also know the peak mitral regurgitant velocity. We can then get the mitral regurgitant volume once we know the EROA by multiplying it by the MR VTI . This principle is illustrated below along with a sample calculation at the bottom of the page. To the right we have the calculator.

Necessary input:

PISA radius: cm
Aliasing velocity: cm/s
Peak MR velocity: METERS/s
MR VTI: cm

Optional input (to calculate regurgitant fraction):


LVOT diameter: cm
LVOT VTI: cm


Effective regurgitation orifice area : cm^2
Regurgitant Volume: ml
Forward LV Stroke Volume: ml
Regurgitant Fraction: %

Criteria For MR severity*

Criteria
Mild MR
Severe MR
Regurgitant Volume
< 30 cc
> 60 cc
Regurgitant Fraction
< 30 %
> 50 %
EROA
< 0.20 cm^2
> 0.40 mm^2

 

*Moderate MR has values considered in between those of mild and severe both.

 

Example Calculation:

 Important Points:

1. It is important to shift the color baseline to get a lower aliasing velocity in order to get an adequate hemispherical flow convergance profile. An aliasing velocity around 40cm/s is recommended.

2. Whether you are doing TEE or TTE a simple rule of thumb is to shift the baseline in the direction of the MR jet (this means changing the lower velocity in TTE apical views and the upper aliasing velocity in the mid esophageal TEE views.)

3. This method is only reliable for quantifying a single centrallly directed jet. In patients with multiple MR jets, or those which are eccentric the PISA method is not reliable.

4. This is just one of many ways to quantify MR. A more detailed description of others can be found in the textbook section.