Proximal isovelocity surface area

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Synonyms and related keywords: PISA

Overview
The proximal isovelocity surface area (PISA) technique can be used to estimate the flow across the regurgitant valve together with the Effective Regurgitant Orifice Area (EROA).

The technique is an application of the continuity principle with the underlying assumption being that the flow at the hemispheric first alias proximal surface is equal to the orificial flow at the same time in the cardiac cycle.

In order to measure these indices of regurgitation it is necessary to perform both continuous wave Doppler (CWD) and colour Doppler analyses of representative cardiac cycles.

Vmax (the peak velocity of the regurgitant flow signal) is measured with CWD.

Colour Doppler is then used to measure the radius (RA1) of the first aliased hemispheric shell at a Nyquist limit (Scale Value) typically in the range 30 - 40 cm/sec (VN).

Typical values of PISA radius (at VN of 38 cm/sec) for mitral regurgitation of differing severity are:

 * Grade             PISA Radius(mm)
 * Mild:             < 3.5
 * Moderate:         3.5 - 7.5
 * Moderately Severe: 7.5 - 14.5
 * Severe:           > 14.5

Typical values of PISA Flow for mitral regurgitation of differing severity are:

 * Grade             PISA Q
 * Mild:             < 30 ml/sec
 * Moderate:         30 - 130 ml/sec
 * Moderately Severe: 130 - 500 ml/sec
 * Severe:           > 500 ml/sec

Typical values of EROA for mitral regurgitation of differing severity are:

 * Grade             EROA(mm2)
 * Mild:             < 20
 * Moderate:         20 - 29
 * Moderately Severe: 30 - 39
 * Severe:           > 40

According to Kolev et al, the PISA technique may be particularly appropriate for the estimation of the severity of mitral regurgitation in the patient with an eccentric regurgitant jet.

How to Calculate PISA?

 * 1) Shift Aliasing velocity to 40 cm/sec
 * 2) Cine to mid systole
 * 3) Measure radius (cm)
 * 4) Calculate r2/ 2 to get ERO
 * 5) To Calculate Volume (cc) ERO x TVI of mitral valve

External Link

 * Duke University Echo Learning Center