Quantification of Mitral Regurgitation

PISA :Proximal Isovelocity Surface Area

Carpentier’ classification of MR

1. Type I Mitral leaflet motion is normal MR results from annular dilation

2. Type II Excessive leaflet motion Prolapse or flail leaflet

3. Type III is from restricted leaflet motionType IIIa:Leaflets have restricted motion in both systole and diastole

- Rheumatic MR Type IIIb: Restricted motion during systole

-Ischemic MR/ functional MR

Normal

LV minor axis: ≤2.8 cm/m2 LV end-diastolic volume: ≤82 mL/m2Maximal LA anteroposterior diameter : ≤2 cm/m2Maximal LA volume: ≤36 mL/m2

Eye balling parameters

Parameters Mild MR Moderate MR Severe MR

LA size Normal Normal or dilated

dilated

LV size Normal Normal or dilated

dilated

Mitral leaflets Normal or abnormal

Normal or abnormal

Abnormal/flail leaflet/ruptured papillary muscle

Supportive parameters ( Doppler )Parameter Mild MR Mod MR Severe MRColour flow jet area

Small central jet (usually <4 cm2 or <20% of LA area)

Variable Large central jet (usually >10 cm2 or >40% of LA area) or variable size wall-impinging jet swirling in LA

Mitral inflow, pulsed wave

A wave dominant|

Variable E wave dominant (E usually 1.2 m/s)

Jet density, CW Incomplete or faint

Dense Dense

Jet contour, CW Parabolic Usually parabolic

Early peaking, triangular

Pulmonary vein flow

Systolic dominance

Systolic blunting

Systolic flow reversal

Definitive(Hard) Parameters

Quantitative Parameters

Mild MR Mod MR Severe MR

Vena contracta width (cm)

<0.3 0.3-0.69 ≥0.7

Regurgitant volume (mL/beat)

<30 30-44 To 45-59 ≥60

Regurgitant fraction (%)

<30 30-39 to 40-49 ≥50

EROA (cm2) <0.20 0.20-0.29 to 0.30-0.39

≥0.40

What does these measurement mean ?

PISA is in LV and ERO is in LA

Proximal isovelocity surface area=PISA

• Fluid dynamic theory predicts that as flow approaches a circular finite orifice, it forms a series of concentric hemispheric shells with gradually decreasing area and increasing velocity. Arrows refer to direction of flow as it approaches the proximal isovelocity surface area region. R is the radius of a hemispherical shell.With principle of conservation of mass, flow through the regurgitant orifice = flow through the isovelocity surface = 2πr2 × aliasing velocity

conservation of mass

• Flow through the regurgitant orifice = flow through the isovelocity surface = 2πr2 × aliasing velocity=Regurgitant orifice X MR jet velocity• Regurgitant orifice =2πr2 × aliasing velocity/MR jet velocity• Regurgitant volume=Regurgitant orifice X MR jet VTI• Regurgitant fraction=Regurgitant volume/TSV• TSV=Regurgitant volume+LVOT VTI X LVOT area=Stroke volume can be

calculated as: (end-diastolic volume—end-systolic volume)/end-diastolic volume .

• Effective orifice area=Vena contracta area

Still need clues !

• Flow A=MR regurgitation volume +B flow(LVOT flow)

Adjusting Nyquist limit to perfect PISA

• Baseline shifting of the Nyquist limit toward the direction of the regurgitant flow results in a larger proximal isovelocity surface area zone for optimal measurement of the proximal isovelocity surface area region radius (right panel).

Angle correction(α)

• It is required in eccentric MR like flail anterior or posterior leaflet• Angle correction is performed by multiplying the surface area

calculation by α/180, where α is the angle between the mitral leaflet and the end of the PISA region confined by the LA wall• This correction does introduce new error • Angle correction is for bench discussion but not used clinically

• Radius (r) of PISA• Convergence angle(α)• Proximal convergence field for

central (left) and eccentric (right) convergence

• The convergence angle is obtained by projecting the most distal point of the isovelocity contour onto the constraining wall.

Aliasing velocity Nyquist limit =19cm/sec

Effect of PISA radius on PISA shape and flow calculation

• Isovelocity hemispheres proximal to a mitral regurgitant orifice (left) at three different distances from the orifice and corresponding plots of calculated flow rates (Qc) as a function of distance from the orifice. The dashed line represents the actual regurgitant flow rate

Validity

Yes and No

Disadvantage• If the valve orifice is not flat or

circular, the flow convergence zone will not be hemispheric, thus PISA radius cannot be used for the calculation of the regurgitant flow.• Systolic changes of regurgitant flow

are not taken into account.• In assessment of regurgitant

flow/volume, errors in calculation of PISA radius are squared.

Advantage• Independent of hemodynamic

factors, aetiology of the disease and presence of multiple valve alterations.• It can be used in central as well as in

eccentric jets (although less accurate)• It is a quantitative estimation of

lesion severity and volume overload with an acceptable reproducibility

Calculation

One page

Bench to Bedside

• Severe primary MR, class I indications for surgical intervention • Symptomatic • LV decompensation

• LV ejection fraction of 0.6 or less• LV end-systolic diameter of 40 mm or more

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