Mitral Regurgitation
c

Assessments of Severity

Mild

Severe

Qualitative & Semi-Quantitative

Qualitative & Semi-Quantitative

Qualitative & Semi-Quantitative

Mitral leaflet

Abnormal, flail, restriction, perforation or wide coaptation defect

LV size (chronic primary MR)

Dilated indicates severe primary MR, although normal size does not rule out severe MR

LA size (chronic primary MR)

Dilated

PISA at Nyquist 40cm/s (cm)

≥1.0

Vena contracta width (cm)

≥0.7

Biplane VC width (cm)

≥0.8

Pulmonary vein systolic flow

Flow reversal

MV inflow VTI/LVOT VTI

>1.4

Dominant mitral inflow wave (cm/s)

E-wave >1.5

Jet area/LA (%)

Large, >50

Flow convergence

Large & holosystolic

CW Doppler

Similar in density to forward flow. Triangular waveform suggests torrential or acute severe MR

Quantitative

Quantitative

Quantitative

Regurgitant orifice area (cm²)

≥0.40

Regurgitant volume (mL)

≥60

Regurgitant fraction (%)

≥50

Vena Contracta Width

What are the principles of using vena contracta width in the assessment of MR?

Vena contracta width is a measurement of the smallest area of the blood flow jet as it exits a valve, as shown by colour doppler. This corresponds to the effective orifice area calculated for valves using the continuity equation.

Which views are used to assess vena contracta width in MR?

• It is preferable to use a zoom mode to optimize visualization of the vena contracta and facilitate its measurement
• The follow views can be used to obtain the measurement:

Transthoracic
• Parasternal long-axis
• Parasternal short-axis view,
• Apical (if parasternal images are inadequate)

Transoesophageal
• TEE 120° long-axis view

How is vena contracta width measured in the assessment of MR?

  1. Ensure the ultrasound beam perpendicular to flow
  2. Adjust the focus setting to the level of the MV
  3. Zoom the image on the mitral valve
  4. Ensure the Colour Doppler sector is narrow around the valve (to maximize lateral & temporal resolution)
  5. Set the colour scale to 50-70 cm/sec
  6. Scroll frame by frame through the systolic cycle for the largest jet area
  7. Measure the vena contracta – the narrowest portion of the jet – in a plane orthogonal to the line of leaflet coaptation.
  8. Recommended to average measurements over at least two to three beats

Which values are used to grade severity of MR using vena contracta width?

Criteria are applicable only for holosystolic MR with preferably circular regurgitant orifice

Mild

Moderate

Severe

<0.3
0.30 – 0.69
≥0.7

What are the advantages of vena contracta width in the assessment of MR?

  • Simple measure of orifice area
  • Valuable in eccentric jets as well
  • Not dependent on pulse repetitive frequency
  • No correction for angle or convergence walls
  • Not affected by other valve involvement
  • If the orifice is fixed then the size of the vena contracta is independent of driving pressure and flow rate
  • Not affected by loading conditions

What are the limitations of vena contracta width in the assessment of MR?

  • No temporal information (as needed in MVP and hypertrophic cardiomyopathy)
  • Can overestimate MR when flow is not holosystolic (especially late systolic prolapse
  • Can underestimate elliptical shape orifices – may need biplane or triplane measurement to get it right
  • Multiple jets are a problem and can underestimate MR – however their respective values are not additive
  • Small errors can make a big difference due to the relatively small values of the vena contracta width.
  • In dynamic regurgitation, orifice vena contracta may change with hemodynamics or during the cardiac cycle
  • The convergence zone is flatter with higher aliasing velocities and becomes more elliptical with lower aliasing velocities. the aliasing velocity is set between 20 and 40 cm/s.
  • Another limitation is with regard to variation in the regurgitant orifice during the cardiac cycle. This is particularly important in MVP where the regurgitation is often confined to the latter half of systole. the precise location of the regurgitant orifice can be difficult to judge, which may cause an error in the measurement of the proximal isovelocity surface area (PISA) radius.

Related Pages: