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Echocardiography assessment of Aortic Regurgitation severity
1. Assessment of severity of aortic regurgitation by
echocardiography
Presenter
DR PRAVEEN GUPTA
Moderator
DR AJIT ANANTHAKRISHNA
PILLAI
Date - 2/08/2016
Department of Cardiology,
JIPMER
Pondicherry, India
2. Introduction
Aortic Regurgitation (AR) is diastolic reflux of blood from the aorta
to the LV
Caused by
Malfunction of the aortic valve leaflets
Dilation of the aortic root and annulus
Combination of these factors
Aortic root disease >50% of all Aortic valve replacement (AVRs)
3. Evaluating the Severity of Aortic Regurgitation
Effective
regurgitant orifice area
Volume or fraction of regurgitant
flow
Size or extent of the regurgitant jet within the LV
4. Evaluating the Severity of Aortic Regurgitation
By Colour flow imaging
Record jet in multiple imaging
planes to provide a three-
dimensional assessment of its
dimensions
Area of the jet,estimated by
planimetry.
Parasternal long-axis view,
the height of the jet just below
the valve measured
This dimension can also be
expressed as a percentage of
left ventricular outflow tract
dimension to provide an
estimate of severity
Three examples of aortic regurgitation are
provided, all taken from the parasternal long-
axis view using color Doppler. Mild (A),
moderate (B), and severe (C) aortic
regurgitation are illustrated.
5. Evaluating the Severity of Aortic Regurgitation
by colour flow imaging
The greater the percentage is of the left ventricular outflow tract that is
filled by the jet at its origin, the more severe the regurgitation.
A jet that occupies > 60% of the LVOT (either height or area) indicates
severe AR.
A similar approach uses the short-axis view with the imaging plane
positioned immediately proximal to the aortic valve .
The outflow tract is directly visualized as a circular space, and the
regurgitant jet is visualized as a two-dimensional shape within this circle
6. Using transesophageal echocardiography, the jet can be visualized from the
short-axis view, just below the aortic valve. A: The regurgitant orifice is visualized
with two-dimensional imaging. B: Color Doppler is used to demonstrate flow
within the regurgitant orifice. C: The regurgitant orifice area is measured by
planimetry (0.75 cm2).
7. Evaluating the Severity of Aortic Regurgitation
By Colour flow imaging
A:The schematic demonstrates how the dimensions of the color jet of aortic
regurgitation can be used to estimate severity. B: The jet height just below the aortic
valve (arrows) can be measured and compared with the dimension of the left
ventricular outflow tract. This is a useful measure of severity
8. Evaluating the Severity of Aortic Regurgitation
By colour flow imaging
Both length of the jet and area of jet method conveys unreliable
information about overall severity.
The best dimensional predictors of angiographic severity are, jet area
indexed to the LV short-axis area (parasternal short-axis view) and jet
diameter indexed to LVOT diameter immediately proximal to the valve
(paraternal long axis view)
9. Limitations to the use of color flow mapping
Eccentric jets tends to alter the perception of severity
Size of the jet is instrument dependent.
Changes in gain, color scale, transducer frequency, and wall filters
affect the jet appearance
Jet is greater from an apical view compared with a parasternal view
Regurgitant orifice area in chronic aortic regurgitation changes (and
usually decreases) during diastole, and it lead to color Doppler to
overestimate severity because the visualized jet area would reflect
peak rather than mean orifice area
10. Vena Contracta
• Narrowest portion of a jet that occurs at or just downstream
from the orifice
• Measure of the effective regurgitant orifice area (EROA)
• Independent of flow rate and driving pressure
• Small errors in measurement lead to a large percent error
and misclassification of the severity of regurgitation
11. Vena Contracta
Vena contracta width of ≥ 6 mm
correlates well with severe AR
(sensitivity 95%, specificity 90%)
Vena contracta width of < 3 mm
specific for mild AR.
Enriquez-Sarano M, et al. NEJM
2004; 351: 1539-1546
.
12. Proximal Isovelocity Surface Area (PISA)
by colour flow
Acceleration of flow occurs proximal
to the valve plane with a series of
isovelocity “surfaces” leading to the
high-velocity jet in the regurgitant
orifice.
Velocity for a PISA =aliasing velocity
where a distinct red-blue interface
seen (at this interface, velocity is
equivalent to Nyquist limit).
Surface area of the PISA region is
2πr2
13. Proximal Isovelocity Surface Area
Peak regurgitant flow
obtained by multiplying
surface area by aliasing
velocity
Effective regurgitant orifice
area (EROA) is peak
regurgitant flow divided by
peak velocity obtained by CW
Doppler.
14. PISA
Limitations
Isovelocity contour flattens as it approaches the orifice,
underestimating flow
Proximal structures can distort the isovelocity contour
Sensitive to errors in radius measurement
10% error in radius leads to 21% error in flow
Multiple measurements
Technically challenging
15. Evaluating the Severity of Aortic Regurgitation by
Continuous Doppler
The simplest approach compares the density or darkness of the envelope of the antegrade
aortic flow and the regurgitant jet.
Mild aortic regurgitation the velocity of the regurgitant jet remains relatively high and
the envelope appears flat.
With more severe aortic regurgitation, steeper slope of the Doppler envelope.
The deceleration of jet velocity can be described as either the slope or the pressure
half-time of the jet
Factors, including aortic compliance, blood pressure, and left ventricular
size and compliance affect these measures
16. Evaluating the Severity of Aortic Regurgitation
by Continuous Wave Doppler
This schematic illustrates how hemodynamic changes are reflected in the Doppler velocity tracing.
Left: Mild aortic regurgitation (AR) is associated with a fairly flat contour of the regurgitant jet.
Right: As severity increases, the slope of the jet becomes steeper. These changes are the result of
the instantaneous pressure gradient between the aorta and left ventricle during diastole
17. Pressure Half-Time
Rate at which aortic and LV pressures equalize
Most relaible in the setting of acute regurgitation
Rapid rate of decline in aortic pressure is reflected in steeper diastolic
deceleration slope
A pressure half-time less than 250 milliseconds or a slope greater than 400
cm/sec2 are indicators of severe aortic regurgitation
18. Evaluating the Severity of Aortic Regurgitation
Pressure Half-Time
Continuous wave Doppler imaging of the aortic regurgitation (AR) jet permits
quantitation of both slope and pressure half-time (P½t). Top: An example of
mild aortic regurgitation is demonstrated. The slope is relatively flat and the
P½t is long. Bottom: An example of severe aortic regurgitation demonstrates a
much steeper slope and shorter P½t.
19. Pressure Half-Time
For a given severity of AR, P1/2 will be shortened by elevated LVEDP or
vasodilator therapy that reduces AR
With acute AR-triangular-shaped CW-Doppler with linear deceleration
slope from maximum velocity to baseline
21. Limitations of pressure half-time assessment
Pressure half-time sensitive to chronicity of AR
Acute AR leads to much shorter values than chronic AR when LV is dilated
with increased compliance
Pressure half-time varies with SVR
Vasodilators may shorten the pressure half-time even as the aortic
regurgitant fraction improves
22. Evaluating the Severity of Aortic Regurgitation
Regurgitant Volume or Fraction
Pulsed Doppler imaging
Stroke volume at any valve annulus is derived as the product of CSA and
VTI of flow at the annulus
In the absence of regurgitation, SV determinations at different sites (LVOT,
mitral annulus, pulmonic annulus) should be equal
Mild: < 30 cc (< 30%)
Mild-moderate: 30-44 cc (30-39%)
Moderately severe: 45-59 cc (40-49%)
Severe: ≥60 cc (≥50%)
23. Evaluating the Severity of Aortic Regurgitation
Regurgitant Volume or Fraction
Stroke volume can be measured
through any valve within the heart.
This schematic demonstrates how
stroke volume can be calculated at
the level of the aortic valve and
mitral valve . The difference in
stroke volume represents the
regurgitant volume. In addition,
the regurgitant fraction can be
calculated
24. Regurgitant Volume or Fraction
Limitation
Cannot be used in presence of shunts
Sensitive to small measurement errors
Requires multiple measurements,
Assumes no regurgitation at reference valve
Limited quantitative information
Affected by sample volume location
25. Evaluating the Severity of Aortic Regurgitation
Pulsed Doppler imaging
Severe AR - diastolic flow reversal in the descending aorta
Nonquantitative approach using pulsed Doppler imaging
Presence of holodiastolic flow reversal in the descending aorta has been
correlated with severe aortic regurgitation
False positives may occur if a PDA is present
This parameter is dependent on vessel compliance and the location of the
sample volume
26. Evaluating the Severity of Aortic Regurgitation
by M-mode echocardiography and two-dimensional imaging
End-diastolic
End-systolic LV dimensions
Ejection fraction
Fractional shortening
End-systolic wall stress
LV systolic dysfunction
Increase in end-systolic
dimension
27. Criteria for Severe AR
Jet width >_65% of LVOT
Vena contracta >0.6 cm
Holodiastolic flow reversal in the proximal abdominal aorta
Rvol>_60 ml/beat
RF>50%
ERO>_0.3 cm2
Angiography grade 3+ to 4+
Evidence of LV dilation
28. Take Home Message
The best dimensional predictors of angiographic severity are jet area
indexed to the LV short-axis area (parasternal short-axis view) and jet
diameter indexed to LVOT diameter immediately proximal to the valve
(paraternal long axis view)
Jet length is not a reliable index of severity
The pressure half-time is most relaible in the setting of acute regurgitation
Holodiastolic flow reversal is a marker of at least moderate regurgitation
