Presentation includes echocardiographic assessment of aortic valve stenosis

1. AORTIC STENOSIS

3. Normal Aortic valve
 Three cusps, crescent shaped
3 commissures
3 sinuses
supported by fibrous annulus
▪ 3.0 to 4.0 cm2

4. Aortic stenosis- Causes
Most common
• Bicuspid aortic valve with calcification
• Senile or Degenerative calcific AS
• Rheumatic AS
Less common
• Congenital
• Type 2 Hyperlipoproteinemia
• Onchronosis

5. Etiology & Morphology

6. Bicuspid Aortic valve
▪ Two cusps are seen in systole with only
two commissures framing an elliptical
systolic orifice(the fish mouth
appearance).
▪ Diastolic images may mimic a tricuspid
valve when a raphe is present.

7. Bicuspid Aortic valve
Fusion of the right and left coronary cusps (80%)
Fusion of the right and non-coronary cusps(20%)
Schaefer BM et al. Am J Cardiol 2007;99:686–90
Schaefer BM et al.Heart 2008;94:1634–1638.

8. Types of Bicuspid Aortic valve
J Am Coll Cardiol Img. 2013;6(2):150-161. doi:10.1016/j.jcmg.2012.11.007

9. Bicuspid Aortic valve
▪ Parasternal long-axis echocardiogram may show
– Symmetric closure line
– Systolic doming
– Diastolic prolapse of the cusps
▪ In adults, stenosis typically is due to calcific
changes, which often obscures the number of cusps,
making determination of bicuspid vs. tricuspid valve
difficult

10. Bicuspid Aortic valve

11. Unicuspid & Quadricuspid valves

12. Which of the following is a predictor of outcome (death or need for
valve replacement due to symptoms) in patients with severe,
asymptomatic aortic stenosis?
A. Patient age
B. Diabetes mellitus
C. Bicuspid aortic valve morphology
D.The presence of moderate to severe calcification
Question

13. Calcific Aortic Stenosis
• Nodular calcific masses on aortic side of cusps
• No commissural fusion
• Free edges of cusps are not involved
• stellate-shaped systolic orifice
o The degree of valve calcification is a predictor of clinical
outcome.

14. Calcific Aortic Stenosis
▪ Parasternal long axis view
showing echogenic and
immobile aortic valve
▪ Parasternal short-axis view
showing calcified aortic valve
leaflets. Immobility of the cusps
results in only a slit like aortic
valve orifice in systole

15. Aortic sclerosis
▪ Thickened calcified cusps with
preserved mobility
▪ Typically associated with peak
doppler velocity of less than 2.5
m/sec

16. Rheumatic aortic stenosis
▪ Characterized by
▪ Commissural fusion
▪ Triangular systolic orifice
▪ Thickening & calcification
▪ Accompanied by rheumatic mitral valve changes.

17. Subvalvular aortic stenosis
Thin discrete membrane consisting of endocardial fold
and fibrous tissue
A fibromuscular ridge
Diffuse tunnel-like narrowing of the LVOT
Accessory or anomalous mitral valve tissue.

18. Supravalvular Aortic stenosis
• Type I -Thick, fibrous ring above the aortic
valve with less mobility and has the easily
identifiable 'hourglass' appearance of the
aorta.
• Type II -Thin, discrete fibrous membrane
located above the aortic valve
• Type III- Diffuse narrowing

19. Stages ofValvular AS

20. Stages of Valvular AS

21. Should Aortic Valve Area Be Indexed?
▪ Indexing valve area is important in children, adolescents,
and small adults
BSA < 1.5 m2
BMI < 22 kg/m2
height < 135 cm
▪ In obese patients, valve area does not increase with excess
body weight, and indexing for BSA is not recommended

25. ▪ Valve anatomy, etiology
▪ Exclude other LVOTO
▪ Stenosis severity
▪ jet velocity
▪ mean pressure gradient
▪ AVA – continuity equation
▪ LV – dimensions/hypertrophy/EF/diastolic fn
▪ Aorta- aortic diameter/ assess COA
▪ AR – quantification if more than mild
▪ MR- mechanism & severity
▪ Pulmonary pressure
Approach

26. 2D Echo-Long axis view
Diastole Systole

27. 2D Echo-Short axis view
Diastole Systole
Y or inverted Mercedes-Benz sign

28. Which of these M-mode images is suggestive of
valvular aortic stenosis?

29. Limitations
Single dimension
Asymmetrical AV involvement
Calcification / thickness
↓ LV systolic function
↓ CO status
M Mode- Aortic Stenosis

30. Doppler assessment of AS
The primary haemodynamic parameters recommended
• Peak transvalvular velocity
• Mean transvalvular gradient
• Valve area by continuity equation.
(EAE/ASE Recommendations for Clinical Practice 2008)

31. Peak Transvalvular velocity
• Continuous-wave Doppler ultrasound
• Multiple acoustic windows
• Apical and suprasternal or right parasternal
most frequently yield the highest velocity
• rarely subcostal or supraclavicular windows
may be required
• Three or more beats are averaged in sinus rhythm,
with irregular rhythms at least 5 consecutive beats

32. The Effect of Angle

34. Doppler Equation- Rearranged
F0:Transmitted frequency of
ultrasound
V: velocity of blood.
C: Speed
q: intercept angle between the
interrogation beam and the target

36. • AS jet velocity is defined as the highest velocity signal
obtained from any window after a careful examination
• Any deviation from a parallel intercept angle results in
velocity underestimation
• The degree of underestimation is 5% or less if the
intercept angle is within 15⁰ of parallel.
• ‘Angle correction’ should not be used because it is likely
to introduce more error given the unpredictable jet
direction.
Peak Transvalvular velocity

37. Which of these continuous-wave spectral Doppler tracings is
most suggestive of aortic stenosis?

38. • The shape of the CW Doppler velocity curve is helpful
in distinguishing the level and severity of obstruction.
• With severe obstruction, maximum
velocity occurs later in systole and the
curve is more rounded in shape
• With mild obstruction, the peak
is in early systole with a triangular
shape of the velocity curve
Peak Transvalvular velocity

39. ▪ The shape of the CWD velocity curve also can
be helpful in determining whether the
obstruction is fixed or dynamic
▪ Dynamic sub aortic obstruction shows a
characteristic late-peaking velocity curve, often
with a concave upward curve in early systole
Peak Transvalvular velocity

40. Mean Transvalvular Gradient
▪ The difference in pressure between the
left ventricle and aorta in systole
▪ Gradients are calculated from velocity
information
▪ The relationship between peak and
mean gradient depends on the shape of
the velocity curve.

41. ▪ Bernoulli equations
ΔP max =4 (v² max- v2
proximal)
▪ The maximum gradient is calculated from
maximum velocity
ΔP max =4v² max
▪ The mean gradient is calculated by averaging the
instantaneous gradients over the ejection period
Mean Transvalvular Gradient

42. ▪ The simplified Bernoulli equation assumes that the proximal
velocity can be ignored
▪ When the proximal velocity is over 1.5 m/s or the aortic velocity
is ,3.0 m/s, the proximal velocity should be included in the
Bernoulli equation
ΔP max =4 (v² max- v2
proximal)
▪ Example
V2 = AS velocity = 4 m/s
V1 = LVOT velocity = 2 m/s
4 (V22 −V12) = 48 mmHg
4V22 = 64 mmHg (overestimation by 33%)
Mean transvalvular gradient

44. Comparing pressure gradients calculated from
doppler velocities to pressures measured at cardiac
catheterization.
Not simultaneous
Non-physiologic

45. Comparing pressure gradients calculated from
doppler velocities to pressures measured at cardiac
catheterization.
Currie PJ et al. Circulation 1985;71:1162-1169

47. Aortic valve area (Continuity equation)

48. A. Severely decreased LV stroke volume
B. Severe aortic regurgitation
C. Severe mitral regurgitation
D. Severe dynamic LVOT obstruction (SAM)
E. Severe pulmonary hypertension
For which of the following situations, with AS, is it invalid to use
continuity between the LVOT and the aortic valve to calculate
aortic valve area?
Question

49. ▪ Calculation of continuity-equation valve area requires three
measurements
▪ AS jet velocity by CWD
▪ LVOT diameter for calculation of a circular CSA
▪ LVOT velocity recorded with pulsed Doppler.
Aortic Valve Area (Continuity Equation)

50. Question
A. LVEF = 25%
B. Patient also has severe MR
C. Sample volume too close to AV for LVOTTVI measurement
D. LV diastolic diameter 45 mm
E. LVOT diameter measurement too small
For a patient with aortic stenosis you obtain MG = 30 mmHg
and AVA = 0.6 cm2 Which of the following would not explain
this discrepancy?

52. ▪ LVOT diameter and velocity should be measured at the
same distance from the aortic valve.
▪ When the PW sample volume is optimally positioned,
the recording shows a smooth velocity curve with a
well-defined peak.
Aortic Valve Area (Continuity Equation)

54. Question
The largest source of error in calculation of aortic
valve area by the continuity equation is:
A. Peak velocity across the aortic valve
B. LVOT diameter
C. Peak velocity across the LVOT
D.Time–velocity integral of aortic valve CW spectral Doppler display
E.Time–velocity integral of LVOT PW spectral Doppler display

55. LVOT Diameter

56. ▪ Well validated - clinical & experimental studies.
Zoghbi WA et al. Circulation 1986;73:452-9.
Oh JK et al. J Am Coll Cardiol 1988;11:1227-34.
▪ Measures the effective valve area, the weight of the evidence
now supports the concept that effective, not anatomic, orifice
area is the primary predictor of clinical outcome.
Baumgartner et al. J Am Society Echo 2009; 22,1 , 1-23.
Aortic valve area (Continuity equation)

58. Limitations Of Continuity-equation Valve Area
▪ Intra- and interobserver variability
▪ AS jet and LVOT velocity 3 to4%.
▪ LVOT diameter 5% to 8%.
▪ When sub aortic flow velocities are abnormal
SV calculation at this site are not accurate
▪ Sample volume placement near to septum or
anterior mitral leaflet

59. ▪ Observed changes in valve area with
changes in flow rate
▪ AS and normal LV function, the effects
of flow rate are minimal
▪ This effect may be significant in
presence concurrent LV dysfunction.
Limitations Of Continuity-equation Valve Area

60. Serial measurements
During follow-up any significant changes in results
should be checked in detail:
Make sure that aortic jet velocity is recorded from the
same window with the same quality (always report the
window where highest velocities can be recorded).
 when AVA changes, look for changes in the different
components incorporated in the equation.
 LVOT size rarely changes over time in adults.

61. ▪ Another approach to reducing error related to LVOT
diameter measurements is removing CSA from the
simplified continuity equation.
▪ This dimensionless velocity ratio expresses the size of
the valvular effective area as a proportion of the CSA
of the LVOT.
Velocity ratio=VLVOT/VAV
▪ In the absence of valve stenosis, the velocity ratio
approaches 1, with smaller numbers indicating more
severe stenosis.
Velocity ratio

62. Aortic valve area -Planimetry
▪ Planimetry may be an acceptable alternative
when Doppler estimation of flow velocities is
unreliable
▪ Planimetry may be inaccurate when valve
calcification causes shadows or reverberations
limiting identification of the orifice
Marie Arsenault, et al. J. Am. Coll. Cardiol. 1998;32;1931-1937

63. Aortic valve area - Planimetry

64. 3D Planimetry

65. Modified continuity equation (CE)
3D echo assessment of SV
• 3D is more accurate than Doppler CE and
than 2D volumetric methods to calculate
AVA
• Limitations: arrhythmias, significant mitral
regurgitation

66. Maximal aortic cusp separation (MACS)
Vertical distance between right CC and non CC during systole
M Mode- Aortic Stenosis
Aortic valve area MACS Measurement Predictive value
Normal AVA >2Cm2 Normal MACS >15mm 100%
AVA>1.0 > 12mm 96%
AVA< 0.75 < 8mm 97%
Gray area 8-12 mm …..
DeMaria A N et al. Circulation.Suppl II. 58:232,1978

67. Experimental descriptors of
stenosis severity
(Level 3 EAE/ASE Recommendations -not recommended for routine clinical use)

68. Valve resistance
▪ Relatively flow-independent measure of stenosis
severity
▪ Depends on the ratio of mean pressure gradient and
mean flow rate
▪ Resistance = (ΔPmean /Qmean) × 1333
▪ There is a close relationship between aortic valve
resistance and valve area
▪ The advantage over continuity equation not
established

69. Left ventricular stroke work loss
▪ Left ventricle expends work during systole to keep
the aortic valve open and to eject blood into the
aorta
SWL(%) = (100×ΔPmean)/ ΔPmean+SBP
▪ A cutoff value more than 25% effectively
discriminated between patients experiencing a
good and poor outcome.
Kristian Wachtell. Euro Heart J.Suppl. (2008) 10 ( E), E16–E22

70. Energy loss index
Damien Garcia.et al. Circulation. 2000;101:765-771.
▪ Fluid energy loss across stenotic aortic valves is
influenced by factors other than the valve effective
orifice area .
▪ An experimental model was designed to measure EOA
and energy loss in 2 fixed stenoses and 7 bioprosthetic
valves for different flow rates and 2 different aortic sizes
(25 and 38 mm).
– EOA and energy loss is influenced by both flow rate
and AA and that the energy loss is systematically
higher (15±2%) in the large aorta.
▪ Damien Garcia.et al. Circulation. 2000;101:765-771.

71.  Energy loss coefficient (EOA × AA)/(AA - EOA) accurately
predicted the energy loss in all situations .
 It is more closely related to the increase in left ventricular
workload than EOA.
 To account for varying flow rates, the coefficient was indexed
for body surface area in a retrospective study of 138 patients
with moderate or severe aortic stenosis.
 The energy loss index measured by Doppler echocardiography
was superior to the EOA in predicting the end points
 An energy loss index #0.52 cm2/m2 was the best predictor of
diverse outcomes (positive predictive value of 67%).
Energy loss index
Damien Garcia.et al. Circulation. 2000;101:765-771.

72. Effects of concurrent
conditions on assessment
of severity

73. Effect of concurrent conditions ……
▪ Left ventricular hypertrophy
▪ Small ventricular cavity & small LV ejects a small SV so
that, even in severe AS the AS velocity and mean
gradient may be lower than expected.
▪ Continuity-equation valve area is accurate in this
situation
 Left ventricular systolic dysfunction
LVEF often underestimates myocardial dysfunction
Global longitudinal function is more sensitive to identify
intrinsic myocardial dysfunction (i.e. GLS < 16%)

74. ▪ Hypertension
– 35–45% of patients
– primarily affect flow and gradients but less AVA
measurements
– Control of blood pressure is recommended
– The echocardiographic report should always include a
blood pressure measurement
Effect of concurrent conditions contd…

75. ▪ Aortic regurgitation
– About 80% of adults with AS also have aortic
regurgitation
– High transaortic volume flow rate, maximum
velocity, and mean gradient will be higher
than expected for a given valve area
– In this situation, reporting accurate
quantitative data for the severity of both
stenosis and regurgitation
Effect of concurrent conditions contd…

76. ▪ Mitral valve disease
– With severe MR, transaortic flow rate
may be low resulting in a low gradient
.Valve area calculations remain
accurate in this setting
– A high-velocity MR jet may be mistaken
for the AS jet.Timing of the signal is the
most reliable way to distinguish
Effect of concurrent conditions contd…

77. ▪ High cardiac output
▪ Relatively high gradients in the
presence of mild or moderate AS
▪ The shape of the CWD spectrum with
a very early peak may help to
quantify the severity correctly
▪ Ascending aorta
▪ Aortic root dilation
▪ Coarctation of aorta
Effect of concurrent conditions contd…

79. Exercise Echocardiography
▪ Should not be performed in symptomatic patients
▪ Can be useful in asymptomatic patients
Criteria For Positive Exercise ECG (less accurate in elderly subjects > 70 y)
o symptom development +++ (recommendation for surgery class IC)
o abnormal blood pressure response: lack of rise (≤ 20 mmHg) or fall in
blood pressure ++ (recommendation for surgery class IIaC)
o ST changes or complex ventricular arrhythmias (minor criteria)

80. Exercise Echocardiography
Quantify exercise-induced changes
o Mean pressure gradient
o Contractile reserve (changes in LV ejection fraction/strain)
o Pulmonary arterial systolic pressure (PASP)
Criteria of poor outcome with exercise echo
o Increase in mean aortic gradient > 18–20 mmHg (recommendation for surgery class IIbC)
o Weak change in LV ejection fraction
o Pulmonary hypertension (PASP > 60 mmHg)

81. Rules for Quantitation of Aortic Stenosis by
Echocardiography
• CW Doppler from multiple windows
• See the base of the aortic cusps before you measure
the LVOT diameter
• For the PW exam, go with the blue flow
• Compare calculated SVI to LV size and EF
• Check for concordance between AVA and MG, or explain
discordance

82. Thanks for your patience listening

83. ▪ The conversion of potential energy to kinetic energy across
a narrowed valve results in a high velocity and a drop in
pressure.
▪ Distal to the orifice, flow decelerates again. Kinetic energy
will be reconverted into potential energy with a
corresponding increase in pressure, the so-called PR
Pressure recovery

84. ▪ Pressure recovery is greatest in stenosis with gradual distal
widening
▪ Aortic stenosis with its abrupt widening from the small
orifice to the larger aorta has an unfavorable geometry for
pressure recovery
PR= 4v²× 2EOA/AoA (1-EOA/AoA)
Pressure recovery