Comprehensive evaluation based on ASE EAC focused update 2017

1. ECHOCARDIOGRAPHIC
EVALUATION OF AORTIC
STENOSIS
ASWIN R.M.
16.03.2018

2. AS –ECHO EVALUATION
Anatomy
Severity
Assessment
LV Function
Associated
conditions

3. AS –ECHO EVALUATION
• Valve & Aorta Morphology
• LVOT dimension
• Planimetry
2D
• Velocity
• Gradient
• Associated AR
Doppler
• Morphology
• PlanimetryTEE & 3D
• Severity assesment
• LVEFM mode

4. PLAX
RA
AO
LA
• Leaflet mobility
• Leaflet thickening
• Asymmetric closure
line
• Thickened closure line
• LVOT Dimension
• MACS
• Supravalvular stenosis
• Subvalvular membrane

5. PSAX
No of cusps
Calcification
Orifice shape
Orifice size (planimetry)

6. APICAL
Doppler assesment
LV function

7. SUPRASTERNAL

8. MORPHOLOGY AND ETIOLOGY
Most common
 Bicuspid aortic
 Senile or
Degenerative
calcific AS
• Rheumatic AS
Less common
• Congenital
• Type 2
Hyperlipoprote
inemia
• Onchronosis

9. Anatomic evaluation
 Combination of short and long axis images to identify
 Number of leaflets
 Leaflet mobility
 Thickness
 Calcification
 Combination of imaging and doppler -determination
of the level of Obstruction
 Subvalvular
 Valvular
 Supravalvular
 Transesophageal echocardiography may be helpful
when image quality is suboptimal.

10. 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

11. CALCIFIC AORTIC STENOSIS
PLAX showing echogenic and
immobile aortic valve
PSAX showing calcified aortic
valve leaflets.
Immobility of the cusps results
only a slit like orifice in systole

12. SEVERE CALCIFICATION

13. GRADING CALCIFICATION
 Semi-quantitative
 Degree of valve calcification -
predictor of clinical outcome
 Heart failure
 Need for AVR
 Death
Mild
Few areas of dense echogenicity with little acoustic shadowing
Moderate
Multiple larger areas of dense echogenicity
Severe
Extensive thickening and increased echogenicity with a prominent
acoustic shadow

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

15. RHEUMATIC AS
 Commissural fusion
 Triangular systolic orifice
 Thickening and
calcification mostly
along the edges of the
cusps.
 Concomitant
involvement of mitral
valve seen

16. RHEUMATIC VS CALCIFIC

17. Bicuspid aortic valve
 Fusion of the right and left
coronary cusps (80%)
 Fusion of the right and
non-coronary cusps(20%)
 Rarely
 Fusion of the left and non-
coronary cusps
 Valves with two equally
sized cusps (“true”bicuspid
valve)

18. Bicuspid Aortic valve PSAX
 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.

19. Bicuspid Aortic valve PLAX
 An asymmetric
closure line
 Systolic doming
 Diastolic prolapse of
the cusps
 Less specific than a
short-axis systolic
image

20. Bicuspid Aortic valve
 In children, valve may be stenotic Without
extensive calcification.
 Or may be functionally normal except for
systolic dooming – but needs follow up
 Rarely unicuspid or quadracuspid
 In adults, stenosis is due to calcific changes
 Often obscures the number of cusps, -
bicuspid vs tricuspid is determination difficult
 Loot for aortic root dilataton & AR

21. SUPRAVALVULAR AS
 Type I(Hourglass type) –Thick
fibrous ring above the aortic valve
with less mobility
 Type II - Thin, discrete fibrous
membrane above the aortic valve
membrane usually mobile and may
demonstrate doming during systole
 Type III- Diffuse narrowing

22. SUBVALVULAR AS
Distinguished from valvular stenosis based on the site of the
increase in velocity seen with colour or pulsed Doppler
 (1)Thin discrete membrane
consisting of endo cardial fold
and fibrous tissue
 (2) A fibro muscular ridge
 (3) Diffuse tunnel-like narrowing
of the LVOT
 (4) accessory or anomalous
mitral valve tissue.

23. AS STAGING
Stage A
At Risk of as
Stage B
Mild to moderate AS
Stage C
Assymptomatic Severe AS
C1: Without LV
Dysfunction EF>50
C2:With LV
Dysfunction EF <50
Aortic Vmax <2 m/s Mild AS:
 Vmax 2.0–2.9 m/s
 Mean PG<20 mm Hg
Moderate AS:
 Vmax 3.0–3.9 m/s
 Mean PG 20–39 mm
Hg
 Vmax >4 m/s
 Mean PG ≥40 mm Hg
 AVA ≤1.0 cm2 (or AVAi <0.6cm2/m2)
Very severe as is an aortic
 Vmax ≥ 5 m/s
 Mean pg≥60 mm Hg
BAV
Aortic sclerosis
Pseudo severe AS

24. AS STAGING
Stage D
Symptomatic Severe AS
AVA ≤1.0 cm2 (or AVAi <0.6cm2/m2)
D1 D2 D3
Vmax >4 m/s
Mean PG ≥40 mm Hg
Mean PG <40 mm Hg
LVEF< 50
Dobutamine stress +
Mean PG <40 mm Hg
LVEF> 50
SVI < 35 mL/min

25. SEVERITY ASSESMENT
 Echocardiogram is the current standard –
catheterization no longer recommended for
routine evaluation
 Integrative approach in grading the severity
 Doppler
 2D data
 Clinical presentation

26. SEVERITY ASSESSEMENT
Level 1 Recommendation= appropriate in all
patients with AS
Echocardiographic Assessment of Valve Stenosis: EAE/ASE Recommendations for
Clinical Practice
AS peak jet velocity.
Mean transvalvular pressure gradient
Aortic valve area by continuity equation

27. 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

28. PEAK TRANSVALVULAR VELOCITY
 Dedicated small dual-crystal CW transducer is
recommended
 Time scale on the x-axis of 100 mm/s
 Wall filters are set at a high level
 Gain is decreased to optimize identification
of the velocity curve.
 Grey scale is used – Most validated
 Contrast?

29. PEAK TRANSVALVULAR VELOCITY
 Highest velocity From any window.
 Any deviation from a parallel intercept angle
results in velocity underestimation
 5% or less if the intercept angle is within 15⁰ of
parallel.
 ‘Angle correction’ should not be used

30. LOCATION OF HIGHEST VELOCITY
Apical Parasternal Suprasternal Supraclavicular
HIGHEST VELOCITY
Thaden et al. JASE 2015

31. PEAK TRANSVALVULAR VELOCITY
 A smooth velocity
curve with a dense
outer edge and clear
maximum velocity
should be recorded
 Fine linear signals at
the peak of the curve
not be included
 VTI also calculated

32. NO OF MEASUREMENTS
 Sinus Rhythm – 3 Measurements
 Irregular Rhythm – 5 Measurements

33. SHAPE OF IMAGE
The shape of the CW Doppler velocity curve is helpful in
distinguishing the level and severity of obstruction.
Severe obstruction -
maximum velocity
occurs later in systole
and the curve is more
rounded in shape
Mild obstruction - the
peak is in early systole
with a triangular shape
of the velocity curve
Dynamic sub aortic
obstruction - shows
characteristic late
peaking velocity curve,

34. MEAN TRANSVALVULAR GRADIENT
 The difference in pressure between the left ventricle
and aorta in systole
 Gradients are calculated from velocity information
 Simplified Bernoulli equation
ΔP =4V²
 The maximum gradient is calculated from maximum
velocity
ΔP max =4V² max
 The instantaneous gradient at any point of time is
calculated similarly from the instantaneous velocity
 And averaged to get the mean gradient (mean
gradient not derived from mean velocity)

35. BERNOULLI EQUATION
 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)

36. MEAN TRANSVALVULAR GRADIENT
 Peak gradient no additional information
 Mean Gradient - mean of different
instantaneous velocities recorded

37. SOURCES OF ERROR FOR PRESSURE
GRADIENT CALCULATIONS
 Misalignment of jet and ultrasound beam.
 Recording of MR jet
 Any underestimation of aortic velocity results
in an even greater underestimation in
gradients, due to the squared relationship
between velocity and pressure difference
 Neglect of an elevated proximal velocity.

38. MR V/S AR
 MR Jet
 Wider
 More symmetrical
 Not recorded in Suprasternal window
 Superimposed LVOT gradient suggest AS Jet
 For a given patient MR faster than AS

39. CORRELATION WITH CATH
 Doppler Echo - Max instantaneous pressure
difference across the valve,
 Pressure tracings - difference between the peak
left ventricular (LV) and peak aortic pressure

40. PRESSURE RECOVERY
 Potential energy converted to kinetic
energy across a narrowed valve results in a
high velocity and a drop in pressure.
 Distal to the orifice , flow decelerates.
Some amount of Kinetic energy dissipates
as heat (depends on turbulence)
 Remaining will be reconverted into
potential energy with a corresponding
increase in pressure, the so-called PR
 Pressure recovery is greatest in stenosis
with gradual distal widening
 Aortic stenosis with its abrupt widening
from the small orifice to the larger aorta -
unfavorable geometry for PR

41. PRESSURE RECOVERY
PR= 4v²× 2EOA/AoA (1-EOA/AoA)
 The ratio between effective aortic orifice and Ascending
Aortic area determines the magnitude of PR
 The net Pressure gradient ( measured gradient–
pressure recovery) determines the hemodynamic
significance
 Most adults magnitude small to be ignored unless
Aortic width < 3 cm
 Smaller aortas echo evaluation overestimates pressure
gradient

42. PG CATH vs DOPPLER
Currie PJ et al. Circulation 1985;71:1162-1169

43. AORTIC VALVE AREA
Continuity equation
3 measurements
𝐴𝑉𝐴 =
𝐶𝑆𝐴 𝑳𝑽𝑶𝑻 𝑋 𝑽𝑇𝐼
𝑳𝑽𝑶𝑻
𝑽𝑇𝐼
𝑨𝑽

44. LVOT MEASUREMENT
 Zoomed PLAX in mid-systole
 (inner-to-inner) of the septal
endocardium to the anterior
mitral leaflet,
 Parallel to the aortic valve
plane.
 At the annulus or within 0.3–
1.0 cm of the valve orifice
 Average of 3 in sinus & 5 in
irregular rhythms
 CSALVOT = 𝝅(𝒅/𝟐) 𝟐

45. LVOT MEASUREMENT- DIFIFICULTIES
 Calcium extension from annulus to
the base of anterior mitral leaflet.
 ‘Sigmoid septum’ - the LVOT
diameter often appear smaller than
the flow area at the annulus
 Outflow tract not imaged clearly at
mid systole end-diastole
 A practical approach - measure LVOT
in the frame that yields the largest
diameter.
 LVOT not perfectly cylindrical
 If TTE not adequate TEE can be used
to determine LVOT

46. VELOCITY MEASUREMENT
 Apical 5 chamber view or
3chamber view
 PW sample volume is
positioned just proximal to the
aortic valve ideally at the level
of measurement of LVOT dm
 Velocity of valve –CWD

47. VELOCITY MEASUREMENT
 Optimally positioned - smooth velocity curve with a well-
defined peak is obtained.
 Only closing click seen
 Severe calcific AS – may have to move sample volume more
towards apex , measure LVOT dm at same level

48. LIMITATIONS - CONTINUITY EQUATION
 Intra- and inter observer variability (3 variables)
 AS jet and LVOT velocity 3 to4%.
 LVOT diameter 5% to 8%.
 LVOT assumed circular
 MDCT , 3D echo - better
 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
 Observed changes in valve area with changes in flow
rate
 Normal LV function - Effects of flow rate minimal
 Significant in presence concurrent LV dysfunction.

49. SUMMARY
Measurement Severity
Criteria
Advantages Limitations
AS peak
velocity.
> 4 m/s • Strong Predictor of
clinical outcome
• Parallel alignment important
• Overestimates LV energy loss -
small aortas
• Under or over estimates in
presence of SHTN
• Under estimates Low flow cases
• Easy
• Low Inter / Intra observer
variability
• High Specificity
• Strong predictor of
clinical outcome
Mean
pressure
gradient
> 40 mm
Hg
• Comparable to invasive
values
Valve area -
continuity
equation
< 1
cm2(EOA)
<0.6
cm2/m2
BSA (EOAi)
• Relatively flow
independent
• EOA Reflects clinical
severity
• Can be used in almost all
patients
• Same limitations applicable as
above
• Susceptible to measurement
errors
• EOA – over estimated in thin
individuals
• EOAi – under estimated in
obese individuals

50. ALTERNATIVE MEASUREMENTS
Level 2 Recommendations = reasonable when
additional information needed in selected patients
Echocardiographic Assessment of Valve Stenosis: EAE/ASE Recommendations for
Clinical Practice
Simplified continuity equation
Velocity ratio and VTI ratio (dimensionless
index
AVA Planimetry

51. SIMPLIFIED CONTINUITY EQUATION
 Native aortic valve stenosis the shape of
the velocity curve Similar in AV & LVOT
 So ratio of peak velocity mean velocity
and VTI similar.
 𝑨𝑽𝑨 = 𝑪𝑺𝑨 𝑳𝑽𝑶𝑻 X
𝑽
𝑳𝑽𝑶𝑻
𝑽
𝑨𝑽
 This method is less well accepted
because results are more variable than
using VTIs in the equation.
 Also VTI required for calculating stroke
volume

52. VELOCITY RATIO
 To reduce error related to LVOT diameter measurements by
removing CSA from the 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 =
𝑽
𝑳𝑽𝑶𝑻
𝑽
𝑨𝑽
𝑽𝑻𝑰 𝑹𝒂𝒕𝒊𝒐 =
𝑽𝑻𝑰
𝑳𝑽𝑶𝑻
𝑽𝑻𝑰
𝑨𝑽
 The velocity ratio approaches 1 in the absence of valve stenosis
 Smaller numbers indicating more severe stenosis.
 Severe stenosis is suggested VR < 0.25 or less, corresponding to
a valve area 25% of normal

53. AVA PLANIMETRY
 Calculates anatomic orifice area (AOA)
 AOA>EOA
 Acceptable alternative when Doppler
estimation of flow velocities is unreliable
 Inaccurate if valve calcification causes
shadows or reverberations (limits
identification of the orifice)
 TEE has shown better correlation with
Invasive data / continuity equation /MDCT
and is prefered

54. AVA PLANIMETRY

55. EXPERIMENTAL MEASUREMENTS
 Level 3 recommendation, not recommended
for routine clinical use

56. GRADING

57. DIFFICULTIES & SPECIAL
SITUATIONS
 Ideally there should be concordance between
different measurements
 All measurements should be made when
patient has a normal BP
 Integrate with other imaging & clinical data
before final judgemnt

58. DIFFICULTIES & SPECIAL
SITUATIONS
 Valve area >1.0 cm2 peak velocity<4 m/s and mean
gradient<40 mmHg but strong clinical suspicion
 Index to BSA
 Consider Low Flow states
 Valve area > 1 cm2 but Velocity & Gradient high
 Concomitant AR or shunt lesions
 Reversible causes of increased flow (fever, anaemia,
hyperthyroidism, AV shunts for dialysis, etc.) must be
excluded
 Valve area <1.0 cm2 peak velocity<4 m/s and mean
gradient<40 mmHg
 Exclude measurement errors
 Small Stature
 Low Flow Low gradient

59. DIFFICULTIES & SPECIAL
SITUATIONS
 Low flow, low gradient AS with reduced
ejection fraction ( Classical LFLG AS)
 Effective orifice area < 1.0 Cm2
 Mean pressure gradient < 30–40 mmHg
 SVi <35 mL/m2
 LV ejection fraction <50%.
 True Severe AS or Moderate AS with
low(Pseudosevere AS) EF??

60. DOBUTAMINE STRESS ECHO
CLASS IIa (B) recommendation ACC /AHA / ESC guidelines
 Measures
 Contractile response - change in ejection
fraction and increase in SV (flow reserve)
 Changes in aortic velocity, mean gradient, and
valve area as flow rate increases
 Helps in identifying severe v/s pseudo-severe
AS
 Severe AS causing LV systolic dysfunction
 Moderate AS with another cause of LV
dysfunction

61. LOW DOSE DOBUTAMINE PROTOCOL

62. DOBUTAMINE STRESS ECHO
 LVOT – Baseline measurement
 Aortic and LVOT velocity recorded at each
stage
 EF should be measured at least twice at
baseline and peak effect
 A patient with a low ejection fraction but
High gradient and velocity does not have
impaired LV systolic function -Stress echo not
indicated

63. DOBUTAMINE STRESS ECHO
TRUE SEVERE AS
EOA – Little or no Change
Mean Gradient >40 mm hg
PSEUDO SEVERE AS
EOA becomes >1 cm2
Mean Gradient < 40 mm hg

64. TRUE SEVERE AS
 No Significant change in EOA
 Mean gradient Increased from 32 to 56

65. PSEUDO SEVERE AS
 Significant change in EOA from 0.7 to 1.1
 Mean gradient remains fairly constant

66. LOW FLOW RESERVE
 Increase in SVI < 20%
 30-40% LFLG with low EF patients
 DSE fails to demonstrare response
 Alternative options
 Projected AVA
 MDCT – Calcium scoring (> 1650 Agatston units
has 90 % sensitivity and specificity )

67. PROJECETED AVA
 AVA increase during each stage of DSE
projected to a flow of 250 ml/min (average
flow rate achieved in patients with Severe AS
and normal LV function)
 Minimum of 15 % increase in SV needed to
calculate AVAproj (not seen in 10-20 % cases)

68. CLASSICAL LFLG AS

69. LOW FLOW, LOW GRADIENT AS WITH
PRESERVED EJECTION FRACTION
(PARADOXICAL LFLG AS)
 5-15% of patients with AS
 Hypertrophied, small ventricles with low EDV
 Elderly patients , Long standing SHTN
 Reduced transvalvular flow (SVi < 35
mL/m2)despite normal EF.
 Always rule out technical errors before
diagnosing LFLG AS with preserved EF
 Severe AS highly unlikely when peak velocity is
<3.0 m/s and mean PG <20 mmHg.

70. DIAGNOSING LFLG AS WITH PRESERVED EF
 Very Difficult , DSE not helpful as there is not
much further increase in flow rate
 First
 R/O SHTN during examination
 R/O technical errors
 Clinically confirm whether AS is moderate only
 Only definitive indicator for severe AS – high
calcium score in MDCT

71. DIAGNOSING LFLG AS WITH PRESERVED EF

72. APPROACH

73. APPROACH

74. M MODE- AORTIC STENOSIS
 Maximal aortic cusp separation (MACS)
 Vertical distance between right CC and non
CC during systole
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

75. ASSOCIATED SHTN
 Associated in 35-40%
 Aortic stenosis can conceal hypertension
especially when there is low flow states.
&
Hypertension can mask aortic stenosis severity
(Primarily affect flow and gradients but less AVA
measurement).
 Control of blood pressure is recommended
before echocardiographic evaluation
 Global LV load depends on both AS severity and
vascular after load which is not assessed in usual
measurements of severity

76. VALVULO ARTERIAL IMPEDENCE
 Amount of energy in mmHg needed to pump 1
ml of blood by the left ventricle against the load
imposed by both the Valve and PVR
 Global systolic load to LV and thus assess the
hemodynamic consequences
 Superior in predicting symptoms and events
 ZVA =
𝑺𝑩𝑷+ 𝜟𝑷𝒏𝒆𝒕
𝑺𝑽𝑰
 Zva > 4.5 mmHg/ml/m2 indicates severe disease

77. VALVULO ARTERIAL IMPEDENCE
 In asymptomatic moderate or severe AS
 Zva>4.5–5.0 mmHg/ml/m2 predicts reduced
event-free survival and a 2.8-fold increased risk
of death
 Drawback
 Does not identify the relative contributions of
the valve and PVR that is necessary to guide
management (i.e. AVR versus BP control)

78. ASSOCIATED AR
 80% of adults with AS have concomitant AR
 Usually mild or moderate - does not affect
severity assessment
 Flow rate, maximum velocity, and mean
gradient will be higher than expected for a
given valve area
 Quantitative severity of both lesions to be
reported

79. MITRAL VALVE DISEASE
 Miral valve diseases should be looked for esp
in Rheumatic AS
 Severe MR, transaortic flow rate may be low
resulting in a low gradient even when severe
AS is present;
 AVA calculations remain accurate (if flow is
calculated in the LVOT and not by volumetry)
 High-velocity MR jet mistaken for the AS jet
 Mitral stenosis (low cardiac output) May
result in low flow, low gradient AS.

80. ASCENDING AORTA
 Should also be assessed as a part of AS
evaluation
 Diameters at the sinuses of Valsalva, the
sinotubular junction and the ascending aorta
measured .
 Dilation of the aortic root associated with
bicuspid aortic valve disease and aortic size
may impact the timing and type of
intervention.

81. PROGNOSTIC INDICATORS
IN ASYMPTOMATIC SEVERE AS
 Peak aortic jet velocity
 Severity of valve calcification
 LV ejection fraction
 Rate of hemodynamic progression
 Increase in gradient with exercise
 Excessive LV hypertrophy
 Abnormal longitudinal LV function (in particular
GLS)
 Pulmonary hypertension

82. PROGNOSTIC INDICATORS
IN ASYMPTOMATIC SEVERE AS
 Peak aortic jet velocity >5.5 m/s;
 Combination of severe valve calcification with
a rapid increase in peak transvalvular velocity
of>_0.3 m/s/year;
 Increase of mean pressure gradient with
exercise by> 20mmHg.

83. STRESS ECHOCARDIOGRAPHY
 In True asymptomatic patients
 AVR
 MG increase > 20 mm Hg
 Reduction in LVEF
 Follow up
 MG increase < 20 mm Hg
 No reduction in LVEF
 Every 6-12 months in severe AS
 Every 12-24 months in Moderate AS

84. AORTIC VALVE RESISTANCE
 Resistance offered by the valve to flow of blood through it
 Relatively flow-independent measure of stenosis severity
 Depends on the ratio of mean pressure gradient and mean
flow rate
 Resistance =
𝜟𝑷𝒎𝒆𝒂𝒏
𝜟𝑸𝒎𝒆𝒂𝒏
× 1333 dynes/cm2
 There is a close relationship between aortic valve resistance
and valve area
 The advantage over continuity equation not established

85. LV STROKE WORK LOSS %
 Work of LV wasted in ejecting blood through
the aorta and to keep valves open
 SWL(%) =
𝜟𝑷𝒎𝒆𝒂𝒏
𝜟𝑷𝒎𝒆𝒂𝒏+𝑺𝑩𝑷
𝒙 100
 A cutoff value more than 25% effectively
discriminates between patients experiencing
a good and poor outcome.
Kristian Wachtell. Euro Heart J.Suppl. (2008) 10 ( E), E16–E22

86. THANK YOU

87. TO SUMMARISE
 The 3 primary haemodynamic parameters recommended for evaluation
of AS severity are
 (i) AS peak jet velocity
 (ii) mean aortic transvalvular pressure gradient
 (iii) valve area by continuity equation.
 Make measurements when BP normal and r/o hyperdynamic circulatory
states
 AS peak jet velocity:
 A peak gradient >_4 m/s is consistent with severe aortic stenosis.
 AS peak jet velocity should be obtained in multiple views.
 Mean aortic transvalvular pressure gradient:
 A mean gradient of>_ 40mmHg is consistent with severe aortic stenosis.
 The mean gradient is calculated by averaging the instantaneous gradients
over the ejection period.
 Cannot be calculated from the mean velocity.
 A common source of error for gradient measurement is misalignment of
the beam - importance of using multiple acoustic windows

88. TO SUMMARISE
 AVA
 An AVA of< 1.0 is consistent with severe aortic stenosis.
 AVA by continuity-equation calculation - well validated predictor of clinical
outcome
 LVOT diameter is measured in a PLAX view - inner edge to inner edge of the septal
endocardium, and the anterior mitral leaflet in mid-systole
 LVOT velocity is recorded with PWD from an apical 5 chamber or 3 chamber view.
 The pulsed Doppler sample volume is positioned just proximal to the aortic valve
at the aortic annulus to get a smooth velocity curve can be obtained
 Flow acceleration at the annulus level may make it necessary to move the sample
volume apically by 0.5–1.0 cm.
 Major limitation of the continuity equation LVOT not circular - LVOT area and
consequently flow and AVA will be underestimated
 Follow up measurements –
 Aortic jet velocity same window (Always give report with window of max
velocity )
 If AVA changes, look for changes in Individual components. LVOT size rarely
changes over time in adults

89. TO SUMMARISE
 Low flow, low gradient AS with reduced EF is defined as
(i) AVA <1.0 cm2, (ii) mean aortic transvalvular
PG<40mmHg, (iii) LVEF<50%, and (iv) SVi <35mL/m2.
 Low-dose DSE can help distinguish between pseudo severe
AS from true severe AS.
 Low flow, low gradient AS with preserved EF is defined
as (i) AVA <1 cm2, (ii) peak velocity <4 m/s, (iii) mean
PG <40mmHg, and (iv) normal LVEF (>_50%)
 R/o measurement errors (esp. LVOT area and thus flow).
 Clinically moderate AS (despite an AVA < 1.0 cm2) in a
patient esp. with small body size.
 Calcium scoring