This document discusses aortic stenosis, including its causes, assessment of severity, clinical presentation, evaluation with echocardiography, and indications for surgery. Key points include: - Aortic stenosis can be caused by a bicuspid valve, degenerative calcification, or rheumatic fever. Severity is classified based on valve area, peak gradient, and mean gradient. - Asymptomatic severe aortic stenosis may remain asymptomatic for years, while symptomatic severe stenosis can cause angina, syncope, dyspnea and other clinical signs. - Echocardiography is the primary imaging modality used to evaluate aortic valve anatomy and function, calculate valve area and gradients, and assess left

2. AORTIC STENOSIS

3. AORTIC STENOSIS
Bicuspid valve Degenerative calcific valve
Rheumatic valve

4. AORTIC STENOSIS
Valve area (cm2)
• normal - 3.0 – 4.0
• mild AS - 1.5 – 2.0
• moderate AS - 1.0 – 1.5
• severe AS - < 1.0
( < 0.6 cm2 / m2 )
• critical AS - < 0.75
( < 0.5 cm2 / m2 )

5. AORTIC STENOSIS
Rate of progression ( annual )
Area - decrease by 0.12 cm2
Jet velocity - increase by 0.32 m / sec
Mean gradient - increase by 7 mm Hg

6. AORTIC STENOSIS
Clinical
Remain asymptomatic for long
Severe AS
• exertional angina , syncope / presyncope
• dyspnea
• low volume, slow rising pulse – parvus et tardus
• narrow pulse pressure
• prominent A in JVP (Bernheim effect)
• heaving apex
• LV S4 , delayed A2
• long MSM with late peaking
• LV strain pattern in ECG

7. AORTIC STENOSIS

8. AORTIC STENOSIS
Geometric orifice area (GOA) … minimal area by planimetry
Effective orifice area (EOA) …. by continuity equation
corresponds to venacontracta

9. AORTIC STENOSIS
Hemodynamics

10. AORTIC STENOSIS
Peak gradient by Doppler
Pressure recovery

12. Mean gradient
Echo
Cath

13. AORTIC STENOSIS
Echocardiography
1. Anatomy - short & long axis views
(occasionally TEE / 3D)
2. LVOT diameter – midsystole ; at the site of measurement
of LVOT velocity measurement
parallel to AV
3. LVOT velocity - apical 4C / 5C ; V max / VTI
4. AS jet velocity (CW) – V max; peak and mean gr; VTI
5. SVI
6. DSE ( SOS)

14. AORTIC STENOSIS
Primary data
• AS jet velocity – V max
• mean gradient
• valve area
• flow .. SVI
Continuity equation
Planimetry .. TTE / TEE / 3D
Gradient …. Diagnostic value
Flow ………. Prognostic value

19. AORTIC STENOSIS
Continuity equation
Flow across LVOT and aortic valve is same
Flow = area x VTI
A LVOT x VTI LVOT = A AV x VTI AV
AAV = A LVOT x VTI LVOT A1 x V1_
VTI AV V2

21. AORTIC STENOSIS
Dimensionless valve index (velocity ratio)
Very simple method
Variable of area is taken away from the continuity equation
LVOT velocity
Aortic valve velocity
Value < 0.25 .. Severe AS

22. SEVERE AS
Mean gradient = 71 mm Hg
Dimensionless index = 0.5 / 5.5 = 0.1

23. V1 = 1. 5 m /sec
V 2 = 4 m / sec
DI = 1.5 / 4 = 0.375

24. AORTIC STENOSIS
Severity
Parameters sclerosis mild AS moderate severe
Vmax..m/sec < 2.5 2.6 – 2.9 3.0 – 3.9 ≥ 4.0
MPG mm Hg -- < 20 20 – 39 ≥ 40
AVA cm2 -- > 1.5 1.0 – 1.5 < 1.0
AVAI cm2 / m2 -- > 0.85 0.6 – 0.85 < 0.6
Dimensionless -- > 0.5 0.25 – 0.5 < 0.25
index

25. AORTIC STENOSIS
Global LV hemodynamic load
Valvuloarterial impedance ( Z va )
Valvular resistance + vascular resistance
Mean gradient SBP
Zva = SBP + mean gradient
Stroke volume index
> 4.5 … severe AS

26. AORTIC STENOSIS
Dobutamine stress echo
• change in mean gradient
• change in valve area
• change in SVI
• effort tolerance , symptoms
• BP response
• increase in mean gradient
Exercise test
in severe “asymptomatic” AS
BNP .. Limitations + ; > 500 pg / ml …poor prognosis

27. AORTIC STENOSIS
CT
• best method to assess annulus, aorta and calcium
• assess GOA
• assess coronaries
• severity of AS .. < 700 AU .. excludes severe AS
> 2000 AU .. severe AS
> 1650 .. optimal sensitivity & specificity
• evaluation of prosthetic valve
• planning TAVR
• assess myocardial fibrosis
CMR

29. AORTIC STENOSIS
Terminologies
Low flow low gradient severe AS
Paradoxical low flow AS
Pseudosevere AS

30. AORTIC STENOSIS
Low flow low gradient AS
Valve area < 1.0 cm2
Mean gr. < 40 mm Hg
SVI < 35 ml / m2
? Possibilities
EF < 50 %
EF > 50 %
• severe AS with reversible LV dysfunction
• AS with severe myocardial failure
• pseudo severe AS
• paradoxical low flow severe AS (EF > 50 %)

31. AORTIC STENOSIS
Physiologic discrepancies
V max > 4.0 m /sec
Mean gr. > 40 mm Hg
Valve area > 1.0 cm2
Valve area < 1.0 cm2 ; normal flow ; low gradient
Gradient under assessed due to hypertension
Prolonged LVET ; reduced flow rate > lower Vmax
Moderate AS ; small body size ; AVA index - > 0.6 cm2
associated AR
high output states
Large BSA … calculate AVAI
1.
2.

32. AORTIC STENOSIS
DSE
Valve area mean gr. SVI change assessment
(cm2) (mm Hg) ( %)
< 1.0 > 40 > 20 severe AS
myocardium OK
< 1.0 < 40 < 20 myocardial failure
↑ by > 0.3 no change > 20 pseudo severe AS

33. AORTIC STENOSIS
Paradoxical low flow severe AS
( Hachicha et al 2007)
1/3 rd of cases ; poor surgical outcome
Severe true AS … area < 1.0 cm2
Low flow … SVI < 35 ml / m2
Preserved EF .. > 50 %
1. Impaired LVEDV
2. Impaired LV longitudinal strain
• severe LVH
• AF , tachycardia
• MS , MR, PAH, TR

34. Stages of valvular AS
Stage type Vmax mean gr EF other data
(m/sec) (mm Hg)
A at risk of AS < 2 -- N --
(BAV)
B progressive AS 2.0 – 3.9 upto 39 N valve area > 1.0
C. Asymptomatic ≥ 4.0 ≥ 40 N ( C1) valve area < 1.0
severe AS
< 50 % (C2)
D Symptomatic
severe AS (valve area < 1.0)
D1 (high gr) ≥ 4.0 ≥ 40 N
D2 (low flow < 4.0 < 40 < 50 DSE .. gr > 40
low gr) SVI > 35
D3 (paradoxical < 4.0 < 40 > 50 DSE .. SVI < 35
low flow low gr)

35. AORTIC STENOSIS
Surgery
Class I
Class II a
Class II b
• symptomatic severe AS .. Stage D1
• asymptomatic severe AS ; EF < 50 % .. C2
• asymptomatic severe AS + other cardiac surgery
• very severe AS ( Vmax > 5 m/sec ; mean gr . 60 mmHg)
abnormal ETT
• low flow low gradient AS with
contractile reserve on DSE
• pseudo low flow severe AS
• asymptomatic severe AS with rapid progression
V max > 0.3 m / s / year

36. AS .. (Vmax, mean gr., AVA, LVEF, SVI)
AVA < 1.0 < 1.0 < 1.0
Vmax > 4.0 < 4.0 < 4.0
MPG > 40 < 40 < 40
EF > 50 > 50 < 50
SVI > 35 < 35 < 35
Normal flow paradoxical low flow low flow low gr
high gr. Vs
pseudo severe AS
DSE
symptomatic symptomatic ? contractile reserve
present absent
AVR MPG > 40 AVA increase
AVA < 1.0 by > 0.3
OMT
pseudo severe AS