2. Aortic valve is composed of three cusps of equal size, each of
which is surrounded by a sinus
Cusps are separated by three commissures and supported by
a fibrous anulus
Each cusp is crescent shaped and capable of opening fully to
allow unimpeded forward flow, then closing tightly to
prevent regurgitation
3. Free edge of each cusp curves upward from the commissure
and forms a slight thickening at the tip or midpoint, called
the Arantius nodule
When the valve closes, the three nodes meet in the center,
allowing coaptation to occur along three lines that radiate out
from this center point
Overlap of valve tissue along the lines of closure produces a
tight seal and prevents backflow during diastole
4. When viewed from a
2D echo parasternal
short-axis projection,
these three lines of
closure are seen as an
“inverted Mercedes
Benz sign”
Normal leaflets are so
delicate that they are
hard to visualize,
generally an indication
that they are
morphologically
normal
5. Behind each cusp is its associated Valsalva sinus
Sinuses represent outpunching in the aortic root directly
behind each cusp
Function to support the cusps during systole and provide a
reservoir of blood to augment coronary artery flow during
diastole
6. Left and right coronary arteries arise from the left and right
sinuses, respectively, and are associated with the left and
right aortic cusps
Third, or noncoronary sinus, is
posterior and rightward, just
above the base of the interatrial
septum, and is associated with
the noncoronary aortic cusp
RCC
LCC
NCC
LA
LAA
RA
RVOT
RV
7. The area of a normal aortic valve is 3 to 4 cm2
Normal opening generally produces 2 cm of
leaflet separation
Maintained throughout the cardiac cycle until low
cardiac output or LVOT obstruction
8. The most common form of aortic stenosis is
caused by degenerative valvular calcification
Leaflets are thickened and calcified
Decreasing systolic opening
Other causes include
bicuspid aortic valve
and rheumatic heart
disease
9. Establishing the diagnosis
Quantifying severity
Assessing left ventricular function
Identify concomitant valvular abnormalities
10. Visualizes the entire aortic valve structure
Helpful in identifying noncalcific as well as calcific aortic
stenosis
Degree of valvular calcification, the size of the aortic
anulus and the supravalvular ascending aorta, and the
presence of secondary subvalvular obstruction are easily
evaluated
Useful for determining the degree of LV hypertrophy
(wall thickness and mass), LA enlargement, ventricular
function, and the integrity of the other valves
11. Cusps are thickened and showed restricted mobility
Their position during systole is no longer parallel to the aortic
walls, and the edges are often seen to point toward the
center of the aorta
In severe cases, a nearly total lack of mobility may be present
and the anatomy may become so distorted that
identification of the individual cusps is impossible
12. Unfortunately only give qualitative
assessment and attempts to quantify the
degree of stenosis based on two-dimensional
echocardiographic findings have been
unsuccessful
27. Hemodynamic assessment of severity of aortic
stenosis determined with Doppler echo is based on
Peak aortic flow velocity
Mean pressure gradient
Aortic valve area
LVOT and aortic valve (AoV) velocity time integral (VTI)
ratio (LVOTVTI: AoV VTI)
28. Meticulous search for the maximal aortic velocity is
essential because all the variables are derived from
the peak aortic flow velocity
All available transducer windows should be used to obtain the
Doppler signal most parallel with the direction of the jet flow,
which provides the highest velocity recording
Failure to achieve parallel alignment will result in
underestimation of true velocity
Nonimaging continuous wave Doppler transducer is smaller and
thus easier to manipulate between the ribs and suprasternal
notch
29.
30. Peak velocity usually occurs in mid systole
As aortic stenosis worsens, velocity tends to peak
later in systole
Offering a clue to severity
31.
32. Blood flow velocity and pressure gradient
increase as the valve becomes smaller as long
as stroke volume remains constant
33. Blood flow velocity (v) measured with Doppler
echocardiography reliably reflects the pressure
gradient according to the modified Bernoulli
equation (give peak instantaneous gradients
because Doppler measure velocity over time)
Pressure gradient = 4v2
34. Often obtained by planimetry of the Doppler
envelope
Mean gradients can also be calculated as:
Mean gradients = Peak gradient/1.45 + 2
35.
36. A technically poor recording may fail to display the
highest velocity signals
Resulting in underestimation of the true gradient
An inability to align the interrogation angle parallel
to flow also results in underestimation
37.
38. Overestimation of the true pressure gradient is less common
but can occur
Result of mistaken identity of the recorded signal e.g., MR
jet has a contour similar to that of a jet of severe AS
Avoid by sweeping the transducer back and forth to clearly
indicate to the interpreter which jet is which
Another helpful clue involves the timing of the two jets MR is
longer in duration, beginning during isovolumic contraction
and extending into isovolumic relaxation
39.
40. Valve gradients are dynamic measurements that
vary with
Heart rate
Loading conditions
Blood pressure
Inotropic state
41. For a given valve area, flow velocity and pressure
gradient vary with the change in stroke volume and
cardiac output
Cardiac output or stroke volume should be taken into
account when the severity of valvular stenosis is
determined
42.
43. Hydraulic formula
Flow = Area x Flow velocity
The continuity equation use law
of conservation of mass,
states that, “what goes in
must come out”
Reliably estimate valve area
44. For calculating aortic valve area following
measurements must be performed
Cross-sectional area of the LVOT
Time velocity integral of the LVOT
Time velocity integral of the aortic stenosis jet
45.
46.
47.
48.
49. Continuity equation has advantages over Bernoulli
equation for the assessment of aortic stenosis
Not affected by the presence of aortic regurgitation
Continuity equation is relatively unaffected and will allow
an accurate estimation of valve area whether the stroke
volume is normal or reduced
50. Potential factors that may contribute to errors
include
Image quality
Annular calcification (which obscures the true dimension)
Noncircular anulus (which invalidates the formula)
Failure to measure the true diameter
51. Always preferable
Because VTI or peak velocity ratio is inversely
proportional to the area ratio of the LVOT and
aortic valve
Also useful in determining the severity of aortic
stenosis
52. Velocity or TVI ratio is independent of any change in
stroke volume because the LVOT and aortic valve
velocities change proportionally
Also helpful in the presence of aortic regurgitation
Normal Ratio > 0.75
53. In patients with normal LV systolic function
and cardiac output, aortic stenosis is usually
severe when
Peak aortic valve velocity is 4 m/s
Mean pressure gradient is 40 mm Hg
Aortic valve area is less then 1 cm2
LVOTVTI: AoVVTI is 0.25
54. LV dysfuction with severe AS than two diagnostic
possibilities:
True anatomically severe aortic stenosis
Functionally severe aortic stenosis (pseudosevere)
Because an aortic valve with mild or moderately
severe stenosis may not open fully if the stroke
volume is low
55. Gradual infusion of dobutamine (up to 20
µg/kg/minute) to increase stroke volume may be
helpful in differentiating morphologically severe
aortic stenosis from a decreased effective stenotic
orifice area caused by low cardiac output
(pseudosevere aortic stenosis)
56. Dobutamine infused gradually from 5 µg/kg/minute
in 5µg increments every 3 minutes until the LVOT
velocity or VTI reaches a normal value i.e., 0.8 to 1.2
m/s or 20 to 25 cm, respectively
Maximal velocity or stroke volume is usually
obtained with 15 to 20 µg/kg/minute of dobutamine
57. In true severe AS, the infusion of dobutamine
increases the peak velocity and VTI of both the
LVOT and aortic valve proportionally (hence, the
LVOTVTI: AoV VTI remains constant)
In pseudosevere AS increase in velocity and VTI of
the LVOT is far greater than that of the aortic valve
hence, LVOTVTI : AoVVTI increases
60. When LV systolic function is abnormal and cardiac
output is reduced, aortic stenosis is probably severe
if
Aortic valve area by the continuity equation is 1.0 cm2
or
less
LVOTVTI :AoVVTI is 0.25 or less
61. Another most important role of dobutamine infusion in
patients who have severe aortic stenosis and a low gradient
is to assess inotropic reserve
Defined as an increase in stroke volume of more than 20% with
dobutamine
Lack of inotropic reserve with dobutamine portends poor
perioperative mortality (50% vs. 7%) if aortic valve
replacement is attempted
62. If Dobutamine infusion is able to increase stroke
volume (or LVOT VTI) by 20% or more and the
aortic valve area remains 1.0 cm2
or less, aortic valve
replacement should be recommended
If no inotropic reserve is demonstrated with
dobutamine, aortic valve replacement is still better
than no treatment, but the mortality rate is very
high
63. If transthoracic is difficult to perform
TEE can be used to measure aortic valve area by
planimetry
The number of aortic cusps can be determined
Not routine practice to use TEE to evaluate aortic
stenosis
Intraoperatively in AVR for assessment of severity
of MR and need for mitral valve replacement
64.
65. Diastolic function varies in patients with aortic
stenosis
Usually have at least a mild degree (grade 1) of
diastolic dysfunction
As aortic stenosis progresses to a symptomatic
stage, diastolic function also deteriorates to grades
2 and 3
