Echocardiographic Assessment Flashcards
What are the echo characteristics of calcific AS?
- Increased reflectivity
- Diffuse thickening
- Reduced systolic excursion
Note: >70yrs unlikely congenital, no MV involvement unlikely rheumatic
What are the echo characteristics of rheumatic AS?
- Thickening of free edges
- Variable commissural fusion; may be functionally bicuspid
Note: almost always associated with mitral valve stenosis
What are the echo characteristics of bicuspid AS?
- 2 commissural attachments to aortic root
- Elliptical systolic orifice
- May be aortic root dilatation and/or effacement of aorta
Note: likely BAV if younger patient (<60yrs) with significant AS
At what stage of the cardiac cycle is the diagnosis of BAV made?
Diagnosis made in systole (when the valve is open), not diastole
Characteristics of Stage 0 Aortic Stenosis (Impact of Aortic Stenosis)
No cardiac damage
Characteristics of Stage 1 Aortic Stenosis (Impact of Aortic Stenosis)
LV damage
- Increased LV mass index
- Diastolic dysfunction
- Reduced LV systolic function
Characteristics of Stage 2 Aortic Stenosis (Impact of Aortic Stenosis)
LA or Mitral Damage
- Dilated LA
- Moderate-severe MR
- Atrial fibrillation
Characteristics of Stage 3 Aortic Stenosis (Impact of Aortic Stenosis)
Pulmonary vasculature or tricuspid damage
- PHTN
- Moderate-severe TR
Characteristics of Stage 4 Aortic Stenosis (Impact of Aortic Stenosis)
RV damage
- Moderate-severe RV dysfunction
What are the primary parameters used to determine AS severity?
- AV Vmax (m/s)
- Mean PG (mmHg)
- AVA (cm2)
What are the supportive parameters used to determine AS severity?
- Indexed AVA
2. DVI/VR (velocity ratio)
Formula to calculate AVA (continuity equation)?
AVA= (LVOT area × LVOT VTI)/(AV VTI)
LVOT area = 0.785 x D^2
Formula to calculate AVA (Vmax method)?
AVA= (LVOT area × LVOT Vmax)/(AV Vmax)
Limitations of AVA via Continuity Principle
- LVOTd measurements
- LVOT VTI measurements
- Non-parallel alignment with AS jet (AV VTI)
AVA consequence of LVOTd underestimation?
Underestimation of AVA
AVA consequence of LVOTd overestimation?
Overestimation of AVA
AVA consequence of LVOT VTI underestimation (sample volume placed too far into the LV)?
Underestimation of AVA
AVA consequence of LVOT VTI overestimation (sample volume placed too close to AV in flow acceleration region)?
Overestimation of AVA
AVA consequence of AV VTI non-parallel alignment with AS jet
- Underestimation of AV VTI
- Overestimation of AVA
When is pressure gradient correction required?
Required when LVOT velocities are ≥ 1.2m/s
Formula to correct peak AV pressure gradient?
Corrected PPG = PPG(AV) - PPG(LVOT)
Formula to correct mean AV pressure gradient?
Corrected mPG = mPG(AV) - mPG(LVOT)
Alternative AVA Methods: Formula for AVA using LV volumes?
AVA = (LVEDV-LVESV)/AV VTI
Alternative AVA Methods: Limitations of AVA using LV volumes?
- Method tends to underestimate stroke volume and is not recommended
Alternative AVA Methods: Formula for AVA using RVOT SV?
AVA = (RVOT area × RVOT VTI)/AV VTI
- RVOTd measured at PV opening in PSAX
- Used when LVOTOB or LVOT flow is not laminar
Alternative AVA Methods: Limitations of AVA using RVOT SV?
- Can’t be used if significant AR, PR or intracardiac shunt
- Assumes SV AV = SV RVOT
Alternative AVA Methods: How to measure AVA using planimetry?
- Measured in PSAX at maximal AV opening during systole
- Acceptable alternative when Doppler unreliable
Alternative AVA Methods: Limitations of AVA using planimetry?
- Measures anatomical orifice area rather than effective orifice area (vena contracta)
- AOA > EOA
Alternative AVA Methods: Formula for Velocity Ratio (VR)?
VR = LVOT VTI/AV VTI
or
VR = LVOT Vmax/AV Vmax
Alternative AVA Methods: Significance of 0.25 Velocity Ratio (VR)?
VR of 0.25 corresponds to an AVA 25% of normal = severe AS
When might we expect highest AS velocities from RSE?
Suspect highest AS velocities from RSE when LV-to-aorta angle is acute (<115°)
AS vs MR: Signal Shape
- MR signal: parabolic, peaks in mid-late systole
- AV signal: V shaped, peaks in early systole
AS vs MR: Duration
- MR incorporates IVCT and IVRT and is therefore longer in duration than AV/AS signal
- AV duration is shorter (excludes IVCT and IVRT)
- LVOT PWD has the same duration as AV CWD (clue to identifying AV signal)
AS vs MR: Continuity
- AV is not continuous with mitral flow
- MR will be continuous with mitral flow
AS vs MR: Velocity
MR gradient will always exceed AS gradient
In the presence of a membranous VSD, AVA will be?
- Overestimated
- LVOT VTI will increase (blood passing through LVOT before exiting to RV)
- AV VTI will decrease (some blood bypassing AV through to RV)
Can AVA via the continuity equation be accurately assessed in a patient with AS and AR?
- Yes
- LVOT SV and AV SV in systole will be the same
- If LVOT SV increased due to AR, AV SV will also be increased due to AR
- AR occurs in diastole
