Aortic Stenosis Flashcards
What are the levels of AS obstruction and their causes?
- Supravalvular - membrane, shelf in AO
- Valvular - calcific, congenital, rheumatic
- Subvalvular - Membrane, muscular IVS
What are the 3 ways to calculate pressure gradients?
- Instantaneous - single point in time
- Peak to peak - two points in time
- Mean - Average
What is the formula for Mean/Average pressure gradient?
Pmean = 2.4 x (Vmax)^2
Describe the effect of AS effect on the LV? (4 steps)
- AS obstruction increases afterload
- LV systolic pressure increases
- Force of contraction increases
- LV concentric hypertrophy due to pressure overload
What does AS lead to?
CHF
How does AS lead to CHF? (7 steps)
- SV decreases
- Afterload increases
- LV stiffness and compliance increase
- LV filling pressures increase
- LA size and pressure increase
- Pulmonary congestion
- RV failure
What are the inter-leaflet triangles and what are the names?
Extensions of the LVOT that extend up to the STJ and provide a smooth surface for blood flow.
- R/L coronary interleaflet triangle
- R/Non coronary interleaflet triangle
- Non/L coronary interleaflet triangle
How does ASE recommend measuring the aorta?
Leading to leading at the sinus, STJ and ascending aorta
How can you find the change in pressure between the LV and AO with Bernoulli?
Change in P = 4(V2^2 - V1^2)
Or
Change in P = 4V^2
What are the symptoms of AS? (6)
- SOBOE
- Fatigue
- Chest pain/Palpitations
- Arrhythmias
- Dizziness/Syncope
- Signs of CHF (edema etc.)
What are the clinical signs of AS? (4)
- Auscultation
- Angina Pectoris
- Presyncope/Syncope
- CHF
What auscultation may be heard with AS and where?
- Harsh ejection murmur
- AO regurgitation murmur (if regurg is present)
Heard in right upper sternal border
Why does AS cause Angina Pectoris? (3)
- Reduced coronary artery profusion
- LV hypertrophy (more muscle = more O2 demand and more pressure)
- Increased contraction and decreased relaxation causes compression of the intramyocardial arteries
Why does AS cause Presyncope/Syncope?
Reduced cerebral perfusion with exertion.
What is the most common order of AS etiology in patients > 70 years?
- Calcific/Degenerative
- Congenital/Bicuspid
- Rheumatic
Where does thickening start with calcific AS?
Underside of cusps/commissures
Where does thickening start with rheumatic AS?
Free edges/tips of the cusps
What are 3 types of congenital AS?
Bicuspid, Unicuspid, Quadricuspid
What is the most common order of AS etiology in patients < 70 years?
- Congenital/Bicuspid
- Rheumatic
- Calcific/Degenerative
How often does aortic sclerosis develop into AS?
10-15%
What causes calcific/degenerative AS?
Atherosclerotic process (lipid deposits, smoking, stress, obesity, lack of exercise).
What are the steps in the development of calcific AS? (4)
- Endothelial damage (force, BP increase, reduced function with age)
- Cells stop producing gasses that prevent clotting and inflammation
- Foam cells infiltrate tissue (fatty macrophages)
- Inflamm/necrosis/calcification/narrowing occurs
How do you assess the AV in m-mode?
- Look for diastolic closure line between boxes (valve opening)
- Measure leaflets at least 2 cm apart during systole (box height)
How do you assess the AV in 2D? (6)
- PLAX LV/LA/AO measurements
- Calc LV mass index
- Calc EF
- Observe valve opening/coaptation
- 3 cusps
- Observe walls/cavity
What is the difference between AV sclerosis and stenosis?
Sclerosis = Some thickening/calcification and a normal CW velocity
Stenosis = Obvious thickening/calcification and an abnormal CW velocity
What is the NV for CW velocity of the AV?
< 2.5 m/s
What is a raphe?
The seam that joins two cusps together in a bicuspid valve (bicupid may or may not have a raphe tho).
What are the most common bicuspid cuspal fusions?
85% RCC and NCC
15% RCC and LCC
What are 5 common signs of bicuspid valve?
- Thick cusps with doming
- Off centre cusp closure m-mode or PLAX
- Systolic doming of larger cusp
- Concentric LVH and LV/LA dilation
What are the 3 most common associations of bicuspid?
- Sub/supra valvular congenital membranes
- Supravalvular coarctation (AO)
- Subvalvular LVOT obstuction (due to HCM- septal LVH or SAM)
What causes Rheumatic AS?
- Rheumatic fever caused by beta-hemolytic streptococci
2. Endocardium swells and damages the valve
What valves does rheumatic affect from most to least?
MV = 75 - 80%
AV = 20 - 25%
PV and TV = 5%
What is the cause of acute and chronic rheumatic heart disease?
Acute = Caught fever travelling
Chronic = Had fever as child, effects manifest later
What are the two methods to calculate AVA and what is more accurate?
- Planimetry
- Continuity equation
Continuity = more accurate
What is the continuity of flow and what is needed to calculate?
The volume of flow proximal to and within the narrowing must be equal (SV LVOT = SV AV)
- LVOT diameter (PLAX)
- PW LVOT VTI trace
- CW AV VTI trace (highest, most parallel signal)
What is the AVA formula?
AVA = ( (0.785 x LVOT d^2) x VTI LVOT ) / VTI AV
What is the normal value for LVOT?
18 - 22 mm
Where should the PW VTI be measured in the AO?
Same spot as LVOT measurement
What are the two methods of AVA by the continuity equation?
- AVA by velocity only
2. AVA by VTI
What is the diff between velocity continuity method and VTI method?
Velocity = Plug in velocities instead of VTI’s
When the AV velocity is greater than 2.5 m/s what should be done? (5)
Assessment in ALL views:
- Apical
- Rt suprasternal
- Rt supraclavicular
- Rt parasternal
- +/- subcostal
How is the velocity and VTI ratio calculated?
VTI ratio = LVOT VTI / AV VTI
Velocity ratio = LVOT vel / AV vel
How can you tell if you are catching MR vs AS on continuous wave?
AS will not have flow during isovolumic periods and MR will.
With true AS, a small space will be seen between jet outflow below baseline and MV inflow above baseline.
How does subaortic stenosis outflow differ from severe AS?
Subaortic => Late peaking profile (dagger sign wave) and high velocity
Severe AS => Acceleration time = Deceleration time (more symmetrical than normal outflow wave)
What AV jet velocity indicates only sclerosis?
≤ 2.5 m/s
What AV jet velocity indicates mild and severe AS?
Mild = 2.5 - 2.9 m/s
Severe = >4.0
What mean gradient indicated mild and severe AS?
Mild = < 20 mmHg
Severe = > 40 mmHg
What AVA indicates mild and severe AS?
Mild = >1.5 cm^2
Severe = < 1.0 cm ^2
What is indexed AVA?
Comparing the AVA to height and weight
AVA/BSA
What indexed AVA indicated mild and severe AS?
Mild = > 0.85 cm^2/m^2
Severe = < 0.6 cm^2/m^2
What velocity ratio indicates mild and severe AS?
Mild = > 0.5 Severe = < 0.25
