Module 4 : Aortic Stenosis Flashcards
4 components of the aortic root
- valve ring = poin t of attachment of the cusps to the root wall
- cusps (NCC, RCC, LCC)
- sinus of valsalva = aortic cusps recess into the sinus during systole
- Sino-tubular junction = where the sinus valsalva becomes the tubular portion of the aorta
aortic commissures
- most age related calcification starts at the commissures and work its way along the free edges to the orifice
stenosis definiton
- formation of a high velocity jet through a narrowed orifice
aortic stenosis
- incomplete opening of the aortic valve during systole leading to a high velocity jet
effect of aortic stenosis
- causes and obstruction to flow from the LV to AO
three levels of obstruction
- supravalvular = membrane, shelf in AO
- valvular - valvular AS
+ calcific, congenital, rheumatic
+ MOST COMMON - subvalvular - membrane or muscular IVS
+ hypertrophic cardiomyopathy
afterlaod effect on the LV
outflow obstruction»_space; increasing after load» LV systolic pressure rises» TO keep SV normal»_space; increased force of contraction»_space; LVH develops (concentric) due to pressure overload
clinical symptoms of aortic stenosis
- exertion dyspnea/ SOB
- fatigue
- chest pain
- dizziness/snycope
- arrhythmias
- signs CHF
auscultation of aortic stenosis
- harsh éjection murmur
- systolic ejection click
- crescendo decrescendo murmur
- right upper sternal border
- may radiate to carotid arteries
- +/- aortic regurge murmur
clinical manifestations of AS
- mild and moderate rarely felt
- symptoms are related to the pathophysiological response
- angina pectoris
+ mini heart attacks - syncope or presyncope
+ exertion not enough blood flow to brain - congestive heart failure
etiology AS - in order of incidence
- calcific AS (degenerative) \+ thickening starts at the underside of the cusps \+ increased incidence with age \+ associated with bicuspid AV - congenital (bicuspid, uni.quad) - rheumatic \+ thickening starts at cusp edges
calcific AS - epidemiology
- about 25% over 65 have some degree of aortic sclerosis
- 10-15% develop aortic stenosis
- progressive thickening over many years
- AV leaflets thicken then start to tether together at the edges
calcific AS - pathology
- number cusps cannot be identified due to disintegration
- calcific aortic valve is seen as extension of the atherosclerotic process
- lipid deposition, inflammation and calcification cause leaflets to stick together
pathogenesis of calcific AS
- endothelial damage»_space; endothelial cells lose ability to produce gasses that prevent clotting inflammation» foam cells infiltrate into tissue» macrophages engulf foam cells causing inflammation» necrosis, calcification and narrowing occurs
6 jobs of echo in AS
- determine etiology of the lesion
- exclude other sources of LVOT obstruction
- assess LV size systolic, diastolic function
- assess degree of LVH
- estimate severity of stenosis
- identify associated valve lesion
AV assessment - M Mode
- look for
+ diastolic closure line - normally at middle of aortic annulus
+ leaflet excursion 2.0cm - BOX
AV assessment - 2D
- look for \+ equal opening/coaptation of cusps \+ cusp number \+ coronary implantation \+ degree of movement \+ morphology changes (atherosclerosis, calcium, commissural fusion, post stenotic dilatation)
2D exam
- assess \+ walls \+ cavities \+ valve morphology - measure \+ IVS, LV, LVPW \+ LA, AoRoot, AscAo \+ LVOT - calculate \+ LV mass index \+ EF \+ LVOT area
AV sclerosis
- some thickening and calcification(brightening)of cusps
- slight reduction of cusp excursion may be present
- CW doppler velocity through AV normal or slightly elevated
< 2.5m/s
AV stenosis
- more obvious thickening and calcification of cusp
- obvious visual reduction of cusp excursion
- CW doppler velocity elevated through the AV >2.5m/s
bicuspid AV is what shape when opened
- football shaped orifice when open
bicuspid AV.
- MOST COMMON TYPE OF AS IN PATIENTS UNDER 50 YEARS OLD
- occurs in 1-2% of the general pop
- affects more males than female
- familial inheritance 9%
- often occurs along with ascending aortic dilation which has 6% chance of rupture
bicuspid AV structure
- multiple configurations possible
- bicuspid with raphe or without raphe
raphe defintion
- seam that joins two cusps together
bicuspid AV - cusps fusion stats
- 85% RCC and LCC
- 15% RCC and NCC
7 things to look for with bicuspid AV
- thickened leaflets
- eccentric closure
- normal valve excursion
- systolic doming of LARGER cusp
- concentric LVH
- LV dilation
- LA enlargement
what is best view to see bicuspid
- PSAX
anomalies associated with bicuspid AV
- congenital membranes \+ subvalvular/supravalvular - supravalvular narrowing \+ ascending AO, AO arch or junction with descending A) - sub aortic LVOT obstruction \+ associated with HCM (hypertrophic cardiomyopathy) \+ asymmetric septal hypertrophy \+ systolic anterior motion of AML
Rheumatic AS
- caused by scarring from rheumatic fever
- inflammatory condition
- caused by beta-hemolytic streptococci
acute phase of rheumatic fever
- endocardial vasculitis = swelling leads to valve damage
- myocardium
- pericardium
- synovial joints
- lungs and pleura
- all of these have swelling which may or may not lead to swelling
rheumatic heart disease
- endocardial vasculitis \+ mitral MOST \+ aortic valve next \+ PV,TV - may resolve of lead to progressive scarring
2D parameters of estimating AS severity
- AV planimetry
how is AV planimetry assessed
- using hemodynamic parameters like \+ peak velocity \+ mean pressure gradient \+ aortic valve area \+ indexed aortic valve area \+ dimensionless velocity ratio
2D AV planimetry
- identify number of cusps
- assess cusp mobility and commissural fusion
- assess valve calcification
- trace orifice in mid systole
continuity principle
- volume of low proximal to and in the narrowing most be equal
continuity equation stroke volume
stoke volume LVOT = stroke volume AV
continuity equation CSA and VTI
- CSAlvot x VTIlvot = CSAav x VTIac
continuity equation rearranged to determine Aortic valve area (AVA)
AVA = (o.785 x LVOTd^2) x VTIlovt / VTIav
three things needed for AVA continuity equation
- obtain LVOT diameter
- obtain VTI of LVOT in PW
- obtain VTI of aorta using CW
continuity equation relationship = velocity and area
- increase in velocity through stenotic valve is inversely proportional to the reduction in area of valve
where to go to get good AV alignment
- LATERAL
what 4 places should you asses AV velocity is over 2.5m/s
- apical
- right suprasternal or right supraclavicular
- right parasternal
- +/- subcostal
rationale behind sampling 4 please when AV velcoty high
- highest velocity could be found at any of these locations
- highest velocity and VTI are used for the calculation unless an arrhythmia is present then they are averaged over 5 beats
continuity equation peak velocity method
- uses single pint only from LVOT and AV
- less accurate than VTI
- unable to incorporate velocity over time
- will overestimate stenosis if waveform is narrow with high peak velocity
continuity equation VTI method
- uses velocity -time integral which incorporates all of the velocities throughout the ejection period
- incorporates the parabolic shape of a waveform
- does not overestimate the degree of stenosis
velocity ratio - relationship to degree of stenosis
VR = velocity LVOT / velocity AV
- inversely related to degree of stenosis
velocity ratio using VTI
VTIlvot / VTI av
AV sclerosis - severity values
- = 2.5m/s
mild aortic stenosis - severity values
av jet velocity = 2.5-2.9m/s mean gradient = , 20mmHG AVA cm^2 = > 1.5cm^2 indexed AVA to BSA = > 0.85 velocity ratio = > 0.50
moderate aortic stenosis - severity values
AV jet velocity = 3.0-4.0 m/s mean gradient = 20-40mmHg AVA cm^2 = 1.0-1.5cm^2 indexed AVA to BSA = 0.6-0.85 velocity ratio = 0.25 -0.5
severe aortic stenosis - severity values
AV jet velocity = >4.0m/s mean gradient = > 40mmHg AVA cm^2 = < 1 cm^2 indexed AVA to BSA = < 0.6 velocity ratio = < 0.25
subaortic stenosis wave form characteristics
- late peaking profile (dagger)
- asymmetric
- very high velocity
- will cover in CMO
severe aortic stenosis waveform characteristics
- acceleration time = deceleration time
- symmetrical waveform
which starts later and ends earlier MR or AS
- AS
aortic stenosis with LOW EF
- low EF cannot generate enough force to push the blood out through the AV with high gradient/ velcoty
- gradients will be artificially low
+ IHD
+ CAD
+CMO
aortic stenosis with high EF
- increases force of contraction \+ fever \+ hypervolumia \+ pregnancy \+ LV overload due to moderate-severe AR \+ gradients artificially high
discrepancy of severity - severe velocity but not by area
- TECHNICAL ERRORS
+ LVOTd overestimated
+ LVOT VTI overestimated (measured to Cloe to AV)
= remeasure and recalculate AVA
discrepancy of severity - severe by area but not by velocity
- TECHNICAL ERRORS
+ LVOTd underestimated
+ LVOT VTI underestimated (measured to far from AV)
= remeasure and recalculate AVA
