What are the three causes of valvular stenoses?
- Congenital abnormality
- Degenerative calcification
- Postinflammatory process (rheumatic)
In isolated valve stenosis, when do clinical symptoms typically occur? What happens when the valve is both stenotic and regurgitant?
In isolated valve stenosis, symptoms typically occur when the orifice is reduced to ¼ its normal size.
In mixed stenosis and regurgitation, sx can occur when each is moderate
What steps does a complete Echo evaluation of valvular stenosis include?
- Imaging of the valve to determine the etiology
- Quantification of stenosis severity
- Evaluation of coexisting valvular lesions
- Assessment of LV systolic function
- Response of chronic overload on upstream chambers and vascular bed
What are the primary findings of AS?
- Thickened leaflets
- Restricted leaflet motion with lack of normal systolic fluttering
- Narrowed valve orifice
What are secondary findings of AS? Which is the most common?
- AI (80%)
- LVH due to pressure overload, leads to increased LVEDP and LAP
- Decreased LVSF late in course
- Post-stenotic dilatation of the ascending aorta (follow aorta in the PSLAX or SSN)
What are the signs/symptoms of AS? Which is most common?
- DOE = most common sx of AS
- Sx of LCHF: DOE, dyspnea, cough, orthopnea, paroxysmal nocturnal dyspnea, crackles, fatigue (50%)
- Angina (35%)
- Dizziness/syncope with exertion (15%)
- Right heart failure late in course: JV distention, hepatomegaly, peripheral edema, ascites
- Narrow pulse pressure (decreased SBP)
- Parvus et tardus palpation of RCA
What can typically be heard with AS on auscultation?
- Muffled S2
- Harsh mid-systolic ejection murmur
- S4 (grunt) with decreased LV compliance
What does the cath tracing of AS look like?
- LV pressures rise much higher than aortic pressure during systole
- Aortic root pressure decreased, curve appears sunken in during rise with later peak, narrower pointed tip
- >>shorter ejection period: longer R-wave to onset of flow
- loss of dicrotic notch
What are possible EKG findings of AS?
- LVH ( >QRS amplitude: voltage criteria; i.e., tall R-waves in LV leads, deep S-waves in RV leads)
- LAE (wide p-wave)
What are possible risks/complications of AS?
- Increased risk of syncope and low SBP (narrow pulse pressure)
- Lethal arrhythmias
- Systemic embolus
When does AS with valve calcification tend to present?
When does congenital (bicuspid) AS typically present?
- Calcified/senile valvular stenosis tends to present at ages 70-85
- Bicuspid valve congenital AS typically presents at age 45-65
How do calcified valves appear on 2D and M-Mode?
- Calcified valve appears very echogenic and filled in
- Normal M-Mode AV cusp flutter not seen in AS
- Reduced ACS <1.5cm, <.8cm severe (degree of stenosis determined by CW/PW Doppler)
What does bicuspid AV valve look like on 2D/M-mode?
- short axis shows only 2 leaflets open in systole
- long axis bowing of leaflets into aorta gives domelike appearance (doming in diastole as well)
- M-mode may show eccentric closure line
- typically anterior or rightward leaflet is larger with a raphe which makes it look tricuspid in diastole
What is a unicuspid valve? When does it occur/appear? What does it look like?
- Congenital unicuspid valves causing AS may be seen in childhood, young adulthood
- may be due to restenosis after valvulotomy
- seen as single eccentric orifice (teardrop) with prominent systolic doming
What causes Rheumatic AS? When does it occur/present? How does it appear in 2D?
- 9% AS due to Rheumatic - strep bacteria attacks connective tissue, Rheumatic Heart Disease
- occurs concurrently with mitral rheumatic disease
- presents in young adults
- results in commissural fusion of the aortic leaflets
- 2D shows increased echogenicity along leaflet edges, commissural fusion and systolic doming
How does AS present in Color flow Doppler?
turbulent (aliased) jet seen past aortic valve due to increased velocities and post-stenotic turbulence
What methods may be used to quantify AS?
- PPG (Bernoulli equation)
- MPG (Doppler trace)
- AVA (continuity equation)
- Aortic valve index
- V1/V2 ratio
How do you calculate PPG?
PPG = 4 (V22 - V12)
If V1<1 m/sec use simplified Bernoulli: PPG = 4 (V22)
What are the Peak Pressure Gradient Norms for AS?
- <36 mmHg = mild AS
- 36-64 mmHg = moderate
- >64 mmHg = Severe AS
What are the Mean Pressure Gradient Norms?
- <20 mmHg = mild AS
- 20-40 mmHg = moderate
- >40 mmHg = severe
What are the disadvantages of using pressure gradients?
- Dependent on volume flow rate
- elevated or reduced SV can lead to erroneous conclusions regarding severity of AS
- (SV increase due to anxiety, exercise, AI, etc; decrease due to sedation, CHF, hypovolemia, MR)
significant AI >> incr. SV >> incr. velocity >> incr. PPG/MPG >> AS looks worse than it really is
How do you calculate AVA?
Continuity equation: AVA cm2 = .785 * LVOTd2 * VTI lvot / VTI av
Simplified Continuity equation substitutes max velocities for VTIs:
AVA cm2 = .785 * LVOTd2 * V1/V2
* LVOT diameter needs to measured 3 times
What are the AVA norms?
- Normal = 2.5 - 4.5 cm2
- Mild AS = > 1.5 cm2
- Moderate = 1.0 - 1.5 cm2
- Severe = < 1 cm2
What are cautions to the continuity equation quantification of AS?
- It can overestimate the severity of AS in patients with significant LV dysfunction.
- (Low dose dobutamine can be given to increase SV and AVA in suspect cases)
Subaortic stenosis may be mistaken for AS
LVOTd can be difficult to measure errors are squared - some physicians encourage LVOTd close to 2cm
What is the Aortic Valve Index? What is a normal range?
AV Index = AVAcm2
- Mild = >.85
- Moderate = .6 - .85
- Severe = < .6
What is the significance of the V1/V2 ratio?
Normal V1/V2 = 1
Ratio of .5 indicates valve area is half normal, .25 = 1/4, etc
Generally, V1/V2 < .25 is considered severe (AVA <.75cm2
- Mild: > .5
- Moderate: .25 - .5
- Severe: <.25
Advantages: takes LVOT diameter out of equation, allows easy tracking of patient over time
What is the Pedoff probe? Where is it used and what can it measure?
small, non imaging probe can obtain the highest velocities or VTI through the AV
used at the apex, RSB and SSN