Aortic Stenosis Flashcards
What are the three causes of valvular stenosis?
Congenital Abnormality
Post inflammatory process (rheumatic)
Degenerative Calcification
In isolated stenosis, when do clinical symptoms typically occur?
when the orifice is reduced to 1/4 its normal size
In mixed stenosis, when do clinical symptoms typically occur?
When each is moderate
What is the ventricular response to pressure overload?
hypertrophy
What is the atrial response to pressure overload?
dilation
What is the ventricular response to volume overload?
dilation
Chronis pressure overload can lead to irreversible changes where?
in proximal chambers including the pulmonary vascular bed
What does a complete echo evaluation of valvular stenosis include?
Imaging of the valve to determine etiology
Quantification of stenosis severity
Evaluation of coexisting valvular lesions
Assessment of left ventricular systolic function
Response of chronic overload on proximal chambers and vascular bed
Aortic Stenosis Echo Findings
Thickened leaflets Restricted leaflet motion (with lack of normal systolic fluttering) Reduced AV orifice in systole Reduced ACS AI (found in 80%) LVH LAE Decrease LVSF late in course Post-stenotic dilation of the ascending aorta
What are the signs of inadequate cardiac output?
Dyspnea/DOE is the most common symptom Anginal chest pain (35%) Effort dizziness/syncope (15%) Hypotension Fatigue
What are the signs of overload to pulmonary venous system?
Dyspnea/DOE Orthopnea PND Cough Rales or crackles Sputum
What are the signs of overload to the right heart and cava?
Jugular venous distension Hepatomegaly (enlarged liver) Right upper quadrant pain Ascites (fluid in abdomen) Peripheral edema
What auscultation is associated with AS?
harsh mid systolic ejection murmur heard at Right Upper Sternal Border
crescendo-decrescendo
softened S2 (CA+ muffles snap)
also an S4 (decreased LV compliance)
What palpitation is associated with AS?
Pulsus parvus et tardus = rises slowly and is small and sustained
best heard at right carotid artery
What cath measurement has no echo equivalent?
Peak to Peak PG
What findings associated with AS will be present on an EKG?
LVH
LAE
What complications are associated with AS?
Increased risk of syncope and low SBP (narrow pulse pressure= difference between systolic and diastolic BP)
Lethal arrhythmia
Endocarditis
Systemic embolus
How would you treat AS?
Monitor symptoms and degree of stenosis to time AV replacement (activity restriction) AV Replacement (typically open heart surgery)
What possible medications would ease symptoms in heart failure?
Diuretics (decrease volume) Beta Blockers (slow rate and O2 demand) Nitrates (dilate coronaries and increase O2 delivery)
What possible medications would they use to treat AS?
Prophylactic antibiotics if deemed necessary
Controlled BP and lipid lowering drugs may slow progression
Etiologies and 2D findings:
Degenerative Calcification
- most common cause of AS
- calcification occurs over many years, reducing the systolic opening
- tends to present itself at age 70-85 (senile)
- 2D PSAX: valve very echogenic and filled in
- Reduced ACS
- Normally on M-mode AV cusps flutter when opening but NOT in AS
What is aortic sclerosis?
Valve calcification without stenosis or borderline stenosis
Where is the degree of stenosis determined?
CW/PW Doppler
Etiologies and 2D Findings:
Congenital Bicuspid
- most common congenital AS
- symptoms present at age 45-65
- 2D PSAX Diastole: valve can look normal/tri due to the presence of raphe
- 2D PSAX Systole: best identified as an oval or football shaped opening (not triangle)
- 2D PLAX: systolic/diastolic bowing/doming of leaflets into the aorta is a helpful identifier
- M-Mode: may show eccentric closure line
- May become calcific and stenosed, then harder to ID
- also look for AI, dilation of sinuses, and AR
What is a raphe?
a fusion line, crease, ridge or seam but not a true separation
runs across the larger leaflet
What are other forms of congenital AS?
Stenosed Unicusp: seen in childhood, young adulthood, or due to restenosis after valvotomy
seen as single eccentric orifice (teardrop) with prominent systolic doming
Quadricusp: rare and often picked up accidentally. most often associated with AI
Etiologies and 2D Findings:
Rheumatic Aortic Stenosis
- untreated strep infection leads to rheumatic fever which causes overactive antibodies to inflame and scan connective tissue and leaflets
- occurs concurrently with mitral rheumatic disease
- presents in young adults
- results in commissural fusion (fusion of commissures begins where the commissures attach to the annulus)
- 2D: increased echogenicity along the leaflet edges, commissural fusion and systolic doming
- 9% of AS due to Rheumatic
What does AS look like on color flow?
May pick up fast/turbulent jet past the aortic valve best seen in PLAX
Which assessments are used to quantify AS?
Velocity PPG MPG AVA by continuity equation AV Index V1/V1 Ratio
AS Velocity Norms
Borderline AS: <2.5 m/s
Mild AS: 2.6-2.9 m/s
Moderate AS: 3-4 m/s
Severe: >4 m/s
AS PPG Norms
Mild: <36 mmHg
Moderate: 36-64 mmHg
Severe: >64 mmHg
AS MPG Norms
Mild: <20 mmHg
Moderate: 20-40 mmHg
Severe: >40 mmHg
AS AVA Norms
Normal: 2.5 to 4.5 cm2
Mild: >1.5 cm2
Moderate: 1-1.5 cm2
Severe: <1 cm2
AS AV Index Norms
Mild: >0.85 cm2/m2
Moderate: 0.6-0.85 cm2/m2
Severe: <0.6 cm2/m2
AS V1/V2 Ratio Norms
Mild: >0.5
Moderate: 0.25-0.5
Severe: <0.25
What are the downfalls to using pressure gradients?
- dependent on volume flow rate
- elevated or reduced stroke volume can lead to erroneous conclusions regarding AS severity
- Examples of increased SV: anxiety, exercise, AI
- Examples of decreased SV: sedation, CHF, hypovolemia, MR
