Track 7: Aortic Stenosis

Question 1

Changes in hemodynamics with AS

Answer 1

• Obstruction that begins on aortic valve opening
• LV pressure becomes much higher than aortic pressure
• Aortic pressure becomes dampened and slow rising
• Gradient between LV and LA
• Compensatory overload
• LV diastolic dysfunction
• Increased LV pressures

Question 2

Explain how pressure abnormalities in AS translate to physical exam

Answer 2

1 Systolic ejection murmur at RUSB, after S1 ends at S2

• Murmur begins after S1
• Crescendo decrescendo murmur
• In calcific AS (S2 may be very quiet or inaudible)
• LV diastolic pressure rising b/c of hypertrophy at time atrial contraction you may hear S4 \

#2 S4 d/t hypertrophy
#3 Feel carotid artery to appreciated dampened aortic pressure (delayed carotid upstroke) “pulsus parvus et tardus”

Question 3

How does AS impact the LV and LA?

Answer 3

• Cavity size stays normal but the myocardium significantly increases and thickens in a concentric manner
  “LVH”
• Increased mass of LV, oxygen demand mismatch occurs, sxs of angina occur despite normal coronary arteries
• Diastolic dysfunction, ventricular diastolic pressures elevated, translates to LA pressures being elevated
  (High pressure back to pulmonary circulation leading to shortness of breath)

Question 4

Explain the mechanism behind dyspnea/DOE, syncope, and angina in AS

Answer 4

• LV diastolic dysfunction, ventricular diastolic pressures elevated. Translates to LA pressures being elevated. High pressure back to pulmonary circuit causing shortness of breath
• LVH, increased mass of LV, oxygen demand mismatch, sxs of angina (despite what may be normal coronaries)
• In extreme/severe obstruction blood may not be able to exit ventricle (especially during exercise), hypo-perfusion to brain, leading to syncope

Question 5

How can you assess AS severity based on the murmur?

Answer 5

Late peaking murmur = more severe
S4 more severe
Delayed carotid upstroke more severe

Question 6

Outline the stages of AS

Answer 6

Stage A: At risk for disease (hx of rheumatic fever, bicuspid valve, atherosclerosis (at risk for “senile AS”))

Stage B: Develop stenosis, asx, < severe stenosis

Stage C: Severe stenosis, asx
C1: normal EF
C2: decreased EF

Stage D: Severe stenosis, symptomatic

Question 7

Define severe stenosis

Answer 7

Mean gradient > 40 mmHg
AVA < 1 cm^2

Question 8

When do you start to see a decrease in survival with AS?

Answer 8

Stage C1: decreases slightly
Stage C2: decreases more
Stage D: most important, survival markedly decreases once onset of sxs develops

Question 9

Indications for AVR (Class I and Class IIa)

Answer 9

Class I:
- Severe, symptoms, Stage D
- Severe, asx, decreased EF < 50% (maybe even <55-60%), Stage C2

Class IIa:
- Stage C1, especially if you they drop BP during stress test
- BNP > 3x ULN
- Rapid progression of disease, (ie AVA generally decreases by .1 cm^2 per year, if decreases > .1 cm^2 per year considered rapid
- Very severe Stage C1 AAS with mean gradients > 60 mmHg