Aortic Stenosis

Question 1

Define Aortic Stenosis

Answer 1

Obstruction of left ventricular outflow due to narrowing at the level of the aortic valve

Question 2

Explain the aetiology/risk factors for aortic stenosis

Answer 2

• Senile degeneration (over 70) of the aortic valve due to calcification (80% of cases) -
  
  • this is said to be due to high pressure/turbulent flow across the valve which stimulates an inflammatory procedure leading to calcium deposition. So risk factors for degeneration include:
    
    • Hypertension
    • Smoking
    • Diabetes
    • High LDL cholesterol
• Calcification of congenital bicuspid aortic valve
• Rheumatic fever
• Chronic Kidney disease

Question 3

Summarise the epidemiology of aortic stenosis

Answer 3

• Present in 3% of 75 year olds
• More common in males
• Those with bicuspid aortic valve present earlier

Question 4

Recognize the presenting symptoms of aortic stenosis

Answer 4

• May be ASYMPTOMATIC to start, once symptoms start mortality drops significantly

CLASSIC TRIAD:

• Exertional dyspnoea (most common)
• Chest pain on exertion/angina (may occur in the absence of coronary atherosclerotic disease)
• Syncope

Question 5

Recognise the signs of aortic stenosis on physical examination

Answer 5

• Ejection-systolic murmur that radiates to carotids bilaterally
  
  • Loudest at the right upper sternal border
  • S2 may grow fainter the more severe it becomes due to decreased mobility of the aortic valve leaflets and single S2 is heard due to delayed aortic valve closing (A2)
  • In severe AS, S2 is split due to delayed aortic valve closure such that A2 comes after P2 (paradoxical split)
• Ejection click may be heard due to pliability of bicuspid valve upon coming into contact with ejected stream.
• S4 may be present due to LVH
  
  • Increases on expiration and diminished with hand grip –> increased afterload –> decreased LV-Aorta pressure gradient
  • Valsalva manoeuvre increases intra-thoracic pressure (e.g. straining for a poo/puff cheeks up, close nose and try to exhale) by trying to expire against a closed epiglottis. This positive pressure reduces preload/venous return so reduces most murmurs including AS but increases HOCM
• Pulsus tardus et parvus (late/after S1 and faint) carotid upstroke (Slow-rising pulse)
• Heaving, undisplaced apex beat (due to LVH)
• Thrill in the aortic area

Question 6

Identify appropriate investigations for aortic stenosis and interpret the results

Answer 6

Transthoracic Echocardiogram – diagnostic

• Estimation of the pressure gradient across the valve in systole
• Can estimate LV ejection function

ECG

• The main feature this will show is LVH and absent Q waves:
  
  • Deep S in V1/V2 and Tall R in V5/6
• LBBB or complete AV block

Cardiac angiography

• Allows differentiation from other causes of angina (e.g. MI) or assessment of concomitant coronary artery disease