Aortic stenosis

Question 1

Define aortic stenosis

Answer 1

Narrowing of the left ventricular outflow at the level of the aortic valve

Question 2

What is the pathophysiology of aortic stenosis?

Answer 2

Narrowed opening area of the aortic valve during systole → obstruction of blood flow from left ventricle (LV) → increased LV pressure → left ventricular concentric hypertrophy, which leads to:

Aortic stenosis → obstructs blood flow from left ventricle to aorta → increased LV pressure → left ventricular concentric hypertrophy → left heart failure → insufficient CO for metabolic demand

Left heart failure → backflow into the pulmonary veins
and capillaries → higher afterload on the right heart → right heart failure

Question 3

What is the aetiology of aortic stenosis?

Answer 3

1. Stenosis secondary to rheumatic heart disease - commonest worldwide
   (inflammation → commissural fusion → narrowed valve opening)
2. Calcification of a congenital bicuspid aortic valve
3. Calcification/degeneration of a tricuspid aortic valve in the elderly

Question 4

What is the epidemiology of aortic stenosis?

Answer 4

• Prevalence in 􏰅3% of 75-year-olds
• Males > females
• Those with bicuspid aortic valve may present earlier (as young adults)

Question 5

What are the symptoms of aortic stenosis?

Answer 5

May be asymptomatic initially.

Symptoms of insufficient CO due to left HF:

• angina (because of increased oxygen demand of the hypertrophied ventricles).
• syncope or dizziness on exercise

Symptoms of right HF:
- dyspnoea

Question 6

What are the signs of aortic stenosis?

Answer 6

BP: Narrow pulse pressure

Pulse: Slow-rising

Palpation:
- Thrill in the aortic area (if severe)
- Forceful sustained thrusting undisplaced apex
beat.

Auscultation:
- Harsh ejection systolic murmur at aortic area, radiating to the carotid artery and apex
→ crescendo-decrescendo murmur
- Second heart sound (S2) may be softened or absent (because of calcification)
- Ejection click (when valve snaps open)

Question 7

What investigations would you do for aortic stenosis and what would you expect to see?

Answer 7

1st line - echocardiogram and ECG

ECG: 
Signs of left ventricular hypertrophy 
- deep S wave in V1–2
- tall R wave in V5–6
- inverted T waves in I, aVL
- V5–6 and left-axis deviation

CXR:

• Post-stenotic enlargement of the ascending aorta
• Calcification of aortic valve (severe)

Echocardiogram:
Visualizes structural changes of the valves and level of stenosis (valvar, supravalvar or subvalvar)

Cardiac angiography:

• Allows differentiation from other causes of angina
• To assess for concomitant coronary artery disease (50% of patients with severe aortic stenosis have significant coronary artery disease).