Aortic stenosis

Question 1

Define

Answer 1

• Narrowing of the left ventricular outflow at the level of the aortic valve
• Obstruction of blood flow across the aortic valve due to aortic calcification.

Question 2

What’s the aetiology?

Answer 2

• Stenosis can be secondary to rheumatic heart disease (MOST COMMON WORLDWIDE)
• Calcification of a congenital bicuspid aortic valve
• Calcification/degeneration of a tricuspid aortic valve in the elderly (most common in Europe)

Patients with chronic kidney disease are at more risk as well.

Question 3

What’s the pathophysiology?

Answer 3

Aortic calcification is no longer thought to reflect age-related wear and tear, and is recognised to be an active process. The valvular endocardium is damaged as the result of abnormal blood flow across the valve. Endocardial injury initiates an inflammatory process similar to atherosclerosis and ultimately leads to deposition of calcium on the valve. Calcification occurs slowly and is subclinical until the disease is fairly advanced. Progressive calcium deposition limits aortic leaflet mobility and eventually produces stenosis.

Unicuspid and bicuspid valves experience abnormal shear and mechanical stresses from birth. Therefore, the pathological processes and resultant stenosis occur earlier than in trileaflet valves.

Question 4

What’s the epidemiology?

Answer 4

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

Question 5

What are the presenting symptoms?

Answer 5

• May be ASYMPTOMATIC initially
• Angina (due to increased oxygen demand of the hypertrophied left ventricle)
• Syncope or dizziness on exercise (due to outflow obstruction)
• Symptoms of heart failure (e.g. dyspnoea, orthopnoea)

Question 6

What are the signs?

Answer 6

• Narrow pulse pressure
• Slow-rising pulse
• Thrill in the aortic area (only if severe)
• Thrusting undisplaced apex beat
• Ejection systolic murmur at the aortic area, radiating to the carotid artery.
A systolic murmur ≥3/6 is present with a crescendo-decrescendo pattern that peaks in mid-systole and radiates to the carotid

• Second heart sound may be softened or absent (due to calcification)
• A bicuspid valve may produce an ejection click

Question 7

What are the appropriate investigations?

Answer 7

• Echocardiogram (including Doppler) – diagnostic
o Visualises structural changes of the valves and level of stenosis (valvar, supravalvar or subvalvar)
o Estimation of aortic valve area and pressure gradient across the valve in systole
o Assess left ventricular function
• ECG
o Signs of left ventricular hypertrophy
• Deep S in V1/2
• Tall R in V5/6
• Inverted T waves in I, aVL and V5/6
• Left axis deviation
o Absent Q waves
o Some: AV block or BBB
• CXR
o Post-stenotic enlargement of ascending aorta
o Calcification of aortic valve
• Cardiac angiography
o Allows differentiation from other causes of angina (e.g. MI)
o Allows assessment of concomitant coronary artery disease
• NOTE: 50% of patients with severe aortic stenosis have significant coronary artery disease