Aortic Stenosis

1. Natural History

a) Aetiology

i) Congenital bicuspid with calcific degeneration

a) Currently most common

b) Symptoms 15 - 65 years

ii) Senile degeneration

a) 30% > 80 years have significant AS

b) symptoms > 70 years

iii) Rheumatic degeneration

a) Used to be most common cause

b) Asymptomatic for 40 years

b) Location

i) Valvular

ii) Subvalvular

iii) Supravalvular

2. Symptoms

a) Presence of symptoms is ominous - have < 5 years life expectancy

b) Angina

i) On exertion - AS only

ii) If at rest have coronary artery disease also

iii) due to high systolic intraventricular pressures

a) very little coronary blood flow during systole

(1) extra diastolic coronary blood flow required to compensate

b) hypertrophied heart has relatively deficient coronary supply

c) intraventricular pressures sometimes remain elevated during diastole—> coronary ischaemia & angina

c) Syncope

d) CCF

3. Pressure-volume loops

a) As the pressure gradient across the aortic valve develops, stroke volume is preserved by an increase in LV systolic pressure.

b) In the later stages of the disease, compromises in LV function lead first to marked elevations in LVEDP & LVEDV and finally to elevation of LVESV and reduced stroke volume

c) Each of these changes increases oxygen demands of an already compromised myocardium

4. Gross Anatomy

a) Hypertrophied left ventricle

b) Post stenotic dilatation of ascending aorta

5. Pathophysiology