Aetiology of Aortic Stenosis

Congenital Acquired
Commonest cause in young adults. The valve can be bi- or unicuspid.
In pure AS in the under 70s who require surgery 50% had a calcified bicuspid valve.(1)
  • Rheumatic: Commonest cause world wide
  • Calcific (degenerative). Commonest cause in the UK. 50% of surgical cases in the over 70s. (1)
  • Rare causes. Rheumatoid involvement, irradiation and obstruction due to infected vegetations.

The aetiology of AS is shown in Table 1

In the Cardiovascular Health Study, 26% of over 65s and 37% of over 75s had age-related degenerative calcific aortic valve thickening causing a systolic murmur but without significant obstruction (aortic sclerosis) [2]. Approximately 2% of over 65s and 2.6% of over 75s had significant aortic stenosis.

Changes in the valves

The changes in the valves are similar to those seen in atherosclerotic vessels. Hypertension, smoking and raised cholesterol are all risk factors for aortic valve calcification. The image shows aortic stenosis due to rheumatic heart disease.