... 10 4, 10 5aortic stenosis 77, 10 1–3aetiology 10 1–2assessment 10 3equations 14 1features 10 2peak pressure gradient 10 3, 10 2–3severity assessment 10 2aortic valve 59– 61 area 10 3bicuspid 12 2congenital ... defects 12 2–3disease 10 1–5early closure 90equations 14 1peak pressure gradient 10 3, 10 2–3, 11 1quadricuspid 12 3replacement 11 1univalve 12 2arrays 17 – 21 artefacts 35–9atherosclerosis 13 6atrial ... 13 6disease 13 6aortic incompetence 77, 10 5equations 14 1aortic insufficiency 10 3–5aetiology 10 3–4features 10 4pressure half time 10 4severity assessment 10 4–5aortic regurgitant fraction 10 4,...