Why does aortic arch dilates in aortic stenosis
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aortic stenosis ascending aortic dilatation mechanism post stenotic dilatation review
In aortic stenosis, the narrowed valve creates a high-velocity systolic jet. As blood exits through the small orifice, its velocity rises markedly, then the jet strikes the wall of the proximal ascending aorta just beyond the valve.
This causes post-stenotic dilatation through:
- Increased turbulence and wall shear stress distal to the stenotic valve
- Repeated mechanical trauma to the aortic media from the eccentric jet
- Progressive weakening and remodeling of elastic tissue in the aortic wall
The dilation is therefore usually in the aortic root/proximal ascending aorta, not the entire arch. Strictly speaking, if an exam says "aortic arch dilatation," it often means the visible proximal aortic contour on chest X-ray from post-stenotic dilatation.
It is particularly prominent with a bicuspid aortic valve, because there can be both an eccentric jet and an intrinsic aortic-wall abnormality (bicuspid aortopathy). A review of bicuspid valve disease describes this jet-related distal wall stress and post-stenotic dilatation.
Bailey and Love's Short Practice of Surgery, 28th Edition, section “Aortic stenosis,” lines 3548-3566.
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