Midaortic syndrome (MAS) is an uncommon entity affecting children and young adults. It is characterised by progressive narrowing of the abdominal aorta and its major branches.
The onset of symptoms is usually during young adulthood or childhood 2:
- hypertension (most common)
- intermittent claudication
- renal failure
The exact cause is unknown in most cases though it is probably due to an insult during intrauterine life. Whilst intimal and subintimal fibrosis and fragmentation of the elastic media are seen, arteritis and atherosclerosis are characteristically absent in this condition.
Elastin arteriopathy in Williams syndrome can rarely be a cause 5.
Whilst involvement of any portion of the abdominal aorta may be seen, the interrenal segment including the origins of the renal arteries is invariably narrowed. Typically enlarged splanchnic collaterals (e.g. inferior mesenteric artery, arc of Riolan, the marginal artery of Drummond) are noted. The aortic bifurcation and iliac arteries are spared 3.
Treatment and prognosis
Endovascular treatment is the preferred mode as it is a minimally invasive treatment option. Balloon expandable stents / stent grafts are usually placed to expand the lumen of the aorta. Complex endovascular / surgical options such as fenestrated grafts with re-implantation of the renal arteries will be required if the renal arteries are involved.
Without treatment, life expectancy is dramatically shortened with most dying of ischaemic/hypertensive complications by age 40 4.
Imaging differential considerations include 2
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- 8. Veean S, Thakkar N, Gupta S, Keshavamurthy J. A case of coarctation of the abdominal aorta and renal artery stenosis due to neurofibromatosis type 1. Postgraduate medical journal. 93 (1098): 235-236. doi:10.1136/postgradmedj-2016-134460 - Pubmed