Middle Aortic Syndrome: From Presentation to Contemporary Open Surgical and Endovascular Treatment

Abstract

Middle aortic syndrome (MAS) is a clinical condition generated by segmental narrowing of the abdominal or distal descending thoracic aorta. MAS may be acquired, caused by Takayasu's or temporal arteritis (giant cell arteritides), neurofibromatosis, fibromuscular dysplasia, retroperitoneal fibrosis, mucopolysaccharidosis, and the Williams syndrome, or congenital, ascribed to a developmental anomaly in the fusion and maturation of the paired embryonic dorsal aortas. Segmental aortic stenosis may be located at the suprarenal, inter-renal or infrarenal aorta, with a high propensity for concomitant stenoses in both the renal (63%) and visceral (33%) arteries. Hypertension proximal to the aortic stenosis, and relative hypotension distal to it, are characteristic findings in MAS. Typical manifestations include headache, early fatigue on exertion, and bilateral lower-limb claudication. The severity of hypertension is the primary indication for intervention and the factor determining procedural timing. As a great proportion of patients with MAS are children or teenagers, the clinical benefits of early surgical intervention to reverse refractory hypertension have to be weighed against the repercussions pertaining to the insult of surgery on the developing aorta. Open surgery is the primary treatment of tubular aortic narrowing (MAS) associated with renovascular hypertension and visceral artery stenosis. This entails aortoaortic bypass of the diseased segment or, less often, patch aortoplasty and usually bypass grafting of the stenosed renal and visceral arteries performed with autologous conduits, particularly in the youngest of patients. Endovascular therapy may provide a sound minimally invasive treatment in MAS caused by discrete aortic stenoses that do not encompass the mesenteric and renal arteries. Hypertension is thus improved or cured in more than 70% of patients. Prognosis after uncompromised surgical reconstruction is rewarding in the mid and long term in patients with congenital aortic coarctation but deteriorates in patients with aortoarteritis and recurrent inflammatory activity.