The Hypoplastic Aorto-Iliac Syndrome: A Critical Approach to Its Pathogenesis

The clinical and angiographic features of 12 patients showing a significant reduction in the diameters of the distal aorta and the common iliac arteries are described. All the patients were women aged between 23 and 63 years (average age: 49 years), heavy smokers in the majority. An associated aortic arch syndrome was observed in 5 patients. Type IV dyslipidemia was found in 5. In 10 patients the erythrocyte sedimentation rate was increased. Claudication of the lower limbs, without dystrophic phenomena, was the most frequent symptom. Intraoperative biopsies of the distal aorta at the level of the aortic bifurcation were performed in 9 patients who underwent vascular surgery. In all the specimens an extensive fibrosis of the arterial wall was noted, but diffuse or focal lymphoplasmacellular infiltrates were also detected in 7 of them, with giant cells in 2 of the 7. The profile of small aorta and iliac arteries has recently been identified as an autonomous morbid process due to a developmental deficit with superimposition of atherosclerotic phenomena ("hypoplastic aorto-iliac syndrome" — HAIS). The clinical data and the histopathologic findings suggest, however, that several cases of HAIS can claim an acquired rather than a congenital origin. An arteritic process, causing an extensive fibrosis of the arterial wall, might be able to give rise to a noteworthy reduction in the aortic diameter. Among the possible inflammatory causes, Takayasu's disease (aspecifc aortoarteritis) seems to play an important role. The denomination HAIS seems, however, to be too restrictive. It should be replaced by "small aorto-iliac syndrome" (SAIS), which is noncommittal as regards the pathogenesis and applicable in any case.