Histopathological changes in the pre-aneurysmatic segment of the abdominal aortic aneurysms

In Abdominal Aortic Aneurysms (AAA) the preaneurysmatic segment is a critical zone for the following reasons: 1) it corresponds to the site where the prosthetic graft is usually suturated; 2) as it assumes a cylindrical shape, its parietal tension (T=P.r/h) is two times that of the spherical sac(T=P.r/2h) of the aneurysm; 3) it is, frequently, the starting point of aneurysm dissection. In this report the pathological features occurring in this tract of the aneurysmatic complex are shown. In four cases of the sacciform AAA, a transverse-2cm height ring, at the preaneurysmatic tract, corresponding to the point where the prosthesis will be fixed, was removed during surgical intervention. From the ring three specimens, 1cm in length, in the lateral (left and right) and in the ventral sides of the vessel, were isolated for the histological examination. The samples were stained with Weigert and Gomori methods. . Profound degenerative changes were present in at least one or in all three sectors. Extreme thinning of the aortic wall, intimal proliferation, disruption of the lamellar build of the media, were particularly pronounced in the lateral segments. . These degenerative changes in a zone which might appear, at surgery, preserved enough from pathological lesions, could contribute to explain some post-surgical complications at the proximal sutural lines of the graft.