Atherosclerotic aneurysm formation in an in situ saphenous vein graft.

Nonanastomotic aneurysm formation in autogenous vein grafts, although rarely described, has been uniformly associated with advanced atherosclerotic change of the vein wall. In the case reported, histologic examination of an in situ vein graft aneurysm demonstrates obliteration of normal vessel wall architecture by penetrating atherosclerotic plaque. Although these findings do not prove a causal relationship, they do provide additional support for atherosclerosis as an etiologic factor in aneurysm disease.