Laminar flow due to venous valves masquerading as vein graft spasm

Two cases of laminar flow at the venous valves were found to produce a tapered appearance of the vein grafts, similar to spasm, during angiography. This possibility should be kept in mind when considering the diagnosis of spasm in a vein graft during postoperative angiographic studies. In addition, the follow-up of these cases suggests that valves may predispose to later stenosis or occlusion of the vein grafts.