Histologic fate and endothelial changes of distended and nondistended vein grafts.

Sixty-two autogenous cephalic vein segments were grafted into the femoral arteries of 31 mongrel dog: the left side receiving non-distended (control) grafts and the right side distended (experimental) grafts. Distending media were heparinized blood and saline. Veins were distended at 600 mm Hg for 2 minutes. Specimens were taken at intervals from 15 minutes to 3 months, and were studied by gross inspection, surface observations (light scanning stereoscope to X 70 scanning electron microscope to x 6,000) and routine histologic techniques (light microscope to X 1000). In general, grafting of veins in the arterial system was followed by progressive degenerative changes in all layers of the vein, including endothelial cell involution, desquamation and re-endothelialization. Often a variable degree of subendothelial fibrous and/or myoepithelial proliferation occurred which might compromise even a lumen lined by healthy endothelium. Distention caused these changes to occur earlier (2–4 weeks) and to be more pronounced. Distention with saline caused more damage to the endothelium than did distention with blood. We conclude that preimplant distention of vein grafts (to overcome spasm) should be employed sparingly, as it adversely affects the endothelial covering of the flow surface, accelerates the development of degenerative changes, and may predispose the graft to early thrombotic complications.