Protection of endothelium in vessel segments excised for grafting

Contracture and collapse often complicate dissection and excision of blood vessels for grafting. Subsequent forceful redilatation and leak checking with cold saline almost always lead to partial or total denudation of endothelium, which increases the risk of early occlusion by thrombi or late occlusion by fibrocellular initimal thickening. To prevent endothelial damage, we used three major modifications of the excision and extracorporeal maintenance procedures: (1) adventitial application of the smooth-muscle relaxant papaverine in situ to avoid contracture and to allow subsequent gentle, gradual redilatation at low pressure; (2) balanced perfusion and maintenance fluid containing 10% protein (serum of albumin); and (3) extracorporeal maintenance of the vessel at body temperature. In an experimental extracorporeal vascular perfusion system, we could preserve morphologically intact endothelium of rabbit carotid arteries for over 3 hours, as evaluated by scanning electron microscopy. Applying the same principles to canine cephalic and saphenous veins, we gradually dilated the vessels at pressures as low as 100 mm Hg and obtained a morphologically intact endothelium after 1 hour of extracorporeal maintenance.