ENDOTHELIUM ON THE FLOW SURFACE OF HUMAN AORTIC DACRON VASCULAR GRAFTS

Purpose: We have previously observed endothelium on two human vascular prostheses explanted under optimal conditions for flow surface preser vation. In this study we sought to further verify the hypothesis that endothelialization can occur on clinical grafts and that it can be det ected in specimens that have been promptly removed and properly preser ved in a timely manner, Methods: We studied 29 aortic grafts. Of these , 11 Dacron bypass grafts were in a condition suitable for analysis wi th light microscopy and immunocytochemistry staining, and scanning and transmission electron microscopy. Results: Three grafts had endotheli um beyond the pannus, identified by factor VIII/vWF, Ulex europaeus ag glutinin, and collagen IV positivity. Specimen A, a knitted 6-year imp lant, was preserved by embalming 3 hours after the patient's death and had a firmly attached outer capsule with fibroblasts, collagen, giant cells, and microvessels in the interstices. Specimen B, a woven 18-ye ar implant, was retrieved at reoperation and immediately fixed in 10% formalin; it had no outer capsule and no tissue ingrowth. Specimen C, a woven 7-year implant, was removed and fixed 5 hours after the patien t's death; it had a firmly attached outer capsule but no tissue ingrow th beyond the outer portion of the wall. Conclusions: The rapidity wit h which the specimens were fixed probably enabled identification of en dothelium. These findings suggest that endothelialization of synthetic arterial grafts may occur more frequently in human beings than previo usly recognized.