Pseudoendothelium formation in expanded polytetrafluoroethylene grafts implanted in the inferior vena cava of normal and defibrinogenated dogs.

The outgrowth of endothelial cells in an expanded polytetrafluoroethylene graft implanted in the canine inferior vena cava was studied by scanning electron microscopy. The adjacent endothelial cells of the vena cava started to invade the anastomotic area three days after the implantation and reached approximately the central part of the 2-cm-long graft after 21 days. There was no obvious difference in the process of endothelialization between the control group and the moderately defibrinogenated group, in which the fibrinogen concentration was at most 0.72-0.87 gm/L. A slight delay in the outgrowth of endothelial cells was noted within the first seven days in the severely defibrinogenated group, in which the fibrinogen concentration was below 0.40 gm/L. After 70 days, all grafts were completely covered by endothelial cells. The structural difference of the mural thrombus resulting from reduced fibrin formation might be a major factor influencing the endothelium formation.