ABSTRACT
The present study represents a long-term investigation of polytetrafluoroethylene
(PTFE) vascular microprostheses implanted in the right common iliac artery of rats,
with the aim of evaluating the degree of intimal hyperplasia and the changes produced
in the vascular prosthesis. A follow-up study was performed between 3 months and 1
year post-implantation, using immunohistochemical techniques, light, and electron
microscopy. Three months after implantation, the PTFE segment appeared sandwiched
between two cell layers. A general endothelialization was observed on the luminal
surface. The underlying myointima appeared as an irregular lining of decreasing thickness,
from the distal anastomosis with the receptor artery to the proximal suture. A large
number of white blood cells were found adherent to and infiltrating the endothelium.
A neoformed adventitia covered the prosthesis on the external surface. At 4 months
post-implantation, a destabilization of the luminal surface was observed induced by
white blood cells. A progressive reduction in the thickness of the myointimal layer
was also apparent, so that 1 year after implantation, the luminal surface of the PTFE
prosthesis was fully lined by a thin cell covering. There is good long-term tolerance
to implanted PTFE microprostheses. The white blood cells present in the implant region
appeared to play an important role in the long-term regression of intimal hyperplasia.
