Using expanded polytetrafluoroethylene for bridging arterial microvascular defects: an experimental study with evaluation in the scanning electron microscopy.

In an experimental investigation the replacement of arterial microvessels with microporous expanded polytetrafluoroethylene was studied. The infrarenal segment of the rat aorta was used as the scientific model. The inside diameter of the micrograft was 1 mm. Using microvascular techniques a total of 18 prostheses were inserted. The animals were harvested at time intervals from 3 days up to 3 months. Patency was determined by angiography and at autopsy. The aorta implant junction, the characteristics of the neointima development and the differentiation of the interstitial cells were studied by scanning electron microscopy. Fourteen of the implanted micrografts remained patent at the time of sacrifice, yielding an early patency rate of 77,7%. As shown by scanning electron microscopy, the development of the neointima took place in 2 stages. The initial fibrin/platelet layer was reduced after one month and replaced by a definite neointima with mononuclear cells, connected with interstitial cells. Investigation of the aorta-implant junction showed the prosthesis functionally embedded in the structure of the aorta. Expanded polytetrafluoroethylene as a prosthetic material for microvascular prostheses was easy to handle and emerged compatible with other tissues. It can be used as a substitute for bridging arterial microvascular defects.