The uptake of platelets, fibrinogen and leucocytes in ePTFE vascular grafts in relation to blood flow--an experimental study in sheep.

The uptake of platelets, fibrinogen and leucocytes in relation to blood flow was studied in ePTFE arterial grafts inserted in both common carotid arteries of 10 adult sheep. Autologous platelets labelled with In-111, autologous leucocytes labelled with Tc-99m and homologous fibrinogen labelled with I-125 were used. The leucocyte uptake was studied in five of the animals. The uptake was measured with a gamma scintillation technique. The blood flow in the graft on one side was restricted to 25 ml/mm, and in the other graft the blood flow was unrestricted (median 170 ml/min). One out of 10 grafts in the reduced flow group occluded but none of the grafts in the unrestricted flow group. The mean thrombus weight was significantly higher in the reduced unrestricted flow (0.28 vs. 0.19 g). At the proximal anastomosis the uptake of platelets, fibrinogen and leucocytes was higher in the reduced than unrestricted flow. The differences were significantly higher for fibrinogen for the whole duration of the experiments and for platelets and leucocytes during the last 48 min. Distally the platelet and fibrinogen uptake were higher in the reduced than in unrestricted flow. The leucocyte uptake did not differ distally. The differences were significant for fibrinogen for the whole duration of the experiments and for platelets during the last 120 min. A comparison between the proximal and distal anastomosis showed a higher uptake distally.