The early platelet uptake and distribution of platelets in small-diameter polytetrafluoroethylene (PTFE) vascular grafts in vivo.

Platelet deposition onto the surface of biomaterial is an important component of the interaction between blood and a prosthetic arterial graft. To understand the thrombotic process in small-diameter by-pass grafts, we used pigs to study the early in vivo uptake of 111In-oxine-labelled platelets in polytetrafluoroethylene (PTFE; GoreTex) grafts. In each experimental animal, 12 PTFE grafts (internal diameter, 3 mm; length, 5 cm) were placed in the femoral artery as interposition grafts. 111In-Labelled autologous platelets were injected. Sequential-scintillation camera images of the graft area were taken over a period of 3.5 h. Platelet deposition in vivo was calculated as an activity ratio for the entire grafts as well as for different segments of the graft. The grafts were harvested, cut into 0.6-cm pieces and weighed, and the 111In activity was measured. The distribution along the graft surface was calculated. Blood flow was measured continuously. The activity ratios rapidly increased, and a maximum was reached 60 min after the re-establishment of blood flow; thereafter the activity ratios slowly decreased. The distribution of platelets along the graft surface was found to be non-uniform where more platelets were deposited towards the distal anastomoses.