SCINTIGRAPHIC ASSESSMENT OF FOCAL PLATELET ACCUMULATIONS FOLLOWING INFRAINGUINAL BYPASS-SURGERY IN HUMANS

Enothelial injury is assumed to be of pathogenetic significance in the development of graft stenoses, which remain a major cause of failure of peripheral bypasses. The aim of this study was to assess endothelia l injury related to infrainguinal bypass surgery by indium-111 platele t scintigraphy. In 28 patients undergoing in situ vein (n = 24), compo site vein-polytetrafluoroethylene (PTFE) (n = 1) or PTFE (n = 3) bypas s surgery, assumed vascular injuries were recorded intraoperatively. A utologous indium-111-labelled platelets were injected into the inflow artery immediately after restoration of flow in the graft. Platelet de position was assessed by gamma-camera images of thigh and crus obtaine d 4 and/or 24 h after surgery. Areas of focally increased activity wer e recorded and graded as moderate or intense. In the 24 vein bypasses, a median of two (range 0-5) areas of focally increased radioactivity were seen at the proximal anastomosis (n = 21), in the body of the gra ft (n = 20) or at the distal anastomosis (n = 9). The activity was mod erate in 27 cases and intense in 23 cases. Scintigraphic evidence of f ocal platelet aggregation in vein grafts was not correlated with preop erative antiplatelet therapy or vein graft diameter. Only 2 of the 20 intragraft platelet depositions occurred in areas where intraoperative vascular injury was suspected. In the composite graft and the PTFE gr afts, diffuse activity was observed throughout the entire bypass. In c onclusion, focal activity accumulations, suggesting localized endothel ial injury, were observed in the majority of in situ vein bypasses, in particular at the sites of the anastomoses. Prosthetic bypasses were characterized by diffuse platelet aggregation.