Platelet-surface interaction: effects of dextran 70 on platelet retention in extracorporeal surfaces

Distal embolisation from the surface of PTFE grafts in vivo and the effect of low molecular weight dextran

Platelet deposition onto the surface of biomaterial is an important component of the interaction between blood and a synthetic arterial graft. Once platelet deposition has occurred, the possibility of distal embolisation exists. Using PTFE interposition femoral grafts and Indium-III-levelled autologous platelets in 16 adult sheep we have studied platelet uptake onto the graft surface using a gamma camera. Radioactivity in the legs was measured by a miniature cadmium-Telluride counter and blood flow was simultaneously recorded. In 8 animals low molecular weight dextran (LMWD) was infused intravenously. It was found that platelet deposition onto PTFE grafts was significantly lower in the LMWD treated group than in controls (P less than 0.001). These differences were confirmed by histological examination and in vitro measurement of graft activity. Furthermore, distal embolisation was frequently seen in both groups with a simultaneous drop in graft activity seen in both groups with a simultaneous drop in graft activity with an increased activity in the peripheral circulation. This distal embolisation was less pronounced in the LMWD treated group.