Spontaneous Re-Canalization of Thrombosed Polytetrafluoroethylene (PTFE) Grafts

Abstract

Fibrinolysis is an important hemostatic process initiated either by tissue plasminogen activator (tPA) or pro-urokinase (pro-UK) released from endothelial cells. These agents act preferentially on plasminogen by converting it to the active molecule plasmin. This initiates the clot lysis process, which may take several days for completion. Most patients with end-stage renal disease (ESRD) have PTFE grafts for chronic hemodialysis. When these grafts are thrombosed, they are either surgically revised or percutaneously thrombolysed. When these measures fail another access is created without removing the clotted graft. However, it is possible that de-clotting of these thrombosed PTFE grafts can occur spontaneously. Once the graft develops an endothelial lining, these cells can contribute to the fibrinolytic process by secreting tPA or pro-UK. Because this endothelial lining may be less developed than that of a normal vessel, the fibrinolytic process may occur at a slower rate or not at all. Frequent cannulation during hemodialysis can denude existing endothelium, further contributing to the inadequacy of the graft to initiate thrombolysis. In practice, once the PTFE is clotted, the graft is ignored if it is not considered for declotting. In such circumstances the re-canalization process could be overlooked, re-sulting in the unnecessary placement of additional accesses. Presented here are three patients with clotted grafts in which re-canalization occurred without intervention.