In patients with grafts felt to be at high risk of occlusion (those in whom grafts have previously occluded, those with very long grafts, those with poor run-off or suboptimal conduit), the use of systemic anticoagulation will improve ° patency. The patient should be heparinized at the end of surgery (using IV UFH which can be turned off if post-operative haemorrhage occurs) and oral anticoagulation begun the next day, provided there is no sign of post-operative haemorrhage. Aim fora target INR of 2–2.5. The duration of anticoagulation depends on circumstances but should ideally be continued for the life of the graft.