There is no dilemma. As you yourself state "ASRA recommendations advice avoiding anticoagulants after traumatic epidural for 24 hours if possible or weighing of risk - benefit ratio in such a scenario." Weighing the risk an epidural haematoma against the near certainty of a graft shutdown with the patient losing a leg, I'd choose to give the heparin. However I admit it's not a choice I'd like to have to make. Luck would definetely play a major role