 There is an unmet medical need to improve thrombolytic therapy in acute peripheral arterial occlusion PAO. Currently used plasminogen activators can result in increased circulating levels of plasmin that result in a systemic lytic state that does not distinguish between physiologic and pathologic thrombosis. In general, mean plasminogen activator infusion durations of greater than 24 hours in order to achieve successful thrombolysis are problematic in a disease where delayed restoration of arterial flow can lead to irreversible ischemic damage. A direct thrombolytic agent like alfimeprase, with a rapid mechanism of action and a potentially safer bleeding risk profile, could facilitate a rapid restoration of arterial flow and avoidance of open vascular surgery. 