During the local fibrinolysis with rt-PA (2.5 mg/h) systemic plasminogen and alpha 2-antiplasmin activities slightly decrease, but the fibrinolytic system is compensated during the whole treatment. The d-dimer plasma levels increase dependently on the mass of thrombus. Despite the administration of high doses of heparin during the fibrinolysis thrombin is formed, measured as thrombin-antithrombin III complex (TAT).