IRCT201104245625N2 IRCT 2011-08-28 Vice Chancellor for research,Tehran Heart Center (TUMS) streptokinase in acute pulmonary embolism Comparative efficacy and complications of Two–Hour versus 24-Hour Regimen of Streptokinase in Acute Pulmonary Embolism In Tehran Heart Center 2011-03-21 anticipated 60 Complete https://irct.ir/trial/6153 interventional Randomization: Randomized, Blinding: Not blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment. 2-3 Acute Pulmonary Embolism. Intervention 1: Intervention: in this group patients will be received 1.5 million Units venous streptokinase, infused during 2 hours. Before treatment starting, Echocardiography and CT- angiography achieve for all patients (intervention and control group). Pulmonary artery pressure (PAP) measure by Echocardiography. 24-72h after treatment ending, second Echocardiography will be done. In all patients aPTT measure after streptokinase therapy. If aPTT be less than twice normal value, heparin therapy begins and if be more than this value, this test repeat per 4 hours while become less than twice normal value. Intervention 2: In control group, 250,000 Units bolus Streptokinase infuse during 30minutes and then 100,000 Units per hour infuse during 24 hours.