Thrombolytic treatment of venous thromboembolism.

From the Vascular Laboratory, St. Elizabeth’s Hospital, Boston, Massachusetts. The objective of thrombolytic therapy is to accelerate the rate of clot lysis or to induce it when natural activation of the lytic system is inadequate. In deep vein thrombosis involving the lower extremities, reduction in the incidence of venous insufficiency is the major goal. Complete lysis of venous thrombi has been reported in 40%’ to 60%3 of streptokinase-treated patients, compared to about 10% of those treated with heparin. When thromboembolic occlusion involves other sites, such as the hepatic or renal veins or the pulmonary arteries, thrombolytic therapy may improve vital organ function or may even be life-saving. However it should be emphasized that the long-term clinical benefits of streptokinase or urokinase have not been proven. What has been demonstrated in clinical trials is that thrombolytic therapy is more effective than heparin in dissolving venous thrombi-1--5 and that these drugs significantly accelerate the rate of lysis of pulmonary emboli compared to heparin. 6