[The value of thrombolysis for the treatment of acute pulmonary embolism]

Abstract

In the 1970s controlled studies in acute massive and submassive pulmonary embolism demonstrated by angiography, scintiscan and hemodynamic measurements that urokinase (UK) and streptokinase (SK) induce a more rapid dissolution of thrombotic material in the pulmonary circulation than heparin. Thousands of individuals would have been needed to prove a statistically significant reduction in the relatively low mortality (10-20%) in the study population. However, in massive pulmonary embolism with right ventricular overload, the advantage of thrombolysis is clearly evident. As confirmed by treatment series of varying size, SK and UK usually require 1-3 days for extensive clearance accompanied by impressive functional improvement. If contraindications are observed and invasive procedures avoided, the bleeding risk is acceptable. Acute severe pulmonary embolism with marked pulmonary hypertension but stable circulation should be treated with conventional doses of SK or UK for several days. In cases with unstable circulation or established shock vital improvement may be obtained by bolus injection (into pulmonary artery, right atrium or i.v.) of 2 m I.U. UK or by short i.v. infusion of 100 mg tissue plasminogen activator. Rapid reduction of pulmonary vascular resistance to a less critical value will prevent right ventricular decompensation and save time for embolectomy or subsequent conventional thrombolytic therapy.