Thrombolytic therapy in pulmonary embolism.

Pulmonary embolism has frequently been chosen for trials of thrombolytic therapy, not only because of its importance to public health, but also because the effects of therapy on the embolus can be readily appreciated by the use of pulmonary angiography, hemodynamics, and lung scans. Moreover, this lesion is theoretically the most attractive potential indication for thrombolytic agents, because its pathophysiologic effects are attributable to right heart strain rather than less reversible tissue necrosis, and because the emboli are usually in previously healthy vessels with ready access to a systemically administered lytic agent. The disadvantages of studying this lesion are its high sudden death rate, which leaves only less severe cases for study, and the demonstration that spontaneous fibrinolytic activity itself may result in the clearing of the pulmonary arterial tree. 2, 3 Clinical trials have been carried out with both streptokinase and uroki-