Thrombolytic therapy: overview of results in major vascular occlusions.

Thrombolytic therapy provides clinical benefit in patients with vascular occlusions, depending upon the organ or limb that is threatened. The impact of therapeutic intervention varies from the quiet alteration of the course of deep vein thrombosis, for which non-life threatening post-phlebitic syndrome can be largely avoided, to the sometimes striking reversal of pulmonary hypertension and possible life-saving benefit in massive pulmonary embolism, the immediate alteration of clinical course in acute peripheral arterial occlusion by reducing the need for surgical intervention, cardiopulmonary complication and one year mortality, and finally to the dramatic and life-saving potential when applied in patients with acute myocardial infarction. Since the risk of serious hemorrhage, especially intracranial hemorrhage, is a constant, regardless of the underlying thrombotic problem, thrombolytic therapy will necessarily be applied variably according to the different potential therapeutic benefits. The balance of potential benefit versus the risk of intracranial hemorrhage in the situation of cerebrovascular thrombosis and stroke remains to be clarified by ongoing studies. As to the evidence for superiority of any single thrombolytic agent or regimen, direct comparative studies are still needed for patients with venous thrombosis and arterial occlusion. Available direct comparisons of two or three agents (streptokinase, urokinase, alteplase and anistreplase) in studies of pulmonary embolism and myocardial infarction show a consistent pattern that documents positive clinical benefit for all of the agents, with striking similarity in quantitative aspects despite marked differences in biochemical properties of the agents.