Thrombolytic therapy for acute pulmonary embolism.

Thrombolytic therapy accelerates the dissolution of acute pulmonary embolism and is potentially lifesaving. The goal of this article is to offer a critical analysis of the use of thrombolytic therapy in this setting. Guidelines have been written and modified and new ones have been published over the past several years. Although an evidence base exists, unanswered questions remain. Despite the potential benefit of rapid clot lysis, nonpathologic thrombi are also lysed, so that thrombolytic therapy can cause significant bleeding complications. Massive acute pulmonary embolism is the clearest indication for these drugs, and although thrombolysis has been studied in submassive pulmonary embolism, this scenario remains more controversial. Traditionally, thrombolytic agents have been delivered intravenously, but intraembolic therapy via a pulmonary artery catheter has gained momentum. Few randomized trials have been conducted, however. Only three agents have been approved for use in the United States: streptokinase, urokinase, and tissue-type plasminogen activator. Urokinase is not currently available for use in the United States. The latter agent has been most widely used on the basis of proven benefit with a relatively short (2-hour) infusion. Newer, unapproved agents include tenecteplase and reteplase. Risk stratification in acute pulmonary embolism is important in determining which patients are the most appropriate candidates for thrombolysis, with careful consideration of contraindications.