Interventional radiology in the treatment of pulmonary embolism.

Percutaneous therapy of pulmonary embolism is performed by local administration of thrombolytic agents or by mechanical canalization. The latter is achieved by fragmentation of the embolus with angiographic catheters, or by aspiration or fragmentation of the thrombus with dedicated devices. The pharmacologic basis of locoregional administration of thrombolytic agents, as in the treatment of deep vein thrombosis, is the possibility of reaching a higher concentration of the drug at the level of the embolus by decreasing the activity of systemic fibrinolysis, thus lowering the incidence of hemorrhagic complications. In recent years, locoregional thrombolytic therapy has been used only combined with mechanical canalization. The easiest way is direct fragmentation of the embolus with an angiographic catheter. The system of aspiration of pulmonary emboli, experimented by Greenfield is based on the use of a flexible catheter the tip of which is equipped with a plastic radiopaque cup. Recently, several rotating devices have been designed. Some have already been used for the peripheral arterial system, others are specific for the venous system (Schmitz-Rode-Gunther device). The clinical effectiveness of these devices is however still to be assessed. Other non conventional possibilities for the mechanical canalization of pulmonary arterial system are represented by metal stents and angioplasty with balloon catheters. At present, interventional radiologic procedures represent an additional tool in the medical or surgical therapy of severe pulmonary embolism, when it is contraindicated or ineffective.