Systemic thrombolysis refers to infusing a large dose of clot busting medication through an IV in the arm. The drug goes to the pulmonary artery and breaks up the clot. It also goes to the rest of the body, so there is a reasonable chance that bleeding can happen elsewhere. In certain cases however, the benefit of breaking up the clot exceeds the risk of bleeding.
Catheter-directed thrombolysis has been developed by interventionalists to reduce the bleeding rate associated with systemic thrombolysis (see above). In this procedure, a catheter is guided through the deep veins and the heart and is embedded within the clot. The clot is dissolved over time (usually 24 hours) as the clot-busting medication is slowly dripped through the catheter into the clot. A much lower dose of the medication is given with catheter-directed thrombolysis, theoretically improving safety.
Cardiothoracic surgeons may open the chest and physically remove the clot in the pulmonary arteries. Usually, the patient is suffering from a severe PE for surgery to be necessary, although some hospitals use this surgery more liberally with very good results.