The accepted treatment for pulmonary embolism (PE) uncomplicated by hypotension or acute right ventricular failure is heparin (low molecular weight or unfractionated). When PE is complicated by hypotension (classified as massive) there is general acceptance of systemic thrombolysis in addition to heparin. More controversial is the intermediate situation, known as submassive PE, defined as PE with normal blood pressure but in the presence of acute right ventricular dysfunction. Right ventricular dysfunction is generally defined by echocardiography.
A randomized double blind placebo controlled trial in 2002 demonstrated that in submassive PE systemic thrombolysis added to heparin was associated with improved patient stability, less need to add hemodynamic support, but no difference in mortality. Controversy has persisted, and in the October 24 Archives of Internal Medicine are pro and con articles with rebuttals.    .