A case of paradoxical embolism "in situ" associated with massive pulmonary embolism: role of echocardiography.

A 49-year-old man was admitted in transfer for further management of a pulmonary embolism (PE) and possible mitral valve vegetation. Transthoracic echocardiography performed at our institution showed evidence of right ventricular (RV) enlargement and dysfunction. Within the right atrium was a serpentine mobile thrombus which traversed the interatrial septum at the level of the fossa ovalis and extended into the left atrium to the level of the anterior mitral valve leaflet. Because of the patient's dyspnea, RV dysfunction, and large clot burden, thrombolytic therapy was considered and would have been administered had the thrombus in situ not been identified. In light of the thrombus in situ and the concern about possible systemic embolization with thrombolytic therapy, the patient underwent successful surgical thrombectomy. This case highlights the importance of echocardiography in the management of patients with PE. We believe that all patients should undergo echocardiography prior to receiving thrombolytic therapy for pulmonary emboli. Careful interrogation of the interatrial septum for the presence of a thrombus in situ is warranted. Thrombectomy should be considered in individuals with PE who have a thrombus in situ.