Unusual cause of acute right ventricular dysfunction: rapid progression of superior vena cava aneurysm complicated by thrombosis and pulmonary thromboembolism.

Aneurysms of the major thoracic veins are rare. They are usually asymptomatic and thus treated conservatively. We report an extremely rare case of rapidly progressing superior vena cava (SVC) aneurysm complicated by thrombosis and acute pulmonary thromboembolism (PTE) with right ventricular dysfunction. Thrombolytic therapy for hemodynamically significant acute PTE was harmful to the patient in the present case, because it induced further thrombosis and mobilization of the thrombi within the aneurysm, subsequently causing de novo PTE. Surgical aneurysmectomy combined with pulmonary artery embolectomy would be a treatment of choice in patients with SVC aneurysm complicated by acute PTE.