Huge arteriovenous malformation in the mediastinum. Clinical presentation and surgical management.

A 24-year-old asymptomatic women presented with a large posterior mediastinal mass and a vertebral defect. Cardiac enlargement was found at roentgenographic and echocardiographic investigation. The ECG was abnormal and right heart catheterization showed cardiac output 17.1 l/min with a large left-to-right shunt at the level of the right atrium and the superior caval vein. The mass was seen on angiograms to be fed by numerous vessels originating from the descending aorta between the aortic arch and the coeliac axis. Computed tomography demonstrated a homogeneous, highly vascular structure. Radical excision was successfully accomplished in a two-step procedure aided by partial cardiopulmonary bypass. This seems to be the first report of a macrofistulous arteriovenous malformation in the mediastinum.