Unusual fibrous band on the left aspect of the aortic arch

Abstract

During dissection of a 63-year-old female cadaver, a firm ribbon-like band was found on the left aspect of the aortic arch. Careful dissection showed that the band (6 cm long, 8 mm wide, 2 mm thick) connected the left superior intercostal vein with the accessory hemiazygos vein. Histological examination showed the fibrous structure of the band and showed the presence of a thread-like vascular lumen. The topography and venous connections of the band indicated its origin from persistence of the embryonic anastomosis between the left superior intercostal and accessory hemiazygos veins. This anastomosis derives from the rostral portion of the supracardinal vein that usually regresses on the left side but forms the terminal arch of the azygos vein on the right side. The severe atherosclerosis present in this patient at the level of the aortic arch may have enhanced the effects of arterial pressure on the adjacent venous anastomotic vessel causing reduction of blood flow and progressive fibrosis. The persistence of this venous anastomosis and its possible age-related fibrosis may have clinical relevance in central venous catheter placement.

(Mis)placed central venous catheter in the left superior intercostal vein

“…They develop from the same embryological structures – the main tract from the supracardinal vein and the terminal segment from the posterior cardinal vein 8. The left superior intercostal vein collects blood from the left second through fourth intercostal vein, and at the level of T3 or T4 it courses anteriorly along the lateral wall of the aortic arch and empties into the left brachiocephalic vein near the venous angle.…”