Left Superior Intercostal Vein

vena intercostalis superior sinistra

The left superior intercostal vein drains the second, third, and sometimes fourth left intercostal spaces and crosses the aortic arch anteriorly before joining the left brachiocephalic vein. It is visible on chest radiograph as the aortic knuckle companion or as a nipple of soft tissue density projecting from the aortic arch. It communicates with the left hemiazygos system inferiorly.

Region: Chest

Clinical Relevance

Clinical Notes

The left superior intercostal vein appears on chest CT as a tubular vascular structure crossing anterior to the aortic arch in the left para-aortic position. It must be distinguished from lymphadenopathy, aortic pseudoaneurysm, and mediastinal masses. It is enlarged in SVC obstruction as a collateral drainage route. The vein is at risk during thoracic surgery and thoracic aortic procedures involving the aortic arch, where its inadvertent division causes venous bleeding.

Pathology

Common Injuries & Conditions

Left Superior Intercostal Vein as Aortic Arch Pseudomass

The left superior intercostal vein crossing the anterior aortic arch produces a rounded density on chest radiograph at the aortic knuckle that mimics lymphadenopathy or aortic pseudoaneurysm; CT confirms its tubular vascular nature and connection to the upper intercostal spaces and brachiocephalic vein.