Anatomical variation in the position of the brachiocephalic trunk (innominate artery) with respect to the trachea: a computed tomography-based study and literature review of Innominate Artery Compression Syndrome.

Respiratory compromise due to tracheal compression by the brachiocephalic trunk (BT), a condition first labeled as Innominate Artery Compression Syndrome (IACS), has been controversially attributed to an anomalous origin of this vessel to the left of, and hence crossing, the trachea. The aim of this study was to establish the normal relationship between the BT and trachea in infants, children, and young adults without obstructive respiratory symptoms. One hundred and eighty-one computed tomography (CT) examinations of the thorax, in three age groups, were reviewed. In axial cross section, the origin of the BT from the aortic arch was identified. The BT origin, with respect to the trachea, was recorded as for a clock face, approximated to the nearest half hour. There were 62 CTs in Group 1 (1 day to 3 years of age), 48 CTs in Group 2 (10-15 years), and 71 examinations in Group 3 (20-40 years). In 96.8% of Group 1, 91.7% of Group 2, and 74.6% of Group 3 the BT origin was to the left of the trachea, between the half past twelve and 3 o'clock positions. The BT origin occurred more the left in Group 1 when compared with the other two groups (P < 0.001). An origin of the BT to the left of the trachea is a normal finding in children and young adults without obstructive respiratory symptoms. There is a tendency for the origin to become progressively more rightward with age.