Unusual aortic arch variation: distal origin of common carotid arteries.

As part of a larger study, the aortic arch and its branches were removed en bloc at autopsy from men of Japanese ancestry born in Hawaii. Of the 193 arterial trees examined, 182 (94.3%) had a typical branching pattern (e.g., brachiocephalic trunk, left common carotid, and left subclavian arteries, in that order). Two specimens had only two branches arising from the aortic arch, a common trunk uniting the brachiocephalic and left common carotid arteries and a left subclavian artery. Nine individuals (4.6%) had four branches off the aortic arch; in eight of these cases (4.1%), the left vertebral artery originated directly off the aortic arch just proximal to, or as a common trunk with, the left subclavian artery. A unique aortic arch branching pattern was found in one of these men. The four arteries arising from the arch of the aorta were, in sequence: right subclavian, left subclavian, right common carotid, and left common carotid. The literature on aortic arch variations is reviewed and the possible embryonic development of these branching patterns and their clinical significance is discussed briefly.