Variations in the anatomical organization of the human aortic arch. A study in a Portuguese population.

We have studied the anatomical features of human aortic arches in a sample of the Portuguese population using postmortem measurements of the arches and their branches in 33 cadavers. We found that there is a significant minority of individuals (18% of the total) who did not present the usual 3-branched aortic arch; interestingly, all 2-branched arches were seen in women and all 4-branched arches were observed in men. The arterial branches could spring either from the ascending segment of the arch (61% of total) or from its horizontal segment (39% of total). Our measurements showed that the springing of the branches was associated with the narrowing of the aortic arch, so that the difference in the diameter of the aortic arch between the origin of the first and last branches could reach up to 11 millimeters. We found that the relative caliber of the arterial branches of the aortic arch depended on the position of its origin at the arch: in aortic arches with branches that were originated at the horizontal segment of the arch the first arterial branch was always the widest of the three, whereas in aortic arches with branches coming out at the ascending segment of the arch the widest arterial branch was the third one. Our data support the view that there is a wide spectrum of variations in the anatomical arrangement of the aortic arch in humans, and offer information on the prevalence of aortic arch variations in a Portuguese population.