Bilateral variant origin of subclavian artery branches

Abstract

Subclavian artery branching patterns have been studied in cadaveric series and frequencies of the many variations have been documented. However, such variations have been seldom noticed antemortem. Here, we present the case of a very rare type of bilaterally different branching pattern of the subclavian artery.

Figure 1.

Three-dimensional reconstructed 64-slice CT angiogram (i) and coronal maximum intensity pixel reconstruction (ii) of the aortic arch and its branches. (a) Right carotid artery; (b) right vertebral artery; (c) right inferior thyroid artery; (d) right transverse cervical artery; (e) right suprascapular artery; (f) right internal thoracic artery; (g) common stump branching into (e) and (f); (h) thyrocervical trunk; (i) left carotid artery; (j) left vertebral artery; (k) left inferior thyroid artery; (l) left transverse cervical artery; (m) left suprascapular artery; (n) left internal thoracic artery; (o) common trunk branching into (l), (m) and (n).

Figure 2.

Aortic arches and the development of SCAs. (a) First aortic arch; (b) second aortic arch; (c) third aortic arch (d) fourth aortic arch, which gives rise to the proximal part of the right SCA; (e) part of the dorsal aorta, which gives rise to the middle portion of the right SCA; (f) seventh intersegmental artery, which gives rise to the distal portion of the right SCA; (g) sixth aortic arch; (h) seventh intersegmental artery, which gives rise to the left SCA; (i) arch of the aorta. SCA, subclavian artery.

Figure 3.

Various branching patterns of the first part of the left (a–h) and right (i–k) SCA. (a) Normal branching pattern of the left SCA—first branch is the VA, second the ITA and third the TCT, which gives rise to the SUS, TCA and THY,; (b) SUS, TCA and THY arising from the ITA; (c) SUS arising from the ITA, and TCA and THY arising from the TCT; (d) TCA arising from the ITA and SUS, and THY arising from the TCT; (e) THY arising from the ITA, and SUS and TCA arising from the TCT; (f) SUS and TCA arising from the ITA, and THY arising directly from the SCA; (g) SUS and THY arising from the ITA, and TCA arising directly from the SCA. (h) Our patient: TCA and SUS arising from the ITA, and THY arising directly from the SCA as its first branch. (i) Normal branching pattern of the right SCA with the pattern analogous to that of normal left SCA; (j) TCT arising from the ITA. (k) Our patient: SUS arising from the ITA, and TCA and THY arising from the TCT. ITA, internal thoracic artery; SCA,subclavian artery; SUS, suprascapular artery; TCA, transverse cervical artery; TCT, thyrocervical trunk; THY, inferior thyroid artery; VA, vertebral artery.