Fig. 2.

a–d Less common but in some ways more important variants to be aware of. The most important of these is the right aberrant subclavian artery (a), which is frequently associated with aberrant origin of the right VA from the right CCA (b). Both right and left VA can originate from the proximal descending thoracic aorta distal to the left subclavian artery (c). Some very rare variants such as d essentially require a pigtail arch aortogram and empiric approach to facilitate catheterization.