[Left innominate artery arising from the ascending aorta in the absence of right innominate artery].

It is important to detect anatomic variants of the supraaortic trunks prior to cardiovascular surgery in order to adjust the surgical technique. We report here, an anatomic variant that was not described previously, detected on a chest multidetector CT and confirmed during surgery. This variant consists of a left innominate artery, arising from the ascending aorta before the right subclavian and common carotid arteries that arise separately from the aortic arch. It is important to notice the absence of associated cardiovascular malformations. We formulate a possible explanation of the described variant through an embryologic study of the vasculogenesis.