A rare vascular anomaly in the form of double left brachiocephalic vein detected incidentally during cardiac implantable electronic device (CIED) placement.

The growing number of transvenous cardiac implantable electronic device (CIED) implantation procedures helps detect rare vascular anomalies. Genetic disturbances in vascular development can produce systemic vein anomalies, including the left brachiocephalic vein (BCV). BCV anomalies commonly coexist with a persistent left superior vena cava (PLSVC), detected in 0.3-0.5% of the general population. The three known anatomical variations of PLSVC are two variations involving a BCV bridge and the third with BCV agenesis. BCV anomalies occur in 1% of patients with congenital heart defects, whereas the estimated proportion of BCV anomalies in the population with no cardiovascular symptoms is below 0.4%. A rarely observed, and thus rarely reported, BCV variation is a double left BCV, with the additional vessel typically found inferior and posterior to the ascending aorta prior to draining into the superior vena cava. This case report presents a previously unreported variation of double left BCV, with both vessels coursing parallel to each other, superior to the aortic arch. (Folia Morphol 2018; 77, 1: 161-165).