congenital anomaly of superior vena cava absence of innominate vein https://www.malacards.org/card/absence_of_innominate_vein UMLS:C4707656 Orphanet:99112 MONDO:0020443 GARD:0019655 MEDGEN:1640707 absence of brachiocephalic vein Absence of innominate vein is a rare congenital anomaly of the great veins characterized by absence of the left brachiocephalic vein (or innominate vein), resulting in an anomalous venous vasculature. Patients are usually asymptomatic and the anomaly is typically discovered intraoperatively. An association with persistence of left superior vena cava, permanent levoatrial cardinal vein or anomaly of the inferior vena cava has been reported in some cases.