Brachiocephalic Veins: Large veins on either side of the root of the neck formed by the junction of the internal jugular and subclavian veins. They drain blood from the head, neck, and upper extremities, and unite to form the superior vena cava.Brachiocephalic Trunk: The first and largest artery branching from the aortic arch. It distributes blood to the right side of the head and neck and to the right arm.Superior Vena Cava Syndrome: A condition that occurs when the obstruction of the thin-walled SUPERIOR VENA CAVA interrupts blood flow from the head, upper extremities, and thorax to the RIGHT ATRIUM. Obstruction can be caused by NEOPLASMS; THROMBOSIS; ANEURYSM; or external compression. The syndrome is characterized by swelling and/or CYANOSIS of the face, neck, and upper arms.Vena Cava, Superior: The venous trunk which returns blood from the head, neck, upper extremities and chest.Azygos Vein: A vein which arises from the right ascending lumbar vein or the vena cava, enters the thorax through the aortic orifice in the diaphragm, and terminates in the superior vena cava.Jugular Veins: Veins in the neck which drain the brain, face, and neck into the brachiocephalic or subclavian veins.Phlebography: Radiographic visualization or recording of a vein after the injection of contrast medium.Catheterization, Central Venous: Placement of an intravenous CATHETER in the subclavian, jugular, or other central vein.Constriction, Pathologic: The condition of an anatomical structure's being constricted beyond normal dimensions.Veins: The vessels carrying blood away from the capillary beds.Tomography, X-Ray Computed: Tomography using x-ray transmission and a computer algorithm to reconstruct the image.Arteriovenous Shunt, Surgical: Surgical shunt allowing direct passage of blood from an artery to a vein. (From Dorland, 28th ed)Subclavian Artery: Artery arising from the brachiocephalic trunk on the right side and from the arch of the aorta on the left side. It distributes to the neck, thoracic wall, spinal cord, brain, meninges, and upper limb.Subclavian Vein: The continuation of the axillary vein which follows the subclavian artery and then joins the internal jugular vein to form the brachiocephalic vein.