Inferior vena cava. The inferior vena cava is also referred to as the posterior vena cava. The inferior vena cava is a large vein that carries de-oxygenated blood from the lower body to the heart. De-oxygenated blood means most of the oxygen has been removed by tissues, and therefore the blood is darker.he inferior vena cava empties into the right atrium of the heart. The right atrium is located on the lower right back side of the heart. The inferior vena cava runs posterior, or behind, the abdominal cavity.