From Wikipedia, the free encyclopedia. The superior vena cava (also known as the cava or cva) is a large diameter (24 mm), yet short, vein that carries deoxygenated blood from the upper half of the body to the heart 's right atrium.It is located in the anterior right superior mediastinum.rom Wikipedia, the free encyclopedia. The superior vena cava (also known as the cava or cva) is a large diameter (24 mm), yet short, vein that carries deoxygenated blood from the upper half of the body to the heart 's right atrium. It is located in the anterior right superior mediastinum.