In the case of a large ASD (>9mm), which may result in a clinically remarkable left-to-right shunt, blood will shunt from the left atrium to the right atrium.
Superior vena cava, a large diameter, yet short, vein that carries deoxygenated blood from the upper half of the body to the heart's right atrium.
Inferior vena cava, the large vein that carries de-oxygenated blood from the lower half of the body into the right atrium of the heart.