The aorta is the main blood vessel that carries oxygen-rich blood from the heart to the rest of the body. It is usually attached to the left ventricle. In cases of tetralogy of Fallot, the aorta is positioned between the right and left ventricles, directly on the defect of the ventricular septum. As a result, oxygen-poor blood from the right ventricle flows into the aorta and the rest of the body.