 Thus, d-TGA is not to be confused with l-TGA, where there is both atrioventricular and ventriculoarterial discordance.In absence of a shunt, patients with d-TGA could not survive, because there would be no flow of oxygenated blood (coming from the pulmonary veins) to the rest of the body after the normal prenatal shunts physiologically close a few weeks after birth.This congenital heart defect caused babies to "turn blue" due to the lack of oxygen flowing through the blood.