Transposition of the great arteries is diagnosed when the the aorta is connected to the anatomic right ventricle and the pulmonary artery is connected to the anatomic left ventricle.
In TGA the pulmonary and systemic circulations function in parallel rather than in series. The neonate will only survive if there is mixing of the two circulations, ie persistence of the ductus arteriosus and/or the foramen ovale.
This is the most common cause of cyanosis in the newborn infant (1).
- Dickinson DF et al (1993). Congenital heart lesions.Medicine International, 21(12), 457-64.