Transposition of the Great Arteries (TGA)
Transposition of the great arteries (TGA), also known as transposition of the great vessels (TGV), is a congenital heart defect where the aorta and the pulmonary artery are connected to the wrong ventricle, opposite of a normal heart.
With these arteries reversed, blood circulates in an abnormal direction through the heart. The oxygen-poor blood returns to the right atrium from the body, passes into the right ventricle, and then goes into the aorta and back to the body. Oxygen-rich blood returns to the left atrium from the lungs and passes into the left ventricle, which pumps it back to the lungs. Because the blood circulates abnormally, it is oxygen poor and cannot meet the body's needs.
TGA is typically diagnosed within the first hours of birth. Because of the severity of the condition, babies with transposition of the great arteries need special care immediately after birth. Surgery is nearly always performed within the first few days of their lives.
Occasionally, a baby with patent ductus arteriosus (PDA), atrial septal defect (ASD) or ventricular septal defect (VSD) has enough mixing of blood so they are not diagnosed until they become more cyanotic (“blue”).
Normal heart – in a healthy heart with proper blood flow, the blue droplets representing oxygen-poor blood travel to the lungs, and the red oxygen-rich droplets circulate through the body.
A heart with transposition of the great arteries (TGA).