Transposition of the great arteries (TGA) is an abnormality of the heart vessels that is present at birth, causing congenital heart disease. This is a serious heart defect that usually requires open heart surgery for the baby to survive.

What is going on in the body?

In a normal heart, the main artery of the body, called the aorta, is attached to the left side of the heart. The main lung artery, called the pulmonary artery, is attached to the right side of the heart. In the birth defect known as transposition of the great arteries, these arteries are reversed. When this happens, the wrong blood goes to the wrong area.

Normally, blood with low oxygen levels is sent to the lungs through the main lung artery to get oxygen. Next, this blood is pumped out through the aorta to the rest of the body. In TGA, blood with low oxygen levels is pumped through the aorta to the rest of the body.

What are the causes and risks of the disease?

The cause of TGA is unknown. Males are more commonly affected than females. Children born to mothers with diabetes are also at higher risk.