Transposition of the Great Arteries

Transposition of the great arteries (or vessels) is a rare issue where the main arteries that move blood out of your heart are in the wrong places. They also connect to your heart in the wrong places. It’s a congenital (present at birth) condition.

The two reversed (transposed) arteries are:

• The main pulmonary artery, which carries blood into your lungs.
• The aorta, the artery that carries blood from your heart to the rest of your body.

Your arteries are part of your circulatory system, which helps blood flow through your body. Unlike most arteries, which bring oxygen-rich blood to your body, your pulmonary arteries carry oxygen-poor blood.

Levo-transposition (l-TGA) type

With this type, a baby’s aorta is to the left of their pulmonary artery. In addition to the two major arteries, the lower section of your baby’s heart is also reversed. Blood without oxygen goes to your baby’s lungs and blood with oxygen goes to their body. But the wrong pumping chamber gets them there. This type is less common but also less harmful because blood goes where it should. Less than 1% of babies who have congenital heart conditions have the l-transposition type of TGA.

Dextro-transposition (d-TGA) type

With this type, a baby’s aorta is to the right of their pulmonary artery. About 5% to 7% of babies with congenital heart conditions have this type of TGA. This type is the main focus of this article.

When your baby’s pulmonary artery and aorta connect to the wrong parts of their heart, it affects how blood travels. It can make it difficult for enough oxygen to reach your baby’s organs. This is because your baby’s blood skips going to their lungs for oxygen. Blood that has oxygen doesn’t travel throughout their body to deliver oxygen. This happens in babies with the d-transposition type.

Holes between your baby’s upper (atrial septal defect or ASD) or lower (ventricular septal defect or VSD) heart chambers may be present at birth, as well. Although they’re abnormal, these congenital conditions may help blood without oxygen to mix with blood that contains oxygen.

That amount of oxygen isn’t enough, though. Your baby will need procedures to ensure that enough oxygen reaches their whole body. While nobody likes to think about a baby having surgery, it’s the best solution for the long term. Surgeons have been doing these operations for decades — with high survival rates.