Transposition of the Great Arteries (TGA)
What is Transposition of the Great Arteries?
Transposition of the Great Arteries (TGA) is a birth defect in which the two main arteries carrying blood out of the heart (the main pulmonary artery and the aorta) are switched in position, or ‘transposed.’
In babies with TGA, oxygen-poor blood from the body enters the right side of the heart, but instead of going to the lungs, the blood is pumped directly back out to the rest of the body through the aorta.
Oxygen-rich blood from the lungs entering the heart is pumped straight back to the lungs through the main pulmonary artery.
Types of TGA
Levo-transposition (l-TGA) type
With this type of TGA, the aorta is to the left of the pulmonary artery. In addition to the two major arteries, the lower section of the heart is also reversed. Blood without oxygen goes to the lungs and blood with oxygen goes to the body, but the wrong pumping chamber gets them there.
This type of TGA is less common, occurring in only 1% of babies with congenital heart conditions, but also less harmful because blood goes where it should.
Dextro-transposition (d-TGA) type
With this type of TGA, the aorta is to the right of the pulmonary artery.
When the pulmonary artery and aorta connect to the wrong parts of the heart, it affects how blood travels and can make it difficult for enough oxygen to reach the organs, because the blood skips going to the lungs for oxygen.
What are the symptoms of TGA?
Newborns with d-TGA have symptoms of cyanosis (low oxygen) and may also have heart failure. Transposition of the great arteries symptoms include:
- Trouble breathing
- Weak pulse
- Difficulty feeding
- Pounding heart
- Skin or whites of their eyes appear bluish (in babies with light skin) or grayish (in babies with dark skin)
For babies with d-TGA, symptoms appear soon after birth. The severity of these symptoms will depend on whether oxygen-rich blood is able to reach the rest of the body.
If a baby also has a large enough atrial septal defect, they may have less severe symptoms, as the ASD allows for some oxygenated blood to get pumped into the body.
What treatment options are there?
Babies born with d-TGA will need surgery to survive, with many babies affected by this condition having surgery within the first week of life.
Surgeons perform an arterial switch procedure, which involves switching the positions of your baby’s aorta and pulmonary artery, restoring a typical pathway for blood to flow through their heart and out to their body.
There are also treatments that can be used to delay major surgery for a short time. These include:
Prostaglandin: This medication can keep the ductus arteriosus open. This is a blood vessel your baby uses before birth, but it closes after birth because they usually don’t need it anymore. Keeping it open allows oxygen-rich blood to flow through your child’s body.
Septostomy procedure: A balloon atrial septostomy uses a catheter to widen the natural opening between the atria (right and left upper chambers in the heart). This minimally invasive procedure allows blood to mix so it can collect oxygen and deliver it to your child’s body.
