Transposition of the Great Arteries


Transposition of the great arteries (TGA) is a rare but serious congenital (present at birth) heart defect, in which the two main arteries leaving the heart are reversed (transposed).

Normally, the aorta leaves the left ventricle carrying oxygen-rich (red) blood to the body, and the pulmonary artery leaves the right ventricle carrying oxygen-poor (blue) blood to the lungs to get oxygen. The reversal in TGA changes the way blood circulates through the body, causing a shortage of oxygen in the blood leaving the heart going to the rest of the body.

According to the National Heart, Lung, and Blood Institute (NHLBI), TGA affects roughly 5 out of every 10,000 babies. The defect is found more frequently in Caucasians.  Untreated, more than 50% of infants with transposition will die in the first month of life, 90 % in the first year.

Causes of TGA

Causes of TGA

Congenital heart defects, such as transposition of the great arteries, are the result of problems that occurred early in the heart’s development. 

Although there is no direct cause for the defect, it is thought that genetics and environmental factors during the mother’s pregnancy may play a role, including: 

  • Alcoholism 
  • Mother who is over 40 years old
  • Family history of TGA or other congenital heart defects
  • Poor nutrition during pregnancy
  • Rubella (German measles) or other viral illnesses during pregnancy
  • Poorly controlled diabetes during pregnancy

TGA also is associated with chromosome disorders, such as Down syndrome.

Symptoms of TGA

Symptoms of TGA

Symptoms of TGA occur at birth or very soon afterwards. How severe the symptoms are depends on whether or not there is a way for blood to mix and get oxygen-rich blood to the body. TGA causes low oxygen levels in the blood, which can cause your baby’s skin to have a bluish-purple color (cyanosis).  

Other symptoms include: 

  • Shortness of breath
  • Poor feeding
  • Weak pulse
  • Pounding heart

Often, babies with TGA also will have other heart defects, such as a hole between the lower chambers (ventricular septal defect) or the upper chambers (atrial septal defect), which will allow blood to mix so that some oxygen-rich blood can be pumped to the rest of the body.

Diagnosis and Treatment Options

Diagnosis and Treatment Options

TGA usually is diagnosed based on the above signs and symptoms, a physical exam, and the results from tests and procedures.

During a physical exam, your doctor will listen to your baby’s heart and lungs to check for a murmur and will evaluate your baby’s general appearance to look for signs of a heart defect, such as a bluish tint to the skin, lips, or fingernails and rapid breathing.

TGA is one of the critical congenital heart defects that can be detected on pulse oximetry. Pulse oximetrey is a simple, non-invasive, bedside test to determine the amount of oxygen in the baby’s blood.

If your doctor finds any signs of TGA, your baby likely will undergo additional testing. Additional tests that your doctor may order include a chest x-ray, echocardiogram (echo), electrocardiogram (EKG), or cardiac catheterization. For more information on these tests, visit our common diagnostic tests page.

The only treatment for TGA is open heart surgery, which is performed by a cardiothoracic surgeon

Be sure to speak with your baby’s doctor about what you should expect during and after the surgery. You can print these sample questions to use as a basis for discussion with the doctor.


Surgery often is performed in the first weeks of life, and the most common approach is the arterial switch procedure. During the procedure, the great arteries are cut off the heart just above the associated valve and then are switched to their usual position. The coronary arteries also are moved and reattached to the new aorta so that the heart is supplied with oxygenated blood. If any septal defects are present, they are closed during the same surgery.



Without surgery, TGA can be fatal and most people die by age one year.

After surgery, your baby will require continued follow-up care. The doctor will schedule routine checkups to make sure that the procedure was successful and monitor for any new problems. Most children with successful complete repair will not have any activity restrictions as they grow older.

Most children who undergo the arterial switch operation do not need any additional surgery, but sometimes patients who had an operation to repair TGA in infancy need additional surgery as they age.

Most often, this procedure is undertaken to repair or replace leaky heart valves, open up areas of narrowing, abnormal heart rhythm, and address problems with the arteries that supply the heart with blood (coronary arteries).

Illustration of heart with repaired TGA

Illustration by Steven P. Goldberg, MD


Preventive antibiotics are almost always recommended for people who have artificial valves or who've had repair with prosthetic material. Be sure to ask your doctor about what is right for your child.


Reviewed by: Lauren C. Kane, MD, and Ram Kumar Subramanyan, MD, PhD
July 2015