Transposition of the great arteries (TGA) is a heart defect that occurs from birth (congenital). The two major arteries that carry blood away from the heart -- the aorta and the pulmonary artery -- are switched (transposed).
The cause of TGA is unknown. It is not associated with any one common genetic abnormality. It rarely occurs in other family members.
TGA is a cyanotic heart defect. This means there is decreased oxygen in the blood that is pumped from the heart to the rest of the body.
In normal hearts, blood that returns from the body goes through the right side of the heart and pulmonary artery to the lungs to get oxygen. The blood then comes back to the left side of the heart and travels out the aorta to the body.
In TGA, venous blood returns normally to the heart through the right atrium. But, instead of going to the lungs to absorb oxygen, this blood is pumped out through the aorta and back to the body. This blood has not been recharged with oxygen and leads to cyanosis.
Symptoms appear at birth or very soon afterward. How bad the symptoms are depends on the type and size of additional heart defects (such as atrial septal defect, ventricular septal defect, or patent ductus arteriosus) and how much the blood can mix between the two abnormal circulations.
Symptoms may include:
The health care provider may detect a heart murmur while listening to the chest with a stethoscope. The baby's mouth and skin will be a blue color.
Tests often include the following:
The initial step in treatment is to allow oxygen-rich blood to mix with poorly oxygenated blood. The baby will immediately receive a medicine called prostaglandin through an IV (intravenous line). This medicine helps keep a blood vessel called the ductus arteriosus open, allowing some mixing of the two blood circulations. In some cases, an opening between the right and left atrium can be created with procedure using a balloon catheter. This allows blood to mix. This procedure is known as balloon atrial septostomy.
Permanent treatment involves heart surgery during which the great arteries are cut and stitched back to their correct position. This is called an arterial switch operation (ASO). Prior to the development of this surgery, a surgery called an atrial switch (or Mustard procedure or Senning procedure) was used.
The child's symptoms will improve after surgery to correct the defect. Most infants who undergo arterial switch do not have symptoms after surgery and live normal lives. If corrective surgery is not performed, the life expectancy is only months.
Complications may include:
This condition can be diagnosed before birth using a fetal echocardiogram. If not, it is most often diagnosed soon after a baby is born.
Go to the emergency room or call the local emergency number (such as 911) if your baby's skin develops a bluish color, especially in the face or trunk.
Call your provider if your baby has this condition and new symptoms develop, get worse, or continue after treatment.
Women who plan to become pregnant should be immunized against rubella if they are not already immune. Eating well, avoiding alcohol, and controlling diabetes both before and during pregnancy may be helpful.
Reviewed By: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.