Transposition of the great arteries

At Children’s Hospital Boston, we understand that the first step in treating your child is forming an accurate, complete and timely diagnosis.

The exam

If your newborn baby was born with a bluish tint to his skin, or if your young child is experiencing certain symptoms, your pediatrician will immediately refer you to a pediatric cardiologist (and/or neonatologist), who will perform a physical exam. Your child’s doctor will listen to your baby’s heart and lungs, measure the oxygen level in his blood (non-invasively) and make other observations that help to determine the diagnosis.

Your child’s cardiologist will also investigate whether he has a heart murmur—a noise heard through the stethoscope that’s caused by the turbulence of blood flow. If there’s a murmur (there isn’t always with TGA), the location in the chest where the murmur is best heard, as well as the sound and character of the murmur itself, will give the cardiologist an initial idea of the kind of heart problem your baby may have.

Note: If your child’s TGA was detected prenatally through ultrasound, upon birth he’ll be immediately admitted for stabilization and surgery.

The tests

For most patients, a echocardiogram and chest x-ray are all that’s needed to form a diagnosis. But in some circumstances, some or all of the following tests may be used to confirm a diagnosis of TGA and its related defects, and to provide detailed information on the exact shape of a patient’s heart:

• echocardiogram (cardiac ultrasound): An echocardiogram evaluates the structure and function of your child’s heart using electronically recorded sound waves that produce a moving picture of the heart and heart valves. No discomfort is involved. It takes 30-60 minutes.
  
  If, during your pregnancy, a routine prenatal ultrasound or other signs raise your obstetrician’s suspicion of a congenital heart defect in the fetus, a cardiac ultrasound (described in the paragraph above) of the baby in utero will usually be the next step. The cardiac ultrasound—focusing exclusively on the baby’s heart—can usually detect a congenital heart defect.
   
• chest x-ray: A conventional chest x-ray will evaluate the size and spatial relationships of the heart within the child’s chest. It takes a few moments. There's no pain or discomfort.
   
• electrocardiogram (EKG): An EKG is used to evaluate the electrical activity of your child’s heart. An EKG is usually the initial test for evaluating the causes of symptoms and detecting heart abnormalities, including TGA. It’s performed by placing electrodes on the arms, legs and chest to record the electrical activity. The test takes five minutes or less and involves no pain or discomfort.
   
• cardiac catheterization: provides detailed visual information and measurements about the structures and pressures inside the heart. Blood pressure and oxygen measurements are taken in the four chambers of the heart, as well as the pulmonary artery and aorta.
   
• cardiac magnetic resonance imaging (MRI): provides a picture of the heart and blood vessels, but without using x-rays. MRI is rarely used in babies with TGA, but may be helpful in follow-up to TGA surgery to detect complications.