Transposition of the Great Arteries (TGA)

A rare congenital heart defect, transposition of the great arteries is diagnosed when the two major arteries attached to the heart are transposed or reversed. Also called transposition of the great vessels, the heart can’t send enough oxygenated blood to the body because oxygen-poor and oxygen-rich blood are separated when the pulmonary artery and aorta are transposed. Without treatment, your baby won’t have adequate oxygen in her bloodstream and may suffer serious complications, such as heart failure. Transposition of the great arteries is a serious heart condition but corrective surgery can restore heart function and help your baby live a normal life.

Wellness & Prevention

Transposition of the great arteries develops in the middle of the first eight weeks of pregnancy as the heart begins to take shape. Normally, oxygen-depleted blood flows into the right side of the heart and the right ventricle pumps blood into the pulmonary artery to be oxygenated in the lungs. Oxygen-rich blood returns to the left side of the heart and the left ventricle pumps blood to the body through the aorta.

With TGA, the aorta attaches to the right ventricle, sending oxygen-poor blood back to the body. The pulmonary artery attaches to the left ventricle, sending oxygen-rich blood back to the lungs. The two separate circuits prevent your baby’s body from getting enough oxygen.

A child who has TGA may have other heart defects that can temporarily help his body receive more oxygen. A hole in the wall between the ventricles or atria — called an atrial septal defect or ventricular septal defect — lets blood from both sides of the heart mix and raises the oxygen level.

The ductus arteriosus, the blood vessel between the pulmonary artery and the aorta, is present in a normal heart but closes soon after birth. If the vessel remains open, patent ductus arteriosus occurs and oxygen-poor and oxygen-rich blood mixes, sending blood with a higher level of oxygenation to the body.

Located in the wall between the atria, the foramen ovale is another natural opening that closes after birth and allows blood to mix.

TGA mostly develops by chance but there may be a genetic link and the mother being older than 40, drinking alcohol, having diabetes, poor nutrition, rubella or a viral illness during pregnancy may increase the baby’s risk.

Babies who are born with TGA typically have symptoms soon after birth and may look blue within the first day because of the lack of oxygen in the bloodstream. Symptoms may include:

  • A blue color to the skin, lips and nails
  • Heart murmur
  • Rapid or labored breathing
  • Rapid heart rate
  • Trouble feeding or lack of appetite
  • Cool, clammy skin

Diagnosis

Transposition of the great arteries may be detected with fetal echocardiography before birth. The ultrasound can be done when the fetus is at least 16 weeks old. After birth, your child’s doctor may notice signs of TGA, including a heart murmur or blue-tinged skin.

To confirm a diagnosis, a pediatric cardiologist may perform different tests including:

  • Chest X-ray: An X-ray shows your pediatric cardiologist the size, shape and structure of your baby’s heart and lungs.
  • Electrocardiogram (ECG or EKG): An electrocardiogram records the electrical activity that happens in the heart with each contraction. An ECG detects stress on the heart muscle and abnormal rhythms, such as arrhythmia.
  • Echocardiogram: An echocardiogram uses sound waves to create a picture of the heart. An echocardiogram can detect a patent ductus arteriosus, ventricular septal defect or atrial septal defect. The test also shows the position of the pulmonary artery and aorta.
  • Cardiac catheterization: Using a larger blood vessel, a small tube is threaded into the heart to take blood pressure and oxygen level measurements.

TGA may also be diagnosed with pulse oximeter to gauge how much oxygen is in the bloodstream.

Treatments

Until corrective surgery can be done, your pediatric cardiologist may treat your baby with IV medication to keep the ductus arteriosus open and perform balloon or atrial septostomy using cardiac catheterization to widen the foramen ovale to improve the oxygen level in the blood.

Surgery to repair transposition of the great arteries and correct other heart defects may be done in the first week or two of your baby’s life. A pediatric cardiac surgeon performs a procedure called an “arterial switch” to move the aorta to the left ventricle, the pulmonary artery to the right ventricle and connect the coronary arteries to the aorta to ensure the heart muscle receives oxygen-rich blood.

Aftercare

After treatment, most babies who have TGA develop and grow normally and should be able to have an active lifestyle. Your pediatric cardiologist may recommend limiting or avoiding specific activities that may stress your child’s heart. Your child may need lifelong care from a cardiologist to check for complications, such as leaky heart valves.