When Your Child Has Transposition of the Great Arteries (TGA)

Your child has been diagnosed with transposition of the great arteries (TGA). This is a heart problem that involves the 2 main blood vessels that carry blood away from the heart. These are called the “great arteries.” Other structural heart problems often occur with TGA. Your child’s healthcare provider will evaluate your child’s heart and tell you the exact defect(s) he or she has. While TGA is a serious heart problem, it can be repaired with surgery.

Front view cross section of heart showing atria on top and ventricles on bottom showing aorta, pulmonary artery, mitral valve, aortic valve, left atrium, left ventricle, right atrium, right ventricle, tricuspid valve, pulmonary valve, superior vena cava, and inferior vena cava. Arrows on right side of heart show oxygen-poor blood pumping to lungs. Arrows on left side of heart show oxygen-rich blood pumped to body.

Front view cross section of heart showing transposition of the great arteries. Aorta is over right ventricle, and pulmonary artery is over left ventricle. There is also patent ductus arteriosus and patent foramen ovale (PFO). Arrows show blood flowing both ways between left and right heart through PFO. Mixed blood flows out of heart through aorta and pulmonary artery.

In a normal heart, oxygen-poor blood is pumped to the lungs from the right ventricle. Oxygen-rich blood is pumped to the body from the left ventricle.

With TGA, the positions of the great arteries are switched. Oxygen-poor blood is pumped to the body and oxygen-rich blood is pumped to the lungs.

The normal heart

  • The heart is divided into 4 chambers. The 2 upper chambers are called atria. The 2 lower chambers are called ventricles. The heart contains 4 valves. The valves open and close to keep blood flowing forward through the heart.

  • In a normal heart, oxygen-poor blood returning from the body fills the right atrium. This blood flows through the tricuspid valve into the right ventricle. The right ventricle pumps this blood through the pulmonary valve into the pulmonary artery and to the lungs to receive oxygen. Oxygen-rich blood returning from the lungs then fills the left atrium. This blood flows through the mitral valve into the left ventricle. The left ventricle pumps this blood through the aortic valve to the aorta to deliver oxygen to the body.

  • The ductus arteriosus is a normal structure in a baby’s heart before birth. It’s a blood vessel that connects the pulmonary artery and the aorta. It allows blood to flow between the pulmonary artery and the aorta before birth. It normally closes shortly after birth. If it remains open, it’s called a patent ductus arteriosus (PDA).

  • The foramen ovale is also a normal structure in a baby’s heart before birth. It’s an opening in the wall (atrial septum) between the atria. It normally closes a few weeks after birth. If it remains open, it’s called a patent foramen ovale (PFO).

What is transposition of the great arteries?

  • With TGA, the positions of the aorta and pulmonary artery are switched (transposed). The aorta is connected to the right ventricle resulting in oxygen-poor blood being pumped to the body. The pulmonary artery is connected to the left ventricle resulting in oxygen-rich blood being pumped back to the lungs. When a child’s body does not receive enough oxygen-rich blood from the heart, this leads to organ failure.

  • After birth, a child with TGA depends on other structures to allow blood to mix in the heart so that some oxygen can reach the body:

    • A PFO allows oxygen-poor blood and oxygen-rich blood to mix between the atria. Mixed blood (blood with some oxygen) from the right atrium can flow into the right ventricle and be pumped into the transposed aorta. As a result, mixed blood can reach the body and deliver oxygen. Because the blood contains less oxygen than normal, it may cause your child’s skin, lips, and nails to appear blue. This condition is called cyanosis.

    • A PDA allows oxygen-poor blood to flow from the aorta to the pulmonary artery. As a result, some of this blood can reach the lungs to pick up more oxygen.

    • A child with TGA may also has ventricular septal defects. This may allow for mixing of oxygen-poor and oxygen-rich blood.

What causes transposition of the great arteries?

TGA is a congenital heart defect. This means it’s a problem with the heart’s structure that your child was born with. The exact cause is unknown, but most cases seem to occur by chance.

What are the symptoms of transposition of the great arteries?

Children with TGA generally have symptoms shortly after birth. These can include:

  • Severe cyanosis with bluish color around the lips

  • Trouble breathing and breathing fast

  • Trouble feeding

  • Heart murmur

How is transposition of the great arteries diagnosed?

  • TGA may be detected with fetal echocardiography (fetal ultrasound) before a child is born. This test uses sound waves to form a picture of the baby's heart. This test is usually done when the mother is at least 16 weeks pregnant. 

  • If TGA isn't detected before birth, signs of a heart problem may be found during a physical exam shortly after birth. 

  • If a heart problem is suspected, your child will be referred to a pediatric cardiologist (doctor who diagnoses and treats heart problems in children). To confirm the diagnosis, several tests may be done. These include:

    • Chest X-ray. X-rays are used to take a picture of the heart and lungs.

    • Electrocardiogram (ECG). The electrical activity of the heart is recorded.

    • Echocardiogram (echo). Sound waves are used to create a picture of the heart and look for structural defects and other problems.

    • Pulse oximeter or oxygen saturation test. The oxygen level in the blood is measured.

How is transposition of the great arteries treated?

  • TGA is repaired with heart surgery. If your child has other structural heart problems (such as VSD) in addition to TGA, surgery may be more complex. Your child’s cardiologist or surgeon will discuss the best treatment options with you.

  • Before surgery, newborns are frequently given medication to keep the ductus arteriosus open. This allows mixed blood to continue to flow from the aorta to the pulmonary artery to receive oxygen.

  • Your child may also need a cardiac catheterization procedure called a balloon septostomy performed to widen the PFO until a complete (surgical) repair can be done. During this procedure, a catheter (thin, flexible tube) with a balloon on the end is guided through a blood vessel into the heart. The balloon is inflated to widen the PFO. This allows a greater amount of blood to mix freely between the atria. More oxygenated blood can then reach the body.

Risks and possible complications of heart surgery

Risks and possible complications include:

  • Reaction to sedative or anesthesia

  • Arrhythmia (abnormal heart rhythm)

  • Narrowing of the reconnected vessels (pulmonary artery, aorta, and coronary arteries)

  • Heart muscle dysfunction

  • Problems in the lungs

  • Infection

  • Bleeding

  • Problems with the nervous system, such as seizure or stroke

  • Abnormal buildup of fluid around the heart or lungs

What are the long-term concerns?

  • After repair of TGA, most children can be active. The level and extent of physical activity will vary with each child. Check with the cardiologist about which activities are appropriate for your child.

  • Your child will need regular follow-up visits with the cardiologist for the rest of your child’s life.

  • Your child may need to take antibiotics before having any surgery or dental work for some time following TGA surgery. This is to prevent infection of the inside lining of the heart and valves. This infection is called infective endocarditis. Antibiotics should be taken as directed by the cardiologist.