Health Library

What Is Levo-Transposition of the Great Arteries?

Levo-transposition of the great arteries (L-TGA) is when the positions of the heart’s ventricles are reversed. Some people with the condition never need treatment. Others develop symptoms and need treatment with medicines and surgery.

How Does the Heart Work?

The heart has four chambers, a left atrium and right atrium and a left ventricle and right ventricle. Usually:

• Blue blood (low oxygen) comes from the body into the right atrium.
• It then flows to the right ventricle, which pumps it through the pulmonary artery out to the lungs to pick up oxygen.
• Red blood (high oxygen) comes from the lungs into the left atrium.
• It then flows into the left ventricle, which pumps it through the aorta out to the body to deliver oxygen.

What Happens in Levo-Transposition of the Great Arteries?

Normally, the left ventricle is bigger and stronger than the right ventricle because it pumps blood through the whole body. In L-TGA, the ventricles are switched, so the weaker right ventricle must do the work of the left ventricle. This puts a lot of extra work on the right ventricle. Over time, this can lead to heart failure — when the pumping chamber gets larger, and the heart muscle becomes weak.

Babies born with L-TGA often have other heart problems too. Some babies are born with a hole between the ventricles (a ventricular septal defect or VSD), or have a problem with the heart’s electrical system or valves.

What Are the Signs & Symptoms of Levo-Transposition of the Great Arteries?

Babies with L-TGA and no other heart issues have no symptoms at birth. Symptoms usually show up later in childhood or in adulthood. These may include trouble breathing, fainting, or lightheadedness. Sometimes a person may have an unsteady or slow heartbeat. When there are other issues, such as a hole in the heart or an abnormal valve or blood vessel, the baby may have a heart murmur or other issues that bring them to medical attention early in life.

What Causes Levo-Transposition of the Great Arteries?

L-TGA happens when a baby is growing in the womb. No one knows exactly what causes it, and there’s no way to prevent it.

How Is Levo-Transposition of the Great Arteries Diagnosed?

Often, doctors diagnose L-TGA because of other heart problems the baby has. The condition might show on a fetal echocardiogram before a baby is born. More often, it’s found when someone develops symptoms. Cardiologists (doctors who find and treat heart problems) do tests to find out the cause. These can include:

• cardiac catheterization
• chest X-ray
• electrocardiogram (ECG)
• echocardiogram (ultrasound of the heart)
• cardiac MRI

How Is Levo-Transposition of the Great Arteries Treated?

A baby born with L-TGA may not need treatment right away. Some children never need treatment. 

When treatment is needed, it may include:

• medicines to help the heart pump better
• medicines to prevent fluid buildup in the heart, lungs, and body
• cardiac catheterization (a non-surgical procedure)
• a pacemaker
• heart surgery

How Can Parents Help?

Learn as much as you can about L-TGA and any treatments your child may need. This will help you work with the care team and help your child cope. Be sure to ask when you have questions.

Take your child to a cardiologist for regular follow-up visits. Your child should continue these visits as an adult. The cardiologist can watch for any new problems and treat them early.

You play a big role in your child’s treatment. Keep a record of:

• your child’s care visits, medicines, and any symptoms
• any special instructions for taking care of your child at home
• any questions you have for the care team

What Else Should I Know?

Children with L-TGA will need follow-up doctor visits and tests. The doctors, nurses, social workers, and other members of the care team are there to help you and your child. Talk to any of them about resources that can help your family.

Take time to take care of yourself too. Parents who get the support they need are better able to support their children. It can help to find a support group for parents of children with heart conditions. Ask the care team for recommendations.

You also can find more information and support online at:

• The American Heart Association