Transposition of the Great Arteries (TGA)

Transposition of the great arteries (TGA) is a type of congenital heart defect. This means that your baby is born with it.  In this condition, the large blood vessels that carry blood from the heart to the lungs and body aren’t connected as they should be. 

• The aorta is connected to the right ventricle. It should be connected to the left ventricle.
• The pulmonary artery is connected to the left ventricle when it should be connected to the right ventricle.

In TGA, the following occurs:

• Oxygen-poor (blue) blood is sent to the body.
• Oxygen-rich (red) blood returns to the lungs.

This is the opposite of a normal heart.

Babies cannot live with this condition unless they get treatment.

TGA may occur on its own. Or your child may also have other heart problems in addition to TGA, such as obstruction of blood flow from the right ventricle to the aorta, and variations in the course of the coronary arteries. Other heart problems such as an atrial or ventricular septal defect may allow some oxygen-rich blood  to be sent to your baby’s body. In addition, some normally present aspects of your baby's heart may remain intact to allow oxygen- rich blood reach your child's body. Normally, these connections would close shortly after birth. \

Heart defects that can happen with TGA include:

• An opening in the ventricular septum, called a ventricular septal defect (VSD). This is a hole between the 2 lower chambers of the heart. This allows oxygen-poor and oxygen-rich blood to mix. 

Normally present aspects of your baby's heart that remain tact include: 

• The ductus arteriosus stays open. This is a blood vessel that carries blood away from the heart in a developing baby. It usually closes soon after birth. This causes oxygen-poor and oxygen-rich blood to mix.

• The foramen ovale or atrial septal defect (ASD) allow oxygen-poor and oxygen-rich blood to mix.

Most of the time, the cause of TGA isn’t known.Most babies with TGA have blue skin color (cyanosis) in the first hours or days of their lives. 

Other symptoms can occur include:

• Fast breathing
• Trouble breathing
• Fast heart rate
• Poor feeding

The symptoms of TGA may be similar to symptoms of other conditions. Make sure that your child sees his or her healthcare provider for a diagnosis.

A healthcare provider may spot TGA in a baby during an ultrasound in pregnancy. But a baby usually isn’t diagnosed until after birth. A healthcare provider may suspect TGA if your baby has bluish skin. Or your child's healthcare provider may suspect this issue when he or she hears an abnormal sound (heart murmur) when listening to your child's heart with a stethoscope.

After birth, if your child has signs of TGA, a pediatric cardiologist or neonatologist will check him or her. A pediatric cardiologist is a doctor with special training to treat heart problems in babies and children. A neonatologist is a doctor with special training to treat problems in newborns. These doctors will be part of your baby’s heart care team.

Your child’s doctor may do tests to confirm the diagnosis. The tests your child has depends on his or her age and condition, and the doctor’s preferences.

Pulse oximetry

For this test, a probe is placed on your child's finger or toe. It measures the level of oxygen in the blood, if it is below a certain level, this may be a sign of TGA.

Chest X-ray

A chest X-ray shows the size and shape of the heart and lungs.

Electrocardiogram (ECG)

This test records the electrical activity of the heart. It also shows abnormal rhythms (arrhythmias or dysrhythmias) and spots heart muscle stress.

Echocardiogram (echo)

An echo uses sound waves to make a moving picture of the heart and heart valves. This test may show TGA.

Cardiac catheterization (cardiac or heart cath)

A cardiac catheterization gives detailed information about the structures inside the heart. In this test, a small, thin, flexible tube (catheter) is put into a blood vessel in your child’s groin. Then the healthcare provider guides it to your child’s heart. Your child’s healthcare provider will inject your child with contrast dye to see his or her heart more clearly. This test measures your child’s blood pressure and oxygen in the 4 chambers of the heart and the pulmonary artery and aorta. Your child will get medicine to help relax and prevent pain (sedation).

Treatment will depend on your child’s symptoms, age, and general health. It will also depend on how severe the condition is.

All children with a TGA will need to have surgery to fix it. Your baby will likely be admitted to the intensive care unit (ICU).

Medical management

At first, your baby may get the following care:

• Supplemental oxygen or a machine that allows breathable air to move in an out of the lungs (ventilator). This helps with breathing.
• Medicine given into a vein (intravenous or IV). This will help your baby’s heart and lungs work better.
• A medicine called prostaglandin E1. This is used to keep the ductus arteriosus open. This allows blood to flow through the heart.

Cardiac catheterization

Your child may have a test called a balloon atrial septostomy. This is done during cardiac catheterization. This test makes it easier for oxygen-rich blood to reach the rest of the body by creating or enlarging an atrial septal defect which allows oxygen-rich blood and oxygen-poor blood to mix.  

Surgery

In the first few months of life, your baby will need surgery for TGA. This procedure is called an arterial switch. Your child’s surgeon will move the aorta and pulmonary artery to their normal places. The surgeon will also have to move the coronary arteries. The doctor will also fix any other heart problems.

Complications of untreated TGA include:

• Heart valve problems
• Heart muscle problems or problems with the arteries that supply blood to the heart muscle
• Abnormal heart rhythm 
• Heart failure
• Lung problems
• Death

Your child will stay in the hospital until surgery. Your child’s healthcare team will tell you how to care for your baby before you leave the hospital. He or she may also give you information about home healthcare for your baby, if you need it.

Most children who have surgery for this condition will grow and develop normally. Ask your child's healthcare provider about your child’s outlook. Your child will still need to see his or her heart doctor for checkups. Your child may need additional surgeries or cardiac cath in the future. 

Your child's doctor may give him or her antibiotics before surgeries or dental procedures. This is to prevent infections. Your child may also need to limit physical activity and avoid certain sports. Ask your child’s heart doctor what activities are safe for your child.

If your child has trouble breathing or any new symptoms, call his or her healthcare provider.In TGA, your child’s aorta is connected to the right ventricle, and the pulmonary artery is connected to the left ventricle. This is the reverse of a normal heart.

• A newborn with TGA will usually have bluish skin color in the first days of life.
• All children with a TGA will need to have surgery to fix it.
• Most children who have surgery for this condition will grow and develop normally. Your child will still need to see his or her heart doctor for checkups and may require more surgery in the future.

Tips to help you get the most from a visit to your child’s healthcare provider:

• Know the reason for the visit and what you want to happen.
• Before your visit, write down questions you want answered.
• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you for your child.
• Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.
• Ask if your child’s condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if your child does not take the medicine or have the test or procedure.
• If your child has a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your child’s provider after office hours. This is important if your child becomes ill and you have questions or need advice.