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What is L-transposition of the great arteries?

L-transposition of the great arteries (L-TGA) is a heart condition present at birth. In this condition, the heart’s connections are reversed, including the lower chambers and how they connect to the upper chambers and arteries. In L-TGA, the heart’s structure allows blood to flow in a more normal pattern, so symptoms may be milder at first.

Because of this switch, blood flows through the heart in a different way than usual. However, the main arteries are also switched. This creates a “double reversal” that still sends oxygen-rich blood to the body and oxygen-poor blood to the lungs. Because of this, L-TGA is often less serious than a d-transposition of the great arteries (d-TGA).

The heart has four chambers. The upper two chambers are the atria, and the lower two are the ventricles (Figure A). The chambers are separated by a wall of tissue called the septum. Blood is pumped through the chambers, aided by four heart valves. The valves open and close to let the blood flow in only one direction.

What causes L-TGA?

The cause is unknown, but genetic factors may contribute to L-TGA.

How does L-TGA affect the heart?

With L-TGA, the right ventricle has to pump at a higher pressure than usual. Over time, this extra work can weaken the right ventricle and affect how well it works.

What are the symptoms of L-TGA?

Babies born with L-TGA usually don’t look bluish, unlike babies born with d-TGA. Because of this, the condition may not be noticed right away. Some people are not diagnosed until adulthood, when symptoms such as heart failure, heart murmurs and abnormal heart rhythms may appear.

If a baby also has a ventricular septal defect (VSD) and pulmonary valve obstruction, they may look bluish and have heart murmurs.

How is L-TGA treated?

Most children with L-TGA do not need surgery in childhood if they do not have a VSD or pulmonary valve obstruction. Children with these problems may need surgery to:

• Close the opening
• Relieve the blockage of blood flow to the lungs
• In some cases, repair or replace the leaky tricuspid valve

Some children may need a more complex surgery called a “double switch,” Depending on their heart anatomy. This reroutes the oxygen-rich blood to the left ventricle and aorta and oxygen-poor blood to the right ventricle and pulmonary artery.

L-TGA in children: What families need to know

As children with L-TGA grow into adulthood, some may develop heart-related problems, even if they had surgery. These can include a weaker heart muscle, a leaky tricuspid valve or changes in heart rhythm.

Because the right side of the heart does more work than usual, it can weaken. This may lead to heart failure for some people. Slow heart rhythms can cause fainting or fatigue. A more serious rhythm problem, called complete heart block, can happen in people with L-TGA and can develop as they grow.

Ongoing Care

What will my child need in the future?

Some children with L-TGA may take medications to help the heart pump better, reduce fluid buildup or control blood pressure. These medications can help manage symptoms of heart failure.

If your child develops very slow heart rhythms, they may need a pacemaker.

As your child becomes an adult, it’s important that they see a cardiologist who specializes in congenital heart disease. This is especially important before any non-heart surgery or invasive procedure.

Medical follow-up

Your child will need regular checkups with a cardiologist to keep track of how their heart is working. During these visits, tests may include an electrocardiogram (EKG), echocardiogram, Holter monitor or an exercise stress test. Sometimes, other tests are needed, such as an MRI or heart catheterization.

Activity restrictions

Many children with L-TGA can stay active and do not need major limits to daily activities. In general, some people may be advised to avoid heavy weightlifting, which can raise blood pressure. If your child’s heart isn’t pumping as well as it should or if they have heart rhythm problems, they may need to adjust activities. Your child’s cardiologist will help guide you on whether any limits are needed.

Preventing endocarditis

Some people with L-TGA may need antibiotics before certain dental procedures, especially if they have a prosthetic heart valve. Most people with L-TGA do not have a prosthetic valve. A cardiologist can help decide if antibiotics are needed before certain dental work. Good oral care is important for everyone and can help lower the risk of infection.

L-TGA in adults: What to expect

Most children who do not have a VSD or pulmonary valve obstruction do not need surgery. Even if the surgery was done earlier in life, many people still have a right ventricle that pumps blood to the aorta.

Which repairs might be done in adulthood?

Some people may need their first heart surgery or another surgery later in life. For example, the tricuspid valve can become leaky and may need to be repaired or replaced. In rare cases, a small number of people may benefit from a more complex surgery called a “double switch.” This reroutes oxygen-rich blood to the left ventricle and aorta, and oxygen-poor blood to the right ventricle and pulmonary artery.

Which L-TGA problems are common in adulthood?

Adults with L-TGA may develop heart-related problems whether or not they had surgery earlier in life. These problems can include a weaker heart muscle, leaky tricuspid valve or changes in heart rhythm.

Because the right side of the heart does more work than usual, it can weaken. This may lead to heart failure for some people. Slow heart rhythms can cause fainting or fatigue. A more serious rhythm problem, called complete heart block, can happen in people with L-TGA and can develop as they grow.

Ongoing Care

What will I need in the future?

It’s important to see a cardiologist who specializes in adult congenital heart disease on a regular basis, usually once a year and more often if symptoms occur.

Some people may need medications to help the heart pump better, reduce fluid buildup and control blood pressure. These medications may help manage symptoms of heart failure. If very slow heart rhythms develop, a pacemaker may be needed.

You should talk with a congenital heart disease specialist before having any non-heart surgery or invasive procedure.

Medical follow-up

You will need regular checkups with a cardiologist to keep track of how your heart is working. During these visits, tests may include an electrocardiogram, echocardiogram, Holter monitor or an exercise stress test. Sometimes, other tests are needed, such as an MRI or heart catheterization.

Activity restrictions

Many adults with L-TGA can stay active and do not need major limits to daily activities. In general, it is best to avoid activities such as weight lifting, which can raise blood pressure. If your heart isn’t pumping as well as it should or if you have heart rhythm problems, you may need to adjust activities. Your cardiologist will help guide you on whether any limits are needed.

Preventing endocarditis

Some people with L-TGA may need antibiotics before certain dental procedures, especially if they have a prosthetic heart valve. Most people with L-TGA do not have a prosthetic valve. A cardiologist can help decide if antibiotics are needed before certain dental work. Good oral care is important for everyone and can help lower the risk of infection.

Pregnancy

Many women with L-TGA can have a pregnancy, but risk may vary depending on their heart function and should be carefully evaluated. The risk to the mother is higher if there is heart failure or problems with heart rhythm. It’s important to talk with a cardiologist who specializes in caring for people with congenital heart disease. This helps you understand health risks and plan for the best care.