Transposition of the Great Arteries (TGA) Symptoms & Causes

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It’s natural for you to be concerned right now about your child’s health—a diagnosis of transposition of the great arteries can be overwhelming. But you can rest assured that at Boston Children's Hospital, your child is in expert hands.

Our cardiologists, cardiac surgeons, cardiovascular imaging professionals and other clinicians have extensive experience with all types of heart problems. Each year, we treat thousands of children, adolescents and even adults with a wide variety of heart defects and disorders.

Comparison with normal heart

In a normal heart, oxygen-poor (blue) blood returns to the right atrium from the body, and is pumped by the right ventricle through the pulmonary artery into the lungs. In the lungs the blood receives oxygen (and gives up carbon dioxide), then returns to the left side of the heart. The left ventricle pumps the oxygen-rich blood through the aorta out to the body.

But in TGA, oxygen-poor (blue) blood keeps circulating through the body, while oxygen-rich (red) blood keeps returning to the lungs—the exact opposite of the way blood is supposed to circulate.

If there’s a large enough opening between the two atria, some of the red and blood will mix, providing enough oxygen for the baby for a period of days or weeks. A few babies will naturally have this opening, but for most patients, doctors must create this opening within the first few hours after birth. Open heart surgery, to re-connect the pulmonary artery and aorta to the appropriate ventricles, is needed for the longer run, and is usually done a few days later.

Are there additional defects associated with TGA?

Most babies with TGA have only that cardiac defect, but other heart defects that can occur with TGA:

  • atrial septal defect (ASD): an opening between the right and left atria. This defect occurs occasionally with TGA and is actually helpful; it can be easily corrected at the time of surgical correction.
  • ventricular septal defect (VSD): an opening in the wall of tissue (ventricular septum) separating the right and left ventricles. This occurs in about 20% of patients with TGA. If large enough, a VSD will need to be surgically closed at the time of surgical correction of the TGA.
  • patent ductus arteriosus (PDA): The ductus arteriosus is a blood vessel that’s normally open (patent) while the baby is inside the mother, but that closes naturally shortly after birth.Because keeping this vessel open helps increase the blood oxygen level in babies with TGA, doctors often give patients a medicine (prostaglandin E1) to keep the ductus open.
  • Miscellaneous other defects, such as narrowing of the aorta, infrequently occur.

What are the signs and symptoms of TGA?

Cyanosis (blue coloration of the skin) is the most common symptom of TGA.

How do you diagnose TGA?

For most patients, an echocardiogram and chest x-ray are all that’s needed to form a diagnosis. But in some circumstances, some or all of the following tests may be used to confirm a diagnosis of TGA and its related defects, and to provide detailed information on the exact shape of a patient’s heart:

  • chest x-ray: shows the size and spatial relationships of the heart within the child’s chest. It takes a few moments. There’s no pain or discomfort.
  • electrocardiogram (ECG or EKG): evaluates the electrical activity of your child’s heart. An EKG is usually the initial test for evaluating the causes of symptoms and detecting heart abnormalities, including TGA. It’s performed by placing electrodes on the arms, legs and chest to record the electrical activity. The test takes five minutes or less and involves no pain or discomfort.
  • echocardiogram(echo, cardiac ultrasound): evaluates the structure and function of your child’s heart using electronically recorded sound waves that produce a moving picture of the heart and heart valves. No discomfort is involved. It takes 30-60 minutes.
  • cardiac catheterization (cardiac cath): provides detailed visual information and measurements about the structures and pressures inside the heart. Blood pressure and oxygen measurements are taken in the four chambers of the heart, as well as the pulmonary artery and aorta.

    Note: Cardiac catheterization can be an interventional tool, as well as a diagnostic tool. Most babies with TGA will require a balloon atrial septostomy as an initial therapy, performed in either the heart cath lab or the CICU. In this procedure, a balloon at the end of a catheter (small, flexible tube) is used to enlarge the opening between the atria.
  • cardiac magnetic resonance imaging (MRI): provides a picture of the heart and blood vessels, but without using x-rays. MRI is rarely used in babies with TGA, but may be helpful in follow-up to TGA surgery to detect complications.

What causes TGA?

As a congenital heart defect, TGA is a problem with your child’s heart structure that he was born with.

The heart forms during the first eight weeks of fetal development. The problem occurs in the middle of these weeks, when the aorta and the pulmonary artery each attach to the incorrect heart chamber. It isn’t clear what causes congenital heart malformations, including TGA, although in most cases it appears that some combination of genetics and environment is involved.

Few risk factors have been identified, but it appears that the risk of TGA is increased in mothers with type 1 diabetes mellitus (formerly known as "insulin-dependent" or "juvenile") , and possibly with the ingestion of certain drugs, such as benzodiazepines.

How do you treat TGA?

Your baby most likely will be admitted to Boston Children’s cardiac intensive care unit (CICU) once his symptoms become apparent.

  • He may be placed on oxygen, and possibly a ventilator (breathing machine). Most babies will be given a medicine to keep the ductus arteriosus from closing (which helps increase the level of oxygen in the blood).
  • Most babies with TGA require a balloon atrial septostomy to improve mixing of oxygen-rich (red) blood and oxygen-poor (blue) blood between the right and left atria (upper chambers of the heart). The septostomy is a heart catheterization procedure, done in the heart catheterization laboratory or the CICU.
  • Within the first one to two weeks, TGA is surgically repaired through a procedure called an “arterial switch operation” (ASO).
    • A heart-lung machine does the work of the heart and lungs during the procedure.
    • The aorta and pulmonary arteries are disconnected, “switched” and reconnected to their proper ventricles.
    • The arteries that supply the heart (“coronary arteries”) must be re-connected to the newly positioned aorta so that “red” blood can supply the muscle of the heart.
    • The associated holes between the chambers of the heart are closed.
    • The heart is restarted as the heart-lung machine is withdrawn.

How should we care for our child after surgery?

After surgery, your child’s cardiologist will offer recommendations for follow-up care, including:

  • wound care while the baby is healing
  • a nutritional program to encourage weight gain
  • an oral hygiene program to prevent infection
  • an appropriate exercise regimen to build body mass and achieve fitness

As your baby recovers and grows, be sure to follow a regular program of well-baby/well-child checkups.

Will my child be OK in the long term?

Your cardiologist will help you create a long-term care program as your baby grows into childhood, the teen years and even adulthood. Most of our patients who’ve had congenital heart disease have an ongoing relationship with their Boston Children’s cardiologist. We’ll prevent and treat complications, and will advise on daily-life issues, such as exercise and activity levels, nutrition and precautions related to pregnancy.

Surgical techniques for treating congenital heart defects are continually being refined, and Boston Children’s surgical success rates are very high. Nevertheless, your child will need periodic monitoring, since he could be at some risk for:

  • abnormal heart rhythms (arrhythmias)
  • leaky heart valves
  • narrowing of one or both switched arteries at the site(s) of the switch
  • narrowing of the coronary arteries at the site of their switch


Frequently Asked Questions (FAQ) about Transposition of the Great Arteries 

What is transposition of the great arteries (TGA)?
Are there other defects associated with TGA?
If my child has TGA, will he be OK?
How does Children’s treat TGA?
How common is TGA?
What are the symptoms of TGA?
What should we do at home after TGA surgery?
What’s the long-term outlook for TGA-affected children?
What causes TGA?
What is Boston Children’s experience treating congenital heart defects? 
Where can my child find care and support when he grows up?


Q: What is transposition of the great arteries (TGA)?
A:
Transposition of the great arteries is a congenital heart defect in which the two “great” vessels that take blood away from the heart to the lungs (the pulmonary artery) or to the body (the aorta) are reversed. This means that the aorta is connected to the right ventricle, and the pulmonary artery is connected to the left ventricle—the opposite of a normal heart’s anatomy.

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Q: Are there other defects associated with TGA?
A:
Other heart defects occasionally occur with TGA.

  • ASD and/or VSD: Openings in the walls (septa) separating the left and right sides of the heart, called an atrial septal defect (ASD) or a ventricular septal defect (VSD), allow blood from one side to mix with blood from another.
  • Miscellaneous other defects, such as narrowing of the aorta, infrequently occur.
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Q: If my child has TGA, will he be OK?
A:
Most infants who have TGA surgery will grow and develop normally. But your child will need to be followed periodically by a pediatric cardiologist, who will check for any heart-related problems.

The outlook varies from child to child, but open heart surgery at Boston Children’s has among the highest success rates in the United States among large pediatric cardiac centers.

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Q: How does Children’s treat TGA?
A:

  • An infant with TGA may be placed on oxygen, and possibly a ventilator (breathing machine). Most babies will be given a medicine to keep the ductus arteriosus from closing (which helps increase the level of oxygen in the blood).
  • Most babies with TGA require a balloon atrial septostomy to improve mixing of oxygen-rich (red) blood and oxygen-poor (blue) blood between the right and left atria (upper chambers of the heart). The septostomy is a heart catheterization procedure, done in the heart catheterization laboratory or the CICU.
  • Within the first one to two weeks, TGA is surgically repaired through a procedure called an “arterial switch operation” (ASO).
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Q: How common is TGA?
A: While relatively rare (one in every 4,000 babies), TGA is among the most common cyanotic ("blue baby") heart defects, and it affects boys more than girls.

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Q: What are the symptoms of TGA?
A: Cyanosis (blue coloration of the skin) is the most common symptom of TGA.

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Q: What should we do at home after TGA surgery?
A:
After surgery, your child’s cardiologist will offer recommendations for follow-up care, including:

  • wound care while the baby is healing
  • a nutritional program to encourage weight gain
  • an oral hygiene program to prevent infection
  • an appropriate exercise regimen to build body mass and achieve fitness

As your baby recovers and grows, be sure to follow a regular program of well-baby/well-child checkups.

Back to top.


Q: What’s the long-term outlook for TGA-affected children?
A:
Your cardiologist will help you create a long-term care program as your baby grows into childhood, the teen years and even adulthood. Most of our patients who’ve had congenital heart disease have an ongoing relationship with their Boston Children’s cardiologist. We’ll prevent and treat complications, and will advise on daily-life issues, such as exercise and activity levels, nutrition and precautions related to pregnancy.

Surgical techniques for treating congenital heart defects are continually being refined, and Boston Children’s surgical success rates are very high. Nevertheless, your child will need periodic monitoring, since he could be at some risk for:

  • abnormal heart rhythms (arrhythmias)
  • leaky heart valves
  • narrowing of one or both switched arteries at the site(s) of the switch
  • narrowing of the coronary arteries at the site of their switch
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Q: What causes TGA?
A:
The heart forms during the first eight weeks of fetal development. The problem occurs in the middle of these weeks, when the aorta and the pulmonary artery each attach to the incorrect heart chamber. It isn’t clear what causes congenital heart malformations, including TGA, although in most cases it appears that some combination of genetics and environment is involved.

Few risk factors have been identified, but it appears that the risk of TGA is increased in mothers with type 1 diabetes mellitus, and possibly with the ingestion of certain drugs, such as benzodiazepines.

Back to top.


Q: What is Boston Children’s experience treating congenital heart defects?

A:
Boston Children’s surgeons treat some of the most complex pediatric heart conditions in the world, with overall success rates approaching 98 percent—among the highest in the nation among large pediatric cardiac centers.

Our experts have pioneered some of medical science’s most advanced heart treatments, now in use around the globe. Boston Children’s is among the only major pediatric heart centers in the world performing fetal heart interventions for certain congenital defects.

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Q: Where can my child find care and support when he grows up?
A: 

  • The Boston Adult Congenital Heart and Pulmonary Hypertension Service (BACH) provides long-term inpatient and outpatient care and advanced therapeutic options for patients with congenital heart disease and pulmonary hypertension as they reach and progress through adulthood.

    BACH is an international center for excellence, with physicians and services from Children’s, Brigham and Women’s Hospital and the Beth Israel Deaconess Medical Center. The center promotes and supports clinical and scientific research for the advancement of care of these patients, and is a leader in the education of providers caring for this unique population.
  • The Adult Congenital Heart Association (ACHA) is a national not-for-profit organization dedicated to improving and extending the life of adults with congenital heart defects, now thought to number at least 1 million. The organization serves and supports many such adults, their families and the medical community, as well as conducting research and providing advocacy, outreach and education.
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When to seek medical advice

Call your health care provider immediately if your baby is having difficulty breathing, is breathing rapidly, has a bluish color or seems to tire too easily.

Questions to ask your doctor

After your child is diagnosed with TGA, you may feel overwhelmed with information. It can be easy to lose track of the questions that occur to you. Lots of parents find it helpful to jot down questions as they arise—that way, when you talk to your child’s doctors, you can be sure that all your concerns are addressed.

Some questions might include:

  • What’s happening to my child, and why?
  • What tests will you perform to determine a treatment for my child?
  • What are the treatment options?
  • Are there alternative therapies?
  • Will my child be OK if he has congenital heart disease?
  • Will there be restrictions on my child’s activities?
  • Will there be long-term effects?
  • What can we do at home?

Who’s at risk

Congenital heart defects usually occur sporadically (by chance), with no clear reason for their development. So, it’s difficult to predict who’s at risk. Familial cases have been reported, but no genetic link has been confirmed. In general, if you have a child with a congenital cardiac defect, the chance of more children having a defect is about 2 to 3 percent.

Few risk factors have been identified, but it appears that the risk of TGA is increased in mothers with insulin-dependent diabetes mellitus, and possibly with ingestion of certain drugs, such as benzodiazepines.

For teens

If you’re a teen with a congenital heart defect, you have a lot to cope with. Besides the typical issues any teenager faces—from social acceptance to body changes and more—you’ll also have to deal with medical appointments and procedures, some delay of your natural wish for independence, feeling different and assuming a lot of personal responsibility for maintaining your own good health.

If you feel overwhelmed, depressed or anxious through this important time in your transition to adulthood, speak to your doctor or counselor to get help.

For adults

If you were treated for congenital heart disease as a child, you’re probably being followed by your cardiologist, since complications from early heart disease can arise in adulthood. In particular, if you had the “atrial switch” procedure for TGA (which is now infrequently used), you may be at greater risk for cardiac complications than if you had the “arterial switch” procedure more commonly in use now.

You may need lifelong monitoring and medication, since you’ll continue to be at some risk for heart problems in the future. Going forward, your cardiologist will advise you on activity levels, pregnancy issues and certain lifestyle choices.

Fortunately, Children’s can help adults with congenital heart defects. Many adults who were patients at Children’s as babies or children continue to be monitored by the clinicians who have followed them since childhood.

In addition, our Boston Adult Congenital Heart and Pulmonary Hypertension Service (BACH) provides long-term inpatient and outpatient care and advanced therapeutic options for patients with congenital heart disease and pulmonary hypertension as they reach and progress through adulthood.

BACH is an international center for excellence, with physicians and services from Children’s, Brigham and Women’s Hospital and the Beth Israel Deaconess Medical Center. The center promotes and supports clinical and scientific research for the advancement of care of these patients, and is a leader in the education of providers caring for this unique population.

What you can do at home

After surgery, your child’s cardiologist will offer recommendations for follow-up care, including:

  • wound care while the baby is healing
  • a nutritional program to encourage weight gain
  • an oral hygiene program to prevent infection
  • an appropriate exercise regimen to build body mass and achieve fitness

As your baby recovers and grows, be sure to follow a regular program of well-baby/well-child checkups.

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- Sandra L. Fenwick, President and CEO

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