Transposition of the Great Arteries

What is transposition of the great arteries?

Transposition of the great arteries (often shortened to TGA) is a heart defect that is present at birth. The two large blood vessels that leave the heart, called the great arteries, are connected to the wrong pumping chambers. In a typical heart, the aorta (the main artery that carries oxygen-rich blood to the body) arises from the left ventricle, and the pulmonary artery (the artery that carries oxygen-poor blood to the lungs) arises from the right ventricle. In transposition of the great arteries, these connections are reversed, or transposed.

Because of this reversal, oxygen-poor blood returning from the body is pumped straight back out to the body instead of going to the lungs, and oxygen-rich blood from the lungs is pumped straight back to the lungs. The result is two separate circulations running in parallel rather than one continuous loop. A baby can survive for a short time only if there is a way for the two circulations to mix, for example through a hole between the heart chambers or a small vessel called the ductus arteriosus that normally closes soon after birth.

There are two main forms:

• Complete transposition (dextro-TGA or d-TGA): the more common and more serious form described above. It usually causes obvious problems in the first hours or days of life.
• Congenitally corrected transposition (levo-TGA or l-TGA): here both the great arteries and the ventricles are switched, so blood still flows in the correct order. However, the right ventricle, which is built to pump at low pressure to the lungs, ends up pumping to the whole body. Problems may not appear until later in childhood or adulthood.

Transposition of the great arteries is considered a rare condition. It affects newborns of all backgrounds and is somewhat more common in boys than in girls. It is often found alongside other heart defects, such as a hole between the ventricles (ventricular septal defect) or narrowing of the pulmonary valve (pulmonary stenosis).

Transposition of the great arteries symptoms

Transposition of the great arteries symptoms depend on the type of transposition, the presence of other heart defects, and how much mixing of blood is possible. In complete transposition, signs usually appear very soon after birth.

Common signs in a newborn with complete transposition include:

• Cyanosis: a blue or gray tint to the lips, tongue, skin, or nail beds, caused by low oxygen levels in the blood
• Fast or labored breathing
• Poor feeding and tiring quickly during feeds
• Weak pulse or cool hands and feet
• Unusual sleepiness or low energy
• Slow weight gain in the first weeks of life
• A heart murmur (an extra sound heard with a stethoscope), although a murmur is not always present

In babies who also have a large hole between the heart chambers, more blood can mix, so cyanosis may be milder at first. Instead, these infants may develop signs of heart failure over the first weeks, such as breathing quickly, sweating during feeds, and an enlarged liver. Heart failure means the heart cannot pump efficiently enough to meet the body’s needs; it does not mean the heart has stopped.

In congenitally corrected transposition, many children have no symptoms for years. Over time, the right ventricle may become tired from pumping against the high pressure of the body’s circulation, and the valve between the right-sided chambers may begin to leak. Symptoms that may appear in older children or adults include shortness of breath during activity, tiredness, swelling of the legs or abdomen, palpitations (an awareness of a fast or irregular heartbeat), fainting, or a very slow heartbeat caused by problems in the heart’s electrical system.

Causes and risk factors

Transposition of the great arteries causes are not fully understood. The defect develops during the first eight weeks of pregnancy, when the heart is forming and the single early outflow tube of the heart is dividing and rotating into two separate arteries. In transposition, this twisting process does not happen in the usual way. In most cases, no specific cause can be identified, and nothing the parents did or did not do is known to have caused it.

Researchers believe that a combination of genetic and environmental influences may play a role. Factors that have been linked with a higher chance of congenital heart defects in general, including transposition, include:

• Diabetes in the mother that is present before pregnancy or poorly controlled during pregnancy
• A viral illness such as rubella (German measles) during pregnancy
• Alcohol use during pregnancy
• Smoking during pregnancy
• Certain medications taken during pregnancy, such as some seizure medicines and some acne medicines
• Poor nutrition during pregnancy
• Maternal age over 40
• A family history of congenital heart disease
• Certain genetic conditions, although transposition is less strongly associated with chromosomal syndromes than some other heart defects

It is important to understand that most babies born with transposition of the great arteries have none of these risk factors, and most parents who have these risk factors have babies with normal hearts. These factors raise the chance somewhat; they do not determine the outcome.

Transposition of the great arteries diagnosis

Transposition of the great arteries diagnosis may happen before birth, shortly after birth, or, in the congenitally corrected form, later in life.

Before birth. A routine pregnancy ultrasound between roughly 18 and 22 weeks may show that the great arteries do not cross each other in the usual way. If the sonographer or obstetrician suspects a heart problem, the mother is usually referred for a fetal echocardiogram, which is a detailed ultrasound of the baby’s heart performed by a specialist in children’s heart disease. Detecting transposition before birth allows delivery to be planned at a hospital where the baby can receive immediate heart care.

After birth. In many countries, newborns are screened with pulse oximetry, a painless test that uses a small sensor on the hand or foot to measure the oxygen level in the blood. A low reading, or visible cyanosis, prompts urgent evaluation. Tests doctors use to confirm the diagnosis include:

• Echocardiogram: an ultrasound of the heart and the main test used to confirm transposition. It shows which artery comes from which ventricle, how blood is mixing, and whether other defects such as a septal defect or valve narrowing are present.
• Chest X-ray: may show a characteristic heart shape and changes in the lung blood vessels, though it cannot confirm the diagnosis on its own.
• Electrocardiogram (ECG or EKG): records the heart’s electrical activity and helps identify rhythm problems, which are especially relevant in congenitally corrected transposition.
• Blood tests: including measurement of oxygen and acid levels in the blood to assess how well the body is being supplied with oxygen.
• Cardiac catheterization: a thin tube is passed through a blood vessel into the heart to measure pressures and take pictures. It is not always needed for diagnosis but is sometimes used when the picture is unclear or when a treatment procedure is planned at the same time.
• Cardiac MRI or CT scan: detailed imaging that may be used, particularly in older children and adults, to look at the coronary arteries, the size and function of the ventricles, and the results of earlier surgery.

In congenitally corrected transposition, the diagnosis is sometimes made incidentally when an ECG or echocardiogram is performed for another reason, or when a slow heart rhythm or heart murmur is picked up during a routine check.

Transposition of the great arteries treatment

Transposition of the great arteries treatment almost always involves surgery. Complete transposition cannot be managed with medicines alone, and without repair the condition is usually fatal in infancy. Treatment is planned in stages, beginning with steps to stabilize the newborn and followed by a corrective operation.

Immediate stabilization. As soon as complete transposition is suspected, the baby is usually given a medicine called prostaglandin E1 through a vein. This keeps the ductus arteriosus open so that some oxygen-rich and oxygen-poor blood can continue to mix. Babies may also need oxygen, fluids, and help with breathing, and they are cared for in a neonatal or pediatric intensive care unit.

Balloon atrial septostomy. If mixing is still not enough, a doctor may perform a procedure through a catheter in which a small balloon is used to enlarge the natural opening between the two upper chambers of the heart. This increases mixing and raises oxygen levels while the baby waits for surgery.

Arterial switch operation. This is the standard corrective surgery for complete transposition and is usually performed in the first weeks of life, often within the first month. The surgeon divides the aorta and the pulmonary artery above their valves and reconnects them to the correct ventricles. Because the coronary arteries (the small vessels that supply the heart muscle itself) arise from the base of the aorta, they must be carefully moved as well. Any holes between the chambers are closed at the same time. The operation is performed with the support of a heart-lung machine. Timing matters because the left ventricle must still be strong enough to take over pumping to the body.

Other surgical approaches. When transposition is combined with a large ventricular septal defect and narrowing below the pulmonary valve, a different operation, often called a Rastelli procedure, may be used. It redirects blood inside the heart with a patch and places a tube (conduit) to carry blood to the lungs. Older children and adults who were treated decades ago may have had an atrial switch operation (known as the Mustard or Senning procedure), which redirects blood at the level of the upper chambers rather than the arteries. People who had these earlier operations need lifelong specialized follow-up.

Treatment of congenitally corrected transposition. Management depends on the person’s symptoms and any associated defects. Some people need no intervention for many years and are followed with regular checkups. Others may need medicines for heart failure, a pacemaker for a slow heart rhythm, repair or replacement of a leaking valve, or, in selected cases, complex surgery that reroutes blood so the left ventricle becomes the pump for the body. In advanced heart failure, heart transplantation may be considered.

Recovery and rehabilitation. After the arterial switch operation, babies typically spend time in intensive care and then on a hospital ward while feeding, breathing, and healing are monitored. Follow-up visits with a pediatric cardiologist continue throughout childhood and into adulthood, usually with periodic echocardiograms and ECGs. In hospital groups such as Acibadem, this type of care is coordinated between pediatric cardiology and the Cardiovascular Surgery department.

Living with transposition of the great arteries and outlook

The outlook for children with transposition of the great arteries has changed greatly since the arterial switch operation became standard. Many children who undergo successful repair grow up to attend school, play, and take part in normal activities, and a large proportion reach adulthood in good health. However, the heart has been surgically rebuilt, and lifelong follow-up with a cardiologist experienced in congenital heart disease is essential. No one can guarantee a particular outcome for an individual child, and your care team is the best source of information about your child’s specific situation.

Possible long-term issues that doctors watch for after an arterial switch include narrowing where the pulmonary artery was reconnected, leakage or widening of the new aortic valve and root, problems with the coronary arteries, and heart rhythm disturbances. Some of these may require further procedures years later. People who had an atrial switch operation earlier in life face a different set of concerns, including weakening of the right ventricle and rhythm problems, and they are generally followed more closely.

Everyday life usually includes:

• Regular cardiology appointments, with the frequency set by your doctor
• Maintaining good dental hygiene, since some people with repaired heart defects have a higher chance of heart valve infection
• Discussing physical activity and sports with the cardiologist; many children are encouraged to be active, while some may be advised to avoid particular high-intensity or competitive activities
• Planning ahead for pregnancy, since women with repaired transposition often need specialist assessment before and during pregnancy
• Transitioning from pediatric to adult congenital heart disease care in the teenage or young adult years

Emotional support matters as well. Parents of a newborn with a serious heart condition often experience shock, fear, and exhaustion, and older children and adults may worry about scars, limitations, or the future. Talking with the care team, counselors, or support groups for families affected by congenital heart disease can help.

Frequently asked questions

What are the first transposition of the great arteries symptoms in a newborn?

The most recognizable early sign is a blue or gray color to the lips, skin, or nail beds within the first hours or days of life, together with fast breathing and difficulty feeding. In babies who also have a large hole between the heart chambers, the blue color may be less obvious and signs of heart failure may develop over the following weeks instead.

What are the main transposition of the great arteries causes?

In most cases the exact cause is unknown. The defect develops early in pregnancy when the heart’s outflow vessels form. Genetic factors and certain conditions during pregnancy, such as diabetes, viral infections like rubella, or exposure to alcohol or some medications, may increase the chance, but many affected babies have no identifiable risk factor.

How is transposition of the great arteries diagnosis confirmed?

An echocardiogram, which is an ultrasound of the heart, is the main test used to confirm the condition. It can be performed before birth as a fetal echocardiogram or after birth if cyanosis or low oxygen levels are found. Other tests, such as an ECG, chest X-ray, blood tests, cardiac catheterization, or MRI, may add information.

Is transposition of the great arteries treatment always surgery?

For complete transposition, yes, corrective surgery, usually the arterial switch operation, is necessary and is typically performed in the first weeks of life. Medicines and a balloon procedure are used beforehand to keep the baby stable. For congenitally corrected transposition, treatment varies, and some people may be monitored for years before any intervention is needed.

Can transposition of the great arteries be detected during pregnancy?

It often can. A routine mid-pregnancy ultrasound may raise suspicion, and a fetal echocardiogram can confirm the diagnosis. Not every case is detected before birth, which is one reason newborn pulse oximetry screening is used in many hospitals.

Will my child need more operations after the arterial switch?

Many children do not, but some develop narrowing at the surgical connections, valve leakage, or coronary artery problems that may require a catheter procedure or further surgery years later. Regular follow-up is designed to detect these issues early. Your child’s cardiologist can explain what to expect based on the findings at each checkup.

Can adults have undiagnosed transposition of the great arteries?

Complete transposition is almost always found in infancy because it causes severe symptoms. Congenitally corrected transposition, however, can go unnoticed for many years and is sometimes first discovered in adulthood during evaluation for a slow heart rhythm, a murmur, or symptoms of heart failure.

When to see a doctor

If your baby has been diagnosed with transposition of the great arteries, or has had heart surgery, your care team will give you specific guidance about warning signs. In general, seek emergency care immediately if a baby or child shows any of the following:

• Blue, gray, or very pale color of the lips, tongue, or skin, or a sudden worsening of an existing blue tint
• Rapid breathing, grunting, flaring nostrils, or pulling in of the chest with each breath
• Difficulty breathing, pauses in breathing, or breathing that seems to require great effort
• Extreme sleepiness, limpness, or difficulty waking
• Refusal to feed, or sweating and exhaustion during feeds
• Fainting or collapse
• A very fast, very slow, or irregular heartbeat
• Fever, redness, swelling, or drainage at a surgical wound

Older children and adults living with transposition should seek prompt medical attention for new or worsening shortness of breath, chest pain, palpitations, fainting, unexplained fever lasting several days, or swelling of the legs or abdomen. For non-urgent concerns, such as questions about activity, growth, medications, or planning a pregnancy, discuss them at your next scheduled visit or contact your cardiology team as they have advised.