Transposition of the Great Arteries
The heart's two main arteries are connected to the wrong chambers
Quick Facts
- Type: Cyanotic congenital heart defect
- What it is: Main arteries attached to the wrong chambers
- Key sign: Bluish skin soon after birth
- Treatment: Urgent surgery in the newborn period
Overview
Transposition of the great arteries (TGA) is a serious congenital heart defect in which the two main arteries leaving the heart are switched. The aorta, which should carry oxygen-rich blood to the body, instead arises from the right chamber and recirculates oxygen-poor blood, while the pulmonary artery carries oxygen-rich blood back to the lungs. As a result, the body does not receive enough oxygen.
TGA is usually identified at or soon after birth because the baby appears blue. It is a life-threatening condition that requires urgent treatment, but with prompt surgery most children do well and lead active lives.
Symptoms
Symptoms typically appear within hours to days of birth.
- Bluish color of the skin, lips, and nails (cyanosis) that does not improve with oxygen
- Rapid or labored breathing
- Poor feeding
- Lack of energy and weak responses
- A heart murmur in some cases
Because the body is not getting enough oxygen, a newborn with TGA can become critically ill quickly, sometimes within the first hours of life. The blue color of TGA typically does not improve when extra oxygen is given, which is an important clue. Marked blue color in a newborn is a medical emergency requiring immediate care, and any baby who appears blue and is struggling should be seen urgently.
Causes
TGA develops during fetal heart formation, when the great arteries connect to the wrong chambers. The exact cause is usually unknown.
- Abnormal fetal development: The arteries form in switched positions.
- Genetic factors: A family history of heart defects may slightly increase risk.
- Conditions during pregnancy: Maternal diabetes, viral illness, poor nutrition, and certain exposures are associated with congenital heart defects in general.
In most cases no single cause is identified, and many babies with TGA have no other health problems.
Risk Factors
- Maternal diabetes, particularly if poorly controlled
- Viral illness such as rubella during pregnancy
- Poor nutrition or alcohol use during pregnancy
- A family history of congenital heart defects
- Older maternal age
Diagnosis
TGA is often suspected before birth or detected soon after when a newborn is blue. Tests confirm the diagnosis.
- Prenatal ultrasound: Can identify the defect during pregnancy, allowing planning for delivery.
- Echocardiogram: The main test, clearly showing the switched arteries and blood flow.
- Pulse oximetry: Newborn screening may flag low oxygen levels.
- Chest X-ray and ECG: Provide additional information about the heart's size and rhythm.
- Cardiac catheterization: Sometimes used to assess the heart in detail or perform a balloon procedure.
Treatment
TGA needs prompt treatment to improve oxygen delivery and then a corrective operation.
- Stabilizing medication: A medicine may be given to keep a fetal blood vessel open temporarily, helping oxygen-rich blood mix until surgery.
- Balloon procedure: A catheter technique can create or enlarge an opening between the upper chambers to improve mixing of blood.
- Arterial switch surgery: The main corrective operation, in which the arteries are reconnected to the correct chambers, usually in the first weeks of life.
After surgery, lifelong follow-up with a heart specialist monitors heart function, and most children grow up to be active. The arterial switch operation has greatly improved outcomes, and long-term results are generally very good. Over the years, specialists watch for issues such as narrowing where the arteries were reconnected, problems with the heart valves, or irregular heart rhythms, any of which can sometimes need treatment later in life. Adults who had TGA repaired as infants are usually cared for in clinics that specialize in adult congenital heart disease. With this ongoing care, many people with repaired transposition complete their education, work, and take part in physical activity, often with only modest limits. Each person's plan is tailored to their individual heart anatomy and how it has healed.
When to See a Doctor
TGA is a newborn emergency. Seek immediate medical care or call emergency services if a baby:
- Has bluish skin, lips, or nails, especially if it does not improve
- Is breathing rapidly or with difficulty
- Feeds very poorly or is unusually limp and unresponsive
- Appears to be deteriorating quickly
Babies diagnosed before birth should deliver where specialist newborn heart care is available.
Frequently Asked Questions
Why does transposition of the great arteries cause low oxygen?
Because the arteries are switched, oxygen-poor blood is pumped back out to the body instead of to the lungs. The body therefore does not receive enough oxygen, giving the baby a blue color. Some mixing of blood through other openings is needed for survival until surgery.
Is transposition of the great arteries an emergency?
Yes. TGA is a life-threatening newborn emergency because the body is starved of oxygen. It requires urgent stabilization and corrective surgery, usually within the first weeks of life. A deeply blue newborn needs immediate medical care.
How is transposition of the great arteries treated?
Babies are first stabilized, sometimes with medication and a balloon procedure to improve blood mixing. The definitive treatment is the arterial switch operation, which reconnects the arteries to the correct chambers. Most children do well afterward.
Can transposition be detected before birth?
Yes, it can often be seen on a detailed prenatal ultrasound. Diagnosing it before birth allows parents and the medical team to plan delivery at a center with specialized newborn heart care, improving outcomes.
Do children with TGA live normal lives?
With timely surgery and ongoing specialist follow-up, most children with TGA grow up to lead active lives. Regular heart check-ups monitor for any later issues. Long-term outcomes have improved greatly with modern treatment.
References
- Centers for Disease Control and Prevention (CDC). Transposition of the Great Arteries.
- Mayo Clinic. Transposition of the great arteries.
- MedlinePlus, U.S. National Library of Medicine. Transposition of the great vessels.