Transposition of the Great Arteries

Transposition of the great arteries is a rare and very serious heart defect that occurs when the two major arteries attached to the heart are reversed. As a result, the heart is unable to send enough oxygenated blood to the body.

About Transposition of the Great Arteries

A rare congenital heart defect, transposition of the great arteries is diagnosed when the two major arteries attached to the heart are reversed. Also known as transposition of the great vessels, the heart is unable to send enough oxygenated blood to the body because delivery of oxygen-poor and oxygen-rich blood are switched when the pulmonary artery and aorta are reversed. Without treatment, your baby won’t have adequate oxygen in the bloodstream and may suffer serious complications, such as congestive heart failure. Transposition of the great arteries is a serious heart condition, but corrective surgery can restore heart function and help your baby live a normal life.

Transposition of the great arteries develops in the first eight weeks of pregnancy as the heart begins to take shape. Normally, oxygen-depleted blood flows into the right side of the heart and the right ventricle pumps blood into the pulmonary artery to be oxygenated in the lungs. Oxygen-rich blood returns to the left side of the heart and the left ventricle pumps blood to the body through the aorta. With the transposition of the great arteries, the aorta attaches to the right ventricle, sending oxygen-poor blood back to the body. The pulmonary artery attaches to the left ventricle, sending oxygen-rich blood back to the lungs. The two separate circuits prevent your baby’s body from getting enough oxygen.

A child who has transposition of the great arteries may have other heart defects that can temporarily help their body receive more oxygen, such as:

• Atrial Septal Defect or Ventricular Septal Defect: A hole in the wall between the atria or ventricles, that allows blood from both sides of the heart mix, sending blood with a higher level of oxygenation to the body.
• Foramen Ovale: Located in the wall between the atria, the foramen ovale allows blood to skip the necessary step of circulation. The foramen ovale is a natural opening present in a normal heart in utero but closes soon after birth. If the vessel remains or is kept open, oxygen-poor and oxygen-rich blood mixes, sending blood with a higher level of oxygenation to the body.
• Patent Ductus Arteriosus: The ductus arteriosus is a blood vessel between the pulmonary artery and the aorta that when open (patent), allows blood to skip the necessary step of circulation. The ductus arteriosus is a natural opening that is present in a normal heart in utero but closes soon after birth. If the vessel remains or is kept open, oxygen-poor and oxygen-rich blood mixes, sending blood with a higher level of oxygenation to the body.

Transposition of the great arteries mostly develops by chance, but there may be a genetic link to the mother being over the age of 40. The mother having diabetes, poor nutrition, rubella, or a viral illness as well as consuming alcohol during pregnancy may increase the baby’s risk.

Symptoms of Transposition of the Great Arteries

Babies who are born with transposition of the great arteries typically have symptoms soon after birth and may look blue within the first day because of the lack of oxygen in the bloodstream.

Symptoms of transposition of the great arteries may include:

• Blue color to the skin, lips, and nails
• Cool, clammy skin
• Heart murmur
• Rapid or labored breathing
• Rapid heart rate
• Trouble feeding or lack of appetite

Diagnosing Transposition of the Great Arteries

Transposition of the great arteries may be detected with fetal echocardiography (ultrasound) before birth. The fetal echocardiography can be done as early as 16 weeks of gestation. After birth, your child’s doctor may recognize signs of transposition of the great arteries, such as a heart murmur or blue-tinged skin (cyanosis). If your doctor suspects transposition of the great arteries, a recommendation to see a pediatric cardiologist may be made.

Tests performed when diagnosing transposition of the great arteries may include:

• Cardiac Catheterization: During cardiac catheterization, a small catheter (thin tube) is inserted into a larger blood vessel, typically in the groin, and guided to the heart where blood pressure and oxygen measurements can be taken in the aorta and pulmonary artery as well as the four chambers of the heart. A dye can also be injected through the tube to make the heart’s structure more visible on an X-ray.
  
• Chest X-Ray: A chest X-ray produces an image of the tissue and bones in the heart and lungs and helps your provider assess the shape, size, and structure of the heart and lungs as well as the aeration of or any congestion in the lungs.
• Echocardiogram: An echocardiogram uses ultrasound technology to create a moving image of the heart and its valves, allowing your provider to assess the structure and function of the heart. An echocardiogram also helps provide information about blood flow and how well the heart is pumping blood.
• Electrocardiogram (ECG or EKG): An electrocardiogram uses electrodes that are placed on the body to record the electrical activity taking place in the heart. An ECG/EKG test helps detect abnormal rhythms, such as cardiac arrhythmias, stress on the heart, and damage to the heart muscles.
• Pulse Oximetry: A pulse oximeter, or oxygen saturation test, is an electronic tool used to measure oxygen in the bloodstream.

Treating Transposition of the Great Arteries

Until corrective surgery can take place, your pediatric cardiologist may treat your baby with intravenous, or IV, medication (prostaglandin) to keep the ductus arteriosus open and perform balloon or atrial septostomy using cardiac catheterization to widen the foramen ovale to improve the oxygen level in the blood.

Surgery to repair transposition of the great arteries and correct other heart defects may be done in the first or second week of your baby’s life. A pediatric heart surgeon performs a procedure, known as an arterial switch, to move the aorta to the left ventricle, the pulmonary artery to the right ventricle, and connect the coronary arteries to the aorta to ensure the heart muscle receives oxygen-rich blood.

After treatment, most babies who have transposition of the great arteries develop and grow normally and should be able to have an active lifestyle. Your pediatric cardiologist may recommend limiting or avoiding specific activities that may stress your child’s heart. Your child may need lifelong care from a cardiologist to check for complications, such as leaky heart valves.

Care Team Approach

The Texas Center for Pediatric and Congenital Heart Disease, a clinical partnership between Dell Children’s Medical Center and UT Health Austin, takes a multidisciplinary approach to your child’s care. This means your child and your family will benefit from the expertise of multiple specialists across a variety of disciplines. Your care team will include pediatric cardiologists, cardiothoracic surgeons, interventional cardiologists, critical care specialists, hospitalists, anesthesiologists, perfusionists, nurses, advanced practice providers, social workers, psychologists, child life specialists, dietitians, physical and occupational therapists, pharmacists, and more, who work together to provide unparalleled care for patients every step of the way. We collaborate with our colleagues at the Dell Medical School and The University of Texas at Austin to utilize the latest research, diagnostic, and treatment techniques, allowing us to identify new therapies to improve treatment outcomes. We are committed to communicating and coordinating your child’s care with referring physicians and other partners in the community to ensure that we are providing comprehensive, whole-person care.

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