Truncus Arteriosus

What is truncus arteriosus?

Truncus arteriosus (pronounced TRUN-kus ar-teer-ee-OH-sus) is a rare birth defect in which only 1 large artery leaves the heart.

Normally, 2 large arteries leave the heart — the aorta, which carries oxygen-rich (red) blood to the body, and the pulmonary artery, which carries oxygen-poor (blue) blood to the lungs.

In babies with this condition, the aorta and pulmonary artery are joined. They form a large common artery, called the truncus arteriosus, or trunk. The arteries to the lung (pulmonary arteries) branch off from this trunk.

There are 4 different types of truncus arteriosus (types I to IV). The type depends on the position of the pulmonary arteries and whether they developed as a single artery or several arteries. Your doctor will consider the type of truncus arteriosus your child has when recommending which kind of surgery is needed and when.

These babies also have a hole in the septum between their left and right ventricles. This hole is known as a ventricular septal defect. The hole allows oxygen-rich blood from the left ventricle to mix with oxygen-poor blood from the right ventricle.

The mixed blood enters the trunk and goes out to both the body and the lungs. This explains why a baby with this condition may be blue (cyanotic). Some of the blood going out to their body does not have oxygen.

The other main problem is that the lungs may get too much blood. This makes breathing hard, and it can lead to high blood pressure in the lungs and heart failure.

Truncus arteriosus in children

Before birth, it’s normal for babies to have one common artery leaving their heart. As they develop, this common artery should divide into an aorta and a pulmonary artery. It’s not clear why the common artery does not divide the way it should in some babies.

Truncus Arteriosus at Seattle Children’s


  • Our Heart Center is the top-ranked cardiology and cardiac surgery program in the Northwest and among the best in the nation, according to U.S. News & World Report. With more than 40 pediatric cardiologists, we have experience diagnosing and treating every kind of heart problem.

    Our heart team has treated many children with truncus arteriosus. We have extensive experience with the surgery these patients require. We also have a pediatric cardiac anesthesia team and a Cardiac Intensive Care Unit to help care for children who undergo heart surgery.

    See our statistics and outcomes for truncus arteriosus repair.

    The Adult Congenital Heart Disease Program shared by Seattle Children’s and the University of Washington can help with care throughout your child’s life.

    Seattle Children’s has been treating children since 1907. Our team members are experts in their fields and in meeting the unique needs of children. For example, the doctors who give your child anesthesia (sedation) are board certified in pediatric anesthesiology. This means they have extra years of training in how to take care of kids. Our child life specialistsknow how to help children understand their illnesses and treatments in ways that make sense for their age.

  • When you come to Seattle Children’s, a team of people will take care of your child. Along with your child’s heart doctor (cardiologist), you are connected with other providers, such as neonatologists, lung doctors (pulmonologists), nurses, child life specialists, social workers and others, if their expertise is needed.

    We work together to meet all of your child’s health needs and help your family through this experience. We’ll discuss treatments in ways you can understand and involve you in every decision.

    Read more about the supportive care we offer.

Symptoms of Truncus Arteriosus

Babies with truncus arteriosus may have these symptoms: 

  • Bluish skin, lips and nail beds (cyanosis)
  • Fast breathing
  • Working hard to breathe
  • Trouble feeding
  • Delayed growth or failure to thrive
  • Getting more tired than normal
  • Thicker, broader fingertips (clubbing)

They may also develop symptoms of heart failure.

Diagnosing Truncus Arteriosus

To diagnose this condition, your doctor will examine your child and use a stethoscope to listen to their heart. In children with this condition, doctors can often hear a heart murmur.

The doctor will ask for details about any symptoms your child has, their health history and your family health history.

Your child will need tests that provide more information about how their heart and nearby blood vessels look and work. These may include: 

Treating Truncus Arteriosus


Babies with truncus arteriosus need surgery early in life so the lungs get only oxygen-poor blood and the body gets only oxygen-rich blood.

During surgery, the doctor completes these steps: 

  • The doctor detaches the main pulmonary artery or the left and right pulmonary arteries from the large common artery. This leaves just the aorta coming out of the heart.
  • The doctor connects the main pulmonary artery or the left and right pulmonary arteries to the right ventricle. This may involve putting in a tube to make the connection. The doctor may also put in a pulmonary valve made from tissue from a cadaver.
  • The doctor closes the ventricular septal defect with a patch. This keeps oxygen-rich blood out of the right ventricle and oxygen-poor blood out of the left ventricle. The patch is placed so that blood flows from the left ventricle into the aorta. 

Before surgery to correct truncus arteriosus, some babies have surgery to put a band around their pulmonary artery. This narrows the artery so their lungs don’t get too much blood. Later these children still need the surgery described earlier. Most babies do not have pulmonary artery banding first. They just have surgery to correct their truncus arteriosus.

Later in life some children with truncus arteriosus need their aortic valve replaced because it did not form the correct way.


Babies with symptoms of heart failure may need medicines to help their heart work better until they have surgery.

Adult Congenital Heart Disease Program

To meet your child’s long-term healthcare needs, we have a special Adult Congenital Heart Disease Program to transition your child to adult care when they’re ready.

Contact Us 

Contact the Heart Center at 206-987-2515 to request an appointment, a second opinion or more information.

Providers, see how to refer a patient.