Truncus Arteriosus

Truncus arteriosus is a rare heart defect that some babies are born with. It means there’s just one artery that carries blood out of your baby’s heart, rather than two. Normally, the aorta sends oxygen-rich blood to the body. And the main pulmonary artery sends oxygen-poor blood to the lungs.

But with truncus arteriosus, these two arteries are combined as a single vessel that sends mixed blood to your baby’s lungs and their body.

Truncus arteriosus overworks your baby’s heart and lungs. It makes their heart pump too much blood to their lungs. It also prevents their organs and tissues from receiving enough oxygen. That’s why healthcare providers call it a critical congenital heart defect. Babies need treatment right away to survive.

Your baby will likely have surgery within weeks of birth. Surgeons can create two separate paths for blood to flow out of your baby’s heart. This reduces the strain on their heart and lungs and lets their body get enough oxygen. As your child grows and the oxygen needs for their organs change, they’ll need more surgeries to keep their heart working as it should. Their care team will be with you each step of the way.

Symptoms of truncus arteriosus

Signs and symptoms typically appear within the first few days of life. You might notice some on your own. Healthcare providers may notice others during a check-up. Newborns with truncus arteriosus may have:

• Blue or gray skin color (cyanosis), especially around your baby’s mouth and fingertips
• Extreme sleepiness
• Fast heart rate
• Slow weight gain
• Trouble breathing
• Trouble feeding, including falling asleep or sweating while feeding
• Weak pulse

About 1 in 3 babies with truncus arteriosus have DiGeorge syndrome. This is a genetic disorder that may cause signs and symptoms affecting other parts of their body, too.

Truncus arteriosus causes

Truncus arteriosus happens when the fetal heart doesn’t develop as it should during pregnancy. In most cases, there’s no clear reason why. But if your child has DiGeorge syndrome, the gene changes that cause the disorder are responsible for this heart defect.

Normally, a fetal blood vessel called the truncus separates into two distinct arteries before your baby is born. A wall of tissue called the aortopulmonary septum marks the boundary between the two vessels and prevents blood from mixing.

But for unknown reasons, the truncus might not form in this way. Instead, the truncus remains (persists) as a single common artery. That’s why healthcare providers sometimes call this condition “persistent truncus arteriosus” or “common arterial trunk." The truncus itself is a normal part of fetal development. But it’s not supposed to persist past birth.

Risk factors

Your baby may have a higher risk of developing truncus arteriosus or other forms of congenital heart disease if you’re pregnant and:

• Have diabetes
• Have certain viral infections, like rubella
• Use alcohol or other addictive substances
• Are exposed to lead or other harmful substances known to affect fetal development

How doctors diagnose this condition

Healthcare providers usually diagnose truncus arteriosus during your baby’s first few days of life when symptoms appear. If providers suspect a heart issue, they perform an echocardiogram. This test can show truncus arteriosus and other heart issues.

It’s also possible for pulse oximetry — part of routine newborn screenings — to show low oxygen levels before other signs develop.

Sometimes, providers notice truncus arteriosus before birth on a prenatal ultrasound. If your provider thinks there might be a heart defect, they may do a fetal echocardiogram. This test shows fetal heart anatomy in more detail.

Truncus arteriosus types

Your child’s care team may mention a specific type of truncus arteriosus. These types describe the anatomy of your child’s left and right pulmonary arteries, which carry blood to their lungs. These arteries normally branch off the main pulmonary artery. But with truncus arteriosus, the branch arteries start in different spots:

• Type 1: One pulmonary artery starts at the truncus before splitting into two branch arteries.
• Type 2: Both branch arteries start at the truncus. Their points of origin are close together.
• Type 3: Both branch arteries start at the truncus. But their points of origin are farther apart than in type 2.

Other variations are possible. Healthcare providers use this knowledge of your child’s anatomy to guide surgery.

Associated heart conditions

Babies with truncus arteriosus usually also have both of the following:

• Ventricular septal defect (VSD): This is a hole in the wall that separates the two lower heart chambers (ventricles). It causes blood from both ventricles to mix before leaving your baby’s heart.
• Truncal valve: This is a valve that controls blood flow out of the single vessel leaving your baby’s heart. Normally, a baby should have two separate valves (the aortic valve and the pulmonary valve). These control blood flow out of the aorta and the main pulmonary artery.

Other heart defects that may occur with truncus arteriosus include:

• Anomalous coronary artery: One of the heart’s main arteries is in the wrong place.
• Atrial septal defect (ASD): There’s a hole in the wall separating the upper heart chambers.
• Interrupted aortic arch: There’s a gap in the curved part of the aorta (the largest artery).
• Right aortic arch: The curved part of the aorta is on the right side of the trachea, rather than the left as expected.

How is truncus arteriosus treated?

Babies with truncus arteriosus need heart surgery within the first weeks of life. The most common procedure is called a Rastelli repair. This creates two separate paths for blood to leave your baby’s heart.

Your baby’s surgeon will:

• Use a patch to close the hole (ventricular septal defect) in your baby’s heart
• Create a new aorta using the existing single blood vessel (truncus)
• Create a new aortic valve using the existing truncal valve
• Place an artificial tube, called a conduit, and an artificial valve to create a new pulmonary artery and valve

These are the basic steps for truncus arteriosus repair. Your baby’s surgery may include other steps if they have other heart defects that need repair. Their surgeon will explain exactly what’s needed for their unique heart anatomy.

Follow-up surgeries

Down the road, your child will need more surgeries to keep their heart and blood vessels working normally. For example, the artificial pulmonary conduit doesn’t grow with your child. So, they’ll need a new one that’s typically larger in size as they get older. Your child may also have issues with their heart valves.

Your child’s surgeon will tell you more about future surgeries and what they’ll involve. Your child will likely need another surgery within three to 10 years after their first one, and possibly more after that.

When should I contact a healthcare provider?

Seek medical care right away if your baby doesn’t seem well in their first few days of life. Some truncus arteriosus signs, like bluish skin tone and trouble feeding, can also point to other serious heart issues.

Follow-up care is very important after truncus arteriosus repair. Your baby’s care team will explain what’s needed and when.

Over the years, you’ll work closely with a heart specialist called a pediatric cardiologist. They’ll run tests to monitor your child’s heart and plan the best timing for other treatments or surgeries.

Life expectancy

How long children with truncus arteriosus live depends on many things, including the complexity of their heart anatomy and other health conditions they have. In general, research shows:

• About 80% to 97% of babies survive truncus arteriosus surgery.
• About 3 in 4 babies who have surgical repair are alive 20 years later.
• About 9 in 10 babies who survive one year after surgery are alive at 20 years.

Numbers don’t always tell the full story. Your child’s care team can give you the best sense of what to expect and how to support your child.