May also be called: Persistent Truncus Arteriosus; Common Truncus; Truncus

Truncus arteriosus (TRUNG-kus ar-teer-ee-OH-sus) is a heart defect that happens when a child is born with one large artery carrying blood to the lungs and body instead of two separate ones.

More to Know

Two arteries carry blood out of the heart. The pulmonary artery carries oxygen-poor blood from the right ventricle to the lungs. The aorta carries oxygen-rich blood from the left ventricle to the rest of the body.

In an embryo, the aorta and the pulmonary artery begin as a single vessel. During normal development, this large vessel splits in two to form the two arteries. If that split does not happen, the child is born with a single common blood vessel called the truncus arteriosus.

The truncus arteriosus is attached to the heart over both the right ventricle and the left ventricle. A hole called a ventricular septal defect (VSD) also exists between the two ventricles of the heart. All of these changes cause the oxygen-rich blood and oxygen-poor blood to get mixed together. This means the body gets less oxygen and more blood flowing to the lungs, which can cause breathing problems. Other symptoms of truncus arteriosus include a blue or purple tint to the skin, problems with feeding, failure to gain weight, sleepiness, excessive sweating, and an abnormal heartbeat.

A child born with truncus arteriosus might not look sick right away. But if it goes untreated, truncus arteriosus can quickly lead to heart failure and other life-threatening complications. Most babies who have it will undergo surgery in the first few months of life. In some cases, more than one operation is needed to separate the aorta and pulmonary artery and repair any associated heart defects.

Keep in Mind

Untreated truncus arteriosus will cause death, often in the first year of life. Surgery to repair it is usually successful, and the outlook for children after surgery is good. However, many children need more surgeries as they grow, and all need to be watched closely to help prevent future complications.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.