Truncus Arteriosus


Truncus arteriosus (TRUNG-kus ahr-teer-e-O-sus), sometimes called “common truncus,” is a rare congenital (present at birth) heart defect in which a single common valve (truncal valve) comes out of the heart, instead of two valves – the aortic valve and pulmonary valve. It can occur by itself or as part of certain genetic disorders.

Cases of truncus arteriosus can vary depending on how the pulmonary arteries exit the aorta. Along with the different types, varying levels of complexity exist within this one diagnosis. With truncus arteriosus, a large hole is usually found between the two ventricles (ventricular septal defect), which causes oxygen-poor (blue) blood and oxygen-rich (red) blood to mix together; too much blood goes to the lungs, and the heart works harder to pump blood to the rest of the body. 

The truncal valve is often abnormal with this disease. It can be thickened and narrowed, which can block the blood as it leaves the heart, or it can leak, causing blood that leaves the heart to leak back into the heart across the valve. The presence of narrowing and leaking is a predictor of poorer outcomes.

According to the Centers for Disease Control and Prevention (CDC), truncus arteriosus occurs in fewer than one out of every 10,000 live births, which means that about 300 babies are born with truncus arteriosus each year in the United States.

Causes of Truncus Arteriosus

Causes of Truncus Arteriosus

Like many congenital heart defects, the cause of truncus arteriosus is largely unknown. It is the result of problems that occurred when your baby was still developing in the womb. 

The formation of the heart during fetal growth is a very complex process. In the early stages of growth, all fetuses have a single large vessel exiting the heart; however, during normal development the large single vessel divides into two smaller parts: one part becomes the lower portion of the aorta, and the other part becomes the lower portion of the pulmonary artery. 

Truncus arteriosus occurs when the single large vessel never finishes dividing into two separate vessels, and the wall separating the two ventricles never closes completely, which results in a large hole between the two chambers (ventricular septal defect).

Symptoms of Truncus Arteriosus

Symptoms of Truncus Arteriosus

A baby with truncus arteriosus generally begins to show signs of the defect within the first week of life. His or her oxygen levels are often slightly lower than normal, which can cause your baby’s skin to have a bluish-purple color (cyanosis), especially around the mouth and nose. The signs and symptoms may increase when your baby is eating.

Other symptoms include: 

  • Delayed growth or failure to grow 
  • Fatigue
  • Lethargy
  • Poor feeding
  • Rapid breathing (tachypnea)
  • Shortness of breath (dyspnea)
  • Widening of the finger tips (clubbing)
Diagnosis and Treatment Options

Diagnosis and Treatment Options

In most cases this one test will provide enough evidence to recommend treatment, but in rare occasions your baby may undergo a cardiac catheterization for further analysis. 

Other tests your doctor might order to confirm a diagnosis include chest x-ray, electrocardiogram (EKG), or magnetic resonance imaging (MRI).

Transthoracic two-dimensional echocardiogram apical four-chamber image showing type 1 truncus arteriosus

For more information on these tests, visit our common diagnostic tests page.

Surgery is the only treatment for truncus arteriosus, which often will be performed before your baby is 3 months old. 

Be sure to speak with your baby’s pediatric/congenital heart surgeon (cardiothoracic surgeon) about what you should expect during and after the surgery. You can print these sample questions to use as a basis for discussion with the doctor.

Expected outcomes: The Society of Thoracic Surgeons (STS) Congenital Heart Surgery Database shows an expected outcome of 6.8% mortality for repair of truncus arteriosus. Outcomes will vary across different programs. It is appropriate to inquire about the outcomes of a surgical group or surgeon during your consultation.


During the procedure, the surgeon will create a pulmonary artery using either tissue from another area of the body or using a prosthetic tube. The existing truncal vessel is usually made into the aorta, and the hole between the two ventricles will be closed, likely with a patch. 

Multiple procedures or surgeries may be necessary because the material used to make the pulmonary artery will not grow as your child grows. 





A typical stay in the hospital after surgery is 1 week, if recovery is uncomplicated. If your child needs repair in the first weeks of life, the hospital stay likely will be longer. After repair, most children go on to live healthy, productive lives.

patient recovering from surgery

Some children may have restrictions on exercise and certain activities, but speak with your doctor to find out what is recommended for your child. 

Your child may be required to take antibiotics during dental procedures to prevent infections that may cause inflammation of the heart (endocarditis). Preventive antibiotics are almost always recommended for people who have artificial valves or who’ve had repair with prosthetic material. 

Possible complications later in life include heart failure and having high blood pressure in the lungs (pulmonary hypertension). 

Reviewed by: Lauren C. Kane, MD
December 2017