Truncus arteriosus is a defect in the large blood vessels that leave the heart.

Normally, 2 large blood vessels, called the aorta and pulmonary artery carry blood away from the heart. The aorta carries oxygen-rich blood from the heart to the rest of the body. The pulmonary artery carries oxygen-poor blood from the heart to the lungs. As the heart develops. a section of these two blood vessels sometimes combine together. It creates one large vessel called the truncus arteriosus. The oxygen-poor and oxygen-rich blood leaving the heart mix in this combined blood vessel. The mixed blood decreases the amount of oxygen-rich blood that reaches the body.

The defect also includes a large hole in the wall between the lower chambers of the heart.

Heart Chambers and Valves
heart anatomy

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Blood Flow Through the Heart

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Truncus arteriosus is a problem with the development of the heart while the baby is in the womb. It is not known exactly why some hearts develop this way.

Risk Factors

Factors that may increase the risk for congenital heart disease may include:

  • Chromosomal disorders such as Down syndrome or DiGeorge syndrome
  • Conditions and lifestyle factors during pregnancy, such as:
    • Viral infection such as rubella
    • Poorly controlled diabetes
    • Alcohol consumption
    • Smoking
    • Taking certain medications such as thalidomide


Low oxygen levels in the body may cause symptoms such as:

  • Blue or pale grayish skin color
  • Fast breathing
  • Irritability
  • Poor feeding/poor weight gain


You will be asked about your child's symptoms and medical history. A physical exam will be done. A rapid heart rate may be detected during the exam.

Your child's bodily fluids may be tested. This can be done with blood tests.

Images may be taken of your child's bodily structures. This can be done with:

Your child's heart function may be tested. This can be done with:


Early treatment is important to help prevent complications such as heart failure. Treatment options may include:


Surgery is usually done right away, during infancy. The type of surgery depends on how severe the defect is. The goals are to improve circulation, which may be done by:

  • Creating a new pulmonary artery to carry blood to the lungs
  • Creating a new aorta to carry blood to the rest of the body
  • Closing the hole in the wall between the lower chambers of the heart

Other surgeries may be needed as your child grows.


Medications may be given to help support your child's heart before surgery. Medication may be given to:

  • Decrease fluid retention to lower workload on the heart
  • Improve heart function

After surgery, your child may need antibiotics before certain medical or dental procedures. This is to prevent an infection in the heart.

Lifelong Monitoring

Your child will have regular exams from a heart specialist.


It is not always possible to prevent heart defects since the cause is not clear. You can reduce the risk of heart defects by practicing good prenatal care such as:

  • Regular doctor visits to monitor your health and the health of the baby
  • Eating nutritious food and taking prenatal vitamins
  • Avoiding alcohol, smoking, or using drugs during pregnancy
  • Practicing good hygiene and staying away from people who are sick

American Heart Association

Family Doctor—American Family Physician


Canadian Cardiovascular Society

Heart and Stroke Foundation of Canada


Truncus arteriosus. American Heart Association website. Available at: Updated May 1, 2017. Accessed December 27, 2017.

Truncus arteriosus. EBSCO DynaMed Plus website. Available at: Updated January 25, 2016. Accessed December 27, 2017.

Truncus arteriosus. Johns Hopkins University, Cove Point Foundation website. Available at: Updated January 24, 2017. Accessed December 27, 2017.

Last reviewed November 2018 by EBSCO Medical Review Board Kari Kassir, MD  Last Updated: 12/20/2014