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).
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).
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.
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