Truncus Arteriosus
Before you begin reading about this heart defect, please read the explanation of how the normal heart works for a basic understanding of its structure and function.
- What is truncus arteriosus?
- What are the signs and symptoms?
- How is it diagnosed?
- What are the treatment options?
- What kind of follow-up care is required?
What is truncus arteriosus?
When the fetus develops during pregnancy, 
Truncus Arteriosus
Enlarge+the heart starts with a single large blood vessel coming from the heart called the truncus arteriosus. If fetal development progresses normally, the truncus divides into two arteries that carry blood out of the heart:
- the pulmonary artery, which is attached to the right bottom chamber (ventricle) of the heart and divides into two arteries carrying oxygen-poor ("blue") blood to each side of the lungs
- the aorta, which is attached to the left bottom chamber (ventricle) of the heart and carries oxygen-rich ("red") blood to the body.
Sometimes the single large blood vessel fails to divide during fetal development and the baby is born with a heart that has one artery carrying blood out of it. This condition is known as truncus arteriosus or persistent truncus arteriosus (the trunk "persists").
The undivided trunk is attached to the heart as one artery straddling the bottom chambers and then divides into arteries taking blood to the lungs and body. The oxygen-poor blood from the right ventricle (bottom chamber) and the oxygen-rich blood from the left ventricle (bottom chamber) mix when ejected out into the trunk, and more blood than normal goes back to the lungs making it harder for the infant to breathe.
In almost all cases, children with truncus arteriosus also have a large hole between the bottom chambers of the heart. This is called a ventricular septal defect or VSD.
As a result of these abnormalities, the baby's blood isn't as oxygenated as it should be when it circulates through the body.
What are the signs and symptoms?
Signs and symptoms include:
- blue or purple tint to lips, skin and nails (cyanosis)
- poor eating and poor weight gain
- rapid breathing or shortness of breath
- profuse sweating, especially with feeding
- more sleepiness than normal
- unresponsiveness (the baby seems "out of it")
- heart murmur - the heart sounds abnormal when a doctor listens with a stethoscope
How is it diagnosed?
Truncus arteriosus is life threatening; most babies won't live for more than a few months without treatment.
Usually a doctor will make the diagnosis before the newborn leaves the hospital if they hear a murmur or see a blue tint to the lips or skin. Or, a primary care pediatrician might detect the same symptoms during a checkup or a parent might notice symptoms and bring the baby to a doctor or hospital.
Diagnosis may require some or all of these tests.
- pulse oximetry - a painless way to monitor the oxygen content of the blood
- electrocardiogram (ECG) - a record of the electrical activity of the heart
- echocardiogram (also called "echo" or ultrasound) - sound waves create an image of the heart
- chest X-ray
- cardiac MRI - a three-dimensional image shows the heart's abnormalities
- cardiac catheterization - a thin tube is inserted into the heart through a vein and/or artery in either the leg or through the umbilicus ("belly button")
Sometimes truncus arteriosus is diagnosed on a fetal ultrasound and/or echocardiogram. Our Fetal Heart Program can prepare a plan for delivery and care immediately after birth.
A number of children with truncus arteriosus also have a genetic syndrome called 22q11 deletion syndrome (also known as DiGeorge, velocardialfacial or conotruncal anomaly face syndromes). Genetic testing (a blood test) for this syndrome may be part of our evaluation.
What are the treatment options?
Surgery is required, usually before the baby is two months old. More than one operation may be required.
Surgeons place a patch to close the hole (VSD). They separate the pulmonary arteries from the trunk, and then connect the pulmonary arteries to the right bottom chamber (ventricle) of the heart using different kinds of conduits (tubes). They repair the trunk so that it becomes a complete, functioning aorta. Other repairs may be needed, based on each child's unique needs.
After surgery, your child will initially recover in the Tabas Cardiac Intensive Care Unit (CICU) and then in the Cardiac Care Unit as he or she improves.
What kind of follow-up care is required?
Through age 18
A child who has had surgical repair of truncus arteriosus will require life-long care by a cardiologist.
Our pediatric cardiologists follow patients until they are young adults, coordinating care with the primary care physician. Patients will need to carefully follow doctors' advice, including staying on any medications prescribed and, in some cases, limiting exercise.
Sometimes children with this condition experience heart problems later in life, including irregular heartbeat (arrhythmia), a restricted conduit or pulmonary artery or a leaky aortic valve. Medicine, surgery and/or cardiac catheterization may be required.
Into adulthood
We will help patients transition care to an adult cardiologist.
The Philadelphia Adult Congenital Heart Center, a joint program of The Children's Hospital of Philadelphia and the University of Pennsylvania, meets the unique needs of adults who were born with heart defects.
Because of enormous strides in medicine and technology, today most children with heart conditions go on to lead productive lives as adults.
Contact the Cardiac Center at The Children's Hospital of Philadelphia for a second opinion or for more information.
Reviewed by: Elizabeth Goldmuntz, MD
Date: January 2009
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