What is Truncus Arteriosus?

Truncus arteriosus is a congenital defect, which means it is present at birth. Normally, the heart has two separate arteries: one carries blood from the heart to the body, and the other carries blood from the heart to the lungs. In infants with truncus arteriosus, the heart only has one artery, which disrupts normal blood flow.

People with truncus arteriosus usually also have a ventricular septal defect (VSD) or a hole between the two lower chambers of the heart. This hole, in combination with truncus arteriosus, causes oxygen-depleted blood coming from the body to mix with the oxygen-rich blood coming from the lungs, leading to severe problems with oxygenation.

Because this defect is present at birth, signs and symptoms develop in the first few hours or days of life and include blue coloring of the skin, shortness of breath, rapid breathing, poor feeding, a pounding heart, and excessive sleepiness. Over time, infants with this condition experience poor growth as well.

Truncus arteriosus can be fatal if left untreated. Signs that may indicate an infant requires urgent medical attention include labored, rapid, or shallow breathing, worsening of the blue color of the skin, and loss of consciousness. If any of these symptoms develop, parents should seek immediate medical attention for their child.

Some screening tests performed during pregnancy can detect congenital abnormalities including truncus arteriosus, which can be picked up during an ultrasound. If doctors suspect truncus arteriosus, they may request a fetal echocardiogram for a more detailed picture of the heart. This can confirm the diagnosis and give a better idea of how the heart is functioning.

A fetus gets oxygenated blood from the placenta. This changes after birth when the baby breathes for the first time and the doctor clamps the umbilical cord. At this point, the baby's blood pressure naturally rises. In infants with truncus arteriosus, blood shunting to the lungs begins its abnormal circulatory path, making the heart work harder. A pulse oximeter to check the infant's oxygen level is often the first test, performed right at the bedside, when doctors note symptoms of this condition. The doctor will also do an echocardiogram immediately.

Surgery to repair the heart and vessels will usually take place within the first few weeks of the infant's life. While the specifics of the procedure depend on the condition of each infant, the surgery will usually involve patching the VSD, placing a conduit and artificial valve to create a new pulmonary artery to carry oxygen-poor blood to the lungs, and reconstructing a complete aorta from the original single vessel.

After surgery, babies with truncus arteriosus require lifelong care including regular visits to a cardiologist to monitor heart health. Children may need to limit their physical activity and take antibiotics prior to any dental procedure to prevent heart infections. Additional surgeries will also be needed as the child grows to replace the artificial conduit and valve.

Adults who had truncus arteriosus repair as infants may experience complications as they get older. The heart can lose its ability to contract effectively, so they may need to take diuretics to control fluid and other medications to help maintain blood pressure. Arrhythmias are common and can require medication. Pulmonary hypertension can also progress over time and requires medication and other interventions.

It can be challenging for expectant or new parents to cope with a diagnosis of truncus arteriosus. The American Heart Association and other non-profit organizations can provide information about local support groups. Keeping careful records of doctors' names, medications, surgeries, and procedures can help prepare for appointments. It is also helpful to keep a list of questions to ask the cardiologist about which activities the child can and cannot participate in as they get older.