What is truncus arteriosus?

Truncus arteriosus (TA) is a rare congenital heart defect, occuring in 7 out of 100,000 births, in which a baby’s heart develops with a single artery instead of the usual two^1,2. The condition occurs when the heart is still forming during pregnancy, where two main blood vessels (the aorta and pulmonary artery) don’t separate properly, and instead stay as one large vessel called an ‘arterial trunk’.² Most people with TA also have a hole in the bottom two areas of the heart (the ventricles) known as a ventricular septal defect (VSD).

As a result of these defects, babies born with TA experience excessive blood flow to the lungs, while the blood circulating to the rest of the body carries insufficient oxygen. This can lead to breathing difficulties and other health complications, which can prove fatal within 2 months if left untreated.³ Given these potentially life-threatening consequences, it is important to diagnose, treat and closely monitor patients with TA as early as possible to improve the chances of survival for babies with TA. This article will discuss the treatment o​​f truncus arteriosus, focusing on prognosis after surgical repair and the long-term management of the condition.

How is truncus arteriosus diagnosed and treated?

Diagnosis

TA is most commonly diagnosed postnatally (after birth) using a specialised ultrasound scan called an echocardiogram.⁴ This type of scan is usually done a few weeks after the baby is born if the doctor spots certain abnormalities. This includes:⁴

• Blueish skin (cyanosis)
• Having trouble breathing
• Irregular heartbeat
• Difficulty when eating/feeding

Other tests used to diagnose TA include chest X-rays and electrocardiograms (ECGs).⁴

TA can also be diagnosed prenatally (before the baby is born) if the doctor believes the baby is at risk due to factors such as maternal diabetes, smoking or drinking during pregnancy, or genetic conditions linked to congenital heart defects.²

Early diagnosis is important as it allows doctors to plan for treatment in advance, significantly improving the baby’s chance of survival and reducing any chances of further complications. Detecting TA prenatally also ensures that delivery of the baby can take place at specialised facilities, such as a children’s cardiac ward, where treatment can be prompt.⁴

Treatment

The most effective type of treatment for TA is repair surgery, which is usually done within a few weeks after birth.⁵ During the operation, the surgeons:⁵

• Close the ventricular septal defect (VSD) using an artificial patch
• Create a blood vessel to carry oxygen-rich blood around the body called an aorta
• Build an artificial blood vessel (i.e., a conduit) to carry oxygen-poor blood towards the lungs, known as a pulmonary artery

In some cases, babies may be too weak to have the operation right after birth, and may need extra care beforehand. This could include medication to help the heart pump better, high-calorie formula to help the baby gain weight, or tube feeding if they are too weak to eat. For some babies, a temporary operation is done where a band is placed around the pulmonary artery to control blood flow and protect the lungs, giving time for the baby to grow before the repair operation.⁶

What is life like after truncus arteriosus repair?

Recovery & complications post-surgery

After repair surgery, babies are closely monitored in a children’s intensive care unit for the first few days.³ During recovery, medical staff will track the baby’s heart rate, blood oxygen levels, breathing and other vital functions to make sure they are recovering properly. As recovery continues, babies are moved to a regular ward where they can be monitored under less intensive supervision. After surgery, common complications which might arise include:⁷

• Breathing difficulties
• Low heart output
• Irregular heart rhythms
• Blood loss
• Seizures

Some patients may need more treatments or surgery to address issues such as excess bleeding or fluid buildup in the lungs⁷.

Re-interventions & long-term prognosis

With timely repair surgery and treatments, most babies with TA grow up to live well into adulthood. With repair surgery, the survival rate for individuals with TA greatly increases from 20% at one year to 80% at 20 years. However, ongoing medical care is essential for individuals with TA to manage any potential challenges. For most babies with TA, further procedures are typically necessary after initial surgery.² Throughout early childhood, treatments such as stenting or dilating the pulmonary arteries may be needed to address narrowing of the vessels (stenosis) or repair of the artificial conduit as the heart grows.

By the 10th year following the original repair surgery, over 75% of patients require further re-intervention, including heart valve repairs, replacements or total blood vessel reconstruction.⁴ The frequency and type of operation required usually depend on the individual’s condition, though surgical intervention is usually required at least 2 - 3 times in childhood. For adults who had TA as babies, it is common for them to undergo cardiac catheterisation, a procedure where a probe is inserted into a blood vessel to assess heart health and function.

Management and follow-up care after TA repair

The vast majority of people who undergo repair surgery for TA as babies go on to active and fulfilling lifestyles. However, individuals who had TA should closely monitor their cardiac health and seek frequent medical advice to manage any potential issues. Adults who have undergone TA repair surgery as babies should consult a cardiologist who specialises in congenital heart conditions to monitor their heart health and detect any future complications.⁸ 

Heart function, exercise & lifestyle

Over time, the heart’s ability to pump blood might become weaker, requiring medication to help the heart beat more efficiently and control blood pressure. Some people may also develop arrhythmias, a condition where their heart doesn’t beat in a regular rhythm, which can lead to nausea and fainting, and may require additional treatment to manage.²

Maintaining an active lifestyle is critical after TA repair surgery to support heart health. However, individuals should exercise with caution to avoid overexerting themselves.⁸ Some people may need to avoid intense sports, while others may participate in moderate exercise. Patients who have had repair surgery during childhood may develop high blood pressure in the lungs (pulmonary hypertension), leading to shortness of breath, reduced ability to exercise, and nausea during intense physical activity. Individuals with TA should consult a cardiologist who can offer more specialised advice regarding healthy levels of exercise.⁹

Endocarditis

People who have previously suffered from TA have an increased chance of developing endocarditis, a rare infection that causes inflammation of the heart. To reduce chances of infection, maintaining good oral health is essential, and some doctors or dentists might recommend taking antibiotics before any procedures.⁹

Pregnancy and family planning

Individuals who have undergone TA repair surgery can often have successful pregnancies. However, those with significant heart issues in adulthood might face higher risks of health complications during pregnancy due to the increased strain on the heart. Because of this increased risk, it’s important for people who have had TA treatment to consult a congenital heart disease cardiologist before pregnancy to discuss their options.

Summary

Truncus arteriosus (TA) is a rare congenital heart defect which occurs when the heart develops with a single large blood vessel rather than two. Serious health complications can result from this condition, such as the body receiving insufficient oxygen and excessive blood flow to the lungs. For successful treatment and survival, early diagnosis before or after birth is extremely important. To fix the heart defects, surgery is performed to repair the defective blood vessels and restore blood flow throughout the body. Although most babies who have undergone TA repair treatment live to adulthood, they still need constant medical attention since they may need re-intervention to treat complications, such as restricted blood vessels or heart valve problems, as they grow older. Maintaining an active lifestyle, monitoring heart health, and attending regular check-ups with specialist cardiologists will help patients maintain normal lives after treatment. Many people who have undergone TA treatment can lead full lives with proper monitoring and care. However, they may experience additional complications, including pulmonary hypertension, cardiac rhythm issues, or an elevated risk of infections like endocarditis. Maintaining general health requires regular exercise, proper oral hygiene, and specialist medical advice.