Truncus arteriosus is a rare congenital heart defect in which a single large blood vessel exits the heart instead of the usual two, the aorta and the pulmonary artery. Babies born with this condition have mixed oxygen-rich and oxygen-poor blood flowing to the body and lungs simultaneously, which leads to heart failure without surgical correction. The defect accounts for roughly 1 to 3 percent of all congenital heart disease, and before surgical techniques were developed in the 1960s and 1970s, most affected infants died within the first months of life. Today, repair in the newborn period produces good survival, though the lifelong picture involves multiple follow-up procedures as the child grows.
How the Defect Forms
During normal fetal development, a single outflow vessel from the early heart is supposed to divide into the aorta (which carries blood to the body) and the pulmonary artery (which carries blood to the lungs). In truncus arteriosus, that division never happens. The baby is born with one common “trunk” sitting atop both the right and left ventricles, separated from them by a single valve called the truncal valve. Almost always, there is also a large hole between the two ventricles.
Inside the womb, this arrangement causes fewer problems than you might expect. The resistance in the fetal lung vessels is naturally high, so most blood is shunted to the body and only moderate mixing occurs, producing mild cyanosis. The trouble starts after birth. As the newborn’s lung resistance drops over the first days and weeks of life, blood rushes preferentially into the lungs. That overcirculation floods the lungs and forces the heart to work much harder. The result is congestive heart failure. If left untreated, the persistent overload on the lung vessels eventually causes irreversible damage, a condition sometimes called Eisenmenger syndrome, at which point the child becomes deeply cyanotic and surgical repair may no longer be feasible.1ResearchGate / Asian Basic and Applied Research Journal. Truncus Arteriosus: Pathophysiology, Investigations, and Treatment – Section: Pathophysiology
Symptoms in the Newborn
Signs typically appear within the first days to weeks of life, depending on how quickly the lung resistance falls and how much the truncal valve leaks. The hallmark is a combination of mild cyanosis, meaning a subtle blue or dusky tint to the skin, lips, and nail beds, alongside signs of heart failure: fast breathing, poor feeding, sweating during feeds, and failure to gain weight. Congestive heart failure and mild cyanosis are the usual early presentation.2Karger. Early Neonatal Cyanosis as a Presentation of a Rare Cardiac Anomaly: Truncus Arteriosus Type IV
Some babies have additional complications that make the picture more severe. About half of patients have some degree of truncal valve regurgitation, meaning blood leaks backward through the valve with each heartbeat, which worsens the heart failure. In a smaller percentage, structural problems with the aortic arch, such as a narrowing or interruption, can cause cardiovascular collapse and shock if not identified quickly.2Karger. Early Neonatal Cyanosis as a Presentation of a Rare Cardiac Anomaly: Truncus Arteriosus Type IV One study of neonates with truncus arteriosus combined with an interrupted aortic arch found that truncal valve stenosis was present in about 12 percent and regurgitation in about 22 percent of that group, illustrating how variable the anatomy can be from one baby to the next.3PubMed. Truncus arteriosus associated with interrupted aortic arch in 50 neonates: a Congenital Heart Surgeons Society study
How It Is Diagnosed
Echocardiography, the ultrasound-based imaging of the heart, is the primary tool. It can correctly establish the structural diagnosis in infants without surgery, showing the single outflow vessel, the ventricular septal defect, and the way the pulmonary arteries branch off.4The American Journal of Cardiology. Two-dimensional echocardiographic prospective diagnosis of common truncus arteriosus in infants Cardiac catheterization and angiography are sometimes still needed, particularly to measure pressures in the pulmonary arteries and assess how much irreversible lung disease may already be present. In practice, many centers now rely heavily on echocardiography supplemented by CT angiography, reserving catheterization for specific hemodynamic questions.
Prenatal diagnosis is also possible. Fetal echocardiography can pick up the abnormal outflow tract before birth, which allows families and medical teams to plan delivery at a center equipped for immediate cardiac surgery. One study examining the impact of prenatal diagnosis found that prenatally diagnosed neonates did undergo repair at a younger age than those diagnosed after birth. However, prenatal diagnosis did not translate into shorter hospital stays, and in that series the prenatally diagnosed group actually had higher death rates before and after surgery, likely because prenatal detection tends to pick up the more complex cases.5PubMed Central. Truncus Arteriosus: Diagnostic Accuracy, Outcomes, and Impact of Prenatal Diagnosis That finding does not mean early detection is unhelpful. Rather, it reflects the fact that fetuses whose anatomy is abnormal enough to flag on ultrasound tend to have more severe forms of the defect.
Genetic Links and Associated Conditions
Truncus arteriosus is not always an isolated heart problem. A significant minority of babies with this defect carry a microdeletion on chromosome 22, a genetic change associated with DiGeorge syndrome (also known as 22q11.2 deletion syndrome). In one series of 15 consecutive patients checked for this deletion, five had it, a rate of about one in three.6PubMed. Truncus arteriosus communis associated with chromosome 22q11 deletion DiGeorge syndrome can bring along immune deficiency, low calcium levels, feeding difficulties, and developmental delays, all of which matter for surgical planning and long-term care. For that reason, genetic testing is standard practice for any baby diagnosed with truncus arteriosus.
The defect can also appear alongside an interrupted aortic arch, a condition in which a segment of the aorta is simply missing. About 11 percent of neonates with an interrupted aortic arch in one large multi-center registry also had truncus arteriosus.3PubMed. Truncus arteriosus associated with interrupted aortic arch in 50 neonates: a Congenital Heart Surgeons Society study Repairing both problems at once adds complexity to the surgery but is generally the approach taken today.
Why Early Repair Matters
The central urgency with truncus arteriosus is the clock ticking on the lung vessels. As pulmonary resistance continues to fall after birth, overcirculation worsens, and the window for safe repair narrows. The consensus across major centers is that any neonate showing signs of overcirculation should be operated on as soon as possible.7The Journal of Thoracic and Cardiovascular Surgery. Truncus arteriosus repair: A 40-year multicenter perspective In practice, most repairs are done within the first weeks of life.
Delaying surgery significantly raises the risk of a dangerous postoperative complication: pulmonary hypertensive crisis. In a study of patients whose repair was delayed beyond one month of age, pulmonary hypertensive crisis occurred in about 22 percent of cases.8PubMed Central. Outcomes and occurrence of post-operative pulmonary hypertension crisis after late referral truncus arteriosus repair During such a crisis, the blood vessels in the lungs suddenly constrict, making it nearly impossible for the right side of the heart to push blood through. In severe cases, emergency mechanical support using a heart-lung machine placed through vessels in the neck has been used successfully to stabilize patients.9European Journal of Cardio-Thoracic Surgery. Salvage of postoperative pulmonary hypertensive crisis using ECMO via cervical cannulation in a case of truncus arteriosus
When repair is performed in the neonatal period, even in patients with major associated abnormalities, survival is excellent.10PubMed. Neonatal repair of truncus arteriosus: continuing improvement in outcomes
What the Surgery Involves
The operation has three main goals: close the hole between the ventricles, separate the pulmonary arteries from the common trunk, and create a new connection from the right ventricle to those detached pulmonary arteries. That last step is the most technically demanding part, and it is where much of the surgical innovation over the decades has focused.
Surgeons use several methods to build the right ventricular outflow tract. The most common approach involves placing a conduit, essentially a tube with a valve inside it, between the right ventricle and the pulmonary arteries. Options for that conduit have evolved considerably. In one series of 51 patients, valved femoral vein homografts were used in about 57 percent of cases, pulmonary artery homografts in 22 percent, and aortic homografts in 14 percent, with a handful receiving valveless tube grafts or a bioconduit.11PubMed Central. Valved Femoral Vein Homografts as Right Ventricle to Pulmonary Artery Conduit for Repair of Truncus Arteriosus Another center reported using cryopreserved allograft valved conduits in 28 infants, various xenograft conduits in 10, and in 23 patients, a direct connection between the pulmonary arteries and the right ventricle was constructed without an external conduit at all.12European Journal of Cardio-Thoracic Surgery. Repair of truncus arteriosus: a considered approach to right ventricular outflow tract reconstruction
Some centers favor direct anastomosis, meaning the pulmonary artery is sewn straight onto an opening cut in the right ventricle, sometimes with a patch to bridge the gap. Others rely heavily on homografts (human donor tissue) or xenografts (animal-derived tissue). There is no single best method. The choice depends on the baby’s anatomy, the size of the pulmonary arteries, and the surgeon’s experience with a given technique.13The Journal of Thoracic and Cardiovascular Surgery. Truncus arteriosus repair: Influence of techniques of right ventricular outflow tract reconstruction
Dealing With a Leaky Truncal Valve
A separate surgical challenge is the truncal valve itself, which becomes the patient’s aortic valve after the pulmonary arteries are detached. In many patients, this valve has an abnormal number of leaflets, often four instead of the usual three, and it may leak significantly. Truncal valve regurgitation adds workload to an already-strained heart, so moderate or severe leaking often needs to be addressed at the time of the initial repair or later.
There is no single standard approach to fixing a leaky truncal valve. A combination of techniques is used, including stitching adjacent leaflets together, extending leaflets with patches, and reducing the valve ring to make it smaller. In one series, surgeons achieved a functional three-leaflet valve in 58 percent of patients, a four-leaflet configuration in 31 percent, and a two-leaflet setup in the remaining 11 percent.14European Journal of Cardio-Thoracic Surgery. Surgical repair of truncal valve regurgitation One center reported that converting a four-leaflet valve to a three-leaflet configuration by resecting one cusp and reducing the ring provided particularly durable results, with about 65 percent freedom from reoperation on the truncal valve at 15 years.15Operative Techniques in Thoracic and Cardiovascular Surgery. What Is Truncus Arteriosus? Symptoms and Surgical Repair A good valve repair can spare patients from needing a mechanical replacement, which would require lifelong blood thinners.
The Reality of Reoperations
Parents often hear that the initial repair “fixes” truncus arteriosus, but the more accurate picture is that it sets a child on a path of ongoing cardiac care. The conduit placed during the original surgery does not grow with the child, and all conduit types eventually develop obstruction or valve failure as the child outgrows them or the tissue degenerates. Reoperation to replace the conduit is not a complication of the first surgery; it is an expected part of the treatment plan.
A major 20-year follow-up study found that 107 out of the patients tracked underwent a total of 133 conduit reoperations. The median time to the first conduit replacement was about five and a half years, and the strongest predictor of needing earlier replacement was a smaller conduit at the initial repair.16PubMed. Long-term follow-up of truncus arteriosus repaired in infancy: a twenty-year experience A more recent study of 33 patients found a slightly shorter median time to reoperation of about 1.6 years, though this may reflect differences in patient anatomy and the types of conduits used. That study also found that the pattern of how the pulmonary arteries branch off from the trunk and the ratio of conduit size to pulmonary artery size were important factors.17PubMed. Conduit Size, Branch Pulmonary Artery Size, and Reoperation in Patients With Truncus Arteriosus
The good news is that options for managing failing conduits have expanded. In addition to open surgery to place a new conduit, catheter-based techniques now allow some patients to have a new valve placed inside the old conduit through a blood vessel in the leg, avoiding open-heart surgery entirely. Balloon dilation and stenting can also extend the life of a conduit before a full replacement is needed.18The Annals of Thoracic Surgery. Transventricular Pulmonary Valve Implantation in Corrected Truncus Arteriosus
The truncal valve itself is another source of long-term concern. In a study following 134 patients after initial repair, a quarter developed worsening truncal valve regurgitation to moderate or greater severity over time, with a larger valve root being the main predictor.19PubMed Central. Long-Term Fate of the Truncal Valve
Quality of Life After Repair
Most adults who underwent truncus arteriosus repair in childhood function well enough to live independently, work, and engage in physical activity, though their health-related quality of life is measurably lower than the general population in some areas. A study comparing adults with repaired truncus arteriosus to age-matched peers found that younger adults (18 to 24) scored lower than their peers in six of eight quality-of-life domains, while older adults (35 to 44) scored lower in four of eight domains. Interestingly, when researchers used a summary health-utility index, the overall scores between the two groups were not significantly different, suggesting that while specific limitations exist, the global sense of well-being is comparable.20PubMed. Long-term quality of life in adults following truncus arteriosus repair
The narrower gap in older adults may seem surprising, but it likely reflects two things: survivors who reach their 30s and 40s tend to be those with less severe residual disease, and people living with chronic conditions often adapt psychologically over time. Physical activity limitations and the psychological burden of repeated surgeries account for many of the lower domain scores, particularly in younger adults navigating school, careers, and identity.
Pregnancy After Truncus Arteriosus Repair
For women who have had truncus arteriosus repaired in childhood, pregnancy is possible but requires careful planning. The extra blood volume of pregnancy stresses the heart significantly, and a conduit that is already narrowing or a truncal valve that already leaks can worsen under that hemodynamic load. A case series of eight pregnancies in four women with repaired truncus arteriosus found that none of the women had adverse cardiac events during pregnancy, though two pregnancies in one woman were complicated by high blood pressure, and three pregnancies resulted in smaller-than-expected birth weights.21PubMed. Pregnancy in Women With Repaired Truncus Arteriosus: A Case Series
In rare cases, the hemodynamic changes of pregnancy can cause sudden deterioration in valve function. One report described an 18-year-old with repaired truncus arteriosus whose truncal valve regurgitation worsened dramatically during pregnancy, producing severe symptoms. She delivered a healthy baby, and her valve function recovered within two weeks after delivery.22PubMed. Severe pregnancy-induced deterioration of truncal valve regurgitation in an adolescent patient with repaired truncus arteriosus Cases like this underscore why preconception cardiac assessment and close monitoring throughout pregnancy are considered essential for these women.
How Surgical Repair Developed
Before the 1960s, truncus arteriosus was essentially untreatable, and most affected babies died within weeks to months from heart failure. The first successful repair with long-term survival was performed in 1963 by Herbert Sloan at the University of Michigan, using a tube without a valve to connect the right ventricle to the pulmonary arteries. In 1967, Rastelli and McGoon at the Mayo Clinic completed the first repair using a homograft conduit with a valve, establishing the template that would become standard. Through the 1970s and 1980s, smaller conduits designed for young infants, better preservation of donor tissue, and earlier surgical timing steadily pushed survival rates upward. By the early 1990s, some centers were performing primary repair in the first days of life with outstanding results.23PubMed. Personal glimpses into the evolution of truncus arteriosus repair
That timeline matters because it means the oldest adults living today with repaired truncus arteriosus had their operations using techniques and conduit materials that are now outdated. Their conduits have different longevity profiles and their surgical scars may present different challenges for reoperation compared with babies repaired today. The field continues to evolve, with catheter-delivered valves, tissue-engineered conduits, and improved valve-repair strategies all aiming to extend the intervals between surgeries and improve long-term heart function. For a defect that was uniformly fatal within living memory, the trajectory is remarkable.