The common arterial trunk is a rare congenital heart defect characterized by the presence of a single arterial vessel arising from the ventricles and giving rise to the coronary arteries, the aorta, and the pulmonary artery. Under normal conditions, the aorta and pulmonary trunk are distinct and arise from the left and right ventricles, respectively. In the common arterial trunk, however, the separation of the two circulatory circuits fails to occur, resulting in the mixing of oxygenated and deoxygenated blood and the systemic and pulmonary distribution of mixed blood.
This condition accounts for approximately 1–3% of all congenital heart defects and is frequently associated with other malformations, particularly with a ventricular septal defect (VSD), which is consistently present in the classic form. Early recognition and timely surgical correction are essential for neonatal survival.
The common arterial trunk is a critical condition, often lethal if untreated, due to excessive pulmonary perfusion, congestive heart failure, and the rapid development of irreversible pulmonary hypertension.
The common arterial trunk results from an embryological defect in the formation of the conotruncus, the embryonic structure from which the aortic and pulmonary bulbs originate. In normal embryogenesis, the conotruncus undergoes a process of spiral septation that leads to the separate formation of the aorta and pulmonary trunk. A failure in this process results in the persistence of a single arterial vessel receiving blood from both ventricles and supplying both the systemic and pulmonary circulations.
The definite etiological cause is genetic abnormalities affecting conotruncal heart development. In particular, a strong association has been documented with the 22q11.2 deletion, typical of velocardiofacial syndrome (DiGeorge syndrome), found in about 30–50% of patients. Other implicated genes include TBX1, CRKL, and VEGF, which regulate neural crest cell migration—critical for conotruncal septation.
Modifiable risk factors include environmental conditions interfering with cardiac embryogenesis during the early weeks of pregnancy. Specifically, pre-gestational maternal diabetes, alcohol consumption, use of anticonvulsants, and folate deficiency have been associated with an increased risk of conotruncal defects, including the common arterial trunk.
The primary pathophysiological consequence is the systemic and pulmonary perfusion with mixed blood, leading to reduced arterial oxygen saturation and a left-to-right shunt at the VSD level. The low resistance of the pulmonary circulation in the early neonatal period causes excessive pulmonary blood flow, resulting in vascular congestion, systemic hypoxia, and the rapid development of congestive heart failure.
Moreover, elevated pulmonary pressure exposes the capillaries to early structural damage, promoting the development of irreversible pulmonary hypertension (pulmonary obstructive vascular disease), which may contraindicate surgery if not performed within the first few months of life. Progressive dilation of the heart chambers in response to volume overload further contributes to the functional deterioration of the heart.
The common arterial trunk presents early after birth, with symptoms related to blood mixing and excessive pulmonary perfusion. Clinical manifestations are often evident within the first days or weeks of life and worsen as pulmonary vascular resistance physiologically decreases.
The neonatal history should investigate signs of early respiratory distress, feeding difficulties, sweating during feeding, and poor weight gain. A positive family history of congenital heart defects or the presence of dysmorphic features suggestive of genetic syndromes (such as DiGeorge syndrome) should raise clinical suspicion.
The most common signs and symptoms include:
In untreated neonates, progressive pulmonary congestion may evolve into severe respiratory distress and refractory heart failure, often within the first month of life.
The diagnosis of common arterial trunk is based on a combination of clinical findings, cardiac imaging, and genetic testing, and must be established promptly to plan early surgical intervention.
Transthoracic echocardiography is the reference test, allowing identification of:
In cases of complex anatomy or diagnostic uncertainty, cardiac computed tomography (multislice CT) or cardiac magnetic resonance imaging (MRI) are used to allow three-dimensional reconstruction of vascular structures and functional assessment of blood flow.
Angiography is now used almost exclusively for preoperative planning or when noninvasive imaging is inconclusive.
The electrocardiogram (ECG) may show signs of biventricular hypertrophy, while chest X-ray typically reveals cardiomegaly and increased pulmonary vascular markings.
Genetic screening for 22q11.2 deletion is recommended due to its high prevalence in affected patients. In the presence of syndromic phenotypes (such as cleft palate, hypocalcemia, or facial anomalies), the involvement of a genetic team is essential for a comprehensive syndromic diagnosis.
Common arterial trunk is a complex congenital heart defect that requires early surgical correction, typically within the first weeks of life, to prevent progressive hemodynamic deterioration and the development of irreversible pulmonary hypertension.
Initial medical management aims to stabilize the patient before surgery and includes:
The corrective surgical procedure involves:
Early intervention is critical to avoid irreversible pulmonary vascular damage and to reduce the risk of long-term complications. In rare, selected cases—such as complex anatomy or very low birth weight—a staged approach with initial palliation followed by definitive repair may be considered.
When treated appropriately during the neonatal period, the prognosis of common arterial trunk has significantly improved in recent decades, thanks to advances in surgery and neonatal intensive care. Long-term survival exceeds 85–90% in high-volume specialized centers.
However, long-term follow-up is essential, as:
Quality of life is generally good, but a dedicated and multidisciplinary cardiology follow-up program is necessary to monitor ventricular function, valve conditions, and the status of the pulmonary conduit.
Without surgical correction, common arterial trunk rapidly progresses to congestive heart failure and, most notably, to a condition of irreversible pulmonary hypertension (Eisenmenger syndrome), rendering the disease inoperable and severely compromised.
The main associated complications include:
Optimal management of common arterial trunk requires early diagnosis, prompt surgical treatment, and structured long-term follow-up in centers experienced with complex congenital heart diseases.