---
title: Truncus arteriosus
description: What truncus arteriosus is, why this defect is dangerous for a newborn, how it is found, how the operation is done and why lifelong follow-up is needed afterwards.
type: disease
aliases:
  - Persistent truncus arteriosus
  - Common arterial trunk
  - Truncus
sources:
  - tier: guideline
    org: minzdrav-rf
    title: Общий артериальный ствол
    year: 2025
    url: https://cr.minzdrav.gov.ru/view-cr/737_2
  - tier: guideline
    org: esc
    title: 2020 ESC Guidelines for the management of adult congenital heart disease
    year: 2020
    doi: 10.1093/eurheartj/ehaa554
    url: https://doi.org/10.1093/eurheartj/ehaa554
  - tier: reference
    org: msd-manuals
    title: Persistent Truncus Arteriosus
    year: 2023
    url: https://www.msdmanuals.com/professional/pediatrics/congenital-cardiovascular-anomalies/persistent-truncus-arteriosus
  - tier: reference
    org: msd-manuals
    title: Persistent Truncus Arteriosus (MSD Manual Consumer Version)
    year: 2025
    url: https://www.msdmanuals.com/home/children-s-health-issues/birth-defects-of-the-heart/persistent-truncus-arteriosus
  - tier: reference
    org: msd-manuals
    title: Overview of Heart Defects (MSD Manual Consumer Version)
    year: 2026
    url: https://www.msdmanuals.com/home/children-s-health-issues/birth-defects-of-the-heart/overview-of-heart-defects
sources_checked: 2026-10-13
review: null
---

Truncus arteriosus is a congenital heart defect in which a single large vessel leaves the heart instead of two separate ones, the <Structure id="aorta">aorta</Structure> and the <Structure id="pulmonary-trunk">pulmonary artery</Structure>.<Cite n={[1, 4]} /> This vessel has one valve, the truncal valve, instead of separate aortic and pulmonary valves, and through it blood flows to the body, to the heart itself through the coronary arteries, and to the lungs.<Cite n={[1, 4]} /> The trunk sits above a large defect in the <Structure id="interventricular-septum">interventricular septum</Structure>, so both ventricles pump blood into it.<Cite n={[3, 4]} />

It is a critical defect of the newborn period.<Cite n={1} />

<Diagram name="truncus-arteriosus">
  <p slot="normal">
    Normally blood goes from the right ventricle into the pulmonary artery and on to the lungs, and
    from the left ventricle into the aorta and on to the body.<Cite n={5} /> Each of the two vessels
    has its own valve.<Cite n={4} />
  </p>
  <p slot="disease">
    The diagram shows one of the variants of the defect (type I): a single common trunk with one
    valve leaves the heart above a ventricular septal defect, and a pulmonary artery leaves the
    trunk and divides into right and left branches.<Cite n={[1, 3]} /> Blood from both ventricles
    mixes in the trunk and goes both to the body and to the lungs.<Cite n={4} /> As a result, the
    lungs are flooded with blood.<Cite n={[1, 3]} />
  </p>
</Diagram>

## Why it happens

<Patient>

In the unborn baby, a single tube, the arterial trunk, first leaves the heart. Normally it divides into two vessels: the pulmonary artery and the aorta. In this defect the trunk does not divide.<Cite n={4} /> The heart forms in the first trimester of pregnancy, and that is when problems with its development arise.<Cite n={1} />

The exact cause of the defect is unknown, but risk factors are known; a serious one is diabetes in the mother.<Cite n={1} /> The defect often occurs together with 22q11.2 deletion syndrome (DiGeorge syndrome); other chromosomal conditions, trisomy 18 and trisomy 21, also occur.<Cite n={[1, 3]} />

Oxygen-rich and oxygen-poor blood mix in the trunk, and this mixture goes to the body, to the heart and to the lungs.<Cite n={[3, 4]} /> Right after birth the pressure in the pulmonary arteries becomes the same as in the trunk, and the lungs are flooded with blood.<Cite n={1} /> This leads to [heart failure](../heart-failure/).<Cite n={3} />

The constant flooding damages the blood vessels of the lungs, and [pulmonary hypertension](../pulmonary-hypertension/) develops. With this defect it develops very quickly, usually within a few months.<Cite n={[1, 5]} /> Without surgery, [Eisenmenger syndrome](../eisenmenger-syndrome/) then follows: the changes in the lungs become so severe that the shunt of blood reverses direction.<Cite n={[1, 5]} /> The defect itself does not go away.<Cite n={1} />

</Patient>

<Student>

According to the Russian Ministry of Health guideline, truncus arteriosus is a defect in which a single great vessel arises from the base of the heart and, through a single undivided semilunar truncal valve, supplies the coronary, systemic and pulmonary circulations; the pulmonary artery (PA) branches arise from the ascending part of the common vessel below the origin of the brachiocephalic arteries.<Cite n={1} /> The trunk overlies a large malalignment-type [ventricular septal defect](../ventricular-septal-defect/) (VSD).<Cite n={3} /> Blood from both ventricles is shunted through the VSD into the common vessel and mixes there; systolic pressure in the ventricles, the truncus and the PA branches is equal immediately after birth, which leads to marked overcirculation of the pulmonary vessels.<Cite n={1} /> The damaging effect of the large shunted volume on the pulmonary vessels contributes to the development of pulmonary hypertension (PH).<Cite n={1} />

Collett–Edwards classification: type I, a PA segment arises from the trunk and gives rise to the branches; type II, the PA branches arise close to each other from the posterior wall of the trunk; type III, the branches arise at a distance from each other from the lateral walls.<Cite n={[1, 3]} /> The former type IV is now classed as [tetralogy of Fallot](../tetralogy-of-fallot/) with pulmonary atresia.<Cite n={3} /> The Van Praagh classification distinguishes type A (with a VSD) and the very rare type B (without a VSD); type A4 has an interrupted aortic arch or coarctation.<Cite n={3} />

The truncal valve may have from two to six leaflets<Cite n={1} /> and may be stenotic, regurgitant or both.<Cite n={3} /> Association with an interrupted aortic arch or coarctation of the aorta is typical; a right aortic arch and coronary artery anomalies may occur, and the variant with an interrupted arch is regarded as a severe form.<Cite n={[1, 3]} />

Data on frequency differ. According to the Russian Ministry of Health guideline, truncus arteriosus accounts for 0.5–0.8% (or less) to 1.7% of congenital heart defects<Cite n={1} />; according to the MSD Manual for professionals, about 1% of congenital heart anomalies and 4% of critical congenital heart defects.<Cite n={3} /> Estimates of the association with 22q11.2 deletion syndrome also differ: according to the Russian Ministry of Health guideline, it is present in 70% of cases<Cite n={1} />; according to the MSD Manual for professionals, in about 35% of patients.<Cite n={3} />

If a child survives the first months without surgery, PH develops in all of them; truncus arteriosus is characterised by rapid, malignant development of PH and Eisenmenger syndrome.<Cite n={1} />

</Student>

<HeartModel highlight={['interventricular-septum', 'aorta', 'pulmonary-trunk']} />

The 3D model shows a normal heart.

## Symptoms

<Patient>

In the first weeks of life the baby usually develops mild cyanosis (a bluish tinge to the skin) and signs of heart failure: breathlessness, fast breathing, poor feeding and sweating.<Cite n={4} /> Breathlessness may occur even at rest and gets worse during feeds; the baby gains weight slowly and often has respiratory infections.<Cite n={1} /> Heart failure develops within a few days to a few weeks after birth.<Cite n={1} />

The blueness may be noticeable right after birth or appear later, and sometimes it is slight or absent altogether.<Cite n={1} />

A deceptive improvement is dangerous. As the pressure in the lung vessels rises, the baby may get ill less often and seem better, but this improvement is false, and the time for surgery may be lost.<Cite n={1} />

</Patient>

<Student>

Physical examination may detect a hyperdynamic precordium, increased pulse pressure with bounding pulses, a loud single second heart sound (S2) and an ejection sound (click).<Cite n={3} /> A grade 2–4/6 systolic murmur is heard along the left sternal border; with increased pulmonary blood flow there may be a mid-diastolic murmur at the apex, and with truncal valve regurgitation a high-pitched decrescendo diastolic murmur.<Cite n={3} />

According to the Russian Ministry of Health guideline, anomalies of other organs and systems are found in 43–48% of cases.<Cite n={1} />

</Student>

## How it is diagnosed

<Patient>

The defect can be found before birth: the Russian Ministry of Health guideline provides for an ultrasound scan of the baby's heart in the womb for this.<Cite n={1} /> After birth, a doctor may suspect the defect from a characteristic heart murmur and strong, "bounding" pulses.<Cite n={4} /> But an exact diagnosis cannot be made from examination and listening to the heart alone.<Cite n={1} />

The main test is a heart ultrasound (echocardiography) with Doppler: it shows the single vessel leaving the heart, the type of defect, how the truncal valve works and the direction of the blood shunt.<Cite n={[1, 3]} /> In newborns this test may be enough to plan the operation.<Cite n={1} />

An ECG and a chest X-ray are also done: the X-ray shows an enlarged heart and increased lung markings.<Cite n={[1, 3]} /> CT, MRI or cardiac catheterisation are used when the anatomy needs to be clarified before surgery.<Cite n={[1, 3]} /> If a child is older than 6 months and has not yet had surgery, the resistance of the lung vessels is measured through a catheter to find out whether the operation can be done.<Cite n={1} />

If DiGeorge syndrome is suspected, the levels of calcium and parathyroid hormone in the blood are checked, as well as the chromosome set (karyotype).<Cite n={1} />

</Patient>

<Student>

The diagnosis is suspected clinically, supported by chest X-ray and ECG, and established by two-dimensional echocardiography with colour flow Doppler.<Cite n={3} /> The echocardiographic sign of truncus arteriosus is a single vessel arising from the base of the heart, seen from the subcostal view.<Cite n={1} /> The Russian Ministry of Health guideline recommends contrast-enhanced cardiac CT for all patients with truncus arteriosus when surgery is being planned, to refine the echocardiographic findings.<Cite n={1} /> Catheterisation is sometimes needed to clarify associated anomalies, but MRI or CT angiography may replace it.<Cite n={3} />

The ECG commonly shows combined ventricular hypertrophy; with marked pulmonary overcirculation there may be signs of left atrial enlargement.<Cite n={3} /> The chest X-ray shows varying degrees of cardiomegaly with increased pulmonary vascular markings, a right aortic arch (in about 30%, according to the MSD Manual for professionals) and relatively high position of the pulmonary arteries.<Cite n={3} />

</Student>

## How it is treated

<Patient>

The defect itself is an indication for surgery, as long as the child can still be operated on.<Cite n={1} /> Heart failure medicines ease breathing and help stabilise the baby's condition until the operation, but they do not correct the defect itself.<Cite n={[1, 4]} />

Sources give different timing for the operation. The Russian Ministry of Health guideline: at 3–6 weeks of age in stable babies, and earlier if heart failure does not respond to medicines.<Cite n={1} /> The MSD Manual for professionals: during the newborn period<Cite n={3} />, and the consumer version of the MSD Manual: usually before the age of 1–2 months.<Cite n={4} />

It is open-heart surgery using a heart-lung machine.<Cite n={1} /> The surgeon closes the septal defect with a patch so that the left ventricle pumps blood into the former common trunk, which now works as the aorta.<Cite n={[3, 4]} /> The pulmonary arteries are separated from the trunk and connected to the right ventricle, most often with a tube (conduit), sometimes using the child's own tissue.<Cite n={[1, 3, 4]} /> The heart surgeon chooses the type of operation according to the anatomy of the defect.<Cite n={1} /> If the truncal valve leaks badly, it is repaired during the same operation.<Cite n={1} />

A conduit does not grow with the child: over time it becomes too small and has to be replaced during childhood; usually one or more repeat procedures are needed.<Cite n={[3, 4]} /> In addition, the conduit may narrow or leak, and [infective endocarditis](../infective-endocarditis/) may develop in it.<Cite n={2} /> A repeat procedure may be an operation or a procedure through a catheter: widening with a balloon or placing a stent or a valve.<Cite n={[1, 2]} /> Whether endocarditis prevention is needed before dental treatment is for the doctor to say.<Cite n={[1, 4]} />

Other problems are possible after the operation: a residual septal defect, persistent pulmonary hypertension, leakage of the aortic (former truncal) valve, narrowing of the pulmonary artery branches, and heart rhythm and conduction problems.<Cite n={[1, 3]} /> That is why lifelong follow-up by a cardiologist is needed.<Cite n={[1, 2]} />

</Patient>

<Student>

According to the Russian Ministry of Health guideline, repair of isolated truncus arteriosus has four stages: separation of the truncus and the PA branches, restoration of aortic continuity, VSD closure and creation of an outflow from the right ventricle to the pulmonary arteries using the patient's own tissue or conduits.<Cite n={1} /> When surgery with cardiopulmonary bypass carries excessive risk (low body weight, prematurity, complex anatomy of associated defects), staged palliation or a hybrid approach is considered.<Cite n={1} /> Surgical repair is not recommended in Eisenmenger syndrome and severe PH with exercise desaturation.<Cite n={1} />

The connection between the right ventricle and the PA confluence is usually created with a valved or non-valved conduit; some centres use a conduit-free technique in which the left atrial appendage forms the posterior wall of the outflow tract and a patch forms the anterior wall.<Cite n={3} /> When the outflow tract contains the patient's own tissue, it can grow with the child.<Cite n={3} /> According to the Russian Ministry of Health guideline, the high rate of reintervention after complete repair of truncus arteriosus is due to the original anatomy of the defect and the need for conduits.<Cite n={1} />

The ESC classes truncus arteriosus, repaired or unrepaired, as congenital heart disease of severe complexity, its highest category.<Cite n={2} /> There is no ideal conduit, and limited durability means early reoperation; conduit dysfunction may present with exertional dyspnoea, palpitations, syncope and sudden cardiac death.<Cite n={2} /> Balloon dilatation and stenting have been reported to be safe and to extend the lifespan of failing conduits, and percutaneous pulmonary valve implantation has become the treatment of choice for valve dysfunction when technically feasible.<Cite n={2} /> Branch PA stenosis is a common sequela of surgery and is often treated with transcatheter balloon dilatation with or without stent placement.<Cite n={3} /> After repair of truncus arteriosus, the risk of complete atrioventricular block needs particular attention.<Cite n={1} />

Follow-up according to the Russian Ministry of Health guideline: visits to a paediatric cardiologist or cardiologist 1, 3, 6 and 12 months after surgery, then at intervals of 3–36 months; follow-up includes ECG and echocardiography.<Cite n={1} /> For adults with a conduit, the ESC recommends follow-up in a specialised adult congenital heart disease centre at least once a year.<Cite n={2} />

</Student>

## When to call an ambulance

Truncus arteriosus is a critical defect of the newborn period.<Cite n={1} /> Heart failure or cyanosis in the first week of life is a medical emergency.<Cite n={5} />

Call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK) if a baby's lips or skin turn blue, if the baby breathes fast and with effort or grunts while breathing, struggles for breath during feeds, feeds poorly, sweats heavily while feeding or has become unusually irritable.<Cite n={5} /> Even if there are no acute signs, if a baby with this defect is not getting better on treatment, the decision about surgery must not be put off: the time for it may be lost.<Cite n={1} />

After the operation, worsening heart failure, heart rhythm problems or infective endocarditis are reasons for emergency admission to hospital.<Cite n={1} /> In an adult who has had surgery for this defect, conduit dysfunction may show up as fainting or an attack of palpitations. For fainting or a prolonged attack of palpitations, call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK).<Cite n={2} />

<Quiz />