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# Truncus arteriosus, TAPVR and tricuspid atresia

Three rare birth heart defects that mix blue and red blood and turn a baby blue. All need surgery, often in the first weeks of life.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Pulmonary trunk](https://durgical.com/en/anatomy/pulmonary-trunk/)
- [Pulmonary veins](https://durgical.com/en/anatomy/pulmonary-veins/)
- [Tricuspid septal leaflet](https://durgical.com/en/anatomy/septal-leaflet-of-right-atrioventricular-valve/)
- [Ascending aorta](https://durgical.com/en/anatomy/ascending-aorta/)
- [Interventricular septum](https://durgical.com/en/anatomy/interventricular-septum/)
- [Interatrial septum](https://durgical.com/en/anatomy/interatrial-septum/)
- [Right atrium](https://durgical.com/en/anatomy/right-atrium/)
- [Left atrium](https://durgical.com/en/anatomy/left-atrium/)
- [Right ventricle](https://durgical.com/en/anatomy/right-ventricle/)
- [Left ventricle](https://durgical.com/en/anatomy/left-ventricle/)
- [Pulmonary arteries](https://durgical.com/en/anatomy/right-pulmonary-artery/)
- [Coronary sinus](https://durgical.com/en/anatomy/coronary-sinus/)
- [Superior vena cava](https://durgical.com/en/anatomy/superior-vena-cava/)
- [Thymus](https://durgical.com/en/anatomy/thymus/)

## Why it happens

- [Fetal circulation and the transition at birth](https://durgical.com/en/physiology/fetal-circulation-and-the-transition-at-birth/)
- [Physiology of congenital shunts](https://durgical.com/en/physiology/physiology-of-congenital-shunts/)

## What it is

This page groups three less common cyanotic congenital heart defects (part of the classic «5 Ts» with tetralogy of Fallot and transposition). In truncus arteriosus a single great artery leaves the heart above a large ventricular septal defect and supplies the systemic, pulmonary and coronary circulations. In total anomalous pulmonary venous return (TAPVR) all [pulmonary veins](https://durgical.com/en/anatomy/pulmonary-veins/) drain into the systemic venous circulation instead of the left atrium. In tricuspid atresia there is no connection between the [right atrium](https://durgical.com/en/anatomy/right-atrium/) and the right ventricle, which is small.

## Who gets it

Each accounts for about 1–3% of congenital heart disease. Congenital heart disease affects close to 1 in 100 live births and, in Colombia and Latin America, is a leading cause of infant death from birth defects; outcomes depend on early detection and access to neonatal cardiac surgery, which is concentrated in large cities.

## Causes

- Truncus arteriosus: failure of the conotruncal (aorticopulmonary) septum to form, linked to abnormal neural crest migration; about a third have 22q11.2 deletion (DiGeorge syndrome)
- TAPVR: failure of the common pulmonary vein to join the left atrium, with persistence of embryonic connections to systemic veins
- Tricuspid atresia: failure of the right atrioventricular valve to develop, with an obligatory atrial septal defect and usually a ventricular septal defect
- Maternal diabetes and some genetic syndromes increase the overall risk of conotruncal defects

## Risk factors

- 22q11.2 deletion (truncus arteriosus)
- Maternal pregestational diabetes
- Family history of congenital heart disease
- Maternal exposures in pregnancy (for example retinoids, alcohol, rubella)

## Pathophysiology

All three cause mixing of systemic and pulmonary venous blood, hence cyanosis. In truncus arteriosus, pulmonary flow is unrestricted: as pulmonary resistance falls after birth, lung flow rises and heart failure develops, with only mild cyanosis; untreated, pulmonary vascular disease (Eisenmenger physiology) appears early. In TAPVR, survival depends on an atrial communication; if the anomalous drainage is obstructed (typical of infracardiac connections) pulmonary venous congestion and severe hypoxaemia occur at birth. In tricuspid atresia all systemic venous return crosses the atrial septum to the left heart; lung blood flow passes through the VSD or a patent ductus, so cyanosis depends on how restrictive these paths are.

## Classification

- Truncus arteriosus: types by origin of the [pulmonary arteries](https://durgical.com/en/anatomy/right-pulmonary-artery/) from the common trunk (Collett-Edwards or Van Praagh)
- TAPVR: supracardiac (most common), cardiac ([coronary sinus](https://durgical.com/en/anatomy/coronary-sinus/) or right atrium), infracardiac (often obstructed), mixed; obstructed vs unobstructed
- Tricuspid atresia: by relation of the great arteries (normally related or transposed) and by pulmonary blood flow (reduced or increased)

## Symptoms and signs

- Cyanosis in the newborn period, of variable severity
- Tachypnoea, poor feeding, sweating with feeds and poor weight gain (heart failure, especially truncus and unobstructed TAPVR)
- Severe respiratory distress and deep cyanosis within hours of birth (obstructed TAPVR)
- Bounding pulses and wide pulse pressure in truncus arteriosus
- Hypercyanotic spells in some infants with tricuspid atresia and restricted pulmonary flow

## Red flags

- Newborn with cyanosis not corrected by oxygen or failed pulse oximetry screening
- Severe hypoxaemia with pulmonary oedema on X-ray and a small heart (obstructed TAPVR: surgical emergency)
- Signs of shock or acidosis
- Hypocalcaemic seizures or immunodeficiency in an infant with truncus (22q11.2 deletion)

## Diagnosis

**Clinical**
Cyanosis that does not improve with 100% oxygen (failed hyperoxia test) points to a cardiac cause. Truncus: single loud S2, ejection click, systolic murmur and sometimes a diastolic murmur of truncal valve regurgitation. Tricuspid atresia: holosystolic VSD murmur with a single S2. TAPVR: may have few findings apart from cyanosis and tachypnoea.

**Tests**
Pulse oximetry screening and arterial blood gas. ECG: left [axis](https://durgical.com/en/anatomy/axis/) deviation with left ventricular dominance in a cyanotic infant suggests tricuspid atresia; right ventricular hypertrophy in TAPVR. In truncus, check calcium, lymphocyte count and genetic testing for 22q11.2 deletion.

**Imaging**
Echocardiography is diagnostic for all three; CT or MRI clarifies pulmonary venous anatomy in TAPVR. [Chest](https://durgical.com/en/anatomy/region/chest/) X-ray: «snowman» or «figure of eight» heart in older infants with supracardiac TAPVR; small heart with diffuse pulmonary oedema in obstructed TAPVR; increased lung markings in truncus; reduced markings in tricuspid atresia with restricted flow.

## Differential diagnosis

- Transposition of the great arteries and tetralogy of Fallot
- Hypoplastic left heart syndrome and Ebstein anomaly
- Persistent pulmonary hypertension of the newborn
- Neonatal respiratory distress syndrome and pneumonia (especially for obstructed TAPVR)
- Methaemoglobinaemia

## Goal of treatment

Stabilise oxygen delivery after birth, relieve obstruction urgently when present, and perform anatomical repair (truncus, TAPVR) or staged single-ventricle palliation (tricuspid atresia).

## Treatment

**Acute**
Prostaglandin E1 infusion when pulmonary blood flow is ductus-dependent (for example tricuspid atresia with pulmonary stenosis); ventilation, inotropes and correction of acidosis. Obstructed TAPVR needs emergency surgery rather than prostaglandin.

**Medical**
Diuretics and nutritional support for heart failure while awaiting surgery, especially in truncus arteriosus.

**Surgical**
TAPVR: reconnection of the common pulmonary venous confluence to the [left atrium](https://durgical.com/en/anatomy/left-atrium/) and closure of the atrial communication, urgently if obstructed.

**Surgical**
Truncus arteriosus: in the first weeks to months, closure of the VSD so the trunk becomes the aorta and a [right ventricle](https://durgical.com/en/anatomy/right-ventricle/) -to-pulmonary artery conduit; the conduit is replaced as the child grows.

**Surgical**
Tricuspid atresia: initial systemic-to-pulmonary shunt or pulmonary artery band as needed, then bidirectional Glenn and Fontan operations (single-ventricle pathway).

**Follow-up**
Nursing: continuous oximetry and cardiorespiratory monitoring, apnoea watch on prostaglandin, calcium checks and irradiated blood products when 22q11.2 deletion is suspected, feeding and weight; lifelong congenital cardiology follow-up.

## Complications

- Heart failure and early pulmonary vascular disease (truncus)
- Truncal valve regurgitation and conduit stenosis requiring reoperation
- Pulmonary vein stenosis after TAPVR repair
- Fontan complications after tricuspid atresia palliation (arrhythmias, thrombosis, protein-losing enteropathy, [liver](https://durgical.com/en/anatomy/liver/) disease)
- Neurodevelopmental delay; death if untreated

## Prognosis

Untreated, most infants with truncus arteriosus or obstructed TAPVR die in the first months of life. After timely repair, survival for TAPVR and truncus is good, although reinterventions are common. Tricuspid atresia relies on a palliative Fontan circulation with lifelong follow-up.

## Prevention

- Glucose control before and during pregnancy in women with diabetes; rubella immunity; avoid alcohol and teratogenic drugs
- Prenatal ultrasound with fetal echocardiography when indicated
- Universal newborn pulse oximetry screening

## Test yourself

Think of the answer, then tap the question to see it.

## Which genetic deletion is found in about a third of infants with truncus arteriosus?

22q11.2 deletion (DiGeorge syndrome).

## A cyanotic newborn has left axis deviation and left ventricular hypertrophy on ECG. What defect is suggested?

Tricuspid atresia.

## What chest X-ray sign is classic for supracardiac TAPVR?

The «snowman» or «figure of eight» heart.

## Which type of TAPVR is most often obstructed and is a surgical emergency?

Infracardiac TAPVR.

## What are the «5 Ts» of cyanotic congenital heart disease?

Truncus arteriosus, transposition of the great arteries, tricuspid atresia, tetralogy of Fallot and total anomalous pulmonary venous return.

[Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/truncus-arteriosus-tapvr-and-tricuspid-atresia/)

## Related conditions

- [Transposition of the great arteries](https://durgical.com/en/conditions/transposition-of-the-great-arteries/)
- [Tetralogy of Fallot](https://durgical.com/en/conditions/tetralogy-of-fallot/)
- [Hypoplastic left heart syndrome](https://durgical.com/en/conditions/hypoplastic-left-heart-syndrome/)
- [Ebstein anomaly](https://durgical.com/en/conditions/ebstein-anomaly/)
- [DiGeorge syndrome (22q11.2 deletion syndrome)](https://durgical.com/en/conditions/digeorge-syndrome/)
- [Ventricular septal defect](https://durgical.com/en/conditions/ventricular-septal-defect/)
- [Atrial septal defect](https://durgical.com/en/conditions/atrial-septal-defect/)
- [Patent ductus arteriosus](https://durgical.com/en/conditions/patent-ductus-arteriosus/)
- [Persistent pulmonary hypertension of the newborn](https://durgical.com/en/conditions/persistent-pulmonary-hypertension-of-the-newborn/)
- [Eisenmenger syndrome](https://durgical.com/en/conditions/eisenmenger-syndrome/)
- [Heart failure](https://durgical.com/en/conditions/heart-failure/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Truncus arteriosus](https://medlineplus.gov/ency/article/001111.htm) (MedlinePlus, US National Library of Medicine, 2026); [Tricuspid atresia](https://medlineplus.gov/ency/article/001110.htm) (MedlinePlus, US National Library of Medicine, 2026); [Total Anomalous Pulmonary Venous Return (TAPVR)](https://www.cdc.gov/heart-defects/about/tapvr.html) (Centers for Disease Control and Prevention (CDC), 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/conditions/truncus-arteriosus-tapvr-and-tricuspid-atresia/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/truncus-arteriosus-tapvr-and-tricuspid-atresia/