Your child’s diagnosis
Truncus arteriosus
01
How blood flows
Truncus arteriosus
The same region in both views. The usual view is a comparison, not a treatment result.
Truncus arteriosus · one common outlet
- Less oxygen
- Mixed blood
- More oxygen
Step 1 of 3
A VSD beneath the outlet
An opening between the ventricles lies beneath the common arterial outlet.
How to read this map
Follow the arrows to see connections. This is a map, not the shape or position of a heart. Both sides work together; the story follows one part at a time. A crossing with a white gap is not a connection; a dot marks a junction. With story controls focused, use left/right arrows, Home or End.
Simplified connections before repair. Common valve function and pulmonary artery anatomy vary.
Colours describe this example: blue means less oxygen, red more oxygen, and purple mixing. Blood is always red in real life. Line widths and animation do not measure flow, pressure, oxygen saturation or severity.
Diagram sources and scope
Simplified connections before repair. Common valve function and pulmonary artery anatomy vary.
Original Heart Up Close connection map · Source check: 26 October 2026 · Independent clinical review pending.
Truncus arteriosus
- A VSD beneath the outlet. An opening between the ventricles lies beneath the common arterial outlet.
- One common valve and trunk. Both ventricles send blood through a common valve into one arterial trunk.
- The trunk branches to lungs and body. The trunk supplies both destinations. Flow is not necessarily equal; too much may reach the lungs.
Simplified connections before repair. Common valve function and pulmonary artery anatomy vary.
02
Diagnosis and care
Diagnosis and tests
Truncus may be seen on a pregnancy scan. After birth, breathing or feeding difficulties may lead to tests. A murmur, an extra sound during the heartbeat, may be heard. A baby may look blue or grey and gain weight slowly. Symptoms can change as blood flow adjusts after birth. The specialist looks at more than the baby’s appearance at one moment.
An echocardiogram, or echo, is an ultrasound scan of the heart. It shows the shared artery, branches to the lungs, opening and valve. Other tests may help plan surgery. The team may discuss genetic tests, which look for changes in the instructions that guide growth and development.
Truncus can occur with conditions such as 22q11 deletion syndrome, where a small piece of genetic material is missing. Ask what a test could explain and whether a specialist can discuss the results with you.
Care and follow-up
Repair usually takes place in infancy. The opening between the lower chambers is closed. This lets the left chamber supply the body through the shared artery, which becomes the aorta. A tube called a conduit connects the right chamber to the arteries supplying the lungs. The surgeon may also treat the truncal valve or other heart differences.
A conduit does not grow as a child does. It can become narrow or its valve can leak. Further procedures may be needed over time. The truncal valve and other repaired parts also need checks. The plan depends on where the lung branches leave the shared artery, how the valve works and other heart details.
Daily life
Ask the team to explain the conduit’s role and how it will be checked as your child grows. If the team suggests genetic testing, ask for time to discuss what the result might mean for your child and family.
03
Questions to ask
Save the questions you want to take to your next appointment. You can edit them in your Journal.
- Where do our child’s lung arteries branch from the shared artery, and how does that affect the repair plan?
- How well is the valve in the shared artery working, and will it need treatment as part of the repair?
- Which connecting tube, or conduit, do you recommend for our child, and why is it the best fit at this stage?
- Would a genetic assessment be helpful for our child, and what could the results mean for our family?
- How will you plan future procedures as our child grows, and what will regular checks help you decide?
Sources and review
Sources checked 9 October 2026. Independent clinical review pending.
- British Heart Foundation: Truncus arteriosus
Accessed 9 October 2026
- Children’s Heart Federation: Truncus Arteriosus Information Sheet
Accessed 9 October 2026