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Patent ductus arteriosus (PDA)

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01

How blood flows

Patent ductus arteriosus (PDA)

The same region in both views. The usual view is a comparison, not a treatment result.

Follow the connections

PDA · a vessel between the arteries

PDA · a vessel between the arteriesSimplified isolated defect after birth, showing the common left-to-right pattern after lung resistance falls. Flow amount and direction vary with opening size, pressures, lung resistance and other anatomy; newborn transition and reversed shunts are not shown. Colours show relative oxygen content, not measured saturation. Structural focus: Aorta, Pulmonary artery, Open duct. Arrows show direction. This diagram does not measure blood flow, oxygen levels or severity. BodyBodyRight atriumRARight ventricleRVPulmonary arteryPALungsLungsLeft atriumLALeft ventricleLVAortaAortaOpen duct
  • Less oxygen
  • Mixed blood
  • More oxygen
RA Right atriumRV Right ventriclePA Pulmonary arteryLA Left atriumLV Left ventricle

Step 1 of 3

A vessel stays open between two arteries

The ductus arteriosus is a vessel joining the aorta and pulmonary artery (PA). It is normally open before birth and usually closes after birth. Here it remains open.

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 isolated defect after birth, showing the common left-to-right pattern after lung resistance falls. Flow amount and direction vary with opening size, pressures, lung resistance and other anatomy; newborn transition and reversed shunts are not shown. Colours show relative oxygen content, not measured saturation.

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 isolated defect after birth, showing the common left-to-right pattern after lung resistance falls. Flow amount and direction vary with opening size, pressures, lung resistance and other anatomy; newborn transition and reversed shunts are not shown. Colours show relative oxygen content, not measured saturation.

Original Heart Up Close connection map · Source check: 26 October 2026 · Independent clinical review pending.

Patent ductus arteriosus (PDA)

  1. A vessel stays open between two arteries. The ductus arteriosus is a vessel joining the aorta and pulmonary artery (PA). It is normally open before birth and usually closes after birth. Here it remains open.
  2. Some aortic blood enters the PA. In this common postnatal pattern, some oxygen-rich blood flows from the aorta through the open duct into the pulmonary artery. Blood can still continue from the aorta to the body.
  3. The extra blood makes another lung circuit. Blood entering the PA goes to the lungs, returns to LA, passes through LV and reaches the aorta again. The size of this extra circuit varies.

Simplified isolated defect after birth, showing the common left-to-right pattern after lung resistance falls. Flow amount and direction vary with opening size, pressures, lung resistance and other anatomy; newborn transition and reversed shunts are not shown. Colours show relative oxygen content, not measured saturation.

02

Diagnosis and care

Diagnosis and tests

PDA is more common in babies born early. A small PDA may cause no noticeable symptoms. Extra flow through a larger PDA can contribute to fast breathing, tiring during feeds or slow weight gain. A doctor may hear a murmur. In premature babies, the team considers other reasons for breathing or feeding difficulties too.

An echocardiogram, or echo, is an ultrasound scan that shows the open duct, its size and direction of blood flow. The team assesses its effect alongside breathing, feeding and growth. Other tests are used if needed. An open duct is expected before birth, so PDA is assessed after birth.

Care and follow-up

Not every PDA needs immediate treatment. The team may monitor it and repeat the echo. If closure is needed, options include medicines in some premature babies, a device delivered through a thin tube called a catheter, or surgery. The choice depends on your child’s age, health and the duct’s size and shape.

Some other heart conditions rely on the duct to supply blood to the lungs or body. In those cases, doctors may deliberately keep it open and the treatment plan is different. After closure, follow-up checks the result and your child’s recovery.

Daily life

Ask which changes in breathing or feeding should prompt a call, and who to contact. Before discharge, confirm when the next echo is due and which team will follow your child.

03

Questions to ask

Save the questions you want to take to your next appointment. You can edit them in your Journal.

  • How much extra blood is passing through the open duct, and what does that mean for our child’s heart and lungs?
  • Is the PDA affecting our child’s breathing, feeding or growth, and what changes should we watch for?
  • Why do you recommend monitoring or closing the duct now, and what would make that plan change?
  • Does our child have another heart difference that means the duct needs to stay open for now?
  • When will the next heart scan be, and who should we contact if we are worried before then?
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Sources and review

Sources checked 13 October 2026. Independent clinical review pending.

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