Embryology · Heart and vessels
Patent ductus arteriosus !
- Malformation
The vessel that links the pulmonary artery to the aorta in the fetus fails to close at birth, and blood flows from the aorta to the lungs.
Updated 2026-11-01
See it in 3D: Ligamentum arteriosum · Pulmonary trunk · Pulmonary arteries · Aortic arch · Thoracic aorta · Recurrent laryngeal nerves
What it is
The ductus arteriosus comes from the left sixth aortic arch and in the fetus diverts blood from the lungs to the aorta. At birth, rising oxygen and falling prostaglandins constrict it within hours to days; if it fails to close, an aorta-to-pulmonary shunt persists. It is acyanotic and very common in preterm infants.
Embryological cause
- The ductus persists because its muscular wall fails to constrict after birth.
- In preterm infants the wall is immature and responds poorly to oxygen; circulating prostaglandins stay high.
- In congenital rubella, first-trimester infection damages the ductal tissue.
- Chronic hypoxia at altitude weakens the stimulus for closure.
Markers
- Prostaglandin E2
- Oxygen
- Congenital rubella
How it presents
- Preterm infant: worsening respiratory distress, bounding pulses and a wide pulse pressure.
- Older child: continuous murmur, often without symptoms; large ducts cause heart failure.
- Untreated: pulmonary hypertension with shunt reversal and differential cyanosis (blue legs, pink hands).
- An open ductus is life-saving in transposition, hypoplastic left heart and pulmonary atresia.
Diagnosis
- Doppler echocardiography: aorta-to-pulmonary flow and duct size.
- Chest X-ray: left heart enlargement and increased vascular markings in large ducts.
Test yourself
Think of the answer, then tap the question to see it.
Which aortic arch does the ductus arteriosus come from?
The distal part of the left sixth aortic arch.
Which two signals normally close the ductus arteriosus at birth?
Rising oxygen tension and the fall in prostaglandin E2 (after loss of the placenta).
Which murmur is typical of a patent ductus arteriosus?
A continuous 'machinery' murmur below the left clavicle.
Which finding shows that a patent ductus has reversed its flow?
Differential cyanosis: blue feet with pink hands, as pulmonary blood enters the descending aorta.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
- Ligamentum arteriosum
- Pulmonary trunk
- Pulmonary arteries
- Aortic arch
- Thoracic aorta
- Recurrent laryngeal nerves
Related
- Aortic arch arteries and their derivatives
- Fetal circulation and the changes at birth
- Congenital rubella syndrome
- Coarctation of the aorta
- Transposition of the great arteries
- Hypoplastic left heart syndrome
Related conditions
- Patent ductus arteriosus
- Prematurity and its complications
- Neonatal respiratory distress syndrome (hyaline membrane disease)
- Congenital (TORCH) infections: syphilis, toxoplasmosis, CMV and Zika
- Pulmonary hypertension and cor pulmonale
Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given.
Sources: Langman's Medical Embryology, 13th ed., ch. 13: Cardiovascular System (Wolters Kluwer, 2015); Patent ductus arteriosus: MedlinePlus Medical Encyclopedia (National Library of Medicine (MedlinePlus), 2025).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.