AKT · Child health/Congenital heart

Patent ductus arteriosus (PDA)

Persistence of the ductus arteriosus (aorta→pulmonary artery) after birth (acyanotic L→R shunt)

Overview

Failure of the ductus arteriosus (the fetal aorta-to-pulmonary-artery connection) to close after birth, leaving a left-to-right shunt. Commoner in preterm infants and congenital rubella. Classic CONTINUOUS 'machinery' murmur with a collapsing/bounding pulse. The management pearl is dual: in a preterm PDA, a PROSTAGLANDIN-INHIBITOR (ibuprofen/indometacin) CLOSES it — but in DUCT-DEPENDENT congenital heart disease, PROSTAGLANDIN (alprostadil) is given to KEEP it open.

Recognise

CONTINUOUS 'machinery' murmur (loudest beneath the left clavicle, throughout systole and diastole); bounding/collapsing pulses, wide pulse pressure
Preterm infant or congenital rubella; large PDA → heart failure, faltering growth, recurrent infections
Eisenmenger if a large untreated shunt

Red flags

Large PDA with heart failure (especially preterm) → treat/close
Duct-dependent congenital lesion (the OPPOSITE situation) → keep the duct OPEN with prostaglandin

Differentials & how to tell them apart

Venous humcontinuous, but disappears on lying flat/turning the head — benign

VSDpansystolic (not continuous), no machinery quality

Coarctationradio-femoral delay; different murmur

Investigations

Echocardiography (the duct, shunt direction, heart size); often found on the preterm/neonatal unit.

Management

Preterm → ibuprofen/indometacin to close; term/failed → catheter/surgical closure

1Confirm on echo. A symptomatic PDA in a PRETERM infant is closed with ibuprofen or indometacin (prostaglandin-synthesis inhibitors); a persistent PDA in term infants/children is closed by transcatheter device or surgical ligation.Gate: Know the TWO opposite prostaglandin manoeuvres: a prostaglandin INHIBITOR (ibuprofen/indometacin) CLOSES a problematic PDA, whereas PROSTAGLANDIN (alprostadil) is given to KEEP the duct OPEN in DUCT-DEPENDENT congenital heart disease (TGA/HLHS/critical coarctation) until surgery
2Device/surgical closure; treat heart failure; endocarditis awareness.

Ibuprofen or indometacin (prostaglandin synthesis INHIBITOR) — CLOSES a PDA in the PRETERM infant

Transcatheter/surgical ligation — if medical closure fails or in term infants/older children

PROSTAGLANDIN (alprostadil) — to KEEP the duct OPEN — the opposite use — in DUCT-DEPENDENT lesions (TGA, HLHS, critical coarctation/PS) while awaiting surgery

Key points

Continuous machinery murmur + bounding pulses = PDA (preterm/rubella). THE high-yield gate: ibuprofen/indometacin CLOSES it, but prostaglandin (alprostadil) is used to KEEP a duct OPEN in duct-dependent lesions — opposite directions, easily confused.

Monitor & prognosis

Heart failure; closure on echo.

Excellent after closure.

Source: RCPCH; BNFc