Paediatrics: Patent ductus arteriosus

2021-03-05 12:00 AM

Defined as a failure of ductus arteriosus to close normally after birth. The ductus is normally functionally closed within 1–3 days of birth in term infants.

Patent ductus arteriosus

Defined as a failure of ductus arteriosus to close normally after birth. The ductus is normally functionally closed within 1–3 days of birth in term infants. Common in preterms (>50% if VLBW).

Presentation

  • Small: asymptomatic.
  • Large:
  • poor growth, difficulty feeding, respiratory difficulty, systolic or continuous ‘machinery’ murmur at the upper left sternal edge radiating to back, heart failure;
  • CXR. Cardiomegaly, pulmonary plethora;
  • echocardiography confirms PDA and the degree of the shunt.

Complications 

Poor growth, heart failure, pulmonary haemorrhage, ‘rise' risk of BPD.

Management

There is considerable uncertainty about whether preterm infants benefit from treatment for PDA and, if so, what is the optimal treatment. There is wide variation in practice with some units treating many cases and others almost none. An approach considered sensible by many is: 

If asymptomatic 

Observe because most close spontaneously.

If symptomatic 

In a preterm infant consider the following:

  • Restrict fluids, e.g. 100–120mL/kg/day.
  • Optimize blood oxygenation, e.g. blood transfusion if anaemic.
  • Treat heart failure, e.g. furosemide 1mg/kg 12-hourly PO or IV.
  • Consider pharmacological closure (e.g. indomethacin or ibuprofen). If the duct fails to close a repeat course may be given. Side effects: ‘fall’ renal blood flow leading to oliguria, fluid retention, +/– hyponatraemia; ‘fall’ cerebral blood flow; GI complications (bleeding, ulceration); bleeding (d platelet function); displace protein binding of bilirubin. Consequently, indomethacin is contraindicated if severe jaundice, necrotizing enterocolitis (NEC), thrombocytopenia, or renal failure. Pharmacological closure is also contraindicated when the PDA is necessary for pulmonary blood flow (e.g. some forms of congenital heart disease).
  • Surgery may be necessary if medical management fails to control symptoms or if there is significant heart failure, ventilator dependence, or prolonged failure to close.

Prognosis

Generally good, but infants who require PDA treatment often have other morbidities that affect prognosis, including severe BPD. Surgery after failed medical treatment carries a significant risk of mortality. PDA is much less likely to close when present in term infants. Medical treatment in term infants is not likely to be effective.