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Patent Ductus Arteriosus
Patent ductus arteriosus (PDA) occurs in 5-10% of all congenital heart defects, excluding premature infants.
PDAs are very common in preterm babies and can have significant physiological effects. It is important to
recognise that PDA in the preterm infant and PDA in term babies and older children are two very distinct
conditions with different implications and management. This article primarily focuses on the PDA as a congenital
heart defect, with a separate section dealing with PDA in preterm babies at the end.
Physiology
The ductus arteriosus is, in developmental terms, a remnant of the sixth aortic arch and connects the pulmonary
artery to the proximal descending aorta just after the left subclavian artery origin. It is a normal structure in fetal
life.
In utero the lungs are not expanded. Gas exchange occurs at the placenta and only about 10% of the circulation
passes through the lungs. The ductus arteriosus connects the pulmonary artery to the aorta to shunt most of the
blood away from the lungs. After delivery it closes and the blood passes through the opened lungs. Failure of the
ductus arteriosus to close can lead to overloading of the lungs. The shunt is left to right unless pulmonary
hypertension occurs and pulmonary pressure exceeds systemic pressure.
After birth the ductus closes functionally in 12-18 hours and anatomically in 2-3 weeks. If it remains open beyond
three months of life in preterm infants and beyond one year of life in full-term infants it is termed as persistent
patency of ductus arteriosus because the incidence of spontaneous closure beyond these time limits is very
low. [1]
Epidemiology [2]
The factors responsible for persistent patency of ductus arteriosus in term babies are not completely
understood but genetic factors and intrauterine infection are likely to play a role.
The reported incidence varies widely because of methodological variations in the population studied
and definition of PDA.
In babies born at term the incidence is reported as in 1 in 2,000 births which accounts for 5-10% of all
congenital heart defects. If children with silent PDA (discovered incidentally by echocardiography done
for another purpose) are included, the incidence increases to 1 in 500 births.
It affects girls twice as often as boys but in congenital rubella syndrome the sex incidence is equal.
Risk factors [1]
Most cases are thought to be multifactorial due to combination of genetic predisposition and a critically
timed environmental exposure such as aspyxia during delivery, rubella infection during pregnancy or
unknown viral infections or chemicals.
Genetic syndromes such as trisomy 21 and Holt-Oram syndrome.
Exposure of a fetus to valproic acid in pregnancy.
Birth at high altitude - because of exposure to low oxygen tension.
Presentation [3]
History
Patients with a small PDA are usually asymptomatic.
A large-shunt PDA may cause lower respiratory tract infection as well as feeding difficulties and poor
growth during infancy, with failure to thrive because of heart failure.
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Examination
If the pulmonary circulation is markedly overloaded there will be tachycardia, tachypnoea and a wide
pulse pressure.
The precordium is hyperactive and a systolic thrill may be present at the upper left sternal border.
The first heart sound is normal but the second is often obscured by the murmur.
A grade 1 to 4/6 continuous ('machinery') murmur is best audible at the left infraclavicular area or
upper left sternal border.
In the case of a large PDA shunt, a diastolic mitral rumble may be heard because of the high flow rate
across the mitral valve.
Patients with a small PDA do not have the above-mentioned findings.
Peripheral pulses are bounding as the run-off into the pulmonary circulation drops the diastolic
pressure and causes a wide pulse pressure.
Click here to hear an example of the murmur:
Differential diagnosis [3]
A number of conditions present with a murmur similar to the continuous murmur of PDA or with bounding pulses
and require differentiation from PDA. These include:
Coronary arteriovenous fistula.
Systemic arteriovenous fistula.
Pulmonary arteriovenous fistula.
Venous hum.
Fallot's tetralogy (with absent pulmonary valve).
Ruptured aneurysm of the sinus of Valsalva (seen in Marfan's syndrome).
Aortopulmonary septal defect (aortopulmonary window).
Investigations [4]
The only investigation needed to confirm the diagnosis and significance of PDA is echocardiograpy. Occasionally,
CXR and ECG are also performed.
Echocardiography confirms the diagnosis and characterises the anatomy and physiology of the PDA.
A complete echocardiogram includes measurement of cardiac chambers and function, twodimensional imaging of PDA anatomy and Doppler assessment to define PDA shunt flow. The ratio of
left atrial size to aortic root size can be used to estimate the degree of PDA shunt.
If the shunt is significant, CXR will show enlargement of the pulmonary arteries, veins, left atrium and
left ventricle. Such features usually require a ratio of pulmonary flow to systemic flow of at least 2:1. In
older people a PDA may be calcified and visible on a plain film.
ECG is often normal in small or moderate PDA but there may be signs of left ventricular hypertrophy
(LVH). A large PDA may be associated with signs of biventricular hypertrophy (BVH) and in those with
pulmonary hypertension, right ventricular hypertrophy (RVH) may be present.
Management
Indometacin is ineffective in term infants with PDA and should not be used. Medical management is
limited to use of decongestive measures such as diuretics in those with features of heart failure.
PDA closure is indicated for any symptomatic infant, child or adult (with exclusion of those with fixed
high pulmonary vascular resistance). Closure is also indicated in asymptomatic patients with left heart
volume load. This can be done either by surgery or interventional techniques at any age. [4]
Surgical closure is reserved for patients in whom a non-surgical closure technique is not considered
applicable. In infants with heart failure or pulmonary hypertension, surgery is performed on an urgent
basis. The standard surgical procedure is ligation and division of the ductus through left posterolateral
thoracotomy without cardiopulmonary bypass. [3]
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In asymptomatic well infants current practice is to wait until 1 year of age, with regular
echocardiographic evaluation to check for spontaneous closure of the PDA. If the duct is still patent at
1 year of age it can be closed usually by occlusion at cardiac catheterisation (endovascular
occlusion). National Institute for Health and Care Excellence (NICE) guidance has been produced and
considers that current evidence on the safety and efficacy of endovascular occlusion of PDA appears
to support the use of this procedure. [5] The procedure should be performed in units where there are
arrangements for cardiac surgical support in the event of complications. The choice of device
depends largely on the size of PDA. Coils are suitable for closing of small- to medium-sized PDAs
while larger PDAs require other devices such as the Amplatzer® patent ductus arteriosus device.
Serious complications of transcatheter closure of PDA are rare and include device embolisation,
femoral artery or vein thrombosis related to vascular access and infection. [4]
Whilst the ductus arteriosus is patent then the risk of endocarditis should be considered (there is no
increased risk of endocarditis once repair is complete). Routine antibiotic prophylaxs is not indicated
but during invasive procedures (eg, urinary or gastrointestinal procedures) involving areas of sepsis,
suitable antibiotics should be given promptly (to cover all the likely organisms, including any known to
cause endocarditis). [6]
Complications
Many patients with small PDAs do not have any haemodynamic overload and apart from the risk of endarteritis
have a normal prognosis. Those with significant left heart volume load can develop congestive heart failure or
irreversible pulmonary vascular disease. [2]
Prognosis
In most older patients successful closure of the PDA can be achieved without complications, and
long-term follow-up is not required.
Children who have had a PDA closed need no further restrictions on their lives.
Patent ductus arteriosus in preterm neonates
PDA is a common diagnosis in extremely preterm infants, especially in those with lung disease. Approximately
65% of infants born at less than 28 weeks of gestation will have persistent patency of the ductus arteriosus and
will be assigned the diagnosis of PDA at some time during the early neonatal period. [7]
In a preterm infant, PDA should be suspected if the respiratory distress because of hyaline membrane
disease does not improve or worsens after initial improvement and the baby cannot be weaned off the
ventilator.
In the premature infant of low birth weight, the classical signs are usually absent. The continuous
murmur is rarely heard. There may be a rough systolic murmur along the left sternal border but a
small baby with a large PDA and significant pulmonary over-circulation may have no murmur. Physical
examination commonly reveals bounding peripheral pulses, a hyperactive precordium, and
tachycardia with or without gallop rhythm.
In a premature baby, the ECG is not diagnostic. It is usually normal but may show LVH.
The diagnosis is confirmed by echocardiography which not only allows the PDA to be visualised but
also assesses the haemodynamic significance of the PDA.
Management of PDA in the preterm infant remains controversial, with diverse approaches ranging
from very conservative management to aggressive early closure of the duct pharmacologically or
surgically. [8]
A recent meta-analysis of published randomised controlled trials has shown that while indometacin
prophylaxis reduces incidence of intraventricular haemorrhage (IVH), symptomatic PDA and the need
for surgical ligation, there was no reduction in other morbidities, including chronic lung disease (CLD),
necrotising enterocolitis (NEC) and, most importantly, neurodevelopmental impairment. [9] The authors
of the meta-analysis conclude that depending on clinical circumstance and personal preference there
may be a role for prophylactic indometacin in some infants on some neonatal units.
Ibuprofen may possibly be a safer alternative that is less likely to cause oliguria. [10, 11]
Surgical ligation of the duct is associated with significant morbidity (hypotension, pneumothorax, vocal
cord paralysis) and mortality. A recent Scottish study has reported a one-year mortality of 12.8% and a
32% incidence of neurodisability in survivors undergoing duct ligation. [12]
Echocardiography-guided catheter closure of the ductus in small preterm babies in the neonatal
intensive care unit has been reported from Oxford. [13]
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Diuretics and restriction of fluid used to be recommended whilst awaiting spontaneous closure.
However, the evidence base is poor and a systematic review of furosemide in preterm neonates with
respiratory distress symptoms showed no long-term benefits and increased the risk of symptomatic
PDA. [14]
PDA is commonly diagnosed in extremely preterm infants and is associated with numerous
pathologies, including CLD, NEC and IVH. The evidence for some of these associations is conflicting
and as association does not imply causation these should not be labelled as complications of PDA. [8]
It used to be believed that premature babies with significant PDA are more likely to develop
bronchopulmonary dysplasia (BPD). However, although early pharmacological closure of PDA
decreases the incidence of pulmonary and intraventricular haemorrhage, there is little evidence from
controlled clinical trials to support or refute a causal role for PDA in the development of BPD. [15]
In infants weighing less than 1000 g, prophylactic non-steroidal anti-inflammatory drug (NSAID) use
may aid closure and reduce the risk of subsequent morbidity. [16] However, there is no evidence of
long-term benefit. [16, 17]
Further reading & references
British Heart Foundation
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Anilkumar M; Patent ductus arteriosus. Cardiol Clin. 2013 Aug;31(3):417-30. doi: 10.1016/j.ccl.2013.05.006.
Schneider DJ, Moore JW; Patent ductus arteriosus. Circulation. 2006 Oct 24;114(17):1873-82.
Park MK; Pediatric Cardiology for Practitioners, 5th Edition, Mosby Elsevier. 2008.
Schneider DJ; The patent ductus arteriosus in term infants, children, and adults. Semin Perinatol. 2012 Apr;36(2):146-53.
doi: 10.1053/j.semperi.2011.09.025.
Endovascular closure of patent ductus arteriosus, NICE (2004)
Prophylaxis against infective endocarditis: Antimicrobial prophylaxis against infective endocarditis in adults and children
undergoing interventional procedures; NICE Clinical Guideline (March 2008)
Bose CL, Laughon MM; Patent ductus arteriosus: lack of evidence for common treatments. Arch Dis Child Fetal Neonatal
Ed. 2007 Nov;92(6):F498-502.
Smith CL, Kissack CM; Patent ductus arteriosus: time to grasp the nettle? Arch Dis Child Fetal Neonatal Ed. 2013
May;98(3):F269-71. doi: 10.1136/fetalneonatal-2011-301129. Epub 2012 Feb 28.
Fowlie PW, Davis PG, McGuire W; Prophylactic intravenous indomethacin for preventing mortality and morbidity in preterm
infants. Cochrane Database Syst Rev. 2010 Jul 7;(7):CD000174. doi: 10.1002/14651858.CD000174.pub2.
Van Overmeire B, Smets K, Lecoutere D, et al; Acomparison of ibuprofen and indomethacin for closure of patent ductus
arteriosus. N Engl J Med. 2000 Sep 7;343(10):674-81.
Ohlsson A, Walia R, Shah S; Ibuprofen for the treatment of a patent ductus arteriosus in preterm and/or low birth weight
infants. Cochrane Database Syst Rev. 2003;(2):CD003481.
Heuchan AM, Hunter L, Young D; Outcomes following the surgical ligation of the patent ductus arteriosus in premature
infants in Scotland. Arch Dis Child Fetal Neonatal Ed. 2012 Jan;97(1):F39-44. doi: 10.1136/adc.2010.206052. Epub 2011
Aug 17.
Bentham J, Meur S, Hudsmith L, et al; Echocardiographically guided catheter closure of arterial ducts in small preterm
infants on the neonatal intensive care unit. Catheter Cardiovasc Interv. 2011 Feb 15;77(3):409-15. doi: 10.1002/ccd.22637.
Epub 2010 Oct 6.
Brion LP, Campbell DE; Furosemide for symptomatic patent ductus arteriosus in indomethacin-treated infants. Cochrane
Database Syst Rev. 2001;(3):CD001148.
Clyman RI; The role of patent ductus arteriosus and its treatments in the development of bronchopulmonary dysplasia.
Semin Perinatol. 2013 Apr;37(2):102-7. doi: 10.1053/j.semperi.2013.01.006.
Fowlie PW, Davis PG; Prophylactic intravenous indomethacin for preventing mortality and morbidity in preterm infants.
Cochrane Database Syst Rev. 2002;(3):CD000174.
Fowlie PW, Davis PG; Prophylactic indomethacin for preterm infants: a systematic review and meta-analysis. Arch Dis
Child Fetal Neonatal Ed. 2003 Nov;88(6):F464-6.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical
conditions. EMIS has used all reasonable care in compiling the information but makes no warranty as to its
accuracy. Consult a doctor or other healthcare professional for diagnosis and treatment of medical conditions.
For details see our conditions.
Original Author:
Dr Richard Draper
Current Version:
Dr Anjum Gandhi
Peer Reviewer:
Dr Adrian Bonsall
Document ID:
2579 (v22)
Last Checked:
13/06/2014
Next Review:
12/06/2019
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