CHAPTER 7 Patent ductus arteriosus (PDA)
Features
The ductus arteriosus usually closes functionally by 48 hours and anatomically by 3 weeks of age in well, term babies. Closure may take longer in preterm or unwell babies.
PDA is associated with increased risk of death, intraventricular haemorrhage (IVH), chronic lung disease, necrotising enterocolitis and impaired renal function; although a causal relationship has not been proved. Most PDAs are asymptomatic and there is no uniformity in the approach to management of PDA. Many will eventually close spontaneously without any specific intervention. Only a small number will cause heart failure. Complications of PDA are related, at least theoretically, to shunting through the duct, circulatory overload and the ‘diastolic steal’ phenomenon.
Diagnosis
The diagnosis of PDA is best done using echocardiography. Clinical signs of a PDA often lag behind the echocardiographic findings by several days, consistent with findings that clinical diagnosis has very low sensitivity. The specificity of many clinical features is also low, as is the inter-observer agreement of the presence of signs. Classical signs that may be sought include:
A chest X-ray has been found to add very little to the other clinical signs in the diagnosis of PDA. In high-risk babies, most but certainly not all systolic murmurs will indicate the presence of a duct. Remember also that some babies (including preterm ones) will have a duct-dependent cardiac lesion.
Decision to treat
The decision to treat a PDA should be based on more than just finding it. Factors such as the baby’s age and gestational age, general condition, and degree of left-to-right shunting should be taken into account. Systematic reviews have not shown any significant benefit to treatment of asymptomatic nor symptomatic PDA. However, most neonatologists would have difficulty ignoring a symptomatic duct and many also choose to treat asymptomatic ducts under some circumstances.
Information that may be provided by the cardiologist or echocardiographer that would indicate a more significant or ‘troublesome’ duct includes:

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