Preterm means born at less than 37 weeks gestational age.

Pathology

Preterm ductal smooth muscle is less responsive to oxygen- so the ductus remains open.

The left to right shunt causes pulmonary congestion- this may further deteriorate lung function in preterms with HMD or bronchopulmonary dysplasia (due to oxygen therapy). Typically, PDA is suspected when a preterm with HMD cannot be weaned from the ventilator.

Echo

 Positive flow in parasternal short axis window indicates left to right shunt and vice versa. With severe PAH, bidirectional flow is seen with negative systolic and positive diastolic flows.

Management

Asymptomatic– Observe or treat medically for 6 months for spontaneous closure.

Symptomatic– Close medically or, if that is not possible, surgically.

Medical closure– This is done with indomethacin or ibuprofen. Indomethacin dose is 0.2 mg/kg IV q12h for 3 doses. Ibuprofen dose is 10-5-5 mg/kg IV at 24 hour intervals.

Surgical closure– This is done via a posterolateral thoracotomy.