This is three times more in females.

Pathology

It is connected to the aorta 0.5 to 1 cm distal to the origin of the left subclavian.

It is cone shaped, with the smaller part at the pulmonary end.

Clinical features

Wide pulse pressure.

Machinery murmur at left infraclavicular area. Systolic murmur only if PAH.

Flow MDM at apex.

Differential cyanosis if Eisenmenger.

Chest X-ray

Ascending aorta is enlarged.

Echo-

Size can be assessed in high PSAX view or in suprasternal view.

Positive flow is seen in parasternal short axis view if there is left to right flow as is the usual case when there is no pulmonary hypertension.

Natural history-

PDA will not close in the full term infant as the ductus is not able to close due to an abnormality in its smooth muscle.

The PDA in a preterm may close later in life as the ductus is patent due to decreased response of its smooth muscle to oxygen, the ductal smooth muscle being structurally normal. In later life, the ductal smooth muscle achieves the ability to respond to oxygen and contracts, closing off the ducuts.

Rarely, the PDA can become aneurysmal and rupture.

Management-

A PDA which is not causing a murmur need not be closed. If it is causing a murmur, it has to be closed.

Indomethacin is ineffective in the term infant as the ductal smooth muscle is abnormal and cannot respond by contraction. (Note that it is can close a preterm’s PDA.)

Gianturco stainless coils are used to close PDAs of less than 4 mm size while Amplatzer device is used to close PDAs of 4 mm to 10 mm size.

Surgical closure is done when coil/device closure cannot be done. Ligation and division through left posterolateral thoracotomy or video assisted thoracoscopic clip ligation are the techniques.

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.