This is three times more in females.



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.



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.



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.