A 30-minute talk, presented as part of the weekly teaching activities in Alder Hey Children's Hospital (Liverpool, UK). It addresses PDA evaluation in children - starting with embryology & anatomy with the basis behind physiological closure versus patency after birth. What is the role of echo study in diagnosing/evaluating PDA? Modes used with some clear movies? Its limitations?

1. PDA Echocardiographic
Assessment: Anatomy,
Flow & Suitability for
Closure
Abd El-Salam Al-Ethawi, MD
Specialty Doctor in Paediatric Cardiology,
Alder Hey Children’s Hospital
2021

2. Disclaimer:
AUDIENCE TIME FEEDBACK

3. Objectives:
• To know the embryologic origin of PDA
• Basis behind physiological closure vs patency
• To understand PDA anatomy, its variants, and suitability for closure
• How can we diagnose PDA with echo?
• What are the helpful modes (2D, CW, PW, M-Mode)?
• Some echo limitations?

4. Background

5. The ductus arteriosus (DA):
fetal vascular connection
between the main pulmonary
artery and the aorta that diverts
blood away from the
pulmonary bed.

6. • Derived from the embryonic left
sixth aortic arch.
• Aortic end arises distal to the
left subclavian artery and the
pulmonary end inserts at the
junction of the main and left
pulmonary arteries.

7. • Right aortic arch:
• Mostly, DA arises from the left
innominate artery and inserts
into the proximal LPA.
• Less frequently, the DA arises
distal to right subclavian
artery and inserts near the
proximal RPA.
• Rarely, bilateral DA; presence
of other complex congenital
cardiovascular anomalies.

8. Vascular ring due to PDA?
• Right aortic arch + aberrant
left subclavian artery.

9. Histology:
• Intima thicker
• Media contains more smooth
muscle fibers arranged in a
characteristic spiral fashion
Abnormal wall structure 
Failure to spont. closure

10. Krichenko angiographic classification:
• Type A – Conical; narrowest portion at PA.
• Type B – Short with narrowing at Ao.
• Type C – Tubular without constriction
• Type D – Tubular with multiple constrictions
• Type E – Bizarre, with an elongated, conical
appearance and multiple constrictions
Not include the ‘reverse-oriented ductus’

11. Fetal Circulation:
RV accommodates 60 percent of the total
COP.
• Pulmonary vasculature is constricted  high
PVR.
• In contrast, the placenta creates a very low
resistance bed  low SVR.
↓
• Majority of blood passes right-to-left
across the DA into the descending aorta
and on to the placenta.

12. • In the fetus, the DA is large, with a diameter
approximating that of the descending
aorta!
• Onset of respiration:
• Lungs expand  systemic O2 sat rises, 
pulmonary vasodilatation  drop in PVR
• At the same time, SVR rises with placental
removal
↓
• Sudden reversal of blood flow from right-to-
left to left-to-right

13. Ductal constriction:
• At birth, ductal constriction is triggered
by:
• ↑O2 tension
• ↓PGE2
o Removal of the placenta
o Prostaglandin dehydrogenase

14. • Functional closure: 10 - 15 hours;
begins at the pulmonary end of the DA
• Anatomical closure: completed by 2-3
weeks
↓
Ligamentum arteriosum

15. Incidence, pathophysiology, clinical
presentation, and treatment options differ in
preterm babies

16. Closure of PDA is indicated even in
asymptomatic patients, regardless of its
variant:
• Risk of infective endarteritis
• Closure is associated with minimal risk

17. Closure of PDA:
Current practice in different parts of the world:
- PDA 2mm and less  coil closure (e.g., Nit-Occlud)
- PDA >2mm  Device closure (e.g., Amplatzer)
- PDA >12mm  septal device, VSD muscular, stent, or surgery

18. How can we
diagnose PDA?

19. How can we
diagnose PDA?
• Clinical evaluation – including ECG &
CXR
• Imaging:
• Echocardiography
• Angiography
• CT/MRA – complex anatomy

20. Echocardiography:
Anatomic confirmation by 2D imaging
Doppler echocardiography
hemodynamic assessment
 degree of shunting
 pulmonary artery pressure

21. Echocardiography:
Many views using 2D
echocardiographic imaging and
superimposed Doppler color flow
mapping
Parasternal short-axis (PSAX) view:
ductus connecting the pulmonary artery
and the descending aorta near the
origin of the LPA

22. Echocardiography:
Many views using 2D
echocardiographic imaging and
superimposed Doppler color flow
mapping
Parasternal short-axis (PSAX) view:
ductus connecting the pulmonary artery
and the descending aorta near the
origin of the LPA

23. Echocardiography:
Suprasternal notch window, the
ductus arises from the descending
aorta at level of the left subclavian
artery and courses anteriorly to join PA

24. Echocardiography:
Suprasternal notch window, the
ductus arises from the descending
aorta at level of the left subclavian
artery and courses anteriorly to join PA

25. Echocardiography:
DUCTAL VIEW – Moving the transducer just
laterally & inferiorly to an “infraclavicular”
position; rotating clockwise.

26. Echocardiography:
Right aortic arch, the ductus
usually arises from the left
brachiocephalic (Innominate)
vessels instead of the descending
aorta and can be followed caudally
to its insertion on PA
What is wrong here?

27. Echocardiography:
Left atrial and ventricular dilation
are seen in the presence of a
large left-to-right shunt.

28. Echocardiography:
Doppler color flow
Supplement 2D imaging
Retrograde color flow jet in PA
Normal PAP, the high-velocity
turbulent flow is easily seen in
both systole and diastole

29. Echocardiography:
Doppler color flow
Supplement 2D imaging
Retrograde color flow jet in PA
Normal PAP, the high-velocity
turbulent flow is easily seen in
both systole and diastole

30. Echocardiography:
Doppler echocardiography can
estimate the degree of left-to-right
shunt and assess the pulmonary
artery pressure.
PG: 35mmHg

31. Echocardiography:
Large PDA:
 Low peak systolic velocity
 Low/absent diastolic velocity
 Flow reversal in descending
aorta
PG: 35mmHg

32. Echocardiography:
Large PDA:
Continuous runoff can be seen
in the branch pulmonary arteries
and in the aorta proximal to the
PDA by pulsed Doppler
echocardiography
Not mistaken with COA!
PG: 35mmHg

33. Echocardiography:
Large PDA:
Distal to the origin of the PDA,
diastolic retrograde flow can be
demonstrated, corresponding to
the runoff into the pulmonary
artery
Other Causes?
PG: 35mmHg

34. Echocardiography:
PAP = systemic pressure:
Pulsed Doppler (PW) within
ductus demonstrates systolic
right-to-left shunting, with
diastolic left-to-right flow within the
vessel
PG: 35mmHg

35. QP = VTI*CSA
QS = VTI*CSA
Echocardiography:
The pulmonary-to-systemic-flow ratio
(Qp:Qs) can be estimated using the
area of the LVOT & RVOT and Doppler-
derived velocity.
However, the ductal jet frequently
distorts the antegrade pulmonary flow
signal  not usually helpful.

36. Echocardiography:
RV and PAP may also be derived by:
TR velocity
Ventricular septal configuration
(qualitatively)

37. Echocardiography:
M-mode echocardiography – significant left-to-
right shunting:
Increased LVIDd
A ratio of LA-to-Ao > 1.5:1
TOE - difficult to visualize PDA

38. Conclusions:
Derived from the embryonic left sixth aortic arch
Changes in O2 tension/PGE2 and PDA wall
histology  post-natal closure VS patency
 PDA should be closed – regardless to its size /
shape
 Once suspected, TTE is initial investigation of
choice to confirm Dx
2D, Color flow, Doppler & M-Modes should be used
for full anatomic/haemodynamic assessment

39. ANY QUESTION?
PDA Echocardiographic Assessment: Anatomy, Flow
& Suitability for Closure
Abd El-Salam Al-Ethawi, 2 0 2 1