Echocardiographic assessment of Patent Ductus Arteriosus

Dr Sandeep Mohanan Senior resident, Cardiology

GMC, Kozhikode

TOPIC OVERVIEW• PDA anatomy and classification

• Echocardiographic identification

• Echocardiographic quantification

• Role of Echo in corrective management

• Role of 3D Echo and TEE

Anatomy

~ 10 * 5mm

5-10mm from the L-SCA

Embryology

Distal part of Left 6th arch

Classification – Angiographic(Krichenko et al,1989)

Conical

Window- like

Tubular Complex with multiple constrictionsElongated with a remote constriction

Krichenko et al. Angiographic classification of the isolated, persistently patent ductus arteriosus and implications for percutaneous catheter occlusion. Am J Cardiol.1989 Apr 1;63(12):877-80.

Why the PDA is often difficult to Echo-image?

TTE?? TEE??

When should the echocardiographer look for a PDA?

• All neonatal echo s• All paediatric referral for Echo• Any unexplainable cause of heart failure in

adults• Unexplained central cyanosis• Any unexplained PAH, LV volume overload• Any referral for suspicion of IE

TTE- PSAX view

Superior and leftward sweep of a routineBasal PSAX view

The 1st step in imaging the ductus is knowing where to look for it.

TTE-PSAX view for PDA

1. Three-legged pant view-high left PSAX view

A large PDA shunting L to R is often easily visualizedHowever smaller PDA required help of Colour Doppler

2. Horizontal short axis view

PSAX – Colour Doppler Echo

-Identify the ‘central flame in the blue stream’

(red - PDAblue-LPA, RPA, Desc Ao)

- A flow that appears to come from the left corner of the LPA origin and directed usually towards the left PV

However again confusion arises in the case of a predominant R to L shunt through the PDA.

Doppler echo

CWD - Normal PA vs PDA

3. Ductal view – high parasternal sagittal view

Ductal view with colour Doppler

Echo measurement of the Pulmonary end

4. TTE- Suprasternal view

The value of suprasternal view above parasternal views

Zhang et al. Value of the Echocardiographic Suprasternal View for Diagnosis of Patent Ductus Arteriosus Subtypes. JUM September 1, 2012vol. 31 no. 9 1421-1427

PDA type characterisation by suprasternal view

Measurements from the suprasternal view

-Ampulla-Adjacent aorticdiameter.

PDA significance

• The direction of shunting

• The shunt gradient

• PA pressures

• Size of the PDA

Direction of predominant shunting-PWD

Increasing PA pressures

Appearance of an early systolic R to L shunt withincreasing PA pressures

Widening and deepening of early systolic R to L shunt in parallel with a lesser L to R gradient.

PDA-Eisenmenger• Very difficult to demonstrate the Doppler flow• Corroborative evidence and clinical picture should guide

suspicion : Septal flattening, RVH, dilated PA, high velocity PR etc

• Contrast Echo : reveal bubbles in the descending aorta and not in the ascending aorta

PDA with suprasystemic pressures

PDA shunt quantifcation

• LA/ Aorta ratio -- >1.5 – moderate to large PDA (Sens -79%, Spec-95%)1

• LV dimensions• LV output• Qp/Qs• PDA pressure gradient• Colour Doppler ductal diameter• Diastolic flow reversal in descending aorta

1. Re-evaluation of the left atrial to aortic root ratio as a marker of patent ductus arteriosus. Archives of Disease in Childhood 1994; 70: Fl 12-Fl 17

Qp/Qs in PDA vs ASD/VSD• In VSD Qs- Qp = shunt• In ASD Qs - Qp = shunt

Any output from LV goes to the systemic circulation ... So, Qs= LV output

Any output from RV goes only to pulm circulation

ie, Qp = RV output

So Qp/Qs = RV output/ LV output for ASD & VSD

--- Continuity equation )

• However in PDA the shunt is extracardiacTherefore, Qp ≠ RV output (will be more) and Qs ≠ Lv output (will be less)

Qp/Qs in PDA

• Counterintuitively ,Qs = RV output & Qp = LV output

• Thus, Qp/Qs = LV output / RV output..... FOR AN ISOLATED PDA

However, for most neonates this is unusual.Coexisting L to R shunts makes simple ventricular output

ratios unreliable

Colour Doppler ductal diameter

• Optimal gain settings (not too high) •Maximum Doppler scale settings

• Duct should be imagedalong its entire length

Colour Doppler diameter > 2mm ~ Qp/Qs >2:1 in neonatesEvans N, Iyer P. Assessment of ductus arteriosus shunt in preterm infants supported by mechanical ventilation: effect of interatrial shunting.J Pediatr.1994;125:778–785

Diastolic flow reversal in Descending AoNORMAL FLOWPWD in PDA

Retrograde diastolic flow –VTId/VTIs >30% ~ QP/Qs>1.6

Increased diastolic flow in branch PAs

PDA in a Right aortic arch

• The PDA is commonly left in origin

Ductal aneurysm

• ~8%• May present at any age• In adults may present as a thoracic mass or with

cardiovocal syndrome• In children may spontaneously resolve• Requires surgical excision / covered stent

placement

Infective endocarditis

TEE image showing vegetations on the MPA wall at the pulmonary end of PDA

Use of 2D Echo in pre-interventional work up

• Minimum diameter (A)• Length (B)• Ampulla diameter (C)

• PDA type

Use of 2D Echo in pre-interventional work up

• Echo classification corresponding to Krichenko’sA- Conical with a narrow pulmonary endB- Short with narrow aortic endC- Tubular without constrictionD- Multiple constrictionsE- Long and tortuous requiring >1echo plane for complete imaging

Comprehensive Assessment of Patent Ductus Arteriosus by Echocardiography BeforeTranscatheter Closure. J Am Soc Echocardiogr 2002;15:1154-9.

Important to define the Ampulla

• Adequate Ampulla: Length of PDA> Narrowest portion of the PDA

(usually at pulm end)

• Inadequate ampulla: Short PDA - Worst example : WINDOW type (Type B)

• Tubular ductus: Same diameter from aorta to pulmonary end

Echo classification

• CONICAL DUCT ( common)

• WINDOW DUCT

• TUBULAR DUCT

Correlation of 2D echo and Angio• Wong et al found poor correlation between colour

Doppler and angiographic measurements1

• 2DE imaging overestimates the minimal diameter in comparison with angiography but in the majority difference was <1mm2

• In ~14% there is discrepancy in classification type2

• Ampulla and length measurement were the most discordant

1. Wong et al. Validation of color Doppler measurements of minimum patent ductus arteriosus diameters: significance for coil embolization. Am Heart J 1998;136:714-7.

2. Comprehensive Assessment of Patent Ductus Arteriosus by Echocardiography BeforeTranscatheter Closure. J Am Soc Echocardiogr 2002;15:1154-9.

TEE for PDA• TEE is not that popular among the PDA cohort in

its incremental benefit in echo diangnosis, compared to ASD, VSD and complex congenital heart disease

• Inherent difficulties in imaging

TEE imaging-In high esophageal position (~20-35cm), probe rotated completely backward to image decending aorta in the short axis (0 deg).... -Then slowly rotated to around 60 to 80 deg will help visualize the PDA to PA connection

Doppler TEE of PDA

Evaluation of Shunt Flow by Multiplane Transesophageal Echocardiography in AdultPatients with Isolated Patent Ductus Arteriosus. JASE 2002.

TEE vs TTE• 40 patients with PDA• Gold standard--- angiography

TEE sensitivity –97% vs 42% andTEE NPV 98% vs 68%, ; p<0.001) for confirming the presence of PDA

Diagnostic Accuracy of Transesophageal Echocardiography for Detecting Patent Ductus Arteriosus in Adolescents and Adults. CHEST 1995; 108:1201-05

For PDA Eisenmenger's syndrome, the sensitivity of TEE in confirming diagnosis of PDA was 100% vs 12% (p<0.01),

3D echo for PDA

Full volume 3D acquisition from a modified parasternal short-axis view, cropped so as to show the entrance of the PDA into the left pulmonary artery

3D vs 2D echo for PDA• 42 patients with PDA (mean ~3 years)

Roushdy et al. Visualization of patent ductus arteriosus using real-time three-dimensional echocardiogram: Comparative study with 2D echocardiogram and angiography. J Saudi Heart Assoc 2012;24:177–186

- 3D was better than 2D for type, length, ampulla as well as constrictions- Both 2D & 3 D Echo overestimated Type A- Type C was overdiagnosed by Echo- Type D is poorly defined in echo - Both underestimated Type E

3D TEE

3D TEE cropped view from aortic side

3D TEE guided device occlusion

Device closure guided by transaortic phased-array imaging

Bartel et al. Device closure of patent ductus arteriosus: optimal guidance by transaortic phased-array imaging. Eur J Echocardiogr (2011) 12 (2):E9.

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