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 Connects to the LPA-MPA junction( actually embryologically from the distal 6th left arch (proximal of which forms the proximal LPA) Around 5-10mm distal to the LSCA origin. At birth it has a diameter of ~ 10mm and in newborn it is almost as if a continuation from the MPA It runs parallel to the arch in same direction and joins at an angle of 30-35degree..... In an AP projection the PDA actually overlaps its aortic entrance

Embryology Distal part of Left 6th arch

Classification – Angiographic (Krichenko et al,1989) Conical Window- like Elongated with a remote constriction Tubular Complex with multiple constrictions 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 The 1st step in imaging the ductus is knowing where to look for it. Superior and leftward sweep of a routine Basal PSAX view

TTE-PSAX view for PDA Start in the high parasternal view...initially angle slightly to the right where the ascending aorta is visualized and RPA crosssection posteriorly...then slightly keep rotating probe to left till the MPA a body is seen...A further slighter angulation foreshortens the MPA and body and brings a good view of the bifurcation.... This reveals the root of the LPA and the origin of the PDA... In this view the PDA is seen to arise superiorly from the LPA root as an arch that is in continuity with the MPA

1. Three-legged pant view -high left PSAX view A large PDA shunting L to R is often easily visualized However 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 - PDA blue-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 aortic diameter. For the purpose of device sizing it is important to assess aortic size...so as to avoid luminal encroachment.

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 with increasing 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 extracardiac Therefore, Qp ≠ RV output (will be more) and Qs ≠ Lv output (will be less)

Qp/Qs in PDA Thus, Qp/Qs = LV output / RV output 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 imaged along its entire length Colour Doppler diameter > 2mm ~ Qp/Qs >2:1 in neonates Evans 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 Ao PWD in PDA NORMAL FLOW 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’s A- Conical with a narrow pulmonary end B- Short with narrow aortic end C- Tubular without constriction D- Multiple constrictions E- Long and tortuous requiring >1 echo plane for complete imaging Comprehensive Assessment of Patent Ductus Arteriosus by Echocardiography Before Transcatheter 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 – 27 children...difference of upto 1.7mm in assessing minimum diameter, Colour doppler excluded 11% patients on the premise that it was large (>4mm)...angiographically <4mm 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. Comprehensive Assessment of Patent Ductus Arteriosus by Echocardiography Before Transcatheter 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 Adult Patients with Isolated Patent Ductus Arteriosus. JASE 2002.

TEE vs TTE 40 patients with PDA Gold standard--- angiography TEE sensitivity –97% vs 42% and TEE NPV 98% vs 68%, ; p<0.001) for confirming the presence of PDA For PDA Eisenmenger's syndrome, the sensitivity of TEE in confirming diagnosis of PDA was 100% vs 12% (p<0.01), Diagnostic Accuracy of Transesophageal Echocardiography for Detecting Patent Ductus Arteriosus in Adolescents and Adults. CHEST 1995; 108:1201-05

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) - 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 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 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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