PICS~AICS

How I do it: Tips, Tricks, and Techniques

A PICS Society education series

Ductus arteriosus stenting in ductal dependent pulmonary blood flow

Authors: Niall Linnane, MD., and Damien Kenny, MD, FACC, FSCAI, FPICS

 

Introduction:

Historically, a systemic to pulmonary artery shunt (SPS) was the procedure of choice to augment pulmonary blood flow when required however, with the advent of modern cardiac catheterisation techniques there have been many reports demonstrating excellent results with Ductus Arteriosus (DA) stenting when compared to SPS for initial palliation even in small infants1-4.

Anticipated challenges of the procedure:

  • Huge morphological/anatomical heterogeneity
  • Access to the DA depending on its origin. Femoral (venous and arterial) versus axillary versus carotid arterial approach
  • Pre-and intra-procedural imaging to assess tortuosity and length of the ductus arteriosus
  • DA spasm when manipulating wire crossing of the DA, possibly leading to acute decompensation – lack of consensus on extent of surgical back-up
  • Stent migration in large DAs – need and timing of cessation of prostaglandin
  • Jailing of either branch pulmonary arteries
  • Ensuring adequate coverage of entire PDA
  • Stent thrombosis

 

TIP 1. Planning and Preparation

  1. Access: A Computed Tomography (CT) angiogram is useful to define the origin and anatomy of the DA and guide vascular approach. Some operators, if using the carotid artery, prefer to have a carotid cut-down performed by the cardiothoracic surgeons particularly in low birth weight infants. Femoral venous access through the heart (if a VSD is present) is an alternative option to avoid arterial access.
  2. For most patients, the prostaglandin infusion is stopped 6-8 hours prior to the procedure to allow the DA to restrict and give a better landing zone for the stent, although in very tortuous DA's some operators may chose to leave low dose prostaglandin running through the procedure.
  3. Imaging: Initial biplane angiography; LAO 30° on the frontal and lateral 90° planes to delineate the course of the DA (Video 1) will provide a good initial assessment. Optimal angulated views may be supported by the pre-procedural CT. The goal is to outline the entire length and curvature of the DA. Multiple measurements including the shortest length connecting proximal to distal ends (Image 1) can be taken however predicting the optimal stent length can be challenging. Often crossing the DA with a coronary wire may lead to straightening of the ductus and assist in "predicting" the impact of a stent (Video 2). Some operators have used a coronary balloon to achieve the same goal.
  4. There is a risk of DA spasm and acute decompensation during the procedure, even when inserting the catheter to take the initial angiogram. The cardiothoracic surgeons need to be aware of the procedure and departmental protocols should be in place to guide the level of ECLS (Extra-Corporeal Life Support) back-up.

Figure 1: Lateral angiographic image demonstrating straight measurement of PDA from aortic to pulmonary artery end. Exact length can be difficult to discern especially in a tortuous as demonstrated here.

  1. Patient positioning maybe defined by the vascular approach with the flip technique as previously described. Coordination with anaesthesia is important and level of intra-procedural monitoring may vary on the expected procedural risk, which may be defined by ductal tortuosity.

Video 1: Lateral angiography demonstrating tortuous PDA with access from the left axillary artery


 

Video 2 demonstrating straightening of the PDA as the stiffer part of the wire is advanced.

 

Tip 2. Tools needed

  1. Sheaths: A 4Fr Terumo Radiofocus Introducer sheath is usually used. If using femoral venous access a 5Fr system can be used to facilitate use of a Guide catheter.
  2. Catheters and wires: A 4Fr angled non-tapered Gluidecath (Terumo Europe, Leuven, Belgium) is used for angiography. A soft tipped 0.014" wire is used initially to cross the PDA and the wire is advanced into either the distal LPA or RPA. This wire can be fixed in the distal branch PA's by rotating the wire to provide varying support if the stent does not initially traverse easily over the wire. Alternatively, if more stability is required, a stiffer 0.014" wire (Asahi Medical, Tokyo, Japan) may be used. Occasionally a "buddy" wire has been used to provide extra support. A microcatheter can be advanced over the wire after stent deployment to simulate the final stent position on angiography once the wire is removed. This facilitates back-up access across the stent if the stent "drops" into the aortic ampulla with wire removal.
  3. Devices: A large range of pre-mounted coronary drug eluting stents should be available. The aim is to deploy a single stent but longer stents can be difficult to track along a serpiginous DA and consequently two stents may be required. Distal placement towards the pulmonary end ensuring full coverage of this end of the duct is advisable if two stents are required to facilitate ease of recrossing with a second stent more proximally. Deflectable microcatheters are also available to facilitate traversing through an angulated initial stent.
  4. Other: Angiography can be performed through the side arm of the short sheath when a carotid or axillary approach are preferred. With a femoral arterial approach, a longer 4Fr Flexor sheath may be required to guide optimal stent positioning.

 

Tip 3. How I do it

Details of the technique:

The cardiac catheterisation procedure is usually performed under general anaesthetic with endotracheal intubation.

Once access is achieved, 100units/kg of IV Heparin is given and an angiogram is performed via a 4Fr angled non-tapered Terumo Gluidecath. Biplane angiography is performed with the most common angles being 90° on the lateral and LAO 30° on the frontal.


Before crossing the DA, the stent needs to be prepped and ready as crossing the DA can cause spasm and desaturation leading to haemodynamic instability. Stent diameter is usually chosen to be 0.5-1mm larger than the infants weight in kilograms – ie 3.5mm to 4mm diameter stent for a 3 kg infant. If the wire position is not adequate, 3 clockwise turns can be placed (if using a softer 0.014"  wire – ie BMW) to allow the wire to be "locked" in place and provide more traction when advancing the stent. The stent is deployed over the wire with positioning confirmed on angiography (Video 3 & 4). Ensure a coordinated approach and that all potential pitfalls have been addressed ie: ensuring the inflation device is tightly connected to the stent catheter.

 

Video 3: AP angiography with stent in position. Note concertina effect on the duct from the stent and wire straightening the serpiginous PDA


 

Video 4: Lateral angiography with stent in position. Note concertina effect on the duct from the stent and wire straightening the serpiginous PDA

 

Following stent deployment, a microcatheter (Penumbra, Berlin, Germany) is advanced over the wire to maintain access across the stent when the wire is removed. Three anti-clockwise turns are performed on the wire to "unlock" it and it is then removed. Final angiography can then be performed with a soft catheter across the stent and final position can be determined while maintaining access across the stent.

 

Video 5: AP angiography post stent expansion with soft part of the wire maintained across the stent if further access required.

 

Video 6: Lateral angiography post stent expansion with soft part of the wire maintained across the stent if further access required.

 

Pitfalls to avoid

  • Maintain access across the stent at all times with the micro-catheter to facilitate access should the aortic end of the stent "drop" into the ampulla with wire removal.
  • In general, err on the side of a longer stent with borderline length measurements – ie a 18mm long stent maybe a better choice than a 15mm stent for a 15mm length DA. Avoiding a second stent is ideal as re-crossing the initial stent even with good wire position may result in distortion of the initial stent.
  • Although data are lacking many operators prefer dual antiplatelet therapy post DA stenting. Clopidogrel may need to be stopped in advance of further surgical palliation.

 

Tip 4. What complications to expect and how to deal with them

  • Deciding which ductal morphologies may be unsuitable for DA stenting is challenging. Case complexity may vary from rather straightforward anatomies to very complex anatomy and therefore a standardized approach particularly in relation to surgical back-up maybe difficult and perhaps should be considered on a case-by-case basis. Published data suggests more tortuous DA's maybe associated with increased need for re-intervention5.

  • If a larger stent is required to reduce stent slippage then be aware of pulmonary over circulation and systemic hypoperfusion.

  • Stent thrombosis is uncommon but can be challenging. Strict attention to ACT measurements are important particularly with protracted cases. Local infusion of Heparin has been described to treat this complication. Pre-procedural aspirin may help although data are lacking to prove benefit in ductal stenting (some data to support its use with BTT shunting).

  • Re-intervention prior to definitive surgery has been reported at up to 40% and includes need to intervene for proximal branch pulmonary artery stenosis5.

 

Summary:

DA stenting in the infant who requires secure pulmonary blood flow before a definitive repair or Glenn operation is safe and effective. Pre-procedure planning with CT imaging and consultation with the cardiothoracic surgeons ensures the optimal trajectory to the DA is chosen and bail out options are available.

 

References:

  1. Bentham, J.R., et al., Duct Stenting Versus Modified Blalock-Taussig Shunt in Neonates With Duct-Dependent Pulmonary Blood Flow. Circulation, 2018. 137(6): p. 581-588.
  2. Glatz, A.C., et al., Comparison Between Patent Ductus Arteriosus Stent and Modified Blalock-Taussig Shunt as Palliation for Infants With Ductal-Dependent Pulmonary Blood Flow. Circulation, 2018. 137(6): p. 589-601.
  3. Mallula, K., et al., Comparison of ductal stenting versus surgical shunts for palliation of patients with pulmonary atresia and intact ventricular septum. Catheterization and Cardiovascular Interventions, 2015. 85(7): p. 1196-1202.
  4. Nasef, M.A., et al., Short‐ and medium‐term outcomes for patent ductus arteriosus stenting in neonates ≤2.5 kg with duct‐dependent pulmonary circulation. Catheterization and Cardiovascular Interventions, 2022. 100(4): p. 596-605.
  5. Shahanavaz S, Qureshi AM, Petit CJ, Goldstein BH, Glatz AC, Bauser-Heaton HD, McCracken CE, Kelleman MS, Law MA, Nicholson GT, Zampi JD, Pettus J, Meadows J. Factors Influencing Reintervention Following Ductal Artery Stent Implantation for Ductal-Dependent Pulmonary Blood Flow: Results From the Congenital Cardiac Research Collaborative. Circ Cardiovasc Interv. 2021 Dec;14(12):e010086.