SHA24/071001

Stent choices for paediatric cardiac catheterisation Shakeel A Qureshi Evelina Children’s Hospital London GHA/SHA, Riyadh, February 2013

Stents in Congenital Heart Disease Issues:

• Used in many defects – Aorta – Pulmonary arteries – Vena cava – Pulmonary veins – RVOT – Arterial ducts

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Vessel recoil

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Vessel kink

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Vessel extrinsic obstruction

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Vessel stretch

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Acute post-operatove lesions

Ideal stent characteristics – High radial strength to avoid recoil of the vessel – Low profile of stent and delivery system (Premounted stents) – Flexibility – Good visibility – Ability to redilate in future for growth – Minimal foreshortening – Retrievable – Open cell design and wide struts to allow access to side branches – Rounded edges – Biodegradable

Requirements in Paediatric Cardiology – Ability to dilate to larger diameters

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Recent designs focus on: •

Foreshortening

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Flexibility

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Radial strength

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Low profile

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Trackability

– Flexibility

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Biodegradability

– Retrievability

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Rounded edges

– Maintain radial strength at large diameters – Low profile for use in smaller children

– Access to side branches

Stent designs • Stents made of: – Stainless steel 316L – used for balloon-expandable stents – Cobalt-based steels (cobalt alloyed with chromium and molybdenum) – Tantalum – Platinum (alloyed with iridium or tungsten) – Nickel-titanium alloys – Polymers – Biodegradable materials

Stents in Paediatric Cardiology Many balloon expandable stents are available: • Palmaz Genesis • Intrastent • Valeo • Cheatham-Platinum (bare and covered) • Andrastent • V12 Atrium (bare and covered) • Sinus Superflex

Stent : designs Material: stainless steel, cobalt, platinum, titanium, biodegradable material Self expandable: flexible, lower profile, conforms to vessel, less radial strength Bare stent/Covered stent: Unmounted (Hand-crimped) or Premounted Cell design: closed or open cells Open cell: flexible, less shortening, access to side branches Disadvantages: less scaffolding, more tissue prolapse, more recoil

Closed cell

Open cell

Courtesy: Caroline Ovaert

Stent designs •Bare stent – Covered stent Unmounted (Hand-crimped) or Premounted •Cell design: closed or open or hybrid cells

Hybrid cells (closed and open)

CP stents (bare or covered)

Stent designs Closed cell • Palmaz generations: Corinthian, Genesis, Palmaz Blue • Cheatham-Platinum • Advanta V12

On expansion cells maintain consistent shape Cell geometry consistent and cells complete

Stent designs Open cell • Intrastent Doublestrut LD • Jomed Wavemax • AVE Bridge • Herculink • Omnilink • Valeo

Stents Balloon expandable stents: •

Small - expandable to 4-5 mm diameter – Wide range of stents available

– Rapidly evolving technology – Covered or bare – Usually premounted – Primarily used in coronary arteries and other peripheral vessels – In ducts or RVOT in neonates

– Medium - expandable to 10-12 mm diameter – Large - expandable to 18 mm diameter – Extra large - expandable to 25 mm diameter

Small stents – cannot be overexpanded 8.0mm balloon

6.0mm balloon

8.0mm balloon 5.0mm balloon

M ax diameter 6.4 mm Courtesy: Frank Ing

Comparison of Genesis medium and large stents Max balloon size: 10 mm Max stent diam: 8.0 mm

Max balloon size: 14 mm Max stent diam: 12.3 mm

Extra large stents at 24 mm diameter

Maxi LD

Palmaz XL

CP 8-zig

Variety of stents • Medium – Genesis medium, Visipro – up to 10 mm • Large – – Genesis XD, Doublestrut LD, Mega LD, Andrastent XL – up to 18 mm – Jomed – up to 14 mm

• Extra large – P4014, 5014, Maxi LD, CP, Andrastent XXL

Stent: medium Dilatable up to 10 or 12 mm Omnilink (Guidant): stainless steel, length 12-58 mm premounted, 5-10 mm balloon, min 6F dilatable to 12 mm with no FS, open cell Valeo ‘medium’: stainless steel, open cell design premounted on 6-8 mm balloons: 6F length: 18, 26, 36, 56 mm dilatable to 13 mm (fracture > 13 mm), no foreshortening, open cell

Courtesy: Caroline Ovaert

Stent : Large Palmaz Genesis XD (19,25,29,39,59)

Dilatable up to 18 mm

Intrastents LD Mega (16,26,36)

Valeo ‘large’ (18,26,36,56)

Unmounted

Unmounted

Premounted (9 or 10mm): 7F

Stainless steel

Stainless steel

Stainless steel

10-12  18mm

9  18mm

9 or 10  20 mm

Flexible, rounded edges

Flexible, rounded edges

Flexible

Closed cells

Open cells

Open cells

good radial strenght

 less radial strength

 poor strength

FS: 35-38% (serial) at 18 mm

FS: single 35%, serial 8.5% at 18 mm

No FS if serial

 circumferential fractures

 easy distortion or fracture

Courtesy: Caroline Ovaert

Stent : Extra Large:

Dilatable up to 25 mm

Palmaz XL 4014, 5015

Intrastents LD Max (16,26,36 mm)

CP 8 zigs (16,22,28,34,39,45 mm)

Andrastent XL & XXL (13 to 57 mm)

Unmounted

Unmounted

Unmounted or premounted

Unmounted

Stainless steel Stainless steel

Platinum/iridum

Cobalt chromium

14 to 25

9 to 25

8 to 24

15-25 mm 20-32 mm

Closed cells

Open cells

Closed cells

Hybrid cell design

Rigid

Flexible

Robust, flexible, rounded edge

flexible

FS: 25% at 25 mm

FS: < 20% when serial

FS: 35% at 24 mm, 14% at 18 mm

FS XL: 35% at 25 mm, < 10% at 18 mm

Foreshortening of stent Closed cells serial vs direct dilation Genesis XD 2510 (large stent): serial dilation

Ing et al.

Foreshortening of stents Open cells Mega LD: serial vs direct dilation (18 mm)

Serial

Direct

Ing et al.

Foreshortening Open cells

Valeo large stent : effect of serial dilation

Ing et al.

Side branch occlusion Open vs Closed cell design 10 mm balloon

Mega LD

6 mm balloon

Genesis

Palmaz

Maximum dilation of cells in large stents

Ing et al.

Stent shortening at 12 mm diameter

Stents in pulmonary artery stenosis Naturally occurring RPA stenosis

Pulmonary artery stenosis post trunk repair In an infant

Oversized Palmaz stent

Covered stent in coarctation & PDA

Stents in IVC pathway

IVC stenting after Fontan operation

Corinthian PDA stent after RF

Bilateral PA stenting

Simultaneous bilateral PA stenting

Genesis closed cell stents

Bare stents and intimal proliferation Factors affecting histological restenosis studies due to intimal hyperplasia •

Stent design (strut thickness, number of struts per crosssection, and strut design)

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stent material

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surface smoothness

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Thin struts with a corrugated ring stent design found to induce the least intimal hyperplasia thickness between tested metal stents.

Hoffmann R, et al. Relation of stent design and stent surface material to subsequent in-stent intimal hyperplasia in coronary arteries determined by intravascular ultrasound. Am J Cardiol 2002;89:1360–1364

Open cell stent in pulmonary artery

Open cells allow tissue prolapse, so may allow intimal proliferation

Intimal proliferation

Covered Stents ePTFE : stretchable Gor-Tex

Covered CP stent (Numed)

Advanta (V12) (Atrium)

Graftmaster Jostent (ABOTT, coronary stent, 3-4 & 4,5-5,5)

Cheatham-Platinum stents

unmounted

Length 16,22,28,34,39,45 mm Anything longer is custom made

premounted

Advanta V12 OTW LD (Atrium) •Stainless steel encapsulated by ePTFE on both sides •Guidewire lumen : 0.035” •Balloon: 12, 14, 16 mm •Sheath: 9Fr (12) - 11Fr (14-16) •Usually better to have 1Fr more •Length: 29, 41, 61 mm •Can be expanded up to 22 mm in steps of maximum 4mm (foreshortening 25%) •Flexible but recoil is an issue

Balloon has long shoulders

Advanta V12 RX (Atrium) • Premounted 5-7 mm, lengths 16, 21, 24 mm •Low profile (6, 7 Fr) •0.014” guidewire •Can be post-dilated to 8 mm

Advanta V12 OTW (Atrium) • Premounted 5-10 mm, lengths 16, 22, 38, 59 mm •Low profile (5, 6 Fr) •0.038” guidewire •Can be post-dilated to 12 mm

Andrastent (Andramed) •

Cobalt chromium stent

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Hybrid cell design (open and closed cells) makes it more flexible

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XL and XXL stents Stent lengths available: 13 mm , 17 mm, 21 mm, 26 mm, 30 mm, 35 mm, 39 mm, 43 mm, 48 mm, 57 mm

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XL – dilation between 15 and 25 mm

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XXL – dilation range between 20 and 32 mm

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Has been used in most indications for CHD

Andrastent (Andramed) • 12 zig or 15 zig design • Used also in RVOT prestenting prior to Melody valve • No fractures so far

Self-expanding stents • Very flexible • Low profile • Cannot be crushed • Conform to the curved vessel • Made of nitinol or cobalt-chromium alloy • Less radial strength than balloon expandable stents

Wallstent Braided wire tube of cobalt-chromium

SMART/Precise stent One piece laser cut nitinol tube construction

0.087â&#x20AC;?

Peak to valley design

0.13â&#x20AC;?

6 Tantalum micromarkers at each end

Self-expanding stents Wallstent Design Metal alloy Sizes Sheath Foreshortening Radial strength

Braided wire tube Elgiloy (cobalt-cromium) 5-24mm diam;

6-11 Fr

SMART/Precise stent Single piece laser cut tube;MicroMesh geometry / segmented design

Nitinol 5-10 mm diam;

5-6 Fr sheath

Significant!

Less than balloon expandable stents

Approx 8%

Sinus superflex stents • Self-expanding • Low profile • Used in stenting PDAs in duct-dependent circulation

Sinus Superflex DS stents •

Radio-opaque markers, braided sheath

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Anti-jump mechanism, self-expanding

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Low profile

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Used in hybrid procedures

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7-9 mm diameter, 15 – 20mm lengths, 0.018” guidewire

Hybrid procedure for HLHS

Sinus Superflex DS stents Hybrid PDA stent

Conforms to the vessel curve

Sinus Repo DS stents •

Radio-opaque markers, braided sheath

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Anti-jump mechanism, self-expanding

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Low profile

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Used for coarctation (or PDA stenting in ductdependent pulmonary circulation)

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5-6 mm diameter, 9 mm length, 0.018” guidewire

Biodegradable stents • Stent designs to overcome growth of patient • Degradable stents e.g polylactic acid – PLLA (Igaki-Tamai stent) – self expanding) • Magnesium stents (AMS biotronik, Mg stability for 8 days only) • PDS (polydiaxonone suture)

After subclavian flap

After AMS stent (3.5x10mm)

After 2 weeks

After AMS stent (4x10mm) Schranz CCI 2006

Biodegradable stents SX Ella stent • Used in bronchi and oesophageal strictures • Made of PDS • Integrity and radial strength maintained for 6-8 weeks • Degrades after 11 – 12 weeks

Biodegradable stents Ella stent • Available between 18 – 25 mm diameter for oesophagus (18 – 28 Fr sheath) • Custom made 6 to 8 + mm diameter for bronchi (16 Fr sheath)

Stents in Congenital Heart Disease •

Aortic coarctation and

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recoarctation

Older children, adolescents and adults

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Branch pulmonary arteries

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Any age

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Caval veins – superior and

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Older children, adolescents

inferior

and adults

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Right ventricular outflow tract

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Any age

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Patent arterial duct

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Neonates

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Aorto-pulmonary collaterals

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Any age

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Bronchi

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Usually in infancy