New Tools for Complex Endovascular Interventions

In the last decade the arrival of new endovascular material and tools has allowed us to perform percutaneous interventions more safely (complicatgion rate <4%) (2), and especially more

efficaciously (technical success rate >90 %). These improvements have led to a high penetration of different types of endovascular interventions in the vascular community, which now proposed this minimally invasive approach for the vast majority of lesions and patients subsets (2).

Herewith, a short summary of different types of specific endovascular tools actually at diposal of every endovascular specialists.

3.3.3.1 Crossing devices:

The oldest and the more studied crossing device for endovascular interventions is the Excimer Laser™ (Spectranetic, Colorado Spring, CO, USA, Figure 11). The Excimer Laser™ has been associated with a good technical success rate when dealing with long femoro-popliteal occlusions as well as BTK occlusions (162). Because the Excimer Laser™ does not garantee an intraluminal recanalization (i.e. subintimal passage still possible and relatively frequently observed), is expensive, requires a special training, and finally because after a laser recanalization the restenosis occurrence may be as up as after a conventional balloon recanalization, this tool should be reserved for very high volume tertiary centers or for scientific purposes.

Figure 11: Excimer Laser™ (Spectranetic, Colorado Spring, CO, USA) [Reproduced from Bonvini RF et al. (160)]

More recently other crossing devices have arrived on the market: the Frontrunner™ XP (Cordis, Miami, FL, USA, Figure 12A) (163) and the Crosser™ (FlowCardia, Inc., Sunnyvale, CA, USA, Figure 12B) (164). The Frontrunner™ XP uses a micro-dissector, which creates an intraluminal channel in the occluded vessel, which will finally be dilatated and stented in a standard fashion. The Crosser™

uses a system of high frequency ultrasound vibrations which generates a mechanical impact on the

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occlusion’s stump. This vibrational effect should allow a more comfortable intraluminal passage in the occlusion. Despite, these theoretical benefits, so far the clinical results are quite disappointing, with a subintimal passage rate still elevated (164). Accordingly, both systems should be reserved, for the moment, for research purposes or for very selected patients or interventions.

Figure 12:

A: Frontrunner™ XP (Cordis, Miami, FL, USA) B: Crosser™ (FlowCardia, Inc., Sunnyvale, CA, USA)

[Reproduced from Bonvini RF et al. (160)]

3.3.3.2 Reentry devices:

When the intraluminal recanalization, especially of a long SFA occlusion, is impossible especially because of extensive calcifications, a subintimal recanalization may be attempted. This subintimal technique, firstly described by Bolia et al. in 1990 (165, 166), may be challenged especially when the reentry in the true lumen, distally the occlusion, is difficult to obtain (167, 168). Accordingly, an important step forward in the subintimal recanalization technique, was the arrival of different reentry devices. These reentry devices were aimed to facilitate the reconnection between the subintimal with the distal intraluminal space, in order that after the entry and the reentry points, as well as the entire subintimal passage may be dilatated or stented in standard fashion. The first reentry catheter which has proved its safety and efficacy was the Outback™ catheter (Cordis, Miami, FL ; USA, Figure 13)

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(167, 169), followed few years after by the Pioneer™ catheter (Medtronic, Santa Rosa, CA, USA, Figure 14) (170).

Figure 13A: subintimal recanalization technique;

13B: Outback™ reentry catheter (Cordis, Miami, FL; USA) [Reproduced from Bonvini RF et al. (160)]

Figure 14: Pioneer™ US-guided reentry catheter (Medtronic, Santa Rosa, CA, USA) [Reproduced from Bonvini RF et al. (160)]

Thanks to these reentry devices, nowadays the subintimal recanalization has become one of the most adopted recanalization techniques, especially by dealing with long SFA occlusions, because the creation of a subintimal passage is usually more easily obtained than to remain intraluminal, especially in case of severe SFA calcifications. Accordingly, in case of reentry failure with standard techniques, these catheters allow a rapid and safe reentry in more then 90% of the cases (167, 169).

The Pioneer™ catheter, thanks to an integrated ultrasound piece, is more sophisticated and expensive. This ultrasound piece allows a direct visualization of the reentry zone, thus allowing an unltrasound guided puncture as close as possible to the reentry zone. Conversely, the Outback™

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catheter may be used only under fluoroscopic guidance and thus is sensibly easier to use and less expensive. Efficacy of both system is similar, even if a direct comparison has never been performed, and both systems may be used, with caution, also at iliac or infra-popiteal level.

3.3.3.3 Debulking devices:

The rational for using a debulking device, especially in the femoro-popliteal regions, is that the femoral and the popliteal arteries are very frequently severly dieseased with a huge amount of atherosclerosis on the arterials’ walls. Accordingly, it is not surprising that during balloon angioplasty of such a long and diseased segments, intimal wall dissections, important elatic recoils or lesions underexpansion may oftenly occur, render conventional balloon angioplasty at that level frequently unsatisfactory. Atherectomy devices are aimed to debulk as much as possible of atherosclerotic material from the arterial wall, in order to obtain a significant lumen gain without the balloon

angioplasty associated barotrauma, thus finally reducing the risk of dissection or other adverse events (Figure 15).

Figure 15: showing the theoretical advantages of atherectomy compared to balloon angioplasty or stenting [courtesy of Prof. Zeller Th., Bad Krozingen, Germany]

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Atherectomy may be performed in several ways with different atherectomy devices. Following a short summary of the most used atherectomy devices and techniques:

Directional atherectomy using the Silverhawk™ device (ev3, Paris, France, Figure 16), rotational atherectomy with aspiration using the Pathway PV Atherectomy system™ (Pathway medical, Redmond, WA, USA, Figure 17A-B), orbital atherectomy using the Diamondback 360° Orbital Atherectomy device (Cardiovascular system, StPaul, MN, USA, Figure 17C-D) and finally the high speed rotational atherectomy using the Rotablator system™ (Boston Scientific, Natick, MA, USA, Figure 17E-F).

Figure 16: Silverhawk™ device (ev3, Paris, France), with the collected atheroma [reproduced from Bonvini RF et al. (160)]

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Figure 17: A-B: Pathway PV Atherectomy system™ (Pathway medical, Redmond, WA) C-D: Diamondback 360° Orbital Atherectomy device™ (Cardiovascular system, StPaul, MN) E-F: Rotablator system™ (Boston Scientific, Natick, MA) [reproduced from Bonvini RF et al.

(160)]

So far the Silverhawk™ device is one of the most used atherectomy devices in high volume centers because efficacious by removing plaques (Figure 18) and relatively user friendly. Accordingly, it is considered by several experts as the first-line treatment in case of severly and diffuse SFA disease, for small size SFA and for all similar situations in which an extensive stenting strategy should be avoided and where a simple balloon angioplasty attitude would be associated with a prohibitive restenosis rate. By using the Silverhawk™ device, also in diffuse SFA lesions, the bailout stenting may be reduced to <10%, with a very promising restenosis rate especially for the « de-novo » lesions in diabetic patients (171, 172). The combination of an atherectomy device followed by a DEB angioplasty seems very attractive, and it is actually under investigation.

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Figure 18 showing removal of different plaque material at the femoro-popliteal level [courtesy of Prof. Zeller Th., Bad Krozingen, Germany]

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