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Anterior Cerebral Artery (A1 Segment) Aneurysm: The eCLIPs Endovascular Clip System, a Novel Flow Diversion Approach to Managing Intracranial Aneurysms Arising from Arterial Bifurcations

  • Ghouth Waggass
  • Saba Moghimi
  • Joost De Vries
  • Thomas R. MarottaEmail author
Living reference work entry
  • 170 Downloads

Abstract

Aneurysms arising from or adjacent to arterial bifurcations are challenging to treat and show a high recurrence rate after traditional endovascular treatment. The high prevalence and the unique structural and hemodynamic characteristics of aneurysms at arterial bifurcations call for dedicated treatment approaches. The endovascular clip system (eCLIPs, Evasc) is a novel device, which enables flow diversion away from the aneurysm sac and is shown to induce physiological remodeling with eventual sealing of the aneurysmal neck. We will discuss the application of eCLIPs for managing an anterior cerebral artery (ACA) aneurysm arising from the proximal A1 segment in a 49-year-old female patient. The medium-sized lobulated unruptured aneurysm adjacent to the right internal carotid artery (ICA) bifurcation was discovered incidentally and was treated with eCLIPs and coiling. Immediate flow stagnation in the aneurysm was observed after the uneventful deployment of eCLIPs. Loose coiling through eCLIPs was performed successfully with a small neck remnant. Follow-up after 6 months showed complete occlusion of the aneurysm. The use of eCLIPs is the main topic of this chapter.

Keywords

Anterior cerebral artery Internal carotid artery bifurcation Flow diversion Bifurcation aneurysm Coils eCLIPs 

Patient

A 49-year-old woman presented with mild traumatic brain injury for which a head CT was performed. An incidental right proximal A1 segment aneurysm adjacent to the ICA bifurcation was noted on CT and a decision was made to treat the aneurysm endovascularly.

Diagnostic Imaging

The right ICA angiogram revealed the proximal A1 aneurysm. The aneurysm was near the right ICA bifurcation pointing posteriorly and superiorly with at least three visible lobules. The aneurysm measured 8.5 × 6 × 4.5 mm in diameter with the neck measuring 2.5 mm (Fig. 1).
Fig. 1

Preprocedural digital subtraction angiography (DSA) of the right ICA in posterior-anterior view (a), right anterior oblique view (b), and 3D reconstruction (c) reveals a lobulated aneurysm at the right proximal A1 segment pointing posteriorly and superiorly

Treatment Strategy

To treat the aneurysm with eCLIPs-assisted coiling with the A1 segment being the first branch where the deployment starts and the M1 segment being the second branch where the deployment ends using the right ICA as the parent artery for access. The flow is preserved in both the ACA and the MCA throughout the procedure.

Treatment

Procedure, 16.10.2014: eCLIPs-assisted coil occlusion and flow diversion of an unruptured proximal right A1 aneurysm adjacent to the right ICA bifurcation

Anesthesia: general anesthesia, target activated clotting time of 2–3.5 times the baseline was achieved using 5000 IU unfractionated heparin (LEO Pharma, B.V., Amsterdam, Netherlands) IV

Premedication: 10 mg oxazepam PO; patient received 325 mg aspirin daily 5 days prior to the procedure including the day of intervention, and 10 mg prasugrel (Efient, Daiichi Sankyo) daily 5 days prior to the procedure including the day of treatment

Access: right common femoral artery, 1× 8F sheath (Terumo), an 8F Angioseal (Terumo) was used for closure; guide catheter: 1× 6F Neuron MAX 90 cm (Penumbra); intermediate catheter: 1× Navien A+ 072, 115 cm (Medtronic); microcatheter: 1× eCLIPs micro-introducer (Evasc), 1× eCLIPs micro-catheter (Evasc). Excelsior SL10 (Stryker) for coils; microguidewire: 1× Asahi Chikai 0.014″ (Asahi)

Implants: flow diverter: 1× eCLIPs (Evasc); coils: Target 360° Soft 4/10; Target 360 ° Ultra 3/6; Target 360° Nano 3/6 (all Stryker)

Course of treatment: The eCLIPs device and delivery system were prepared as per instructions. The eCLIPs micro-introducer and the Asahi Chikai 0.014″ microguidewire were navigated to gain access to the right A1 segment under roadmap control (Fig. 2a). The eCLIPs microcatheter was tracked over this, to a position in the right A1 segment. Both the microguidewire and the eCLIPs micro-introducer were removed from the eCLIPs microcatheter. An Asahi Chikai 0.014″ microguidewire was then loaded into the eCLIPs Bifurcation Remodeling System, which delivers the eCLIPs device. The above combination was entered into and advanced through the eCLIPs microcatheter. The anchor of the eCLIPs device was deployed into the right A1 segment with attention to the device’s axial and rotational orientations by aligning the device markers, a crucial step in successful deployment. After achieving the optimal orientation, the device was fully unsheathed into the A1 segment and partially into the ICA. The microguidewire was pulled back toward the delivery hypotube and advanced into the right MCA (Fig. 2b). The eCLIPs was advanced along the wire and the device was placed into the M1 segment with careful attention to the device orientation across the neck. After gaining the optimal orientation and aneurysm neck coverage, the eCLIPs detacher was used to detach the eCLIPs device from the delivery hypotube. Throughout the procedure and before detachment, the device was fully resheathable and could be repositioned or fully retrieved at any time. The post-deployment angiographic DSA run showed flow stagnation with an O’Kelley-Marotta (OKM) (O’Kelly et al. 2010) grade of A3 (Fig. 2c).
Fig. 2

eCLIPS implantation: A1 segment access and beginning of the deployment of the anchor of the eCLIPs (a); the guidewire is navigated to the right MCA after deployment of the anchor with well-aligned markers (b); well-positioned eCLIPs across the aneurysm with flow stagnation in the aneurysm sac (c)

The eCLIPs microcatheter, the pusher, and the Asahi Chikai microguidewire were removed. An Excelsior SL10 straight microcatheter was navigated over the Asahi Chikai microguidewire and through the eCLIPs leaf segment into the aneurysm sac. The coiling was performed using Target (Stryker) coils achieving a Raymond 2 level of occlusion (Fig. 3). Final DSA run ruled out any thromboembolic complications. The aneurysm was rated to be an OKM grade B3, upon completion of the procedure. A schematic summary of the eCLIPs deployment is given in Figs. 4 and 5 showing the same process in a transparent model.
Fig. 3

Coiling of the aneurysm through the eCLIPs

Fig. 4

Schematic representation of the deployment steps of the eCLIPs, followed by a catheterization and coil occlusion of the aneurysm sac

Fig. 5

Deployment of an eCLIPs in a bifurcation aneurysm model: first branch guidewire access (a), first branch micro-introducer navigation (b), first branch microcatheter navigation (c, d), eCLIPs device and guidewire navigation (e), deployment into parent artery (f, g), second branch guidewire navigation (h), deployment into second branch covering the aneurysm neck (i), detachment (white circle) (j, k), withdraw (l, m), final result (n)

Duration: 1st – 16th DSA run: 124 minutes; fluoroscopy time: 41 min

Complications: none

Postmedication: The patient continued receiving the dual antiplatelet therapy (325 mg aspirin and 10 mg prasugrel PO daily) for 3 months; prasugrel was stopped at 3 months and the patient continued on a regimen of aspirin monotherapy indefinitely.

Clinical Outcome

There were no periprocedural or late complications at the 6 months and 1 year follow-up investigations with a National Institute of Health Stroke Scale (NIHSS) and modified Rankin scale (mRS) score of zero.

Follow-up Examinations

A 6-month follow-up angiogram (Fig. 6) revealed a complete obliteration of the aneurysm (Raymond 1, OKM D1). Complete healing is thought to be due to the flow diversion and the endothelial remodeling effect promoted by the eCLIPs device.
Fig. 6

Immediate postprocedure angiogram, which showed minimal neck remnant (a), and 6 months follow-up DSA, which revealed complete obliteration of the A1 aneurysm (b)

Discussion

Aneurysms arising from arterial bifurcations are challenging to treat and show a significant recurrence rate when using current endovascular approaches. Different strategies are used to treat such aneurysms including standard coiling, double or triple microcatheter techniques, or modified coils such as the Medina device (Medtronic) (Baxter et al. 1998; Cho et al. 2015; Henkes and Weber 2015). Various stent-assisted coiling strategies have been used for vascular reconstruction and protection of the aneurysm neck either by using one stent or more with different crossing and kissing techniques (i.e., Y-, T-, X-stenting), which are usually technically challenging. A less frequently used suboptimal stent-assisted technique is the waffle cone approach where the distal end of a self-expandable stent is deployed within the aneurysm (Padalino et al. 2013). Balloon-assisted coiling has also been used to treat aneurysms arising from arterial bifurcations (Pierot and Wakhloo 2013).

The shortcomings of the aforementioned techniques led to development of variable innovative devices to treat such aneurysms. These are divided into modified stents such as the pCONus (phenox) and the PulseRider (Pulsar Vascular, Cerenovus), which have a stent shaft deployed in the parent vessel and distal splayed petals or wing-like segments. The distal part of these stent derivates is deployed either inside the aneurysm (pCONus) at the aneurysm neck or into two efferent branches (PulseRider) and supports the subsequent coil occlusion. The Barrel Vascular Reconstruction Device (Medtronic) is a detachable stent, which has a central belly that projects into the aneurysm orifice to assist coiling. These devices have little if any hemodynamic effect on the aneurysm. Another category is intra-aneurysmal flow disruptors such as Woven EndoBridge (WEB; MicroVention) and pCANvas (phenox).

The Endovascular Clip system (eCLIPs; Evasc Medical Systems) is a novel neck bridging device which uses flow diversion to manage aneurysms at arterial bifurcations and is shown to induce physiological remodeling and possible sealing of the aneurysmal neck (Marotta et al. 2018). The eCLIPs is an implantable nickel-titanium device that can be deployed at the aneurysm neck. The second-generation eCLIPs, used in this case, is self-expanding, fully retrievable, and is deployed using a microcatheter. The device works on a one-size-fits-all basis and is composed of two segments, namely, the anchor that is designed to imitate the shape of the arterial wall and hold the device in place, and the leaf segment that allows flow diversion away from the aneurysm to reduce the risk of recurrence (Fig. 7).
Fig. 7

eCLIPs device: 3D view (a), side view (b), plan view (c)

One of the unique features of the eCLIPs is the ability of the device to promote physiological remodeling. Initial testing in rabbit models, with pathology and electron microscopy investigations, demonstrated the ability of the eCLIPs to induce physiological remodeling (Marotta et al. 2018). Both leaf and anchor of the “clip” can act as a scaffold upon which epithelial growth can occur. As the device gets incorporated into the vessel wall, complete closure of the aneurysm neck may ensue. In addition to remodeling, on days 30 and 90 postimplantation, progressive thrombosis formation was detected within the aneurysm sac (Marotta et al. 2018). The intra-aneurysmal thrombus formation along with physiological sealing of the aneurysm neck may contribute to flow stasis and may reduce the risk of recurrence. Like with other neurovascular stents, dual antiplatelet medication for 3 months followed by mono-antiaggregation for life is recommended.

The recently published initial clinical series using eCLIPs showed comparable aneurysm occlusion rate to the other bifurcation coil support device initial experiences. For eCLIPs, there were no documented cases of worsening in the Raymond grade. Among the 21 successfully treated patients with available data, who had late follow-up, the modified Raymond Roy classification (MRRC) grade was I in 7 (33%), II in 10 (47%), IIIa in 2 (9%), and IIIb in 2 (9%) (Chiu et al. 2018).

The foregoing experience included all cases, including several that were done on compassionate grounds without following the strict indications for use criteria for which eCLIPs was intended. As of December 31, 2017, among 38 cases done following indications for use criteria, however, none showed Raymond 3 scores at any follow-up timeframe (Ricci et al. 2017).

The use of eCLIPs as a means of flow diversion has multiple advantages to offer. These “clips” are flexible and easy to deploy and are associated with a low risk of perforation due to reduced manipulation of the weak aneurysm wall. These advantages and the potential for promoting epithelial remodeling make the eCLIPs a promising device for the hemodynamic treatment of aneurysms arising from or adjacent to arterial bifurcations.

Cross-References

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Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  • Ghouth Waggass
    • 1
  • Saba Moghimi
    • 1
  • Joost De Vries
    • 2
  • Thomas R. Marotta
    • 3
    Email author
  1. 1.Faculty of MedicineUniversity of TorontoTorontoCanada
  2. 2.Radboud UniversityNijmegenThe Netherlands
  3. 3.Department of Medical Imaging, Diagnostic and Therapeutic NeuroradiologySt. Michael’s Hospital University of TorontoTorontoCanada

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