Anterior Cerebral Artery (A1 Segment) Aneurysm: The eCLIPs Endovascular Clip System, a Novel Flow Diversion Approach to Managing Intracranial Aneurysms Arising from Arterial Bifurcations
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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.
KeywordsAnterior cerebral artery Internal carotid artery bifurcation Flow diversion Bifurcation aneurysm Coils eCLIPs
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.
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.
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)
Duration: 1st – 16th DSA run: 124 minutes; fluoroscopy time: 41 min
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.
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.
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).
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.
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