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Case series
LVIS Jr ‘shelf’ technique: an alternative to Y stent-assisted aneurysm coiling
  1. Elizabeth Hai Yen Du1,
  2. Jai Jai Shiva Shankar2
  1. 1Department of Diagnostic Radiology, Dalhousie University, Halifax, Nova Scotia, Canada
  2. 2Division of Neuroradiology, Department of Diagnostic Imaging, QE II Health Sciences Center, Halifax, Nova Scotia, Canada
  1. Correspondence to Dr Jai Jai Shiva Shankar, Division of Neuroradiology, Department of Diagnostic Imaging, QE II Health Sciences Centre, Halifax, Nova Scotia, Canada B3H 1E6; shivajai1{at}gmail.com

Abstract

Wide-necked bifurcation intracranial aneurysms have traditionally not been amenable to coil embolization with the use of a single stent due to the high risk of coil prolapse. Y-configuration double stent-assisted coil embolization (‘Y-stenting’) of this aneurysm type has been shown to have generally good clinical outcomes, although the technique is complex with various challenges described in the literature. The compliant and flexible closed-cell design of braided stents such as the LVIS Jr allows for the creation of a ‘shelf’ across the aneurysm neck sufficient to prevent coil prolapse. We describe this novel ‘shelf’ technique and present a small case series of LVIS Jr stent-assisted wide-necked bifurcation intracranial aneurysm coiling in eight patients. Our small, albeit important, case series demonstrates that the ‘shelf’ technique is feasible and safe with very good short-term clinical and angiographic outcomes, and may obviate the need for Y-stenting.

  • Aneurysm
  • Coil
  • Device
  • Intervention
  • Stent

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Introduction

Wide-necked bifurcation intracranial aneurysms have traditionally not been amenable to coil embolization with the use of a single stent due to the high risk of coil prolapse, particularly when the branch arteries are incorporated into the aneurysm dome. In recent years, Y-configuration double stent-assisted coil embolization (‘Y-stenting’) of this aneurysm type has been undertaken using combinations of open-open, open-closed, or closed-closed stents, with preservation of the parent circulation. Single and multicenter retrospective studies of this double stent technique have shown generally low complication rates and good clinical and angiographic outcomes.1–8 However, Y-stenting is technically complex and various challenges have been described in the literature.3–5 ,9

Braided stents such as the Low-profile Visualized Intraluminal Support Junior device (LVIS Jr; MicroVention-Terumo, Tustin, California, USA) have a compliant and flexible closed-cell design where the cell size varies with force applied along the length of the stent.10 This property of braided stents can be used to create a ‘shelf’ sufficient to prevent coil prolapse using a single stent at the neck of a wide-necked bifurcation aneurysm, obviating the requirement for Y-stenting.

The purpose of this study is to describe this novel ‘shelf’ technique using LVIS Jr stents and to report the safety and feasibility of this technique in a small case series of eight patients.

Materials and methods

With institutional ethics board approval, we retrospectively reviewed our prospectively maintained interventional neuroradiology database for use of LVIS Jr stent assistance in aneurysm coiling. We assessed aneurysms for their clinical presentation, size, neck diameter, and location. The ‘shelf’ technique had been used in all but one of these patients. We also assessed immediate post-coiling results, perioperative morbidity and mortality, and short-term follow-up of these patients.

General technique

Patients were pretreated with aspirin (81–325 mg/day by mouth given 3–7 days before the procedure) and clopidogrel (75 mg/day by mouth given at least 5 days before the procedure or as a loading dose of 600 mg given at least 2 h before the procedure). During the procedure, patients were administered intravenous heparin to maintain an activated clotting time of double the baseline and close to 250–300 s throughout. The clotting time was monitored at 60 min intervals during the procedure. After the procedure, patients were maintained on 81 mg aspirin/day and 75 mg clopidogrel/day for at least 3 months with one antiplatelet agent (aspirin) recommended for life. All procedures were performed by a single operator (JJSS). Most procedures were performed through a 6 Fr femoral access using standard commercially available guiding catheters and sheaths. The LVIS Jr device was used through a Headway 21 microcatheter (MicroVention-Terumo).

Shelf technique

The distal artery was first accessed using the Headway microcatheter and microguidewire. The LVIS Jr stent was back-loaded in the microcatheter and the first centimeter of the stent was deployed by primarily unsheathing while withdrawing the microcatheter. The rest of the stent was deployed by pushing on the pusher wire of the stent. After covering half of the neck of the aneurysm, the whole system (comprising stent pusher wire and microcatheter) was pushed forward, allowing the stent to open further. The stent was then deployed 1 mm at a time and the whole system was advanced to open the stent further. This was continued until the stent started to pooch at the neck of the aneurysm to form a ‘shelf’ (figures 13). Once the shelf was considered satisfactory (covering at least three-quarters of the neck of the aneurysm), the rest of the stent was deployed using the standard push technique. In many of the cases, at the point of the ‘shelf’, the stent was able to open to a diameter more than the known maximum unconstrained diameter (figures 1B,D,E and 3E). The stent was always checked for complete opening and absence of twisting using dyna-CT.

Figure 1

An LVIS Jr stent in a model wide-necked aneurysm (A, B) shows that creating a ‘shelf’ covering at least three-quarters of the neck of the aneurysm helps to prevent coil prolapse. CT reconstruction of a left internal carotid artery termination wide-necked aneurysm (C). An LVIS Jr stent is deployed in a ‘shelf’ formation in practice (D, E). The aneurysm then undergoes coil embolization (F).

Figure 2

A wide-necked basilar tip aneurysm (A) is coiled by advancing the microcatheter with the back-loaded LVIS Jr stent into the distal artery, deploying the stent slowly while pushing both the stent pusher wire and microcatheter forward so that the stent pooches and creates the desired ‘shelf’ formation (D, E), then embolizing with coils (F). This patient developed an in-stent thrombus during coiling (B) that dissolved (C) by the end of the procedure after treatment with abciximab. There was no associated clinical morbidity.

Figure 3

A wide-necked anterior communicating artery aneurysm on CT reconstruction and angiogram (A, B) is coiled (C, F) by advancing the microcatheter with the back-loaded LVIS Jr stent into the distal artery, deploying the stent, and pushing both the stent pusher wire and microcatheter forward while continuing to deploy the stent 1 mm at a time to create the desired ‘shelf’ formation covering at least three-quarters of the neck of the aneurysm (D, E).

The deployed LVIS Jr stent was then traversed with the same Headway microcatheter to allow for aneurysm coiling. All aneurysms were embolized with standard bare platinum or hydro coils. Angiography in standard branch projections and the working angles for coil embolization were performed before and after coil embolization. The aneurysms were followed using contrast-enhanced MR angiography. Aneurysms at the end of coiling and on follow-up were characterized using the Raymond–Roy (RR) classification.11

Results

The details of the aneurysms are given in table 1. The average aneurysm diameter was 7.7 mm (range 3–12 mm). All aneurysms were wide-necked with an average neck diameter of 5.5 mm (range 3–8 mm). The technical success rate for stent placement and aneurysm occlusion was 100%. At 3–15 months clinical follow-up and 2–10 months imaging follow-up, no coil prolapses have been identified. One patient developed an in-stent thrombosis discovered immediately post-procedure, which dissolved with the use of abciximab. Another patient required a second stent to be placed in the proximal segment of the parent artery to jail a stretched coil. Neither patient experienced clinical morbidity or mortality. These two cases accounted for a technical complication rate of 25%, but neither patient experienced clinical morbidity or mortality. Five of the eight aneurysms (62.5%) demonstrated RR2 occlusion initially, with the remaining three (37.5%) demonstrating RR3 occlusion. On imaging follow-up, five of the eight aneurysms (62.5%) demonstrated RR1 occlusion and three (37.5%) demonstrated RR2 occlusion. None of the patients needed retreatment.

Table 1

Characteristics of patients undergoing LVIS Jr ‘shelf’ technique-assisted wide-necked bifurcation aneurysm coiling

Discussion

We present what is to our knowledge a novel stenting technique, which we have termed the ‘shelf’ technique, using LVIS Jr stents in wide-necked intracranial bifurcation aneurysms. As the technique depends on the closed-cell design with mutable cell size properties of the LVIS Jr, other similar braided stents available should theoretically be compatible with this technique. In this technique the stents were able to open to a diameter more than the known maximum unconstrained diameter to create the ‘shelf’ (figures 1B,D,E and 3E). This is possible only because of the mutable cell size property of the braided stent like LVIS Jr. Open-cell stents such as the Neuroform device (Boston Scientific, Natick, Massachusetts, USA) are known to kink with the introduction of curvature,12 ,13 and thus run the high risk of cells tangling among themselves if used in this ‘shelf’ technique, particularly with acute bifurcation angles. Closed-cell non-braided stents such as the Enterprise device (Cordis Neurovascular, Miami Lakes, Florida, USA) lack the degree of mutability upon physical manipulation seen in braided stents, and do not achieve a configuration sufficient to prevent coil prolapse if used in single stent-assisted coiling of bifurcation aneurysms.

Of the eight patients who underwent coiling via the ‘shelf’ technique, none experienced immediate or up to 15 months clinical follow-up morbidity or mortality. The technical success rate for initial stent placement and aneurysm coiling was 100% with short-term follow-up negative for coil prolapse. One patient developed an asymptomatic in-stent thrombosis that resolved with use of abciximab. Similar in-stent thromboses have been seen with Y-stenting.2 ,4 One patient required placement of another stent in the proximal segment of the parent artery to jail a stretched coil, but otherwise also remained asymptomatic. The two technical complications were not specific to the described ‘shelf’ technique and are known complications for coiling or stent-assisted coiling of aneurysms. The initial occlusion rates progressed to 62.5% for RR1 and 37.5% for RR2 on short imaging follow-up, with none requiring retreatment. This is similar to the occlusion rates of 60–96% RR1 and 2–33% RR2 on imaging follow-up for Y-stenting.2 ,4 ,8 Thus, the ‘shelf’ technique appears to be a safe and effective alternative technique to Y-stenting based on the data from this small case series.

The advantage of the ‘shelf’ technique lies in obviating the need for placement of two stents at wide-necked bifurcation aneurysms, which is a technically complex procedure and includes challenges such as difficult navigation of the microcatheter into the contralateral branch artery across the struts of the first stent, kinking at the bifurcation point where branches diverge at acute angles, migration of the first stent during second stent insertion, difficult navigation of the microcatheter through the two stents, and increased risk of thromboembolic complications.3–5 ,9 Once operators are familiar with the pull and push mechanics of the ‘shelf’ technique, the LVIS Jr or potentially other braided stents can be placed with relative ease from the parent artery into one of the branch arteries.

There are several smaller studies describing other emerging alternative devices to treat wide-necked bifurcation aneurysms. A study of 19 wide-necked bifurcation intracranial aneurysms treated with the Barrel VRD (Medtronic Neurovascular, Irvine, California, USA) reported similar imaging follow-up aneurysm occlusion rates to ours, but four serious adverse events including ischemic stroke and subarachnoid hemorrhage.14 Treatment of 15 wide-necked bifurcation intracranial aneurysms with the unique arch design PulseRider stent (Pulsar Vascular, San Jose, California, USA) showed low procedural complication rates. Imaging follow-up was only available for three patients, but showed similar occlusion rates to ours.15 Results are varied for the WEB-DL braided wire intrasaccular flow diverter (Sequent Medical, Aliso Viejo, California, USA). A study of 45 wide-necked bifurcation intracranial aneurysms treated with the WEB-DL showed good short- to mid-term imaging follow-up occlusion rates of 56.8–69% RR1 and 20.7–24.3% RR2, albeit a retreatment rate of 7/45 (15.6%).16 However, when the WEB-DL was used to treat 15 very complicated wide-necked bifurcation aneurysms that the operators deemed untreatable with other techniques, imaging follow-up occlusion rates dropped to 0% RR1, 52.7% RR2, and the rest RR3.17 Assessment of 19 wide-necked bifurcation aneurysms treated with the pCONus self-expanding nitinol intrasaccular stent (Phenox, Bochum, Germany) showed a 75% combined RR1 and RR2 imaging follow-up occlusion rate, albeit a 25% recanalization rate and a 10.5% short-term morbidity rate.18 As new devices continue to emerge and evolve in the field of interventional neuroradiology, technical modification of existing devices (like the ‘shelf’ technique) to improve the safety and efficacy is certainly desirable.

There are two main limitations with this case series. First, all eight patients received stent placement by a single operator (JJSS). The described ‘shelf’ technique should be performed by other operators to assess efficacy, procedural ease, and interoperator variability. Second, as this is a relatively small case series with short-term follow-up, ideally this technique should be assessed in a larger sample group with longer-term follow-up to assess stent placement and coil performance.

Conclusion

Our small case series shows that the ‘shelf’ technique with LVIS Jr stents is a feasible and safe technique for the treatment of wide-necked intracranial aneurysms with very good short-term clinical and angiographic outcomes. This technique may obviate the need for Y-stenting at intracranial wide-necked bifurcation aneurysms.

References

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Footnotes

  • Contributors JJSS made substantial contributions to the conception and design of the work, acquisition, analysis, and interpretation of data for the work, had a major role in drafting the work and revising it critically for important intellectual content, approved the version to be published, and agrees to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. EHYD made substantial contributions to the acquisition, analysis, and interpretation of data for the work, had a major role in drafting the work and revising it critically for important intellectual content, approved the version to be published, and agrees to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • Competing interests JS is a proctor for LVIS Jr stents in Canada and has received an honorarium for his proctorship. He has also received a Microvention education grant.

  • Ethics approval Ethics approval was obtained from the Nova Scotia Health Authority Research Ethics Board.

  • Provenance and peer review Not commissioned; externally peer reviewed.