Utility of bulging technique for endovascular treatment of small and wide-necked aneurysms with a Low-profile Visualized Intraluminal Support (LVIS Jr.) device: A case report and review of the literature

Abstract

Small and broad-necked aneurysms are generally very difficult to treat using endovascular therapy. The arrival of the low-profile stent (e.g., Low-profile Visualized Intraluminal Support; LVIS) has enabled reconstructive treatment for these aneurysms. In addition, the bulging technique using LVIS is an effective and attractive technique for performing stent-assisted coiling to preserve parent arteries and achieve neck coverage. We report here a patient with a small and wide-necked ruptured basilar artery (BA) top aneurysm, in whom successful treatment was achieved by stent-assisted coiling with LVIS Jr. using the bulging technique. A 74-year-old woman with moderate hypertension consulted for treatment of subarachnoid hemorrhage with a ruptured BA top aneurysm measuring 2.7 mm in height with a 4.3 mm neck. We initially tried emergency balloon-assisted coiling, but coiling proved difficult. We therefore performed stent-assisted coiling with LVIS Jr. using the bulging technique. The postoperative course was uneventful, with no aggravation of neurological symptoms, and the patient was discharged 14 days postoperatively. This treatment strategy with LVIS Jr. using the bulging technique may be very useful for patients with a ruptured aneurysm with a small and broad neck that would otherwise require treatment with intravascular devices or open surgery.

Introduction

Recent rapid advances in endovascular technology have allowed neuro-interventionalists to treat complex cerebral aneurysms safely and effectively. Nonetheless, small, wide-necked and other complex intracranial aneurysms remain very difficult to treat by endovascular therapy and present various challenges. Specifically, broad-necked aneurysms present a significant risk for prolapse of coils into the parent artery, which can result in devastating thromboembolic or ischemic sequelae.^1–4 Since Higashida et al. first reported placement of an intravascular stent for assistance with coil embolization of a ruptured intracranial aneurysm, stent-coiling techniques have been a cornerstone of the armamentarium available to neuro-interventionalists. ⁵ Several successive generations of stents have been developed. One of the most recently released stents is the Low-profile Visualized Intraluminal Support device (LVIS and LVIS Jr., MicroVention Inc, Aliso Viejo, CA, USA). This microstent offers several potential advantages over other traditional stents.^2–4 We present herein a case of ruptured basilar artery (BA) top aneurysm, in which successful treatment was achieved by stent-assisted coiling with LVIS Jr. using the bulging technique.

Case report

A 74-year-old woman who was previously diagnosed with moderate hypertension presented with an acutely ruptured aneurysm measuring 2.7 mm in height with a 4.3 mm neck at the top of the BA, with the proximal BA measuring 2.8 mm in diameter and distal posterior cerebral artery (PCA) measuring 2.2 mm in diameter (Figures 1 and 2(A) and (B)). Consciousness was clear and muscle strength was normal. Endovascular treatment using balloon-assisted coiling was initially attempted emergently, but we could not complete coil embolization because this aneurysm was small and broad-necked. We therefore scheduled stent-assisted coil embolization two days after onset. First, a 6-Fr Launcher guiding catheter (Medtronic Vascular, Danvers, MA, USA) was inserted into the femoral artery and advanced until the tip reached the right vertebral artery (VA). This procedure was performed bilaterally. A Headway 17 microcatheter (MicroVention Inc, Aliso Viejo, CA, USA) was navigated over a CHIKAI 0.35-mm (0.014 in) microwire (Asahi Intec, Aichi, Japan) via the right VA into the right PCA, and a Neuroduo-10® microcatheter (Medico’s Hirata Inc, Osaka, Japan) was placed in the aneurysm to perform the jailing technique via the left VA. A 3.5 × 18 mm LVIS Jr. was gently deployed across the neck of the aneurysm. We applied intermittent forward tension while deploying the stent, and widened the stent across the aneurysm neck providing a buttress for the left PCA ostium (Figure 3(A)). That is, we succeeded in expanding a segment of the LVIS Jr. into the aneurysm neck, protecting the parent vessel and the bifurcation using bulging technique. Just after stent placement, the patient was administered 330 mg of aspirin and 80 mg of ozagrel. After confirming a good crimp and herniation into the aneurysmal neck of the stent strut on cone beam computed tomography (Figure 3(B)), a total of six coils were placed in the aneurysm to stabilize the coil mesh. No procedural complications were encountered. Final post-embolization digital subtraction angiography (DSA) showed complete occlusion of the aneurysm (Figure 4). One day after these procedures, we started treatment with dual-agent antiplatelet therapy (aspirin 100 mg/day and cilostazol 200 mg/day). She was discharged home on postoperative day 21. She recovered well without any sequelae, and follow-up angiography one year later showed that the PCA was well reconstructed, and that the aneurysm had disappeared (Figure 5). The clinical study of the above-mentioned case report was approved by the Ethics Committee for Clinical Research of Ehime University Hospital, and informed consent was obtained from the patient prior to initiating the study.

Figure 1.

Computed tomography on admission showing diffuse subarachnoid hemorrhage.

Figure 2.

(A) Preoperative digital subtraction angiography (left vertebral angiography: anterior posterior view) showing the aneurysm originating at the top of the basilar artery (BA). (B) Aneurysm measuring 2.7 mm in height (a: dotted line) and 4.3 mm at the neck (b: dashed line), with the proximal BA measuring 2.8 mm in diameter (c: white line) and the distal posterior cerebral artery measuring 2.2 mm in diameter (d: white line).

Figure 3.

(A) Cerebral angiography showing the LVIS Jr. stent deployed gently using the bulging technique to completely cover the neck of the aneurysm (white arrow: Neuroduo-10; black dashed line and arrow: bulging of LVIS Jr.). (B) Cone-beam computed tomography demonstrating good stent attachment and herniation of stent strut in the neck of the aneurysm.

Figure 4.

Postoperative digital subtraction angiography (A) and cerebral angiography ((B)-1: anteroposterior view; (B)-2: lateral view) demonstrating complete occlusion of aneurysm.

Figure 5.

Follow-up cerebral angiography revealing disappearance of the aneurysm. The bilateral posterior cerebral artery is well reconstructed (A) one month after operation; (B) one year after operation).

Discussion

With the development of endovascular techniques and associated new devices, endovascular therapy has become the first-line treatment for intracranial ruptured aneurysms.^6,7 However, for small and broad-necked aneurysms or those with small-diameter parent arteries, endovascular treatment still presents certain difficulties despite technical and instrumental advances.^2,8 In recent years, a new generation of self-expandable braided microstents has become available for stent-assisted coiling of complex or distal aneurysms. The LVIS and LVIS Jr. devices are among the most recently released stents, and have been approved by the Food and Drug Administration in the United States under a Humanitarian Device Exemption for unruptured, wide-necked (neck ≥4 mm or dome-to-neck ratio <2), intracranial saccular aneurysms arising from parent vessels 2.5–4.5 mm in diameter. While the LVIS is typically recommended for vessels 3–4.5 mm in diameter, the LVIS Jr. is recommended for vessels 2.5–3.0 mm in diameter.^3,9

The LVIS Jr. device is a hybrid closed-cell microstent comprising braided nitinol wires. ⁸ This stent offers several potential advantages over conventional stents such as the Neuroform (Stryker, Fremont, CA, USA) and Enterprise (Codman & Shurtleff, Raynham, MA, USA).^3,4,6 First, the most beneficial advantage of LVIS Jr. is that it is available for small and broad-necked aneurysms. When performing stent-assisted coiling, a dome size ≥7 mm is applicable for a conventional stent, but LVIS Jr. is applicable for smaller sizes >5 mm. This advantage has led to an increase in the range of treatments for stent-assisted coiling of aneurysms. Second, the braided design allows stent opening and wall conformability in small arteries with diameters between 2.0 and 3.0 mm, and delivery can be achieved through microcatheters with an internal diameter of 0.43 mm (0.017 in), representing a promising option for navigation in small arteries. ¹⁰ When delivered through small vessels, some time may be needed to achieve complete expansion and the 0.017 in microcatheter may have to be advanced through the inner delivery wire to achieve complete stent apposition. In addition, partially opening and recapturing the stent before hooking with the delivery hub is extremely important, to facilitate opening of the struts on deployment. The device is 75% resheathable and provides 15%–18% surface area coverage. ²

This braided structure increases neck coverage and also contributes to the flow diversion effect, improving the blockage rate of aneurysms. In a previous report, compared with Enterprise stents, LVIS stents achieved a greater complete or near-complete occlusion rate with no significant difference in the rate of procedural-related complications or clinical outcomes between LVIS and Enterprise. ¹¹ In addition, this system has proven effective in treating middle cerebral artery aneurysms and basilar tip aneurysms.^8,12,13 One unique and attractive technique for stent-assisted coiling using LVIS Jr. seems to be the bulging technique. The technical details of the bulging technique are described as follows. Step 1: Push out the stent and engage the distal. Step 2: Pull the microcatheter and place it in a shortcut line. Step 3: Push out the stent. Step 4: Push the stent and the microcatheter together to expand the stent. Step 5: Push out the stent to finish. This technique is similar to the concept underlying the barrel bifurcation vascular reconstruction device (Covidien).^14–16 The barrel bifurcation vascular reconstruction device is an easy-deployment system for achieving flow diversion effects, but some disadvantages are seen, in that stent cells are coarse in comparison with LVIS Jr., and the potential for assisted coiling seems low. ¹⁶ On the other hand, the bulging technique using LVIS Jr. provides greater neck coverage and flow diversion effects, and reduces the need to select a difficult obtusely arising branch artery. ¹⁷ Expansion is limited to 0.2 mm beyond the unconstrained diameter of the stent, which is currently available in 2.5 mm and 3.0 mm diameters for LVIS Jr. In addition, given that the LVIS Jr. is a braided stent, the deployment technique is more complex than laser-cut nitinol devices like the Neuroform and Enterprise, but provides advantages in expansion or barreling not readily available with other stents.^2–4 This technique with LVIS Jr. is an innovative concept for broad-necked aneurysms. In our case, the results demonstrate the clinically beneficial effects of this stent in terms of both radiological findings and improvement of clinical features. Further experience with more cases is needed to confirm the safety and effectiveness of this technique, and longer patient follow-up is required.

Conclusion

We have described a case of a small ruptured BA top aneurysm that presented with a wide neck, in which successful treatment was achieved using stent-assisted coiling with LVIS Jr. The bulging technique using LVIS Jr. can provide better stent coverage of the aneurysmal neck. This novel technique may be an effective, innovative, less-invasive treatment for small, broad-necked aneurysms.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.