Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 59, Num. 4, 2011, pp. 548-552

Neurology India, Vol. 59, No. 4, July-August, 2011, pp. 548-552

Original Article

Endovascular treatment for wide-necked intracranial aneurysms with the Enterprise stent

Haidong Wang¹, Dianshuang Xu¹, Yongsheng Xiang¹, Wei Li¹, Zhiyong Chen¹, Shancheng Chen¹, Xu Kan²

¹ Department of Neurosurgery, Jinan University Affiliated First Hospital, Guangzhou, China
² Department of Neurosurgery, Jilin University Affiliated First Bethune Hospital, Changchun, China
Correspondence Address: Xu Kan, Neurosurgery Department, Jilin University, Bethune Hospital, 130 021, Changchun, China, 13823307551@139.com

Date of Submission: 27-Mar-2011
Date of Decision: 22-Apr-2011
Date of Acceptance: 27-Apr-2011

Code Number: ni11168

PMID: 21891931

DOI: 10.4103/0028-3886.84335

Abstract

Keywords: Enterprise stent, intracranial aneurysm, stent-assisted coiling

Introduction

The development of self-expanding stents dedicated to intracranial use has significantly widened the applicability of endovascular therapy to many intracranial aneurysms. ^[1] The recent Enterprise stent has added a new option for self-expanding stent-assisted intracranial aneurysm coiling. ^[2] We report angiographic and clinical outcomes and rates of complications in wide-necked intracranial aneurysms treated by using Enterprise stents.

Material and Methods

Between June 2009 and December 2010, 46 patients with 50 wide-necked cerebral aneurysms were treated endovascularly using Enterprise stents, in our center. Demographic information included the following: Reason for presentation, patient age and sex, aneurysm size, and aneurysm location. Procedural data included percentage of occlusion (at the completion of the initial procedure), and technical complications. Before all the procedures, the patients underwent conventional angiography of both internal carotid arteries (ICA) and vertebral arteries (VA) and three-dimensional angiography. The characteristics of the patients and aneurysms are summarized in [Table - 1].

Indications

The Enterprise is intended for use with embolic coils for the treatment of wide-necked (defined as having a neck width >4 mm or a dome-to-neck ratio of <2) saccular or dissecting intracranial aneurysms arising from a parent vessel, with a diameter between 3 and 4 mm. The diagnosis of a dissecting aneurysm is classically made by the angiographic appearance with a double lumen, a focal vessel wall irregularity, a pre-aneurysmal narrowing and a fusiforme dilatation. On magnetic resonance imaging (MRI), when a vessel wall flab is seen, it is diagnosed as dissection.

Endovascular procedure

All procedures consisted of stent delivery across the aneurysm (in the case of a fusiform aneurysm) or its neck (wide-necked aneurysms) and subsequent coiling of the sac. Endovascular treatment was performed on a biplane, flat panel digital subtraction unit. Patients with no subarachnoid hemorrhage (SAH) were pretreated with 200 mg of aspirin and 75 mg of clopidogrel (Plavix; Bristol-Myers Squibb/Sanofi Pharmaceuticals, NY) for three to five days preceding stent placement and patients with SAH were pretreated with 300 mg of aspirin and 300 mg of clopidogrel, two hours before the procedure. The endovascular procedures were performed under general anesthesia and systemic heparinization. The bolus infusion of heparin was 4000 IU followed by 1000 IU/hour with the purpose of anticoagulation. Systemic heparinization was prolonged for 24 hours in all patients. Unilateral femoral access was obtained through a percutaneous femoral artery puncture, and one 6-French Envoy MPD (Cordis Neurovascular, Inc.) guiding catheter was inserted into the parent vessel. A 2.3-French Prowler Plus microcatheter with an internal diameter of 0.021 inch was then advanced over a 0.014-inch Transend or Synchro microguidewire (Target Therapeutics, Fremont, CA) into the normal distal artery beyond the aneurysm, by 2 cm. The guide-wire was then removed, and the stent was introduced into the hub of the catheter via the delivery system. Under road-mapping, the stent was then pushed through the microcatheter and aligned directly across the neck of the aneurysm. When proper alignment was achieved, the microcatheter was gently pulled back to unsheath the stent, while gentle forward tension was maintained on the stent system to keep it in place [Figure - 1]. We waited for the distal flared end to be completely open, and then the stent was deployed to as much as 70% of its opening; the positioning was confirmed by direct visualization. If the stent required repositioning, it was re-sheathed, repositioned, and then redeployed. Once the stent was fully deployed, the microcatheter and introducing system were removed. A smaller microcatheter, Echelon 10/14 (M.T.I-ev3), was then introduced through the guiding catheter, and with direct fluoroscopic visualization and road-mapping, guided through the interstices of the stent and into the aneurysm. Microplex coils (MicroVention, Aliso Viejo, CA) were then delivered within the aneurysm through the microcatheter. After treatment, the fluid balance, neurological status, and blood pressure were carefully monitored. The patients were maintained on aspirin and clopidogrel for one month and aspirin (100 mg per day) for six months.

Angiographic and clinical results

The initial procedural outcome was categorized as: Complete occlusion (100%), nearly complete (>90%), and incomplete (≤90%). ^[3] The outcome according to the Glasgow Outcome Scale ^[4] was evaluated at a 9.1 month follow-up (range 1 - 18 months). Follow-up angiograms were performed after one to nine months.

Results

Demographic data

In total, 46 patients (20 males and 26 females) with 50 wide-necked cerebral aneurysms underwent 50 attempted stent deployments. The mean age was 51.2±11.5 years. The most common location was the paraclinoid region (in 17 patients) followed by, in decreasing frequency, VA (in 13 patients), basilar artery (not tip) (in 11 patients), posterior communicating artery (in five patients), cavernous ICA (in three patients) and basilar tip (in one patient). Initial presentation was: Incidental in 18 patients; SAH in 16 patients; visual impairment in six patients; ophthalmoplegia in three patients; hemiparesis in three patients; routine follow-up of a previously coiled aneurysm demonstrating recurrence in one patient; and tetraplegia in one patient. Mean aneurysm size was 10.3±5.5 mm [Table - 1]. Thirty-one aneurysms were saccular and 19 were dissecting.

Treatment

Forty-eight aneurysms were treated by Enterprise stent-assisted coiling [Figure - 2] and [Figure - 3], and two aneurysms with dissection and without aneurysmal dilation, were treated with stent alone. A parallel technique (aneurysmal catheterization was performed prior to stent releasing) was used in all stent-assisted coiling embolization. Complete and nearly complete occlusion was achieved in 44 aneurysms (88%) and incomplete in six aneurysms (12%). One complication occurred in this group.

Complication

In total, one patient died (2% mortality rate). This death occurred in one patient with an unruptured aneurysm. The death was due to microcatheter dome perforation during coiling (post-stent placement) of an unruptured large basilar trunk aneurysm.

Follow-up

Clinical and angiographic follow-up examinations were performed in 45 (97.8%) patients for 49 aneurysms, after a mean time of 9.1 months (range 1 - 18 months). Forty-seven lesions were unchanged (complete occlusion in 42, residual neck in 5). One aneurysm exhibited increasing spontaneous thrombosis after stent deployment, without coil embolization. Two (4%) recurrences were evident. Subsequently, one of these was completely occluded by coil embolization. During the follow-up period, no angiographic narrowing of the vessels was seen and the outcome was good in 45 patients.

Discussion

This study shows that the Enterprise stent is a very useful tool for endovascular embolization of wide-necked intracranial aneurysms. Higashida et al., ^[5] reported their experience with stent-assisted coiling of intracranial aneurysms in five patients with the Enterprise stent, with 100% accurate deployment; there were no adverse events or morbidity. More recently, Weber et al., ^[6] reported a larger series of 30 patients with 31 aneurysms, with 100% successful deployment, and two 'possible or probable device-related serious adverse events during the six-month follow-up period'. However, despite these events, there was no procedural-related morbidity or death. In our study the use of the Enterprise stent was associated with a 90% rate of occlusion in 88% of the cases with no morbidity and 2% mortality. These data compare well with the previously published data for Neuroform and Enterprise, as well as with the non-stent related surgical and endovascular studies. ^{[7],[8],[9],[10],[11],[12],[13],[14],[15],[16],[17],[18]} The current Neuroform and Enterprise data report initial rates of >90% occlusion with a range of 35.3 to 80% for intracranial aneurysms. ^{[9],[10],[11]} Our experience favors the upper limit of this range.

The early published experience with Neuroform demonstrated: Rates for the inability to navigate or deploy 4-14%, rates for inaccurate deployment 8-7.8%, and rates for 'difficulty' in deployment 24-31%. ^[8],[9],[11] However, newer Neuroform iterations have resulted in some improvement in navigability, with only 4% inaccurate deployment rate for Neuroform, and it was 1.3% for Enterprise. ^{[9],[10],[11]} We experienced no inaccurate deployment rate and no inability in deployment with the Enterprise. Our series confirms the efficacy and safety of stent-assisted coiling with the Enterprise device, and the parallel technique was used frequently in our center. We did not encountered difficulties in selecting the aneurysm through the stent strut. Moreover, the Enterprise stent appears very easy to navigate and to position, on account of its delivery system. Indeed, this stent is delivered through a conventional coiling catheter that is easy to navigate. It is approved for use in parent vessels with a diameter of 2.5 to 4.0 mm. The major disadvantage is the fact that it is available in only one diameter, despite being available in multiple lengths.

The Neuroform stent (Boston Scientific/Target Therapeutics, Fremont CA), approved in 2002, was the first stent available in the United States market. Other aneurysm stents or vascular reconstruction devices are available outside the United States market and include the Leo stent (Balt Extrusion, Montmorency, France), ^[19] Solo stent (ev3, Inc., Irvine, CA), ^[20] and the Pipeline device (Chestnut Medical Technologies, Inc., Menlo Park, CA). ^[21] The first retractable stent to be released was the Leo stent. The Leo stent presents a limiting characteristic: The need for progressively larger and stiffer delivery catheters, to place larger stents. ^[22]

References

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