Initial experience and one-year follow-up with Neuroform Atlas Stent System for the treatment of brain aneurysms

Abstract

Introduction: The Neuroform Atlas Stent System is a recently introduced modification of the original Neuroform Stent System consisting of a hybrid design with open and closed cells. Initial experience, technical considerations and treatment outcomes including 1-year follow-up using the Atlas stent in combination with coil embolization are reported.

Material and methods: Thirty patients with 30 unruptured aneurysms were treated with stent reconstruction. Immediate, 4-month and 12-month post-treatment angiography and clinical assessment were performed.

Discussion: In 29 cases, the stents were delivered and positioned without difficulty in deployment. Technical complications occurred in one patient related to advancement of the stent during delivery. One procedure-related clinical complication occurred with no permanent neurological deficit. On immediate post-treatment angiography, 29 of 30 aneurysms showed Raymond Class I or Class II occlusion. At 1-year follow-up, all 30 patients were clinically stable and 18 of 30 aneurysms showed Raymond Class I complete occlusion. Retreatment was performed in two patients with residual aneurysm.

Conclusions: The Atlas stent is technically safe and simple to implant and has a low thrombogenic potential. We experienced fewer problems associated with deployment and implantation, thromboembolic complications and hemorrhagic events compared with other types of stents, including braided stents. However, because of its low thrombogenic potential, partially occluded aneurysms or those with aneurysm remnants do not progress to complete occlusion.

Keywords: Aneurysm; brain; hemorrhage; stent; stroke.

Figure 1.

Neuroform Atlas Stent System. (a) The open-cell distal end is designed to aid in stent conformability and device tracking. The 8-cell structural elements are designed to provide support and anchoring, the 12-cell structural elements are designed to provide flexibility, improve scaffolding and prevent ‘gapping’ on a vessel bend, and the closed-cell proximal end is designed to aid in stent stability during lumen recrossing. (b) The hybrid design can reduce the bifurcation neck. (c) The hybrid design can be apposed on tight curves. (d) The hybrid design can conform to anatomy while maintaining re-crossability.

Figure 2.

Thromboembolic complication. Implantation of a subacute Neuroform Atlas stent in a ruptured posterior inferior cerebellar artery aneurysm treated with simple coiling 3 weeks prior in order to stabilize the treatment. The parent vessel had a non-occlusive asymptomatic dissection after the passage of the microcatheter that was resolved at follow-up.

Figure 3.

Recanalization. A worsening of the degree of closure in two aneurysms is observed. A middle cerebral artery aneurysm treated by Y stent and coils that was treated again by implantation of new coils 6 months after the initial treatment. An aneurysm of the basilar tip of the basilar treated by a Y stent with neck remnant in the initial treatment and a recanalization that progressed from mild 6 months after with digital subtraction angiography to significant 1 year after with magnetic resonance imaging.

Figure 4.

Treatment with remodeling of an aneurysm of the top of the basilar with subsequent implantation of the Neuroform Atlas stent in order to achieve stability of the treatment.

Figure 5.

Aneurysm of the anterior communicating artery treated with balloon and coils and later implantation of a Neuroform Atlas stent. The observed technical complication is a displacement of the stent from the desired position A1-A2, to a position in average T. The aneurysm presents a lower and posterior remnant that required new treatment with coils and implantation of a stent in Y configuration.

Figure 6.

Hemorrhagic complication. Aneurysm rupture with the first coils after crossing through the previously placed Neuroform Atlas stent. After suspending the intravenous administration of Tirofiban, it was possible to contain the bleeding with the implantation of new coils, and subsequently reintroduce the administration of the intravenous antiaggregant. The patient presented a delay in hospital discharge but did not sustain permanent neurological deficits.