Background Since FDA approval in May 2007, closed cell intracranial stents have become increasingly used to assist aneurysm coil embolization. Inadvertent deformation and displacement of a deployed closed cell stent may occur with manipulation of devices through or beyond them. Misshapen stents may compromise the vessel lumen, serving as a thromboembolic risk and/or no longer function as a scaffold to assist with coil embolization. Two cases are reviewed where the Alligator retrieval device was used to salvage a misshapen intracranial stent.
Case No 1 A 62-year-old woman underwent coil embolization of a carotid ophthalmic artery aneurysm with the use of a Neuron guide catheter and an Enterprise stent. The stent was inadvertently deployed proximal to the target lesion. Attempts to regain access to the aneurysm through the stent resulted in a misshapen configuration, obstructing the vessel lumen.
Case No 2 A 61-year-old woman underwent coil embolization for a posterior communicating aneurysm dome remnant. Using a Neuron guide catheter, an Enterprise stent was accurately deployed. Subsequent microcatheter selection of the aneurysm led to a misshapen, constricted stent. Attempts to advance a balloon and another stent delivery catheter through the misshapen stent were unsuccessful.
Case No 1 A 5.2 F Outreach catheter was positioned adjacent to the proximal border of the stent. We then used the 4 mm Alligator retrieval device within a Prowler Select Plus microcatheter to then grasp the endoluminal portion of the stent and retrieve it completely into the 5.2 F catheter. No resistance was encountered. Subsequent angiographic runs showed no vessel injury. Stent assisted coil embolization was then completed with good results.
Case No 2 A Prowler Select Plus microcatheter was advanced to the proximal end of the stent. A 2 mm Alligator retrieval device was used to grasp the proximal edge of the stent and gently pull the stent proximally until the radio-opaque markers were visualized to expand and fully oppose the vessel wall. Coil embolization was then completed with good results.
Conclusions Guide catheters that allow for distal access, such as the Penumbra Neuron Guide catheter, minimize proximal tortuosity, thereby allowing for greater force to be transmitted when advancing a microcatheter intracranially.
Delayed migration has been reported in the use of the Enterprise stent and is thought to be due to the inherent flexibility of the closed cell design that allows for force transmitted on one end to be transmitted to the entire device. Because of this delicate property plus the low level chronic outward radial force, some physicians prefer to stage coil embolization at some interval after stent placement to allow for stent stabilization.
In both cases, excess microcatheter force combined with the closed cell stent construct led to a misshapen stent. The Alligator retrieval device has been reported to retrieve platinum coils, cerebral thromboemboli and coronary stents, but never with intracranial stents. As a bailout method, the Alligator retrieval device allowed for safe and effective endovascular rescue via stent removal in the first case and repositioning in the second case.
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Competing interests None.
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