A novel endovascular clip system for the treatment of intracranial aneurysms: technology, concept, and initial experimental results

Laboratory investigation

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Object

The authors describe a novel device for the endovascular treatment of intracranial aneurysms, the endovascular clip system (eCLIPs). Descriptions of the device and its delivery system as well as the results of flow model tests and the treatment of experimental aneurysms are provided.

Methods

The eCLIPs comprises a flexible hybrid implantable device (an anchor and a covered leaf) and a balloon catheter delivery system, designed to be positioned and activated in the parent vessel in such a way that the covered portion will abut the aneurysm neck. The eCLIPs was subjected to testing in glass, elastomeric, and cadaveric flow models to determine its navigability, orientation, and activation compared with commercially available stents. In a second experiment, 8 carotid artery sidewall aneurysms in swine were treated using eCLIPs. The degree of occlusion was observed on angiography immediately following and 30 days after device activation, and a histological analysis was performed at 30 days.

Results

The device could navigate tortuous glass models and human cadaveric vessels. Compared with commercially available stents, the eCLIPs performed well. It could be navigated, oriented, and activated easily and reliably. With regard to the 8 porcine experimental aneurysms, immediate postactivation angiograms confirmed complete occlusion of 4 lesions and near occlusion of the other 4. Angiographic follow-up at 30 days postactivation showed occlusion of all 8 aneurysms and patency of all parent vessels. Histopathological analysis revealed aneurysm healing, with smooth-muscle cells growing across the lesion neck to allow reendothelialization.

Conclusions

Aneurysm occlusion with a single extrasaccular endovascular device has potential advantages. The authors believe that eCLIPs may prove to be a useful tool in the endovascular treatment of cerebral aneurysms. The system should reduce risks associated with coiling, procedure time, costs, and radiation exposure. The device satisfactorily occluded 8 experimental sidewall aneurysms. The observed healing pattern is similar to that seen after microsurgical clipping.

Abbreviations used in this paper: eCLIPs = endovascular clip system; SAH = subarachnoid hemorrhage.

Article Information

Address correspondence to: Thomas R. Marotta, M.D., Department of Radiology, St. Michael's Hospital, 30 Bond Street, Toronto, Ontario, Canada M5B 1W8. email: marottat@smh.toronto.on.ca.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    Drawing (A) and photograph (B) of the nonactivated eCLIPs device showing the device profile and nomenclature.

  • View in gallery

    Photographs showing the leaf release mechanism. a: Device prior to activation. b: Initial expansion in the anchoring section up to a predefined circumference. c: Separation of leaf edges. d: Coaxing the leaf against the aneurysm neck opening by further balloon inflation.

  • View in gallery

    Schematic depicting the eCLIPs delivery catheter. 1: Guidewire taper and torque handle. 2: Inflation port. 3: Hub body. 4: Strain relief. 5: Proximal shaft. 6: Distal shaft. 7: Balloon.

  • View in gallery

    Schematic illustrating the eCLIPs orientation based on the relationship between the guidewire, the aneurysm neck, and the markers.

  • View in gallery

    Photographs showing the eCLIPs being positioned and activated in a pulsatile flow glass model. A: Initial positioning and balloon inflation. B: The leaf moving against the aneurysm neck. C: The leaf close to its final positioning. D: Neck occlusion after total balloon inflation.

  • View in gallery

    Schematic depicting the positioning and activation of an eCLIPs for the treatment of sidewall (upper) and bifurcation (lower) aneurysms. Note the orientation of the leaf in relationship to the anchor segment.

  • View in gallery

    Angiograms depicting delayed (A1–3) and acute (B1–3) closure of experimental aneurysms. Preactivation (A1), postactivation (A2), and late (A3) views. Preactivation (B1), activation (B2), and postactivation (B3). Note the radiopaque markers (arrows).

  • View in gallery

    A: Photomicrograph depicting a vessel section at the level of an aneurysm with a completely healed neck (arrows). B: Photomicrograph showing the detail of the border between the native artery (left) and the newly formed vessel wall (arrow) at the location of the previous neck opening (right). H & E. Bar = 500 μm.

  • View in gallery

    Photomicrograph demonstrating a thrombus (arrows) located between the device leaf and the healed aneurysm neck. No evidence of recanalization is seen, with well-organized fibrous tissue in the aneurysm sac to the right of the vessel lumen. H & E. Bar = 500 μm.

  • View in gallery

    Photomicrograph revealing a small fissure with intimal lining extending from the border zone between the native vessel and neointimal closure of the aneurysm neck. Note the obliteration of the aneurysm sac (to the right) by an organized thrombus. H & E. Bar = 500 μm.

  • View in gallery

    Photograph showing a vessel after implantation of the eCLIPs prototype. The neck opening of the experimental sidewall aneurysm closed with neointimal healing. The fissure (small arrows) is an artifact from opening the vessels longitudinally. Note the anchor (large arrow) and the leaf (arrowhead).

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