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

Particle Image Velocimetry Measurements of the Flow-Diverting Effects of a New Generation of the eCLIPs Implant for the Treatment of Intracranial Bifurcation Aneurysms

Flow diverters (FDs) for the endovascular treatment of intracranial aneurysms are effective for sidewall aneurysms, but their use at a bifurcation is problematic because FDs only partially cover the aneurysm neck and impede flow into a daughter branch; they are thus not employed routinely in this anatomy. eCLIPs was developed as a non-tubular implant to completely cover the neck of an aneurysm and serve as a coil retention device necessary for the adequate treatment of wide-neck bifurcation aneurysms. eCLIPs has shown some flow diversion effects in bifurcation anatomy but not equal to those exhibited by clinically accepted flow diverters in sidewall anatomy. A new generation of eCLIPs implant, the eCLIPs bifurcation flow diverter (eBFD), with higher metal coverage, was developed to achieve a similar flow diversion as a Pipeline Embolization Device (PED), a prototypical FD. Particle image velocimetry was used to capture the fluid dynamics and velocity reduction within silicone aneurysm replicas. A circulatory mimicking loop was developed to circulate the flow through the silicone models. All generations of eCLIPs implants had some flow-diverting effect, with increasing metal coverage density of the implant proportionately increasing the flow diversion effect. The eBFD, with a metal density of 35%, showed greater flow diversion than PED, with 30% metal density, for bifurcation anatomy. The eBFD showed similar reduction of flow in a bifurcation anatomy to PED in a sidewall, both sufficient to permit early thrombosis of the aneurysm. Thus, the eBFD can potentially provide sufficient flow diversion for the treatment of bifurcation aneurysms to avoid adjunctive coiling.

Neurovascular devices for the treatment of intracranial aneurysms: emerging and future technologies

Introduction: Despite numerous advances in the endovascular treatment of intracranial aneurysms (IAs), treatment in cases of wide-neck, complex configurations or branching locations remains challenging. Apart from the paradigm shift introduced by flow diverters, several other devices have seen the light or are under development in order to address these challenges.Areas covered: We performed a review of the novel implantable endovascular devices which have been introduced for the treatment of IAs, from 1 January 2014 to 1 September 2019, excluding classic flow diverter and intracranial stent designs.Expert opinion: Alternative designs have been proposed for the treatment of IAs at branching positions, which do not jail the side branches, with or without flow diversion effect, most of which with good initial outcomes. Endosaccular devices have also been proposed, some of which with lower initial total occlusion rates. Alternative materials such as biopolymers have also been proposed and are under bench research. Despite the challenges in the exploitation of some of the new devices, most of them seem to provide solutions to some current technical shortcomings. The exploitation of the biological phenomena and the physical properties of the devices will allow us to expand the therapeutic armamentarium for more complex IA cases.

Current Status of the PulseRider in the Treatment of Bifurcation Aneurysms: A Systematic Review

BACKGROUND

The PulseRider is an innovative stent-like device designed for the treatment of intracranial bifurcation aneurysms. The aim of this study was to assess the current evidence on safety and effectiveness of the PulseRider.

METHODS

A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The following databases were searched: PubMed, Ovid MEDLINE, and Scopus. The search strategy consisted of "pulserider," "bifurcation aneurysm," and "endovascular" in both AND and OR combinations. Studies included were original research articles in peer-reviewed journals. The manuscripts were thoroughly examined for study design, outcomes, and results.

RESULTS

Three studies were identified describing use of the PulseRider device in the treatment of 63 patients with 63 bifurcation aneurysms. We identified 2 multicenter case series and 1 single-arm clinical trial. The majority of aneurysms treated were located at the basilar tip (37, 58.7%). All devices were successfully deployed, and there were 5 intraoperative complications (7.9%), including 2 intraoperative aneurysm ruptures, 1 vessel dissection, and 2 thrombus formations. Immediate complete aneurysm occlusion was achieved in 61.9% (39/63) of cases and at the 6-month imaging follow-up, 66.7% (42/63) achieved complete aneurysm occlusion. One recanalization was reported in 1 of the multicenter case series within the 6-month follow-up.

CONCLUSIONS

The PulseRider is safe and probably effective for the treatment of intracranial bifurcation aneurysms, sometimes not amenable for stent-assisted coiling. However, current evidence is limited to a small sample and short follow-up. In addition, the device has not been compared with other treatment modalities.

The second-generation eCLIPs Endovascular Clip System: initial experience

OBJECTIVE Treatment of wide-necked intracranial aneurysms is associated with higher recanalization and complication rates; however, the most commonly used methods are not specifically designed to work in bifurcation lesions. To address these issues, the authors describe the evolution in the design and use of the eCLIPs (Endovascular Clip System) device, a novel hybrid stent-like assist device with flow diverter properties that was first described in 2008. METHODS A registry was established covering 13 international centers at which patients were treated with the second-generation eCLIPs device. Aneurysm morphology and rupture status, device neck coverage, coil retention, and procedural and late morbidity and mortality were recorded. For those patients who had undergone successful implantation more than 6 months earlier, the final imaging and clinical follow-up results and need for re-treatment were recorded. RESULTS Thirty-three patients were treated between June 2013 and September 2015. Twenty-five (76%) patients had successful placement of an eCLIPs device; 23 (92%) of these 25 patients had complete data. Eight cases of nondeployment occurred during the 1st year of use, consistent with a learning curve; no failures of deployment occurred thereafter. Two periprocedural transient ischemic attacks and 2 asymptomatic thrombotic events occurred. Twenty-one (91%) of 23 patients underwent follow-up at an average of 8 months (range 3-18 months); 9 (42.9%) of these 21 patients demonstrated an improvement in Raymond grade at follow-up; no cases of worsening Raymond grade were recorded, and 17 (81.0%) patients sustained a modified Raymond-Roy Classification class of I or II angiographic result at follow-up. Two delayed ruptures were recorded, both in previously coiled, symptomatic giant aneurysms where the device was used as a part of a salvage strategy. CONCLUSIONS The second-generation eCLIPs device is a viable treatment option for bifurcation aneurysms. The aneurysm occlusion rates in this initial clinical series are comparable to the initial experience with other bifurcation support devices.

Physiological remodeling of bifurcation aneurysms: preclinical results of the eCLIPs device

OBJECTIVE

Intracranial bifurcation aneurysms are complex lesions for which current therapy, including simple coiling, balloon- or stent-assisted coiling, coil retention, or intrasaccular devices, is inadequate. Thromboembolic complications due to a large burden of intraluminal metal, impedance of access to side branches, and a high recurrence rate, due largely to the unmitigated high-pressure flow into the aneurysm (water hammer effect), are among the limitations imposed by current therapy. The authors describe herein a novel device, eCLIPs, and its use in a preclinical laboratory study that suggests the device's design and functional features may overcome many of these limitations.

METHODS

A preclinical model of wide-necked bifurcation aneurysms in rabbits was used to assess functional features and efficacy of aneurysm occlusion by the eCLIPs device.

RESULTS

The eCLIPs device, in bridging the aneurysm neck, allows coil retention, disrupts flow away from the aneurysm, leaves the main vessel and side branches unencumbered by intraluminal metal, and serves as a platform for endothelial growth across the neck, excluding the aneurysm from the circulation.

CONCLUSIONS

The eCLIPs device permits physiological remodeling of the bifurcation.

Development of New Endovascular Devices for Aneurysm Treatment

Since the first use of the Guglielmi detachable coil system for cerebral aneurysm embolization in 1990, various endovascular methods have been developed to treat large numbers of aneurysms. The main strategic and technical modifications introduced to date include balloon-assisted coil embolization, stent-assisted coil embolization, flow diverters, and flow disrupters. The development and introduction of such devices have been so persistent and rapid that new devices are being approved worldwide even before the earlier ones become available in some countries. However, even if some patient populations may possibly benefit from earlier introduction of new devices, the approval authorities should balance the available evidence of the safety and effectiveness of novel devices. This review aims to provide an overview of the recent innovations in endovascular treatment of cerebral aneurysms and a brief review of market access policies and regulations for importing high-risk medical devices, such as those used for endovascular aneurysm management, which correspond to class III devices, as defined by the U.S. Food and Drug Administration. We focus on the current situation in Korea and compare it with that in other Asian countries, such as China and Japan.

Synchrotron-based intra-venous K-edge digital subtraction angiography in a pig model: a feasibility study

BACKGROUND

K-edge digital subtraction angiography (KEDSA) combined with the tunability of synchrotron beam yields an imaging technique that is highly sensitive to low concentrations of contrast agents. Thus, contrast agent can be administered intravenously, obviating the need for insertion of a guided catheter to deliver a bolus of contrast agent close to the target tissue. With the high-resolution detectors used at synchrotron facilities, images can be acquired at high spatial resolution. Thus, the KEDSA appears particularly suited for studies of neurovascular pathology in animal models, where the vascular diameters are significantly smaller than in human patients.

MATERIALS AND METHODS

This feasibility study was designed to test the suitability of KEDSA after intravenous injection of iodine-based contrast agent for use in a pig model. Four adult male pigs were used for our experiments. Neurovascular angiographic images were acquired using KEDSA with a solid state Germanium (Ge) detector at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France.

RESULTS

After intravenous injection of 0.9 ml/kg iodinated contrast agent (Xenetix), the peak iodine concentrations in the internal carotid and middle cerebral arteries reached 35 mg/ml. KEDSA images in radiography mode allowed the visualization of intracranial arteries of less than 1.5mm diameter.