The second-generation eCLIPs Endovascular Clip System: initial experience

eCLIPs bifurcation remodeling system for treatment of wide-neck bifurcation aneurysms: A systematic review and meta-analysis of safety and efficacy

BACKGROUND

Wide neck bifurcation aneurysms (WNBAs) are a subtype of aneurysms that are especially complex to treat. We aim to conduct a systematic review and meta-analysis to synthesize the available literature on the safety and efficacy of employing endovascular clip system (eCLIPs) in the treatment of WNBAs.

METHODS

We report this study in accordance to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) 2020 guidelines. PubMed, Embase, Web of Science, and Scopus were queried for this review. Screening and extraction were performed by at least two authors to ensure accuracy and completeness, and a senior author arbitrated any discrepancies. All data were analyzed using R software version 4.3.0. and random-effects model.

RESULTS

Four studies were finally included, of which three were prospective and one was retrospective. Successful adjunctive coiling occurred in 91.38% (95% CI = 70.71-97.9) of cases and overall technical success was achieved in 88.61% (95 CI = 75.54-95.15) of cases. The pooled complete occlusion (Raymond-Roy Class I) was 50.65% (95% CI = 39.63-61.60) and adequate occlusion (Raymond-Roy Class I/II) was 84.42% (95% CI = 74.53-90.93). Thrombo-embolic complication had a pooled rate of 1.22% (95% CI = 0.17-8.15), retreatment rate was 6.10% (95% CI = 2.56-13.83), and mortality reported in 3.66% (95% CI = 1.18-10.74) of patients.

CONCLUSION

The use of eCLIPs may be a safe and efficacious treatment for WNBAs. Future randomized controlled trials are needed for further validation of the findings.

A comprehensive simulation framework for predicting the eCLIPs implant crimping into a catheter and its deployment mechanisms

Tubular flow diverters (FDs) represent an important subset of the endovascular treatment of cerebral aneurysms (CAs), acting to reduce aneurysm inflow, eventually resulting in aneurysm thrombosis and occlusion. eCLIPs (product of Evasc Neurovascular Enterprises, Vancouver, Canada), an innovative non-tubular implant causes flow diversion by bridging the neck of bifurcation CAs. However, in a small subset of challenging bifurcation aneurysms with fusiform pathology, the currently available eCLIPs models do not provide sufficient neck bridging resulting in a gap created between the device structure and the aneurysm/artery wall. To overcome this challenge, a new design of the eCLIPs (VR-eCLIPs) was developed by varying the rib length to cover such an inflow gap. To optimize the new product development process, and avoiding expensive and time-consuming iterative manufacture of prototype devices, we have developed a new finite element model to simulate the crimping and expansion processes of the VR-eCLIPs implant, and assess the possibility of plastic deformation. Results indicated that neither eCLIPs nor VR-eCLIPs experience plastic deformation during the crimping process. Upon full expansion, the ribs of VR-eCLIPs interact with the aneurysm and artery wall to cover the inflow gap that exists in certain challenging anatomies. This process serves as a basis to expedite design development prior to prototype manufacturing.

Endovascular Treatment of Wide-Neck Bifurcation Aneurysm: Recent Trends in Coil Embolization with Adjunctive Technique

Wide-neck bifurcation aneurysms (WNBAs) are sometimes challenging to treat. During endovascular treatment, it is important to prevent coil deviation and preserve normal vessels. Adjunctive balloon- and stent-assisted techniques have been developed. A meta-analysis of endovascular treatments of WNBAs revealed that only 40% of patients had complete occlusion. Recently, novel devices have been developed to expand the range of treatment options. Flow-diverter stents and intra-aneurysmal flow disruption devices do not require coils; however, coil embolization remains the standard procedure used by many neurointerventionists. This review describes the recent trends in adjunctive techniques for supporting coil embolization for WNBAs. We referred to literature on balloon-assisted techniques, stent-assisted techniques, Y-stenting, PulseRider, Barrel stents, Comaneci temporary stents, pCONUS, and eCLIPs. These reports showed that adequate embolization rates were generally greater than 80%, and the complete occlusion rate was as high as 94.6%. All devices had a relatively high occlusion rate; however, it may be inaccurate to simply compare each device because of the heterogeneity of the studies. It is important to select the best treatment for each individual case by considering not only literature-based efficacy and safety but also patient background, aneurysm characteristics, and operator experience.

The Management of Intracranial Aneurysms: Current Trends and Future Directions

Intracranial aneurysms represent a major global health burden. Rupture of an intracranial aneurysm is a catastrophic event. Without access to treatment, the fatality rate is 50% in the first 30 days. Over the last three decades, treatment approaches for intracranial aneurysms have changed dramatically. There have been improvements in the medical management of aneurysmal subarachnoid haemorrhage, and there has been an evolution of treatment strategies. Endovascular therapy is now the mainstay of the treatment of ruptured intracranial aneurysms based on robust randomised controlled trial data. There is now an expansion of treatment indications for unruptured intracranial aneurysms to prevent rupture with both microsurgical clipping and endovascular treatment. Both microsurgical and endovascular treatment modalities have evolved, in particular with the introduction of innovative endovascular treatment options including flow diversion and intra-saccular flow disruption. These novel therapies allow clinicians to treat more complex and previously untreatable aneurysms. We aim to review the evolution of treatment strategies for intracranial aneurysms over time, and discuss emerging technologies that could further improve treatment safety and functional outcomes for patients with an intracranial aneurysm.

[Brain aneurysms treatment with pCONus2 device. Initial experience at IMSS]

Background

pCONus2 device has been used in some countries as coadyuvant in the treatment of wide-neck bifurcation aneurysms with coils.

Objective

To present the first series of brain aneurysms treated with pCONus2 in the Mexican Institute for Social Security (IMSS).

Material and methods

We retrospectively present the first 13 aneurysms treated from October 2019 to February 2022 with pCONus2 device at a third level hospital.

Results

6 aneurysms located at anterior communicating artery, 3 at middle cerebral artery bifurcation, 2 at internal carotid artery bifurcatión, and 2 at the tip of basilar artery were treated. Device deployment was performed without complications and it was possible to embolize aneurysms with coils in 12 patients (92%), while on an internal carotid bifurcation aneurysm (8%) there was an incident of a pCONus2 petal migration toward vascular lumen caused by coils mesh pressure, situation that was solved by placing an nitinol self-expandable microstent. In 7 cases (54%) we performed coiling technique after microcatheter passage through pCONus2, while in 6 cases (46%) we used the jailing technique without complications.

Conclusions

pCONus2 is a useful device for wide-neck bifurcation aneurysms embolization. In Mexico our experience is yet limited; however, the first cases have been successful. Furthermore, we showed the first cases treated using jailing technique. Much more cases are required in order to carry out a statistically conclusive analysis and to establish the effectiveness and safety of the device.

The pCONUS2 and pCONUS2 HPC Neck Bridging Devices : Results from an International Multicenter Retrospective Study

INTRODUCTION

Bifurcation aneurysms represent an ongoing endovascular challenge with a variety of techniques and devices designed to address them. We present our multicenter series of the pCONUS2 and pCONUS2 HPC devices when treating bifurcation aneurysms.

METHODS

We performed a retrospective review of our prospectively maintained databases at 3 tertiary neurointerventional centers to identify all patients who underwent coil embolization with the pCONUS2 or pCONUS2 HPC device between February 2015 and August 2021. We recorded baseline demographics, aneurysm data, complications, immediate and delayed angiographic results.

RESULTS

We identified 55 patients with 56 aneurysms, median age 63 years (range 42-78 years), 67.3% female (n = 37). The commonest aneurysm location was the MCA bifurcation (n = 40, 71.4%). Average dome height was 8.9 ± 4.2 mm (range 3.2-21.5 mm), average neck width 6.4 ± 2.5 mm (range 2.6-14 mm), and average aspect ratio 1.3 ± 0.6 (range 0.5-3.3). The pCONUS2 was used in 64.3% and the pCONUS2 HPC in 35.7%. The procedural technical success rate was 98.2%. Intraoperative complications occurred in 5 cases (8.9%), 4 of which were related to the coils with partial thrombus formation on the pCONUS2 HPC seen in 1 case that was resolved with heparin. In relation to the procedure and treatment of the aneurysm the overall permanent morbidity was 1.8% (n = 1/55) and mortality 0%. Delayed angiographic follow-up (48 aneurysms) at median 12 months postprocedure (range 3-36 months) demonstrated adequate occlusion of 83.4% of aneurysms.

CONCLUSION

The pCONUS2 and pCONUS2 HPC devices carry a high technical success rate, low complication and retreatment rate, and good rates of adequate occlusion. Larger prospective confirmatory studies are required.

Safety and efficacy of the eCLIPs bifurcation remodelling system for the treatment of wide necked bifurcation aneurysms: 1 year results from the European eCLIPs Safety, Feasibility, and Efficacy Study (EESIS)

BACKGROUND

The eCLIPs bifurcation remodelling system is a non-circumferential implant that bridges the neck from outside of a bifurcation aneurysm. The goal of the multicenter, post-marketing European eCLIPs Safety, FeasIbility, and Efficacy Study (EESIS), was to present the efficacy and safety results of the eCLIPs device after 365 days of follow-up.

METHODS

All patients were to receive an eCLIPs in conjunction with coils. The study was conducted according to good clinical practices and included independent adjudication of safety and efficacy outcomes.

RESULTS

Twenty patients were enrolled at four European centers. Mean age was 60 years (range 41-74) and aneurysms were located at the basilar tip (n=19) and carotid tip (n=1). Average aneurysm dome height was 6.0 mm (range 2.0-15.0). Mean neck length was 5.1 mm (range 2.6-8.5). The technical success rate was 90% (18 of 20). No major territorial strokes or deaths occurred between the index procedure and after 365 days of follow-up. Complete occlusion was achieved in 60% of patients (12 of 20 patients) and 67% of patients with an eCLIPs device (12 of 18) after 365 days of follow-up. Adequate occlusion (complete occlusion and neck remnant) was achieved in 80% of patients (16 of 20 patients) and 89% of patients with an eCLIPs device (16 of 18 patients) after 365 days of follow-up.

CONCLUSION

In this small series, treatment with eCLIPs was feasible, safe, and efficacious, considering the challenging nature of the aneurysms.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT02607501.

Treatment of wide-necked bifurcation aneurysms with the eCLIPs device: 5-year experience of a single center

BACKGROUND

The endovascular clip system (eCLIPs) is a novel device with both neck bridging and flow-diversion properties that make it suitable for the treatment of wide-necked bifurcation aneurysms.

OBJECTIVE

To describe the clinical and radiologic outcomes of the eCLIPs device, including the first-in-man use of the latest version of the device.

METHODS

This is a retrospective case series on all the wide-necked bifurcation aneurysms treated with the eCLIPs device in our center. The immediate and latest radiologic and clinical outcomes were assessed.

RESULTS

The device was successfully implanted in 12 of 13 patients. After a median follow-up period of 19 months (range 3-64 months), all patients with available data (11/12) had a good radiologic outcome (modified Raymond-Roy classification scores of 1 or 2). Two patients (18.2%) underwent re-treatment with simple coiling through the device. One of these had a subarachnoid hemorrhage prior to re-treatment. There were no major complications (death or permanent neurologic deficits) associated with use of the device.

CONCLUSION

Our series demonstrates occlusion rates that are similar to those of standard stent-assisted coiling and intrasaccular flow diversion for wide-necked bifurcation aneurysms. Larger registry-based studies are necessary to support our findings.

Results of the pToWin Study: Using the pCONUS Device for the Treatment of Wide-Neck Intracranial Aneurysms

Coil embolization has become a well-established option for the treatment of intracranial aneurysms. Yet, wide-neck bifurcation aneurysms (WNBAs) remain a challenge. The pCONUS is the first generation of a stent-like implant for the bridging of WNBAs to enable coiling. The pToWin study was a prospective, single-arm, multicenter study conducted to analyze the safety and efficacy of the pCONUS in the treatment of WNBAs. The primary effectiveness endpoint was the rate of adequate occlusion of the aneurysm at 3–6 and 7–12 months. The primary safety endpoint was the occurrence of major ipsilateral stroke or neurological death during the follow-up. A total of 115 patients were included. Aneurysm locations were the middle cerebral artery in 52 (45.2%), the anterior communicating artery in 35 (30.4%), the basilar artery in 23 (20%), the internal carotid artery terminus in three (2.6%), and the pericallosal artery in two (1.7%) patients. Treatment was successfully performed in all but one patient. The morbi-mortality rate was 1.9% and 2.3% at 3–6 and 7–12 months, respectively. Of the aneurysms, 75.0% and 65.6% showed adequate occlusion at 3–6 and 7–12 months, respectively. pCONUS offers a safe and reasonably effective treatment of WNBAs, demonstrated by acceptable adequate aneurysm occlusion and low rates of adverse neurologic events.

Comprehensive review of the recent advances in devices for endovascular treatment of complex brain aneurysms

The International Subarachnoid Aneurysm Trial (ISAT) showed superiority for endovascular treatment of ruptured aneurysms and technology has since moved on rapidly. Many approaches and technology now exist for the endovascular management of ruptured and unruptured intracranial aneurysms, which reflects their varied nature - there is no one-size-fits-all technique. We aim to provide an overview of the various classes of device and the major developments over the past decade. Coiling is the oldest of the technology and continues to demonstrate high levels of occlusion and acceptable risks, making it the default treatment choice, particularly in the acutely ruptured aneurysm setting. Advances on coiling include the use of adjuncts such as balloons, stents and fully retrievable temporary neck-bridging devices, which have facilitated the treatment of more complex aneurysms. Flow divertors have also revolutionised complex aneurysm treatment with small added risk in acute aneurysm treatment and seek to remodel the aneurysm-vessel interface without accessing the aneurysm sac. The latest development and most promising avenue appears to be intrasaccular flow disrupting devices like WEB, Contour and Neqstent that provide excellent opportunities to treat wide neck complex aneurysm with minimal mortality and morbidity and good occlusion rates and may in future replace a significant number of stent-assisted coiling too.

Flow Diversion for Middle Cerebral Artery Aneurysms: An International Cohort Study

BACKGROUND

Open surgery has traditionally been preferred for the management of bifurcation middle cerebral artery (MCA) aneurysms. Flow diverting stents present a novel endovascular strategy for aneurysm treatment.

OBJECTIVE

To add to the limited literature describing the outcomes and complications in the use of flow diverters for the treatment of these complex aneurysms.

METHODS

This is a multicenter retrospective review of MCA bifurcation aneurysms undergoing flow diversion. We assessed post-treatment radiological outcomes and both thromboembolic and hemorrhagic complications.

RESULTS

We reviewed the outcomes of 54 aneurysms treated with flow diversion. Four (7.4%) of the aneurysms had a history of rupture (3 remote and 1 acute). Fourteen (25.9%) of the aneurysms already underwent either open surgery or coiling prior to flow diversion. A total of 36 out of the 45 aneurysms (80%) with available follow-up data had adequate aneurysm occlusion with a median follow-up time of 12 mo. There were no hemorrhagic complications but 16.7% (9/54) had thromboembolic complications.

CONCLUSION

Flow diverting stents may be a viable option for the endovascular treatment of complex bifurcation MCA aneurysms. However, compared to published series on the open surgical treatment of this subset of aneurysms, flow diversion has inferior outcomes and are associated with a higher rate of complications.

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.

Endovascular embolization of wide-necked bifurcation aneurysms with the use of pCONus device: A systematic review and meta-analysis

BACKGROUND

The following study aimed to summarize the overall safety and efficacy of the pCONus device in the treatment of wide-necked bifurcation aneurysms.

MATERIAL AND METHODS

Major electronic medical databases were thoroughly searched to identify relevant studies. Data regarding the type of included studies, type of aneurysm and its location, treatment results measured in Raymond-Roy Occlusion Class (RROC) and its complications, as well as patients' neurological outcome at the discharge were extracted from the eligible studies and included in the meta-analysis. The subgroup analyses dependent on the aneurysm rupture status were also conducted.

RESULTS

A total of 8 studies (198 patients with 200 aneurysms) were included in this meta-analysis. The most common localization of the treated aneurysms was the middle cerebral artery with its pooled prevalence estimate (PPE) of 44.5%. Immediately after the procedure, RROC I (complete obliteration of the aneurysm) was observed in 46.8%, RROC II in 32.9%, while RROC III (residual aneurysm) in 20.3% of the patients. In a short-term follow-up, PPE of RROC I was 55.0%, RROC II 29.0%, and RROC III 16.1%. The PPE of intraprocedural complications was 17.3%, the most frequent were thromboembolic events, which were observed in 12.1% of all procedures. Poor neurological outcome at the discharge was noted with PPE of 9.6%.

CONCLUSIONS

The effectiveness and safety of wide-necked bifurcation aneurysm treatment utilizing the pCONus device is moderate. There is still a need for a consensus regarding the effective antiplatelet regimen in furtherance of diminishing the rate of thromboembolic events.

Use of pCONUS HPC for the treatment of unruptured wide-necked bifurcation aneurysms: early clinical experience using single antiplatelet therapy

BACKGROUND

In recent years, a growing number of stents and stent-like devices have become available to facilitate the treatment of challenging aneurysms. However, the need for dual antiplatelet therapy can limit their use, especially in ruptured aneurysms. The hydrophilic polymer coating (pHPC, phenox) is a novel glycan-based multilayer polymer that reduces platelet adhesion. This study aims to report our initial experience using the pCONUS HPC device for the treatment of unruptured wide-necked bifurcation aneurysms (WNBA) using acetylsalicylic acid (ASA) as single antiplatelet therapy (SAPT).

METHODS

We retrospectively identified all patients who were treated with the pCONUS HPC for unruptured WNBA in a multi-staged procedure using ASA as SAPT. Records were made of periprocedural complications, clinical outcome and angiographic and clinical follow-up.

RESULTS

We identified 15 patients with 15 WNBA. The average age was 69 years old (range, 41-76). Seven aneurysms were located in the middle cerebral artery, five in the anterior communicating artery, two at the basilar tip and one in the posterior communicating artery. Immediate post-treatment angiography showed five aneurysms with modified Raymond-Roy classification (mRRC) grade I and four aneurysms with mRRC grade II. There were no haemorrhagic complications. Four patients developed thrombus formation during the second treatment session, all of them completely resolving after administration of glycoprotein IIb/IIIa antagonists. Angiographic follow-up data were available for 10 patients and showed adequate occlusion (mRRC I or II) in eight aneurysms (80%). In-stent stenosis was observed in one patient whereas two patients showed de novo stenosis in one of the efferent branches.

CONCLUSIONS

This early experience on the use of the pCONUS HPC device suggests that it can be useful for treating unruptured WNBA under ASA as SAPT. Further investigation with a randomised treatment registry and larger cohort is needed.

eCLIPs bifurcation remodeling system for treatment of wide neck bifurcation aneurysms with extremely low dome-to-neck and aspect ratios: a multicenter experience

Background

Wide necked bifurcation aneurysms (WNBA) are among the most difficult aneurysms to treat. Very low dome-to-neck (DTN) and aspect ratios provide an even greater challenge in the management of WNBAs. We present the safety and efficacy profile for endovascular clip system (eCLIPs) device in the treatment of this subset of WNBAs with very unfavorable morphologies.

Methods

In our case series, 24 patients treated at 12 international centers were taken from a larger prospective voluntary post-marketing registry of 65 patients treated with the eCLIPs device and coiling. Those who had WNBAs at either the carotid or basilar terminus with a DTN ratio <1.6 and aspect ratio <1.2 were included. Radiologic and clinical outcomes were assessed immediately after the procedure and at the latest follow-up.

Results

The eCLIPs device was successfully deployed in 23 cases (96%). One patient (4.2%) died due to guidewire perforation distal to the implant site. No other complications were documented. After a mean follow-up of 15.8 months (range 3–40 months), good radiologic outcomes (modified Raymond–Roy classification (MRRC) scores of 1 or 2) were documented in 20 of 21 patients (95%) with follow-up data. The lone patient with an MRRC score of 3 showed coiled compaction after incomplete neck coverage with the device.

Conclusion

Our series of patients with aneurysms having adverse DTN and aspect ratios demonstrated that the eCLIPs device has a safety and efficacy profile comparable with currently available devices in the treatment of WNBAs.

Efficacy and safety of PulseRider for treatment of wide-necked intracranial aneurysm-A systematic review and meta-analysis

OBJECTIVE

PulseRider is a novel self-expanding nickel-titanium (nitinol) stent for treatment of wide-necked aneurysms, which is commonly located at the arterial branches in the brain. This systematic review and meta-analysis aims to assess the efficacy and safety of PulseRider for treatment of wide-necked intracranial aneurysm.

METHOD

We performed a systematic literature search on articles that evaluate the efficacy and safety of PulseRider-assisted coiling of the wide-necked aneurysm from several electronic databases. The primary endpoint was adequate occlusion, defined as Raymond-Roy Class I + Raymond-Roy Class II upon immediate angiography and at six-month follow-up.

RESULTS

There were a total of 157 subjects from six studies. The rate of adequate occlusion on immediate angiography was 90% (95% CI, 85%-94%) and 91% (95% CI, 85%-96%) at six-month follow-up. Of these, Raymond-Roy Class I can be observed in 48% (95% CI, 41%-56%) of aneurysms immediately after coiling, and 64% (95% CI, 55%-72%) of aneurysms on six-month follow-up. Raymond-Roy Class II was found in 30% (95% CI, 23%-37%) of aneurysms immediately after coiling, and 25% (17-33) after six-month follow-up. Complications occur in 5% (95% CI, 1%-8%) of the patients. There were three intraoperative aneurysm rupture, three thrombus formation, three procedure-related posterior cerebral artery strokes, one vessel dissection, and one delayed device thrombosis. There was no procedure/device-related death.

CONCLUSIONS

PulseRider-assisted coiling for treatment of patients with wide-necked aneurysm reached 90% adequate occlusion rate that rises up to 91% at sixth month with 5% complication rate.

Recent advances in stent-assisted coiling of cerebral aneurysms

INTRODUCTION

Stent-assisted coiling (SAC) of intracranial aneurysms paved the way for endovascular coiling of wide-neck and bifurcation aneurysms, improving rates of aneurysm obliteration and recurrence. In this review, we provide a comprehensive review of the most recent advances related to stent-assisted coiling of intracranial aneurysm.

AREAS COVERED

The authors have made an attempt to cover the inception, applications, and limitations of SAC of intracranial aneurysms. Special focus is given to 1) the current and recently introduced SAC techniques, 2) most recent advances in device technology, and 3) outcome data for the discussed techniques and devices. The authors also discuss the potential future direction of SAC.

EXPERT OPINION

technical refinements in the field of SAC should continue to focus on device development and addressing the limitations of SAC, namely aneurysm recurrence and need of antiplatelet agents. Although the recurrence rate of SAC has not been shown to be inferior to flow diverters, the use of intrasaccular and intravascular flow diverters are likely to expand in the future at the expense of SAC.

Advances in endovascular aneurysm management: coiling and adjunctive devices

Endovascular coil embolisation continues to evolve and remains a valid modality in managing ruptured and unruptured cerebral aneurysms. Technological advances in coil properties, adjunctive devices and interventional techniques continue to improve long-term aneurysm occlusion rates. This review elaborates on the latest advances in next-generation endovascular coils and adjunctive coiling techniques for treating cerebral aneurysms.

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.

Use of the pCONus HPC as an adjunct to coil occlusion of acutely ruptured aneurysms: early clinical experience using single antiplatelet therapy

Background

Coil occlusion has become the standard treatment for many ruptured aneurysms. However, specific aneurysm structures pose technical difficulties and may require the use of adjunctive neck-bridging devices, which necessitate the use of dual antiplatelet therapy. The hydrophilic polymer coating (pHPC, phenox) is a surface modification that inhibits platelet adhesion.

Objective

To present initial experience with the pCONUS HPC device as an adjunct to coil embolization for ruptured aneurysms using single antiplatelet therapy (SAPT).

Methods

All patients who were treated with the pCONUS HPC for ruptured aneurysms using SAPT were retrospectively identified. The occurrence of thromboembolic and hemorrhagic complications was recorded together with the angiographic and clinical follow-up details.

Results

Fifteen patients were identified (nine female) with a median age of 54 years (range 27–81). Six aneurysms were located at the anterior communicating artery, five at the middle cerebral artery bifurcation, two at the basilar artery bifurcation, one at the posterior communicating artery, and one involving the intradural internal carotid artery. Ten patients (66.6%) achieved modified Raymond–Roy classification I or II at post-treatment angiography, with 45.5% of patients having adequate occlusion (defined as complete occlusion or neck remnant) at follow-up. All patients received acetylsalicylic acid (ASA) as SAPT before and after the procedure. Intraprocedural thrombus formation was seen in three patients (20%), resolving in two patients after a bolus dose of eptifibatide, and one treated with mechanical aspiration. No clinical or radiological consequences were seen. There were no recurrent aneurysm ruptures. One patient died owing to cerebral vasospasm.

Conclusion

This initial clinical experience highlights the possibility and limitations of using the pCONUS HPC device in the treatment of complex ruptured aneurysm with ASA as SAPT. Randomized trials with longer follow-up in larger cohorts are underway.

Future Directions of Flow Diverter Therapy

The treatment of intracranial aneurysms has undergone a few very significant paradigm shifts in its history. Needless to say, microsurgery and surgical clipping served as the initial basis for successful treatment of these lesions. The pursuit of endovascular therapy subsequently arose from the desire to reduce the invasiveness of therapy. While the first breakthrough arose with Guido Guglielmi's invention of the detachable platinum coil, commercialized flow diverter therapy represents a disruptive therapy with a completely different paradigm for aneurysmal obliteration. This has not only altered the distribution of aneurysmal management strategies, but also opened the gateway to the treatment of previously inoperable lesions. With the basic flow diverter stent technology now considered an integral part of the neurointerventional armamentarium, we now consider what may lay in the future - including potential directions for research with regards to case selection; the location and type of aneurysms which may become routinely treatable; and modifications to the flow diverter, which may increase its utility and safety in terms of size, structural design, and surface modifications.

Treatment of Recurrent Wide Neck Bifurcation Aneurysm With the Barrel Vascular Reconstruction Device

We present a case of successful embolization of a recurrent wide neck bifurcation aneurysm with a Barrel vascular reconstruction device (VRD). The unique properties of this novel device allowed optimal aneurysm neck coverage during third consecutive re-treatment, ultimately resulting in complete aneurysm obliteration. The parent vessel anatomy and the neck morphology of the aneurysm, in combination with a presence of a large pre-existing coil mass, were ideal for Barrel stent placement. The expanded portion of the device conformed perfectly to the recanalized aneurysm neck, providing optimal support for additional coil embolization. This case illustrates the advantages of Barrel VRD for definitive embolization of large, recurrent, and previously coiled wide-neck bifurcation aneurysm as a reasonable alternative to other traditional treatment modalities, such as flow diversion or Y and X stenting.

Using the pCANvas neck-bridging device in treating a wide-necked aneurysm of the basilar tip

BACKGROUND AND IMPORTANCE

The endovascular treatment of recurrent wide-necked bifurcation aneurysms at the basilar tip remains very challenging. Many different techniques and devices have emerged in recent years as potential options but results remain less than controversial. The pCANvas is a relatively new device wielding neck-bridging properties with a haemodynamically active membrane acting as blood flow disrupter.

CLINICAL PRESENTATION

We present the clinical case of a patient in whom multiple endovascular and microsurgical attempts failed to achieve the definitive treatment of a large and wide-necked basilar tip aneurysm. The patient underwent successful endovascular implantation of the novel pCANvas device across the recurrent aneurysm neck. The device limited the blood flow to the anerysmal lumen and thus promoted faster thrombosis. Third month follow-up confirmed complete obliteration of the aneurysm.

CONCLUSION

The application of the pCANvas device offers a potential treatment option in difficult and recurrent aneurysms. The endovascular flow disruption is a relatively new feature aiming to create conditions for intraluminal thrombosis and is certainly promising for the treatment of complex bifurcation aneurysms.

On Flow Diversion: The Changing Landscape of Intracerebral Aneurysm Management

Uptake of flow-diverting technology is rapidly outpacing the availability of clinical evidence. Most current usage is off-label, and the endovascular community is nearer the beginning than the end of the learning curve, given the number of devices in development. A comprehensive overview of technical specifications alongside key outcome data is essential both for clinical decision-making and to direct further investigations. Most-studied has been the Pipeline Embolization Device, which has undergone a transition to the Pipeline Flex for which outcome data are sparse or heterogeneous. Alternative endoluminal devices do not appear to be outperforming the Pipeline Embolization Device to date, though prospective studies and long-term data mostly are lacking, and between-study comparisons must be treated with caution. Nominal technical specifications may be unrelated to in situ performance, emphasizing the importance of correct radiologic sizing and device placement. Devices designed specifically for bifurcation aneurysms also lack long-term outcome data or have only recently become available for clinical use. There are no major studies directly comparing a flow-diverting device with standard coiling or microsurgical clipping. Data on flow-diverting stents are too limited in terms of long-term outcomes to reliably inform clinical decision-making. The best available evidence supports using a single endoluminal device for most indications. Recommendations on the suitability and choice of a device for bifurcation or ruptured aneurysms or for anatomically complex lesions cannot be made on the basis of current evidence. The appropriateness of flow-diverting treatment must be decided on a case-by-case basis, considering experience and the relative risks against standard approaches or observation.

The pCONUS HPC: 30-Day and 180-Day In Vivo Biocompatibility Results

Background

Endovascular stents are commonly used during neurointerventional procedures; however, the concomitant use of dual anti-platelet treatment (DAPT) can limit their use. There is a need to develop stent coatings that mitigate requirement for DAPT.

Methods

The hydrophilic polymer coating is a novel glycan-based multilayer polymer that inhibits platelet adhesion. After Institutional Animal Care and Use Committee approval, 18 New Zealand white rabbits (mean weight 4.02 ± 0.51 kg) were commenced on DAPT (ASA 10 mg/kg/day and clopidogrel 10 mg/kg/day). A bare nitinol pCONUS and coated pCONUS HPC were implanted into the common carotid arteries of each rabbit. Histological examinations were performed at 30 days (n = 9) and 180 days (n = 8) to assess the acute and chronic inflammatory reactions to the pCONUS HPC. Wilcoxon/Kruskal–Wallis and ANOVA were used with p value < 0.05 considered as significant.

Results

There is no statistically significant difference in inflammation within the intima/media or adventitia at 30 days (p = 0.3901 and p = 1, respectively) or at 180 days (p = 0.144 and p = 1, respectively) between pCONUS and pCONUS HPC cohorts. There is no significant difference in the presence of granulomas or giant cells between the cohorts at either 30 days (p = 1 and p = 0.8363) or 180 days (p = 1.00 and p = 0.149). At 30 days and 180 days, there was near-complete endothelialisation of the stent struts and no significant difference between the pCONUS or pCONUS HPC (p = 0.7832 and p = 0.334, respectively).

Conclusion

pCONUS HPC stents do not elicit an acute or chronic inflammatory response in vivo with no significant difference in the tissue response to bare nitinol pCONUS stents or pCONUS HPC stents.

Endovascular Metal Devices for the Treatment of Cerebrovascular Diseases

Cerebrovascular disease involves various medical disorders that obstruct brain blood vessels or deteriorate cerebral circulation, resulting in ischemic or hemorrhagic stroke. Nowadays, platinum coils with or without biological modification have become routine embolization devices to reduce the risk of cerebral aneurysm bleeding. Additionally, many intracranial stents, flow diverters, and stent retrievers have been invented with uniquely designed structures. To accelerate the translation of these devices into clinical usage, an in-depth understanding of the mechanical and material performance of these metal-based devices is critical. However, considering the more distal location and tortuous anatomic characteristics of cerebral arteries, present devices still risk failing to arrive at target lesions. Consequently, more flexible endovascular devices and novel designs are under urgent demand to overcome the deficiencies of existing devices. Herein, the pros and cons of the current structural designs are discussed when these devices are applied to the treatment of diseases ranging broadly from hemorrhages to ischemic strokes, in order to encourage further development of such kind of devices and investigation of their use in the clinic. Moreover, novel biodegradable materials and drug elution techniques, and the design, safety, and efficacy of personalized devices for further clinical applications in cerebral vasculature are discussed.

A Virtual Comparison of the eCLIPs Device and Conventional Flow-Diverters as Treatment for Cerebral Bifurcation Aneurysms

PURPOSE

Effective, consistent, and complication-free treatment of cerebral bifurcation aneurysms remains elusive despite a pressing need, with the majority of lesions presenting in such locations. Current treatment options focus either on aneurysm coil retention, supported by a stent-like device positioned in the parent vessel lumen, or intrasaccular devices that disrupt flow within the aneurysm dome. A third alternative, i.e., the use of conventional (intraluminal) flow-diverters to treat such bifurcation aneurysms raises the problem that at least one daughter vessel needs to be jailed in such a deployment. The eCLIPs is a stent-like device that offers the possibility of flow-diversion at the aneurysm neck, without the drawbacks of daughter vessel occlusion or those of intrasaccular deployment.

METHODS

In this study the eCLIPs device was virtually deployed in five cerebral bifurcation aneurysms and compared with a conventional tubular flow-diverter device. Computational fluid dynamics (CFD) simulations of the aneurysm haemodynamic environment pre- and post-implantation were conducted, and focussed on metrics associated with successful aneurysm occlusion. Absolute and relative reductions in aneurysm inflow rate (Q) and time-averaged wall shear stress (TAWSS) were recorded.

RESULTS

The eCLIPs device was found to perform in a similar qualitative fashion to tubular flow-diverters, with overall reduction of metrics being somewhat more modest however, when compared to such devices. Aneurysm inflow reduction and TAWSS reduction were typically 10-20% lower for the eCLIPs, when compared to a generic flow diverter (FD_BRAIDED) similar to devices currently in clinical use. The eCLIPs was less effective at diffusing inflow jets and at reducing the overall velocity of the flow, when compared to these devices. This result is likely due to the larger device pore size in the eCLIPs. Notably, it was found that the eCLIPs provided approximately equal resistance to flow entering and exiting the aneurysm, which was not true for the FD_BRAIDED device, where high-speed concentrations of outflow were seen at the aneurysm neck along with local TAWSS elevation. The clinical implications of such behaviour are not examined in detail here but could be significant.

CONCLUSIONS

Our findings indicate that the eCLIPs device acts as a flow-diverter for bifurcation aneurysms, with somewhat diminished occlusion properties comparing to tubular flow diverters but without the jailing and diminished flow evident in a daughter vessel associated with use of conventional devices.

Intracranial Aneurysm: Diagnostic Monitoring, Current Interventional Practices, and Advances

PURPOSE OF REVIEW

Cerebral aneurysms are commonly diagnosed incidentally with non-invasive neuro-imaging modalities (i.e., brain MRA and/or head CTA). The first decision to be made in the management of patients with unruptured cerebral aneurysms is to determine if the aneurysm should undergo treatment as any intervention carries a risk of morbidity and mortality.

RECENT FINDINGS

The multiple risk factors that are associated with increased risk of aneurysm rupture should be evaluated (size, shape, and location of aneurysm; history of hypertension and cigarette smoking and family history of cerebral aneurysms). With the advent and rapid evolution of less traumatic neuro-endovascular surgery techniques in the past two decades, many more patients are undergoing treatment of cerebral aneurysms. The neuro-endovascular surgeon has multiple options for the treatment of aneurysms including coiling, with or without balloon/stent assistance, and flow diversion. A number of intrasaccular devices for the neuro-endovascular treatment of cerebral aneurysms are being evaluated. The percentage of patients with cerebral aneurysms treated with craniotomy and clip ligation is decreasing. This is controversial as it has direct impact in neurosurgical training and the aneurysms that are usually recommended for microsurgical clipping are the ones with challenging anatomy that cannot be treated safely with endovascular approaches. The best outcomes are achieved with management by experienced, high-volume practitioners at specialized cerebrovascular treatment centers that consist of individuals with dedicated training in neuro-endovascular surgery as well as individuals trained in open cerebrovascular neurosurgery.

Treatment of Wide-Necked Bifurcation Aneurysms : Initial Results with the pCANvas Neck Bridging Device

Background

Recently, numerous devices dedicated to the treatment of wide-necked aneurysms have become available. We present our initial experience with the pCANvas device and present the technical success rate, clinical outcome and immediate angiographic occlusion rates.

Objective

We sought to determine the efficacy of flow with the pCANvas for the treatment of unruptured intracranial aneurysms.

Methods

We performed a retrospective review of our prospectively collected data to identify patients treated with the pCANvas device between February 2015 and February 2017. The patient demographics, aneurysm characteristics, immediate and delayed clinical and radiographic follow-up data were recorded.

Results

We identified 17 patients (13 female) treated only with the pCANvas device. The average age of the patients was 60.5 ± 13.3 years (range 25–75 years). The average dome width was 7.6 ± 3.2 mm (range 3–15.8 mm), dome height 7.1 ± 3.2 mm (range 3–12.9 mm) and neck width 5.4 ± 3.2 (range 3–16.3 mm). The average aspect ratio was 1.5 ± 0.8 (range 0.6–3.7). At the end of the procedure 15 aneurysms continued complete filling of the aneurysm (Raymond Roy Classification[RRC] 3) with 2 aneurysms showing only filling of the neck of the aneurysm (RRC 2). Early follow-up angiography was available for 16 patients and at this stage 11 aneurysms showed persistent and complete filling of the aneurysm (RRC 3), 5 aneurysms showed complete occlusion of the aneurysm (RRC 1) and 7 aneurysms underwent repeat treatment with coiling.

Conclusion

The early results on the use of the pCANvas are promising; however, longer term follow-up and larger studies are required.

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.