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Paradigm shift backed by clinical evidence
From initial scepticism to “artistic simplicity”: WEB� device pioneers discuss its 15-year journey
In the time since it was awarded a CE mark for European use back in 2010, the Woven EndoBridge (WEB™) embolisation system (Terumo Neuro) has become a true mainstay in the endovascular treatment of intracranial aneurysms. It has been rigorously evaluated in a number of clinical studies to date, producing the most comprehensive and resoundingly positive body of results on any device in the history of aneurysm care, with US Food and Drug Administration (FDA) approval at the end of 2018 and ever-increasing uptake across Asia having also been achieved more recently. As pioneers and leading educators in the neurointerventional space, Jacques Moret (Bicêtre Hospital, Paris, France) and Saruhan Çekirge (Liv Hospital, Ankara, Türkiye) have both observed the entirety of this 15-year journey, each contributing significantly to the development and global expansion of the WEB device.
MORET CONCEDES THAT, WHEN HE was initially approached by a representative from Sequent Medical—the original developer of the WEB system that Terumo acquired in 2016—he was “a little bit sceptical” about the device.
“I couldn’t really imagine that it would be easy to manipulate and manage to occlude the aneurysm neck, because I wasn’t expecting it to fit properly into the sac of the aneurysm,” he explains.
However, a few WEB device cases later— roughly 20 procedures, he recalls—Moret observed that it was able to successfully conform to many different aneurysm types, and could be adjusted to suit a variety of shapes and sizes with relative ease. As such, he and his colleagues quickly came to realise that the WEB device held “tremendous potential” as a “real gamechanger” in endovascular aneurysm treatment.
Çekirge’s recollection of the early days of the WEB system paints a similar picture. He too harboured reservations over intrasaccular therapies and their utility in aneurysm care; but, “almost immediately”, Çekirge came to appreciate the “artistic simplicity” of WEB device treatments, as they created the possibility for more straightforward procedures that could be completed within just a few minutes while also removing the need for antiplatelet medications.
“It was amazing,” he adds. “I could see after only a few cases that the future of this device was very bright.”
A new mindset
“What we realised,” Çekirge continues, “was that WEB [device] treatments were—as the Americans say—a different ballgame. It required a change in mindset for the operators. The treatments were very quick,
wonderful example that should be copied”.
“The introduction of the device started with GCP [good clinical practice] studies, which was so important in creating very valuable data,” Çekirge posits. “There was a question mark over the stability of the aneurysm occlusion because, as I said, this was a mindset change, but we started to see different angiographic occlusion results with the WEB system compared to the coils we used to have.”
but they required operators to spend a lot of time in front of workstations to determine the ideal sizing of the device. We used to look at the aneurysm, plan the procedure, and then try to perform a lot of technical tricks in the operating room, but this was completely different. [With the WEB device], you had to sit and work on the aneurysm anatomically, and define the ideal size—and then deployment was just so easy!”
Çekirge and Moret are in agreement on this point, and on the importance of instilling these new attitudes into subsequent generations of neurointerventionists. Moret highlights the fact that, while the safety of the WEB device quickly became evident in clinical practice, the understanding of optimal sizing—and, in particular, the benefits of ‘oversizing’— emerged progressively as operators gained experience. This evolution reflects growing expertise within the field and contributes to increasingly successful outcomes.
“I want to emphasise that the success of the device comes from its architecture and its design—there is no question about this,” Moret adds. “However, another very good thing Sequent did was putting all of the WEB [device] cases into a study from the beginning. So, very rapidly, after just one year, we had results that were really helping us [improve our understanding] as quickly as possible.”
Robust evidence
Reflecting on the many high-level clinical studies within which the WEB device has been evaluated—most notably the WEBCAST, WEB-IT, CLARYS, CLEVER and French Observatory studies—Moret states that these efforts represent “a
Digging deeper into how it differed from previous endovascular aneurysm treatments, Çekirge says that the simplicity and practicality—and, ultimately, the safety— associated with the WEB device set it apart from any of the other solutions that had come before it. He draws attention to the 0% mortality rate from analyses of more than 300 “very complex” bifurcation aneurysm patients in the WEBCAST, WEBCAST-2 and WEB-IT studies as evidence of this.
“This is something that was impossible to reach with other techniques, and that’s why the device gained worldwide acceptance,” Çekirge adds.
Remodelling the future
Moret notes that, in contrast to the coilingfirst philosophy that he and many of his colleagues held for years prior to an intrasaccular option becoming available, younger generations now increasingly reach for the WEB device rather than an embolisation coil at the beginning of an aneurysm case.
“The safety and ease of delivering the procedure—especially now that we have smaller sizes and can go through an 017 microcatheter—means there is a big difference compared to the perception we used to have,” he avers.
Providing a look to the future, Çekirge highlights the continued efforts of Terumo Neuro to further enhance the device— positing that “there is no end to technical evolution”—and says operator training and education will play a key role in the WEB system becoming even more widely accepted across the globe.
“It’s an indispensable tool in the armamentarium of neurointerventionists treating aneurysms—and it has to be taught like that,” he concludes. “Any new fellow will learn remodelling and coiling, and they have to learn this too. It’s very important that centres around the world are trained on this technique and can adapt their practice accordingly, especially in wide-neck and ruptured aneurysms.”
Jacques Moret Saruhan Çekirge
Fifteen years of WEB embolisation system
WEB™ device continues trajectory backed by “incredible” clinical outcomes
Having performed the world’s second ever treatment with the WEB™ device, Laurent Pierot (Reims University Hospitals, Reims, France) has played an integral role from the beginning of the system’s 15-year journey, also going on to lead the seminal WEBCAST and WEBCAST-2 studies as principal investigator.
POSITIVE EARLY RESULTS
FROM this prospective research paved the way for the system to become an established option in aneurysm care—and, in 2022, were further bolstered by five-year follow-up data demonstrating safety and efficacy in the 100 patients included across both studies. In Pierot's view, such an extensive, long-term body of clinical evidence is “very rare” in the study of endovascular aneurysm treatments.
“It’s important to have an idea of the stability of the anatomical results and safety in the long term,” he notes. “In WEBCAST and WEBCAST-2, we had no delayed complications, confirming the great safety outcomes depicted at one month and one year. It’s also the first [endovascular aneurysm] device associated with a 0% rate of mortality, which is quite incredible.”
Pierot goes on to highlight the absence of thromboembolic and haemorrhagic
Five-year
WEB-IT data add to unparalleled evidence on device’s longterm success
Subsequent to the positive findings observed with the WEB™ system across multiple European studies, WEB-IT— launched more than a decade ago— has provided the neurointerventional community with “definitive evidence” of the device’s durability as a safe and effective aneurysm treatment.
FIVE-YEAR DATA FROM THE STUDY were published by principal investigator Adam Arthur (Semmes-Murphey Clinic, Memphis, USA) et al in the Journal of NeuroInterventional Surgery in 2023, ultimately reporting no instances of bleeding or rebleeding during follow-up, no new device- or procedure-related adverse events beyond the first year, and high rates of both adequate (87.2%) and complete (58.1%)
complications across both studies as evidence of the fact the WEB device is “probably the safest endovascular aneurysm treatment” available right now.
Five-year data from the WEBCAST studies—published by Pierot et al in the Journal of NeuroInterventional Surgery have also elucidated the device’s efficacy, as per adequate and complete occlusion rates of 77.9% and 51.6%, respectively, as well as a retreatment occurrence of 11.6%.
Pierot notes that this “completely acceptable” reintervention rate is particularly significant given that recanalisation is seen relatively frequently following coiling treatments.
Another “very important” detail he touches on relates to the majority (87.8%) of aneurysms remaining stable or improving between years one and five across both of the WEBCAST studies.
“With coiling, the only possibility you
occlusion, across an enrolled cohort of 150 wide-necked bifurcation aneurysm patients.
“These data should provide significant comfort to healthcare providers, as well as patients and their families,” Arthur comments. “The amount and quality of clinical evidence indicating that the WEB device is a very safe and effective strategy really eclipses what we have for any other aneurysm therapy.”
While the system is generally considered to be a simpler, more reproducible approach compared to coiling, Arthur is keen to emphasise that dedicated physician training and proctoring, and practising via silicone models prior to in-human procedures—key methods utilised in preparation for WEB-IT—remain vital, and are often “hugely beneficial”.
can have after one year is worsening—it’s not technically possible to have an improvement,” Pierot explains. “But, with the WEB device, we see improvements in the occlusion status after one year in a significant number of patients, and most of the worsening we see goes from complete occlusion to a neck remnant, which is still [clinically] acceptable.”
Finally, outlining some key real-world considerations, Pierot highlights greater ease of use, shorter procedure duration and reduced radiation exposure versus coiling as potential reasons for the WEB system’s evergrowing uptake worldwide.
“What does the future hold? In my mind, an increasing place for the intrasaccular treatment of both ruptured and unruptured aneurysms over the next few years,” he adds. “For widenecked bifurcation aneurysms, the WEB device will probably become the first-line treatment, because we now have 15 years of experience, and it’s easier than stent- or balloon-assisted coiling. And, following the CLARYS and CLEVER studies, we’re definitely seeing an increasing usage of [the system] in ruptured aneurysms, from year to year, and progressively less aneurysm coiling too.”
term, Arthur et al’s publication reports that— across 82 patients with available occlusion status data at both one and five years—76.8% of aneurysms remained stable or improved with no retreatment between these timepoints.
“I’m proud of that approach,” he continues. “I’ve received criticism that the WEB-IT results were unrealistically good because we were so careful about training and patient selection but, if I’m the patient, that seems like a very good approach to me. In WEB-IT, we were lucky to have phenomenal physicians who were very receptive to learning something new and different to what they’d done previously, and it’s because of that attitude that the results are so good.”
In addition to demonstrating that the study’s promising one-year data had endured long
WEB-IT’s five-year results also reveal a 15.5% retreatment rate—an “interesting” finding that, in Arthur’s view, aligns with the notion that retreatments are more frequent after coiling and intrasaccular therapies in the USA compared to Europe. Discussing his own paradigm for post-WEB [device] reintervention, Arthur says he attempts to outline all available options to his patients and provide them with “clear recommendations”, informed by multidisciplinary team meetings and backed by clinical evidence, while also emphasising that “this is their decision, and they’re in charge”.
Arthur concludes by alluding to how WEB device treatments may evolve further, averring: “Neurointerventionists are receptive to better clinical evidence informing their choices and, as such, I think it will continue to be used very widely. I’d love to see intrasaccular flow disruption carry on iterating to provide more treatment options, and even better long-term safety and efficacy—although I recognise that’s a challenge given how good the data are already.”
Laurent Pierot
Adam Arthur
Expanding aneurysm care
WEB™ device’s safety
and
efficacy in
ruptured cases bolstered by analyses spanning hundreds of patients
Multiple recent study analyses have challenged initial beliefs that the WEB™ device may only be strictly appropriate in the treatment of unruptured aneurysms, with findings spanning hundreds of patients indicating rebleeding and complication rates that compare favourably to other endovascular options—as well as positive clinical and occlusion-related outcomes—in ruptured aneurysm management.
AS SUCH, IN THE VIEW OF WALEED Brinjikji (Rochester, USA)—a leading author for one of these analyses—the device can now be considered a standard-of-care approach in ruptured wide-necked bifurcation aneurysms, and he anticipates continued growth in its utilisation in these cases, adding: “I’ve seen many people shift to a WEB system-first strategy for ruptured aneurysms”.
A 2021 systematic review and meta-analysis published by Brinjikji et al in the American Journal of Neuroradiology including almost 500 ruptured aneurysms across 18 studies ultimately revealed rates of 1.1% for late rebleeding, 3.2% for clinical complications, 2.1% for procedure-related mortality, and 5.1% for retreatment. In addition, favourable clinical outcomes were achieved in 85% of
“Tremendous” results with WEB™ system may alter mindsets in ruptured aneurysms
With two large, prospective, multicentre studies—CLARYS and CLEVER— having produced “tremendous” results in treating ruptured aneurysms using the WEB™ system, Laurent Spelle (Bicêtre Hospital, Paris, France) believes the device will become increasingly popular in these cases as physician confidence grows accordingly.
“WHEN DEALING WITH A ruptured aneurysm located in a bifurcation, even if it has a small neck, all the physicians in our team are prone to using the WEB system; it has been very quickly adopted. Usage of the device has become the gold
patients, while overall adequate occlusion at final follow-up was 87.3%.
These data have since been bolstered by the findings of a larger meta-analysis published in Neuroradiology earlier this year, with researchers detailing a rebleeding rate of 0.3%, overall complication rate of 12.8%, procedure-related mortality rate of 0.4%, retreatment rate of 7.5%, 90-day favourable clinical outcome rate of 87.3%, and 12-month adequate occlusion rate of 83.8%, across more than 1,000 ruptured cases.
Both analyses’ authors subsequently posit that the WEB device appears to be a safe and effective option in ruptured aneurysms, with the latter paper concluding that data support its wider adoption in clinical practice.
“The most important thing to consider when
standard—not only in our department, but in many centres around the world,” he comments. “It is easy to use and, importantly, very safe. Its safety is a major result across all the studies we have conducted to date.”
CLARYS assessed the device in ruptured aneurysms only, while CLEVER evaluated ruptured and unruptured aneurysm treatments with the newer, low-profile WEB 17 device. Spelle was a leading investigator for both studies, which were published in the Journal of NeuroInterventional Surgery in 2022 and 2024. Twelve-month data showed that zero instances of rebleeding occurred in more than 200 patients treated across both studies. In addition, CLARYS found a 0% rate of WEB device-related morbidity and mortality, as well as 87% adequate and 41.3% complete occlusion rates, with six patients undergoing target aneurysm retreatment. CLEVER produced similar adequate occlusion, 73.1% complete occlusion and 1.8% retreatment rates at one year solely in ruptured aneurysm cases.
you’re treating any ruptured aneurysm is to prevent rebleeding—at least in the acute phase and, preferably, in the very long term,” Brinjikji comments. “I think the fact that rebleeding rates are so low—essentially similar to what we see with coiling, and possibly even with clipping—basically tells us that the WEB device is an effective treatment in ruptured aneurysms. And, the procedural safety rates are very important as well.”
Brinjikji goes on to state that the high adequate occlusion rates observed across both meta-analyses suggest that, “provided you continue to monitor patients”, it represents a “durable” treatment for ruptured cases.
“If you look at large datasets on coiling, the safety profile of the WEB system is much better, and I think we’ll see that more and more, as younger generations are going to be a lot less familiar with coiling when these one-and-done options are available,” he adds.
“Ultimately, we’re not treating the aneurysm—we’re treating the patient. The one thing you don’t want is for your procedure to make the patient’s clinical outcomes worse, and the fact WEB [devices] do that so much less often than coiling is something people should definitely be considering.”
in many countries outside Europe and the USA, clipping is still very [common]. So, as neurosurgeons come into our field, I think they will become increasingly convinced that using the WEB system for this indication is very beneficial for the patient, especially now we have long-term data.”
Spelle also admits that, given the wealth of high-level evidence supporting its safety and efficacy, he is unsure why some physicians remain reluctant to utilise the device in ruptured cases. He goes on to posit that, while simpler, proximally located aneurysms can be managed successfully with WEB 21, the availability of WEB 17 is “definitely a gamechanger” that makes it “much easier” to treat more complex aneurysms in angulated anatomies or distal locations.
“We have the data to scientifically prove that using the WEB device in ruptured aneurysms is safe, and we will have more in the future,” Spelle says, reflecting on these findings. “So, physicians have to gain confidence through training and exposure to the technique.
“For most ruptured bifurcation aneurysms
Spelle concludes by stating that a number of remaining, currently unanswered questions— including reasons for the discrepancy between ruptured aneurysm complete occlusion rates in CLARYS versus CLEVER, and the observed trend towards higher complete occlusion rates in patients not receiving postprocedural antiplatelet or anticoagulant therapy in CLEVER—are set to be examined further in the WISE study, whereby researchers will collate and analyse all of the currently available clinical data on the WEB device.
Waleed Brinjikji
Laurent Spelle
“Empiric,
practical” guide to WEB™ system oversizing ensures sufficient lateral compression in clinical setting
Following the WEB™ device’s US approval, Josser Delgado (Abbott Northwestern Hospital, Minneapolis, USA) began to use the implant “very routinely” at his centre from 2019 onwards. In addition to the many benefits he and his colleagues found with the technology, they quickly realised that—due to the relevance of the percentage of lateral compression (%LC) achieved by the device once inside an aneurysm—sizing conventions could play a key role in dictating treatment outcomes.
“IT BECAME APPARENT THAT, FOR example, trying to oversize a 4mm device by a full millimetre was probably too much.”
Delgado states. “We started to notice that the +1/-1 rule likely didn’t apply across the whole spectrum of WEB [device] sizes. And, for larger devices, we realised you may need more than one millimetre of LC.”
Delgado’s team therefore set out to shed more light on the appropriate degree of ‘oversizing’ across different WEB implants, conducting a retrospective review of 155 patients—published in Neurosurgery Practice in 2023—in which they demonstrated %LC to be the single most important predictor of aneurysm occlusion at both first and last follow-up after WEB device treatments. Their research revealed that optimal %LC thresholds for complete and adequate occlusion at first follow-up were >17.1% and >15.7%, respectively. Delgado et al report that, compared to aneurysms in which
these thresholds were not attained, WEB device treatments attaining these thresholds saw significantly higher rates of complete (31% vs 68%) and adequate (81% vs 96%) occlusion. They also found %LC to be an independent predictor of retreatment, as cases with ≤15.6% LC demonstrated a much higher retreatment rate versus those with >15.6% LC (15% vs 4%).
“While 15.7% was a good threshold for adequate occlusion, that includes neck remnants, which [many operators] don’t like to leave behind,” Delgado states. “But we were able to show that, if you bump that threshold up to 17.1%—so, a little more LC— then that will maximise the chances of complete occlusion.”
Today, in clinical practice, Delgado’s centre uses a series of “empiric, practical” thresholds extrapolated from these data, ranging from ≥0.4mm for a 4mm-wide device, ≥0.5mm for a 4.5mm device, and ≥0.7mm for a 5mm device, to ≥1mm covering all 6–8mm devices and
LC manipulation could broaden applicability of WEB� device
“The technique is straightforward, easy to adopt across all experience levels, and has proven safe and effective in both elective and emergency settings,” says Han Seng Chew (Queen Elizabeth Hospital, Birmingham, UK), discussing a novel technique that—in his view—could significantly broaden the range of aneurysms that can be treated using the WEB™ system.
IN 2024, CHEW ET AL PUBLISHED A study evaluating lateral compression (LC) manipulation of the device as a means for managing elongated, ‘taller-than-wide’ aneurysms in Neurointervention. Their retrospective, single-centre analysis identified 25 eligible patients (76% ruptured) across a 10-year period, with aneurysm height exceeding width by an average of 2.33mm.
“The official sizing chart for the WEB device [...] offers no guidance for elongated aneurysms that are taller than they are wide,” Chew explains. “To accommodate these cases, we need a different strategy that expands the aneurysm size range without requiring additional fixed-size WEB devices. Through experience, we've observed that certain sizes can be interchangeable as long as the combined sum of their height and width remains constant.
For instance, a 7x5mm and an 8x4mm device are functionally equivalent. This observation allows us to address elongated aneurysms by inverting the height and width when selecting a device, effectively broadening the applicability of existing WEB [device] sizes.”
Chew et al found that 20 out of 25 cases adhered to the sizing convention outlined above, resulting in a 100% success rate for adequate occlusion and a 70% rate of complete occlusion. However, outcomes for the five cases that did not follow the proposed sizing method were less favourable; four were treated with undersized WEB devices and showed neck remnants during follow-up, while one patient received an oversized WEB device and required device replacement.
The researchers therefore conclude that the proposed approach appears to elicit promising
≥1.5mm for 9–11mm devices. This guideline has proved easy to remember and apply in the real world, Delgado says, also relaying that subsequent research has revealed no performance differences between these ranges and the percentages outlined in the 2023 study.
“It has really become second nature in our clinical practice,” he avers. “I don’t sit there and measure every single WEB [device] anymore. Now that we’re so attuned to oversizing as much as we can, I only really measure them if I’m worried that I might be undersized!”
Delgado comments that the percentages detailed in his team’s Neurosurgery Practice paper should be viewed as minimum thresholds for device oversizing, and he typically deploys the widest WEB system he believes can be accommodated inside the aneurysm.
“In general, the more LC you can get, the better—especially in medium-sized aneurysms of 5–8mm, which constitute most of the aneurysms we treat,” he adds. “These are the cases where LC is particularly important.”
results, and may allow the WEB system to address double the original range of treatable aneurysm sizes without compromising safety or angiographic outcomes.
According to Chew, in addition to its simplicity, key advantages of this method include improved inventory management and obviation of the need for larger-calibre delivery catheters typically used alongside longer devices. He also notes that this sizing principle can even be applied successfully in irregular aneurysm shapes, advising that only the primary lobule capable of accommodating the WEB device should be considered when determining its dimensions.
“Importantly,” Chew adds, “our data show that the increased LC resulting from this strategy does not increase aneurysm wall injury risks, even in acutely ruptured cases. In addition, the increased LC often improves the likelihood of achieving durable, complete aneurysm occlusion. These findings strongly support broader adoption of this method as a means to simplify sizing, expand treatment indications, and maintain high safety and efficacy standards in WEB [system] embolisation.”
Han Seng Chew
Josser Delgado
Current practice and beyond
Meta-analysis reveals clinical improvements and comparable occlusion outcomes with WEB� device versus SAC
Last year, Elad Levy (University at Buffalo, Buffalo, USA) and his colleagues published a comprehensive systematic review and meta-analysis in the Journal of Neurosurgery comparing the WEB™ device to coiling—both with and without stent assistance—in the treatment of bifurcation and wide-necked aneurysms. Here, Levy discusses the findings of this research as well as outlining key considerations when opting to treat aneurysm patients using WEB..
“IT’S
AS I TELL THE STUDENTS
and the residents: if it looks like an aneurysm that would be suitable for the WEB device, then the WEB device is a great option,” he explains. “We don’t try to force the technology into aneurysms where it doesn’t belong like oblong-shaped or multilobulated aneurysms but, for a broad base of round, wide-necked aneurysms, it’s a great choice— especially in a ruptured setting where you want to avoid stents and antiplatelets.”
Recent data
The findings of Levy et al’s 2024 metaanalysis can be seen to support the notion that the WEB device is not only a safe and effective treatment option in its own right, but also when evaluated against coil embolisation.
Ultimately including a total of 16 studies comparing the WEB system versus primary coiling (PC) or stent-assisted coiling (SAC), the researchers split these different endovascular approaches into three groups, finding them to be generally comparable in terms of baseline characteristics.
The analysis revealed lower complete and adequate occlusion rates in the WEB device group versus both PC and SAC on imaging performed immediately after the procedure, but subsequently demonstrated comparable rates of both complete and adequate occlusion across all groups upon later follow-up evaluations.
Levy describes the inferior immediate occlusion results seen with the WEB system in this analysis as a “fair criticism” of the device, even when considering the fact that this did not appear to translate into worse clinical outcomes, also noting that re-access and retreatment are typically more complex relative to coiling.
“The way to avoid this is to not stretch the technology,” he posits. “Don’t try to place a WEB [device] in an aneurysm that is really suboptimal—things like multilobe aneurysms, or ones that are oblong- or inverted cone-shaped.”
Clinical outcomes
Regarding clinical endpoints, Levy et al found that patients in the WEB device group experienced significantly fewer unfavourable neurological outcomes (modified Rankin scale [mRS] >2) than the SAC group, while these outcomes were comparable between the WEB device and PC groups.
In addition, retreatment rates were comparable between the WEB system and coiling. And, although the WEB device group demonstrated fewer haemorrhagic and thromboembolic complications, similar results in terms of neurological and procedure-related complications—and
Levy attributes this to the ‘one-and-done’ nature of the WEB device, highlighting the “inherent efficiency” of these treatments in contrast to the multiple implants required for coiling procedures.
Ruptured cases
In addition to these primary results, subgroup analyses of Levy et al’s findings revealed that rupture status had no significant bearing on between-group occlusion outcomes or retreatment rates.
However, unfavourable clinical outcomes were found to be less frequent with the WEB device versus coiling in ruptured cases, while clinical outcomes were comparable between the two approaches in unruptured cases.
Additionally, the WEB device achieved a lower complication rate versus SAC in ruptured cases—although this trend did not endure in unruptured cases, and complication rates were statistically similar between the WEB device and PC.
“I think the WEB device is an excellent choice in a ruptured setting, especially in wide-necked aneurysms where clipping isn’t an option and you want to avoid placing a stent,” Levy comments, reflecting on these data. “We’ve had a lot of success [with the WEB system] in these ruptured settings.”
I think the WEB device is an excellent choice in a ruptured setting, especially in widenecked aneurysms where clipping isn’t an option and you want to avoid placing a stent.”
mortality rates—were seen with the WEB device compared to both coiling modalities.
The authors conclude that these data, in combination with the reduced costs they found to be associated with the WEB device, should serve to establish it as a safe and effective treatment in the treatment of bifurcation and wide-necked aneurysms.
Another noteworthy finding of the analysis was that both procedure duration and fluoroscopy time were significantly reduced in patients treated with the WEB device as compared to endovascular coils.
Training and experience
In their paper, Levy et al also put forward the idea that retreatment rates and other outcomes observed with the WEB device to date may be ameliorated as operator experience with the device continues to grow.
Here, Levy reiterates this point, highlighting the integral role of training and practise in maximising the likelihood of procedural success and, ultimately, increasing the chances of positive clinical outcomes being achieved.
“As with a lot of things, if you know how to use a tool correctly, then it’s very safe,” he says. “Once it unfolds and begins to ‘flower’, it is soft, supple and very safe.
“And, as operators become more comfortable with it, they find that there’s something of an art to using it. One can mould it, shape it and almost cajole it into optimally fitting inside an aneurysm.
“I think the learning curve comes with understanding how much one can ‘oversize’ the width relative to the height. It’s about device selection and device sizing. And, at high-volume centres, like anything else, it’s about time in the saddle.
“In my opinion, the amount of experience you have with the technology is very apropos for the WEB device.”
Elad Levy
Fifteen years of WEB embolisation system
WEB™ system shows "versatility and durability" across wide array of cases
As per a study encompassing 169 aneurysms in 161 patients, the WEB™ device appears safe and effective across a wide range of case types—potentially expanding its usage far beyond the wide-necked bifurcation aneurysms it was originally developed for. Findings from this multicentre, retrospective analysis were published last year in World Neurosurgery by Hamed Asadi (Deakin University, Melbourne, Australia) and colleagues.
ASADI ET AL’S CASE SERIES included wide-necked bifurcation but also sidewall and irregularly shaped aneurysms, as well as cases previously managed with alternative strategies, and aneurysms managed using the WEB device alongside adjunctive devices like coils, balloons and stents.
“We were increasingly encountering aneurysms that didn't fit neatly into the classical wide-necked bifurcation category, yet posed significant treatment challenges, as traditional options were limited or carried higher risks,” Asadi says, also explaining that his team’s growing confidence in the device and its versatility led them to expand its use. “It became clear to us that [the device's] mechanical properties could be applied more broadly.”
Across a plethora of varied and complex aneurysm cases, 70 of which were ruptured,
Could high-res CTA enable more practical WEB� device follow-ups?
While digital subtraction angiography (DSA) is widely considered the goldstandard imaging modality in followup evaluations of WEB™ device treatments, the approach is not without its limitations—a fact that led Ichiro Nakahara (Fujita Health University Bantane Hospital, Nagoya, Japan) and colleagues to compare DSA occlusion statuses to those obtained with the more novel technique of high-resolution computed tomography angiography (HR-CTA) via a recent study.
DESPITE THE PROVEN VALUE OF DSA imaging, its invasive nature—and the potential thromboembolic and haemorrhagic complications this can lead to—makes conducting these evaluations before, during and multiple times after a WEB implant procedure potentially burdensome for the
Asadi et al observed an 85.6% adequate occlusion rate and an 86.7% rate of good functional status at latest follow-up—as well as procedure-related mortality, procedurerelated haemorrhage and thromboembolic complication rates of 0.6%, 1.2%, and 7.1%, respectively. Additionally, there were no instances of postoperative re-rupture.
“Once adequate occlusion was achieved initially, the results were very stable over time. Compared to other endovascular modalities, the WEB device has shown excellent durability,” Asadi comments, also noting that positive occlusion outcomes and retreatment rates (5.9%) were sustained out to five years.
Furthermore, across 14 cases in which a WEB device was deployed following prior treatment failure, analyses revealed an adequate occlusion rate close to 70% with no
patient. Meanwhile, HR-CTA may be able to deliver a comparable level of diagnostic accuracy versus DSA in addition to being a non-invasive modality, which eliminates catheterisation and, thus, reduces associated risks and patient discomfort.
Nakahara’s team therefore conducted a single-centre, retrospective study to ascertain concordance between DSA and HR-CTA in measuring occlusion status, analysing 250 aneurysm cases treated with the device from January 2021 to December 2024. Their findings were published in the Journal of NeuroInterventional Surgery earlier this year.
procedure-related mortality. Asadi says the device was “particularly useful” in such cases, ascribing this to its intrasaccular flowdisruption mechanism being “fundamentally different” to approaches like coiling.
“These results highlight [its] versatility and usefulness as a salvage option in anatomically or technically challenging recurrences, and reinforce our view that it can serve as an effective second-line treatment when other strategies have not succeeded,” Asadi adds, before also advising his peers on contexts within which techniques adjunctive to the WEB device—utilised in close to 20% of cases in the analysis—may be required.
“The decision typically arises when we’re dealing with particularly wide necks, branch vessel incorporation, or unstable device positioning,” he concludes. “In these situations, adjunctive coiling, ballooning or stenting is helpful to optimise aneurysm occlusion and maintain parent vessel patency. Essentially, the anatomical complexity and potential for WEB [device] instability are the main prompts for employing adjunctive strategies—and these decisions are always driven by the anatomy in front of us, and the need to ensure both occlusion and vessel safety.”
proving accurate in identifying aneurysm remnants (BOSS 3). Univariate analyses performed by Nakahara et al found cases of no residual flow inside the aneurysm but with opacification of the proximal recess (BOSS 0’) to be the only significant factor contributing to these discrepancies.
“As our study indicates, the concordance between DSA and HR-CTA is very high,” Nakahara relays. “On binary evaluations [adequate versus inadequate occlusion], it was perfect. The agreement rate was 100%.”
Furthermore, when utilising the Bicêtre occlusion scale score (BOSS)—which is specific to intrasaccular aneurysm treatments and provides a more detailed delineation between occlusion statuses—Nakahara et al observed a “very high” concordance rate of 85.2% between DSA and HR-CTA.
A closer look at these data also reveals that all eight instances of discordance between the two modalities stemmed from HR-CTA overestimating the occlusion status, despite
Discussing the significance of this, Nakahara explains that slight disagreements between DSA and HRCTA over BOSS 0’ occlusion statuses do not represent a major concern— and are ultimately “acceptable”—due to there being no clinically significant difference between BOSS 0’ and complete occlusion (BOSS 0).
While Nakahara has retained a preference for DSA imaging at the preprocedural stage and at one year in WEB device patients—also conceding that high associated costs mean HR-CTA machines are not available at every centre—he feels this novel modality can offer a practical, patientfriendly alternative for intermediate-length follow-up evaluations, such as at three or six months. Nakahara adds that the image quality of current HR-CTA systems could be further enhanced over the coming years too.
“Clinically, it is very good but, in terms of precise radiological diagnoses, it is not perfect,” he says. “Hopefully, this will be [improved] in the near future.”
1. Data on File, Terumo Neuro. 2. Pierot L, Szikora I, Barreau X, et al. Aneurysm treatment with the Woven EndoBridge (WEB) device in the combined population of two prospective, multicenter series: 5-year follow-up. J Neurointerv Surg. 2022. 3. Fiorella D, Molyneux A, Coon A, et al. Safety and effectiveness of the Woven EndoBridge (WEB) system for the treatment of wide necked bifurcation aneurysms: final 5 year results of the pivotal WEB Intrasaccular Therapy study (WEB-IT). J. Neurointerv Surg.
WEB US Indications for use:
The WEB Aneurysm Embolization System is indicated for use at the middle cerebral artery (MCA) bifurcation, internal carotid artery (ICA) terminus, anterior communicating artery (AComm) complex, or basilar artery apex for the endovascular treatment of adult patients with saccular, wide neck bifurcation intracranial aneurysms with dome diameter from 3 mm to 10 mm and either neck size 4 mm or greater or the dome-to-neck ratio is greater than 1 and less than 2. Caution: Federal (USA) law restricts this device to sale, distribution and use by or on the order of a physician. Indications, contraindications, warnings, instructions for use, pictures, and figures for the WEB Aneurysm Embolization System can be found in the Instructions for Use provided with the Device. Contraindications: Patients with known active bacterial infection that may interfere with or negatively affect the implantation procedure. Patients with known hypersensitivity to nickel. Warnings: The WEB Aneurysm Embolization System (see Figure 1) is provided sterile and nonpyrogenic unless the unit package is opened or damaged. Do not use if the packaging is open or damaged. Use before expiration date noted on the product packaging. The WEB Aneurysm Embolization System is intended for single use only. The detachment control device is intended to be used for one patient. Do not resterilize and/or reuse the WEB embolization device. Reuse and/or resterilization can increase risk of infection, cause a pyrogenic response or other life-threatening complications. Reuse and/or resterilization can degrade product performance, leading to WEB embolization device malfunction. Dispose of all WEB embolization devices in accordance with applicable hospital, administrative and/or local government policy. The safety and effectiveness of the WEB embolization device in areas other than those identified in the Indications for Use has not been established. The safety and effectiveness of the WEB embolization device has not been established for ruptured intracranial aneurysms. The safety and effectiveness of the WEB embolization device has not been evaluated or established in intracranial aneurysms that were previously treated. High quality, digital subtraction fluoroscopic road mapping, with orthogonal views is recommended to achieve correct placement of the WEB embolization device. Do not allow an inappropriately sized or non-optimally positioned WEB embolization device to reside in the aneurysm significantly beyond the activated clotting time (ACT). Experience has shown that thrombus formation can also prevent the WEB embolization device from full deployment and recapture. To minimize the risks of potential complications, the status of the patient’s anti-platelet medication regimen should be considered when deciding to remove the entire WEB embolization device from the aneurysm prior to deployment/detachment for replacement by a new WEB embolization device. Use of the WEB embolization device in anatomy with severe tortuosity, stenosis, or vessel narrowing may result in difficulty or inability to deploy the subject WEB embolization device and can lead to damage of the WEB embolization device or microcatheter. The safety and effectiveness of the WEB embolization device has not been established for patients taking anticoagulants or who have a known blood dyscrasia, coagulopathy, or hemoglobinopathy. The WEB embolization device must be delivered only through a compatible microcatheter with a PTFE inner surface coating. If an incompatible microcatheter is used, damage to the WEB embolization device and delivery device may occur and necessitate removal of both the WEB embolization device and microcatheter from the patient. Advance and retract the WEB embolization device slowly. Do not advance the delivery device with excessive force. Determine the cause of any unusual resistance. Remove the WEB embolization device if excessive friction is noted and check for damage. Do not rotate the delivery device during or after delivery of the WEB embolization device. Rotating the WEB embolization device may result in damage or premature detachment. The WEB embolization device cannot be detached with any other power source other than a WEB detachment control device. Ensure that at least two WEB detachment control devices are available before initiating an embolization procedure. Precautions: Large bore microcatheters may have a higher probability of developing a thromboembolic event in the parent vessel. The WEB embolization device should be used only by physicians trained in percutaneous, intravascular, and neurovascular techniques and procedures at medical facilities with the appropriate fluoroscopic equipment. The WEB embolization device should be used by physicians who have received appropriate training for this WEB embolization device. Carefully weigh the benefits of treatment vs. the risks associated with treatment using the WEB embolization device for each individual patient based on their medical health status and risks factors for intracranial aneurysm rupture during their expected life time such as age, medical comorbidities, history of smoking, intracranial aneurysm size, location, and morphology, family history, history of prior asymptomatic subarachnoid hemorrhage (aSAH), documented growth of intracranial aneurysm on serial imaging, presence of multiple intracranial aneurysms, and presence of concurrent pathology. The benefits of WEB embolization device use may not outweigh the risks associated with the WEB
embolization device in certain patients; therefore, judicious patient selection is recommended. Limit the exposure to X-ray radiation doses to patients and physicians by using sufficient shielding, reducing fluoroscopy times, and modifying X-ray technical factors when possible. The WEB embolization device may create local field inhomogeneity and susceptibility artifacts during magnetic resonance angiography (MRA), which may degrade the diagnostic quality to assess effective intracranial aneurysm treatment. Please only use digital subtraction angiography (DSA) or computed tomography angiography (CTA) to assess intracranial aneurysm occlusion for patient follow-up. Steam shaping 0.021” and greater microcatheters may result in improper WEB embolization device delivery and deployment, depending on the degree of shaping and catheter deflection during WEB embolization device delivery. If repositioning is required, take special care to retract or to advance the WEB embolization device under fluoroscopy, including new road map to confirm catheter position. If the WEB embolization device must be retrieved from the vasculature after detachment, retrieval devices (e.g. alligator and snare) should be used per their manufacturer’s instructions. The pictures in (a) through (c) below illustrate WEB embolization device deployment. Initially, the distal implant marker band exits the microcatheter (a). As the implant is advanced, it begins to expand in diameter (b). When the distance between the catheter marker band and implant tip is about 1/3 of the total implant marker distance, the implant diameter is generally about 1/2 of its fully deployed diameter (b). When the implant distal marker band to catheter distal marker band distance is about 2/3 of the total implant marker-marker distance, the implant has reached about 4/5 of its fully deployed diameter and the distal marker band begins moving into the distal recess (c). VIA 17 Microcatheters have a proximal marker band not shown in the drawings or photos below. This proximal catheter marker band is not used for WEB delivery. The WEB embolization device foreshortens during delivery (~60%) (e.g. see Figure 2a, a 11mm x 9mm device will measure ~20mm in length when contained within a 0.032”-0.038” delivery microcatheter). When properly deployed, two radio-opaque markers should be separated and fluoroscopically visible (e.g. see Figure 2b, depending on working projection and placement in the aneurysm, the distance between the proximal to distal marker should approximate the labeled WEB embolization device length). WEB embolization device visibility may vary with diameter; larger sizes may be more visible than smaller sizes. Examples are shown in Figure 2c. If the radio-opaque markers are clustered (i.e. a shorter distance between markers than expected), retract WEB embolization device into the microcatheter and evaluate the microcatheter/aneurysm position with multiple fluoroscopic angles. Batteries are pre-loaded into the WEB detachment control device. Do not attempt to remove or replace the batteries. Potential complications: Include but are not limited to the following: vessel puncture site hematoma, aneurysm perforation or rupture, hemorrhage, edema, thromboembolic, transient ischemic attack, ischemic stroke, neurologic deficits, parent artery occlusion, ischemia, vessel dissection or perforation, vascular thrombosis, vasospasm, device migration or misplacement, premature detachment, headache, post-embolization syndrome, infection and death. The WEB embolization device requires the use of fluoroscopy. Potential complications related to angiographic and fluoroscopic radiation doses include, but are not limited to, alopecia, burns ranging in severity from skin reddening to ulcers, cataracts, and delayed neoplasia. The probability of occurrence of complications may increase as procedure time and number of procedures increase. Other procedural complications including but not limited to anesthetic and contrast media risks, hypotension, hypertension and access site complications. For complete indications, contraindications, potential complications, warnings, precautions, and instructions, see instructions for use (IFU provided in the device)
For Professional Use Only RX Only: Federal (FDA) law restricts this device to sale by or on the order of a physician.
WEB OUS Indications for use: OUS: The WEB Aneurysm Embolization System is intended for the endovascular embolization of ruptured and unruptured intracranial aneurysms and other neurovascular abnormalities such as arteriovenous fistulae (AVF). The WEB Aneurysm Embolization System is also intended for vascular occlusion of blood vessels within the neurovascular system to permanently obstruct blood flow to an aneurysm or other vascular malformation. Indications, contraindications, warnings and instructions for use can be found in the product labeling supplied with each device
BRAZIL AND CANADA: The WEB Aneurysm Embolization System is intended for the endovascular embolization of ruptured and unruptured intracranial aneurysms. It is recommended for saccular intracranial aneurysms located at the basilar artery apex, posterior communicating artery, middle cerebral artery bifurcation, termination of the internal carotid artery, anterior communicating artery in a body/neck ratio 1 and intracranial wide-neck aneurysm with a neck size 4 mm or body/ neck ratio < 2. The device should only be used by physicians who have undergone training in all aspects of the WEB Aneurysm Embolization System procedures as prescribed by manufacturer.
The VIA Microcatheter is intended for the introduction of interventional devices (such as the WEB device/stents/flow diverters) and infusion of diagnostic agents (such as contrast media) into the neuro, peripheral, and coronary vasculature.
Indications, contraindications, warnings and instructions for use can be found in the product labeling supplied with each device. For Healthcare Professionals Intended Use Only.
