Original ArticleA computational fluid dynamics (CFD) study of WEB-treated aneurysms: Can CFD predict WEB “compression” during follow-up?
Introduction
The WEB intra-saccular flow disrupter (Sequent Medical, Alisa Viejo, California) is a novel endovascular approach to treat broad base intracranial aneurysms. A recent report has demonstrated a worsening of aneurysm occlusion between postoperative baseline and follow-up due to “compression” of the device [1]. Cognard et al. described a worsening between the post-procedural and follow-up angiographies in 10 of 14 cases (71.5%) and a “compression” of the WEB in 9 of 14 cases (64.3%) (Fig. 1). In a larger series, other authors [2] demonstrated that this phenomenon was not infrequent with a WEB shape modification in 32% of cases.
Yet the underlying mechanisms are still unknown. The WEB device is expected to better resist arterial flow due to its volumetric shape and radial force, therefore some suspect that WEB shape is modified by clot retraction [3].
However, neither mechanism has yet been demonstrated. Here, we sought to determine whether the reported worsening of aneurysm occlusion is flow related using computational fluid dynamics (CFD) technology.
Section snippets
Data collection
From our prospectively maintained database, we retrospectively extracted all consecutive patients treated with a WEB device in our institution between July 2012 and June 2015 for either a middle cerebral artery (MCA) or basilar tip aneurysm, that were unruptured, untreated and without partial thrombosis. Informed consent was obtained in each case. The study was conducted under the rules of local ethics committee. Patients with obvious bad technical results were excluded, i.e. absence of neck
Demographic data
Between July 2012 and June 2015, a total of 22 unruptured MCA and basilar tip aneurysms, that had never received treatment, were operated on with a WEB device in our institution (Table 1). A total of 18 patients (15 women and 3 men; average age 64 years), with 19 WEB-treated aneurysms were included in this study. Three cases were excluded for different reasons:
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one patient had obvious post-detachment negative results (with flow around the device) and is planned to be retreated in a second
WEB “compression”
The WEB intra-saccular flow disrupter was first introduced to the market as an exciting device since it appeared to be a simple solution for managing previously difficult-to-treat wide-neck bifurcation aneurysms, in addition to a very good safety profile [8], [9], [10], [11], [12], [13], [14]. However, it has recently been described in an unexpected phenomenon: during early follow-up, a worsening of the occlusion rates, related to “compression” of the device, had been observed in up to 64% of
Conclusion
The mechanisms underlying in WEB shape change with time, as observed in some aneurysms, are most likely complex as well as multifactorial. This device compression does not correspond to worsening of aneurysm occlusion in all cases. However, it is apparent from our pilot study that a high arterial inflow effect is, at least, partially involved. Further theoretical and animal research studies are needed to increase our understanding of this phenomenon.
Authors contribution
JC: project development, data collection, manuscript writing, statistical analysis, approval of final version.
TY: project development, approval of final version.
CM, VDR, MI, LI, JM, LS: data analysis, approval of final version.
Disclosure of interest
LS and JM are consultants for Sequent Medical, TY is an employee of EBM corp.
Jildaz Caroff, Cristian Mihalea, Valerio Da Ros, Marta Iacobucci, Léon Ikka declare that they have no competing interest.
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