INTRODUCTION
The Woven EndoBridge (WEB; Terumo Neuro) device has emerged as an effective intrasaccular flow disruption strategy for the treatment of wide-neck bifurcation aneurysms [1-3]. In ruptured aneurysms, the WEB device offers the theoretical advantage of immediate flow disruption without the need for adjunctive stenting or routine dual antiplatelet therapy, making it an attractive alternative to stent-assisted coiling in selected acute subarachnoid hemorrhage (SAH) cases [4-6]. Prospective and multicenter studies in the acute setting have reported favorable occlusion rates and a low incidence of early rebleeding after WEB deployment [2,4,5].
Although intraprocedural rupture is a recognized complication of endovascular aneurysm treatment, most WEB-related hemorrhagic events described in the literature have been associated with device manipulation during the initial deployment phase—when the device is still partially expanded—or with microcatheter-related injury [1,7]. In addition, delayed rebleeding after apparently uneventful WEB treatment has also been reported [8]. In ruptured aneurysms, several mechanisms may therefore need to be considered, including device-related mechanical stress during deployment or repositioning, catheter-related injury, incomplete early protection of a fragile rupture point, or spontaneous rebleeding unrelated to a specific maneuver [3,4,8]. Once fully deployed and stably positioned, the WEB device is generally considered mechanically stable [1].
However, in clinical practice, repositioning maneuvers such as partial resheathing and system push may be required to optimize device configuration or preserve an adjacent branch [1,7]. Appropriate sizing relative to aneurysm width is a fundamental principle of WEB therapy to ensure stable apposition of the device to the aneurysm wall [9]. These maneuvers can alter the mechanical interaction between the fully expanded device and the aneurysm wall, particularly at a fragile rupture point. The risk of catastrophic rebleeding during or after repositioning of a fully deployed WEB device has not been well characterized.
We report a case of a ruptured fetal-type posterior communicating artery (PCoA) aneurysm in which a small, unrecognized intraprocedural extravasation occurred during WEB repositioning, followed by sudden catastrophic rebleeding after device detachment.
CASE REPORT
A patient in their early 90s presented with sudden-onset severe headache and decreased consciousness. Noncontrast computed tomography (CT) demonstrated diffuse SAH (Fig. 1A). Based on the clinical findings in the presence of SAH, she was classified as WFNS (World Federation of Neurosurgical Societies) grade V. Spontaneous respiration was present, and anisocoria was not observed. Three-dimensional CT angiography (3D-CTA) revealed a right PCoA aneurysm measuring greater than 10 mm in maximal diameter with a fetal-type PCoA configuration. Although the patient was extremely elderly and presented with poor-grade SAH, the family strongly wished for minimally invasive treatment aimed at preventing rebleeding. Given the patient’s age and neurological severity, open surgical treatment was considered inappropriate, and emergency endovascular treatment was selected under general anesthesia. Among the available endovascular options, the WEB device was chosen as the first-line treatment because it allowed intrasaccular treatment of this broad-neck aneurysm without adjunctive stenting or dual antiplatelet therapy, and was expected to provide rapid flow disruption with a shorter and simpler procedure than coil embolization. Preoperative 3D-CTA demonstrated marked atherosclerotic changes along the access route from the femoral puncture site to the aorta, in addition to a bovine arch configuration. Furthermore, the only reasonable access route to the left common carotid artery was considered to be via the right upper extremity. Therefore, the procedure was performed via a right distal transradial approach using a single guiding system. A diagnostic angiography demonstrated a large aneurysm with a distinct bleb considered to represent the rupture point (Fig. 1B–D).
Through the right distal radial artery, a 4-Fr sheath introducer was initially placed and then exchanged for a 7-Fr 95-cm RIST guiding system (Medtronic). Based on 3D-DSA (digital subtraction angiography) measurements (axial view, Fig. 1E; oblique view, Fig. 1F), the aneurysm showed a mean width of 10.22 mm, a minimum height of 9.94 mm, and a neck diameter of 9.94 mm. After determination of an adequate working angle, a WEB SL 11×9 mm (Terumo Neuro) was selected accordingly. A 5-Fr SofiaSelect EX (Terumo Neuro) was used for distal access catheter. A VIA 33 (Terumo Neuro) was navigated to the aneurysm using a Headway DUO microcatheter (Terumo Neuro) and a Synchro SOFT microwire (Stryker) through the above-mentioned guiding system without difficulty (Fig. 1G, Supplementary Video 1). Deployment was performed essentially by an unsheathing maneuver (Fig. 1H). After initial deployment, angiographic assessment demonstrated that the proximal portion of the device completely covered the origin of the fetal-type PCoA (Fig. 1I). Therefore, partial resheathing was performed, and a system push maneuver was applied to reposition the device while preserving the origin of the fetal-type PCoA. As a result, the proximal portion of the WEB assumed a concave configuration and rotated slightly clockwise (Fig. 1J). This repositioning changed the relationship between the bleb and the junction between the lateral surface and the distal marker surface of the device. During repositioning, no contrast extravasation was recognized at the time of the procedure. However, retrospective assessment of the procedural recording suggested minimal contrast leakage just above the bleb (Fig. 1J, Supplementary Video 1). At the working angle, the parent vessel was preserved, and visualization of the intracranial arteries was satisfactory (Fig. 1K), and therefore the configuration was judged acceptable. The WEB device was then detached, and the VIA 33 was withdrawn. Subsequently, during the final diagnostic DSA runs undertaken as the last step before completion of the procedure, abrupt and massive contrast extravasation occurred in the later arterial phase, consistent with catastrophic rebleeding (Fig. 1L).
Immediate rescue measures were initiated. Heparinization was reversed using an intravenous bolus of 3,000 units of protamine sulfate, with systolic blood pressure maintained at approximately 100 mmHg. A SHOURYU 4×10 mm balloon catheter (Kaneka Medix) was positioned at the aneurysm neck for temporary internal carotid artery (ICA) occlusion (Fig. 1M) of approximately 5 minutes through the SofiaSelect EX left in the petrous ICA, with DSA performed after each deflation to assess hemostasis; this sequence was repeated 4 times, resulting in persistent extravasation despite these attempts. Therefore, the SofiaSelect EX was urgently removed, and the SHOURYU balloon was reintroduced through the RIST guiding system. While maintaining ICA occlusion with the balloon, a Headway DUO microcatheter with a CHIKAI 14 wire (Asahi Intecc) was advanced coaxially through the RIST system and carefully navigated outside the WEB, between the WEB and the aneurysm wall. After confirming that the catheter tip was located in close proximity to the rupture point, approximately 0.3 mL of 30% n-butyl cyanoacrylate (NBCA; Histoacryl Blue, B. Braun) was carefully administered under roadmap guidance. Injection was terminated when the NBCA cast was judged to occlude the rupture point and to minimally fill the space within the WEB (Fig. 1N), resulting in hemostasis (Fig. 1O).
The final angiographic runs demonstrated poor filling of the intracranial arteries, suggesting markedly elevated intracranial pressure. Postprocedural cone-beam CT revealed a massive intracerebral hematoma deep to the left Sylvian fissure (Fig. 1P). Emergency decompressive craniotomy with hematoma evacuation was proposed; however, given the extremely poor neurological prognosis, surgical intervention was declined. The patient was managed with supportive care and died 3 days later.
DISCUSSION
Intraprocedural rupture during WEB deployment has most commonly been reported in the early deployment phase, particularly when the device is still in a lance-like configuration and a system jump occurs [1,7]. Although multicenter experience has shown generally favorable perioperative results of WEB treatment for ruptured aneurysms, rupture after full or near-full expansion of the device appears to be extremely rare [1,10]. In addition, when rupture occurs during deployment, continued expansion and deployment of the WEB often allows immediate control of bleeding [1]. Partial resheathing and repositioning are integral components of WEB treatment, particularly when optimization of the neck line or preservation of an adjacent branch is required [1,7]. A certain degree of system push or delivery push is generally regarded as safe and is routinely performed in daily practice [1,7]. To our knowledge, no report has clearly attributed aneurysm rupture to a reposition maneuver itself. Most reported WEB-related hemorrhagic events have been associated with initial deployment, microcatheter- or microwire-related injury, detachment-related events, or delayed rebleeding after an apparently uneventful procedure. In the present case, the temporal association between partial resheathing/push-assisted repositioning and the subsequently recognized minimal contrast leakage is therefore suggestive, but not definitive proof of causation.
In the present case, preservation of a fetal-type PCoA necessitated partial resheathing and a push-assisted repositioning maneuver. Retrospective assessment of the procedural video demonstrated that, during repositioning, the WEB rotated in a clockwise direction. Although the bleb had been covered by the lateral surface of the device after initial deployment, repositioning altered the geometric relationship between the bleb and the junction between the lateral surface and the distal marker surface of the device. In the setting of acute rupture, a large aneurysm, extreme advanced age, and a fragile bleb, contact at this transition zone may have played a role in the subsequent catastrophic rebleeding.
The precise cause of rebleeding in this case remains uncertain. Potential mechanisms of hemorrhagic deterioration during WEB treatment may include device-related mechanical stress during deployment or repositioning, microcatheter-related injury, incomplete early protection of a fragile rupture point, or spontaneous rebleeding in a highly unstable acutely ruptured aneurysm. In the present case, intra-aneurysmal microcatheter angiography was not performed before rebleeding, and balloon inflation was used only after catastrophic extravasation had already become evident as a rescue maneuver for hemostasis. Therefore, these factors were considered unlikely to represent the initiating event. A previously reported case described delayed rebleeding several hours after WEB treatment of a ruptured aneurysm [8]. In that case, postprocedural CT showed no evidence of immediate rebleeding, and hemorrhagic deterioration became evident 4 hours later, suggesting a delayed post-treatment event rather than a procedurally recognized rupture. By contrast, in the present case, retrospective assessment of the procedural recording suggested minimal contrast leakage during repositioning, followed by catastrophic rebleeding during the final angiographic runs after detachment. These differences in timing may indicate different underlying mechanisms, although definitive proof is not possible.
In retrospect, selection of a slightly smaller device (for example, 11×8 mm) with avoidance of push-assisted repositioning might have been considered as an alternative strategy to preserve the branch while minimizing focal stress [9]. Furthermore, although not feasible in the present case because of access limitations, the use of balloon guiding or pre-positioning of a balloon catheter near the aneurysm neck may be considered in selected high-risk situations to facilitate rapid hemorrhage control. More importantly, acute-phase WEB deployment demands meticulous intraluminal manipulation, and the extent of device manipulation in the present case may have exceeded what would be considered prudent under these circumstances.
This report describes a single case, and the proposed mechanism remains speculative. The interpretation is based on retrospective assessment of procedural imaging and video without biomechanical validation. The relative contributions of device sizing, repositioning maneuvers, and patient-specific factors cannot be definitively determined.
Although the WEB device is widely regarded as safe and effective for ruptured aneurysms, this case demonstrates that catastrophic rebleeding may occur even after near-complete deployment under specific high-risk conditions. In large ruptured aneurysms with fragile blebs, particularly when push-assisted repositioning is required, careful attention to device–wall interaction and procedural strategy may help reduce the risk of this rare but devastating complication.
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