Hemodynamics of 8 different configurations of stenting for bifurcation aneurysms

Low-Profile Visualized Intraluminal Support Device for Y-Stent-Assisted Coiling of Wide-Neck Intracranial Aneurysms: A Single-Center Experience

BACKGROUND

The Low-Profile Visualized Intraluminal Support (LVIS) device has been frequently used as an intracranial stent for treating intracranial aneurysms. However, the feasibility and efficacy of LVIS devices in Y-stent-assisted coiling (Y-SAC) have remained contentious. This study aimed to evaluate long-term angiographic and clinical outcomes of Y-SAC using LVIS devices.

METHODS

We retrospectively reviewed the clinical presentation and angiography data of patients treated with Y-SAC using LVIS stents. The vascular angle geometry between the parent and the 2 branch vessels, before and after stent deployment and after coiling, were analyzed. Based on the Raymond-Roy Occlusion Classification (RROC), aneurysm occlusion status was classified. Clinical outcomes were assessed using the modified Rankin Scale.

RESULTS

Forty patients with 40 aneurysms were included in this study. Immediate postprocedural angiograms showed complete/near-complete occlusion (RROC 1 and 2) in 31 aneurysms (77.5%). The long-term follow-up angiographic studies were available in 32 patients and showed RROC class 1 and 2 in 93.8% of patients. Y-SAC with LVIS devices significantly decreased the angle between the bifurcation branches from 171.90° ± 48.0° (standard deviation) to 130.21° ± 46.3° (standard deviation) (P < 0.0001). Periprocedural complications occurred in 5 patients (12.5%) including 4 in-stent thromboses (10.5%). Thirty-six patients (90.0%) had favorable clinical outcomes at the final follow-up. Univariate analysis showed that World Federation of Neurological Societies grade 3-5, thickness of subarachnoid hemorrhage on head computed tomography, intraprocedural complications, and in-stent thrombosis were predictors of poor outcome.

CONCLUSIONS

Y-SAC using the LVIS device for intracranial bifurcation aneurysms is a feasible and relatively safe procedure with favorable long-term angiographic and clinical outcomes.

Efficacy and safety of low profile stents in Y-stent assisted coil embolization of wide-necked bifurcation aneurysms: a systematic review and meta-analysis

Low-profile stents may provide significant advantages in Y-stent-assisted coiling due to their miniaturized design and capability to be delivered through a 0.0165-inch microcatheter. We aim to investigate the safety and efficacy of using these newer versions of stents in Y-stent-assisted coiling for the treatment of wide-necked bifurcation aneurysms. We conducted a systematic review of the PubMed, Embase, Cochrane Library, and Web of Science databases up to September 2023, following the PRISMA guidelines. Eligible studies included  ≥ 5 patients with intracranial wide-necked bifurcation aneurysms treated with Y-stent-assisted coiling using low-profile stents, providing angiographic and clinical outcomes. Two authors independently handled the search and selection. Primary outcomes were immediate and follow-up aneurysm occlusion, procedure-related complications, aneurysm recanalization, and retreatment. Secondary outcomes included technical success, procedure-related morbidity, procedure-related mortality, procedure-related stroke, and in-stent stenosis at follow-up. We analyzed the data using random-effects meta-analysis. In total, 19 studies including 507 patients with 509 aneurysms were included. 95% of the treated aneurysms were managed using the crossing Y-configuration. Technical success rate was 99%. Immediate adequate aneurysm occlusion was 90%. Follow-up angiographies were available for 443 aneurysms. The mean angiographic follow-up duration was 15.6 ± 1.9 months. The rates for follow-up adequate aneurysm occlusion and complete occlusion were 98% and 89%, respectively. After a mean clinical follow-up of 15 ± 2.4 months, a good clinical outcome was observed in 98% of patients. Overall, procedure-related morbidity and mortality rates were 1.3%, and 0.4%, respectively. Low-profile stents in Y-stent-assisted coiling outperform previous stent versions in terms of safety, efficacy, and technical success rates.

Expanded range of indications for Neuroform Atlas stent in the treatment of very small, wide-necked cerebral aneurysms

The purpose of this study was to investigate the range of indications for using the Neuroform Atlas stent. Between 2016 and 2020, we treated 20 females and 5 males for aneurysms with a diameter of less than 3 mm and an aspect ratio less than 1.5. The diameter of the parent arteries varied from 1.1 mm to 4.5 mm. There were 13 ruptured and 12 unruptured aneurysms. Double stent-assisted coiling was performed in 14 cases, and single stent-assisted coiling was performed in 11 cases. After deployment, the morphology of the Neuroform Atlas stents was analyzed in tapered or Y-shaped silicone tubes that simulated parent arteries. Radiological results were assessed 7 months and 2 years after the intervention using the Raymond-Roy scale. Clinical outcome was assessed 1 year after the intervention using the modified Rankin score. There were three fatal outcomes. One aneurysm was recoiled. The rate of class I aneurysm occlusion was registered in 21 patients at the last follow-up. At the end of the clinical follow-up period, a favorable outcome (modified Rankin scale 0 -1) was registered in nine patients with ruptured aneurysms. An analysis of the morphology of the stents deployed in the silicone tubes provided an explanation for the stability of the coil mass in the treated aneurysms. Our results suggest that the range of indications for use of the Neuroform Atlas stent can be expanded beyond the present range with regard to the diameter of the parent vessels and size of the aneurysms.

Contour-Assisted coiling with jailed microcatheter May result in better occlusion (CoCoJaMBO) in wide-necked intracranial aneurysms: Proof of principle and immediate angiographic results

PURPOSE

Wide-necked bifurcation aneurysms, partially thrombosed, and recurrences of large and giant aneurysms are challenging to treat. We report our preliminary experience with a Contour-assisted coiling technique and discuss the periprocedural safety, feasibility, and effectiveness of the approach.

METHODS

We retrospectively reviewed consecutive patients who received endovascular treatment for intracranial aneurysms with an intra-aneurysmal flow disruptor (Contour) at two neurovascular centres between October 2018 and December 2020 and identified patients treated with a combination of Contour and platinum coils. Clinical and procedural data were recorded.

RESULTS

For this analysis, 8 patients (5 female) aged 60.1  ±  9.2 years on average were identified. Three of 8 aneurysms were associated with previous acute subarachnoid hemorrhage (SAH). The mean average dome height was 12.8  ±  7.6 mm, mean maximum dome width 10.3  ±  5.4 mm, and neck width 5.5  ±  2.5 mm. The mean dome-to-neck ratio was 1.9  ±  1.0. Immediate complete occlusion of the aneurysm was seen in 5 of 8 cases. In one SAH patient, a parent vessel was temporarily occluded but could be reopened rapidly. One device detached prematurely without any sequelae. No other procedural adverse events were recorded.

CONCLUSION

From this initial experience, Contour with adjunctive coiling is a safe and technically feasible method for endovascular treatment of large, wide-necked, partially thrombosed, recurrent, or ruptured bifurcation aneurysms. Further studies with larger numbers of patients and longer follow-up are needed to confirm our results.

Modified balloon-assisted coiling instead of acute stenting in the treatment of ruptured wide necked intracranial aneurysms

BACKGROUND

The aim of this study was to investigate the safety and efficiency of the modified balloon assisted coiling (mBAC) technique in endovascular treatment (EVT) of ruptured wide-necked aneurysms (WNAs) to avoid stent placement in the acute phase of subarachnoid hemorrhage (SAH).

METHODS

The local neurointerventional radiology database was retrospectively reviewed to identify patients who underwent EVT due to ruptured WNAs by the authors. According to the EVT technique performed, the study sample was divided into 3 groups: conventional BAC, stent assisted coiling (SAC), and mBAC. The patient demographics, aneurysm features, technical and clinical complications, aneurysm occlusion grades, morbidity, and mortality rates were comparatively analyzed.

RESULTS

This study involved a total of 113 patients who had ruptured WNAs. The mBAC technique was performed on 26 aneurysms (23 saccular and 3 fusiform) in 26 patients to avoid acute phase stenting. The mean continuous balloon inflation time was 7.1 ± 2.12 min. The initial and follow-up angiographic and clinical outcomes were better in the mBAC group than in the SAC group (p < 0.05).

CONCLUSIONS

The mBAC technique offers a prolonged, continuous balloon inflation time during the whole coiling process in the treatment of ruptured WNAs. The mBAC technique has the potential to obviate the need for SAC in patients who are candidates for stenting during the acute phase of SAH, and it might be considered a safe and effective endovascular approach with low complication rates and good angiographic and clinical outcomes.

Long-term outcomes of Y-stent-assisted coil embolization using Low-profile Visualized Intraluminal Support Junior (LVIS Jr) for intracranial bifurcation aneurysms

OBJECTIVE

Y-stent-assisted coil embolization is indicated for the treatment of complex intracranial bifurcation aneurysms. However, the long-term outcomes associated with this technique remain unclear. The purpose of this study was to evaluate the long-term outcomes of Y-stent-assisted coil embolization using the Low-profile Visualized Intraluminal Support Junior (LVIS Jr) device.

METHODS

We retrospectively reviewed our databases to identify patients treated with Y-stent-assisted coiling using LVIS Jr. Digital subtraction angiography, silent magnetic resonance angiography (MRA), and time-of-flight MRA were performed at 1 year after the procedure. Patients also received an annual follow-up using MRA. Aneurysm occlusion status was classified into complete occlusion (CO), neck remnant (NR), and body filling (BF). Clinical outcomes were assessed using the modified Rankin Scale.

RESULTS

Twenty-one patients (22 aneurysms) were included in this study. All procedures were performed successfully. Immediate postprocedural angiograms showed CO in 13 aneurysms (59.1%), NR in two aneurysms (9.1%), and BF in seven aneurysms (31.8%). One-year follow-up angiograms revealed CO in 86.4% of patients. Only one patient had a major recurrence and required retreatment. The mean follow-up duration was 43.5 months. The last angiographic studies demonstrated CO in 18 aneurysms (81.8%), NR in three aneurysms (13.6%), and BF in one aneurysm (4.5%). Periprocedural and delayed complications occurred in two patients and one patient, respectively. There was no permanent morbidity or death. The modified Rankin Scale scores at last clinical follow-up were equal to those before the procedures in all patients.

CONCLUSION

Y-stent-assisted coil embolization using LVIS Jr for intracranial bifurcation aneurysms has favorable long-term angiographic and clinical outcomes.

Endovascular treatment for large (> 10 mm) basilar tip aneurysms: a retrospective case series

PURPOSE

To report the long-term clinical and angiographic outcomes of the endovascular treatment of large/giant basilar tip aneurysms (BTAs) in our institutions.

METHODS

We retrospectively reviewed cases of BTA larger than 10 mm that received endovascular treatment between January 2009 and December 2019. Data on the demographic and clinical characteristics and radiologic severity were obtained from the patients' medical records. The collected clinical follow-up data included neurological evaluation. Magnetic resonance angiography (MRA) was performed 6 to 12 months after the procedure, followed by once every 1 to 2 years as needed.

RESULTS

A total of 12 patients with BTA were included in this study. The median age was 60.08 years (27-80 years), and the mean clinical follow-up was 66.78 months (19.00-142.87 months). Almost half of the patients presented with unruptured BTAs (58.33%, n = 7). The median maximum aneurysm diameter was 13.00 mm (10.46-20.90 mm) and the mean neck size was 8.34 mm (4.82-13.04 mm). A Modified Raymond Roy Classification (MRRC1) of 1 or 2 was observed in 66.67% of the patients (n = 8) immediately after the first procedure. Procedural morbidity and mortality were 33.33% and 8.33%, respectively. Major recanalization occurred in two patients, one of whom underwent additional coiling with the other being merely observed due to older age.

CONCLUSION

It is very difficult to cure a large BTA completely at once and recanalization occurred often after endovascular treatment. Conducting long-term follow-up studies at short intervals is warranted, as well as improving existing treatment methods and developing new approaches.

Application of the Neuroform Atlas Stent in Intracranial Aneurysms: Current Status

The Neuroform Atlas stent (NAS) is the successor of the Neuroform EZ stent. The NAS is compatible with a low-profile 0.0165-inch microcatheter and is soft enough to pass through small and highly tortuous vessels. The NAS can be used in treating intracranial aneurysms at almost all locations, and its use is becoming increasingly common. However, there has not yet been a complete review of NAS applications. Therefore, we performed this review, which addresses several aspects of the NAS, mainly including its characteristics, clinical trials of its application in treating aneurysms, deployment techniques for the device, the prognosis and complications of its application in treating aneurysms, and antiplatelet requirements associated with its use. Based on the evidence reviewed here, as well as our experience, we found that the NAS is a promising device for treating intracranial aneurysms, especially complex and distal aneurysms. This stent can also be used as a powerful tool to assist in rescuing coil migration, completing dual-stent reconstruction, and coiling aneurysms via a transcirculation approach. The device may require antiplatelet therapy at a lower dose and over a shorter period than other stents. The deployment of the NAS to assist in aneurysm coiling can yield good clinical outcomes and an acceptable rate of complications. Thus, the NAS is a promising device.

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.

Safety, Efficacy, and Durability of Stent Plus Balloon-Assisted Coiling for the Treatment of Wide-Necked Intracranial Bifurcation Aneurysms

BACKGROUND

Wide-necked bifurcation aneurysms remain a challenge for endovascular surgeons. Dual-stent-assisted coiling techniques have been defined to treat bifurcation aneurysms with a complex neck morphology. However, there are still concerns about the safety of dual-stenting procedures. Stent plus balloon-assisted coiling is a recently described endovascular technique that enables the coiling of wide-necked complex bifurcation aneurysms by implanting only a single stent.

OBJECTIVE

To investigate the feasibility, efficacy, safety, and durability of this technique for the treatment of wide-necked bifurcation aneurysms.

METHODS

A retrospective review was performed of patients with wide-necked intracranial bifurcation aneurysms treated with stent plus balloon-assisted coiling. The initial and follow-up clinical and angiographic outcomes were assessed. Preprocedural and follow-up clinical statuses were assessed using modified Rankin scale.

RESULTS

A total of 61 patients (mean age: 54.6 ± 10.4 yr) were included in the study. The immediate postprocedural digital subtraction angiography revealed complete aneurysm occlusion in 86.9% of the cases. A periprocedural complication developed in 11.5% of the cases. We observed a delayed ischemic complication in 4.9%. There was no mortality in this study. The permanent morbidity rate was 3.3%. The follow-up angiography was performed in 55 of 61 patients (90.1%) (the mean follow-up period was 25.5 ± 27.3 mo). The rate of complete aneurysm occlusion at the final angiographic follow-up was 89.1%. The retreatment rate was 1.8%.

CONCLUSION

The results of this study showed that stent plus balloon-assisted coiling is a feasible, effective, and relatively safe endovascular technique for the treatment of wide-necked bifurcation aneurysms located in the posterior and anterior circulation.

The Geometry of Y-Stent Configurations Used for Wide-Necked Aneurysm Treatment: Analyzing Double-Barrel Stents In Vitro Using Flat-Panel Computed Tomography

BACKGROUND

Stent-assisted coil embolization of wide-necked bifurcation aneurysms often employs a Y configuration stent. A similar stent configuration, termed kissing/double-barrel (KDB), is used often at the aortoiliac bifurcation. Studies of KDB stents in aortoiliac disease show that rates of thromboembolic complications vary with the cross-sectional geometry of the stent pair, a function of the radial crush resistive force of each stent. We assessed cross-sectional geometry of intracranial stent pairs in an in vitro model of the basilar artery using flat-panel computed tomography.

METHODS

In a silicone model of a wide-necked basilar tip aneurysm, 6 simulated KDB stent deployment trials were performed using combinations of 5 stents (Enterprise 1, Enterprise 2, Neuroform Atlas, LVIS, LVIS Jr.). Flat-panel computed tomography reconstructions were used to assess cross-sectional stent geometry. Relative conformability, defined by ovalization and D-ratio, radial crush resistive force (predicted vs. actual), and radial mismatch fraction were compared by stent type (braided vs. laser-cut).

RESULTS

Several distinct forms of cross-sectional stent geometry were observed. Braided stents had lower ovalization and D-ratio (P = 0.015) than laser-cut stents. The Neuroform Atlas/LVIS combination yielded the lowest radial mismatch fraction (19.7% vs. mean 44.3% ± 0.7%). Braided stents tended to have a deployed stent radius closer to the expected (nominal) diameter (i.e., higher relative crush resistive force) than laser-cut stents (measured vs. nominal diameter discrepancy +38.6% ± 21.1% vs. -10.7% ±16.1%, P = 0.14).

CONCLUSIONS

In constant anatomy, cross-sectional geometry of the KDB stent configuration will vary depending on the design and structure of the stents employed.

Y-stent assisted coiling of ruptured wide neck intracranial aneurysm in the acute phase

BACKGROUND

The objective of the present study is to analyze the outcomes of patients with subarachnoid hemorrhage (SAH) in the acute phase after treatment with Y-stent-assisted coiling (YSAC) embolization.

METHODS

This retrospective study assessed of 30 patients with acutely ruptured wide-neck aneurysms following YSAC treatment between April 2013 and October 2019. The demographic data, aneurysm occlusion grade, procedural and periprocedural complications, and clinical outcomes were assessed.

RESULTS

The procedure was completed in 30 cases (90.1%) and technical failure occurred in 3 cases (9.1%). Immediate control angiography revealed that total occlusion Raymond-Ray Class 1 (RR1) was achieved in 21 (70%), neck filling (RR2) in eight (26.6%) and sac filling (RR1) in one (3.3%) aneurysm. Upon angiographic follow-up, RR1 occlusion was observed in 15 (71.4%) patients, RR2 in three (14.3%) patients and RR3 in three (14.3%) patients. In-stent thrombus developed in five (16.6%) patients; procedural ischemic events were observed in four (13.3%) patients; and two (6.6%) patients were symptomatic. A periprocedural asymptomatic intracranial hemorrhage was detected in two patients. At discharge, 17 (56.6%) patients were in good clinical condition, six (20%) were in a severe disability condition, and seven (23.3%) patients had died. At the final follow-up visit (mean: 18.9 months), 16 (76,2%) of 21 patients were in a good clinical condition and five (23.8%) had severe disabilities.

CONCLUSIONS

Y-stent assisted coiling in might be a feasible and promising option for treatment in acute phase in selected wide-necked ruptured intracranial aneurysms.

Hemodynamic effects of intracranial aneurysms from stent-induced straightening of parent vessels by stent-assisted coiling embolization

BACKGROUND

Straightening of parent vessels happens for stent-assisted coiling embolization (SACE) treatment of intracranial aneurysms. This study aims to investigate aneurysmal hemodynamic modifications caused by stent-induced vessel straightening.

METHODS

Stent and coil deployments of a SACE-treated distal bifurcation aneurysm by finite element method were performed first with the preoperative (not straightened, NS) and postoperative (straightened, S) vessel models respectively. Computational fluid dynamics were then performed for eight models, including (I) NS only model, (II) NS+stent model, (III) NS+coils model, (IV) NS+stent+coils model, (V) S only model, (VI) S+stent model, (VII) S+coils model, and (VIII) S+stent+coils model. Finally, changes in aneurysmal flow velocity, isovelocity surface and wall shear stress (WSS) were analyzed qualitatively and quantitatively.

RESULTS

The flow was less in the S models than that in the corresponding NS models. Coils blocked most of the flow into the aneurysm sac in both NS models and S models and vessel straightening had more profound effect on the high aneurysmal flow volume reduction than coiling, while stenting generated adverse effect on flow reduction. Taking the NS only model as baseline (100%), the sac-averaged velocities of models II to VIII were 112%, 36%, 42%, 45%, 39%, 12%, 13%, and high flow volumes were 119%, 21%, 30%, 10%, 8%, 3%, 3%, while the sac-averaged WSSs were 106%, 37%, 44%, 41%, 35%, 17% and 24%, respectively.

CONCLUSIONS

Stent-induced vessel straightening combined coil embolization has the best performance in hemodynamic modifications and may reduce the recurrence rate, whereas stenting may generate adverse effect on hemodynamic alterations.

T-Stent or Half T-Stent-Assisted Embolization of Wide-Necked Aneurysms at the Internal Carotid-Posterior Communicating Artery Bifurcation

Objective

We report the usefulness and pitfalls of coil embolization using the T or half T-stent technique for aneurysms located at internal carotid artery-posterior communicating artery (ICA-P-com) bifurcation in which the neck is wide and the P-com must be kept patent due to it being the fetal-type with a hypoplastic P1 segment.

Case Presentations

Two cases were treated using the T-stent technique and two were treated using the half T-stent technique. The average age of the patients was 70.3 years and all were females. One aneurysm ruptured. The average size of aneurysms and neck was 12 mm and 8.5 mm, respectively, in the T-stent group, and 7.4 mm and 6.7 mm, respectively, in the half T-stent group. An S- or pigtail-shaped microcatheter (MC) was used to navigate into the P-com. Stent deployment was successful in all the cases. Retreatment was required in one case treated using the T-stent technique due to major recurrence.

Conclusion

T or half T-stent-assisted coil embolization can be an alternative endovascular treatment method for wide-necked ICA-P-com aneurysms in which the P-com must be kept patent due to it being the fetal-type with a hypoplastic P1 segment.

Long-term outcomes of wide-necked intracranial bifurcation aneurysms treated with T-stent-assisted coiling

OBJECTIVE

The endovascular treatment of complex bifurcation aneurysms possessing a neck that incorporates multiple side branches remains a surgical challenge. Double-stent-assisted coiling techniques, such as those with stents in an X and Y configuration, enable the endovascular treatment of wide-necked complex intracranial bifurcation aneurysms. However, the intraluminal struts at the intersection point in X- and Y-stents are not amenable to endothelialization, which may lead to thromboembolic complications. Stenting in the T configuration is a relatively new double-stent coiling technique. T-stenting differs from X- or Y-stenting in that there are no overlapping or intersecting stent segments. Promising short-term results of T-stent-assisted coiling were recently reported. However, the long-term results have not yet been demonstrated. This retrospective study investigated the long-term angiographic and clinical results in patients with wide-necked complex intracranial bifurcation aneurysms treated with T-stent-assisted coiling.

METHODS

A retrospective review was performed to identify patients with wide-necked complex intracranial bifurcation aneurysms treated with T-stent-assisted coiling at 4 institutions. The technical success and the initial and follow-up clinical and angiographic outcomes were assessed. Aneurysm filling status was assessed according to the Raymond classification. Periprocedural and delayed complications were reviewed. The neurological status of the patients was evaluated using the modified Rankin Scale (mRS).

RESULTS

One hundred two aneurysms in 102 patients (54 females), whose mean age was 57.9 ± 13.0 years, were included in the study. T-stenting was performed successfully in all patients. Immediate postprocedural angiography revealed complete occlusion in 83.3% of patients. Periprocedural complications developed in 13.7%, resulting in permanent morbidity in 1.9% and death in 1%. Eighty patients (78.4%) had at least one follow-up DSA examination performed at 6 months or later following the endovascular procedure. The mean duration of angiographic follow-up was 30.0 ± 16.3 months. The last follow-up examinations showed complete occlusion in 90.0% of patients. During the follow-up period, only 1 patient (1.3%) required retreatment. Delayed thromboembolic complications were observed in 4 patients (3.9%) without permanent morbidity. The mRS scores of all patients at the last clinical follow-up were between 0 and 2.

CONCLUSIONS

The short-term angiographic findings showed that T-stent-assisted coiling is a feasible and effective endovascular method to treat wide-necked complex bifurcation aneurysms. The long-term angiographic follow-up results suggest that T-stent-assisted coiling provides a durable treatment for wide-necked complex bifurcation aneurysms with favorable clinical outcomes, demonstrating the long-term safety of T-stent-assisted coiling.

Strut remodeling with hypercompliant balloon: A new approach to Y stent-assisted coil embolization in the treatment of complex wide-neck bifurcation aneurysms

BACKGROUND

The objective of this study was to present the long-term safety and effectiveness of strand remodelling with a hypercompliant balloon.

METHODS

Patients with complex wide-neck bifurcation aneurysms (WNBAs) who underwent strand remodelling with a hypercompliant balloon via Y-stent-assisted coil embolization (Y-SACE) between September 2016 and January 2020 were included in the study. The feasibility, safety, effectiveness, and complication rates of the strand remodelling technique were investigated.

RESULTS

A total of 12 patients (6 females, 6 males) were included in this study. Significant expansion was obtained in the intersection zone after remodelling. No regression was observed in the expansion rates during follow-up. There was no additional morbidity or mortality. No delayed thromboembolic complications occurred in our patients during long-term follow-up.

CONCLUSIONS

Performing strand remodelling to reduce thromboembolic complications triggered by structural faults caused by the Y-stent configuration is feasible, safe, and effective. This new approach can aid in the prevention of thromboembolic complications in Y-SACE.

Periprocedural Safety and Feasibility of the New LVIS EVO Device for Stent-Assisted Coiling of Intracranial Aneurysms: An Observational Multicenter Study

BACKGROUND AND PURPOSE

Stent-assisted treatment techniques can be an effective treatment option for intracranial aneurysms. The aim of this study was to evaluate the periprocedural feasibility and safety of the new LVIS EVO stent for the treatment of intracranial aneurysms.

MATERIALS AND METHODS

Patients with intracranial aneurysms treated with the LVIS EVO in 11 European neurovascular centers were retrospectively reviewed. Patient and aneurysm characteristics, procedural parameters, immediate grade of occlusion, and technical and clinical complications were assessed.

RESULTS

Fifty-seven patients with 59 aneurysms were treated with the LVIS EVO device; 57.6% of the aneurysms were incidental; 15.3% were acutely ruptured; 15.3% were recanalized or residual aneurysms; and 11.9% were treated for symptoms other than acute hemorrhage. The most frequent aneurysm locations were the middle cerebral artery (25.4%) and the anterior communicating artery (22.0%). The rate of immediate successful deployment was 93.2%. In 6.8% (n = 4) of cases, additional in-stent angioplasty was needed. The immediate complete occlusion rate was 54.2%, while there was a residual aneurysm in 35.6% and a residual neck in 10.2%. Periprocedural technical complications occurred in 7/59 treatments (11.9%; the most frequent technical complication [n = 3] was thrombus formation), which all resolved completely without clinical sequelae. Postprocedural neurologic complications occurred after 4/59 treatments (6.8%; 2 transient ischemic attacks, 1 minor stroke, 1 major stroke), of which only 1 persistent complication was directly related to the procedure (minor stroke in the vascular territory distal to the stent).

CONCLUSIONS

The LVIS EVO stent is a safe, feasible device for the treatment of intracranial aneurysms.

Y-Configuration Stenting for Coil Embolization of Complex Intracranial Aneurysms: Distinguishing Between Use of Crossing-Y and Kissing-Y

OBJECTIVE

Coil embolization with Y stenting is recognized as a suitable treatment for complex wide-necked aneurysms. Y stenting comprises crossing-Y stenting, in which a stent is passed through the interstices of another stent, and kissing-Y stenting, in which 2 stents are arranged in parallel. The purpose of this study was to elucidate how to distinguish between use of the 2 Y-stenting techniques.

METHODS

Clinical and angiographic data of patients who underwent coil embolization with Y stenting at our department from 2015 to 2019 were retrospectively analyzed. Basic characteristics, endovascular procedure, complications, and outcomes were compared between kissing-Y and crossing-Y stenting groups.

RESULTS

Thirty-eight intracranial aneurysms in 38 consecutive patients were included in this study. Nineteen patients (50%) were treated with coil embolization with kissing-Y stenting and 19 (50%) with crossing-Y. Endovascular procedures were successfully performed in all but 1 patient, in the kissing-Y group, who had stent migration. One hemorrhage (2.6%) recurred 12 months after coiling with kissing-Y stenting. Angiographic follow-up (mean, 15.8 months) was available in 35 patients. Adequate occlusion was shown in 14 patients (77.8%) and 13 patients (76.5%) in the kissing-Y and crossing-Y groups, respectively. Larger, wider-necked, and more proximal aneurysms were treated with kissing-Y stenting than with crossing-Y stenting, although there were no significant differences between the groups in complication rates or clinical outcomes.

CONCLUSIONS

Kissing-Y and crossing-Y stenting of intracranial aneurysms were both feasible and yielded reasonable angiographic and clinical results. The choice between the kissing-Y or crossing-Y-stenting technique should be decided according to the angioarchitecture of targeted aneurysms.

Evaluation of the Accero Stent for Stent-Assisted Coiling of Unruptured Wide-Necked Intracranial Aneurysm Treatment with Short-Term Follow-Up

BACKGROUND

Stent-assisted coiling is an effective method of treating intracranial aneurysms. The aim of the study was to assess the safety and efficacy of the new Accero stent for the treatment of intracranial aneurysms.

MATERIALS AND METHODS

It was a retrospective, single-center study. Eighteen unruptured intracranial aneurysms were treated using the stent-assisted coiling method with the Accero stent. Patient demographics, aneurysm characteristics, procedural parameters, grade of occlusion, complications, and clinical results were analyzed. Follow-up magnetic resonance (MR) was performed 6 months after intervention.

RESULTS

Seventeen patients with 18 incidental unruptured aneurysms were electively treated with coiling and the Accero stent. The aneurysms were located on internal carotid artery (ICA), middle cerebral artery (MCA) and basilar artery (BA). All stents were deployed successfully. Immediate complete occlusion rate Raymond-Roy occlusion classification (RROC) class I was achieved in 13 cases and class II in 4 cases. Complications occurred in 2/17 treatments and included guidewire stent perforation with subarachnoid hemorrhage (SAH) and stent deformation. Vascular spasm in the subarachnoid hemorrhage (SAH) patient subsided before discharge. Ninety days after intervention, the modified Rankin Scale (mRS) value was 0. RROC class I was observed in 88.23% of cases in follow-up.

CONCLUSION

The Accero stent provides excellent support for coil mass. It constitutes an efficacious device with good initial occlusion rate for treating wide-necked unruptured intracranial aneurysms.

Computational fluid dynamics as a risk assessment tool for aneurysm rupture

OBJECTIVE

The authors reviewed the clinical role of computational fluid dynamics (CFD) in assessing the risk of intracranial aneurysm rupture.

METHODS

A literature review was performed to identify reports on CFD assessment of aneurysms using PubMed. The usefulness of various hemodynamic parameters, such as wall shear stress (WSS) and the Oscillatory Shear Index (OSI), and their role in aneurysm rupture risk analysis, were analyzed.

RESULTS

The authors identified a total of 258 published articles evaluating rupture risk, growth, and endovascular device assessment. Of these 258 articles, 113 matching for CFD and hemodynamic parameters that contribute to the risk of rupture (such as WSS and OSI) were identified. However, due to a lack of standardized methodology, controversy remains on each parameter's role.

CONCLUSIONS

Although controversy continues to exist on which risk factors contribute to predict aneurysm rupture, CFD can provide additional parameters to assess this rupture risk. This technology can contribute to clinical decision-making or evaluation of efficacy for endovascular methods and devices.

'Railroad switch' technique for stent-assisted coil embolization of a wide-neck bifurcation intracranial aneurysm: technical note

Preservation of the posterior cerebral arteries during endovascular treatment of wide-neck basilar bifurcation aneurysms remains a technical challenge despite recent device innovations. We present a novel stent deployment technique, the 'railroad switch', to protect both posterior cerebral arteries during treatment of a recurrent basilar bifurcation aneurysm. Following asymmetric basilar-posterior cerebral artery stent deployment, favoring distal placement in a posterior cerebral artery, advancement of a jailed microcatheter will advance the proximal stent into the aneurysm, protecting both posterior cerebral arteries and the native basilar terminus. This novel maneuver offers interventionalists another application of commonly used intracranial stents for endovascular management of complex basilar bifurcation aneurysms.

Custom tissue engineered aneurysm models with varying neck size and height for early stage in vitro testing of flow diverters

Endovascular techniques for treating cerebral aneurysms are rapidly advancing and require testing to optimize device configurations. The purpose of this work was to customize tissue-engineered aneurysm "blood vessel mimics" (aBVMs) for early stage in vitro assessment of vascular cell responses to flow diverters and other devices. Aneurysm scaffolds with varying neck size and height were created through solid modeling, mold fabrication, mandrel creation, and electrospinning. Scaffold dimensions and fiber morphology were characterized. aBVMs were created by depositing human smooth muscle and endothelial cells within scaffolds, and cultivating within perfusion bioreactors. These vessels were left untreated or used for flow diverter implantation. Cellular responses to flow diverters were evaluated at 3 days. Custom scaffolds were created with aneurysm neck diameters of 2.3, 3.5, and 5.5 mm and with aneurysm heights of 2, 5, and 8 mm. A set of scaffolds with varying neck size was used for aBVM creation, and dual-sodding of endothelial and smooth muscle cells resulted in consistent and confluent cellular linings. Flow diverters were successfully implanted in a subset of aBVMs, and initial cell coverage over devices was seen in the parent vessel at 3 days. Direct visualization of the device over the neck region was feasible, supporting the future use of these models for evaluating and comparing flow diverter healing. Tissue-engineered aneurysm models can be created with custom neck sizes and heights, and used to evaluate cellular responses to flow diverters and other endovascular devices.

Utility of Low-Profile Visualized Intraluminal Support Junior Stent as a Rescue Therapy for Treating Ruptured Intracranial Aneurysms During Complicated Coil Embolization

BACKGROUND

Coil protrusion occasionally occurs during embolization and can lead to thromboembolic complications. We aimed to evaluate the efficacy of rescue stenting procedures with a low-profile stent system (LVIS Jr.) for treating ruptured intracranial aneurysms during complicated coil embolization.

METHODS

We performed a retrospective review to identify patients who had subarachnoid hemorrhage and were treated with LVIS Jr. stent rescue therapy. We enrolled 15 patients with intracranial aneurysms and evaluated the technical success and immediate postprocedural clinical and angiographic outcomes.

RESULTS

All 15 patients underwent successful rescue-stent treatment, and no thrombotic or hemorrhagic complications occurred. Immediate postprocedural angiography revealed complete aneurysm occlusion in 40% (6/15) of the patients, whereas 60% (9) of the patients had a residual neck. Among the 12 patients who underwent follow-up angiography, 10 (83.3%) patients had complete aneurysm occlusion, 1 (8.3%) had a residual neck, and 1 (8.3%) showed an increase in the filling status of the aneurysm. There were no thrombotic complications during the follow-up period.

CONCLUSIONS

Our findings indicate that LVIS Jr. stent rescue therapy is clinically useful for handling coil protrusion during the embolization of ruptured intracranial aneurysms.

Incomplete stent apposition of low-profile visualized intraluminal support stents in the treatment of cerebral aneurysms

OBJECTIVE

This study retrospectively analyzed the risk factors, management strategies, and complications of incomplete stent apposition (ISA) of low-profile visualized intraluminal support (LVIS) stents after initial deployment in the treatment of cerebral aneurysms.

METHODS

The clinical characteristics of ISA or wall apposition (WA) of LVIS stent after initial deployment were analyzed. The risk factors of ISA were identified using univariate logistic regression analysis and multivariate logistic regression analysis. The clinical characteristics of ISA following different management strategies were also shown.

RESULTS

The retrospective study enrolled 303 patients with 315 LVIS stent-assisted aneurysms. Fifty-nine patients with 59 stents showed ISA after initial deployment. At the end of the study, the presence of ISA was only observed in eight patients (2.5%). The stent-subtended arc angle (>90) and the aneurysm of the internal carotid artery (ICA) were associated with ISA. The stent-subtended arc angle (>90) and stent size (4.5*20 mm) were independent risk factors of ISA. The incidence of thromboembolic events in the ISA group was significantly higher than that in the WA group. After the treatment of ISA, there was no significant difference in good outcomes between patients with ISA and those with WA after initial deployment.

CONCLUSIONS

ISA is more likely to occur at tortuous vessels. The stent-subtended arc angle (>90) and LVIS size (4.5*20 mm) were independent risk factors of ISA. ISA led to significantly increased incidence of thromboembolic events. However, ISA after initial deployment did not affect the patient's prognosis.

Y-Stenting Versus PulseRider-Assisted Coiling in the Treatment of Wide-Neck Bifurcation Aneurysms: Role of Anatomical Features on Midterm Results

BACKGROUND

Y-stenting is an effective but challenging approach for wide-neck aneurysms. PulseRider (PR) (Pulsar/Cerenovus) is a new device designed to provide scaffolding during coiling but has never been compared with other techniques.

OBJECTIVE

To compare the immediate and 6-mo results of Y-stenting vs PR assisted coiling.

METHODS

A total of 105 consecutive patients were retrospectively divided into 2 groups (73 Y-stenting and 32 PR). All underwent angiographic 6-mo follow-up. We evaluated if some anatomical features could influence treatment results.

RESULTS

The groups were homogeneous. Immediate adequate occlusions as well as complication rates were similar in Y-stenting and PR group (94.5% vs 96.9% and 8.2% vs 6.2%, respectively). At 6 mo, adequate occlusion was 93.1% after Y-stenting and 84.3% after PR (P = .28), complete occlusion was significantly higher after Y-stenting: 90.3% vs 62.5% (P = .0017). Occlusion grade worsening occurred in 6.9% of Y-stenting and 18.7% of PR patients (P = .09).

Neck size was associated with occlusion grade in both groups. Maximal aneurysm size was associated with occlusion grade in the PR group (P = .023) but not in the Y-stenting group (P = .06). After PR, 6-mo occlusion rate was higher in small (&lt; 10 mm) than in large aneurysms (P = .0094); this was not observed after Y-stenting (P = .54).

Location did not significantly affect the mid-term occlusion rate in both the groups. After PR, occlusion was more stable in basilar than anterior or middle cerebral artery aneurysms.

CONCLUSION

Y-stenting and PR are both effective with similar immediate and mid-term results. However, treatment stability seems higher after Y-stenting. Aneurysm size seems to negatively affect PR results.

Initial and Long-Term Outcomes of Complex Bifurcation Aneurysms Treated by Y-Stent-Assisted Coiling with Low-Profile Braided Stents

BACKGROUND AND PURPOSE

Coiling complex intracranial bifurcation aneurysms often necessitates the implantation of double stents in various configurations, such as Y-stent placement. Low-profile braided stents have been introduced recently to facilitate the endovascular treatment of wide-neck aneurysms. We aimed to investigate the feasibility, safety, efficacy, and durability of Y-stent-assisted coiling with double low-profile braided stents for the treatment of complex bifurcation aneurysms.

MATERIALS AND METHODS

A retrospective review was performed to identify patients who were treated using Y-stent-assisted coiling with low-profile braided stents. Technical success was assessed, as were initial and follow-up clinical and angiographic outcomes. Periprocedural and delayed complications were reviewed. Preprocedural and follow-up clinical statuses were assessed using the modified Rankin Scale.

RESULTS

Forty patients with 40 intracranial aneurysms were included in the study. Y-stent placement was successfully performed in all cases. Immediate postprocedural digital subtraction angiography images revealed total aneurysm occlusion in 72.5% of cases. The mean angiographic follow-up time was 24.8 months. The last follow-up angiograms showed complete occlusion in 85% of patients. During follow-up, only 1 patient showed an increase in the filling status of the aneurysm and that patient did not require retreatment. There was no mortality in this study. The overall procedure-related complication rate, including asymptomatic complications, was 17.5%. A permanent morbidity developed in 1 patient (2.5%).

CONCLUSIONS

The long-term angiographic and clinical outcomes of this retrospective study demonstrate that Y-stent-assisted coiling using low-profile braided stents is an effective, relatively safe, and durable endovascular treatment for wide-neck and complex bifurcation aneurysms.

The Effect of Stents in Cerebral Aneurysms: A Review

The etiology of up to 95% of cerebral aneurysms may be accounted for by hemodynamically-induced factors that create vascular injury. The purpose of this review is to describe key physical properties that stents have and how they affect cerebral aneurysms. We performed a two-step screening process. First, a structured search was performed using the PubMed database. The following search terms and keywords were used: “Hemodynamics,” “wall shear stress (WSS),” “velocity,” “viscosity,” “cerebral aneurysm,” “intracranial aneurysm,” “stent,” “flow diverter,” “stent porosity,” “stent geometry,” “stent configuration,” and “stent design.” Reports were considered if they included original data, discussed hemodynamic changes after stent-based treatment of cerebral aneurysms, examined the hemodynamic effects of stent deployment, and/or described the geometric characteristics of both stents and the aneurysms they were used to treat. The search strategy yielded a total of 122 articles, 61 were excluded after screening the titles and abstracts. Additional articles were then identified by cross-checking reference lists. The final collection of 97 articles demonstrates that the geometric characteristics and configurations of deployed stents influenced hemodynamic parameters such as aneurysmal WSS, inflow, and pressure. The geometric characteristics of the aneurysm and its position also had significant influences on intra-aneurysmal hemodynamics after treatment. In conclusion, changes in specific aneurysmal hemodynamic parameters that result from stenting relate to a number of factors including the geometric properties and configurations of deployed stents, the geometric properties of the aneurysm, and the pretreatment hemodynamics.

LVIS Jr Device for Y-Stent-Assisted Coil Embolization of Wide-Neck Intracranial Aneurysms: A Multicenter Experience

Background and Purpose

Complex wide-neck intracranial aneurysms are challenging to treat. We report a multicenter experience using the LVIS Jr stent for "Y-stent"-assisted coiling embolization of wide-neck bifurcation aneurysms.

Methods

Seven centers provided retrospective data on patients who underwent Y-stenting. Technical complications, immediate posttreatment angiographic results, clinical outcomes, and imaging follow-up were assessed.

Results

Thirty patients/aneurysms were treated: 15 basilar tip, 8 middle cerebral artery, 4 anterior communicating artery, 1 pericallosal, and 2 posterior inferior cerebellar artery aneurysms. The mean aneurysm size was 11 mm and the mean dome-to-neck ratio was 1.3 mm. Twenty-four aneurysms were unruptured and treated electively, and 6 were acutely ruptured. Fifty-eight LVIS Jr stents were successfully deployed without any technical issue. One pro-cedural and transient in-stent thrombosis resolved with the intravenous infusion of a glycoprotein IIb/IIIa inhibitor. Five periprocedural complications (within 30 days) occurred: 2 periprocedural neurological complications (1 small temporal stroke that presented with transient aphasia and 1 posterior cerebral artery infarct) and 3 nonneurological periprocedural complications (2 retroperitoneal hematomas, and 1 patient developed a disseminated intravascular coagulopathy). One permanent complication (3.3%) directly related to Y-stenting was reported in the patient who suffered the posterior cerebral artery infarct. Immediate complete obliteration (Raymond-Roy Occlusion Classification [RROC] I-II) was achieved in 26 cases (89.6%). Twenty-four patients had clinical and imaging follow-up (mean 5.2 months). Complete angiographic occlusion (RROC I-II) was observed in 23 patients (96%). A good functional outcome with a modified Rankin Scale score ≤2 was achieved in 26 cases.

Conclusions

In this multicenter case series, Y-stent-assisted coiling of wide-neck aneurysms with the LVIS Jr device was feasible and relatively safe. Follow-up imaging demonstrated very low recanalization rates.

The Role of Hemodynamics in Intracranial Bifurcation Arteries after Aneurysm Treatment with Flow-Diverter Stents

BACKGROUND AND PURPOSE

Treatment of intracranial bifurcation aneurysms with flow-diverter stents can lead to caliber changes of the distal vessels in a subacute phase. This study aims to evaluate whether local anatomy and flow disruption induced by flow-diverter stents are associated with vessel caliber changes in intracranial bifurcations.

MATERIALS AND METHODS

Radiologic images and demographic data were acquired for 25 patients with bifurcation aneurysms treated with flow-diverter stents. Whisker plots and Mann-Whitney rank sum tests were used to evaluate if anatomic data and caliber changes could be linked. Symmetry/asymmetry were defined as diameter ratio 1 = symmetric and diameter ratio <1 = asymmetric. Computational fluid dynamics was performed on idealized and patient-specific anatomies to evaluate flow changes induced by flow-diverter stents in the jailed vessel.

RESULTS

Statistical analysis identified a marked correspondence between asymmetric bifurcation and caliber change. Symmetry ratios were lower for cases showing narrowing or subacute occlusion (medium daughter vessel diameter ratio = 0.59) compared with cases with posttreatment caliber conservation (medium daughter vessel diameter ratio = 0.95). Computational fluid dynamics analysis in idealized and patient-specific anatomies showed that wall shear stress in the jailed vessel was more affected when flow-diverter stents were deployed in asymmetric bifurcations (diameter ratio <0.65) and less affected when deployed in symmetric anatomies (diameter ratio ∼1.00).

CONCLUSIONS

Anatomic data analysis showed statistically significant correspondence between caliber changes and bifurcation asymmetry characterized by diameter ratio <0.7 (P < .001). Similarly, computational fluid dynamics results showed the highest impact on hemodynamics when flow-diverter stents are deployed in asymmetric bifurcations (diameter ratio <0.65) with noticeable changes on wall sheer stress fields. Further research and clinical validation are necessary to identify all elements involved in vessel caliber changes after flow-diverter stent procedures.

Midterm results of T-stent–assisted coiling of wide-necked and complex intracranial bifurcation aneurysms using low-profile stents

OBJECTIVE

Coiling of wide-necked and complex bifurcation aneurysms frequently requires implantation of double stents in various configurations. T-stent–assisted coiling involves the nonoverlapping implantation of 2 stents to protect the daughter vessels of bifurcation and is followed by coiling of the aneurysm. The authors studied the feasibility, efficacy, and safety of the T-stent–assisted coiling procedure as well as the midterm angiographic/clinical outcomes of patients with wide-necked bifurcation intracranial aneurysms treated using this technique.

METHODS

The authors retrospectively identified patients with wide-necked bifurcation intracranial aneurysms treated using double-stent–assisted coiling with a T-stent configuration.

RESULTS

Twenty-four patients with 24 aneurysms and a mean of age of 51.91 years were identified. The most common locations were the middle cerebral bifurcation (45.8%) and anterior communicating artery (35.7%). T stentings were performed using low-profile stents. The procedures were performed with a technical success rate of 95.8%, and an immediate total occlusion rate of 79.2% was achieved. We observed periprocedural complications in 16.7% of cases and a delayed thromboembolic event in 4.2%. The complications caused permanent morbidity in 1 patient (4.2%). No deaths occurred. The mean angiographic follow-up duration was 9.3 months. The total occlusion rate at the last follow-up was 81.2%. The recanalization rate was 4.5%. Modified Rankin Scale scores of all patients at the last follow-ups were between zero and 2.

CONCLUSIONS

T-stent–assisted coiling using low-profile stents is a feasible, effective, and relatively safe endovascular technique used to treat wide-necked and complex intracranial aneurysms. The midterm angiographic and clinical outcomes are outstanding.

Safety and effectiveness of the Low Profile Visualized Intraluminal Support (LVIS and LVIS Jr) devices in the endovascular treatment of intracranial aneurysms: results of the TRAIL multicenter observational study

Background and purpose

To evaluate the safety and effectiveness of the low-profile braided intracranial stents called the Low Profile Visualized Intraluminal Support (LVIS) devices for stent-assisted coil embolization of wide-necked intracranial aneurysms.

Materials and methods

This was a prospective, multicenter, observational study of unruptured and ruptured intracranial aneurysms treated with the LVIS devices. Imaging and clinical data were independently analyzed respectively by CoreLab and Clinical Event Committee. Primary endpoints were clinical safety, effectiveness, and angiographic stability of the results at 6 and 18 months.

Results

Ten centers participated in the study; 102 patients were included and 90 patients (42.2% men, 57.8% women) were eventually analyzed, among which 27 (30.0%) had multiple aneurysms. Twenty-three (25.6%) were ruptured aneurysms, four of which (4.4%) were treated in the acute phase. One aneurysm was treated per patient; 92 LVIS and LVIS Jr devices were placed overall. The total aneurysm occlusion rate was 91.0% on immediate post-procedure angiograms, which remained unchanged at 6-month follow-up and was 92.4% at 18-month follow-up. One patient (1.1%) underwent retreatment between 6 and 18 months of follow-up. A modified Rankin score of 0 was documented for most cases immediately after the procedure (86.7%) and at 6-month (86.8%) and 18-month (83.3%) follow-up. The overall permanent morbidity rate at 18 months was 5.6% and the overall rate of events with sequelae related to the stent was 2.2%. The 18-month procedure-related mortality rate was 3.3%. No patient was deemed to require retreatment at 18-month follow-up.

Conclusion

The LVIS/LVIS Jr endovascular devices are safe and effective in the treatment of ruptured and unruptured intracranial aneurysms, with acceptable complication rates, very high immediate total occlusion rates, and stable angiographic results.

Contribution of the straightening effect of the parent artery to decreased recanalization in stent-assisted coiling of large aneurysms

OBJECTIVE The durability of embolization of large aneurysms is enhanced by use of the neck-bridging stent. However, it remains unclear what factors contribute to decreased recanalization. The purpose of this study was to demonstrate the contribution of the straightening effect of the parent artery to the durability of stent-assisted coiling for large aneurysms. METHODS Of the 182 aneurysms treated by embolization since the introduction of the neurovascular stent, 82 consecutive unruptured aneurysms with a diameter greater than 7 mm were selected. There were 52 aneurysms treated with a stent (Group S) and 30 treated without a stent (Group NS). Occlusion status was evaluated 12 months after embolization with digital subtraction angiography. The vascular angle of the parent artery was measured before, immediately after, and 12 months after embolization. The rates of recanalization were compared between Group S and Group NS. In Group S, the rates of recanalization were further compared between those aneurysms with and without a significant angle change. RESULTS The rate of major recanalization was 9.6% in Group S and 26.7% in Group NS. The volume embolization ratio was 32.6% in Group S and 31.6% in Group NS, with no statistically significant difference. However, the angulation change before and after coiling was significantly higher in Group S (10.6°) than in Group NS (0.9°). The difference in the angulation was more evident 12 months after coiling (19.1° in Group S and 1.5° in Group NS). In Group S, recanalization was found in 14.3% of 35 stented aneurysms without a significant angular change when a significant angular change was defined as more than 20°. In contrast, all 17 aneurysms with ≥ 20° of angular change remained occluded. CONCLUSIONS Significant angular change of ≥ 20° most likely leads to decreased recanalization following stent-assisted embolization of large aneurysms.

Modification of hemodynamics in basilar artery aneurysm by the single and Y stent placement1

BACKGROUND

Stent placement can change the hemodynamics in basilar artery aneurysms. However, the effects of the stent placement can depend on the angle of vessel bifurcation.

OBJECTIVE

The hemodynamics in and near the aneurysm are investigated for two angles of vessel bifurcation and two stent models. Some statistical indexes are calculated to evaluate the effects of the stent placements on the possibility of aneurysm rupture.

METHODS

Computational fluid dynamics simulations and phantom model experiments are performed. The angle between the basilar and posterior cerebral arteries is set to 90 and 135 degrees. The single stent and Y stent models are tested in addition to the case without stent placement.

RESULTS

The velocity in the aneurysm in the Y stent case is smaller than that in the no stent and single stent cases when the angle is 135 degrees. High OSI and low AFI areas often appear at the same locations, and the area is larger in the single stent case than in the no stent and Y stent cases.

CONCLUSIONS

The Y stent placement promotes hemostasis and thrombosis in the basilar artery aneurysm, whereas the single stent placement can enhance the growth and rupture.

Virtual endovascular treatment of intracranial aneurysms: models and uncertainty

Virtual endovascular treatment models (VETMs) have been developed with the view to aid interventional neuroradiologists and neurosurgeons to pre-operatively analyze the comparative efficacy and safety of endovascular treatments for intracranial aneurysms. Based on the current state of VETMs in aneurysm rupture risk stratification and in patient-specific prediction of treatment outcomes, we argue there is a need to go beyond personalized biomechanical flow modeling assuming deterministic parameters and error-free measurements. The mechanobiological effects associated with blood clot formation are important factors in therapeutic decision making and models of post-treatment intra-aneurysmal biology and biochemistry should be linked to the purely hemodynamic models to improve the predictive power of current VETMs. The influence of model and parameter uncertainties associated to each component of a VETM is, where feasible, quantified via a random-effects meta-analysis of the literature. This allows estimating the pooled effect size of these uncertainties on aneurysmal wall shear stress. From such meta-analyses, two main sources of uncertainty emerge where research efforts have so far been limited: (1) vascular wall distensibility, and (2) intra/intersubject systemic flow variations. In the future, we suggest that current deterministic computational simulations need to be extended with strategies for uncertainty mitigation, uncertainty exploration, and sensitivity reduction techniques. WIREs Syst Biol Med 2017, 9:e1385. doi: 10.1002/wsbm.1385 For further resources related to this article, please visit the WIREs website.

Y-configuration Stent-assisted Coil Embolization for Wide-necked Intracranial Bifurcation Aneurysms

OBJECTIVE

The objective of this study was to determine the efficiency and safety of Y configuration stent-assisted coiling with double-closed stents for wide-necked intracranial aneurysms located at arterial bifurcations thorough analysis of a multicenter case series.

MATERIALS AND METHODS

A retrospective chart review was done on 10 patients who underwent endovascular treatment of wide-necked intracranial aneurysms with Y-configuration stent-assisted coil embolization in three centers from August 2011 to March 2014. The degree of aneurysmal occlusion was assessed using the Raymond scale. Clinical outcomes were assessed before operation, at discharge, and at the last follow-up visit using the Glasgow outcome scale.

RESULTS

The 10 patients included 6 females and 4 males with a mean age of 58.6 years. Indications for treatment included 6 unruptured intracranial aneurysms and 4 ruptured intracranial aneurysms. Five aneurysms were located at the basilar artery bifurcation, four aneurysms were located in an anterior communicating artery, and one aneurysm was in the pericallosal artery. The mean size of the 10 aneurysms was 9.7 mm. All aneurysms had a dome-to-neck ratio of < 1.5 (mean, 0.89). Immediate complications included one thromboembolic event out of the 10 cases. Immediate posttreatment angiograms showed complete occlusion in 1 aneurysm and residual necks in 9 aneurysms. Follow-up results showed 8 complete occlusions and 2 residual necks. No delayed complications were observed during the follow-up period (mean: 20 months).

CONCLUSION

Y configuration using double-closed cell stents is feasible and safe in selected patients. This method is an acceptable option for managing complex wide-necked bifurcations.

Double-barrel Y-configuration Stenting for Flow Diversion of a Giant Recurrent Basilar Apex Aneurysm with the Pipeline Flex Embolization Device

Giant basilar apex aneurysms are extremely challenging to successfully manage. The Pipeline Flex embolization device (PFED) is a new generation flow-diverting stent with a modified delivery system which allows resheathing of the stent after partial deployment. We describe a case of double-barrel Y-configuration stenting of a giant, recurrent basilar apex aneurysm using the PFED. A 73-year-old male was previously treated for an unruptured 11-mm basilar apex aneurysm with stent-assisted coiling using a Neuroform stent. The aneurysm was retreated twice with repeat coiling. After the third recurrence and persistent aneurysm growth into a giant, symptomatic lesion, we decided to proceed with flow diversion. We performed Y-stenting of the basilar bifurcation using three PFEDs, and was recoiled the aneurysm sac. Due to the low porosity of the flow diverters, a side-by-side double-barrel configuration was necessary in the basilar artery. Without the PFED's resheathable capability, it would not have been possible to perform Y-stenting with flow diverters.

Jailed double-microcatheter technique following horizontal stenting for coil embolization of intracranial wide-necked bifurcation aneurysms: A technical report of two cases

The horizontal stenting technique facilitates endovascular treatment of wide-necked bifurcation intracranial aneurysms. Previous literature shows, however, that subsequent coil embolization at initial treatment results in incomplete obliteration in many cases. The authors present two consecutive cases of wide-necked large bifurcation aneurysms to describe an additional coil embolization technique following horizontal stenting. The patients were a 53-year-old female with an unruptured internal carotid artery terminus aneurysm and a 57-year-old female with a recurrent basilar artery tip aneurysm. Both patients underwent endovascular treatment with horizontal stenting followed by coil embolization with jailed double-microcatheters. Immediate complete obliteration was achieved with no complications, and no recanalization was observed at the one-year follow-up in both cases. Coil embolization with jailed double-microcatheter technique following horizontal stenting is a safe and effective strategy for wide-necked bifurcation aneurysms.

Vascular angular remodeling by kissing-Y stenting in wide necked intracranial bifurcation aneurysms

Introduction

Single stent deployment leads to a change in vascular geometry in wide necked bifurcation aneurysms. In some complex cases, the use of the single stent technique might not be sufficient or may not be feasible. The kissing-Y stenting technique appears to be an alternative endovascular treatment option. The aim of this study was to evaluate the effects of the kissing-Y stenting technique on vascular angular remodeling.

Methods

21 patients with wide necked intracranial bifurcation aneurysms at different sites (10 anterior communicating artery, 6 middle cerebral artery, 3 basilar artery, 1 vertebral artery/posterior inferior cerebellar artery, 1 internal carotid artery/posterior communicating artery) were treated with 44 closed cell stents (follow-up 2012–2016) using the kissing-Y stenting technique. We analyzed vascular angle geometry between the mother and both affected daughter vessels by digital subtraction angiography, before and after stent deployment, using standard working projections.

Results

Endovascular treatment of wide necked intracranial aneurysms using the kissing-Y stenting technique significantly decreased the angle between the bifurcation branches from 130.4±9.5° to 91.5±9.1° (p<0.0001).

Conclusions

Kissing-Y stenting in wide necked bifurcation aneurysms leads to vascular angular remodeling of both affected branches. The resulting straightening of the bifurcation angle may prevent aneurysmal recurrence.

Stent-assisted embolization of wide-neck anterior communicating artery aneurysms: Review of consecutive 34 cases

OBJECTIVE

We report our experience with stent-assisted coiling of anterior communicating artery aneurysms with special consideration of angiographic and clinical outcomes, retreatment rate and periprocedural complications.

MATERIALS AND METHODS

The analysis included 34 consecutive ruptured and unruptured wide-neck aneurysms. The aneurysm size ranged from 2 to 18mm (mean 5.47). Clinical examinations with the use of modified Rankin Score and angiographic outcomes were evaluated initially post-embolization and at a minimum follow-up of 6 months.

RESULTS

Initial post-treatment complete and near-complete aneurysm occlusion was achieved in 32 (94%) and 2 (6%) cases, respectively. Imaging follow-up, performed in 28 (82%) patients, showed no change in the degree of occlusion in 25 (89%) cases and coil compaction in 3 (11%) patients. Of these, one (3.6%) patient underwent a second coil embolization. The periprocedural severe complication rate was 2.9% (1/35) and was associated with prolonged attempt of retrieval of migrated coil resulting in anterior cerebral artery infarct with serious clinical consequences. In another 3 patients periprocedural adverse events without delayed clinical consequences were noticed. The clinical follow-up evaluation achieved in 33 (97%) patients showed no change in 30 (91%) cases, one patient (3%) with clinical improvement and two (6%) cases of neurological deterioration.

CONCLUSIONS

The use of stent is feasible and effective for coil embolization of wide-necked anterior communicating artery aneurysms. Although periprocedural complications resulting in severe morbidity are rare, they should be noted, since in terms of thromboembolic events some of them presumably have a potential to be avoidable.

Computational fluid dynamics of cerebral aneurysm coiling using high-resolution and high-energy synchrotron X-ray microtomography: comparison with the homogeneous porous medium approach

BACKGROUND

Computational modeling of intracranial aneurysms provides insights into the influence of hemodynamics on aneurysm growth, rupture, and treatment outcome. Standard modeling of coiled aneurysms simplifies the complex geometry of the coil mass into a homogeneous porous medium that fills the aneurysmal sac. We compare hemodynamics of coiled aneurysms modeled from high-resolution imaging with those from the same aneurysms modeled following the standard technique, in an effort to characterize sources of error from the simplified model.

MATERIALS

Physical models of two unruptured aneurysms were created using three-dimensional printing. The models were treated with coil embolization using the same coils as those used in actual patient treatment and then scanned by synchrotron X-ray microtomography to obtain high-resolution imaging of the coil mass. Computational modeling of each aneurysm was performed using patient-specific boundary conditions. The coils were modeled using the simplified porous medium or by incorporating the X-ray imaged coil surface, and the differences in hemodynamic variables were assessed.

RESULTS

X-ray microtomographic imaging of coils and incorporation into computational models were successful for both aneurysms. Porous medium calculations of coiled aneurysm hemodynamics overestimated intra-aneurysmal flow, underestimated oscillatory shear index and viscous dissipation, and over- or underpredicted wall shear stress (WSS) and WSS gradient compared with X-ray-based coiled computational fluid dynamics models.

CONCLUSIONS

Computational modeling of coiled intracranial aneurysms using the porous medium approach may inaccurately estimate key hemodynamic variables compared with models incorporating high-resolution synchrotron X-ray microtomographic imaging of complex aneurysm coil geometry.

In vitro experiments of vessel wall apposition between the Enterprise and Enterprise 2 stents for treatment of cerebral aneurysms

BACKGROUND

A closed-cell stent called Enterprise has been used for stent-assisted coil embolization of cerebral aneurysms. The Enterprise stent tends to cause kinks and vessel wall malposition in curved vessels and may cause thromboembolic complications. We evaluated vessel wall apposition of a new closed-cell stent, Enterprise 2, compared with a previous Enterprise stent, using curved vascular silicone models.

METHODS

The Enterprise or Enterprise 2 stent was deployed in curved vascular models with various radii of approximately 5 to 10 mm. Stent deployment was performed 25 times in each stent. A push-pull technique was used to minimize incomplete wall apposition. To evaluate conformity of stents, gaps between a stent and a vessel wall were measured.

RESULTS

The gap ratio (gap / a wall diameter) was 15 % ± 17 % (mean ± standard deviation) and 41 % ± 15 % with the Enterprise 2 stent and the Enterprise stent, respectively. Taking gap ratios and radii of vessel curvature into consideration, the Enterprise 2 stent had significantly better wall apposition than the Enterprise stent (p = 0.005). In the same radius of vessel curvature, the Enterprise 2 stent had approximately half of the gap compared with the Enterprise stent. There were no significant differences in vessel straightening effects between the two stents.

CONCLUSIONS

The Enterprise 2 stent has better wall apposition in curved vessels than the Enterprise stent. The gap between a vessel wall and the Enterprise 2 stent is approximately half that of the Enterprise stent. However, gaps and kinks are still present in curved vessels with a small radius. Caution should be taken for kinks and malposition in acutely curved vessels, such as the siphon of the internal carotid artery.

Intra-aneurysmal hemodynamics: evaluation of pCONus and pCANvas bifurcation aneurysm devices using DSA optical flow imaging

Background

Implantation of self-expanding stents from the parent artery into the sac of a bifurcation aneurysm is regularly used to facilitate endovascular coil occlusion with the so-called waffle cone technique (WCT). Self-expanding aneurysm bridging stents like Solitaire AB, can be used; however, bifurcation devices like pCONus and pCANvas are especially designed for WCT. These devices provide additional support for coil implantation owing to intraluminal nylon fibers (pCONus) or membranes (pCANvas) covering the intracranial aneurysm neck.

Objective

Assessment of the intra-aneurysmal hemodynamic impact of these three devices: a regular intracranial stent (Solitaire AB) and two bifurcation devices (pCONus and pCANvas).

Material and methods

An in vitro experiment was set up using a silicone model of a basilar tip aneurysm filled with blood mimicking fluid under a pulsatile circulation. Solitaire AB, pCONus, and pCANvas were successively implanted in the model for hemodynamic evaluation. High frame rate DSA series were acquired under various conditions. Intra-aneurysmal flow changes, including mean aneurysm flow amplitude ratio (R), were subsequently assessed by the optical flow method, measuring the detector velocity field before and after device implantations.

Results

pCONus and Solitaire minimally reduced the intra-aneurysmal flow (R=0.96, p=0.17 and R=0.91, p=0.01, respectively), whereas pCANvas strongly diminished the intra-aneurysmal flow (R=0.41, p=5×10⁻¹²).

Conclusions

Waffle cone deployment of stents and technique-specific devices had no undesirable effect on the intra-aneurysmal flow. In particular, no increased flow was redirected into the aneurysm sac. The intraluminal membrane of the pCANvas strongly reduced the intra-aneurysmal flow, potentially preventing recanalization problems.

LEO Baby Stent Use following Balloon-Assisted Coiling: Single- and Dual-Stent Technique--Immediate and Midterm Results of 29 Consecutive Patients

BACKGROUND AND PURPOSE

We report our preliminary results in terms of safety and efficacy in using the low-profile LEO Baby stent for the treatment of large-neck and complex intracranial aneurysms with balloon-then-stent-assisted coiling and single- or dual-stent-assisted coiling.

MATERIALS AND METHODS

Clinical and radiologic data of all consecutive patients treated at our institution from September 2012 to October 2013 for an intracranial aneurysm by using a LEO Baby stent were retrospectively analyzed. Immediate and midterm clinical and anatomic follow-up of each patient is reported.

RESULTS

Twenty-nine patients with 29 aneurysms were treated with LEO Baby stents at our institution. The mean age of patients was 48 years; 20 patients were women (71%). One patient was treated in the acute phase of a subarachnoid hemorrhage. In 8 procedures, a double-lumen-catheter balloon was used for balloon-then-stent-assisted coiling. In 3 cases, a LEO Baby stent was used in a Y-, T-, and telescopic dual-stent configuration. In 18 cases, a single LEO Baby stent was used. In 2 cases, technical failure to deploy the stent resulted in acute parent artery thrombosis. In 3 further cases, thromboembolic complications occurred intraoperatively. MR imaging and angiographic midterm follow-up showed complete aneurysm occlusion for 96% of the followed patients (27/29). Clinical outcome was favorable for all patients followed up.

CONCLUSIONS

Results obtained in our study by using the LEO Baby stent for balloon-then-stent and single- or dual-stent-assisted coiling of complex and distally located intracranial aneurysms are encouraging. Incomplete or inadequate opening of the device is a potential cause of laminar blood flow alteration and thrombus formation.

Stent-Assisted Coiling of Wide-Neck Intracranial Aneurysms Using Low-Profile LEO Baby Stents: Initial and Midterm Results

BACKGROUND AND PURPOSE

Low-profile self-expandable stents were recently introduced for the treatment of wide-neck intracranial aneurysms. This study investigated the initial and midterm clinical and angiographic results of LEO Baby stent-assisted coiling in the treatment of wide-neck intracranial aneurysms.

MATERIALS AND METHODS

A retrospective review was performed to identify patients who were treated with LEO Baby stent-assisted coiling. Eighty patients with 80 wide-neck intracranial aneurysms were included in the study. Eleven patients (13.8%) presented with subarachnoid hemorrhage. All patients were treated with LEO Baby stent-assisted coiling. Technical success and immediate postprocedural clinical and angiographic outcomes were evaluated. Seventy-three patients attended angiographic and clinical follow-up for a mean duration of 7.2 ± 3.8 months. Periprocedural and delayed complications were reviewed. Preprocedural and follow-up clinical statuses were assessed by using the modified Rankin Scale.

RESULTS

The technical success rate of the procedure was 97.5%. The immediate postprocedural angiography revealed a complete occlusion of the aneurysm in 75% of the 80 patients. The last follow-up angiograms showed complete occlusion in 85.7% of the 77 patients with an angiographic follow-up. Of the 77 patients with a follow-up angiography, 6.5% showed an increase in the filling status of the aneurysm and 5.2% required retreatment. The overall procedure-related complication rate, including asymptomatic complications, was 11.3%. The permanent morbidity rate was 3.8%. There was no mortality in this study.

CONCLUSIONS

This case series demonstrates the relative safety, efficacy, and midterm durability of the LEO Baby stent-assisted coiling procedure for the treatment of wide-neck intracranial aneurysms.

Geometrical characteristics after Y-stenting of the basilar bifurcation

PURPOSE

We aimed to investigate the angular changes after Y-stenting of the basilar bifurcation aneurysms.

METHODS

A total of 19 patients (age range, 27-80 years; mean age, 52.5 years) underwent Y-stent coiling for basilar bifurcation aneurysm. Three vascular angles (α, β1, β2) were measured in the anteroposterior plane. β1 and β2 represented the angles between the basilar artery and the proximal P1 segments of the right and left posterior cerebral arteries, respectively. α represented the complementary angle between the β1 and β2 angles. Angles were measured before and after stent deployment. Diameters of the basilar artery and P2 segment of the posterior cerebral artery were measured at both sides. Correlation between vascular diameter and angular change of the basilar bifurcation was investigated.

RESULTS

Statistically significant α, β1, and β2 angle changes were found after stent deployment (P < 0.001). There was no statistically significant relationship between the diameter of the basilar artery and the α, β1, β2 angle changes (P > 0.05). There was no statistically significant relationship between the diameter of the posterior cerebral artery and the β angle change (P > 0.05). We found a statistically significant inverse correlation between pre-stent β angle and post-stent angle change (right side, P = 0.008; left side, P < 0.001).

CONCLUSION

Y-stenting narrows the effective neck and straightens the vascular bifurcation angle. Most of the angular remodeling occurs on the side that had a more acute angle before stent deployment.

Assisted coiling using LEO Baby or LVIS Jr stents: Report of six cases

BACKGROUND AND PURPOSE

Endovascular treatment of broad-neck, complex cerebral aneurysms is a challenging issue. Placement of a stent over the aneurysm neck and secondary coil embolization prevents coil migration and allows dense packing of the coils. Another challenge is represented by distal aneurysms situated in small vessels. In these cases, the use of little stents, which we are going call ministents, could be a good decision. These low-profile intracranial ministents can be deployed into arteries with diameters between 1.5 and 3.10 mm and delivered through microcatheters with an internal diameter of 0.0165 inches, which allows easier navigation in small-sized, delicate vessels. We present six cases of wide-neck aneurysms, with small parental arteries less than 2.5 mm using a low-profile ministent system (LEO Baby and LVIS Jr) plus coil embolization.

MATERIALS AND METHODS

We retrospectively reviewed patients in whom LEO Baby or LVIS Jr stent was used for the treatment of intracranial aneurysms. Five aneurysms were treated during 2013-2014 in our service using the LEO Baby stent and one aneurysm using LVIS Jr. Stent-assisted coil embolization was performed using the jailing technique in all cases. Clinical and angiographic findings, procedural data, and follow-up are reported.

RESULTS

Six consecutive patients were included in this study. Four patients presented with subarachnoid hemorrhage in the subacute-chronic phase and two patients had unruptured aneurysms. Two of the six aneurysms were located at branches of the sylvian artery, one at the basilar artery, two at the anterior communicating artery, and one at the P1-P2 artery. The procedures were successful. Six-month control digital subtraction angiograms were obtained in all cases; they demonstrated complete occlusion of the aneurysms in all instances. All patients had good clinical outcomes on follow-up, as measured with the Glasgow Outcome Scale and Modified Rankin Scale.

CONCLUSIONS

The results of this small study show that the LEO Baby and LVIS Jr ministents could be safe and efficient for endovascular treatment of intracranial broad-neck aneurysms situated in small arteries.