Beneficial Remodeling of Small Saccular Intracranial Aneurysms after Staged Stent Only Treatment: A Case Series

Stent-Induced Vascular Remodeling in Two-Step Stent-Assisted Coiling Treatment of Brain Aneurysms: A Closer Look Into the Hemodynamic Changes During the Stent Healing Period

Stenting has become an important adjunctive tool for assisting coil embolization in complex-shaped intracranial aneurysms. However, as a secondary effect, stent deployment has been related to both immediate and delayed remodeling of the local vasculature. Recent studies have demonstrated that this phenomenon may assume different roles depending on the treatment stage. However, the extent of such event on the intra-aneurysmal hemodynamics is still unclear; especially when performing two-step stent-assisted coiling (SAC). Therefore, we performed computational fluid dynamics (CFD) analysis of the blood flow in four bifurcation aneurysms focusing on the stent healing period found in SAC as a two-step maneuver. Our results show that by changing the local vasculature, the intra-aneurysmal hemodynamics changes considerably. However, even though changes do occur, they were not consistent among the cases. Furthermore, by changing the local vasculature not only the shear levels change but also the shear distribution on the aneurysm surface. Additionally, a geometric analysis alone can mislead the estimation of the novel hemodynamic environment after vascular remodeling, especially in the presence of mixing streams. Therefore, although the novel local vasculature might induce an improved hemodynamic environment, it is also plausible to expect that adverse hemodynamic conditions might occur. This could pose a particularly delicate condition since the aneurysm surface remains completely exposed to the novel hemodynamic environment during the stent healing period. Finally, our study emphasizes that vascular remodeling should be considered when assessing the hemodynamics in aneurysms treated with stents, especially when evaluating the earlier stages of the treatment process.

Effect of Straightening the Parent Vessels in Stent-Assisted Coil Embolization for Anterior Communicating Artery Aneurysms

BACKGROUND

Stent-assisted coil embolization (SAC) for treating anterior communicating artery (AcomA) aneurysms is safe and effective. Straightening of parent vessels by stent placement can lead to progressive thrombosis. We describe our experience with SAC for AcomA aneurysms and demonstrate the effect of straightening the parent vessels.

METHODS

A total of 26 patients with AcomA aneurysms were treated using SAC in our institute between July 2010 and December 2017. Follow-up digital subtraction angiography was performed 6 months after treatment, magnetic resonance angiography was performed every year, and outcomes were analyzed.

RESULTS

From all aneurysms (n = 24), 12 (50.0%) were neck remnant, and 12 (50.0%) were dome-filling types immediately after the procedure. At the 6-month digital subtraction angiography follow-up (n = 22), 13 (59.1%) aneurysms were complete obliteration, 8 (36.4%) were neck remnant, and 1 (4.5%) was dome filling. The median parent vessel angle was measured preoperatively at 98.1°, increased to 124.8° immediately after stent deployment, and further increased to 149.6° at the 6-month follow-up. Progressive thrombosis was observed in 13 of 22 (59.1%) aneurysms. The parent vessel angle change immediately after stent deployment in the progressive thrombosis group tended to be larger than that observed in the no thrombosis group; this change was significant at the 6-month follow-up. The median follow-up term was 18 months. No patients required retreatment.

CONCLUSIONS

Good SAC outcomes were achieved for AcomA aneurysms, and hemodynamic changes related to straightening of the parent vessels is a consideration in SAC.

Flow-Diversion Effect of LEO Stents: Aneurysm Occlusion and Flow Remodeling of Covered Side Branches and Perforators

BACKGROUND AND PURPOSE

Flow diversion with intermediate-porosity stents (braided stents) has been recently reported for distally located small aneurysms. The aim of this study was to evaluate the flow-diversion effect of LEO stents on covered vessels and for aneurysms treated with sole stent-placement therapy.

MATERIALS AND METHODS

We retrospectively evaluated the following outcomes: 1) remodeling of covered side branches and perforators (extra-aneurysmal flow remodeling), and 2) the occlusion rate of aneurysms treated with sole stent-placement therapy (intra-aneurysmal flow remodeling).

RESULTS

Seventy-six patients with 98 covered vessels were studied. Overall, 89 covered arteries (91%) were normal, 7 showed narrowing (7%), and 2 (2%) were occluded (1 posterior communicating artery and 1 MCA) without related complications (mean DSA follow-up, 14 months). Univariate and multivariate analyses highlighted smoking (P = .03) and the length of follow-up (P = .002) as factors associated with arterial remodeling. Of the 17 Sylvian (lenticulostriate arteries) and 7 basilar perforators, 1 (4%) group of Sylvian perforators covered with double stents had asymptomatic remodeling. Ten aneurysms (mean size, 3.5 mm) were treated with LEO stents as stent monotherapy (5 recanalized after coiling and 5 directly treated with the LEO). Complete occlusion (Raymond-Roy I) was achieved in 70% of aneurysms (mean follow-up, 14 months). The Raymond-Roy I occlusion rate among recanalized aneurysms and those directly treated with LEO stents was 80% and 60%, respectively (P = .9).

CONCLUSIONS

The rate of flow remodeling on the covered arteries and perforators was 9% and 4%, respectively, and was clinically irrelevant in all cases. Complete occlusion of aneurysms treated with sole stent-placement therapy was 70%. These data stress the flow-diversion properties of LEO stents.

Angiographic Characteristics and Endovascular Treatment of Anterior Cerebral Artery A1 Segment Aneurysms

OBJECTIVE

This report aimed to review the angiographic characteristics and evaluate the safety and feasibility of endovascular treatment of A1 aneurysms.

METHODS

Nineteen ruptured and 13 unruptured A1 aneurysms treated endovascularly were evaluated in this study. The angiographic and clinical records were retrospectively reviewed.

RESULTS

Endovascular treatments were successfully applied in all 32 aneurysms. Conventional coiling was performed in 24 aneurysms, stent-assisted coiling in 7, and solo stenting in 1. The immediate angiographic result was 1 aneurysm in 15, two aneurysms in 10, and 3 in 7 aneurysms according to the Raymond grade. Intraoperative rupture was detected in 1 case without clinical consequence, and no other procedure-related complication occurred. Angiographic follow-up (mean, 12 months; range, 2-42 months) of 25 aneurysms showed total occlusion in 20, improvement in 1, stability in 3, and recurrence in 1. The only recurrence was detected in a case treated using conventional coiling, and it was retreated with stent-assisted coiling. Clinical follow-up (mean, 25 months; range, 6-93 months) was available in 24 of 30 patients, and the modified Rankin Scale score was 0-1 in 22 patients.

CONCLUSIONS

Endovascular treatment is technically feasible and safe for A1 aneurysms.

Comparison of simulated structural deformation with experimental results after Wingspan stenting

OBJECTIVES

Biomechanical stress distribution correlates with the biological responses after stenting. Computational analyses have contributed to the optimization of stent geometry. In particular, structural analysis based on pre-operative angiography can be used to predict the stent-artery interaction before endovascular treatments. However, the simulated results need to be validated. In this report, we compared the simulated arterial structure with post-operative images after an intracranial Wingspan stent.

METHODS

A Wingspan stent was deployed at a slightly curved ascending pharyngeal artery (APA) in the swine. Using a finite element method (FEM), the configuration after stenting was simulated and quantitatively compared with post-procedural 3D angiography.

RESULTS

The finite element analysis demonstrated arterial straightening after stenting. The simulated images were similar to the experimental results with respect to the curvature index of the center line and the cross-sectional areas.

CONCLUSION

We assessed the simulated structural deformation after Wingspan stenting, by comparison with experimental results.