Entry remnants in flow-diverted aneurysms: Does branch geometry influence aneurysm closure?

Abstract

<jats:sec><jats:title>Objective</jats:title><jats:p> Numerous studies have suggested a relationship between delayed occlusion of intracranial aneurysms treated with the Pipeline Embolization Device (PED) and the presence of an incorporated branch. However, in some cases, flow diversion may still be the preferred treatment option. This study sought to determine whether geometric factors pertaining to relative size and angulation of branch vessel(s) can be measured in a reliable fashion and whether they are related to occlusion rates. </jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p> Eighty aneurysms treated at a single neurovascular center from November 2008 to June 2014 were identified. Two blinded raters prospectively reviewed the imaging performed at the time of the procedure and measured the following geometric variables: inflow jet/incorporated branch direction angle and branch artery/ parent artery ratio. Delayed occlusion was defined as the absence of complete aneurysmal occlusion at one year. Analysis was performed using logistic regression and intra-class correlation co-efficient (ICC). </jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p> Twenty-four (30%) aneurysms with 28 incorporated branches were identified. A trend toward higher inflow jet/incorporated branch direction angle was found in the group of aneurysms demonstrating delayed occlusion when compared to the group with complete occlusion. ICC revealed high correlation. Overall lower one-year occlusion rates of 53% versus 73% for aneurysms with and without incorporated branches, respectively, were also noted. </jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p> The presence of an incorporated branch conferred a 20% absolute risk increase for delayed aneurysmal occlusion. Incorporated branches with a larger angle between the inflow jet and the incorporated branch direction exhibited a trend toward lower occlusion rates. This might be further investigated using a multicenter approach in conjunction with other potentially relevant clinical and angiographic variables. </jats:p></jats:sec>

The Silk Vista Baby – The UK experience

“…23 It is also worth noting that many aneurysms arising from the distal vasculature are bifurcation aneurysms in some form and as such may well have a branch vessel incorporated into the aneurysm dome or neck. This configuration has previously been shown to slow the aneurysm occlusion rate 24,25 and for bifurcation aneurysms it has been said that a longer time frame for occlusion, perhaps upto 18 months, may be required for complete occlusion. 26,27 Similarly, with respect to Acom aneurysms the configuration may also play an important role in the success of flow diversion.…”

Flow diversion for treatment of intracranial aneurysms: Mechanism and implications

“…45,46 FD treatment failure is usually attributed to inadequate coverage of the aneurysm, presence of a pre-existing stent, presence of an incorporated branch, or endoleak analogous to that seen in endovascular abdominal aortic aneurysm repair. 47,48 However, these do not explain recurrence in completely occluded aneurysms. Other mechanisms that could explain recurrence are branch vessel runoff or improper endothelialization and thrombus formation leading to aneurysm recurrence and delayed rupture despite angiographic evidence of complete occlusion.…”

“…Some clinical trials have shown there is potential for recurrence of an aneurysm once it is completely occluded after treatment with an FD . FD treatment failure is usually attributed to inadequate coverage of the aneurysm, presence of a pre‐existing stent, presence of an incorporated branch, or endoleak analogous to that seen in endovascular abdominal aortic aneurysm repair . However, these do not explain recurrence in completely occluded aneurysms.…”