Introduction Flow diverters (FDs) are increasingly used in the treatment of wide-necked aneurysms.

Objective To examine the hypothesis that intentional FD compaction might improve aneurysm occlusion rates.

Methods Bilateral wide-necked carotid aneurysms were created in 12 dogs. Endovascular treatment was performed 1 month later, using Pipeline embolization devices deployed with compaction across the aneurysm neck (n=12). Group 1a consisted of aneurysms treated with a single compacted FD (n=8), while group 1b aneurysms required two compacted FDs (n=4). Control aneurysms were treated with a single non-compacted FD (group 3; n=6), or not treated (group 4; n=4). Angiographic results were compared at 3 months. Pathology specimens were photographed and the neointimal coverage of devices scored using an ordinal grading system.

Results Twenty-two of 24 aneurysms were patent at 1 month. Deployment with compaction was successful in eight cases (group 1a aneurysms). The compaction maneuver led to immediate FD prolapse into the aneurysm in four cases, rescued by deploying a second, telescoping FD (forming group 1b aneurysms). One compacted device later migrated distally, leaving the aneurysm untreated. Angiographic results differed significantly between groups (p=0.0002). At 3 months, aneurysms successfully treated with a single compacted FD were more often occluded at 3 months (7/7) than aneurysms flow-diverted without compaction (2/6; p=0.021). All aneurysms treated with two compacted FDs were occluded, while all untreated aneurysms remained patent. There were no parent vessel stenoses.

Conclusions Compaction of FDs can improve angiographic occlusion of experimental wide-necked aneurysms.