Testing flow diverters in giant fusiform aneurysms: a new experimental model can show leaks responsible for failures

FDs are the latest, most promising tool to treat giant and complex aneurysms. Currently available experimental aneurysm models do not reproduce the potential clinical difficulties of treating these lesions with FDs.

Six large or giant canine fusiform aneurysms were created on the distal carotid arteries of 4 animals. Four of the aneurysms had multiple arterial branches originating from the aneurysm; 2 other aneurysms had all branches clipped at the time of aneurysm construction. Aneurysms were treated with multiple telescoping prototype flow-diverting stents (total of 15 FDs). Angiography was carried out before and immediately after implantation, at 2 weeks, and immediately before sacrifice at 12 weeks. Macroscopic photography of specimens was performed, followed by biopsies of selected regions of the tissue formed on the surface of FDs.

Technical or device-related difficulties occurred in 2 of 6 aneurysm treatments. Fusiform aneurysms with branches intact remained widely patent (mean angiographic score, 3), whereas aneurysms with clipped branches had only small residua (mean angiographic score, 1) at 12 weeks. The presence of very small defects in neointima formation on the surface of FDs, or leaks, was sufficient for residual filling of the aneurysms, which served as reservoirs to feed branches.

Experimental canine fusiform carotid aneurysms may reproduce many of the difficulties associated with the treatment of giant aneurysms and could be appropriate for preclinical testing of FD stents.