Flow Diversion of Giant Curved Sidewall and Bifurcation Experimental Aneurysms with Very-Low-Porosity Devices

OBJECTIVE: Flow diverters (FDs) are increasingly used to treat difficult intracranial aneurysms. The objective of this study was to test whether treatment challenges posed by giant curved sidewall (cSW) and endwall bifurcation (EwB) aneurysms can be overcome with the use of very-low-porosity devices. METHODS: Large and giant EwB (n = 12) and cSW aneurysms (n = 5) were constructed in 17 dogs. EwB aneurysms were treated with 48 (n = 4), 64 (n = 4), or two overlapping 64-wire low-porosity devices (n = 4), whereas all cSW aneurysms were treated with single 64-wire devices. Angiographic results were recorded immediately and at 12 weeks before euthanasia. Pathologic specimens were photographed and neointimal coverage of devices measured and scored. RESULTS: By 12 weeks, 1 of 12 EwB and 1 of 5 cSW aneurysms were occluded. All other aneurysms were patent. Device-related arterial stenoses occurred in 13 of 17 animals, hemodynamically significant in two. All branches jailed by the FDs remained patent. There was a significant correlation between angiographic scores and the degree of neointima formation on the device (Rho = 0.527; P = 0.04). Failures of aneurysm occlusion could be explained by holes, sometimes barely visible, in the neointima that formed over FDs. CONCLUSION: Low-porosity FDs fail to reliably occlude experimental giant EwB and cSW aneurysms.