The Effect of Placing Flow-Diverting Stents in Intracranial Collateral Arteries of Miniature Pig.

BACKGROUND Flow-diverting stent (FDS) has been suggested as an effective intracranial aneurysm treatment. However, the effects of FDS on collateral branches of an aneurysm parent artery still remain unknown. Thus, the present study aimed to comprehensively evaluate the effects of placing a FDS in the intracranial collateral artery, using a miniature pig animal model. MATERIAL AND METHODS Ten healthy miniature pigs were included in the study: one pig was reserved as a control and the remaining nine pigs were placed in three experimental groups: FDS (i.e., Pipeline), LVIS, and Solitaier-AB stent groups. Pigs in the experimental groups were examined by cerebral angiography immediately after stent placement, followed by hemodynamic analyses. In addition, magnetic resonance imaging (MRI) of the brain of pigs in the experimental groups was performed to inspect the brain for obstruction and blood flow. Stents were examined for the growth of neointimas. RESULTS The results showed that neointimas, consisting of smooth muscle cells, collagenous fibers, and macrophages, were 0.67 mm thick on average and partially covered the stent wires. The thickness of neointimas in the FDS group was significantly higher than in the two conventional intracranial stent groups. There was no obvious obstruction identified in collateral arteries where the FDS was placed. CONCLUSIONS These results indicated that neointimas in collateral arteries of a miniature pig would be slightly thickened after one month of FDS placement; and FDS was shown to be safe for collateral arteries.