Peripheral Vasculature Embolization with the Onyx Liquid Embolic System in a Swine Model.

Purpose: To characterize the histologic and inflammatory changes that resulted from peripheral embolization using ethylene vinyl alcohol ([EVOH]; Onyx) in an animal model. This study also assessed the radiopacity of the Onyx after a 1-minute mixing time.

Materials and methods: Embolization using EVOH alone or in combination with coils/plugs was performed on large-vessel, small-vessel, and very-small-vessel (3-5 mm, 1-3 mm, and <1 mm in diameter, respectively) targets in the peripheral vasculature of Yucatan miniature pigs. Multiple formulations of EVOH were used. Angiography at 1, 3, and 12 months was used to assess embolic migration and vessel occlusion. Pathological evaluations were performed to assess the biological response to Onyx-mediated embolization.

Results: Angiography demonstrated that the radiopacity of EVOH was sufficient for control during deployment in 98.2% of the procedures. Microcatheter removal was successful in all cases, and there was minimal migration of EVOH after delivery. Pathological findings indicated no significant tissue response or vessel trauma after embolization, and the occlusive material (consisting of EVOH, thrombus, and fibrotic tissue) evolved over time. The inflammatory response was minimal to mild, and vessel wall injury was observed in some cases. Complete to near-complete occlusion was achieved at every embolization site at the time of follow-up, although histologic evidence of recanalization was observed in 59.3% of the treated vessels.

Conclusions: The study demonstrated the effectiveness of EVOH as an embolic agent in the peripheral vascular system with adequate radiopacity, minimal adverse effects, and acceptable long-term histologic outcomes in a swine model.