In vivo evaluation of the new PHIL low viscosity in a swine rete mirabile model

Abstract

Introduction Few liquid embolic materials are available for treatment of arteriovenous malformations. We describe the in vivo experience with the new PHIL low viscosity (LV) liquid embolic agent in a swine rete mirabile model. Methods Eight swine were treated. Two animals underwent embolization of a rete with PHIL LV and the contralateral rete with Squid 12 (euthanized the same day). Six animals underwent embolization of the right rete: two with balloon flow arrest (euthanized at 14 d) and four with a microcatheter alone (euthanized at 14 and 90 d). Performance characteristics of the embolic agents were evaluated. Microscopic and histological analysis of the harvested retia was performed. Macroscopic examinations and high contrast digital-based radiographs of the central nervous system were obtained. Results We did not experience any technical complication during embolization of each rete. Overall occlusion ability, on/off injection and ease to retrieve the microcatheter/balloon with PHIL LV were optimal. Fluoroscopic visualization of the PHIL LV cast was adequate to optimal. Average embolization time with flow arrest was 9.5 min versus 19.5 min with microcatheter plugging. Embolizations with PHIL LV required less volume and were shorter when compared to Squid 12. Subacute (14 d) and chronic (90 d) microscopic and histological analysis demonstrated minimal inflammatory changes in the perivascular tissues and permanent occlusion of the embolized vasculature. Conclusion In this swine rete model, the new PHIL LV embolic agent had an excellent embolization performance. Vessels embolized remained occluded up to 90 d from the procedure with minimal inflammatory changes.