Liquid embolic agent Fe3O4-EVOH for endovascular arteriovenous malformation embolisation: Preliminary evaluation in an in vivo swine rete mirabile model

Abstract

Aim: Arteriovenous malformation (AVM) embolisation is in peril after the ARUBA trial. Advancements that are needed to reduce procedural risk are better control and visualisation during micro-catheter injection of liquid embolic material. The injectability, radiographic visualisation, mechanical stability and biocompatibility of the embolic agent Fe₃O₄-EVOH was evaluated in an in vivo swine AVM model.

Methods: The swine AVM model is the rete mirabile (RM). Nine swine AVM models were embolised with the embolic agent Fe₃O₄-EVOH by using a 1.5 F micro-catheter. Procedure times, embolisation success (defined as complete embolisation of the nidus), volume of embolic agent and histopathology were assessed.

Results: Six swine underwent embolisation of one side rete, and three underwent embolisation of both sides. We did not experience any technical complication during embolisation of each rete. The micro-catheter was easy to retrieve. Fluoroscopic visualisation of the Fe₃O₄-EVOH cast was adequate. The mean embolisation time for each RM was 7.5 minutes. The median volume of the embolic agent for each RM was 0.52 mL. At one, four and eight weeks following injection, microscopic and histological analysis demonstrated minimal inflammatory changes in the perivascular tissues and permanent occlusion of the embolised vasculature.

Conclusion: Fe₃O₄-EVOH embolic agent is an effective endovascular occlusion material, providing the initial in vivo characteristics of stability and biocompatibility.

Keywords: Fe3O4-EVOH; arteriovenous malformation; embolisation; rete mirabile.

Figure 1.

(a) The right APAs directly feed the portion of the RM. The common carotid artery branch just before the base of the skull into the external carotid arteries and the APAs. (b) Note the tip of the micro-catheter in the distal ascending pharyngeal artery (APA). (c) Unsubtracted fluoroscopy of embolic agent cast (arrow). APA: ascending pharyngeal artery; RM: rete mirabile.

Figure 2.

Hematoxylin and eosin–stained photomicrographs of RM cross-section. (a) At one week after injection, an intact internal elastic lamina with luminal embolic material is shown. (b) At four weeks after injection, adventitial chronic inflammatory cell infiltration is shown. (c) At eight weeks after injection, the Fe₃O₄-EVOH surrounded by a tissue growth beginning to encapsulate the polymer is shown.