Non-Adhesive Liquid Embolic Agents in Extra-Cranial District: State of the Art and Review of the Literature

Abstract

This review focuses on the use of “new” generation of non-adhesive liquid embolic agents (NALEA). In literature, non-adhesive liquid embolic agents have mainly been used in the cerebral district; however, multiple papers describing the use of NALEA in the extracranial district have been published recently and the aim of this review is to explore and analyze this field of application. There are a few NALEA liquids such as Onyx, Squid, and Phil currently available in the market, and they are used in the following applications: mainly arteriovenous malformations, endoleaks, visceral aneurysm or pseudoaneurysm, presurgical and hypervascular lesions embolization, and a niche of percutaneous approaches. These types of embolizing fluids can be used alone or in combination with other embolizing agents (such as coils or particles) so as to enhance its embolizing effect or improve its possible defects. The primary purpose of this paper is to evaluate the use of NALEAs, predominantly used alone, in elective embolization procedures. We did not attempt a meta-analysis due to the data heterogeneity, high number of case reports, and the lack of a consistent follow-up time period.

Spontaneous Haematomas and Embolization: The Challenging Choice of the Embolic Agent

“…Solid agents, such as coils and plugs, are easy to use, cheap, and their release should be controlled using detachable devices, but in any case, the occlusion power depends on the coagulation status [ 5 ].…”

“…Liquid embolic agents, like glue and polymers, work well even when the coagulation capabilities are missing. Glue is an adhesive embolic agent (AEA), characterized by high and immediate occlusive power, but a correct handling requires a long learning curve and anyhow be associated with technical complications (microcatheter entrapment, non-target embolization) [ 5 ].…”

“…Vasospasm scarcely influences vehiculation of EVOH, unlike adhesive agents. A discrete learning curve is required also to handle NAEA [ 5 ] (Fig. 1 A–D).…”

Editorial of Special Issue “Embolization Techniques: State of the Art and Future Perspectives”

“…Embolization is used with the main purpose to obtain a target vessel occlusion [ 4 ] or a significant flow reduction as in conventional chemoembolization [ 5 ], although it can be also used in the case of a vessel bifurcation to determine an obligatory flow direction, for example in case of gastroduodenal artery coil embolization to favor hepatic intra-arterial chemotherapy [ 6 ]. Embolization is routinely performed in many clinical situations including arterial/venous bleeding [ 7 ], vascular/lymphatic malformations [ 8 ], visceral/renal aneurysms [ 9 , 10 ], endoleaks [ 11 ], variceal diseases [ 12 ], pre-surgical treatments [ 13 ], oncological treatments [ 14 ], benign/hypertrophic nodules/organs [ 15 ]. Every embolic agent is characterized by points of strengths and weaknesses and can be used alone or combined with another embolic agent to increase its embolic power.…”

“…Extreme caution is required during glue preparation and delivery to avoid any contact with any ionic solution to prevent premature polymerization. Onyx and Squid are the most used non-adhesive liquid embolic agents, nowadays widely employed also in the extra-cranial district [ 11 ]. Onyx and Squid comprise an ethylene vinyl alcohol (EVOH) copolymer dissolved in dimethyl sulfoxide (DMSO) and suspended micronized tantalum powder to provide radiopacity.…”