Amplatzer-Onyx Sandwich: A Method for Impermeable Proximal Cerebral Vessel Occlusion

Abstract

Editor: The treatment of intracranial vascular lesions is usually undertaken with the goal of parent artery preservation. In some instances of fusiform lesions, proximal parent vessel occlusion becomes the only therapeutic option (1). Parent vessel occlusion had previously successfully relied on the intraluminal deployment of detachable silicone balloons (DSB; Boston Scientific, Natick, Mass), which are no longer available. Current endovascular arterial occlusion is performed with detachable coils, including fibered (2) and Hydrogel-coated variants. Because outward radial force may be insufficient to anchor coils to the intima in compliant arteries not confined within a bony canal, reliance on coils alone can be complicated by distal migration. The use of the Amplatzer detachable vascular plug (AGA Medical, Golden Valley, Minn) has been recently reported in the high cervical vessels to achieve endovascular occlusion of the carotid or vertebral artery by acting as an endovascular anchor in combination with coils (3). A 66-year-old woman presented with new-onset diplopia and a partial left sixth cranial nerve palsy resulting from compressive mass effect by a 3.3-cm giant fusiform left cavernous internal carotid artery (ICA) aneurysm with a wide 1.8-cm neck (Figure, a). Parent vessel occlusion was selected as the method of treatment following successful balloon test occlusion with hypotensive challenge supported by single photon emission computed tomography perfusion study. Parent vessel occlusion was performed under monitored anesthesia care after starting oral aspirin therapy. Under systemic heparin anticoagulation (activated clotting time 250 seconds), and through a microcatheter advanced via a 6-F MPD guide catheter (Cordis Neurovascular, Miami, Fla) in the cervical left ICA, a combination of bare and fibered platinum (Boston Scientific) and Hydrogel-coated (MicroVention, Aliso Viejo, Calif) coils were deployed distal to the aneurysm to prevent retrograde filling of the aneurysm and proximal to the aneurysm neck to achieve parent vessel occlusion. A small but significant antegrade flow persisted in the aneurysm in the late arterial phase. A 6 7-mm Amplatzer vascular plug was deployed at the level of the C2 vertebral body, and this had little effect on antegrade flow. Persistent opacification of the distal ICA and aneurysm remained despite deployment of a second packet of coils proximal to the first vascular plug and even after a second Amplatzer plug and a third proximal coil packet (Figure, b). Ethylene-vinyl alcohol copolymer (EVOH) dissolved in dimethyl sulfoxide and tantalum (Onyx; Micro Therapeutics, Irvine, Calif) has emerged as a useful liquid embolic agent for the endovascular embolization of cerebral arteriovenous malformations (4), with cohesive properties superior to nbutyl-cyanoacrylate. Because of persistent flow-through, we elected to use Onyx proximal to the Amplatzer-coil construct. The pre-mixed Onyx-34 preparation (8% EVOH) was agitated on a rotary shaker as per manufacturer’s recommendations and infused slowly through a microcatheter (Echelon-10; Micro Therapeutics) to a total of 1 mL. This created a 1.4-cm-long plug in the ICA proximal to the third coil packet and instantaneously led to complete occlusion (Figure, c). The patient underwent magnetic resonance (MR) imaging, which showed no evidence of ischemia and no detectable flow within the left ICA. Angiographic follow-up at 2 months revealed complete occlusion (Figure, d), and at 1 year the patient remained asymptomatic with no evidence of flow within the aneurysm or parent vessel at MR angiography. Onyx by itself, in the formulations currently available (Onyx 18 and 34, containing 6% and 8% EVOH, respectively), is unsafe to use in a nontapered high-flow vessel such as the ICA or vertebral artery (VA) for vessel occlusion because of the high risk of dislodgement and distal embolization of the plug from the catheter during injection before flow arrest. In a recent report, Ross and Buciuc (5) reported complete flow cessation distal to a single Amplatzer device 5 minutes after deployment without reversal of anticoagulation. In our experience (3), persistent flow through the interstices of the first vascular plug was encountered in all of our cases, possibly owing to periprocedural antiplatelet therapy. In summary, in cases in which the Amplatzer plug-coil packet does not lead to complete flow arrest, the liquid embolic agent Onyx can be successfully used as an adjunct to create an Amplatzer-Onyx sandwich construct leading to an immediate and durable impermeable vessel occlusion.