Coils, plugs, covered stents, and snares

Devices

The Concerto Detachable Coil System (Medtronic, Minneapolis, MN) consists of nylon or glycolide/L-lactide copolymer (PGLA) fibered helical or three-dimensional (3D) platinum coils and an instant detacher ( Fig. 11.1A–B ). The nylon and PGLA fibers increase thrombogenicity of the coils compared with bare metal equivalents, and the LatticeFX technology promotes thrombosis response. The Concerto Helix coils are available in 2 to 20 mm diameter with a minimum microcatheter compatibility of 0.0165 inches (for 2–4 mm diameter coils) or 0.021 inches (for 5–20 mm diameter coils). The Concerto PGLA 3D coils are available in 2 to 18 mm diameter with 0.0165-inch microcatheter compatibility for up to 10 mm coils. The AXIUM Detachable Coils (Medtronic, Minneapolis, MN; see Fig. 11.1C–E ) have an outer diameter of 0.014 inches and can be delivered through smaller microcatheters such as Corsair/Caravel (Asahi Intecc USA, Tustin, CA) or Turnpike (Teleflex, Morrisville, NC). The Concerto and AXIUM coils are fully resheathable after complete or partial deployment and are therefore easy to reposition.

The AZUR Embolization System (Terumo Interventional Systems, Somerset, NJ) consists of a family of coils: Framing Coil, CX, and Hydrocoil. The AZUR Hydrocoils consist of hydrogel that expands four to five times the original size in the presence of blood to create a mechanical occlusion. The coils are available in diameters ranging from 2 to 20 mm and have a detachable or pushable system. The 0.018-inch coils can be delivered via microcatheters with inner diameter of 0.021 to 0.027 inches, whereas the 0.035-inch coils require diagnostic catheters with inner diameters of 0.038 to 0.047 inches for delivery.

Other peripheral embolization coil systems include the Boston Scientific pushable coils (Boston Scientific, Marlborough, MA), which are available in six shapes (complex helical, VortX, VortX Diamond, straight, figure 8, and multi-loop/two-dimensional [2D] helical) and have highly thrombogenic dense Dacron fibers; the pushable (Nestor, Tornado, MReye, Hilal) or detachable (Retracta, MReye Flipper) fibered embolization coils and microcoils from Cook Medical (Bloomington, IN); and the Ruby Coil Large-Volume and Low-Profile Systems (Penumbra Inc., Alameda, CA).

Applications

Peripheral embolization coils can be used to occlude coronary artery aneurysms, SVG aneurysms, coronary artery fistulas, and left internal mammary artery (LIMA) side branches that cause coronary steal phenomenon in patients with LIMA to left anterior descending coronary artery bypass grafts. For treatment of aneurysms, large-diameter framing/filling coils (e.g., Concerto 3D, AXIUM PRIME FRAME, AZUR Framing/CX, Helical/VortX Diamond, or Ruby Coil) are delivered within the aneurysmal sac. This can be performed directly or using one of the stent-assisted techniques in which a noncovered stent is deployed across the aneurysm and coils delivered into the aneurysm sac through the stent struts or coils delivered via a microcatheter into the aneurysm jailed by a coronary balloon followed by placement of a noncovered stent. Often, occluding the inflow is necessary to achieve complete cessation of flow into the aneurysm sac. This can be accomplished with packing coils (e.g., Concerto Helix, AXIUM PRIME SOFT or MICROFX, AZUR Hydrocoil, VortX, or Tornado) or by deploying a vascular plug in the proximal nonaneurysmal part of the coronary artery (if the distal coronary is known to be occluded or is bypassed), or with the use of covered stents deployed across the aneurysm.

More frequently, embolization coils are used for the management of bleeding from small vessel perforation at the site of vascular access or in a coronary artery. Once a small vessel/branch perforation is identified by angiography, a 0.014-inch workhorse wire is advanced into the branch beyond the site of perforation. A coronary or peripheral microcatheter is then advanced over the wire, through which microcoils (oversized 1–2 mm to the target vessel) may be deployed using either a pushable or a detachable system. A block and deliver (BAD) technique (also known as the “balloon microcatheter technique”) has been described in which a balloon is inflated in the vessel proximal to the perforation site to occlude flow, and a microcatheter compatible with at least a 6 French (F) guiding catheter is advanced to the site of perforation over a second parallel guidewire during a very brief deflation of the occluding balloon. A small-volume contrast injection is performed through the microcatheter lumen to confirm persistent extravasation by fluoroscopy, and coils are delivered while maintaining proximal occlusion. The balloon is then deflated, and final angiography is performed to ensure complete cessation of contrast extravasation. In chronic total occlusion (CTO) percutaneous coronary interventions (PCI) via retrograde approach, especially through epicardial collaterals, both antegrade and retrograde coil embolization is often necessary for effective treatment of coronary or collateral perforation ( Video 11.1 ).