25 Stent-Assisted Coiling

General Description

Stent-assisted coiling for the treatment of intracranial aneurysms first was reported by Higashida et al. in 1997. ¹ In that case, a basilar artery aneurysm was treated by deploying a balloon-mounted cardiac stent within the parent artery and coiling the aneurysm by way of catheterization through the stent tines. A year later, Mericle et al. ² followed with a description of the technique for an internal carotid artery aneurysm. Since these early reports, the development of intracranial-specific stents has increased the feasibility and use of stent-assisted coiling for the treatment of intracranial aneurysms.

Evidence

Traditionally, stent-assisted coiling has been reserved for wide-necked aneurysms that are not amenable to primary coiling. Contemporary series by Hetts et al. ³ and Feng et al., ⁴ comparing stent-assisted coiling to primary coiling alone, have demonstrated its safety and efficiency. No difference was found in thromboembolic events, hemorrhagic complications, or procedure-related morbidity. Similarly, there was no statistical significance in initial complete occlusion or recanalization. A systematic review and meta-analysis found improved rates of angiographic occlusion and progressive thrombosis and a reduced rate of recurrent aneurysms treated with stent-assisted coiling, compared to those treated with primary coiling. ⁴

Because of the need for dual antiplatelet therapy, the use of stent-assisted coiling in the setting of an acute subarachnoid hemorrhage traditionally has been met with apprehension. Although, in general, periprocedural morbidity are similar to those of primary coiling, an analysis performed by Bodily et al. ⁵ found hemorrhagic complications to occur in 8% of patients (a rate higher than reported in the literature for primary coiling). For acutely ruptured intracranial aneurysms, stent-assisted coiling remains controversial.

Indications

Stent-assisted coiling typically has been reserved for wide-necked unruptured aneurysms. A wide aneurysm neck is defined as a neck diameter > 4 mm and a dome-to-neck ratio of < 2. In the case of a wide-necked aneurysm, the stent provides a buttress, which prevents coil herniation into the parent vessel. A large tertiary care center reported increased coil packing density with stent-assisted coiling compared to primary coiling alone. ⁶

Neuroendovascular Anatomy

Stent-assisted coiling has been utilized in most locations around the circle of Willis where intracranial aneurysms occur. It is critical to assess the anatomy of the parent vessel in which the stent will be placed. Measurement of the vessel diameter with correct sizing of the stent is necessary to obtain good wall apposition. The stent length should take into account the various turns of the parent artery (this is particularly important when placing a stent within the carotid siphon).

Periprocedure Medications

Use of a stent requires dual antiplatelet therapy. This is typically achieved with aspirin and clopidogrel. It is our practice to begin the dual antiplatelet regimen 5–7 days prior to the procedure with aspirin 325 mg daily and clopidogrel 75 mg daily. When this is not possible, loading doses of both medications (aspirin 650 mg and clopidogrel 600 mg) are administered immediately prior to the procedure. We routinely measure platelet inhibition assays to confirm adequate response to both medications. In cases in which a patient is unresponsive to clopidogrel (reported to occur in up to 50% of the population), we use ticagrelor (loading dose 180 mg, followed by 90 mg twice daily). Dual antiplatelet therapy is continued for 6 months after the procedure, at which time clopidogrel (or ticagrelor) is discontinued and aspirin is maintained indefinitely.

In all cases of stent-assisted coiling, it is our practice to administer systemic heparinization. Full heparinization is confirmed by checking the activated coagulation time (ACT), with a therapeutic ACT of > 300 seconds.

Specific Technique and Key Steps

A 6 or 8 French (F) sheath is placed in the femoral artery.
A guide catheter is placed in the distal cervical segment of the appropriate vessel (e.g., internal carotid artery or vertebral artery) ( Fig. 25.1–25.8, Video 25.1–25.8 ).
A three-dimensional angiogram is performed to assess aneurysm and parent vessel morphology ( Fig. 25.1–25.8 ).
The parent vessel diameter is measured. The length of the stent is approximated by measuring the parent vessel.
Under roadmap guidance, the microcatheter (and intermediate catheter, if used) is advanced.
Jailing technique—One microcatheter is advanced in the parent vessel distal to the aneurysm neck for placement of the stent ( Video 25.1–25.3 ). The stent is then advanced within the microcatheter but not yet deployed. A second microcatheter is advanced into the aneurysm. One or two loops of coil are deployed within the aneurysm. The stent is then deployed and coiling of the aneurysm is completed.
Traditional stent-assisted coiling—The microcatheter is advanced into the parent vessel distal to the aneurysm neck, and the stent is deployed. A microwire is advanced through the stent tines into the aneurysm, and the microcatheter is advanced into it. Coils are then deployed within the aneurysm.
Control injections are performed at the working angles to ensure aneurysm obliteration, stent patency, and adequate wall apposition.
Control injections are performed with full views of the intracranial vasculature to assess for delayed capillary filling, distal emboli, or vessel extravasation.

Device Selection

In our practice, the following devices are routinely used for stent-assisted coiling:

6 or 8F sheath.
6F guide catheter (Envoy XB, Codman Neuro; Benchmark, Penumbra; or 8F guide catheter, Neuron MAX, Penumbra).
Intermediate catheter (Distal Access Catheter [DAC], Stryker Neurovascular).
Stent and microcatheter selection ( Table 25.1 ).
Microwire (Synchro 2, Synchro 10, Stryker).
Coils.

**Table 25.1** Stent and microcatheter selection
Stent	Manufacturer	Design	Diameter	Lengths	Microcatheter inner diameter (ID)
Neuroform	Stryker	Open	2.5–4.0 mm	10–30 mm	0.027 inch
Neuroform Atlas	Stryker	Hybrid	3.0–4.5 mm	15–30 mm	0.017 inch
Low-Profile Visualized Intraluminal Support Junior (LVIS Jr)	MicroVention	Closed	2.5–3.5 mm	13–34 mm	0.017 inch
Low-Profile Visualized Intraluminal Support (LVIS)	MicroVention	Closed	3.5–5.5 mm	12–33 mm	0.021 inch

Pearls

Confirmation of platelet inhibition has become standard at many centers. Lack of adequate platelet inhibition has been associated with an increased frequency of thromboembolic complications.
In-stent thrombosis can be managed with aspiration or glycoprotein IIa/IIIb inhibitor infusion. We do not recommend mechanical thrombectomy because it can cause migration or movement of the stent.
When using the jailing technique, the deployed stent can serve as an anchor to help reduce redundancy in the coiling catheter.
When using the jailing technique, the deployment of one or two loops of coil within the aneurysm helps stabilize the microcatheter within the aneurysm during deployment of the stent.

References

[1] Higashida RT, Smith W, Gress D, et al. Intravascular stent and endovascular coil placement for a ruptured fusiform aneurysm of the basilar artery. Case report and review of the literature. J Neurosurg. 1997;87(6):944–949. [2] Mericle RA, Lanzino G, Wakhloo AK, Guterman LR, Hopkins LN. Stenting and secondary coiling of intracranial internal carotid artery aneurysm: Technical case report. Neurosurgery. 1998;43(5):1229–1234. [3] Hetts SW, Turk A, English JD, et al. Matrix and platinum science trial investigators. Stent-assisted coiling versus coiling alone in unruptured intracranial aneurysms in the matrix and platinum science trial: Safety, efficacy, and mid-term outcomes. AJNR Am J Neuroradiol. 2014;35(4):698–705. [4] Feng MT, Wen Wl, Feng ZZ, et al. Endovascular embolization of intracranial aneurysms: To use stent(s) or not? Systemic review and meta-analysis. World Neurosurg. 2016;93:271–278. [5] Bodily KD, Cloft HJ, Anzino G, et al. Stent-assisted coiling in acutely ruptured intracranial aneurysms: A qualitative, systemic review of the literature. AJNR Am J Neuroradiol. 2011;32(7):1232–1236. [6] Linzey JR, Griauzde J, Guan Z, et al. Stent-assisted coiling of cerebrovascular aneurysms: Experience at a large tertiary center with a focus on predictors of recurrence. J Neurointerv Surg. 2017;9(11):1081–1085.

Case Overview: CASE 25.1 Superior Hypophyseal Artery Aneurysm: Stent-Assisted Coiling Jailing Technique (Neuroform Atlas Stent)

A 48-year-old female presented to the emergency department with acute double and blurry vision. Neurological examination was normal. She has a past medical history of hypertension, diabetes, and familial history of subarachnoid hemorrhage.
Computed tomography (CT) was normal.
CT angiography demonstrated a left superior hypophyseal artery (SHA) aneurysm.

**Fig 25.1a** CT angiography showing left wide-necked SHA aneurysm.

**Fig 25.1b** Artist’s illustration of stent-assisted coiling of left SHA aneurysm (Jailing technique).

**Fig 25.1c** Coiling microcatheter in the aneurysm.

**Fig 25.1d** Stent microcatheter in the internal carotid artery.

**Fig 25.1e** Stent deployment (red arrows) coiling microcatheter jailed (blue arrow).

**Fig 25.1h** Complete aneurysm obliteration.

**Video 25.1** Stent-assisted coiling of an ICA aneurysm

Procedure

The patient underwent elective endovascular stent-assisted coiling of left SHA aneurysm. Patient was given aspirin 325 mg daily and clopidogrel 75 mg for 7 days prior to the intervention. The procedure was performed under general anesthesia and through a right femoral artery approach. 5,000 units of heparin were given to obtain an activated clotting time of more than 250.

Device List

Standard femoral artery access.
- Micropuncture kit.
- 6F sheath.
0.035-inch Glidewire.
Envoy XB DA guide catheter (Codman).
0.017-inch Excelsior XT-17 microcatheter (Stryker).
0.0165-inch Excelsior SL-10 microcatheter (Stryker).
0.014-inch Synchro 2 microwire (Stryker).
4 x 21 mm Neuroform Atlas stent (Stryker).
Multiple intracranial coils
6F AngioSeal percutaneous closure device.

Device Explanation

This unruptured enlarging aneurysm presented with cranial nerve neuropathy and diplopia, the aneurysm’s neck is wide and endovascular coiling requires balloon- or stent-assisted tech-niques. A 6F catheter was navigated into the distal petrous internal carotid artery (ICA) segment. Jailing technique was used. Under road and magnification, a coiling microcatheter was advanced into the aneurysm, followed by a stenting microcatheter advanced into the ICA bifurcation. Few coil loops were deployed in the aneurysm. The stent is advanced and deployed across the aneurysm neck. The rest of the coils were inserted until the aneurysm was completely obliterated. Jailing technique permits microcatheter stabilization during coiling. The size of this patient’s intracranial ICA was 3.5 mm; therefore, a relatively small stent (Neuroform Atlas) was used.

Tips, Tricks & Complication Avoidance

In the last decade, several laser-cut or braided stents have been introduced such as Solitaire, Neuroform, Neuroform Atlas, Enterprise, Enterprise2, Leo, Leo baby, low profile visualized intraluminal support (LVIS), LVIS Jr, and Acclino stent. Neuroform Atlas (Stryker) stent is the successor to the Neuroform stent as the first approved for intracranial aneurysm treatment. It is intended for the treatment of aneurysm on a small parent vessel ranging from 2.5 to 4 mm. It can be delivered through standard coiling microcatheters down to an inner diameter of 0.0165-inch (Excelsior SL10 [Stryker], Headway DUO [Microvention]).
European early multicenter postmarketing registry showed Neuroform Atlas stent placement was possible and accurately (because of minimal to no foreshortening) in all cases. There were no permanent morbidity or mortality with a periprocedural rate of 2.7% (one case) (J Neurointerv Surg. 2018).
Be familiar with the stent and its multiple markers to achieve an accurate deployment.
Multiple sizes of the stent include 3x (15, 21, 24) mm, 4x (21, 24) mm, 4.5x (21, 30) mm.

Case Overview: CASE 25.2 Anterior Communicating Artery Aneurysm: Stent-Assisted Coiling (LVIS Jr Stent)

A 77-year-old male presented to the emergency department with transient altered mental status. Neurologically, the patient was awake, alert, oriented to person only. No motor or sensory deficits. No focal deficits. He had a past medical history of hypertension, atrial fibrillation, chronic leukemia, coronary artery diseases, and heart failure. The patient is currently taking aspirin and warfarin. Further work-up revealed hyponatremia (Na 130) was the cause of his neurological symptoms.
Computed tomography (CT) was normal.
CT angiography demonstrated an anterior communicating artery (ACoA) aneurysm.

**Fig 25.2a** 3D CT angiogram demonstrating the ACoA aneurysm.

**Fig 25.2b** Artist’s illustration of stent-assisted coiling of ACoA aneurysm with LVIS stent.

**Fig 25.2d** Stent-delivering microcatheter in an A2 artery.

**Fig 25.2e** Coiling microcatheter in the aneurysm.

**Fig 25.2f** Stent (arrows) positioning prior to deployment.

**Fig 25.2g** Stent deployment (red arrows) and jailing of coiling microcatheter (white arrow).

**Fig 25.2i** Complete aneurysm obliteration.

**Video 25.2** Stent-assisted coiling of an ACoA aneurysm

Procedure

The patient underwent elective endovascular stent-assisted coiling of ACoA aneurysm. Patient was started on 75 mg clopidogrel 7 days prior to his procedure and continued with his anticoagulation. No aspirin was given. The procedure was performed under conscious sedation and through a right femoral artery approach. 5,000 units of heparin were given to obtain an activated clotting time of more than 250.

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25 Stent-Assisted Coiling