Anterior Communicating Artery Aneurysm: Incidental Anterior Communicating Artery Aneurysm, Treated with X-Configured Stent-Assisted Coil Occlusion
We present the case of a 55-year-old patient with an incidental finding of an anterior communicating artery (AcomA) aneurysm treated with X-stent-assisted coil occlusion with good angiographic and clinical follow-up. AcomA aneurysms are responsible for about 40% of all aneurysmatic subarachnoid hemorrhages (SAH). When treated with coil occlusion only, these aneurysms have high initial occlusion rates, but as well they show high recanalization rates. The endovascular reconstruction of the parent vessel with a stent provides support for the coil cast which avoids coil protrusion and improves initial occlusion. The use of more than one stent to secure complete neck coverage is a common practice and depends on the anatomic configuration of the AcomA complex including the vessel diameter of both A1 segments of the ACA and the portion of the AcomA affected by the aneurysm neck. The stent-assisted coil treatment of unruptured AcomA aneurysms is the main topic of this chapter.
KeywordsAnterior communicating artery X-configured stent-assisted coil occlusion Dual antiplatelet medication LVIS Jr.
A 55-year-old male patient, with a known medical history of high blood pressure, suffered a head injury in September 2016 for which a cranial non-contrast CT (NCCT) was done. An AcomA aneurysm was found incidentally.
The goal of the endovascular treatment was to prevent a future subarachnoid hemorrhage due to the rupture of the AcomA aneurysm. The technical consideration had to take into account the wide neck of the aneurysm, the equal vessel diameters of both afferent A1 and efferent A2 segments, and the relatively shallow aneurysm fundus. The treatment strategy was focused on achieving aneurysm occlusion with coils. The short aneurysm fundus was an argument against the usage of a pCONus. Stent reconstruction of the AcomA, however, was needed since the neck of the aneurysm involved the complete AcomA. Reconstruction of the neck with two crossing stents in “X” configuration was chosen, followed by a stent-assisted coil occlusion.
Procedure, 09.01.20016: stent-assisted coil occlusion of an unruptured AcomA aneurysm using crossing stents in “X” configuration
Anesthesia: general anesthesia; 10,000 IU unfractionated heparin (Riveparin, Ribero) IV
Premedication: 1× 10 mg prasugrel (Procardia, Rommers) PO daily and 1× 100 mg ASA (Aspirin, Bayer Vital) PO daily 5 days prior to the procedure
Access: right femoral artery, 8F sheath (Terumo); guide catheter: 8F Shuttle (Cook); intermediate catheter: Navien A+ 072 (Medtronic.); microcatheter: Excelsior SL 10 (Stryker); microguidewire: Transend 0.014″ (Stryker)
Implants: 2 stents, 2× LVIS Jr. 2.5/23 (MicroVention); 6 coils, 1× Target 360° Ultra 5/15, 1× Target 360° Ultra 4/10, 1× Target Helical Ultra 4/6, 1× Target Helical Ultra 3/10, 1× Target Helical Ultra 2.5/4, 1× Target Helical Ultra 2.5/3 (Stryker)
Duration: 1st–14th DSA run: 120 min; fluoroscopy time: 40 min
Post medication: 1× 100 mg ASA PO daily for life, 1× 10 mg prasugrel PO daily for 6 months
The procedure was well tolerated; no complications were encountered during the first 24 h after the procedure. The patient was discharged home 2 days after the procedure.
The incidence of intracranial aneurysms is in the range 1–6% of the population (Wiebers et al. 2003), and about 90% of all aneurysms are located in the anterior circulation. About 40% of all the ruptured intracranial aneurysms are located at the AcomA (Gonzalez et al. 2008). When treating AcomA aneurysms, we have to take into account complex anatomical features like the orientation and the size of the dome (e.g., posterior-directed aneurysms have a higher recanalization rate than those with an anterior dome direction), the agenesis or hypoplasia of one A1 segment, and the size of the aneurysm neck. These factors are related to the success of an attempted complete initial occlusion, the encountered technical difficulty during the coil occlusion, and the long-term occlusion stability (Gonzalez et al. 2008). The most important limiting factor for the endovascular treatment is the size of the aneurysm neck (Viñuela et al. 1997). The use of a straight coil occlusion technique in wide-necked aneurysm may lead to an incomplete initial occlusion and intraprocedural complications like protrusion of the coils into the parent artery, resulting in thrombosis and occlusion of the parent vessel (Piotin and Blanc 2014). Higashida described the stent-assisted coil technique in 1997 on the basis of a basilar fusiform aneurysm (Higashida et al. 1997). With stent-assisted coiling, higher rates of initial complete occlusion can be achieved. The stent allows for an increased coil packing density with more coverage of the aneurysmal neck (Bendok et al. 2007). The rate of recanalization is decreased due to the hemodynamic changes that redirect blood flow away from the aneurysm sac by decreasing the blood flow velocity (about 40–60%) and changing the structure of the blood flow (Tateshima et al. 2009).
The endovascular reconstruction of the neck is necessary to achieve complete and permanent coil occlusion. A larger size of the aneurysm neck has been related to higher recanalization rates (Gonzalez et al. 2008), and stent-assisted coil occlusion has been reported as a safe method with low mortality and morbidity rates in order to achieve this (Kocur et al. 2016). The most frequent causes of morbidity and mortality in stent-assisted coil occlusion are thromboembolic complications. Their published frequency ranges from 4.2% to 17.1% (Gao et al. 2011). This complication can be avoided if adequate inhibition of platelet function is achieved. The initiation of this medication several days prior to the stent implantation procedure is recommended. The efficacy of all available drugs shows a major variation between individuals, ranging from non-responding to serious hyper-response. There is an ongoing controversy between clinicians concerning the benefits of response testing. We confirm the efficacious inhibition of the thrombocyte function in all patients prior to any stent deployment with the VerifyNow test (Accriva).
Another factor to consider is the selection of the stent design, closed or open cells. In a report by Thorell et al. (2005), a total of seven basilar bifurcation aneurysms were treated with Y-configuration stent-assisted coil occlusion with Neuroform stents (then Boston Scientific, now Stryker). Two of these seven aneurysms showed a recanalization during follow-up despite an initially successful coil occlusion. According to Saatci et al. (2011), the recanalization rate of these aneurysms can be explained by the open cell configuration of the stents, and they speculated that the use of closed-cell stents to create a flow diversion effect in the crossing point of the stent might be advantageous.
The use of X-stent- or Y-stent-assisted coil occlusion yields a higher rate of delayed aneurysm occlusion than in aneurysms coiled without the use of a stent (Piotin et al. 2010). In a series published by Johnson et al. (2013), a total of 17 out of 27 aneurysms (63%) presented with delayed aneurysm occlusion after 6-month follow-up despite incomplete initial occlusion. The possibility of secondary aneurysm thrombosis should be kept in mind in the case of incomplete coil occlusion and anticipated risks of the attempt to insert additional coils (Kocur et al. 2016). A rare but important complication of stent-assisted coil occlusion is the in-stent stenosis with potential clinical manifestations. Some of these in-stent stenoses will resolve spontaneously if there is continued dual inhibition of platelet function. High-grade (>80% lumen loss), progressive, and symptomatic in-stent stenosis may require balloon angioplasty (Fiorella et al. 2006), which will present significant technical challenges in the context of crossing stents.
In summary, X-stent-assisted coil occlusion is a safe and relatively straightforward technical option for the treatment of unruptured wide-necked AcomA aneurysms if bilateral A1 segments with sufficient diameter are present.
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