Endovascular assisted embolization Introduction The endovascular coil embolization

Endovascular ostium bypass technique using the low-profile stents in the coil embolization ofbroad-ostium complex cerebral aneurysmsAbstractPurpose I present a technique for bypassing the broad aneurysm ostium by the Low-profile stents.

Material and methods The endovascular coil embolization of a ruptured anterior communicating arteryaneurysm with complex and broad-ostium configuration was done by ostium bypass technique using alow-profile stent.Results The patient underwent stent assisted coil embolization as scheduled, without any proceduralsignifcant complications.Conclusion The low -profile stent, in this case LVIS® Jr, can be used in broad-ostium complexaneurysms endovascular embolization.Keywords Complex aneurysm; low -profile stent; LVIS; low-profile visualized intraluminal support;stent assisted embolizationIntroductionThe endovascular coil embolization of cerebral aneurysms with complex or broad-ostium configurationshas a high technical failure risk due to the acute angle between the aneurysm and the parent artery, thetortuous structure of parent artery, and the resistance of the aneurysm ostium against placing a stent 1.Since stents make a mechanical cage to prohibit a coil sagging into the parent artery, stent-supportedcoiling is progressively used for the endovascular embolization of broad-ostium aneurysms 2–5. Here, Ihave described an ostium bypass technique using the Low-profile stent, in this particular case, Low -profile Visualized Intraluminal Support (LVIS® Jr; MicroVention Inc., Aliso Viejo, CA, USA) device. Itprovides an access to the distal part of the aneurysm ostium in the stent-supported endovascular coilembolization of broad-ostium complex aneurysms in which conventional techniques have failed, or inmore complex and complicated cases.

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Material and methodsA 54-year-old male was admitted to the intensive care unit for a subarachnoid hemorrhage with aGlasgow Coma Scale score of 15. The diagnostic angiography showed a complex, ruptured, broad-ostiumanterior communicating artery aneurysm (Fig. 2). The aneurysm had a complex morphologyincorporating more than one daughter vessel, and it showed an acute angle with the daughter artery. Theostium diameter was 7 mm, and the dome-to-ostium ratio was less than 2. Treatment using a single stent-supported coiling procedure was chosen by a team of neurosurgeons and an interventional radiologistafter considering the aneurysm morphology, anatomy of the arteries, and the patient’s medical condition.

The endovascular procedure was performed by using a femoral approach, with the patient undergeneral anesthesia. 70 IU / kg intravenous heparin bolus dose and following slow heparin infusion inorder to maintain an activated clotting time ? 2-fold of baseline value was started immediately afterplacement of the femoral introducer sheath. On account of preveting rehemorrhage in case of technicalfailure, 450 mg clopidogrel and 300 mg aspirin with 20 mg Abcixamab hold beside the patient and startedimmediately after successful partial unsheathing the stent. Antiplatelet activity was evaluated beforefinishing the infusion dose of Abcixamab in window time that had been continued for 12 hours. Thepatient had a good response to clopidogrel (platelet aggregation inhibition ; 40%). In inadequate responseto clopidogrel, there was a plan for switching to prasugrel. A 7 Fr peripheral guiding sheath(Destination®; Terumo Interventional Systems, Leuven, Belgium) was placed in the left internal carotidartery. Two microcatheters, one for stent delivery and the other for coil delivery (Headway 17 Advanced;MicroVention Inc.

), were loaded in 6 Fr intracranial support catheters (NavienTM; Covidien VascularTherapies, Mansfield, MA, USA). The aneurysm ostium bypass was attempted using a Headway 17microcatheter and Traxcess 0.014″ guidewire (MicroVention Inc.) with different tip angles.

Themicrocatheter with the microguidewire was gently pushed towards the aneurysm along the inner wall tomake a loop inside and to reach the outflow into the main artery located distal to the aneurysm. Whengentle pulling/straightening of the intra-aneurysmal looped stent catheter failed and the distal segment ofthe catheter was prone to falling back into the aneurysm sac, endovascular broad ostium bypass techniqueby the low profile stent (LVIS® Jr device )is used. In this technique, the stent is advanced inside themicrocatheter and placed more distal than optimal to the aneurysm, and it is partially deployed forstabilization. Next, the stent microcatheter is pulled back gently in order to get rid of the loosen part andto access the outflow of the aneurysm and main artery proximal to the aneurysm. Since the stent ispartially disengaged at distal part, it cannot move as its loop within the aneurysm is adjusted by pullingslowly.

The stent should not be fully deployed until efficient coil packing is made inside the aneurysm inorder to prevent the risk of stent slipping towards the aneurysm (Fig. 1). The postprocedural angiographicimages showed a Raymond-Roy class 1 complete occlusion of the aneurysm (Fig. 2).ResultsThe endovascular procedure was performed by using a femoral approach. The microcatheter with themicroguidewire was gently pushed towards the aneurysm along the inner wall to make a loop inside andto reach the outflow into the main artery located distal to the aneurysm.

When gentle pulling/straighteningof the intra-aneurysmal looped stent catheter failed and the distal segment of the catheter was prone tofalling back into the aneurysm sac, the guidewire was removed and the LVIS® Jr device was advancedinside the microcatheter. It was placed distal to the aneurysm in the opposite daughter artery. In order tostabilize the lowest profile stent catheter, the stent placed distal to the aneurysm was partially deployed.The stent microcatheter was then pulled very gently to straighten the loose part within the aneurysmcavity. I performed the full release of the stents when an efficient coil packing formed in the aneurysmsac (Fig. 1).

The patient underwent stent assisted coil embolization as scheduled, without any proceduralsignifcant complications.DiscussionPerforming endovascular treatment of broad-ostium aneurysms while preserving parent artery is achallenging procedure. Although various advanced endovascular techniques have been suggested toovercome challenges, there is still high risk of failure for the primary bypass of the complex aneurysmostium using any kind of microguidewire or microcatheter 6–8.

Furthermore, in case of broad ostium, negotiation of the aneurysm neck to pass across the acute anglebetween the inflow and outflow of the aneurysm, in order to place a balloon or stent-delivery catheteracross it, is one of the main challenges leading to technical failures 1. Blood stream directed from theinflow into the aneurysm, particularly in case of acute angle, could result outflow catheterization difficult;frequently the microwire and following microcatheter should be looped in the dome to find the outflow ofthe parent vessle. For deploying a stent across the ostium of a wide neck aneurysm, the looped cathetermust be flatten. Straightening by pulling back of the catheter will often end up sag of the microcathetertip into the aneurysm dome from distal vessel. it occurs due to lack of anchor within the distal part of theparent artery.Double-wire and sheeping techniques, were reported as alternative methodes previously by Nakahara etal. 9 and Chapot et al. 10, respectively.

But in both techniques need to pass aneurysm and challengewith friction between the parent arterial wall and stent catheter or the balloon. Also it could beimpossible in broad ostium aneurysm, complex vascular anatomy, or parent artery tortuosity to accessoutflow by any types of microcatheter or microwire.Cekirge, et al. 11 and Wolfe et al. 12described a balloon-assisted bypass and a balloon bouncetechniques to bypass a broad ostium aneurysms, respectively. However, these techniques need additionaldevice(balloon catheter) and have potential risk of lossing access at the time of exchanging for the stentand unexpected rupture due to over-inflation.

Ito, et al. 13 defined temporary caging technique for catheter navigation in patients with intracranialbroad ostium aneurysms. Although, in this technique no risky manipulations within an aneurysm happens,but it is not always possible to coiling a wide neck aneurysm without sagging to the parent artery, and itmay be troublesome to pass out the stent or balloon catheter through the prolapsed coils to reach outflowin the parent artery.By the rapid 14or gently15 pull-back techniqes, the microcatheter can be placed distal enough in theparent artery and straightened across the aneurysm neck with rapid or gently pulling the loopedmicrocatheter; however, this works sometimes.

Another method for overcoming to prolaps of the distal tip of the microcatheter to aneurysmal dome, isthe sea anchor technique by using a long soft coil passed across the acute angle between the inflow andoutflow tracts of a aneurysm, results in distal purchase between the coil and the distal vesselendothelium, and allow the catheter to be straightened across the aneurysm neck when traction is appliedto the microcatheter in an attempt to straighten it across the aneurysm neck.16However, using an embolization device ( a long soft coil) as an anchor has a potential thromboembolicrisk in the distal part of the parent vessel.In such settings, I suggest that the low -profile stents- supported endovascular ostium bypass technique isvery useful for treating the aneurysms. Advancing the low -profile stents (LVIS® Jr device) within thelooped microcatheter inside the aneurysm to provide a distal access and removal of loose part when thestent is semi-deployed are the important stages of this technique. In the first step, placing the intracranialsupport catheter as high as possible before putting forward the stent inside the microcatheter couldfacilitate this step. In the second step, semi-deploying the stent would be strong enough to stabilize it inthe vessel, which is imperative.

I recommend the LVIS® Jr device, because it is the lowest profile deliverysystem, and its good compatibility ensures superior navigation and safety. Also partly similir methodpreviously reported by Fargen, et al.18 but to the best of my knowledge, this is the first endovascularostium bypass technique using the low-profile stents in the coil embolization of broad-ostium complexcerebral aneurysms.

The technique depicted above (Fig. 1), uses low profile stents that is less traumaticin the aneurysm sac compare to conventional intracranial stents therfore have a less potentialintraoperative rupture risk while performing the technique, particularly in patients with recently rupturedaneurysm, as in our case. The LVIS® Jr stent-supported ostium bypass technique can also be used inbroad-ostium aneurysms located on the middle cerebral artery bifurcation and the basilar artery tipConclusionLow-profile stent-supported ( LVIS® Jr ) endovascular broad ostium bypass is a simple and safetechnique, which allows the location of stent across the wide aneurysm neck, making endovasculartreatment of complex aneurysms possible.Compliance with ethical standardsEthical statement Informed consent for the treatment and images used in the analysis were obtainedfrom the patient and the legal representative of him. Institutional review board approval was not obtainedbecause it is not required by the institution for this type of technical note.Conflict of interest The author declares that he has no confict of interest.Acknowledgements I have no acknowledgement.

Funding I have received no grants related to this technical note.Figure LegendsFigure 1. Schematic diagrams of the Low-profile Visualized Intraluminal Support (LVIS® Jr) stent-supported endovascular ostium bypass technique used in the coil embolization of broad-ostium complexcerebral aneurysms. (a) Illustration of broad-ostium complex aneurysm. (b) Catheterization of theproximal parent artery.

(c) For bypassing the aneurysm ostium, the LVIS® Jr stent is partially deployed ina higher than optimal spot. (d) The stent microcatheter is pulled very slowly to remove the slackenedportion within the aneurysm sac. Because the stent is partially deployed distally, it does not move whileits loop inside the aneurysm is straightened by the gentle pulling of the stent catheter, bringing it to theoptimal place.

(e) Because the large and complex ostium geometry creates a high risk for thedisplacement of the stents into the aneurysm sac, first partially coiling, (f) then optimizing the distalposition of stent, and (g) finally, the full deployment of the stents until a sufficient coil mass is formed inthe aneurysm sac should be performed. (h) In the end, the jailed microcatheter in the aneurysm sac forcoil delivery should be removed. (i) Illustration of the final appearance. (Special thanks to ElmiraJalalidizaji for providing the technical support for the illustrations.

)Figure 2. (a) Preprocedural three-dimensional rotational angiography with volume rendering image of a54-year-old male patient with a ruptured complex broad-ostium anterior communicating aneurysm. (b)Preprocedural digital subtraction angiographic image in the anterior posterior projection showing an 8-mm broad-ostium aneurysm located on the anterior communicating artery. The ostium of the aneurysmincorporates both daughter artery origins.

(c) Postprocedural subtracted angiographic image showing aRaymond-Roy class 1 complete occlusion of the aneurysm sac.


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