Endovascular ostium bypass technique using the low-profile stents in the coil embolization of broad-ostium complex cerebral aneurysms Abstract Purpose I present a technique for bypassing the broad aneurysm ostium by the Low-profile stents

April 11, 2019 Critical Thinking

Endovascular ostium bypass technique using the low-profile stents in the coil embolization of
broad-ostium complex cerebral aneurysms

Abstract
Purpose 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 artery
aneurysm with complex and broad-ostium configuration was done by ostium bypass technique using a
low-profile stent.
Results The patient underwent stent assisted coil embolization as scheduled, without any procedural
signifcant complications.
Conclusion The low -profile stent, in this case LVIS® Jr, can be used in broad-ostium complex
aneurysms endovascular embolization.

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Keywords Complex aneurysm; low -profile stent; LVIS; low-profile visualized intraluminal support;
stent assisted embolization

Introduction
The endovascular coil embolization of cerebral aneurysms with complex or broad-ostium configurations
has a high technical failure risk due to the acute angle between the aneurysm and the parent artery, the
tortuous 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-supported
coiling is progressively used for the endovascular embolization of broad-ostium aneurysms 2–5. Here, I
have 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. It
provides an access to the distal part of the aneurysm ostium in the stent-supported endovascular coil
embolization of broad-ostium complex aneurysms in which conventional techniques have failed, or in
more complex and complicated cases.

Material and methods
A 54-year-old male was admitted to the intensive care unit for a subarachnoid hemorrhage with a
Glasgow Coma Scale score of 15. The diagnostic angiography showed a complex, ruptured, broad-ostium
anterior communicating artery aneurysm (Fig. 2). The aneurysm had a complex morphology
incorporating more than one daughter vessel, and it showed an acute angle with the daughter artery. The

ostium 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 radiologist

after 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 under
general anesthesia. 70 IU / kg intravenous heparin bolus dose and following slow heparin infusion in
order to maintain an activated clotting time ? 2-fold of baseline value was started immediately after
placement of the femoral introducer sheath. On account of preveting rehemorrhage in case of technical
failure, 450 mg clopidogrel and 300 mg aspirin with 20 mg Abcixamab hold beside the patient and started
immediately after successful partial unsheathing the stent. Antiplatelet activity was evaluated before
finishing the infusion dose of Abcixamab in window time that had been continued for 12 hours. The
patient had a good response to clopidogrel (platelet aggregation inhibition ; 40%). In inadequate response
to 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 carotid
artery. 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 Vascular
Therapies, Mansfield, MA, USA). The aneurysm ostium bypass was attempted using a Headway 17
microcatheter and Traxcess 0.014″ guidewire (MicroVention Inc.) with different tip angles. The
microcatheter with the microguidewire was gently pushed towards the aneurysm along the inner wall to
make a loop inside and to reach the outflow into the main artery located distal to the aneurysm. When
gentle pulling/straightening of the intra-aneurysmal looped stent catheter failed and the distal segment of
the catheter was prone to falling back into the aneurysm sac, endovascular broad ostium bypass technique
by the low profile stent (LVIS® Jr device )is used. In this technique, the stent is advanced inside the
microcatheter and placed more distal than optimal to the aneurysm, and it is partially deployed for
stabilization. Next, the stent microcatheter is pulled back gently in order to get rid of the loosen part and
to access the outflow of the aneurysm and main artery proximal to the aneurysm. Since the stent is
partially disengaged at distal part, it cannot move as its loop within the aneurysm is adjusted by pulling
slowly. The stent should not be fully deployed until efficient coil packing is made inside the aneurysm in
order to prevent the risk of stent slipping towards the aneurysm (Fig. 1). The postprocedural angiographic
images showed a Raymond-Roy class 1 complete occlusion of the aneurysm (Fig. 2).

Results
The endovascular procedure was performed by using a femoral approach. The microcatheter with the
microguidewire was gently pushed towards the aneurysm along the inner wall to make a loop inside and
to reach the outflow into the main artery located distal to the aneurysm. When gentle pulling/straightening
of the intra-aneurysmal looped stent catheter failed and the distal segment of the catheter was prone to
falling back into the aneurysm sac, the guidewire was removed and the LVIS® Jr device was advanced
inside the microcatheter. It was placed distal to the aneurysm in the opposite daughter artery. In order to
stabilize 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 aneurysm
cavity. I performed the full release of the stents when an efficient coil packing formed in the aneurysm
sac (Fig. 1). The patient underwent stent assisted coil embolization as scheduled, without any procedural
signifcant complications.
Discussion
Performing endovascular treatment of broad-ostium aneurysms while preserving parent artery is a

challenging procedure. Although various advanced endovascular techniques have been suggested to
overcome challenges, there is still high risk of failure for the primary bypass of the complex aneurysm
ostium 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 angle
between the inflow and outflow of the aneurysm, in order to place a balloon or stent-delivery catheter
across it, is one of the main challenges leading to technical failures 1. Blood stream directed from the
inflow 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 of
the parent vessle. For deploying a stent across the ostium of a wide neck aneurysm, the looped catheter
must be flatten. Straightening by pulling back of the catheter will often end up sag of the microcatheter
tip into the aneurysm dome from distal vessel. it occurs due to lack of anchor within the distal part of the
parent artery.
Double-wire and sheeping techniques, were reported as alternative methodes previously by Nakahara et
al. 9 and Chapot et al. 10, respectively. But in both techniques need to pass aneurysm and challenge
with friction between the parent arterial wall and stent catheter or the balloon. Also it could be
impossible in broad ostium aneurysm, complex vascular anatomy, or parent artery tortuosity to access
outflow by any types of microcatheter or microwire.
Cekirge, et al. 11 and Wolfe et al. 12described a balloon-assisted bypass and a balloon bounce
techniques to bypass a broad ostium aneurysms, respectively. However, these techniques need additional
device(balloon catheter) and have potential risk of lossing access at the time of exchanging for the stent
and unexpected rupture due to over-inflation.
Ito, et al. 13 defined temporary caging technique for catheter navigation in patients with intracranial
broad 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 it
may be troublesome to pass out the stent or balloon catheter through the prolapsed coils to reach outflow
in the parent artery.
By the rapid 14or gently15 pull-back techniqes, the microcatheter can be placed distal enough in the
parent artery and straightened across the aneurysm neck with rapid or gently pulling the looped
microcatheter; however, this works sometimes.
Another method for overcoming to prolaps of the distal tip of the microcatheter to aneurysmal dome, is
the sea anchor technique by using a long soft coil passed across the acute angle between the inflow and

outflow tracts of a aneurysm, results in distal purchase between the coil and the distal vessel
endothelium, and allow the catheter to be straightened across the aneurysm neck when traction is applied
to the microcatheter in an attempt to straighten it across the aneurysm neck.16
However, using an embolization device ( a long soft coil) as an anchor has a potential thromboembolic
risk in the distal part of the parent vessel.
In such settings, I suggest that the low -profile stents- supported endovascular ostium bypass technique is
very useful for treating the aneurysms. Advancing the low -profile stents (LVIS® Jr device) within the
looped microcatheter inside the aneurysm to provide a distal access and removal of loose part when the
stent is semi-deployed are the important stages of this technique. In the first step, placing the intracranial
support catheter as high as possible before putting forward the stent inside the microcatheter could
facilitate this step. In the second step, semi-deploying the stent would be strong enough to stabilize it in
the vessel, which is imperative. I recommend the LVIS® Jr device, because it is the lowest profile delivery
system, and its good compatibility ensures superior navigation and safety. Also partly similir method
previously reported by Fargen, et al.18 but to the best of my knowledge, this is the first endovascular
ostium bypass technique using the low-profile stents in the coil embolization of broad-ostium complex
cerebral aneurysms. The technique depicted above (Fig. 1), uses low profile stents that is less traumatic
in the aneurysm sac compare to conventional intracranial stents therfore have a less potential
intraoperative rupture risk while performing the technique, particularly in patients with recently ruptured
aneurysm, as in our case. The LVIS® Jr stent-supported ostium bypass technique can also be used in
broad-ostium aneurysms located on the middle cerebral artery bifurcation and the basilar artery tip

Conclusion
Low-profile stent-supported ( LVIS® Jr ) endovascular broad ostium bypass is a simple and safe
technique, which allows the location of stent across the wide aneurysm neck, making endovascular
treatment of complex aneurysms possible.

Compliance with ethical standards
Ethical statement Informed consent for the treatment and images used in the analysis were obtained

from the patient and the legal representative of him. Institutional review board approval was not obtained
because 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 Legends

Figure 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 complex

cerebral aneurysms. (a) Illustration of broad-ostium complex aneurysm. (b) Catheterization of the
proximal parent artery. (c) For bypassing the aneurysm ostium, the LVIS® Jr stent is partially deployed in
a higher than optimal spot. (d) The stent microcatheter is pulled very slowly to remove the slackened
portion within the aneurysm sac. Because the stent is partially deployed distally, it does not move while
its loop inside the aneurysm is straightened by the gentle pulling of the stent catheter, bringing it to the
optimal place. (e) Because the large and complex ostium geometry creates a high risk for the
displacement of the stents into the aneurysm sac, first partially coiling, (f) then optimizing the distal
position of stent, and (g) finally, the full deployment of the stents until a sufficient coil mass is formed in
the aneurysm sac should be performed. (h) In the end, the jailed microcatheter in the aneurysm sac for
coil delivery should be removed. (i) Illustration of the final appearance. (Special thanks to Elmira
Jalalidizaji for providing the technical support for the illustrations.)
Figure 2. (a) Preprocedural three-dimensional rotational angiography with volume rendering image of a
54-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 aneurysm
incorporates both daughter artery origins. (c) Postprocedural subtracted angiographic image showing a
Raymond-Roy class 1 complete occlusion of the aneurysm sac.

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