Keywords
Y stent - wide - aneurysm - bifurcation
Introduction
Endovascular therapy is an established means of treatment for ruptured wide-necked
bifurcation aneurysms since the advent of International Subarachnoid Aneurysm Trial
and Barroe Ruptured Aneurysm Trial trials. Newer techniques have been evolving in
this field since then like balloon remodeling, stent-assisted coiling, bifurcation
devices, flow diverters, and intrasaccular flow disrupters (WEB). However, aneurysms
with wide necks are still challenging lesions for treatment by endovascular means
and have technical limitations. Balloon-assisted coiling may be challenging in cases
of very wide-necked aneurysms with complex anatomy.[1] Flow diversion is a revolution in endovascular treatment, but the destiny of the
covered side branches in case of bifurcation aneurysms is concerning.[2]
[3] Intrasaccular flow disrupters have evolved as the new modality of treatment in such
wide-necked aneurysms of the bifurcation, but the technical expertise and mechanisms
are still in evolution and long-term angiographic occlusion rates are still lower
than stent-assisted coiling.[4]
[5] Last but not the least, PulseRider (Cerenovus, New Brunswick, New Jersey, United
States) and pCONus aneurysm implant (phenox, Bochum, Germany) devices appear to be
promising new strategies to treat wide-necked lesions, though further researches are
required to confirm the efficacy of these devices. Newer devices such as eClips (Evasc
Neurovascular Enterprise ULC), honeycomb microporous covered stent, and Comaneci (Rapid
medical) devises have arrived for wide-necked bifurcation aneurysm but these are still
under investigation and require further research to prove their efficacy.
The use of two stents in a Y configuration has been first described by Chow et al.[5] Its safety and efficacy have made it one of the safest alternatives to clip reconstruction.
It is done by placing two stents in a Y configuration in the parent artery to create
a new bifurcation point for the wide-necked bifurcation aneurysm and it prevents coil
protrusion and provides a scaffold. There have been variations to this Y stenting
in the form of T stenting in which the stents are placed in the form of a T in the
parent artery that provides the same help that is prevention of coil protrusion and
scaffolding.
There has been wide variation in the nature of implants taken for Y stenting. Studies
have been with Enterprise (closed stent), Solitaire and usage of complaint balloon.
The use of open cell stents (Neuroform) for Y stenting provides better scaffolding
of parent vessels and is used in this study for Y stenting.
The current article tries to address our single-center experience of Y stenting in
the treatment of ruptured wide-necked bifurcation aneurysms.
Procedure Details
After inducing general anesthesia, a 6 FR Cook (750 Daniels Way Bloomington, Indiana,
United States) long sheath was placed in common carotid artery through right femoral
access over a 5 FR Piccard diagnostic catheter and then DAC 070 (Stryker Neurovascular
4870 West 2100 South Salt Lake City, Utah, United States) guiding catheter was parked
in the cavernous segment of internal carotid artery (after giving 100 µg of intraarterial
nitroglycerin). Following this first, the difficult daughter branch to navigate is
cannulated with a Headway (Microvention Inc, 1311 Valencia Avenue, Tustin, California,
United States) 017 microcatheter over a Traxcess (Microvention, Inc,1311 Valencia
Avenue, Tustin, California, United States) 014 microwire. Another coiling microcatheter
(Excelsior SL 10 [Stryker Neurovascular, Business and Technology Park, Model Farm
Road, Cork, Ireland]) in our case was navigated inside the aneurysm sac over a 014
microwire and few coil loops were placed in it without detaching. The 017 microcatheter
in one daughter vessel was used to deploy a Neuroform Atlas stent so that a part remains
in the daughter vessel and it lands in the parent vessel across the neck of the aneurysm
sac. Now through the struts of this first stent 014 microwire (made in the form of
J) was passed in to the other daughter vessel (easily accessible as per initial plan)
and another Neuroform Atlas stent was deployed in a similar fashion so that the straight
limbs of both the stents overlapped in the single limb of Y reconstruct one within
the other. This step is considered the most difficult step in the process as deployment
of the second stent through the struts of the first might lead to displacement of
the first stent that may cause dissection or improper positioning leading to failed
procedure. The coiling catheter jailed across the stents needs to be taken care of
during this entire process as slight movement might lead to rupture of the aneurysm.
It was now used to coil the rest of the aneurysm and the coiling microcatheter in
the end was taken out to finish the process.
The whole process needs to be under loading dose of antiplatelets (which in our series
were done with Tab Ecosprin 300 mg and Tab Prasugrel 50 mg) 2 hours prior to stent
placement and Injection Heparin was used before starting and during the process with
intraoperative activated clotting time (ACT) monitoring and target ACT was kept approximately
double the baseline or roughly a value of 300.
Case 1
A 45-year-male, with known seizure disorder, came with sudden onset loss of consciousness
with severe headache. Computed tomography (CT) showed right temporal bleed ([Fig. 1A,B]) and CT angiography showed a right middle cerebral artery (RT MCA) bifurcation aneurysm.
digital subtraction angiography (DSA) showed a ruptured wide-necked bifurcation aneurysm
of RT MCA measuring 7.8 × 6.6 mm with neck measuring 4.6 mm ([Fig. 1C]). So, plan for Y stent-assisted coiling was taken in view of the wide neck and neck
dome ratio >2.A SL 10 microcatheter was placed into the aneurysm over a 014 microwire
and few coil loops were placed that were then jailed across a 3 x 24 mm size Neuroform
Atlas stent placed via a 017 microcatheter into the difficult most branch first that
in this case was the superior division through the struts of which subsequently 017
microcatheter was passed into the inferior division and a Neuroform Atlas stent 3
× 21 mm was placed. The coiling catheter was then used to place and fill the residual
aneurysm with further coils. Post-procedure injection showed some residual space in
the neck of the aneurysm as shown in [Fig. 1D]. Six months later, DSA showed thrombosis of residual filling that was present in
the aneurysm neck with no residual filling in the aneurysm (R &R 1) ([Fig. 1E,F]).
Fig. 1 Schematic diagram of a Y stent reconstruct with the pattern of Y stenting marked
in red ink resembling the letter “Y.”
Case 2
A 62-year-old female presented with severe headache and vomiting. CT showed a diffuse
subarachnoid hemorrhage (SAH). DSA showed a ruptured wide-necked ACOM aneurysm measuring
1.6 1.8 mm with neck measuring 1.2 mm with neck dome ratio more than 2. With a 017
microcatheter Neuroform Atlas stents were placed in a Y fashion in the two anterior
cerebral artery measuring 3 x 24 mm by 3 × 21 mm with the jailing technique for coiling
of ACOM aneurysm. The packing was dense and post procedure there was no complications.
The patient was discharged on double antiplatelets (Tab Ecosprin 150 mg and Tab Prasugrel
10 mg) and 6 months follow-up angiogram showed a well-coiled aneurysm without any
residual filling (R & R 1) ([Fig. 2]).
Fig. 2 Case 1: (A and B) subarachnoid bleed with right temporal hematoma, (C) digital subtraction angiography (DSA) finding of right middle cerebral artery bifurcation
aneurysm, (D) DSA image after Y stent-assisted coiling, (E and F) follow-up DSA image 6 months later showing progressive thrombosis of residual neck
and no residual recanalization of aneurysm.
Case 3
A 59-year-old female presented with sudden onset headache and vomiting following that
she was admitted and CT brain showed a large hematoma in midbasifrontal region measuring
4.5 × 3.1 cm with perilesional edema with SAH. Magnetic resonance angiography revealed
an ACOM aneurysm. DSA done confirmed a wide-necked ruptured ACOM aneurysm measuring
5.08 × 1.78 mm with neck 4.02 mm. Similarly Y stent with Neuroform Atlas stents were
done with 3 × 24 mm by 3 × 21 mm with coiling done by jailing technique. However,
post-procedure the patient had a deterioration in Glasgow Coma Scale (GCS) following
which intubation was continued and conservative management was continued. CT showed
expansion of the hematoma that was the reason for the deterioration of GCS; however,
the relatives denied any further intervention and leave against medical advice was
taken ([Fig. 3]).
Fig. 3 Case 2: (A and B) Diffuse subarachnoid hemorrhage, (C and D) digital subtraction angiography image of ACOM aneurysm, (E and F) DSA image of Y stent-assisted coiling.
Case 4
A 59-year-old male presented with headache and vomiting. CT showed Right sylvian fissure
bleed with subdural hematoma (SDH) in right side. DSA revealed a ruptured wide-necked
RT MCA bifurcation aneurysm measuring 5.25 × 5.05 mm with neck measuring 5.01 mm.
Thus, Y stent-assisted coiling was done with Neuroform Atlas stent measuring 3 x 24
mm by 4 × 24 mm with the coiling of aneurysm by jailing technique. The patient was
discharged on double antiplatelets (Tab Ecosprin 150 mg and Tab Prasugrel 10 mg).
After 2 months of discharge, the patient presented with slurred speech and altered
sensorium. CT brain now revealed acute on chronic SDH in right frontotemporoparietal
region that was subsequently managed by burr hole operation by the neurosurgical team.
Antiplatelets were modified (ascribing as the cause of atraumatic SDH) and he was
discharged on Tab Ecospirin 150 mg and Tab Plavix 75 mg. After 1 month of the same,
he again presented similarly but this time to another hospital where CT brain showed
a similar left frontoparietal SDH that was again managed surgically by burr hole and
antiplatelets were stopped. One month following this he presented with left-sided
weakness and aphasia suggestive of RT MCA syndrome; CT showed minor infarcts in RT
MCA territory without any new SDH. DSA was immediately done to find no residual filling
of MCA aneurysm but with minor clots in stents. Antiplatelets were renewed but this
time with only Ecosprin 150 mg and he was discharged in a stable condition ([Fig. 4]).
Fig. 4 Case 3: (A) ACOM aneurysm, (B) Y stent-assisted coiling.
Case 5
A 45-year-old female, hypertensive, diabetic, presented to us with headache, vomiting
with minor SAH in CT in the anterior cerebral interhemispheric fissure. DSA revealed
a ruptured wide-necked ACOM aneurysm measuring 1.98 × 2.78 mm with neck measuring
2.97 m. Y stenting with Neuroform Atlas stent was done measuring 3 x 24 mm by 3 ×
21 mm with coiling by jailing method. Post-procedure no complications were encountered.
DSA in follow-up after 6 months revealed no recanalization (R&R 0) with stent seen
in situ ([Fig. 5]).
Fig. 5 Case 4: (A–C) right middle cerebral artery (MCA) bifurcation aneurysm in digital subtraction angiography
(DSA), (D) DSA image of Y stent-assisted coiling, computed tomography brain on initial presentation
showing subarachnoid hemorrhage, (E–G) subdural bleed on either sides, (H) DSA of right MCA bifurcation aneurysm in follow-up.
Case 6
A 51-year-old male, hypertensive, bronchial asthma, h/o splenectomy and hemiarthroplasty,
chronic smoker, presented with headache diagnosed as SAH and ACOM aneurysm treated
7 years back with coiling. He was lost to follow-up and presented 7 years later with
mild headache. CT revealed no SAH. DSA was done to check for aneurysm coiling status
and large recanalization was documented (R& R 2) (measuring 5.23 × 4.14 mm) with neck
measuring 3.23 mm. The large neck and the anatomy led to decision of Y stent-assisted
coiling of recanalized ACOM aneurysm. Subsequently, 3 x 24 and 3 × 21 mm Neuroform
Atlas stents were used for Y stenting. Subsequent follow-up DSA showed thrombosis
of previously recanalized portion of ACOM aneurysm with stent in situ ([Fig. 6]).
Fig. 6 Case 5: (A and B) digital subtraction angiography image showing ACOM aneurysm, (C–F) Y stent-assisted coiling.
Discussion
Stent-assisted coiling has been in effect since 1997. Stents in aneurysm coiling offer
multiple advantages. It imparts an adjunct to potential mechanical, hemodynamic, and
biologic properties to coil embolization alone. It provides support to coils and prevents
its prolapse mechanically, serves as a conduit for passage of blood, and also acts
as a scaffold for endothelial growth and healing. Stents after placement also alter
the hemodynamics of blood flow into the aneurysm, thereby causing progressive thrombosis
of incompletely occluded aneurysms.
Even with the advancements of endovascular therapy for aneurysm management, wide neck
defined as neck diameter more than 4 mm with neck to dome ratio more than 2, at bifurcations,
is a hard nut to crack. Apart from the coil mass protruding and occluding the daughter
vessels that often are incorporated in the bifurcation aneurysms, these aneurysms
are more often recanalized by simple coiling and chance of rerupture remains high
in such cases. In the ATENA study, which was a morphologic study of 694 unruptured
aneurysms treated endovascularly, in which the investigators found that a dome-to-neck
aspect ratio of < 1.5 was associated with a decreased rate of successful coil embolization.
Various devices have come for such aneurysms like waffle-cone technique, flow diverters,
WEB, bifurcation devices like Pulse rider, pCONUS, pCANVAS, eCLIPS, honeycomb, Contour,
and Comaneci device. The Y stenting ([Fig. 7]) remains one of the most cost-effective and safe techniques for coiling of such
cases; however, it has technical difficulties and in inexperienced hands might lead
to increased morbidity.
Fig. 7 Case 6: (A) ACOM aneurysm digital subtraction angiography image, (B–D) Y stent-assisted coiling.
A total of six cases ([Table 1]) were obtained over 1 and ½ year from January 2019 to April 2020 with follow-up
after 6 months for all the patients except one (as she deteriorated and has been taken
leave against medical advice after procedure). Intraprocedural complications like
rupture of aneurysm, dissection, and stent misplacement were not seen in our series
in any patient; however, post-procedure a drop in GCS to E1M1 VT from E4V4M6 GCS status
was seen in one patient that was ascribed to expansion of hematoma. No episode of
thromboembolic events was noted in each of the cases. Vasospasm was noted in two patients
during the 7th to 9th day post ictus related to SAH-induced vasospasm as all were
ruptured cases. Rates of technical difficulties such as stent migration (3.1%), stent
prolapse (3.1%), and coil herniation (1.6%) remain low combining the two largest center
experiences.[6]The periprocedural symptomatic ischemic stroke rate was found to be 4.7% in larger
studies.[6]Thromboembolic rates range from 0 to 11.1%,[6] with the highest reported rates reported in the early experience. This difference
may reflect a broader acceptance of more long-term dual antiplatelet therapy based
on the preliminary data, specifically a reluctance to discontinue clopidogrel prior
to 6 months. The incidence of delayed strokes (> 2 weeks after procedure) is low at
3.1%.[1]
[2]
[6] There have been no reports of in-stent stenosis (approximately 7.8% incidence) requiring
treatment in studies by other groups.[1]
[7]
[8]
[9]
Table 1
Patients with location of aneurysm, size of stents used, and outcome
|
Patients
|
Location of aneurysm
|
Size of aneurysm
|
Neck
|
Size of Neuroform Atlas
|
Follow-up at 6 months R&R
|
Complications
|
|
Abbreviations: ACOM, anterior communicating; ACA, anterior cerebral artery; BAC, balloon-assisted
coiling; NA, not available; RT MCA, right middle cerebral artery; SDH, subdural hematoma.
|
|
1
|
RT MCA bifurcation
|
7.8 × 6.5
|
4.6
|
3x24 & 3 × 21
|
1
|
|
|
2
|
ACOM
|
1.6 × 1.8
|
1.2
|
3x24 & 3x 21
|
1
|
|
|
3
|
ACOM
|
5.08 × 1.78
|
4.02
|
3x24 & 3x 21
|
NA
|
Hematoma expansion
|
|
4
|
RT MCA bifurcation
|
5.25 × 5.05
|
5.01
|
3x24 & 4x 24
|
1
|
SDH
|
|
5
|
ACOM
|
1.98 × 2.78
|
2.97
|
3x24 & 3x 21
|
1
|
|
|
6
|
ACOM
|
5.23 × 4.14
|
3.23
|
3x24 & 3x 21
|
1
|
|
All the patients in our series were discharged on dual antiplatelets (Tab Ecosprin
150 mg and Tab Prasugrel 10 mg) till at least 6 months of follow-up with DSA and were
continued till 1 year after which plan was to continue on one antiplatelet lifelong.
After discharge, one patient developed subdural hematoma on double antiplatelets that
was then evacuated by burr hole and antiplatelet regime was changed to single antiplatelet
(clopidogrel only 75mg); however, he developed atraumatic subdural hematoma in the
contralateral side. Following this antiplatelets were withdrawn from an outside hospital
after burr hole of the opposite side, but he developed stent thrombosis and infarct
in his stented side. After this, he was put on single antiplatelet (Ecosprin 150 mg
only) and is continuing well till now.
Follow-up after 6 months of all the patients (5 patients) shows no recanalization
of the aneurysm (R &R 1). There was no episode of rerupture in any of the cases.
Progressive thrombosis of the incompletely coiled part of the aneurysm has been documented
in two cases. One of the cases was retreated with Y stenting after initial recanalization
following simple Balloon-assisted coiling 7 years ago in which coiling was not done
in the remnant neck of the aneurysm and just Y stenting was done. Follow-up angiogram
at 6 months revealed thrombosis of the remnant portion of the neck of the aneurysm
with R & R 1.
Despite inherent technical challenges, the centers reporting their experience with
Y-stent reconstruction have demonstrated high technical success ranging from 88.9
to 100%, while the incidence of complications on the initial treatment remained low
from 0 to 21%.[1]
[6]
[7]
[8]
[9]
[10]
All studies report a zero procedural mortality rate. Aneurysm recurrence rates range
from 8.9 to 28.6% at from 3.5 to 36.7% months follow-up. Our 6 months follow-up has
led to no recanalization so far in the five patients we have followed up. Retreatment
rates range from 0 to 15%[1]
[6]
[7]
[10] in other groups, whereas none so far required in our study.
Technical success in using Neuroform Atlas stents for such cases has been easy in
our experience. The placing of the first stent and crossing a 014 microwire in the
form of a J through the struts of the first stent has been smooth in our experience
with Neuroform Atlas stent and none of the case had stent migration, malapposition,
dissection during the procedure as a complication. Follow-up in all the cases showed
successful coiling without significant recanalization. Thus, Y stenting in our experience
has been successfully able to treat such wide-necked bifurcation aneurysms and is
a very good alternative to newer devices keeping also the economic background in resource-poor
settings.
Like in any other study, limitation in our study is the less number of sample size
and increasing this number will give a better insight on such cases.
Conclusion
Y stenting with or without coiling is an effective means of endovascular management
in this group of wide-necked bifurcation aneurysm in the era of modern endovascular
devices that obviously are with a price tag and often difficult in the middle-to-low
socioeconomic countries. Experience varies with centers, but overall our experience
as shared here offers significant benefit. Limitations remain like use of antiplatelet
drugs in acute ruptured scenario but still it offers nice outcomes as shown in our
series even with progressive thrombosis of incompletely occluded part of aneurysms
after coiling. Further studies are needed in this regard possibly with more patients
and larger period of study and follow-up.
