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CONCEPTS, INNOVATIONS, AND TECHNIQUES
TOPIC
Concepts, Innovations, and Techniques
Transcirculation Endovascular Treatment of
Complex Cerebral Aneurysms: Technical
Considerations and Preliminary Results
Felipe C. Albuquerque, MD*
L. Fernando Gonzalez, MD*†
Yin C. Hu, MD*
C. Benjamin Newman, MD*
Cameron G. McDougall, MD*
*Division of Neurological Surgery, Barrow
Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona;
†Current Location: Department of Neurosurgery, Jefferson Medical College, Philadelphia, Pennsylvania
Correspondence:
Felipe C. Albuquerque, MD,
c/o Neuroscience Publications,
Barrow Neurological Institute,
350 West Thomas Road,
Phoenix, AZ 85013.
E-mail: [email protected]
Received, February 18, 2010.
Accepted, August 23, 2010.
Copyright ª 2011 by the
Congress of Neurological Surgeons
BACKGROUND: Unfavorable anatomy can preclude embolization of intracranial
aneurysms. Transcirculation techniques, in which a catheter is navigated from one side of
the brain to the other or from the anterior to the posterior circulation, are alternative
pathways for primary or balloon- or stent-assisted coiling.
OBJECTIVE: We report the largest experience in coil embolization of aneurysms using
transcirculation techniques.
METHODS: We reviewed our endovascular database from 2006 to 2009 and identified
18 patients who had aneurysms treated with transcirculation techniques.
RESULTS: Eight patients had anterior and 10 had posterior circulation aneurysms.
Overall, 8 patients were treated with stent-assisted coiling and 9 with balloon-assisted
coiling, including 1 patient treated with a ‘‘kissing balloon’’ technique. Of the 9 patients
treated with balloon-assistance, 1 also was stented at the conclusion of aneurysm
coiling. One patient with a left fourth vertebral artery (V4) aneurysm was treated with
coiling alone via a bilateral vertebral artery (VA) approach. In 14 patients, the anterior
communicating and posterior communicating arteries were used as conduits. In 4 patients, both VAs were traversed to treat 2 V4 aneurysms and 2 posterior inferior cerebellar
artery aneurysms. One patient died as a result of treatment and was the only permanent
complication (5.6%). Complete or near-complete (.95%) embolization was achieved in
all patients.
CONCLUSION: Transcirculation techniques are effective pathways for embolization of
complex aneurysms. Although technically challenging, these techniques are associated
with an acceptably low rate of complications when compared to the natural history of
the treated lesion.
KEY WORDS: Aneurysm, Balloon, Coiling, Stent, Transcirculation
Neurosurgery 68:820–830, 2011
DOI: 10.1227/NEU.0b013e3182077f17
W
hen aneurysms are coiled, various
techniques can be used to preserve the
parent artery. Balloon or stent assistance,
or both, often is involved. In certain complex cases,
the primary navigation of these devices to the
target lesion is either too difficult to achieve or
ABBREVIATIONS: AcoA, anterior communicating
artery; ICA, internal carotid artery; PCA, posterior
cerebral artery; PICA, posterior inferior cerebellar
artery; PCoA, posterior communicating artery;
SCA, superior cerebellar artery; V4, fourth intracranial vertebral artery; VA, vertebral artery; VBJ,
vertebrobasilar junction
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fails to provide compete protection of the parent
artery. Transcirculation catheterization, also
known as the retrograde approach, involves the
navigation of a catheter, balloon, or stentdelivery device either from one arterial side to the
other or from the anterior to the posterior circulation. These techniques require adequate
patency of the posterior (PCoA ) and anterior
communicating arteries (ACoA) or of both
vertebral arteries (VAs). Furthermore, two brachiocephalic arteries must be catheterized.
These transcirculation techniques are particularly effective for treating wide-necked basilar
apex and ACoA aneurysms, aneurysms involving
a fetal PCoA, superior cerebellar artery (SCA)
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TRANSCIRCULATION ENDOVASCULAR TREATMENT OF ANEURYSMS
aneurysms, intracranial vertebral artery (V4 segment) aneurysms,
carotid terminus aneurysms, and posterior inferior cerebellar
artery (PICA) aneurysms. Simultaneous angiography through the
2 target brachiocephalic vessels adequately delineates the route
of catheterization, and transcirculation navigation of a catheter,
balloon, or stent-deployment device facilitates primary coiling of
the aneurysm.
MATERIALS AND METHODS
loading dose of abciximab was infused transarterially through the microcatheter proximal to the stent at the conclusion of treatment. These
patients were then treated with aspirin and clopidogrel, as described
earlier. Patients undergoing balloon-assisted coiling were not treated with
anti-platelet agents, although practitioners at other institutions do use
these medications in this group of patients. Finally, all patients were
heparinized at some point during treatment to achieve an activated
coagulation time greater than 250 seconds. Heparin was given at the
onset of the procedure when treating unruptured aneurysms and after
placement of a few coils when treating ruptured aneurysms.
Patients
Transcirculation Techniques
Patients included 11 women and 7 men ranging in age from 38 to
79 years (mean age, 59 years). Aneurysm subtypes included 5 basilar
apex, 3 internal carotid artery (ICA) terminus, 3 ACoA, 2 PCoA,
2 PICA, 2 V4, and 1 SCA aneurysm. All patients were deemed high risk
for surgical clip ligation either because of the location of their aneurysm
or because of comorbid conditions. Overall, 10 aneurysms were located
in the posterior circulation and 8 in the anterior circulation. Transcirculation routes involved the ACoA in 8 patients ( Table 1), the PCoA
in 6 patients ( Table 2), and both VAs in 4 patients ( Table 3). Thirteen
patients presented with unruptured aneurysms, and 5 presented with
subarachnoid hemorrhage.
Balloon-assisted coiling was performed in 9 patients, including 1 in
whom a ‘‘kissing balloon’’ construct was employed. Of these 9 patients,
1 was also stented at the conclusion of balloon-assisted coiling. In
addition to this patient, 8 others were treated with stent-assisted coiling.
One patient was treated with a dual-catheter technique alone and
required neither balloon nor stent assistance.
Once treated, all patients were entered into our prospectively maintained database in which treatment-related and post-treatment complications were tracked. The results of clinical and radiographic followup subsequently were catalogued in this database. Clinical assessment
was performed by the treating physician both immediately after the
procedure and during subsequent office visits. These records were reviewed to establish delayed patient outcomes.
Standard anticoagulation and anti-platelet regimens were employed
during treatment of all patients. Specifically, patients undergoing
planned stenting in the setting of an unruptured aneurysm were pretreated with clopidogrel (75 mg) and aspirin (325 mg) for 3 days before
the procedure was performed. Patients remained on this dual regimen for
3 weeks after treatment. In the setting of unplanned stenting, half the
Posterior Circulation
Transcirculation catheterization of the basilar apex requires adequate
patency of one of the PCoAs. Deployment of a stent in a horizontal
fashion across the neck of an apical aneurysm allows both posterior
cerebral arteries (PCAs, Figure 1) to be preserved. This maneuver
obviates the need to create a Y-stent construct in which one stent is
deployed through the side walls of another stent.1 Y-stenting may disrupt
or damage the original stent and is likely associated with a higher
incidence of thromboembolic complications.1 When deploying a stent in
the horizontal fashion, we prefer to jail a microcatheter within the
aneurysm first. This maneuver negates the risk of damaging or moving
the stent during the subsequent catheterization of the aneurysm. If the
junction of the PCoA and PCA is tortuous, a stent-deployment catheter,
which typically is large and not overly navigable, may not make the
necessary arterial turns to cross the basilar apex. In this case, it may be
necessary to navigate a more supple and smaller microcatheter first and
then exchange it for the stent delivery catheter.
Similarly, a balloon can be steered across the basilar apex via the
PCoA. As with the horizontal deployment of a stent, a catheter exchange
may be necessary to deliver the balloon to the neck of the aneurysm. In
the case of a large aneurysm, however, balloon remodeling is less desirable than stent assistance, because multiple balloon inflations would be
needed to ensure adequate coil embolization. These inflations increase
the risk of arterial rupture and thromboembolic complications.
The PCoA also can be used as a transcirculation conduit for stenting
or balloon remodeling across the neck of the SCA (Figure 2). In some
SCA aneurysms, the parent artery originates from the aneurysm and
courses inferiorly at an acute angle. This angulation precludes catheterization of the SCA from the transvertebral route, because the course of
TABLE 1. Clinical Summary of Patients Undergoing Treatment via the ACoAa
Patient
1
2
3
4
5
6
7
8
Age/Sex
Aneurysm Site
SAH
Assist Technique
73/F
75/F
52/M
56/F
65/M
38/M
49/F
78/F
ACoA
ACoA
ACoA
L ICA terminus
R ICA terminus
L ICA terminus
L PCoA
R PCoA
No
Yes
Yes
No
No
No
No
No
Stent
Balloon
Kissing balloons
Stent
Stent
Stent
Balloon
Balloon
Result
Outcome
F/U, mo
CO
CO
CO
CO
CO
CO
CO
CO
CO
NA
CO
CO
CO
NA
CO
NA
5
Lost
4
17
7
Lost
3
Died
a
AcoA, anterior communicating artery; CO, complete or near-complete occlusion (.95%); F/U, follow-up; ICA, internal carotid artery; L, left; NA, not applicable; PCoA, posterior
communicating artery; R, right; SAH, subarachnoid hemorrhage.
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ALBUQUERQUE ET AL
TABLE 2. Clinical Summary of Patients Undergoing Treatment via the PCoAa
Patient
9
10
11
12
13
14
a
Age/Sex
Aneurysm Site
SAH
Assist Technique
50/F
65/F
54/M
65/F
55/M
79/F
BA
BA
BA
BA
BA
L SCA
No
No
No
Yes
No
No
Stent
Stent
Stent
Balloon
Balloon Stent
Stent
Result
Outcome
Length of F/U, mo
CO
CO
CO
CO
CO
CO
CO
NA
CO
NA
CO
CO
18
Refused
7
Lost
5
12
Stent Location
P1 to P1
P1 to P1
P1 to P1
N/A
P1 to P1
R P1 to L SCA
BA, basilar apex; CO, complete or near-complete occlusion (.95%); F/U, follow-up; L SCA, left superior cerebellar artery; NA, not applicable; SAH, subarachnoid hemorrhage.
the SCA is too difficult to navigate. Given the simultaneous tortuosity
of the PCoA and SCA vessels, this scenario likely requires a catheter
exchange for either the balloon catheter or the stent delivery device.
Given the difficulties of traversing the side walls of a stent constrained
within the small caliber of the SCA, jailing a microcatheter within the
aneurysm before stent deployment is preferable.
V4 aneurysms are typically of the dissecting variety and pose great risks
to patients. Because of the potentially devastating consequences of a first
rupture and the propensity of V4 aneurysms for re-rupture, these
aneurysms mandate urgent treatment. Transcirculation techniques, in
which both VAs are catheterized, are invaluable in the management of
these challenging lesions. Two scenarios are particularly exemplary of the
utility of these approaches. In the first, a balloon is navigated over the
vertebrobasilar junction (VBJ) down the contralateral VA to a position
just distal to the aneurysm. This configuration serves to protect the origin
of a critical arterial branch such as the PICA or anterior spinal artery or to
buttress the coil mass and prevent it from migrating toward the VBJ. In
the second scenario, microcatheters can be navigated via both VAs to the
aneurysmal section. Simultaneous coiling through both microcatheters
speeds the treatment of the lesion and also may buttress the coil mass at
the aneurysm site.
Bilateral catheterization of the VA also can be used to treat select PICA
aneurysms (Figure 3). As with SCA aneurysms, the PICA can originate
from the neck of the aneurysm and course inferiorly. This trajectory
makes catheterization of the PICA for balloon remodeling difficult from
an ipsilateral VA approach. Navigation of a microcatheter from the
contralateral VA over the VBJ and down the ipsilateral VA facilitates
catheterization of the PICA. In this fashion, a microcatheter can be
exchanged for a balloon catheter as a means of protecting PICA during
aneurysm coiling.
Anterior Circulation
Three scenarios are ideal for the use of the transcirculation techniques:
fetal PCoA aneurysms; ICA terminus aneurysms; and wide-necked
ACoA aneurysms. Transcirculation navigation across the ACoA is
necessary in each case.
As with PICA and SCA aneurysms, a fetal PCoA may arise from the
neck of the aneurysm and course inferiorly at an acute angle (Figure 4).
This angle is difficult to navigate from an ipsilateral approach. Traversing
the ACoA and coming down from the ICA terminus facilitate catheterization of the fetal PCoA. Because primary navigation of a balloon is
difficult, a microcatheter exchange for the balloon catheter often is
required. Once the balloon is placed appropriately, the aneurysm can be
catheterized from an ipsilateral carotid artery approach.
A balloon or stent can be placed across the ICA terminus from the A1
to M1 segments by traversing a patent ACoA segment (Figure 5). Given
the relatively straight trajectories of the A1 and M1 segments, these
devices usually can be navigated primarily rather than requiring a microcatheter exchange. The aneurysm can be catheterized from an ipsilateral approach. As with basilar apex aneurysms, we typically jail the
microcatheter in place when using a stent–assisted technique.
The transcirculation treatment of wide-necked ACoA aneurysms is
complicated by the tortuosity of the A1-A2 junction and by the often
small caliber of the ACoA. In most cases, primary catheterization with
a microcatheter and subsequent exchange for the balloon or stent delivery devices are required. These lesions can be treated either through
a kissing balloon construct or through Y stenting. These scenarios require
catheterization of both ICAs. The complexity of these techniques likely
exposes patients to increased risk. This factor must be weighed against
the natural history of the lesion were it left untreated or were it addressed
through a microsurgical approach.
TABLE 3. Clinical Summary of Patients Undergoing Treatment via Bilateral Vertebral Arteriesa
Patient
15
16
17
18
Age/Sex
Aneurysm Site
SAH
Assist Technique
53/F
57/F
44/M
44/M
L PICA
L PICA
L V4
R V4
No
No
No
Yes
Balloon
Balloon
None
Balloon
Result
Outcomes
Length of F/U, mo
CO
CO
CO
CO
CO
CO
CO
CO
3
13
5
13
a
CO, complete or near-complete occlusion; F/U, follow-up; L, left; R, right; PICA, posterior inferior cerebellar artery; SAH, subarachnoid hemorrhage; V4, fourth vertebral artery
segment.
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TRANSCIRCULATION ENDOVASCULAR TREATMENT OF ANEURYSMS
FIGURE 1. A 65-year-old woman presented with headaches. A, early-phase posteroanterior (PA) right vertebral artery (VA) angiogram demonstrated a wide-necked basilar
apex aneurysm. B, late-phase PA arterial angiogram demonstrated the subtle opacification of the left posterior cerebral artery (PCA) (arrows). Simultaneous left intracranial
artery (ICA) and right VA angiogram (C) and angiographic image of transcirculation catheterization of the right PCA (D) showed a patent segment of the posterior
communicating artery (PCoA). A stent delivery catheter was navigated across the peak and into the right PCA while a microcatheter was jailed in the dome of the aneurysm. E,
native imaging demonstrated the stent delivery catheter in the distal right PCA and jailing of the microcatheter in the dome of the aneurysm (arrow). F, the stent was
subsequently deployed from one PCA segment to the other (arrows). G, after the PCAs were stented, the aneurysm was progressively coiled; native fluoroscopic images show the
aneurysm (H) during coiling and (I) after coiling is complete. PA (J) and lateral (K) angiographic images show that at the conclusion of stent-supported embolization, the
aneurysm was completely obliterated. L, lateral ICA angiographic image shows preservation of the PCoA (circle). Reproduced with permission from Barrow Neurological
Institute.
Finally, transcirculation navigation through both A1s may be necessary when 2-catheter embolization of a wide-necked ACoA aneurysm is
considered. In this scenario, a large 3-dimensional coil is threaded into
but not deployed in the aneurysm, and then multiple smaller coils are
NEUROSURGERY
deployed into the aneurysm via the second catheter. The first coil serves
to cover the ostium of the aneurysm and contain the smaller coils that
follow. Once a stable coil mass has been created, the first coil is detached.
We used this technique in 1 patient in our series.
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ALBUQUERQUE ET AL
FIGURE 2. A 73-year-old woman presented with headache. A, 3-dimensional CT reconstruction showed a left superior cerebellar artery (SCA) aneurysm. PA (B) and lateral
(C) angiographic images confirm that the left SCA originated from the proximal portion of the aneurysm and coursed inferiorly in an acute angle from the basilar artery. Right
posteroanterior (D) and lateral ICA (E) angiographic images confirmed the presence of a large posterior communicating artery (PCoA, arrow). Roadmap images demonstrating
jailing of a catheter in the dome of the aneurysm (arrow) (F), and transcirculation placement of a stent delivery device via the right PCoA and down into the left SCA
(arrowhead) (G). H, native image demonstrates placement of the stent from the right PCA into the left SCA. I, at the conclusion of stent-supported coil embolization, there was
near-complete obliteration of the aneurysm. Reproduced with permission from Barrow Neurological Institute.
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TRANSCIRCULATION ENDOVASCULAR TREATMENT OF ANEURYSMS
FIGURE 3. PA (A) and lateral (B) angiographic images of a 53-year-old woman who presented with
headaches. Left VA angiography demonstrated a large left posterior inferior cerebellar artery (PICA)
aneurysm. The left PICA originated from the base of the aneurysm and coursed inferiorly at an acute
angle. A small right superior cerebellar artery (SCA) aneurysm also was present. A balloon catheter was
navigated into the left PICA via a catheter exchange performed via the right VA. Native fluoroscopic (C),
PA (D), and lateral (E) blank roadmap images demonstrate inflation and deflation (F) of the balloon. In
C and D, the tube was obliqued in a fashion looking down the barrel of the PICA. In this way, we were
able to safely ascertain that the aneurysm projected superiorly above the artery. PA (G) and lateral (H)
angiographic images obtained after balloon-assisted coil embolization show that the aneurysm was
occluded completely. The left PICA also is patent. I, magnetic resonance (MR) angiogram obtained on
postoperative day 1 demonstrated complete obliteration of the aneurysm. J, sequential axial MR images
demonstrated patency of the left PICA. Reproduced with permission from Barrow Neurological Institute.
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FIGURE 4. A 49-year-old woman presented with an aneurysm originating from a fetal PCA. Simultaneous PA (A) and lateral (B) ICA angiograms demonstrated a widely
patent anterior communicating artery (ACoA). The left fetal PCA projected inferiorly from the neck of the aneurysm and coursed in an acute trajectory relative to the left ICA
(circle). C, a balloon catheter was navigated after a microcatheter exchange into the fetal left PCoA across the ACoA. D, the catheter was then navigated into the aneurysm. E,
at the conclusion of embolization, the PA angiographic image demonstrated that the aneurysm was obliterated completely and that the fetal PCA was preserved. Used with
permission from Barrow Neurological Institute.
RESULTS
At the conclusion of the original procedure, all aneurysms were
completely or near completely (.95%) coiled. The extent of
coiling was assessed by the primary surgeons (FCA, CGM)
performing the procedure and was in accordance with standard
endovascular evaluations documented in the literature.
Two complications occurred as a result of treatment. After
a procedural rupture, 1 patient failed to awaken after treatment
and eventually died from complications related to status epilepticus. This iatrogenic rupture occurred during treatment of
a fetal PCoA in which a balloon catheter was placed in the fetal
vessel after transcirculation exchange across the ACoA. The
rupture occurred after placement of the fourth coil and was
controlled by balloon inflation and further coiling. The second
complication occurred in a patient with an ICA terminus aneurysm who developed a thrombus within the M1 arterial segment that was treated with thrombolysis. The patient suffered no
826 | VOLUME 68 | NUMBER 3 | MARCH 2011
sequelae. Therefore, only 1 patient (5.6%) suffered permanent
complications as a result of transcirculation treatment.
Clinical and radiographic follow-up was obtained in 13 of the
17 surviving patients. Three patients were lost to follow-up, and
1 patient refused. Of the13 patients with follow-up, all demonstrated complete or near-complete obliteration (.95%) of
their aneurysms on either digital subtraction angiographic or
magnetic resonance angiographic follow-up. Of these 13 patients,
all were neurologically unchanged as a result of treatment. The
mean length of follow-up was 8.6 months (range, 3-18 months).
DISCUSSION
Transcirculation techniques are invaluable in the treatment of
complex cerebral aneurysms. Their use, however, should be reserved
for patients for whom the risks of leaving their aneurysms untreated
are high. The comparative morbidity and mortality associated with
a conventional surgical approach also should be weighed against the
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FIGURE 5. A 38-year-old man underwent MRI for evaluation of his neurofibromatosis, and a left ICA terminus aneurysm was discovered. A, left posteroanterior ICA
angiography confirmed the presence of the aneurysm. B, simultaneous angiography through both ICAs demonstrated a large and widely patent AcoA (arrow). C, angiographic
image looking down the barrel of the middle cerebral artery (MCA) and anterior cerebral artery (ACA) shows a double density at the base of the aneurysm. D, native
fluoroscopic image obtained after the stent was deployed in a transarterial fashion via the ACoA. The proximal stent tines are seen within the ACAs. E, anteroposterior
angiographic image obtained during coil embolization demonstrates what appears to be coil herniation into the parent ICA terminus. Nonetheless, native (F), angiographic
(G), and native (H) images obtained looking down the barrel of the ACA demonstrate that the struts of the stent are distinct from the coil mass. I, the double density of the ACA
and MCAs also is seen on subtracted angiography (arrows). At the conclusion of embolization, posteroanterior (PA) (J) and lateral (K) angiograms demonstrate near-complete
obliteration of the aneurysm, as well as preservation of the parent ICA terminus. L, MR angiographic image confirms near-complete obliteration of the lesion. Reproduced with
permission from Barrow Neurological Institute.
risks of these technically challenging endovascular approaches.
Nonetheless, in the setting of adequately large communicating or
VAs, these catheterizations can be performed safely.
This series represents the largest number of patients treated
through transcirculation routes. Six prior reports of 12 patients
have documented the transcirculation deployment of stents for
the treatment of 8 basilar apex aneurysms, 3 ICA terminus
NEUROSURGERY
aneurysms, and 1 ACoA aneurysm (Table 4).2-7 Moret et al.8 also
reported the transcirculation navigation of a balloon catheter for
coiling 10 aneurysms in 10 patients. Gurian et al.9 reported the
transcirculation occlusion (via the PCoA artery) of the distal right
VA for the treatment of a giant V4 aneurysm. Ours is the first
report to document the transcirculation balloon catheterization
of fetal PCoA and PICAs as well as the transcirculation,
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TABLE 4. Summary of Transcirculation Cases in the Literaturea
Author
Fitzpatrick et al
Cross et al3
Pride et al4
Kelly et al5
Benndorf et al6
Wanke et al7
Moret et al8
Gurian et al9
Aneurysm(s) Location
2
1
1
3
2
2
1
1
1
4
2
1
1
1
1
1
BA
BA
BA
BA
ICA-T
ACoA
ICA-T
BA
BA
ICA-T
PCoA
PCoA
SCA
PICA
VA
Conduit
Treatment
PCoA
PCoA
PCoA
PCoA
ACoA
ACoA
ACoA
PCoA
PCoA
ACoA
PCoA
ACoA
PCoA
CVA
PCoA
SAC
SAC
SAC
SAC
SAC
SAC
SAC
SAC
BAC
BAC
BAC
BAC
BAC
BAC
Coil
a
ACoA, anterior communicating artery; BA, basilar apex; BAC, balloon-assisted
coiling; CVA, contralateral vertebral artery; ICA-T, internal carotid artery terminus;
PCoA, posterior communicating artery; PICA, posterior inferior cerebellar artery;
SAC, stent-assisted coiling; SCA, superior cerebellar artery; VA, vertebral artery.
stent-assisted treatment of an SCA aneurysm. We also describe
novel strategies for the treatment of ACoA and V4 aneurysms.
Transcirculation techniques are particularly efficacious when
angulation of the parent or branching vessel would be difficult or
impossible to catheterize from an antegrade approach. In our
series, this was the case for 1 SCA, 1 PICA, and 2 fetal PCoA
aneurysms. The acute angulation of those arteries projecting
inferiorly from the aneurysm made antegrade catheterization
impossible to achieve. In each of these 4 cases, retrograde
transcirculation catheterization to deploy a balloon or stent delivery device facilitated coiling. However, because of the lack of
navigability of these devices, primary microcatheterization and
subsequent catheter exchange were required to complete treatment. Although this additional step was performed without incident in all cases, it likely increases the risk of these procedures.
In cases of basilar apex, ICA terminus, and even some middle
cerebral artery aneurysms, Y-stenting techniques have been used.1
The horizontal insertion of a stent across the neck of a basilar or
ICA terminus aneurysm may have several advantages over this
technique. In the Y construct, neither stent actually bridges the
entire neck of the aneurysm.1 A horizontally placed stent spans
the entire neck and may be more effective in directing flow away
from the ostium of the aneurysm. Placement of a single stent may
be associated with less risk of thromboembolic complications.
Furthermore, a single horizontally placed stent represents less
metal and, therefore, may incite less intimal hyperplasia. The
financial burden for patients and the hospital also should be
considered: a single stent is less expensive than two. Finally, in the
Y construct, one or both stents probably are damaged to a certain
degree by the sidewall navigation.1 Such damage does not occur
with the transcirculation deposition of a stent.
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Transcirculation deposition of a stent in the treatment of
basilar apex aneurysms also may be superior to the ‘‘waffle cone’’
technique, in which a stent is deployed from the basilar artery
into the proximal neck of the aneurysm.10 The expanded tines
within the aneurysm neck serve to secure coils within the aneurysm. Long-term follow-up in patients treated with this
technique is not yet available.10 One can argue that a stent placed
in this vertical fashion directs flow into the aneurysm and may be
associated with a higher rate of coil compaction.
Several factors must be considered when attempting transcirculation catheterization of the basilar apex. The caliber and
tortuosity of the PCoA must be favorable to allow passage of
either the stent delivery device or balloon catheter. Similarly, the
trajectory of the PCAs must be assessed. Either a horizontal
course or acute inferior angulation of the PCAs is a possible
configuration for the horizontal deposition of a stent. However,
vertical angulation of the PCAs is better suited for Y stenting. The
length of the stent is another important factor, as longer devices
are more apt to be deployed inadvertently in the PCoA. Deposition within the PCoA may distort the vessel and crimp the
stent, possibly increasing the likelihood of in-stent stenosis.
As with basilar apex aneurysms, SCA aneurysms pose several
anatomic challenges. The caliber and trajectory of the PCoA, PCA,
and SCA must be favorable to allow the transcirculation treatment
of this subgroup of aneurysms. Stenting from the PCA to the
contralateral SCA ‘‘jails’’ the contralateral PCA. The long-term
effects on the patency of this jailed vessel are unknown. At the
1-year follow-up visit of our patient with the SCA aneurysm, the
contralateral PCA remained normally patent and the aneurysm
completely occluded. How a stent placed in this configuration
alters the flow at the basilar apex is also unknown. One could argue
that stenting from the PCA to the SCA diverts flow away from the
ostium of the aneurysm as it does in basilar apex aneurysms.
One also must consider that deposition of the stent into such
a small vessel may crimp the cells of the stent, precluding secondary
catheterization of the aneurysm. In this instance, we prefer to
jail a microcatheter primarily within the aneurysm before deploying
the stent. Finally, deposition of stents in these small-caliber arteries
may be associated with a higher rate of in-stent stenosis and
intimal hyperplasia. Our previous experience with the Neuroform
(Boston Scientific, Ellicott City, Maryland) and Wingspan (Boston
Scientific) stenting systems suggests that this may be the case.
ICA terminus aneurysms are technically easier to treat in
a transcirculation fashion because catheterization is directed horizontally across the ACoA. For aneurysms involving the basilar apex
and SCA, navigation first must be directed posteriorly through the
PCoA and then horizontally across the PCAs. The added tortuosity
of this approach confers a greater degree of complexity. For ICA
terminus aneurysms, the caliber and tortuosity of the bilateral A1s
and ACoA must be conducive to allow transcirculation navigation.
As with basilar and SCA aneurysms, we typically prefer the jailing
technique for coiling rather than navigating across both stent walls.
Doing so likely reduces the incidence of stent distortion, damage,
and movement.
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TRANSCIRCULATION ENDOVASCULAR TREATMENT OF ANEURYSMS
Wide-necked ACoA aneurysms represent the most challenging
subgroup to treat in a transcirculation fashion. Catheterization of
both A1s and A2s is required for delivery of either stents or balloons
to the aneurysmal neck. The small caliber of these vessels increases
the difficulty of creating a Y-stent construct and likely subjects the
patient to greater morbidity and mortality. The kissing balloon
technique also is difficult, given the lack of navigability of these
devices, the need for a microcatheter exchange, and the small luminal
diameter of the target vessels. Moreover, the balloons must be positioned so that the second balloon abuts the side of the first.
Multiple or prolonged inflation subjects patients to ischemic and
thromboembolic sequelae and increases the likelihood of vessel
rupture, which usually is a catastrophic event. Given all of these
daunting factors, the transcirculation treatment of these lesions
should be reserved for select cases.
Although transcirculation techniques have been described for
basilar apex, ACoA, ICA terminus, and SCA aneurysms, we are
the first to report the retrograde catheterization of the V4, PICA,
and fetal PCoA circulations for aneurysm treatment. In the fetal
PCoA aneurysms, the acute inferior angulation of the fetal vessels
from the aneurysmal necks negated the possibility of antegrade
catheterization. In both cases, a microcatheter exchange for the
balloon was required, given the complexity of the catheterization
and the relative lack of navigability of the balloon catheter itself.
Regarding the PICA aneurysms, microcatheter exchange was
again required to deploy the balloon accurately in the PICA. Like
the fetal PCoA aneurysms, PICA coursed inferiorly from the
aneurysm neck in both cases.
The two V4 aneurysms were treated through 2 different
transcirculation strategies. In 1 of these, the PICA originated just
distal to the dissecting aneurysm and was protected through
retrograde balloon catheterization from the contralateral VA. In
the second, catheters were navigated from both VAs to coil a left
V4 dissecting aneurysm. This technique enabled us to establish
a stable coil mass in the distal V4 segment via the transcirculation
catheter. In so doing, we were then able to coil from the ipsilateral
catheter without fear of coil propagation into the basilar artery.
This approach had the added benefit of speeding coil occlusion
of the affected V4 segment, as we were able to deliver coils
simultaneously through both catheters.
Several factors may raise the likelihood of complications
associated with the use of transcirculation techniques. Since 2
brachiocephalic arteries are catheterized, thromboembolic complications would be expected to be higher. Similarly, the frequency of arterial dissections may be greater. The transcirculation
deployment of a balloon or stent typically requires a microcatheter exchange. Theoretically, then, the chances of causing
a microvascular perforation or thrombosis are increased. Arterial
rupture from balloon inflation and intimal injury from stent
deposition also may occur more frequently, especially with the
use of these devices in small-caliber vessels. Also, arterial access is
required in both femoral arteries; therefore, the rate of puncture
site complications would be expected to be higher. In our series,
only 2 permanent complications occurred. Nonetheless, this
NEUROSURGERY
complication rate may be artificially low, given the relatively small
sample size and the 4 cases lost to follow up.
Three-dimensional angiography is vital to the success of
transcirculation catheterization. Three-dimensional angiography
not only will demonstrate the optimal working angle for parent
vessel preservation during coiling, but it also can be used to
optimize visualization of the transcirculation route. Similarly,
simultaneous angiography or roadmapping through both guide
catheters will illuminate the transcirculation route and clarifies its
degree of tortuosity. Biplanar angiography is essential for performing these techniques.
CONCLUSION
Although they are technically demanding, transcirculation
techniques are effective means of addressing complex intracranial
aneurysms. These techniques require bifemoral access, catheterization of 2 brachiocephalic vessels, and microcatheter navigation
across the circle of Willis. Because of the relative tortuosity of
these pathways, microcatheter exchanges for either a stent delivery device or balloon catheter often are necessary. Although
these maneuvers likely increase the incidence of complications,
we have demonstrated their relative safety and efficacy when
compared to the natural history of these challenging aneurysms.
Disclosure
The authors have no personal financial or institutional interest in any of the
drugs, materials, or devices described in this article.
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VOLUME 68 | NUMBER 3 | MARCH 2011 | 829
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ALBUQUERQUE ET AL
COMMENTS
A
lbuquerque and colleagues from the Barrow Neurological Institute
present a collection of 18 patients treated with transcirculatory stent
or balloon-assist endovascular techniques. In these patients, the anatomic
relationship of the aneurysm to the parent or branch arteries required
balloon or stent assistance, and the optimal geometry for placement of
the balloon or stent was ‘‘transcirculatory,’’ meaning via the anterior or
posterior communicating artery, or antegrade up one vertebral artery and
retrograde down the other. One of the 18 patients suffered a periprocedural complication (rupture and death).
The authors are to be congratulated on their creative use of the tools
available, as well as their excellent outcomes in these challenging cases.
This is a very useful and practical report. While the need for these
approaches is uncommon, in some situations a transcirculatory technique is by far the best option. The retrograde catheterization method for
stent-assisted coiling of posterior inferior cerebellar artery aneurysms is
one that I have found particularly useful. The large experience reported
here should help readers to recognize situations where these creative,
830 | VOLUME 68 | NUMBER 3 | MARCH 2011
‘‘outside the box’’ approaches may be useful, as well as the potential
pitfalls and limitations of the technique.
Colin P. Derdeyn
St. Louis, Missouri
A
lbuquerque and colleagues report their experiences treating patients
with complex aneurysms with what they describe as transcirculation
endovascular approaches. The authors clearly explain their techniques
and the considerations in such cases. Multiple cases are well imaged to
enhance this document and facilitate the understanding of the approaches. Those creative retrograde approaches already described by Dr.
Moret are rarely necessary, but this article reconfirms their usefulness in
selected cases. With those approaches, potential complications in a part
of the brain unaffected by the current pathology are possible. This fact
should be kept in mind when selecting the treatment option and when
considering those approaches. The authors must to be congratulated for
their great results with these demanding techniques.
Eric Sauvageau
Tampa, Florida
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