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Analysis of the Anatomical Factors Affecting Ability to Navigate Penumbra Catheter through Internal Carotid Siphon


Abstract and Figures

Objective: The efficacy and safety of aspiration thrombectomy using Penumbra catheter with acute large vessel occlusion in the anterior circulation have been reported in previous studies. In some cases, the carotid siphon (CS) is elongated, and with this anatomy, especially where there is bifurcation of the ophthalmic artery (OA), navigation of Penumbra catheters into distal internal carotid artery (ICA) is interrupted, which is known as the ‘ledge effect’. We investigate the anatomical characteristics of CS that cause interruption of navigation of the Penumbra catheter. Methods: Between January 2015 and March 2018, mechanical thrombectomy using Penumbra 60 was performed on 51 patients with middle cerebral artery (MCA) or intracranial ICA occlusion. Patients were divided into two groups: The ‘ledge-effect’ group those in whom the Penumbra catheter was unable to be navigated into the distal ICA through the CS, and ‘no ledge-effect’ group those in whom this was possible. The anatomical characteristics of CS, the diameter of ICA, diameter of OA, OA/ICA ratio and radius of the CS were evaluated using angiographical imaging. Results: The ‘ledge-effect’ group numbered eight cases (17%). Only the value of the CS radius was significantly smaller in the ledge-effect group (p = 0.0019), other parameters were not significantly different between the groups. The cutoff radius value was 3.62 mm. Conclusion: The most notable anatomical factor affecting possibility of navigation of the Penumbra catheter through the CS was the CS radius. This could be useful information when devices used in mechanical thrombectomy are selected.
DOI: 10.5797/jnet.oa.2020-0003
Analysis of the Anatomical Factors
Affecting Ability to Navigate Penumbra
Catheter through Internal Carotid Siphon
Emi Kuriyama, Yoshikazu Matsuda, Takumi Kawaguchi, Rie Yako, and Naoyuki Nakao
Objective:  The  ecacy  and  safety  of  aspiration  thrombectomy  using  Penumbra  catheter  with  acute  large  vessel 
occlusion in the anterior circulation have been reported in previous studies. In some cases, the carotid siphon (CS) is 
elongated,  and  with  this  anatomy, especially  where  there  is  bifurcation  of  the  ophthalmic  artery  (OA),  navigation  of 
Penumbra  catheters  into  distal  internal  carotid  artery  (ICA)  is  interrupted,  which  is  known  as  the  ‘ledge  eect’.  We 
investigate the anatomical characteristics of CS that cause interruption of navigation of the Penumbra catheter.
Methods:  Between January 2015 and March 2018, mechanical thrombectomy using Penumbra 60 was performed on 
51 patients with middle cerebral artery (MCA) or intracranial ICA occlusion. Patients were divided into two groups: The 
‘ledge-eect’ group those in whom the Penumbra catheter was unable to be navigated into the distal ICA through the CS, 
and ‘no ledge-eect’ group those in whom this was possible. The anatomical characteristics of CS, the diameter of ICA, 
diameter of OA, OA/ICA ratio and radius of the CS were evaluated using angiographical imaging.
Results:  The ‘ledge-eect’ group numbered eight cases (17%). Only the value of the CS radius was signicantly smaller 
in the ledge-eect group (p =0.0019), other parameters were not signicantly dierent between the groups. The cuto
radius value was 3.62 mm.
Conclusion:  The most  notable anatomical factor  aecting possibility of  navigation of the  Penumbra catheter through 
the CS was the CS radius. This could be useful information when devices used in mechanical thrombectomy are selected.
Keywords   mechanical thrombectomy, Penumbra catheter, carotid siphon
Recent trials and meta-analyses have proved the ecacy of
mechanical thrombectomy over other types of treatment
of large vessel occlusion in patients with acute ischemic
stroke. Although the eectiveness of stent retrievers has
been reported, Penumbra aspiration catheter (Penumbra
Inc., Alameda, CA, USA) has been suggested as a good
alternative device. Thrombectomy using Penumbra catheter
such as a direct aspiration rst pass technique (ADAPT)
enables recanalization signicantly faster than previously
reported means of thrombectomy.1) There are many recent
reports on adjunctive technique using Penumbra catheter.
For example, Solumbra/Trenumbra techniques are reportedly
useful as methods of reperfusion using a combination of
Penumbra catheter and the stent-retriever (Solitaire FR
device; Medtronic Neurovascular Irvine, CA, USA) or Trevo
(Stryker Neurovascular Fremont, CA, USA).2,3) Continu-
ous aspiration prior to intracranial vascular embolectomy
(CAPTIVE) and stent-retriever-assisted vacuum-locked
extraction (SAVE) technique which use a stent retriever
with continuous aspiration by large-bore catheter are help-
ful to get successful recanalization and have shorter reca-
nalization time.4,5) Proximal balloon occlusion together
with direct thrombus aspiration during stent-retriever
thrombectomy (PROTECT) using additional balloon guid-
ing catheter showed excellent results.6)
Although aspiration catheters with larger catheter lumen
have been developed to improve aspiration power, this also
This work is licensed under a Creative
Commons Attribution-NonCommercial-
NoDerivatives International License.
©2020 The Japanese Society for Neuroendovascular Therapy
Depart ment of Neurosurgery, Wakayama Medical University,
Wakayama, Wakayama, Japan
Received: January 17, 2020; Accepted: February 25, 2020
Corresponding author: Emi Kuriyama. Department of Neurosu r-
gery, Wakayama Medical Universit y, 811-1 Kimiidera, Wakayama,
Wakayama 641-8509, Japan
Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020
Kuriy ama E, et al .
results in a larger prole and more diculty in achieving
distal navigation. Generally, larger Penumbra catheters
often require the use of a coaxial technique to navigate into
the site of the occlusion because of the ‘ledge eect’, being
held up by bifurcation of the ophthalmic artery (OA).7,8)
Even if a coaxial technique was used, in some cases, we
experienced that Penumbra catheter was unable to track to
distal internal carotid artery (ICA) because of the anatomy
of the carotid siphon (CS).
We investigated the anatomical characteristics of the
ICA that render navigation of Penumbra catheters into the
distal ICA through the CS challenging.
Materials and Methods
Patient selection
We retrospectively reviewed clinical characteristics and
radiographic imaging of patients with acute ischemic
stroke who underwent mechanical thrombectomy using
Penumbra system at our institution between January 2015
and March 2018. This study was approved by the
Wakayama Medical University Ethics Committee.
Patients with basilar/vertebral artery occlusion were
excluded from this study. The inclusion criteria at our institu-
tion was as follows: (1) Symptoms were either moderate or
severe, an admission National Institutes of Health Stroke
Scale (NIHSS) score was at least 6. (2) Patients had a small
territorial infarction by non-contrast CT, dened as an Alberta
Stroke Program Early CT Score (ASPECTS) >6. (3) A mod-
ied Rankin Scale (mRS) prior to stroke onset score was 0, 1,
or 2. (4) Patients with ICA and/or middle cerebral artery
(MCA) occlusion identified by radiographic imaging
underwent mechanical thrombectomy using Penumbra 60
(Almeda, CA, USA). (5) Clinical-diusion mismatch existed.
(6) The time from onset to puncture was within 6 hours. If the
patients met the adaptation criteria of intravenous tissue plas-
minogen activator (IV-tPA), they underwent IV-tPA rst.
We divided these patients into two groups, ‘ledge-eect
group’ in whom a Penumbra 60 could not be navigated into
the distal ICA over the CS, and ‘no ledge-eect group’, those
in whom a catheter was able to be navigated over the CS.
In these groups, the patients whose OA could not be identied
on angiography was excluded from radiographic analysis.
The case details were reviewed, including demographic
data, medical history (atrial brillation, hypertension, diabetes
mellitus, hyperlipidemia), history of smoking, comorbidity
(cardiac artery disease, previous cerebral infarction, periph-
eral artery disease), NIHSS and CT-ASPECTs.
Means of conrming diagnoses
Less than 2 on the mRS was considered to be a favorable
outcome. Thrombolysis in Cerebral Infarction (TICI) 2b-3
classication was used for evaluation of successful reca-
nalization. The rst pass eect (FPE) was dened as
achieving a complete recanalization with the rst pass.
Radiographic analysis
We evaluated the anatomical characteristics of CS by
reviewing lateral angiography as follows: diameter of ICA,
diameter of OA, OA/ICA ratio, and radius of CS between
two groups. CS radius was dened as the diameter of the
circle passing the centerline of the CS through three points,
the midpoint of the diameter in the ICA at bifurcation of
the OA, the vertex of the ICA genu, and the proximal C3
(Fig. 1). Smaller CS radius means greater elongation of
the CS. These parameters were measured twice each by
E.K. and Y.M.
Endovascular procedure
All endovascular therapies were performed on the angio-
suite under local anesthesia. Generally, a 9F balloon-guiding
catheter (Optimo, Tokai Medical products, Japan) was
placed in the cervical portion of the ICA. Systematic hepa-
rin was intravenously injected during the procedure to keep
the activating clot time between 250 and 350s. In case with
IV-tPA, only 3000 units of heparin were injected after
sheath insertion. The guiding catheter was continuously
ushed with heparinized saline.
Fig. 1 Lateral  angiography  shows  representative  CS.  Radius  of 
the CS was dened as the diameter (white arrow) of the cir-
cle (white circle)  passing  the  centerline of the  CS  through 
three points: (A) midpoint of the diameter  in ICA at bifurca-
tion of OA, (B) the vertex of ICA genu, and (C) the proximal 
C3  (white  dots).  CS:  carotid  siphon;  ICA:  internal  carotid 
artery; OA: ophthalmic artery
Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020
Abili ty to Na viga te Penum br a Cat heter thro ugh Int erna l CS
Cuto value of the CS radius was calculated by receiver
operating characteristic curve.
Flowchart for exclusion and inclusion of the patients
underwent thrombectomy in our study is shown in Fig. 2.
No ledge-eect group comprised 43 of 51 cases (83%),
and the ledge-eect group comprised eight of 51 cases
(17%). Patient characteristics are shown in Table 1. In all,
24 male patients (56%) were in the no ledge-eect group,
six (76%) were in the ledge-eect group. Mean ages were
75.7 in the no ledge-eect group and 78.6 in the ledge-
eect group. Risk factors and comorbidity were not signi-
cantly dierent between the two groups. Mean NIHSS
scores were 17 and 15, respectively. Acute stroke severity
assessed by the NIHSS and ASPECTs at presentation was
not signicantly dierent between the two groups.
The site of occlusion of the intracranial ICA was 18.6%
(8/43) in the no ledge-eect group and 25% (2/8) in the
ledge-eect group. The occlusion of the rst segment of
MCA (M1) was 76.7% (33/43) in the no ledge-eect group
Penumbra 60 was navigated just proximal to the throm-
bus over intermediate catheter, Penumbra 3Max (Alameda,
CA, USA) or Marksman catheter (Covidien, Irvine, CA,
USA) and a Chikai 0.014 inch microguidewire (Asahi
Intecc, Aichi, Japan). After positioning, the catheters and
microguidewires were withdrawn. After no retrograde
blood was identied, pump aspiration was performed. Pen-
umbra 60 was gently withdrawn under continuous aspira-
tion. If this procedure was unsuccessful, the same procedure
was tried once more. In unsuccessful aspiration proce-
dures, use of a stent retriever was considered. In case, the
Penumbra 60 was unable to be navigated over the CS,
another method, such as using a stent retriever, was also
Statistical analysis
ImageJ software (National Institutes of Health, USA) was
used for anatomical measurements. JMP pro13 software
(SAS Institute Inc., Cary, NC, USA) was used for statistical
analysis. The chi-square homogeneity test and Student’s
t-test were used to compare categorical variables. P value
of <0.05 was considered to be statistically signicant.
Fig. 2 Flowchart for exclusion and inclusion of the patients underwent thrombectomy in our study
Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020
Kuriy ama E, et al .
Trevo and/or Revive [Codman, Raynham, Massachusetts,
USA]) to achieve recanalization because of the diculty
for navigation of Penumbra 60. The ADAPT method using
3MAX was performed in the latter one case. IV-tPA was
conducted 18.6% (8/43, no ledge-eect group) and 12.5%
(1/8, ledge-eect group), respectively. The dierence of
inner intermediate catheters of Penumbra 3MAX and
Marksman demonstrates no signicant dierence in track-
ability of Penumbra 60. Mean pass times to recanalization
were 2.0 in both groups. FPE was achieved in 34.5%
(15/43) and 37.5% (3/8), respectively (p = 0.33). Results
are shown in Table 2.
The rates of successful recanalization (TICI grade 2b)
were 86.0% (37/43, no ledge-eect group) and 100% (8/8,
and 50% (4/8) in the ledge-eect group, the occlusions of
the second segment of MCA (M2) were 4.7% (2/43) and
25% (2/8), respectively. The tandem occlusion was 9.3%
(4/43) in the no ledge-eect group and 12.5% (1/8) in the
ledge-eect group. There was one case (12.5%) with
embolism from carotid artery occlusion requiring carotid
artery stenting (CAS) in the ledge-eect group. There were
four cases (9.3%) with embolism due to carotid artery ste-
nosis or occlusion requiring CAS or percutaneous translu-
minal angioplasty (PTA) in the no ledge-eect group. The
simple aspiration method was used in 23.3% (10/43) of the
no ledge-eect group and 12.5% (1/8) in the ledge-eect
group. In the former group, other ve5 cases with M1 dis-
tal occlusion required additional stent retrievers (Solitaire,
Table 1  Characteristics of patients
No ledge-effect group Ledge-effect group p
No. of patients (%) 43 (83) 8 (17) 0.3
Age (years) (SD) 75.7 ± 1.8 78.6 ± 4.4 0.94
Sex, male (%) 24 (56) 6 (75) 0.43
Af/pAf (%) 28 (65) 3 (38) 0.27
Risk factors (%) Hypertension 26 (60) 6 (75) 0.69
Hyperlipidemia 7 (16) 3 (38) 0.18
Diabetes mellitus 8 (19) 4 (50) 0.08
(Ex-)smoker 5 (31) 1 (13) 1
Comorbidity (%) CAD 9 (19) 2 (20) 0.62
Previous CI 12 (28) 2 (20) 1
CKD 2 (4) 0 (0) 1
PAD 1 (2) 0 (0) 1
NIHSS (mean) 17 15 0.29
CT-ASPECTs (mean) 9 9 0.85
Af: atrial fibrillation; ASPECTs: Alberta Stroke Program Early CT Score; CAD: cardiac artery disease; CI: cerebral infarction;
PAD: peripheral artery disease; pAf: paroxysmal atrial fibrillation; NIHSS: National Institutes of Health Stroke Scale
Table 2  Sites of occlusion and methods for mechanical thrombectomy
No ledge-effect group Ledge-effect group p
ICA occlusion 8 2 0.25
MCA occlusion M1 33 4 0.25
M2 2 2
Tandem occlusion 4 1 1
Side Left 26 2 0.06
IV-tPA 8 1 1
Inner catheter 3MaxACE 6 2 0.76
Marksman 35 6
Others 2 0
Other system Solitare 14 4 0.04
(Stent) Trevo 7 4
Revive 10 0
None 10 1
Number of passes 2 2 0.79
Number of FPE 15 3 0.33
FPE: first pass effect; ICA: internal carotid artery; IV-tPA: intravenous tissue plasminogen activator; MCA: middle
cerebral artery
Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020
Abili ty to Na viga te Penum br a Cat heter thro ugh Int erna l CS
distal ICA. Generally, ledge eect is reported to render
navigation of the catheter into the distal ICA both chal-
lenging and time-consuming.7) Therefore, we evaluated
CS anatomy inuencing the ledge eect and focused on
the diameter of ICA, OA, OA/ICA ratio, and radius of
CS for the following reasons.
Diameter of ICA
The average diameter of the cavernous part of the ICA was
reported to be 3.68 mm on the right, 3.85 mm on the left.9)
In the no ledge eect and ledge-eect group, these aver-
ages were 4.53 mm and 4.06 mm, respectively. It was
slightly larger than that previously reported. Small diame-
ter of ICA was assumed to make navigation of the Penum-
bra catheter challenging, but in this study, the average ICA
diameter was not signicantly small.
Diameter of OA
A larger diameter of the OA would create a larger ledge
eect to advance the Penumbra catheter through the CS.
OA is the rst branch of the ICA immediately after it arises
from the cavernous sinus and enters the cranial cavity. Its
diameter ranges between 0.7 and 1.8 mm.10,11) The average
OA diameter in this study was not signicantly dierent
between groups: 1.08 and 1.11 mm, reference value range.
OA could be measured except in four cases and be located
in supraclinoid segment of the ICA. Recanalization was
not necessary in one of the cases. OA was not detected in
the other three cases with successful recanalization.
ledge-eect group), respectively. (p = 0.22). Puncture to
recanalization times were 61.0 and 73.5 minutes in each
group (p = 0.34). Favorable outcome was 39.5% and 37.5%
(17/43 and 3/8), considered to be without signicant dier-
ence (Table 3).
The radius of CS in ledge-eect group was signicantly
smaller than that in the no ledge-eect group (p = 0.0019).
The other parameters, diameter of ICA, OA, and OA/ICA
ratio, between the two groups showed no signicant dier-
ence (Table 4). Cuto value of the radius was 3.62 mm.
A representative case, a 72-year-old female, with occlu-
sion of ICA top had small CS radius and was in the ledge-
eect group (Fig. 3). Small radius indicates that the vertex
of CS is severe. First, Penumbra 60 with Penumbra 3MAX
intermediate catheter into 9F balloon guide catheter was
applied. It failed to be passed through CS because of the
ledge eect. Marksman microcatheter was navigated to the
distal thrombus through Penumbra and stent retriever
(Trevo 4 × 20 mm) was deployed across the thrombus and
the microcatheter was removed completely. After waiting
for 5 minutes, continuous aspiration was started and the
stent was retrieved into the aspiration catheter. After two
passes of same the procedure, full recanalization was
shown on nal angiography.
In our study, the CS radius was independent factor in
unsuccessful navigation of Penumbra catheter into the
Table 3  Outcome of procedure
No ledge-effect group Ledge-effect group p
TICI 3 19 6 0.22
2b 18 2
2a 4 0
10 0
02 0
TICI 2b–3 (%) 37(86) 8(100) 1
Puncture to recanalization (min) 61 73.5 0.34
mRS 0–2 at 30 days (%) 17(39.5) 3(37.5) 1
mRS: modified Rankin Scale; TICI: Thrombolysis in Cerebral Infarction
Table 4 Anatomical results
No ledge-effect group Ledge-effect group p
Diameter of ICA (mm) 4.53 4.06 0.11
Diameter of OA (mm) 1.08 1.11 0.78
OA/ICA ratio 0.22 0.23 0.11
Radius (mm) 4.19 2.92 0.0019
ICA: internal carotid artery; OA: ophthalmic artery
Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020
Kuriy ama E, et al .
ICA at bifurcation of OA, vertex of the genu of ICA, and
midpoint of the proximal C3. Radius of the CS means rel-
atively the tortuosity. Smaller radius shows severe elonga-
tion of the vessel which can make advancement of a
catheter challenging. In our study, only this parameter had
signicant dierence between the two groups. It proved
the bending of the CS in the ledge-eect group aected
feasibility to navigate Penumbra over CS.
Greater dierence in diameters between inner diameter
of Penumbra 60 and outer diameter of intermediate cath-
eter (Penumbra 3MAX or Marksman microcatheter)
causes greater ledge eect. The coaxial advancement
technique was reported previously. If a microguidewire is
just used for advancing the Penumbra 60, the gap between
the two devices is expected to be large and this could
OA/ICA ratio
If the OA/ICA ratio is smaller, it means a relatively smaller
diameter of OA. Smaller ratio is expected to facilitate the
navigation of Penumbra catheter into distal ICA through
CS. In our study, however, there was no dierence between
the two groups.
Radius of CS
Previous reports on radius of ICA reported that bending of
the CS resembles the circle. Chi Zhang et al. (2013)
reported geometric classication of the CS and dened the
osculating circle (OC) as the curvature radius tting to the
bend of centerline of CS.12–14) We dened radius of the CS
as the diameter of the circle passing the centerline of CS
through three points including midpoint of the diameter in
Fig. 3 (A) Representative case, a 72-year-old female, with small radius of CS (3.54 mm) and ledge-eect group is shown. 
Small radius indicates severe bending of the CS. Diameter of ICA is 5.46 mm, diameter of OA is 0.94 mm, and OA/
ICA ratio is 0.17. (B) Diagnostic angiography shows the occlusion of ICA top. (C) Stent retriever Trevo 4 × 20 mm was 
deployed across the thrombus. Penumbra catheter was navigated just proximal of Trevo. Trenumbra was conducted. 
(D) Two  passes of  the  same  procedure showed full  recanalization  on  nal angiography. CS: carotid siphon;  ICA: 
internal carotid artery; OA: ophthalmic artery
Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020
Abili ty to Na viga te Penum br a Cat heter thro ugh Int erna l CS
result in diculty controlling the catheter. The coaxial
advancement technique was used to reduce the gap
between the inner diameter of Penumbra 60 and the outer
diameter of intermediate catheter so to allow navigation
of the Penumbra 60 into distal portion over CS.15) How-
ever, in our study, the dierence of intermediate catheter
was not signicant. The outer diameter of Penumbra
3MAX is 0.050 inch. On the other hand, that of Marks-
man microcatheter is 0.037 inch. This difference of
0.013 inch was negligible for navigation of Penumbra 60
through CS. When comparing the Penumbra 60 with the
intermediate catheter, the ledge eect (inner diameter of
Penumbra 60 [0.060 inch] – outer diameter of intermedi-
ate catheter), is 0.010 inch for Penumbra 3Max and 0.023
inch for Marksman microcatheter. This dierence could
be negligible from our result.
Previous reports detailed other methods of navigation of
Penumbra catheter through CS smoothly.
One method of navigating the Penumbra catheter
through the CS is by steam-shaping the tip of the Penum-
bra catheter. It allows easy navigation through the CS. In
the previous reports, there were three types of “sim-
ple-curved” steam shaping; a 45° curve, a 90° curve, and
J-shape curve. In most cases, advancement is more
smoothly achieved using a steam-shaped catheter tip with
a 45° curve. However, in some cases with extreme tortuos-
ity or severe atherosclerotic stenosis, a 90° curve or J-shape
can be occasionally used.16) Therefore, if tortuosity of CS
is severe, although in our study steam-shaping was not per-
formed, it may be better to shape the Penumbra catheter
before puncture. The disadvantage of this proposal is that it
is time-consuming and shaping might induce the malfor-
mation of tip of the Penumbra catheter.
Another means of navigating the Penumbra catheter
through the CS is by the so-called ‘buddy wire’ technique.
It means introducing a supportive microguidewire. This
can be used to support the Penumbra catheter and provide
added stability. This method is usually used for percutane-
ous coronary intervention (PCI), CAS, stenting of the ver-
tebral artery, and other endovascular therapies.17–19) Double
wires might enable reduction of the gap between microgu-
idewire and microcatheter and improve usability of the
catheter by reducing the ledge eect.
More recently, Sofia Non-wire Advancement tech-
niKE (SNAKE) is reported benefit for mechanical
thrombectomy. Because the distal end of the Sofia cath-
eter is extremely soft, it could be safely advanced into
the intracranial vessels without any microcatheter or
microguidewire. This technique may be one method to
overcome the challenging of the ledge effect.20)
Successful recanalization with TICI 2b or 3 was
achieved in 75–87% with ADAPT in other reports.21) The
reperfusion rate of TICI2b or 3 in no ledge eect and
ledge-eect group was 86% and 100%, respectively. These
results were similar to those of previous reports.22) The
mean reperfusion times were 61.0 and 73.5 minutes,
respectively (p = 0.33). There was no dierence in pass
times or in treatment for cervical lesion between both
groups. Ledge-eect group had tendency for longer reper-
fusion time. Consequently, change of devices in cases of
unsuccessful navigation of Penumbra catheter through CS
may be required, and more patients in the ledge-eect
group would result in dierence between these groups.
In this study, in unsuccessful navigation through CS,
correct selection of devices could reduce reperfusion time.
Furthermore, aspiration catheters with larger lumen that
could improve power of aspiration are under developed.
These catheters could produce greater ledge eect, how-
ever. Therefore, this study is meaningful for mechanical
thrombectomy using Penumbra catheters.
A limitation of our study is that, because of limited
resources, this was a retrospective study and it was con-
ducted in a single institution. Actually CS radius would
rely on a completely orthogonal view of the CS but lat-
eral angiograph is not completely orthogonal to the skull.
To reduce the inuence, strict lateral angiography with
the acoustic meatus at same level was obtained. The tor-
tuosity of femoral artery and arch of aortic artery might
aect navigation of Penumbra catheter to thrombus.
However, ination of balloon guiding catheter not only
stop ow of ICA but also support anchoring ability for
navigation of Penumbra catheter. As a results, this ina-
tion of balloon could minimize elongation of femoral
artery and aortic arch.
The main factor in ability to navigate a Penumbra catheter
through the CS was the radius of the CS. This measure-
ment could be helpful for selection of devices for mechan-
ical thrombectomy.
Disclosure Statement
There is no conict of interest for the rst author and
Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020
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Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020Journal of Neuroendovascular Therapy Advance Published Date: March 13, 2020
... Many studies have reported catheters getting caught on the "ophthalmic ledge"-the point at which the ophthalmic artery takes off from the carotid siphon (20,58). This is commonly referred to as the "ledge effect" (59)(60)(61) and can also be seen as catheters get stuck at the posterior communicating artery or the anterior choroidal artery ostia. This challenge is particularly relevant for large-bore aspiration catheters where a larger difference between the inner diameter of the outer catheter and the inner catheter results in a step that catches at bends or branching vessels. ...
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In-vitro neurovascular models of large vessel occlusions (LVOs) causing acute ischemic stroke (AIS) are used extensively for pre-clinical testing of new treatment devices. They enable physicians and engineers to examine device performance and the response of the occlusion to further advance design solutions for current unmet clinical needs. These models also enable physicians to train on basic skills, to try out new devices and new procedural approaches, and for the stroke team to practice workflows together in the comfort of a controlled environment in a non-clinical setting. Removal of the occlusive clot in its entirety is the primary goal of the endovascular treatment of LVOs via mechanical thrombectomy (MT) and the medical treatment via thrombolysis. In MT, recanalization after just one pass is associated with better clinical outcomes than procedures that take multiple passes to achieve the same level of recanalization, commonly known as first pass effect (FPE). To achieve this, physicians and engineers are continually investigating new devices and treatment approaches. To distinguish between treatment devices in the pre-clinical setting, test models must also be optimized and expanded become more nuanced and to represent challenging patient cohorts that could be improved through new technology or better techniques. The aim of this paper is to provide a perspective review of the recent advancements in the in-vitro modeling of stroke and to outline how these models need to advance further in future. This review provides an overview of the various in-vitro models used for the modeling of AIS and compares the advantages and limitations of each. In-vitro models remain an extremely useful tool in the evaluation and design of treatment devices, and great strides have been made to improve replication of physiological conditions. However, further advancement is still required to represent the expanding indications for thrombectomy and thrombolysis, and the generation of new thrombectomy devices, to ensure that smaller treatment effects are captured.
Larger microcatheters are being used with increasing frequency in routine neurovascular procedures. Navigating catheters safely and effectively to the target intracranial vessels can be a challenge when using conventional 0.014″ microwires. A new family of 0.024″ Aristotle 24 microwires (Scientia Vascular, West Valley City, UT) specifically designed for intracranial navigation were recently introduced. These microwires offer significant technical advantages over the standard 0.014″ microwires, including a reduced ledge gap, improved torquability and support, and overall safety. This video case series contains several illustrative cases to demonstrate the features of the novel Aristotle 24 microwire for use in endovascular neurointervention.
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Purpose Stent retriever-based mechanical thrombectomy (MT) for emergent large vessel occlusions (ELVO) is often complicated by thrombus fragmentation causing distal embolization and embolization to new vascular territories. Well-established embolic protection approaches include proximal flow arrest and distal aspiration techniques during stent retriever maneuvers. Aiming at the reduction of thrombus fragmentation during MT we evaluated a technical approach combining proximal balloon occlusion together with direct thrombus aspiration during MT: the PROTECT technique. Methods We performed a case-control study comparing the PROTECT technique with sole distal aspiration during MT regarding technical and procedural parameters, n=200 patients with ELVO of either the terminus of the internal carotid artery or the proximal middle artery were included. Results PROTECT resulted in a shorter procedure time (29 vs 40 min; P=0.002), in a higher rate of successful recanalizations (100% vs 78%; P=0.001) and a higher rate of complete reperfusions (70% vs 39%; P<0.001) compared with sole distal aspiration during MT. Conclusion The PROTECT technique is a promising new approach to significantly reduce thrombus fragmentation and, hence distal embolization during MT. This safe and efficient technique needs to be validated in larger trials to confirm our results.
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The petrous and cavernous parts of internal carotid artery (ICA) are obscure and are not readily accessible to observation/imaging. These parts have broad biological and medical interest because of their peculiar shape. Given the their clinical importance and the scarce data available based mostly on imaging, the present study was aimed at studying these parts of ICA by dissection. The study was carried out on 56 ICAs obtained from embalmed adult cadavers and 10 ICAs from five fetuses. The foetal ICAs were studied in situ. The morphometric analysis of the adult ICA was done after its removal from cranial cavity to gain an insight into the geometry of the vessel, i.e., length, various bends, and diameters at various locations. ICAs in fetuses ran a relatively straighter course taking gentle curves at three positions (two intrapetrous, one cavernous). Adult ICAs were more tortuous and exhibited greater variability in length and angulations. The length of respective portions of the ICA correlate negatively with the measure of angles. The angles in the petrous and cavernous parts were positively correlated to each other. The carotid siphon was positively, highly significantly correlated to other angles. Longer vessels are more tortuous with acute bends. An acute carotid siphon is an indication of more tortuous ICA. The findings of the present study have created a reference data of unsuspected adult population and has potential implications for studying cause/effect relationship of vessel geometry and hemodynamic factors.
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Intravenous recombinant tissue plasminogen activator had been the only approved treatment for acute ischemic stroke since its approval in 1995. However, the restrictive time window, numerous contraindications, and its low recanalization rate were all limitations of this modality. Under those circumstances, endovascular stroke therapy went through a great evolution during the past two decades of intravenous thrombolysis. The results of the 2013 randomized trials for endovascular stroke therapy were neutral, although they were limited by insufficient imaging screening at enrollment, early-generation devices with less efficacy, and treatment delays. Huge progress was made in 2015, as there were five randomized clinical trials which all demonstrated the safety and efficacy of endovascular stroke treatment. Despite differences in detail patient enrollment criteria, all 5 trials employed key factors for good functional recovery; (1) screening with non-invasive imaging to identify the proximal occlusion and exclude a large infarct core, (2) using highly effective modern thrombectomy devices mainly with stent retriever, and (3) establishment of a fast workflow to achieve effective reperfusion. The results of those trials indicate that modern thrombectomy devices can allow for faster and more effective reperfusion, which can lead to improved clinical outcomes compared to intravenous thrombolysis alone. These advances in mechanical thrombectomy are promising in the global fight against ischemic stroke-related disability and mortality. Two current mainstreams among such mechanical thrombectomy techniques, “stent retriever thrombectomy” and “direct clot aspiration”, are the topic of this review. Stent retriever thrombectomy using Solitaire and Trevo retriever will be firstly discussed. And, the commonalities and the differences between two major clot aspiration thrombectomy techniques; a direct aspiration first pass technique (ADAPT) and forced arterial suction thrombectomy (FAST), will be additionally explained. Finally, details regarding the combination of direct clot aspiration and stent retriever thrombectomy, the switching strategy and the Solumbra technique, will be described.
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Background: Endovascular techniques for treatment of large vessel occlusions (LVO) in patients with acute ischemic stroke (AIS) have advanced in recent years. We report a multicenter experience using a combined aspiration and stent retriever technique for mechanical thrombectomy (MT). Methods: We retrospectively analyzed 32 consecutive MT patients using a novel, combined approach of Stent retriever Assisted Vacuum-locked Extraction (SAVE) by 3 operators at 3 stroke centers. Primary endpoint was successful first-pass reperfusion with a modified Thrombolysis in Cerebral Infarction (mTICI) score of 3. Secondary endpoints were number of passes, time from groin puncture to reperfusion, embolization to new territories (ENT), postinterventional symptomatic intracranial hemorrhage (sICH) and clinical outcome at discharge. Results: First-pass mTICI 3 reperfusion was achieved in 23 out of 32 patients (72%) with a mean groin puncture to reperfusion time of 36.0 min ± 15.8 and mTICI 3 was accomplished in 25 out of 32 cases (78%) with a maximum of 3 attempts. Successful reperfusion (mTICI ≥ 2b) was achieved in all patients (100%) with a mean time from groin puncture to reperfusion of 44.5 min ± 25.8 and an average of 1.2 ± 0.7 attempts. The rate of ENT was 0% and 1 patient with sICH after MT died on postoperative day 4. At discharge, the median National Institutes of Health Stroke Scale (NIHSS) score was 4 (range 0-17) and favorable neurological outcome by the modified Rankin score (mRS ≤ 2) was achieved in 19 out of 32 patients (59%). Conclusion: SAVE is fast and appears to be very effective in terms of first-pass complete reperfusion in patients with LVO.
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Background: A closed-cell stent called Enterprise has been used for stent-assisted coil embolization of cerebral aneurysms. The Enterprise stent tends to cause kinks and vessel wall malposition in curved vessels and may cause thromboembolic complications. We evaluated vessel wall apposition of a new closed-cell stent, Enterprise 2, compared with a previous Enterprise stent, using curved vascular silicone models. Methods: The Enterprise or Enterprise 2 stent was deployed in curved vascular models with various radii of approximately 5 to 10 mm. Stent deployment was performed 25 times in each stent. A push-pull technique was used to minimize incomplete wall apposition. To evaluate conformity of stents, gaps between a stent and a vessel wall were measured. Results: The gap ratio (gap / a wall diameter) was 15 % ± 17 % (mean ± standard deviation) and 41 % ± 15 % with the Enterprise 2 stent and the Enterprise stent, respectively. Taking gap ratios and radii of vessel curvature into consideration, the Enterprise 2 stent had significantly better wall apposition than the Enterprise stent (p = 0.005). In the same radius of vessel curvature, the Enterprise 2 stent had approximately half of the gap compared with the Enterprise stent. There were no significant differences in vessel straightening effects between the two stents. Conclusions: The Enterprise 2 stent has better wall apposition in curved vessels than the Enterprise stent. The gap between a vessel wall and the Enterprise 2 stent is approximately half that of the Enterprise stent. However, gaps and kinks are still present in curved vessels with a small radius. Caution should be taken for kinks and malposition in acutely curved vessels, such as the siphon of the internal carotid artery.
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Anatomy of ophthalmic artery has been thoroughly studied and reviewed in many anatomical and surgical textbooks and papers. Issues of interest are its intracranial and extracranial course, its branches, its importance for vision, and its interaction with various intracranial pathologies. Improvement of our understanding about pathophysiology of certain diseases like aneurysm formation, central retinal artery occlusion, and retinoblastoma and also invention of new therapeutic modalities like superselective catheterization, intra-arterial fibrinolysis, and intra-arterial chemotherapy necessitate a reappraisal of its anatomy from a clinical point of view. The aim of this review is to examine clinical anatomy of ophthalmic artery and correlate it with new diagnostic and therapeutic applications.
Background The development of new revascularization devices has improved recanalization rates and time but not clinical outcomes. We report our initial results with a new technique utilizing a direct aspiration first pass technique with a large bore aspiration catheter as the primary method for vessel recanalization. Methods A retrospective evaluation of a prospectively captured database of 37 patients at six institutions was performed on patients where the ADAPT technique was utilized. The data represent the initial experience with this technique. Results The ADAPT technique alone was successful in 28 of 37 (75%) cases although six cases had large downstream emboli that required additional aspiration. Nine cases required the additional use of a stent retriever and one case required the addition of a Penumbra aspiration separator to achieve recanalization. The average time from groin puncture to at least Thrombolysis in Cerebral Ischemia (TICI) 2b recanalization was 28.1 min, and all cases were successfully revascularized. TICI 3 recanalization was achieved 65% of the time. On average, patients presented with an admitting National Institutes of Health Stroke Scale (NIHSS) score of 16.3 and improved to an NIHSS score of 4.2 by the time of hospital discharge. There was one procedural complication. Discussion This initial experience highlights the fact that the importance of the technique with which new stroke thrombectomy devices are used may be as crucial as the device itself. The ADAPT technique is a simple and effective approach to acute ischemic stroke thrombectomy. Utilizing the latest generation of large bore aspiration catheters in this fashion has allowed us to achieve excellent clinical and angiographic outcomes.
Background Neurointerventional surgeries (NIS) benefit from supportive endovascular constructs. Sofia is a soft-tipped, flexible, braided single lumen intermediate catheter designed for NIS. Sofia advancement from the cervical to the intracranial circulation without a luminal guidewire or microcatheter construct has not been described. Objective To evaluate the efficacy and safety of the new Sofia Non-wire Advancement techniKE (SNAKE) for advancement of the Sofia into the cerebral circulation. Methods Consecutive patients who underwent NIS using Sofia were identified. Patient information, SNAKE use, and patient outcome were determined from electronic medical records. Sofia advancement to the cavernous internal carotid artery or the V2/V3 segment junction of the vertebral artery was the primary outcome measure. Secondary outcomes included arterial vasospasm and arterial dissection. Results 263 Patients (181 females, 69%) who underwent a total of 305 NIS using Sofia were identified. SNAKE (SNAKE+) was used in 187 procedures (61%). Two hundred and ninety-three procedures (96%) were technically successful, which included 184 SNAKE+ NIS and 109 SNAKE− NIS. Primary outcome was achieved in all SNAKE+ procedures, but not in five SNAKE− procedures (2%). No arterial dissections were identified among 305 interventions. In the intracranial circulation, a single SNAKE+ patient (0.5%) had non-flow limiting arterial vasospasm involving the petrous internal carotid. Three SNAKE+ patients (1.6%) and one SNAKE− patient (0.8%) demonstrated external carotid artery branch artery vasospasm during dural arteriovenous fistula or facial arteriovenous malformation treatment. Conclusion SNAKE is a safe and effective technique for Sofia advancement. Sofia is a highly effective and safe intermediate catheter for a variety of NIS.
Background Modern stent retriever-based embolectomy for patients with emergent large vessel occlusion improves outcomes. Techniques aimed at achieving higher rates of complete recanalization would benefit patients. Objective To evaluate the clinical impact of an embolectomy technique focused on continuous aspiration prior to intracranial vascular embolectomy (CAPTIVE). Methods A retrospective review was performed of 95 consecutive patients with intracranial internal carotid artery or M1 segment middle cerebral artery occlusion treated with stent retriever-based thrombectomy over an 11-month period. Patients were divided into a conventional local aspiration group (traditional group) and those treated with a novel continuous aspiration technique (CAPTIVE group). We compared both early neurologic recovery (based on changes in National Institute of Health Stroke Scale (NIHSS) score), independence at 90 days (modified Rankin score 0–2), and angiographic results using the modified Thrombolysis in Cerebral Ischemia (TICI) scale including the TICI 2c category. Results There were 56 patients in the traditional group and 39 in the CAPTIVE group. Median age and admission NIHSS scores were 78 years and 19 in the traditional group and 77 years and 19 in the CAPTIVE group. Median times from groin puncture to recanalization in the traditional and CAPTIVE groups were 31 min and 14 min, respectively (p<0.0001). While rates of TICI 2b/2c/3 recanalization were similar (81% traditional vs 100% CAPTIVE), CAPTIVE offered higher rates of TICI 2c/3 recanalization (79.5% vs 40%, p<0.001). Median discharge NIHSS score was 10 in the traditional group and 3 in the CAPTIVE group; this difference was significant. There was also an increased independence at 90 days (25% traditional vs 49% CAPTIVE). Conclusions The CAPTIVE embolectomy technique may result in higher recanalization rates and better clinical outcomes.
Purpose: To compare rates of symptomatic intracranial hemorrhage (SICH) and good clinical outcome at 90 days in patients with ischemic strokes from anterior circulation emergent large vessel occlusions (ELVO) treated with mechanical thrombectomy using either Solumbra or A Direct Aspiration first-Pass Thrombectomy (ADAPT) techniques. Methods: We compared clinical characteristics, procedural variables, and clinical outcomes in patients with anterior circulation ELVOs treated with mechanical thrombectomy using either a Solumbra or ADAPT technique at our institution over a 38-month period. SICH was defined using the SITS-MOST criteria. A good clinical outcome was defined as a modified Rankin Scale score of 0-2 at 90 days. Results: One hundred patients were included, 55 in the Solumbra group and 45 in the ADAPT group. Patients in the ADAPT group had higher National Institutes of Health Stroke Scale (NIHSS) (19.2 vs 16.8, p=0.02) and a higher proportion of internal carotid artery terminus thrombi (42.2% vs 20%, p=0.03) than patients in the Solumbra group. Patients in the ADAPT group had a trend toward a lower rate of SICH than patients in the Solumbra group (2.2% vs 12.7%, p=0.07). Patients in the ADAPT group had a significantly higher rate of good clinical outcome at 90 days than patients in the Solumbra group (55.6% vs 30.9%, p=0.015). Use of the ADAPT technique (OR 6 (95% CI 1.0 to 31.2), p=0.049) was an independent predictor of a good clinical outcome at 90 days in our cohort. Conclusions: In our cohort, the ADAPT technique was associated with significantly higher good clinical outcomes at 90 days in patients with acute ischemic stroke due to anterior circulation ELVOs treated with mechanical thrombectomy.