NEW METHODS: Clinical Endoscopy
Prospective evaluation of a new biflanged metal stent for the
treatment of pancreatic fluid collections (with videos)
Shuntaro Mukai, MD,1 Takayoshi Tsuchiya, MD,1 Takao Itoi, MD, FASGE,1 Shujiro Tsuji, MD,1
Reina Tanaka, MD,1 Ryosuke Tonozuka, MD,1 Yuichi Nagakawa, MD,2 Kazuhiko Kasuya, MD,2
Masaaki Shimatani, MD,3 Atsushi Sofuni, MD1
Tokyo, Japan
Background and Aims: EUS-guided transluminal drainage (EUS-TD) and sequential direct endoscopic
necrosectomy (DEN) for pancreatic fluid collections (PFCs) by using a dedicated biflanged metal stent
(BFMS) has been reported as a useful alternative to using plastic stents or a conventional metal stent. However,
current dedicated BFMSs have limitations. Recently, a new BFMS with solidly constructed biflanges and various
stent lengths matched to the PFC condition has been developed. Herein, we prospectively evaluated this new
BFMS for the treatment of PFCs.
Methods: From July 2015 to July 2016, EUS-TD by using the new BFMS was performed in 12 patients for PFCs
(4 patients with pancreatic pseudocysts, 8 patients with walled-off necrosis). When clinical resolution could not be
achieved, DEN was performed the following day.
Results: The stent was deployed successfully with a median procedure time of 16 minutes (range 11-24
minutes) and with no procedure-related adverse events in any patients (12/12, 100%). DEN via the stent
was achieved in all patients in whom they were attempted (4/4,100%). Spontaneous stent migration or stent
dislocation during DEN was not observed in any patients. Two WON patients died from spontaneous
pseudoaneurysm rupture and multiple organ failure. The PFCs in the other 10 patients completely resolved,
and later the stent was removed with no difficulty in 9 patients after a median time of 48 days (range 30-180
days).
Conclusions: The new BFMS is technically feasible and safe for the treatment of PFCs. (Clinical trial registration
number: UMIN000021347.)
(footnotes appear on last page of article)
EUS-guided transluminal drainage (EUS-TD) and
sequential direct endoscopic necrosectomy (DEN) for
pancreatic fluid collections (PFCs) using a dedicated
biflanged metal stent (BFMS) has been reported as a
useful alternative to using 1 or more plastic stents or a
conventional self-expandable biliary metal stent.1-7
Current dedicated BFMSs are divided into lumenapposing metal stents (LAMSs) and flared metal stents
(FMSs).8 The LAMS has limitations in the case of a
longer length between the gastric wall and the cyst
wall because the stent length between biflanges is 1
cm. In contrast, the FMS has limitations in terms of a
weak lumen-apposing force, leading to stent migration
because of the flared flanges. Recently, a new BFMS
with solidly constructed biflanges and various stent
lengths matched to the PFC condition has been developed. Herein, we prospectively evaluated this new
BFMS for the treatment of PFCs.
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Volume 86, No. 1 : 2017 GASTROINTESTINAL ENDOSCOPY 203
New biflanged metal stent for treatment of pancreatic fluid collections
Mukai et al
by using a 6F electrocautery dilator and a 4-mm to 6-mm
dilating balloon. Finally, a stent was deployed under EUS,
fluoroscopic, and endoscopic guidance (Fig. 2; Video 1,
available online at www.giejournal.org). The placement of
a 5F or 6F nasocystic catheter for irrigation was left to the
operator’s discretion. Clinical resolution was defined as
the disappearance of symptoms, improvement in
inflammation, and the shrinkage of the PFC cavity on CT.
When clinical resolution could not be achieved within a
few days (usually 3-7 days) after EUS-TD, DEN was performed. A standard upper endoscope was directly advanced
via the stent. Necrotic tissue was removed by using a snare
forceps during CO2 insufflation (Fig. 3; Video. 2, available
online at www.giejournal.org).
Figure 1. The new fully covered biflanged metal stent (HANARO stent,
MI Tech, Seoul, Korea).
METHODS
The new BFMS (HANARO stent, MI Tech, Seoul,
Korea) is a fully covered metal stent designed for
EUS-TD, with a 14-mm-diameter lumen and a 20-mm
or 30-mm-long body (Fig. 1). This stent is made of a
self-expanding nitinol wire and is fully covered with a silicon membrane to minimize leakage. Both the proximal
and distal anchor flanges are designed to hold tissue
layers tight and prevent stent migration. The diameter
of a flange is 24 mm. The large lumen diameter yields
effective drainage, and the short body length and the
high stability enable the easy insertion of a standard upper endoscope into the cyst for DEN. The delivery
sheath is 10.2F, and the delivery system is almost identical to that of a conventional biliary metal stent.
Our eligibility criteria for EUS-TD by using the new BFMS
in a pilot observational study were as follows: (1) the size of
the pancreatic pseudocyst (PPC) or walled-off necrosis
(WON) is >30 mm, and (2) the distance between the GI tract
and the cavity measured under EUS is <20 mm. EUS-TD by
using the new BFMS was performed in 12 consecutive
patients who conformed to our eligibility criteria for PFCs
(ie, 4 patients with PPCs, 8 patients with WON)9 between
July 2015 and July 2016 at Tokyo Medical University
Hospital. The clinical results were assessed prospectively.
This study was approved by our institutional review
board, and written informed consent was obtained from
all patients. This study was registered with the University
Hospital Medical Information Network Clinical Trials
Registry (UMIN000021347). Data were collected in accordance with the provisions of the Declaration of Helsinki.
All procedures were performed by using a conventional
curved linear array echoendoscope (GF-UCT240 or GFUCT260; Olympus Medical Systems, Tokyo, Japan). A 19gauge, FNA needle was used to puncture the PFC under
EUS guidance. A 0.025-inch guidewire was inserted into
the cyst to form several loops. Then, the tract was dilated
204 GASTROINTESTINAL ENDOSCOPY Volume 86, No. 1 : 2017
RESULTS
The patients and treatment results for PFCs are shown in
Table 1. The stent was deployed successfully with a median
procedure time of 16 minutes (range 11-24 minutes) and
with no procedure-related adverse events in any patients.
Insertion of a standard upper endoscope through the stent
and DEN were achieved in all patients in whom they were attempted. Spontaneous stent migration or stent dislocation
during the DEN procedures was not observed in any patients. Two patients with WON died from spontaneous pseudoaneurysm rupture occurring between the endoscopic
necrosectomy sessions and from multiple organ failure,
although hemostasis was achieved by coil embolization.
The PFCs completely resolved in the other 10 patients,
and later the stent was removed with no difficulty in 9 patients after a median time of 48 days (range 30-180 days)
except in 1 patient who had malignant pancreatic cancer
with a poor prognosis. A PFC recurrence or stent-related
late adverse event was not observed for a median followup time of 186 days (range 43-396).
DISCUSSION
We demonstrated that EUS-TD by using a new BFMS is
an effective treatment approach for PFCs, with high technical and clinical success rates. There were no
procedure-related adverse events with the deployment or
removal of the new stent. Several investigators have reported that a dedicated BFMS is a more useful device for
PFC drainage under EUS guidance in a pilot observational
study than traditional plastic stent placement because it
may provide a better drainage owing to its large bore
and a better access route for additional procedures such
as DEN.10-12 Moreover, the use of a BFMS reduces the procedure time and technical complexity because of its ease of
placement. The major limitation of BFMSs is the cost, making its routine use controversial. However, this may be
overcome by less need for a repeat intervention in complicated cases. Our previous study showed no significant
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Mukai et al
New biflanged metal stent for treatment of pancreatic fluid collections
Figure 2. Transgastric EUS-guided drainage by using the new biflanged metal stent. A, The distal flange was deployed under EUS and fluoroscopic guidance. B, After the stent placement, the necrotic fluid was drained through the stent.
Figure 3. Endoscopic necrosectomy through the new biflanged metal stent. A, A standard upper endoscope was directly advanced via the stent. B,
Necrotic tissue was removed by using a snare forceps.
difference in the total procedure cost between a plastic
stent and a BFMS in the treatment of complicated WON
cases in which DEN was needed.13
The previously reported BFMSs are divided into 2 types:
LAMS (AXIOS stent [Boston Scientific, Natick, Mass, USA]
and SPAXUS stent [Taewoon Medical Co., Ilsan, Korea])
and FMS (Niti-S; Nagi stent [Taewoon Medical Co.,
Gyeonggi-do, Korea]). FMS migration may be inevitable
because of its weak lumen-apposing function. This was
shown in a multicenter national study conducted in Australia
to evaluate FMS (Nagi stent) for EUS-TD, which included 54
cases of which 4 cases (7.4%) had stent migration during
DEN and 6 cases (11.1%) had spontaneous stent migration.14
On the other hand, LAMS has a lower stent migration rate
(1.1%-5%) than FMS (11.1%-19%).6-8,15,16 These data indicate
that the stability of LAMSs appears to be better than that of
FMSs. The advantage of FMSs is that the stent length between
the 2 flanges is longer than that of LAMSs (20 or 30 mm
vs 10 mm); thus, the FMS is deployed safely in
cases located at a long distance from the GI tract. Moreover,
the delivery system is almost identical to that of a conventional biliary metal stent, making it simple to use.7,17
The new BFMS in this study (HANARO stent) has advantages of both the LAMS and the FMS, the so-called hybrid
BFMS. In our clinical experience (data not recorded), the
radial force of the HANARO stent is comparable with that
of existing BFMSs. The lumen-apposing force of the HANARO stent may be weak compared with that of the AXIOS
stent because the length between the 2 flanges of the HANARO stent is longer than that of the AXIOS stent (20 or
30 mm vs 10 mm). On the other hand, the AXIOS stent
is not suitable in cases of a longer distance (>20 mm) between the stomach and the cavity. The HANARO stent may
have a similar or better lumen-apposing force than the
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Volume 86, No. 1 : 2017 GASTROINTESTINAL ENDOSCOPY 205
New biflanged metal stent for treatment of pancreatic fluid collections
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TABLE 1. Patients and treatment data for pancreatic fluid collections
Age, y/sex
Disease
Maximum size
of PFC, mm
Stent size, mm
Access route
Technical success
1
65/M
Sterile PPC
96
30
Transgastric
Yes
2
36/M
Sterile PPC
54
30
Transgastric
Yes
3
68/M
Infected PPC
73
30
Transgastric
Yes
4
77/F
Infected PPC
115
30
Transgastric
Yes
5
80/M
Sterile WON
95
30
Transgastric
Yes
6
44/M
Infected WON
73
20
Transgastric
Yes
7
79/M
Infected WON
106
30
Transgastric
Yes
8
75/M
Infected WON
129
30
Transgastric
Yes
9
50/M
Infected WON
200
30
Transgastric
Yes
10
64/M
Infected WON
128
30
Transgastric
Yes
11
67/M
Infected WON
147
30
Transgastric
Yes
12
81/F
Infected WON
105
20
Transgastric
Yes
Patient no.
PFC, Pancreatic fluid collection; M, male; PPC, pancreatic pseudocyst; F, female; WON, walled-off necrosis; DEN, direct endoscopic necrosectomy; N/A, not available.
SPAXUS stent because it has powerful flanges compared
with the SPAXUS stent despite having the same stent
length (20 mm). The lumen-apposing force of the HANARO stent is better than that of the Nagi stent, which
has only flared flanges. On the other hand, the stability
of the HANARO stent is equivalent to that of the AXIOS
stent because the anchor flanges of the HANARO stent
are designed to hold tissue layers tightly similarly to the
AXIOS stent, preventing migration. Actually, stent migration occurring spontaneously or during DEN was not
observed in the present study. Because the stent body
length is 20 or 30 mm, and the delivery system is simple
and similar to that of FMS, the stent adapts to various locations of the PFCs.
In 2 patients, severe bleeding in the WON cavity
between DEN sessions occurred owing to the spontaneous
rupture of the pseudoaneurysm. Because the pseudoaneurysm location was distinct from the stent, its occurrence was possibly a result of inflammation and not in
relation with the stent. Although the clinical outcome of
WON has been improved by the development of DEN or
a dedicated BFMS, several adverse events may be inevitable
during the endoscopic treatment course.18,19 In previous
multicenter studies that included a large number of cases,
the clinical success rate of EUS-TD and DEN by using BFMS
for WON has been reported to be approximately 80% to
90%.16,20 The clinical success rate of 83% in the present
study was within the clinical success range in these
previous reports.
The limitations of this study include the absence of a
control group and the small case series being a prospective pilot study at a single institution. In addition, longterm results including recurrence and late adverse
206 GASTROINTESTINAL ENDOSCOPY Volume 86, No. 1 : 2017
events could not be evaluated. Furthermore, all drainage
procedures were performed via the transgastric route in
the present study. Thus, the efficacy of the new BFMS
for drainage via the transduodenal route could not be
evaluated at this time.
In conclusion, the new BFMS is technically feasible and
safe for the treatment of PFCs. Further adequately powered, well-designed, randomized-controlled studies
comparing the new BFMS with previous BFMSs (LAMS or
FMS) are required to validate its efficacy.
ACKNOWLEDGMENT
We thank Dr Edward Barroga, Associate Professor
and Senior Medical Editor from the Department of
International Medical Communications of Tokyo
Medical University for editing the manuscript.
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New biflanged metal stent for treatment of pancreatic fluid collections
Mukai et al
TABLE 1. Continued
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Volume 86, No. 1 : 2017 GASTROINTESTINAL ENDOSCOPY 207
Abbreviations: BFMS, biflanged metal stent; DEN, direct endoscopic necrosectomy; EUS-TD, EUS-guided transluminal drainage; FMS, flared
metal stent; LAMS, lumen-apposing metal stent; PFC, pancreatic fluid
collection; PPC, pancreatic pseudocyst; WON, walled-off necrosis.
DISCLOSURE: All authors disclosed no financial relationships relevant
to this publication.
Copyright ª 2017 by the American Society for Gastrointestinal Endoscopy
0016-5107/$36.00
http://dx.doi.org/10.1016/j.gie.2016.11.025
Received September 10, 2016. Accepted November 14, 2016.
Current affiliations: Department of Gastroenterology and Hepatology (1);
Third Department of Surgery, Tokyo Medical University, Tokyo (2), Third
Department of Internal Medicine, Kansai Medical University, Osaka,
Japan (3).
Reprint requests: Takao Itoi, MD, PhD, FASGE, Department of
Gastroenterology and Hepatology, Tokyo Medical University, 6-7-1
Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan.
If you would like to chat with an author of this publication, you may
contact Dr Itoi at itoi@tokyo-med.ac.jp.