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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1348_Библиотеки_им_академика_М_И_Перельмана.pdf
1077 Enteric Prostheses
Fig. 7.4 WallFlex enteral stent. ( a ) WallFlex enteral stent
has a fl are at the proximal end and roundly angled edges.
( b ) Three radiopaque markers on the delivery system
enable precise stent deployment. The stent can be reconstrained at any time up to when the exterior tube marker
Evolution Duodenal Stent
The Evolution duodenal stent is manufactured by
Cook Medical Inc. (Winston-Salem, NC, USA;
Fig. 7.5 ). This is a TTS, self-expandable metal
uncovered stent made of braided nitinol with a
single-wire woven structure. This stent has proximal and distal fl anges to prevent stent migration.
The diameter of the fl ared ends is 27 mm with a
length of 20 mm. The unconstrained body diameter is 22 mm and unconstrained lengths are 6, 9,
and, 12 cm. The stent comes preloaded on a 10-F,
230-cm delivery system.
There are eight radiopaque markers on the
stent (four on each end) in addition to the
radiopaque mesh structure to provide fl uoroscopic
visualization. An endoscopic marker on the introducer system indicates the proximal end of the
stent within the sheath. The Evolution duodenal
stents are recapturable up to approximately 50%
of stent deployment. The stents foreshorten by
approximately 45–50%.
band ( dark solid arrow ) reaches the deployment limit
marker band ( closed arrowhead ). A postdeployment
marker band ( open arrowhead ) identi fi es the approximate
fi nal position of the proximal end of the stent when fully
expanded
Niti-S Pyloric/Duodenal Stent
Niti-S is the registered trademark of Taewoong
Medical, Seoul, Korea. The Niti-S (ComVi type)
is a unique triple-layered covered stent sandwiched designed to overcome tumor ingrowth
and an uncovered outer stent to reduce
migration.
Niti-S Pyloric/Duodenal Uncovered Stent:
D Type
The Niti-S pyloric/duodenal uncovered stent – D
type – is a self-expandable metal uncovered stent
made of braided nitinol, which is woven with
knitted-interlock structure (D type, Fig. 7.6a ). “D
type” denotes “double wire type” in which two
separate wires are woven into a stent mesh.
Unlike the S type (single wire type), individual
cells of D-type stent are not fi xed and can overlap
with each other at the curved areas where the
stent is bent (Fig. 7.6b, c ), designed to avoid
abrupt luminal narrowing at the fl exed area. The
108
C.G. Kim and I.J. Choi
Fig. 7.5 Evolution duodenal stent. This stent is a through the scope, uncovered enteral stent with fl anges at both ends
to prevent stent migration
structural characteristics provide high fl exibility
and conformability.
This stent is a straight type, with the same
diameter on body and both ends with round edges
to reduce the risk of tissue injury. The unconstrained body diameter is available in 18, 20, 22,
and 24 mm, and unconstrained lengths are 6, 8,
10, and 12 cm. In addition to the radiopacity of
the mesh structure, there are ten platinum
radiopaque markers – four each at the distal/
proximal end and two at middle portion to provide optimal fl uoroscopic visualization. The stent
can be inserted by TTS or OTW methods and
comes preloaded on a 10-F delivery system. The
length of the delivery system is 180 cm for TTS
and 135 cm for OTW placement. After complete
deployment, the shortening rate of this enteral
stent is 17%. It is not reconstrainable at any point
during deployment.
Niti-S Pyloric/Duodenal Stent: ComVi
Type
This is a newly designed covered enteral stent to
overcome both stent migration and reocclusion.
This stent has a unique design of a triple-layered
sandwich structure. The stent is made of two
nitinol-braided outer and inner D-type stents with
a PTFE membrane between them (Fig.
7.6d, e ).
The outer exposed stent mesh is expected to
reduce migration by embedding itself into the
tumor and surrounding normal tissue and a
central PTFE membrane that prevents tumor
ingrowth [
20 ] . There are 5 or 15-mm uncovered
portions at each end and also looped edges to
reduce the risk of mucosal injury.
Available unconstrained body diameters are
18 and 20 mm, and unconstrained lengths and
radiopaque markers, and are same as the uncovered stent (D type). The stent comes preloaded on
a 10.5 F for TTS or OTW delivery. Other characteristics of the delivery system and the shortening
rate of stent are similar to the D-type stent.
Niti-S Pyloric/Duodenal Stent: S Type
The Niti-S pyloric/duodenal stent – fully covered –
is an older model but still currently available. It is a
self-expandable metal stent woven into single-wired
structure (Fig. 7.6c, f ). The covering material is sili-
cone. It has fl anges (24 mm diameter and 15 mm
long) at the ends to minimize the risk of migration
and rounded edges to reduce the risk of tissue
injury. A repositioning lasso on the proximal end is
optional. Although the default model has coated
fl anges on both ends, the manufacturer provides
uncoated fl anges at the proximal and/or distal ends.
The unconstrained body diameter, lengths,
radiopaque markers, and delivery system are the
same as the ComVi-type stent. After complete
deployment, the shortening rate of this enteral
stent is 50–60%, and it is reconstrainable up to
70% stent deployment, allowing easy repositioning and improved control.
HANAROSTENT® Duodenum/Pylorus
HANAROSTENT is the registered trademark of
M.I. Tech Co. Ltd., Seoul, Korea. It is available
either uncovered stent or covered, both of similar
design other than the silicone-coated body.
1097 Enteric Prostheses
Fig. 7.6 Niti-S pyloric/duodenal stents ( a ) Niti-S pyloric/
duodenal uncovered stent (D type) is an uncovered enteral
stent. ( b ) A close-up of the bent D-type (double-wire knit-
ted-interlock structure) stent shows overlapping cells
because the individual cells are not fi xed. ( c ) A close-up
of the bent S-type stent shows that individual cells do not
HANAROSTENT Duodenum/Pylorus,
Noncovered (NNN)
This is an uncovered enteral stent. NNN denotes
noncovered distal, center, and proximal parts of
the stent, respectively. It is a self-expandable
metal stent woven with the hook-type nitinol
structure (Fig.
7.7a, b ). A repositioning lasso can
be attached at the proximal end if needed.
overlap. ( d ) Niti-S pyloric/duodenal stent (ComVi type) is
a covered enteral stent. ( e ) ComVi type consists of three
layers; an outer and inner nitinol meshes and a PTFE
membrane between the meshes. ( f ) Niti-S pyloric/duode-
nal stent (S type) is the old model of covered enteral stent.
A reposition lasso (arrowhead) is optional
The unconstrained body diameter is 20 mm,
and unconstrained lengths are 6, 8, 10, 12, 14, or
16 cm. This stent has fl ares (diameter 25 mm and
length 13 mm) on both ends to reduce the risk of
migration and rounded edges to reduce the risk
of tissue injury. In addition to the radiopacity of
the mesh structure, there are 12 gold radiopaque
markers – four each located at the center and both
110
Fig. 7.6 (continued)
C.G. Kim and I.J. Choi
ends for excellent fl uoroscopic visualization,
(Fig. 7.7b, c ).
This stent can be inserted TTS or OTW. The
stent comes preloaded on a 10.2-F, 230-cm-long
(for TTS delivery) or 10.5-F, 120-cm-long (for
OTW delivery) HANARO delivery device. The
olive tip of the delivery device is radiopaque, and
the distal end of outer sheath has radiopaque
tungsten rings. After complete deployment, there
is a 20% foreshortening. It is reconstrainable up
to 80% of fully stent deployment, allowing easy
repositioning and improved control. The point of
no return is marked in red on the inner shaft of
handle (Fig.
7.7f , open arrowhead).
HANAROSTENT Duodenum/Pylorus (NCN
and CCN)
HANAROSTENT® duodenum/pylorus (NCN)
is a covered enteral stent. NCN means noncovered distal, covered center, and noncovered proximal portions. CCN means covered distal and
center, and uncovered proximal portions. The
body of this stent is coated by silicone. Flared
uncovered portions are present on both ends
(NCN) or proximal end (CCN) to reduce the risk
of migration (Fig. 7.7d, e ).
The covered stent has a similar design to the
uncovered HANAROSTENT, except the number
and location of radiopaque markers. There are 16
gold radiopaque markers (four each distal and
proximal to the uncovered end, and distal and
proximal to the covered end) to provide improved
fl uoroscopic visualization.
BONASTENT ® Pyloric/Duodenal
The BONASTENT has a design similar to the
HANAROSTENT, but another uniquely designed
stent, BONASTENT M-Duodenal, is available
and developed to enable biliary stent placement
and adequate expansion through the lumen of the
duodenal stent.
BONASTENT Pyloric/Duodenal Uncovered
BONASTENT is the registered trademark of
Standard Sci-Tech Inc., Seoul, Korea. This is a
self-expandable metal uncovered stent made of
1117 Enteric Prostheses
Fig. 7.7 HANAROSTENT® duodenum/pylorus stents.
( a ) HANAROSTENT duodenum/pylorus uncovered stent.
This enteral stent has fl ares on both ends. ( b ) A close-up
view of HANAROSTENT duodenum/pylorus uncovered
stent shows hook-type wire structure and gold radiopaque
marker ( arrowhead ). ( c ) Fluoroscopic view of radiopaque
markers ( arrowhead ). ( d ) HANAROSTENT duodenum/
braided nitinol with a fi xed hook and cross-wired
structure (Fig.
7.8a ). The cell size of the stent
mesh is 4 mm. The diameter of the fl ared ends is
6 mm larger than that of the body, and the length
of fl are is 15 mm to minimize the risk of migra-
pylorus covered stent (NCN). Flares on both ends remain
uncovered. ( e ) HANAROSTENT duodenum/pylorus cov-
ered stent (CCN). Proximal end fl are remains uncovered.
( f ) Recapturing red marker ( open arrowhead ) and deploy-
ment black markers. Left closed arrowhead denotes the
starting point of stent deployment, and the right closed
arrowhead indicates the fi nishing point of deployment
tion, and it has smooth ends to reduce the risk of
tissue injury. The unconstrained body diameter is
available in 18 and 20 mm, and unconstrained
lengths are 6, 8, 10, 12, 14, and 16 cm. There are
12 platinum wire spring radiopaque markers
112
Fig. 7.7 (continued)
C.G. Kim and I.J. Choi
Fig. 7.8 BONASTENT® pyloric/duodenal stents. ( a ) BONASTENT pyloric/duodenal uncovered stent. This enteral
stent has fl ares on both ends. ( b ) BONASTENT pyloric/duodenal covered stent. Flares on both ends are uncovered
(four each at the distal, center, and proximal portions of the stent).
The stent comes preloaded on a 10-F delivery
system for TTS or OTW placement. The lengths
for TTS delivery are 180 and 230 cm, and 120 cm
for OTW placement. Stainless steel radiopaque
bands are on the proximal and distal parts of the
delivery system inner shaft. After complete deployment, the stent shortens by up to 30%. It is reconstrainable up to 80% stent deployment. There is a
red marker on the stainless steel outer shaft of the
delivery system to denote the point of no return.
1137 Enteric Prostheses
BONASTENT Pyloric/Duodenal Covered
This partially covered enteral stent has same
design as the BONASTENT pyloric/duodenal,
except that the body is coated with silicone.
Flares on both ends remain uncovered to reduce
the risk of migration (Fig. 7.8b ).
BONASTENT M-Duodenal
Patients with malignant gastric outlet obstruction
often have combined or impending biliary
obstruction [ 21 ] . In these patients, a biliary stent
is recommended prior to duodenal stent insertion
through a percutaneous or an endoscopic
approach. If a conventional enteral stent is placed,
access to the papilla and biliary tree can be very
dif fi cult, and special maneuvers such as cutting
the overlying wires or balloon dilating to widen
the mesh structure of the duodenal stent are often
required [ 21 ] . Moreover, biliary stents placed
through the mesh of a conventional enteral
stent rarely expand adequately because of
the shape memory property of nitinol [ 14 ] . The
BONASTENT M-Duodenal was developed to
enable biliary stent placement and allow adequate
expansion though the mesh structure of the duodenal stent.
The stent consists of two portions: a fi xed portion with a woven fi xed hook and cross-wired
structure similar to the uncovered BONASTENT
pyloric/duodenal and a 3-cm un fi xed portion
(M-portion) with an un fi xed cross-wired structure. There are two stent types according to the
location of the un fi xed portion. The central type
has the un fi xed portion at the center of the stent,
which is designed for type II bilioduodenal strictures that involve the second portion of duodenum with involvement of the papilla (Fig. 7.9a ).
The lateral type has the un fi xed portion at either
the distal or proximal part of the stent (Fig. 7.9b ).
The former is for type I bilioduodenal stenosis
involving the duodenal bulb or the fi rst portion
without papillary involvement. The latter is for
type III bilioduodenal stenosis involving the third
portion of the duodenum with sparing of the
papilla. These features contribute to easy insertion of a biliary stent through the mesh wall of the
un fi xed portion of the duodenal stent without
resistance (Fig. 7.9c, d ). There are 16 platinum
wire spring radiopaque markers (four each at both
ends of the un fi xed portion, and proximal and
distal ends) for improved fl uoroscopic visualization of the entire stent and the un fi xed portions.
Although the initial model had a smaller stent
mesh cell size of 2.5–2.75 mm, the current model
has 4-mm cells in both fi xed and un fi xed portions
[ 22 ] . The available diameter of BONASTENT
M-Duodenal is 22 mm. Other speci fi cations of
the fl ared ends and body are compatible with
BONASTENT pyloric/duodenal uncovered.
EGIS Pyloric Stent
The EGIS pyloric stent is the enteral stent from
S&G Biotech (Seongnam, Korea), which provides various types of stents including EGIS
pyloric stent-single bare, double bare, singlecovered, double-covered, and Hercules SP pyloric stent, which consists of two stents. EGIS
pyloric stent-double bare and Hercules SP pyloric stents have unique designs to minimize tumor
ingrowth and stent migration.
EGIS Pyloric Stent, Single Bare and
Double Bare
These are self-expandable metal uncovered stents
made of braided nitinol, which are woven into a
cross and hooked structures. There are two types
of stents that differ in the number of layers of mesh
wire: single bare and double bare (Fig. 7.10a, b ).
Double bare is a unique double-layered structure
created by crossing two stents resulting in a
smaller diameter cell size (2–3 mm) with denser,
numerous cells designed to reduce tumor
ingrowth. EGIS pyloric stents lack fl ared ends
and have round edges to reduce the risk of tissue
damage and perforation. The unconstrained body
diameters are 18, 20, 22, and 24 mm, and unconstrained lengths are 6, 8, 10, and 12 cm. There are
ten gold radiopaque markers (four at each end
and two in the midportion). The stent comes preloaded on a 10-F delivery system for either TTS
(length, 180 cm) or OTW (length, 120 cm)
deployment. There is radiopaque tungsten at the
distal end of the outer sheath. After complete
deployment, the stent foreshortens by 32% in
114
C.G. Kim and I.J. Choi
Fig. 7.9 BONASTENT® M-duodenal. Un fi xed portion of BONASTENT® M-duodenal enables biliary
stents to be placed and allows expansion though the
lumen of the duodenal stent. ( a ) Central type. Un fi xed
portion is located on the center of the stent body for
the second portion of duodenal strictures. ( b ) Lateral
type. Un fi xed portion is located on the distal or
proximal part. ( c ) Fluoroscopic view showed placement
of a BONASTENT M-duodenal central type across the
duodenal stricture. ( d ) Fluoroscopic view showed biliary
stent successfully placed through the un fi xed mesh of
the duodenal stent (c and d, Courtesy of Prof. JH Moon,
Soon Chun Hyang University School of Medicine,
Bucheon/Seoul, Korea)
1157 Enteric Prostheses
Fig. 7.10 EGIS pyloric stent. ( a ) EGIS pyloric single
bare stent. ( b ) The double-layered structure of EGIS
pyloric double bare stent creates a smaller cell size. ( c )
EGIS pyloric single-covered stent is the old model
of S&G Biotech. ( d ) Double-covered EGIS pyloric
stent is double-layered combination pyloric stent which
is made of 2 nitinol-braided stents and a silicone
membrane
116
C.G. Kim and I.J. Choi
Fig. 7.11 Hercules SP pyloric stent. This dual stent
consists of two stents. ( a ) Inner bare nitinol stent ( top )
and outer stent consist of each end bare nitinol stent
and a central Dacron fabric without wire structure
single bare and 20% in double bare stents. These
stents are not reconstrainable.
EGIS Pyloric Stent, Single Covered
and Double Covered
The covered type of EGIS pyloric stent is available in two models: single covered and double
covered (Fig.
7.10c, d ). The older model single-
covered stent is fully covered with silicone and
has 16 gold radiopaque markers (seven each at
the ends and two on the midportion). After complete deployment, the stent foreshortens by 25%.
EGIS pyloric stent double covered is the doublelayered combination pyloric stent made of two
nitinol-braided stents and a silicone membrane
(Fig.
7.10d ). There are 5-mm uncovered portions
at the proximal and distal ends of the stent. Other
characteristics are the same as EGIS pyloric stent
double bare type.
( bottom ). ( b ) Assembly of the two stents consecutively
inserted under fl uoroscopic guidance of the inner bare
nitinol stent after insertion of the outer partially covered stent
Hercules SP Pyloric Stent
The Hercules SP pyloric stent is a uniquely
designed enteral stent from S&G Biotech
designed to prevent tumor ingrowth and stent
migration. This dual expandable stent consists of
an outer partially covered stent and an inner bare
nitinol stent which are inserted consecutively
under fl uoroscopic guidance (OTW method,
Fig.
7.11a, b ). The outer partially covered stent
consists of three parts – a proximal and distal
bare nitinol stent, and a central Dacron fabric
without wire structure [ 23 ] . Both proximal and
distal bare nitinol stent parts are 28 mm in diameter and 25 mm long. The diameter of the central
Dacron portion is 18 mm. After the outer partially covered stent is inserted, a bare inner nitinol
stent is inserted to expand the wireless Dacron
portion of the outer stent and to increase its radial