Peter
R. Mueller,
M.D.
Metallic
T
Endoprostheses:
Boon
with
potential
from
occlusions
long-term
or Bust?’
complications
Both
the
et al (1) reand largest published study on the use of metallic biliary endoprostheses for the treatment of malignant bihiary disease. The question that this and other recently published reports (2-9) on metallic stents raises is,
the appropriately selected patient. Recently, radiologists have shown
sheaths.
tremendous est in the originally
small
Are
tallic
HE article ports
by
the
metallic
Lameris
newest
endoprostheses
really
bet-
deemed
enthusiasm use of metallic thought that
stents
would
acceptable
in
and
for and interstents. It was the use of me-
improve
long-term
results and reduce complications when compared with the use of conventional stents. Over the past few years, several
ter than conventional endoprostheses and should they replace them? Althouglt clinical trials (10-15) of various types of endoprostheses used as substitutes for internal-external catheters have been well documented, the search for the perfect stent resembles the surfer’s pursuit of the perfect wave. Initially, early reports of uncomplicated success with conventional endoprostheses were overly optimistic (16); however, after several years of experience, some authors advocated abandonment of these devices (17). In the past few years, the marginal benefits versus marginal costs have become understood, and a comfortable middleground approach has been reached,
artit’les
have
been
published
on the
Gianturco (Cook; Bloomington, Ind) (3,7) and Wallstent (Schneider [U.S.A.], Plymouth, Minn; and Pfizer, Minneapolis) (1,2,4,5) metallic endoprostheses, the two most commonly used metallic stents. Both sents are constructed
from
thin
stainless
steel
and
have
large
internal diameters (Table I). The Gianturco is zigzag; the Wallstertt has a meshlike structure. There are supporters and skeptics for both of these stents.. The major advantages and disadvantages of metallic stents are summarized herein.
Radiology
1991;
Small
179:603-605
local
minimal,
these
the
trauma
rather
analgesics
administered
and narcotics.
induced
is no
more
than that seen with a routine biliary drainage. This contrasts greatly with the 14-16-F transhepatic tract required for placement Similarly, the
of a conventional small introducer
stent. system
allows the option of placement tallic stent at a single-session the radiology department. Lameris et al (1) did not
nique,
of a mevisit to
Although
use this techet al (2) and Mueller et al
Adam
(18) noted that they placed metallic prostheses at the initial visit in up to 40% of patients. Even if this is not accomplished, the trauma of a second session is negligible, and the pain experienced by the patient is considerably less than the degree of discomfort that has been seen with placement of conventional endoprostheses.
Diameter
Perhaps
System
McLean and Burke pointed out in their state-of-the-art article on biliary endoprostheses that patients’ reactions to biliary intervention are paramount to its success and acceptance (14). The problems of multiple catheter manipulations and procedure-induced pain have contributed, as much as anything, to the reduction of radiologically controlled biliary interventions. One cannot overestimate the negative effects that multiple painful dilations of the transhepatic tract have on patients and clinical acceptance of the procedure.
‘From the Department of Radiology. Massachusetts General Hospital, 32 Fruit St. Boston, MA 02114. Received and accepted March 14, 1991. Address reprint requests to the author. ‘RSNA, 1991 See also the article by Lameris et al (pp 703707) in this issue.
Table
Introducer
tolerate
with
intravenously
Thus,
is often
patients
tracts
the Wallstent 7-10-F introducer
and
with
Dilatation
most
Large
ADVANTAGES Index terms: Bile ducts, interventional procedure, 768.1229 #{149} Bile ducts, neoplasms, 768.36 #{149} Bile ducts, stenosis or obstruction, 768.36 #{149} Editorials #{149} Gallbladder, neoplasms, 762.36S #{149} Interventional procedures, complications
Gianturco
can be inserted
the
most
significant
advan-
tage of the metallic stents over the conventional stents is their large internal diameter, which varies from I cm (Gianturco) to 1.2 cm (30 F) (Wallstent). In general, the largest external diame-
ter conventional stent F (7-8 mm). However,
inserted because
rather
external
thick
these
types
(2-3
mm)
of endoprostheses
is 12-14 of the wall,
have
a
relatively small (4-5 mm) internal diameter, which actually reduces the functional lumen. Experimental work by Rey et al has proved that patency is directly related to the stent diameter (19). The severalfold increase in diame-
I
Characteristics
of Metallic
Stents No. of Stents
Stent
Diameter (cm)
Length (cm)
Gianturco
1.2
1.5-3.0
Wallstent
1.0
6 or 10
Introducer Size (F)
Routinely Used
10
>2-3
9
1
Manufacturer
Cost(S)
Cook (Bloomington, Ind) Schneider (U.S.A.)
(Plymouth. Pfizer
700-1,200 1,000
Minn),
(Minneapolis)
603
ter of a metallic stent versus that of a conventional stent should increase patency.
Small
Surface
Area
et al
(1)
and
of Malignant
Obstruction
other
recent
articles
by Adam et al (2) and Gillams et al (5) seem to support this fact. Although they all reported a relatively high percentage of patients with recurrent jaundice, the rate of sepsis due to occlusion from debris was actually low.
Dooleyetal(1984)(11) Mueller et al (1985) (15) Lammer and Neumayer(1986)(13)
Dicketal
stent and of recurrent
(1), Adam
(1987) (10)
has
been jaundice
reported as a cause by Lameris et al
et al (2), and
Gillams
et al (5).
Consequently,
like conventional endoprostheses in which a problem of migration occurred, the metallic endoprosthesis should not be positioned so that it is the same length as the obstructing lesion. In a certain percentage of cases, particularly those with strictures longer than 3-4 cm, two or more stents are necessary. Whereas the Wallstent shortens s it expands, the Gianturco stent is simply shorter (1.5-3.0 cm in length). This necessitates placement of multiple stents. In fact, both Irving et a! (7) and Coons (3) reported the use of multiple stents in their patients; Coons used 87 metal-
lic Gianturco tients.
endoprostheses
in 31 pa-
the previously described adone should consider several disadvantages before declarmetallic stents are indeed more than conventional stents.
Treatment Because
of Occlusion both
the Gianturco and the Walistent are made of thin wire mesh that becomes incorporated into the bile duct mucosa and both exert natural pressure on the surface of the bile duct wall, they are not easily removed. In fact, Lameris et al noted complications in three of their patients because the wires eroded through the mucosa (1). Gillams et al also described a failed attempt at surgical removal (5). This is in contradistinction to the conventional endoprosthesis that can be removed by radiologic or endoscopic methods (22,23). However, this does not mean that occlusion cannot be treated. Re-
drainage, reinsertion and Fogarty balloon been tallic
used for stents.
of a new methods
treatment
stent, have
of clogged
all me-
Shortening Several
authors
report
a decrease
in
size of the Walistent of up to 40% of the original length within weeks of placement (2,9). due to the
604
This phenomenon mechanical properties
Radiology
#{149}
is simply of the
the
procedure.
proximately
The $1,000;
out,
the
use
the cost of
Wallstent
costs
ap-
a single
Gianturco
approximately $350. One often has to insert 3-4 Gianturco stents per patient; hence, if the stricture is longer than 1-2 cm, there is not a great difference in price between the two. Lameris et al (1) suggest that balloon dilation after placement of the metallic endoprosthesis may not be necessary, and stent,
not using
a balloon
dilation
catheter
might reduce the cost of the biliary procedure. However, other authors, notably Coons (3) and Adam et al (2), ar-
gue that dilation after placement mandatory. In summary, these penses contrast sharply low cost of a conventional varies between $60 and
is
exthe rather stent, which $160.
with
13 22
162 87
20 20
rence
of jaundice
patients
with
report lic
stated
stents
that
has
report
on
and/or
Early results of treatment of malignant obstruction with both Gianturcos and Walistents were not encouraging and were no better than results from major studies in patients with conventional stents (Tables 2, 3). Coons (3) reported that up to 21% of patients in his
study
experienced
late sequelae
that
42%
experienced
“.
cholangitis
the
.
.
of metalIn
Gillams
et al (5)
of
their
late
.
use
45
a
patients
complications
of
or jaundice.”
both Adam et al et al (1) demonstrated much better results. Adam et al reported long-term complications in only 7% of their patients. Importantly, Lameris et al (1) grouped their own patients Recently,
however,
(2) and
with
Lameris
long-term
ly into
complications
patients
common
who
bile
duct
separate-
had
disease
(2.4%)
and
in the those
hilar lesions (17%). As one rethe literature, particularly reports on patients with metallic stents, it is important to separate the results and with
views
related
analysis
of
use
to
the
disease
greater in
These cult
to
endoprostheses
with
of the
but
all
were of
combined
the
terestingly,
with
with
stent
most
recent
diffimany
and!
by
poor
stent,
shortening
stent
is placed.
and
Adam,
considerable
placement,
po-
possibly
natural
the
Lameris
diologists
lesions.
been
caused
the
after
were
hilar
of jaundice
metallic
with
occurs
a
likelihood
cases
cholangitis
that
always in
recurrent
sitioning
in
that
high
have
treat,
Carereports
of problems
patients lesions
location.
previous
indicates
percentage
seen
or
all
of metallic
malignant
In-
two
ra-
experience
have
publications
had and
best results. In general, reviewing the numerous published
the
have
had
the
doprosthesis
in
that
most
patients
long-term
of
long-term
It appears. experienced
who
complications
occlusion that
terms
the results in reports on en-
is difficult.
complications
to
had
problems
overgrowth (perhaps positioning and/or metallic stent) rather
from
needs
debris. be
This
studied
is an
further
beshortthan area be-
cause, if tumor overgrowth was indeed the cause of long-term complications, metallic
more
endoprostheses
encouraging
of
jaundice and/or cholangitis. Irving et al (7), in their summary of a multicenter European clinical trial, reported an approximately 50% rate of recur-
.
Their
disappointing.”
Walistents,
indicated
in
disease.
“.
been
with
cholangitis
malignant
due to tumor cause of poor ening of the
RESULTS
of Patients Complications
53 113
ful
As Lameris et al (1) point of metallic stents increases
Stents
Percentage Long-term
of the
DISADVANTAGES
Conventional
complications
Expense
Despite vantages, potential ing that beneficial
with
No. of Patients
Authors
Because the stents are constructed from extremely thin stainless steel wire, they have a low mass and small surface area. Theoretically, these decrease the possibility of infections. In studies of endoscopically placed endoprostheses, for example, it has been shown that the initiating event of infection occurs when bacteria adhere to the stent surface. This results in secondary deposition of protein and formation of a gelatin matrixlike material that promotes occlusion (14,19,20,21). Because the metallic endoprostheses present less surface area, such adherence would seem less likely to happen. Similarly, the wire mesh often becomes incorporated into the wall of the duct (1,3,5), which further reduces the surface area and decreases the likelihood of infection. In fact, the article by Lameris
Table 2 Results of Treatment
BENIGN The the lignant
use
previous of
metallic
disease,
may
have
a
future.
DISEASE commentary stents primarily
concerns strictly
in
because
June
mathe
1991
13.
Table 3 Results of Treatment
of Malignant
Obstruction
with
Metallic
Stents 14.
Stent
Authors
No. of Patients 16 41 41 69
Gianturco Wallstent Wallstent Wallstent
Coons (1989) (3) Gillams et al (1990) (5) Adam et al (1991) (2) Lameris et al(1991)(1)
Percentage Long-term
of Patients Complications
21 42 7 2 (common 18 (hilar)
with
15. duct) 16.
use
of stents-conventional or metalgenerally somewhat controversial in benign disease. The largest current study of the use of metallic stents in benign disease was reported by RosSi et al (9), who used Gianturco stents to
5.
lic-is
treat benign strictures in 17 patients. Even Rossi et al suggest that only selected patients should undergo this treatment, and only after other, more standard methods have failed. In summary, we are still in a discovery phase with metallic stents. The potential is still unproved and the results are still uncertain. U
6.
7.
8.
References 1.
2.
3.
4.
Lameris JS, Stoker J, Nijs HGT, et al. Malignant biliary obstruction: percutaneous use of self-expandable stents. Radiology 1991; 179:703-707. Adam A, Chetty N, Roddie M, Yeung E, Benjamin IS. Self-expandable stainless steel endoprostheses for treatment of malignant bile duct obstruction. AJR 1991; lS6:321-32S. Coons HG. Self-expanding stainless steel bihiary stents. Radiology 1989; 170:979983. Dick R, Gillams A, Dooley JS, Hobbs KEF. Stainless steel mesh stents for bihiary strictures. J Intervent Radiol 1989; 4:95-98.
Volume
179
Number
#{149}
3
9.
10.
11.
12.
Gillams A, Dick R, Dooley JS, Wallsten H, El-Din A. Self-expandable stainless steel braided endoprosthesis for biliary strictures. Radiology 1990; 174:137-140. Huibregtse K, Cheng J, Coene PPLO, Fockens P. Tytgat GNJ. Endoscopic placement of expandable metal stents for biliary strictures: a preliminary report on experience with 33 patients. Endoscopy 1989; 21:280-282. Irving JD, Adam A, Dick R, Dondelinger RF, Lunderquist A, Roche A. Gianturco expandable metallic biliary stents: results of a European clinical trial. Radiology 1989; 172:321-326. Roeren T, Brambs HJ, Richter GM, Kauffmann GW. Coated balloon-expandable stent for percutaneous treatment of mahignant biliary obstruction. Radiology 1990; l77(P):238-239. Rossi P, Bezzi M, Salvatori FM, Maccioni F, Porcaro ML. Recurrent benign biliary strictures: management with self-expanding metallic stents. Radiology 1990; 175: 661-665. Dick R, Platts A, Gilford J, Reddy K, Duncan-Irving J. The Carey-Coons percutaneous biliary endoprosthesis: a three-centre experience in 87 patients. Clin Radiol 1987; 38:175-178. Dooley JS, Dick R, George P, Kirk RM, Hobbs KEF, Sherlock S. Percutaneous transhepatic endoprosthesis for bile duct obstruction. Gastroenterology 1984; 86: 905-909. Gibson RN. Transhepatic biliary endoprostheses. J Intervent Radiol 1989; 4:712.
17.
18.
19.
20.
21.
22.
23.
Lammer J, Neumayer K. Bihiary drainage endoprostheses: experience with 201 placements. Radiology 1986; 159:625-629. McLean GK, Burke DR. Role of endoprostheses in the management of malignant biliary obstruction. Radiology 1989; 170:961-967. Mueller PR, Ferrucci JT Jr. Teplick 5K, et al. Biliary stent endoprosthesis: analysis of complications in 113 patients. Radiology 1985; 156:637-639. Coons HG, Cary PH. Large-bore, long biliary endoprostheses (bihiary stents) for improved drainage. Radiology 1983; 148: 89-94. Mendez G Jr, Russell E, LePage JR. Guerra JJ, Posniak RA, Trefler M. Abandonment of endoprosthetic drainage technique in malignant bihiary obstruction. AJR 1984; 143:617-622. Mueller PR, Tegtmeyer CJ, Saini 5, et al. Metallic biliary stents: early experience (abstr). Radiology 1990; l77(P):307. Rey JF, Marpetit D, Greff M. Experimental study of biliary endoprostheses efficiency. Endoscopy 1985; 17:145-148. Groen AK, Out 1, Huibregtse K, Delzenne B, Hoek FJ, Tytgat GNJ. Characterization of the content of occluded biliary endoprostheses. Endoscopy 1987; 19:57-59. Leung JWC, Ling TKW, Kung JLS, Vallance-Owen J. The role of bacteria in the blockage of biliary stents. Gastrointest Endosc 1988; 34:19-22. Jackson JE, Roddie ME, Yeung EYC, Benjamin IS, Adam A. Biliary endoprosthesis dysfunction in patients with malignant hilar tumors: successful treatment by percutaneous replacement of the stent. AJR 1990; 155:391-395. Lee MJ, Mueller PR, Saini 5, Morrison MC, Brink JA, Hahn PF. Occlusion of biliary endoprostheses: presentation and management. Radiology 1990; 176:531534.
-
‘a’-
R. Mueller,
M.D.
Metallic
T
Endoprostheses:
Boon
with
potential
from
occlusions
long-term
or Bust?’
complications
Both
the
et al (1) reand largest published study on the use of metallic biliary endoprostheses for the treatment of malignant bihiary disease. The question that this and other recently published reports (2-9) on metallic stents raises is,
the appropriately selected patient. Recently, radiologists have shown
sheaths.
tremendous est in the originally
small
Are
tallic
HE article ports
by
the
metallic
Lameris
newest
endoprostheses
really
bet-
deemed
enthusiasm use of metallic thought that
stents
would
acceptable
in
and
for and interstents. It was the use of me-
improve
long-term
results and reduce complications when compared with the use of conventional stents. Over the past few years, several
ter than conventional endoprostheses and should they replace them? Althouglt clinical trials (10-15) of various types of endoprostheses used as substitutes for internal-external catheters have been well documented, the search for the perfect stent resembles the surfer’s pursuit of the perfect wave. Initially, early reports of uncomplicated success with conventional endoprostheses were overly optimistic (16); however, after several years of experience, some authors advocated abandonment of these devices (17). In the past few years, the marginal benefits versus marginal costs have become understood, and a comfortable middleground approach has been reached,
artit’les
have
been
published
on the
Gianturco (Cook; Bloomington, Ind) (3,7) and Wallstent (Schneider [U.S.A.], Plymouth, Minn; and Pfizer, Minneapolis) (1,2,4,5) metallic endoprostheses, the two most commonly used metallic stents. Both sents are constructed
from
thin
stainless
steel
and
have
large
internal diameters (Table I). The Gianturco is zigzag; the Wallstertt has a meshlike structure. There are supporters and skeptics for both of these stents.. The major advantages and disadvantages of metallic stents are summarized herein.
Radiology
1991;
Small
179:603-605
local
minimal,
these
the
trauma
rather
analgesics
administered
and narcotics.
induced
is no
more
than that seen with a routine biliary drainage. This contrasts greatly with the 14-16-F transhepatic tract required for placement Similarly, the
of a conventional small introducer
stent. system
allows the option of placement tallic stent at a single-session the radiology department. Lameris et al (1) did not
nique,
of a mevisit to
Although
use this techet al (2) and Mueller et al
Adam
(18) noted that they placed metallic prostheses at the initial visit in up to 40% of patients. Even if this is not accomplished, the trauma of a second session is negligible, and the pain experienced by the patient is considerably less than the degree of discomfort that has been seen with placement of conventional endoprostheses.
Diameter
Perhaps
System
McLean and Burke pointed out in their state-of-the-art article on biliary endoprostheses that patients’ reactions to biliary intervention are paramount to its success and acceptance (14). The problems of multiple catheter manipulations and procedure-induced pain have contributed, as much as anything, to the reduction of radiologically controlled biliary interventions. One cannot overestimate the negative effects that multiple painful dilations of the transhepatic tract have on patients and clinical acceptance of the procedure.
‘From the Department of Radiology. Massachusetts General Hospital, 32 Fruit St. Boston, MA 02114. Received and accepted March 14, 1991. Address reprint requests to the author. ‘RSNA, 1991 See also the article by Lameris et al (pp 703707) in this issue.
Table
Introducer
tolerate
with
intravenously
Thus,
is often
patients
tracts
the Wallstent 7-10-F introducer
and
with
Dilatation
most
Large
ADVANTAGES Index terms: Bile ducts, interventional procedure, 768.1229 #{149} Bile ducts, neoplasms, 768.36 #{149} Bile ducts, stenosis or obstruction, 768.36 #{149} Editorials #{149} Gallbladder, neoplasms, 762.36S #{149} Interventional procedures, complications
Gianturco
can be inserted
the
most
significant
advan-
tage of the metallic stents over the conventional stents is their large internal diameter, which varies from I cm (Gianturco) to 1.2 cm (30 F) (Wallstent). In general, the largest external diame-
ter conventional stent F (7-8 mm). However,
inserted because
rather
external
thick
these
types
(2-3
mm)
of endoprostheses
is 12-14 of the wall,
have
a
relatively small (4-5 mm) internal diameter, which actually reduces the functional lumen. Experimental work by Rey et al has proved that patency is directly related to the stent diameter (19). The severalfold increase in diame-
I
Characteristics
of Metallic
Stents No. of Stents
Stent
Diameter (cm)
Length (cm)
Gianturco
1.2
1.5-3.0
Wallstent
1.0
6 or 10
Introducer Size (F)
Routinely Used
10
>2-3
9
1
Manufacturer
Cost(S)
Cook (Bloomington, Ind) Schneider (U.S.A.)
(Plymouth. Pfizer
700-1,200 1,000
Minn),
(Minneapolis)
603
ter of a metallic stent versus that of a conventional stent should increase patency.
Small
Surface
Area
et al
(1)
and
of Malignant
Obstruction
other
recent
articles
by Adam et al (2) and Gillams et al (5) seem to support this fact. Although they all reported a relatively high percentage of patients with recurrent jaundice, the rate of sepsis due to occlusion from debris was actually low.
Dooleyetal(1984)(11) Mueller et al (1985) (15) Lammer and Neumayer(1986)(13)
Dicketal
stent and of recurrent
(1), Adam
(1987) (10)
has
been jaundice
reported as a cause by Lameris et al
et al (2), and
Gillams
et al (5).
Consequently,
like conventional endoprostheses in which a problem of migration occurred, the metallic endoprosthesis should not be positioned so that it is the same length as the obstructing lesion. In a certain percentage of cases, particularly those with strictures longer than 3-4 cm, two or more stents are necessary. Whereas the Wallstent shortens s it expands, the Gianturco stent is simply shorter (1.5-3.0 cm in length). This necessitates placement of multiple stents. In fact, both Irving et a! (7) and Coons (3) reported the use of multiple stents in their patients; Coons used 87 metal-
lic Gianturco tients.
endoprostheses
in 31 pa-
the previously described adone should consider several disadvantages before declarmetallic stents are indeed more than conventional stents.
Treatment Because
of Occlusion both
the Gianturco and the Walistent are made of thin wire mesh that becomes incorporated into the bile duct mucosa and both exert natural pressure on the surface of the bile duct wall, they are not easily removed. In fact, Lameris et al noted complications in three of their patients because the wires eroded through the mucosa (1). Gillams et al also described a failed attempt at surgical removal (5). This is in contradistinction to the conventional endoprosthesis that can be removed by radiologic or endoscopic methods (22,23). However, this does not mean that occlusion cannot be treated. Re-
drainage, reinsertion and Fogarty balloon been tallic
used for stents.
of a new methods
treatment
stent, have
of clogged
all me-
Shortening Several
authors
report
a decrease
in
size of the Walistent of up to 40% of the original length within weeks of placement (2,9). due to the
604
This phenomenon mechanical properties
Radiology
#{149}
is simply of the
the
procedure.
proximately
The $1,000;
out,
the
use
the cost of
Wallstent
costs
ap-
a single
Gianturco
approximately $350. One often has to insert 3-4 Gianturco stents per patient; hence, if the stricture is longer than 1-2 cm, there is not a great difference in price between the two. Lameris et al (1) suggest that balloon dilation after placement of the metallic endoprosthesis may not be necessary, and stent,
not using
a balloon
dilation
catheter
might reduce the cost of the biliary procedure. However, other authors, notably Coons (3) and Adam et al (2), ar-
gue that dilation after placement mandatory. In summary, these penses contrast sharply low cost of a conventional varies between $60 and
is
exthe rather stent, which $160.
with
13 22
162 87
20 20
rence
of jaundice
patients
with
report lic
stated
stents
that
has
report
on
and/or
Early results of treatment of malignant obstruction with both Gianturcos and Walistents were not encouraging and were no better than results from major studies in patients with conventional stents (Tables 2, 3). Coons (3) reported that up to 21% of patients in his
study
experienced
late sequelae
that
42%
experienced
“.
cholangitis
the
.
.
of metalIn
Gillams
et al (5)
of
their
late
.
use
45
a
patients
complications
of
or jaundice.”
both Adam et al et al (1) demonstrated much better results. Adam et al reported long-term complications in only 7% of their patients. Importantly, Lameris et al (1) grouped their own patients Recently,
however,
(2) and
with
Lameris
long-term
ly into
complications
patients
common
who
bile
duct
separate-
had
disease
(2.4%)
and
in the those
hilar lesions (17%). As one rethe literature, particularly reports on patients with metallic stents, it is important to separate the results and with
views
related
analysis
of
use
to
the
disease
greater in
These cult
to
endoprostheses
with
of the
but
all
were of
combined
the
terestingly,
with
with
stent
most
recent
diffimany
and!
by
poor
stent,
shortening
stent
is placed.
and
Adam,
considerable
placement,
po-
possibly
natural
the
Lameris
diologists
lesions.
been
caused
the
after
were
hilar
of jaundice
metallic
with
occurs
a
likelihood
cases
cholangitis
that
always in
recurrent
sitioning
in
that
high
have
treat,
Carereports
of problems
patients lesions
location.
previous
indicates
percentage
seen
or
all
of metallic
malignant
In-
two
ra-
experience
have
publications
had and
best results. In general, reviewing the numerous published
the
have
had
the
doprosthesis
in
that
most
patients
long-term
of
long-term
It appears. experienced
who
complications
occlusion that
terms
the results in reports on en-
is difficult.
complications
to
had
problems
overgrowth (perhaps positioning and/or metallic stent) rather
from
needs
debris. be
This
studied
is an
further
beshortthan area be-
cause, if tumor overgrowth was indeed the cause of long-term complications, metallic
more
endoprostheses
encouraging
of
jaundice and/or cholangitis. Irving et al (7), in their summary of a multicenter European clinical trial, reported an approximately 50% rate of recur-
.
Their
disappointing.”
Walistents,
indicated
in
disease.
“.
been
with
cholangitis
malignant
due to tumor cause of poor ening of the
RESULTS
of Patients Complications
53 113
ful
As Lameris et al (1) point of metallic stents increases
Stents
Percentage Long-term
of the
DISADVANTAGES
Conventional
complications
Expense
Despite vantages, potential ing that beneficial
with
No. of Patients
Authors
Because the stents are constructed from extremely thin stainless steel wire, they have a low mass and small surface area. Theoretically, these decrease the possibility of infections. In studies of endoscopically placed endoprostheses, for example, it has been shown that the initiating event of infection occurs when bacteria adhere to the stent surface. This results in secondary deposition of protein and formation of a gelatin matrixlike material that promotes occlusion (14,19,20,21). Because the metallic endoprostheses present less surface area, such adherence would seem less likely to happen. Similarly, the wire mesh often becomes incorporated into the wall of the duct (1,3,5), which further reduces the surface area and decreases the likelihood of infection. In fact, the article by Lameris
Table 2 Results of Treatment
BENIGN The the lignant
use
previous of
metallic
disease,
may
have
a
future.
DISEASE commentary stents primarily
concerns strictly
in
because
June
mathe
1991
13.
Table 3 Results of Treatment
of Malignant
Obstruction
with
Metallic
Stents 14.
Stent
Authors
No. of Patients 16 41 41 69
Gianturco Wallstent Wallstent Wallstent
Coons (1989) (3) Gillams et al (1990) (5) Adam et al (1991) (2) Lameris et al(1991)(1)
Percentage Long-term
of Patients Complications
21 42 7 2 (common 18 (hilar)
with
15. duct) 16.
use
of stents-conventional or metalgenerally somewhat controversial in benign disease. The largest current study of the use of metallic stents in benign disease was reported by RosSi et al (9), who used Gianturco stents to
5.
lic-is
treat benign strictures in 17 patients. Even Rossi et al suggest that only selected patients should undergo this treatment, and only after other, more standard methods have failed. In summary, we are still in a discovery phase with metallic stents. The potential is still unproved and the results are still uncertain. U
6.
7.
8.
References 1.
2.
3.
4.
Lameris JS, Stoker J, Nijs HGT, et al. Malignant biliary obstruction: percutaneous use of self-expandable stents. Radiology 1991; 179:703-707. Adam A, Chetty N, Roddie M, Yeung E, Benjamin IS. Self-expandable stainless steel endoprostheses for treatment of malignant bile duct obstruction. AJR 1991; lS6:321-32S. Coons HG. Self-expanding stainless steel bihiary stents. Radiology 1989; 170:979983. Dick R, Gillams A, Dooley JS, Hobbs KEF. Stainless steel mesh stents for bihiary strictures. J Intervent Radiol 1989; 4:95-98.
Volume
179
Number
#{149}
3
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12.
Gillams A, Dick R, Dooley JS, Wallsten H, El-Din A. Self-expandable stainless steel braided endoprosthesis for biliary strictures. Radiology 1990; 174:137-140. Huibregtse K, Cheng J, Coene PPLO, Fockens P. Tytgat GNJ. Endoscopic placement of expandable metal stents for biliary strictures: a preliminary report on experience with 33 patients. Endoscopy 1989; 21:280-282. Irving JD, Adam A, Dick R, Dondelinger RF, Lunderquist A, Roche A. Gianturco expandable metallic biliary stents: results of a European clinical trial. Radiology 1989; 172:321-326. Roeren T, Brambs HJ, Richter GM, Kauffmann GW. Coated balloon-expandable stent for percutaneous treatment of mahignant biliary obstruction. Radiology 1990; l77(P):238-239. Rossi P, Bezzi M, Salvatori FM, Maccioni F, Porcaro ML. Recurrent benign biliary strictures: management with self-expanding metallic stents. Radiology 1990; 175: 661-665. Dick R, Platts A, Gilford J, Reddy K, Duncan-Irving J. The Carey-Coons percutaneous biliary endoprosthesis: a three-centre experience in 87 patients. Clin Radiol 1987; 38:175-178. Dooley JS, Dick R, George P, Kirk RM, Hobbs KEF, Sherlock S. Percutaneous transhepatic endoprosthesis for bile duct obstruction. Gastroenterology 1984; 86: 905-909. Gibson RN. Transhepatic biliary endoprostheses. J Intervent Radiol 1989; 4:712.
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Lammer J, Neumayer K. Bihiary drainage endoprostheses: experience with 201 placements. Radiology 1986; 159:625-629. McLean GK, Burke DR. Role of endoprostheses in the management of malignant biliary obstruction. Radiology 1989; 170:961-967. Mueller PR, Ferrucci JT Jr. Teplick 5K, et al. Biliary stent endoprosthesis: analysis of complications in 113 patients. Radiology 1985; 156:637-639. Coons HG, Cary PH. Large-bore, long biliary endoprostheses (bihiary stents) for improved drainage. Radiology 1983; 148: 89-94. Mendez G Jr, Russell E, LePage JR. Guerra JJ, Posniak RA, Trefler M. Abandonment of endoprosthetic drainage technique in malignant bihiary obstruction. AJR 1984; 143:617-622. Mueller PR, Tegtmeyer CJ, Saini 5, et al. Metallic biliary stents: early experience (abstr). Radiology 1990; l77(P):307. Rey JF, Marpetit D, Greff M. Experimental study of biliary endoprostheses efficiency. Endoscopy 1985; 17:145-148. Groen AK, Out 1, Huibregtse K, Delzenne B, Hoek FJ, Tytgat GNJ. Characterization of the content of occluded biliary endoprostheses. Endoscopy 1987; 19:57-59. Leung JWC, Ling TKW, Kung JLS, Vallance-Owen J. The role of bacteria in the blockage of biliary stents. Gastrointest Endosc 1988; 34:19-22. Jackson JE, Roddie ME, Yeung EYC, Benjamin IS, Adam A. Biliary endoprosthesis dysfunction in patients with malignant hilar tumors: successful treatment by percutaneous replacement of the stent. AJR 1990; 155:391-395. Lee MJ, Mueller PR, Saini 5, Morrison MC, Brink JA, Hahn PF. Occlusion of biliary endoprostheses: presentation and management. Radiology 1990; 176:531534.
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