U.S. patent application number 10/827957 was filed with the patent office on 2004-10-07 for prosthesis having a sleeve valve.
This patent application is currently assigned to Wilson-Cook Medical Incorporated. Invention is credited to Dua, Kulwinder S., Karpiel, John A., Moore, Scott T..
Application Number | 20040199262 10/827957 |
Document ID | / |
Family ID | 27378622 |
Filed Date | 2004-10-07 |
United States Patent
Application |
20040199262 |
Kind Code |
A1 |
Dua, Kulwinder S. ; et
al. |
October 7, 2004 |
Prosthesis having a sleeve valve
Abstract
Disclosed is a pressure sensitive prosthesis (10) that includes
a tubular member (11) having a passageway (12) extending
therethrough and a sleeve (13) attached about one end of the
tubular member. The sleeve functions as a one-way valve to permit
fluid flowing through the sleeve lumen (15) in a first direction
(17) and under a first pressure, while collapsing in response to
fluid flowing in a second direction 18 where the pressure that
exceeds that of the first direction or pressure. One aspect of the
invention includes an esophageal anti-reflux expandable prosthesis
wherein the sleeve is adapted to invert back through the tubular
stent frame to permit belching or vomiting (fluid or materials
under a third, significantly higher pressure). Another aspect of
the invention includes a tubular drainage stent (60), such as a
biliary or urethral stent in which the sleeve opens to permit
passage of fluids, then collapses to prevent retrograde flow.
Inventors: |
Dua, Kulwinder S.;
(Brookfield, WI) ; Moore, Scott T.; (Rural Hill,
NC) ; Karpiel, John A.; (Winston-Salem, NC) |
Correspondence
Address: |
BRINKS HOFER GILSON & LIONE
P.O. BOX 10395
CHICAGO
IL
60610
US
|
Assignee: |
Wilson-Cook Medical
Incorporated
|
Family ID: |
27378622 |
Appl. No.: |
10/827957 |
Filed: |
April 20, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10827957 |
Apr 20, 2004 |
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09876520 |
Jun 7, 2001 |
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6746489 |
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10827957 |
Apr 20, 2004 |
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09386173 |
Aug 31, 1999 |
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6302917 |
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60211753 |
Jun 14, 2000 |
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60098542 |
Aug 31, 1998 |
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Current U.S.
Class: |
623/23.7 ;
623/23.66 |
Current CPC
Class: |
A61F 2/04 20130101; A61F
2/86 20130101; A61F 2002/044 20130101 |
Class at
Publication: |
623/023.7 ;
623/023.66 |
International
Class: |
A61F 002/04 |
Claims
1. A prosthesis for placement in a patient comprising: a tubular
drainage stent having a passage extending longitudinally
therethrough; and a sleeve extending from an end of the tubular
drainage stent and having a lumen extending longitudinally
therethrough and communicating with the passage of the tubular
drainage stent, the sleeve in response to a fluid applying a first
pressure in a first direction passing the fluid through the lumen
thereof, the sleeve collapsible to at least substantially close the
lumen in response to a fluid applying a second pressure in a second
direction.
2. The prosthesis of claim 1, wherein a portion of the sleeve
extends over an outer surface of the tubular drainage stent and is
affixed thereto.
3. The prosthesis of claim 2, wherein the sleeve includes an
attachment member that affixes the sleeve to the tubular drainage
stent.
4. The prosthesis of claim 3, wherein the attachment member
comprises a metal band.
5. The prosthesis of claim 1, wherein the sleeve comprises a
bile-resistant polymeric material.
6. The prosthesis of claim 5, wherein the material comprises
expanded polytetrafluoroethylene.
7. The prosthesis of claim 1, wherein the material comprises
polyurethane.
8. The prosthesis of claim 1, wherein the sleeve has an average
thickness in the range of approximately 0.001" to 0.01".
9. The prosthesis of claim 8, wherein the sleeve has an average
thickness of approximately 0.002" to 0.005".
10. The prosthesis of claim 9, wherein the sleeve has a thickness
of approximately 0.0025".
11. The prosthesis of claim 1, wherein the tubular drainage stent
is sized and configured for placement in the biliary system such
that the sleeve is extendable into the intestine of the patient
such that bile travels in the first direction thereinto.
12. The prosthesis of claim 1, wherein the prosthesis further
includes a guiding catheter and pusher element having a distal end,
the prosthesis being mounted over the guiding catheter such that
the prosthesis is deliverable to a target site within the patient
by way of the distal end of the pusher element urging the
prosthesis distally and relative to the guiding catheter until the
prosthesis is deployed therefrom.
13. The prosthesis of claim 1, wherein the sleeve and tubular
drainage stent comprise the same polymeric material, the sleeve
representing an integral extension of the one end of the tubular
drainage stent.
14. The prosthesis of claim 1, wherein the sleeve is normally
closed in the absence of the fluid applying a first pressure in a
first direction.
15. The prosthesis of claim 1, wherein the end form which the
sleeve extends includes a pigtail configuration.
16. A prosthesis for placement in a patient comprising: a tubular
drainage stent sized and configured for placement in the biliary
system, the tubular drainage stent having a passage extending
longitudinally therethrough; and a sleeve comprising a polymeric
material, the sleeve extending from an end of the tubular drainage
stent and having a lumen extending longitudinally therethrough and
communicating with the passage of the tubular drainage stent, the
sleeve in response to a fluid applying a first pressure in a first
direction passing the fluid through the lumen thereof, the sleeve
collapsible to at least substantially close the lumen in response
to a fluid applying a second pressure in a second direction.
17. The prosthesis of claim 16, wherein the sleeve is normally
closed in the absence of the fluid applying a first pressure in a
first direction.
18. The prosthesis of claim 16, wherein the material comprises
expanded polytetrafluoroethylene.
19. The prosthesis of claim 16, wherein the sleeve has an average
thickness of approximately 0.002" to 0.005".
20. The prosthesis of claim 14, wherein the prosthesis further
includes a guiding catheter and pusher element having a distal end,
the prosthesis being mounted over the guiding catheter such that
the prosthesis is deliverable to a target site within the patient
by way of the distal end of the pusher element urging the
prosthesis distally and relative to the guiding catheter until the
prosthesis is deployed therefrom.
21. A prosthesis for placement in a patient comprising: a tubular
drainage stent sized and configured for placement in a bodily
passageway, the tubular drainage stent having a passage extending
longitudinally therethrough, and a sleeve comprising a thin,
flexible polymeric material, the sleeve attached about the tubular
drainage stent and having a lumen extending longitudinally
therethrough and communicating with the passage of the tubular
drainage stent, the sleeve in response to a fluid applying a first
pressure in a first direction passing the fluid through the lumen
thereof, the sleeve collapsible to at least substantially close the
lumen in response to either a fluid applying a second pressure in a
second direction or the absence of the fluid applying a first
pressure in a first direction.
22. The prosthesis of claim 21, wherein the sleeve extends from an
end of the tubular drainage stent.
23. The prosthesis of claim 21, wherein one end of the sleeve is
affixed within the lumen of the tubular drainage stent.
24. The prosthesis of claim 21, wherein the sleeve resides
completely within the lumen of the tubular drainage stent.
25. (Cancelled)
26. (Cancelled)
27. (Cancelled)
28. A prosthesis for placement in a patient comprising: a tubular
drainage stent having a passage extending longitudinally there
through configured to pass only bodily matter; a retention
structure extending from an outer surface of the passage and
comprising a flexible material configured to hold the tubular
drainage stent within a vessel that conveys fluid without enlarging
a diameter of the passage; and a sleeve extending from an end of
the tubular drainage stent and having a lumen extending
longitudinally there through and communicating with the passage of
the tubular drainage stent, the sleeve in response to a fluid
applying a first pressure in a first direction passing the fluid
through the lumen thereof, the sleeve collapsible to at least
substantially close the lumen in response to a fluid applying a
second pressure in a second direction.
29. The prosthesis of claim 28, wherein the retention structure
comprises a structure selected from the group consisting of a flap
and a barb.
30. The prosthesis of claim 28, wherein the tubular drainage stent
is sized and configured for placement within a body passage
selected from the group consisting essentially of a bile duct, a
pancreatic duct, and a urethra.
31. The prosthesis of claim 28, wherein the tubular drainage stent
is sized and configured for placement within a body passage
selected from the group consisting of a pancreatic duct and a
urethra.
32. (Cancelled)
33. (Cancelled)
34. A prosthesis for placement in a patient comprising: a tubular
drainage stent having a passage sized and configured for placement
within a pancreatic duct; a retention structure extending from an
outer surface of the passage comprising a flexible material
configured to expand without enlarging a diameter of the passage;
and a sleeve extending from an end of the tubular drainage stent
and having a lumen extending longitudinally there through and
communicating with the passage of the tubular drainage stent, the
sleeve in response to a fluid applying a first pressure in a first
direction passing the fluid through the lumen thereof, the sleeve
collapsible to at least substantially close the lumen in response
to a fluid applying a second pressure in a second direction.
35. A prosthesis for placement in a patient comprising: a tubular
drainage stent having a passage sized and configured for placement
within a urethra; a retention structure extending from an outer
surface of the passage comprising a flexible material configured to
expand without enlarging a diameter of the passage; and a sleeve
extending from an end of the tubular drainage stent and having a
lumen extending longitudinally there through and communicating with
the passage of the tubular drainage stent, the sleeve in response
to a fluid applying a first pressure in a first direction passing
the fluid through the lumen thereof, the sleeve collapsible to at
least substantially close the lumen in response to a fluid applying
a second pressure in a second direction.
36. A prosthesis for placement in a patient comprising: a tubular
drainage stent having a passage sized and configured for conveying
a glandular secretion; a retention structure extending from an
outer surface of the passage comprising a flexible material
configured to expand without enlarging a diameter of the passage;
and a sleeve extending from an end of the tubular drainage stent
and having a lumen extending longitudinally there through and
communicating with the passage of the tubular drainage stent, the
sleeve in response to a fluid applying a first pressure in a first
direction passing the fluid through the lumen thereof, the sleeve
collapsible to at least substantially close the lumen in response
to a fluid applying a second pressure in a second direction.
37. A prosthesis for placement in a patient comprising: a
non-expanding tubular drainage stent sized and configured for
placement in a bodily passageway, the tubular drainage stent having
a passage extending longitudinally there through, and a sleeve
comprising a thin, flexible polymeric material, the sleeve attached
about the tubular drainage stent and having a lumen extending
longitudinally there through and communicating with the passage of
the tubular drainage stent, the sleeve in response to a fluid
applying a first pressure in a first direction passing the fluid
through the lumen thereof, the sleeve collapsible to at least
substantially close the lumen in response to either a fluid
applying a second pressure in a second direction or the absence of
the fluid applying a first pressure in a first direction.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority of provisional application
Serial No. 60/211,753, filed Jun. 14, 2000, and is a
continuation-in-part of co-pending U.S. patent application Ser. No.
09/386,173, filed Aug. 31, 1999, which claims priority to
provisional application Serial No. 60/098,542, filed Aug. 31,
1998.
TECHNICAL FIELD
[0002] This invention relates generally to medical devices and, in
particular, to an indwelling valved prosthesis.
BACKGROUND OF THE INVENTION
[0003] Anti-reflux esophageal prosthesis or stents are typically
placed in the lower esophagus and through the lower esophageal
sphincter to maintain the patency thereof due to the presence of a
cancerous tumor commonly found in the vicinity thereof. The
cancerous tumor growth typically impinges the flow of food and
fluids through the esophagus. Lower esophageal cancer in the United
States presently occurs at the rate of approximately 12,000
patients per year. The incidence in the United States is
approximately 5.1 per 100,000 people, which is rising particularly
in white male patients. Esophageal prosthesis or stents are
typically utilized in these cancerous patients. However, these
devices are not FDA approved for benign tumors which also cause
blockage or partial stenosis of the esophagus. Esophageal
prosthesis or stents are utilized in Europe and other countries for
benign tumor conditions, but not in the United States at this
time.
[0004] A problem with esophageal prosthesis or stents is that fluid
from the stomach flows into the mouth of the patient when in a
prone position. In an attempt to solve this problem, a number of
esophageal prosthesis or stents utilize a one-way valve such as a
duck-bill or reed-type valve in which only food or fluid from the
esophagus flows into the stomach in only an antegrade or forward
direction. However, these one-way anti-reflux prosthesis or stents
present another problem. When the patient wants to belch or vomit,
he/she is prevented from doing so, because the one-way valve
prevents backward flow in the retrograde direction. Such condition
is not only painful to the patient, but can also lead to more
complicated medical conditions.
[0005] There are other anatomical sites, such as the biliary tree
or genitourinary system in which a prosthesis may be placed to
maintain an open lumen for passage of bodily fluids, thereby
creating risk of undesirable retrograde flow and/or migration of
pathogenic organisms which could lead to infection or other
problems, such as obstruction of the stent. When a drainage stent
or catheter is placed across a sphincter or natural stricture at
the opening to a bodily passage, the sphincter or stricture cannot
fulfill its normal function of restricting retrograde flow or
migration. What is needed is a prosthesis and one-way valve that
can effectively regulate antegrade and retrograde flow in response
to the normal flow rates and pressures that exist across the site
in which the prosthesis is placed.
SUMMARY OF THE INVENTION
[0006] The foregoing problems are solved and a technical advance is
achieved in an illustrative prosthesis having a sleeve which
permits antegrade flow under a first pressure through the sleeve,
and collapses in response to a second flow or pressure that is
greater than the first flow or pressure.
[0007] In one aspect of the invention, the prosthesis comprises an
anti-reflux esophageal prosthesis in which a sleeve extending from
a tubular frame thereof inverts through the passage of the tubular
frame and allows stomach gas or vomit to flow in a retrograde
direction when the pressure in the stomach exceeds a given level.
In the antegrade or downward position, the sleeve collapses and
prevents the reflux of stomach gas and fluid from flowing through
the esophagus and into the mouth of the patient. The collapsible
sleeve functions as a one-way valve and allows the patient to
ingest or pass liquid and food therethrough and into the stomach.
In addition, the tubular frame of this advantageous anti-reflux
esophageal prosthesis maintains the patency of the lower esophagus
and sphincter particularly when a cancerous tumor impedes fluid
flow through the esophagus.
[0008] In another advantageous aspect of the present invention, the
tubular frame of the anti-reflux esophageal prosthesis includes a
plurality of self-expanding zig-zag stents. The compressed stents
along with the sleeve are positioned in an delivery catheter which
is orally passed through the esophagus and lower sphincter. The
prosthesis is then deployed from the delivery catheter with, for
example, a dilator or pusher catheter that is inserted in the lumen
of the delivery catheter. The deployed, self-expanding stents
readily expand to engage the esophagus and lower sphincter and
maintain them in a patent condition.
[0009] The self-expanding stents of the tubular frame are also
advantageously flared at each end of the tubular frame to prevent
antegrade and retrograde migration of the expanded prosthesis. To
further prevent migration of the zig-zag stents with respect to
each other, a filament is circumferentially positioned through
closed eyelets at the bends of adjacent zig-zag stents. The
filaments are also utilized advantageously to control the radial
expansion and the flared configuration of the stents positioned at
the ends of the tubular frame.
[0010] The pressure needed to collapse or invert the one-way
valvular sleeve is a function of the sleeve material, its wall
thickness and length extending from the distal end of the tubular
frame. Depending on the anatomical size of the human or veterinary
patient, the sleeve can extend from the end of the frame for a
length in a range of from 0.0 to 20 cm, preferably in a range of 5
to 15 cm; and more preferably in length of approximately 10 cm in a
human patient or 8 cm in a veterinary patient as experimentally
derived therefor. The sleeve material also advantageously includes
a material of polyurethane, silicone, polyamides, other urethanes
or any biocompatible material that is flexible and acid resistant.
The sleeve material can have an advantageous thickness of 0.005"
through 0.008".
[0011] This thickness is at the portion covering the frame itself.
The sleeve extending from an end of the frame comprises a material
having a thickness in a range of 0.0015" to and including 0.004"
and preferably approximately 0.002". Advantageously, the length of
the sleeve is made long enough so that it can be readily shortened
to accommodate individual anatomical situations.
[0012] In another aspect of the invention the collapsible sleeve is
attached to a tubular drainage stent, such as a biliary stent, to
advantageously prevent reflux of intestinal contents and the
associated bacteria into the passage of the stent. These bacteria
are known to promote the formation of biofilm which can lead to
occlusion of the stent. With the stent placed in the biliary tree
for maintaining patency of the bile or pancreatic duct and the
Papilla of Vater, the sleeve extends down into the duodenum to
provide a one-way valve for the flow of bile. When bile is not
being secreted, the sleeve advantageously collapses to prevent
backflow of material from the duodenum, a situation which might
otherwise occur in a biliary stent without a closure means. Tubular
drainage stents for placement in the ureters or urethra can include
either a sleeve extending from one end to permit urine flow and
prevent retrograde flow or pathogen migration toward the kidneys or
bladder, or the sleeve may be located completely within the lumen
of the drainage stent with one end of the sleeve being bonded or
otherwise attached to the inner walls of the lumen.
BRIEF DESCRIPTION OF THE DRAWING
[0013] FIG. 1 depicts a pictorial view of an illustrative
embodiment of a pressure sensitive anti-reflux esophageal
prosthesis of the present invention;
[0014] FIG. 2 depicts an enlarged cross-sectional view of a sleeve
about a cylindrical wire of a flared stent of the esophageal
prosthesis taken along line 2-2 of FIG. 1;
[0015] FIG. 3 depicts an enlarged partially sectioned view of the
adjacent ends of interconnected stents of the prosthesis of FIG.
1;
[0016] FIG. 4 depicts a two piece mandril that is used to apply the
sleeve material to the prosthesis of FIG. 1;
[0017] FIG. 5 depicts the esophageal prosthesis of FIG. 1 deployed
in the lower esophagus of a patient, and, in particular, through
the lower esophageal sphincter and a cancerous tumor;
[0018] FIG. 6 depicts the anti-reflux esophageal prosthesis of FIG.
1 in a collapsed state in a delivery catheter;
[0019] FIG. 7 depicts the delivery catheter of FIG. 6 positioned in
the lower esophagus, sphincter, and tumor of a patient;
[0020] FIG. 8 depicts an in-vitro barrier reflux curve for an
anti-reflux esophageal prosthesis of the present invention;
[0021] FIGS. 9 and 10 depict the percent of fraction time of
standard and anti-reflux esophageal prosthesis utilized in an
evaluation of the present invention;
[0022] FIG. 11 depicts a pictorial view of an embodiment of a
tubular drainage prosthesis of the present invention;
[0023] FIG. 12 depicts a cross-sectional view of a second
embodiment of a tubular drainage prosthesis;
[0024] FIG. 13 depicts the prosthesis of FIG. 11 positioned in the
common bile duct of a patient;
[0025] FIG. 14 depicts a side view of the prosthesis of FIG. 11
mounted on a delivery system;
[0026] FIG. 15 depicts a side view of one end of a valved
prosthesis that includes a pigtail configuration; and
[0027] FIG. 16 depicts a laterally sectioned view of a valved
prosthesis in which the sleeve is affixed with the lumen.
DETAILED DESCRIPTION
[0028] FIGS. 1-14 depict exemplary prostheses of the present
invention comprising a tubular member 11 with a passage 12
therethrough, and a thin, flexible sleeve 13 extending from the
tubular member 11. The sleeve 13, which also has a passage 15
therethrough, is configured to allow the flow of liquid or other
materials moving under a first pressure until the flow and pressure
are lessened where they are exceeded by the second, back pressure
of the drainage environment, at which time the sleeve 13 collapses
to prevent the ingress of fluids of materials into the tubular
member.
[0029] FIG. 1 depicts a pictorial view of an illustrative,
preferred embodiment of pressure sensitive anti-reflux esophageal
prosthesis 10 of the present invention. The prosthesis includes a
tubular frame 11 of a plurality 19 of self-expanding, zig-zag wire
stents 20, 21, and 23 covered by a polyurethane sleeve 13 that is
disposed around and extends along entire length 27 of the tubular
frame. The sleeve also extends from distal end 14 of the
self-expanding tubular frame and has a lumen 15 extending
longitudinally therethrough. Lumen 15 of the sleeve also
communicates with passage 12 of the tubular frame. When the
prosthesis is positioned in the lower esophagus and through the
lower sphincter of a patient, lumen 15 in lower portion 28 of the
sleeve collapses upon itself due to wetting by gastric juices,
fluid or saliva flowing therethrough from the esophagus in a first
direction 17. As a result, sleeve 13 is in a collapsed position and
acts as a one-way valve into the stomach, thereby preventing the
reflux of gastric fluid from flowing in a retrograde manner through
the prosthesis and esophagus and into the mouth of the patient,
referred to herein as the second direction 18. However, fluid
readily flows in the opposite (first) direction 17 from the
esophagus and through the one-way valve sleeve into the patient's
stomach.
[0030] Tubular frame 11 includes plurality 19 of self-expanding
stents 20, 21, and 23 that are interconnected circumferentially by
filament 24 about adjacent ends 25 and 26 of the stents. In this
illustrative embodiment, the tubular frame includes four
self-expanding, zig-zag wire metal stents of the Gianturco type as
described in U.S. Pat. No. 4,580,568, which is incorporated by
reference herein. Tubular frame includes first and second flared
stents 20 and 21 positioned at distal and proximal ends 14 and 22
with first and second cylindrical stents 23 positioned
therebetween. By way of example, first and second flared stents 20
and 21 have a minimum diameter of 18 mm and a flared diameter of
approximately 25 mm. These diameters are nominal diameters for the
stents and can be customized to meet the particular demands of any
human or veterinary patient. The diameter of the flared end is
maintained by end filament 29. The minimum diameter of the flared
stents along with the nominal diameter of the cylindrical stents is
maintained by interconnecting filaments 24. The interconnecting and
end filaments 24 and 29 are, for example, 3/0 diameter mononylon
suture material. The first and second flared stents 20 and 21 are
positioned below and above the lower esophageal sphincter and
prevent the migration of the prosthesis in either the antegrade or
retrograde direction with respect to the esophagus. The flared
proximal stent along with the cylindrical stents 23 also expand
against any tumor that is in the region of the lower esophagus and
maintains the patency of the lower esophageal lumen.
[0031] Flared stents 20 and 21 are, for example, formed from
commercially available Series 304 stainless steel cylindrical wire
having a diameter of approximately 0.015". The wire is formed into
a zig-zag pattern of which the ends are joined together using, for
example, a metal sleeve and soldered together using silver/tin
solder. However, other ways of forming a closed zig-zag
configuration that resembles at least a partially tubular shape is
contemplated. The flared or maximum diameter of the flared stents
is approximately 25 mm with the minimum diameter at approximately
18 mm. Interconnecting cylindrical stents 23 are also formed from
the same cylindrical wire and have a nominal diameter of
approximately 18 mm matching that of the minimum diameter of the
flared stents. The length of the individual stents is approximately
2 cm. The overall length of the tubular frame can range from 8 to
14 cm in 2 cm increments. These 2 cm increments are typically
provided by increasing the number of interconnecting cylindrical
stents 23.
[0032] Sleeve 13 preferably comprises a polyurethane material or
other liquid impermeable material that does not degrade in the
presence of fluids or gastric material that comes in contact
therewith. The sleeve is disposed around and extends at least
partially around tubular frame 11. Preferably, the sleeve extends
the entire length of the frame and extends longitudinally from
distal end 14 of the tubular frame. The length of the sleeve
material extending from the distal end of the tubular frame can
range from 0 through 20 cm, preferably 5 to 15 cm, and more
preferably 10 cm. The length of the sleeve material can be
individually customized by the physician depending on the anatomy
of the patient. Experimental data has indicated that dogs typically
utilize a 7 cm length of sleeve material. Human patients are
expected to utilize a sleeve length of 8 or 9 cm. However, the
length can again be modified by the physician to meet the
particular anatomy of the patient. The wall thickness of the sleeve
material disposed around the tubular frame is approximately 0.006"
thick. The thickness of the sleeve material along lower portion 28
of the sleeve is approximately 0.002" thick.
[0033] The sleeve material preferably includes a medical grade
polyurethane material; although silicone, nylon, polyamides such as
other urethanes, or other biocompatible material that is flexible
and acid resistant are also suitable materials. In particular, the
polyurethane of the present invention is a medical grade
polyurethane material grade EG-80A material commercially known as
TECOFLEX.RTM. polyurethane material from Thermedics, Incorporated,
Woburn, Mass.
[0034] FIG. 2 depicts an enlarged sectioned end view of sleeve 13
about cylindrical wire 30 of flared stent 20 of FIG. 1 along the
line 2-2. As shown, the thickness of the sleeve material is
approximately 0.006", whereas the thickness of the sleeve material
along lower or distal portion 28 thereof is preferably and
approximately 0.002". The thickness of sleeve material above distal
portion 28 ranges from 0.005" through 0.008". Experimental data has
indicated that the sleeve material along distal portion 28 still
collapses at 0.004" wall thickness so as to effectively form a
one-way valve. Closure of the one-way valve sleeve material occurs
at thicknesses above 0.004"; however, closure does not occur on a
guaranteed basis each time. The thickness of the sleeve wall
material below 0.0015" presents a problem of tearing particularly
when inserting the prosthesis into a delivery catheter.
[0035] FIG. 3 depicts an enlarged partially sectioned view of
adjacent ends 25 and 26 of interconnected stents 20 and 23 of FIG.
1. Bends 31 of cylindrical wire 30 are formed into a keyhole
configuration with silver solder 32 interconnecting the wire arms,
thereby forming an aperture or eyelet 33. Interconnecting filament
24 is positioned through each eyelet and wound around at least once
to aid in fixing the diameter of the expandable stents. One
interconnecting or end filament is used at the end of each stent
and tied at the loose ends with suture knot 34.
[0036] FIG. 4 depicts two piece mandril 35 that is used to apply
sleeve material 13 to the prosthesis of FIG. 1. The mandril
includes sleeve portion 36 and upper frame portion 37 that are
interconnectable with, for example, threaded rod 38 and internally
threaded channel 39. In use, the tubular frame including the
plurality of self-expanding wire stents are positioned end-to-end
and interconnected using interconnecting filament 24. The end
filament is also positioned through the eyelets of the flared
stents to control the maximum diameter thereof. The mandril has a
minimum inner diameter matching that of the inside diameter of the
inner stents and a flared diameter matching that of the flared
stents. Extending from the ends of the flared portions, the mandril
assumes the inner diameter of the one-way valve sleeve material.
The assembled tubular frame is positioned between the upper frame
portion of the sleeve portion of the mandril. The two portions of
the mandril are then interconnected, thereby filling up the passage
of the tubular frame. The tubular frame is then dipped into a
slurry material of polyurethane to form an initial 0.004" thickness
over the entire length of the tubular frame. The mandril and
covered tubular frame are then dipped in the slurry material at
least one additional time to form the desired thickness of the
sleeve material over mandril sleeve portion 36. After the slurry
material cures, the two portions of the mandril are disconnected to
form the anti-reflux esophageal prosthesis.
[0037] FIG. 5 depicts esophageal prosthesis 10 deployed in lower
esophagus 40, and, in particular, through lower esophageal
sphincter 41 and cancerous tumor 42. Distal flared stent 20
typically extends into the stomach along with sleeve 13. Flared
stent 21 is positioned proximal to the sphincter and tumor, whereas
the interconnected cylindrical stents are typically positioned
through the sphincter and tumor. The flared stents 20 and 21,
again, prevent a migration of the prosthesis in the esophagus. The
lower or distal portion 28 of sleeve 13 extends into stomach 43.
The lumen of the lower sleeve portion readily collapses when in
contact with any external fluid applied thereto. However, any
liquid or food is readily passed in an antegrade direction through
the esophageal stent and into the stomach. As a result, one-way
valve sleeve 13 opens to provide flow in the antegrade direction.
Conversely, any fluids or food material 44 are prevented from
flowing into the retrograde direction due to the collapsed lumen of
sleeve 13. However, when the pressure of the gas or fluid in the
stomach builds so as to cause the patient to belch or vomit, sleeve
13 will invert and extend in an antegrade direction through the
lumen of the tubular frame as shown by phantom lines 45. In this
position, gastric fluid and matter flows in the retrograde
direction to relieve the patient. The length of distal portion 28
of the sleeve and the thickness thereof control the pressure at
which the distal portion of the sleeve inverts through the tubular
frame.
[0038] Self-expanding esophageal prosthesis are increasingly being
used for palliation of malignant dysphagia. They can predispose to
significant gastroesophageal reflux, including risk of aspiration,
when deployed across the gastroesophageal junction. A study was
performed to evaluate the anti-reflux efficacy of a esophageal
prosthesis of the present invention to prevent reflux. A model EZS
21-8 from Wilson-Cook Inc., Salem, N.C. (16 mm diameter) was
modified by extending its polyurethane covering 7 cm beyond its
distal metal cage so as to form a "windsock" or collapsible sleeve.
The pressure required to invert the windsock or collapsible sleeve
into the tubular frame (reflux barrier) was determined by attaching
the proximal end of the prosthesis to a hollow graduated tube and
vertically inserting the stent under water until the windsock
inverted. The pressure required to revert the windsock or
collapsible lumen to its original one-way position was determined
by pouring water into the lumen of the prosthesis. In-vivo
evaluation was done in two esophagostomized dogs (male-18 kg,
female-16 kg) and prosthesis insertion, positioning, and removal
done by standard endoscopic and fluoroscopic techniques. Two site
ambulatory esophageal pH monitoring (Synectics Medical) was
performed at 5 cm and 10 cm above the gastroesophageal function.
Each dog was studied twice using the standard model EZS 201-8
prosthesis and twice using the modified prosthesis (mean recording
time per session 18.7+/-1 SE and 17+/-3 hours respectively). The
results indicated that the windsock modification posed no
difficulty in mounting or deploying the prosthesis using a
currently available delivery system. Resistance to antegrade flow
was minimal as even a drop of water put into the prosthesis easily
passed through the windsock and both the dogs drank all the Ensure
(4 cans per session) given to them irrespective of the type of
prosthesis used. The pressure (cm of water) to overcome the reflux
barrier was 15.7+/-0.3 SE and that to revert an inverted windsock
or collapsible lumen was 0.4+/-0.03 SE. Results of the pH
monitoring (mean +/-SE) is depicted in Table 1.
1TABLE 1 Recording Standard Stent Anti-reflux Stent site (cm) above
GEJ 5 10 5 10 Number of reflux 229 .+-. 25" 56 .+-. 9@ 9.7 .+-. 7*
8 .+-. 5@ episodes Fraction time pH 60 .+-. 5* 7.6 .+-. 2@ 0.7 .+-.
0.3* 0.2 .+-. 0.1@ <4 (%)
[0039] The conclusions reached in the experiment were that a
modified self-expanding metal esophageal prosthesis is highly
effective in preventing reflux. The ability of the windsock or
collapsible lumen sleeve 13 to invert at higher pressure gradients
can allow patients to belch or vomit. Reversion to anti-reflux
position requires minimal pressure and can be achieved by a water
swallow. Further studies are indicated in FIGS. 8-10.
[0040] FIG. 6 depicts anti-reflux esophageal prosthesis 10 of FIG.
1 in a collapsed state in delivery catheter 46. Sleeve material 13
is positioned at the distal end of the delivery catheter. The
prosthesis is drawn into the delivery catheter with a drawstring
attached at the proximal end of the prosthesis. The drawstring and
prosthesis are inserted through lumen 47 of the catheter by
collapsing the tubular frame and then pulling the prosthesis into
the distal end of the delivery catheter with the drawstring. To
deploy the collapsed prosthesis from the delivery catheter, a
pusher catheter 48 is positioned proximally in lumen 47 to engage
the proximal end of the wire tubular frame 11.
[0041] FIG. 7 depicts delivery catheter 46 of FIG. 6 positioned in
lower esophagus 40, sphincter 41, and tumor 42 of a patient. The
distal end of the delivery catheter extends into stomach 43. As
shown, the pusher has been placed in the lumen of the delivery
catheter and engages the proximal end of prosthesis 10. As shown,
sleeve 13 and flared distal stent 20 have been deployed from the
distal end of the catheter. After the sleeve and distal flared
stent 20 of the prosthesis have been deployed, the delivery
catheter is partially withdrawn so as to engage the flared stent
with the neck of the stomach about sphincter 41. Once positioned,
the delivery catheter is pulled back while maintaining the position
of the pusher catheter therein so as to release the central
cylindrical stents and proximal flared stent against the sphincter,
tumor, and lower esophagus.
[0042] An in-vitro and in-vivo evaluation of a modified
self-expandable metal esophageal stent with an anti-reflux
mechanism of the present invention was performed on a number of
dogs. The evaluation included four dogs, two of which were males at
14 and 18 kg and two females at 14 and 16 kg. An esophagostomy was
utilized with the use of upper gastro-intestinal endoscopy. The
evaluation included the methods of ambulatory pH monitoring with
the use of Synectics medical equipment at 5 and 10 cm with
Gastrograph Inc. software. A liquid diet of Ensure at a pH of 6.5
was administered. The results of the employed methods are included
in Table 2.
2TABLE 2 Standard Stent Anti-Reflux Stent P Duration of pH 20.30
.+-. 1.6 21.38 .+-. 0.9 ns Monitoring (hrs .multidot. mins) Oral
Intake Ensure (ml) 1007 .+-. 0.5 978 .+-. 0.4 ns
[0043] FIG. 8 depicts in-vitro reflux barrier curve 48 which
illustrates the water column height in centimeters necessary to
invert a given sleeve length extending from the distal end of the
prosthesis. Rectangular median value boxes 49 indicate the median
value of the water column height at the indicated sleeve lengths.
The vertical bar 50 positioned on curve 48 with rectangular median
value boxes 49 represent a standard deviation above and below the
indicated median value. In addition, the number of reflux episodes
was monitored at the distal and proximal ends of the prosthesis.
With a standard prosthesis without a one way valve, 197 episodes of
reflux were encountered in 250 attempts. At the proximal end of the
standard tubular esphageal prosthesis, a total of 33 reflux
episodes were noted with 50 attempts. Correspondently, only 16
reflux episodes were noted out of 250 attempts at the distal end of
an anti-reflux esophageal prosthesis of the present invention. At
the proximal end of the anti-reflux esophageal stent only 8
episodes out of 50 attempts were noted. The number of reflux
episodes longer than five minutes was also noted. In the standard
prosthesis, 19.8 episodes were recorded for 25 attempts. This is in
contrast to 0.3 episodes for an anti-reflux esophageal stent of the
present invention. At the proximal end of the prosthesis, 2.3
episodes lasting longer than five minutes were noted with three
attempts; whereas none were noted with the anti-reflux prosthesis.
The longest reflux episodes were also noted at the distal and
proximal ends of the standard and anti-reflux prosthesis. For the
standard prosthesis, 107 episodes were noted out of approximately
130 attempts; whereas only 3.8 were noted for the anti-reflux
prosthesis at the distal end thereof. At the proximal end of the
prosthesis, 39 episodes were noted out of 45 for the standard
prosthesis; whereas only 1.8 for the anti-reflux prosthesis were
noted.
[0044] FIG. 9 depicts the fraction time percentages of which the
esophagus was exposed to gastric juice with a pH less than 4. At
the distal end of the prosthesis, the percentage of fraction time
is indicated by boxes 51 for the four dogs at the distal end of the
standard prosthesis. These percentage fraction times range from
20-80% with a median value of 49%.
[0045] For the anti-reflux prosthesis, the percentage of fraction
time ranges from 0.0 to approximately 1.5% with a median value of
1% as indicated by boxes 52. The p-values for these fractions times
is 0.026.
[0046] FIG. 10 depicts the fraction time percentages at the
proximal ends of the standard and anti-reflux prosthesis. Boxes 53
represent the percent fraction time for the standard prosthesis
which ranges from approximately 4-14% with a median of 6.6%.
Rectangular boxes 54 represent the percent fraction time for the
anti-reflux prosthesis which range from approximately 0.0 to 1.0%.
These have a p-value of approximately 0.055.
[0047] The conclusions resulting from this in-vitro and in-vivo
evaluation are as follows. The modified self-expanding metal
esophageal stent of the present invention is highly effective in
preventing gastro-esophageal reflux. The ability of the
modification to invert at higher pressure gradients allows for
belching and vomiting. Once inverted, reversion to the anti-reflux
position of the prosthesis requires minimal pressure that can be
achieved by a water swallow.
[0048] In a second embodiment of the present invention depicted in
FIGS. 11-14, the prosthesis 10 and tubular member 11 comprise a
tubular drainage stent 60 having a first end 62 for drainage into a
duct, vessel, organ, etc., 30 and a second end 63 that receives the
fluid or other material that is moving under a first, antegrade
pressure and direction 17. As defined, a tubular drainage stent (or
tubular drainage catheter) is typically an elongate, closed tubular
conduit (typically plastic or metal) that is placed within a bodily
passage, such as the bile duct, pancreatic duct, urethra, etc. to
facilitate the flow of fluids therethrough. It is typically
non-expanding, unlike a the wire or open-frame stents of FIGS.
1-10. It is commonly placed either to establish or maintain patency
of the bodily passage or to drain an organ or fluid source, such as
the gall bladder or urinary bladder. The tubular drainage stent may
also include a retention means 64,65 at one or more ends 62,63,
such as flaps, barbs, pigtail loops, etc. The tubular drainage
stent 60 is attached to the collapsible sleeve 13, which acts as a
one-way valve to prevent retrograde flow 18 therethrough. The first
end 67 of the sleeve is maintained open when the fluid or material
passing through the sleeve is exhibiting a pressure associated with
normal antegrade flow 17. The first end 67 collapses shut when the
antegrade flow 17 has ceased or lessened such that the second fluid
pressure 18 occurring in the environment into which the fluid is
drained becomes higher than the first pressure of the antegrade
flow 17. In the illustrative biliary stent embodiment, bile is able
to flow into the duodenum 71, but the sleeve 13 closes in the
absence of measurable flow 17, thus preventing the contents of the
intestinal tract, which now have a second, higher pressure 18, from
entering the passageway of the stent. The sleeve 13 is made of a
biocompatible material that will not degrade when placed in the
particular environment of the human body into which it is to be
placed. Possible materials include expanded polytetrafluoroethylene
(ePTFE), polyurethane, silicone, nylon, polyamides such as other
urethanes, or other biocompatible materials. It is important that
the sleeve material be selected appropriately. For example, in the
illustrative embodiment, the sleeve is typically made of a 2-3 cm
section of ePTFE which is much more resistant to the caustic bile
than would a sleeve of polyurethane. The ePTFE tube is extruded
into a thin wall tube having sufficient flexibility to collapse and
seal against the ingress of fluid, while having sufficient
integrity to resist tearing. The normal range of sleeve thickness
for the illustrative embodiment is 0.001 to 0.01 in., with a more
preferred thickness of 0.002 to 0.005 in (e.g., 0.0025). The second
end 68 of the sleeve is attached about the first end 62 of a
biliary stent 60, such as a ST-2 SOEHENDRA TANNENBAUM.RTM. stent, a
COTTON-LEUNG.RTM. stent or a COTTON-HUIBREGTSE.RTM. stent
(Wilson-Cook Medical Inc., Winston-Salem, N.C.), by an attachment
means 66, such as an illustrative crimped metal band. This band 66
can be made radiopaque to also serve as a fluoroscopic marker.
Other methods of attachment could include, suture binding, selected
medical grade adhesives, or thermal bonding, if appropriate for
both the sleeve and stent polymers.
[0049] An alternative method of forming the sleeve for a tubular
drainage stent 60 is depicted in FIG. 12. Rather than attaching a
separately extruded or preformed sleeve 13 to the tubular member
11, the wall of the tubular member, which is made of polyethylene
in this embodiment, is thinned out distally from the first end 62
of the tubular drainage stent 60, such that the sleeve 13 is
integral with the tubular member 11. A transition zone 77 exists
between the first end tubular drainage stent 60 and the second end
68 of the sleeve 13, beyond which the sleeve 13 becomes
sufficiently thin to collapse into a closed position in the absence
of antegrade flow 17, such as bile.
[0050] FIG. 13 depicts how the illustrative embodiment is used
within the common bile duct 69 to permit the drainage of bile
across the Papilla of Vater 70 and into the duodenum 71. The
biliary stent 60 is positioned in the normal manner inside the
common bile duct 69 with the first end 62 of the stent extending
outside of the duct and Papilla of Vater 70. The first retention
means 64 abuts the opening of the sphincter to prevent ingress of
the stent 60 into the duct while the second retention means 65,
located about the second end 63, is positioned well inside the duct
to prevent the stent 60 from migrating outward. The sleeve 13 lies
completely within the duodenum where it acts as a one-way valve to
prevent intestinal contents from entering the biliary stent 60.
Unlike the embodiment of FIG. 1, the sleeve 13 is not designed to
invert back through the tubular member 13 in the presence of a
third, significantly higher pressure, a situation which is normally
not found inside the duodenum, or even clinically necessary as with
the esophageal embodiment where belching or vomiting make such a
capability desirous. Placement of the embodiments of FIGS. 11-12
can be accomplished by a system such as that depicted in FIG. 14.
The biliary stent 60 is mounted on a guiding catheter 73 which is
fed over an standard biliary exchange wire guide 74 into the bile
duct. To deploy the stent from over the guiding catheter 73, a
pusher element 72 is used with the distal end 75 of the pusher
contacting the first end 62 of stent 60 and urging it forward until
deployment occurs. The sleeve 13 is normally folded in accordion
fashion prior to deployment, whereby it resumes its elongate
configuration once the prosthesis 10 has been properly
positioned.
[0051] FIG. 15 depicts a prosthesis 10 comprising a tubular
drainage stent 60 that is configured for placement in the urinary
system, such as within the ureter between the kidney and the
bladder. The sleeve 13 is attached to the first end 62 of the
tubular drainage stent 60, which includes a first retention means
64 that comprises a pigtail configuration 79. In a ureteral stent,
the pigtail 79 would be placed within the bladder to prevent
migration of the stent. Optionally, a pigtail configuration 79 can
be used to anchor the second end of the stent (not shown),
typically within the ureteropelvic junction. The pigtail
configuration is exemplary of a large variety of well know pigtail
ureteral and urethral stents.
[0052] FIG. 16 depicts a tubular drainage stent 60 in which the
first end 68 of the sleeve 13 is affixed completely within the
lumen 12 of the stent 60, the attachment 66 comprising a well-known
means such as thermal bonding, adhesive, or a ring of material that
can affix the sleeve 13 material to the inner walls 78 of the stent
60. In the illustrative embodiment, the sleeve 13 resides
completely within the lumen 12, such that it doesn't not extend
beyond the end of the tubular drainage stent 12. This could have
particular utility in a urethral stent to prevent migration of
pathogenic organism though the stent and into the bladder, while
still allowing antegrade flow of urine 17. Having a sleeve 13
extending out of the urethra would normally be less acceptable from
a clinical and patient's point of view.
[0053] As with each of the embodiments of FIGS. 11-16, it is
important that the sleeve be made highly flexible and readily
collapsible such that normally exists it a closed state, either by
a fluid (air or bodily fluids) applying second pressure in a second
direction 18 to at least substantially close the sleeve lumen 15 to
greatly reduce retrograde migration of fluids, materials, or
pathogens, or merely by the absence of fluid applying a first
pressure in a first direction 17. In the preferred embodiments, the
sleeve 13 does not maintain its regular tubular configuration
(unless perhaps, it is hanging straight down) due to the inability
of the thin polymeric material to support such a configuration
against gravitational forces. Rather, it collapses into a closed
configuration or self-closes to form a one-way valve due to the
material adhering to itself, particularly if wet, the atmospheric
pressure or fluid pressure in the second direction 18, typically
facilitating its closure.
[0054] It is to be understood that the above described anti-reflux
esophageal, biliary, an urological prostheses 10 are merely
illustrative embodiments of this invention. The present invention
can also include other devices and methods for manufacturing and
using them may be devised by those skilled in the art without
departing from the spirit and scope of the invention. It is also to
be understood that the invention is directed to embodiments both
comprising and consisting of disclosed parts. For example, in the
esophageal embodiments, it is contemplated that only a portion of
the tubular frame need be coated with the sleeve material.
Furthermore, the sleeve material extending from the distal end of
the tubular member can be formed with different material from that
covering the tubular frame. It is also contemplated that the
material of the self-expanding stents can be formed of other
materials such as nickel titanium alloys commercially known as
nitinol, spring steel, and any other spring-like material formed to
assume the flexible self-expanding zig-zag stent configuration.
* * * * *