U.S. patent application number 10/447110 was filed with the patent office on 2003-10-23 for method and device for inserting and withdrawing a two piece stent across a constricting anatomic structure.
This patent application is currently assigned to Scimed Life Systems, Inc.. Invention is credited to Devonec, Marian A., Lehmann, John W., Paddock, Kimberly A., Rioux, Robert F..
Application Number | 20030199988 10/447110 |
Document ID | / |
Family ID | 27252715 |
Filed Date | 2003-10-23 |
United States Patent
Application |
20030199988 |
Kind Code |
A1 |
Devonec, Marian A. ; et
al. |
October 23, 2003 |
Method and device for inserting and withdrawing a two piece stent
across a constricting anatomic structure
Abstract
A stent device and methods for inserting and removing a stent to
and from an anatomical tract of a living being. The stent includes
a distal segment and a proximal segment joined by a flexible
connection structure. The stent is inserted using components
comprising a delivery assembly such that the stent proceeds through
the anatomical tract and seats the flexible connection structure of
the stent in a natural constricting structure of the anatomical
tract. The flexible quality of the connection structure permits the
natural constricting functions of the anatomical tract to occur.
The natural closure of the anatomical constricting structure stops
the flow of fluid, for example, from a target organ which indicates
that the stent is properly placed within the anatomical tract.
Inventors: |
Devonec, Marian A.;
(Miribel, FR) ; Rioux, Robert F.; (Ashland,
MA) ; Paddock, Kimberly A.; (Newton, MA) ;
Lehmann, John W.; (Wayland, MA) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
Scimed Life Systems, Inc.
Maple Grove
MN
|
Family ID: |
27252715 |
Appl. No.: |
10/447110 |
Filed: |
May 29, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10447110 |
May 29, 2003 |
|
|
|
09899112 |
Jul 6, 2001 |
|
|
|
6576008 |
|
|
|
|
10447110 |
May 29, 2003 |
|
|
|
09032978 |
Mar 2, 1998 |
|
|
|
6290666 |
|
|
|
|
10447110 |
May 29, 2003 |
|
|
|
08501140 |
Aug 15, 1995 |
|
|
|
5766209 |
|
|
|
|
08501140 |
Aug 15, 1995 |
|
|
|
PCT/FR94/00171 |
Feb 16, 1994 |
|
|
|
Current U.S.
Class: |
623/23.64 ;
623/1.16; 623/23.7 |
Current CPC
Class: |
A61F 2002/047 20130101;
A61F 2250/0039 20130101; A61F 2/82 20130101; A61F 2210/0004
20130101; A61F 2/04 20130101; A61F 2250/0067 20130101 |
Class at
Publication: |
623/23.64 ;
623/1.16; 623/23.7 |
International
Class: |
A61F 002/04 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 19, 1993 |
FR |
93 02284 |
Claims
What is claimed is:
1. A method of placing a prosthesis into an anatomical tract that
passes through an anatomical constricting structure, the prosthesis
comprising a first segment, a second segment and a connection
structure that flexibly connects the first and second segments, the
prosthesis mounted on an insertion assembly, the method comprising:
inserting the prosthesis and the insertion assembly into an opening
in the anatomical tract; advancing the prosthesis through the
anatomical tract using the insertion assembly until at least the
first segment is at least partially located on a far side of the
anatomical constricting structure from the opening in the
anatomical tract; at least partially withdrawing at least a first
portion of the insertion assembly from the anatomical tract
relative to the prosthesis; and manipulating at least one of a
second portion of the insertion assembly and a portion of the
prosthesis to obtain the connection structure extending through the
anatomical constricting structure, the first segment being located
entirely on the far side of the anatomical constricting structure,
and the second segment being located entirely on a near side of the
anatomical constricting structure relative to the opening in the
anatomical tract.
2. The method of claim 1, wherein advancing the prosthesis through
the anatomical tract using the insertion assembly comprises
locating at least one of the first and second segments relative to
at least one of an organ and a cavity associated with the
anatomical tract.
3. The method of claim 2, wherein locating at least one of the
first and second segments relative to at least one of an organ and
a cavity comprises locating the first segment relative to an
opening in a bladder.
4. The method of claim 1, wherein: the first segment comprises a
first end connected to the connection structure and a second end
opposite the first end, the second end having an opening; and
locating the first segment relative to the opening in the bladder
comprises advancing the second end of the first segment through the
opening in the bladder and into the bladder such that at least one
of liquids and gases are released into the bladder signaling entry
of the first segment into the bladder.
5. The method of claim 1, wherein: locating the first segment
entirely on the far side of the anatomical constricting structure,
and locating the second segment entirely on a near side of the
anatomical constricting structure relative to the opening in the
anatomical tract signals placement of the connecting structure
within the anatomical constricting structure by voluntary control
of the anatomical constricting structure.
6. The method of claim 3, wherein: the first segment comprises a
first end connected to the connection structure and a second end
opposite the first end, the second end having an opening; and
locating the first segment relative to the opening in the bladder
comprises advancing the second end of the first segment through the
opening in the bladder and into the bladder such that fluid held in
the bladder can flow through the opening of the second end and into
the first segment.
7. The method of claim 6, wherein: the insertion assembly
comprises: a mandrel, a pusher mountable on the mandrel, and a
removal structure attached to one of the first and second segments;
and at least partially withdrawing at least a portion of the
insertion assembly from the anatomical tract comprises removing the
mandrel and the pusher from the anatomical constricting
structure.
8. The method of claim 7, wherein locating the first segment
relative to the at least one of an organ and a cavity comprises
locating the first segment entirely on the far side of the
anatomical constricting structure.
9. The method of claim 8, wherein manipulating one of the second
portion of the insertion assembly and a portion of the prosthesis
comprises pulling on at least a portion of the removal structure
until the connection structure extends through the anatomical
constricting structure and the second segment is entirely on the
near side.
10. The method of claim 2, wherein locating at least one of the
first and second segments relative to at least one of the organ and
the cavity comprises advancing the first segment entirely through
the anatomical constricting structure and advancing the second
segment at most partially through the anatomical constricting
structure.
11. The method of claim 10, wherein: the insertion assembly
comprises: a mandrel; a pusher mountable on the mandrel; a removal
structure attached to one of the first and second segments; and at
least partially withdrawing at least a portion of the insertion
assembly from the anatomical tract comprises removing the mandrel
and the pusher from the anatomical constricting structure.
12. The method of claim 11, wherein manipulating one of the second
portion of the insertion assembly and a portion of the prosthesis
comprises pulling on at least a portion of the removal structure
until the connection structure extends through the anatomical
constricting structure and the second segment is on the near
side.
13. The method of claim 10, wherein manipulating one of the second
portion of the insertion assembly and a portion of the prosthesis
comprises pulling the one of the second portion of the insertion
assembly and a portion of the prosthesis to withdraw the second
segment to the near side such that the connection structure extends
through the anatomical constricting structure.
14. The method of claim 13, wherein pulling the one of the second
portion of the insertion-assembly and a portion of the prosthesis
comprises pulling at least a portion of a removal structure, the
pulled portion of the removal structure attached to at least the
second segment.
15. The method of claim 14, wherein the pulled portion of the
removal structure includes at least a removal thread attached to
the second segment.
16. The method of claim 13, wherein: the insertion assembly
comprises: a mandrel, a pusher mountable on the mandrel, and a
removal structure attached to one of the first and second segments;
and at least partially withdrawing at least a portion of the
insertion assembly from the anatomical tract comprises removing the
mandrel and the pusher from the anatomical constricting
structure.
17. The method of claim 16, wherein pulling the second portion of
the insertion assembly comprises pulling at least a portion of the
removal structure that is attached to the second segment.
18. The method of claim 13, wherein: the insertion assembly
comprises: a stiff member that extends through the first and second
segments and the connection structure and that contacts an end of
the first segment that is opposite an end of the first segment
connected to the connection structure, an insertion structure that
extends through the second segment and the connection structure and
into the first segment, at least one segment release structure,
each segment release structure releasably connecting the insertion
structure to one of the first and second segments, and a removal
structure attached to at least the second segment; and pulling at
least one of the second portion of the insertion assembly and the
portion of the prosthesis comprises pulling the insertion
structure.
19. The method of claim 18, wherein: the at least one segment
release structure comprises a first segment release structure that
releasably connects the insertion structure to the first segment;
and withdrawing at least a portion of the insertion assembly
comprises withdrawing the first segment release structure to
release the first segment from the insertion structure before
pulling the insertion structure.
20. The method of claim 18, wherein withdrawing at least a portion
of the insertion assembly further comprises at least partially
withdrawing the stiff member from the prosthesis before pulling the
insertion structure.
21. The method of claim 18, further comprising, after pulling the
insertion structure, withdrawing the stiff member from the
anatomical tract.
22. The method of claim 21, further comprising, after removing the
stiff member, withdrawing the insertion structure from the
anatomical tract.
23. The method of claim 18, wherein withdrawing at least a portion
of the insertion assembly further comprises withdrawing one of the
at least one segment release structure that connects the insertion
structure to the first segment before pulling the insertion
structure.
24. The method of claim 22, wherein: when the first and second
segments and the connection structure are mounted on the insertion
structure, the at least one segment release structure releasably
connects the insertion structure to the first and second segments
such that the connection structure is in a collapsed state; and
pulling the insertion structure after withdrawing the segment
release structure that connects the insertion structure to the
first segment causes the connection structure to expand from the
collapsed state and extend through the anatomical constricting
structure.
25. The method of claim 23, wherein the at least one segment
release structure further releasably connects the insertion
structure to the first and second segments such that the first and
second segments approximately abut each other.
26. The method of claim 18, wherein the stiff member contacts the
first segment at a closed end of the first segment opposite an end
of the first segment connected to the connection structure.
27. The method of claim 13, wherein: the insertion assembly
comprises: a stiff member that extends through the first and second
segments and the connection structure and that contacts the first
segment, an insertion structure that extends through the second
segment and the connection structure and into the first segment, a
first segment release structure that releasably holds the first
segment relative to the insertion structure, and a second segment
release structure that releasably holds the second segment relative
to the insertion structure; at least partially withdrawing at least
a portion of the insertion assembly from the anatomical tract
relative to the prosthesis comprises removing the first segment
release structure from the insertion assembly to release the first
segment from the insertion structure; and pulling at least one of
the second portion of the insertion assembly and the portion of the
prosthesis comprises partially withdrawing the insertion structure
from the anatomical tract.
28. The method of claim 26, wherein at least partially withdrawing
at least a portion of the insertion assembly from the anatomical
tract relative to the prosthesis further comprises at least
partially withdrawing the stiff member from the prosthesis before
partially withdrawing the insertion structure from the anatomical
tract.
29. The method of claim 26, further comprising, after partially
withdrawing the insertion structure from the anatomical tract:
removing the second segment release structure from the insertion
assembly to release the second segment from the insertion
structure; and withdrawing the insertion structure from the
anatomical tract.
30. The method of claim 28, further comprising withdrawing the
stiff member from the anatomical tract.
31. The method of claim 29, wherein: when the first and second
segments and the connection structure are mounted on the insertion
structure, the at least one segment release structure releasably
connects the insertion structure to the first and second segments
such that the connection structure is in a collapsed state; and
pulling the insertion structure after withdrawing the segment
release structure that connects the insertion structure to the
first segment causes the connection structure to expand from the
collapsed state and extend through the anatomical constricting
structure.
32. The method of claim 30, wherein the at least one segment
release structure releasably further connects the insertion
structure to the first and second segments such that the first and
second segments approximately abut each other.
33. The method of claim 2, wherein: locating at least one of the
first and second segments relative to at least one of the organ and
the cavity comprises advancing the first segment at most partially
through the anatomical constricting structure; and manipulating one
of the second portion of the insertion assembly and a portion of
the prosthesis comprises advancing the second portion of the
insertion assembly further into the anatomical tract to advance the
first segment entirely to the far side of the anatomical
constricting structure such that the connection structure extends
through the anatomical constricting structure.
34. The method of claim 33, wherein: the insertion assembly
comprises: a stiff member that extends through the first and second
segments and the connection structure and that contacts the first
segment, a first portion of the insertion assembly that extends
through the second segment and the connection structure and into
the first segment, a first segment release structure that
releasably holds the first segment relative to the insertion
assembly, and a second segment release structure that releasably
holds the second segment relative to the insertion assembly; and at
least partially withdrawing at least a first portion of the
insertion assembly from the anatomical tract relative to the
prosthesis comprises removing the first segment release structure
from the insertion assembly to release the first segment from the
insertion structure; and advancing the second portion of the
insertion assembly comprises advancing the stiff member to advance
the first segment entirely to the far side of the anatomical
constricting structure.
35. The method of claim 34, wherein: when the first and second
segments and the connection structure are mounted on the insertion
structure, the at least one segment release structure releasably
connects the insertion structure to the first and second segments
such that the connection structure is in a collapsed state; and
advancing the insertion structure after withdrawing the segment
release structure that connects the insertion structure to the
first segment causes the connection structure to expand from the
collapsed state and extend through the anatomical constricting
structure.
36. The method of claim 34, wherein the at least one segment
release structure further releasably connects the insertion
assembly to the first and second segments such that the first and
second segments approximately abut each other.
37. The method of claim 33, wherein advancing the second portion of
the insertion assembly comprises advancing the second portion to
place the first segment in a location on the far side of the
anatomical constricting structure that is relative to at least one
of an organ and a cavity associated with the anatomical tract.
38. The method of claim 37, wherein placing the first segment in a
location relative to at least one of an organ and a cavity
comprises placing the first segment relative to an opening in a
bladder.
39. The method of claim 38, wherein: the first segment comprises a
first end connected to the connection structure and a second end
opposite the first end, the second end having an opening; and
placing the first segment relative to the opening in the bladder
comprises advancing the second end of the first segment through the
opening and into the bladder such that fluid held in the bladder
can flow into the first segment.
40. The method of claim 33, wherein: the insertion assembly
comprises: a stiff member that extends through the first and second
segments and the connection structure and that contacts the first
segment, an insertion structure that extends through the second
segment and the connection structure and into the first segment, a
first segment release structure that releasably holds the first
segment relative to the insertion structure, and a second segment
release structure that releasably holds the second segment relative
to the insertion structure; at least partially withdrawing at least
a first portion of the insertion assembly from the anatomical tract
relative to the prosthesis comprises removing the second segment
release structure from the insertion assembly to release the second
segment from the insertion structure; advancing the second portion
of the insertion assembly comprises advancing the insertion
structure to advance the first segment entirely to the far side of
the anatomical constricting structure.
41. The method of claim 40, wherein: when the first and second
segments and the connection structure are mounted on the insertion
structure, the at least one segment release structure releasably
connects the insertion structure to the first and second segments
such that the connection structure is in a collapsed state; and
advancing the insertion structure after withdrawing the segment
release structure that connects the insertion structure to the
second segment causes the connection structure to expand from the
collapsed state and extend through the anatomical constricting
structure.
42. The method of claim 41, wherein the at least one segment
release structure further releasably connects the insertion
structure to the first and second segments such that the first and
second segments approximately abut each other.
43. The method of claim 40, further comprising: removing the first
segment release structure from the insertion structure; and
removing the insertion structure from the anatomical tract.
44. The method of claim 40, wherein advancing the second portion of
the insertion assembly comprises advancing the second portion to
place the first segment in a location on the far side of the
anatomical constricting structure that is relative to at least one
of an organ and a cavity associated with the anatomical tract.
45. The method of claim 44, wherein placing the first segment in a
location relative to at least one of an organ and a cavity
comprises placing the first segment relative to an opening in a
bladder.
46. The method of claim 45, wherein: the first segment comprises a
first end connected to the connection structure and a second end
opposite the first end, the second end having an opening; and
placing the first segment relative to the opening in the bladder
comprises advancing the second end of the first segment through the
opening and into the bladder such that fluid held in the bladder
can flow into the first segment.
Description
[0001] This is a Continuation in Part (CIP) application of a
co-pending U.S. patent application Ser. No. 09/032,978, filed Mar.
2, 1998, which in turn is a divisional application of U.S. patent
application Ser. No. 08/501,140, filed Aug. 15, 1995, now U.S. Pat.
No. 5,766,209, which in turn is a National Stage application of
PCT/FR/94/00171, filed Feb. 16, 1994, each incorporated herein by
reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] The invention relates to methods and devices usable to place
a stent in an anatomical constricting structure, such as, for
example, a sphincter, using an easily-inserted and
easily-withdrawn, self-stabilizing stent.
[0004] 2. Description of Related Art
[0005] Prostheses usable to provide an artificial passage in
anatomical tracts, such as, for example, the urinary, respiratory,
digestive, gynecological or vascular tracts, in a living being are
known. For example, an endo-urethral prosthesis for a human is
known to have a tubular element whose walls are made from a
relatively smooth and soft bio-compatible material, for example a
silicone rubber, at least in its outer part. Such a tubular element
is sufficiently flexible to conform to the anatomical profile and
movements of, for example, a human urethra, while providing
sufficient rigidity that the tubular element will not collapse
under the influence of the anatomical profile or movements of the
urethral tract.
[0006] As disclosed in FR-A-2 667 783, a tubular element, as
described above, is placed in the urethra without passing through
the striated muscles that form the sphincter in the urethral tract.
The tubular element is supported primarily by the elasticity of the
tubular element and the compressive force of the urethral wall. If
the tubular element's diameter is large enough, the compressive
forces of the elastic urethral wall may adequately secure the
tubular element in the urethral tract. However, if the tubular
element is too large, damage to the urethral wall may occur and
withdrawal of the tubular element may be painful to the
patient.
[0007] Alternatively, a smaller-diameter tubular element may be
used, with notches formed in the outer wall of the tubular element,
to provide a degree of secondary support for the tubular element
within the urethral tract. However, such notches do not prevent the
tubular element from moving downward, or descending, in the urethra
during micturition, for instance. The changing position of the
tubular element renders the tubular element problematic and risks
discomfort to the patient. Further, providing the tubular element
with scales, or fastening catches, to counter the tendency of the
prosthesis to descend during micturition does not prevent the
prosthesis from moving upward, or ascending, in the urethral tract
as a result of routine bodily motions or functions. Such scales, or
fastening elements also generate increased discomfort to the
patient during withdrawal of the tubular element.
[0008] Other known catheter-delivered prostheses that provide an
artificial passage in an anatomical tract of a living being include
very flexible, spirally coiled metal elements. However, the
flexible quality of the spirally coiled elements prove very
unstable during insertion as the more rigid delivery catheter ends
where the flexible element begins. As a result, bunching or other
inappropriate placement of the flexible member often occurs,
requiring withdrawal and re-insertion of the prosthesis, and/or
causing discomfort to the patient due to the ill-configured
element.
[0009] Still other known catheter-delivered prostheses that provide
an artificial passage in an anatomical tract of a living being
require ultra-sound, radioscopy, or other indirect visualizing
devices to determine when and whether the prosthesis is in position
to provide the artificial passage desired without inhibiting the
natural constricting function of the anatomical constricting
structure against the anatomical tract.
[0010] Thus, known tubular element prostheses are not
self-stabilizing across a anatomical constricting structure. Nor
are known prostheses provided with a method for inserting the
prosthesis into and withdrawing the prosthesis from an anatomical
tract that minimizes the pain and discomfort typically associated
with stenting. Similarly, known prostheses do not have structures
that provide a direct method for determining whether the
catheter-delivered prosthesis is in the appropriate position in the
anatomical tract such that the artificial passage is created
without inhibiting the natural constricting function of the
anatomical constricting structure against the anatomical tract.
SUMMARY OF THE INVENTION
[0011] This invention provides stent assemblies and methods usable
to insert and withdraw a self-stabilizing prosthetic stent to or
from an anatomical tract of a living being.
[0012] This invention separately provides stent assemblies and
insertion/withdrawal methods that allow the self-stabilizing
prosthetic stent to create an artificial passage within the tract
in a manner that minimizes pain and discomfort to the living
being.
[0013] This invention separately provides stent assemblies and
insertion/withdrawal methods that enable a user to determine
directly when the self-stabilizing prosthetic stent is properly
placed.
[0014] In various exemplary embodiments, the self-stabilizing
prosthetic stent comprises distal and proximal segments connected
to one another via a flexible connection structure to form an
approximately continuous outer surface of the self-stabilizing
prosthetic stent. The approximately continuous outer surface of the
self-stabilizing prosthetic stent permits non-traumatic insertion
or withdrawal of the self-stabilizing prosthetic stent to or from
an anatomical tract of a living being without needing anesthesia.
In various exemplary embodiments, the distal and proximal segments
are generally tubular elements that can be formed of a relatively
smooth, soft bio-compatible material. This permits the distal and
proximal segments to conform to the profile and movements of the
anatomical tract that the self-stabilizing prosthetic stent is
placed within. In various exemplary embodiments, each of the distal
and proximal segments have a substantially constant
cross-section.
[0015] In various exemplary embodiments, the self-stabilizing
prosthetic stent's flexible connection structure includes a
tubular, flexible sleeve having opposed first and second ends. The
first end of the flexible connection structure connects to the
self-stabilizing prosthetic stent's distal segment. The second end
of the flexible connection structure connects to the
self-stabilizing prosthetic stent's proximal segment. The flexible
connection structure, when properly seated, lies adjacent to the
anatomical constricting structure of the anatomical tract. The
flexible quality of the flexible connection structure permits the
natural function of the anatomical constricting structure to
continue, thus creating the desired artificial passage in the
anatomical tract.
[0016] In various exemplary embodiments, the stent assembly usable
to insert and withdraw this self-stabilizing prosthetic stent
structure includes one or more additional structural features
permitting the insertion and withdrawal methods of the invention to
be achieved.
[0017] In various exemplary embodiments, inserting the
self-stabilizing prosthetic stent uses a delivery catheter, on
which at least a portion of the self-stabilizing prosthetic stent
is placed, to generally guide the self-stabilizing prosthetic stent
into an anatomical tract. In various exemplary embodiments, the
delivery catheter includes a semi-rigid, hollow mandrel usable to
urge the distal stent segment into the anatomical tract, and a
pusher to push the proximal stent segment, in a trailing fashion
relative to the distal stent segment, to the desired position
within the anatomical tract.
[0018] In these exemplary embodiments, the pusher is first placed
upon the mandrel. The self-stabilizing prosthetic stent is then
mounted upon the mandrel. The self-stabilizing prosthetic stent is
then placed into the anatomical tract such that a generally closed
end of the distal stent segment enters the anatomical tract first.
The flexible connection structure joins the distal stent segment to
the proximal stent segment and also is mounted upon the mandrel.
Mounting the self-stabilizing prosthetic stent in this manner upon
the mandrel precludes the flexible connection structure from
deforming until after the mandrel is withdrawn. The hollow mandrel
is provided with an opening on one end that aligns with a similar
opening in the closed, rounded end of the distal stent segment.
Aligning the openings in the mandrel and the distal stent segment
permits fluid to flow into and through the self-stabilizing
prosthetic stent and mandrel.
[0019] Together, the mandrel and the pusher advance and maintain
the self-stabilizing prosthetic stent, particularly the distal
stent segment, into a desired position relative to a target organ
and/or body cavity as the stent assembly delivers the
self-stabilizing prosthetic stent into and through the anatomical
tract, and ultimately to the target organ and/or body cavity. An
end of the proximal segment of the self-stabilizing stent, furthest
from the flexible connection structure, is provided with an eyelet
from which one or more withdrawal threads, pull-wires, or
equivalent structures extend outwardly through the anatomical tract
to be accessible outside of the living being.
[0020] Combined with the delivery catheter, the self-stabilizing
prosthetic stent is inserted to the desired anatomical tract until
the proximal and distal segments of the self-stabilizing prosthetic
stent extend at least partly across an anatomical constricting
structure and until the closed end of the distal segment reaches a
desired position relative to the target body cavity or organ, such
as, for example, extending into a bladder. The openings in the
distal segment's closed end and in the mandrel are aligned such
that a flow of fluid through the self-stabilizing prosthetic stent
and in the mandrel occurs, signaling that the self-stabilizing
prosthetic stent has reached a desired location relative to the
target organ and/or body cavity. Thus, general placement of the
self-stabilizing prosthetic stent is achieved without needing
ultra-sound, radioscopy, or other visualizing methods or
devices.
[0021] The mandrel is then withdrawn, while the pusher is
maintained in place. Once the mandrel is withdrawn, the flexible
connection structure is available and will flex in response to the
natural constricting or relaxing functions of the anatomical
constricting structure. Then, the pusher is withdrawn. The one or
more withdrawal threads, pull-wires, or other equivalent structures
that extend from the self-stabilizing prosthetic stent is
accessible outside of the living being. At least one of the
withdrawal threads, pull-wires, or other equivalent structures is
then gently tugged until the flexible connection structure of the
self-stabilizing prosthetic stent is fully extended and seated
within the anatomical constricting structure.
[0022] Thus, specific placement of the self-stabilizing prosthetic
stent and the flexible connection structure is easily identified as
increased resistance to tugging on the at least one withdrawal
thread, pull-wire, or other equivalent structure is sensed when the
flexible connection structure is seated in the anatomical
constricting structure. Further, the natural function of the
anatomical constricting structure causes the flexible connection
structure to close, thus stopping the flow of fluid through the
self-stabilizing prosthetic stent and directly indicating that the
self-stabilizing prosthetic stent is appropriately positioned
within the anatomical tract. Accordingly, an artificial passage,
complying with the natural functions and configurements of the
anatomical tract, is achieved.
[0023] Withdrawing the self-stabilizing prosthetic stent is
accomplished by providing a more constant pulling on at least one
of the withdrawal threads, pull-wires, or other equivalent
structures of the self-stabilizing prosthetic stent so that the
constricting forces of the anatomical constricting structure are
overcome. Having overcome the anatomical constricting forces, the
self-stabilizing prosthetic stent can be freely removed from the
anatomical tract with reduced pain or discomfort.
[0024] In other exemplary embodiments of the stent assembly and
insertion and withdrawal methods of this invention, the
self-stabilizing prosthetic stent is mounted upon a delivery
catheter. In various exemplary embodiments, the proximal and distal
stent segments abut one another during insertion due to the
flexible connection structure joining the distal and proximal stent
segments being in a collapsed state. An end of a distal stent
segment release structure protrudes through a wall of the delivery
catheter to hold the distal stent segment in place during
insertion. The distal stent segment has a generally closed end that
is placed relative to a target organ and/or cavity, and an opening
through which fluid flows when the self-stabilizing prosthetic
stent reaches the target organ or body cavity. A stiff member is
used during insertion of the self-stabilizing prosthetic stent to
position the distal segment of the self-stabilizing prosthetic
stent, or to more securely maintain the position of the distal
segment in the anatomical tract and relative to the target organ
and/or body cavity.
[0025] An end of a proximal stent segment release structure
protrudes through the wall of the delivery catheter to hold the
proximal stent segment in place during insertion, such that the
proximal and distal stent segments are maintained in an abutting
relationship during insertion until the respective release
structures are withdrawn. Fluid flow through the opening in the
generally closed end of the distal stent segment signals that the
self-stabilizing prosthetic stent has reached the target organ
and/or body cavity. The distal stent segment release structure, the
proximal stent segment release structure, and the delivery catheter
are removed in any one of a number of different orders, depending
on which exemplary embodiment is being used, to seat the flexible
connection structure of the self-stabilizing prosthetic stent in
the anatomical constricting structure.
[0026] Proper positioning of the flexible connection structure is
easily detected as the fluid flow from the target organ through the
self-stabilizing prosthetic stent and the delivery catheter ceases
as the flexible connection structure extends such that the proximal
and distal stent segments no longer abut one another. By seating
the flexible connection structure of the stent in the region of the
anatomical constricting structure, the natural functioning of the
anatomical constricting structure is permitted and the desired
artificial passage in the anatomical tract is-achieved.
[0027] In still other various exemplary embodiments, the proximal
and distal stent segments, in a non-abutting relationship to one
another, are mounted upon a hollow delivery catheter such that the
flexible connecting structure joining the proximal and distal stent
segments is substantially extended during insertion of the stent to
the anatomical tract. Fluid flow through the hollow delivery
catheter and stent again indicates the stent has reached the target
organ and/or body cavity. Withdrawal of the delivery catheter
permits the natural constricting and relaxing functions of the
anatomical constricting structure to act upon the flexible
connecting structure of the stent. Again, gentle tugging on at
least one of the one or more withdrawal threads, pull-wires, or
other equivalent structures enable the flexible connecting
structure to be seated more compliantly with the anatomical
constricting structure desired.
[0028] Withdrawing the self-stabilizing prosthetic stent is
accomplished by providing a more constant pulling on at least one
of the one or more withdrawal threads, pull-wires, or other
equivalent structures so that the constricting forces of the
anatomical constricting structure are overcome. Having overcome the
anatomical constricting forces, the self-stabilizing prosthetic
stent is freely removable from the anatomical tract.
[0029] It should be appreciated that in all of the exemplary
embodiments the self-stabilizing prosthetic stent may also be used
to instill fluids, or other irrigating solutions, to the target
organ and/or body cavity. Further, the stent assemblies and stent
insertion and withdrawal methods according to this invention may be
used to insert or control other instruments, such as, for example,
an endoscope, to view or otherwise involve a target body cavity or
organ by deploying an instrument through the stent assembly and
self-stabilizing prosthetic stent using the methods described.
[0030] It should be further appreciated that, in all of the
exemplary embodiments, the flexible connecting structure may be
tubular, threaded, slotted, or any equivalent structural
combination permitting the seating of the flexible connecting
structure for compliance with the naturally occurring actions
within the anatomical constricting structure the flexible
connecting structure is subject to, such as, for example, the
structures disclosed in the incorporated U.S. Pat. No.
5,766,209.
[0031] It should be still further appreciated that the terms
"distal" and "proximal" as used herein are exemplary only with
reference to the insertion entry point of the self-stabilizing
prosthetic stent after the self-stabilizing prosthetic stent is
inserted into the anatomical tract.
[0032] The simplicity of the insertion and withdrawal methods and
structures according to this invention permit non-specialists to
place successfully a stent in a living being relatively painlessly,
and without needing anesthesia. Further, appropriately positioning
the self-stabilizing prosthetic stent can be achieved without
expensive visualizing equipment, because the appropriate placement
of the self-stabilizing prosthetic stent across the anatomical
constricting structure is determined directly based on the flow of
fluid or gases through the self-stabilizing prosthetic stent, by
feeling the resistance to further withdrawal of the stent, and/or
by the living being controlling, for example, micturition by
voluntarily controlling, for example, the sphincter across which
the flexible connecting structure of the self-stabilizing stent is
placed.
[0033] These and other features and advantages of this invention
are described in, or are apparent from, the detailed description of
various exemplary embodiments of the systems and methods according
to this invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Various exemplary embodiments of this invention will be
described in detail with reference to the following figures,
wherein like numerals represent like elements, and wherein:
[0035] FIG. 1 illustrates a first exemplary embodiment of the
general configuration of the self-stabilizing prosthetic stent
according to this invention;
[0036] FIG. 2 illustrates a second exemplary embodiment of the
general configuration of the self-stabilizing prosthetic stent
according to this invention;
[0037] FIG. 3 illustrates an exemplary embodiment of a perforated
flexible connection structure according to this invention;
[0038] FIG. 4 illustrates an exemplary embodiment of a slotted
flexible connection structure according to this invention;
[0039] FIG. 5 illustrates various exemplary embodiments of
angularly adapted stent segments according to this invention;
[0040] FIG. 6 illustrates a first exemplary embodiment of a stent
assembly according to this invention;
[0041] FIG. 7 illustrates the exemplary embodiment shown in FIG. 6
in an assembled state;
[0042] FIG. 8 illustrates an example of the self-stabilizing
prosthetic stent located across a sphincter of a male urethra after
insertion of the self-stabilizing prosthetic stent according to
this invention;
[0043] FIGS. 9-12 illustrate a first exemplary embodiment of a
method for positioning of the self-stabilizing prosthetic stent
within a human male's penis for insertion of the self-stabilizing
prosthetic stent according to this invention using the stent
assembly of FIGS. 6 and 7;
[0044] FIGS. 13-15 illustrate a second embodiment of a method for
inserting the self-stabilizing prosthetic stent according to this
invention using a second exemplary embodiment of the stent
assembly;
[0045] FIG. 16 illustrates a third exemplary embodiment of the
stent assembly according to this invention;
[0046] FIGS. 17-20 illustrate a third exemplary embodiment of a
method for inserting a self-stabilizing prosthetic stent according
to this invention using the third exemplary embodiment of the stent
assembly of FIG. 16;
[0047] FIGS. 21-25 illustrate a fourth exemplary embodiment of a
method for inserting a self-stabilizing prosthetic stent according
to this invention using the third exemplary embodiment of the stent
assembly of FIG. 16;
[0048] FIG. 26 illustrates a fourth exemplary embodiment of the
stent assembly according to this invention; and
[0049] FIGS. 27-31 illustrate a fifth exemplary embodiment of a
method for inserting a self-stabilizing prosthetic stent according
to this invention using the fourth exemplary embodiment of the
stent assembly of FIG. 26.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0050] FIG. 1 shows a first exemplary embodiment of a
self-stabilizing prosthetic stent 1. As shown in FIG. 1, the stent
1 includes a distal segment 2, a proximal segment 3 and a flexible
connection structure 4. In various exemplary embodiments, the
distal segment 2 and proximal segment 3 are tubular elements. In
some exemplary embodiments, one or both of the distal segment 2
and/or the proximal segment 3 have substantially constant
cross-sections. In various exemplary embodiments, the distal and
proximal segments 2 and 3 are made of bio-compatible materials,
such as silicone rubber, to provide a sufficiently flexible stent
1. However, the distal and proximal segments 2 and 3 can be made of
any suitable material that is conformable to the profile and
movements of the anatomical tract that the stent 1 is placed
within, while maintaining a rigidity sufficient to create an
artificial passage within that anatomical tract. In various
exemplary embodiments, at least an outer surface of the stent 1 is
made of a smooth material, such as, for example, silicone rubber.
When smooth, the outer surface of the stent 1 provides for a more
non-traumatic insertion or withdrawal of the stent 1 from the
anatomical tract.
[0051] In various exemplary embodiments, the flexible connection
structure 4, as shown in FIG. 1, is a soft, flexible sleeve. In
general, the connection structure 4 will have a flexibility that is
greater than the flexibility of the distal or proximal segments 2
and 3. Additionally, in various exemplary embodiments, either or
both of the walls comprising the connection structure 4 can be
thinner than the walls comprising the distal or proximal segments 2
and 3. This contributes to the relatively greater flexibility of
the connection structure 4. The connection structure 4 has two
opposed ends 4a and 4b. The first end 4a of the connection
structure 4 is connected to the interior surface of the distal
segment 2. The second end 4b of the connection structure 4 is
similarly connected to the interior surface of the proximal segment
3. This provides continuity between the distal and proximal
segments 1 and 2. By connecting the distal and proximal segments 2
and 3 using the flexible connection structure 4, the stent 1 has an
approximately continuous outer surface.
[0052] FIG. 2 shows a second exemplary embodiment of the stent 1.
As shown in FIG. 2, the second exemplary embodiment of the stent 1
includes a flexible connection structure 14 having two opposed ends
14a and 14b connected to the distal and proximal segments 2 and 3,
respectively. The flexible connection structure 14 of the second
exemplary embodiment of the stent 1 can be generally similar to the
structures and/or materials of the flexible connection structure 4
of the first exemplary embodiment of the stent 1. However, as shown
in FIG. 2, the flexible connection structure 14 is connected to the
outer surface of the distal and proximal segments 2 and 3 using the
first end 14b and the second end 14b. The flexible connection
structures 4 and 14 may be attached to the distal and proximal
segments 2 and 3 in any suitable manner, such as, for example, by
adhesive bonding. Thus, it should be appreciated that any known or
later developed suitable attachment structures and methods could be
used.
[0053] The flexible connection structures 4 and 14 thus provide a
predetermined region that complies with and permits the
continuation of the natural functioning of an anatomical
constricting structure, such as, for example, a sphincter, when the
stent 1 is placed within the anatomical tract to create an
artificial passage. The flexible connection structures 4 and 14
each further provides a self-stabilizing quality to the stent 1
when the stent 1 is inserted into the anatomical tract. That is,
when the flexible connection structure 4 or 14 is positioned in
alignment with the anatomical constricting structure, such as the
sphincter, of the anatomical tract, the location of the stent 1 in
the anatomical tract is stable. That is, the stent 1 does not
readily move within the anatomical tract.
[0054] The distal segment 2, at the end opposite the connection
structure 4 or 14, includes a generally closed end 5. The closed,
rounded end 5 serves as an entry end of the distal stent segment 2
of the stent 1. The generally closed end 5 promotes the
non-traumatic insertion of the stent 1 into the anatomical tract.
The generally closed end 5 of the stent 1 further includes at least
one orifice or opening 6 that permits fluid to flow into and
through the stent 1. As shown in FIGS. 1 and 2, in various
exemplary embodiments, the at least one orifice or opening 6 is a
lateral orifice or opening 6 that opens in the side wall of the
distal segment 2 of the stent 1. In this case, the generally closed
end 5 is a completely closed end 5. In general, in various
exemplary embodiments, when the generally closed end 5 is
completely closed, the generally closed end 5 can be rounded.
[0055] In various other exemplary embodiments of the distal segment
2, the at least one orifice or opening 6 can be formed in the end
wall of the generally closed end 5. That is, the distal segment 2
forms a tube have two open ends. In this case, the generally closed
end 5 is not completely closed. However, in various exemplary
embodiments, the generally closed end 5 can be narrowed relative to
the diameter of the rest of the distal segment 2. This will allow a
mandrill, such as that shown in FIG. 6, or a stiff member, such as
that shown in FIG. 13, to be placed into the distal segment 2 of
the stent 1 to aid in advancing the stent 1 into the anatomical
traps. In still other exemplary embodiments, the generally closed
end 5 can be completely open, such that the closed end 5 is not
closed at all. In this case, one or more constricting structures
can be placed within the distal segment 2 to provide surfaces
against which the mandrill shown in FIG. 6 or the stiff member
shown in FIG. 13 can bear against to advance the distal segment 2
into the anatomical tract.
[0056] The proximal segment 3 of the stent 1 includes an eyelet
hole 7. The eyelet hole 7 is formed in an end 3a of the proximal
segment 3 furthest from the connection structure 4 or 14. The one
or more withdrawal threads, pull-wires, or other equivalent
structures 8 extend from the eyelet hole 7. The one or more
withdrawal threads, pull-wires, or other equivalent structures 8
are accessible to a user outside the anatomical tract, even after
the stent 1 has been inserted into the desired anatomical tract.
The one or more withdrawal threads, pull-wire, or other equivalent
structures 8 enable a user to pull on at least one of the
withdrawal threads, pull-wires, or other equivalent structures 8 to
position the stent 1 more precisely within the anatomical
constricting structure region, and/or to remove the stent 1 from
the anatomical tract in a relatively smooth and painless
manner.
[0057] FIGS. 3 and 4 show third and fourth exemplary embodiments of
the flexible connection structure 14' and 14". While the first and
second exemplary embodiments of the flexible connection structures
4 or 14 described above are tubular elements having generally solid
sides, as shown in FIGS. 1 and 2, it should be appreciated that the
flexible connection structure of the stent 1 may instead have
perforated sides, as in the flexible connection structure 14' shown
in FIG. 3. Alternatively, the flexible connection structure may
have slotted sides, as in the flexible connection structure 14"
shown in FIG. 4. The perforations or slots in the flexible
connection structures 14' and 14", respectively, render it easier
to bend or otherwise deform the flexible connection structures 14 '
and 14", thus contributing to voluntary control by the patient of
the functioning of the anatomical constricting structure.
[0058] While FIGS. 1 and 2 show the distal and proximal segments 2
and 3 as essentially linear, as in FIGS. 1 and 2, it should be
appreciated that one or both of the distal and/or proximal segments
2 and 3 may be angularly adapted to conform to the profile of the
portion of the anatomical tract that the distal and proximal
segments 2 or 3 will be inserted into. FIG. 5 shows one exemplary
embodiment of a stent 1 having an angularly adapted distal segment
2', and an angularly adapted proximal segment 3'. The angularly
adapted distal or proximal segments 2' and 3' may be identical to
or different from the natural angulation of the anatomical tract
the stent 1 is to be placed into. The angularly adapted distal
and/or proximal segments 2' and/or 3' may ease insertion or
withdrawal of the stent 1, and/or may help secure the stent 1 in a
desired position once placed within the anatomical tract.
[0059] FIGS. 6 and 7 show a first exemplary embodiment of a stent
assembly 100 that includes the various components outlined above,
assembled for inserting the stent 1 into, or withdrawing the stent
1 from a living being according to the methods of this invention.
The stent assembly 100 includes a hollow mandrel 9 having an
external cross-section that is adapted to receive the stent 1,
including one of the flexible connection structures 4 or 14. In
various exemplary embodiments, the mandrel 9 is formed of a
semi-rigid material. The mandrel 9 has an end-stop 10 and a
generally closed end 11. The generally closed end 5 of the distal
segment 2 of the stent 1 abuts the generally closed end 11 of the
mandrel 9 when the stent 1 is mounted on the mandrel 9 for
insertion to an anatomical tract. An eyelet 12 is formed in the
generally closed end 11 of the mandrel 9. The eyelet 12 can be
aligned to match the orifice or opening 6 of the distal segment 2
when the stent 1 is engaged with the mandrel 9. Thus, the generally
closed end 11 can have any of the structures described above for
the generally closed end 5. By aligning the eyelet 12 and orifice
or opening 6, fluid can flow from a body cavity or organ, such as,
for example, a bladder, once the stent 1 has been inserted through
the anatomical tract far enough to penetrate, for example, the
bladder.
[0060] A hollow pusher 13 has an internal cross-section that allows
the pusher 13 to be-placed or mounted on the mandrel 9. The pusher
13 spaces the proximal segment 3 of the stent 1 from the end-stop
10 of the mandrel 9 when the stent 1 is mounted on the mandrel 9
for insertion into the anatomical tract. In various exemplary
embodiments, the hollow pusher 13 is formed of a rigid
material.
[0061] The stent 1, including its proximal and distal segments 2
and 3 and one of the flexible connection structures 4 or 14, along
with the mandrel 9 and the pusher 13, forms the stent assembly 100
for inserting the stent 1 into an anatomical tract. FIG. 7 shows
the various elements of the stent assembly 100 assembled into a
single assembly for inserting the stent 1 into an anatomical tract.
As shown in FIG. 7, the end 3a of the proximal stent segment 3
abuts the pusher 13. The pusher 13 is mounted on the mandrel 9 and
spaces the proximal segment 3 of the stent 1 a distance L from the
end-stop 10 of the mandrel 9. At the same time the generally closed
end 5 of the distal stent segment 2 of the stent 1, when mounted on
the mandrel 9, abuts the generally closed end 11 of the mandrel 9.
The stent 1 is aligned so that the orifice or opening 6 of the
distal segment 2 is adjacent to the eyelet 12 of the mandrel 9. The
one of the flexible connection structures 4 or 14 can be relaxed or
can be fully extended as that flexible connection structure 4 or 14
joins the distal and proximal segments 2 and 3. However, the
position of that flexible connection structure 4 or 14 on the
mandrel 9 precludes that flexible connection structure 4 or 14 from
bending or complying with the natural constricting function of the
anatomical constricting structure, such as, for example, a
sphincter, until the mandrel 9 is withdrawn at least from within
that flexible connecting structure 4 or 14. The anatomical tract
into which the stent 1 will be placed may be lubricated to ease the
insertion or subsequent withdrawal process.
[0062] By way of example only, as shown for example in FIGS. 8 to
12, once assembled, the stent assembly 100 can be inserted to the
urethral tract 19 of a human male through the urethral meatus 16 of
the penis 17 until the generally closed end 5 of the distal segment
2 and the generally closed end 11 of the mandrel 9 enters into the
bladder 15. Insertion of the stent 1 and mandrel 9 into the
urethral tract 19 is eased by positioning the penis 17 in a
direction compliant with the linearly projecting mandrel 9, as
shown, for example, in FIG. 9. Because the orifice or opening 6 of
the distal segment 2 and the eyelet 12 of the mandrel are aligned,
urine flows through the orifice or opening 6 and eyelet 12 and into
the mandrel 9 once the stent 1 is placed into the bladder 15. The
fluid flow through the mandrel 9 indicates directly, without
radioscopy or other indirect visualizing means, that the stent 1
has reached its target organ, which is, in this instance, the
bladder 15.
[0063] Thus far in this exemplary insertion process, the stent 1
maintains its approximately continuous outer surface such that the
mandrel-mounted stent 1, and the flexible connection structure 4 or
14 in particular, bridges the anatomical constricting structure,
such as, for example, the sphincter 18, prohibiting the sphincter
18 from closing. Thereafter, the mandrel 9 is withdrawn, although
the pusher 13 is maintained in place abutting the proximal segment
3. As a result, the stent 1 does not drift or move from its
position bridging the sphincter 18 and penetrating into the bladder
15.
[0064] Next, the pusher 13 is removed. If the flexible connection
structure 4 or 14 has been properly seated into the desired
location within the sphincter 18, a gentle tug on at least one of
the withdrawal threads, pull-wires, or other equivalent structures
8 may be used to move the flexible connection structure 4 or 14
until that flexible connecting structure 4 or 14 is appropriately
seated relative to the sphincter 18 region.
[0065] The desired position of the stent 1 is thus easily
determined by the user inserting the stent 1, since the sphincter
18 closes on the flexible connection structure 4 or 14 providing a
resistance to further tugging on at least one of the withdrawal
threads, pull-wires, or other equivalent structures 8. Further,
once the sphincter 18 closes, the flow of fluid from the bladder 15
stops. Thus, the appropriate positioning of the stent is easily
achieved, without expensive visualization tools or devices.
[0066] Withdrawing the stent 1 from the anatomical tract 19
according to the first exemplary embodiment of the method for
inserting and withdrawing the stent 1 is accomplished by pulling
steadily on at least one of the withdrawal threads, pull-wires, or
other equivalent structures 8 with a force sufficient to overcome
the resistance of the anatomically constricting structure, such as,
for example, the muscles of the sphincter 18. This force releases
the flexible connection structure 4 or 14 from the region of the
anatomical constricting structure, such as, for example, the region
adjacent to the sphincter 18. Once released from the region of the
anatomical constricting structure, such as the region adjacent to
the sphincter 18, the stent 1 descends through the anatomical tract
19 until the stent 1 is completely withdrawn from the anatomical
tract 19.
[0067] FIGS. 13-15 show a second exemplary embodiment of a stent
assembly 200 and a third exemplary embodiment of the
self-stabilizing prosthetic stent 1 according to this invention. As
shown in FIGS. 13-15, this third exemplary embodiment of the
self-stabilizing prosthetic stent 1 is usable with a second
exemplary embodiment of a stent insertion and withdrawal method
according to this invention.
[0068] In the third exemplary embodiment of the self-stabilizing
prosthetic stent 1, as shown in FIGS. 13-15, the self-stabilizing
prosthetic stent 1 includes the distal stent segment 2 having an
orifice or opening 6 formed in the generally closed end 5 that
permits fluid flow through the self-stabilizing prosthetic stent 1
when the generally closed end 5 of the distal stent segment 2
reaches the target organ or body cavity. The proximal stent segment
3 is provided with an eyelet 7 from which one or more withdrawal
threads, pull-wires, or other equivalent structures 8 extend. A
flexible connecting structure, such as, for example, a thin wire
flexible connecting structure 14", joins the distal and proximal
stent segments 2 and 3.
[0069] In addition, the stent assembly 200 includes a delivery
catheter 20 having a first hollow tubular segment 22 of a
cross-section less than that of a second hollow tubular segment 24.
A stiff member 29 is provided to control the position of the distal
stent segment 2 of the self-stabilizing prosthetic stent 1 after
the distal stent segment 2 has reached the desired target organ or
body cavity.
[0070] The second exemplary embodiment of the methods for inserting
and withdrawing the self-stabilizing prosthetic stent 1 using the
stent assembly 200 is shown in FIGS. 13-15. The self-stabilizing
prosthetic stent 1 is mounted upon the first hollow tubular segment
22 of the delivery catheter 20 of the stent assembly 200. The
self-stabilizing prosthetic stent 1 is mounted such that the distal
stent segment 2 and the proximal stent segment 3 do not abut one
another. A stiff member 29, which is provided through the first and
second hollow tubular segments 22 and 24 of the delivery catheter
20 and through the distal and proximal stent segments 2 and 3 and
the flexible connecting structure 14", maintains the distal and
proximal stent segments 2 and 3 in non-abutting fashion relative to
one another during insertion of the stent 1 into the anatomical
tract.
[0071] The non-abutting relationship of the distal and proximal
stent segments 2 and 3 during the insertion method of the second
exemplary embodiment permits the flexible connecting structure 14"
to be at least partially extended, though it need not be taut,
throughout the insertion process of the stent 1 into the anatomical
tract. FIGS. 13-15 shows the flexed status of the flexible
connecting structure 14" as indicated by the curved, flexed thin
wires of the flexible connecting structure 14".
[0072] The stent 1 is mounted upon the delivery catheter 20 such
that a smaller diametered first hollow tubular segment 22 of the
delivery catheter 20 is ensleeved by the distal stent segment 2,
the at least partially extended flexible connecting structure 14",
and the proximal stent segment 3. A trailing end of the proximal
stent segment 3 rests on a shoulder of a second hollow tubular
segment 24 having a diameter larger than that of the first hollow
tubular segment 22. The shoulder of the second hollow tubular stent
segment 24 advances the stent 1 into the anatomical tract by
maintaining contact with the proximal stent segment 3 during
insertion of the stent 1 into the anatomical tract.
[0073] Because of the non-abutting relationship of the distal and
proximal segments 2 and 3, the flexible connecting structure 14"
joining the distal and proximal stent segments 2 and 3 is at least
partially extended, though not taut, as indicated by the curved,
flexed status of the thin wires of the flexible connecting
structure 14" in FIGS. 13-15.
[0074] The at least semi-rigid quality of the first hollow tubular
segment 22 spans across the anatomical constricting structure, such
as, for example, the sphincter 18 as the self-stabilizing
prosthetic stent 1 is inserted into the anatomical tract, such as,
for example, the urethra 19. By spanning across the anatomical
constricting structure, such as, for example, the sphincter 18, the
sphincter 18 and the flexible connecting structure 14" remain open
for fluid to flow through the orifice or opening 6 into the distal
stent segment 2, the flexible connecting structure 14", the
proximal stent segment 3, and the delivery catheter 20 when the
generally closed end 5 of the distal stent segment 2 reaches the
target organ, such as, for example, the bladder 15.
[0075] Once fluid flow through the self-stabilizing prosthetic
stent 1 and delivery catheter 20 is detected, the self-stabilizing
prosthetic stent 1 has reached the target organ and/or body cavity,
such as, for example, the bladder 15. A stiff member 29 is provided
through the first and second hollow tubular segments 22 and 24 of
the delivery catheter 20 to hold the distal stent segment 2 in
place until the delivery catheter 20 is withdrawn.
[0076] As shown in FIG. 14, the delivery catheter 20 is then
withdrawn to below the anatomical constricting structure, such as,
for example, the sphincter 18. The flexible connecting structure
14" is then subject to the naturally occurring relaxing and
constricting actions of the sphincter 18, such that fluid flow
through the self-stabilizing prosthetic stent 1 and the delivery
catheter 20 stops or slows. The stopping or slowing of fluid flow
indicates the flexible connecting structure 14" is appropriately
seated within the sphincter 18 region. More specific placement of
the flexible connecting structure 14" may be achieved by gently
tugging on at least one of the withdrawal threads, pull-wires, or
other equivalent structures 8 until fluid flow stops completely, or
is otherwise voluntarily controlled by the patient.
[0077] Thereafter, as shown in FIG. 15, the delivery catheter 20 is
fully withdrawn and then the stiff member 29 is withdrawn, leaving
the properly placed self-stabilizing prosthetic stent 1 in the
anatomical tract, such as, for example, the urethra 19 such that
the natural functioning of the anatomical constricting structure,
such as, for example, the sphincter 18 is maintained.
[0078] It should be appreciated that the non-abutting relationship
of the distal and proximal stent segments 2 and 3 could be achieved
instead by friction fitting the distal stent segment 2 and proximal
stent segment 3 onto the first hollow tubular segment 22 using an
adjustable diametered first hollow tubular segment, releasable
distal and proximal stent segment position holding structures, or
other equivalent structures to hold the distal stent segment 2 and
proximal stent segment 3 in place in non-abutting relation relative
to one another during insertion of the stent 1 into the anatomical
tract. After insertion of the stent 1, the delivery catheter could
then be removed by reducing the diameter so that friction fitting
no longer exists, or the release structures or other equivalent
structures could be operated to permit withdrawal of the delivery
catheter.
[0079] Withdrawal of the self-stabilizing prosthetic stent 1 is
accomplished as in the earlier exemplary embodiments by tugging
sufficiently on at least one of the withdrawal threads, pull-wires,
or other equivalent structures 8 to overcome the anatomical
constricting forces of the anatomical constricting structure, such
as, for example, the sphincter 18. Having overcome the anatomical
constricting forces, the self-stabilizing prosthetic stent 1 is
freely removable from the anatomical tract, such as, for example,
the urethral tract 19.
[0080] FIG. 16 illustrates a third exemplary embodiment of a stent
assembly 300 and an exemplary embodiment of the stent 1 according
to this invention. As shown in FIG. 16, this third exemplary
embodiment of the stent assembly 300 accommodates the third and
fourth exemplary embodiments of the stent insertion and withdrawal
methods according to this invention, as shown in FIGS. 16-25.
[0081] In the third exemplary embodiment of the stent assembly 300,
as shown in FIG. 16, the self-stabilizing prosthetic stent 1 again
includes the distal segment 2 having the orifice or opening 6 for
permitting fluid flow through the self-stabilizing prosthetic stent
1, the proximal stent segment 3, the one or more withdrawal
threads, pull-wires, or other equivalent structures 8, and one of
the flexible connection structures 4 or 14 as outlined above. In
addition, the third exemplary embodiment of the stent assembly 300
shown in FIG. 16 includes the delivery catheter 20, a proximal
segment release structure 26, a distal segment release structure
28, and the stiff member 29. In general, the stiff member 29 is
usable to control the position of the distal segment 2 of the
self-stabilizing prosthetic stent 1.
[0082] In various exemplary embodiments, the delivery catheter 20
includes the two tubular segments 22 and 24. The first segment 22
has a cross-section that is less than the cross-section of the
second segment 24 and that is less than the cross-section of the
distal and proximal segments 2 and 3. Thus, the stent 1 is mounted
upon the first segment 22 of the delivery catheter 20 for inserting
the stent 1 into an anatomical tract such that the generally closed
end 5 of the distal segment 2 of the stent 1 enters the anatomical
tract first as the self-stabilizing prosthetic stent 1 is inserted
to the anatomical tract.
[0083] An end 28a of the distal segment release structure 28
protrudes through the wall of the delivery catheter 20 to hold the
distal segment 2 relative to the first tubular segment 22 as the
stent assembly 300 is used to advance the stent 1 into position in
the anatomical tract. Similarly, an end 26a of the proximal segment
release structure 26 protrudes through the wall of the delivery
catheter 20 to hold the proximal segment 3 relative to the second
tubular segment 24 as the stent assembly 300 is used to advance the
stent 1 into position in the anatomical tract.
[0084] The distal and proximal segment release structures 28 and
26, respectively, hold the distal and proximal segments 2 and 3,
respectively, relative to the delivery catheter 20 such that the
distal and proximal segments 2 and 3 approximately abut one another
when the self-stabilizing prosthetic stent 1 is mounted on the
delivery catheter 20 to form stent assembly 300. This causes the
flexible connecting structure 4 or 14 to take a collapsed state,
especially as the stent 1 is inserted into the anatomical tract. As
a result, relative to the first and second exemplary embodiments of
the stent assembly 100 and 200, the third exemplary embodiment of
the stent assembly 300, because the distal segment 2 of the stent 1
approximately abuts the proximal segment 3 of the stent 1, provides
an outer surface of the stent 1 as a part of the stent assembly 300
that is relatively smoother and more continuous.
[0085] Once inserted through the anatomical tract, such as, for
example, a urethral tract 19, as shown schematically in FIGS.
17-25, the distal segment 2 is maintained in place relative to the
target organ and/or body cavity by the stiff member 29 projecting
through the delivery catheter 20 and-through the stent 1. That is,
the stiff member 29 contacts a portion of the generally closed end
5 of the stent 1 to hold the stent in place relative to the
targeted organ or body cavity, such as, for example, the bladder
15. Fluid flow through the lateral orifice or opening 6 of the
distal segment 2 once again indicates that the stent 1 has been
placed in the desired position adjacent to or extending into the
target body organ or body cavity, such as, for example, the bladder
15.
[0086] FIGS. 17-20 illustrate the insertion steps of a third
exemplary embodiment of the method according to this invention of
inserting the stent 1 using the third exemplary embodiment of the
stent assembly 300. As shown in FIG. 17, the stent 1 is mounted
upon the first segment 22 of the delivery catheter 20 such that the
distal and proximal segments 2 and 3 abut due to the collapsed
state of the flexible connecting structure 4 or 14. The generally
closed end 5 of the distal segment 2 of the stent 1 enters the
anatomical tract first. The distal release structure 28 maintains
the position of the distal segment 2 relative to the delivery
catheter 20 during insertion using the end 28a that protrudes
through the wall of the delivery catheter 20. The proximal release
structure 26 maintains the position of the proximal segment 3
relative to the delivery catheter 20 during insertion using the end
26a that protrudes through the wall of the delivery catheter. The
ends 26a and 28a of the proximal and distal release structures 26
and 28 thus maintain the proximal and distal segments 3 and 2 in
the abutting relation during insertion. The abutting relation of
the proximal and distal segments 3 and 2 is maintained until one or
both of the proximal and distal release structures 26 and 28 is
removed from the delivery catheter 20 after the stent 1 is
inserted.
[0087] As shown in FIG. 18, the stent 1 is fully inserted through
the anatomical tract 19 such that the stent 1 reaches a target
organ or cavity, such as, for example, the bladder 15. In
particular, in this third exemplary embodiment of the method, the
distal segment 2 is positioned entirely above the anatomical
constricting structure, such as, for example, the sphincter 18. A
flow of fluid through the orifice or opening 6 of the distal
segment 2 of the stent 1 and delivery catheter 20 indicates the
stent 1 has reached the target organ or body cavity, such as, for
example, the bladder 15.
[0088] Thereafter, as shown in FIG. 19, the distal segment release
structure 28 is removed. As a result, the distal segment 2 is
released from the delivery catheter 20. The stiff member 29 remains
in position stabilizing the distal segment 2. Thus, the delivery
catheter 20 can be withdrawn without affecting the position of the
distal segment 2. Next, either at the same time or at some time
thereafter, the delivery catheter 20 is incrementally withdrawn to
below the sphincter 18. The withdrawal of the distal segment
release structure 28 from the stent assembly 300 and the
incremental withdrawal of the delivery catheter 20 to below the
sphincter 18 permits the flexible connection structure 4 or 14 to
extend from the collapsed state and to assume a position in the
region of the anatomical constricting structure, such as, for
example, the sphincter 18. The flexible quality of the connecting
structures 4 or 14 permits the natural relaxing and constricting
functions of the anatomical constricting structure, such as, for
example, the muscles of the sphincter 18, to occur. As a result,
the flow of fluid through the stent 1 and delivery catheter 20
ceases, or is otherwise voluntarily controlled by the patient. The
ability of the patient to stop, or otherwise control the fluid flow
indicates the stent 1 is appropriately positioned within the
anatomical tract 19 and across the anatomical constricting
structure, such as, for example, the sphincter 18.
[0089] Thereafter, as shown in FIG. 20, the stiff member 29 is
withdrawn. As also shown in FIG. 20, the proximal segment release
structure 26 is also withdrawn. As a result, the proximal segment 3
is released from the delivery catheter 20. Thus, the delivery
catheter 20 and the proximal stent segment 3 can move within the
anatomical tract relative to one another. This permits the flexible
connection structure 4 or 14 to more fully extend and seat itself
within the anatomical constricting structure, such as, for example,
the sphincter 18.
[0090] Finally, as also shown in FIG. 20, the delivery catheter 20
is completely withdrawn from the anatomical tract 19. As a result,
the stent 1 remains in the anatomical tract 19 as an artificial
passage having the flexible connecting structure 4 or 14 that is
compliant with the natural constricting functions of, for example,
the sphincter 18.
[0091] FIGS. 21-25 shows a fourth exemplary embodiment of the
method of inserting the stent according to this invention. As shown
in FIG. 21, the stent 1 is mounted upon the first segment 22 of the
delivery catheter 20 such that the distal and proximal segments 2
and 3 abut due to the collapsed state of the one of the flexible
connecting structures 4 or 14. Again, the generally closed end 5 of
the distal segment 2 of the stent 1 enters the anatomical tract
first. The distal release structure 28 maintains the position of
the distal segment 2 relative to the delivery catheter 20 during
insertion using the end 28a that protrudes through the wall of the
delivery catheter 20. The proximal release structure 26 maintains
the position of the proximal segment 3 relative to the delivery
catheter 20 during insertion using the end 26a that protrudes
through the wall of the delivery catheter. The ends 26a and 28a of
the proximal and distal release structures 26 and 28 thus maintain
the proximal and distal segments 3 and 2 in abutting relation
during insertion. The abutting relation of the proximal and distal
segments 3 and 2 is maintained until one or both of the proximal
and distal release structures 26 and 28 is removed from the
delivery catheter 20 after the stent 1 is at least partially
inserted.
[0092] As shown in FIG. 22, the stent 1 is fully inserted through
the anatomical tract 19 such that the stent 1 reaches the target
organ or body cavity, such as, for example, the bladder 15, and the
distal segment 2 is positioned entirely above the anatomical
constricting structure, such as, for example, the sphincter 18.
Again, the flow of fluid through the orifice or opening 6 of the
distal segment 2 of the stent 1 and the delivery catheter 20
indicates the stent 1 has reached the target organ or body cavity,
such as, for example, the bladder 15.
[0093] Thereafter, as shown in FIG. 23, the distal and proximal
segment release structures 28 and 26 are removed in sequence. The
distal and proximal stent segment release structures 28 and 26 are
not removed simultaneously. This method is like the previous
method, except that the delivery catheter is removed first,
followed by the stiff member 29. Thus, once initial fluid or gas
flow demonstrates that the anatomical cavity has been attained, the
distal stent segment release structure 28 is removed. Stabilized by
the stiff member 29, the distal stent segment 2 remains in position
while the proximal stent segment 3, still mounted on the delivery
catheter 20, is withdrawn to a position proximal to the sphincter
18. When the patient can demonstrate voluntary control of
micturition, then the proximal stent release structure 26, is
removed. Now, in distinction to the prior method, the stiff member
29 remains while the delivery catheter is withdrawn, followed by
removal of the stiff member 29.
[0094] The release of the proximal and distal release segment
structures 26 and 28, and the incremental release of the delivery
catheter 20 to below the sphincter 18 permits the flexible
connecting structure 4 or 14 to relax from its collapsed state such
that the connecting structure 4 or 14 assumes a position in the
region of, for example, the sphincter 18. The flexible connecting
structure 4 or 14, when positioned within the region of the
sphincter 18, permits the natural relaxing and constricting
functions of the anatomical constricting structure, such as, for
example, the muscles of the sphincter 18, to occur. As a result,
fluid flow through the stent 1 and delivery catheter 20 ceases, or
is otherwise voluntarily controlled by the patient. The ceasing, or
patient control of the fluid flow, indicates that the stent 1 and
the flexible connecting structure 4 or 14 are appropriately placed
within the anatomical tract 19 such that the stent 1 provides an
artificial passage through the anatomical tract 19.
[0095] Thereafter, as shown in FIG. 24, the delivery catheter 20 is
completely withdrawn from the anatomical tract 19 permitting the
flexible connecting structure 4 or 14 to fully extend or relax such
that it seats even more compliantly within the musculature of the
anatomical constricting structure, such as, for example, the
sphincter 18. The stiff member 29 is maintained in position to keep
the stent 1 from drifting or moving until all other components of
the stent insertion assembly 300 are successfully withdrawn.
[0096] Finally, as shown in FIG. 25, the stiff member 29 is
completely withdrawn from the anatomical tract 19.
[0097] FIG. 26 shows a fifth exemplary embodiment of a stent
assembly 400 and another exemplary embodiment of the stent 1. As
shown in FIG. 26, in this exemplary embodiment, the stent 1 has an
elongated distal segment 2" as compared to the distal segment 2 of
the third and fourth exemplary embodiments, and a truncated
proximal segment 3" as also compared to the proximal segment 3 of
the third and fourth exemplary embodiments.
[0098] As shown in FIGS. 27 and 28, the elongated distal segment 2"
permits the distal segment 2" to penetrate a target organ and/or
body cavity, such as, for example, the bladder 15 while still
spanning across the anatomical constricting structure, such as, for
example, the sphincter 18 during insertion of the stent 1 to the
anatomical tract. Because the elongated distal segment 2" spans the
anatomical constricting structure, such as, for example, the
sphincter 18, the flow of fluid from the target organ and/or body
cavity, such as, for example, the bladder 15 is permitted to flow
through the stent 1 and the delivery catheter 20 indicating the
elongated distal segment 2" has reached, for example, the bladder
15.
[0099] FIGS. 27-31 show a fifth exemplary embodiment of a method
for inserting a self-stabilizing prosthetic stent according to this
invention. In this fifth exemplary embodiment, the stent 1 is
initially inserted, with the distal and proximal segments 2 and 3
abutting one another, as shown in either of FIGS. 18 and 22.
[0100] Thus, as shown in FIG. 27, the elongated distal segment 2"
is both positioned relative to the target organ or body cavity and
holds open the anatomical constricting structure, such as, for
example, the sphincter 18. As a result, the truncated proximal
segment 3" lies entirely below the anatomical constricting
structure, such as, for example, the sphincter 18. This is in
contrast to the third and fourth exemplary embodiments described
above, where the distal segment 2 lies entirely above the
anatomical constricting structure and the proximal segment 3 holds
the anatomical constricting structure open.
[0101] Thereafter, as shown in FIG. 28, the proximal and distal
segment release structures 26 and 28 are withdrawn. Upon release of
the proximal and distal segment release structures 26 and 28, the
truncated proximal segment 3" and the elongated distal segment 2"
are released from the delivery catheter 20. Thus, the delivery
catheter 20 and the truncated proximal segment 3" and the elongated
distal segment 2" can move within the anatomical tract relative one
another.
[0102] Next, as shown in FIG. 29, a stiff member 29 is used to
advance the generally closed end 5 of the elongated distal segment
2" further upward relative to the target organ and/or body cavity,
such as, for example, the bladder 15. As a result, the elongated
distal segment 2" and the truncated proximal segment 3" no longer
abut one another and the flexible connecting structure 4 extends to
seat within the anatomical constricting structure, such as, for
example, the sphincter 18. As shown in FIG. 29, the elongated
distal stent segment 2" is moved upward so that it is entirely
above the anatomical constricting structure, such as, for example,
the sphincter 18. As a result, the flexible connecting structure 4
or 14 is relaxed from the collapsed state and located within the
region of the anatomical constricting structure, such as, for
example; the sphincter 18. The stiff member 29 is used to maintain
the elongated distal stent segment 2" in position relative to the
target organ and/or body cavity, for example, the bladder 15, while
the other elements of the stent delivery assembly 400 are
withdrawn.
[0103] Thereafter, as shown in FIG. 30, the first and second
tubular segments 22 and 24 of the delivery catheter 20 are
withdrawn from the anatomical tract 19. As a result, the stiff
member 29 holds the stent 1 in place to appropriately position the
extended flexible connecting structure 4 within the anatomical
constricting structure, such as, for example, the sphincter 18. As
in earlier described embodiments, a gentle tugging on at least one
of the withdrawal threads, pull-wires, or other equivalent
structures 8 provide a more specific positioning of the flexible
connecting structure 4 within the anatomical constricting
structure, such as, for example, the sphincter 18.
[0104] Then, as shown in FIG. 31, the stiff member 29 is removed.
As a result, the self-stabilizing prosthetic stent 1 is securely
and appropriately placed within the anatomical constricting
structure, such as, for example, the sphincter 18 so that the
flexible connecting structure 4 complies with the naturally
occurring relaxing and constricting functions of, for example, the
sphincter 18.
[0105] In either of the embodiments shown in FIGS. 16-31,
withdrawing the stent 1 from the anatomical tract 19 is
accomplished similar to that described in the first and second
exemplary embodiments of the method. That is, a steady pulling
force on at least one of the withdrawal threads, pull-wires, or
other equivalent structures 8 overcomes the resistance of the
muscles of the anatomical constricting structure, such as, for
example, the resistance of the muscles of the sphincter 18 such
that the stent 1 can slidingly descend through the anatomical tract
19 for removal.
[0106] It should further be appreciated that, in yet another
embodiment, the elongated distal and truncated proximal stent
segments 2" and 3" may be mounted in abutting relation to one
another on first and second tubular segments 22' and 24' of the
delivery catheter 20'. The first and second tubular segments 22'
and 24' have substantially the same diameter. This is in contrast
to the differing diameters of the first and second tubular segments
22 and 24 of earlier described embodiments. As a result, the stent
1 is inserted into the desired anatomical tract, such as, for
example, the urethra 19 and across the anatomical constricting
structure, such as, for example, the sphincter 18. The delivery
catheter 20' prohibits the sphincter 18 from closing. When the
generally closed end 5 of the distal segment 2 reaches the bladder
15, fluid flows through the stent 1 and delivery catheter 20'
indicating the target organ and/or body cavity, such as, for
example, the bladder 15 has been reached.
[0107] Thereafter, the proximal release structure 26 is removed and
the delivery catheter 20' is used to advance the elongated distal
segment 2" further upwards relative to the bladder 15 to extend the
flexible connecting structure 4 within the region of the anatomical
constricting structure, such as, for example, the sphincter 18.
Thus, it should be appreciated that the delivery catheter 20' moves
through the proximal segment 3" as the delivery catheter 20' is
advanced further into the urethra 19. Then the distal release
structure 28 is removed.
[0108] Next, the first and second tubular segments 22' and 24' of
the delivery catheter 20' are removed. The flexible connecting
structure 4 may be manipulated to a more appropriate position
within the anatomical constricting structure, such as, for example,
the sphincter 18, by gently pulling on the at least one withdrawal
threads, pull-wires, or other equivalent structures 8.
[0109] Finally, the stiff member 29 is removed leaving the stent 1
appropriately positioned within the anatomical constricting
structure, such as, for example, the sphincter 18 to comply with
the naturally occurring actions of the sphincter 18. However, it
should be appreciated that the stiff member 29 could be removed
earlier in the process.
[0110] It should be appreciated that seating of the flexible
connecting structure 4 or 14 in any of the embodiments described
related to FIGS. 26-31 need not require an elongated distal segment
2" provided that a sufficiently long flexible connecting structure
4 or 14 is used. As in earlier described embodiments, the
connecting structure 4 or 14 joins the distal and proximal segments
2 and 3. As the stent 1 is inserted into the anatomical tract, such
as, for example, the urethra 19, the length of the flexible
connecting structure 4 or 14 permits the proximal segment 3 to
remain entirely below the anatomical constricting structure, such
as, for example, the sphincter 18.
[0111] Then, either the distal segment 2 is manipulated further
upward relative to the target organ and/or body cavity to extend
the flexible connecting structure 4 or 14 in the anatomical
constricting structure, such as, for example, the sphincter 18, or
the proximal segment 3 is manipulated downward relative to the
anatomical constricting structure, such as, for example, the
sphincter 18 to extend the flexible connecting structure 4 or 14
across the anatomical constricting structure, such as, for example,
the sphincter 18.
[0112] In either case, the flexible connecting structure 4 or 14
may be more specifically positioned within the anatomical
constricting structure, such as, for example, the sphincter 18 by
gently tugging on the withdrawal threads, pull-wires, or other
equivalent structures 8 so that the stent 1 complies with the
naturally occurring functions of the sphincter 18.
[0113] It should be appreciated that in all of the exemplary
embodiments requiring a stiff member 29, the stiff member 29 may be
blunted or otherwise shaped on the end of the stiff member 29 that
contacts the closed rounded end of the distal segment. The blunting
or otherwise shaped end of stiff member 29 may prevent the
"spearing" of the closed rounded end 5 of the distal stent segment
2. The blunting or otherwise shaped end of stiff member 29 may also
prevent the stiff member from accidentally protruding through the
opening 6 of the distal stent segment 2.
[0114] Still further, it should be appreciated that all of the
embodiments described herein are exemplary only and that this
invention, including the stent 1, and methods of inserting and
withdrawing the stent 1 from an anatomical tract of a living being
may also be used to instill fluids, or other irrigating solutions,
to a target body cavity or organ as well rather than for the
exemplary described purpose of emptying or eliminating fluids from,
for example, a target organ or body cavity of a living being.
Further, it should be appreciated that the invention may also be
used to insert or control other instruments, e.g., an endoscope, to
view, or otherwise involve, a target body cavity or organ by
deploying an instrument through the assembly 100, 200 or 300 and
stent 1 using the methods and devices herein described.
[0115] While this invention has been described in conjunction with
the exemplary embodiments outlined above, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art. Accordingly, the exemplary embodiments of
the invention, as set forth above, are intended to be illustrative,
not limiting. Various changes may be made without departing from
the spirit and scope of the invention.
* * * * *