U.S. patent application number 12/715016 was filed with the patent office on 2010-10-28 for stent delivery system having stent securement apparatus.
This patent application is currently assigned to BOSTON SCIENTIFIC SCIMED, INC.. Invention is credited to David J. Blaeser, Terry V. Brown, Fernando Di Caprio, Andrew J. Dusbabek, Louis G. Ellis, Charles L. Euteneuer, Christopher R. Larson, Linda R. Lorentzen Cornelius, Richard C. Mattison, Steven P. Mertens, Stanley A. Nordin, Martin R. Willard.
Application Number | 20100274344 12/715016 |
Document ID | / |
Family ID | 27505462 |
Filed Date | 2010-10-28 |
United States Patent
Application |
20100274344 |
Kind Code |
A1 |
Dusbabek; Andrew J. ; et
al. |
October 28, 2010 |
Stent Delivery System Having Stent Securement Apparatus
Abstract
A system/assembly for delivery and deployment of an inflation
expandable stent within a vessel, comprising a catheter having
proximal and distal ends; a stent, inflation expandable from a
delivery diameter to a deployment diameter, such that the delivery
diameter is reduced from the deployment diameter for conforming the
stent to the catheter, such that the stent, in its delivery
diameter, is coaxially mounted on the catheter near the catheter
distal end; an expandable inflation means coaxially mounted on the
catheter axially within the stent, for expansion of the stent from
the delivery diameter to the deployment diameter upon application
of fluid deployment pressure to the inflation means; and a
securement component coaxially mounted on the catheter, axially
within the expandable inflation means, the securement component
designed and adapted to provide a securement pressure to the stent
in the delivery diameter to maintain the stent in position on the
catheter during delivery to the deployment site.
Inventors: |
Dusbabek; Andrew J.;
(Dayton, MN) ; Ellis; Louis G.; (St. Anthony,
MN) ; Larson; Christopher R.; (St. Paul, MN) ;
Brown; Terry V.; (Fridley, MN) ; Euteneuer; Charles
L.; (St. Michael, MN) ; Mertens; Steven P.;
(Plymouth, MN) ; Mattison; Richard C.; (Zimmerman,
MN) ; Blaeser; David J.; (Champlin, MN) ;
Lorentzen Cornelius; Linda R.; (Wayzata, MN) ;
Willard; Martin R.; (Maple Grove, MN) ; Di Caprio;
Fernando; (Mendota Heights, MN) ; Nordin; Stanley
A.; (Monticello, MN) |
Correspondence
Address: |
VIDAS, ARRETT & STEINKRAUS, P.A.
SUITE 400, 6640 SHADY OAK ROAD
EDEN PRAIRIE
MN
55344
US
|
Assignee: |
BOSTON SCIENTIFIC SCIMED,
INC.
Maple Grove
MN
|
Family ID: |
27505462 |
Appl. No.: |
12/715016 |
Filed: |
March 1, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10737497 |
Dec 16, 2003 |
7670364 |
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12715016 |
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|
09794648 |
Feb 27, 2001 |
6663660 |
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10737497 |
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|
09418277 |
Oct 14, 1999 |
6203558 |
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09794648 |
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08916544 |
Aug 22, 1997 |
5960497 |
|
|
09418277 |
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08807791 |
Feb 28, 1997 |
6077273 |
|
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08916544 |
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|
08702150 |
Aug 23, 1996 |
6007543 |
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08807791 |
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08697453 |
Aug 23, 1996 |
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08702150 |
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08701979 |
Aug 23, 1996 |
6395008 |
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08697453 |
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Current U.S.
Class: |
623/1.12 |
Current CPC
Class: |
A61M 25/1018 20130101;
A61F 2002/9586 20130101; A61M 25/10186 20131105; A61M 25/10184
20131105; A61M 2025/1079 20130101; A61F 2002/9583 20130101; A61M
2025/1081 20130101; A61M 25/104 20130101; A61M 2025/1013 20130101;
A61F 2/958 20130101; A61M 2025/1093 20130101; A61M 2025/1063
20130101; A61M 25/10182 20131105; A61M 25/1011 20130101; A61F
2/9522 20200501 |
Class at
Publication: |
623/1.12 |
International
Class: |
A61F 2/84 20060101
A61F002/84 |
Claims
1. A system/assembly for delivery and deployment of an inflation
expandable stent within a vessel, comprising: a catheter having
proximal and distal ends; a stent, inflation expandable from a
delivery diameter to a deployment diameter, such that the delivery
diameter is reduced from the deployment diameter for conforming the
stent to the catheter, such that the stent, in its delivery
diameter, is coaxially mounted on the catheter near the catheter
distal end; an expandable inflation means coaxially mounted on the
catheter axially within the stent, for expansion of the stent from
the delivery diameter to the deployment diameter upon application
of fluid deployment pressure to the inflation means; and a
securement component coaxially mounted on the catheter, axially
within the expandable inflation means, the securement component
designed and adapted to provide a securement pressure to the stent
in the delivery diameter to maintain the stent in position on the
catheter during delivery to the deployment site.
2. The system of claim 1, the catheter having a shaft and the
expandable inflatable means associated therewith at a distal part
of the shaft and including mounting and retaining means for
receiving the stent on the expandable means for radial expansion of
the stent, the mounting and retaining means being associated with
the inflatable means and being constructed and arranged for
selectively providing an enlarged mounting body for receiving the
stent.
3. The system of claim 2 wherein the mounting body is inside the
inflatable means.
4. The system of claim 2 wherein the mounting body is outside the
inflatable means.
5. The system of claim 2, the inflatable means being a balloon,
wherein the mounting body is carried by the catheter and is axially
movable between the stent mounting position associated with the
balloon and a position removed from the stent mounting
position.
6. The system of claim 1, the catheter having a shaft, the
expandable inflatable means being associated therewith at a distal
part of the shaft and including mounting and retaining means for
receiving a stent on the expandable inflatable means and for radial
expansion of the stent upon inflation of the inflatable means, the
mounting and retaining means including at least one mounting body
carried on and surrounding the shaft inside the inflatable means
whereby the diameter of the shaft and inflatable portion may be
increased at the distal part of the shaft for facilitating the
mounting and retaining of the stent.
7. The delivery system of claim 6 wherein the mounting body is
axially movable with respect to the inside shaft, and including
means for moving the mounting body.
8. The stent delivery system of claim 7 wherein the mounting body
is of a material which resiliently deforms under radial
pressure.
9. The stent delivery system of claim 8 wherein the material
comprises HDPE or silicone.
10. The stent delivery system of claim 7 wherein the mounting body
configuration includes at least one separation whereby the
flexibility of the body and catheter is increased.
11. The stent delivery system of claim 10 wherein the separation is
in the form of a spiral.
12. The stent delivery system of claim 7 wherein the mounting body
is positionable to receive a stent and a stent is crimped to the
mounting and retaining means over the balloon for delivery.
13. The stent delivery system of claim 6 including a stop
positioned at the distal end portion of the inflatable means and
carried by the shaft inside the inflatable means.
14. The stent delivery system of claim 6 including at least one
marker band.
15. The stent delivery system of claim 6 wherein the inflatable
means comprises a balloon.
16. The stent delivery system of claim 6 including a stop
positioned at the distal end of the catheter and carried by the
shaft inside the inflatable means.
17. The stent delivery system of claim 6 wherein the mounting body
is in a fixed position and is adapted and arranged to enlarge in
diameter to receive a stent.
18. The stent delivery system of claim 17 wherein the mounting body
is a second inflatable means inside the first inflatable means, the
inner one being shaped to have wide end portions and a narrow
center portion.
19. The stent delivery system of claim 17 wherein the mounting body
is a coil-like structure adapted and arranged to be compressed and
the proximal portion of the inside shaft is connected thereto for
compressing the structure to enlarge its diameter.
20. The system of claim 17 wherein the mounting body is a sleeve
including radial accordion like pleats extending over at least a
portion of its length, the distal end being secured to the inside
shaft and a means for compressing the body from its proximal end
and attached thereto.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. Ser. No.
10/737,497, filed Dec. 16, 2003 and issued as U.S. Pat. No.
7,670,364, which is a continuation of U.S. Ser. No. 09/794,648,
filed Feb. 27, 2001 and issued as U.S. Pat. No. 6,663,660, which is
a continuation of U.S. Ser. No. 09/418,277, filed Oct. 14, 1999 and
issued as U.S. Pat. No. 6,203,558, which is a continuation of U.S.
Ser. No. 08/916,544, filed Aug. 22, 1997 and issued as U.S. Pat.
No. 5,968,069, which is a Continuation-in part application based on
U.S. Ser. No. 08/807,791, filed Feb. 28, 1997 and issued as U.S.
Pat. No. 6,077,273, U.S. Ser. No. 08/702,150, filed Aug. 23, 1996
and issued as U.S. Pat. No. 6,007,543, U.S. Ser. No. 08/697,453,
filed Aug. 23, 1996 abandoned, and U.S. Ser. No. 08/701,979, filed
Aug. 23, 1996 and issued as U.S. Pat. No. 6,395,008, all of which
are incorporated by reference in their entirety.
FIELD OF THE INVENTION
[0002] This invention relates to an assembly and method for
delivering and deploying an inflation expandable stent,
particularly within a lumen of a body vessel. More specifically,
this invention relates to stent securement devices most notably
positioned between the balloon and the inner shaft of the
catheter.
BACKGROUND OF THE INVENTION
[0003] Stents and stent delivery assemblies are utilized in a
number of medical procedures and situations, and as such their
structure and function are well-known. A stent is a general
cylindrical prosthesis introduced via a catheter into a lumen of a
body vessel in a configuration having a generally reduced diameter
and then expanded to the diameter of the vessel. In its expanded
configuration, the stent supports and reinforces the vessel walls
while maintaining the vessel in an open, unobstructed
condition.
[0004] Both self-expanding and inflation expandable stents are
well-known and widely available. Self-expanding stents must be
maintained under positive external pressure in order to maintain
their reduced diameter configuration during delivery of the stent
to its deployment site. Inflation expandable stents (also known as
balloon expandable stents) are crimped to their reduced diameter
about the delivery catheter, positioned at the deployment site, and
then expanded to the vessel by diameter by fluid inflation of the
balloon positioned between the stent and the delivery catheter. The
present invention is particularly concerned with enhanced stent
securement and safer stent loading in the delivery and deployment
of balloon expandable stents.
[0005] In angioplasty procedure, there may be restenosis of the
artery, which either necessitates another angioplasty procedure, a
surgical bi-pass procedure, or some method of repairing or
strengthening the area. To prevent restenosis and strengthen the
area, a physician can implant an intravascular prosthesis for
maintaining vascular patency, i.e. a stent, inside the artery at
the lesion. The stent is expanded to a larger diameter for
placement in the vasculature, often by the balloon portion of the
catheter. Stents delivered to a restricted coronary artery,
expanded to a larger diameter as by a balloon catheter, and left in
place in the artery at the site of a dilated lesion are shown in
U.S. Pat. No. 4,740,207 to Kreamer; U.S. Pat. No. 5,007,926 to
Derbyshire; U.S. Pat. No. 4,733,665 to Palmaz; U.S. Pat. No.
5,026,377 to Burton et al.; U.S. Pat. No. 5,158,548 to Lau et al.;
U.S. Pat. No. 5,242,399 to Lau et al.; U.S. Pat. No. 5,344,426 to
Lau et al.; U.S. Pat. No. 5,415,664 to Pinchuck; U.S. Pat. No.
5,453,090 to Martinez et al.; U.S. Pat. No. 4,950,227 to Savin;
U.S. Pat. No. 5,403,341 to Solar; U.S. Pat. No. 5,108,416 to Ryan
et al.; and European Patent Application No. 707837A1 to Scheiban,
all of which are incorporated herein by reference. A stent
particularly preferred for use with this invention is described in
PCT Application No. 96/03092-A1, published 8 Feb. 1996, the content
of which is incorporated herein by reference.
[0006] In advancing a balloon expandable stent through a body
vessel to the deployment site, there are a number of important
considerations. The stent must be able to securely maintain its
axial position on the delivery catheter. The stent, particularly
its distal and proximal ends, are sometimes protected to prevent
distortion of the stent, and minimize trauma to the vessel walls.
Balloon expandable stent delivery and deployment assemblies are
known which utilize restraining means that overlay the stent during
delivery. U.S. Pat. No. 4,950,227 to Savin et al., relates to a
balloon expandable stent delivery system in which a sleeve overlaps
the distal or proximal margin (or both) of the stent during
delivery. During inflation of the stent at the deployment site, the
stent margins are freed of the protective sleeve(s) and the sleeves
then collapse toward the delivery catheter for removal. A number of
balloon expandable stent delivery and deployment assemblies do not
use overlaying restraining members, such as the Savin sleeves, to
position the stent for delivery. European Patent Application No. EP
055 3960A1 to Lau et al., uses an elastic sheath interspaced
between the balloon and the stent. The sheath is said to act as a
barrier to protect the balloon from the stent, allow uniform stent
expansion, decrease balloon deflation time, prevent undesirable
balloon flattening upon deflation and provide a friction substrate
for the stent. The Lau sheath can be positioned on the inside or
outside of the balloon. U.S. Pat. No. 5,409,495 to Osborne,
similarly uses an elastic sleeve or sheath surrounding and in
contact with the balloon for controlling the balloon radial
expansion. In addition, Osborne is said to use restraining bands or
a pair of balloons to achieve controllable stent expansion
characteristics. U.S. Pat. No. 5,403,341 to Solar, relates to stent
delivery and deployment assembly which uses a retaining sheath
positioned about opposite ends of the compressed state. The
retaining sheaths of Solar are adapted to tear under pressure as
the stent is radially expanded, thus releasing the steno for
engagement with the sheaths. U.S. Pat. No. 5,108,416 to Ryan et al.
describes a stent introducer system which uses one or two flexible
end caps and annular socket surrounding the balloon to position the
stent during introduction to the deployment site. The content of
all of these patents is incorporated herein by reference.
[0007] In positioning a balloon expandable stent on the delivery
catheter over the fluid expandable balloon, the stent must be
smoothly and evenly crimped to closely conform to the overall
profile of the catheter and the unexpanded balloon. It has been
noted that, due to physical properties of the material used in
manufacturing the stent (typically a shaped memory metal, such as
stainless steel or Nitinol.TM.) there is a certain amount of
"recoil" of the stent despite the most careful and firm crimping.
That is the stent evidences a tendency to slightly open up from the
fully crimped position and once the crimping force has been
released. For example, in the typical stent delivery and deployment
assembly, if the stent has been fully crimped to a diameter of
approximately 0.0035'', the stent has been observed to open up or
recoil to approximately 0.0037''. This phenomenon has been
characterized as "recoil crimping". Due to recoil crimping to this
slightly enlarged diameter, it can be understood that the stent
tends to evidence a certain amount of looseness from its desired
close adherence to the overall profile of the underlying catheter
and balloon. That is, the stent tends to have a perceptible
relatively slack fit in its mounted and crimped position. During
delivery, the stent can thus tend to slip and dislocate from its
desired position on the catheter or even become separate from the
catheter, requiring further intervention by the physician.
[0008] According to the present invention, a securement device is
secured over the inner catheter beneath the balloon to compensate
for the undesired looseness or slack that due to recoil crimping
and to aid in securing the stent to the balloon, as well as
protecting the balloon material from being sandwiched between the
stent and any metal or protruding item which may be mounted on the
inner shaft/guide wire lumen, for delivery of the stent. The
securement devices secure the stent during tracking and delivery
and provide a good friction fit to the stent and insure good
contact between the stent and underlying balloon and catheter,
instead of merely crimping the stent onto the balloon and the
underlying catheter and relying on the bulk of the flaccid balloon
to hold the stent on.
[0009] The art referred to and/or described above is not intended
to constitute an admission that any patent, publication or other
information referred to herein is "prior art" with respect to this
invention. In addition, this section should not be construed to
mean that a search has been made or that no other pertinent
information as defined in 37 C.F.R. .sctn.1.56(a) exists.
SUMMARY OF THE INVENTION
[0010] This invention concerns a catheter apparatus suitable for
performing angioplasty and for delivery of stents to body cavities.
In general, stents are prosthetic devices which can be positioned
within a body cavity, for example, a blood vessel or in some other
difficultly accessible place of the body of a living human or
animal. The stent prosthesis is formed of a generally tubular body,
the diameter of which can be decreased or increased. Stents are
particularly useful for permanently widening a vessel which is
either in a narrowed state, or internally supporting a vessel
damaged by an aneurysm. Such stents are typically introduced into
the body cavity by use of a catheter. The catheter is usually of
the balloon catheter type in which the balloon is utilized to
expand the stent, which is positioned over the balloon for
delivery, to place it in a selected location in the body cavity.
The present invention is particularly directed to improved
arrangements for releasably attaching and securing the stent to the
catheter to facilitate delivery thereof, specifically having a
securement device within the balloon. The below identified
embodiments all disclose improved means for securing the stent to
the catheter during the delivery procedure.
[0011] In certain embodiments the stent is held in place on the
catheter by means of an enlarged mounting body carried within the
balloon by the catheter shaft to which the stent and balloon are
fitted. The stent is fitted over the balloon, as by crimping.
According to the invention in some embodiments, the enlarged body
is axially movable on the inner shaft of the catheter so that it
can be retracted from the stent mounting area to provide a small
profile for performing angioplasty. The catheter can then be
withdrawn; the enlarged body can be moved into the stent mounting
area; the stent can be mounted and the catheter can be re-inserted
to implant the stent. In other embodiments, the enlarged body can
be arranged to be reducible and enlargeable in size rather than
being movable. Alternatively, the movable mounting body may be
carried outside the balloon. A catheter of this type makes possible
a method in which, before stent loading with the associated
mounting body arranged to provide reduced diameter in the balloon
region, the catheter may be used to dilate a lesion or the like.
The catheter may be withdrawn and the mounting body may then be
selectively manipulated to provide an enlarged diameter in the
stent mounting region and a stent may be loaded onto the catheter.
The catheter may be re-inserted to implant the stent. The catheter
may be withdrawn or left in situ and the mounting body may be
manipulated to provide reduced diameter again and the catheter may
be used for any post-dilation desired. Also, the catheter may be
used multiple times in the procedure for dilation and stent
implantation.
[0012] Another embodiment of the present invention is also an
assembly for delivery and deployment of an inflation expandable
stent within a vessel. The assembly comprises a catheter, an
expandable tube component mounted on the catheter, an expandable
balloon mounted on the catheter and encompassing the tube
component, and a stent mounted on the balloon. The catheter has
proximal and distal ends. The stent is inflation expandable from a
delivery diameter to a deployment diameter. The delivery diameter
is reduced from the deployment diameter for conforming the stent to
the catheter. The stent, in its delivery diameter, is coaxially
mounted on the catheter near the catheter distal end. The
expandable balloon is coaxially mounted on the catheter axially
within the stent. The balloon is designed and adapted for expansion
of the stent from the delivery diameter to the deployment diameter
upon application of fluid deployment pressure to the balloon. The
expandable tube component is coaxially mounted on the catheter,
axially within the expandable balloon. The tube components is
designed and adapted for fluid expansion to provide a securement
pressure to the stent in the delivery diameter to maintain the
stent in position on the catheter during delivery to the deployment
site. The expandable tube component is sized and constructed to be
fluid expandable to no more than the delivery diameter. The tube
component is essentially equal in length to the stent and the stent
is positioned on the assembly essentially coextensive with the tube
component.
[0013] In another embodiment, this invention is a method for
delivering and deploying a stent using an assembly as just
described. A catheter is provided having proximal and distal ends.
An expandable balloon is coaxially mounted on the catheter. An
expandable tube component is coaxially mounted on the catheter,
axially within the expandable balloon. The balloon and the tube
component are each in an unexpanded condition. A stent is provided
which is expandable from a delivery diameter to a deployment
diameter. The stent, in a diameter greater than the delivery
diameter, is mounted on the balloon. The stent is collapsed to the
delivery diameter to conform to an overall profile of the catheter,
the tube component and the balloon. The tube component is inflated
to provide to the stent a securement pressure, to retain the stent
on the assembly in the delivery diameter. The assembly is delivered
to a deployment site. The balloon is inflated to expand the stent
to its deployment diameter.
[0014] An alternative embodiment of present invention is also an
assembly for delivery and deployment of an inflation expandable
stent within a vessel. The assembly comprises a catheter, an
expandable balloon mounted on the catheter, a corrugated tubing
mounted on the catheter beneath or within the balloon, and a stent
mounted on the balloon. The catheter has proximal and distal ends.
The stent is inflation expandable from a delivery diameter to a
deployment diameter. The delivery diameter is reduced from the
deployment diameter for conforming the stent to the catheter. The
stent, in its delivery diameter, is coaxially mounted on the
catheter near the catheter distal end. The expandable balloon is
coaxially mounted on the catheter axially within the stent. The
balloon is designed and adapted for expansion of the stent from the
delivery diameter to the deployment diameter upon application of
fluid deployment pressure to the balloon. The corrugated tubing is
mounted and adhered coaxially onto the catheter and is situated
between the balloon and the catheter itself When the stent is
crimped and loaded onto the balloon, the balloon is situated
therefore between the stent and the corrugated tubing. The tubing
is preferably essentially equal to the length of the stent and the
stent is positioned on the assembly essentially co-extensive with
the tube component. The tubing on the catheter effectively holds
the stent in place, takes up the slack due to recoil and protects
the balloon material from being damaged during crimping.
[0015] Still another embodiment of the present invention comprises
an assembly for delivery and deployment of an inflation expandable
stent. The assembly comprises a catheter having proximal and distal
ends. An annular collar or the like is coaxially located on the
catheter distal end. A fluid expandable balloon is coaxially
mounted over the collar at the catheter distal end. The balloon is
expandable from a contracted to an expanded state. A stent is
coaxially mounted on the balloon. The stent is inflation expandable
from a reduced to an enlarged condition, the reduced condition
conforming the stent to the balloon, collar and catheter in the
preferred embodiment. The stent has at least an end portion
overlying the balloon. At least one cup is coaxially mounted on the
catheter distal end. The cup has a first end portion which may
overlie the stent end portion. The cup and collar are cooperatively
constructed and arranged to retain the stent end portion on the
catheter in the stent reduced condition when the balloon is in the
contracted state. The balloon and catheter are cooperatively
constructed and arranged to cause expansion of the balloon from the
contracted to the expanded state to cause enlargement of the stent,
including the stent end portion, from the reduced to the enlarged
condition, and thereby release the stent end portion from the cup
end portion. The cup may be axially spaced from the collar but
preferably they are relatively close together. The second end
portion of the cup may be fixed to the catheter. The cup may
overlie at least a portion of the collar. The collar can be shaped
as a single member with the catheter, that is integral with it or
the collar may be a separate body mounted axially and positioned on
the catheter. The collar may be a mounting ring or cylinder axially
positioned between stent end portions under the stent and balloon.
The collar may be a sheath under the stent and balloon.
[0016] A further embodiment is also directed to improved
arrangements for releasably attaching the stent to the catheter to
facilitate delivery thereof. The stent is held in place on the
catheter by means of an enlarged body carried by the catheter shaft
within the balloon to which the stent and balloon are fitted, as by
crimping in combination with one or more sleeves releasably
overlying an end portion or portions of a stent and balloon.
BRIEF DESCRIPTION OF THE FIGURES
[0017] FIG. 1 is an isometric view, a portion of which is enlarged
and in longitudinal section, of a balloon catheter having a
mounting body in a retracted position;
[0018] FIG. 2 is an even more enlarged view in longitudinal
cross-section of the distal end portion of the catheter of FIG.
1;
[0019] FIG. 3 is similar to FIG. 2 but showing the mounting body
advanced to receive a stent mounted on the balloon;
[0020] FIG. 4 is an enlarged cross-sectional view of the distal end
portion of the catheter of FIG. 1 similar to that of enlarged view
FIG. 3 but showing the balloon in an expanded condition along with
the expanded stent;
[0021] FIG. 5 is a schematic showing of a preferred mounting body
carried by the catheter shaft within the balloon, the body being
spirally cut to improve flexibility;
[0022] FIG. 6 is a schematic showing in cross-section of another
embodiment of the invention with a mounting body positioned to
receive a stent but with a stent not yet mounted;
[0023] FIG. 7 is a schematic showing of another embodiment of the
invention;
[0024] FIG. 8 is a schematic showing of a means for conveniently
crimping the stent on the embodiment shown in FIG. 5;
[0025] FIG. 9 is a schematic showing of yet another embodiment of
the invention;
[0026] FIG. 10 is a showing of another embodiment of a mounting
body according to the invention;
[0027] FIG. 11 is a schematic of an enlargeable mounting body which
is not axially movable;
[0028] FIG. 12 is a schematic of an alternate enlargeable mounting
arrangement which is not axially movable;
[0029] FIGS. 13 and 14 are schematic showings of yet another
embodiment in which the axially movable mounting body is carried
outside the balloon;
[0030] FIGS. 15 and 16 are schematic showings of still yet another
embodiment of the invention, and
[0031] FIGS. 17 and 18 are modified versions of the embodiment
shown in FIG. 11.
[0032] FIGS. 19-21 are modified versions of the securement means of
the present invention.
[0033] FIG. 22 is a side profile section showing a balloon
expandable stent delivery and deployment assembly, with the stent
crimped to delivery diameter onto the balloon, the underlying
inflating component and the catheter and with the inflating tube
component inflated to securement pressure.
[0034] FIG. 23 is a side profile section, similar to FIG. 22, with
the balloon and the stent fully inflated to deployment
diameter.
[0035] FIG. 24 is a side profile section showing an alternative
embodiment of a balloon expandable stent delivery and deployment
assembly, having a tube component formed in several sections.
[0036] FIGS. 25, 26 and 27 are cross-sectional views taken along
lines 4-4, 5-5 and 6-6 of FIG. 24, respectively.
[0037] FIG. 28 is a side profile section showing a balloon
expandable stent delivery and deployment assembly, with the stent
crimped to delivery diameter onto the balloon, the underlying tube
component and the catheter.
[0038] FIG. 29 is a side profile section, similar to FIG. 28, with
the balloon and the stent fully inflated to deployment
diameter.
[0039] FIG. 30 is a perspective view of the corrugated tubing of
the present invention.
[0040] FIGS. 31-33 are side profile sections showing alternative
embodiments of balloon expandable stent delivery and deployment
assemblies, having the tubing component formed in a plurality of
sections.
[0041] FIGS. 34-35 are side profile sections showing alternative
embodiments of the balloon expandable stent delivery and deployment
assemblies, the tube component inflatable to add securement
pressure.
[0042] FIG. 36 is a side profile section showing a balloon
expandable stent delivery and deployment assembly, with the stent
crimped to delivery diameter onto the balloon, the underlying tube
component and the catheter, and also having containment sleeves
covering the ends of the stent.
[0043] FIG. 37 is a side profile section showing a balloon
expandable stent delivery and deployment assembly, with the stent
crimped to delivery diameter onto the balloon, the underlying tube
component and the catheter, and also having a pull-back wire
attached to the tube component.
[0044] FIG. 38 is a longitudinal cross-section of a stent delivery
and deployment assembly of this invention showing a catheter with a
collar mounted at the catheter distal end, an uninflated balloon
mounted on the catheter over the collar, an unexpanded stent
mounted on the balloon abutting the collar and a cup overlying the
stent proximal end portion.
[0045] FIG. 39 is a longitudinal cross-section of another stent
delivery and deployment assembly of this invention showing a
catheter with a collar mounted as a mounting ring at the catheter
distal end, an uninflated balloon mounted on the catheter over the
mounting ring, an unexpanded stent mounted on the balloon overlying
the mounting ring and a cup overlying the stent proximal end
portion; note that the collar is positioned closer to the cup than
in FIG. 38.
[0046] FIG. 40 is a longitudinal profile in partial cross-section
of an assembly similar to that of FIG. 38, with a bulge formed
under the uninflated balloon at the catheter distal end.
[0047] FIG. 41 is a longitudinal profile in partial cross-section
of the assembly shown in FIG. 38 with the balloon inflated and the
stent expanded, showing the cup end portion flared to release the
stent.
[0048] FIG. 42 is a longitudinal profile, similar to FIG. 41,
showing the cup end portion rolled proximally to release the
stent.
[0049] FIG. 43 is a longitudinal profile of yet another stent
delivery and deployment assembly of this invention, with the
balloon mounted on the catheter, which has a collar formed as a
tapered single enlarged piece on the catheter, an unexpanded stent
mounted on the unexpanded balloon abutting the collar and a
cylindrical sleeve overlying the stent proximal end portion.
[0050] FIG. 44 is a longitudinal profile of the assembly of FIG. 43
with the balloon inflated and the stent expanded, showing the
sleeve moved proximally to release the stent.
[0051] FIG. 45 is a side profile of still another stent delivery
and deployment assembly of this invention with the uninflated
balloon mounted on the catheter which has two collars formed
integrally with the catheter, an unexpanded stent mounted on the
balloon abutting the collar and a cylindrical cup overlying the
stent proximal end portion and the underlying collar.
[0052] FIG. 46 is a longitudinal profile of another stent delivery
and deployment assembly of this invention with the uninflated
balloon mounted on the catheter, an unexpanded stent mounted on the
balloon, mounting a cylinder on the catheter and a pair of cups
overlying the stent ends.
[0053] FIG. 47 is an isometric view, a portion of which is enlarged
and in longitudinal section, of a balloon catheter having a stent
fixed to the catheter over the balloon;
[0054] FIG. 48 is an even more enlarged view in longitudinal
cross-section of the distal end portion of the catheter of FIG.
47;
[0055] FIG. 49 is a schematic showing of one form of retraction of
the releasable sleeve upon expansion of the balloon;
[0056] FIG. 50 is a schematic showing of another form of retraction
of the releasable sleeve upon expansion of the balloon;
[0057] FIG. 51 is yet another form of retraction of the releasable
sleeve upon expansion of the balloon;
[0058] FIG. 52 is a schematic showing of yet another form of
retraction of the releasable sleeve upon expansion of the
balloon;
[0059] FIG. 53 is a schematic showing of a modified shape for the
releasable sleeve;
[0060] FIG. 54 is a schematic showing in cross-section of another
embodiment of the invention with a stent not yet mounted;
[0061] FIG. 55 is a schematic showing of another embodiment of the
invention; and
[0062] FIG. 56 is a schematic showing of yet another embodiment of
the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0063] The present invention relates to stent securement devices,
most notably positioned between the balloon and the inner shaft of
the catheter. Individual elements of the below disclosed
embodiments are generally interchangeable if desired. Referring to
FIGS. 1-4 an angioplasty and stent delivery catheter system
generally indicated at 10 includes a balloon catheter 12 having a
balloon 14 on a distal end portion generally indicated at 16. FIG.
1 shows a proximal portion of the catheter at 12a and a distal
portion 12b in enlarged view. FIGS. 2 and 3 show the distal end
portion 16 in an even more enlarged view. The illustrative catheter
12 is of the type known as a rapid exchange or single operator
catheter. However, other types of catheters may be used, such as
over the wire and fixed wire types. The balloon 14 is fixed to the
catheter 12 by standard means. The balloon is shown in its
contracted state in. A stent 18 is fixed about the balloon by
crimping thereto. The stent has a larger expanded diameter which is
obtained when the balloon is expanded in the known manner. In FIGS.
1 and 2 catheter is shown prepared for performing angioplasty and
in FIG. 3 it is prepared for stent implantation.
[0064] In FIGS. 1 and 2, an axially movable mounting body 30 is
shown in a position proximal to the end portion 16 of the catheter
where a stent may be mounted. The catheter includes at its proximal
end a manifold, generally designated 13, as is known in the art.
The manifold includes an inflation port 15 as is known in the art.
A wire 31 is attached to body 30 to enable remote (from the
proximal catheter end) advancement and retraction of it axially on
inner lumen 26 over which it slides. In the retracted position
shown in FIGS. 1 and 2, the catheter has a low profile for
performing angioplasty.
[0065] This position is a retracted position and is selected by
operation of a pull wire 31. The retracted position of the mounting
body may vary. To maximize the low profile of the distal end 16 of
the catheter, the retracted position may be within the outer member
24.
[0066] After such a procedure, the balloon is deflated, the
catheter is withdrawn and the mounting body is advanced by means of
wire 31 to the stent mounting position shown in FIG. 3. A stent 18
may then be fixed about the deflated balloon by crimping it
thereto. The stent has a larger expanded diameter which is obtained
when the balloon is again expanded in the known manner. That is,
the stent is released from the catheter upon expansion of the
balloon as shown in FIG. 4 to be placed in a vessel at the desired
location. When the balloon is then again deflated, removal of the
balloon and catheter may be accomplished, leaving the stent in
place. Exemplary dimensions for the inner 26 is a diameter of 1/2
mm and for body 30 a diameter of 3/4 mm.
[0067] As is known in the art the balloon is either bonded at its
ends by adhesive 20 and 22, respectively to the outer member 24 of
the catheter and to the inner member 26 of the catheter in the
manner as shown, or is made one-piece with the outer member as is
known in the art. The catheter balloon may be inflated by fluid
(gas or liquid) from an inflation port extending from a lumen 28
(seen in FIGS. 2 and 3) contained in the catheter shaft and opening
into the balloon as shown, or by other known arrangements,
depending on the design of the catheter. The details and mechanics
of balloon inflation and specific overall catheter construction
will vary according to the particular design involved in any given
instance, and are known in the art per se. Such details are only
shown schematically herein. All variations are acceptable for use
with this invention.
[0068] Any balloon expandable stent may be used with this
invention. Many are known in the art including plastic and metal
stents. Some are more well known such as the stainless steel stent
shown in U.S. Pat. No. 4,735,665; the wire stent shown in U.S. Pat.
No. 4,950,227; another metal stent shown in European Patent
Application EPO 707 837 A1 and that shown in U.S. Pat. No.
5,445,646, or U.S. Pat. No. 5,242,451. All of these patents are
incorporated herein by reference. Also, shape memory metal stents
may be used. As already indicated the stent of PCT Application 960
3092 A1 is particularly preferred.
[0069] The stent is typically for example about 16 mm long, while
the balloon may be 20 mm long for example. These dimensions,
however, are merely representative for illustrative purposes only
and are not meant to be limiting. The stent is positioned over the
balloon portion of the dilatation catheter and gently crimped onto
the balloon either by hand or with a tool such as a pliers or the
like to be mounted for delivery as shown in FIG. 3. The crimping
may be readily accomplished by the physician during the
procedure.
[0070] In accordance with this invention, mounting body 30, best
seen in FIGS. 2 and 3, is included inside balloon 14 to provide a
cushion and/or substrate of enlarged diameter relative to the stent
to support and hold the stent and secure it during crimping and the
delivery procedure. The mounting body may be axially movable
proximally or distally from the position shown in FIG. 3,
proximally being preferred.
[0071] In the embodiment shown in FIGS. 1-3, mounting body 30 is
cylindrical in form and takes the shape of a sleeve axially and
slidably carried on inner lumen 26, providing an enlarged area or
portion for receiving the balloon and stent when the latter is
crimped to the balloon. Marker band 34 may also be included on
inner 26 as shown. Any radiopaque material such as gold is useful
for this purpose. A stop member 36 of generally conical shape or
any other shape may also be included on the marker band 34 as shown
to provide additional resistance to stent movement during delivery
and to protect the leading edge of the stent during delivery.
Polyethylene or the like is suitable for the stop member. Other
marker arrangements and stop arrangements may be used as well.
[0072] Although, the material of the mounting body may be hard, it
is preferably of any deformable thermoplastic material, preferably
an elastomer material and more preferably of a relatively resilient
elastomer material, e.g., lower durometer silicone. A preferred
deformable thermoplastic material is high density polyethylene
(HDPE). A preferred lower durometer silicone is in the form of
tubing. The deformation of the resilient material of the mounting
body when the stent/balloon is crimped to it causes a radial
outward force on the stent/balloon increasing the friction
therebetween despite any recoil of the stent.
[0073] During stent delivery, the balloon catheter is advanced
through and positioned in a patient's vasculature so that the stent
is adjacent to the portion of the vessel where treatment is to take
place. The balloon is inflated to expand the stent to an enlarged
diameter. When the stent has reached the desired diameter, the
balloon is deflated so that the catheter may be removed leaving the
stent in place.
[0074] Another embodiment of the invention is shown in FIG. 5. In
this embodiment mounting body 30 is a spiral cut elastomer or other
suitable material, such as a rigid or flexible plastic, to provide
separation for flexibility in that portion of the catheter,
allowing more easy movement or tracking around bends. The spiral
cut may be only partly through the mounting body or may be all the
way through as shown in FIG. 5. Also, while stop member 36 is shown
at the distal end portion of the catheter in this embodiment, no
stop member may be used.
[0075] Another similar version is shown in FIG. 6 which includes a
cylindrical mounting body 30 made up of a plurality of separate
adjacent rings 30a held together by wire 31 which extends
therethrough as shown with stops 29 to secure the rings together.
Rings 30a may be individual bodies carried on the sheath or bodies
cut from a cylinder to partially separate them or fully separate
them. Suitable arrangements may be made to wire 31 at each end of
the body 30 to hold the rings together, as shown.
[0076] The embodiment shown in FIG. 7 includes another feature
based on the geometry of the mounting body for further securing the
stent upon crimping. This feature is referred to herein as
"interlocking". That is, the stent may be interlocked to the mount
so that the stent cannot slide proximally or distally on the
balloon unless it is deformed, such as by expansion. This can be
seen by perusing the structure shown in FIG. 7 which includes the
inner 26 having a two-piece mounting body made up of spaced
mounting bodies 30a and 30b. These bodies are connected to each
other by connection means 33 which may be a separate or integral
cylindrical body of lesser diameter or may be one or two or more
relatively rigid wire members as shown. The spacing between bodies
30a and 30b allows portions of the stent 18 and balloon 14 to be
depressed or inserted between the bodies upon crimping of the stent
thus forming an interlock against sliding of the stent axially or
longitudinally before the stent is released.
[0077] The interlock formation or crimping is readily accomplished
by any suitable means such as a two-piece die 40 shown in FIG. 8 or
the like.
[0078] FIG. 9 demonstrates that more than a two-piece mounting body
arrangement may be used if desired. In this embodiment, the
mounting body is comprised of three spaced interconnected bodies
30a, 30b and 30c on the inner 26. Preferably in the embodiments of
FIGS. 7 and 9, the mounting bodies will be ring-like in shape or
cylindrical in shape although other configurations will be readily
apparent to those familiar with this art.
[0079] Referring now to FIG. 10, another embodiment of a movable
mounting body 30 is shown in the form of a rigid coil of plastic,
metal or the like having a control wire 31, preferably integral
therewith. When in the metal form, the coil may be coated with a
polymer such as polyethylene or PTFE or enclosed in a polymeric
sheath of similar material. The coil may be slidably received on
the inner 26 similar in arrangement to that shown in the preceding
Figures.
[0080] As already indicated, an alternate arrangement may be used
in which the mounting body, instead of being movable, is designed
to be enlargeable and reducible or collapsible, while remaining in
a fixed position in the stent mounting area of the catheter. FIGS.
11 and 12 are directed to such an arrangement.
[0081] In FIG. 11, an inner balloon 50 of smaller diameter than
outer balloon 14 is mounted on the inner 26. Balloon 50 may have a
separate inflation conduit 52 inside inner 26, preferably including
a valving arrangement 54. Valve 54 may be a one-way valve allowing
only inflation of balloon 50 if desired. However, inner 26 may
serve as the inflation conduit as well. In addition to fully
inflating the balloon, inner balloon 50 may also be partially
inflated.
[0082] FIG. 19 shows a modification to FIG. 11 in which two inner
balloons 50a and 50b are included. FIG. 20 shows a modification in
which two inflation valves 54a and 54b are included.
[0083] FIG. 21 shows a full arrangement of inner balloon 50 in
which a syringe 120 is inserted into the distal end of the liner 26
of the catheter. The syringe has at its ends blocks 122 and 124 to
enable local pressurization of inner 26 to inflate balloon 50.
[0084] FIGS. 17 and 18 show an inner balloon 50 similar to the
arrangement of FIG. 11 but the balloon 50 in FIG. 17 has a narrow
center portion and wide ends to provide a mounting shape similar to
that of FIG. 7. In FIG. 17, balloon 50 is inflated and balloon 14
is partially inflated. In FIG. 18, balloon 50 is inflated and
balloon 14 is uninflated ready for stent loading. Balloon material
is preferably a polyethylene or urethane elastomer such as Tecoflex
or Tecothane from Thermedics.
[0085] Referring to FIG. 12, an alternate embodiment is shown in
which the proximal portion of the inner 26 is axially movable while
the distal portion 26b is fixed with respect to the catheter. In
between portion 26a and portion 26b is a coil spring 60 inside a
flexible sheath 62 of PTFE or the like. Portion 26b of the inner is
attached to balloon 14 at the very distal end portion of the
catheter. Portion 26a is movable axially within the outer 22. Thus,
if 26a is pushed in the distal direction and held to compress coil
60, the coil will enlarge in diameter to provide an enlarged
mounting area for a stent. Twisting the inner to twist the coil
will enhance enlargement. Alternatively, coil spring 60 may be
replaced by a braided element.
[0086] Also, by providing different pitch over the length of the
coil it can be made to enlarge more in some regions than in others.
For example, if the coil windings are closer together in the center
portions than in the end portions, when the coil undergoes
compressing, the two end portions will enlarge in diameter more
than the center portion to provide a mount similar to that of FIG.
7.
[0087] Referring now to FIGS. 13 and 14, another embodiment is
shown which is alternative to the earlier described embodiments
which are inside the balloon on the catheter. In this embodiment a
sheath 80 is carried on the outside of the catheter. Sheath 80 is
elastomeric and is axially movable from a stent mounting position
as shown in FIG. 14 to a position remote from the stent mounting
position, such as the retracted position as shown in FIG. 13. In
the position shown in FIG. 13, balloon 14 may be inflated and
deflated. In the position shown in FIG. 14, balloon 14 will be
deflated for low profile. Sheath 80 when over the balloon as in
FIG. 14 acts to increase the profile of the catheter to facilitate
crimping a stent thereto during deployment of the stent, sheath 80
will expand with balloon 14 to facilitate inflation and during
deflation the elastomer sheath will return to its original
dimension. An elastomer material which is presently preferred is
Tecothane, a trade name for a thermoplastic polyurethane available
from Thermedics, Inc., of Woburn, Mass. It may be about 0.003
inches thick, for example.
[0088] With respect to FIGS. 15 and 16, a further embodiment of the
invention is shown in which inner 26 carries a mounting body 30,
the distal end 100 of which is secured or fixably attached to inner
26, as by any suitable adhesive. The remainder of body 30 is
slidable over inner 26 as by the application of compression in the
distal direction at the proximal end 102. This may be accomplished
by push wire 104 which extends to the proximal end of the catheter
for remote manipulation as is known in the art.
[0089] Mounting body 30 is accordion folded with more widely spaced
folds at the end portions 106, than at the central portion 108.
Thus, as can be seen in FIG. 15, a relatively low profile is
provided without compression for normal angioplasty use. When a
stent is to be mounted (not shown), compression by means of push
wire 104 will result in a configuration of enlarged diameter of
body 30 as shown in FIG. 16 to provide a mount similar to that of
FIG. 7 in general configuration. If the spring is uniform over the
body, it sill enlarge uniformly, similar to the inner balloon of
FIG. 11. The Figures are schematic in form but the concept can be
readily appreciated.
[0090] As an alternative to a folded construction, the body may be
of braided construction to achieve the same operation.
[0091] Also, this form of body 30 may be inserted into a two piece
inner 26 similar to the arrangement shown in FIG. 12. In all of
these arrangements, the accordion folded body material may be of
any suitable polymer, such as polyethylene. For example, tubing
having a wall thickness of about 0.002 inches may be used. The
accordion folds or pleats may be readily formed in such tubing by
means of a pressure mold containing spaced blades placed in a
heated chamber.
[0092] FIGS. 22-27 show embodiments wherein the inner securement
device comprises an inner balloon beneath the outer catheter
balloon, similar to above. FIGS. 22 and 23 illustrate a side
profile section showing an inflation expandable stent delivery and
deployment assembly generally designated 110. Assembly 110 includes
a catheter comprised of inner shafts 112 and 113 and an outer shaft
115 of the coaxial type, an inflation expandable balloon 114, an
inflation tube component 116 such as an inner balloon and inflation
expandable stent 118. Any conventional type of catheter may be
used, such as a catheter of the type generally used for PTA or PTCA
angioplasty procedures, for prostate therapy, and TTS endoscopic
catheters for gastrointestinal use. However, coaxial types as shown
are most preferred. The particular catheter 112 shown is formed of
a biocompatible and hydrophilic compatible material, such as a
lubricous polyimide or polyethylene. Other suitable materials for
the catheter 112 include nylons, urethanes, and polypropylene
materials compatible with coatings such as silicone and/or
hydrophilic coatings. In addition to hydrophilic compatible
materials, any biocompatible material may be used. For example,
polyethylene or polypropylene can be coated with a hydrophilic
material to render them hydrophilic compatible suitable catheters
for use according to the present invention include a number of
catheters available from SciMed Life Systems, Inc., Maple Grove,
Minn., the assignee of the present invention, such as BANDI.TM.,
COBRA.TM., VIVA.TM., and VIVA PRIMO.TM. catheters.
[0093] Inflatable tube component 116 is fixed at its distal and
proximal end to inner shaft 112 and at its proximal end to inner
shaft 113 at a position to be encompassed within the distal and
proximal ends of the outer balloon 114. According to art-recognized
convention, the length L-B of the balloon 114 is defined as the
length of the body portion of the balloon 114, excluding the
terminal cone sections 120. As seen in FIG. 23, the body portion of
the balloon 114 is generally cylindrical when in its deployed or
inflated condition. Tube component 116 is illustrated as having
terminal sections 122 which are more relatively vertical than the
cone sections 120 illustrated for the balloon 114. However, it is
to be understood that, according to the present invention, either
of the terminal sections 120, 122 may be relatively cone shaped,
relatively vertical or of any other configuration known to those of
skill in this art. A preferred length L-T of the tube component 116
is illustrated in FIGS. 22 and 23 as substantially equal to the
length L-B of balloon 114, and substantially equal to the length
L-S of stent 112. However, according to the present invention,
stent 112 should be supported by the underlying tube component 116
for a length sufficient to permit accomplishment of the stated
purpose of the tube component 116, when inflated, to
provide-securement pressure for stent 112 to maintain stent 112 in
position with assembly 110 during delivery. It is also within the
present invention for tube component 116 to be slightly shorter
than stent 112, for example, the distal end 119 of stent 112 may
extend distally beyond the distal end 121 of tube component 116
(not shown), so that the distal end 119 of stent 121 can be crimped
over the distal end 121 of tube component 116 to prevent the distal
end 119 of stent 112 from catching and tending to further open as
it is maneuvered within a body vessel. As has been explained above,
tube component 116 is designed and constructed to be inflatable to
no more than is necessary to compensate for recoil crimping of
stent 112 and to closely accommodate (or even slightly over-stress)
the delivery diameter of stent 112, taking into consideration the
thickness of the intervening uninflated balloon 114. Tube component
116 is inflated through the opening(s) 117 of inner shaft 112.
Typically, tube component 116 will have a wall thickness of about
0.0002-0.0007 inch and will be inflatable to no more than about
0.035.-0.045 inches.
[0094] Inflating tube component 116 may be formed of either
compliant or non-compliant balloon materials. Compliant materials
include low pressure, relatively soft or flexible polymeric
materials, such as thermoplastic polymers, thermoplastic
elastomers, polyethylene (high density, low density, intermediate
density, linear low density), various co-polymers and blends of
polyethylene, ionomers, polyesters, polyurethanes, polycarbonates,
polyamides, poly-vinyl chloride, acrylonitrile-butadiene-styrene
copolymers, polyether-polyester copolymers, and polyetherpolyamide
copolymers. Suitable materials include a copolymer polyolefin
material available from E.I. DuPont de Nemours and Co. (Wilmington,
Del.), under the trade name Surlyn.TM. Ionomer and a polyether
block amide available under the trade name PEBAX.TM.. Non-compliant
materials include relatively rigid of stiff high pressure polymeric
materials, such as thermoplastic polymers and thermoset polymeric
materials, poly(ethylene terephthalate) (commonly referred to as
PET), polyimide, thermoplastic polyimide, polyamides, polyesters,
polycarbonates, polyphenylene sulfides, polypropylene and rigid
polyurethanes.
[0095] A balloon 114 for use according to the present invention may
be any conventional balloon for catheter delivery, such as a
balloon of the type generally used for PTA and PTCA procedures.
Typically, balloon 114 is fixed at its distal end to inner shaft
112 near the catheter-distal end and at its proximal end to outer
shaft 115. Balloon 114 is larger in diameter than tube component
116, because balloon 114 must be able to expand to a larger
diameter than tube component 116. Balloon 114 is inflatable through
an inflation conduit 123, i.e., the space between coaxial inner
shaft 113 and outer shaft 115 of the catheter. The distal and
proximal ends of balloon 114 are shown in FIGS. 22 and 23
positioned exterior to the distal and proximal ends of tube
component 116, respectively, and of a length L-B generally equal to
the length L-T of the tube component 116. To be compatible with
tube component 116 illustrated in FIGS. 22 and 23 and described
above, balloon 114 is inflatable at deployment to about the
diameter of the body vessel in which the stent 118 is to be
deployed. Balloon 114 may be formed of a compliant or non-compliant
material, of the types of compliant materials described herein
above, such as polyethylene or any standard balloon material.
Balloon 114 typically has a wall thickness of about 0.0007-0.004
inch for example.
[0096] A stent for use according to the present invention may be
any conventional type of balloon expandable stent, including stents
of the type used for PTA and PTCA angioplasty procedures, for
prostate therapy, and TTS endoscopic catheters for gastrointestinal
use. Suitable stent material is biocompatible stainless steel in
the form of sheet metal, tube component wire or Nitinol. A
preferred stent is described in PCT Application No. 960 3072 A1,
published 8 Feb. 1996, the content of which is incorporated herein
by reference. All such stents are well known in this art generally
and additional examples are described in U.S. Pat. No. 5,507,768 to
Lau et al.; in U.S. Pat. No. 5,458,615 to Klemm et al; in U.S. Pat.
No. 5,226,889 to Sheiban; in U.S. Pat. No. 4,875,480 to Imbert; in
U.S. Pat. No. 4,848,343 to Wallsten et al., and in U.S. Pat. No.
4,733,665 to Palmaz. Stent 18 as shown in FIGS. 22 and 23 is
positioned on balloon 114, the underlying inflatable tube component
116 and the distal end of the catheter. The length L-S of stent 118
is shown as essentially equal or slightly smaller than the length
L-T of tube component 116 and is positioned on assembly 110 to be
co-extensive with tube component 116. In this position, stent 118
is shown in FIG. 22 crimped to its delivery diameter D1, which is
about 0.035-0.045 inch for example.
[0097] As discussed above, despite the most careful and firm
crimping of stent 118 to closely conform to the overall profile of
the catheter unexpanded balloon 114 and underlying inflatable tube
component 116, there is a certain amount of "recoil" of stent 118
or a tendency of stent 118 to slightly open from a desired
hypothetical minimum crimped diameter. The actual minimum diameter
achievable for fully crimped stent 118 on assembly 110 is referred
to as the stent 118 delivery diameter D1. This tendency of stent
118 to open or recoil slightly when crimped on assembly 10 has been
characterized as "recoil crimping". In FIG. 22, inflatable tube
component 116 is shown inflated to a diameter which is generally
sufficient to compensate for any slack or looseness between crimped
stent 118 and the overall profile of the catheter, the unexpanded
balloon 114 and the underlying inflatable tube component 116 due to
recoil crimping.
[0098] FIG. 23 illustrates a side profile section showing a stent
delivery and deployment assembly 110 of this invention with balloon
114 fluid inflated to its fully expanded position. As a result of
the fluid inflation of the balloon 114, stent 118 has also been
fully expanded to its deployment diameter D2 in which it can be
deployed against the walls of a body vessel in which it is
situated.
[0099] Tube component 116 may have a shape other than the
cylindrical shape described and illustrated with regard to the
embodiment shown in FIGS. 22 and 23. Further, the tube component
may be comprised of more than one separately inflatable pouch. For
example, as illustrated with regard to FIG. 24, the tube component
of an alternative stent delivery and deployment assembly generally
designated 130 can be comprised of three separately inflatable
pouches 136, 138, 140. The pouches 136, 138, 140 are each
separately inflatable through their respective inflation conduits
137, 139 141, and each of the pouches 136, 138, 140 can be
inflatable to a different extent. The conduits are formed in the
wall of shaft 132 as can be seen in FIGS. 25-27. The stent delivery
and deployment assembly 130 of FIG. 24 is also comprised of a
catheter having inner shaft 132 and outer shaft 135, a balloon 134,
with its balloon inflation conduit 139 and the balloon terminal
cone sections 144, and a stent 142. As has been explained above
with reference to FIGS. 22 and 23, stent 142 is crimped to closely
conform to the overall profile of the catheter the unexpanded
balloon 134 and the underlying inflatable pouches 136, 138, 140.
Even with the most careful and firm crimping, there is a certain
amount of "recoil" of the stent 142 or a tendency of stent 142 to
slightly open from a desired hypothetical minimum diameter. In FIG.
24, the first 136 and third 140 pouches are inflated to a slightly
larger size than the second pouch 138. As discussed above, the
inflation of the pouches 136, 138, 140 to this configuration is
generally sufficient to compensate for any slack or looseness
between the crimped stent 142 and the overall profile of the
catheter, the unexpanded balloon 134 and the underlying inflatable
pouches 136, 138, 140 due to recoil crimping. Once pouches 136, 138
140 have been inflated to the configuration shown in FIG. 24, stent
142 is firmly secured against axial movement With regard to
assembly 130. The distal 146 and proximal 148 ends of stent 142 are
protected from any possible unwanted contact with vessel walls
during maneuvering, which helps to protect the vessel walls from
abrasion and also helps to protect the ends 146, 148 of stent 142
from distortion. Additionally, stent 142 may be of a length such
that it fits over pouch 140 and pouch 136 as well as over pouch
138.
[0100] The method of using the stent delivery and deployment
assembly 110 of this invention, as shown in FIGS. 22 and 23, is
described as follows. The assembly 110 is constructed as described
above. Stent 118 is compressed or crimped onto balloon 114,
inflatable tube component 116 and the catheter to a delivery
diameter D1. This crimping can be done manually or with the aid of
tooling specially designed for the purpose either by the physician
or the manufacturer. In the crimped position, stent we closely
conforms to the overall profile of balloon 114, inflatable tube
component 116 and the catheter except for the slight slack or
looseness due to recoil crimping. Tube component 116 is fluid
inflated to the extent necessary to compensate for this slack or
looseness due to recoil crimping. The pressure of force required to
inflate tube component 116 to this extent is also referred to as
securement pressure, i.e., the force or pressure needed to secure
stent 112 in this position. It is to be noted that, since tube
component 116 is designed and constructed to be capable of fully
expanding to no more than the size necessary to compensate for
recoil crimping, there is no possibility of stent 112 expanding or
beginning to open to a larger diameter. Thus, there is no hazard of
stent 112 moving out of its position on the catheter during
delivery or of becoming separated from the catheter within a body
vessel. The catheter distal end is delivered by standard techniques
to the deployment site within the body vessel of interest. At this
point, stent 112 is positioned as required by the physician and
balloon 114 is fluid inflated by standard technique to expand stent
121 to its deployment diameter D2. During this expansion, stent 112
is expanded to fill the body vessel. Following deployment of stent
112, balloon 114 and optionally, tube component 116 are deflated
and the assembly 110 is retracted proximally and withdrawn from the
body. If required by the procedure, the site of entry to the body
is appropriately closed.
[0101] The method of using the stent delivery and deployment
assembly 130 of this invention, as shown in FIG. 24, is similarly
described. The assembly 130 is constructed as described above.
Stent 142 is compressed or crimped to closely conform to the
overall profile of balloon 134, inflatable pouches 136, 138, 140
and the catheter except for the slight slack or looseness due to
recoil crimping. Pouches 136, 138, 140 are each fluid inflated to
the profile shown in FIG. 24 through separate fluid inflation
conduits (not shown) to securement pressure to compensate for this
slack or looseness and to secure stent 142 in this position. The
overall configuration of pouches 136, 138 140 further serves to
position stent 142 against axial dislocation during delivery. The
catheter is delivered by standard techniques to the deployment site
within the body vessel of interest. At this point, stent 142 is
positioned as required by the physician and balloon 134 is fluid
inflated by standard technique to expand and deploy stent 142.
Following deployment of stent 142, balloon 134 and, optionally,
pouches 136, 138 140 are deflated and the assembly 130 is retracted
proximally and withdrawn form the body. If required by the
procedure, the site of entry to the body is appropriately
closed.
[0102] The inflation tube component provided by this invention
maximizes stent securement force by optimizing the frictional force
between the inflating tube component, the balloon wall and the
internal diameter of the stent in its reduced crimped delivery
diameter. The inflation tube component is more flexible than a
solid sheath under the expandable balloon, and thus the entire
assembly has greater flexibility. This invention has particular
advantages for assemblies in which the stent is provided for use as
pre-crimped to the balloon and underlying catheter, by increasing
the shelf life of the pre-crimped assembly. The features and
principles described for this invention are suitable for use with
fixed wire, over-the-wire and single operator exchange
assemblies.
[0103] FIGS. 28-37 disclose still further embodiments of the
securement device. FIGS. 28 and 29 illustrate a side profile
section showing an inflation expandable stent delivery and
deployment assembly, generally designated 210. Assembly 210
includes a catheter comprised of inner shaft 212 and outer shaft
213 of the coaxial type and an optional retractable delivery shaft
211 (typically called a guide catheter, shown retracted in FIG. 29,
an inflation expandable balloon 214, a corrugated/ribbed stent
securement device 216, optional marker bands 217 and an inflation
expandable stent 218. Any conventional type of catheter may be
used, such as a catheter of the type generally used for PTA or PTCA
angioplasty procedures, for prostate therapy, and TTS endoscopic
catheters for gastrointestinal use. However, coaxial types as show
are most preferred. The particular catheters 212 and 213 shown are
formed of a biocompatible and hydrophilic compatible material, such
as a lubricous polyimide or poly ethylene. Other suitable materials
for the catheters 212 and 213 include nylons, urethanes, and
polypropylene materials compatible with coatings such as silicone
and/or hydrophilic coatings. In addition to hydrophilic compatible
materials, any biocompatible material may be used. For example,
polyethylene or polypropylene can be coated with a hydrophilic
material to render them hydrophilic compatible. Suitable catheters
for use according to the present invention include a number of
catheters available from SciMed Life Systems, Inc., Maple Grove,
Minn., the assignee of the present invention, such as BANDIT.TM.,
COBRA.TM., VIVA.TM., VIVA PRIMO.TM., MAXXUM.TM., MAXXUM ENERGY.TM.
and RANGER.TM. catheters.
[0104] Securement device 216 is fixed at its distal and/or proximal
ends to inner shaft 212 at a position to be encompassed within the
distal and proximal ends of the outer balloon 214. According to
art-recognized convention, the length L-B of the balloon 214 is
defined as the length of the body portion of the balloon 214,
excluding the terminal cone sections 220. As seen in FIG. 29, the
body portion of the balloon 214 is generally cylindrical when in
its deployed or inflated condition. Securement device/tube
component 16 is illustrated as having terminal sections 221,222. It
is to be understood that, according to the present invention,
either of the terminal sections 220, 222 may be relatively cone
shaped, relatively vertical, relatively flat or of any other
configuration known to those of skill in this art. A preferred
length L-T of the tubing 216 is illustrated in FIGS. 28 and 29 as
substantially equal to the length L-B of balloon 214, and
substantially equal to the length L-S of stent 218. However,
according to the present invention, stent 218 should be supported
by the underlying tube component 216 for a length sufficient to
permit accomplishment of the stated purpose of the tube component
216, to provide a superior securement and protective surface for
stent 218 to maintain stent 218 in position with assembly 210 and
to protect the balloon material during loading/crimping. It is also
within the present invention for the tube component 216 to be
slightly shorter than stent 218, for example, the distal end 219 of
stent 218 may extend distally beyond the distal end 21 of tube
component 216 (not shown), so that the distal end 19 of stent 18
can be crimped over the distal end 221 of tube component 216 to
prevent the distal end 221 of stent 218 from catching and tending
to snag or further open as it is maneuvered within a body vessel.
As has been explained above, tube component 216 is designed and
constricted to have enough flexibility and have enough volume to no
more than is necessary to compensate for recoil crimping of stent
218 and to closely accommodate (or even slightly over stress) the
delivery diameter of stent 218, taking into consideration the
thickness of the intervening uninflated balloon 214. Typically, the
tube component 216 will have a consistent frequency of ribs, but
may also vary by having intermittent groups of ribs along the
tubing.
[0105] The balloon and the crimped stent slightly conform to the
undulations of the tube component for greater securement, but this
conformation is not illustrated.
[0106] Tube component 216 may be formed from a thermoplastic
material, preferably a low modulus polymer, such as Surlyn.TM.,
Pebax and urethane. The device such as polypropylene, low density
polyethylene (LDPE), high density polyethylene (HDPE), ethylene
vinyl acetate (EVA), nylon, polyester and polyethylene
terephthalate ("PET"), may be prepared through free blowing in a
mold or inside a coil. Tubing is extruded with relatively thin
walls and then free-blown in a mold, coil or other fixture to form
the ribs/corrugation.
[0107] A balloon 214 for use according to the present invention may
be any conventional balloon for catheter delivery, such as a
balloon of the type generally used for PTA and PTCA procedures.
Typically, balloon 214 is fixed at its distal end to inner shaft
212 near the catheter distal end and at its proximal end to inner
shaft 212, near the distal end of the outer shaft 213. Balloon 214
is inflatable through an inflation conduit 223, i.e., the space
between coaxial inner shaft 213 and outer shaft 213 of the
catheter. The distal and proximal ends of balloon 214 are shown in
FIGS. 28 and 29 positioned exterior to the distal and proximal ends
of tube component 216, respectively, and of a length L-B generally
equal to the length L-T of the tube component 216. To be compatible
with the tube component 216 illustrated in FIGS. 28 and 29 and
described above, balloon 214 is inflatable at deployment to about
the diameter of the body vessel in which the stent 218 is to be
deployed. Balloon 214 may be formed of a compliant or non-compliant
material, such as polyethylene or any standard balloon material.
Compliant materials include low pressure, relatively soft or
flexible polymeric materials, such as thermoplastic polymers,
thermoplastic elastomers, polyethylene (high density, low density,
intermediate density, linear low density), various co-polymers and
blends of polyethylene, ionomers, polyesters, polyurethanes,
polycarbonates, polyamides, poly-vinyl chloride,
acrylonitrile-butadiene-styrene copolymers, polyether-polyester,
copolymers, and polyetherpolyamide copolymers. Suitable materials
include a copolymer polyolefin material available from E.I. DuPont
de Nemours and Co. (Wilmington, Del.), under the trade name
Surlyn.TM. Ionomer and a polyether block amide available under the
trade name PEBAX.TM.. Non-compliant materials include relatively
rigid stiff high pressure polymeric materials, such as
thermoplastic polymers and thermoset polymeric materials,
poly(ethylene terephthalate) (commonly referred to as PET),
polyimide, thermoplastic polyimide, polyamides, polyesters,
polycarbonates, polyphenylene sulfides, polypropylene and rigid
polyurethanes, or combinations thereof The balloon 214 typically
has a wall thickness of about 0.0007-0.004 inch for example.
[0108] A stent for use according to the present invention may be
any conventional type of balloon expandable stent, including stents
of the type used for PTA and PTCA angioplasty procedures, for
prostate therapy, and TTS endoscopic catheters for gastrointestinal
use. Suitable stent material is biocompatible stainless steel in
the form of sheet metal, tube component wire or Nitinol. A
preferred stent is described in PCT Application No. 960 3072 A1,
published 8 Feb. 1996, the content of which is incorporated herein
by reference. All such stents are well known in this art generally
and additional examples are described in U.S. Pat. No. 5,507,768 to
Lau et al.; in U.S. Pat. No. 5,458,615 to Klemm et al.; in U.S.
Pat. No. 5,226,899 to Sheiban; in U.S. Pat. No. 4,875,480 to
Imbert; in U.S. Pat. No. 4,848,343 to Wallsten et al.; and in U.S.
Pat. No. 4,733,665 to Palmaz. Stent 218 as shown in FIGS. 28 and 29
is positioned on balloon 214, which is over the underlying tube
component 216, at the distal end of the catheter. The length L-S of
stent 218 is shown as essentially equal or slightly smaller than
the length L-T of tube component 216 and is positioned on assembly
210 to be coextensive with tube component 216. In this position,
stent 218 is shown in FIG. 28 crimped to its delivery diameter D1,
which is about 0.035-0.45 inch for example.
[0109] As discussed above, despite the most careful and firm
crimping of stent 218 to closely conform to the overall profile of
the catheter unexpanded balloon 214 and underlying tube component
216, there is a certain amount of "recoil" of stent 218 or a
tendency of stent 218 to slightly open from a desired hypothetical
minimum crimped diameter. The actual minimum diameter achievable
for fully crimped stent 218 on assembly 210 is referred to as stent
218 delivery diameter D1. This tendency of stent 218 to open or
recoil slightly when crimped on assembly 210 has been characterized
as "recoil crimping". In FIG. 28, tube component 216 is shown
inflated to a diameter which is generally sufficient to compensate
for any slack or looseness between crimped stent 218 and the
overall profile of the catheter, the unexpanded balloon 214 and the
underlying tube component 216 due to recoil crimping.
[0110] FIG. 29 illustrates a side profile section showing a stent
delivery and deployment assembly 210 of this invention with balloon
214 fluid inflated to its fully expanded position. As a result of
the fluid inflation of the balloon 214, stent 218 has also been
fully expanded to its deployment diameter D2 in which it can be
deployed against the walls of a body vessel in which it is
situated.
[0111] FIG. 30 illustrates the preferred configuration of the tube
component 216. The tube component has a plurality of ribs 230 and
is configured in a corrugated or accordion fashion. The ends of the
tube component 216, 222 and 221, are substantially rib-free so as
to provide a flat surface to receive an adhesive and thereby bond
to the inner shaft 212. Preferable adhesives include cyanoacrylates
such as Loctite 4061/4011 or urethanes, such as H. B. Fuller
3507/3506. The tube component may also be heat bonded to the inner
shaft. The ribs may vary in frequency and spacing.
[0112] Tube component 216 may have different configurations in
other embodiments, as shown in FIGS. 31-33. The tube component 216
may be comprised of more that one piece of corrugated tubing (FIG.
31), a smaller single piece (FIG. 32) or one single piece of tubing
sectioned into a plurality of ribbed sections, wherein the tubing
is adhered to the inner shaft 212 in more than two locations (FIG.
33).
[0113] FIG. 31 shows two pieces of tubing component 216a, 216b.
Both pieces are adhered to inner shaft 212 at adhesion points 232.
FIG. 32 discloses an embodiment which comprises one smaller piece
of tube component 216 which is adhered to inner shaft 212 at
adhesion points 232. FIG. 33 discloses an embodiment which
comprises one tube component 216 which has interrupted ribbed
sections 234 adhered to the inner shaft 212.
[0114] FIGS. 34 and 35 illustrate an alternative embodiment in
which the tubing component is inflatable to increase the securement
pressure on the inside of balloon 214 when the stent is crimped
onto the balloon so as to negated additional recoiling. The full
expansion of the tube component 216 should only be slightly greater
than the diameter of the inside of the balloon 214 when the stent
218 is fully crimped onto the balloon 214.
[0115] In FIG. 34, the inflating fluid comes through the guide wire
lumen 212 under pressure from the proximal end or the distal end of
the guide wire lumen 212, preferably via a syringe, and fills the
tubing component 216 through a one-way valve 247 (preferably
resisting up to about 4 atm) in the inner catheter 212.
[0116] In FIG. 35, the tubing component 216 is inflated via an
additional lumen 242 which extends from the proximal end of the
catheter along the guide wire lumen 240, much the same as any
inflating lumen incorporated to inflate a balloon.
[0117] In an alternative embodiment, as shown in FIG. 36, socks or
sleeves 251 may be incorporated to stretch over the ends of the
stent to prevent snagging and to secure the stent onto the balloon.
Such sleeves are demonstrated in U.S. application Ser. Nos.
08/702,149, filed Aug. 23, 1996, and Ser. No. 08/701,979, filed
Aug. 23, 1996, which are incorporated in their entirety herein by
reference.
[0118] In still another embodiment, as shown in FIG. 37, the tubing
component 216 is slidable axially along the inner shaft 212 and is
connected to a retracting wire 250 such that the tubing component
may be retracted into the outer shaft 213 after the balloon has
been inflated to reduce the profile of the balloon 214 when the
catheter is removed. The tubing component, since it is not adhered
to the inner shaft 212 in this embodiment, should fit tightly
enough on the inner shaft to stay in place, but not too tightly so
that it may be retracted by pulling on the retracting wire 250.
[0119] The method of using the stent delivery and deployment
assembly 210 of this invention, as shown in FIGS. 1 and 2, is
described as follows. The assembly 210 is constructed as described
above. Stent 218 is compressed or crimped onto balloon 214, tube
component 216 and the catheter to a delivery diameter D1. This
crimping can be done manually or with the aid of tooling
specifically designed for the purpose either by the physician or
the manufacturer. In the crimped position, stent 218 closely
conforms to the overall profile of balloon 214, tube component 216
and the catheter except for the slight slack or looseness due to
recoil crimping. Tube component 216 is flexible enough to slightly
collapse during crimping and rebound to the extent necessary to
compensate for the slack or looseness due to recoil crimping, thus
securing the stent. As a result, the stent does not move out of its
position on the catheter during delivery or become separated from
the catheter within a body vessel. The catheter distal end is
delivered by standard techniques to the deployment site within the
body vessel of interest. At this point, stent 218 is positioned as
required by the physician and balloon 214 is fluid inflated by
standard technique to expand stent 218 to its deployment diameter
D2. During this expansion, stent 218 is expanded to fill the body
vessel. Following deployment of stent 218, balloon 214 is deflated
and the assembly is retracted proximally and withdrawn from the
body. If required by the procedure, the site of entry to the body
is appropriately closed.
[0120] The tube component provided by this invention increases
stent securement force by increasing the frictional force between
the tube component, the balloon wall and the internal diameter of
the stent in its reduced crimped delivery diameter. The tube
component is more flexible than a solid sheath under the expandable
balloon, and thus the entire assembly has greater flexibility. This
invention has particular advantages for assemblies in which the
stent is provided for use as pre-crimped to the balloon and
underlying catheter, by increasing the shelf life of the
pre-crimped assembly. The tube component also protects the balloon
material during crimping by acting as a buffer between the balloon
material and whatever may be mounted on the inner shaft, such as
marker bands 217. The features and principles described for this
invention are suitable for use with fixed wire, over-the-wire and
single operator exchange assemblies.
[0121] FIGS. 38-46 disclose alternative embodiments of the
securement device. FIG. 38 shows a stent delivery and deployment
assembly generally designated 310. A catheter 312 has a collar 314
coaxially mounted at the catheter distal end portion 316. An
uninflated balloon 318 is coaxially mounted on catheter 312 over
collar 314. An unexpanded stent 320 is coaxially mounted on the
balloon 318 abutting but not overlying collar 314. A cup 322
coaxially overlies the stent proximal end portion 324. Cup 322 may
be elastomeric or rigid, preferably elastomeric. Cup 322 is
over-expanded over the stent 320, so that recoil of the cup 322 is
sufficient to secure stent 320 in place and prevent it from being
pulled off of the assembly 310 distally or proximally as assembly
310 is delivered to a deployment site in a body vessel. Cup 322
also protects the proximal end of stent 324 from inadvertently
catching on anatomical structures or other things during
maneuvering within the body or during loading and other handling.
The ends of the stent may axially protrude and should be protected
during maneuvering of stent 320 to keep stent 20 on assembly 310 in
its contracted configuration and to maintain the structural
integrity of stent 320. Collar 314 abuts the stent distal end 326
without underlying stent 320. The position of cup 322 overlying
stent 320 and containing stent 320 against collar 314 increases the
securement force maintaining stent 320 in its axial and radial
position on catheter 12. FIG. 40 is similar to FIG. 38, showing a
bulge 28 beneath the uninflated balloon 318 at catheter distal end
316.
[0122] Any of the various types of known stents may be used in the
delivery system of this invention, even self-expanding stents which
are partly balloon-expandable may be used, the balloon initiating
release of the stent and/or finally seating the stent after
self-expansion. However, ordinary balloon expandable stents are
preferred and aforenoted.
[0123] FIG. 39 shows another stent delivery and deployment assembly
generally designated 330. A catheter 332 has a collar coaxially
mounted as a mounting ring 334 on the catheter. An uninflated
balloon 338 is coaxially mounted on catheter 332 over mounting ring
334. An unexpanded stent 340 is coaxially mounted on balloon 338
overlying the mounting ring 34. A cup 342 overlies the stent
proximal end portion 344 to secure the stent 340 in place and
prevent it from being pulled off of assembly 330 distally or
proximally, as assembly 330 is delivered to a deployment site in a
body vessel. Cup 342 also protects the proximal end of stent 40
from inadvertently catching on anatomical structures during
maneuvering within the body. The position of cup 342 overlying
stent 340 together with the closer positioning of mounting ring 334
as compared to FIG. 38 increases the securement force maintaining
stent 340 in its axial and radial position on catheter 342. The
closer the mounting ring 334 is positioned to cup 342 the more
securely the stent is held in place and interlocked between this
cup and ring. When used in conjunction with mounting ring 334, cup
342 will also prevent the stent proximal segment 344 from opening
up, i.e., increasing its diameter, and will keep the stent 340
locked onto the mounting ring 334. This will prevent stent 340 from
moving on the catheter distally as well as proximally. This cup
does not have to be an elastomer, but may be sufficiently rigid to
prevent the stent 340 from expanding.
[0124] Cups 322, 342 of FIGS. 38-40 release stents 320, 340 when
balloons 318,338 are inflated during deployment. Cups 322,342 can,
for example, flare radially outward as illustrated with reference
to FIG. 41, roll axially away from stents 320, 340 as illustrated
with reference to FIG. 42, or slide axially away from stents 320,
340 as illustrated with reference to FIGS. 43 and 44. Also, the
cups may be formed with axial areas of weakness which split on
balloon inflation, as described in the aforenoted Savin patent.
[0125] FIG. 41 shows an assembly generally designated 310 as shown
in FIGS. 38 and 36 with balloon 318 inflated and stent 320
expanded, showing the cup 322 end portion flared to release stent
320. As noted above, cup 322 may be elastomeric or rigid. The
dimension L is short enough and the material of cup 322 is
sufficiently elastic so that cup 322 flares out and is no longer in
contact with stent 320 when balloon 318 is inflated and the stent
320 expanded for deployment.
[0126] FIG. 42 shows an assembly generally designated 310, as shown
in FIGS.
[0127] 38 and 36, with balloon 318 inflated and stent 320 expanded,
showing cup 322 end portion rolled proximally to release the stent
320. As noted above, the cup 322 may be elastomeric to facilitate
rolling. The cup may also accordion or bunch up on itself to
release the stent.
[0128] FIGS. 43 and 44 show yet another stent delivery and
deployment assembly generally designated 350. The catheter 352 has
a coaxial collar 354 formed integrally with catheter 352 at the
catheter distal end 356. A balloon 358 is coaxially mounted on
catheter 352, overlying collar 354. In FIG. 43, balloon 358 is
coaxially mounted on catheter 352, overlying collar 354. In FIG.
43, balloon 358 is shown as uninflated, with an unexpanded stent
360 mounted on balloon 358 abutting collar 354, and a cylindrical
cup in the form of sleeve 362 overlying the stent proximal end
portion 364. FIG. 44 shows the assembly 350 of FIG. 43 with balloon
358 inflated and stent 360 released and expanded. Sleeve 362 is
designed, constructed and adapted so that, as balloon 358 and stent
360 are enlarged, the sleeve portion 366 gathers or moves
proximally to release stent 360. The increasing angle of the
balloon 358 cone (the tapered end sections of balloon 358) during
inflation push sleeve 362 axially away from stent 360. This can be
done by shaping sleeve 362 with preformed accordion pleats 368.
Sleeve 362 may also be formed so that the portion detaining (that
is, abutting or overlying) stent 360 is of thicker or more rigid
material than the portion of sleeve 362 axially distant from stent
360. Materials which may be used to provide the foregoing function
are silicones, urethanes and the like as well as other elastomers,
for example. A rigid sleeve carried on the catheter for sliding
movement may also be used. Sleeves may be included at the proximal
and distal end of the stent.
[0129] FIG. 45 shows still another stent delivery and deployment
assembly generally designated 370. A catheter 372 has two collars
374 formed integrally with catheter 372 and spaced from each other
on the catheter distal end portion. A balloon 378 is coaxially
mounted on the catheter 372, overlying the collars 374. The balloon
378 is shown as uninflated with an unexpanded stent 380 mounted on
balloon 378 abutting both of the collars 374. It can be seen that
the distance between the collars 374 is to be chosen to closely
accommodate stent 380 in its fully contracted position about the
balloon 378 and underlying catheter 372. A cup 382 overlies the
stent proximal end portion 384 and the underlying proximal collar
374. Cup 382 will deploy during balloon 378 inflation in the manner
described above with reference to FIGS. 41-44.
[0130] FIG. 46 shows even another stent delivery and deployment
assembly generally designated 390. The uninflated balloon 398 is
shown coaxially mounted on a catheter 392 at the catheter distal
end portion. An unexpanded stent 400 is coaxially mounted on
balloon 398. A pair of cups 402 overlap the ends of the stent 400
ends. A mounting cylinder 404 is carried by the catheter shaft
392.
[0131] The Figure also illustrates cups at both ends of the stent,
an arrangement which may be used in all the foregoing
embodiments.
[0132] The cups or sleeves used in the various embodiments of this
invention can be of elastomeric or rigid material to contain one or
both ends of the stent. In preferred embodiments of this invention
the cups are used in conjunction with one or more stent collars
positioned under the balloon. The collar may be formed as a ring,
to abut the end of the stent, to lie under the stent and the
intervening balloon, or as a cylinder, to lie under essentially the
entire length of the stent and the intervening balloon. The stent
detainment according to the present invention offers increased
stent securement, particularly on pre-mounted delivery systems. The
cups and sleeves illustrated in the various embodiments of this
invention can be secured to the catheter, as by adhesive or thermal
bonding, or they may be sliding cups or sleeves. When the cups are
freely sliding on the catheter, they should always be used directly
over a collar so that there is a friction fit between the cup and
the stent.
[0133] A method for delivering and deploying a stent using an
assembly according to the present invention is described as
follows: A catheter is provided as described above with reference
to any of FIGS. 38-40, 43 and 45. At least one collar is coaxially
mounted at the catheter distal end. As discussed above, the collar
may be a separate element affixed to the catheter or the collar and
catheter may be formed together as a single element. The collar may
be positioned abutting an end of the stent. The collar may be a
mounting ring, may be positioned under the stent or underlying the
balloon. The collar may be a cylinder essentially coextensive in
length with the stent and underlying the balloon. A fluid
expandable balloon is coaxially mounted over the collar on the
catheter distal end. A stent is provided which is inflation
expandable from a reduced to an enlarged condition. The stent, in
its reduced condition, is coaxially mounted on the balloon so that
at least an end portion of the stent overlies the balloon. A cup is
provided which has first and second end portions. The cup is in an
expanded form and also has a retracted form. The expanded cup is
coaxially mounted on the catheter at the distal end portion so that
the cup first end portion detains the stent end portion. The cup
first end portion detains the stent end portion by overlying the
stent end portion, or by closely accommodating the stent against
the collar without overlying the stent end portion. The cup is then
contracted about the catheter and the stent end portion to fix the
stent to the catheter. The cup and collar cooperate to retain the
stent on the catheter in its reduced condition. The assembly is
then maneuvered by the physician through a body vessel by methods
known per se to reach a pre-selected deployment site. The surgeon
can determine when the assembly has reached the deployment site by
means which are themselves known per se. For example, the assembly
may be provided with radiopaque marking bands at either end of the
stent, or the cups or the collars or both may be made of radiopaque
material. Once the surgeon determines that the stent has been
correctly positioned at the desired site, the balloon is inflated
to expand the stent to its enlarged condition. Inflation of the
balloon expands the stent and the stent is released from the cup or
cups. As has been discussed above, the cups may deploy to release
the stent in a number of ways, dependant on the construction and
materials of the cup or cups. The cup may flare or enlarge radially
following the increasing angle of the balloon cones. The cup may
roll axially away from the stent. The portion of the cup axially
distant from the stent may accordion back on itself The cup may
slide axially. The cup may accordion or buckle. If the cup is not
fixed to the catheter, but is freely slidable on the catheter, the
cup may slide axially away from the stent. After deployment of the
stent, the balloon, according to previously known procedures, is
deflated and the assembly is withdrawn proximally from the body
vessel. Any incision made to allow access from the assembly is
appropriately closed.
[0134] FIGS. 47-56 illustrated alternative embodiments of
securement devices. Referring to FIGS. 47 and 48 a stent delivery
system generally indicated at 410 includes a balloon catheter 412
having a balloon 414 on a distal end portion generally indicated at
416. FIG. 47 shows a proximal portion of the catheter at 412a and a
distal portion 412b in enlarged view. FIG. 48 shows the distal end
portion 416 in an even more enlarged view. The illustrative
catheter 412 is of the type known as an over the wire catheter.
However, other types of catheters may be used, such as rapid
exchange/single operator exchange and fixed wire types. The balloon
414 is fixed to the catheter 412 by standard means. The balloon is
shown in its contracted state in FIGS. 47 and 48. A stent 418 is
fixed about the balloon by crimping it thereto. The stent has a
larger expanded diameter which is obtained when the balloon is
expanded in the known manner. That is, the stent is released from
the catheter upon expansion of the balloon when placed in a vessel.
When the balloon is then deflated, removal of the balloon and
catheter may be accomplished while leaving the stent in place.
[0135] As is known in the art the balloon is either bonded at its
ends by adhesive 420 and 422, respectively to the outer member 424
of the catheter and to the inner member 426 of the catheter in the
manner as shown, or is made one-piece with the outer member as is
known in the art. The catheter balloon may be inflated by fluid
(gas or liquid) from an inflation port extending from a lumen 428
contained in the catheter shaft and opening into the balloon as
shown, or by other known arrangements, depending on the design of
the catheter. The details and mechanics of balloon inflation and
specific overall catheter construction will vary according to the
particular design involved in any given instance, and are known in
the art per se. All variations are acceptable for use with this
invention.
[0136] Any balloon expandable stent may be used with this
invention. Many are known in the art including plastic and metal
stents. Some are more well known such as the stainless steel stent
shown in U.S. Pat. No. 4,735,665; the wire stent shown in U.S. Pat.
No. 4,950,227; another metal stent shown in European Patent
Application No. EPO 707 837 A1 and that shown in U.S. Pat. No.
5,445,646. All of these patents are incorporated herein by
reference. Also, shape memory metal stents may be used. As already
indicated the stent of PCT Application 960 3092 A1 is particularly
preferred.
[0137] The stent is typically about 16 mm long, while the balloon
may be 20 mm long. These dimensions, however, are merely
representative for illustrative purposes only and are not meant to
be limiting. The stent is positioned over the balloon portion of
the dilatation catheter and gently crimped onto the balloon either
by hand or with a tool such as a pliers or the like to be mounted
for delivery as shown in FIGS. 47 and 48. The crimping may be
accomplished by either the manufacturer or the physician.
[0138] In accordance with one embodiment of this invention, a
mounting bodies 430, seen in FIGS. 47 and 48 are included inside
balloon 414 to provide a cushion and/or substrate of enlarged
diameter relative to the shaft to support and hold the stent and
secure it during crimping and the delivery procedure. The mounting
bodies are preferably located in the body portion of the
balloon.
[0139] In the embodiment shown, mounting bodies 430 are ring-like
in form and are mounted on inner lumen 426, providing an enlarged
area or portion for receiving the balloon and stent when the latter
is crimped. Marker bands 432 and 434 may also be included on inner
426 as shown. Any radiopaque material such as gold is useful for
this purpose. Although, the material of the mounting bodies may be
hard, it is preferably of any thermoplastic elastomer having
elastic or deformable properties, more preferably of a relatively
resilient elastomer material, e.g., silicone, preferably a lower
durometer silicone, or polyurethane, such as Tecothane 1055D. A
deformable thermoplastic material such as high density polyethylene
(HDPE) may be used. Any deformation of resilient material of the
mounting body when the stent/balloon is crimped to it causes a
radial outward force on the stent/balloon increasing the friction
therebetween despite a recoil of the stent.
[0140] The stent is also fixed in position by two overlying
retaining sleeves 436 and 438. Sleeves 436 and 438 are formed of
polyurethane, preferably Tecothane 1055D, and are axially fixed on
catheter 412 by adhesive plugs 440 and 442 of urethane adhesive.
The plugs of adhesive may be tapered to the catheter as shown to
facilitate movement of the catheter in a vessel. The sleeves
overlap the marginal end portions of stent 418 as shown.
[0141] A lubricating solution such as silicone fluid may be used
between balloon 414 and sleeves 436 and 438 and thereon to
facilitate release of stent 418 from the sleeves.
[0142] During delivery, the balloon catheter is advanced through
and positioned in a patient's vasculature so that the stent is
adjacent to the portion of the vessel where treatment is to take
place. The balloon is inflated to expand the stent to an enlarged
diameter. At this time, expansion of the balloon causes the end
margin of the sleeves to slide axially from over the stent thereby
releasing the ends of the stent from the catheter. Various forms of
retraction of sleeves 436 and 438 are shown in FIGS. 49-52. These
figures illustrate the configuration of the sleeves 436 and 438 in
their retracted state after the balloon 414 has been fully
expanded. Only the distal sleeve 438 is shown. FIG. 49 illustrates
the preferably retraction configuration. To promote easier
retraction sleeves are coated with silicone. The sleeves are
preferably adhered to the outer shaft 424 and the inner shaft 426
at point 440, 442, but may be adhered further up the waste 441 of
the balloon. The retraction configurations may be controlled by
either pre-creasing the sleeves or adhering the sleeve to a point
further up on the waist of the balloon. The sleeves have a tendency
of folding at a pre-fold crease or at the point of adherence. A
preferred cone angle of 45.degree. for the balloon is shown in FIG.
52, which shows an expanded balloon 414 and retracted sleeves
436,438. When the stent has reached the desired diameter, the
balloon is deflated so that the catheter may be removed leaving the
stent in place.
[0143] A modified 439 sleeve configuration is shown in FIG. 53 in
stepped form 43 having a large diameter at 444 in one section 446
and a small diameter 445 in a second section 450.
[0144] FIGS. 54-56 show alternative embodiments of the invention.
Specifically, alternative positioning and number of mounting bodies
430. These figures show an unexpanded balloon having the mounted
bodies 430 within the balloon. They are meant to illustrate
essentially the same structure as shown in FIG. 448 differing only
in the number and positioning of the mounted bodies 430. In the
embodiment shown in FIG. 54, the ring-like mounting body 430 is
singular. Another similar version is shown in FIG. 55 which
includes three ring-like mounting bodies 430. The embodiment shown
in FIG. 56 includes four ring-like mounting bodies 430.
[0145] It should be understood that the various elements and
materials of all embodiments could be utilized in each of the other
embodiments, if desired.
[0146] The above Examples and disclosure are intended to be
illustrative and not exhaustive. These examples and description
will suggest many variations and alternatives to one of ordinary
skill in this art. All these alternatives and variations are
intended to be included within the scope of the attached claims.
Those familiar with the art may recognize other equivalents to the
specific embodiments described herein which equivalents are also
intended to be encompassed by the claims attached hereto.
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