U.S. patent application number 13/205283 was filed with the patent office on 2011-12-01 for stent with reduced weld profiles and a closed-end wire configuration.
This patent application is currently assigned to BOSTON SCIENTIFIC SCIMED, INC.. Invention is credited to Claude O. Clerc, Gary J. Leanna, Paul K. Norton, George Tom Roberts, Michael Zupkofska.
Application Number | 20110295359 13/205283 |
Document ID | / |
Family ID | 35116114 |
Filed Date | 2011-12-01 |
United States Patent
Application |
20110295359 |
Kind Code |
A1 |
Clerc; Claude O. ; et
al. |
December 1, 2011 |
Stent With Reduced Weld Profiles and a Closed-End Wire
Configuration
Abstract
A method for making an implantable stent includes the steps of
(i) providing a plurality of elongate stent wires; (ii) forming
said wires into a hollow tubular structure having opposed first and
second open ends; (iii) terminating said wires at the second end;
(iv) aligning the wires at the second end into a plurality of mated
adjacent wires to define a plurality of abutting regions; (v)
welding the mated adjacent wires to one and the other at the
abutting regions to define a plurality of welds; and optionally
(vi) chemically or electro-chemically removing a portion of the
welds. The method may further include the steps of (a) extending at
least one of the mated stent wires to provide an extended stent
wire; (b) looping the extended stent wire so the extended end abuts
a proximal pair of stent wires; and (c) welding the extended and
looped wire to the proximal pair of wires. The step of looping may
include the forming of the wire into a equilaterally arched loop
having an apex, but not having other sharp bends.
Inventors: |
Clerc; Claude O.;
(Marlborough, MA) ; Norton; Paul K.; (Lunenburg,
MA) ; Zupkofska; Michael; (Rockland, MA) ;
Leanna; Gary J.; (Holden, MA) ; Roberts; George
Tom; (Lincoln, MA) |
Assignee: |
BOSTON SCIENTIFIC SCIMED,
INC.
Maple Grove
MN
|
Family ID: |
35116114 |
Appl. No.: |
13/205283 |
Filed: |
August 8, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10845844 |
May 14, 2004 |
7993387 |
|
|
13205283 |
|
|
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|
Current U.S.
Class: |
623/1.15 |
Current CPC
Class: |
B23K 2101/32 20180801;
B23K 2101/06 20180801; A61F 2220/005 20130101; D10B 2509/06
20130101; B23K 9/0026 20130101; C23F 3/04 20130101; B23K 26/12
20130101; C25F 3/16 20130101; B23K 26/123 20130101; A61F 2220/0058
20130101; B23K 11/008 20130101; B23H 9/02 20130101; A61F 2/90
20130101; D04C 3/48 20130101; A61F 2230/0013 20130101; D04C 1/06
20130101; D10B 2403/0112 20130101; B23K 37/08 20130101; B23K 15/008
20130101; B23K 2101/22 20180801; B23K 26/211 20151001; A61F
2230/001 20130101 |
Class at
Publication: |
623/1.15 |
International
Class: |
A61F 2/82 20060101
A61F002/82 |
Claims
1. A prosthesis, the prosthesis comprising a plurality of wires,
each wire comprising at least one weld region and at least one
non-weld region, each non-weld region having a first diameter, each
weld region having a second diameter less than the first diameter;
and a plurality of welds, each weld comprising a weld region of at
least two of the plurality of wires.
2. The prosthesis of claim 1, the prosthesis being a tubular mesh,
the tubular mesh comprising the plurality of wires.
3. The prosthesis of claim 2, the tubular mesh being selected from
the group consisting of a braid, a weave, or a knit.
4. The prosthesis of claim 1, wherein the weld regions forming a
weld are substantially parallel to one another.
5. The prosthesis of claim 1, the prosthesis comprising a first end
region and a second end region, the at least one first weld located
in the first end region of the prosthesis, the first end region
having a reduced diameter relative to other regions of the
prosthesis.
6. The prosthesis of claim 1, the prosthesis further comprising a
band of biocompatible material, the band being attached to an outer
surface of a portion of the first end region.
7. The prosthesis of claim 1, each weld comprising a weld region of
only two of the plurality of wires.
8. The prosthesis of claim 1, the plurality of welds comprising a
plurality of first welds and a plurality of second welds, each
first weld comprising a weld region of two of the plurality of
wires, each second weld comprising a weld region of three of the
plurality of wires.
9. The prosthesis of claim 8, wherein one of the three of the
plurality of wires of a second weld also forms a part of a first
weld.
10. The prosthesis of claim 9, the one of the three of the
plurality of wires forming a loop.
11. The prosthesis of claim 10, the first welds and the second
welds longitudinally aligned, each first weld being between two
second welds and each second weld being between two first
welds.
12. The prosthesis of claim 1, each wire having a first end region,
the weld regions comprising first weld regions and second weld
regions, each first weld region forming the first end region of a
wire and each second weld region being a distance away from the
first end region of a wire, the plurality of welds comprising a
plurality of first welds, each first weld comprising one first weld
region of a wire and one second weld region of a wire.
13. The prosthesis of claim 12, each first weld located at a first
longitudinal position of the prosthesis, the plurality of welds
further comprising second welds, each second weld comprising one
first weld region of a wire and one second weld region of a wire,
and each second weld located at a second longitudinal position of
the prosthesis, the second longitudinal position being different
than the first longitudinal position.
14. The prosthesis of claim 13, wherein the first and second welds
have a wire in common.
15. The prosthesis of claim 13, the prosthesis further comprising a
plurality of coils, each coil longitudinally aligned and forming a
first end of the prosthesis, the second welds longitudinally
aligned and positioned a first distance from the coils, the first
welds longitudinally aligned and positioned a second distance from
the coils, the second distance being greater than the first
distance.
16. The prosthesis of claim 12, the prosthesis comprising a
plurality of first welds, the first welds being a distance from a
hook forming a first end of the prosthesis, the hook comprising
wires with a second weld region forming a part of one of the
plurality of first welds.
17. A prosthesis, the prosthesis having a first end and a second
end, the prosthesis being a tubular mesh comprising a plurality of
wires, each wire having a first diameter, the plurality of wires
comprising: a plurality of first wires, each first wire comprising
a first weld region, the first weld region including an end of the
first wire; a plurality of second wires, each second wire
comprising a first end and a first weld region, the first weld
region positioned a first distance from the first end of the second
wire; a plurality of third wires, each third wire comprising a
first end and a first weld region, the first weld region being
located a first distance away from the first end of the third wire;
the prosthesis further comprising a plurality of first welds, each
first weld positioned a first distance away from the first end of
the prosthesis, each first weld comprising: the first weld region
of one first wire and one of the first weld region of one second
wire or the first weld region of one third wire.
18. The prosthesis of claim 17, each third wire comprising a coil
portion, the coil portions of the plurality of third wires forming
the first end of the prosthesis.
19. The prosthesis of claim 17, further comprising a plurality of
second welds, each second weld positioned a second distance away
from the first end of the prosthesis, where the second distance is
less than the first distance.
20. The prosthesis of claim 19, each second wire further comprising
a second weld region, the second weld region including the first
end of the second wire; each third wire further comprising a second
weld region, the second weld region being located a second distance
away from the first end of the third wire, where the second
distance is less than the first distance; each second weld
comprising the second weld region of one second wire and the second
weld region of one third wire.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 10/845844 filed May 14, 2004, the contents of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to stents having welded
portions and atraumatic looped ends. The present invention also
relates to such stents having their welded portions
electro-chemically polished to reduce their profile and/or having a
suture loop threaded at one or both extremities and/or being
manufactured with a wire having a radiopaque core, and/or being
fully or partially covered with a polymer such as silicone.
BACKGROUND OF THE INVENTION
[0003] Stents made from interconnecting, often braiding, elongate
wires may be made less traumatic, i.e., atraumatic, by closing the
loose wire ends at the ends of the stents. The loose wire ends have
typically been closed by mechanical means, such as by clamps, for
example clamped microtubes, or by welding. Such mechanical means,
however, provide regions of high profile as compared to the other
regions of the stents, see e.g., U.S. Pat. No. 6,083,257. The high
profile regions are undesirable, often leading to deployment
concerns, including higher deployment forces.
[0004] Electropolishing or electro-chemical polishing of laser cut
nitinol stents to improve surface finishes has been previously
mentioned, see e.g. U.S. Pat. No. 6,325,825 B1 and U.S. Patent
Application Publication No. 2003/0024534 A1. Further,
electro-polishing or electrochemical polishing services are
available, see e.g. from Admedes Schuessler GmbH. Such polishing,
however, has not been attempted to alleviate the above-discussed
deployment concerns.
[0005] The present invention provides a stent made from elongate
wires in a closed-end design while avoiding the disadvantages of
the prior art. More particularly, the present invention is directed
to certain advantageous closed-end stent loop designs having
reduced profiles to lower deployment forces and ease deployment of
the stent.
SUMMARY OF THE INVENTION
[0006] In one aspect of the present invention is a method for
making an implantable stent. The method comprises the steps of (i)
providing a plurality of elongate stent wires; (ii) forming the
wires into a hollow tubular structure having opposed first and
second open ends; (iii) terminating the wires at the second end;
(iv) aligning the wires at the second end into a plurality of mated
adjacent wires to define a plurality of abutting regions; (v)
welding the mated adjacent wires to one and the other at the
abutting regions to define a plurality of welds; and, optionally,
(vi) chemically or electro-chemically removing a portion of the
welding material from the plurality of welds. Desirably, the mated
adjacent wires are substantially parallel to one and the other at
the abutting regions.
[0007] In this aspect of the present invention, the step of welding
may include the step of providing an inert gas proximal to the weld
areas. Further, the step of welding includes laser welding,
electron beam welding, resistance welding, tungsten inert gas
welding, metal inert gas welding, and combinations thereof.
[0008] Desirably, the step of forming the tubular structure
comprises braiding the wires, winding the wires, knitting the
wires, and combinations thereof, preferably braiding the wires. The
material of the wires and the material of the welds may be the same
type of material.
[0009] Further, the stent wire may include a radiopaque
material.
[0010] The step of chemically or electro-chemically removing the
portion of the welding material may include chemical polishing or
etching, chemical deburring, electrochemical polishing or etching,
jet-electropolishing and combinations thereof. The step of
electro-chemically removing the portion of the welding material
further includes the step of providing an electrolyte, where the
electrolyte is selected from the group consisting of NaClO.sub.3
electrolyte, NaNO.sub.3 electrolyte, NaCl electrolyte,
Na.sub.2Cr.sub.2O.sub.7 electrolyte, HOCH.sub.2CH.sub.2OH
electrolyte, and combinations thereof.
[0011] In further detail, the step of electro-chemically removing
the portion of the welding material may further include the step of
(i) providing an electrolyte; (ii) placing a cathode into the
electrolyte; (iii) placing a portion of the stent having the
welding material into the electrolyte; (iv) providing an electrical
voltage or current so that the cathode is negatively charged and
the stent portion is positively charged; and (v) partially
dissolving the portion of the stent exposed to the electrolyte.
[0012] In another aspect of the present invention, the method of
making the stent may further include the steps of (i) extending at
least one of the mated stent wires to provide an extended stent
wire; (ii) looping the extended stent wire so the extended end
abuts a proximal pair of stent wires; and (iii) welding extended
and looped wire to the proximal pair of wires. Desirably, the step
of looping includes forming the wire into an arch with equilateral
sides, having an apex, but not having other sharp bends. Desirably,
the step of looping includes forming the wire into an equilateral
arch having one vertex having similar curvatures on either side of
the one vertex, where the equilateral arch does not contain a
second vertex having dissimilar curvatures on either side of the
second vertex.
[0013] In another aspect of the present invention, the method of
making the stent may further include the steps of (i) extending at
least one of the mated stent wires past the abutting regions to
provide an extended stent wire; and (ii) looping the extended stent
wire at its extended end to form a coil thereat. A plurality of
extended wires may also be formed into one coil or pig tail.
[0014] Desirably, the elongate wires comprise biocompatible
materials selected from the group consisting of nitinol, stainless
steel, cobalt-based alloy such as Elgiloy, platinum, gold,
titanium, tantalum, niobium, and combinations thereof, preferably
nitinol. The elongate wires may be composite wires for improved
radiopacity, such as having an inner core of tantalum, gold,
platinum, iridium or combination of thereof and an outer layer or
member of nitinol.
[0015] In another aspect of the present invention, an implantable
stent is provided. The stent of this aspect of the present
invention may include a plurality of wires arranged to form a
hollow tubular structure having a tubular wall to define an
interior surface and an exterior surface and having opposed open
first and second ends, where the wires terminate at the second open
end ends and adjacently abutting wires are welded at the second
open end with a welding material to provide welds, and further
where at least a portion of the welded material has been removed to
reduce the profile of the welds. Desirably, the portion of welded
material has been removed by chemical or electro-chemical
polishing. Preferably, at least 25 to 50% by weight of the stent
material at or around the weld location has been removed. The
reduced profile of the welds are from about 5 to about 50 linear
percent of a diameter of the stent wires.
[0016] The stent includes wires made from bio compatible materials,
such as nitinol, stainless steel, cobalt-based alloy such as
Elgiloy, platinum, gold, titanium, tantalum, niobium, and
combinations thereof. The weld material and the wire material may
also be the same, for example nitinol. Further, the elongate wires
have an inner core of tantalum gold, platinum, iridium or
combination of thereof and an outer member of nitinol.
[0017] In another aspect of the present invention, at least one
some of the adjacently abutting stent wires are extended past the
welds and looped into an arch with equilateral sides having an
apex, but not having other sharp bends, or in other words at least
some of the adjacently abutting stent wires are extended past the
welds and looped into an arch with equilateral sides having one
vertex having similar curvatures on either side of the one vertex,
where the arch design does not contain a second vertex having
dissimilar curvatures on either side of the second vertex.
Alternatively, at least some of the adjacently abutting stent wires
are extended past the welds and looped to form a coil thereat in
the shape of a pig tail. Still alternatively, at least some of the
adjacently abutting stent wires are extended past the welds and
looped to form one coil thereat.
[0018] The stent wires may be coated, for example coated with
silicone. Further, the stent may be fully or partially covered with
a polymeric covering, such as silicone, in order to prevent tissue
or tumor ingrowth.
[0019] The stent may further include a hollow tubular graft
disposed over the interior or the exterior surface. The graft may
be a polymeric material, for example, a polyester, a polypropylene,
a polyethylene, a polyurethane, a polynaphthalene, a
polytetrafluoroethylene, an expanded polytetrafluoroethylene, a
silicone, and combinations thereof.
[0020] Desirably, the stent is a braided stent.
[0021] The stent may further include a polymeric ring disposed over
the exterior surface at the second open end. Additionally, the
stent may further include a suture secured to one of the open ends.
Such suture or sutures are useful for positioning, repositioning,
and/or removing the stent. The suture can be a metallic, polymeric
or textile suture loop threaded through the stent loops at one or
both extremities of the stent. The suture loop may include a
protruding part to help facilitate the capture or grabbing of the
stent end.
[0022] In another aspect of the present invention, an implantable
stent includes a plurality of wires arranged to form a hollow
tubular structure having a tubular wall to define an interior
surface and an exterior surface and having opposed open first and
second ends, where the wires terminate at the second open end ends
and adjacently abutting wires are welded at the second open end
with a welding material to provide welds, and further where at
least a portion of the welded material has been removed by chemical
or electrochemical polishing to reduce the profile of the
welds.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a perspective view of a hollow, tubular stent
according to the present invention.
[0024] FIG. 2 is an expanded view of a wall portion of the stent of
FIG. 1 taken along the 2-2 axis showing a plurality of stent
wires.
[0025] FIG. 3 depicts a braided stent with a closed-end loop design
having a plurality of welds at the closed end according to the
present invention.
[0026] FIG. 4 is an expanded view of a weld of FIG. 3.
[0027] FIG. 5 depicts a weld adjoining two stent wires according to
the present invention.
[0028] FIG. 5A depicts a weld adjoining two stent wires having an
insulator or photoresist on selected stent wire portions according
to the present invention.
[0029] FIG. 6 is a cross-sectional view of the adjoining stent
wires of FIG. 5 taken along the 6-6 axis.
[0030] FIG. 7 is a cross-sectional view of the welded stent wires
of FIG. 5 taken along the 7-7 axis.
[0031] FIG. 8 is a cross-sectional view of the welded stent wires
of FIG. 7 after chemical or electrochemical polishing.
[0032] FIG. 9 is a schematic depiction of an electro-chemical
polishing cell according to the present invention.
[0033] FIGS. 10-14 depict an arch with equilateral sides and an
apex in a closed-end loop design according to the present
invention.
[0034] FIG. 15 depicts another embodiment according to the present
invention of a closed-end loop design of the present invention
having a plurality of coils at the closed end.
[0035] FIG. 16 depicts yet another embodiment according to the
present invention of a closed-end loop design of the present
invention having one coil or pigtail at the closed end.
[0036] FIGS. 17-18 depict yet another embodiment according to the
present invention of a closed-end design having a band disposed
over the stent wires at the closed end.
[0037] FIG. 19 depicts a mandrel having shaped pins for forming the
closed loops of FIGS. 10-14.
[0038] FIG. 20 depicts a stent having a covering of silicone
according to the present invention.
[0039] FIG. 21 is a cross-sectional view if the stent of FIG. 20
showing an outer covering of silicone about the stent.
[0040] FIG. 22 is a cross-sectional view if the stent of FIG. 20
showing an inner covering of silicone about the stent.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0041] The present invention overcomes the deficiencies of the
prior art by providing, among other things, low profile stent welds
that reduce stent deployment forces. FIG. 1 depicts stent 10 of the
present invention. Stent 10 is a hollow tubular structure having
opposed open ends 12, 14 and having a tubular wall 16 therebetween.
A portion of the tubular wall 16 is depicted in FIG. 2 as having a
plurality of elongate wires 18 formed into the tubular wall 16. The
elongate wires 18 traverse the length of the stent 10 in a
direction traverse to the longitudinal length of the stent 10. The
elongate wires 18 may be formed into the tubular wall 16 by
braiding the wires 18, winding the wires 18, knitting the wires 18,
and combinations. Preferably, the wires 18 are braided to form the
tubular wall 16.
[0042] A welded stent 10' according to the present invention is
depicted in FIG. 3. The elongate wires 18 terminating at open end
12 are mated and adjacently mated wires are secured to one and the
other by welds 20. The joining of three adjacently mated wires 18
and the welding thereat is depicted in further detailed in FIG. 4.
The positioning of adjacently mated wires to form closed-loop end
designs, excluding the closed-end arch loop design of the present
invention which is described below, is further described in U.S.
application Ser. No. 60/472,929, filed May 23, 2003, which
represents U.S. application Ser. No. 10/852,495 and which published
as US 2005/0049682 A1, the contents of which are incorporated
herein by reference. The weld 20 may be a low profile weld, i.e., a
weld with a reduced welding zone as compared to stent welds of the
prior art. The stent 10' depicted in FIG. 3 includes 24 wires 18 of
nitinol or nitinol-containing material. The wires are relatively
thin at a diameter of about 0.011 inches. The number of wires and
the diameters of the wires, which may be the same or different,
depicted in FIG. 3 are not limiting, and other numbers of wires and
other wire diameters may suitably be used.
[0043] A pair of adjacently welded wires according to the present
invention is depicted in FIGS. 5-8. Weld 24 securably joins
adjacently mated stent wires 22. As compared to the prior art, the
weld 24 of the present invention has a significant reduction in the
amount of welding material in weld 24. Desirably, weld 24 has at
least about 25% or less welding material than prior art welds, for
example from about 25% to about 50% less welding material.
Alternatively, the weld 24 desirably has a profile, i.e., a depth
d.sub.3 and/or a width d.sub.4, that is less than the diameter,
d.sub.1, of the wire 22. Yet alternatively, or in addition to, the
welds 24 of the present invention have a profile of about 150
microns or less, preferably from about 50 microns to about 150
microns. Yet alternatively, or in addition to, the weld 24' of the
present invention and portions of the stent wires 22' proximal to
the welds 24' have a reduced profile where the profile of weld 24'
is lower than the profile of weld 24 and where the diameter,
d.sub.2, of the proximal stent portions 22' is less than the
diameter, d.sub.1, of stent wire portions 22. The mass and volume
of the weld 24' and/or stent portions 22' is suitably reduced by
chemical or electrochemical polishing. Reduced profile welds 24,
24' of the present invention overcome the difficulty of
constraining the stent 10, 10' on a delivery device (not shown) by
removing excess weld material that would otherwise increase
localized constraining forces at the weld locations as compared to
other portions of the stent 10, 10'.
[0044] Useful welding methods include, but are not limited to,
laser welding, electron beam welding, resistance welding, tungsten
inert gas welding, metal inert gas welding and combinations
thereof. In laser and electron beam welding the wires are partially
melted by the energy provided by the laser or electron beam. In gas
tungsten arc welding (GTAW or TIG welding), an arc is formed
between an electrode, typically tungsten, and the metal being
welded. In metal inert gas (MIG) welding, an arc is generated
between a filler electrode and the metal being welded with metal
melted from the filler electrode being added to the metal being
welded. Resistance welding uses the application of electric current
and sometimes mechanical pressure to create a weld between two
pieces of metal. The weld areas may be shielded with an inert gas.
Suitable, but non-limiting, inert gasses include argon and
argon/gas admixtures, such as argon/hydrogen or argon/helium.
[0045] FIG. 9 depicts an electro-chemical cell 30 for removing weld
material to thereby form the low profile weld 24, 24' of the
present invention. The cell 30 includes an electrolyte 32 contained
within a container 34. The stent 10 with welds 24, 24' at stent end
12 is placed within the electrolyte 32. A cathode 36 is also placed
within the electrolyte 32. A wire 38 connects the cathode 36 to the
negative terminal 40 of voltage or current source 46. A wire 42
connects the stent 10 to the positive terminal 44 of the voltage or
current source 46. Upon application of voltage or current from the
source 46 the cell 30 becomes operational. Material, such as weld
material, is dissolved from the stent 10 into the electrolyte 32.
Useful electrolytes include NaClO.sub.3 electrolyte, NaNO.sub.3
electrolyte, NaCl electrolyte, Na.sub.2Cr.sub.2O.sub.7 electrolyte,
HOCH.sub.2CH.sub.2OH electrolyte and combinations thereof. Typical,
but non-limiting, current densities are in the magnitude of about
50 to about 150 amps/cm.sup.2. The electrolyte 32 may be in motion
at low velocities or unstirred. As the anode metal is dissolved
electrochemically, the dissolution rate is not influenced by the
hardness or other physical characteristics of the metal.
[0046] Desirably, the wires 22 are made from nitinol, stainless
steel, cobalt-based alloy such as Elgiloy, platinum, gold,
titanium, tantalum, niobium, and combinations thereof. Further, the
wires 22 have an inner core of tantalum gold, platinum, iridium or
combination of thereof and an outer member or layer of nitinol to
provide a composite wire for improved radiocapicity or visibility.
Further details of such composite wires may be found in U.S. Patent
Application Publication 2002/0035396 A1, the contents of which is
incorporated herein by reference. Preferably, the wires 22 are made
from nitinol. Further, the filling weld material, if required by
welding processes such as MIG, may also be made from nitinol,
stainless steel, cobalt-based alloy such as Elgiloy, platinum,
gold, titanium, tantalum, niobium, and combinations thereof,
preferably nitinol. The material of the cathode is no critical and
can be made out of any suitable metal. The filling weld material
and the wire 22 may be made of the same material, for example
nitinol.
[0047] As the chemical electro-chemical polishing 30 removes
material from portions of the stent 10 that are disposed within the
electrolyte 32, there are several means to selectively remove
material from the stent 10, such as welds 24, 24', burrs or other
imperfections (not shown), and the like. One technique for
selectively removing material is through the use of a photoresist
or insulator, which is an organic polymer or resin that can be
applied to selective areas of the stent 10 to avoid the
electrochemical polishing of covered parts 30 as the photoresist
insulates the selected from the action of the electrolyte. For
example, as depicted in FIG. 5A, portions of the stent wires 22 may
be coated with a photoresist prior to placement in the cell 30.
After chemical or electro-chemical polishing is completed the
photoresist may be removed by application of a suitable solvent.
Alternatively, jet electro-chemical polishing or etching could be
used to specifically etch weld regions. Jet etching includes the
localized application of electrolyte at moderate velocity, such as
about 3 to about 30 m/s, to selectively polish desired areas, such
as stent welds.
[0048] Alternatively, chemical polishing, chemical etching and the
like may be used to remove portions of the weld 24, 24' and
optionally portions of the stent wire 22. Chemical polishing or
etching is similar to the above described electrochemical methods,
expect an oxidizing acid is added to the electrolyte and associated
equipment (current or voltage source, cathode, etc.) is optionally
not necessary. Useful, but not limiting, oxidizing acid-containing
electrolytes include electrolytes having hydrofluoric acid, nitric
acid, and combinations thereof.
[0049] The present invention, however, is not limited to low
profile welds just at terminatingly adjacent wires, such as wires
22 of FIG. 5 or 5A. As depicted in FIGS. 10-14, certain stent wires
56, 62 may be extended beyond adjacent wires 50, 64, and then
looped back to proximal wires 52, 60 and 58, 64, respectively.
Adjacent portions of wires 50 and 56 are abuttingly disposed at
abutting region 68. Similarly, adjacent portions of wires 52 and 60
and the adjacent portion of the extended loop portion 66 are
abuttingly disposed at abutting region 70; adjacent portions of
wires 54 and 62 are abuttingly disposed at abutting region 72; and
adjacent portions of wires 58 and 64 and the adjacent portion of
the extended loop portion 67 are abuttingly disposed at abutting
region 74. Desirably, the abuttingly disposed wire portions in the
abutting regions are substantially parallel to one and the other,
for example, but not limited to, being within about plus or minus
10 degrees of parallelism to one and the other, preferably, but not
limited to within about plus or minus 5 degrees of parallelism.
[0050] As depicted in FIG. 11, the wires at the abutting regions
68, 70, 72, 74 may be secured by welds 76. Desirably, welds 76 are
low profile welds having low profiles from electrochemical
polishing according to the present invention.
[0051] Desirably, the extended loop portions 66, 67 are of an arch
with equilateral sides design, which can be referred to as a
cathedral type of arch or loop. As depicted in FIG. 12, the
equilaterally arched loop 78 has an apex or vertex 80. As used
herein, the term "vertex" and its variants refer to the
intersection of two geometric lines or curves. As used herein, the
term "apex" and its variants refer to a vertex at the top or summit
of a loop. Desirably, the equilaterally arched loop 78 does not
have any bends, which are defined as areas having dissimilar
curvatures on either side of a point, except for the apex 80. In
other words, the equilaterally arched loop 78 has an apex, but not
other sharp bends. Desirably, the equilaterally arched loop 78 has
one vertex (or apex 80) having similar curvatures on either side of
the one vertex (or apex 80), but does not contain a second vertex
having dissimilar curvatures on either side of the second
vertex.
[0052] The equilaterally arched loop design offers several
advantages, including reduced deployment force, as compared to
prior art loop designs having a plurality of vertices or sharp
bends. When a stent is constrained on or in a delivery system (not
shown) the multiple sharp bends in the end loops of the stent
typically impinge on the wall of the delivery system and become
slightly imbedded thereat, thereby distorting the outer sheath of
the delivery system. This results in significantly greater
deployment force values. Further, as the equilaterally arched loop
has only one sharp bend, i.e., its apex, and is defined otherwise
by a gradual curvature, the gradual curvature portions do not
become imbedded in the wall of the delivery system, thereby
significantly reducing the resultant deployment force.
[0053] In another aspect of the present invention as depicted in
FIG. 13, an equilaterally arched loop 82 may have an apex 84 and
vertices 86 having substantially straight line portions 88. In such
a case, the vertices 86 and the straight line portions 88 have low
profile welds 90 thereover to adjoin other adjacently abutting
stent wires (not shown). The equilaterally arched loops 66, 67, 78,
82 of the present invention may be suitably formed by winding their
stent wires about shaped pins 98 on a mandrel 100 as depicted in
FIG. 19. Further, either or both of the ends 12, 14 of the stent
10, 10', including end 12 with equilaterally arched loops 66, 67,
78, 82, may have a suture or sutures (not shown) attached thereto.
Such sutures are useful for positioning, repositioning, and/or
removing the stent 10, 10'.
[0054] In still a further aspect of the present invention, the
stent 10 may have other designs at open end 12 that are useful for
positioning, repositioning, and/or removing stent 10. As depicted
in FIG. 15, wires may be extended from all or some of the adjacent
wire engaging portions 92. The ends of the extended wires may be
formed into coils 90. As depicted in FIG. 16, wires may be extended
from all or some of the adjacent wire engaging portions 92. The
ends of the extended wires may be formed into a coil 94, which is
in the shape of a hook and commonly referred to as a pigtail. Still
further, the open end 12 of stent 10 may be of reduced diameter as
compared to the other portions of the stent 10. The reduced
diameter portion facilitates access to the stent end 12 for
positioning, repositioning, and/or removing stent 10. The stent end
12 of the stent 10 of FIG. 17 may include any of the previously
described loops or coils thereat. Alternatively, or in addition to,
the stent end 12, as depicted in FIG. 18, may have a band 96
disposed thereover, which is also useful for positioning,
repositioning, and/or removing stent 10. Band 96 may be made of any
biocompatible material, including polymers, plastics and metals.
The band 96 may be attached to the stent end 12 by adhesive,
mechanical or physical means, such as adhesive bonding, welding,
suturing, fusing, and the like.
[0055] As depicted in FIG. 20, the stent 10 may be fully,
substantially or partially covered with silicone 102 in also the
form of a tubular structure. The silicone 102 may be disposed on
external surfaces 104 of the stent 10, as depicted in FIG. 21, or
disposed on the internal surfaces 106 of the stent 10, as depicted
in FIG. 22, or combinations thereof.
[0056] With any embodiment of the stent 10, 10' is usable to
maintain patency of a bodily vessel, such as in the coronary or
peripheral vasculature, esophagus, trachea, bronchi colon, biliary
tract, urinary tract, prostate, brain, and the like. Also, the
stent 10, 10' may be treated with any of the following:
anti-thrombogenic agents (such as heparin, heparin derivatives,
urokinase, and PPack (dextrophenylalanine proline arginine
chloromethylketone); anti-proliferative agents (such as enoxaprin,
angiopeptin, or monoclonal antibodies capable of blocking smooth
muscle cell proliferation, hirudin, and acetylsalicylic acid);
anti-inflammatory agents (such as dexamethasone, prednisolone,
corticosterone, budesonide, estrogen, sulfasalazine, and
mesalamine); antineoplastic/antiproliferative/anti-miotic agents
(such as paclitaxel, 5-fluorouracil, cisplatin, vinblastine,
vincristine, epothilones, endostatin, angiostatin and thymidine
kinase inhibitors); anesthetic agents (such as lidocaine,
bupivacaine, and ropivacaine); anti-coagulants (such as
D-Phe-Pro-Arg chloromethyl keton, an RGD peptide-containing
compound, heparin, antithrombin compounds, platelet receptor
antagonists, anti-thrombin antibodies, anti-platelet receptor
antibodies, aspirin, prostaglandin inhibitors, platelet inhibitors
and tick antiplatelet peptides); vascular cell growth promotors
(such as growth factor inhibitors, growth factor receptor
antagonists, transcriptional activators, and translational
promoters); vascular cell growth inhibitors (such as growth factor
inhibitors, growth factor receptor antagonists, transcriptional
repressors, translational repressors, replication inhibitors,
inhibitory antibodies, antibodies directed against growth factors,
bifunctional molecules consisting of a growth factor and a
cytotoxin, bifunctional molecules consisting of an antibody and a
cytotoxin); cholesterol-lowering agents; vasodilating agents; and
agents which interfere with endogenous vascoactive mechanisms.
[0057] The invention being thus described, it will now be evident
to those skilled in the art that the same may be varied in many
ways. Such variations are not to be regarded as a departure from
the spirit and scope of the invention and all such modifications
are intended to be included within the scope of the following
claims.
* * * * *