Note: Descriptions are shown in the official language in which they were submitted.
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TUBULAR STENT AND METHODS OF MAKING THE SAME
Technical Field
This invention generally relates to stents and methods of making a stent from
a
tubular member for placement within a body lumen or interior space of a body
during
a medical procedure.
Background
Stents are expandable endoprosthetic devices adapted to be placed in a body
lumen in order to maintain the patency of a body lumen by providing a flow
pathway
and/or structural support, for example. Stents are typically used in the
treatment of
atherosclerotic stenosis in blood vessels and the like to reinforce body
vessels and to
prevent restenosis following angioplasty in the vascular system. Additionally,
stents
may be used in the treatment of aortic aneurysms, by providing strength to a
weakened vascular wall. They have also been implanted in other body lumens,
such
as urinary tracts and bile ducts. Stents are generally tubular structures that
may be
radially expandable between an unexpanded size and an expanded size greater
than
the unexpanded size. Therefore, a stent may be inserted through a body lumen
in an
unexpanded state and then expanded at a specific location within the lumen to
an
expanded state.
As the use of stents in a variety of medical procedures is gaining widespread
acceptance, it is desirable to provide improved methods of manufacturing
stents in
order to increase efficiency, reduce costs, and/or minimize material waste.
The
disclosed stents and accompanying methods of manufacturing a stent may be
deemed
advantageous in view of the increased usage of stents during medical
procedures.
Summary
The invention is directed to a stent manufactured from a tubular member. The
stent may be cut from a tubular member such that a pattern and an opening
extending
from the first end to the second end of the tubular member are cut therein.
The
opening may define a first edge and a second edge through the wall of the
tubular
member. One or more connectors may be cut along either the first or second
edge and
may extend into the opening.
Accordingly, a process of making a stent from a tubular member is disclosed.
A tubular structure having a pattern configured to provide expansion and an
opening
defining a first edge and a second edge may be cut from a tubular member. The
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opening may be cut such that one or more connectors may be cut along either
the first
or second edge and extend into the opening.
Brief Description of the Drawings
The invention may be more completely understood in consideration of the
following detailed description of various embodiments in connection with the
accompanying drawings, in which:
Figure 1A is a perspective view of an exemplary stent within the scope of the
invention;
Figure 1B is a perspective view of an exemplary embodiment of a pattern cut
in a tubular member to form a stent within the scope of the invention;
Figure 1C is a cut away view of the tubular member of Figure 1B, more easily
showing an opening cut along the tubular member including exemplary connectors
within the scope of the invention;
Figure 1D is a perspective view of the tubular structure formed after
expansion
of the tubular member of Figure 1B;
Figures 1E-1F are enlarged views of exemplary embodiments of connectors
within the scope of the invention;
Figure 2A is a perspective view of another exemplary stent within the scope of
the invention including a plurality of connectors extending across an opening;
Figure 2B is a perspective view of an exemplary embodiment of a pattern cut
in a tubular member to form a stent within the scope of the invention;
Figure 2C is a cut away view of the tubular member of Figure 2B, more easily
showing an opening cut along the tubular member including exemplary connectors
within the scope of the invention;
Figure 2D is an enlarged view of an exemplary connector extending across an
opening cut in a tubular member within the scope of the invention;
Figure 3A is a perspective view of another exemplary stent within the scope of
the invention;
Figure 3B is a perspective view of an exemplary embodiment of a pattern cut
in a tubular member to form a stent within the scope of the invention;
Figure 3C is a cut away view of the tubular member of Figure 3B, more easily
showing an opening cut along the tubular member including exemplary connectors
within the scope of the invention;
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Figures 3D-3G are enlarged views of exemplary embodiments of connectors
comprising tooling nodes within the scope of the invention;
Figure 4A is a perspective view of an exemplary embodiment of another
tubular member to form a stent within the scope of the invention;
Figure 4B is a cut away view of the tubular member of Figure 4A, more easily
showing an opening cut along the tubular member including a spine extending
along
the opening within the scope of the invention;
Figure 5 is a plan view illustrating an exemplary device for elongating and/or
forming the tubular member of Figure 3B;
Figure 6 is a plan view illustrating forming an exemplary stent having
overlapping edges witliin the scope of the invention; and
Figure 7 is a plan view illustrating forming an exemplary stent having a C-
shape within the scope of the invention.
Detailed Description
As used in this specification and the appended 'claims, the singular forms
"a",
"an", and "the" include plural referents unless the content clearly dictates
otherwise.
As used in this specification and the appended claims, the term "or" is
generally
employed in its sense including "and/or" unless the content clearly dictates
otherwise.
The following detailed description should be read with reference to the
drawings in which similar elements in different drawings are numbered the
same.
The detailed description and the drawings, which are not necessarily to scale,
depict
illustrative embodiments and are not intended to limit the scope of the
invention. The
illustrative embodiments depicted are intended only as exemplary. Selected
features
of any illustrative embodiment may be incorporated into an additional
embodiment
unless clearly stated to the contrary.
Referring now to the drawings, and particularly Figure 1A, illustrates an
exemplary stent 10 within the scope of the invention. As discussed herein,
stent 10
may be formed from a tubular member. Stent 10 may be manufactured from a
variety
of materials. For example, stent 10 may include a nickel-titanium alloy, such
as a
shape memory material commonly referred to as nitinol, which may provide the
stent
with superelastic properties, psuedoeleastic properties, or linear elastic
properties.
Other suitable materials for the stent include, but are not limited to,
stainless steels
and their alloys, composites, platinum enhanced stainless steel, layered
materials,
niobium (Nb), zirconium (Zr), Nb-Zr alloys, tantalum (Ta), platinum (Pt),
titanium
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(Ti), gold (Au), silver (Ag), magnesium (Mg), and alloys and compositions
comprising the same. Polymers, polymer composites, and combinations and
mixtures
thereof, may also be used. Stent 10 may be treated or coated with an anti-
tllrombogenic agent, an anti-proliferative agent, an anti-inflammatory agent,
or an
anti-coagulant. Additionally or alternatively, stent 10 may be treated or
coated with a
medication, such as a time-release drug. Stent 10 may also desirably have
radiopaque
characteristics for visualization on a fluoroscopy device, which may aid in
proper
placement of the stent 10 during a medical procedure. For example, stent 10
may be
doped with, plated with, or otherwise include a radiopaque material.
Radiopaque
materials are understood to be materials capable of producing a relatively
bright
image on a fluoroscopy screen or another imaging technique during a medical
procedure. Some examples of radiopaque materials include, but are not limited
to,
gold (Au), platinum (Pt), palladium (Pd), tantalum (Ta), tungsten (W), plastic
material
loaded with radiopaque filler, and the like. Stent 10 may, alternatively or
additionally, include MRI compatible materials and/or be coated witli one or
more
MRI compatible coatings.
Now referring to Figure 1B, stent 10 may be formed from a tubular member
50. Tubular member 50 may be a thin-walled tube having appropriate dimensions.
A
pattern 60 may be cut into tubular member 50. Although a relatively simple
pattern of
interconnected segments is shown in Figure 1B, numerous patterns of varying
design
and complexity are possible. A selected pattern 60 may dictate the degree of
expansion and/or flexibility of stent 10. Pattern 60 may be cut into tubular
member
50 by a laser cutting device controlled by a computer automated system, for
example
a computer numerically controlled (CNC) machine. Such a laser cutting device
may
be able to replicate a very intricate and precise pattern 60. A laser beam,
for example,
or a laser beam traveling through a fluid jet may be directed at the tubular
member 50.
The tubular member 50 may be translated and/or rotated relative to the
position of the
laser, or vise versa, in order to cut the desired pattern 60. The lumen 20 of
the tubular
member 50 may be subjected to a fluid column to flush dross from the tubular
meinber, provide cooling to the cuttiiig zone, and/or deflect the laser beam
from the
opposing wall of the tubular member 50 during the cutting process. The fluid
column
may be a gas and/or a liquid, and a single or multiple fluid columns may be
provided
through the lumen 20. For example, two fluid columns may be separated by a
tubular
mandrel disposed within the lumen 20 of the tubular member 50, such that a
first
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colunm of fluid is positioned in the annular space between the tubular member
50 and
the mandrel and a second fluid column is positioned in the lumen of the
tubular
mandrel. Such a laser cutting process is disclosed in U.S. Patent No.
6,696,666
entitled Tubular Cutting Process and System, which is herein incorporated by
reference in its entirety. Other cutting techniques may include optical
etching,
chemical etching, electron beam ablation, material deposition, as well as
other laser
ablation techniques.
Figure 1C shows a cut away view of tubular member 50. An opening 30 may
be cut through tubular member 50 during the cutting process or during an
additional
cutting process. Opening 30 may extend from the first end 22 of the tubular
member
50 to the second end 24 of the tubular member 50. Opening 30 defines a first
edge 32
and an opposing second edge 34 of the wall of the tubular member 50 and may
extend
from the first end 22 to the second end 24. Edges 32, 34 may extend from the
outer
surface to the inner surface of the wall of the tubular member 50. Opening 30
may
extend substantially longitudinally along tubular member 50. However, opening
30
may extend helically around the tubular member 50, providing a helical
configuration
of opening 30 along the length of tubular member 50, undulate along at least a
portion
of the length of tubular member 50, or otherwise extend along tubular member
50 in a
regular or irregular manner.
One or more connectors 40 may be cut along the first edge 32 and extend into
the opening 30. Additionally or alternatively, one or more connectors 40 may
be cut
along the second edge 34 and extend into the opening 30. Connectors 40 may be
positioned adjacent one another and extend from opposing edges 32, 34 of the
tubular
member 50, or connectors 40 may be alternated along at least a portion of the
length
of the opening 30. A connector 40 may extend from the first edge 32 toward the
second edge 34 and be attached to a connector 40 extending from the second
edge 34
toward the first edge 32, thus creating one continuous connector 40 spanning
the
opening 30 between the first edge 32 to the second edge 34. Alternatively,
opposing
connectors 40 may not be attached to one another, thus a space may remain
between
opposing connectors 40.
Figures 1E and 1F show two possible embodiments of connector 40. As
shown in Figure 1E, connector 40 may be a serpentine or zig-zag shaped strut
extending from the first edge 32 to the second edge 34. The shape and size of
connector 40 may be dimensioned such that the connector 40 may be elongated a
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predetermined amount during a subsequent expansion process. Figure 1F shows
another embodiment of a connector 40 similar to that shown in Figure 1E.
Connector
40 may have a serpentine or zig-zag shape having a grasping portion, such as
an
eyelet 42. The eyelet 42 may be substantially located in the central portion
of the
connector 40, or eyelet 42 may be located at any position along connector 40.
An
aperture, such as hole 44 may extend through eyelet 42. Hole 44 may allow a
tooling
device to be coupled or otherwise be engaged with the connector 40. Eyelet 42
may
be used to retain and/or manipulate the stent 10 during a subsequent
manufacturing
process. The aperture may extend through eyelet 42 or the aperture may be a
recess
or pocket with a terminus within the thickness of connector 40. Other
configurations
of connectors, such as connectors with a grasping portion such as tabs, slots,
slits,
projections, grooves, loops, or hooks are contemplated to be within the scope
of the
invention.
Referring now to Figure 1D, the tubular member 50 may be expanded
subsequent to cutting the pattern 60 in the tubular member 50. The resulting
tubular
structure 70 may have an outer diameter greater than the initial diameter of
the tubular
member 50. Tubular member 50 may be expanded by placing a mandrel through the
lumen 20 of tubular member 50 or by other means for expanding the tubular
member
50. The expanded tubular structure 70 may be a mesh 65 including a plurality
of
interconnected segments 66 formed from the material of the tubular member 50
remaining after cutting the pattern 60 in the tubular member 50. The
interconnected
segments 66 are spaced farther apart after expansion to create the mesh 65
having a
plurality of interstices 67 disposed therein. The specific pattern 60 cut into
the tubular
member 50 and/or the material used may dictate the degree of expansion of the
tubular structure 70.
As a result of the expansion of the tubular structure 70, connectors 40 may
become elongated. Connectors 40 may provide support and/or continuous
structure in
order to ensure uniform, non-uniform or an otherwise predetermined expansion
of the
tubular structure 70. Therefore, the tubular shape of the structure 70 may be
maintained throughout the expansion process. For example, connectors 40 may be
configured to have a degree of expansion similar to that of the pattern 60.
Therefore,
the circumferential expansion of the tubular structure 70 may be uniform at
all
locations around the circumference of the tubular structure 70. Connectors 40
may be
configured to provide visual confirmation of proper expansion, such as when
the
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connectors 40 are sufficiently straightened. Therefore, the tubular structure
70 may
reach its proper expanded dimensions when the connectors 40 have reached a
sufficient elongated configuration. Alternatively, connectors may be
configured to
provide visual confirmation of proper expansion of the tubular member 50 at
the point
wliere elongation of connectors 40 commences or at the point of fracture of
connectors 40 from tubular member 50.
Connectors 40 may be sufficiently frangible such that connectors 40, or a
portion thereof, may be separated from the tubular structure 70 subsequent
expansion
of the tubular structure 70, or connectors 40 may be retained with the tubular
structure
70. Connectors 40 may be removed during a subsequent process using mechanical,
electrical or chemical techniques. A cutting process may be used to provide
separation from the edge 32, 34 of the structure 70. For example, a laser
ablation
teclinique may be used to separate the connectors 40 from the tubular
structure 70 or
weaken the interface between connector 40 and tubular structure 70. Connectors
40
may be removed by mechanically cutting, snipping, breaking or otherwise
severing
the connectors, or by grinding, sandblasting or otherwise eroding away
material.
Additionally or alternatively, a chemical etching or electro-polishing process
may be
used to remove connectors 40 or a portion thereof. Connectors 40 may be
dissolved
or weakened during a subsequent manufacturing process in which a portion of
the
material is eroded away.
Figure 2A shows a tubular structure 170 forming another stent 110, similar to
stent 10. Stent 110 may be similarly formed from a tubular member 150. Tubular
structure 170, shown in Figure 2A, includes connectors 140 coupled to stent
110
subsequent to expansion of the stent 110. However, connectors 140 may be
removed
from stent 110 during or subsequent the expansion process, as discussed
herein. With
connectors 140 removed, stent 110 may substantially replicate stent 10
illustrated in
Figure lA. As shown in Figure 2B, a pattern 160 may be cut through tubular
member
150. Additionally, an opening 130 may extend from the first end 122 to the
second
end 124 of the tubular member 150. As shown in the cut away view in Figure 2C,
the
opening 130 defines a first edge 132 and a second edge 134 of the wall of the
tubular
member 150. One or more connectors 140 may be cut in the tubular member 150
such that connector 140 extends across the opening 130 from the first edge 132
to the
second edge 134. Connector 140, which may more clearly be understood from
Figure
2D, may be connected to opposing edges 132, 134 of the tubular member 150.
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Connector 140 may have one or more apertures, such as holes 144 used to retain
and/or manipulate the tubular structure 170 during a manufacturing process.
The
aperture may extend through the wall of tubular structure 170 or the aperture
may be a
recess or pocket with a terminus within the wall of tubular structure 170.
Other
configurations of connectors, such as connectors having a grasping portion
including
tabs, slots, slits, projections, grooves, loops, or hooks are contemplated to
be within
the scope of the invention. Hole 144 may be located in the central portion of
connector 140, or hole 144 may be located at another location of connector
140.
Connector 140 may provide support and/or continuous structure in order to
ensure
uniforni, non-uniform or otherwise proper expansion of the tubular structure
170
during expansion of the stent 110. Therefore, the tubular shape of the
structure 170
may be maintained tliroughout the expansion process. Connector 140 may allow
the
tubular structure 170 to retain a uniform diameter during expansion of the
stent 110.
The connection between the connector 140 and the edge 132, 134 of the tubular
structure 170 may be a weakened zone or an otherwise frangible region, such
that
prior to providing the finished product stent 110, connector 140 may be
removed.
The connector 140, or a portion thereof, may be removed by mechanically
cutting,
snipping, breaking, grinding, sandblasting, laser ablation, chemical etching,
electro-
polishing, or other processes wherein the connector 140 is separated, eroded
or
dissolved from the tubular structure 170.
Figure 3A illustrates a stent 210 similar to stent 10 in an expanded
configuration. Stent 210 may include one or nzore connectors 240, as discussed
herein. As shown in Figure 3B, stent 210 may be cut from a tubular member 250
such as discussed above. An opening 230, which may more easily be shown in the
cut away view of Figure 3C, may be cut along tubular member during a cutting
process and may extend from the first end 222 to the second end 224 of the
tubular
member 250. One or more connectors 240 may be cut in tubular member 250, such
that connectors 240 extend from edge 232, 234 of tubular member 250 into
opening
230. As more clearly shown in Figures 3D-3G, connectors 240 may be tooling
nodes.
Connectors 240 may be configured to be coupled to or otherwise engaged with a
tooling apparatus. Connectors 240 may be used to retain and/or manipulate the
tubular structure 270 during a subsequent manufacturing process. As shown in
Figure
3D, connectors 240 may extend from edge 232, 234 toward an opposing edge.
However, connectors 240 may not be connected to one another. Instead, a gap
may
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be maintained between adjacent connectors 240. Although comiectors 240 are
shown
adjacent one another, opposing connectors 240 may alternate along the length
of the
tubular structure 270, such as shown in Figure 3G. Alternatively, connectors
240 may
extend toward an adjacent connector 240 and be connected to.an adjacent
connector
240, as shown in Figure 3E. The connection between adjacent connectors 240 may
be
a weakened zone or an otherwise frangible region. For example, the connection
may
be a region of reduced cross sectional area or an area scored during a cutting
process.
Such a configuration of connectors 240 may be separated during a subsequent
manufacturing process. For example, connectors 240 may be separated by
mechanically cutting, snipping, breaking, grinding, sandblasting, laser
ablation,
chemical etching, or electro-polishing. Figure 3F illustrates yet another
embodiment
of connectors 240. A strut 242 may bridge a pair of connectors 240 extending
from
opposing edges 232, 234 of the tubular structure 270. Strut 242 may have a
serpentine or zig-zag shape or otherwise have an extendable shape. During an
expansion process, strut 242 may be elongated similar to connectors 40
discussed
above regarding Figures lA-1F. Therefore, strut 242 may provide support and/or
continuous structure around the circumference of the tubular structure 270 in
order to
ensure uniform, non-uniform or otherwise proper expansion of the tubular
structure
270. Therefore, the tubular shape of the structure 270 may be maintained
throughout
the expansion process. Elongation of the strut 242 may be a visual indicator
of proper
expansion of the tubular structure 270. Sufficient elongation of the strut 242
may
indicate the tubular structure 270 has reached its predetermined expanded
configuration. Subsequent to expansion of the tubular structure 270, strut 242
may be
removed by mechanical, electrical or chemical means. For example, strut 242
may be
removed by laser ablation, cutting, snipping, breaking, grinding,
sandblasting, or prior
to or during a chemical etching or electro-polishing process.
Alternatively or additionally, a wire or filament may be extend between
connectors 240 to join opposing or alternating connectors. For exanlple, the
wire may
be laced or threaded through holes 244 of connectors 240. The wire may be a
temporary connector which extends across opening 230. The wire may
substantially
restrain separation of opposing edges 232, 234 or tubular structure 270. The
wire may
provide support and/or continuous structure to the tubular member 250 to
ensure
uniform, non-uniform or an otherwise predetermined expansion of the tubular
structure 270. Therefore, the tubular shape of the structure 270 may be
maintained
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throughout the expansion process. Subsequent expansion and/or forming of the
tubular structure 270, the wire may be removed from the structure 270. The
wire may
be removed by mechanical, electrical or chemical means. The wire may be
dissolvable whereby it is dissolved with a solvent, by a thermal process, a
chemical
process or an electrical process. The wire may have characteristics similar to
a
dissolvable suture. Alternatively, wire may be mechanically removed by a
laser,
grinding, sandblasting, cutting, snipping, etching, breaking, or by another
process.
Additionally or alternatively, connectors, such as connectors 240, having an
aperture such as a recess, may include an adhesive. The adhesive, which may be
disposed in the recess of the connector 240, may be used to secure one portion
of the
tubular structure 270 with another portion of the tubular structure 270. For
example,
one connector 240 may be adhesively secured to an opposing connector 240. The
adhesive may also be used to secure the tubular structure 270 to another
apparatus for
forming and/or processing of the tubular structure 270. The adhesive may be
dissolvable, or otherwise provide temporary securement, or the adhesive may be
intended to provide permanent securement.
Alternatively or additionally, an apparatus such as a mandrel having hooks,
tines, clips, or other engagement means, may be used to engage connectors 240.
The
mandrel may substantially couple opposing edges 232, 234 such that edges 232,
234
are restrained from separation during expansion of the tubular structure 270.
For
example, the hooks of the mandrel may be inserted in holes 244 of connectors
240.
The mandrel may provide support and/or continuous structure to the tubular
member
250 to ensure uniform, non-uniform or an otherwise predetermined expansion of
the
tubular structure 270. Therefore, the tubular shape of the structure 270 may
be
maintained throughout the expansion process. Subsequent expansion and/or
forming
of the tubular structure 270, the mandrel may be removed from the structure
270.
Although the mandrel may engage cormectors 240, mandrel may also engage
another
portion of the stent to restrain separation of opposing edges 232, 234.
Figure 4A shows another embodiment of a tubular member 350 for forming a
stent within the scope of the invention. As more easily shown in Figure 4B,
tubular
member 350 may be cut with an opening 330 extending from a first end 322 to a
second end 324. A connecting spine 345 may be disposed along opening 330. One
or
more connectors 340 may extend from edge 332, 334 to connecting spine 345. An
electrical current of a sufficient magnitude may be applied to the connecting
spine
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345 to remove the connectors 340. The connectors 340 may be sufficiently thin
relative to the other portions of the tubular member 350, such that the
magnitude of
the electrical current and/or the geometry of the connectors 340 is sufficient
to
remove the connectors 340 from the stent. Alternatively, an electrical current
may be
directly applied to the connectors 340, thus alleviating the need for the
connecting
spine 345.
Connectors 240, characterized as tooling nodes as shown in Figures 3D-3G,
may be used to retain and manipulate tubular structure 250 during a subsequent
process. For example, Figure 5 illustrates an exemplary process wherein a
tooling
device 400 is coupled to or otherwise engaged with one or more connectors 240.
Tooling device 400 may be manipulated such that tubular member 250 is unrolled
and/or elongated into a substantially planar sheet 280. Thus, interconnected
segments
266 may be sufficiently directed away from one another to form a mesh 265 with
a
plurality of interstices 267 disposed thereon. While elongated in a
substantially
planar sheet 280, the sheet may be subjected to one or more additional
processes, such
as a heat treatment process, a cleaning process, a chemical etching process,
an electro-
polishing process, a quenching process, a coating process, or another chosen
process.
Sheet 280 may undergo a forming process, wherein the sheet 280 is rolled into
a
tubular stent. Additional processes, such as a heat treatment ' process, a
cleaning
process, an electro-polishing process and/or a coating process may follow
rolling the
sheet 280 into a tubular stent. Tooling device 400, or an additional tooling
device,
may be used to re-roll or otherwise form the sheet 280 into a tubular stent or
an
intermediate form. For example, a mandrel having clips, tines, hooks or other
means
of engaging the structure may be used to expand, roll, form, wrap or otherwise
manipulate the structure to form a stent.
Any one of the previously disclosed tubular structures may further be rolled
into a coil stent. As shown in Figure 6, a stent, such as stent 10 may be
wrapped such
that the first edge 32 of the tubular structure 70 overlaps the second edge
34. The
degree of overlap may be determined by the profile necessary to provide
sufficient
clearance through a body lumen, such as a blood vessel, and/or the degree of
expansion necessary to provide sufficient patency of a body lumen. A tooling
device,
such as a mandrel, may be coupled to one or more connectors 40 along one edge
of
stent 10 and rotated such that the first edge 32 is urged toward the second
edge 34.
Thus the stent 10 may be wrapped into a chosen tubular shape such as a coiled
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overlapping configuration. However, stent 10 may be rolled into a coil using
otlier
mechanical means. Alternatively, stent 10 may be rolled such that edge 32
substantially abuts edge 34 to form a generally continuous tubular structure.
Edge 32
may be secured to edge 34 by welding, brazing, soldering, bonding, adhesive,
mechanically coupling, crimping, or the like, or edges 32, 34 may remain
unconnected.
Alternatively, one of the previously disclosed tubular structures may be
formed in a C-shape such as shown in Figure 7. A stent 10 having a C-shape may
be
readily expanded within a lumen to provide necessary patency of the lumen. The
opening 30 extending along the length of the steiit 10 allows opposing edges
32, 34 to
deflect away from one another when stent 10 is allowed to expand within a
lumen.
Stent 10 may be formed into a C-shape during a subsequent forming/rolling
process,
or C-shape may be the result of cutting a tubular member 50 and expanding into
a
tubular structure 70 having a longitudinal, helical, undulating or otherwise
elongate
opening 30 as discussed above.
Any one of the previously described stent forming processes may include one
or more further processing steps. For example, the tubular member may be
subjected
to a cleaning process to remove dross or residue subsequent a cutting process.
For
instance, an alcohol and/or water solution may be used to clean foreign
material from
the tubular structure. A chemical etching process may be used to remove
connectors
and/or other material from the tubular structure to provide a surface with no
sharp
edges or burrs. An electro-polishing process may be used to reduce the surface
roughness of the machined tubular member and provide a stent having a
substantially
smooth outer surface. An electro-polishing process, or similar electrical
process, may
also be used to dissolve or otherwise separate a connector from the stent. For
example, an electro-polishing process may dissolve a percentage of the mass of
the
material forming the stent. By dimensioning the connectors relatively small
compared to the material of the interconnected segments of the stent, the
connectors
will completely dissolve, erode or otherwise be separated from the stent
without fully
dissolving the interconnected segments during an electro-polishing process. An
electrical current of a sufficient magnitude may be applied to the connectors
to
separate the connectors from the stent. Additionally, a stent may be subjected
to one
or more heat treating processes in order to remove residual stresses and/or
provide
favorable characteristics to the stent, such as shape memory properties.
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One illustrative stent forming process may include a plurality of processes.
Initially a stent may be laser cut from a tubular member as discussed above.
The stent
may then be subjected to a chemical etching and/or electro-polishing process
to
remove residue, connectors and/or rough edges remaining after being cut from
the
tubular member. Alternatively or additionally, the stent may be placed in an
ultrasonic cleaning process. Next, the stent may be expanded or otherwise
formed by
rolling and/or tucking the ends of the stent. Once formed, the stent may be
heat
treated to remove any residual stresses and/or provide shape memory properties
and
then quenched. The stent may then undergo a final cleaning process to remove
any
remaining residue. Additional processes, such as chemical etching, electro-
polishing,
cleaning or heat treating, may be included throughout. For example, the stent
may be
subjected to a chemical etching or electro-polishing process subsequent to
being
expanded in order to remove temporary connectors from the stent.
It is contemplated that the disclosed process of forming a stent may be
substantially used to form other similar products from a tubular member. For
example, a filter mesh or frame for an intravenous filter or distal protection
device
may be formed utilizing the disclosed process.
Those skilled in the art will recognize that the present invention may be
manifested in a variety of forms other than the specific embodiments described
and
contemplated herein. Accordingly, departure in form and detail may be made
without
departing from the scope and spirit of the present invention as described in
the
appended claims.
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