U.S. patent application number 10/662792 was filed with the patent office on 2004-11-18 for stent having a multiplicity of undulating longitudinals.
Invention is credited to Fischell, David R., Fischell, Robert E., Fischell, Tim A..
Application Number | 20040230294 10/662792 |
Document ID | / |
Family ID | 22748604 |
Filed Date | 2004-11-18 |
United States Patent
Application |
20040230294 |
Kind Code |
A1 |
Fischell, Robert E. ; et
al. |
November 18, 2004 |
Stent having a multiplicity of undulating longitudinals
Abstract
A method for implanting a balloon expandable stent at a site
within a passageway of a curved coronary article. The stent
includes at least two longitudinally spaced apart circumferential
rings. At least one longitudinally extending connector extends
between adjacent rings. The connector has at least one turn back
portion that can expand or contract in length while being passed
through a curved passageway. The stent is disposed on a stent
delivery catheter having an inflatable balloon. The stent delivery
catheter and the stent is delivered through the passageway to the
site of implementation with the connector member expanding or
contracting in length to facilitate delivery and placement of the
stent. The stent is expanded at the site of implantation by
inflating the balloon to force the stent radially outward against
the wall of the coronary artery.
Inventors: |
Fischell, Robert E.;
(Dayton, MD) ; Fischell, David R.; (Fair Haven,
NJ) ; Fischell, Tim A.; (Nashville, TN) |
Correspondence
Address: |
WOOD, PHILLIPS, KATZ, CLARK & MORTIMER
500 W. MADISON STREET
SUITE 3800
CHICAGO
IL
60661
US
|
Family ID: |
22748604 |
Appl. No.: |
10/662792 |
Filed: |
September 15, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10662792 |
Sep 15, 2003 |
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10345531 |
Jan 16, 2003 |
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6716240 |
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10345531 |
Jan 16, 2003 |
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09596074 |
Jun 16, 2000 |
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6547817 |
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09596074 |
Jun 16, 2000 |
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09263518 |
Mar 5, 1999 |
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6086604 |
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09263518 |
Mar 5, 1999 |
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08864221 |
May 28, 1997 |
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5879370 |
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08864221 |
May 28, 1997 |
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08202128 |
Feb 25, 1994 |
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5643312 |
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Current U.S.
Class: |
623/1.16 |
Current CPC
Class: |
A61F 2002/91533
20130101; A61F 2/91 20130101; A61F 2210/0019 20130101; A61F 2/915
20130101; A61F 2/90 20130101; A61F 2002/825 20130101; A61F 2/844
20130101; A61F 2002/9155 20130101 |
Class at
Publication: |
623/001.16 |
International
Class: |
A61F 002/06 |
Claims
1-35 (Cancelled)
36: A generally cylindrical stent for delivery to a coronary
artery, said stent having a first pre-deployment diameter and a
second deployed diameter, said stent being cut from a pre-existing
metal tube and having a circumference and a longitudinal axis, said
stent having sufficient flexibility to permit percutaneous delivery
to a curved coronary artery; said stent in its first diameter
comprising: at least two longitudinally spaced apart
circumferential rings, each of said circumferential rings defining
a portion of the circumference of the stent, each of said
circumferential rings having at least two peak segments and at
least two valley segments; and at least one connector having a
first end portion and a second end portion, said first end portion
being fixedly connected to a peak segment of a first of said
circumferential rings and said second end portion being fixedly
connected to a valley segment of a circumferential ring adjacent to
said first circumferential ring, at least one of said first and
second end portions of said connector including a straight segment
that is substantially parallel to the longitudinal axis of the
stent, said connector having at least one circumferentially
extending generally U-shaped turn back portion between its first
and second end portions that can expand or contract in length, as
measured by the straight line distance between its first and second
end portions, while being passed through a curved coronary
artery.
37: The stent of claim 36, wherein the turn back portion has a
first end point and a second end point, and a line drawn from the
first end point to the second end point is generally parallel to
the longitudinal axis of the stent.
38: The stent of claim 37, wherein said line drawn from the first
end point to the second end point remains generally parallel to the
longitudinal axis of the stent when the stent is expanded into its
second deployed diameter.
39: The stent of claim 36, wherein the stent is laser-cut from a
pre-existing metal tube.
40: The stent of claim 36, wherein at least three circumferentially
spaced connectors connect said first circumferential ring and a
circumferential ring adjacent to said first circumferential
ring.
41: The stent of claim 36, wherein said connector has at least two
turn back portions between its first and second end portions.
42: The stent of claim 36, wherein each of said first and second
end portions of said connector includes a straight segment and a
straight line drawn therethrough is substantially parallel to the
longitudinal axis of the stent.
43: The stent of claim 36, wherein at least one turn back portion
of said connector is located entirely within a valley segment of a
circumferential ring.
44: The stent of claim 36, wherein said connector includes at least
two generally U-shaped turn back portions that open in opposite
directions.
45: A generally cylindrical stent for delivery to a coronary
artery, said stent having a first pre-deployment diameter and a
second deployed diameter, said stent being cut from a preexisting
metal tube and having a longitudinal axis, said stent having
sufficient flexibility to permit percutaneous delivery to a curved
coronary artery; said stent in its first diameter comprising: a
multiplicity of closed perimeter cells, each of said cells
including at least one generally U-shaped turn back portion having
a first end point and a second end point wherein a line drawn from
the first end point to the second end point is generally parallel
to the longitudinal axis of the stent.
46: The stent of claim 45, wherein said line drawn from the first
end point to the second end point remains generally parallel to the
longitudinal axis of the stent when the stent is expanded into its
second deployed diameter.
47: The stent of claim 45, wherein each of said cells has at least
one circumferentially adjacent cell which shares one generally
U-shaped turn back portion.
48: The stent of claim 45, wherein the stent includes at least two
longitudinally spaced apart circumferential rings, each of said
circumferential rings having at least two peak segments and at
least two valley segments; and at least one connector having a
first end portion and a second end portion, said first end portion
being fixedly connected to a peak segment of a first of said
circumferential rings and said second end portion being fixedly
connected to a valley segment of a circumferential ring adjacent to
said first circumferential ring, said connector having at least one
of said generally U-shaped turn back portions, wherein each of said
closed perimeter cells includes at least a portion of two
circumferentially adjacent rings and at least one connector.
49: The stent of claim 45, wherein the stent is laser-cut from a
pre-existing metal tube.
50: The stent of claim 45, wherein each of said cells includes at
least two generally U-shaped turn back portions.
51: A generally cylindrical stent for delivery to a coronary
artery, said stent having a first pre-deployment diameter and a
second deployed diameter, said stent being cut from a pre-existing
metal tube and having a longitudinal axis, said stent having
sufficient flexibility to permit percutaneous delivery to a curved
coronary artery; said stent in its first diameter comprising: at
least two longitudinally spaced apart circumferential rings and at
least one connector, said connector having a first end portion
fixedly connected to a first of said circumferential rings and a
second end portion fixedly connected to a circumferential ring
adjacent to said first circumferential ring, said connector
including at least one generally U-shaped turn back portion having
a first end point and a second end point so that a line drawn from
the first end point to the second end point is generally parallel
to the longitudinal axis of the stent so as to define a
multiplicity of perimeter cells that include at least a portion of
two circumferentially adjacent rings and at least one
connector.
52: The stent of claim 51, wherein said line drawn from the first
end point to the second end point remains generally parallel to the
longitudinal axis of the stent when the stent is expanded into its
second deployed diameter.
53: The stent of claim 51, wherein the stent is laser-cut from a
pre-existing metal tube.
54: The stent of claim 51, wherein at least three circumferentially
spaced connectors connect said first circumferential ring and a
circumferential ring adjacent to said first circumferential
ring.
55: The stent of claim 51, wherein said connector has at least two
turn back portions between its first and second end portions.
56: The stent of claim 51, wherein said connector includes at least
two generally U-shaped turn back portions that open in opposite
directions.
Description
FIELD OF THE INVENTION
[0001] This invention is in the field of stents for maintaining
patency of any one of a multiplicity of vessels of the human
body.
BACKGROUND OF THE INVENTION
[0002] In the last decade, many different designs of stents have
been used to maintain patency of arteries and other vessels of the
human body. In all such devices, hoop strength is an important
characteristic. Specifically, the stent must have enough hoop
strength to resist the elastic recoil exerted by the vessel into
which the stent is placed. The Mass stent described in the U.S.
Pat. No. 4,553,545 and the Dotter stent described in U.S. Pat. No.
4,503,569 are each open helical coils. The Palmaz stent described
in the U.S. Pat. No. 4,733,665 is of the "chinese finger" design.
The Gianturco-Rubin stent currently sold by Cook, Inc, is another
stent design which like the stents of Mass, Dotter and Palmaz does
not have any closed circular member to optimize hoop strength.
[0003] The ideal arterial stent utilizes a minimum wire size of the
stent elements to minimize thrombosis at the stent site after
implantation. The ideal arterial stent also possess sufficient hoop
strength to resist elastic recoil of the artery. Although the
optimum design for maximizing hoop strength is a closed circular
structure, no prior art stent has been described which has a small
diameter when percutaneously inserted into a vessel and which
expands into the form of multiplicity of closed circular structures
(i.e. rings) when expanded outward against the vessel wall.
BRIEF SUMMARY OF THE PRESENT INVENTION
[0004] The present invention is an expandable stent that can be
used in an artery or any other vessel of the human body which, when
expanded, forms a multiplicity of generally circular rings whose
closed structure optimizes hoop strength so as to minimize elastic
recoil of the vessel into which the stent is inserted. Furthermore,
the structure of the stent in the present invention is initially in
the form of folded ellipses or ovals which can be formed to a small
diameter for percutaneous insertion by means of a stent delivery
catheter. The ovals are joined to each other by either a straight
or undulating shaped wires which are called "longitudinals" which
serve to space the deployed rings within the vessel. Straight
longitudinals are used in straight vessels and undulating
longitudinals can be employed in either straight or highly curved
vessels such as some coronary arteries.
[0005] Thus, an object of this invention is to provide a stent
having a maximum hoop strength by the employment of closed,
generally circular structures which are in fact rings.
[0006] Another object of this invention is that the rings are
initially in the form of ovals that can be folded to fit onto a
cylindrical structure at a distal portion of a stent delivery
catheter.
[0007] Still another object of this invention is that the fully
deployed rings are spaced apart by means of longitudinals which are
either straight of undulating wires that are placed to be generally
parallel to the longitudinal axis of the vessel into which the
stent is deployed.
[0008] Still another object of this invention is that the
pre-deployment stent structure is formed as a single piece out of a
metal tube having a smaller inside diameter as compared to the
outside diameter of an expandable balloon onto which the
pre-deployment stent is mounted.
[0009] These and other important objects and advantages of this
invention will become apparent from the detailed description of the
invention and the associated drawings provided herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a side view of the stent after it has been
deployed; i.e., in its post-deployment form.
[0011] FIG. 2 is a transverse cross section of section 2-2 of FIG.
1 illustrating how the longitudinals are joined to the rings.
[0012] FIG. 3 is a cross section at section 3-3 of FIG. 2 showing
the joining of a single ring to the longitudinals.
[0013] FIG. 4 is a side view of the stent prior to being mounted
onto a stent delivery catheter, i.e., in the form of an initial
structure.
[0014] FIG. 5 is a transverse cross section of section 5-5 of FIG.
4 illustrating how the longitudinals are joined to the ovals.
[0015] FIG. 6 is a side view of a pre-deployment form of the stent
structure in which the ovals have been folded into a small diameter
cylinder that is placed around a deflated balloon situated near the
distal end of a stent delivery catheter.
[0016] FIG. 7 is a partial side view of a pre-deployment stent
structure showing only two of a multiplicity of folded ovals formed
around an expandable balloon in which the ovals are folded in an
alternative manner as compared with FIG. 6.
[0017] FIG. 8 is a side view of a post-deployment stent structure
which utilizes two undulating longitudinals on opposite sides of
the stent for improved placement in curved vessels.
[0018] FIG. 9 is a side view of a stent as etched out of a small
diameter metal cylinder as a single piece of metal.
DETAILED DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a side view of the cylindrical stent 1 of the
present invention shown in its post-deployment configuration. The
stent 1 has a multiplicity of rings 2 which are spaced apart by
four wires called longitudinals. As seen in FIGS. 1 and 2, at the
top of the stent is longitudinal 4T, at the bottom is longitudinal
4B, at the left side is longitudinal 4L and at the right side is
longitudinal 4R. Although FIGS. 1 and 2 show 7 rings and 4
longitudinals, it is apparent that the stent can be made longer by
adding rings or increasing the separation between rings. In a
similar manner, the stent can be made shorter by reducing the
number of rings or decreasing the spacing between rings. Also
variable spacing of the rings is envisioned for accomplishing a
variety of purposes including increased hoop strength at a
particular section of the stent. Also, it is envisioned that the
two or more longitudinals could be utilized for this stent design
with a maximum number being 32.
[0020] FIGS. 2 and 3 illustrate the joining of the longitudinals to
the rings. Specifically the longitudinals can be placed into
cutouts in the form of notches 5 located on the outside perimeter
of the ring 2. The longitudinals can then be spot welded,
adhesively bonded or joined by any variety of means to the rings 2.
It is also envisioned that the longitudinals could be placed on the
inside perimeter of the ring 2, or holes could be mechanically or
laser drilled through the ring 2 for placement therethrough of the
longitudinals.
[0021] FIGS. 4 and 5 illustrate a stent 1' shown in one particular
form in which it could be fabricated; i.e., in an initial structure
form. Specifically, FIGS. 4 and 5 show that this initial form of
the stent 1' is a multiplicity of parallel ellipses or ovals 2"
each oval having the same minor axis dimension m and major axis
dimension M. The oval's minor axis passes through the center of the
longitudinals 4L and 4R. The oval's major axis passes through the
center of the longitudinals 4T and 4B. It is important to note
that, if it is desired to have a final outside diameter D (as seen
in FIG. 2) of the ring 2 after it is fully deployed, then it can be
shown that D is given by the equation
D.sup.2=1/2(m.sup.2+M.sup.2).
[0022] To place the stent design of FIGS. 4 and 5 onto a balloon
that is mounted near the distal end of a stent delivery catheter,
it is necessary to fold the ovals 2' around that balloon.
Specifically, the pre-deployment cylindrical stent 1" can be formed
onto an expandable balloon 6 as shown in FIG. 6 by folding the
ovals 2' about the dotted line F (which is the minor axis of the
oval 2') as shown in FIG. 5 Specifically, as seen in FIG. 4, the
top and bottom of the ovals 2' could be held stationery while the
side longitudinals 4R and 4L are pushed to the left which results
in the pre-deployment structure which is shown as the stent 1" in
FIG. 6. An optimum design has the folded ovals 2" as shown in FIG.
6 with the stent 1" being a cylinder whose outside diameter is
equal in size to the minor axis dimension m. When the balloon 6 of
FIG. 6 is expanded, the pre-deployment stent 1" structure forms the
post-deployment stent 1 structure having circular rings 2 as shown
in FIGS. 1 and 2.
[0023] The stent 1'" is an alternative embodiment for a
pre-deployment structure of the stent of the present invention as
it is placed onto a balloon. Specifically, FIG. 7 shows 2 folded
rings 2'" of a multiple ring stent 1'". The stent 1'" being formed
by holding the top and bottom of the stent 1' of FIG. 4 stationery
while pushing the longitudinal 4R to the left and pushing the
longitudinal 4L to the right. Like the stent 1" of FIG. 6, when
mounted onto a balloon, the stent 1'" has cylindrical shape with a
diameter equal to the dimension m.
[0024] FIGS. 1 to 7 inclusive illustrate stents that employ
longitudinals that are formed from generally straight wires. FIG. 8
shows an alternative embodiment of a stent 10 that has two
undulating longitudinals. Specifically, the left side longitudinal
14L (shown as dotted lines) and the right side longitudinal 14R are
each undulating shaped longitudinals. A stent such as stent 10
could have two or more undulating longitudinals. Such a stent would
bend more easily during insertion into a vessel and would be more
readily adaptable for placement in curved vessels such as some
coronary arteries.
[0025] Typically, the rings and longitudinals of the stents would
be made of the same material. Typical metals used for such a stent
would be stainless steel, tantulum, titanium, or a shape memory
metal such as Nitinol. If Nitinol is used, the stent would be heat
treated into the shape at body temperature having circular rings 2
as shown in FIGS. 1 and 2. The rings could then be distorted into
ovals as shown in FIGS. 4 and 5 and then mounted onto a stent
delivery catheter which does not employ a balloon but is of the
more general shape described in the previously cited U.S. Pat. No.
4,553,545 by C. T. Dotter. Such a design would provide the desired
stent structure having a multiplicity of generally circular rings
instead of the Dotter design of a helical spring which inherently
has a lesser hoop strength as compared to the present
invention.
[0026] It should be understood that once the ovals are folded onto
a stent delivery catheter, when they fully deploy, they do not form
perfectly circular rings as shown in FIG. 2, but rather they are of
a generally circular shape. Such comparatively small deviations
form an exactly circular shape do not appreciably decrease hoop
strength because they are in fact closed structures that are almost
exactly circular.
[0027] It should also be understood that at least part of the end
rings of the stent could be fabricated from or coated with a
radiopaque metal such as tantalum or gold to provide a fluoroscopic
indication of the stent position within a vessel. However, the
other rings and the longitudinals could be made from a much less
dense metal which would provide less obscuration of the central
region within the stent. For example, the stent rings and
longitudinals could all be fabricated from titanium or a titanium
alloy except the end rings which could be formed from gold which is
then plated with titanium. Thus, the entire outside surface of the
stent would be titanium, which is known to be a comparatively
non-thrombogenic metal while the gold in the end rings provides an
improved fluoroscopic image of the stent extremities.
[0028] The dimensions of stent rings are typically 0.1 to 0.3 mm
thick, with a width of 0.1 to 0.5 mm and an outside diameter D
between 2.0 and 30.0; mm depending on the luminal diameter of the
vessel into which it is inserted. The length of the stent could be
between 1 and 10 cm. The wire diameter for the longitudinals would
typically be between 0.05 and 0.5 mm.
[0029] Although the designs of FIGS. 1 through 7 inclusive
illustrate separate longitudinals attached to a multiplicity of
rings, this invention also contemplates an initial stent structure
which is chemically etched from thin-walled tubing having an oval
transverse cross section. Thus the oval and longitudinals would be
formed from a single piece of metal thus precluding the need for
attaching the longitudinals to the rings. In a similar manner laser
or EDM machining could be used to form the stent from a thin-walled
tube.
[0030] It is further anticipated that a pre-deployment stent
structure 20 as shown in FIG. 9 could be formed from a thin-walled
cylindrical tube whose inside diameter is slightly smaller than the
outside diameter of the balloon 6 shown in FIG. 6. A pattern such
as that shown in either FIG. 6 or FIG. 7 could be photoetched onto
a tin-walled metal cylinder. The one piece structure 20 shown in
FIG. 9 has folded ovals 22 and longitudinals 23T, 24B, 24R and (not
shown) 24L. This pre-deployment stent structure 20 could then be
mounted onto the expandable balloon; the stent having sufficient
elastic recoil to firmly grasp down onto the balloon. Another
method to form the pre-deployment stent is by etching the correct
pattern onto a thin, flat metal plate, then forming a tube from the
plate and then making a longitudinal weld to form a cylindrically
shaped structure which is, in fact, the pre-deployment stent
structure 20 shown in FIG. 9.
[0031] Various other modifications, adaptations, and alternative
designs are of course possible in light of the above teachings.
Therefore, it should be understood at this time that within the
scope of the appended claims, the invention may be practiced
otherwise than as specifically described herein.
* * * * *