U.S. patent application number 10/993380 was filed with the patent office on 2005-04-28 for crimpable intraluminal endoprosthesis having helical elements.
Invention is credited to Becker, Gary J., Pazienza, John D., Piferi, Peter G..
Application Number | 20050090894 10/993380 |
Document ID | / |
Family ID | 26146599 |
Filed Date | 2005-04-28 |
United States Patent
Application |
20050090894 |
Kind Code |
A1 |
Pazienza, John D. ; et
al. |
April 28, 2005 |
Crimpable intraluminal endoprosthesis having helical elements
Abstract
A stent having helical elements, a geometry for improved
crimping, and a good stent-to-vessel ratio is disclosed. In one
embodiment, the stent has a plurality of first helical segments and
a plurality of second opposing helical segments. The first helical
segments are comprised of a plurality of first expandable elements
and the second helical segments are comprised of a plurality of
second helical elements. The expandable elements are joined to each
other by a plurality of struts. When the stent is crimped a portion
of one of the first expandable elements nest within another portion
of the same expandable element and a portion of two first
expandable elements nestle between the same two portions of second
expandable elements.
Inventors: |
Pazienza, John D.; (Pompano
Beach, FL) ; Piferi, Peter G.; (Plantation, FL)
; Becker, Gary J.; (Miami, FL) |
Correspondence
Address: |
WHITE & CASE LLP
PATENT DEPARTMENT
1155 AVENUE OF THE AMERICAS
NEW YORK
NY
10036
US
|
Family ID: |
26146599 |
Appl. No.: |
10/993380 |
Filed: |
November 19, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10993380 |
Nov 19, 2004 |
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10071071 |
Feb 8, 2002 |
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6821292 |
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10993380 |
Nov 19, 2004 |
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09511481 |
Feb 23, 2000 |
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09511481 |
Feb 23, 2000 |
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09094402 |
Jun 10, 1998 |
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6117165 |
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60267778 |
Feb 9, 2001 |
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Current U.S.
Class: |
623/1.15 |
Current CPC
Class: |
A61F 2002/91508
20130101; A61F 2002/91516 20130101; A61F 2002/91533 20130101; A61F
2230/0013 20130101; A61F 2/91 20130101; A61F 2002/91541 20130101;
A61F 2002/91558 20130101; A61F 2002/9155 20130101; A61F 2002/91525
20130101; A61F 2/915 20130101; A61F 2/88 20130101; A61F 2002/91583
20130101 |
Class at
Publication: |
623/001.15 |
International
Class: |
A61F 002/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 13, 1997 |
EP |
97201799.0 |
May 6, 1998 |
EP |
98201446.6 |
Claims
1-16. (canceled)
17. A stent having a generally cylindrical main body, the main body
comprising: a plurality of helical segments, at least one helical
segment crossing another helical segment; and wherein the stent has
a crimped diameter and an expanded diameter that is 3-6 times the
crimped diameter.
18. The stent of claim 17, wherein the helical segments contract
and expand in a direction parallel to the circumference of the main
body when the stent is crimped and expanded.
19-20. (canceled)
21. The stent of claim 18, wherein at least a portion of one
helical segment nestles between two other helical segments when the
stent is crimped and the stent is manufactured from a tube having a
diameter of approximately between 0.03 to 0.500 inches.
22. The stent of claim 21, wherein the stent is manufactured by
laser cutting the tube.
23-37. (canceled)
Description
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/267,778, filed on Feb. 9, 2001, which is hereby
incorporated in its entirety by reference, and it is a
continuation-in-part of U.S. patent application Ser. No.
09/511,481, filed on Feb. 23, 2000, which is also hereby
incorporated in its entirety by reference and which is a
continuation of U.S. patent application Ser. No. 09/094,402, filed
Jun. 10, 1998 (now U.S. Pat. No. 6,117,165).
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to intraluminal endoprosthetic
devices known as stents. In particular, the present invention
relates to stents having helical elements with a geometry that
allows the stent to be readily crimped onto a delivery device.
[0004] 2. Description of Related Art
[0005] Stents are prosthetic devices that are implanted in the
lumen of a vessel inside the body to provide support for the
vessel's wall. Structural support from stents is particularly
important in angioplasty procedures. Typically, stents are
implanted within a vessel system to reinforce vessels that are
partially occluded, collapsing, weakened, or abnormally dilated.
More generally, stents can be used inside any physiological conduit
or duct, including--for example--arteries, veins, bile ducts, the
urinary tract, alimentary tracts, the tracheobronchial tree, a
cerebral aqueduct or the genitourinary system. Stents may be used
in both humans and animals.
[0006] There are typically two types of stents: self expanding
stents and balloon expandable stents. Self expanding stents
automatically expand once they are released and assume a deployed,
expanded state. A balloon expandable stent is expanded using an
inflatable balloon catheter. The balloon is inflated to plastically
deform the stent. Balloon expandable stents may be implanted by
mounting the stent in an unexpanded or crimped state on a balloon
segment of a catheter. The catheter, after having the crimped stent
placed thereon, is inserted through a puncture in a vessel wall and
moved through the vessel until it is positioned in the portion of
the vessel that is in need of repair. The stent is then expanded by
inflating the balloon catheter against the inside wall of the
vessel. Specifically, the stent is plastically deformed by
inflating the balloon so that the diameter of the stent is
increased and remains at an increased state. In some situations,
the vessel in which the stent is implanted may be dilated by the
stent itself when the stent is expanded.
[0007] The Palmaz-Schatzt.TM. stent, which is disclosed in the
Handbook of Coronary Stents by Patrick W. Serruys et al. (Martin
Dunitz, LTD 1998), is an example of a balloon expandable stent that
had been implanted in hundreds of thousands of patients. The
Palmaz-Schatz.TM. stent, like other known stents, has certain
limitations. These include, but are not limited to: (i) low
stent-to-vessel ratio uniformity, (ii) comparative rigidity of the
stent in a crimped as well as deployed state, and (iii) limited
flexibility making delivery and placement in narrow vessels
difficult. Stent-to-vessel ratio generally refers to the degree
that the vessel wall is supported by the stent in its expanded
state and preferably should be uniform throughout the length of the
stent. Furthermore because the Palmaz-Schatz.TM. stent consists of
one or more bridges that connect a number of consecutively slotted
tubes, there are a number of bare areas in the vessel after the
expansion of the stent. These shortfalls are common to many stents.
Id. at 36.
SUMMARY OF THE INVENTION
[0008] The present invention is directed to expandable stents that
have geometries that allow them to be readily crimped onto a
balloon delivery device. In one embodiment, the stent may be
comprised of a plurality of first helical segment having a first
helical angle with respect to the longitudinal axis of the stent
and a plurality of second helical segments that have a second
helical angle. The helical segments are capable of expanding and
contracting circumferentially, i.e., they expand or contract along
the circumference of the stent. In this embodiment, when the stent
is crimped, at least one portion of one first helical segment,
along with at least one portion of a second first helical element,
nestle between the same two portions of two separate second helical
segments.
[0009] In one embodiment of the present invention, the stent is
comprised of a plurality of first expandable elements and a
plurality of second expandable elements. The first expandable
element may have a segment that nests within another segment of the
same first expandable element. In some embodiments, the first
expandable elements are joined together by struts to form first
helical segments and the second expandable elements are joined
together by struts to form second helical segments. The first and
second helical segments may have different helical angles or
different pitches. In some embodiments, the first and second
helical segments share common struts.
[0010] In some embodiments of the present invention, the stent may
be comprised of a plurality of cells. Each cells may be comprised
of first and second elements that are alternatively joined together
(i.e., each first element is joined to two second elements and each
second element is joined to two first elements to form a polygon).
The polygon may be amorphous or may have a definite shape. When the
stent is crimped a portion of each first of the elements that make
up the cell nestles between portions of the second elements of the
cell. In some embodiments, the first and second elements may touch
each other when the stent is crimped. A plurality of struts joins
the cells to form a stent body. In addition portions of a first
element may nest within other portions of the same first element
and a portion of a second element may also nest within a portion of
the same first element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a three dimensional view of one embodiment of a
stent according to the present invention.
[0012] FIG. 2 is planar view of a flattened portion of the
circumference of the stent in FIG. 1.
[0013] FIG. 3 is a planar view of one element that makes us the
stent body as shown in the planar view of FIG. 2.
[0014] FIGS. 4a and 4b are views of filament segments that comprise
the element shown in FIG. 3.
[0015] FIG. 5 is a planar view of a second element that makes up
the stent body shown in FIG. 2.
[0016] FIG. 6 is a planar view of the element of FIG. 3, when the
stent is crimped.
[0017] FIG. 7 is a planar view of the elements of FIGS. 3 and 5,
when the stent is crimped.
[0018] FIG. 8a is a planar view illustrating a plurality of cells
that may be joined together to make one embodiment of the stent of
the present invention.
[0019] FIG. 8b is an enlarged portion of one of the cells shown in
FIG. 8a.
[0020] FIG. 9 is a planar view of the cell of FIG. 8a after the
stent has been crimped.
[0021] FIG. 10 illustrates how certain first elements and certain
second elements nestle when the stent is crimped.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention is directed to an expandable stent
having a geometry that is well-suited for crimping the stent onto a
delivery device. In some, but not necessarily all embodiments of
the present invention, the stents may have an expanded diameter
that is 3 to 6 times that of its crimped diameter. In addition, in
some--but not necessarily all--embodiments the stent-to-vessel
ratios may be better than 15%.
[0023] In one embodiment of the present invention, as is shown in
FIGS. 1 & 2, a stent is comprised of a main body section 100
having a longitudinal axis 1000. The stent shown in FIG. 1 is
mounted on a carrier 616. The main body is comprised of a plurality
of first helical segments 120a and 120b and a plurality of second
helical segments 150a and 150b. The first helical segments form a
helical angle .alpha. with respect to the longitudinal axis 1000 of
the stent, resulting in the first helical segments having a first
pitch. The second helical segments 150a and 150b form a helical
angle .theta. with respect to the longitudinal axis 1000, resulting
in the second helical segments having a second pitch. In some
embodiments a varies between 20.degree. and 50.degree., and .theta.
varies between 20.degree. and 90.degree.. The first helical
segments 120a and 120b and second helical segments 150a and 150b
are circumferentially expandable, i.e., they are capable of
expanding in a direction parallel to the direction of the
circumference 200 of the stent. The helical segments 120a, 120b,
150a, and 150b also circumferentially contract when the stent is
crimped.
[0024] As is discussed further below, in some embodiments, the
first helical segments 120a and 120b may be comprised of a
plurality of filament segments and likewise the second helical
segments 150a and 150b may be comprised of a plurality of filament
segments. In some embodiments the total length of the sum of all
the filament segments comprising the first helical segment may be
longer than the total length of the filament segments comprising
the second helical segment. In some cases, the first and second
helical segments may share common filament segments.
[0025] As is shown in FIG. 2, the first helical segments 120a and
120b are comprised of a plurality of first expandable elements 300,
and the second helical segments are comprised of a plurality of
second expandable elements 350. Two or more first expandable
segments 300 are joined together by a plurality of struts 400 to
form each of the first helical segments 120a and 120b. The same
struts 400 also join two second expandable segments 350 to form the
second helical segments 150a and 150b. The struts 400 may be an
integral part of the first or second expandable element, or
both.
[0026] As is shown in FIG. 3, in some embodiments, the first
expandable elements 300 are comprised of a plurality of contiguous
filament segments 700a, 700b, 710a, 710b and 720. In one
embodiment, the filament segments 700a, 710a and 720 are joined
together to form a generally R-shaped structure 730. (See FIG. 4).
The filament that forms the head of the R, i.e. filament 710a or
710b, may be curved and have a radius r. The radius r may take many
values, including but not limited to approximately 0.015 inches. As
is shown in FIGS. 3, 4a, and 4b, the first expandable elements 300
may be comprised of a plurality of R-shaped structures 730a and
730b oriented inversely to one another and sharing a common
filament segment 720.
[0027] In some embodiments, as is shown in FIG. 5, the second
expandable elements 350 may be comprised of a plurality of
contiguous filament segments 770a, 770b, 775a, 780, and 775b and
may, for example, in some embodiments form a Z-shaped structure.
For example, as is shown, filament 770a may lie at an angle .beta.
with respect to filament 780 and segments 770a and 770b may be
joined to the single segment 780 by curved segments 775a and 775b.
In some, but not necessarily all, embodiments, 770a and 770b have
the same dimensions, and 780 may be shorter. The angle .beta. may
also vary greatly, and in one embodiment ranges between 30.degree.
and 40.degree., for example.
[0028] As is shown in FIG. 1, some embodiments of the present
invention may have endzones 600 & 610 that straddle the main
body 100. The endzones may have square outer edges 605 & 615.
The endzones may be attached to the main body 100 with a plurality
of second struts 450. (See FIG. 2). The second struts may have an
orientation that differs from that of the other struts 400. For
example, the second struts 450 may be parallel to the cylindrical
axis 1000 of the stent, while the struts 400 may be oriented at an
angle to the cylindrical axis of the stent.
[0029] The stents of the present invention provide a geometry that
improves their crimpability. For example, one embodiment of the
present invention may have a crimped diameter of less than 2.0 mm
and an expanded diameter of 6.0-12.0 mm, or greater. The stent may
be crimped onto a PTA Balloon at a diameter of 1.50 mm and it may
be manufactured from a tube having a diameter of approximately
0.030 to 0.500 inches. Of course, other sized tube may be used. And
stents may be manufactured in a wide variety of sizes for a wide
variety of applications.
[0030] In one embodiment of the present invention, when the stent
is crimped, a first portion of the first expandable element 300
nests within another portion of the same first expandable element
300. For example, as is shown in FIG. 6, portions of filament 710a
and 720 nest within a concave portion of filament 700b. Likewise
portions of filaments 710b and 720 nest within a concave portion of
filament 700a.
[0031] In some embodiments of the present invention, when the stent
is crimped, a portion of a second expandable element 350 nests
within a portion of the first expandable element 300. For example,
as is shown in FIG. 7, a portion of second expandable element 350
nests within a portion of element 300. Specifically, in this
embodiment, which is illustrative and not exhaustive of the present
invention, a portion of filament 770b and 775b nest within the
concave portions of filament 710a and 700a. This example
illustrates some, but not necessarily all, of the nesting features
of the present invention
[0032] In some embodiments of the present invention, when the stent
is crimped, portions from two separate first expandable elements
300 may nestle between the same portions of two separate second
expandable segments 350. As is shown in FIG. 10, part of one first
expandable element, namely filament 710a and part of a second first
expandable element 710b, both of which comprise heads for R-shaped
structures 730a and 730b (see also FIGS. 4a and 4b) nestle between
filaments 775a and 775b, which are each part of a separate second
expandable elements 350. FIG. 10 illustrates some, but not
necessarily all, of the nestling features of the geometry of the
present invention.
[0033] As is illustrated by FIGS. 10, 3, 4a, 3b, and 3, in some
embodiments, not only is the filament 775a part of one second
expandable element 350 which is in turn part of a second helical
segment 150a, but also filament 710a is part of one first
expandable segment 300 which is in turn part of a first helical
segment 120a. Likewise, filament 775b is part of different second
expandable element 350, which is part of a second second helical
segment 150b and filament 710b is part of a second first expandable
element 300, which is in turn part of another helical segment 120b.
Thus, in one embodiment of the present invention portions of one
first helical segment and portions of another first helical segment
nestle, when the stent is crimped, between portions of two separate
second helical segments.
[0034] As is shown in FIG. 8a, the stent of the present invention,
may in some embodiments, be comprised of a plurality of cells 500.
In some embodiments, the cells 500 may be joined together by struts
400. Each cell 500 may be comprised of first elements 300 and
second elements 350. In one embodiment, as is shown in FIG. 8b,
each first element 300 is joined to two second elements 350, and
each second element 350 is joined to two first elements 300. This
results in a polygon, which may take many forms or may be
amorphous. As is shown in FIGS. 2 and 8a, cells may be joined
together so that the resulting stent has a plurality of helical
segments, wherein at least one helical segment cross another. (See
e.g. FIG. 2).
[0035] Cell geometry may be such that each cell expands at a
relatively constant rate. For example, in the embodiment shown in
FIG. 8a, each cell is comprised of a plurality of first expandable
elements 300 and a plurality of second expandable elements 350.
Each first element 300 is in turn comprised of a plurality of
R-shaped elements 730a and 730b. The second expandable elements 350
in this illustrative embodiment are generally Z-shaped. During
expansion, the R-shaped elements 730a and 730b expand at a slower
initial rate than the Z shaped elements. By staggering or
alternating circumferentially first elements 300 and second
elements 350, the stent expands circumferentially in a uniform
manner because each cell circumferentially expands uniformly, not
withstanding that the elements 350 expand faster than the elements
300.
[0036] As is shown in FIG. 9, when a stent according to the present
invention is crimped, each cell circumferentially contracts. In
this embodiment, which is included herein for illustrative purposes
only and is not exhaustive of the present invention, when the stent
is crimped, one portion of a first expandable element (e.g. at
least portions of filaments 710a and 720) nests within another
portion of the same first expandable element (e.g. at least
portions of filament 700b) and portions of two separate first
expandable elements 300 (e.g., filaments 710a and 710b) nestle
between two separate second expandable elements 350. When the stent
is expanded each cell expands uniformly along line 200, which is
the circumferential dimension of the stent. (See FIG. 1). The
second expandable elements 350 open at a faster rate than the first
expandable elements 300, but since the first expandable elements
are oriented diagonally, as are the second expandable elements, the
right portion 2000 of the cell 500 expands at the same rate as the
left portion 3000 of the cell 500. (See FIG. 9).
[0037] The foregoing embodiments and description is intended to
illustrate the various and broad-ranging features of the present
invention and is not intended to limit the scope or spirit of the
present invention. The present invention may be embodied in
numerous forms other than those specifically described above. For
example, and without limitation, the first elements 300 and the
second elements 350 may take numerous forms and shapes other than
those shown. This may result in a first helical segment having a
total filament length that is greater than or less than that of a
second helical element. In addition, the stents of the present
invention may be manufactured from materials with techniques that
are readily known in the art, such as for example, by laser cutting
tubes, which are manufactured from appropriate stent materials.
Thus, although the embodiments described herein refer to different
elements and segments within the same stent, those skilled in the
art will recognize that the stent of the present invention may be
comprised of a single continuous piece of material or it may be
comprised of multiple disparate filaments or segment pieces joined
together by well-known techniques.
* * * * *