WO2003007842A2 - Stents - Google Patents

Stents Download PDF

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Publication number
WO2003007842A2
WO2003007842A2 PCT/ZA2002/000116 ZA0200116W WO03007842A2 WO 2003007842 A2 WO2003007842 A2 WO 2003007842A2 ZA 0200116 W ZA0200116 W ZA 0200116W WO 03007842 A2 WO03007842 A2 WO 03007842A2
Authority
WO
WIPO (PCT)
Prior art keywords
ring
bars
adjacent
longitudinals
stent
Prior art date
Application number
PCT/ZA2002/000116
Other languages
French (fr)
Other versions
WO2003007842A3 (en
Inventor
Gregory Richard Starke
Markus Lehmann
Damian John Conway
Original Assignee
Disa Vascular (Pty) Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Disa Vascular (Pty) Ltd filed Critical Disa Vascular (Pty) Ltd
Priority to AU2002354966A priority Critical patent/AU2002354966A1/en
Publication of WO2003007842A2 publication Critical patent/WO2003007842A2/en
Publication of WO2003007842A3 publication Critical patent/WO2003007842A3/en

Links

Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
    • A61F2/91Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
    • A61F2/915Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
    • A61F2/91Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
    • A61F2/91Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
    • A61F2/915Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
    • A61F2002/91533Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other characterised by the phase between adjacent bands
    • A61F2002/91541Adjacent bands are arranged out of phase
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
    • A61F2/91Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
    • A61F2/915Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
    • A61F2002/9155Adjacent bands being connected to each other
    • A61F2002/91558Adjacent bands being connected to each other connected peak to peak
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2230/00Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2230/0002Two-dimensional shapes, e.g. cross-sections
    • A61F2230/0028Shapes in the form of latin or greek characters
    • A61F2230/0054V-shaped
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2250/00Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2250/0058Additional features; Implant or prostheses properties not otherwise provided for
    • A61F2250/0067Means for introducing or releasing pharmaceutical products into the body
    • A61F2250/0068Means for introducing or releasing pharmaceutical products into the body the pharmaceutical product being in a reservoir

Definitions

  • THIS INVENTION relates to stents.
  • a stent is used medically in any one of a multiplicity of vessels of the
  • the object of the present invention is to provide a stent with improved
  • Each bar preferably has end portions contiguous with the hairpin bends
  • Each ring can be a mirror image of the ring, or rings, adjacent thereto
  • said one ring and said adjacent ring each comprise
  • stent of cylindrical form which comprises a plurality of rings extending around the stent's
  • each ring being of zig-zag form and comprising a plurality of first bars all of which are
  • adjacent pair of longitudinals considered in the circumferential direction, at least two, or
  • each longitudinal connecting a first ring to a second ring being midway between
  • stent of cylindrical form which comprises a plurality of rings extending around the stent's
  • each ring being of zig-zag form and comprising a plurality of first bars all of which are
  • each longitudinal being of sinusoidal or generally sinusoidal
  • each ring being a mirror image of the adjacent ring
  • hairpin bend of said one ring is axially aligned with one of the hairpin bends of said
  • Each group of three rings can comprise a centre ring, a first adjacent ring
  • the centre ring being joined by longitudinals to the second adjacent ring.
  • each bar of the stent can be narrower considered in the circumferential
  • each bar of the stent can have a centre section
  • Figure 1 illustrates a stent in layflat form
  • Figure 2 illustrates another stent in layflat form
  • Figure 3 illustrates a detail of a stent
  • Figure 4 illustrates a further stent detail
  • Figure 5 illustrates a number of bars and hairpin bends of a stent
  • Figure 6 illustrates a further form of stent. DETAILED DESCRIPTION OF THE DRAWINGS
  • the stent 10 illustrated is of cylindrical form and
  • the rings 12 are spaced apart along the longitudinal axis of the stent and
  • Each ring 12 is of zig-zag form and comprises a plurality of first bars 16 all
  • Bars 16 alternate with bars 18.
  • the bars are joined to one another by way of hairpin bends 20.
  • Each longitudinal 14 joins a hairpin bend 20 of one ring 12 to a hairpin
  • each ring 12 has two hairpin
  • Each longitudinal is of S-configuration, one end of each longitudinal being
  • Each bar 16, 18 is non-linear in configuration. More specifically each bar
  • each ring 12 is a mirror image of
  • the stent comprises a plurality of rings 24 which extend around the stent's longitudinal axis and are spaced apart along the axis.
  • the rings 24 are spaced apart along the axis.
  • Each ring 24 is of zig-zag form and comprises a plurality of bars 28 all of
  • the bars 28 are at an angle to the bars 30, bars 30 alternating with bars
  • each bar 30 being joined at each thereof to two adjacent bars 28 by way of
  • the longitudinals 26 join the bends 32 of one ring 24 to the bends 32 of
  • Each longitudinal 26 is of sinusoidal form. There is a junction at 34
  • first junction 34 at one end of a longitudinal 26 is displaced circumferentially around the
  • the configuration of the stent is such that the rings can be considered to
  • centre ring 24.2 are joined by longitudinals designated 26.1 to the ring 24.1 on one side
  • the stents described above are of an eight cell design. A stent of six cell
  • radio opacity of a six cell stent it preferably has the configuration shown in Figure 4.
  • width W3 of the centre section of each bar is greater than the width W4 of
  • each end section of each bar and also greater than the width of the hairpin bend.
  • the stent shown in Figure 5 comprises bars 38 and hairpin bends 40.
  • the bars have slots 42 cut
  • these can be on the radially inner faces of the bars, or the radially outer faces
  • the slots and/or grooves provide reservoirs in
  • slow release drugs can be located within a polymer substrate or other binder.
  • More or larger slots can be provided where there is a greater need for drug elution.
  • the ends of the stent are places where higher drug concentrations can be required.
  • the drugs are released into the tissue or bloodstream over a period of time.
  • the stent shown in Figure 6 has rings designated 46, 48 and 50.
  • the stent shown in Figure 6 has rings designated 46, 48 and 50.
  • the bars 52, 54 of the ring 46 are longer than the bars of the ring 48
  • ends of the stent are shorter than the bars of the rings towards the middle of the stent
  • bar lengths can be chosen to provide ring-like zones of greater strength and ring-like
  • W2/W1 will always be greater than 1.
  • the bars can include through slots and/or recesses for receiving drugs
  • measured in the axial direction can vary from one ring to another. A similar variation in
  • stiffness can be provided by means of bars which in one ring are of a different length to

Abstract

A stent (22) of cylindrical form is disclosed which comprises a plurality of rings (24) extending around the stent's longitudinal axis. The rings (24) are spaced apart along the axis and are joined to one another by longitudinals (26) each of which spans between one ring and an adjacent ring. Each ring (24) is of zig-zag form and comprises bars (28) all of which are parallel to one another and bars (30) all of which are parallel to one another and at an angle to the bars (28). The bars (28, 30) alternate and are joined to one another by way of hairpin bends (32). the longitudinals (26) join the hairpin bends (32) of one ring to the hairpin bends (32) of the adjacent ring. Each of the rings has, between each adjacent pair of longitudinals (considered in the circumferential direction) at least two, or any multiple of two, hairpin bends (32) which are not joined to hairpin bends (32) of the adjacent ring.

Description

STENTS
FIELD OF THE INVENTION
THIS INVENTION relates to stents.
BACKGROUND TO THE INVENTION
A stent is used medically in any one of a multiplicity of vessels of the
human body to maintain its patency.
Applicant is aware of European patent specifications EP 0 669 114 B1 ,
EP 0 821 920 B1 and EP 0 821 921 A1 and US specifications 5733303, 5195984,
5102417, 4733665, 6179867, 5514154, 6068656, 6190403, 5913895 and 5643312
which disclose stents of various types.
The object of the present invention is to provide a stent with improved
radial expansion capabilities and minimal longitudinal contraction during radial
expansion.
BRIEF DESCRIPTION OF THE INVENTION
According to one aspect of the present invention there is provided a stent
of cylindrical form which comprises a plurality of rings extending around the stent's longitudinal axis, the rings being spaced apart along the axis and being joined to one
another by longitudinals each of which spans between one ring and an adjacent ring,
characterized in that each ring is of zig-zag form and comprises a plurality of first bars
all of which are parallel to one another and a plurality of second bars all of which are
parallel to one another and at an angle to the bars of the first set of bars, first bars
alternating with second bars and each first bar being joined at each end thereof to the
adjacent second bars by way of hairpin bends, the longitudinals joining the hairpin
bends of one ring to the hairpin bends of the adjacent ring, each of these rings having
between each adjacent pair of longitudinals, considered in the circumferential direction,
at least two, or any multiple of two, hairpin bends which are not joined to hairpin bends
of the adjacent ring.
Each bar preferably has end portions contiguous with the hairpin bends
that join it to adjacent bars and a centre portion which joins said end portions to one
another, the centre portion being of non-linear configuration.
Each ring can be a mirror image of the ring, or rings, adjacent thereto
about radial planes passing through the midpoints of the longitudinals.
In a specific form said one ring and said adjacent ring each comprise
three first bars, three second bars and five hairpin bends between each of said adjacent
pairs of longitudinals thereby providing the two non-joined hairpin bends on the facing sides of said rings and three hairpin bends on the sides of the rings which face away
from another, the centre ones of these hairpin bends being joined by longitudinals to
further rings.
According to another aspect of the present invention there is provided a
stent of cylindrical form which comprises a plurality of rings extending around the stent's
longitudinal axis, the rings being spaced apart along the axis and being joined to one
another by longitudinals each of which spans between one ring and an adjacent ring,
each ring being of zig-zag form and comprising a plurality of first bars all of which are
parallel to one another and a plurality of second bars all of which are parallel to one
another and at an angle to the bars of the first set of bars, first bars alternating with
second bars and each first bar being joined at each end thereof to the adjacent second
bars by way of hairpin bends, the longitudinals joining the hairpin bends of one ring to
the hairpin bends of the adjacent ring, each of these rings having between each
adjacent pair of longitudinals, considered in the circumferential direction, at least two, or
any multiple of two, hairpin bends which are not joined to hairpin bends of the adjacent
ring, each longitudinal connecting a first ring to a second ring being midway between,
considered in the circumferential direction, two further longitudinals which connect the
first ring to a further ring and midway between two additional longitudinals which
connect the second ring to another ring, the further longitudinals being spaced the
same circumferential distance from one another as the two additional longitudinals are
spaced from one another and which is the same distance as the spacing between the longitudinals connecting the first and second rings.
According to a further aspect of the present invention there is provided a
stent of cylindrical form which comprises a plurality of rings extending around the stent's
longitudinal axis, the rings being spaced apart along the axis and being joined to one
another by longitudinals each of which spans between one ring and an adjacent ring,
each ring being of zig-zag form and comprising a plurality of first bars all of which are
parallel to one another and a plurality of second bars all of which are parallel to one
another and at an angle to the bars of the first set of bars, first bars alternating with
second bars and each first bar being joined at each end thereof to the adjacent second
bars by way of hairpin bends, the longitudinals joining the bends of one ring to the
bends of the adjacent ring, each longitudinal being of sinusoidal or generally sinusoidal
form, there being a first junction where one end of the longitudinal is joined to one ring
and a second junction where the other end of the longitudinal is joined to an adjacent
ring, said first junction being displaced circumferentially around the stent with respect to
the second junction, each ring being a mirror image of the adjacent ring whereby each
hairpin bend of said one ring is axially aligned with one of the hairpin bends of said
adjacent ring.
Each group of three rings can comprise a centre ring, a first adjacent ring
on one side of the centre ring and a second adjacent ring on the other side of the
centre ring, alternate hairpin bends on one side of the centre ring being joined by longitudinals to the first adjacent ring and alternate hairpin bends on the other side of
the centre ring being joined by longitudinals to the second adjacent ring.
In a configuration which reduces stress concentrations at the hair pin
bends, each bar of the stent can be narrower considered in the circumferential
direction, than the width of the hairpin bends considered in the axial direction.
To improve radio opacity each bar of the stent can have a centre section
and end sections on each side of the centre section, the end sections being narrower,
considered in the circumferential direction, than the centre section.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention, and to show how the
same may be carried into effect, reference will now be made, by way of example, to the
accompanying drawings in which:-
Figure 1 illustrates a stent in layflat form;
Figure 2 illustrates another stent in layflat form;
Figure 3 illustrates a detail of a stent;
Figure 4 illustrates a further stent detail;
Figure 5 illustrates a number of bars and hairpin bends of a stent; and
Figure 6 illustrates a further form of stent. DETAILED DESCRIPTION OF THE DRAWINGS
Referring firstly to Figure 1 the stent 10 illustrated is of cylindrical form and
comprises a plurality of rings 12 which extend around the stent's longitudinal axis. For
ease of illustration the stent has been shown in the form it adopts if split longitudinally
and flattened.
The rings 12 are spaced apart along the longitudinal axis of the stent and
are joined to one another by longitudinals 14 which span between one ring 12 and an
adjacent ring 12.
Each ring 12 is of zig-zag form and comprises a plurality of first bars 16 all
of which are parallel to one another and a plurality of second bars 18 all of which are
parallel to one another and at an angle to the bars 16. Bars 16 alternate with bars 18.
The bars are joined to one another by way of hairpin bends 20.
Each longitudinal 14 joins a hairpin bend 20 of one ring 12 to a hairpin
bend 20 of the adjacent ring. This arrangement enables longitudinals of sufficient
length to be obtained without having to increase the spacing between adjacent rings.
As will be seen from Figure 1 , not all the hairpin bends are joined to one
another. More specifically, between each pair of longitudinals and the hairpin bends joined by them, considered in the circumferential direction, each ring 12 has two hairpin
bends 20 which are not joined to the hairpin bends of adjacent rings. To distinguish
between them, the hairpin bends of one pair of joined hairpin bends have been
designated 20.1 and a non-joined pair 20.2.
Each longitudinal is of S-configuration, one end of each longitudinal being
spaced from the other end both in the axial direction of the stent and also in the
circumferential direction of the stent. This arrangement enables longitudinals of
sufficient length to be obtained without having to increase the spacing between
adjacent rings.
Each bar 16, 18 is non-linear in configuration. More specifically each bar
16 has end portions 16.1 , 16.2 which are approximately straight and in alignment with
one another and a centre portion 18.3 which is of non-linear curved configuration and
joins the end portions 16.1 , 16.2 to one another.
A consideration of Figure 1 reveals that each ring 12 is a mirror image of
the adjacent ring. To illustrate this the rings 12.1 and 12.2 are mirror images of one
another about the line AA.
Turning now to Figure 2, the illustrated stent 22 is again shown in
longitudinally split flat form. The stent comprises a plurality of rings 24 which extend around the stent's longitudinal axis and are spaced apart along the axis. The rings 24
are joined to one another by longitudinals 26 which span between one ring 24 and an
adjacent ring 24.
Each ring 24 is of zig-zag form and comprises a plurality of bars 28 all of
which are parallel to one another and a plurality of bars 30 which are also parallel to
one another. The bars 28 are at an angle to the bars 30, bars 30 alternating with bars
28 and each bar 30 being joined at each thereof to two adjacent bars 28 by way of
hairpin bends 32.
The longitudinals 26 join the bends 32 of one ring 24 to the bends 32 of
the adjacent ring. Each longitudinal 26 is of sinusoidal form. There is a junction at 34
where one end of the longitudinal 26 is joined to one hairpin bend 32 and another
junction at 36 where the other end of the longitudinal is joined to an adjacent ring. Each
first junction 34 at one end of a longitudinal 26 is displaced circumferentially around the
stent with respect to the second junction 36 between that longitudinal and the adjacent
ring. This again permits longitudinals 26 to be obtained which are of a length sufficient
to counter stent shortening on radial expansion.
The configuration of the stent is such that the rings can be considered to
be in groups of three. Three rings forming a group are designated 24.1 , 24.2 and 24.3
in Figure 2. The centre ring 24.2 of the group is joined to the rings on both sides thereof. More specifically, alternate hairpin bends, designated 32.1, on one side of the
centre ring 24.2 are joined by longitudinals designated 26.1 to the ring 24.1 on one side
thereof and alternate hairpin bends 32.2 on the other side of the centre ring 24.2 are
joined by longitudinals designated 26.2 to the ring 24.3.
When the cylindrical stent is expanded, the hairpin bends 20 open out to
enable the diameter of the stent to be increased. Inevitably the opening out of the
bends tends simultaneously to narrow each ring in the axial direction. Straightening of
the longitudinals accommodates this narrowing of the rings without foreshortening the
stent.
To minimise the strains imposed on the stent during expansion, it can
have the configuration shown in Figure 3. In this form the width W1 of the hairpin
bends is greater than the width W2 of the bars. This concentrates the greatest areas of
stress away from the hairpin bends and reduces the prospects of stress at the bends
fracturing the bends.
The stents described above are of an eight cell design. A stent of six cell
design has less metal content than a stent of eight cell design. In order to improve the
radio opacity of a six cell stent, it preferably has the configuration shown in Figure 4. In
this form the width W3 of the centre section of each bar is greater than the width W4 of
each end section of each bar and also greater than the width of the hairpin bend. The stent shown in Figure 5 comprises bars 38 and hairpin bends 40. To
provide for local delivery of drugs to the site of implantation, the bars have slots 42 cut
through them or grooves or recesses 44 cut into them. Where grooves or recesses are
provide, these can be on the radially inner faces of the bars, or the radially outer faces
or both. Areas of high plastic deformation must be avoided when choosing the
positions for the slot and/or grooves. The slots and/or grooves provide reservoirs in
which slow release drugs can be located within a polymer substrate or other binder.
More or larger slots can be provided where there is a greater need for drug elution.
The ends of the stent are places where higher drug concentrations can be required.
The drugs are released into the tissue or bloodstream over a period of time.
The stent shown in Figure 6 has rings designated 46, 48 and 50. The
bars are designated 52, 54 and the hairpin bends 56.
The bars 52, 54 of the ring 46 are longer than the bars of the ring 48
which in turn are longer than the bars of the ring 50. If the bars of the rings towards the
ends of the stent are shorter than the bars of the rings towards the middle of the stent,
this provides for greater stiffness towards the ends of the stent. This resists flaring o
the ends of the stent as it is expanded. It will be understood that any arrangement of
bar lengths can be chosen to provide ring-like zones of greater strength and ring-like
zones of lesser strength in any desired pattern. It is also possible to provide rings with different stiffnesses by varying the
widths of the hairpin bends, considered in the axial direction. Thus hairpin bends of
greater axial width can be provided at the ends of the stent to resist flaring of the ends
during expansion. The widths of the hairpin bends in the axial direction will always be
greater than the widths of the bars in the circumferential direction. Thus in Figure 3
W2/W1 will always be greater than 1.
The bars can include through slots and/or recesses for receiving drugs
which are to be released into the recipient of the stent.
To provide rings of differing stiffness the widths of the hairpin bends,
measured in the axial direction, can vary from one ring to another. A similar variation in
stiffness can be provided by means of bars which in one ring are of a different length to
the bars in another ring.

Claims

CLAIMS:
1. A stent of cylindrical form which comprises a plurality of rings extending
around the stent's longitudinal axis, the rings being spaced apart along the axis and
being joined to one another by longitudinals each of which spans between one ring and
an adjacent ring, each ring being of zig-zag form and comprising a plurality of first bars
all of which are parallel to one another and a plurality of second bars all of which are
parallel to one another and at an angle to the bars of the first set of bars, first bars
alternating with second bars and each first bar being joined at each end thereof to the
adjacent second bars by way of hairpin bends, the longitudinals joining the hairpin
bends of one ring to the hairpin bends of the adjacent ring, each of these rings having
between each adjacent pair of longitudinals, considered in the circumferential direction,
at least two, or any multiple of two, hairpin bends which are not joined to hairpin bends
of the adjacent ring.
2. A stent as claimed in claim 1 , wherein each bar has end portions
contiguous with the hairpin bends that join it to adjacent bars and a centre portion which
joins said end portions to one another, the centre portion being of non-linear
configuration.
3. A stent as claimed in claim 1 or 2, wherein each ring is a mirror image of
the ring, or rings, adjacent thereto about radial planes passing through the midpoints of the longitudinals.
4. A stent as claimed in claim 1 or 2, wherein said one ring and said adjacent
ring each comprise three first bars, three second bars and five hairpin bends between
each of said adjacent pairs of longitudinals thereby providing the two non-joined hairpin
bends on the facing sides of said rings and three hairpin bends on the sides of the rings
which face away from another, the centre ones of these hairpin bends being joined by
longitudinals to further rings.
5. A stent of cylindrical form which comprises a plurality of rings extending
around the stent's longitudinal axis, the rings being spaced apart along the axis and
being joined to one another by longitudinals each of which spans between one ring and
an adjacent ring, each ring being of zig-zag form and comprising a plurality of first bars
all of which are parallel to one another and a plurality of second bars all of which are
parallel to one another and at an angle to the bars of the first set of bars, first bars
alternating with second bars and each first bar being joined at each end thereof to the
adjacent second bars by way of hairpin bends, the longitudinals joining the hairpin
bends of one ring to the hairpin bends of the adjacent ring, each of these rings having
between each adjacent pair of longitudinals, considered in the circumferential direction,
at least two, or any multiple of two, hairpin bends which are not joined to hairpin bends
of the adjacent ring, each longitudinal connecting a first ring to a second ring being
midway between, considered in the circumferential direction, two further longitudinals which connect the first ring to a further ring and midway between two additional
longitudinals which connect the second ring to another ring, the further longitudinals
being spaced the same circumferential distance from one another as the two additional
longitudinals are spaced from one another and which is the same distance as the
spacing between the longitudinals connecting the first and second rings.
6. A stent of cylindrical form which comprises a plurality of rings extending
around the stent's longitudinal axis, the rings being spaced apart along the axis and
being joined to one another by longitudinals each of which spans between one ring and
an adjacent ring, each ring being of zig-zag form and comprises a plurality of first bars
all of which are parallel to one another and a plurality of second bars all of which are
parallel to one another and at an angle to the bars of the first set of bars, first bars
alternating with second bars and each first bar being joined at each end thereof to the
adjacent second bars by way of hairpin bends, the longitudinals joining the bends of
one ring to the bends of the adjacent ring, each longitudinal being of sinusoidal or
generally sinusoidal form, there being a first junction where one end of the longitudinal
is joined to one ring and a second junction where the other end of the longitudinal is
joined to an adjacent ring, said first junction being displaced circumferentially around
the stent with respect to the second junction, each ring being a mirror image of the
adjacent ring whereby each hairpin bend of said one ring is axially aligned with one of
the hairpin bends of said adjacent ring.
7. A stent as claimed in claim 6, wherein each longitudinal is joined to said
one ring at the junction between a first bar of said one ring and the hairpin bend at the
end of said first bar and is joined to the adjacent ring at the junction between a first bar
of said adjacent ring and the hairpin bend at the end of said first bar of the adjacent
ring, said first bars being in alignment with one another.
8. A stent as claimed in claim 6 or 7, wherein each group of three rings
comprises a centre ring, a first adjacent ring on one side of the centre ring and a
second adjacent ring on the other side of the centre ring, alternate hairpin bends on one
side of the centre ring being joined by longitudinals to the first adjacent ring and
alternate hairpin bends on the other side of the centre ring being joined by longitudinals
to the second adjacent ring.
9. A stent as claimed in any one of claims 1 to 8, wherein each bar of the
stent is narrower, considered in the circumferential direction, than the width of the
hairpin bends considered in the axial direction.
10. A stent as claimed in any one of claims 1 to 9, wherein each bar
comprises a centre section and end sections on each side of the centre section, the
end sections being narrower, considered in the circumferential direction, than the centre
section.
PCT/ZA2002/000116 2001-07-18 2002-07-18 Stents WO2003007842A2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2002354966A AU2002354966A1 (en) 2001-07-18 2002-07-18 Stents

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA2001/3691 2001-07-18
ZA200103691 2001-07-18

Publications (2)

Publication Number Publication Date
WO2003007842A2 true WO2003007842A2 (en) 2003-01-30
WO2003007842A3 WO2003007842A3 (en) 2003-09-25

Family

ID=25589152

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/ZA2002/000116 WO2003007842A2 (en) 2001-07-18 2002-07-18 Stents

Country Status (2)

Country Link
AU (1) AU2002354966A1 (en)
WO (1) WO2003007842A2 (en)

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WO2007102855A1 (en) * 2006-03-07 2007-09-13 Boston Scientific Scimed, Inc. Bifurcated stent with improved securement
US7758634B2 (en) 2001-02-26 2010-07-20 Boston Scientific Scimed, Inc. Bifurcated stent and delivery system
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US7850727B2 (en) 2001-08-20 2010-12-14 Innovational Holdings, Llc Expandable medical device for delivery of beneficial agent
US7850728B2 (en) 2000-10-16 2010-12-14 Innovational Holdings Llc Expandable medical device for delivery of beneficial agent
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