EP0817599A1 - Expandable surgical stent - Google Patents

Expandable surgical stent

Info

Publication number
EP0817599A1
EP0817599A1 EP96907602A EP96907602A EP0817599A1 EP 0817599 A1 EP0817599 A1 EP 0817599A1 EP 96907602 A EP96907602 A EP 96907602A EP 96907602 A EP96907602 A EP 96907602A EP 0817599 A1 EP0817599 A1 EP 0817599A1
Authority
EP
European Patent Office
Prior art keywords
stent
slots
locally
tubular member
regions
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP96907602A
Other languages
German (de)
French (fr)
Inventor
Anthony James Grass
Mohan Adiseshiah
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ADISESHIAH, MOHAN
GRASS, ANTHONY JAMES
Original Assignee
University College London
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 University College London filed Critical University College London
Publication of EP0817599A1 publication Critical patent/EP0817599A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS 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
    • A61F2/00—Filters 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
    • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90—Stents 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
    • A61F2/91—Stents 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
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS 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
    • A61F2/00—Filters 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
    • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90—Stents 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
    • A61F2/91—Stents 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
    • A61F2/915—Stents 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
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS 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
    • A61F2/00—Filters 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
    • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90—Stents 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
    • A61F2/91—Stents 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
    • A61F2/915—Stents 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
    • A61F2002/9155—Adjacent bands being connected to each other
    • A61F2002/91558—Adjacent bands being connected to each other connected peak to peak
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS 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
    • A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2230/0002—Two-dimensional shapes, e.g. cross-sections
    • A61F2230/0004—Rounded shapes, e.g. with rounded corners
    • A61F2230/0013—Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped

Definitions

  • This invention relates to expandable surgical stents for use with vascular grafts or
  • the surgical process of expandable intraluminal vascular grafting involves the insertion of a vascular graft into a blood vessel.
  • the graft is in the form of a fabric tube eg. of
  • the graft is manoeuvred using a balloon catheter to the desired position in the vessel, where the ste is expanded outwardly by
  • This procedure is common for example in the treatment of blocked a ⁇ eries, where, after opening the artery, the walls of the artery require internal support to prevent collapse; for the treatment of aortic and other aneurysms; and for the supportive reinforcement of constricted portions of the oesophagus, intestine and ureter, or other hollow viscera.
  • Such stents may take a variety of different forms, such as helically wound coils, and expandable structures of wires or bars.
  • a known surgical ste is disclosed in EP-A-0 221 570, and is shown in Figure 1 hereof.
  • the stem 70 comprises a thin- walled tube 71 in which
  • the slots 82 are of uniform length and are arranged both parallel to the longitudinal axis of the tubular member 71 and circumferentially, thereby
  • Each slot has ends bounded by members 77. which connect adjacent elongate members 75.
  • the tube 71 has a first diameter d that permits the stem 70 to be inserted into the
  • the stem 70 When in position, the stem 70 may be expanded by applying a radially outward force to the walls of the stent. This is achieved by inflating a balloon
  • the stent expands to a
  • the increase in the diameter of the stent is determined by controlling the volumetric expansion of the balloon portion of the catheter. Following the required inflation of the balloon, the balloon is deflated and the catheter removed, leaving the expanded stent in position.
  • the present invention provides an expandable stent for a
  • tubular eg. vascular
  • prosthesis for expanding or supporting a body passageway
  • said stem comprising a thin walled tubular member having slots defining a plurality of interconnected elongate members arranged such that the application of a distributed radially- outward force within the tubular member expands it radially by deformation thereof, so as to
  • the relatively weak portions are at the ends of the elongate members.
  • the relatively weak portions are defined by relatively enlarged regions of adjacent slots.
  • the invention provides an expandable stent for a tubular (eg. vascular) graft or prosthesis or for expanding or supporting a body passageway, said stent comprising a thin walled tubular member having therein a plurality of slots distributed circumferentially and longitudinally of said tube, characterised in that at least some of the slots have at least one locally-enlarged region, said regions defining an array of relatively weak portions in said tubular member whereby, on expanding said stent. said portions act as plastic hinges.
  • a tubular eg. vascular
  • prosthesis for expanding or supporting a body passageway
  • said stent comprising a thin walled tubular member having therein a plurality of slots distributed circumferentially and longitudinally of said tube, characterised in that at least some of the slots have at least one locally-enlarged region, said regions defining an array of relatively weak portions in said tubular member whereby, on expanding said stent. said portions act as plastic hinges.
  • the slots have a pair of separate locally-enlarged regions, each one of the pair being situated equidistant from the centre of the slot, for example at the
  • the slots have a further pair of locally enlarged regions, each locally enlarged region of said further pair being situated equidistant from the centre of the slot.
  • Each of one pair of locally enlarged regions situated in one slot is preferably aligned axially of the stent with one of the further pair of locally enlarged regions situated in a circumferentially adjacent slot.
  • a locally enlarged region may be formed by a round hole of diameter greater than the
  • the material between unenlarged regions of circumferentially adjacent slots remains substantially undeformed during expansion of the tubular member.
  • the slots may be equally spaced.
  • the slots may be formed by mechanical cutting or by electro-discharge machining.
  • the plurality of slots each have a first and a second end and the first ends of alternate circumferentially spaced slots are contained within the same radial plane perpendicular to the longitudinal axis of the tube.
  • the invention provides a tubular graft or prosthesis comprising at least one stent as set forth above.
  • Figure 1A is a perspective view of an expandable intraluminal stent according to the prior art.
  • Figure IB is a perspective view of the stent according to Figure 1 A in expanded form.
  • Figure 2 is a plan view of the expandable intraluminal stent according to the present
  • Figure 3 is a cross-section perpendicular to the longitudinal axis of the stent according to the present invention.
  • stent 100 comprises a seamless tubular member 102.
  • the member is preferably of uniform thickness, for example 250 ⁇ m thick, and may be formed from medical grade stainless steel, for example 316L.
  • the stent When for use in repair of an aortic aneurysm the stent has a length of typically 40 to 50mm, and a diameter of 5mm.
  • a plurality of slots 104 are provided within the member 102, thereby forming a plurality of elongate members 108 in the tubular member 102 that are joined by interconnections 110.
  • the slots may be formed by a variety of different conventional methods, such as mechanical or laser cutting, electro-discharge machining or electro-chemical machining, exposed edges being rounded or otherwise deburred and blunted to avoid presenting a sharp edge which may injure or irritate body tissue during insertion or subsequent use.
  • the length of each slot is preferably 9mm, and the width of the slot is preferably less than 200 ⁇ m.
  • the slots 104 are distributed both longitudinally and circumferentially of the tubular member. In this example.
  • Circumferentially spaced adjacent slots may also be arranged in a staggered relationship, as shown in Figure 2 where, in this example, the ends of alternate circumferentially spaced slots are contained within the same radial plane perpendicular to the longitudinal axis of the tubular member.
  • First 106 and second 107 pairs of locally-enlarged regions are formed in each of the slots 104, thereby forming portions of locally reduced cross-section 118 in the elongate members 108.
  • This is the preferred arrangement, but the invention is not limited to this particular number of locally-enlarged regions 106, 107.
  • the locally-enlarged regions 106, 107 preferably take the form of round holes of diameter greater than the width of the slot and preferably at least twice as wide. For example, for a slot width of 200 ⁇ m or less, the
  • each slot 104 contains two pairs of holes 106 and 107.
  • the holes of each pair are situated equidistant from centre 1 16 of the slot.
  • One pair, 107. is situated at the ends of the slots, whereas each of the other pair 106 is situated so as to be aligned axially of the stent with one of the pair of holes 107 in the circumferentially adjacent slot.
  • the cross-section of the portions 118 are substantially reduced in comparison with the cross- section of material between unenlarged regions of the slots 104 of the stent.
  • the width b of portion 118 is 253 ⁇ m ⁇ lO ⁇ m, compared to a width of approximately 0.45mm for the major portion of the elongate members 108.
  • the dimensions b is accurately controlled.
  • the positions and diameter of the holes 106,107 is subject to a close tolerance, but the width of the major part of the elongate members may be subject to a wider tolerance.
  • the holes are nominally 400 ⁇ m diameter, spaced longitudinally at 4.15mm centres and at 15° intervals circumferentially.
  • the stent 100 is expanded by inflating a balloon portion of a catheter placed within the stent substantially along the longitudinal axis of the stent 100.
  • the balloon comes into contact with the inner walls of the stent.
  • the balloon exerts a radially- outward force on the walls of the stent, causing the stent to radially expand by deformation
  • Portions of the stent 118 having a reduced cross-section are relatively weak compared to the material between the unenlarged regions of the slots of the stent, and so are preferentially deformed by the balloon. Due to the concentration of the deformation in the portions 1 18, the material of the members 108 between unenlarged regions of the slots remains substantially undeformed by the force acting on them by the expanding balloon.
  • the portions 1 18 act as plastic hinges, permitting pivotal movement of the members
  • the relatively weak portions in the walls of the stent thus determine the expansion characteristics of the stent and its final shape.
  • the final shape of the stent of the invention is therefore much more controlled than the final shape of known stents not provided with
  • T e size and location of the holes 106, 107 may be reliably controlled and repeatable in production of the stents. to the necessary degree of accuracy using known techniques. Because the resulting cross section of the plastic hinges 118 is markedly less t an that of the members 108. the small tolerance which is required in forming the holes 106, 107 can be substantially relaxed when forming the connecting slots, thus easing demands on the manufacturing process.
  • the stents may be made in a variety of sizes of both length and diameter, with different stiffnesses and ratios of expanded to unexpanded diameter, depending on the intended use in each case. They may be used alone to expand and/or support occluded or weak blood vessels or other body passageways (hollow viscera) or may be used in
  • An expandable stent for a tubular (eg. vascular) graft or prosthesis or for expanding or supporting a body passageway comprises a thin walled tubular member ( 102) having slots (104) defining a plurality of interconnected elongate members (108) arranged such that the application of a distributed radially-outward force within the tubular member expands it radially by deformation thereof, so as to open-out the slots, characterised by means (106,107) defining relatively weak portions ( 118) of locally-reduced cross section which upon expansion of the stent act as plastic hinges and in which said deformation is concentrated.

Abstract

An expandable stent for a tubular (e.g. vascular) graft or prosthesis or for expanding or supporting a body passageway comprises a thin walled tubular member (102) having slots (104) defining a plurality of interconnected elongate members (108) arranged such that the application of a distributed radially-outward force within the tubular member expands it radially by deformation thereof, so as to open-out the slots, characterised by means (106, 107) defining relatively weak portions (118) of locally-reduced cross section which upon expansion of the stent act as plastic hinges and in which said deformation is concentrated.

Description

EXPANDABLE SURGICAL STENT
This invention relates to expandable surgical stents for use with vascular grafts or
protheses or for the expansion and/or support of a blood vessel or other body passageway.
The surgical process of expandable intraluminal vascular grafting involves the insertion of a vascular graft into a blood vessel. The graft is in the form of a fabric tube eg. of
TEFLON® or DACRON® having attached thereto an expandable ste enabling it to be
attached to a healthy portion of blood vessel. The graft is manoeuvred using a balloon catheter to the desired position in the vessel, where the ste is expanded outwardly by
inflating the balloon to abut the inner surface of the vessel, thereby holding the graft in place.
This procedure is common for example in the treatment of blocked aπeries, where, after opening the artery, the walls of the artery require internal support to prevent collapse; for the treatment of aortic and other aneurysms; and for the supportive reinforcement of constricted portions of the oesophagus, intestine and ureter, or other hollow viscera.
Such stents may take a variety of different forms, such as helically wound coils, and expandable structures of wires or bars. A known surgical ste is disclosed in EP-A-0 221 570, and is shown in Figure 1 hereof. The stem 70 comprises a thin- walled tube 71 in which
a plurality of slots 82 are formed. The slots 82 are of uniform length and are arranged both parallel to the longitudinal axis of the tubular member 71 and circumferentially, thereby
forming elongate members 75 in the wall 74 of the tubular member 71. Each slot has ends bounded by members 77. which connect adjacent elongate members 75.
The tube 71 has a first diameter d that permits the stem 70 to be inserted into the
blood vessel or body passage. When in position, the stem 70 may be expanded by applying a radially outward force to the walls of the stent. This is achieved by inflating a balloon
portion of a catheter situated along the longitudinal axis of the stent. The stent expands to a
diameter d ' so that the walls of the stent come into contact with the inner walls of the blood
vessel. The increase in the diameter of the stent is determined by controlling the volumetric expansion of the balloon portion of the catheter. Following the required inflation of the balloon, the balloon is deflated and the catheter removed, leaving the expanded stent in position.
A problem that has been encountered in using the above stents occurs when there is
any variation in the cross-section of the elongate members 75 or connecting members 77.
Should a portion of one of such members have a enlarged cross-section, for example, it will be more resistant to bending (i.e. it will be stiffer), and so will undergo a smaller radial expansion than the remainder of the wall of the stent for a particular balloon pressure. Small
manufacturing irregularities in the initial unexpanded geometry of the stent can therefore produce significant irregularities in the final expanded form, compromising its effectiveness for purpose. Because the bending resistance is proportional to the square of the member width, the effect of small imperfections is magnified. The stent can therefore dilate under
internal balloon pressure in a haphazard and inconsistent manner. Such behaviour is surgically highly undesirable. It is therefore critical that the fabrication process for the prior art stents is such that the lattice of members 75. 77 are of very closely uniform cross-section.
This is both difficult and expensive.
It is an object of at least the preferred embodiments of the present invention to provide
an expandable stent that offers consistent expansion characteristics, leading to greater control over the final expanded shape of the stent. and repeatability in production. Accordingly, in one aspect the present invention provides an expandable stent for a
tubular (eg. vascular) graft or prosthesis or for expanding or supporting a body passageway, said stem comprising a thin walled tubular member having slots defining a plurality of interconnected elongate members arranged such that the application of a distributed radially- outward force within the tubular member expands it radially by deformation thereof, so as to
open-out the slots, characterised by means defining relatively weak portions of locally-reduced cross section which upon expansion of the stent act as plastic hinges and in which said deformation is concentrated.
Preferably, the relatively weak portions are at the ends of the elongate members. The relatively weak portions are defined by relatively enlarged regions of adjacent slots.
In another aspect the invention provides an expandable stent for a tubular (eg. vascular) graft or prosthesis or for expanding or supporting a body passageway, said stent comprising a thin walled tubular member having therein a plurality of slots distributed circumferentially and longitudinally of said tube, characterised in that at least some of the slots have at least one locally-enlarged region, said regions defining an array of relatively weak portions in said tubular member whereby, on expanding said stent. said portions act as plastic hinges.
Preferably, at least some of the slots have a pair of separate locally-enlarged regions, each one of the pair being situated equidistant from the centre of the slot, for example at the
ends of the slots.
Advantageously, at least some of the slots have a further pair of locally enlarged regions, each locally enlarged region of said further pair being situated equidistant from the centre of the slot. Each of one pair of locally enlarged regions situated in one slot is preferably aligned axially of the stent with one of the further pair of locally enlarged regions situated in a circumferentially adjacent slot.
A locally enlarged region may be formed by a round hole of diameter greater than the
width of the slot.
Preferably, the material between unenlarged regions of circumferentially adjacent slots remains substantially undeformed during expansion of the tubular member.
In both of the above aspects of the present invention, the slots may be equally
circumferentially spaced around the tube, and preferably in a staggered relationship. The slots may be formed by mechanical cutting or by electro-discharge machining.
Preferably, the plurality of slots each have a first and a second end and the first ends of alternate circumferentially spaced slots are contained within the same radial plane perpendicular to the longitudinal axis of the tube.
In another aspect the invention provides a tubular graft or prosthesis comprising at least one stent as set forth above.
The invention will now be described with reference to the accompanying drawings in which:-
Figure 1A is a perspective view of an expandable intraluminal stent according to the prior art.
Figure IB is a perspective view of the stent according to Figure 1 A in expanded form.
Figure 2 is a plan view of the expandable intraluminal stent according to the present
invention which, for greater clarity, does not show all of the slots formed in the wall of the tube. Such slots as are shown are in a plane development so that their relative positions can
be seen. Figure 3 is a cross-section perpendicular to the longitudinal axis of the stent according to the present invention.
Referring to Figure 2, stent 100 comprises a seamless tubular member 102. The
member is preferably of uniform thickness, for example 250 μm thick, and may be formed from medical grade stainless steel, for example 316L. When for use in repair of an aortic aneurysm the stent has a length of typically 40 to 50mm, and a diameter of 5mm.
A plurality of slots 104 are provided within the member 102, thereby forming a plurality of elongate members 108 in the tubular member 102 that are joined by interconnections 110. The slots may be formed by a variety of different conventional methods, such as mechanical or laser cutting, electro-discharge machining or electro-chemical machining, exposed edges being rounded or otherwise deburred and blunted to avoid presenting a sharp edge which may injure or irritate body tissue during insertion or subsequent use. For example, for a stent 40mm long and 5mm in diameter, the length of each slot is preferably 9mm, and the width of the slot is preferably less than 200μm. The slots 104 are distributed both longitudinally and circumferentially of the tubular member. In this example. the longitudinal spacing between the slots is 250 μm. and the circumferential spacing between adjacent slots is such that there is an angular pitch of 15° between the centres of the slots, as shown in Figure 3. Circumferentially spaced adjacent slots may also be arranged in a staggered relationship, as shown in Figure 2 where, in this example, the ends of alternate circumferentially spaced slots are contained within the same radial plane perpendicular to the longitudinal axis of the tubular member.
First 106 and second 107 pairs of locally-enlarged regions are formed in each of the slots 104, thereby forming portions of locally reduced cross-section 118 in the elongate members 108. This is the preferred arrangement, but the invention is not limited to this particular number of locally-enlarged regions 106, 107. The locally-enlarged regions 106, 107 preferably take the form of round holes of diameter greater than the width of the slot and preferably at least twice as wide. For example, for a slot width of 200 μm or less, the
diameter of the hole may be 400 μm. In the preferred embodiment shown in Figure 2, each slot 104 contains two pairs of holes 106 and 107. The holes of each pair are situated equidistant from centre 1 16 of the slot. One pair, 107. is situated at the ends of the slots, whereas each of the other pair 106 is situated so as to be aligned axially of the stent with one of the pair of holes 107 in the circumferentially adjacent slot. With this configuration, the cross-section of the portions 118 are substantially reduced in comparison with the cross- section of material between unenlarged regions of the slots 104 of the stent. In this example, the width b of portion 118 is 253μm ± lOμm, compared to a width of approximately 0.45mm for the major portion of the elongate members 108. For the stent to have consistent expansion characteristics, it is important that the dimension b is accurately controlled. Thus the positions and diameter of the holes 106,107 is subject to a close tolerance, but the width of the major part of the elongate members may be subject to a wider tolerance. In this example the holes are nominally 400μm diameter, spaced longitudinally at 4.15mm centres and at 15° intervals circumferentially.
In operation, the stent 100 is expanded by inflating a balloon portion of a catheter placed within the stent substantially along the longitudinal axis of the stent 100. When the balloon comes into contact with the inner walls of the stent. the balloon exerts a radially- outward force on the walls of the stent, causing the stent to radially expand by deformation
so as to open-out the slots 104. Portions of the stent 118 having a reduced cross-section are relatively weak compared to the material between the unenlarged regions of the slots of the stent, and so are preferentially deformed by the balloon. Due to the concentration of the deformation in the portions 1 18, the material of the members 108 between unenlarged regions of the slots remains substantially undeformed by the force acting on them by the expanding balloon. The portions 1 18 act as plastic hinges, permitting pivotal movement of the members
108 between the hinges as the diameter of the stent expands.
The relatively weak portions in the walls of the stent thus determine the expansion characteristics of the stent and its final shape. The final shape of the stent of the invention is therefore much more controlled than the final shape of known stents not provided with
defined points of weakness, thereby providing a significant improvement in the safety of vascular grafting or prostheses operations with the final shape of the stent. and its expansion behaviour, being much more consistent and reliable. T e size and location of the holes 106, 107 may be reliably controlled and repeatable in production of the stents. to the necessary degree of accuracy using known techniques. Because the resulting cross section of the plastic hinges 118 is markedly less t an that of the members 108. the small tolerance which is required in forming the holes 106, 107 can be substantially relaxed when forming the connecting slots, thus easing demands on the manufacturing process.
The stents may be made in a variety of sizes of both length and diameter, with different stiffnesses and ratios of expanded to unexpanded diameter, depending on the intended use in each case. They may be used alone to expand and/or support occluded or weak blood vessels or other body passageways (hollow viscera) or may be used in
combination with a tubular prosthesis or graft to anchor the ends of the prosthesis in healthy but spaced-apart portions of a duct (eg. the aorta) enabling an intervening weak or damaged portion of the duct to be bridged by the graft. Each feature disclosed in this specification (which term includes the claims) and/or shown in the drawings may be incorporated in the invention independently of other disclosed and/or illustrated features.
SUMMARY
An expandable stent for a tubular (eg. vascular) graft or prosthesis or for expanding or supporting a body passageway comprises a thin walled tubular member ( 102) having slots (104) defining a plurality of interconnected elongate members (108) arranged such that the application of a distributed radially-outward force within the tubular member expands it radially by deformation thereof, so as to open-out the slots, characterised by means (106,107) defining relatively weak portions ( 118) of locally-reduced cross section which upon expansion of the stent act as plastic hinges and in which said deformation is concentrated.

Claims

1. An expandable stent for a tubular graft or prosthesis or for expanding or supporting a body passageway, said stent comprising a thin walled tubular member having slots defining a plurality of interconnected elongate members arranged such that the application of a
distributed radially-outward force within the tubular member expands it radially by deformation thereof, so as to open-out the slots, characterised by means defining relatively weak portions of locally-reduced cross section which upon expansion of the stent act as plastic hinges and in which said deformation is concentrated.
2. A stent as claimed in claim 1, wherein the relatively weak portions are at the ends of the elongate members.
3. A stent as claimed in claim 1 or claim 2, wherein the relatively weak portions are defined by relatively enlarged regions of adjacent slots.
4. An expandable stent for a tubular graft or prosthesis or for expanding or supporting a body passageway, said stent comprising a thin walled tubular member having therein a plurality of slots distributed circumferentially and longitudinally of said tube, characterised in that at least some of the slots have at least one locally-enlarged region, said regions defining an array of relatively weak portions in said tubular member whereby, on expanding
said stent, said portions act as plastic hinges.
5. A stent as claimed in any preceding claim, wherein said slots are equally
circumferentially spaced around the tube.
6. A stent as claimed in Claim 4 or Claim 5, wherein circumferentially spaced adjacent slots are arranged in a staggered relationship.
7. A stent as claimed in Claim 6. wherein the plurality of slots each have a first end and a second end and where the first ends of alternate circumferentially spaced slots are contained within the same radial plane perpendicular to the longitudinal axis of the tube.
8. A stent as claimed in Claim 4. wherein at least some of said slots have a pair of
separate locally-enlarged regions, each one of said pair being situated equidistant from the centre of the slot.
9. A stent as claimed in Claim 8. wherein said pair of locally-enlarged regions are situated at the ends of the slots.
10. A stent as claimed in Claim 8 or Claim 9, wherein at least some of said slots have a
further pair of locally-enlarged regions, each locally-enlarged region of said further pair being
situated equidistant from the centre of the slot.
1 1. A stent as claimed in Claim 10. wherein each of one pair of locally-enlarged regions
situated in one slot are aligned axially of the stent with one of the further pair of locally-
enlarged regions situated in a circumferentially adjacent slot.
12. A stent as claimed in Claim 3 or Claim 4, wherein a said locally-enlarged region is
formed by a round hole of diameter greater than the width of the slot.
13. A stent as claimed in any of the preceding claims, wherein said tubular member is of uniform wall thickness.
14. A stent as claimed in any of the preceding claims, wherein the slots are formed b
mechanical cutting.
15. A stent as claimed in any one of Claims 1 to 12. wherein the slots are formed by electro-discharge machining.
16. A stent as claimed in Claim 4, wherein the material between unenlarged regions of circumferentially adjacent slots remains substantially undeformed during expansion of the tubular member.
17. A tubular graft or prosthesis including at least one stent as claimed in any preceding
claim.
EP96907602A 1995-03-21 1996-03-21 Expandable surgical stent Withdrawn EP0817599A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB9505721 1995-03-21
GB9505721A GB9505721D0 (en) 1995-03-21 1995-03-21 Expandable surgical stent
PCT/GB1996/000676 WO1996029028A1 (en) 1995-03-21 1996-03-21 Expandable surgical stent

Publications (1)

Publication Number Publication Date
EP0817599A1 true EP0817599A1 (en) 1998-01-14

Family

ID=10771599

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96907602A Withdrawn EP0817599A1 (en) 1995-03-21 1996-03-21 Expandable surgical stent

Country Status (5)

Country Link
EP (1) EP0817599A1 (en)
AU (1) AU722946B2 (en)
CA (1) CA2216522A1 (en)
GB (1) GB9505721D0 (en)
WO (1) WO1996029028A1 (en)

Families Citing this family (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0934036B1 (en) * 1996-10-28 2004-03-03 BIOTRONIK Mess- und Therapiegeräte GmbH & Co Ingenieurbüro Berlin Stent
CA2278640C (en) 1997-01-24 2007-12-11 Petrus Antonius Besselink Bistable spring construction for a stent and other medical apparatus
US8663311B2 (en) 1997-01-24 2014-03-04 Celonova Stent, Inc. Device comprising biodegradable bistable or multistable cells and methods of use
US8353948B2 (en) 1997-01-24 2013-01-15 Celonova Stent, Inc. Fracture-resistant helical stent incorporating bistable cells and methods of use
DE19722857A1 (en) * 1997-05-23 1998-11-26 Biotronik Mess & Therapieg Stent
US7208010B2 (en) 2000-10-16 2007-04-24 Conor Medsystems, Inc. Expandable medical device for delivery of beneficial agent
US6241762B1 (en) * 1998-03-30 2001-06-05 Conor Medsystems, Inc. Expandable medical device with ductile hinges
US20040254635A1 (en) 1998-03-30 2004-12-16 Shanley John F. Expandable medical device for delivery of beneficial agent
EP1222941B2 (en) 1998-03-30 2009-04-22 Conor Medsystems, Inc. Flexible medical device
US6293967B1 (en) 1998-10-29 2001-09-25 Conor Medsystems, Inc. Expandable medical device with ductile hinges
US6290673B1 (en) 1999-05-20 2001-09-18 Conor Medsystems, Inc. Expandable medical device delivery system and method
US6799637B2 (en) 2000-10-20 2004-10-05 Schlumberger Technology Corporation Expandable tubing and method
AU9463401A (en) 2000-10-16 2002-04-29 Conor Medsystems Inc Expandable medical device for delivery of beneficial agent
EP1676547A1 (en) 2001-02-05 2006-07-05 Conor Medsystems, Inc. Expandable medical device
US20040073294A1 (en) 2002-09-20 2004-04-15 Conor Medsystems, Inc. Method and apparatus for loading a beneficial agent into an expandable medical device
US6964680B2 (en) 2001-02-05 2005-11-15 Conor Medsystems, Inc. Expandable medical device with tapered hinge
US7842083B2 (en) 2001-08-20 2010-11-30 Innovational Holdings, Llc. Expandable medical device with improved spatial distribution
AU2004226327A1 (en) 2003-03-28 2004-10-14 Innovational Holdings, Llc Implantable medical device with beneficial agent concentration gradient
US7785653B2 (en) 2003-09-22 2010-08-31 Innovational Holdings Llc Method and apparatus for loading a beneficial agent into an expandable medical device
US8435280B2 (en) 2005-03-31 2013-05-07 Boston Scientific Scimed, Inc. Flexible stent with variable width elements
US8211162B2 (en) 2007-05-25 2012-07-03 Boston Scientific Scimed, Inc. Connector node for durable stent

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2671280B1 (en) * 1991-01-03 1993-03-05 Sgro Jean Claude SELF-EXHIBITING VASCULAR STENT WITH PERMANENT ELASTICITY, LOW SHORTENING AND ITS APPLICATION MATERIAL.
DE4303181A1 (en) * 1993-02-04 1994-08-11 Angiomed Ag Implantable catheter
FR2710834B1 (en) * 1993-10-05 1995-12-22 Guerbet Sa Expandable tubular organ for intraluminal endoprosthesis, intraluminal endoprosthesis, manufacturing process.

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9629028A1 *

Also Published As

Publication number Publication date
WO1996029028A1 (en) 1996-09-26
AU5116896A (en) 1996-10-08
AU722946B2 (en) 2000-08-17
CA2216522A1 (en) 1996-09-26
GB9505721D0 (en) 1995-05-10

Similar Documents

Publication Publication Date Title
AU722946B2 (en) Expandable surgical stent
EP0824902B1 (en) Expandable stent
US5810872A (en) Flexible stent
KR100386784B1 (en) Expansive branch stent and its implantation method
US5861027A (en) Stent for the transluminal implantation in hollow organs
CA2144305C (en) A flexible stent having a pattern formed from a sheet of material
EP1342455B1 (en) Expandable supportive branched endoluminal grafts
JP4659159B2 (en) Bifurcated stent and manufacturing method thereof
US4739762A (en) Expandable intraluminal graft, and method and apparatus for implanting an expandable intraluminal graft
US6436133B1 (en) Expandable graft
US5913897A (en) Endoprosthesis having multiple bridging junctions and procedure
EP0903120B1 (en) Aortic graft
CA2141917C (en) Bi-directional crimped graft
US5195984A (en) Expandable intraluminal graft
US5102417A (en) Expandable intraluminal graft, and method and apparatus for implanting an expandable intraluminal graft
US5911732A (en) Articulated expandable intraluminal stent
US20100004728A1 (en) Graft endoframe having axially variable characteristics
AU741328B2 (en) Microporous stent and implantation device
EP1302179A2 (en) Flexible stent
JP2004073876A (en) Expandable intravascular stent
JPH0268052A (en) Internal prosthetic jig expansible in radius direction and production thereof
EP0806191A1 (en) Expandable intraluminal graft or stent

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19971021

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: ADISESHIAH, MOHAN

Owner name: GRASS, ANTHONY JAMES

RIN1 Information on inventor provided before grant (corrected)

Inventor name: ADISESHIAH, MOHAN

Inventor name: GRASS, ANTHONY JAMES

17Q First examination report despatched

Effective date: 20010704

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20011115