WO2006117545A1 - Manufacturing method for a non- planar curved stent - Google Patents

Manufacturing method for a non- planar curved stent Download PDF

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Publication number
WO2006117545A1
WO2006117545A1 PCT/GB2006/001598 GB2006001598W WO2006117545A1 WO 2006117545 A1 WO2006117545 A1 WO 2006117545A1 GB 2006001598 W GB2006001598 W GB 2006001598W WO 2006117545 A1 WO2006117545 A1 WO 2006117545A1
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WO
WIPO (PCT)
Prior art keywords
hollow structure
shape
stent
tool
modified
Prior art date
Application number
PCT/GB2006/001598
Other languages
French (fr)
Inventor
Colin Caro
Original Assignee
Veryan Medical Limited
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 Veryan Medical Limited filed Critical Veryan Medical Limited
Priority to AU2006243061A priority Critical patent/AU2006243061A1/en
Priority to EP06726977A priority patent/EP1874124A1/en
Priority to JP2008508309A priority patent/JP2008538961A/en
Priority to BRPI0611022A priority patent/BRPI0611022A2/en
Priority to CA002605812A priority patent/CA2605812A1/en
Publication of WO2006117545A1 publication Critical patent/WO2006117545A1/en
Priority to IL186549A priority patent/IL186549A0/en

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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
    • 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
    • A61F2/02—Prostheses implantable into the body
    • A61F2/04—Hollow or tubular parts of organs, e.g. bladders, tracheae, bronchi or bile ducts
    • A61F2/06—Blood vessels
    • A61F2002/068—Modifying the blood flow model, e.g. by diffuser or deflector
    • 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
    • A61F2210/00—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2210/0014—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof using shape memory or superelastic materials, e.g. nitinol
    • A61F2210/0023—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof using shape memory or superelastic materials, e.g. nitinol operated at different temperatures whilst inside or touching the human body, heated or cooled by external energy source or cold supply
    • A61F2210/0028—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof using shape memory or superelastic materials, e.g. nitinol operated at different temperatures whilst inside or touching the human body, heated or cooled by external energy source or cold supply cooled
    • 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
    • A61F2230/0063—Three-dimensional shapes
    • A61F2230/0091—Three-dimensional shapes helically-coiled or spirally-coiled, i.e. having a 2-D spiral cross-section

Definitions

  • This invention relates to methods of manufacturing stents for insertion in a fluid conduit of the human or animal body.
  • Stents are generally tubular devices used for providing physical support to biological conduits, including blood vessels, i.e. they can be used to help prevent kinking or occlusion of conduits such as veins or arteries and to prevent their collapse after dilatation or other treatment.
  • Stents can be broadly divided into two main categories: balloon expandable stents and self-expanding stents.
  • the material of the stent is plastically deformed through the inflation of a balloon, so that after the balloon is deflated the stent remains in the expanded shape.
  • Such stents are manufactured in the "collapsed" condition, ready for delivery, and may be expanded to the expanded condition when inside the vessel or other fluid conduit.
  • Self-expanding stents are also designed to be delivered in the collapsed condition and when released from a constraining delivery system the stent expands to its expanded condition of a predetermined size. This effect is achieved by using the elasticity of the material and/or a shape-memory or superelastic effect.
  • shape-memory or superelastic stents a commonly used material is nitinol.
  • stents are available on the market. They are made from a variety of materials providing corrosion resistance and biocompatibility, therapeutic opportunities such as the release of chemicals, ionizing radiation activity, and biodegradability. If metallic, they are made from sheet, round or flat wire or tubing. They are formed as a mesh and are generally cylindrical but also longitudinally flexible so as to conform to the curvature of the fluid conduit into which they are inserted.
  • shape-memory alloys to make self-expanding stents is advantageous because a stent can be cooled for easy insertion into a restraining sleeve or other constraining delivery system.
  • the constraint is removed by the operator and the stent adopts the shape "programmed" into its memory at body temperatures, for example around 37 0 C for the human body.
  • the expanded shape of the stent at body temperatures is usually a cylinder having a straight longitudinal axis, but because of the resilience of the stent when deployed it is longitudinally flexible to conform to the curvature of the fluid conduit without kinking or collapsing.
  • a stent made of shape-memory alloy for supporting part of a blood vessel.
  • the stent includes a supporting portion around which or within which part of a blood vessel intended for grafting can be placed so that the stent internally or externally supports that part.
  • the supporting portion of the stent is shaped so that flow between graft and host vessel is caused to follow a non-planar curve. This generates a swirl flow, to provide a favourable blood flow velocity pattern which reduces the occurrence of vascular disease, particularly intimal hyperplasia.
  • a stent in this case including a supporting portion around which or within which part of an intact blood vessel other than a graft can be placed.
  • This supporting portion can prevent failure of the vessel through blockage, kinking or collapse.
  • the supporting portion of the stent is of a shape and/or orientation whereby flow within the vessel is caused to follow a non-planar curve.
  • Favorable blood flow velocity patterns can be achieved through generation therein of swirl flow within and beyond the stent. Failures in blood vessels through diseases such as thrombosis, atherosclerosis, intimal hyperplasia can thereby be significantly reduced.
  • a method of making a stent which, when the stent is inserted in a fluid conduit of the human or animal body defines a flow lumen following a non-planar curve, the method comprising providing a tubular hollow structure having a longitudinally extending cavity and made of a shape memory material, modifying the shape of the hollow structure into a shape in which its longitudinally extending cavity follows a non-planar curve, heating the modified hollow structure to a temperature such that the modified shape is memorised by the shape memory material, and cooling the hollow structure.
  • Such a stent may be held in a constraining delivery system and when in place in the fluid conduit it will expand and seek to adopt its shape at body temperature, e.g. 37 0 C. It will thus define and impose a non-planar flow lumen therein. Flow within the fluid conduit supported by the stent can follow a non- planar curve, promoting swirl flow, the benefits of which are discussed above.
  • the flow lumen of the conduit as this extends in the longitudinal direction (x-axis) it curves in more than one plane (i.e. in both the y- axis and the z-axis).
  • the flow lumen extends generally helically in the longitudinal direction.
  • the flow lumen has a centre line (a line joining centroids of adjacent cross-sections) which extends generally helically.
  • the shape memory property of the stent is used not just to facilitate insertion in a delivery system and expansion to a much wider shape, as is conventional, but also to provide a flow lumen modified from the conventional linear shape.
  • a conventionally shaped stent may be used as a starting point in the method of the invention.
  • Known stents are typically designed to be longitudinally flexible to conform to the curvature of a vessel in which they are inserted.
  • a stent modified from a linear shape to a generally helical shape is able to impose a generally helical shape when deployed in a fluid conduit, albeit with a reduced helical amplitude.
  • the tubular hollow structure initially has a cylindrical shape, for example of circular cross-section, with a straight centre line. It is this shape which is then modified such that the longitudinally extending cavity follows a non-planar curve.
  • the hollow structure may comprise a plurality of circumferentially extending rings with adjacent rings being longitudinally joined at intervals around the circumference of the structure. Typical numbers of joints between rings are four or six.
  • One known way of making stents is to laser cut them from a cylindrical tube.
  • laser cutting can take place before the shape modification step, when the tube is still cylindrical, thereby avoiding the complexity of seeking to make a helical tube and then laser cut it.
  • the shape of the hollow structure may be modified by placing it along a flexible rod and twisting both the hollow structure and the rod so that both adopt a generally helical shape.
  • the shape of the hollow structure is modified by winding it round a tool, such as a mandrel.
  • the tool is preferably substantially rigid.
  • the tool may be a simple cylinder, but in order to provide control of the shape of the hollow structure (in particular the pitch and amplitude thereof) the tool may have a helical groove for receiving the hollow structure.
  • the shape of the hollow structure may for example be modified by placing it along a machined groove in a rod shaped tool.
  • the hollow structure is constrained in contact with the tool, so that it does not return to the original cylindrical shape during heat treatment. This can be done using a wire along the inside of the hollow structure and/or a sleeve placed externally of the hollow structure and rod
  • the hollow structure and tool may be together inserted in a suitable sleeve.
  • a tool preferably has a helical shape, preferably with a plurality of helical turns.
  • the tool may take the form of a helical rod.
  • This method will generally not require the use of a sleeve or other constraint around the hollow structure and therefore has the advantage that the heating and cooling of the hollow structure can be carried out with greater uniformity and more rapidly. It is generally desirable to cool the hollow structure quickly, for example by quenching it in water, and this is facilitated by a method in which the rod or mandrel has a relatively small mass and the hollow structure is exposed directly to the cooling means. This method also provides superior constraint and improved control over the new helical set shape.
  • Figure 1 shows a mandrel for use in the method of the invention
  • Figure 2 shows a hollow structure inserted into a groove in the mandrel
  • Figure 3 shows the hollow structure after it has been removed from the mandrel
  • Figure 4 shows another form of mandrel
  • Figure 5 shows a hollow structure with the mandrel of Figure 4 inserted therein.
  • a tool in the form of a mandrel 2 is made from stainless steel and is formed with a helical groove 4 extending along its length.
  • the groove 2 has a diameter suitable to receive a hollow structure 6, as seen in Figure 2.
  • the hollow structure is a conventional cylindrical stent made of shape memory alloy, which is deformed from its usual linear shape to a shape following the helical groove of the mandrel.
  • the stent initially has a cylindrical shape, with a circular cross-section. As seen in Figure 3, it has a series of rings 7 which, when the stent is in its initial cylindrical form, are all arranged parallel to each other.
  • Each ring 7 consists of a zigzag configuration of struts, so that adjacent struts form a crown 5 and each ring has a plurality of crowns 5.
  • Joint portions 9 between the crowns of adjacent rings are provided at circumferential intervals around the rings.
  • a ring may have eighteen crowns and there may be six joint portions between adjacent rings.
  • Figure 4 shows another form of mandrel 8, in the form of a stainless steel rod having a helical shape.
  • the rod has been made by milling in a CNC milling machine .
  • An alternative technique for making the mandrel is to heat a stainless steel rod and then thread it into a helical groove in a former having a shape such as that of the mandrel show in Figure 1.
  • the mandrel 8 is designed to be inserted inside the hollow structure 6 of a conventional shape memory alloy stent, so as to modify the longitudinal cavity of the hollow structure to conform to the shape of the helical rod.
  • the outside diameter of the mandrel is slightly smaller than the inside diameter of the stent.
  • a 5.8 mm diameter mandrel may be inserted in a 6 mm diameter stent.
  • the stent with the mandrel inside is seen in Figure 5.
  • a nitinol stent was used, having an outside diameter of 8 mm.
  • the stent was placed in the groove 4 of the mandrel 2 as shown in Figure 2.
  • a steel sleeve (8). It was placed in a hot furnace heated to 500 0 C in an inert (oxygen free) atmosphere (argon) for 15 minutes.
  • the mandrel, hollow structure and sleeve were then immersed in water at a temperature of 2O 0 C so as to be rapidly cooled.
  • the sleeve was removed and the stent was separated from the mandrel.
  • the stent so made When the stent so made is cooled to below 5 0 C, for example by being placed in iced water, it is easily manipulated and so can be readily placed in a collapsed condition constrained by an appropriate delivery system.
  • the stent When the stent is deployed in a fluid conduit of the human or animal body, it expands to a helical shape, so as to define a flow lumen following a non-planar curve.
  • the mandrel of Figure 4 was inserted in a the same type of stent as described in Example 1.
  • the stent and mandrel were placed in a hot furnace heated to 500 0 C in an inert (oxygen free) atmosphere (argon) for 15 minutes. They were then immersed in water at a temperature of 2O 0 C so as to be rapidly cooled.
  • the stent and mandrel were separated and the stent had adopted a helical shape. By cooling this stent to below 5 0 C it can be easily constrained in a delivery system. When it is deployed in a fluid conduit of a human or animal body it defines a flow lumen following a non-planar curve.
  • the stent after separation from the mandrel the stent had the helical shape shown in Figure 3. Adjacent rings on the inside of the helix are closer together or overlap, whilst those on the outside are further apart.
  • the modification of the relative positions of the rings whereby the stent adopts the helical shape is achieved by the mandrel and the heating step. It is possible to avoid initial fabrication of a stent with a complex variation in the lengths and orientations of the struts and the joints between them to obtain the desired helical shape.

Abstract

A method of making a stent which, when the stent is inserted in a fluid conduit of the human or animal body defines a flow lumen following a non- planar curve, the method comprising providing a tubular hollow structure having a longitudinally extending cavity and made of a shape memory material, modifying the shape of the hollow structure into a shape in which its longitudinally extending cavity follows a non-planar curve, heating the modified hollow structure to a temperature such that the modified shape is memorised by the shape memory material, and cooling the hollow structure.

Description

MANUFACTURING METHOD FOR A NON- PLANAR CURVED STENT
This invention relates to methods of manufacturing stents for insertion in a fluid conduit of the human or animal body.
Stents are generally tubular devices used for providing physical support to biological conduits, including blood vessels, i.e. they can be used to help prevent kinking or occlusion of conduits such as veins or arteries and to prevent their collapse after dilatation or other treatment.
Stents can be broadly divided into two main categories: balloon expandable stents and self-expanding stents. In the case of the former the material of the stent is plastically deformed through the inflation of a balloon, so that after the balloon is deflated the stent remains in the expanded shape. Such stents are manufactured in the "collapsed" condition, ready for delivery, and may be expanded to the expanded condition when inside the vessel or other fluid conduit.
Self-expanding stents are also designed to be delivered in the collapsed condition and when released from a constraining delivery system the stent expands to its expanded condition of a predetermined size. This effect is achieved by using the elasticity of the material and/or a shape-memory or superelastic effect. In the case of shape-memory or superelastic stents a commonly used material is nitinol.
Many different designs of stents are available on the market. They are made from a variety of materials providing corrosion resistance and biocompatibility, therapeutic opportunities such as the release of chemicals, ionizing radiation activity, and biodegradability. If metallic, they are made from sheet, round or flat wire or tubing. They are formed as a mesh and are generally cylindrical but also longitudinally flexible so as to conform to the curvature of the fluid conduit into which they are inserted.
The use of shape-memory alloys to make self-expanding stents is advantageous because a stent can be cooled for easy insertion into a restraining sleeve or other constraining delivery system. Once the stent is in position in the fluid conduit of the human or animal body the constraint is removed by the operator and the stent adopts the shape "programmed" into its memory at body temperatures, for example around 370C for the human body. The expanded shape of the stent at body temperatures is usually a cylinder having a straight longitudinal axis, but because of the resilience of the stent when deployed it is longitudinally flexible to conform to the curvature of the fluid conduit without kinking or collapsing.
We have previously proposed that the flow pattern in arteries including the swirling pattern induced by their non-planar geometry operates to inhibit the development of vascular diseases such as thrombosis, atherosclerosis and intimal hyperplasia.
In WO 98/53764, there is disclosed a stent made of shape-memory alloy for supporting part of a blood vessel. The stent includes a supporting portion around which or within which part of a blood vessel intended for grafting can be placed so that the stent internally or externally supports that part. The supporting portion of the stent is shaped so that flow between graft and host vessel is caused to follow a non-planar curve. This generates a swirl flow, to provide a favourable blood flow velocity pattern which reduces the occurrence of vascular disease, particularly intimal hyperplasia.
In WO 00/32241, there is disclosed another type of stent, in this case including a supporting portion around which or within which part of an intact blood vessel other than a graft can be placed. This supporting portion can prevent failure of the vessel through blockage, kinking or collapse. Again, the supporting portion of the stent is of a shape and/or orientation whereby flow within the vessel is caused to follow a non-planar curve. Favorable blood flow velocity patterns can be achieved through generation therein of swirl flow within and beyond the stent. Failures in blood vessels through diseases such as thrombosis, atherosclerosis, intimal hyperplasia can thereby be significantly reduced.
Further aspects of how swirl flow is beneficial are explained in the above publications. It is further explained in Caro et al. (1998) J. Physiol. 513P,2P how non-planar geometry of tubing inhibits flow instability. Further information on this topic is given in Caro et al (2005) J.Roy Soc. Interface 2, 261 - 266.
We have now found a way of producing an internal stent which facilitates flow within the stent supported fluid conduit to follow a non-planar curve, i.e. to swirl. We have realised that the shape-memory properties of a stent made from shape-memory material can be exploited to modify an existing cylindrical stent into one promoting swirl flow. This means that existing cylindrical stents made from shape-memory material can be used as a starting point in the new method, thereby avoiding complex geometric, mechanical or structural modification of the wires or struts or other structural components forming the stent wall.
According to the invention there is provided a method of making a stent which, when the stent is inserted in a fluid conduit of the human or animal body defines a flow lumen following a non-planar curve, the method comprising providing a tubular hollow structure having a longitudinally extending cavity and made of a shape memory material, modifying the shape of the hollow structure into a shape in which its longitudinally extending cavity follows a non-planar curve, heating the modified hollow structure to a temperature such that the modified shape is memorised by the shape memory material, and cooling the hollow structure.
Such a stent may be held in a constraining delivery system and when in place in the fluid conduit it will expand and seek to adopt its shape at body temperature, e.g. 370C. It will thus define and impose a non-planar flow lumen therein. Flow within the fluid conduit supported by the stent can follow a non- planar curve, promoting swirl flow, the benefits of which are discussed above. Thus, considering the flow lumen of the conduit, as this extends in the longitudinal direction (x-axis) it curves in more than one plane (i.e. in both the y- axis and the z-axis). hi other words, the flow lumen extends generally helically in the longitudinal direction. The flow lumen has a centre line (a line joining centroids of adjacent cross-sections) which extends generally helically.
The shape memory property of the stent is used not just to facilitate insertion in a delivery system and expansion to a much wider shape, as is conventional, but also to provide a flow lumen modified from the conventional linear shape. Thus a conventionally shaped stent may be used as a starting point in the method of the invention. Known stents are typically designed to be longitudinally flexible to conform to the curvature of a vessel in which they are inserted. However, we have found that a stent modified from a linear shape to a generally helical shape is able to impose a generally helical shape when deployed in a fluid conduit, albeit with a reduced helical amplitude.
Preferably, the tubular hollow structure initially has a cylindrical shape, for example of circular cross-section, with a straight centre line. It is this shape which is then modified such that the longitudinally extending cavity follows a non-planar curve.
The hollow structure may comprise a plurality of circumferentially extending rings with adjacent rings being longitudinally joined at intervals around the circumference of the structure. Typical numbers of joints between rings are four or six. With this arrangement, when the shape of the hollow structure is modified according to the invention, the relative position of adjacent rings is adjusted whereby the hollow structure adopts the modified shape. Thus part of a ring may move closer to an adjacent ring, possibly overlapping therewith, and part of the ring may move further away from the adjacent ring. The maximum movement typically takes place in the regions where the rings are not longitudinally joined. In the case of an initially cylindrical hollow structure, the rings may be initially parallel to each other before their relative position is adjusted.
One known way of making stents is to laser cut them from a cylindrical tube. By using the method of the present invention, laser cutting can take place before the shape modification step, when the tube is still cylindrical, thereby avoiding the complexity of seeking to make a helical tube and then laser cut it.
The shape of the hollow structure may be modified by placing it along a flexible rod and twisting both the hollow structure and the rod so that both adopt a generally helical shape. Preferably, the shape of the hollow structure is modified by winding it round a tool, such as a mandrel. The tool is preferably substantially rigid. The tool may be a simple cylinder, but in order to provide control of the shape of the hollow structure (in particular the pitch and amplitude thereof) the tool may have a helical groove for receiving the hollow structure. Thus the shape of the hollow structure may for example be modified by placing it along a machined groove in a rod shaped tool. Advantageously, the hollow structure is constrained in contact with the tool, so that it does not return to the original cylindrical shape during heat treatment. This can be done using a wire along the inside of the hollow structure and/or a sleeve placed externally of the hollow structure and rod Thus, the hollow structure and tool may be together inserted in a suitable sleeve.
Another way of modifying the shape of the hollow structure would be to insert a tool inside the structure. Such a tool preferably has a helical shape, preferably with a plurality of helical turns. The tool may take the form of a helical rod. This method will generally not require the use of a sleeve or other constraint around the hollow structure and therefore has the advantage that the heating and cooling of the hollow structure can be carried out with greater uniformity and more rapidly. It is generally desirable to cool the hollow structure quickly, for example by quenching it in water, and this is facilitated by a method in which the rod or mandrel has a relatively small mass and the hollow structure is exposed directly to the cooling means. This method also provides superior constraint and improved control over the new helical set shape.
Certain preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:
Figure 1 shows a mandrel for use in the method of the invention;
Figure 2 shows a hollow structure inserted into a groove in the mandrel;
Figure 3 shows the hollow structure after it has been removed from the mandrel;
Figure 4 shows another form of mandrel; and
Figure 5 shows a hollow structure with the mandrel of Figure 4 inserted therein.
A tool in the form of a mandrel 2 is made from stainless steel and is formed with a helical groove 4 extending along its length. The groove 2 has a diameter suitable to receive a hollow structure 6, as seen in Figure 2.
The hollow structure is a conventional cylindrical stent made of shape memory alloy, which is deformed from its usual linear shape to a shape following the helical groove of the mandrel. The stent initially has a cylindrical shape, with a circular cross-section. As seen in Figure 3, it has a series of rings 7 which, when the stent is in its initial cylindrical form, are all arranged parallel to each other. Each ring 7 consists of a zigzag configuration of struts, so that adjacent struts form a crown 5 and each ring has a plurality of crowns 5. Joint portions 9 between the crowns of adjacent rings are provided at circumferential intervals around the rings. Typically, a ring may have eighteen crowns and there may be six joint portions between adjacent rings.
Figure 4 shows another form of mandrel 8, in the form of a stainless steel rod having a helical shape. The rod has been made by milling in a CNC milling machine . An alternative technique for making the mandrel is to heat a stainless steel rod and then thread it into a helical groove in a former having a shape such as that of the mandrel show in Figure 1.
The mandrel 8 is designed to be inserted inside the hollow structure 6 of a conventional shape memory alloy stent, so as to modify the longitudinal cavity of the hollow structure to conform to the shape of the helical rod. The outside diameter of the mandrel is slightly smaller than the inside diameter of the stent. For example, a 5.8 mm diameter mandrel may be inserted in a 6 mm diameter stent. The stent with the mandrel inside is seen in Figure 5. EXAMPLE 1
A nitinol stent was used, having an outside diameter of 8 mm. The stent was placed in the groove 4 of the mandrel 2 as shown in Figure 2. In order to prevent the stent from springing out of the groove it was restrained by a steel sleeve (8). It was placed in a hot furnace heated to 5000C in an inert (oxygen free) atmosphere (argon) for 15 minutes. The mandrel, hollow structure and sleeve were then immersed in water at a temperature of 2O0C so as to be rapidly cooled.
The sleeve was removed and the stent was separated from the mandrel.
When the stent so made is cooled to below 50C, for example by being placed in iced water, it is easily manipulated and so can be readily placed in a collapsed condition constrained by an appropriate delivery system. When the stent is deployed in a fluid conduit of the human or animal body, it expands to a helical shape, so as to define a flow lumen following a non-planar curve.
It is expected that the modification process applied to the stent will have no adverse physiological effects.
EXAMPLE 2
The mandrel of Figure 4 was inserted in a the same type of stent as described in Example 1. The stent and mandrel were placed in a hot furnace heated to 5000C in an inert (oxygen free) atmosphere (argon) for 15 minutes. They were then immersed in water at a temperature of 2O0C so as to be rapidly cooled. The stent and mandrel were separated and the stent had adopted a helical shape. By cooling this stent to below 50C it can be easily constrained in a delivery system. When it is deployed in a fluid conduit of a human or animal body it defines a flow lumen following a non-planar curve.
In both examples, after separation from the mandrel the stent had the helical shape shown in Figure 3. Adjacent rings on the inside of the helix are closer together or overlap, whilst those on the outside are further apart. The modification of the relative positions of the rings whereby the stent adopts the helical shape is achieved by the mandrel and the heating step. It is possible to avoid initial fabrication of a stent with a complex variation in the lengths and orientations of the struts and the joints between them to obtain the desired helical shape.

Claims

Claims
1. A method of making a stent which, when the stent is inserted in a fluid conduit of the human or animal body defines a flow lumen following a non- planar curve, the method comprising providing a tubular hollow structure having a longitudinally extending cavity and made of a shape memory material, modifying the shape of the hollow structure into a shape in which its longitudinally extending cavity follows a non-planar curve, heating the modified hollow structure to a temperature such that the modified shape is memorised by the shape memory material, and cooling the hollow structure.
2. A method as claimed in claim 1, comprising inserting a tool inside the hollow structure to modify its shape.
3. A method as claimed in claim 2, wherein the tool is helical.
4. A method as claimed in claim 3, wherein the tool has a plurality of helical turns.
5. A method as claimed in claim 1, wherein the shape of the hollow structure is modified by winding it round a tool.
6. A method as claimed in claim 5, where the tool has a helical groove for receiving the hollow structure.
7. A method as claimed in claim 5 or 6, comprising constraining the hollow structure in contact with the tool.
8. A method as claimed in claim 7, wherein a sleeve is used to constrain the hollow structure in contact with the tool.
9. A method as claimed in any preceding claim, wherein the hollow structure initially has a cylindrical shape.
10. A method as claimed in any preceding claim, wherein the hollow structure comprises a plurality of circumferentially extending rings with adjacent rings being longitudinally joined at intervals around the circumference of the structure, and wherein, when the shape of the hollow structure is modified, the relative position of adjacent rings is adjusted whereby the hollow structure adopts the modified shape.
PCT/GB2006/001598 2005-04-29 2006-05-02 Manufacturing method for a non- planar curved stent WO2006117545A1 (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
AU2006243061A AU2006243061A1 (en) 2005-04-29 2006-05-02 Manufacturing method for a non- planar curved stent
EP06726977A EP1874124A1 (en) 2005-04-29 2006-05-02 Manufacturing method for a non- planar curved stent
JP2008508309A JP2008538961A (en) 2005-04-29 2006-05-02 Method for manufacturing non-planar curved stent
BRPI0611022A BRPI0611022A2 (en) 2005-04-29 2006-05-02 method of producing a stent
CA002605812A CA2605812A1 (en) 2005-04-29 2006-05-02 Manufacturing method for a non- planar curved stent
IL186549A IL186549A0 (en) 2005-04-29 2007-10-10 Manufacturing method for a non-planar curved stent

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0508859A GB2425485A (en) 2005-04-29 2005-04-29 Shape memory stent producing non planar, swirling flow
GB0508859.6 2005-04-29

Publications (1)

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Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB0306176D0 (en) 2003-03-18 2003-04-23 Imp College Innovations Ltd Tubing
BRPI0408418A (en) 2003-03-18 2006-03-21 Veryan Medical Ltd stent
US8205317B2 (en) 2007-07-16 2012-06-26 Medtronic Vascular, Inc. Method of manufacturing a controlled porosity stent
US9597214B2 (en) 2008-10-10 2017-03-21 Kevin Heraty Medical device
WO2010041038A1 (en) * 2008-10-10 2010-04-15 Veryan Medical Limited A medical device
US9539120B2 (en) 2008-10-10 2017-01-10 Veryan Medical Ltd. Medical device suitable for location in a body lumen
WO2010041039A1 (en) 2008-10-10 2010-04-15 Veryan Medical Limited A medical device suitable for location in a body lumen
US10456276B2 (en) 2009-05-08 2019-10-29 Veryan Medical Limited Medical device suitable for location in a body lumen

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020179166A1 (en) * 2001-06-05 2002-12-05 Houston John Graeme Flow means
EP1279382A1 (en) * 2001-07-26 2003-01-29 Jomed Nv Curved stent
US20030135268A1 (en) * 2000-04-11 2003-07-17 Ashvin Desai Secure stent for maintaining a lumenal opening
WO2003059199A1 (en) * 2001-12-29 2003-07-24 Global Medical Sciences Ltd. Stent and method for the production thereof (variants)
US20040037986A1 (en) * 1998-12-28 2004-02-26 Tayside University Hospitals Nhs Trust, A British Corporation Blood-flow tubing
WO2004082533A1 (en) * 2003-03-18 2004-09-30 Veryan Medical Limited Helical stent

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2344053A (en) * 1998-11-30 2000-05-31 Imperial College Stents for blood vessels

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040037986A1 (en) * 1998-12-28 2004-02-26 Tayside University Hospitals Nhs Trust, A British Corporation Blood-flow tubing
US20030135268A1 (en) * 2000-04-11 2003-07-17 Ashvin Desai Secure stent for maintaining a lumenal opening
US20020179166A1 (en) * 2001-06-05 2002-12-05 Houston John Graeme Flow means
EP1279382A1 (en) * 2001-07-26 2003-01-29 Jomed Nv Curved stent
WO2003059199A1 (en) * 2001-12-29 2003-07-24 Global Medical Sciences Ltd. Stent and method for the production thereof (variants)
US20050096733A1 (en) * 2001-12-29 2005-05-05 Kovneristy July K. Stent and method for the production thereof (variants)
WO2004082533A1 (en) * 2003-03-18 2004-09-30 Veryan Medical Limited Helical stent

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GB2425485A (en) 2006-11-01
GB0508859D0 (en) 2005-06-08
JP2008538961A (en) 2008-11-13
CA2605812A1 (en) 2006-11-09
AU2006243061A1 (en) 2006-11-09
IL186549A0 (en) 2008-03-20
BRPI0611022A2 (en) 2016-11-16
EP1874124A1 (en) 2008-01-09

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