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 sheets 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 sheets 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 sheets 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 sheets 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 sheets or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
  • A61F2002/91533—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 sheets 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
• • 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 sheets 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 sheets 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

Definitions

• the present invention relates to the field of stents, more commonly called “stents", which are used in cardiovascular surgery, being implanted in a vascular duct, such as the coronary artery or peripheral arteries, and act as stakes for the vascular duct.
• the invention more particularly relates to a stent made from a stainless steel tube whose wall has been cut in particular by laser, and which is intended to be implanted in the vascular duct by means of an inflatable balloon.
• Atheromatous vascular diseases which correspond to narrowing of the arteries
• balloon dilation techniques called angioplasty.
• These narrowing of the arteries are caused by an infiltration of the wall and by the formation of an atheroma deposit inside the lumen of the vessel.
• the balloon is introduced into the artery, and is inflated as a rule with pressures ranging from 4 to 20 Bars, making it possible to crush the atheromatous material and to swell the arterial wall.
• stent In order to treat and re-stick these intimate tears and reduce restenosis by avoiding secondary recoil, it is currently widely used to implant in the vascular duct, at the area treated by angioplasty, a stent, more commonly called “stent". These stents or stents can be defined as metal supports acting as stakes once they are introduced into the artery at the level of the treated area. In the following description, for the sake of clarity, the stents will be designated by the term "stent".
• stents those made from coiled wire, those made from a mesh and those made from tubes cut in particular by laser.
• the invention is in the field of stents made from cut tubes.
• the stents produced from cut tubes are designed to be deployed by means of an inflatable balloon, during their implantation in the vascular duct.
• the stents must be crimped onto the balloon, in a so-called rest position, prior to the introduction of the balloon into the vascular duct.
• the stent Once the stent has been delivered to its implantation zone inside the vascular duct, it is deployed by expansion of the balloon, so as to be brought into contact with the wall of the vascular duct.
• the prior operation of crimping the stent onto the balloon must be carried out while ensuring that the stent or the balloon is not damaged, while ensuring that the stent is held perfectly in relation to the balloon. It is indeed essential that keeping the stent in position relative to the balloon is sufficient to avoid the risks of displacement of the stent relative to the balloon, during their passage inside the vascular duct to be treated, and in particular at inside the guiding catheter pre-implanted in the vascular duct. Any displacement of the stent may on the one hand obstruct the expansion of the balloon and on the other hand cause a defective opening and positioning of the stent.
• the stent is sold while already being crimped on a balloon, or the stent is sold separately without being crimped on a balloon.
• the crimping of the stent is carried out on a new balloon, having a perfectly cylindrical surface of revolution, and is carried out by crushing the stent on the balloon, symmetrically and evenly over the entire length of the stent and over its entire length. circumference.
• the crimping of the stent is carried out by the surgeon, as a rule on a balloon having already been previously used to dilate the area of the vascular duct to be treated, the crimping is carried out in this case on a balloon which has already deployed, and which therefore has a membrane with asymmetrical folds and which no longer forms a perfect cylinder.
• a stent must have certain characteristics, the most important of which are radial strength, biocompatibility, flexibility and malleability.
• a stent made from a cut tube has the advantage of having a greater radial force than the other two types of stents (coiled wire and wire mesh).
• biocompatibility the material used to make the stent must obviously be biocompatible and the least thrombogenic possible.
• material used with the exception of a few rare stents made of Platinum, Tantalum or Nitinol, the vast majority of stents are now made of stainless steel.
• Biocompatibility in particular with regard to the thrombogenic aspect, also depends on the surface condition of the stent, that is to say mainly on the roughness of the surface of the stent. The surface condition must be as smooth as possible.
• the flexibility of the stent must be sufficient to allow its routing in the vascular conduit, which can be strongly sinuous, and in addition sometimes calcified.
• An articulated stent is in the form of a succession of rings which on the one hand consist of cells having a determined geometric shape and capable of deploying, and which on the other hand are connected in the longitudinal direction of the stent by connections, so as to be articulated with each other.
• the malleability of the stent is linked to various factors, including mainly the hardness of the metal used, the thickness of the stent, and the cutting geometry.
• the malleability of the stent is today considered to be preponderant for the operation of crimping the stent.
• the more malleable the stent the easier it is to deform it by locally crushing it to fix it on the balloon.
• the malleable nature of the stent is even more preponderant in the case of a stent intended to be fixed on a used balloon, taking into account the irregularity of the surface of the balloon.
• the malleability of the stent allows it to match the relief of the irregular surface of the balloon, and thereby obtain a more reliable fixation of the stent on the balloon.
• the malleability of the stent also influences the flexible nature of the stent. The more malleable the stent, the greater its flexibility.
• an initial tube for example made of stainless steel, is selected at the start, the thickness of which is equal to the thickness of the final stent, and which also has the hardness required for the stent. final.
• a laser tube wall wall operation is carried out, so as to give it a determined geometric configuration.
• the manufacturing operation ends with a cleaning operation by electrolytic polishing, which is carried out so as to round the edges of the stent, to remove cutting burrs and carbonization residues due to laser cutting.
• the main object of the invention is a stent intended to be implanted in a vascular duct by being deployed under the effect of expansion of a balloon, which once implanted and deployed does not require any additional means for keeping it in place. deployed state and has a sufficient radial force to oppose the elastic retraction of the wall of the vascular duct, and which is obtained by cutting a stainless steel tube.
• the stent of the invention is characterized by a sufficiently high malleability to obtain an opening of the stent by expansion of the balloon under a pressure less than or equal to 3 bars and in particular under a pressure between 2 bars and 3 bars.
• tubular stents marketed to date are designed in such a way that they exhibit malleability resulting in an opening under an inflation pressure of the balloon which is at least 5 bars. To date, this malleability has been considered sufficient to meet the crimping and flexibility constraints. In addition, it was considered until now, by the manufacturers of tubular stents, that it was not conceivable to increase the malleability of the existing tubular stents, without the stents collapsing under the effect of elastic retraction of the wall of the vascular duct. It is the merit of the invention to have overcome this technical prejudice, by highlighting that by making a tubular stent cut out of stainless steel which has greater malleability, resulting in an aptitude of the stent to open. at a pressure less than or equal to 3 bars and in particular between 2 bars and 3 bars, a stent was obtained which could have sufficient radial force to reliably oppose the phenomenon of elastic retraction of a vascular conduit.
• the lower opening pressure of the stent of the invention also provides two important advantages: It makes it possible to obtain better symmetry in the opening of the stent. It contributes to reducing the aggression of the internal wall of the vascular duct by the stent during its opening, and thereby reduces the risk of restenosis by intestinal proliferation.
• the endoprosthesis of the invention is obtained by carrying out the following operations on a stainless steel tube, having an initial hardness and thickness (e,) greater than the hardness and thickness (e 2 ) sought for the final endoprosthesis: - cutting of the wall of the tube and cleaning by electrolytic polishing, - thermal treatment of hyperhardening, so as to reduce the hardness of the stainless steel, followed by a second electrolytic polishing treatment allowing decrease the initial thickness (e,) of the starting tube while improving its surface condition.
• the thickness e 2 of the tube 1 c obtained at the outlet of step 4 was between 0.06mm and 0.08mm, and was equal to average 0.067mm; for a stent intended to be implanted in a peripheral artery, the thickness e 2 of the tube 1c obtained at the outlet of step 4 was between 0.16mm and 0.18mm, and was worth on average 0.17mm.
• the roughness index R a of the stent 1ç obtained at the end of the process, under the effect of the double electropolishing of steps 3 and 4 dropped to a value between 0.1 ⁇ m and 0.4 ⁇ m.
• the pivot P 2 corresponds to the articulation of an arm 6a making an angle A, with respect to the articulation zone 6b; in the example illustrated, the angle A is greater than 90 ° and is more particularly about 120 °; the pivot P ⁇ corresponds to the articulation of an arm 6a making an angle B with the articulation zone 6b; this angle B is less than 90 ° and is worth more particularly around 30 ° ; the pivot P 3 corresponds to the junction of an articulation zone 6b with a connection 7.
• each arm 6a makes a substantially angle of 45 ° relative to the longitudinal axis 8 of the stent.
• Each arm 6a of angle A opens at an angle ⁇ , of approximately 15 °
• each arm 6a of angle B opens at an angle a 2 of approximately 75 °.
• each arm 6a opening at substantially the same angle, i.e. about 45 °.
• connections 7 transversely to the longitudinal axis 8 of the stent makes it possible to produce connections 7 whose length is greater, which allows better compensation for the reduction in the length of the stent when it is opened. More particularly, in the example of FIG. 4, the connections 7 consist of a wavy segment with four inflection points 7a for their elongation. This particular structure makes it possible to have a greater length reserve compared to the connections 7 of FIGS. 2 and 3.

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• Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Optics & Photonics (AREA)
• Cardiology (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Transplantation (AREA)
• Physics & Mathematics (AREA)
• Vascular Medicine (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Media Introduction/Drainage Providing Device (AREA)

Applications Claiming Priority (3)

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• 1997
  • 1997-12-09 FR FR9715816A patent/FR2771921B1/fr not_active Expired - Fee Related
• 1998
  • 1998-12-07 WO PCT/FR1998/002645 patent/WO1999029264A1/fr not_active Ceased
  • 1998-12-07 EP EP98958968A patent/EP0961599A1/de not_active Withdrawn

Non-Patent Citations (1)

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