Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/14—Macromolecular materials
• • 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
• • 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
  • A61F2210/0004—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof bioabsorbable

Definitions

• the present invention relates to a new type of blood vessel prosthesis for permanent or long-term implantation, which has clearly improved properties compared to previously used substitutes.
• a variety of substitutes for pathologically changed, functionally important arteries and veins have been utilized in surgical treatment.
• autologous material such as superficial veins from the lower extremities
• non-autologous biological material such as chemically or physically treated blood vessels from other persons or from animals
• synthetic materials such Dacron and Teflon ® tubes having varying structures depending on method of preparation
• the intimal layer consists of a cell layer, whose functions are on one hand to prevent the formation of intravascular thrombi (anti-thrombogenic effect), and on the other hand to provide for exchange of metabolic products between the blood and smooth muscle ceils in the vascular wall.
• a relatively thick and uniform layer of thrombotic material can be formed, building a scaffold for the proliferation of a endothelium coated muscle layer.
• the resorbable material is arranged so that more or less continuous interspaces are formed within the resorbable material and/or between the resorbable and the at least partially non-resorbable materials. This can, for example, be achieved by spacing, preferably large, parts of the resorbable material from the non-resorbable material.
• the resorbable layer or covering can be designed and applied in different ways.
• the resorbable material may, for example, be an inner tubular member, which is inserted into and fixed to the outer tubular prosthesis element of non-resorbable material.
• the inner tube may be formed of a coarse-to fine-meshed net, or may be a tube with perforated walls or walls having pores, etc.
• the resorbable structure may e.g. further consist of a fine wire structure protruding from or fixed to the outer tubular member or be another correspondingly porous structure of a resorbable material, e.g. a spongy layer.
• the attachment of the resorbable covering to the non-resorbable member may, of course, also take place before the prosthesis material is formed into a tube. It is also possible to cover the non-resorbable surface with the resorbable material by a method providing the necessary interspaces or growth zones as well as the necessary blood-cell pervious structure of the resorbable material. More detailed examples of the arrangement of the resorbable structure will be described below.
• resorbable material To increase the thickness of the fibrin layer which in the initial stage after the implantation is to be retained by the resorbable material, two or possibly more, at least partially, mutually separated layers of resorbable material may be applied or, alternatively, a relatively thick layer with sufficient porosity or perforation may be used.
• the resorbable net, tube etc. can be fixed to the non-resorbable prosthesis sleeve in different ways, e.g. with resorbable sutures or glue.
• At least the inside of the outer non-resorbable member ought to be micro-porous, porous or provided with holes in order to promote the attachment of the reformed tissues.
• Tubular prosthesis members of everything from a coarse-meshed net to a tube with fine pores may be used.
• a suitable and well-functioning vascular prosthesis according to the invention can e.g. consist ol a per se conventional vascular prosthesis, on whose inside one or more nets of a resorbable material have been applied.
• interspaces between non-resorbable and resorbable material in the vascular prosthesis can each have a greater or lesser extent, but the total area of these interspaces should preferably be so large that it approaches the size of the inner surface of the outer non-resorbable material layer, i.e. those portions or points where the resorbable material for fixing to the non-resorbable material contacts the latter should be as small as possible.
• the distance between the material surfaces in these interspaces or growth zones should be at least about 10 ⁇ to permit penetration of the blood cells, but it should suitably not exceed about 5 to 10 mm even for large prostheses. Preferably said distance is about 0,5 to 3 mm, depending, of course, also on the size of the blood vessel to be replaced.
• the resorbable material should be non-toxic without adverse tissue reaction, be resorbed at such a rate that a satisfactory reformation of tissue is permitted and not give rise to a fibrous scar tissue.
• PGA polyglycolic acid
• copolymers of glycolic acid and lactic acid and various lactide polymers may be mentioned.
• Polyglycolic acid can essentially be considered as a product of polymerization of glycolic acid, that is hydroxyacetic acid, which in simplified form is shown by the equation:
• n is such that the molecular weight is in the range from about 10.000 to about 500.000.
• polyhydroxy acetic esters are described in e.g. U.S. Patent No. 3.463.158, which is incorporated by reference herein.
• Copolymers of glycolic acid and lactic acid are described e.g. in U.S. Patent No. 3.982.543, which is incorporated by reference herein, the copolymer containing 15-85 mole percent glycolic acid and the remainder lactic acid and possibly small amounts of additional momomers.
• Homopolymers and copolymers of lactic acid are described e.g. in U.S. Patent No. 3.636.956, which is incorporated by reference herein.
• These polylactide compositions contain up to about 15 percent by weight of repeating units of the formula:
• R is lower alkylene, preferably methylene or ethylene, m is 0 or 1
• R' is hydrogen or lower alkyl
• R" is hydrogen or alkyl of up to about 22 carbon atoms when m is 0, and hydrogen or lower alkyl when m is 1, and can be the same as R' or different.
• Preferred are units derived from ⁇ -hydroxycarboxylic acids and particularly comonomer units derived from giycolide or DL-lactide.
• Suitable comonomers are glycolide, ⁇ -propiolactone, tetramethylglycolide, ⁇ -butyrolactone, ⁇ -butyrolactone, pivalolactone, and intermolecular cyclic esters of ⁇ -hydroxybutyric acid, ⁇ -hydroxiisobutyric acid, ⁇ -hydroxyvaleric acid, ⁇ -hydroxyisovaleric acid, ⁇ -hydroxycapronic acid, ⁇ -hydroxy- ⁇ -ethylbutyric acid, ⁇ -hydroxyisocapronic acid, ⁇ -hydroxy-3-methylvaleric acid, ⁇ -hydroxyheptanoic acid, ⁇ - hydroxyoctanoic acid, ⁇ -hydroxydecanoic acid, ⁇ -hydroxymyristic acid, ⁇ -hydroxystearic acid and ⁇ -hydroxy lignoceric acid.
• the polylactide composition may contain about 35 mole percent of repeating units derived therefrom.
• suture wire such as suture wire, suture net, etc.
• suture materials are also described in the literature.
• Commercially available suture materials are e.g. Polyglactin 910 (VICRYI ® , Ethicon, Sommerville, New Jersey, USA), which is a copolymer containing 90% glycolic acid and 10% lactic acid and DEXON® (Davis & Geek, Pearl River, New York, USA) which consists of polyglycolic acid.
• VIPYI ® Polyglactin 910
• Ethicon Ethicon, Sommerville, New Jersey, USA
• DEXON® Diavis & Geek, Pearl River, New York, USA
• other materials can be used provided that they have the desired properties according to the above.
• non-resorbable prosthesis part any conventional body-acceptable, non-resorbable material usually used for similar purposes may be used.
• non-resorbable material usually used for similar purposes.
• examples of such materials are polyethylene terephthalates, such as Dacron and Terylene, (e.g. micro-porous expanded) polytetrafluoroethylene (TEFLON ® , linear polyethene, isotactic polypropene, nylon, etc.
• TEFLON ® micro-porous expanded polytetrafluoroethylene
• This non-resorbable prosthesis part may as mentioned above be manufactured in various fabric forms (knitted, woven, possibly provided with outer and inner velour surfaces) or as a more or less porous tube.
• the nonresorbable material may be combined with a resorbable material, e.g.
• wires or fibres of a non-resorbable material coated with a resorbable material be made of wires or fibres of a non-resorbable material coated with a resorbable material, be woven with the interspersion of wires of resorbable material, have the inside coated by a resorbable material layer etc.
• other materials having such properties that permit implantation may be used.
• the prosthesis covering of resorbable material ought to be such that the absorption thereof in the organism takes at least 20 days, and preferably 40- 150 days.
• Fig. 1 is a perspective view of an embodiment of a vascular prosthesis according to the invention.
• Figs. 2 to 7 are schematic fragmentary sectional views of alternative embodiments of the invention.
• the vascular prosthesis shown in Figure 1 comprises an outer tube 1 of a porous essentially non-resorbable material, and an inner covering or tube 2 of a resorbable material.
• the inner tube 2 is in the figure formed of a net, which is attached to the outer tube 1 by means of a number of (not shown) sutures of a resorbable material.
• the covering 2 contacts the outer tube 1 only at the fixing points, and the net portions therebetween remain spaced from the inner surface la of the tube 1 - as is schematically shown in Fig. 2 - and form the above mentioned growth zones, to which the blood cells after implantation can pass via the meshes of the net 2.
• the mesh size of the net 2 is not critical as such but mesh sizes up to about 5 ⁇ 5 mm can conveniently be used.
• a tubular element of a more or less (e.g. micro-porous) porous material e.g., both the outer tube 1 and the covering 2 may consist of nets, it also being possible to use woven or knitted materials.
• the inner tube 2 can be a porous tube structure, while the outer tube 1 is a tubular net.
• the fixing of the inner tube or covering 2 and the outer tube 1 can also be performed in another way than is shown above, e.g. by gluing with a suitable material.
• the distance between the tube surface la and the covering 2 is suitably chosen such that it is about 0,5-3 mm.
• the thickness of. the muscle cell/endothelium layer which is to be formed can be varied, e.g. by using several nets 2 separated by a suitable interspace as above.
• the inner tube 2 is a porous tube
• the thickness of the latter can be varied, it being understood, however, that the porosity according to the above should be sufficient for good penetration of the blood cells.
• the thicknesses of the outer tube 1 and the covering layer 2 are suitably chosen such that the outer tube 1 corresponds to the outer layer of connective tissue (adventitia) and the layer 2 corresponds to the muscle cell and endothelium layer of the blood vessel or blood vessel part to be replaced by the vascular prosthesis. In the same way as in the case of nets it is possible to use several mutually separated layers of a porous material.
• Figs. 2 to 7 schematically show some variations of the design and application of the inner wall construction 2 to the outer tube 1.
• the resorbable material structure 2 is supposed to be a net (as in Fig. 1) or another porous flexible structure which remains spaced to the outer tube 1 between fixing points 3, so that interspaces 4 are formed between the respective portions of the inner wall 2 and the outer tube 1.
• the inner wall 2 may, of course, also be a more rigid resorbable structure designed and fixed in the above manner.
• the fixing means may e.g. be resorbable sutures or glue.
• a tubular resorbable structure 2 having a smaller diameter than the inner diameter of the outer tube 1 is fixed to the latter through projections 5 of non-resorbable material extending from the outer tube 1, so that an interspace 4 is formed between the tubes.
• Fig. 4 shows a similar arrangement, but here the projections or connecting elements 5 protrude from the resorbable structure 2.
• the connecting parts 5 are fewer and thus more spaced apart.
• the connecting elements or parts 5 may be arranged and designed in any suitable way. Thus, they may have a small wire-like dimension, and be uniformly or non-uniformly distributed along the material surfaces 1 and 2 in any suitable manner. They may, however, also have larger dimensions and can, for example, form partition walls or structures extending e.g. radially or circumferentially.
• an inner tube or covering 2 is fixed to the outer tube 1 through a more porous or loose layer 6, e.g. a wire structure, of a resorbable or partially resorbable material.
• a more porous or loose layer 6 e.g. a wire structure, of a resorbable or partially resorbable material.
• the resorbable covering 2 is applied to the outer tube 1 without any proper spacing as above, and consists of a structure of a more porous nature, such as a fine wire-structure of loop or skein type, or of a highly porous or spongy material.
• the layer 2 may further be e.g. a wire-structure in the form of a "nail or pin carpet” or the like having pins or wire protruding from a layer of a resorbable material applied to the non-resorbable material.
• Figs. 1 to 7 are, as mentioned hereinbefore, only examples of various ways of providing the resorbable material, and further variations, such as various combinations of the above described examples are naturally possible within the invention.
• an endothelium layer as well as an underlying cell layer of smooth muscle tissue is developed on the inside of the synthetic non-resorbable vascular prosthesis material.
• the reformed layer on the inside of the synthetic material is developed in a short time through regeneration of normal constituents of the vascular wall from the edges of the animal's own vessels, while at the same time the resorbable material disappears.
• the reformed endothelium presents properties characteristic of a normal endothelium.
• the grafted vessel segment consists of an outer part of synthetic material, which gives a sufficient strength to the vessel, and of an inner part of body tissue having the structure of a normal vessel.
• the vascular prosthesis according to the invention essentially functions as a normal blood vessel.
• a vascular prosthesis was produced by applying a net of Polyglactin 910 (Vicryl ® , Ethicon, Sommerville, New Jersey, USA) on the inside of tube of expanded polytetrafluoroethyiene (Impra Inc., Phoenix, Arizona, USA) having a length of 10 cm and an inner diameter of 13 mm.
• the net had a wire size of 140 + 20 ⁇ and a pore thickness of 400 ⁇ 400 ⁇ and was attached to the PTFE tube with polyglactin sutures.
• the tube thus constructed was then sewn into pig thorax aorta as a replacement for an excised section.
• a vascular prosthesis was produced as above, using as the outer tube a double velour knitted Dacron ® tube (Meadox Medicals, Oakland, New Jersey, USA) of the same length as above and with an inner diameter of 10 mm and as the inner tube a polyglactin net of the same type as in Example 1. The net was attached to the outer tube with polyglactin sutures. With this device the same experiment as in Example 1 was then performed. The result after six weeks implantation totally corresponded to the result of Example 1.
• Example 1 A similar tube construction as in Example I was produced, a tube of Dacron fabric with a wire thickness of about 20 ⁇ and a mesh size of about 600 ⁇ 600 ⁇ being used as the outer tube, and the inner tube consisting of a polyglactin net of the same type as in Example 1. With this device the same experiment on pig as in Example 1 was then performed. The result after six weeks' implantation totally corresponded to the results in Example 1.
• the invention is, of course, not restricted to the above specially described and shown embodiment, but many modifications and variations are possible within the scope of the subsequent claims. This applies especially to the resorbable and non-resorbable materials, the design of covering and outer tube, the dimensioning of the various components etc.

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• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Transplantation (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Gastroenterology & Hepatology (AREA)
• Pulmonology (AREA)
• Heart & Thoracic Surgery (AREA)
• Biomedical Technology (AREA)
• Vascular Medicine (AREA)
• Cardiology (AREA)
• Chemical & Material Sciences (AREA)
• Dermatology (AREA)
• Medicinal Chemistry (AREA)
• Epidemiology (AREA)
• Prostheses (AREA)
• Materials For Medical Uses (AREA)

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Cited By (22)

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• 1979
  • 1979-06-06 SE SE7904938A patent/SE424401B/sv unknown
• 1980
  • 1980-06-04 GB GB8103147A patent/GB2063685B/en not_active Expired
  • 1980-06-04 WO PCT/SE1980/000161 patent/WO1980002641A1/en active Application Filing
  • 1980-06-04 AU AU59897/80A patent/AU539875B2/en not_active Ceased
  • 1980-06-04 NL NL8020201A patent/NL8020201A/nl not_active Application Discontinuation
  • 1980-06-04 CH CH82281A patent/CH645532A5/fr not_active IP Right Cessation
  • 1980-06-04 JP JP55501198A patent/JPS6318508B2/ja not_active Expired
  • 1980-06-04 DE DE803047573T patent/DE3047573T1/de active Granted
  • 1980-06-05 BE BE0/200895A patent/BE883646A/fr not_active IP Right Cessation
  • 1980-06-05 FR FR8012488A patent/FR2458274A1/fr active Granted
  • 1980-06-06 CA CA000353650A patent/CA1166802A/en not_active Expired

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