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
  • A61F2/02—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
• • D—TEXTILES; PAPER
  • D03—WEAVING
  • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
  • D03D15/00—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used
  • D03D15/40—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used characterised by the structure of the yarns or threads
  • D03D15/44—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used characterised by the structure of the yarns or threads with specific cross-section or surface shape
• • D—TEXTILES; PAPER
  • D03—WEAVING
  • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
  • D03D15/00—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used
  • D03D15/20—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used characterised by the material of the fibres or filaments constituting the yarns or threads
  • D03D15/283—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used characterised by the material of the fibres or filaments constituting the yarns or threads synthetic polymer-based, e.g. polyamide or polyester fibres
• • D—TEXTILES; PAPER
  • D03—WEAVING
  • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
  • D03D15/00—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used
  • D03D15/40—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used characterised by the structure of the yarns or threads
  • D03D15/49—Woven fabrics characterised by the material, structure or properties of the fibres, filaments, yarns, threads or other warp or weft elements used characterised by the structure of the yarns or threads textured; curled; crimped
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2331/00—Fibres made from polymers obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. polycondensation products
  • D10B2331/04—Fibres made from polymers obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. polycondensation products polyesters, e.g. polyethylene terephthalate [PET]
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2401/00—Physical properties
  • D10B2401/10—Physical properties porous
• • D—TEXTILES; PAPER
  • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
  • D10B2509/00—Medical; Hygiene
  • D10B2509/06—Vascular grafts; stents

Definitions

• the invention relates to a woven fabric for an endovascular application. More particularly, the invention relates to an ultra-thin low porosity woven fabric for use in endovascular grafts.
• An abdominal aortic aneurysm is a sac caused by an abnormal dilatation of the wall of the aorta as it passes through the abdomen.
• the aorta is the main artery of the body, supplying blood to all organs and parts of the body except the lungs. It arises from the left ventricle of the heart, passes upward, bends over and passes down through the thorax and through the abdomen, and finally divides into the iliac arteries which supply blood to the pelvis and lower extremities .
• the AAA ordinarily occurs in the portion of the aorta below the kidneys. When left untreated, the aneurysm will eventually cause the sac to rupture with ensuing fatal hemorrhaging in a very short time.
• the repair of abdominal aortic aneurysms has typically required major abdominal surgery in which the diseased and aneurysmal segment of the aorta is bridged with a prosthetic device, such as a synthetic graft .
• stent/graft deployment catheter eliminates the problem of suturing the graft to the aorta associated with surgical repair techniques.
• use of tne catheter still requires a cu -down surgery to locate and expose the blood vessel, and thus, the patient recovery time is still quite long. Therefore, the need exists for a stent/graft deployment catheter and a stent/graft which are small enough to be inserted percutaneously into the blood vessel of the patient.
• the term stent/graft refers to a stent and graft assembly, a stent alone, or a graft alone. A percutaneous procedure would avoid the surgery necessary to locate the blood vessel and thereby decrease patient recovery time significantly.
• the presence of such a catheter and stent/graft on the market may finally allow for the full transition from the currently used surgical cut-down method of stent/graft insertion to the much preferred percutaneous insertion method.
• a catheter has not appeared on the market because of the difficulty inherent in designing a catheter and stent/graft small enough to be inserted percutaneously.
• the present invention discloses a graft material which is greater than 50% thinner than prior art graft materials, and thus, given the existence of an appropriately sized stent/graft deployment catheter, capable of percutaneous insertion.
• tubular grafts have been formed from knitted or woven continuous filament polyester fiber (Dacron Registered TM) and from expanded polytetrafluoroethylene (PTFE) .
• a vascular graft is influenced by a variety of characteristics such as strength, permeability, tissue ingrowth, and ease of handling.
• a graft should be sufficiently strong: (a) to prevent the sidewalls from bursting when blood is flowing through the device even at high blood pressures; and (b) to maintain the patency of the vessel lumen.
• a graft sidewall must be sufficiently impervious to blood to prevent hemorrhaging as blood flows through the graft .
• Expanded grafts are inherently leak resistant .
• Woven and knitted grafts may require sealing of the openings between adjacent interlacings to prevent blood leakage. Sealing of said openings may be accomplished through a pre-clotting procedure. Pre-clotting involves immersing a woven or knitted graft in the patient's blood and then allowing the graft to dry until the interstices in the graft fabric become filled with the clotted blood.
• Another common technique for sealing the above mentioned openings is to coat the graft with an impervious material such as albumin, collagen or gelatin.
• Tissue ingrowth through the interstices of the graft is believed to nourish and organize a thin neointima lining on the inner surface of a graft, preventing clotting of blood within the lumen of the graft which could occlude the graft.
• a velour surface may be provided on the outer surface of a woven or a knitted graft to encourage tissue infiltration.
• the pore size of a graft also influences tissue ingrowth. Although larger openings facilitate tissue penetration, pre-clotting or coating of the graft may be adversely affected as pore size increases. Ease of handling is another important feature of an vascular graft.
• a flexible and conformable graft facilitates placement of the prosthesis by the surgeon.
• Woven and knitted grafts generally have been formed from continuous filament polyester yarns which typically are textured prior to fabrication to impart bulk and stretch to the vascular graft fabric.
• a technique known as false twist texturizing has been employed which involves the steps of twisting, heat setting and then untwisting the continuous multifilament yarns, providing substantially parallel, wavy filaments.
• Expanded PTFE grafts provide strong structures which are non-porous and impervious to blood leakage. The absence of pores, however, precludes tissue ingrowth. Expanded PTFE grafts also may be stiff and nonconforming which detrimentally affects handleability .
• Knitted grafts have attractive tissue ingrowth and handleability features.
• the porous structure of knitted grafts requires that the graft be pre-clotted or coated to prevent hemorrhaging .
• Woven grafts are less porous than knitted grafts and may not require pre-clotting or coating.
• the tightly compacted weave structure may provide a stiff prosthetic which is not as conformable or as easily handled as is a knitted graft.
• the present invention accomplishes a dramatic reduction in graft woven fabric thickness through the use of non-slashed untwisted yarn.
• most textiles are generally woven from twisted yarns.
• Grafts are generally manufactured with at least the warp yarn twisted. Twisting of the yarns acts to bond all the filaments, making up the yarn, together. Bonding of the filaments is important because it assures that if a portion of one filament breaks along its length it does not simply fall out or hang loose from the woven fabric. It is important for most fabrics that surface abrasion, whether during the weaving process itself or during actual use of the fabric, does not cause the woven fabric to easily fall apart.
• micro-denier Use of these thin fibers results in an overall thinner graft.
• Use of microfilament yarns may achieve graft thickness of less than 0.1 mm, however the water permeability of such grafts is significantly greater than 500 ml/min/cm 2 , and the grafts may chemically degrade over a long period of time.
• All commercially available textile vascular grafts are made of polyester yarns having a minimum filament linear density of approximately 1.5 denier, such as 40/27 Dacron (40/27 is shorthand for a 40 denier yarn having 27 filaments of 1.48 denier each) .
• micro- filament artificial vascular grafts may be suitable for the particular purpose employed, or for general use, they would not be as suitable for the purposes of the present invention as disclosed hereafter.
• the invention is an ultra-thin endovascular graft having a low rate of water permeation.
• the woven graft fabric comprises untwisted non-slashed multifilament yarns capable of flattening upon weaving.
• FIG 1 is a plan view of a prior art graft fabric woven with twisted yarns.
• FIG 1A is a cross section view of the fabric illustrated in FIG 1 taken along lines 1A-1A.
• FIG 2 is a plan view of an improved graft fabric woven with non-twisted yarns.
• FIG 2A is a cross sectional view of the fabric illustrated in FIG 2 taken along lines 2A-2A.
• FIG 1 illustrates a plan view of a prior art woven graft fabric, designated generally 10, comprising a plurality of twisted warp yarns 12 and twisted fill yarns 14 woven together in a conventional 1/1 plain weave.
• FIG 1A illustrates a cross section of the woven fabric 10 taken along lines 1A-1A. It can be seen in FIG 1A that the thickness of the woven fabric 10, labeled Thickness, equals approximately the sum of both the twisted warp yarn 12 and the twisted fill yarn 14 thicknesses.
• the presence of twist on the yarns makes them generally rigid and incompressible. Therefore, upon weaving, the twisted incompressible yarns maintain their round-ellipse cross sectional shape rather than flattening out.
• the presence of twist on yarns 12 and 14, and the resultant round-ellipse cross sectional shape of yarns 12 and 14, aside from preventing flattening, also results in the introduction of unnecessary large interstices 16 between the yarns 12 and 14, as shown in Figure 1.
• Equation (1) indicates that the effect of both fabric porosity ( ⁇ ) and filament diameter (d) on water permeability ( WP) is significantly greater than that of fabric thickness (t). Accordingly, the large yarn interstices 16, which are present due to the twist on the yarns 12 and 14, significantly raises the water permeability of the graft fabric 10 by increasing the level of fabric porosity.
• grafts are usually made with a thickness greater than 0.1 mm.
• surgical grafts thicker than 0.1 mm are not problematic and in most cases are necessary for required strength.
• grafts thicker than 0.1 mm are considered too bulky for endovascular applications.
• Use of microfilament yarns in a twisted format, such as 30/30 (30 denier with 30 filaments of 1.0 denier each) polyester yarns, may achieve graft thickness of less than 0.1 mm.
• the water permeability of such a graft is significantly greater than 500 ml/min/cm 2 , and the graft may chemically degrade over a long period of time.
• the graft may chemically degrade over a long period of time.
• All commercially available textile vascular grafts are made of polyester yarns having a minimum filament linear density of approximately 1.5 denier, such as 40/27 Dacron.
• FIG 2 illustrates a plan view of an improved ultra-thin graft fabric 10.
• the graft fabric 10 comprises a plurality of non-twisted warp yarns 18 and a plurality of non-twisted fill yarns 20 woven together in a conventional 1/1 plain weave.
• Both the warp yarns 18 and the fill yarns 20 used to weave the graft fabric 10 are multifilament polymeric yarns, textured or flat, non-twisted or only slightly twisted, with a surface twist angle of less than approximately 5 degrees, but preferably non-twisted.
• the linear densities for the warp yarns 18 and fill yarns 20 may be different or identical, depending on the weavability and design of woven construction.
• the number of filaments within the yarns 18 and 20 should be sufficient, preferably more than 20 filaments per yarn, for the yarns 18 and 20 to change their cross-sectional shapes, i.e. flatten, during and after weaving.
• the yarns 18 and 20 are capable of changing their shape during and after weaving because they are non-twisted and non-slashed, i.e. have not gone through the slashing process.
• the filaments of non- slashed yarn are not bound together by an adhesive, and therefore, can change shape during and after weaving.
• the weave pattern can be plain, twill, satin or sateen, but preferably 1/1 plain weave because it has the highest degree of interlacing.
• the surface of a graft, made from the graft fabric 10, can be smooth or a single or double velour, but preferably smooth because the presently disclosed graft fabric 10 is intended for an endovascular application.
• Constructing and arranging the graft fabric 10 into a tubular configuration, having a lumen for conveying blood therethrough, is well known in the art.
• sufficient yarn tensions should be applied during the weaving process, followed by compacting and heat-setting the graft fabric 10 on appropriate mandrels at a raised temperature above the glass transition temperature and below the melting temperature. Note that use of non-twisted yarn in only one of the directions in the graft fabric 10, warp or fill, is also anticipated.
• Warp/Filling Yarns 40 denier/27 fila. 40 denier/27 fila.
• Warp Density 316 ends/inch 128 ends/inch Filling Density 88 picks/inch 128 picks/inch Area Density 404 yarns/square inch 256 yarns/square inch Weave Pattern 1/1 plain 1/1 plain Graft Diameter 24 mm 24 mm Graft Thickness 0.145 mm 0.070 mm (measured)

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Health & Medical Sciences (AREA)
• Gastroenterology & Hepatology (AREA)
• Pulmonology (AREA)
• Cardiology (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Transplantation (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Vascular Medicine (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Prostheses (AREA)

Applications Claiming Priority (5)

Publications (1)

Family

ID=26821256

Family Applications (1)

Country Status (3)

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Family Cites Families (6)

• 2000
  • 2000-01-31 WO PCT/US2000/002404 patent/WO2000051524A1/en not_active Application Discontinuation
  • 2000-01-31 AU AU36940/00A patent/AU3694000A/en not_active Abandoned
  • 2000-01-31 EP EP00915712A patent/EP1079766A1/de not_active Withdrawn

Non-Patent Citations (1)

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