Abstract: Methods for grafting unmodified PEO or any other water-soluble polymers to the surfaces of metals and glasses to form biocompatible surfaces having low protein affinity is provided. One technique includes the steps of: (a) providing a support member having a plurality of hydroxyl or oxide groups attached to a surface of said support member; (b) exposing said surface to a silane coupling agent to cause the silane coupling agent to form a silane layer that is covalently bound to the surface wherein the silane layer comprises a plurality of vinyl groups; and (c) exposing the silane layer to a hydrophilic polymer and causing the silane layer to react with the hydrophilic polymer to covalently bond to the silane layer. Exposure of the silane layer to .gamma.-radiation to induce grafting with low radiation to induce grafting of the hydrophilic polymer to the silane layer.

Abstract: A radially expandable support body is enveloped within a cocoon. In a preferred construction, the support is a stent, and a tube of polymeric material, e.g. polytetrafluoroethylene (PTFE), passes through the interior of the stent body and is turned back upon itself over the stent to form a cuff. The assembly is then heated and the outer layer contacts and coalesces with the inner layer, closely surrounding the stent body within a folded envelope having a continuous and seamless end. In one embodiment, an end portion of the tube is expanded before folding back over the stent. The end portion, which becomes an exterior surface of the finished product, thus acquires a greater degree of porosity. Each end of the central tube may be so expanded, and folded back to seal all surfaces and both ends. The stent body itself may be a ring, or a short series of spaced-apart rings, or a wire or web, or a sheet possessing a number of apertures extending entirely through the sheet.

Abstract: An uncured or partially cured, collagen-based material is delivered to a selected site in a blood vessel and is crosslinked in the blood vessel by laser energy or other suitable energy to form an endovascular stent. The collagen-based material can be delivered to the blood vessel as a coating on an inflatable balloon mounted on the distal end of a catheter. The collagen-based material can also be delivered to the blood vessel in liquid form. The liquid collagen-based material is forced through a porous balloon to form either an imperforate tubular configuration or a tubular mesh configuration. The collagen-based material is preferably crosslinked by laser radiation carried through an optical fiber to a diffusing tip located within the balloon.

Abstract: A prosthesis for insertion into a lumen to limit restenosis of the lumen. The prosthesis carries restenosis-limiting drugs which elute after the device is positioned in the lumen.

Abstract: A perforated unitary multi-laminar tissue graft construct and method for preparing such construct is described. The method comprises overlapping strips of submucosa tissue with other strips of submucosal tissue, compressing at least the overlapped portions of said strips between two surfaces under conditions that allow or promote dehydration of the compressed submucosa sheets, and perforating the resulting unitary tissue graft construct. The perforated tissue graft compositions have enhanced mechanical and remodeling properties relative to non-perforated submucosal tissue grafts.

Abstract: A graft system is provided that includes either a support ring or a support sleeve that is used in providing transitional support to either an end or a side of a graft or a host vessel. The support ring is provided with a generally cylindrical wall and defining a passageway that is adapted for receiving an end of a vein graft or an end of a host vessel. The support ring has a first end and a second end, with the thickness of the wall being greater at the first end than at the second end. The support sleeve is provided with a first side edge, a second side edge, and an opening. The support sleeve surrounds a side opening of a graft or host vessel so that the opening of the support sleeve is aligned with the side opening of the graft or host vessel. The thickness of the support sleeve is greater at the opening than at the first and second side edges.

Abstract: An externally supported, tape-reinforced tubular prosthetic graft and method of manufacturing therefore. The graft comprises a tubular base graft formed of expanded, sintered fluoropolymer material, a strip of reinforcement tape helically wrapped about the outer surface of the tubular base graft and attached thereto, and, an external support member helically wrapped around the outer surface of the reinforcement tape and attached thereto. The helical pitch of the reinforcement tape is different from the helical pitch of the external support member. Preferably, the helical pitch of the reinforcement tape is in a direction which is opposite the direction of the external support member.

Abstract: A device, whose purpose is such internal shielding of a vascular anastomosis that undesirable perivascular vibration is avoided, is created from a stiff or possibly moderately elastic, non-resorbable, biologically inert, non-moistenable and sterilizable material. The shield has the form of an incomplete tube (4), whose length is at least five times larger than the diameter of the targeted vessel or substitute. This incomplete tube (4) in the third and fourth fifths of its length (counting counter to the course of blood flow) is provided with an orifice (5) having a width of at least one quarter of the circumference of the tube. From the apical end of the orifice (5) and/or from the rear end of the said orifice (5) projects a gradually tapered tongue-shaped structure (6, 10) which is moderately bow-curved externally. The margin (8) of the orifice (5) and all margins of the device are blunt, and the whole internal surface of the device is highly polished.

Abstract: Stents are coated with a polymer such that the polymeric coating binds the crossover points of the wires, or, in the case of a zig-zag stent, binds adjacent zig-zags of wires without occluding the interstices of the stent lattice. Suitable polymers include polyurethane, polycarbonate urethane, polyurethane urea, silicone rubber, polyisobutylene copolymer (with styrene, etc.), polyolefin, polyester, glycolated polyester, polyamide, amorphous polyamide, combinations of the above and the like. Biodegradable polymers such as polyisobuterate, polyvalerate, polylactic acid, polyglycolic acid and combinations of these are also suitable. The polymer can be reacted in place without a solvent, such as two component polyurethanes, or silicone rubbers, or the reacted polymer can be dissolved in an appropriate solvent, for example, dimethylacetamide for the polyurethanes, toluene for the polyolefins, or heptane for the silicone rubbers.

Abstract: Medical devices, most particularly prosthesis, are defined having at least one porous tissue-mating surface. The tissue-mating surface of the device includes therein a pharmacologically active substance within a biodegradable carrier, such as a polymer or a biodegradable ceramic, such as calcium phosphate. A biodegradable composition of the drug and carrier is impregnated within the pores of the tissue-mating surfaces of the device. The device thereby provides for the long-term release of pharmacologically active substances upon implant. The prosthesis of the present invention provides for enhanced rigid fixation, as pores at the surface of said device provide for bony ingrowth as biodegradable material impregnated therein degrades. Pharmacologically active substances within the biodegradable composition also enhances the rate of bony in-growth where said substances are particularly osteoinductive. The structure of the present device effectively delivers pharmacologically active substances to tissue- (e.g.

Abstract: An expandable endovascular stent comprises a flexible, tubular body (1) with a longitudinal axis, the wall of which is formed by interconnected, closed frame cells (2) arranged with at least two cells adjacent to each other in the circumferential direction. Filament-shaped frame material capable of transmitting compressive forces in the axial direction of the filament extends continuously from one frame cell directly into the frame cell following in the longitudinal direction. The stent can be expanded from a radially compressed state into a state having a larger diameter. In the expanded state of the stent, the pressure transmitting frame material in several of the frame cells (2) forms a heart-like or arrowhead-like shape with two interconnected shorter cell sides (5) positioned opposite to and interconnected with two mutually converging longer cell sides (3).

Abstract: A stent for the inhibition of restentosis. The stent is coated with an antigen which can be bound by a labelled antibody. The antibody is preferably labelled with a radioactive source. After the stent has been placed in the blood vessel of the subject, the antibody is injected. The antibody then binds to the antigen on the stent, thereby localizing the radioactive source to the area to be treated, for example for restenosis. Other biomedical devices, such as coil, artificial valve and vascular graft, could also be used in the place of the stent. The biomedical device could be placed in another biological passageway, such as the gastrointestinal tract, an airway or the genitourinary tract.

Abstract: A reconstructive structure for a cartilaginous element having a plurality of superimposed layers of a small intestine submucosa compressed and secured together and shaped to provide the multilayered reconstructive element of the anatomical shape of the cartilaginous element to be constructed. The method of forming the reconstructive structure includes superimposing the planar layers of the small intestine compressing, securing and cutting to the desired shape. The superimposing is performed so as to maintain the layers substantially planar prior to compressing and securing. The method of reconstructing a cartilaginous element includes removing at least a portion, if not substantially all of the cartilaginous element, but leaving a seed portion, sculpturing the reconstructive structure to the anatomical shape of the cartilaginous element to be reconstructed; positioning the receptive element adjacent to the seed portion and securing it thereto.

Abstract: The invention is directed to an apparatus and method for both supporting and preserving a piece of graft tissue during pre-implantation preparation, and for creating a tubular graft from the piece of graft tissue. The purpose of the device is (1) to support, stabilize, and preserve a piece of graft tissue; (2) to provide a rotating base to debride or otherwise prepare the donor tissue; and (3) to place the tissue around a mandrel for tubularization. The apparatus may be used as a support for preparing a piece of tissue for use as a skin graft or the like. Additionally, the preferred embodiment of the invention provides an advantageous method and apparatus for forming the graft tissue into a tubular configuration for use as a tubular graft.

Abstract: A tissue press for shaping or compressing a piece of tissue comprises first and second members movable relative to each other. A first forming element of a predetermined shape is selectively engageable on the first member. A second forming element of predetermined shape is selectively engageable on the second member. The first and second forming elements are positionable on opposite sides of the piece of tissue. The first and second members are relatively movable between a first spaced apart condition and a second condition in which the piece of tissue is held between the first and second forming elements. The means for shaping or compressing a piece of tissue may extrude the tissue. Means may also be provided for draining off fluid from compressed tissue, so that the tissue can be implanted in a compressed state and imbibe fluid from the host site. A retainer, which may be expandable, can be used to maintain the tissue graft in a compressed condition.

Abstract: Apparatus and methods are disclosed for maturing a biopolymer tissue construct in vitro prior to use as a replacement construct in vivo as, for example, a graft, implant, or prosthesis. The tissue is seeded with specific cells, exposed to a maturation fluid, such as a synovial-like fluid containing hyaluronic acid, and subjected to selected conditioning and maturation forces, which can include frictional forces, shear forces, and compressive pressure. The tissue is mounted on a first support element and a second surface applies a selected force to the tissue. This maturation process occurs within a maturation chamber. The resultant matured replacement tissue construct is intended to provide a replacement tissue that is more readily integrable in vivo to produce a more durable and functional replacement tissue.

Abstract: A method of preparing biological implantation material fixed by means of aldehydes, in which the excess aldehyde is bound by treatment with an aminocarboxylic acid and the acid is selected from compounds of the general formula: ##STR1## in which n is 1 or 2 and X is a sulpho- (--SO.sub.3 H) or phosphono- (--PO.sub.3 H) group, and mixtures of such compounds.

Abstract: A vascular prosthesis comprises pericardial, fascial, or other tissue formed over a tubular support frame. A first exemplary tubular support frame comprises an inner helical member and an outer helical member, where the tissue is rolled and captured therebetween. A second exemplary tubular support frame comprises a plurality of ring elements which are located alternately on the outside and on the inside of the rolled tissue. Other exemplary frames employ fasteners for penetrating the rolled tissue and attaching tissue to frame elements. The tissue is preferably obtained from the patient who is to receive the vascular prosthesis, with the tissue being mounted over the frame immediately prior to use.

Abstract: An intraluminal stent comprising fibrin is capable of reducing the incidence of restenosis at the site of vascular injury such as that produced by an angioplasty procedure.

Abstract: A stent or other endoprosthesis is provided from a single strand of biocompatible and resilient material into which spring coils are formed by winding the strand through in excess of 360.degree.. The thus-formed coil springs are positioned along outside edges of the endoprosthesis, with legs joining the coil springs in order to form a generally zig-zag structure. When the endoprosthesis is compressed for endoluminal delivery, the coil springs allow for large angular deflection between adjoining legs while avoiding plastic deformation of the coil or of the legs.

Abstract: A method for making an intravascular stent by applying to the body of a stent a solution which includes a solvent, a polymer dissolved in the solvent and a therapeutic substance dispersed in the solvent and then evaporating the solvent. The inclusion of a polymer in intimate contact with a drug on the stent allows the drug to be retained on the stent during expansion of the stent and also controls the administration of drug following implantation. The adhesion of the coating and the rate at which the drug is delivered can be controlled by the selection of an appropriate bioabsorbable or biostable polymer and the ratio of drug to polymer in the solution. By this method, drugs such as dexamethasone can be applied to a stent, retained on a stent during expansion of the stent and elute at a controlled rate.

Abstract: A woven vascular graft fabric that permits limited radial compliance but resists long term dilation and longitudinal extension. The thin walled graft has a double wall thickness of less than 0.02 inches and a greater number of picks per inch than ends per inch.

Abstract: A composite intraluminal device is deployable within a body vessel. The composite device includes an elongate radially expandable tubular stent having an interior luminal surface and an opposed exterior surface extending along a longitudinal stent axis. A stent cover is formed of unsintered ePTFE which is expandable. The stent cover is positioned about the stent so as to permit expansion of the cover upon the radial expansion of the stent.

Abstract: A process for impregnating a medical device made from a water absorbable polymer material, e.g., a hydrogel, with a medical compound having low solubility in aqueous solutions, e.g., an antiseptic or radiopaque compound, is disclosed. The device is first infiltrated with an aqueous solution containing a first water soluble, ionizable compound, and subsequently infiltrated with an aqueous solution containing a second water soluble, ionizable compound. The ionizable compounds are selected such that they react after mutual contact to form the medical compound in-situ within the device.

Abstract: An apparatus for sodding onto the inner lumenal surface of a synthetic graft of harvested and concentrated microvessel endothelial cells from liposuctioned fat tissues, which harvested cells are formed into a "pellet" of isolated endothelial cells in loose aggregations, includes a sodding tube having a single rigid outer wall bounding a sodding chamber. A filter pack assembly is provided to communicate the pellet of cells from a processing vessel to the graft. This filter pack assembly includes a series of successively finer filter members cooperatively defining a series of turbulent-flow chambers in which aggregations of cells too large to pass through a particular filter are exposed to liquid flow turbulence which is effective to break up the aggregations.

Abstract: An endovascular support device for treatment of chronic restenosis or other vascular narrowing is disclosed together with a method of manufacture and a method for delivering a plurality of such devices to an affected area of a vessel. In a preferred embodiment, the endovascular support device comprises a unitary wire-like structure configured to form a plurality of upper and lower peaks which may be compressed for delivery to an affected area of a coronary or peripheral vessel in a human, and then expanded to maintain a passageway through the vessel.

Abstract: An intraluminal stent comprising fibrin is capable of reducing the incidence of restenosis at the site of vascular injury such as that produced by an angioplasty procedure.

Abstract: Continuously flat-woven implantable tubular prostheses have seamless woven sections which gradually change the number of warp yarns to smoothly transition, i.e., taper, from one diameter to another. Multi-diameter endoluminal grafts having a variety of shapes and configurations are made using a seamless weaving process without unacceptable voids or gaps in the tubular wall.

Abstract: An apparatus and method for sterilizing, seeding, culturing, storing, shipping, and testing vascular grafts is disclosed. Specifically, the present invention relates to an apparatus and method for seeding and culturing vascular grafts with human cells. The apparatus includes a fluid reservoir, a pump, an alternating pressure source, and at least one treatment chamber. By alternating pressure to a support structure within the treatment chamber upon which a vascular graft scaffold is positioned, a varying radial stress is placed on the scaffold. In an alternative embodiment, fluid is pumped directly through the vascular graft subjecting the vascular graft to radial and shear stresses. Applying shear and/or radial stresses to the vascular graft during seeding and culturing simulates physiological conditions.

Abstract: A reconstructive structure for a cartilaginous element having a plurality of superimposed layers of a small intestine submucosa compressed and secured together and shaped to provide the multi-layered reconstructive element of the anatomical shape of the cartilaginous element to be constructed. The method of forming the reconstructive structure includes superimposing the planar layers of the small intestine compressing, securing and cutting to the desired shape. The superimposing is performed so as to maintain the layers substantially planar prior to compressing and securing. The method of reconstructing a cartilaginous element includes removing at least a portion, if not substantially all of the cartilaginous element, but leaving a seed portion, sculpturing the reconstructive structure to the anatomical shape of the cartilaginous element to be reconstructed; positioning the receptive element adjacent to the seed portion and securing it thereto.

Abstract: The expandable stent-graft generally defines a cylindrical lumen made from a stent having a discontinuous wall that is at least substantially covered with an expanded polytetrafluoroethylene material. The expanded polytetrafluoroethylene covering may be a biaxially oriented, expanded polytetrafluoroethylene material having nodules and longitudinal and circumferential fibrils or a uniaxially oriented, expanded polytetrafluoroethylene material. The expandable stent-graft expands and compresses in association with the stent structure as it is contracted and expanded.

Abstract: This invention relates to improved vascular prostheses derived from mammalian blood vessels. The prostheses are fabricated from arterial segments from which the donor endothelium has been removed. A key aspect of this invention is the preservation of the subendothelial extracellular matrix that will serve as the blood interface of the vascular prostheses. The vessel segments are treated to reduce the likelihood of calcification and fixed with a tissue preservative. This invention results in vascular prostheses that are particularly useful for small diameter applications, such as arterial replacement requiring a diameter of 6 mm or less.

Abstract: A device for delivery of a therapeutic substance into a body lumen including a polymer in intimate contact with a drug on a stent allows the drug to be retained on the stent during expansion of the stent and also controls the administration of drug following implantation. The adhesion of the coating and the rate at which the drug is delivered can be controlled by the selection of an appropriate bioabsorbable or biostable polymer and the ratio of drug to polymer.

Abstract: A device and method for removing a generally cylindrical tissue structure such as a blood vessel from the body of a human or animal. The device includes a body portion having distal and proximal ends with at least one lumen extending longitudinally through the body portion. The lumen is sized to accommodate the vessel and at least one tool used in removing the vessel. The lumen is provided for isolating the vessel from the tools used in the removal procedure.

Abstract: Variably compliant natural tissue valve leaflets and vascular bioprosthetics incorporating variably compliant leaflets are provided along with methods for their manufacture. The variably compliant leaflets are fixed with the leaflet base section under greater pressure than the leaflet tip section rendering them relatively stiff along the leaflet base section and more flexible at the leaflet tip section. The radially variable flexing characteristics of the valve leaflets promote even distribution of mechanical stress on the valve assembly during the cardiac cycle leading to improved hemodynamic performance while retarding the calcification of the leaflet tissue.

Abstract: The invention is directed to an expandable stent for implantation in a body lumen, such as an artery, and a method for making it from a single length of tubing. The stent consists of a plurality of radially expandable cylindrical elements generally aligned on a common axis and interconnected by one or more interconnective elements. The individual radially expandable cylindrical elements consist of ribbon-like material disposed in an undulating pattern. Portions of the expanded stent project outwardly into engagement with the vessel wall to more securely attach the stent.

Abstract: This invention relates to improved vascular prostheses derived from mammalian blood vessels. The prostheses are fabricated from arterial segments from which the donor endothelium has been removed. A key aspect of this invention is the preservation of the subendothelial extracellular matrix that will serve as the blood interface of the vascular prostheses. The vessel segments are treated to reduce the likelihood of calcification and fixed with a tissue preservative. This invention results in vascular prostheses that are particularly useful for small diameter applications, such as arterial replacement requiring a diameter of 6 mm or less.

Abstract: The invention concerns a vascular prosthesis for the replacement of blood vessels in the human or animal body, consisting of a section of a replacement blood vessel (3) which has been taken from a human or animal body and a fibro-elastic tube (2) which is drawn over this vascular section, whose intersecting threads (1) which form the tube wind in spiral form around the longitudinal axis of the tube, wherein the fibro-elastic tube (2) is extended pointwise in the longitudinal direction with alteration of the diameter or is compressed and thereby is caused to contact the replacement vessel evenly over its total area.

Abstract: A method for polishing radially expandable surgical stents is disclosed where fluid abrasive media M flows over surfaces of the stent 10 causing the surfaces of the stent 10 to be polished and streamlined. The stent 10 is temporarily provided with cylindrical support ends 20, which are not radially expandable to support the stent 10 during the polishing process. An interior polishing fixture 100 is provided which has cylindrical chambers 135 therein adapted to receive a stent 10 therein. Fluid abrasive media M then flows into bores 108 in the fixture 100 leading to the cylindrical chambers 135 and adjacent the inner diameter surfaces of the stent 10. Surfaces of the stent 10 forming the outer diameter are polished by placing the stent 10 within an exterior polishing fixture 200 which has a cylindrical recess 220 therein.

Abstract: A prosthesis for insertion into a lumen to limit restenosis of the lumen. The prosthesis carries restenosis-limiting drugs which elute after the device is positioned in the lumen.

Abstract: This invention provides a more functionalized artificial blood vessel which can be organized by independently designing its inner and outer surfaces and endowing them with respectively different biocompatibilities, as well as a process for producing the same.The artificial blood vessel comprises a tubular support having a layer of photogelled cinnamic acid-bound chondroitin sulfate coated on the inner surface thereof and a layer of photogelled coumarin-bound gelatin coated on the outer surface thereof. The process for producing the above artificial blood vessel comprises coating a layer of coumarin-bound gelatin on the outer surface of a tubular support and a layer of cinnamic acid-bound chondroitin sulfate on the inner surface of the support and irradiating each of the layers with light.

Abstract: The present invention provides a vascular prosthesis which comprises a braided tubular fabric comprising a plurality of braid layers wherein each layer includes at least one interlocking yarn which extends from that layer into another layer to form an interlock therewith. In one aspect of the invention, the plurality of braid layers may include a substantially non-absorbable first surface layer and a substantially resorbable second surface layer.

Abstract: An intraluminal stent comprising fibrin and an elutable drug is capable of providing a treatment of restenosis.

Abstract: Methods for coating a prosthetic surface with anti-thrombogenic, or anti-coagulant, proteins are disclosed. The methods involve contacting a surface of a prosthetic material with a composition containing multimers of fibrin degradation products. These multimers, preferably D-dimers, have cross-linked D-domains. The methods of the invention are useful for providing an anti-thrombogenic coating on prosthetic implants which are exposed to a patient's blood after implantation, for example vascular grafts and artificial heart valves.

Abstract: Endothelial cells transduced with genetic material encoding a polypeptide or protein of interest and, optionally, a selectable marker, as well as methods for making and using the transduced endothelial cells are disclosed. Such endothelial cells are useful in improving the performance of vascular grafts and in delivering the encoded polypeptide or protein, such as an enzyme, a hormone, a receptor or a drug, to an individual.

Abstract: A mouse model for transplant arteriosclerosis useful for identifying compounds which reduce or prevent such arteriosclerosis, consisting of a mouse engrafted with a histoincompatible artery which exhibits detectable arteriosclerosis within 30 days of transplantation. Also disclosed are therapeutic methods for inhibiting the development of transplant arteriosclerosis in mammalian recipients of allografted organs.

Abstract: A tissue press for shaping or compressing a piece of tissue comprises first and second members movable relative to each other. A first forming element of a predetermined shape is selectively engageable on the first member. A second forming element of predetermined shape is selectively engageable on the second member. The first and second forming elements are positionable on opposite sides of the piece of tissue. The first and second members are relatively movable between a first spaced apart condition and a second condition in which the piece of tissue is held between the first and second forming elements. Means are preferably provided for monitoring and controlling the amount of pressure applied to the piece of tissue, in order to maintain the tissue in a viable living condition. Means may also be provided for draining off fluid from compressed tissue, so that the tissue can be implanted in a compressed state and imbibe fluid from the host site.

Abstract: The present invention is directed to methods and compositions for immunomodifying a graft so that it is nonthrombogenic and substantially nonimmunogenic when transplanted into a recipient. In an ex vivo process, the lumenal surfaces of blood vessels comprising the vasculature within the graft are coated with an extracellular matrix, or membrane synthesized therefrom, that renders the surface substantially nonimmunogenic and nonthrombogenic to the recipient, while maintaining the viability of the donor graft vascular endothelial cells remaining underneath the coating. In addition, the extracellular matrix may provide a surface, exposed to the lumen, that can support efficient re-endothelialization with vascular endothelial cells allogeneic or preferably autologous with respect to the recipient receiving the graft.

Abstract: A process for the production of prostheses wherein endogenic tissue material is substantially mechanically comminuted and, if necessary, additionally enzymatically digested to tissue particles, whose sizes fall within very narrow limits. A preshaped carrier material is treated with the resultant suspension. In the case of a porous carrier material the suspension is filtered through the material, whereas with less or non-porous carrier material the suspension is applied to the material surface by centrifuging. Unlike the case of corresponding prior art processes, as a result of this improvement, the process according to the invention can be performed very rapidly, i.e., directly during the operation and in a closed system.

Abstract: A vascular graft in the form of a tube or flat sheet of biocompatible material having an outer covering of deflectably secured material such as porous film, fibers, discrete pieces of material, or combinations thereof. Two different types of fibers may also be used. The vascular graft may be of tubular form for replacing or bypassing entire segments of veins or arteries or alternatively may be in the form of a flat sheet useful for repairing portions of the circumference of veins or arteries. The tube or flat sheet of biocompatible material and the outer covering of deflectably secured material are preferably of porous polytetrafluoroethylene. The inventive vascular graft is useful for dialysis access in that it offers a reduction in blood leakage when the vascular graft is punctured by a dialysis needle and the needle is subsequently removed. It is also useful for reducing suture hole bleeding resulting from holes created through the graft by penetration of the graft with a suture needle.