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Publication numberUSRE31618 E
Publication typeGrant
Application numberUS 06/369,962
Publication dateJul 3, 1984
Filing dateApr 19, 1982
Priority dateOct 12, 1978
Also published asCA1143105A1, DE2941279A1, US4306318
Publication number06369962, 369962, US RE31618 E, US RE31618E, US-E-RE31618, USRE31618 E, USRE31618E
InventorsHiroshi Mano, Toshisaburo Oga
Original AssigneeSumitomo Electric Industries, Ltd.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Tubular organic prosthesis
US RE31618 E
Abstract
A tubular organic prosthesis comprising a porous tubing of polytetrafluoroethylene and elastic fibers provided helically on its outside surface.
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Claims(14)
What is claimed is:
1. A tubular organic prosthesis comprising a porous tubing of polytetrafluoroethylene and elastic fibers provided helically on its outside surface.
2. The prosthesis of claim 1, wherein said polytetrafluoroethylene tubing has a microstructure composed of fibers and nodes connected to one another by said fibers, said fibers being radially distributed.
3. The prosthesis of claim 1, wherein said elastic fibers are made from polyurethane.
4. The prosthesis of claim 3, wherein said polyurethane is a polyether polyurethane.
5. The prosthesis of claim 4, wherein said prosthesis has a suture tear resistance of about 300 g/ply or more.
6. The prosthesis of claim 1, wherein said elastic fibers are rubber yarns.
7. The prosthesis of claim 1, wherein said fibers have a denier of about 150 to about 5,000.
8. The prosthesis of claim 1, wherein said fibers have a tensile strength of about 1 g/denier.
9. The prosthesis of claim 1, wherein said PTFE tubing has a porosity of at least about 70%.
10. The prosthesis of claim 1, wherein said PTFE tubing has a wall thickness of about 0.3 to 1.0 mm.
11. The prosthesis of claim 1, wherein said PTFE tubing has an average pore diameter of about 2 μm to about 100 μm.
12. The prosthesis of claim 1, wherein said prosthesis has a suture tear resistance of about 300 g/ply or more.
13. The tubular organic prosthesis of claim 1, wherein said tubular organic prosthesis is a vascular prosthesis.
14. The prosthesis of claim 13, wherein said prosthesis has a suture tear resistance of about 300 g/ply or more.
Description
BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an improvement in and relating to a tubular organic prosthesis composed of a porous tubing of polytetrafluoroethylene (abbreviated "PTFE"), and is directed to increasing the strength of the tubing and its ability to connect with the tissues of a patient.

2. Description of the Prior Art

Many reports have been made heretofore to show that a porous tubing of PTFE produced by a stretching method can be clinically used as a tubular organic prosthesis, especially as a vascular prosthesis. Such a prosthesis is regarded as better than conventional prostheses made of knitted or woven fabrics. A PTFE tubing which has been subjected to a stretching treatment has a microstructure composed of very fine fibers and nodes connected to one another by the fibers. The diameters of the fibers vary depending on stretching conditions, and can be made much smaller than those of the fibers of the knitted or woven fabrics mentioned above. Moreover, since the pore diameter and porosity of the tubing can be varied freely, when it is used, for example, as an artifical vessel, it is pliable and scarcely permits formation of thrombus. The tubing also shows good formation of a pseudointima on the inner surface without any appreciable adverse effect on the surrounding tissues. Thus, the stretched tubing is regarded as one of the best prostheses for tubular organs.

The stretched PTFE tubing, however, has the disadvantage that when it is used as a tubular organic prosthesis and joined with the living body, the needle or suture tends to tear the tubing. This tearing frequently occurs in the axial direction of the porous PTFE tubing. Since this is due to the orientation of the fine PTFE fibers formed as a result of stretching, it can be reduced to some extent by biaxially stretching the tubing, namely stretching it in the axial direction and expanding its diameter, thereby to change the structure of the fine fibers to a radial orientation. A great improvement in strength, however, cannot be expected from this process alone. Furthermore, it is difficult for natural occlusion of suture holes to occur based on the elasticity of the porous PTFE tubing alone, and when it is used as an artificial vessel, bleeding from the suture holes is also a problem. Further, when it is sharply bent it buckles and cannot retain a cylindrical shape. This is also a drawback in practical application.

The present invention offers a solution to these problems in a junction operation.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a tubular organic prosthesis comprising a porous PTFE tubing and elastic fibers provided helically on its outside surface.

Another object of this invention is to provide a tubular organic prosthesis which permits easy entry and attachment of the surrounding tissues to promote the assimilation of the prosthesis.

According to this invention, there is provided a tubular organic prosthesis comprising a porous tubing of polytetrafluoroethylene and elastic fibers provided helically on its outside surface.

In another aspect, the invention provides a process for producing a tubular organic prosthesis which comprises wrapping elastic fibers helically about the outside surface of a porous tubing of polytetrafluoroethylene, impregnating the resulting structure with a solvent capable of dissolving or swelling the elastic fibers to thereby bond them to the PTFE tubing, drying the structure, and then heat-setting.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE is a side view of the tubular prosthesis showing the essential elements thereof. Said tubular prosthesis is provided with a body of porous PTFE 1, which body is helically provided with elastic fibers upon its outer surface 2.

DETAILED DESCRIPTION OF THE INVENTION

As a result of providing elastic fibers helically on the outside surface of the porous PTFE tubing, the porous PTFE tubing of the present invention does not undergo tearing by a joining needle or suture. It also has the advantage that when the tubing together with the elastic fibers is sutured at the time of a junction operation, the holes left after joining are occluded by the elasticity of the fibers. Furthermore, since the elastic fibers are helically oriented, the tubing is pliable in the longitudinal direction, and even when it is sharply bent, it does not easily buckle. In addition, spaces for easy entry of the surrounding tissues of a patient are available on the outside surface of the tubing and this accelerate the assimilation of the porous PTFE tubing as an organic prosthesis.

The porous tubing of PTFE in accordance with this invention is produced by the method described in Japanese Patent Publication No. 13560/67 and, e.g., U.S. Pat. Nos. 3,953,566 and 3,962,153. A liquid lubricant is mixed with an unsintered powder of polytetrafluoroethylene and the mixture is extruded into a tubular form by a ram-type extruder. The PTFE used in this invention preferably has a molecular weight of 106 to 107. The tubing is stretched at least monoaxially after the liquid lubricant is optionally removed. Preferably, the tubing is stretched in the axial direction, and its diameter is expanded. The tubing is heated at a temperature above 327 C. which is the sintering temperature while fixing it in place to avoid shrinkage. Thus, the stretched and expanded structure is fixed and a tubing having increased strength is obtained. The resulting porous PTFE tubing has a microstructure composed of very fine fibers and nodes connected to one another by these fibers. Because the diameters and lengths of these fibers and the sizes and number of the nodes can be varied depending upon the stretching and sintering conditions, the pore diameter and porosity of the resulting porous tubing can be determined freely. It has been clinically confirmed that when this tubing is used as a vascular prosthesis, it suitably has an average pore diameter of about 2 μm to about 100 μm, a porosity of at least about 70%, and a wall thickness of about 0.3 to 1.0 mm.

In the microstructure of the porous PTFE tubing preferred in this invention, the fibers are distributed not unidirectionally but radially. This fibrous structure is obtained by biaxially stretching the PTFE tubing, namely by stretching it in the axial direction and expanding its diameter. Expansion of its diameter can be achieved by reducing the pressure on the outside surface of the tubing, or pressing its inside surface, or simultaneously performing these two procedures, while heating. Alternatively, the diameter of the tubing may be mechanically enlarged by passing an article of a suitable configuration through the inside of the tubing. Stretching of the tubing in the axial direction and expansion of its diameter are carried out simultaneously or successively, or may be carried out simultaneously with the final sintering step. The porous PTFE tubing obtained by the biaxial stretching method is more pliable and less prone to longitudinal tearing than a porous PTFE tubing stretched only in the axial direction because the fibers are distributed not only in the axial direction but radially in all directions. However, to perform a junction operation using this biaxially stretched porous PTFE tubing, more improvements in strength, natural occlusion of the suture holes, bending property, and the ability to connect with the tissues of a patient are desired.

In accordance with this invention elastic fibers are helically provided on the outside surface of the porous PTFE tubing to solve the aforesaid problems.

The elastic fibers are fibers produced from at least 50% elastomer. They include polyurethane fibers and fibers from various rubbers (so-called rubber yarns), e.g., silicone rubbers, fluorine rubbers, acrylic rubbers, natural rubber, etc. Examples of non-elastomers which may be present in combination with the elastomers include polyamides, polyesters, polypropylenes, etc. The elastic fibers used in this invention are described in detail below with reference to polyurethane fibers which constitute a preferred embodiment of the present invention. Substantially the same description will apply to other elastic fibers.

Preferably fibers are selected and wrapped around the prosthesis to give it a suture tear resistance of at least 300 g/ply. The polyurethane elastic fibers are made from an organic diisocyanate and a polyether or polyester and are characterized by their elasticity. Polyurethane fibers normally used for apparel are also suitable for the purposes of this invention. Polyurethane elastic fibers of the polyether type are especially suitable for organic prostheses.

The fibers may be in the form of monofilaments or multifilaments. Not only bare yarns of polyurethane but also processed or modified yarns can be used to achieve the objects of this invention. Commercally available processed yarns include covered yarns having other fibers wrapped thereabout, core spun yarns having polyurethane fibers as a core, ply yarns, etc. All of these yarns can be used in this invention. The polyurethane elastic yarns usually have a tensile strength of about 1 to 1.5 g/denier (ASTM D-638) and those having a size of about 150 denier to about 5,000 denier are effective.

To provide the elastic fibers helically on the outside surface of the porous PTFE tubing, the fibers are first helically wrapped about the outside surface of the tubing. The fibers may be wrapped in close contact with one another, or at some interval, preferably not exceeding the diameter of the prosthesis. A suitable thickness of the fiber wrapping ranges from about 0.05 mm to about 1 mm.

After wrapping, the fibers are impregnated with a solvent capable of dissolving or swelling the elastic fibers to dissolve the elastic fibers partly and bond them to the PTFE tubing. Suitable solvents for the polyurethane elastic fibers include phenol, m-cresol, benzene, toluene, formic acid, tetrahydrofuran, N,N-dimethylformamide and N,N-dimethylacetamide. The structure impregnated with the solvent is dried, and then heated at a suitable temperature to heat-set it. This heat-setting relaxes the residual stress of the helically wrapped elastic fibers, and sets their configuration. The heat-setting temperature and time are determined according to the material of the elastic fibers. In the case of polyurethane elastic fibers, heat-setting is usually carried out at a temperature of about 120 to 230 C. for a period of 1 to 60 minutes. Heating may be effected in air or with steam or the like.

The tubular organic prosthesis of this invention described hereinabove is very useful as an artificial vessel, but can also be used for the prosthesis of other tubular organs including the esophagus, trachea, biliary duct, ureter, and urethra.

The following Examples illustrate the present invention more specifically. It should be understood that the scope of the invention is not limited by these Examples.

EXAMPLE 1

One hundred parts by weight of fine PTFE powder, Polyflon F-104 (a trademark for a product of Daikin Kogyo Co., Ltd.), was mixed uniformly with 29 parts by weight of a liquid lubricant (Deobase). The mixture was pre-formed under pressure, and extruded by a ram-type extruder into a tubing having an inside diameter of 3.0 mm and an outside diameter of 4.5 mm. The tubing was dipped in trichloroethylene to extract and remove the liquid lubricant, and then stretched 200% in the axial direction of the tubing while it was heated at about 250 C. The stretched tubing was then heated at 350 C. while reducing the pressure on the outside surface of the tubing to expand its diameter and simultaneously sinter the tubing. The tubing obtained was a porous tubing having an inside diameter of 4.0 mm, and outside diameter of 4.9 mm, and a porosity of 79%.

A stainless steel rod having a diameter of 4.0 mm was inserted in the porous PTFE tubing, and elastic polyurethane multifilaments having a size of 1,120 denier were densely wrapped helically about the outside surface of the tubing. The filaments were fixed at both ends, and impregnated with tetrahydrofuran to bond them. The resulting structure was dried and heated at 170 C. for 10 minutes to heat-set the fibers. The resulting tubing did not deform even when the stainless steel rod was withdrawn. It was pliable and had high flexibility. When a stainless steel wire having a diameter of 0.40 mm was inserted in a loop-like configuration into the wall of the tubing at 5 mm from one end of the tubing, and pulled in the axial direction of the tubing at a speed of 50 mm/min., tearing occurred in the tubing under a load of 1,250 g which is much larger than the load (180 g) under which tearing occurred in the tubing without the elastic fibers. Holes left after inserting a surgical suturing needle were naturally occluded by the elasticity of the elastic fibers. Thus, the resulting product had various superior characteristics as a tubular organic prosthesis.

EXAMPLE 2

Elastic polyurethane multifilaments having a size of 2,240 denier were wrapped helically at intervals of 0.5 mm about the outside surface of the same porous PTFE tubing as used in Example 1, and treated in the same way as in Example 1. The load under which tearing occurred in the resulting tubing was 860 g. Thus, the product had superior characteristics as a tubular organic prosthesis as in the case of the tubing obtained in Example 1.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3105492 *Oct 1, 1958Oct 1, 1963Us Catheter & Instr CorpSynthetic blood vessel grafts
US3479670 *Oct 19, 1966Nov 25, 1969Ethicon IncTubular prosthetic implant having helical thermoplastic wrapping therearound
US3490975 *Oct 10, 1966Jan 20, 1970Univ Of Birmingham TheMethod of making an artificial artery of wound silicone rubber thread
US4229838 *Jul 3, 1978Oct 28, 1980Sumitomo Electric Industries, Ltd.Polytetrafluoroethylene tube, quaternized polyethylenimine, heparin
FR2248015A1 * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5100422 *May 26, 1989Mar 31, 1992Impra, Inc.Expanded polytetrafluoroethylene layer and nonporous elastomer coating for vascular patches
US5104400 *Aug 28, 1991Apr 14, 1992Impra, Inc.Coating outer wall of polytetrafluoroethylene tube with elastomer; drying; opening tube; cutting patch from flat sheet
US5152782 *May 26, 1989Oct 6, 1992Impra, Inc.Non-porous coated ptfe graft
US5207705 *Dec 8, 1989May 4, 1993Brigham And Women's HospitalVascular systems
US5282823 *Mar 19, 1992Feb 1, 1994Medtronic, Inc.Intravascular radially expandable stent
US5433909 *Mar 12, 1993Jul 18, 1995Atrium Medical CorporationMethod of making controlled porosity expanded polytetrafluoroethylene products
US5443496 *Oct 15, 1993Aug 22, 1995Medtronic, Inc.Intravascular radially expandable stent
US5527353 *Dec 2, 1993Jun 18, 1996Meadox Medicals, Inc.Implantable tubular prosthesis
US5556426 *Aug 2, 1994Sep 17, 1996Meadox Medicals, Inc.PTFE implantable tubular prostheses with external coil support
US5641373 *Apr 17, 1995Jun 24, 1997Baxter International Inc.Method of manufacturing a radially-enlargeable PTFE tape-reinforced vascular graft
US5651174 *Apr 27, 1995Jul 29, 1997Medtronic, Inc.Intravascular radially expandable stent
US5800510 *Jun 6, 1995Sep 1, 1998Meadox Medicals, Inc.Implantable tubular prosthesis
US5800512 *Jan 22, 1996Sep 1, 1998Meadox Medicals, Inc.PTFE vascular graft
US5861033 *Jan 30, 1997Jan 19, 1999Atrium Medical CorporationImplantable prosthesis tube of porous ptfe including a tube wall with a porous microstructure of nodes and fibrils, with tapered channels between nodes, wall is uniformly sintered; fibrils impede leakage while allowing cellular growth
US6245100Feb 1, 2000Jun 12, 2001Cordis CorporationMethod for making a self-expanding stent-graft
US6270523Oct 15, 1999Aug 7, 2001Atrium Medical CorporationExpandable shielded vessel support
US6287337Feb 8, 1999Sep 11, 2001Atrium Medical CorporationMulti-stage prosthesis
US6296661Feb 1, 2000Oct 2, 2001Luis A. DavilaSelf-expanding stent-graft
US6312458 *Jan 19, 2000Nov 6, 2001Scimed Life Systems, Inc.Tubular structure/stent/stent securement member
US6355063Jan 20, 2000Mar 12, 2002Impra, Inc.Expanded PTFE drug delivery graft
US6416537Jun 27, 2000Jul 9, 2002Atrium Medical CorporationMulti-stage prosthesis
US6423089Apr 22, 1999Jul 23, 2002Atrium Medical CorporationVascular endoprosthesis and method
US6428571Mar 14, 2000Aug 6, 2002Scimed Life Systems, Inc.Self-sealing PTFE vascular graft and manufacturing methods
US6478813Dec 29, 1999Nov 12, 2002Peter T. KeithMethod for joining grafts in a common body passageway
US6482227Nov 16, 2000Nov 19, 2002Cordis CorporationStent graft having improved attachment within a body vessel
US6575994Nov 10, 2000Jun 10, 2003Teramed, Inc.Method and apparatus concerning bypass grafts
US6589468May 12, 2000Jul 8, 2003Meadox Medical, Inc.Method of forming an implantable tubular prosthesis
US6626938Nov 16, 2000Sep 30, 2003Cordis CorporationStent graft having a pleated graft member
US6719783Aug 5, 2002Apr 13, 2004Scimed Life Systems, Inc.PTFE vascular graft and method of manufacture
US6814753May 7, 2003Nov 9, 2004Scimed Life Systems, Inc.Implantable tubular prosthesis
US6840958 *May 14, 2003Jan 11, 2005Scimed Life Systems, Inc.Shaped woven tubular soft-tissue prostheses and method of manufacturing the same
US6843802Nov 16, 2000Jan 18, 2005Cordis CorporationDelivery apparatus for a self expanding retractable stent
US6863686Jul 24, 2001Mar 8, 2005Donald ShannonRadially expandable tape-reinforced vascular grafts
US6881221 *Sep 28, 2001Apr 19, 2005Scimed Life Systems, Inc.Tubular structure/stent/stent securement member
US6887268Jan 8, 2002May 3, 2005Cordis CorporationExtension prosthesis for an arterial repair
US6942692Jan 8, 2002Sep 13, 2005Cordis CorporationSupra-renal prosthesis and renal artery bypass
US7229472Jan 8, 2002Jun 12, 2007Cordis CorporationThoracic aneurysm repair prosthesis and system
US7244271Apr 9, 2004Jul 17, 2007Boston Scientific Scimed, Inc.Self-sealing PTFE vascular graft and manufacturing methods
US7267685Jan 8, 2002Sep 11, 2007Cordis CorporationBilateral extension prosthesis and method of delivery
US7314483Jan 8, 2002Jan 1, 2008Cordis Corp.Stent graft with branch leg
US7326237Jan 8, 2002Feb 5, 2008Cordis CorporationSupra-renal anchoring prosthesis
US7462675Sep 14, 2005Dec 9, 2008Gore Enterprise Holdings, Inc.Thermoplastic copolymer of tetrafluoroethylene and perfluoromethyl vinyl ether and medical devices employing the copolymer
US7500988Nov 16, 2000Mar 10, 2009Cordis CorporationStent for use in a stent graft
US7862609Jul 18, 2003Jan 4, 2011Cordis CorporationStent graft having a pleated graft member
US8029563Nov 29, 2004Oct 4, 2011Gore Enterprise Holdings, Inc.Implantable devices with reduced needle puncture site leakage
US8048440Mar 16, 2006Nov 1, 2011Gore Enterprise Holdings, Inc.Thermoplastic fluoropolymer-coated medical devices
US8062354Dec 10, 2004Nov 22, 2011Edwards Lifesciences CorporationRadially-expandable PTFE tape-reinforced vascular grafts
US8066758Dec 28, 2005Nov 29, 2011C. R. Bard, Inc.Vascular graft with kink resistance after clamping
US8157940Aug 24, 2009Apr 17, 2012Bard Peripheral Vascular, Inc.Methods for making a supported graft
US8196279Feb 24, 2009Jun 12, 2012C. R. Bard, Inc.Stent-graft covering process
US8313524Aug 30, 2005Nov 20, 2012C. R. Bard, Inc.Self-sealing PTFE graft with kink resistance
US8337650Mar 29, 2012Dec 25, 2012Bard Peripheral Vascular, Inc.Methods for making a supported graft
US8609125Oct 27, 2011Dec 17, 2013W. L. Gore & Associates, Inc.Thermoplastic fluoropolymer-coated medical devices
US8617337Feb 8, 2011Dec 31, 2013Bard Peripheral Vascular, Inc.Partial encapsulation of stents
US8617441Feb 17, 2012Dec 31, 2013Bard Peripheral Vascular, Inc.Methods for making an encapsulated stent
US8636794Nov 9, 2006Jan 28, 2014C. R. Bard, Inc.Grafts and stent grafts having a radiopaque marker
US8647458Dec 14, 2012Feb 11, 2014Bard Peripheral Vascular, Inc.Methods for making a supported graft
US8652284Nov 21, 2011Feb 18, 2014C. R. Bard, Inc.Vascular graft with kink resistance after clamping
US8696738 *May 20, 2010Apr 15, 2014Maquet Cardiovascular LlcComposite prosthesis with external polymeric support structure and methods of manufacturing the same
US20110288628 *May 20, 2010Nov 24, 2011Maquet Cardiovascular LLC.Composite prosthesis with external polymeric support structure and methods of manufacturing the same
US20130095228 *Dec 3, 2012Apr 18, 2013Cook Medical Technologies LlcIntroducer sheath with encapsulated reinforcing member
Classifications
U.S. Classification623/1.33
International ClassificationA61L27/00, A61F2/06, A61L27/16, A61F2/04, A61F2/02
Cooperative ClassificationA61L27/16, A61F2/06
European ClassificationA61L27/16, A61F2/06