DE2704771A1 - VESSEL PROSTHESIS - Google Patents

Description

TlEDTKE - BüHLING - KlNNE - GrMPE

2 7 0 A 7 7 1 Dipl.-Chem. Bühling

Dipl.-Ing. Kinne Dipl.-Ing. Group

Bavariaring 4, P.O. Box 20 24. 3. 8000 Munich 2

Tel .: (0 89) 53 96 53-56 Telex: 5 24 845 tipat cable. Germaniapatent Munich February 4th 1977

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ICI case Q / PH 28530

IMPERIAL CHEMICAL INDUSTRIES LIMITED London, United Kingdom

Vascular prosthesis

The invention relates to an electrostatically spun and by means of a suitable collecting device Product having absorbed organic fiber material according to patent ... (according to patent application P 25 34 935.3).

In the DT patent application P 25 34 935.3 is the Manufacture of products, including tubular products, by electrostatic spinning organic material. Reference is expressly made here to these statements.

The electrostatic spinning process involves the introduction of a liquid into an electric field, which is thereby caused to form fibers which tend to be drawn towards an electrode.

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Dresdner Dank (Munich) KlO 3939 844 Postscheck (Munich) KIo. 670-43-804

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When drawn out of the liquid, the fibers usually harden, which process is simply a cooling process (if the spinning liquid is normally solid e.g. at room temperature), chemical hardening (e.g. treatment with hardening vapors) or evaporation of solvents (e.g. by dehydration). The product fibers can be collected on a suitably arranged receptacle and subsequently stripped or peeled off from it.

Tubular products obtained by the above procedure are now considered to be synthetic Blood vessels (vascular prostheses) particularly useful, e.g. for a replacement of damaged or impaired Blood vessels in the mammalian body can be used. Such vascular prostheses typically have at least one tubular section with an inside diameter in the region of 0.3 to 3 cm.

According to the invention, the product comprising fiber material is therefore of the type mentioned at the outset characterized in that it is in the form of a vascular prosthesis having a tubular or tubular portion with an inner diameter (or a maximum inner cross-sectional dimension) of the order of 0.3 to 3 cm.

Preferred inside diameters are in the region of 0.5 to 2 cm and in particular 0.8 to 1.5 cm.

The vascular prostheses according to the invention are usually in the form of a simple tube or tubing with one bore with a circular cross-section and one that is essentially constant along its length

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• jT *

Diameter are available. However, it is possible that the The diameter of the hole shows regular or uneven changes, such as a tapered or tapered bore or a bore with constrictions and / or the cross-sectional shape of the bore of deviates from the circular shape and e.g. oval or rectangular or any other possibly suitable Shape can be. If the cross-section of the bore is not circular, the above refer to Dimensions to the maximum dimensions. The exterior of the prosthesis can follow the contour of the bore or away from it differ; it may have reinforcing elements that e.g. circular or spiral or helical and rigid, elastic, flexible or partially flexible (e.g. in a predetermined direction). The shape and structure of the prosthesis will be such that the physical requirements of their puncture are met; e.g. it can have such a configuration that their connection with an adjacent vessel is facilitated or it may be such that one Curvature or flexibility of the vessel in certain directions is favored or restricted.

The prosthesis according to the invention can be made from a solution or dispersion of a polymer or its precursors (Precursors) are spun. To polymers which are suitably spun from solution can include high molecular weight fiber-forming thermoplastics; in particular would be polyurethane, polyamides and Mention polyacrylonitrile. Polymers which can suitably be spun as a dispersion include Polytetrafluoroethylene and polyester as well as those given above. As an example of a polymer precursor, that can be spun from the solution is urea-formaldehyde to be mentioned, which can be crosslinked after the spinning process by treatment with acid vapor.

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Water-soluble polymers such as polyvinyl alcohol, polyvinylpyrrolidone and polyethylene oxide can be spun from an aqueous solution. Although the possibility is not to be excluded here that prostheses made from such materials can be used as such, such prostheses are preferably at least a certain degree of insolubility in aqueous medium, ζ.Β. by crosslinking with a suitable crosslinking agent.

If the prostheses are spun from a dispersion, the spinning material preferably also comprises a solution of an additional component which has a viscosity-increasing effect on the suspension and improves its fiber formation properties. It has been found that for this purpose is an additional organic polymeric material most suitable, which then destroys the fiber formation as desired or during sintering can be eliminated v / ground. The application of such to-

^ O additional material for influencing the viscosity and / or fiber formation on spinning from solution can also be beneficial.

The preferred spinning material is thereafter a solution or suspension, which preferably comprises an organic polymer in such an amount that it is capable of fiber formation and has such cohesive properties that the fiber shape is retained during any subsequent hardening of the fiber until the fiber has hardened to the point that it does not lose its fiber shape at replacement of a base (where appropriate).

The additional organic component only needs in a relatively small amount (usually in the range of

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0.001 to 12 % and preferably 0.01 to 3% by weight of the suspension), although the exact concentration for any particular application can easily be determined by preliminary tests. 5

The degree of polymerization of the additional organic Component is preferably greater than about 2,000 linear units; a wide range of such Polymers is available. An essential requirement is the solubility of the polymer in the chosen one Solvent or suspension medium, which is preferably formed by water. As examples of water-soluble polymer compounds can be polyethylene oxide, polyacrylamide, polyvinylpyrrolidone, and polyvinyl alcohol to be named; if an organic medium is used to produce the spinning material (either as the sole liquid solvent or as a component thereof), there is another broad one Variety of organic polymer compounds available such as polystyrene and polymethyl methacrylate.

The degree of polymerization of the polymer is determined in view of the required solubility and ability of the polymer selected, the fiberizable liquid the desired cohesive and viscosity properties to rent.

Any suitable method can be used for introducing the spinning material into the electrostatic field be applied; e.g. the spinning liquid was introduced into the electric field at a suitable point, by feeding it to a nozzle from which it was withdrawn by the action of the field, whereupon Fiber formation occurred. Any suitable device may serve this purpose; so became the spinning material

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e.g. from the reservoir of a (injection) syringe of the a tip or opening suitably spaced from an electrostatically charged surface a grounded syringe needle or a plurality of needles. When leaving the needle or needles the material forms fibers between the tip of the needle and the charged surface.

The optimum distance between the nozzles and the loaded surface is easily determined by simply trying ("trial and error") determined. For example, it has been found that with a potential in the region of 20 kV a A distance of 5 to 35 cm is suitable, although with a change in the charge, nozzle dimensions, Flow rate of the liquid, size of the charged area etc. the optimal distance can vary and is best determined as described.

The electrostatically charged surface can be formed by the sides of a rotating tube or cylinder which is coaxial with the nozzle and at a suitable distance therefrom. Alternatively the fiber deposition and formation of a tube can be done on a cylindrical bobbin. This can be formed from any of a variety of materials. A metallic bobbin is preferred, especially one made of aluminum. The hose or tube formed can be removed from the bobbin can be removed in a variety of ways. In particular, it should be noted that a polyurethane pipe is preferably made of an aluminum bobbin is "peeled off" or stripped, while an aluminum bobbin is used to achieve a PTFE tube can be dissolved in caustic soda. To make it easier for polyurethane to be stripped off The latter can expediently be aluminum bobbins

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be covered with a layer of flexible polyurethane foam.

The applied electrical voltage is usually in the range from 5 to 1000 kV, expediently 10 to 100 kV and preferably 10 to 50 kV.

The prostheses can depending on the intended function have a diverse shape. E.g.

- as already mentioned - a simple straight or bent or curved pipe can be produced or a pipe loop or an anastomosis or a fork. In all of these cases, however, at least it will part of the prosthesis is in the form of a tube with the dimensions mentioned above.

The wall thickness of the prosthesis can vary within wide limits and is influenced, among other things, by the strength and / or elasticity desired in the product. The wall thickness can in turn be different on different parts of the prosthesis. It is preferred, however, that a substantial part of the wall should have a thickness in the region of 0.5 to 5 mm, in particular 1 to 3 mm.

The actual dimensions of the prosthesis will, of course, be based on its intended function and arrangement selected and the prostheses can of course on a mandrel of appropriate dimensions and Configuration can be established.

The prosthesis can be obtained by spinning onto a mandrel of suitable shape. Where appropriate, the mandrel can be made removable from the interior of the spun prosthesis, for example by

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Collapse (e.g. when using an inflatable

Doms), dissolving (when using a dome with a suitable soluble material) or by a melting process.
5

The use of fibers of small diameter, such as 0.1 to 10 μm and in particular 0.4 to 10 μm, is preferred and preferably at least the part of the prosthesis adjacent to the bore will be porous, with preferably the majority of the pores in the area of 5 to 25, in particular 7 to 15 μm (diameter).

The preferred prostheses comprise fibers of a suitable polyurethane which is of a wide range of available materials taking into account ease of manufacture, lack of toxicity, Solubility, mechanical properties, degree of biodegradability, etc. is selected. Although

2.0 a completely polymerized polyurethane dissolved in a suitable solvent (together with other additives, as required) is preferred for use as a spinning solution, the possibility of spinning incompletely polymerized polyurethane

2 ^ than with completion of the polymerization during the spinning process or thereafter could not be excluded. For example, you can have an incomplete Spun polymerized polyurethane product on an inflatable mandrel in a certain configuration and inflate the mandrel to stretch the formed product (e.g., to increase the porosity to a desired one Measure) and then cure the product under these (expanded) conditions.

The following example serves to illustrate the invention.

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example 1

A 12 Solution of polyurethane ("Daltermold" 338E) in dimethylformamide electrostatically by a battery of 24 Needles are spun at a rate of 1 g / needle / hour. The pipe produced had a wall thickness of 2 mm of mainly 0.5 Α ™ (diameter) fibers, that were connected at the contact points.

The tube was sutured into the descending aorta in pigs. After 6 months the Review of the grafting of a well-attached thin intina, intramural capillary growth and a tight one attached adventitial layer. No thrombosis was observed.

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Claims (7)

B 7945 270A771 claims 1. J Electrostatically spun and using a suitable Collection device containing organic fiber material containing product according to patent ... (according to application P 25 34 935.3), characterized in that it is in the form of a vascular prosthesis is present, which is a tubular or tubular part with an inner diameter (or a maximum internal cross-sectional dimension) of the order of 0.3 to 3 cm. 2. Product according to claim 1, characterized in that the fibers comprise a polyurethane. 3. Product according to claim 1 or 2, characterized shows that the fibers have a diameter of 0.4 to 10 / am. 4. Product according to one of the preceding claims, characterized by a deviating from the elongated tube Shape, especially in the form of a pipe loop or bend, anastomosis or bifurcation. 5. Product according to one of the preceding claims, characterized by a non-electrostatic Reinforcement formed during the spinning process. 6. Vascular prosthesis, in particular according to one of the preceding claims, characterized by polyurethane fibers and a tubular part with a core with an inner diameter or inner dimension in the area from 0.3 to 3 cm. 709 Π 33/0266 ORIGINAL INSPECTED -W- B 7945 7. A method for producing a vascular prosthesis according to any one of the preceding claims, characterized by electrostatic spinning of a fiber-forming mass and collecting the fibers thus formed on a suitably shaped bobbin or mandrel. - & T- Proverbs 1 to 6 in des zu erseti “E -en. Removal of the udder vessel section and sewing in -1. ♦ 77 P? 3 / 026S