Claims
- 1. A method of forming a bio-compatible vascular prosthesis which comprises the steps of:
- (a) forming a solution of a coagulatable, bio-compatible polymer in an organic solvent;
- (b) extruding the solution through an extrusion head on to a mandrel having an axis being fed axially through the extrusion head together with the extruding solution, the extrusion being directed into a coagulant liquid which coagulates the polymer into a hollow polymer extrusion on the mandrel;
- (c) simultaneously rotating the mandrel and the extrusion head about the axis of the mandrel during the extrusion; and
- (d) removing the mandrel to form a vascular prosthesis which closely approximates a natural artery in its elastic extensibility and compressibility.
- 2. A method according to claim 1, in which the method is carried out at temperature not exceeding about 40.degree. C.
- 3. A method according to claim 1, in which the solution further comprises a filler soluble in the coagulant.
- 4. A method according to claim 3 in which the filler is sodium hydrogen carbonate.
- 5. A method according to claim 3, in which the filler is ground to an average particle size of 60 microns.
- 6. A method according to claim 3, in which the filler comprises between 10 and 60 percent of the weight of said solution.
- 7. A method according to claim 1, in which the solution comprises surfactant which comprises between 1 and 10 percent of the weight of said solution.
- 8. A method according to claim 1, in which the polymer comprises polyurethane.
- 9. A method according to claim 8, in which the polyurethane is a linear segmented poly(ether)urethane with a number average molecular weight in the region 20,000 to 60,000.
- 10. A method according to claim 1, in which the solvent is aprotic.
- 11. A method according to claim 1, in which the solvent comprises N,N-Dimethylacetamide.
- 12. A method according to claim 10, in which the solvent comprises N,N-Dimethylformamide.
- 13. A method according to claim 1, in which the said solution is injected from a piston in cylinder arrangement of which the piston and cylinder are in relative rotation to impose a shearing force on the said solution and thus in effect decrease its viscosity.
- 14. A method according to claim 1, in which the mandrel has a smooth surface on to which the polymer solution is cast directly.
- 15. A method according to claim 1, in which the mandrel is arranged to be horizontal in the coagulant and is rotated about a horizontal axis so as to maintain the concentricity of the tubular form of the cast polymer solution during coagulation.
- 16. A method according to claim 15, in which an extrusion head through which the mandrel extends rotates with the mandrel.
- 17. A method according to claim 1, in which the coagulant comprises water.
- 18. A method according to claim 17, in which the coagulant is maintained at a constant temperature throughout the coagulation process.
- 19. A method according to claim 1, in which the coagulation is maintained for 1 to 2 hours.
- 20. A method according to claim 1, in which the coagulant is circulated during coagulation.
Priority Claims (1)
Number |
Date |
Country |
Kind |
8708476 |
Apr 1987 |
GBX |
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Parent Case Info
This application is a continuation of application Ser. No. 07/132,330, filed on 12/14/87, now abandoned.
US Referenced Citations (5)
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Continuations (1)
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Number |
Date |
Country |
Parent |
132330 |
Dec 1987 |
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