US4173689A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Synthetic polymer prosthesis material
Assignee: University of Utah Research Foundation Inc
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Filing: 1976-02-03
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Granted: 1979-11-06
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Expires: 1996-02-03
Abstract
Abstract A blood and body-tissue compatible synthetic polymer having mechanical compliance properties matching that of body tissue, useful in prosthesis as vascular grafts, skin covering, small diameter body duct work, and similar tissue replacement materials. A block copolymer having suitable body and blood compatibility characteristics is dissolved in a solvent, yielding a solution having an approximate relative viscosity between the range of 100 to 1000. A clean mandrel is slowly dipped into the solution and slowly withdrawn, leaving a uniform coating of polymer solution over the forming surface of the mandrel. The coated mandrel is then immersed into a second, nonsolvent solution which is miscible with the first solvent. The resulting transfer of the nonsolvent solution into the polymer network, displacing the first solvent molecules, acts to precipitate the polymer in a physical form containing a uniform dispersion of voids throughout the polymer structure. Such voids provide a mechanical response to the final polymer material which parallels that of natural arterial tissue, while at the same time retaining the necessary compatibility characteristics for prosthesis.
Inventors
- 👤 Donald J. Lyman
- 👤 Frank J. Fazzio
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 16:14
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/28; A; A61; A61F; A61F2/00; A61F2/02; A61F2/04; A61F2/06; A61L; A61L27/00; A61L27/14; A61L27/18; B; B29; B29C; B29C67/00; B29C67/02; B29C67/06; C08J2375/00; C08J2375/04
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
225 words
A method of fabricating a prosthesis material for use with a living body, said prosthesis having mechanical properties of compliance and elasticity approximating that of soft body tissue and being operable to preserve surface properties of blood and tissue compatibility, said method comprising the steps (a) preparing a copolyurethane composition having a molecular weight range approximately corresponding to an inherent viscosity of 0.4 to 1.0 as measured in a solution of 0.5% concentration in N,N-dimethylformamide at 30° C.; (b) dissolving an amount of said copolyurethane composition in solvent to produce a dipping solution having 5-12% by weight polymer concentration, said solution having a relative viscosity between the range of 100 to 1000 at a dipping temperature of 10° C. to 60° C.; (c) coating forming means with a uniform thickness of said dipping solution; and (d) precipitating said coating into a stable physical structure having a substantially uniform dispersion of voids throughout the copolyurethane composition by immersing said coated forming means into a precipitating solution comprising a fluid which is miscible in said solvent but operable as a precipitating nonsolvent with respect to the said copolyurethane composition, the precipitation being accomplished by means of a balanced rate of exchange between said solvent and nonsolvent molecules which prevents any substantial shrinkage of said coating during precipitation and fixes said copolyurethane composition in a stable physical structure.
Claim 2
Independent Claim
225 words
A method of fabricating a prosthesis material for use with a living body, said prosthesis having mechanical properties of compliance and elasticity approximating that of soft body tissue and being operable to preserve surface properties of blood and tissue compatibility, said method comprising the steps (a) preparing a copolyurethane composition having a molecular weight range approximately corresponding to an inherent viscosity of 0.4 to 1.0 as measured in a solution of 0.5% concentration in N,N-dimethylformamide at 30° C.; (b) dissolving an amount of said copolyurethane composition in solvent to produce a dipping solution having 5-12% by weight polymer concentration, said solution having a relative viscosity between the range of 100 to 1000 at a dipping temperature of 10° C. to 60° C.; (c) coating forming means with a uniform thickness of said dipping solution; and (d) precipitating said coating into a stable physical structure having a substantially uniform dispersion of voids throughout the copolyurethane composition by immersing said coated forming means into a precipitating solution comprising a fluid which is miscible in said solvent but operable as a precipitating nonsolvent with respect to the said copolyurethane composition, the precipitation being accomplished by means of a balanced rate of exchange between said solvent and nonsolvent molecules which prevents any substantial shrinkage of said coating during precipitation and fixes said copolyurethane composition in a stable physical structure.
Claim 3
Dependent Claim
23 words
A method as defined in claim 1 wherein the selected block copolymer is taken from the group consisting of copolyether-urethanes and copolyether-urethane ureas.
Claim 4
Dependent Claim
22 words
A method as defined in claim 1, wherein the solvent is selected from the group consisting of sulfoxide solvents and amide solvents.
Claim 5
Dependent Claim
21 words
A method as defined in claim 3 wherein the solvent is selected from the group consisting of dimethyl sulfoxide and N,N-dimethylformamide.
Claim 6
Dependent Claim
15 words
A method as defined in claim 1 wherein the precipitating nonsolvent is H 2 O.
Claim 7
Dependent Claim
46 words
A method as defined in claim 1, wherein the precipitating step is regulated by controlling the rate of exchange between said solvent and nonsolvent molecules by adding rate impeding constituents to the polymer solution of step b or to the nonsolvent material of the precipitating step.
Claim 8
Dependent Claim
25 words
A process as defined in claim 6 wherein said rate impeding constituents are selected from the group consisting of polyethylene glycols, ketones and inorganic salts.
Claim 9
Dependent Claim
17 words
A method as defined in claim 1, wherein an additional step comprises drying the precipitated copolyurethane composition.
Claim 10
Dependent Claim
33 words
A blood and tissue compatible, synthetic prothesis material prepared in accordance with the method defined in claim 1, wherein said material has mechanical properties of compliance and elasticity approximating those of organic tissue.
Claim 11
Dependent Claim
20 words
A product as defined in claim 9, wherein the copolyurethane is selected from the group comprising copolyether-urethanes and copolyether-urethane ureas.
Claim 12
Dependent Claim
17 words
A prosthesis material as defined in claim 9, wherein the material is configured as a nerve cuff.
Claim 13
Dependent Claim
25 words
A prosthesis material as defined in claim 9, wherein the material is formed in a sheet structure suitable for protective or prosthesis application for skin.
Claim 14
Dependent Claim
13 words
A prosthesis duct formed in accordance with the method defined in claim 1.
Claim 15
Dependent Claim
31 words
A prosthesis duct as defined in claim 13, wherein the duct is adapted for replacement of human tissue selected from the group consisting of urethra, ureta and common bile duct tissue.
Claim 16
Dependent Claim
18 words
A prosthesis duct as defined in claim 13 having an inner diameter of approximately 6 mm or less.
Claim 17
Dependent Claim
13 words
A vascular graft formed in accordance with the method defined in claim 1.
Claim 18
Dependent Claim
20 words
A vascular graft as defined in claim 16, wherein the graft has an inner diameter of 6 mm or less.
Claim 19
Dependent Claim
47 words
A process for replacing soft body tissue comprising the steps of: (a) Preparing prosthesis material fabricated in accordance with the method of claim 1, and (b) applying said material to a portion of a living body to form an integral combination of prosthesis material and living tissue.
Claim 20
Dependent Claim
22 words
A process as defined in claim 18, wherein the prosthesis material is formed in a structure substantially equivalent to natural vascular tissue.
Claim 21
Dependent Claim
22 words
A process as defined in claim 19, wherein the prosthesis material is sutured to natural vascular tissue to form a continuation thereof.
Claim 22
Dependent Claim
25 words
A process as defined in claim 18, wherein the prothesis material is structured in duct configuration substantially equivalent to duct tissue of a living body.
Claim 23
Dependent Claim
27 words
A process as defined in claim 21, wherein the prosthesis material is attached to form part of a ureta, urethra or bile duct within a living body.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-11-05 | 1983-05-07 | 1983-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-11-05 | 1987-05-07 | 1987-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-11-05 | 1991-05-07 | 1991-11-06 | $7700.00 | Window Closed / Lapsed |