ELECTROSPUN MATERIAL COVERED MEDICAL APPLIANCES AND METHODS OF MANUFACTURE

• US 20140081414A1
• Filed: 03/14/2013
• Published: 03/20/2014
• Est. Priority Date: 09/19/2012
• Status: Active Grant

• Current Assignee: Merit Medical Systems, Inc.
• Original Assignee: Merit Medical Systems, Inc.
• Inventors: Hall, John William, Dolmatch, Bart, Eller, Zeke, Kellar, Robert S., Simmons, Rachel Lynn, Mower, Wayne L.
• Granted Patent: US 10,507,268 B2
• Time in Patent Office: Days
• US Class Current: 623/23.7
• CPC Class Codes: A61F 2/07 Stent-grafts
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• CPC Class Codes: A61F 2002/30003 Material related properties of the prosthesis or of a coating on the prosthesis
• CPC Class Codes: A61F 2002/3006 Properties of materials and coating materials
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30067 Coating or prosthesis-covering structure made of thermoplastic material
• CPC Class Codes: A61F 2002/30072 Coating made of plastically deformable or self-moulding material
• CPC Class Codes: A61K 9/70 Web, sheet or filament bases ; Films; Fibres of the matrix type containing drug hollow drug-filled fibres A61K9/0092
• CPC Class Codes: A61L 27/16 obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: A61L 27/34 Macromolecular materials
• CPC Class Codes: A61L 27/56 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61L 31/048 obtained by reactions only involving carbon-to-carbon unsaturated bonds A61L31/041 takes precedence
• CPC Class Codes: A61L 31/10 Macromolecular materials
• CPC Class Codes: A61L 31/146 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61L 31/148 Materials at least partially resorbable by the body
• CPC Class Codes: B05D 1/007 using an electrostatic field B05D1/02 - B05D1/16 take precedence
• CPC Class Codes: C08L 27/12 containing fluorine atoms
• CPC Class Codes: C08L 27/18 Homopolymers or copolymers or tetrafluoroethene
• CPC Class Codes: D01D 5/0076 characterised by the collecting device, e.g. drum, wheel, endless belt, plate or grid D01D5/0046 takes precedence
• CPC Class Codes: D01F 6/12 from polymers of fluorinated hydrocarbons
• CPC Class Codes: D04H 1/728 : by electro-spinning electro-spinning methods and apparatus D01D5/0007
• CPC Class Codes: D04H 3/073 : Hollow cylinder shaped

Abstract

A medical appliance or prosthesis may comprise one or more layers of electrospun nanofibers, including electrospun polymers. The electrospun material may comprise layers including layers of polytetrafluoroethylene (PTFE). Electrospun nanofiber mats of certain porosities may permit tissue ingrowth into or attachment to the prosthesis.

Claims

1. A medical appliance, comprising:

a first layer of electrospun polytetrafluoroethylene (PTFE), having an average percent porosity between about 30% and about 80%.

2. The medical appliance of claim 1, wherein the medical appliance further comprises a second layer of electrospun PTFE, wherein the first layer of electrospun PTFE is disposed such that it defines a first surface of the medical appliance and the second layer of electrospun PTFE is disposed such that it defines a second surface of the medical appliance.

3. The medical appliance of claim 2, wherein the first layer of electrospun PTFE has an average pore size configured to permit tissue ingrowth on the first surface of the medical appliance.

4. The medical appliance of claim 2, wherein the second layer of electrospun PTFE has an average percent porosity of about 50% or less.

5. The medical appliance of claim 2, wherein the second layer of electrospun PTFE has an average pore size configured to resist tissue ingrowth into or through the second surface of the medical appliance.

6. The medical appliance of claim 2, further comprising a tie layer disposed between the first layer of electrospun PTFE and the second layer of electrospun PTFE, wherein the tie layer is configured to inhibit tissue or fluid migration into or through the tie layer.

7. The medical appliance of claim 6, wherein the tie layer comprises PTFE.

8. The medical appliance of claim 6, wherein the tie layer is fluorinated ethylene propylene (FEP).

9. The medical appliance of claim 8, wherein the FEP partially bonds to fibers of the first and second layers of electrospun PTFE.

10. The medical appliance of claim 9, wherein the FEP flows into and coats the fibers of the first and second layers of electrospun PTFE while maintaining the porosity of the layers.

11. The medical appliance of claim 5, wherein at least one of the first and second layers of electrospun PTFE have been heated and stretched after sintering.

12. The medical appliance of claim 1, further comprising a reinforcing layer of electrospun PTFE, the reinforcing layer having greater tensile strength in a first direction of the layer than in a second direction perpendicular to the first direction.

13. The medical appliance of claim 12, wherein the medical appliance comprises a tubular construct.

14. The medical appliance of claim 13, wherein the reinforcing layer comprises a tube disposed such that the first direction is in the axial direction of the tubular construct.

15. The medical appliance of claim 13, wherein the reinforcing layer comprises a strip wrapped helically around a portion of the tubular construct.

16. The medical appliance of claim 15, wherein the medical appliance has increased resistance to creep in the radial direction as compared to the axial direction.

17. A stent, comprising:

a frame configured to resist radial compression when disposed in a lumen of a patient, and

a covering disposed on at least a portion of the scaffolding structure, the covering comprising a first layer of electrospun polytetrafluoroethylene (PTFE), the first layer having a percent porosity between about 30% and about 80%.

18. The stent of claim 17, wherein the stent further comprises a second layer of electrospun PTFE, wherein the stent is generally tubular in shape and the first layer of electrospun PTFE is disposed such that it defines an inside surface of the stent and the second layer of electrospun PTFE is disposed such that it defines an outside surface of the stent.

19. The stent of claim 18, wherein the first layer of electrospun PTFE has an average pore size configured to permit tissue ingrowth on the inside surface of the stent.

20. The stent of claim 18, wherein the second layer of electrospun PTFE has an average percent porosity of about 50% or less.

21. The stent of claim 18, wherein the second layer of electrospun PTFE has an average pore size configured to resist tissue ingrowth into or through the second layer of electrospun PTFE.

22. The stent of claim 18, further comprising a tie layer disposed between the first layer of electrospun PTFE and the second layer of electrospun PTFE, wherein the tie layer is configured to inhibit tissue or fluid migration into or through the tie layer.

23. The stent of claim 22, wherein the tie layer is fluorinated ethylene propylene (FEP).

24. The stent of claim 23, wherein the second layer of electrospun PTFE material is configured to permit tissue ingrowth into the second layer to reduce device migration.

25. The stent of claim 17, further comprising a main lumen extending to a bifurcation and two branch lumens extending from the bifurcation.

26. A method of constructing a medical appliance, comprising:

electrospinning a first tube of polytetrafluoroethylene (PTFE) onto a mandrel, the first tube having a percent porosity between about 30% and about 80%, and

sintering the first tube.

27. The method of claim 26, wherein the first tube of PTFE is electrospun onto a rotating mandrel.

28. The method of claim 26, further comprising applying a second tube of electrospun PTFE around the first layer.

29. The method of claim 28, further comprising:

applying a scaffolding structure around the first tube, and

applying a fluorinated ethylene propylene (FEP) layer around the first tube and the scaffolding structure, prior to applying the second tube of electrospun PTFE.

30. The method of claim 29, further comprising heating the medical appliance such that the FEP layer bonds to the first and second tubes.

31. The method of claim 28, further comprising applying a compressive wrap around the second tube before the medical appliance is heat treated.

32. The method of claim 26, wherein electrospinning the first tube of PTFE comprises:

mixing a PTFE dispersion with polyethylene oxide (PEO), wherein the PEO is dissolved in water to form a mixture; and

discharging the mixture from an orifice onto the rotating mandrel.

33. A tubular vascular prosthesis comprising:

a porous inner layer,

a porous outer layer, and

a substantially non-porous tie layer disposed between the inner layer and the outer layer, the tie layer substantially impervious to tissue or fluid migration into or through the tie layer, wherein at least one of the inner layer and the outer layer comprises an electrospun material.

34. The prosthesis of claim 33, wherein the inner and outer layers are configured to permit cellular ingrowth.