Atherectomy catheter

• US 5,669,920 A
• Filed: 03/20/1996
• Issued: 09/23/1997
• Est. Priority Date: 07/09/1993
• Status: Expired due to Term

• Current Assignee: Advanced Cardiovascular Systems Incorporated
• Original Assignee: Devices for Vascular Intervention, Inc.
• Inventors: Conley, Daniel J., Andreas, Bernard H., Dell, Kent D., Deem, Mark E.
• Primary Examiner(s): Buiz, Michael
• Assistant Examiner(s): TRUONG, KEVIN THAO
• Application Number:
  US08/618,943
• Time in Patent Office: 552 Days
• Field of Search: 606/159, 606/171, 606/180, 128/898, 604/22, 604/282
• US Class Current: 606/159
• CPC Class Codes: A61B 17/320783 through side-hole, e.g. sliding or rotating cutter inside catheter
• CPC Class Codes: A61B 2017/22069 Immobilising; Stabilising
• CPC Class Codes: A61M 25/0009 Making of catheters or other medical or surgical tubes
• CPC Class Codes: A61M 25/0012 with embedded structures, e.g. coils, braids, meshes, strands or radiopaque coils
• CPC Class Codes: A61M 25/005 with embedded materials for reinforcement, e.g. wires, coils, braids
• CPC Class Codes: A61M 25/0053 having a variable stiffness along the longitudinal axis, e.g. by varying the pitch of the coil or braid

Abstract

An improved atherectomy catheter and methods of making and using a catheter are disclosed. In one embodiment, the catheter comprises a housing shaft having a torsionally-reinforced outer layer concentrically disposed over a polymeric inner layer, with an inflation tube disposed concentrically over the housing shaft to define an annular inflation lumen. A housing is attached to the distal end of the housing shaft, and may contain interventional means such as a cutting blade. The balloon for urging the housing against a vessel wall, such as a balloon, is attached to the housing opposite the interventional means and is in communication with the inflation lumen. A drive shaft may be rotatably disposed through a longitudinal lumen in the housing shaft, the drive shaft being coupled at its distal end to the interventional balloon. The method of the invention facilitates construction of a catheter shaft through the steps of forming a flexible tubular polymeric outer layer with a first melting point over a tubular polymeric inner layer with a second melting point, the first melting point being lower than the second melting point; heating the outer layer to at least the first melting point and less than the second melting point, and impregnating a wire braid into the outer layer up to the inner layer. In a preferred embodiment, the inner layer is a fluorocarbon polymer, and the outer layer is a thermoplastic elastomer which is stable near body temperatures, impregnated with one or more layers of a stainless steel wire braid.

Claims

1. A method of making a catheter, the method comprising:

providing a tubular inner layer of a first polymer having a first melting point;

forming over the inner layer an outer layer of a second polymer having a second melting point, the second melting point being lower than the first melting point;

heating the outer layer to a temperature of at least the second melting point and less than the first melting point; and

impregnating the outer layer with a wire braid such that the braid penetrates the outer layer to the inner layer.

2. A method as in claim 1 wherein the first melting point is between 500°

F. and 800°

F. and the second melting point is between 200°

F. and 500°

F.

3. A method as in claim 1 wherein the inner layer has a coefficient of friction between 0 and 0.4.

4. A method as in claim 1 wherein the inner layer comprises a fluorocarbon polymer.

5. A method as in claim 1 wherein the outer layer comprises a polyether-amide block copolymer or polyether-amide block copolymer/polyamide blend.

6. A method as in claim 1 wherein the wire braid is stainless steel.

7. A method as in claim 1 further comprising extruding said inner layer before said forming step.

8. A method as in claim 1 wherein the outer layer is formed by extrusion over the inner layer.

9. A method as in claim 1 further comprising:

reheating the outer layer to at least the second melting point; and

impregnating the outer layer with a second wire braid.

10. A method as in claim 1 further comprising roughening an outer surface of said inner layer before said step of forming to improve adhesion with said outer layer.

11. A method as in claim 10 wherein said roughening is performed by chemically etching said outer surface.

12. A method as in claim 1 further comprising passing the inner and outer layers through a heated die for sizing and surface finishing.

13. A catheter formed by the method of:

providing a tubular inner layer of a first polymer having a first melting point;

forming over the inner layer an outer layer of a second polymer having a second melting point, the second melting point being lower than the first melting point;

heating the outer layer to a temperature of at least the second melting point and less than the first melting point; and

embedding the outer layer with a wire braid such that the braid penetrates the outer layer to the inner layer.

14. A catheter as in claim 13 wherein the first melting point is between 500°

F. and 800°

F. and the second melting point is between 200°

F. and 500°

F.

15. A catheter as in claim 13 wherein the inner layer has a coefficient of friction between 0 and 0.4.

16. A catheter as in claim 13 wherein the inner layer comprises a fluorocarbon polymer.

17. A catheter as in claim 13 wherein the outer layer comprises a polyether-amide block copolymer or polyether-amide block copolymer/polyamide blend.

18. A catheter as in claim 13 wherein the wire braid is stainless steel.

19. A catheter as in claim 13 wherein said method further comprises extruding said inner layer before said forming step.

20. A catheter as in claim 13 wherein the outer layer is formed by extrusion over the first layer.

21. A catheter as in claim 13 wherein the method further comprises:

reheating the outer layer to at least the second melting point; and

impregnating the outer layer with a second wire braid.

22. A catheter as in claim 13 wherein the method further comprises passing the inner and outer layers through a heated die for sizing and surface finishing.

23. A catheter as in claim 13 wherein said inner and outer layers form a housing shaft of said catheter, the housing shaft having proximal and distal ends and a lumen therebetween, the catheter further comprising a housing attached to the distal end of the housing shaft.

24. A catheter as in claim 23 further comprising an inflation tube disposed concentrically about the housing shaft defining an annular lumen, means mounted to a side of the housing for urging the housing against a vessel wall, and a transition tube disposed about a distal portion of the housing shaft and having a proximal end secured to a distal end of the inflation tube and a distal end connected to the urging means, wherein the transition tube has a transition lumen connecting the annular lumen to the urging means.

25. A catheter as in claim 24 wherein the transition lumen is formed by placing a mandril between the transition tube and the housing shaft, heating the transition tube so as to melt a portion of the transition tube into the housing shaft and removing the mandril so as to leave an axial passage comprising the transition lumen.

26. A catheter as in claim 24 wherein the urging means comprises a balloon having a leg extending into the transition lumen, the catheter further comprising at least one polymeric anchor ring in the transition tube disposed about the balloon leg and the housing shaft for providing strain relief support.

27. A catheter as in claim 13 wherein said inner and outer layers form an inflation tube of said catheter, the inflation tube having proximal and distal ends and a lumen therebetween, the catheter further comprising a balloon at a distal end thereof in communication with said lumen.

28. A catheter as in claim 13 wherein said inner and outer layers form a drive shaft of said catheter, the drive shaft having proximal and distal ends, the catheter further comprising a cutting blade coupled to the distal end of the drive shaft.

29. A shaft for a catheter, the shaft comprising:

an unreinforced inner layer of a first polymer having a first melting point, said inner layer defining a longitudinal lumen; and

a torsionally reinforced outer layer of a second polymer having a second melting point, the outer layer fixed concentrically about the inner layer, wherein the first melting point is higher than the second melting point.

30. A shaft as in claim 29 wherein the first melting point is between 500°

F. and 800°

F. and the second melting point is between 200°

F. and 500°

F.

31. A shaft as in claim 29 wherein the first polymer has a coefficient of friction between 0 and 0.4.

32. A shaft as in claim 29 wherein the outer layer is embedded with a wire braid.

33. A shaft as in claim 29 wherein the inner layer is polytetrafluoroethylene or fluorinated ethylene-propylene.