Variable stiffness electrically conductive composite, resistive heating catheter shaft

• US 6,562,021 B1
• Filed: 06/30/2000
• Issued: 05/13/2003
• Est. Priority Date: 12/22/1997
• Status: Expired due to Term

• Current Assignee: Micrus Corporation (Johnson & Johnson)
• Original Assignee: Micrus Corporation (Johnson & Johnson)
• Inventors: Derbin, J. Todd, Ferrera, David A.
• Primary Examiner(s): Walberg, Teresa
• Assistant Examiner(s): Fastovsky, Leonid M
• Application Number:
  US09/608,497
• Time in Patent Office: 1,047 Days
• Field of Search: 385/115, 385/123, 604/524, 604/282, 604/280, 604/527, 606/15, 606/7, 128/658
• US Class Current: 604/523
• CPC Class Codes: A61B 18/14 Probes or electrodes therefor
• CPC Class Codes: A61B 18/24 with a catheter A61B18/26, A61B18/28 take precedence
• CPC Class Codes: A61M 25/0009 Making of catheters or other medical or surgical tubes
• CPC Class Codes: A61M 25/0045 multi-layered, e.g. coated coating materials A61L29/08
• CPC Class Codes: A61M 25/0054 with regions for increasing flexibility
• CPC Class Codes: G02B 23/26 using light guides for illumination G02B23/2469
• CPC Class Codes: G02B 6/04 formed by bundles of fibres G02B6/24 takes precedence
• CPC Class Codes: G02B 6/241 Light guide terminations
• CPC Class Codes: G02B 6/3624 Fibre head, e.g. fibre probe termination optical details of light guide terminations G02B6/241; reshaping of light guides G02B6/2552; optical details of coupling light into or out of fibre end G02B6/262
• CPC Class Codes: G02B 6/40 having fibre bundle mating means

Abstract

The variable stiffness electrically conductive catheter shaft includes one or more electrically conductive members, and at least one coaxial layer of heat shrink polymer disposed over the one or more electrically conductive members of a length shorter than the one or more electrically conductive members, to provide variations in stiffness along the length of the shaft. The variable stiffness electrically conductive catheter shaft preferably includes a plurality of coaxial layers of heat shrink polymer encapsulating the one or more electrically conductive members, extending from the proximal end of the one or more electrically conductive members toward the distal end, the plurality of coaxial layers having different lengths to provide the electrically conductive catheter shaft with varying stiffness over the length of the electrically conductive catheter shaft.

Claims

1. A variable stiffness electrically conductive catheter shaft for use in interventional therapy, comprising:

at least one electrically conductive member having a proximal end and a distal end, and

at least one coaxial sheath over said at least one electrically conductive member, said sheath having a tapering thickness over its length to provide variations in stiffness along the length of the shaft.

2. The variable stiffness electrically conductive catheter shaft of claim 1, wherein said coaxial sheath comprises a plurality of coaxial layers of heat shrink polymer encapsulating said at least one electrically conductive member, said layers extending from the proximal end of said at least one electrically conductive member toward the distal end, the plurality of coaxial layers having different lengths to provide said electrically conductive catheter shaft with varying stiffness over the length of the electrically conductive catheter shaft.

3. The variable stiffness electrically conductive catheter shaft of claim 1 wherein said sheath includes a plurality of layers applied to said at least one electrically conductive member, said layers being of different stiffness from one another and partially overlapping one another to thereby provide variable stiffness to the shaft along its length while maintaining a desired outside shaft diameter along its length.

4. The variable stiffness electrically conductive catheter shaft of claim 1 wherein said sheath further comprises a plurality of fibers woven about said at least one electrically conductive member in a lengthwise fashion to provide variable stiffness along said shaft.

5. The variable stiffness electrically conductive catheter shaft of claim 4 wherein said woven fibers are wound in a helical pattern about said at least one electrically conductive member.

6. The variable stiffness electrically conductive catheter shaft of claim 2, wherein said coaxial sheath further comprises the coaxial layers being arranged so that the shortest layer is closest to said at least one electrically conductive member and the longest layer is the outer layer to thereby present a smooth outer surface to the assembled variable stiffness electrically conductive catheter shaft.

7. The variable stiffness electrically conductive catheter shaft of claim 1 wherein said coaxial sheath comprises a metal hypo tube bonded to said at least one electrically conductive member over at least a portion of its length.

8. The variable stiffness electrically conductive catheter shaft of claim 7 wherein said hypo tube is tapered along its length.

9. The variable stiffness electrically conductive catheter shaft of claim 1 wherein said at least one electrically conductive member comprises a pair of electrically conductive wires.

18. The variable stiffness electrically conductive catheter shaft of claim 9 wherein said catheter shaft comprises a pair of electrically conductive wires.

10. A variable stiffness catheter shaft for use in interventional therapy comprising:

a catheter shaft used to conduct electrical energy to a remote location, said catheter shaft having a distal end and a proximal end;

at least one sheath extending longitudinally over the catheter shaft from the proximal end to a predetermined point near the distal end of said shaft, said at least one sheath tapered to have a varying stiffness over its length;

whereby the combination of said sheath and said catheter shaft comprises a composite catheter shaft displaying variations of stiffness at predetermined positions along its length from the proximal end to the distal end of said shaft.

11. The variable stiffness catheter shaft of claim 10 wherein said sheath is formed of a plurality of coaxial layers of polymer material, said coaxial layers terminating at different points along the length of said catheter shaft to thereby provide variations in stiffness of said shaft along its length.

12. The variable stiffness catheter shaft of claim 10 wherein said sheath comprises at least two lengths of material having a stiffness different from one another arranged end to end and attached at their ends, both layers being coaxial with said catheter shaft.

13. The variable stiffness catheter shaft of claim 12, further comprising an additional outer layer of material to encapsulate said coaxial sheaths.

14. The variable stiffness catheter shaft of claim 10, said sheath further comprising:

strengthening fibers wound about said catheter shaft to thereby provide increased stiffness to said shaft at predetermined positions along said shaft; and

a smooth outer cover formed over said fibers.

15. The variable stiffness catheter shaft claim 10 wherein said sheath comprises a hypo tube adhesively bonded to the exterior of said catheter shaft.

16. The variable stiffness catheter shaft of claim 11 wherein said hypo tube is tapered along its length.

17. The variable stiffness catheter shaft of claim 14 wherein said strengthening fibers are embedded in a resilient plastic material formed around said catheter shaft.

19. A variable stiffness electrically conductive catheter shaft comprising:

at least one electrically conductive member;

a plurality of layers of heat shrink polymer shrunk over said at least one electrically conductive member and coaxial therewith, said layers extending from the proximal end of said at least one electrically conductive member and terminating at different distances between said proximal end and said distal end; and

an outer sheath of shrink wrap material shrunk over said at least one electrically conductive member and said plurality of layers of heat shrink material to thereby construct a tapered composite electrically conductive catheter shaft displaying a stiffness which varies over the length of the shaft.

20. The variable stiffness electrically conductive catheter shaft of claim 19 wherein said at least one electrically conductive member comprises a pair of electrically conductive wires.

21. A method of constructing a variable stiffness electrically conductive catheter shaft comprising the steps of shrinking a first layer of heat shrink material over at least one electrically conductive member, said layer of heat shrink material being of a first length shorter than said at least one electrically conductive member;

shrinking a second layer of heat shrink material over said electrically conductive catheter shaft, said second layer of heat shrink material extending from the proximal end of said shaft towards the distal end of said shaft and terminating in a position different from the termination point of said first layer; and

forming a third layer of material over said previously formed layers of said electrically conductive catheter shaft to provide a smoothly tapered exterior sheath over said shaft.

22. A method for forming a variable stiffness electrically conductive catheter shaft comprising;

passing at least one electrically conductive member at a predetermined speed through a first die which deposits a first polymer;

passing said shaft upon which said first polymer has been deposited thereafter through a second die which deposits a second polymer; and

quenching the resultant shaft to provide a desired amount of stiffness along the length of said shaft.

23. The method of claim 22 wherein said method further comprises quenching the composite shaft after it emerges from the first die to thereby cool the first polymer deposited thereon.

24. A method of constructing a composite electrically conductive catheter shaft comprising the steps of:

winding about a catheter shaft including at least one electrically conductive member in a lengthwise fashion a helical strand of strengthening material;

depositing a matrix about said strand in a predetermined position against said shaft; and

forming an outer sheath to encapsulate said strands of said matrix and provide a smooth exterior shaped composite shaft.

25. A method of forming a composite electrically conductive catheter shaft with variable stiffness comprising;

depositing on at least one electrically conductive member a buffer layer external to a electrical insulation layer on said at least one electrically conductive member; and

centerless grinding said buffer layer to produce therein a taper in said buffer layer along the length of said shaft to thereby provide a variable stiffness to said at least one electrically conductive member.

26. A method of constructing an electrically conductive catheter shaft comprising:

forming a hypo tube;

grinding at least one taper into said hypo tube along its length; and

adhesively attaching said hypo tube to at least one electrically conductive member extending therethrough, to thereby provide a composite shaft with variable stiffness along its length.

27. A method of constructing a composite electrically conductive catheter shaft comprising:

passing at least one electrically conductive member at a first predetermined speed through a first die connected to a source of a first polymer to thereby deposit on said at least one electrically conductive member a predetermined thickness of said first polymer;

varying the speed of said at least one electrically conductive member through said first die to thereby vary the thickness of said first polymer deposited on said at least one electrically conductive member;

passing said at least one electrically conductive member at a second predetermined speed through a second die connected to a source of a second polymer to thereby deposit on said at least one electrically conductive member a predetermined thickness of said second polymer; and

varying the speed of said at least one electrically conductive member through said second die to thereby vary the thickness of said second polymer deposited on said at least one electrically conductive member.

28. The method of claim 27, further comprising the step of:

quenching the surface of said first polymer after it is deposited by said first die.

29. The method of claim 27, further comprising the step of:

varying the thickness of said second polymer to provide a constant overall diameter of said composite shaft.