Flexible composite drive shaft for transmitting torque

• US 5,816,923 A
• Filed: 02/26/1996
• Issued: 10/06/1998
• Est. Priority Date: 12/09/1993
• Status: Expired due to Term

• Current Assignee: Advanced Cardiovascular Systems Incorporated
• Original Assignee: Devices for Vascular Intervention, Inc.
• Inventors: Webler, William Earl, Milo, Charles, Co, Fred Henrik
• Primary Examiner(s): Walsh, Donald P.
• Assistant Examiner(s): RIVERA, WILLIAM ARAUZ
• Application Number:
  US08/606,678
• Time in Patent Office: 953 Days
• Field of Search: 464/902, 464/58, 464/57, 464/173, 464/174, 74/502.5
• US Class Current: 464/58
• CPC Class Codes: A61B 17/320758 with a rotating cutting instrument, e.g. motor driven A61B17/320725, A61B17/32075 and A61B17/320783 take precedence; for removing intra-ocular material A61F9/00763; endoscopic rotatable cutting instruments A61B17/32002
• CPC Class Codes: A61F 2002/30092 using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2210/0014 using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: F16C 1/02 for conveying rotary movements
• CPC Class Codes: F16C 2202/28 Shape memory material
• CPC Class Codes: F16C 2316/10 in medical appliances, e.g. in diagnosis, dentistry, instruments, prostheses, medical imaging appliances
• CPC Class Codes: Y10S 464/902 Particular material

Abstract

A flexible composite drive shaft used with a flexible vascular atherectomy catheter for connecting a proximal rotating drive member and a distal rotatable working member. The flexible composite drive shaft includes a core of specially selected highly elastic shape memory alloy surrounded by a flexible torsional reinforcing helical wound member and a covering of a smooth polymeric material penetrating the interstices between the wound member and the outer surface of the core. The material of the core, the relative winding direction of the reinforcing member and the direction of angular offset between the reinforcing member and the core are selected to optimize the consistency of the rotational characteristics of the drive shaft in use. The cooperation between the shape memory elastic core, the helical reinforcing member and the interpenetrating polymer provides a composite drive shaft which has improved resistance to kinking and binding failure while traversing tight radii, narrow blood vessel pathways during axial translation and high speed rotational operation.

Claims

1. A composite drive shaft, adapted for use with a biological catheter, comprising:

an elongated core made from a shape memory alloy, the core having a proximal and a distal end and defining a cylindrical substrate having an outer surface, the core extending from a proximal end of the drive shaft through at least a substantial portion of the drive shaft, the core being rotatable; and

a reinforcing member for reinforcing the torsional strength of the composite drive shaft, the reinforcing member surrounding the core and extending from the proximal end of the core to at least the distal end of the core, the member having a first end attached to one end of the core at a first attachment point and the other end attached to the opposite end of the core at a second attachment point, the reinforcing member contracts to contact the core in response to rotation of the core to reinforce the core.

2. A composite drive shaft as set forth in claim 1, wherein the shape memory alloy core is fabricated from an alloy selected from the group of a first alloy consisting essentially of nickel-titanium;

a second alloy consisting essentially of copper-zinc-aluminum; and

a third alloy consisting essentially of copper-aluminum-nickel.

3. A composite drive shaft as set forth in claim 1, wherein the reinforcing member is a helical wound member wrapped around the outer surface of the core, the helical wound member comprised of at least one filamentary element.

4. A composite drive shaft as set forth in claim 1, having a polymeric coating surrounding the reinforcing member and the core.

5. A composite drive shaft as set forth in claim 1, wherein the core and the reinforcing member define interstices therebetween, and wherein a polymeric coating surrounds the reinforcing member and penetrates the interstices,

whereby coupling forces between the core and the reinforcing member are substantially uniformly distributed.

6. A composite drive shaft as set forth in claim 1, wherein the reinforcing member is a double wound member comprising a first helical wound member and an oppositely wound second helical member, wherein the first helical wound member comprises at least one first filamentary element adjacent to the outer surface of the core and having a first winding direction, and the second helical wound member comprises at least one second filamentary element defining a second winding direction;

and wherein the second helical wound member is disposed on the outside of the first helical wound member.

7. A composite drive shaft as set forth in claim 1, wherein the reinforcing member is comprised of a first helical wound member intertwined and braided with a second helical wound member;

wherein the first helical wound member is comprised of at least one first filamentary element wound in a first winding direction;

wherein the second helical wound member is comprised of at least one second filamentary element wound in a second, opposite winding direction; and

wherein the intertwined and braided helical wound members are disposed between the outer surface of the core and the polymeric coating.

8. A composite drive shaft as set forth in claim 1, wherein the end of the core and the end of the reinforcing member opposite to the first attachment point are angularly displaced relative to the first attachment point and in relative opposition to each other prior to forming the second attachment at the second attachment point whereby the core member and reinforcing member are preloaded with opposed torsional strain.

9. A composite drive shaft as set forth in claim 8, wherein the preloaded torsional strain in the core is substantially equal to the beginning of a first superelastic region of the core in a first direction of angular displacement, whereby a torsional load placed in opposition to the preloaded strain will cause the core to traverse the full span of elastic strain from the first superelastic region to a second superelastic region in a second rotational direction opposite to the first direction of angular displacement.

10. A composite drive shaft as set forth in claim 1, wherein the core extends the full length of the drive shaft.

11. A composite drive shaft as set forth in claim 1, wherein the core extends approximately 2/3 the length of the drive shaft from the proximal end of the shaft.

12. A composite drive shaft as set forth in claim 1, wherein the composite drive shaft has a polymeric coating and defines interstices between the core and the reinforcing member, the polymeric coating penetrates interstices between the reinforcing member and the core and makes contact with the reinforcing member and the outer surface of the core to evenly distribute coupling forces between the core and the reinforcing member.

13. A composite drive shaft, adapted for use with a biological catheter, comprising:

an elongated core made of a shape memory alloy, the core having a proximal and a distal end and defining a cylindrical substrate having an outer surface, the core extending from a proximal end of the drive shaft through at least a substantial portion of the drive shaft; and

a reinforcing member for reinforcing the torsional strength of the composite drive shaft having an inner surface in contact with the outer surface of the core, the reinforcing member surrounding the core and extending from the proximal end of the composite drive shaft to the distal end of the composite drive shaft, the reinforcing member having a first end attached to one end of the core at a first attachment point and the other end attached to the opposite end of the core at a second attachment point, the reinforcing member squeezes the elongated core in response to rotation of the drive shaft,

whereby the drive shaft rotates and the reinforcing member contracts against the core reinforces the torsional strength of the core.

14. A composite drive shaft as set forth in claim 13, wherein the shape memory alloy core is selected from the group consisting of a first alloy constituting essentially nickel-titanium, a second alloy constituting essentially copper-zinc-aluminum and a third alloy constituting essentially copper-aluminum-nickel.

15. A composite drive shaft as set forth in claim 13, wherein the reinforcing member is a helical wound member wrapped around the outer surface of the core, the helical wound member comprised of at least one filamentary element.

16. A composite drive shaft as set forth in claim 13, having a polymeric coating surrounding the reinforcing member and the core.

17. A composite drive shaft as set forth in claim 13, having a polymeric coating surrounding and penetrating the reinforcing member, wherein the polymeric coating impregnates interstices between the core and reinforcing member,

whereby coupling forces between the core and the reinforcing member are more uniformly distributed.

18. A composite drive shaft as set forth in claim 13, wherein the reinforcing member is a double wound member comprising a first helical wound member and an oppositely wound second helical member, wherein the first helical wound member is comprised of at least one first filamentary element adjacent to the outer surface of the core and having a first winding direction, and the second helical wound member is comprised of at least one second filamentary element defining a second winding direction;

wherein the second helical wound member is disposed on the outside of the first helical wound member.

19. A composite drive shaft as set forth in claim 13, wherein the reinforcing member is comprised of a first helical wound member intertwined and braided with a second helical wound member;

wherein the first helical wound member is comprised of at least one first filamentary element wound in a first winding direction;

wherein the second helical wound member is comprised of at least one second filamentary element wound in a second, opposite winding direction; and

wherein the intertwined and braided helical wound members are disposed on the outer surface of the core.

20. A composite drive shaft as set forth in claim 13, wherein the end of the core and the end of the reinforcing member opposite to the first attachment point are angularly displaced relative to the first attachment point and in relative opposition to each other prior to forming the second attachment at the second attachment point whereby the core member and reinforcing member are preloaded with opposed torsional strain.

21. A composite drive shaft as set forth in claim 20, wherein the preloaded torsional strain in the core is substantially equal to the beginning of a first superelastic region of the core in a first direction of angular displacement, whereby a torsional load placed in opposition to the preloaded stain will cause the core to traverse the full span of elastic strain from the first superelastic region to a second superelastic region in a second rotational direction opposite to the first direction of angular displacement.

22. A composite drive shaft as set forth in claim 13, wherein the core extends the full length of the drive shaft.

23. A composite drive shaft as set forth in claim 13, wherein the core extends approximately 2/3 the length of the drive shaft from the proximal end of the shaft.

24. A composite drive shaft as set forth in any one of claims 13 wherein the shape memory alloy core consists of essentially 50% nickel and 50% titanium.

25. A composite drive shaft for use with a biological catheter having a rotatable work element, comprising:

an elongated core, the core being made of a shape memory alloy defining a cylindrical substrate having an outer surface;

a reinforcing member coupled around the core for reinforcing the torsional strength of the composite drive shaft, the reinforcing member being impregnable by a coating; and

a coating surrounding the reinforcing member and the core to facilitate composite cooperation between the reinforcing member and the core,

the core and the reinforcing member define interstices therebetween which are impregnable by the coating,

whereby the coating impregnates the interstices between the core and reinforcing member and binds the reinforcing member and the core to distribute coupling forces between the core and the reinforcing member.

26. A composite drive shaft as set forth in claim 25, wherein the reinforcing member is preloaded with a torsional load, when the drive shaft rotates, the reinforcing member causes the core to enter a region of stress-strain behavior known as the superelastic region.

27. A composite drive shaft as set forth in claim 25, wherein the core has a first end and second end, the core being preloaded with a torsional load to angularly displace the first end of the core with respect to the second end, when the drive shaft rotates, the angular displacement of each end changes and causes the reinforcing member to squeeze the core to cause the core to enter a region of stress-strain behavior known as the superelastic region.

28. A composite drive shaft as set forth in claim 25, wherein the reinforcing member couples to the outer surface of the cylindrical substrate.

29. A composite drive shaft as set forth in claim 25, wherein the reinforcing member has a first helical wound member and an oppositely wound second helical member, the first helical wound member has at least one first filamentary element adjacent to the outer surface of the core in a first winding direction, and the second helical wound member having at least one second filamentary element defining a second winding direction.

30. A composite drive shaft as set forth in claim 25, wherein the reinforcing member includes a first helical wound member braided with a second helical wound member, the first helical wound member has at least one first filamentary element wound in a first winding direction, the second helical wound member has at least one second filamentary element wound in a second, opposite winding direction, and each helical wound member being disposed on the outer surface of the core.

31. A composite drive shaft as set forth in claim 25, wherein the core has an outside diameter within the range of 0.01 to 0.125 inches.

32. A composite drive shaft as set forth in claim 25, wherein the cylindrical substrate is hollow having a wall with a thickness of between 0.001 to 0.020 inches.

33. A composite drive shaft as set forth in claim 25, wherein the reinforcing member is a helical winding of high strength spring material with a rectangular cross-section having dimensions within the range of 0.001 to 0.01 inches.

34. A composite drive shaft as set forth in claim 25, wherein the coating is a polyethylene sheath having a thickness of about 0.003 inches.

35. A composite drive shaft as set forth in claim 25, wherein the reinforcing member includes a helical spring having two ends, each end of the reinforcing member being attached to the core.