Variable stiffness guidewire

• US 20070149951A1
• Filed: 12/27/2005
• Published: 06/28/2007
• Est. Priority Date: 12/27/2005
• Status: Active Grant

• Current Assignee: Cardinal Health Switzerland 515 GmbH (Cardinal Health, Inc.)
• Original Assignee: Cordis Corporation (Cardinal Health, Inc.)
• Inventors: Hojeibane, Hikmat, Wu, Mina
• Granted Patent: US 7,867,176 B2
• Time in Patent Office: Days
• US Class Current: 604/526
• CPC Class Codes: A61M 2025/09083 having a coil around a core
• CPC Class Codes: A61M 2025/09158 when heated
• CPC Class Codes: A61M 2025/09175 having specific characteristics at the distal tip
• CPC Class Codes: A61M 25/09 Guide wires

Abstract

A guidewire navigable through body vessels of a human subject for delivery of a catheter or the like is provided. The guidewire has a tube which receives a corewire that protrudes beyond a distal portion of the tube. The protruding portion of the corewire is surrounded by a spring and shapeable into a curve or arc. The cross-sectional shape of the spring may be varied in order to promote bending flexibility and curvature or to favor curvature of a chosen type. The corewire is axially movable with respect to the tube, which compresses or stretches the spring to change the stiffness of the spring. The tube has a proximal portion comprised of a relatively rigid material, such as stainless steel, while a distal portion is comprised of a more flexible material, such as a nitinol.

Claims

1. A variable stiffness guidewire for navigating through body vessels, comprising:

a tube having a proximal portion substantially comprised of a first material and a distal portion substantially comprised of a second material, wherein said second material is different from and more flexible at human body temperature than said first material;

an elongated corewire received by the tube and including a distal end, a proximal end, and a protruding portion extending beyond the distal portion of the tube; and

a coiled spring surrounding at least said protruding portion of said corewire, said spring having a distal end associated with said distal end of said corewire and a proximal end associated with said distal portion of said tube, wherein said corewire is axially movable with respect to said tube to adjust the total length of the spring and thus the stiffness of said spring.

2. The guidewire of claim 1, wherein said second material has shape memory properties.

3. The guidewire of claim 1, wherein said second material is a nitinol material.

4. The guidewire of claim 1, wherein said first material is stainless steel and said second material is a nitinol material.

5. The guidewire of claim 4, wherein said distal end of said corewire includes a portion having an increased diameter for contacting said distal portion of said tube to prevent downstream movement of said corewire with respect to said tube.

6. The guidewire of claim 4, wherein said distal end of said spring is connected to and movable with said distal end of said corewire and wherein said proximal end of said spring is connected to and movable with said distal portion of said tube.

7. The guidewire of claim 6, further comprising a separation gap between adjacent coils of said spring and wherein downstream movement of said corewire with respect to said tube generally increases the separation gap to thereby decrease the stiffness of the coil, and wherein upstream movement of said corewire with respect to said tube generally decreases the separation gap to thereby increase the stiffness of the coil.

8. The guidewire of claim 7, wherein said separation gap is variable between approximately 0 inches in a maximum stiffness configuration and approximately 0.010 inch in a minimum stiffness configuration.

9. The guidewire of claim 6, wherein said coil is rotatably connected to at least one of.said distal end of said corewire and said distal portion of said tube.

10. The guidewire of claim 1, further comprising an atraumatic weld associated with said distal end of said corewire.

11. The guidewire of claim 1, further comprising a plurality of corewires receivable by said tube.

12. The guidewire of claim 1, further including a non-rotation system comprising a longitudinal pathway along one of said tube or corewire and a follower on the other of said tube or corewire, said follower being slidable with respect to said pathway.

13. The guidewire of claim 1, wherein at least a portion of said corewire is shapeable.

14. The guidewire of claim 1, wherein at least a portion of said distal portion of said tube is shapeable.

15. The guidewire of claim 1, wherein said spring has a varying pitch.

16. The guidewire of claim 1, further comprising a sheath covering said protruding portion of said corewire.

17. The guidewire of claim 16, wherein said sheath is heat-shrunk over said spring for providing a fluid-tight seal.

18. A coiled spring for use at a distal tip of a medical guidewire having a tube and a corewire received by the tube and protruding from a distal portion of the tube, wherein the spring surrounds a protruding portion of the corewire and comprises:

a length;

a proximal end;

a distal end; and

a plurality of coils having cross-sectional shapes, wherein the cross-sectional shape of at least a portion of one of said coils is substantially flat and the cross-sectional shape of at least a portion of another one of said coils is substantially circular.

19. The spring of claim 18, wherein the stiffness of the spring is variable by changing said length.

20. The spring of claim 19, wherein said length is varied by axially moving the corewire with respect to the tube.

21. The spring of claim 19, wherein said proximal end of the spring is engageable with the distal portion of the tube and said distal end of the spring is engageable with the corewire.

22. The spring of claim 20, wherein the spring allows rotational movement of the corewire with respect to the tube.

23. The spring of claim 18, further comprising a separation gap between adjacent coils, wherein the separation gap is approximately 0 inches in a maximum stiffness configuration and the separation gap is approximately 0.10 inch in a minimum stiffness configuration.

24. The spring of claim 18, wherein the spring has a varying pitch.