Catheters and methods for supporting a guidewire or delivering a radiopaque, diagnostic or therapeutic agent through a vessel stenosis or other tortuous anatomy are disclosed. A catheter can comprise an elongate shaft body and a tip member disposed at a distal end of the shaft body. The shaft body can extend from a proximal end to the distal end and can define an inner lumen. The shaft body can include a liner, a braid member surrounding the liner, a multi-layer coil surrounding the braid member, and a polymer cover surrounding the multi-layer coil. The multi-layer coil can include first and second coil layers wound in opposing directions. An outer surface portion of the polymer cover can include one or more helical threads. In an example, the one or more helical threads are positioned around a distal end portion of the shaft body. The tip member can be made from a metal or a polymer and can also include one or more helical threads around its outer surface.
1. A catheter, comprising:
an elongate shaft body extending from a proximal end to a distal end and defining an inner lumen, the shaft body including a liner, a braid member surrounding the liner, a multi-layer coil surrounding the braid member, and a polymer cover surrounding the multi-layer coil,
the multi-layer coil including a first coil layer and a second coil layer surrounding the first coil layer, a proximal end of each of the first and second coil layers extending from a proximal portion of the shaft body to the shaft body's distal end,
a distal end of each of the liner, the braid member, and the first and second coil layers extending beyond the distal end of the shaft body,
a distal outer surface portion of the polymer cover of the shaft body including one or more helical threads configured to urge movement of the shaft body within vasculature via rotation applied to the shaft body's proximal end; and
a tip member disposed at the distal end of the shaft body.
2. The catheter of claim 1 , wherein the first coil layer is wound in a first direction and the second coil layer is wound in a second direction opposing the first direction.
3. The catheter of claim 2 , wherein the first and second coil layers each include a plurality of wound wires having a fully round cross-section.
4. The catheter of claim 1 , wherein the polymer cover extends inward through voids between successive windings of the multi-layer coil.
5. The catheter of claim 1 , wherein the polymer cover extends inward through voids between successive windings of the multi-layer coil and into voids of the braid member.
6. The catheter of claim 1 , wherein the one or more helical threads include a polymer member wound around the polymer cover.
7. The catheter of claim 6 , wherein the polymer member forming the one or more helical threads has a melting point higher than a melting point of the polymer cover surrounding the multi-layer coil.
8. The catheter of claim 1 , wherein the one or more helical threads include a depression of the outer surface of the polymer cover.
9. The catheter of claim 1 , wherein the tip member includes a metallic tip member.
10. The catheter of claim 9 , wherein an outer surface of the metallic tip member includes one or more helical threads.
11. The catheter of claim 10 , wherein the one or more helical threads of the metallic tip member project radially outward from its outer surface.
12. The catheter of claim 10 , wherein the one or more helical threads of the metallic tip member extend radially inward from its outer surface.
13. The catheter of claim 1 , wherein the tip member includes a polymer tip member.
14. The catheter of claim 13 , wherein the polymer tip member includes a non-tapered proximal portion and a tapered distal portion.
15. The catheter of claim 14 , wherein the distal end of each of the first and second coil layers extends into the non-tapered proximal portion of the polymer tip member.
16. The catheter of claim 1 , wherein a boundary marking the distal end of the shaft body and a proximal end of the tip member is defined by a change in radiopacity, the change in radiopacity due to a material of the tip member having greater radiopacity than any material proximal of the tip member.
17. The catheter of claim 1 , wherein the second coil layer is in contact with the first coil layer such that the first and second coil layers interlock when the rotation is applied to the shaft body's proximal end.
18. A catheter, comprising:
an elongate shaft body extending from a proximal end to a distal end and defining an inner lumen, the shaft body including a liner, a braid member surrounding the liner, a multi-layer coil surrounding the braid member, and a polymer cover surrounding the multi-layer coil,
the multi-layer coil including a first coil layer wound in a first direction and a second coil layer wound in a second direction opposing the first direction and surrounding the first coil layer, a proximal end of each of the first and second coil layers extending from a proximal portion of the shaft body to the shaft body's distal end,
a distal end of each of the liner, the braid member, and the first and second coil layers extending beyond the distal end of the shaft body; and
a tip member disposed at the distal end of the shaft body.
19. The catheter of claim 18 , wherein the distal end of the shaft body and a proximal end of the tip member are defined by a change in radiopacity of a material.
20. The catheter of claim 18 , wherein the second coil layer is in contact with the first coil layer such that the first and second coil layers interlock when rotation is applied to the shaft body's proximal end.