Spring cannulae
Disclosed herein are embodiments of spring cannulae, including one or more holes in the sidewall of the cannula. Some disclosed cannulae include a wire, helically wound to form coils, and at least one hole in the cannula that interrupts one or more of the coils. Some embodiments further include a fused region of the coils through which the hole passes. Some embodiments include a ring attached to ends of the interrupted coils, where the hole is surrounded by the ring. Some embodiments include a sheath that is attached to a radial surface of the interrupted coils, where the hole passes radially though the sheath. Some embodiments include an elongated coil with a hole passing between the elongated coil and an adjacent coil. Further embodiments disclose cannulae that include a wire helically wound to form coils, and an insert having a porous section with at least one hole.
1. A cannula, comprising:
a wire, helically wound to form a plurality of coils, the coils defining a tubular sidewall of the cannula;
a hole passing radially through the sidewall and interrupting at least one of the coils, the hole suitable for allowing passage of a fluid through the sidewall; and
wherein the interrupted coils are reinforced by being axially coupled to adjacent coils in a region surrounding the hole, wherein the interrupted coils are reinforced by a ring that connects the interrupted coils and surrounds the hole, and wherein the ring is attached to a radially inner surface of the coils.
2. The cannula of claim 1 , further comprising a polymeric coating encasing the coils, wherein the coating does not cover the hole.
3. The cannula of claim 1 , wherein an adjacent group of the coils are fused axially together to form a fused region of the wire, and the hole passes radially through the fused region of the wire, such that the hole interrupts a plurality of fused coils, and an axial length of the hole is less than an axial length of the fused region of the wire.
4. The cannula of claim 3 , wherein a second hole passes radially through the fused region of the wire such that the second hole interrupts the plurality of the fused coils, and an axial length of the second hole is less than the axial length of the fused region of the wire.
5. The cannula of claim 3 , wherein the fused region of the wire comprises one or more un-interrupted coils on either axial side of the hole.
6. The cannula of claim 3 , wherein the adjacent group of coils are fused such that the fused region forms a solid tube.
7. The cannula of claim 3 , further comprising: a second group of adjacent coils that are axially fused together to form a second fused region of the wire; and a hole passing radially through the second fused region of the wire, such that the hole interrupts a plurality of the fused coils in the second fused region of the wire, and an axial length of the hole is less than an axial length of the second fused region of the wire.
8. The cannula of claim 3 , wherein the length of the fused region is from about 0.2 cm to about 2 cm.
9. The cannula of claim 1 , wherein the wire comprises nitinol.
10. A cannula, comprising:
a wire, helically wound to form a plurality of coils, the coils defining a tubular sidewall of the cannula;
a hole passing radially through the sidewall and interrupting at least one of the coils, the hole suitable for allowing passage of a fluid through the sidewall; and
wherein the interrupted coils are reinforced by being axially coupled to adjacent coils in a region surrounding the hole, wherein the interrupted coils are reinforced by a ring that connects the interrupted coils and surrounds the hole, and wherein a plurality of pieces of metal are inserted in between ends of the interrupted coils, and the ring comprises the ends of the interrupted coils and the pieces of metal.
11. The cannula of claim 10 , further comprising a sheath attached to a radial surface of an adjacent group of the coils, the adjacent group of the coils including the interrupted coils and at least one un-interrupted coil at either axial side of the interrupted coils, wherein the hole passes through and is surrounded by the sheath.
12. The cannula of claim 10 , wherein the wire comprises nitinol.
13. A cannula, comprising:
a wire, helically wound to form a plurality of coils, the coils defining a tubular sidewall of the cannula;
a hole passing radially through the sidewall and interrupting at least one of the coils, the hole suitable for allowing passage of a fluid through the sidewall; and
wherein the interrupted coils are reinforced by being axially coupled to adjacent coils in a region surrounding the hole, wherein the interrupted coils are reinforced by a ring that connects the interrupted coils and surrounds the hole, and wherein the ring is positioned between ends of the interrupted coils and attached to the ends of the interrupted coils, such that the ring and the interrupted coils are positioned at about the same radial distance from a longitudinal center axis of the cannula.
14. The cannula of claim 13 , further comprising a sheath attached to a radial surface of an adjacent group of the coils, the adjacent group of the coils including the interrupted coils and at least one un-interrupted coil at either axial side of the interrupted coils, wherein the hole passes through and is surrounded by the sheath.
15. The cannula of claim 14 , wherein the radial surface is a radially inner surface.
16. The cannula of claim 14 , wherein the radial surface is a radially outer surface.
17. A cannula, comprising:
a wire, helically wound to form a plurality of coils, the coils defining a tubular sidewall of the cannula;
a hole passing radially through the sidewall and interrupting at least one of the coils, the hole suitable for allowing passage of a fluid through the sidewall; and wherein the interrupted coils are reinforced by being axially coupled to adjacent coils in a region surrounding the hole; and
a sheath attached to a radial surface of an adjacent group of the coils, the adjacent group of the coils including the interrupted coils and at least one un-interrupted coil at either axial side of the interrupted coils, wherein the hole passes through and is surrounded by the sheath, wherein the sheath is a solid metal tube welded to the coils.
18. A cannula, comprising:
a wire, helically wound to form a plurality of coils, the coils defining a tubular sidewall of the cannula;
a hole passing radially through the sidewall and interrupting at least one of the coils, the hole suitable for allowing passage of a fluid through the sidewall; and wherein the interrupted coils are reinforced by being axially coupled to adjacent coils in a region surrounding the hole; and
a sheath attached to a radial surface of an adjacent group of the coils, the adjacent group of the coils including the interrupted coils and at least one un-interrupted coil at either axial side of the interrupted coils, wherein the hole passes through and is surrounded by the sheath, wherein the sheath comprises an inner layer comprising metal, and an outer layer comprising a polymer.
19. The cannula of claim 18 , wherein the radial surface is a radially inner surface.
20. The cannula of claim 18 , wherein the radial surface is a radially outer surface.