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.
1. A cannula comprising:
a wire that is helically wound to form a plurality of coils, wherein the plurality of coils comprises at least one fused coil portion wherein adjacent coils are fused together, the plurality of coils further comprising non-fused coil portions positioned at opposite ends of the at least one fused coil portion; and
at least one hole passing radially through the at least one fused coil portion.
2. The cannula of claim 1 , wherein the at least one hole interrupts a plurality of the adjacent coils of the at least one fused coil portion.
3. The cannula of claim 2 , wherein the at least one fused coil portion comprises one or more uninterrupted coils on either axial side of the hole.
4. The cannula of claim 2 , wherein at least three holes interrupt a plurality of the adjacent coils of the at least one fused coil portion.
5. The cannula of claim 4 , wherein the at least three holes are spaced apart from one another equally in a circumferential direction around the at least one fused coil portion.
6. The cannula of claim 1 , wherein the adjacent coils of the at least one fused coil portion are fused together via welding.
7. The cannula of claim 1 , wherein the adjacent coils of the at least one fused coil portion are fused together via adhesive.
8. The cannula of claim 1 , wherein the at least one fused coil portion extends parallel to the central axis of the cannula.
9. The cannula of claim 1 , wherein the at least one fused coil portion comprises a fused portion axial length, and the at least one hole comprises a hole axial length, and the fused portion axial length is greater than the hole axial length.
10. The cannula of claim 1 , further comprising:
a coating which encases the adjacent coils of the at least one fused coil portion but does not block the at least one hole.
11. The cannula of claim 10 , wherein the coating encases the non-fused coil portions positioned at opposite ends of the at least one fused coil portion.
12. The cannula of claim 11 , wherein the coating is flexible and encases all of the plurality of coils.
13. A cannula comprising:
a wire that is helically wound to form a plurality of coils, wherein the plurality of coils comprises at least one fused coil portion wherein adjacent coils are fused together, the plurality of coils further comprising non-fused coil portions positioned at opposite ends of the at least one fused coil portion; and
a first hole passing radially through and interrupting a plurality of the adjacent coils of the at least one fused coil portion.
14. The cannula of claim 13 , further comprising:
a second hole passing radially through and interrupting a plurality of the adjacent coils of the at least one fused coil portion.
15. The cannula of claim 14 , further comprising:
a third hole passing radially through and interrupting a plurality of the adjacent coils of the at least one fused coil portion.
16. The cannula of claim 13 , wherein the at least one fused coil portion comprises one or more uninterrupted coils on opposing axial sides of the first hole.
17. The cannula of claim 13 , wherein the wire comprises Nitinol.
18. The cannula of claim 13 , further comprising:
a coating which encases the adjacent coils of the at least one fused coil portion but does not substantially block the first hole.
19. The cannula of claim 18 , wherein the coating comprises a polymeric material.
20. The cannula of claim 18 , wherein the first hole allows blood to flow therethrough.