Variable stiffness cannulae and associated delivery systems and methods

1. A delivery system, comprising:

a cannula, comprising:

an elongate tubular member having a lengthwise axis and a circumferential wall extending between a proximal end and a distal end and defining an interior lumen;

the elongate tubular member having an intermediate axial portion extending between a proximal axial portion that includes the proximal end and a distal axial portion that includes the distal end; and

a pattern of openings in the circumferential wall of the elongate tubular member, the pattern of openings comprising a plurality of openings arranged in an interrupted spiral that extends circumferentially along the intermediate axial portion of the elongate tubular member, the pattern of openings comprising distinct sections separated from each other by intervening sections, the intervening sections free of the pattern of openings and comprising an uninterrupted circumferential wall;

wherein the proximal axial portion and the distal axial portion are free of the pattern of openings and comprise an uninterrupted circumferential wall; and

wherein the proximal portion is longer than the distal portion;

an intraluminal medical device disposed on the distal axial portion of the elongate tubular member; and

an elongate outer tubular member defining an outer tubular member lumen;

wherein the cannula is disposed within the outer tubular member lumen such that the intraluminal medical device is circumferentially disposed about the cannula and within the outer tubular member lumen.

2. The delivery system of claim 1 , wherein each opening of the plurality of openings comprises an elongate slit that extends through the entire thickness of the circumferential wall of the elongate tubular member.

3. The delivery system of claim 1 , wherein a portion of the circumferential wall is disposed between openings in immediately adjacent revolutions of the interrupted spiral; and

wherein each opening of the plurality of openings has an axial width;

wherein the portion has a length along the lengthwise axis of the elongate tubular member that is between about 0.5 times and about 40 times the axial width of the openings in the immediately adjacent revolutions of the interrupted spiral.

4. The delivery system of claim 1 , wherein portions of the circumferential wall are disposed between immediately adjacent revolutions of the interrupted spiral; and

wherein the portions have uniform lengths along the lengthwise axis of the elongate tubular member.

5. The delivery system of claim 1 , wherein portions of the circumferential wall are disposed between immediately adjacent revolutions of the interrupted spiral; and

wherein the portions have varying lengths along the lengthwise axis of the elongate tubular member.

6. The delivery system of claim 1 , wherein a portion of the circumferential wall is disposed between immediately adjacent openings within a revolution of the interrupted spiral; and

wherein each opening of the plurality of openings has an axial width;

wherein the portion has a circumferential length along the elongate tubular member that is between about 0.1 times and about 2 times the axial width of the immediately adjacent openings within a revolution of the interrupted spiral.

7. The delivery system of claim 1 , wherein portions of the circumferential wall are disposed between immediately adjacent openings within a revolution of the interrupted spiral; and

wherein the portions have uniform circumferential lengths along the elongate tubular member.

8. The delivery system of claim 1 , wherein portions of the circumferential wall are disposed between immediately adjacent openings within a revolution of the interrupted spiral; and

wherein the portions have varying circumferential lengths along the elongate tubular member.

9. The delivery system of claim 1 , further comprising a double-tapered distal tip secured to the distal end of the elongate tubular member;

wherein the double-tapered distal tip has an outer diameter that is greater than an outer diameter of the elongate tubular member.

10. The delivery system of claim 1 , wherein the elongate tubular member comprises a metal.

11. A delivery system, comprising:

a cannula, comprising:

an elongate tubular member having a lengthwise axis and a circumferential wall extending between a proximal end and a distal end and defining an interior lumen;

a double-tapered distal tip secured to the distal end of the elongate tubular member and having an outer diameter that is greater than an outer diameter of the elongate tubular member;

the elongate tubular member having an intermediate axial portion extending between a proximal axial portion that includes the proximal end and a distal axial portion that includes the distal end; and

a pattern of openings in the circumferential wall of the elongate tubular member, the pattern of openings comprising a plurality of openings arranged in an interrupted spiral that extends circumferentially along the intermediate axial portion of the elongate tubular member;

wherein the proximal axial portion and the distal axial portion are free of the pattern of openings and comprise an uninterrupted circumferential wall; and

wherein the proximal portion is longer than the distal portion;

an intraluminal medical device disposed on the distal axial portion of the elongate tubular member; and

an elongate outer tubular member defining an outer tubular member lumen;

wherein the cannula is disposed within the outer tubular member lumen such that the intraluminal medical device is circumferentially disposed about the cannula and within the outer tubular member lumen.

12. The delivery system of claim 11 , wherein each opening of the plurality of openings comprises an elongate slit that extends through the entire thickness of the circumferential wall of the elongate tubular member.

13. The delivery system of claim 11 , wherein a portion of the circumferential wall is disposed between openings in immediately adjacent revolutions of the interrupted spiral; and

wherein each opening of the plurality of openings has an axial width;

wherein the portion has a length along the lengthwise axis of the elongate tubular member that is between about 0.5 times and about 40 times the axial width of the openings in the immediately adjacent revolutions of the interrupted spiral.

14. The delivery system of claim 11 , wherein portions of the circumferential wall are disposed between immediately adjacent revolutions of the interrupted spiral; and

wherein the portions have uniform lengths along the lengthwise axis of the elongate tubular member.

15. The delivery system of claim 11 , wherein portions of the circumferential wall are disposed between immediately adjacent revolutions of the interrupted spiral; and

wherein the portions have varying lengths along the lengthwise axis of the elongate tubular member.

16. The delivery system of claim 11 , wherein a portion of the circumferential wall is disposed between immediately adjacent openings within a revolution of the interrupted spiral; and

wherein each opening of the plurality of openings has an axial width;

wherein the portion has a circumferential length along the elongate tubular member that is between about 0.1 times and about 2 times the axial width of the immediately adjacent openings within a revolution of the interrupted spiral.

17. The delivery system of claim 11 , wherein portions of the circumferential wall are disposed between immediately adjacent openings within a revolution of the interrupted spiral; and

wherein the portions have uniform circumferential lengths along the elongate tubular member.

18. The delivery system of claim 11 , wherein portions of the circumferential wall are disposed between immediately adjacent openings within a revolution of the interrupted spiral; and

wherein the portions have varying circumferential lengths along the elongate tubular member.

19. The delivery system of claim 11 , wherein the elongate tubular member comprises a metal.

20. The delivery system of claim 19 , wherein the metal comprises stainless steel.