Medical devices having coaxial cannulae

1. A medical device, comprising:

an outer cannula having an outer cannula lengthwise axis and an outer cannula circumferential wall extending between an outer cannula proximal end and an outer cannula distal end, the outer cannula circumferential wall defining an outer cannula interior lumen and a first side port opening extending through the outer cannula circumferential wall;

an inner cannula disposed within the outer cannula interior lumen and secured to the outer cannula, the inner cannula having an inner cannula lengthwise axis, an inner cannula circumferential wall extending between an inner cannula proximal end and an inner cannula distal end, the inner cannula circumferential wall defining an inner cannula interior lumen, a pattern of openings extending along a spiral path about the inner cannula lengthwise axis, and a second side port opening extending through the inner cannula circumferential wall and aligned with the first side port opening with respect to the inner cannula lengthwise axis;

a side port joint disposed between the outer cannula and the inner cannula and adjacent the second side port opening, the side port joint forming an attachment between the outer cannula and the inner cannula; and

a ramp member disposed within the inner cannula interior lumen and defining a ramp surface aligned with the second side port opening.

2. The medical device of claim 1 , wherein the ramp member extends from the second side port opening axially along the inner cannula lengthwise axis and toward the distal end of the inner cannula.

3. The medical device of claim 1 , further comprising a distal joint disposed between the outer cannula distal end and the inner cannula distal end, the distal joint forming an attachment between the outer cannula and the inner cannula.

4. The medical device of claim 3 , wherein the distal joint comprises a circumferential joint.

5. The medical device of claim 3 , wherein the distal joint comprises a joint selected from the group consisting of a weld joint, a brazing joint, and a solder joint.

6. The medical device of claim 1 , wherein the side port joint comprises a circumferential joint extending around the second side port opening.

7. The medical device of claim 1 , wherein the ramp member extends from the second side port opening axially along the inner cannula lengthwise axis and to the distal end of the inner cannula.

8. The medical device of claim 1 , wherein the ramp member extends from the second side port opening axially along the inner cannula lengthwise axis and toward the proximal end of the inner cannula.

9. The medical device of claim 1 , wherein the ramp member extends from the second side port opening axially along the inner cannula lengthwise axis and to the proximal end of the inner cannula.

10. The medical device of claim 1 , wherein the outer cannula comprises a first metal.

11. The medical device of claim 10 , wherein the inner cannula comprises a second, different metal.

12. The medical device of claim 11 , wherein the first metal comprises stainless steel and the second metal comprises a superelastic alloy.

13. A medical device, comprising:

an outer cannula having an outer cannula lengthwise axis and an outer cannula circumferential wall extending between an outer cannula proximal end and an outer cannula distal end, the outer cannula circumferential wall defining an outer cannula interior lumen and a first side port opening extending through the outer cannula circumferential wall, the outer cannula comprising a polymeric material and being free of openings in the outer cannula circumferential wall other than the first side port opening;

an inner cannula disposed within the outer cannula interior lumen and secured to the outer cannula, the inner cannula having an inner cannula lengthwise axis, an inner cannula circumferential wall extending between an inner cannula proximal end and an inner cannula distal end, the inner cannula circumferential wall defining an inner cannula interior lumen, a pattern of openings extending along a spiral path about the inner cannula lengthwise axis, and a second side port opening extending through the inner cannula circumferential wall and aligned with the first side port opening with respect to the inner cannula lengthwise axis, the inner cannula comprising a metal;

a side port joint disposed between the outer cannula and the inner cannula, the side port joint comprising a circumferential joint extending around the second side port opening and forming an attachment between the outer cannula and the inner cannula; and

a ramp member disposed within the inner cannula interior lumen and defining a ramp surface aligned with the second side port opening.

14. The medical device of claim 13 , further comprising a distal joint disposed between the outer cannula distal end and the inner cannula distal end, the distal joint forming an attachment between the outer cannula and the inner cannula.

15. The medical device of claim 14 , wherein the distal joint comprises a circumferential joint.

16. The medical device of claim 14 , wherein the distal joint comprises a joint selected from the group consisting of a weld joint, a brazing joint, and a solder joint.

17. The medical device of claim 13 , wherein the ramp member extends from the second side port opening axially along the inner cannula lengthwise axis and toward the distal end of the inner cannula.

18. The medical device of claim 13 , wherein the ramp member extends from the second side port opening axially along the inner cannula lengthwise axis and to the distal end of the inner cannula.

19. The medical device of claim 13 , wherein the ramp member extends from the second side port opening axially along the inner cannula lengthwise axis and toward the proximal end of the inner cannula.

20. The medical device of claim 13 , wherein the ramp member extends from the second side port opening axially along the inner cannula lengthwise axis and to the proximal end of the inner cannula.