Injection devices and systems and methods for using them

1. A device for injecting one or more agents into tissue within a patient's body, comprising:

a substantially radially fixed and substantially axially incompressible tubular member comprising a proximal end and a distal end sized for introduction into the patient's body, at least a distal portion of the tubular member being sufficiently flexible to allow introduction into tortuous anatomy within the patient's body;

a flexible, fluid-tight member disposed within an interior region of the tubular member and extending between the proximal end and the distal end, the fluid-tight member defining a lumen extending between the proximal end and the distal end, the fluid-tight member being expandable within the interior of the tubular member when exposed to internal fluid pressure with the tubular member limiting expansion of the fluid-tight member; and

a needle tip extending from a distal end of the tubular member and having a cross-section smaller than the distal end, the needle tip comprising a passage communicating between the lumen and one or more outlets in the needle tip, the passage having a cross-section smaller than the lumen.

2. The device of claim 1 , wherein the tubular member comprises a coil including windings extending between the proximal end and the distal end and a tensile element coupled to the proximal and distal ends.

3. The device of claim 2 , further comprising a jacket surrounding the coil.

4. The device of claim 2 , wherein the fluid-tight member comprises a membrane or bladder.

5. A device for injecting one or more agents into tissue within a patient's body, comprising:

a substantially axially incompressible elongate coil comprising a proximal end, a distal end sized for introduction into the patient's body;

a sleeve disposed within an interior region of the coil and extending between the proximal end and the distal end such that the sleeve is free-floating along at least a portion of its length between the proximal end and the distal end, the sleeve defining a lumen extending between the proximal end and the distal end;

a tensile element coupled to the proximal end and the distal end of the coil; and

a needle tip extending from the distal end of the coil and having a cross-section smaller than the distal end, the needle tip comprising a passage communicating between the lumen and one or more outlets in the needle tip, the passage having a cross-section smaller than the lumen.

6. The device of claim 5 , further comprising a jacket surrounding the coil.

7. The device of claim 6 , wherein the jacket comprises one or more layers of material applied around an outer surface of the coil.

8. The device of claim 5 , further comprising a distal stop on the distal end of the coil having an outer cross-section larger than an outer cross-section of the distal end of the coil, and wherein the needle tip is coupled to the distal stop.

9. The device of claim 5 , wherein the sleeve comprises a flexible, thin-walled tube.

10. The device of claim 9 , wherein the flexible, thin-walled tube has an outer diameter in a relaxed state that is as large or larger than an inner diameter of the coil.

11. The device of claim 5 , wherein the tensile element comprises an elongate wire including a first end attached to the proximal end of the coil and a second end attached to one of the distal end of the coil and a distal stop on the distal end of the coil.

12. The device of claim 11 , wherein the wire is unattached to the coil between the first end and the second end.

13. The device of claim 5 , wherein the tensile element comprises an elongate tubular member including a first end attached to the proximal end of the coil and a second end attached to one of the distal end of the coil and a distal stop on the distal end of the coil, the tubular member including a secondary lumen communicating with the passage in the needle tip.

14. A device for injecting one or more agents into tissue within a patient's body, comprising:

a substantially radially fixed tubular member comprising a proximal end and a distal end sized for introduction into the patient's body, at least a distal portion of the tubular member being sufficiently flexible to allow introduction into tortuous anatomy within a patient's body;

a flexible, fluid-tight member disposed within an interior region of the tubular member and extending between the proximal end and the distal end, the fluid-tight member defining a lumen extending between the proximal end and the distal end, the fluid-tight member being expandable within the interior of the tubular member when exposed to internal fluid pressure with the tubular member limiting expansion of the fluid-tight member; and

a needle tip extending from a distal end of the tubular member and having a cross-section smaller than the distal end, the needle tip comprising a passage communicating between the lumen and one or more outlets in the needle tip, the passage having a cross-section smaller than the lumen.

15. The device of claim 14 , wherein the tubular member comprises a coil including windings extending between the proximal end and the distal end and a tensile element coupled to the proximal end and the distal end.

16. The device of claim 15 , further comprising a jacket surrounding the coil.

17. The device of claim 15 , wherein the fluid-tight member comprises a membrane or bladder.

18. The device of claim 14 , wherein the tubular member is substantially axially incompressible.