Needle and tine deployment mechanism
A needle electrode deployment shaft includes a central member and a plurality of needle electrodes. The central member has a plurality of needle advancement channels formed therein. The needle electrodes are disposed within the advancement channels and each advancement channel terminates in a ramp portion which deflects the needles radially outwardly as they are axially advanced. The ramps may be spirally or acutely configured in order to increase the distance through which the needles may be bent as they are axially advanced. Additionally, the central member may have a radially reduced distal tip in order to decrease tissue insertion forces.
1. A needle electrode deployment shaft comprising: a central member having a proximal end, a distal end, a longitudinal axis therebetween, an outer surface, and a plurality of needle electrode advancement channels; and a plurality of peripheral needle electrodes slidably received in the channels; wherein the plurality of needle electrode advancement channels comprises a plurality of ramps, each ramp being arcuate and curved about the longitudinal axis of the central member.
2. The device of claim 1 , wherein each channel has a proximal portion axially aligned with the longitudinal axis of the central member.
3. The device of claim 1 , wherein each channel comprises a ramp entrance located at a first angular orientation relative to the longitudinal axis and at a preselected radial distance between the longitudinal axis of the central member and the ramp entrance.
4. The device of claim 3 , wherein each channel comprises a ramp exit located at a second angular orientation angularly offset from the first angular orientation and on an outer surface of the central member.
5. The device of claim 4 , wherein the offset angle is in the range from 450 to 1500.
6. The device of claim 4 , wherein the ramp entrance and ramp exit are separated by a distance in the axial direction in the range from 2.5 mm to 25 mm.
7. The device of claim 3 , wherein the central member has a diameter in the range from 0.75 mm to 3.1 mm and the preselected radial distance is in the range from 0.25 mm to 1.25 mm.
8. The device of claim 1 , wherein each channel follows a spiral path.
9. The device of claim 1 , wherein each channel is confined within a plane that intersects the central member.
10. The device of claim 1 , wherein the plurality of channels deflect the needle electrodes radially outwardly as they are advanced through the plurality of channels.
11. The device of claim 1 , wherein the needle electrodes are configured to deliver radiofrequency energy to tissue.
12. The device of claim 11 , wherein the radiofrequency energy is monopolar.
13. The device of claim 11 , wherein the radiofrequency energy is bipolar.
14. The device of claim 1 , further comprising an imaging array coupled to the distal end of the central member.
15. The device of claim 14 , wherein the imaging array is deflectable between a low profile configuration and a higher profile, deflected configuration.
16. The device of claim 14 , wherein the imaging array is configured to pivot or rotate about the central member.
17. The device of claim 14 , wherein the imaging array comprises an ultrasound imaging array.
18. The device of claim 1 , further comprising a plurality of deployment ports from which the plurality of needle electrodes extend as they are advanced through the plurality of channels.
19. The device of claim 18 , wherein the ports of the plurality of deployment ports are in the form of a slot, circle, or oval at an angle to a longitudinal axis of the shaft member.
20. The device of claim 1 , wherein the central member has a distal tip with a sharpened distal end.
21. The device of claim 20 , wherein the distal tip comprises a spike having a region with a width which is less than that of the central member.
22. The device of claim 21 , further comprising a central electrode reciprocatably mounted in a central lumen in the central member.
23. The device of claim 22 , wherein the spike is generally cylindrical and axially aligned with the central member where the central lumen extends through the distal tip.
24. The device of claim 22 , wherein the spike is radially offset from the axis of the central member and has a groove which receives the central electrode when extended from the central member.
25. The device of claim 22 , wherein the spike has a chamfered surface having an electrode transition cavity extending from the central lumen.
26. The device of claim 21 , comprising a plurality of axially aligned spikes extending from a distal end of the central member, wherein the central electrode advances distally through a protected region defined by the plurality of spikes.
27. The device of claim 21 , wherein the spike extends from the central member and is connected as a central electrode.
28. The device of claim 1 , wherein the plurality of channels consists of from 3 to 9 channels.
29. The device of claim 1 , wherein the plurality of needle electrodes consists of from 3 to 9 needle electrodes.
30. The device of claim 1 , wherein the needle electrode has a beveled end which is oriented to engage a surface of the ramp as the needle is axially advanced.
31. The device of claim 30 , wherein the beveled ends are chamfered to have a flat surface, a curved surface, or a multi-faceted surface.
32. The device of claim 1 , wherein at least a distal region of the central member is non-conductive.
33. The device of claim 1 , wherein at least a distal region of the central member is electrically conductive and adapted to act as an electrode.
34. The device of claim 1 , wherein the central member has a central lumen.
35. The device of claim 1 , wherein each needle electrode has a tissue penetrating tip.