Method and apparatus for creating a virtual electrode used for the ablation of tissue

• US 6,315,777 B1
• Filed: 07/06/1999
• Issued: 11/13/2001
• Est. Priority Date: 07/07/1998
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Comben, Richard H.
• Primary Examiner(s): GIBSON, ROY DEAN
• Application Number:
  US09/347,380
• Time in Patent Office: 861 Days
• Field of Search: 606/34, 606/37, 606/40-42, 606/45, 606/49, 606/50, 607/116, 607/122, 607/96-102
• US Class Current: 606/41
• CPC Class Codes: A61B 18/1477 Needle-like probes
• CPC Class Codes: A61B 2018/1472 for use with liquid electrolyte, e.g. virtual electrodes

Abstract

A method and apparatus for creating a virtual electrode to ablate bodily tissue. The surgical apparatus includes an inner tube and an outer tube. The inner tube defines a proximal portion and a distal portion. The distal portion forms an orifice for distributing a conductive solution from the inner tube and further forms an electrode. The outer tube coaxially receives the inner tube such that the outer tube is slidable relative to the inner tube. With this configuration, the outer tube selectively blocks flow of conductive solution from the orifice. During use, conductive solution distributed from the orifice is subjected to a current from the electrode, thereby creating a virtual electrode.

Claims

1. A surgical apparatus for creating a virtual electrode to ablate bodily tissue, the surgical apparatus comprising:

an inner tube defining a proximal portion and a distal portion, the distal portion forming a plurality of orifices including a proximal-most orifice and a distal-most orifice for distributing a conductive solution from the inner tube and further forming an electrode; and

an outer tube coaxially disposed about the inner tube, the outer tube defining a proximal end and a distal end and forming a slot proximal the distal end, wherein the outer tube is slidable relative to the inner tube and a longitudinal spacing between a distal side of the slot and the distal end is not less than a longitudinal distance between the proximal-most and distal-most orifices such that a portion of the outer tube distal the slot selectively, simultaneously blocks the plurality of orifices.

2. The surgical apparatus of claim 1, wherein the electrode is formed distal the distal-most orifice.

3. The surgical apparatus of claim 1, the slot being configured such that when aligned with the plurality of orifices, the slot dictates a desired bolus shape of the conductive solution distributed from the inner tube.

4. The surgical apparatus of claim 1, wherein the proximal portion of the inner tube is attached to a shutter index element for dictating a desired position of the outer tube relative to the inner tube.

5. The surgical apparatus of claim 4, wherein the outer tube defines a proximal end and a distal end, the surgical apparatus further comprising:

a support connected to the proximal end of the outer tube, the support being sized to selectively engage a portion of the shutter index element.

6. The surgical apparatus of claim 5, wherein the shutter index element forms an axial slot sized to guide the support and a circumferential slot sized to selectively maintain the support, the circumferential slot being located to dictate a desired orientation of the outer tube relative to the inner tube.

7. The surgical apparatus of claim 6, wherein the shutter index element forms a plurality of spaced circumferential slots connected to the axial slot, each of the circumferential slots configured to selectively receive the support to dictate a desired position of the outer tube relative to the inner tube.

8. The surgical apparatus of claim 1, wherein a longitudinal length of the slot is not less than a longitudinal distance between the proximal-most and distal-most orifices.

9. The surgical apparatus of claim 1, wherein a longitudinal spacing between the distal side of the slot and the distal end of the outer tube is not greater than a longitudinal distance between the distal-most orifice and a distal end of the inner tube.

12. The surgical system of claim 1, wherein the electrode is formed at the distal portion of the inner tube.

10. A surgical apparatus for creating a virtual electrode to ablate bodily tissue, the surgical apparatus comprising:

an inner tube defining a proximal portion and a distal portion, the distal portion forming a plurality of orifices for distributing a conductive solution from the inner tube and further forming an electrode, wherein the plurality of orifices includes a set of axially arranged orifices increasing in size toward a center of the set;

an outer tube coaxially disposed about the inner tube, wherein the outer tube is slidable relative to the inner tube such that the outer tube selectively blocks at least one of the plurality of orifices.

11. A surgical system for creating a virtual electrode to ablate bodily tissue, the surgical system comprising:

a fluid source maintaining a supply of conductive solution;

a current source configured to selectively supply an electrical current; and

a surgical instrument including;

an inner tube fluidly connected to the fluid source, the inner tube defining a proximal portion and a distal portion, wherein the distal portion forms a plurality of orifices for releasing the conductive solution from the inner tube,

an outer tube coaxially disposed about the inner tube, wherein the outer tube is slidable relative to the inner tube from a first position in which the outer tube exposes at least one of the orifices to a second position in which the outer tube blocks release of the conductive fluid from the surgical instrument by directly covering all of the orifices formed by the inner tube,

an electrode associated with the distal portion of the inner tube, the electrode being electrically connected to the current source to energize conductive solution released from the inner tube.

13. The surgical system of claim 11, wherein the outer tube defines a proximal end and a distal end, and further wherein the outer tube forms a slot proximal the distal end, the slot being configured such that when aligned with the orifice, the slot dictates a desired bolus shape of conductive solution released from the inner tube.

14. The surgical system of claim 11, wherein the proximal portion of the inner tube is attached to a shutter index element for dictating a desired position of the outer tube relative to the inner tube.

15. The surgical system of claim 14, wherein the outer tube defines a proximal end and a distal end, the surgical instrument further including:

a support connected to the proximal end of the outer tube, the support being sized to selectively engage a portion of the shutter index element.

16. The surgical system of claim 15, wherein the shutter index element forms an axial slot sized to guide the support and a circumferential slot sized to selectively maintain the support, the circumferential slot being located to dictate a desired orientation of the outer tube relative to the inner tube.

17. The surgical system of claim 16, wherein the shutter index element forms a plurality of spaced circumferential slots connected to the axial slot, each of the circumferential slots configured to selectively receive the support so as to dictate a desired position of the outer tube relative to the inner tube.

18. The surgical system of claim 11, wherein the surgical instrument is configured such that in the second position, the distal end of the outer tube is proximal a distal end of the inner tube.

19. A method of forming a virtual electrode for ablating bodily tissue, the method comprising:

providing a surgical instrument including an inner tube slidably received within an outer tube, the inner tube defining a proximal portion and a distal portion, the distal portion forming an orifice for distributing a conductive solution from the inner tube and further forming an electrode;

delivering the distal portion of the inner tube to a target site;

positioning the outer tube relative to the inner tube such that the orifice is exposed;

distributing a conductive solution at the target site via the orifice;

repositioning the outer tube relative to the inner tube after distributing the conductive solution such that the orifice is blocked; and

applying a current to the conductive solution distributed from the orifice via the electrode to create a virtual electrode.

20. The method of claim 19, wherein the distal portion of the inner tube forms a plurality of orifices, and wherein repositioning the outer tube relative to the inner tube includes orientating the outer tube to block a portion of the plurality of orifices.

21. The method of claim 19, wherein the outer tube defines a proximal end and a distal end and includes a slot adjacent the distal end, and wherein positioning the outer tube relative to the inner tube includes aligning the slot with the orifice to produce a desired bolus shape of the conductive solution.

22. The method of claim 19, wherein the distal portion of the inner tube forms a plurality of orifices, and wherein repositioning the outer tube relative to the inner tube includes orienting the outer tube to block all of the orifices formed by the inner tube.