Endocardial Dispersive Electrode for Use with a Monopolar RF Ablation Pen

• US 20090138008A1
• Filed: 02/02/2009
• Published: 05/28/2009
• Est. Priority Date: 04/29/2003
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Briscoe, Roderick E.
• Granted Patent: US 7,871,409 B2
• Time in Patent Office: Days
• US Class Current: 606/33
• CPC Class Codes: A61B 18/1492 having a flexible, catheter-like structure, e.g. for heart ablation A61B18/1477 takes precedence
• CPC Class Codes: A61B 18/16 Indifferent or passive electrodes for grounding
• CPC Class Codes: A61B 2018/00148 with metal
• CPC Class Codes: A61B 2018/00214 Expandable means emitting energy, e.g. by elements carried thereon
• CPC Class Codes: A61B 2018/0022 Balloons
• CPC Class Codes: A61B 2018/00351 Heart

Abstract

Methods and devices for forming a lesion in a target tissue having a cavity within a first RF electrode and a second RF electrode can be coupled to opposite poles of an RF current source. The second electrode can be inserted into the tissue cavity and expanded to contact the target tissue from within. The first electrode can be externally disposed against the target tissue while applying RF current between the first and second electrodes to ablate the target tissue. Some methods are directed to ablating tribiculated atrial wall tissue to treat atrial fibrillation. The second electrode can contact the tribiculated tissue directly from within to provide a direct path between the two electrodes. In some methods, the second electrode is inserted through an incision made to remove an atrial appendage. The methods can provide deeper, narrower lesions relative to those made using remote, indifferent electrodes. Atrial fibrillation ablation procedures can be performed using the invention, requiring fewer incisions than conventional methods.

Claims

1. A device for facilitating cardiac tissue ablation, the device comprising:

a shaft having a proximal region and a distal region;

an electrode including an envelope, the envelope having an interior and an electrically conductive surface disposed near the shaft distal region, wherein the surface has a first configuration having a first interior volume within the conductive surface and a second, expanded configuration having a second interior volume within the conductive surface, wherein the second to volume is greater than the first volume.

2. A device as in claim 1, wherein the electrically conductive surface includes an outer metallic layer disposed over a polymeric layer.

3. A device as in claim 1, wherein the electrically conductive surface includes an outer metallic mesh disposed over a polymeric layer.

4. A device as in claim 3, wherein the polymeric layer is substantially resistant to fluid permeation, and wherein the polymeric layer is inflatable.

5. A device as in claim 1, wherein the electrically conductive surface is the outer surface of an electrically conductive polymeric layer.

6. A device as in claim 1, wherein the envelope is porous and the electrically conductive surface is the outer surface an electrically conductive porous mesh.

7. A device as in claim 1, wherein the device shaft includes a lumen extending along the shaft length and in fluid communication with the envelope interior for inflating the electrode surface.

8. A device as in claim 7, wherein the lumen is disposed within the shaft.

9. A device as in claim 1, wherein the device shaft includes a lumen within, wherein the lumen is in fluid communication with the envelope interior for inflating the surface electrode.

10. A device as in claim 1, wherein the device has a length of less than about 12 inches when expanded.

11. A device as in claim 1, wherein the device has a length of less than about 6 inches when expanded.

12. A device as in claim 1, wherein the envelope is biased to expand outwardly when unconstrained.

13. A device as in claim 12, wherein the envelope includes a metallic mesh that is biased to expand outwardly when unconstrained.

14. A device as in claim 1, wherein the envelope includes an electrically conductive shape memory metallic mesh that expands outwardly when heated to body temperature from room temperature.

15. A method for forming a lesion in a target tissue having a cavity within, the method comprising:

providing a first RF electrode coupled to one pole of an RF current source;

providing a second RF electrode electrically coupled to the other pole of the RF current source, wherein the second RF electrode has an electrically conductive expandable surface;

inserting the second electrode into the tissue cavity;

expanding the second electrode to contact the target tissue from within the cavity; and

disposing the first electrode against the target tissue while applying RF current between the first and second electrodes to ablate the target tissue.

16. A method as in claim 15, wherein the target tissue in atrial tissue and the cavity is the atria, wherein the expanding includes expanding the second electrode by inflating the electrode within the atria.

17. A method for performing a maze procedure to treat atrial fibrillation by ablating atrial tissue to form at least one lesion in the atrial tissue, the method comprising:

providing a first RF electrode coupled to one pole of an RF current source;

providing a second RF electrode electrically coupled to the other pole of the RF current source;

inserting the second electrode into the atrial chamber; and

disposing the first electrode against the target tissue and drawing paths with the first electrode to form the maze lesions while applying RF current between the first and second electrodes to ablate the target tissue in a maze pattern,

wherein the inserting is done through an incision made at the atrial appendage.

18. A method as in claim 17, wherein the incision is made to remove the right atrial appendage and the method does not include making any other incisions in the right atrium.

19. A method as in claim 17, wherein the incision is made to remove the right atrial appendage and wherein the method does not include making an incision from the right atrial appendage incision toward the inferior vena caval orifice.

20. A method as in claim 17, wherein the incision is made to remove the right atrial appendage, and wherein the method does not include making a posterior longitudinal incision starting caudal to the superior caval cannulation site at the dorsal aspect of the right atrium.