Multipolar, virtual-electrode catheter with at least one surface electrode and method for ablation

• US 20070027448A1
• Filed: 07/27/2005
• Published: 02/01/2007
• Est. Priority Date: 07/27/2005
• Status: Active Grant

• Current Assignee: St. Jude Medical (Abbott Laboratories Incorporated)
• Original Assignee: St. Jude Medical (Abbott Laboratories Incorporated)
• Inventors: Belhe, Kedar, Paul, Sauray
• Granted Patent: US 7,879,030 B2
• Time in Patent Office: Days
• US Class Current: 606/41
• 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 2018/1472 for use with liquid electrolyte, e.g. virtual electrodes

Abstract

Virtual-electrode catheters and methods for using such virtual-electrode catheters are disclosed. For example, bipolar and multipolar, virtual-electrode catheters having at least one internal electrode and at least one surface electrode, and methods of using these catheters for treatment of cardiac arrhythmias via, for example, radiofrequency (RF) ablation are disclosed. The catheters may comprise a catheter body with an internal lumen extending within it and adapted to flowingly receive a conductive fluid. An exit feature defining a flow path from the internal lumen to the catheter'"'"'s outer surface may exist through a sidewall of the catheter body. A conductor is mounted within the internal lumen adjacent to the exit feature and is adapted to deliver treatment energy to the tissue via the conductive fluid in the internal lumen. At least one surface electrode is mounted on the outer surface of the catheter body adjacent to the exit feature.

Claims

1. A virtual-electrode catheter for treatment of tissue, the catheter comprising a catheter body comprising a sidewall and an outer surface;

a first internal lumen extending within said catheter body and adapted to flowingly receive a conductive fluid;

an exit feature comprising a flow path from said first internal lumen through said catheter body sidewall and said outer surface, said exit feature being adapted to permit the conductive fluid to exit from said first internal lumen toward the tissue;

an internal flexible conductor mounted within said first internal lumen adjacent to said exit feature and an inner surface of said catheter body sidewall, wherein said internal flexible conductor is adapted to deliver treatment energy to the tissue via the conductive fluid in said first internal lumen; and

at least one surface electrode mounted on said outer surface of said catheter body adjacent to said exit feature.

2. The virtual-electrode catheter of claim 1, wherein said exit feature is selected from the group consisting of a plurality of exit portholes, at least one exit slot, and a plurality of micro-pores.

3. The virtual-electrode catheter of claim 2, wherein said exit feature comprises a plurality of exit portholes arranged along said outer surface of said catheter body.

4. The virtual-electrode catheter of claim 3, wherein said plurality of exit portholes are symmetrically distributed about a porthole centerline.

5. The virtual-electrode catheter of claim 4, wherein said internal flexible conductor comprises an internal coil electrode, and wherein said internal coil electrode extends adjacent to each exit porthole of said plurality of exit portholes.

6. The virtual-electrode catheter of claim 5, wherein said internal coil electrode comprises a multitude of turns;

wherein said multitude of turns of said internal coil electrode are adapted to allow the conductive fluid to pass between adjacent turns; and

wherein at least two of said multitude of turns of said internal coil electrode are present between adjacent portholes of said plurality of exit portholes.

7. The virtual-electrode catheter of claim 4, wherein said porthole centerline extends longitudinally along said outer surface of said catheter body.

8. The virtual-electrode catheter of claim 2, wherein said exit feature comprises an exit slot extending longitudinally along said outer surface of said catheter body.

9. The virtual-electrode catheter of claim 8, wherein said internal flexible conductor comprises an internal coil electrode, and wherein said internal coil electrode extends over an entire length of said exit slot.

10. The virtual-electrode catheter of claim 1, wherein said internal flexible conductor comprises an internal coil electrode having a multitude of turns;

and wherein said multitude of turns of said internal coil electrode are adapted to allow the conductive fluid to pass between adjacent turns.

11. The virtual-electrode catheter of claim 1, wherein said internal flexible conductor is selected from the group consisting of a coil electrode, a wire strand electrode, and a tubular electrode.

12. The virtual-electrode catheter of claim 11, wherein said internal flexible conductor is constructed from metal.

13. The virtual-electrode catheter of claim 11, wherein said internal flexible conductor comprises a coil electrode having an annular cross-sectional shape, wherein said first internal lumen has an elliptical cross-sectional shape, wherein said coil electrode extends longitudinally within said first internal lumen, and wherein a minor axis of said elliptical cross-sectional shape of said first internal lumen is substantially the same length as an outside diameter of said annular cross-sectional shape of said coil electrode.

14. The virtual-electrode catheter of claim 13, wherein a lateral cross section of said coil electrode and said first internal lumen defines a flow channel comprising a circular central region, a forward crescent-moon-shaped region, a rearward crescent-moon-shaped region.

15. The virtual-electrode catheter of claim 1, wherein said internal flexible conductor comprises an internal coil electrode having a multitude of turns, wherein said internal coil electrode extends longitudinally within said first internal lumen, and wherein said internal coil electrode is at least partially embedded in a longitudinally-extending internal sidewall of said first internal lumen.

16. The virtual-electrode catheter of claim 1, wherein said at least one surface electrode is selected from the group consisting of a conductive coil and a conductive tube.

17. The virtual-electrode catheter of claim 16, wherein said surface electrode is constructed from metal.

18. The virtual-electrode catheter of claim 16, wherein said at least one surface electrode is mounted in and retained by a longitudinally-extending, C-shaped channel on said outer surface of said catheter body.

19. The virtual-electrode catheter of claim 16, wherein said at least one surface electrode comprises a thermally and electrically conductive tube, and wherein said catheter further comprises a thermal sensor within a core of said thermally and electrically conductive tube.

20. The virtual-electrode catheter of claim 1, wherein said at least one surface electrode is a cooled electrode.

21. The virtual-electrode catheter of claim 20, wherein said at least one surface electrode comprises a coil of wound, tubular metal adapted to carry a cooling fluid.

22. The virtual-electrode catheter of claim 20, wherein said at least one surface electrode comprises a hollow tube constructed from a thermally and electrically conductive material and adapted to carry a surface-electrode cooling fluid.

23. The virtual-electrode catheter of claim 22, wherein said hollow-tube surface electrode includes an open distal end adapted to permit the surface-electrode cooling fluid to exit said hollow-tube surface electrode.

24. The virtual-electrode catheter of claim 20, wherein said first internal lumen is adapted to convey conductive fluid from a first fluid source, and wherein said at least one surface electrode comprises a hollow tube constructed from a thermally and electrically conductive material and adapted to convey a surface-electrode cooling fluid from a second fluid source.

25. The virtual-electrode catheter of claim 1, wherein said at least one surface electrode comprises a plurality of surface electrodes on said outer surface of said catheter body, and wherein at least one of said plurality of surface electrodes acts as a dispersive electrode.

26. The virtual-electrode catheter of claim 1, wherein said at least one surface electrode comprises a first surface electrode and a second surface electrode.

27. The virtual-electrode catheter of claim 26, wherein said first surface electrode comprises a first conductive coil along a first side of a longitudinal centerline of said exit feature, wherein said second surface electrode comprises a second conductive coil along a second side of said longitudinal centerline of said exit feature, and wherein said first conductive coil and said second conductive coil straddle said exit feature longitudinal centerline.

28. The virtual-electrode catheter of claim 1, wherein said at least one surface electrode comprises a thermally and electrically conductive coil, and wherein said catheter further comprises a longitudinally-extending thermal sensor that extends within said thermally and electrically conductive surface electrode coil.

29. The virtual-electrode catheter of claim 1, wherein said catheter further comprises at least one temperature sensor on said outer surface of said catheter body next to said at least one surface electrode.

30. The virtual-electrode catheter of claim 29, wherein said at least one temperature sensor is selected from the group consisting of a thermocouple, a thermister, and a fiber optic sensor.

31. The virtual-electrode catheter of claim 1, wherein said at least one surface electrode is metal, and wherein said internal flexible conductor is metal.

32. The virtual-electrode catheter of claim 1, wherein said virtual-electrode catheter further comprises a terminal sphere, and wherein said internal flexible conductor comprises a distal projection that is anchored in said terminal sphere.

33. The virtual-electrode catheter of claim 32, wherein said virtual-electrode catheter further comprises a release hole that extends from said first internal lumen through said terminal sphere and through said outer surface of said catheter body, and wherein said release hole is adapted to inhibit stagnation of said conductive fluid.

34. The virtual-electrode catheter of claim 1, wherein said catheter body defines a second longitudinally-extending internal lumen adapted to slippingly receive a rail.

35. The virtual-electrode catheter of claim 34, wherein said rail comprises a nickel-titanium wire.

36. The virtual-electrode catheter of claim 34, wherein said rail has a rounded-rectangular cross-sectional configuration that complements a cross-sectional configuration of said second lumen.

37. A virtual-electrode catheter for tissue ablation, the catheter comprising a catheter body having an outer surface, an internal lumen, and a fluid exit feature extending between said internal lumen and said outer surface, wherein said exit feature is adapted to be placed against tissue, and wherein said internal lumen is adapted to deliver conductive fluid to said fluid exit feature;

an active internal electrode mounted within said internal lumen of said catheter body and adapted to contact said conductive fluid, wherein said active internal electrode is electrically connected to a source of ablative energy and is adapted to impart said ablative energy to the tissue via said conductive fluid; and

at least one passive external electrode mounted on said outer surface of said catheter body adjacent to said fluid exit feature, wherein said at least one passive external electrode is electrically connected to said source of ablative energy and is adapted to return at least a portion of said ablative energy to said source of ablative energy, whereby, upon activation of said source of ablative energy, an electric field is created between said active internal electrode and said at least one passive external electrode, and in the tissue adjacent to said fluid exit feature.

38. The virtual-electrode catheter of claim 37, wherein said fluid exit feature is arranged along a longitudinally-extending exit feature centerline, and wherein said at least one passive external electrode further comprises a first surface electrode mounted on said outer surface of said catheter body adjacent to a first side of said longitudinally-extending exit feature centerline;

and

a second surface electrode mounted on said outer surface of said catheter body adjacent to a second side of said longitudinally-extending exit feature centerline.

39. A multipolar, virtual-electrode catheter for performing radiofrequency ablation of cardiac tissue, the catheter comprising a catheter body defining an outer surface and an internal lumen, wherein said internal lumen is adapted to carry conductive fluid;

at least two metal electrodes positioned on said outer surface of said catheter body, wherein said at least two metal electrodes are adapted for placement against the cardiac tissue;

a metal conductor positioned within said internal lumen and adapted to impart radiofrequency energy to the conductive fluid;

at least one opening on said outer surface of said catheter, said at least one opening adapted to create a flow path for the conductive fluid in said internal lumen to flow out of the catheter and impinge upon the cardiac tissue as a virtual-electrode; and

at least one temperature sensor on said outer surface of said catheter body in close juxtaposition to said at least two metal electrodes.

40. A method for tissue ablation using a virtual-electrode catheter comprising a catheter body with a sidewall and an outer surface;

a first internal lumen extending within said catheter body and adapted to flowingly receive a conductive fluid;

an exit feature comprising a flow path from said first internal lumen through said catheter body sidewall and said outer surface, said exit feature being adapted to permit the conductive fluid to exit from said first internal lumen toward the tissue;

an internal flexible conductor mounted within said first internal lumen adjacent to said exit feature and an inner surface of said catheter body sidewall, wherein said internal flexible conductor is adapted to deliver ablation energy to the tissue via the conductive fluid in said first internal lumen; and

at least one surface electrode mounted on said outer surface of said catheter body adjacent to said exit feature, the method comprising the steps of

(a) flowing the conductive fluid within said first internal lumen and out of said exit feature;

(b) delivering ablation energy to said internal flexible conductor;

(c) generating an electric field between said internal flexible conductor and said at least one surface electrode; and

(d) terminating delivery of said ablation energy upon creating of a lesion in the tissue.

41. A method for tissue ablation using a virtual-electrode catheter, the method comprising the steps of

(a) placing against the tissue both a first dispersive surface electrode and a second dispersive surface electrode, wherein said first and second surface electrodes are mounted on an outer surface of a catheter body of the virtual-electrode catheter;

(b) flowing a conductive fluid trough a first internal lumen extending within said catheter body toward an exit feature that is adjacent to said first and second surface electrodes;

(c) delivering ablation energy to an active internal flexible conductor within said first internal lumen;

(d) generating a concentrated electric field between said internal flexible conductor and at least one of said first and second surface electrodes; and

(e) terminating delivery of said ablation energy after creation of a lesion in the tissue.

42. The method of claim 41, wherein said step (d) further comprises operating said virtual-electrode catheter in a first mode, thereby generating said electric field only between said internal flexible conductor and said first surface electrode.

43. The method of claim 41, wherein said step (d) further comprises operating said virtual-electrode catheter in a second mode, thereby generating said electric field between said internal flexible conductor and both of said first and second surface electrodes.