Ablation electrode

• US 5,718,701 A
• Filed: 03/18/1996
• Issued: 02/17/1998
• Est. Priority Date: 08/11/1993
• Status: Expired due to Term

• Current Assignee: Merit Medical Systems, Inc., Philadelphia Heart Institute
• Original Assignee: Electro-Catheter Corporation
• Inventors: Schwartzman, David S., Shai, Isaac, Marchlinski, Frank E.
• Primary Examiner(s): Cohen, Lee S.
• Application Number:
  US08/616,969
• Time in Patent Office: 701 Days
• Field of Search: 607/99, 607/101, 607/102, 607/119, 607/122, 606/41, 606/45, 606/49, 128/642, 128/734, 128/736
• 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 2018/00351 Heart
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/00815 measured by a thermistor
• CPC Class Codes: A61B 2018/00821 measured by a thermocouple
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/1497 Electrodes covering only part of the probe circumference
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/0565 Electrode heads
• CPC Class Codes: A61N 1/06 for high-frequency therapy
• CPC Class Codes: A61N 1/40 Applying electric fields by inductive or capacitive coupling microwave apparatus A61N5/00; Applying radio-frequency signals

Abstract

An electrode catheter is provided for ablation of arrhythmogenic tissue in a malperforming heart and includes an elongated catheter tube having longitudinally spaced apart proximal and distal ends. At least one electrode for ablation of the arrhythmogenic tissue in a targeted region of the patient is carried on the catheter tube, preferable at or proximate the distal end of the catheter tube. One such electrode may be located at the distal tip of the catheter and configured in the shape of a generally flat disk that substantially conforms to the contour of the targeted region and such that the ratio of the surface area of the tissue-contacting end face to that of a side wall portion of the electrode is greater than 1.0. A conductor is arranged through the elongated catheter tribe and is coupled with the electrode at the distal end, while an energy source is electrically coupled to the conductor at the proximal end of the catheter tube for supplying energy to the electrode for ablation of the arrhythmogenic tissue. A temperature sensor is disposed in the electrode for dynamically sensing the temperature of the targeted region and for use in controlling the amount Of energy supplied to the electrode tip to maintain a predetermined temperature at the targeted region.

Claims

1. An electrode catheter, comprising:

an elongated catheter tube having proximal and distal ends and an insulated portion at the distal end thereof; and

a catheter tip portion comprising conductive electrode means carried at the distal end of the tube for ablation of targeted tissue in a patient, said conductive electrode means comprising a bottom face and a sidewall extending proximally from the bottom face, said insulated portion of said catheter tube being secured about a first portion of the sidewall such that said bottom face and a second portion of said sidewall of said electrode means are exposed at the distal end of said elongated catheter tube, said bottom face defining an end face having a first surface area intended for contact with the targeted tissue and said second portion of said sidewall defining a second surface area, the ratio of the first surface area to the second surface area being greater than 1;

wherein a ratio of a first impedance of a circuit comprising said conductive electrode means when said end face is in contact with the targeted tissue to a second impedance of said circuit when said end face is in contact with a nontreatment region is greater than approximately 1.5.

2. A catheter according to claim 1, wherein said end face is configured in a shape selected from the group consisting of a disk, an ellipse and a polygon.

3. A catheter according to claim 2, wherein said end face has a substantially concave contour.

4. A catheter according to claim 2, wherein said end face has a substantially convex contour.

5. A catheter according to claim 1, further comprising energy supply means coupled to said electrode means at the proximal end of said catheter tube for supplying energy to said conductive electrode means for ablation of the targeted tissue.

6. A catheter according to claim 5, further comprising wiring means extending through said elongated catheter tube for conductively coupling said conductive electrode means to said energy supply means.

7. A catheter according to claim 6, further comprising a temperature sensing means disposed in the bottom of said conductive electrode means for sensing a temperature of the targeted tissue.

8. A catheter according to claim 7, wherein said energy supply means is operatively responsive to said temperature sensing means for maintaining a predetermined temperature of the targeted tissue.

9. A catheter according to claim 5, wherein said energy supply means supplies one of DC energy and radio frequency energy to said conductive electrode means.

10. A catheter according to claim 1, wherein said ratio of the first surface area to the second surface area is greater than 5.

11. A catheter according to claim 1, wherein said ratio of the first surface area to the second surface area is greater than 10.

12. A catheter tip portion for dependency from a distal end of an electrode catheter, comprising:

conductive electrode means for ablation of targeted tissue in a patient, said conductive electrode means comprising a bottom face and a sidewall extending proximally from the bottom face, said bottom face defining an end face having a first surface area intended for contact with the targeted tissue and said sidewall defining a second surface area, the ratio of the first surface area to the second surface area being greater than 1;

wherein a ratio of a first impedance of a circuit comprising said conductive electrode means when said end face is in contact with the targeted tissue to a second impedance of said circuit when said end face is in contact with a nontreatment region is greater than 1.5.

13. A catheter tip portion according to claim 12, wherein said end face is configured in a shape selected from the group consisting of a disk, an ellipse and a polygon.

14. A catheter tip portion according to claim 13, wherein said end face has a substantially concave contour.

15. A catheter tip portion according to claim 12, further comprising energy supply means coupled to said electrode means for supplying energy to said conductive electrode means for ablation of the targeted tissue.

16. A catheter tip portion according to claim 12, wherein said ratio of the first surface area to the second surface area is greater than 5.

17. A catheter tip portion according to claim 12, wherein said ratio of the first surface area to the second surface area is greater than 10.

18. In a method for ablating targeted tissue in a patient, a method of confirming that an end face of a catheter is in contact with the targeted tissue, comprising the steps of:

providing an electrode catheter comprising;

an elongated catheter tube having proximal and distal ends and an insulated portion at the distal end thereof, and

a catheter tip portion comprising conductive electrode means carried at the distal end of the tube for ablation of targeted tissue in a patient, the conductive electrode means comprising a bottom face and a sidewall extending proximally from the bottom face, the insulated portion of the catheter tube being secured about a first portion of the sidewall such that the bottom face and a second portion of the sidewall of the conductive electrode means are exposed at the distal end of the elongated catheter tube, the bottom face defining an end face for contact with the targeted tissue, and such that a ratio of a first impedance of a circuit comprising said conductive electrode means when the end face is in contact with the targeted tissue to a second impedance of said circuit when the end face is in contact with a nontreatment region is greater than 1.5;

positioning the end face by moving the conductive electrode means from a first position wherein the end face is in contact with a nontreatment region to a second position;

measuring the impedance of a circuit comprising the conductive electrode means at the first and second positions; and

confirming that the end face is in contact with the targeted tissue in the second position when the impedance measured in said measuring step in the second position is at least approximately 50% greater than the impedance measured in the first position.

19. In a method according to claim 18, further comprising the step of supplying energy to the conductive electrode means for ablation of the targeted tissue.

20. In a method according to claim 19, further comprising the step of sensing the temperature of the targeted tissue.

21. A method according to claim 20, further comprising the step of controlling the supply of energy in said supplying step to the conductive electrode means in accordance with the temperature sensed in said sensing step to maintain a predetermined temperature at the targeted tissue.

22. A method for ablating targeted tissue of initially unknown size and shape within a patient'"'"'s body, comprising the steps of:

(a) determining the shape of the targeted tissue;

(b) selecting a conductive electrode to conform to said shape of the targeted tissue determined in said step (a), said conductive electrode being of fixed size and shape and carried on an elongated catheter tube;

(c) positioning said elongated catheter tube so that said conductive electrode selected in said step (b) is positioned within the patient'"'"'s body in complementary contact with the targeted tissue; and

(d) supplying energy to said selected conductive electrode to ablate the targeted tissue.

23. An electrode catheter for ablating targeted tissue within a patient'"'"'s body, the targeted tissue having a predetermined shape, said electrode catheter comprising:

an elongated catheter tube having proximal and distal ends and an insulated portion arranged proximate said distal end of the catheter tube;

a plurality of electrically-conductive ablation electrodes arranged proximate said distal end of said elongated catheter tube for placement against target tissue to be ablated and variously shaped to conform to anticipated shapes of target tissue to be ablated through contact with the target tissue, said plurality of ablation electrodes being electrically and thermally insulated from one another by said insulated portion; and

means for selecting one of said plurality of ablation electrodes that most closely conforms to the predetermined shape of the targeted tissue and for supplying energy to said selected one of said ablation electrodes for ablating the targeted tissue.

24. An electrode catheter according to claim 23, wherein at least one of said plurality of electrically-conductive ablation electrodes is carried at said distal end of said elongated catheter tube.

25. An electrode catheter according to claim 23, wherein said plurality of electrically-conductive ablation electrodes comprise first and second electrodes carried at said distal end of said elongated catheter, wherein said first and second electrodes are electrically and thermally insulated from each other by said insulated portion.

26. An electrode catheter according to claim 23, wherein said elongated catheter tube has a distal region proximate said distal end, and wherein said plurality of electrically-conductive ablation electrodes comprise a peripheral electrode carried on a peripheral wall at said distal region and extending about a fractional portion of a periphery of said elongated catheter tube, said electrically-conductive ablation electrode having a shape substantially conforming to the predetermined shape of the targeted tissue.

27. An electrode catheter according to claim 23, wherein at least one of said plurality of electrically-conductive ablation electrodes is configured in a shape selected from the group consisting of a disk, an ellipse, a semi-circle and a polygon.

28. An electrode catheter according to claim 23, wherein at least one of said plurality of electrically-conductive ablation electrodes has a contour selected from a substantially concave contour and a substantially convex contour.

29. An electrode catheter according to claim 23, wherein each of said plurality of electrically-conductive ablation electrodes comprises a respective temperature sensor for monitoring the temperature of each ablation electrode, and wherein said means for supplying energy is operatively responsive to said temperature means of the selected ablation electrode for maintaining a predetermined temperature of the targeted tissue.

30. An electrode catheter for ablating targeted tissue within a patient'"'"'s body, said targeted tissue having a predetermined shape and size, said electrode catheter comprising:

an elongated catheter tube comprising an insulated portion and having proximal and distal ends and a distal region proximate said distal end;

a first electrically-conductive ablation electrode carried on a peripheral wall at said distal region and extending about a fractional portion of a periphery of said elongated catheter tube, said first electrically-conductive ablation electrode being configured so as to have a shape substantially conforming to the predetermined shape of the targeted tissue;

an electrically-conductive ablation tip electrode carried at the distal end of said elongated catheter tube, wherein said ablation tip electrode is electrically and thermally insulated from said first ablation electrode by said insulated portion; and

means for selecting the one of said first ablation electrode and said ablation tip electrode that most closely conforms to at least one of the predetermined shape and size of the targeted tissue and for supplying energy to said selected electrode for ablating the targeted tissue.

31. An electrode catheter according to claim 30, wherein said electrode catheter further comprises:

a second electrically-conductive ablation electrode carried on a peripheral wall of the catheter tube at said distal region and extending about a fractional portion of a periphery of said elongated catheter tube, said second ablation electrode being electrically and thermally insulated and separated from said first ablation electrode by said insulated portion; and

wherein said means for selecting further comprises means for selecting the one of said first and second ablation electrodes and said ablation tip electrode that most closely conforms to at least one of the predetermined shape and size of the targeted tissue and for supplying energy to said selected one electrode for ablating the targeted tissue.

32. An electrode catheter according to claim 31, wherein at least one of said first electrically-conductive ablation electrode, said second electrically-conductive ablation electrode, and said electrically-conductive ablation tip electrode has a contour selected from a substantially concave contour and a substantially convex contour.