Radio-frequency ablation system using multiple electrodes

• US 20020156472A1
• Filed: 06/10/2002
• Published: 10/24/2002
• Est. Priority Date: 06/07/2000
• Status: Active Grant

• Current Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Original Assignee: Wisconsin Alumni Research Foundation (University of Wisconsin System)
• Inventors: Wright, Andrew S., Haemmerich, Dieter, Johnson, Chris D., Lee, Fred T., Mahvi, David M., Webster, John G.
• Granted Patent: US 8,486,065 B2
• Time in Patent Office: Days
• US Class Current: 606/41
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1477 Needle-like probes
• CPC Class Codes: A61B 2018/00654 with individual control of each of a plurality of energy emitting elements
• CPC Class Codes: A61B 2018/00726 Duty cycle
• CPC Class Codes: A61B 2018/0075 Phase
• CPC Class Codes: A61B 2018/00755 Resistance or impedance
• CPC Class Codes: A61B 2018/00791 Temperature
• CPC Class Codes: A61B 2018/00797 measured by multiple temperature sensors
• CPC Class Codes: A61B 2018/00827 Current
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/124 switching the output to different electrodes, e.g. sequentially
• CPC Class Codes: A61B 2018/143 multiple needles
• CPC Class Codes: A61B 2018/1432 curved
• CPC Class Codes: A61B 2018/1467 using more than two electrodes on a single probe

Abstract

Efficient ablation with multiple electrodes is obtained by rapidly switching electric power to the electrodes. In this way, shielding effects caused by the field around each electrode which would otherwise create cool spots, are avoided. Complex inter-electrode current flows are also avoided.

Claims

1. A radio-frequency ablation system comprising:

at least three electrodes positionable in contact with a patient;

a radio-frequency power source; and

a switch system communicating with the electrodes and the radio-frequency power source to sequentially connect at least one pair of the electrodes to the power source to provide for ablative current flow between connected electrodes while inhibiting current flow between at least one unconnected pair.

2. The radio-frequency ablation system of claim 1 wherein at least one of the electrodes is adapted for application to the skin.

3. The radio-frequency ablation system of claim 2 wherein the sequentially connected one pair always includes the electrode adapted for application to the skin.

4. The radio-frequency ablation system of claim 1 wherein the switch system communicating with the electrodes and the radio-frequency power source sequentially connects only one pair of the electrodes to the power source at a time to provide for ablative current flow between connected electrodes while inhibiting current flow between all other pairs.

5. The radio-frequency ablation system of claim 1 wherein at least two of the electrodes are adapted for insertion into the patient.

6. The radio-frequency ablation system of claim 5 wherein the probes are umbrella electrodes having at least two electrode wires extending from a common shaft.

7. The radio-frequency ablation system of claim 1 wherein the switch system changes the sequentially connected pairs of electrodes.

8. The radio-frequency ablation system of claim 1 wherein the electronic switch controls the relative duration of the connection of the pairs of electrodes to the power supply according to a control parameter selected from the group consisting of impedance between the connected pairs of electrodes, temperature of at least one of the connected pairs of electrodes, a predetermined time setting, and power dissipated between the connected pairs of the electrodes.

9. The radio-frequency ablation system of claim 1 wherein the electronic switch includes a proportional/integral controller, controlling the switching according to a parameter selected from the group consisting of impedance between the connected pairs of electrodes, temperature at at least one of the connected pairs of electrodes, a predetermined time period, and power dissipated between the connected pairs of the electrodes.

10. The radio-frequency ablation system of claim 1 wherein the electrodes define a contact area with the patient having a width and wherein at least two of the electrodes are positioned to have a portion within no more than three times the width of each other.

11. A method of radio-frequency ablation comprising the steps of:

(a) placing at least three electrodes in contact with a patient; and

(b) sequentially connecting pairs of the electrodes to a radio-frequency power source to provide for ablative current flow between a connected pair of electrodes while inhibiting current flow between an unconnected pair.

12. The method as recited in claim 11 wherein at least two of the electrodes are placed in different portions of a single tumor.

13. The method as recited in claim 11 wherein at least two of the electrodes are placed in different tumors.

14. The method as recited in claim 11 wherein at least one of the electrodes is adapted for application to the skin.

15. The radio-frequency ablation system of claim 14 wherein the sequentially connected one pair always includes the electrode adapted for application to the skin.

16. The method recited in claim 11 wherein at least two of the electrodes are adapted for insertion into the patient by a method selected from the group consisting of percutaneously, operatively, and laparoscopically.

17. The method recited in claim 16 wherein the at least two probes are umbrella electrodes having at least two electrode wires extending from a common shaft.

18. The method recited in claim 11 wherein the sequentially connected pairs of electrodes are changed at a frequency substantially greater than 10 kHz.

19. The method recited in claim 11 wherein the relative duration of the sequential connection of the pairs of electrodes to the power supply is according to a control parameter selected from the group consisting of impedance between the connected pairs of electrodes, temperature at least one of the connected pairs of electrodes, and power dissipated between the connected pairs of the electrodes.

20. The method recited in claim 11 wherein the sequential connection is controlled by a proportional/integral controller according to a parameter selected from the group consisting of impedance between the connected pairs of electrodes, temperature at at least one of the connected pairs of electrodes, and power dissipated between the connected pairs of the electrodes.

21. The method recited in claim 11 further including the step of adjusting the radio-frequency power source output according to a control parameter selected from the group consisting of impedance between the connected pairs of electrodes, temperature of at least one of the connected pairs of electrodes, and power dissipated between the connected pairs of the electrodes.

22. The method recited in claim 11 wherein the electrodes define a contact with the patient area having a width and wherein at least two of the electrodes are positioned to have a portion within no more than three times the width of each other.