Polyphase Electrosurgical System and Method

• US 20100030210A1
• Filed: 08/01/2008
• Published: 02/04/2010
• Est. Priority Date: 08/01/2008
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Paulus, Joseph A.
• Granted Patent: US 9,700,366 B2
• Time in Patent Office: Days
• US Class Current: 606/38
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 2018/00654 with individual control of each of a plurality of energy emitting elements
• CPC Class Codes: A61B 2018/00684 using lookup tables
• CPC Class Codes: A61B 2018/00732 Frequency
• CPC Class Codes: A61B 2018/0075 Phase
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/128 generating two or more frequencies
• CPC Class Codes: A61B 2018/143 multiple needles

Abstract

A polyphase electrosurgical system and method are provided. In embodiments, a radiofrequency generator having the capability of delivering a plurality of independent electrosurgical signals is disclosed. An electrosurgical instrument having an array of electrodes that correspond to the plurality of signals may be used to deliver the electrosurgical signals to tissue. In embodiments, three RF signals having a phase offset of about 120° therebetween, i.e., a three-phase configuration, may be used to achieve a balanced delivery of electrosurgical energy, which may lead to increased rates of energy delivery, improved control of tissue ablation regions, and improved operative outcomes. The phase, amplitude, and/or frequency of each signal may be independently variable in response to user inputs and/or biological parameters such as tissue impedance or return electrode current.

Claims

1. A method of delivering electrosurgical energy to tissue, comprising:

providing an electrosurgical instrument having at least three electrodes;

coupling the electrosurgical instrument to a radiofrequency generator;

applying the electrodes to tissue; and

providing at least three alternating-current electrosurgical signals to the electrodes, respectively, wherein the difference in phase between the alternating-current electrosurgical signals is about 120 degrees.

2. The method according to claim 1, further comprising providing a return path for at least part of at least one of the alternating-current electrosurgical signals to the radiofrequency generator.

3. The method according to claim 1, wherein providing at least three alternating-current electrosurgical signals to the electrodes is provided in response to a user input.

4. The method according to claim 1, further comprising:

sensing at least one biological parameter of the tissue; and

altering an amplitude of at least one of the alternating-current electrosurgical signals in response to the biological parameter.

5. The method according to claim 4, wherein the biological parameter is indicative of the formation of bubble steam in proximity to at least one of the electrodes.

6. The method according to claim 4, wherein the biological parameter is indicative of the formation of eschar in proximity to at least one of the electrodes.

7. The method according to claim 4, wherein the biological parameter is indicative of the circuit impedance corresponding to at least one of the electrodes.

8. A method of ablating tissue, comprising:

providing an electrosurgical instrument having at least three electrodes;

coupling the electrosurgical instrument to a radiofrequency generator;

applying the electrodes to tissue; and

providing at least three alternating-current electrosurgical signals to the electrodes, respectively, wherein the difference in phase between the alternating-current electrosurgical signals is variable from about 1 degrees to about 120 degrees.

9. The method according to claim 8, further comprising:

sensing at least one biological parameter of the tissue; and

altering the phase of at least one of the alternating-current electrosurgical signals in response to the biological parameter.

10. The method according to claim 9, wherein the biological parameter is indicative of the formation of bubble steam in proximity to at least one of the electrodes.

11. The method according to claim 9, wherein the biological parameter is indicative of the formation of eschar in proximity to at least one of the electrodes.

12. The method according to claim 9, wherein the biological parameter is indicative of the circuit impedance corresponding to at least one of the electrodes.

13. The method according to claim 9, wherein the biological parameter is indicative of the size of the region of ablated tissue.

14. The method according to claim 9, wherein the biological parameter is indicative of the shape of the region of ablated tissue.

15. The method according to claim 8, wherein the at least three electrodes includes a plurality of groups of electrodes, each group having an equal number of electrodes, and wherein the total number of electrodes is equal to a multiple of three, the method further comprising:

sensing at least one biological parameter of the tissue; and

altering a signal property of at least one of the electrode groups in response to the biological parameter.

16. The method according to claim 15, wherein the signal property of the altering step is the phase offset.

17. The method according to claim 15, wherein the signal property of the altering step is the amplitude.

18. A polyphase electrosurgical system, comprising:

a controller module;

a generator module operably coupled to the controller module, the generator module configured to generate a plurality of radiofrequency signals having a phase offset therebetween and to provide the plurality of radiofrequency signals to respective outputs;

an electrosurgical instrument having a plurality of electrodes disposed in spaced relation, the electrodes operably coupled to the respective outputs of the generator module corresponding to the plurality of radiofrequency signals; and

an actuator operably coupled to the controller for activating the generator module.

19. The polyphase electrosurgical system of claim 18, wherein the phase offset is selected from the group consisting of about 120 degrees, about 90 degrees, and in the range of about 1 degrees to about 180 degrees.

20. The polyphase electrosurgical system of claim 18, further comprising:

at least one digital-to-analog converter;

a storage device having a digitized representation of a waveform stored therein;

a processor operably coupled to the digital-to-analog converter and the storage device, the processor configured to execute a set of programmable instructions for generating the plurality of radiofrequency signals.

21. The polyphase electrosurgical system of claim 20, further including multiple pointers to data points of the digitized waveform table corresponding to the desired phase offset between the radiofrequency signals.

22. The polyphase electrosurgical system of claim 20, wherein the set of programmable instructions is configured to vary the amplitude of at least one of the radiofrequency signals.

23. The polyphase electrosurgical system of claim 20, wherein the set of programmable instructions is configured to vary the frequency of at least one of the radiofrequency signals.

24. The polyphase electrosurgical system of claim 18, farther comprising a display module operably coupled to the controller module for displaying operational parameters.

25. The polyphase electrosurgical system of claim 18, further comprising a return electrode operably coupled to the generator module for providing a return path for at least one of the radiofrequency signals.

26. The polyphase electrosurgical system of claim 18, wherein the actuator is selected from the group consisting of a handswitch and a footswitch.

27. The polyphase electrosurgical system of claim 20, further comprising:

a sensor in communication with at least one electrode for sensing a biological parameter, the sensor operatively coupled to the controller, wherein the set of programmable instructions is configured to vary at least one property of the radiofrequency signals in response to the biological parameter.

28. A method of delivering electrosurgical energy to tissue, comprising:

providing an electrosurgical instrument having at least three electrodes, wherein at least two of the electrodes are active electrodes and at least one of the electrodes is a return electrode;

coupling the electrosurgical instrument to a radiofrequency generator;

applying the electrodes to tissue;

establishing a target return current;

providing a plurality of alternating-current electrosurgical signals to the active electrodes, respectively, wherein a property of the signals is variable;

sensing the current in the return electrode; and

varying the property of the signals to more closely conform the sensed current to the target return current.

29. The method in accordance with claim 28, wherein the property of the signals is the difference in phase between the signals.

30. The method in accordance with claim 28, wherein the properly of the signals is the difference in amplitude between the signals.