Radio-frequency generator for powering an ablation device

• US 6,508,815 B1
• Filed: 05/06/1999
• Issued: 01/21/2003
• Est. Priority Date: 05/08/1998
• Status: Expired due to Term

• Current Assignee: Cytyc Surgical Products, LLC (Hologic Incorporated)
• Original Assignee: Novacept Inc. (Hologic Incorporated)
• Inventors: Strul, Bruno, Kane, Mark Leo, Truckai, Csaba, Sampson, Russel Mahlon
• Primary Examiner(s): ROLLINS, ROSILAND STACIE
• Application Number:
  US09/306,480
• Time in Patent Office: 1,356 Days
• Field of Search: 606/34, 606/37, 606/38, 606/39, 606/40, 606/41, 606/42, 606/45, 606/49
• US Class Current: 606/34
• CPC Class Codes: A61B 18/1206 Generators therefor
• CPC Class Codes: A61B 18/1485 having a short rigid shaft for accessing the inner body through natural openings
• 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 2018/00214 Expandable means emitting energy, e.g. by elements carried thereon
• CPC Class Codes: A61B 2018/00559 Female reproductive organs
• CPC Class Codes: A61B 2018/00684 using lookup tables
• CPC Class Codes: A61B 2018/00702 Power or energy
• CPC Class Codes: A61B 2018/00761 Duration
• CPC Class Codes: A61B 2018/00779 Power or energy
• CPC Class Codes: A61B 2018/00875 Resistance or impedance
• CPC Class Codes: A61B 2018/00916 with means for switching or controlling the main function of the instrument or device
• CPC Class Codes: A61B 2018/124 switching the output to different electrodes, e.g. sequentially
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61B 2218/007 Aspiration

Abstract

An apparatus and method for use in performing ablation of organs and other tissues includes a radio frequency generator which provides a radio frequency signal to ablation electrodes. The power level of the radio frequency signal is determined based on the subject area of ablation. The radio frequency signal is coupled with the ablation electrodes through a transformation circuit. The transformation circuit includes a high impedance transformation circuit and a low impedance transformation circuit. The high or low impedance transformation circuit is selected based on the impedance of the ablation electrodes in contact with the subject tissue. Vacuum level, impedance level, resistance level, and time are measured during ablation. If these parameters exceed determinable limits the ablation procedure is terminated.

Claims

1. A radio-frequency generator suitable for energizing an ablation device comprising:

a power supply;

a first winding having a first impedance and configured to electrically couple with an electromagnetic ablation device;

a second winding having a second impedance different from the first impedance and configured to electrically couple with the electromagnetic ablation device; and

a switch operationally coupled with the first and the second winding wherein the switch selects between the first winding to energize the ablation device by creating an electrical connection between the power source, first winding, and ablation device, and the second winding to energize the ablation device by creating an electrical connection between the power source, second winding, and ablation device.

2. The radio-frequency generator of claim 1, wherein the first and second windings comprise first and second load windings, respectively, and wherein the first and second load windings are coupled with a power winding.

3. The radio-frequency generator of claim 2, wherein the first load winding comprises a portion of the second load winding and wherein the power winding and the first and second load winding comprise a two-tap transformer.

4. The radio-frequency generator of claim 2, wherein the power winding comprises a first and a second power winding and wherein the first power winding is coupled with the first load winding thereby forming a first transformer and the second power winding is coupled with the second load winding thereby forming a second transformer and wherein the switch selects between the first and second transformer.

5. The radio-frequency generator of claim 1, further comprising:

an impedance detection circuit having a connection to the ablation device and configured to generate an impedance signal indicating an impedance of the ablation device in contact with a tissue; and

a control circuit operationally coupled with the impedance detection circuit and the switch wherein the control circuit controls the selection between the first and second winding based on the impedance signal.

6. The radio-frequency generator of claim 5, wherein the control circuit selects the winding having the impedance characteristic closest to that of the ablation device.

7. The radio-frequency generator of claim 1, further comprising:

a power supply operationally coupled with the first and second windings;

an impedance detection circuit having a connection to the ablation device and configured to generate an impedance signal; and

a regulator operationally coupled with the impedance detection circuit and the power supply, and configured to control the power supply based on the impedance signal.

8. The radio-frequency generator of claim 7, further comprising input means for receiving input corresponding to dimensions of an ablation region, and a power selector operationally coupled with the regulator, wherein the power selector uses the dimensions to determine an electrical power level for ablation.

9. A radio-frequency generator suitable for energizing an ablation device comprising:

an RF power supply operationally coupled with an ablation device;

an input device for receiving data corresponding to the dimensions of a tissue to be ablated; and

a regulator operationally coupled with the RF power supply and the input device, the regulator responsive to input signals from the input device to control an amount of power supplied to the ablation device by the RF power supply.

10. The radio-frequency generator of claim 9, wherein the input device is configured to receive signals corresponding to the length and width of the tissue.

11. The radio-frequency generator of claim 9, further comprising an impedance detection circuit having a connection to the ablation device and configured to generate an impedance signal indicating the impedance of the ablation device, wherein the regulator is operationally coupled with the impedance detection circuit and wherein the regulator further controls the amount of power based upon the impedance signal.

12. A radio-frequency generator coupled to an ablation device in contact with tissue to be ablated, the radio-frequency generator comprising:

an RF power supply,

a means for coupling the RF power supply to an ablation device wherein a transformation ratio of the coupling means can be adjusted;

a detector for measuring an impedance of an ablation device; and

a feedback loop to vary the transformation ratio of the coupling means to select an impedance of the RF power supply that approximates the impedance of the ablation device in contact with tissue to be ablated.

13. The radio-frequency generator of claim 12 wherein the coupling means includes:

a first winding having a first impedance;

a second winding having a second impedance different from the first impedance; and

a switch operationally coupled with the first and the second winding, the switch responsive to feedback from the feedback loop to select between the first and second winding.

14. The radio-frequency generator of claim 13, wherein the first and second windings comprise first and second load windings, respectively, and wherein the first and second load windings are coupled with a power winding.

15. The radio-frequency generator of claim 13, wherein the first load winding comprises a portion of the second load winding and wherein the power winding and the first and second load winding comprise a two-tap transformer.

16. The radio-frequency generator of claim 13, wherein the power winding comprises a first and a second power winding and wherein the first power winding is coupled with the first load winding thereby forming a first transformer and the second power winding is coupled with the second load winding thereby forming a second transformer and wherein the switch selects between the first and second transformer.

17. The radio-frequency generator of claim 13, wherein the feedback loop includes a control circuit operationally coupled with the detector and the switch, wherein the control circuit controls the selection between the first and second winding based on an impedance signal from the detector.

18. The radio-frequency generator of claim 17 wherein the control circuit selects the winding having the impedance characteristic closest to that of the ablation device.

19. The radio-frequency of claim 13 wherein the power supply is operationally coupled with the first and second windings, and wherein the radio-frequency further includes a regulator operationally coupled with the impedance detection circuit and the power supply, the regulator configured to control the power supply based on the impedance signal.

20. The radio-frequency generator of claim 19, further comprising input means for receiving input corresponding to dimensions of an ablation region, and a power selector operationally coupled with the regulator, wherein the power selector uses the dimensions to determine an electrical power level for ablation.