Electrosurgical apparatus and electrosurgical instrument

Patent metadata

Field	Value
Publication number	US-11344367-B2
Application number	US-201816472181-A
Country	US
Kind code	B2
Filing date	Feb 7, 2018
Priority date	Feb 10, 2017
Publication date	May 31, 2022
Grant date	May 31, 2022

Abstract

An electrosurgical instrument capable of supporting resonance of microwave energy at multiple frequencies. The instrument comprises a coaxial cable and a radiating distal tip portion arranged to receive microwave energy from the coaxial cable. The radiating tip portion consists of a dielectric material having an electrical length selected in conjunction with its dielectric properties at three or more frequencies of microwave energy to support resonance at each frequency. By providing a single device that can effectively couple microwave energy into biological tissue at three or more frequencies, tissue ablation can be performed rapidly with accuracy. The instrument may be used in an apparatus that includes a generator arranged to supply microwave energy at three or more different frequencies.

First claim

The invention claimed is:

1. An electrosurgical instrument for delivering microwave electromagnetic (EM) energy into biological tissue, the instrument comprising:
a coaxial cable for conveying microwave EM energy, the coaxial cable having an inner conductor, an outer conductor, and a first dielectric material separating the inner conductor and the outer conductor; and
a radiating tip portion disposed at a distal end of the coaxial cable to receive microwave EM energy from the coaxial cable, the radiating tip portion comprising a second dielectric material different from the first dielectric material,
wherein the radiating tip portion has an electrical length selected in conjunction with its dielectric properties at three or more frequencies of microwave EM energy to support resonance at the three or more frequencies of microwave EM energy,
wherein the radiating tip is configured to deliver the microwave EM energy at the three or more frequencies, in an alternating or simultaneous manner,
wherein the three or more frequencies of microwave EM energy comprise a first frequency, a second frequency that is lower than the first frequency, and a third frequency that is lower than the first frequency and the second frequency, and
wherein the second dielectric material has a length approximately equal to:
2.5 wavelengths of the microwave EM energy at the first frequency in the second dielectric material;
one wavelength of the microwave EM energy at the second frequency in the second dielectric material; and
half a wavelength of the microwave EM energy at the third frequency in the second dielectric material.

2. An electrosurgical instrument according to claim 1 , wherein the first frequency, second frequency and third frequency are 14.5 GHz, 5.8 GHz, and 2.45 GHz respectively.

3. An electrosurgical instrument according to claim 1 , wherein a physical length L of the second dielectric material substantially satisfies
L=nλ/ 2,

where n is a positive integer, and A is a wavelength of microwave EM energy in the second dielectric material at each of the three of more frequencies of microwave EM energy.

4. An electrosurgical instrument according to claim 1 , wherein the second dielectric material comprises an elongate probe extending distally away from the coaxial cable, the elongate probe having a cylindrical shape with a diameter equal to or less than a diameter of the coaxial cable.

5. An electrosurgical instrument according to claim 1 , wherein the outer conductor extends beyond a distal end of the first dielectric material to enclose a proximal portion of the second dielectric material.

6. An electrosurgical instrument according to claim 1 , wherein the inner conductor extends into the second dielectric material beyond a distal end of the outer conductor.

7. An electrosurgical instrument according to claim 1 , wherein the second dielectric material has a lower impedance than the first dielectric material at each of the three of more frequencies of microwave EM energy.

8. An electrosurgical instrument according to claim 1 , wherein the distal end of the radiating tip portion is tapered to a point.

9. An electrosurgical apparatus for delivering microwave electromagnetic (EM) energy into biological tissue, the apparatus comprising:
a generator arranged to generate microwave EM energy at three or more different frequencies; and
an electrosurgical instrument according to claim 1 , wherein the coaxial cable has a proximal end connected to the generator to receive microwave EM energy therefrom.

10. An electrosurgical apparatus according to claim 9 , wherein the generator comprises three or more separate microwave sources for generating microwave EM energy at a respective one of the three or more different frequencies.

11. An electrosurgical apparatus according to claim 10 , wherein the generator comprises a multiplexer for receiving a signal from each of the three or more separate microwave sources, wherein the multiplexer is arranged to convey each signal to a common signal path that is connected to the coaxial cable.

12. An electrosurgical apparatus according to claim 11 , wherein the multiplexer is operable as a switching unit for selecting a signal to be conveyed on the common signal path.

13. An electrosurgical apparatus according to claim 11 , wherein the multiplexer is operable as a signal combiner to convey two or more of the signals on the common signal path in a simultaneous or quasi-simultaneous manner.

14. An electrosurgical apparatus according to claim 11 , wherein the multiplexer is operable as a time-domain multiplexer.

15. An electrosurgical apparatus according to claim 11 , wherein the multiplexer is operable as a filter multiplexer.

16. An electrosurgical apparatus according to claim 9 including a surgical scoping device having flexible instrument cord for non-invasive insertion to a treatment site, wherein the instrument cord includes an instrument channel, and wherein the electrosurgical instrument is dimensioned to be insertable within the instrument channel.

17. An electrosurgical apparatus according to claim 9 , wherein the generator is operable to select an energy delivery profile for delivering the microwave EM energy at the three or more different frequencies.

18. An electrosurgical apparatus according to claim 17 , wherein the generator is operable under the selected energy delivery profile to:
deliver a first signal during a first ablation period, the first signal comprises microwave EM energy having predominantly the first frequency;
deliver a second signal during a second ablation period, the second signal comprises microwave EM energy having predominantly the second frequency; and
deliver a third signal during a third ablation period, the third signal comprises microwave EM energy having predominantly the third frequency.

19. An electrosurgical apparatus according to claim 18 , wherein the second frequency is less than half the first frequency.

20. An electrosurgical apparatus according to claim 18 , wherein the third frequency less than half the second frequency.

21. An electrosurgical apparatus according to claim 18 , wherein the first frequency is 14.5 GHz, the second frequency is 5.8 GHz, and the third frequency is 2.45 GHz.

22. An electrosurgical apparatus according to claim 18 , wherein the generator includes a detector arranged to detect reflected power received back from the coaxial cable, and wherein the generator is arranged to switch from one ablation period to the next ablation period based on the detected reflected power.

Assignees

• Creo Medical Ltd

Inventors

• Hancock Christopher Paul
• Burn Patrick
• White Malcolm
• Turner Louis

Classifications

• A61B2018/00785

  Reflected power · CPC title

• A61B2018/00577

  Ablation · CPC title

• A61B18/1815 Primary

  using microwaves · CPC title

• A61B2018/00732

  Frequency · CPC title

• A61B2018/1823

  Generators therefor · CPC title