Electrosurgical instrument and method of use

• US 20030078578A1
• Filed: 07/19/2002
• Published: 04/24/2003
• Est. Priority Date: 10/22/2001
• Status: Active Grant

• Current Assignee: Ethicon Endo-Surgery, Inc. (Johnson & Johnson)
• Original Assignee: SurgRx, Inc. (Johnson & Johnson)
• Inventors: Shadduck, John H., Truckai, Csaba
• Granted Patent: US 7,083,619 B2
• Time in Patent Office: Days
• US Class Current: 606/51
• CPC Class Codes: A61B 18/1442 Probes having pivoting end effectors, e.g. forceps
• CPC Class Codes: A61B 2018/00077 high, i.e. electrically conducting
• CPC Class Codes: A61B 2018/00083 low, i.e. electrically insulating
• CPC Class Codes: A61B 2018/00148 with metal
• CPC Class Codes: A61B 2018/0063 Sealing

Abstract

An electrosurgical medical device and method for creating thermal welds in engaged tissue. In one embodiment, at least one jaw of the instrument defines a tissue engagement plane carrying a conductive-resistive matrix of a conductively-doped non-conductive elastomer. The engagement surface portions thus can be described as a positive temperature coefficient material that has a unique selected decreased electrical conductance at each selected increased temperature thereof over a targeted treatment range. The conductive-resistive matrix can be engineered to bracket a targeted thermal treatment range, for example about 60° C. to 80° C., at which tissue welding can be accomplished. In one mode of operation, the engagement plane will automatically modulate and spatially localize ohmic heating within the engaged tissue from Rf energy application—across micron-scale portions of the engagement surface.

Claims

1. An electrosurgical jaw structure for controlled application of energy to tissue, comprising:

first and second jaws movable between opened and closed positions, each jaw defining an engagement surface layer for contacting tissue;

at least one engagement surface layer carrying first and second conductors operatively coupled to an electrical source to define opposing polarities therein;

said at least one engagement surface layer carrying a matrix material intermediate the first and second conductors, the matrix material comprising first and second compositions each in a selected proportion of the matrix volume, the first composition being substantially non-conductive electrically and the second composition being electrically conductive and dispersed within first composition, and wherein the first and second compositions define different selected coefficients of thermal expansion to thereby provide the matrix with a resistance that varies with temperature.

2. The jaw structure of claim 1 wherein said first composition is an elastomer.

3. The jaw structure of claim 1 wherein said first composition is a silicone.

4. The jaw structure of claim 1 wherein said first composition is a thermoplastic polymer.

5. The jaw structure of claim 1 wherein said first composition is a ceramic.

6. The jaw structure of claim 1 further comprising a plurality of voids in an interior of the matrix material for controlling the thermal expansion envelope of the matrix material.

7. The jaw structure of claim 1 further comprising at least one void in an interior of the jaw structure proximate to the matrix material for controlling the thermal expansion envelope of the matrix material.

8. The jaw structure of claim 7 further comprising at least one vent in the jaw structure communicating with said at least one void.

9. The jaw structure of claim 1 further comprising at least one portion of compressible material within the jaw and within the matrix material for controlling the thermal expansion envelope of the matrix material.

10. The jaw structure of claim 1 further comprising at least one portion of a material defining a negative thermal coefficient of expansion proximate to or within the matrix material for controlling the thermal expansion envelope of the matrix material.

11. The jaw structure of claim 1 wherein the second composition is a conductive particle having a dimension across a principal axis ranging between about 1 nanometer and 1000 microns.

12. The jaw structure of claim 1 wherein the second composition is a conductive particle having a dimension across a principal axis ranging between about 1 nanometer and 100 microns.

13. The jaw structure of claim 1 wherein the second composition is a conductive particle having a dimension across a principal axis ranging between about 1 nanometer and 10 microns.

14. The jaw structure of claim 1 wherein the second composition is a conductive filament.

15. The jaw structure of claim 14 wherein the conductive filament is of a shape memory material.

16. An electrosurgical jaw structure for controlled application of energy to tissue, comprising:

first and second jaws movable between opened and closed positions, the jaws defining first and second engagement surface layers respectively for contacting tissue;

the first engagement surface layer carrying a matrix material that defines a positively sloped temperature coefficient of resistance;

a first conductor in contact with the matrix material, said first conductor coupled to an electrical energy source to define a first polarity therein during operation; and

a second conductor exposed in the second engagement surface layer, said second conductor coupled to said electrical energy source to define a second polarity therein during operation.

17. The electrosurgical jaw structure of claim 16 further comprising:

a third conductor exposed the first engagement surface layer spaced apart from the first conductor, said third conductor coupled to said electrical energy source to define said second polarity therein;

wherein the matrix material is intermediate the first conductor and third conductor in the first engagement surface layer.

18. The electrosurgical jaw structure of claim 16 wherein the first conductor is surrounded on at least two sides in the first engagement surface by the matrix material.

19. The electrosurgical jaw structure of claim 16 wherein the first conductor comprises an island on a layer of the matrix material.

20. The electrosurgical jaw structure of claim 16 further comprising matrix thermal expansion control means within the interior of the jaw for controlling the dimensional envelope of the matrix material upon its elevation in temperature.

21. The electrosurgical jaw structure of claim 20 wherein said matrix thermal expansion control means comprises a volume of voids dispersed with the matrix material.

22. The electrosurgical jaw structure of claim 20 wherein said matrix thermal expansion control means comprises at least one air gap within an interior of the jaw proximate to said matrix material.

23. The electrosurgical jaw structure of claim 20 wherein said matrix thermal expansion control means comprises at least one material within or proximate to the matrix that is compressible in response to thermal expansion of the matrix material.

24. The electrosurgical jaw structure of claim 20 wherein said matrix thermal expansion control means comprises at least one material with a negative temperature coefficient of expansion within or proximate to the matrix.

25. An electrosurgical instrument for controllably causing ohmic heating of tissue, comprising:

an instrument having a body that defines an engagement surface for engaging tissue;

the engagement surface carrying an electrical conductor; and

an interior portion of the body comprising a matrix in contact with said electrical conductor, the matrix coupled to an electrical source wherein the matrix defines a positive temperature coefficient of resistance for controlling current flow therethrough, and wherein the matrix or body defines voids therein for controlling the overall dimensional expansion of the matrix in the body of the instrument.

26. The electrosurgical instrument of claim 25 wherein the body carries at least one vent that communicates with said voids.

27. The electrosurgical instrument of claim 25 wherein the voids comprise gas bubbles ranging in size from a sub-micron diameter to about 1 mm. in diameter.

28. The electrosurgical instrument of claim 25 wherein the engagement surface is carried in at least one of a pair of jaw members that are moveable between open and closed positions.

29. The electrosurgical instrument of claim 25 wherein the matrix is at least partly an elastomeric composition.

30. The electrosurgical instrument of claim 25 wherein the matrix is at least partly a ceramic composition.

31. The electrosurgical instrument of claim 25 wherein the matrix is at least partly a thermoset material.

32. The electrosurgical instrument of claim 25 wherein the matrix is an open cell composition.

33. The electrosurgical instrument of claim 25 wherein the matrix is a closed cell composition.

34. An electrosurgical method for controlling application of energy to a tissue site, comprising the steps of:

(a) providing a working end that defines an engagement surface for contacting tissue, said engagement surface comprising in part a temperature coefficient matrix material that defines a positively-sloped temperature-resistance curve over a selected temperature range, the working end carrying first and second spaced apart conductors operatively connected to an electrical source that defines first and second polarities in said conductors, said matrix material positioned intermediate said first and second conductors;

(b) positioning the engagement surface in contact with tissue; and

(c) causing Rf current flow from the first polarity conductor to the second polarity conductor through the engaged tissue and said matrix material thereby causing ohmic heating in the engaged tissue;

(d) wherein said ohmic heating in the engaged tissue is modulated as the temperature of said matrix material changes and alters the resistance thereof to thereby modulate and redirect current paths in said matrix material and said engaged tissue.

35. The method of claim 34 wherein said matrix material defines a temperature-resistance curve that continuously increases over a selected temperature range of about 37°

C. to 100°

C. and wherein step (d) continuously modulates energy application when the temperature of the said matrix material and the engaged tissue is within said selected temperature range.

36. An electrosurgical instrument comprising:

an introducer member extending along a longitudinal axis;

first and second jaws carried at a distal end of said introducer, said jaws defining first and second engagement surfaces respectively for contacting tissue, said engagement surfaces moveable relative to each other from an open position to a closed position for engaging tissue,

a portion of the first engagement surface comprising a conductor that defines a first polarity therein;

a portion of the second engagement surface comprising a conductor that defines a second polarity therein;

an interior of at least one jaw carrying a matrix material in contact with the conductor, the matrix material having a resistance to electrical current flow that increases with the temperature thereof.

37. The electrosurgical instrument of claim 36 wherein said matrix material has a resistance to current flow when at 37°

C. ranging from about 0.0001 ohms to 1000 ohms.

38. The electrosurgical instrument of claim 36 wherein said matrix material has a resistance to current flow when at 37°

C. ranging from about 1.0 ohm to 500 ohms.

39. The electrosurgical instrument of claim 36 wherein said matrix material has a resistance to current flow when at 37°

C. ranging from about 25 ohms to 150 ohms.