Electrosurgical instrument with carbon fiber electrode

Abstract

To provide an electrosurgical instrument by which extensive surface areas of biological tissue can be coagulated quickly and uniformly on the surface.SOLUTION: In a surgical instrument 15 according to the present invention for the treatment of a tissue surface 14, particularly for coagulation or ablation of the tissue surface, an electrode 23 composed of carbon fibers or at least containing carbon fibers functions to conduct current to the tissue surface. Anisotropy of the electrical conductivity of the carbon fibers or of the formed electrode enables realization of a large-area and uniform current distribution. This applies in the case of direct-contact coagulation as well as in the case of mixed coagulation in plasma generation with the electrode at least partially in contact with the tissue surface. Due to the configuration of the electrode surface by the carbon fibers and particularly their high thermal conductivity, sticking of the electrode to the tissue surface is effectively avoided.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an instrument for electrosurgical treatment of living tissue of a human or animal patient, and in particular to an instrument for superficial coagulation of such tissue. [Background technology]

[0002] Argon plasma coagulation instruments are known for treating biological tissue, particularly for coagulation and / or ablation. Such instruments are disclosed, for example, in U.S. Pat. No. 5,623,499. The instrument disclosed therein is configured as a flexible probe and includes a hose having a gas-carrying lumen. An electrode is disposed adjacent to the distal gas outlet opening of the hose, and the electrode is connected via an electrical supply line to a generator, which supplies the electrode with a voltage high enough to generate plasma. The argon flowing through the lumen is ionized at the electrode and exits the instrument distally as a plasma jet.

[0003] Such instruments can be used to treat selected tissue areas with precision and precision.

[0004] However, treatment of larger tissue areas may be desired, for example, during mucosal ablation of the stomach, in which case it may be necessary to electrosurgically treat a larger area, for example, up to two-thirds of the stomach surface, by argon plasma coagulation.

[0005] In this regard, Patent Documents 2 and 3 each disclose an ablation instrument suitable for ablation of a large area of ​​mucosa. The instrument comprises a probe hose supporting a head at its distal end, within which the lumen of the probe hose first extends continuously and then branches. The lumen thus opens into two mutually separated outlet openings. Electrodes for generating plasma jets are located at the outlet openings, respectively. The two generated plasma jets impinge adjacent to each other on the tissue surface. In this way, a wider ablation stripe is generated.

[0006] Another instrument for argon plasma coagulation is known from US Pat. No. 5,629,499. This instrument comprises a tube into the end of which a nozzle is inserted. In a variant, the nozzle contains a small sintered ball mass at the outlet opening, made of insulating ceramic material or even a conductive material such as metal or carbon. In this case, it is recommended to insert the nozzle into an insulating sleeve to avoid direct contact with the tissue.

[0007] Furthermore, instruments for tissue contact coagulation are known, in which a coagulation electrode is in direct contact with living tissue. For this purpose, Patent Document 5 discloses an instrument with a carbon-coated electrode. The carbon coating prevents the electrode from adhering to the tissue.

[0008] Furthermore, Patent Document 6 discloses an electrosurgical instrument having a distal electrode with a plastic coating.

[0009] Further prior art is known from US Pat. No. 5,629,299, ... and US Pat. No. 5,629,299.

[0010] Depending on the diameter and size of the plasma jet, different areas of tissue can be treated, and contact coagulation allows for even finer, more localized treatment of tightly defined areas. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication No. 2021 / 013852 [Patent Document 2] European Patent No. 3141203 [Patent Document 3] European Patent No. 3141204 [Patent Document 4] German Patent No. 19535811 [Patent Document 5] U.S. Patent No. 4,074,718 [Patent Document 6] US Patent Application Publication No. 2013 / 0110105 [Patent Document 7] International Publication No. 2014 / 197632 [Patent Document 8] Chinese Patent Application Publication No. 1168308 [Patent Document 9] US Patent Application Publication No. 2012 / 083782 [Patent Document 10] US Patent Application Publication No. 2016 / 121134 [Patent Document 11] European Patent Application Publication No. 3708222 Summary of the Invention [Problem to be solved by the invention]

[0012] SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrosurgical instrument capable of rapidly and uniformly superficially coagulating large surface areas of living tissue. [Means for solving the problem]

[0013] This object is achieved by the device according to claim 1.

[0014] The device according to the present invention comprises a shank including an electrode at its distal end, which can be supplied with a treatment current via a line and an electrical generator. The electrode comprises electrically conductive carbon fibers. The carbon fibers cause the electrode to be electrically conductive, and at the same time, the electrode's spatial extent allows for a wider current distribution when it contacts a larger area of ​​biological tissue. Therefore, the width of the electrode attached to the elongated shank, particularly the width measured transversely to the longitudinal direction of the shank, can be greater than the width of the shank. The carbon fibers thereby form individual, resistive linear conductors that individually conduct current and distribute it relatively uniformly over the surface where the electrode contacts the tissue.

[0015] The elongated shank can be rigid or flexible, and carries an electrode at its distal end and includes means at its proximal end for connecting an electrical line to a generator. The carbon fiber containing electrode in this case primarily serves as a contact coagulator.

[0016] The elongated shank may also have one or more lumens within it, such that the shank is configured as a hose or tube. The lumens may be connectable or connected to a gas source by suitable connecting means. If multiple lumens are present, they may be connected to the same gas source or even different gas sources.

[0017] The distal end of the hose (or tube) may have an outlet opening connected to one or more lumens, from which a suitable gas, particularly an inert gas such as argon, may flow. The outlet opening and the electrode are preferably positioned relative to one another so that the released gas flows around the electrode.

[0018] The electrode can be supported in or on the shank, either stationary or movably. If the shank is configured as a hose or tube, the electrode can be positioned entirely or partially inside or outside the lumen, for example, in front of the exit opening. In particular, the electrode can be positioned so that it can exit the lumen. The electrode can function to ionize the gas flow, thereby generating plasma, and simultaneously or alternately perform contact coagulation on the surface of the tissue to be treated. In particular, if the electrode has an ohmic resistance higher than the treatment voltage divided by the maximum treatment current, it can have a current-limiting effect on the current used for contact coagulation, thereby further enabling the generation of plasma for tissue coagulation. This can contribute to achieving uniform, widespread, and more rapid tissue coagulation.

[0019] Electrodes made of or containing carbon fibers can further have a preferred direction of current flow, which is determined by the carbon fibers. This can also result in a more uniform current distribution across the electrode. For example, the electrode can have low electrical resistance along its length. This can be supported by a metal wire extending within the electrode along its length, e.g., in the center of the electrode. The current must overcome electrical resistance on its way from the metal wire to the electrode surface, which can help avoid or reduce local current density peaks on the electrode surface.

[0020] The electrode can be movably positioned within and at the exit opening of the lumen. For example, the electrode can be positioned inside the lumen in a first position, while in a second position, the electrode is positioned entirely or partially outside the lumen. In this way, the instrument can select different coagulation types depending on the position of the electrode. For example, the instrument can perform plasma coagulation as long as the electrode is positioned inside the lumen. However, if the electrode is entirely or partially outside the lumen, contact coagulation can complement plasma coagulation, or if the area of ​​tissue contact of the electrode is large, contact coagulation can be primarily or solely effective.

[0021] The electrode can be configured to be rigid or flexible, for example, as a brush, loop, twisted thread, or rigid or flexible spatula. The carbon fibers can be embedded in a solid body, for example, a plastic matrix. The plastic matrix can be made of an electrically insulating plastic. The number and arrangement of the carbon fibers thereby determine the electrode's conductivity and the preferred direction of current flow, and ultimately the current distribution on the electrode surface. However, inherently or non-inherently conductive plastics can also be used for the plastic matrix.

[0022] The carbon fibers can be entirely embedded in the body of the electrode or have ends that protrude from the body. Similarly, the carbon fibers can be braided, twisted, or otherwise bound together to form threads or strands, one or both ends of which are connected to a current supply line. It is also possible for all of the carbon fibers to be held in a holder at one end, while the other end protrudes away from the holder in the form of a brush. In addition to the carbon fibers, other conductors, such as blank metal wires, can be placed within the electrode to specifically influence the spring or electrical properties of the loop-shaped electrode.

[0023] Furthermore, it is possible to configure the flexibility of the electrode so that, on the one hand, it fits into the lumen of the hose in its compressed state, and, on the other hand, it becomes larger when it is positioned outside the lumen, thus having a transverse dimension that is larger than the transverse dimension of the lumen; Further details of advantageous embodiments of the invention are found in the subject matter of the claims as well as in the drawings and the respective description. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic diagram of an ablation device having a device according to the present invention, an apparatus for delivering the device, and biological tissue undergoing thermal treatment. [Figure 2] FIG. 2 is a view of the distal end of the device according to FIG. [Figure 3] FIG. 3 is a longitudinal cutaway view of the distal end of an alternative embodiment of an instrument according to the present invention. [Figure 4] FIG. 4 is a diagram of part of the electrodes of the device according to FIG. [Figure 5] FIG. 5 is a view of a portion of an alternative embodiment of the electrodes of the device according to FIG. [Figure 6] FIG. 6 is a diagram of an alternative electrode configuration for the device according to FIG. 3 having a material structure according to FIG. 4 or FIG. [Figure 7] FIG. 7 is a view of the distal end of the device according to FIG. 1 in an alternative configuration with electrodes formed as loop-shaped strands. [Figure 8] FIG. 8 is a view of the device according to FIG. 7 with the electrodes retracted inside the lumen of the shank. [Figure 9] FIG. 9 shows a view of the electrode according to FIG. 7 during coagulation of biological tissue and also a simplified schematic diagram of the electrical state. [Figure 10] FIG. 10 is a diagram of an alternative embodiment of the device according to the present invention without a gas supply. [Figure 11] FIG. 11 is a longitudinal cutaway view of the distal end of the device according to FIG. [Figure 12] FIG. 12 is a view of the distal end of a modified device in an alternative configuration with a double loop shaped electrode. DETAILED DESCRIPTION OF THE INVENTION

[0025] A treatment device 12 that functions for two-dimensional coagulation of biological tissue 13 is apparent from Figure 1, and biological tissue 13 is shown very diagrammatically in Figure 2. The biological tissue 13 includes a surface 14 that may be formed from an internal organ surface such as the gastric mucosa.

[0026] The tool 15 and an instrument 16 for providing the tool 15 are part of the device 12, and a connection means provided at the proximal end of the tool 15, for example in the form of a connector 17, is connected to the instrument 16.

[0027] The instrument 15 includes an elongated shank 18, configured in this case as a flexible hose 19 or even a tube, which can be passed through a working channel of an endoscope or another instrument (not shown) that provides access to the inside of the patient's body and moved to a treatment site opposite the tissue surface 14. A proximal end of the hose 19 is connected to equipment 16 outside the patient, and a distal end 20 of the instrument 15 is disposed on or within the patient.

[0028] The instrument 15 shown in Figure 1 serves for coagulation of tissue surface 14 under an argon plasma atmosphere. For this purpose, the instrument 16 includes a gas source 21 that supplies argon or another suitable gas to the instrument 15 via a connector 17. The instrument 16 further includes a radiofrequency generator 22, one pole of which is connected to a line 24 that leads to an electrode 23 of the instrument 15, and the other pole of which is connected to a line 26 that leads to an indifferent electrode 25. The indifferent electrode 25 is attached globally to the patient.

[0029] 2, the hose 19 contains at least one lumen 27 through which a gas, preferably argon, supplied to the hose 19 flows towards the electrode 23 and out of an outlet opening 28 located at the distal end 20 of the hose 19. Optionally, the hose 19 may include one or more additional lumens 27a connectable to the same gas source 21 or to one or more additional fluid sources 27a, in particular to a gas source or even a liquid source.

[0030] The electrode 23 includes a number of carbon fibers 29, which may be arranged, for example, in the form of a brush. To this end, the carbon fibers 29 have their ends held within a holder 30 and extend distally from the holder 30, thus away from the opening 28. As shown in FIG. 2, the carbon fibers 29 may be arranged to protrude from the holder 30 in a divergent manner, such that the width of the resulting brush 31 exceeds the diameter of the lumen 27. The width is measured transversely to the lumen and thus transversely to the line 24. The brush 31 conducts current substantially only along its length, so that each fiber 29 has an electrical resistance. Therefore, even if one or more carbon fibers come into contact with the tissue surface 14, the entire current provided by the generator does not flow through these fibers. Rather, the generator voltage is maintained in the remaining carbon fibers.

[0031] Electrodes 23 may be arranged axially stationary or may be further arranged movably in the longitudinal direction of the lumen and thus the longitudinal direction of line 24. For example, electrodes 23 may enter and exit lumen 27 by respective positioning along arrow 32 (FIG. 2).

[0032] The electrode 23 of the device 15 can be configured in various ways. To this end, FIG. 3 shows an embodiment in which the electrode 23 is configured as a rigid or low-flexibility elliptical body 33. The body 33 is preferably a plastic body, the internal structure of which is apparent from FIG. 4. The plastic body is formed by a plastic matrix 34 made of a low-conductivity or non-conductive plastic in which numerous carbon fibers are embedded. These can be relatively short and longer fibers. The carbon fibers 29 can have a preferred direction or can be arranged alternately without a preferred direction. The carbon fibers can be completely embedded in the body 33, resulting in a smooth surface. Alternatively, the carbon fibers 29 can have ends 35 protruding from the plastic matrix 34, resulting in a rough or hair-like surface.

[0033] The electrode 23 is by no means limited to the oval shape shown in Figure 3. The electrode 23 can also be configured as a spear-shaped or oval spatula, as a needle or rod, or as a slotted spatula 36 as shown in Figure 6.

[0034] In another modified embodiment shown in FIG. 7, the carbon fibers 28 of the electrode 23 are formed into a rope or thread 23a, both ends of which are held in a holder 30. Thus, the electrode 23 is flexible and forms a smooth sling or loop. The electrode 23 includes carbon fibers twisted or intertwined with each other, allowing ends 35 of the carbon fibers to protrude from the thread 23a or rope. If desired, the thread 23a may include a metal or plastic wire 30a positioned approximately in the center of the thread 23a. The wire 30a is represented by a dashed line in FIG. 7. This (plastic) wire 30a can serve to stiffen the thread 23a. When the wire 30a is made of metal, or when a plastic wire is combined with a metal wire, the wire 30a can also serve to uniformly distribute the current.

[0035] The electrode 23 formed by the strand 23a or loop can be held at a predetermined fixed position on the shank 18. However, the electrode 23 can also be arranged movably. In this case, the electrode 23 can be moved by a respective axial movement either to an exposed position shown in FIG. 7 or to a retracted position shown in FIG. 8. In the retracted position, the electrode 23 is held partly or entirely within the lumen 27. The width of the electrode 23, exemplarily formed as a loop, in its extended state according to FIG. 7 can be greater than the inner diameter of the hose 19 and thus the lumen 27. Thanks to its flexibility, the electrode 23 can be compressed in terms of its width to fit into the lumen 27 according to FIG. 8.

[0036] The functioning of the device 15 described so far will now be explained, by way of example, with reference to FIG.

[0037] For coagulation of the tissue surface 14, the distal end 20 of the instrument 15 is brought into close proximity with the tissue surface 14. Argon flows distally through the lumen 27 and around the electrode 23. The electrode 23 is connected via line 24 to a radio frequency generator 22, which receives an alternating voltage of several hundred volts having a frequency significantly greater than 100 kHz. This positions the electrode 23 to protrude through the opening 28, allowing at least a portion of the electrode 23 to selectively touch the tissue surface 14. However, the electrode 23 has a resistance per unit length along its length, symbolically designated by resistors R1 and R2 in FIG. 9, across which the UHF voltage output by the generator 22 is applied.

[0038] The electrode 23 directly contacts the tissue surface 14, thereby producing a coagulation effect on the tissue surface 14. This allows the argon flowing through the lumen 27 to surround the electrode 23 in a protective manner, resulting in contact with the tissue surface 14 and the formation of a spark plasma generated by the electrode 23. Depending on the size and pressure of the contact area between the electrode 23 and the tissue surface 14, the electrical resistance formed by the electrode 23 between the line 24 and the tissue surface 14 can be increased or decreased. Specifically, the non-metallic construction of the electrode 23 limits the current transmitted from the electrode 23 to the contact point on the tissue 13. As a result, in addition to contact coagulation, plasma generation occurs, for example, in the holder 30 or in a portion of the electrode 23. The plasma is indicated by the wavy arrow 37 in the physical diagram of FIG. 9 and the accompanying electrical schematic diagram.

[0039] The carbon fibers 29 may contribute to the strong electrical anisotropy of the electrode 23. For example, the twisted yarns 23a or even the ends 35 of the carbon fibers protruding from the electrode according to FIG. 3 or FIG. 6 may be preferred current exit points for plasma yarn generation. However, the configuration of the electrode 23 made of the carbon fibers 29 in particular avoids adhesion or attachment of the electrode 23 to the tissue surface 14, and thus damage to the tissue surface 14. Whether the electrode 23 is configured as a brush 31, a spatula 36, ​​or an elliptical body 33, the carbon fibers 29 contribute to a uniform current distribution on the tissue surface 14 and to preventing adhesion of the electrode 23 to the tissue surface 14. Furthermore, the high thermal conductivity of the carbon fibers can be used to keep the temperature of the electrode relatively low, thereby reducing the tendency of tissue to adhere to the electrode.

[0040] Another embodiment of the present invention is derived from FIGS.

[0041] In the embodiment according to FIG. 10, the instrument 15 includes a rigid shank 18 that may include a gas-carrying lumen as in the previous embodiment. However, it is also possible to omit the gas supply through the shank 18 and instead supply gas to the body cavity 38 from a gas source via a separate access 39. This allows the electrode 23 to be configured in any of the forms described above. By way of example, FIG. 11 shows the configuration as a brush 31. When the body cavity 38 is filled with a protective gas, such as argon, plasma threads may emerge from the free ends of the carbon fibers 29 and form toward the tissue surface 14. The practitioner can then move the brush 31 over a large area of ​​the tissue surface 14, with or without contact, to coagulate the tissue surface 14.

[0042] Many further variations of the device are possible. For example, FIG. 12 shows a device 15 substantially according to the embodiment described in FIGS. 7-9. However, while the electrode 23 is configured as a single loop in the embodiment according to FIGS. 7-9, it is also possible to configure an electrode with multiple loops, for example, two loops 39, 40 positioned at approximately 90° to each other. This electrode 23 can be electrically connected at its proximal end to a conductor extending through the hose 19. The loops 39, 40 can be configured as twisted, twisted, or braided yarns of carbon fiber connected, for example, by crimping, to a conductor extending through the hose 19. With regard to the operation and function of the device 15 according to FIG. 12, the above description applies mutatis mutandis, using the respective reference numerals already introduced. One or more wires can be included in the loops 39, 40 to increase the stiffness of the electrode 23 and to give it spring-like recovery properties. These wires can extend centrally through each leg of the loops 39, 40, similar to the wire 30a in FIG. 7.

[0043] In all of the above-described embodiments, the electrodes made of carbon can be electrically contacted by supply lines made of metal. This is particularly advantageous if the elements holding the electrodes, such as crimp sleeves, and possibly also the electrical supply lines, have high thermal conductivity. For example, the supply lines can be made of copper or stainless steel wire with a thermally conductive coating.

[0044] In the inventive instrument 15 for surgical treatment of a tissue surface 14, in particular for coagulation or ablation of the tissue surface 14, an electrode 23 made of or at least including carbon fibers 29 serves to pass an electric current through the tissue surface 14. Due to the anisotropy of the electrical conductivity of the carbon fibers 29 or the formed electrode 23, a uniform current distribution over a large area can be achieved. This applies both in the case of direct contact coagulation and in the case of mixed coagulation with plasma generation, with the electrode 23 at least partially in contact with the tissue surface 14. The construction of the electrode surface with carbon fibers 29 and, in particular, their high thermal conductivity, effectively prevents adhesion of the electrode 23 to the tissue surface 14. [Explanation of symbols]

[0045] 12. Devices for tissue coagulation 13 Organization 14 Tissue surface 15 Equipment 16 Equipment 17 Connectors 18 Shank 19 Horse 20 Distal end of instrument 21 Gas Source 22 RF Generator 23 electrodes 23a Twisted Yarn 24 Line to electrode 23 25 Neutral electrode 26 Line to neutral electrode 25 27, 27a lumen 28 Opening 29 Carbon Fiber 30 Holder 30a wire 31 Brush (Figure 2) 32 Arrow 33 Main body (Fig. 3) 34 Plastic Matrix 35 Carbon fiber end 36 Spatula 37 Wavy Arrow 38 body cavity 39, 40 Loops

Claims

1. An instrument (15) for treating living tissue (13), comprising: an elongated shank (18) including an electrode (23) at one distal end (20), said electrode (23) being connected to an electrical line (24) connected or connectable to an electrical generator (22); The electrode (23) comprises carbon fibers (29). Equipment.

2. The elongated shank (18) is a hose (19) or tube, the hose (19) or tube including at least one lumen (27) connected or connectable to a gas source (21), and having an outlet opening (28) at the distal end (20) of the hose (19) or tube.

10. The device of claim 1.

3. The electrode (23) is located in or at the outlet opening (28).

3. The device of claim 2.

4. The electrode (23) is movably supported in or on the shank (18).

10. The device of claim 1.

5. The electrode (23) can be retracted entirely within the lumen (27).

3. The device of claim 2.

6. The electrode (23) is configured as a loop The device according to any one of claims 1 to 5.

7. The electrode (23) is configured to be flexible. The device according to any one of claims 1 to 5.

8. At least some of the carbon fibers (29) have uncovered movable ends (35). The device according to any one of claims 1 to 5.

9. At least some of the carbon fibers (29) have ends that are fixed within the electrode (23). The device according to any one of claims 1 to 5.

10. The carbon fibers (29) are held in the form of a brush (31). The device according to any one of claims 1 to 5.

11. The carbon fiber (29) is configured as a twisted yarn (23a). The device according to any one of claims 1 to 5.

12. The line (24) is configured to extend from the electrode (23) to a proximal connecting means (17). The device according to any one of claims 1 to 5.

13. The line (24) is disposed within the lumen (27). The device according to any one of claims 2 to 5.

14. The shank (18) includes multiple lumens (27, 27a) that run from the proximal end of the shank (18) to the distal end (20). The device according to any one of claims 2 to 5.

15. The lumens (27, 27a) are connected to connecting means (17) for connecting the lumens (27, 27a) to different fluid sources (21, 21a).

15. The device of claim 14.

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