Ablation instrument and manufacturing method thereof

Abstract

To provide an ablation instrument which is more considerably oriented toward medical aspects and considerations, allows freer work, and remarkably increases the safety of treatment for a patient.SOLUTION: An interior-cooled ablation instrument (11) includes a curved section (20) adjoining its distal end (12) in which the ablation instrument (11) is bent relative to its axial direction (A). The size of the angle is preferably defined to be from one third to two thirds, and preferably half, of the maximum angulation. The maximum angulation can significantly exceed an absolute value of 140°. The pre-bend in the curved section (20) can effectively avoid kinking of a hose of the ablation instrument, and thus the functional degradation of the electrode cooling as well as the occurrence of high dam pressure.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an ablation device, particularly for thermal ablation of a tissue volume by application of electrical current, as well as to a method for manufacturing such an ablation device. [Background technology]

[0002] Patent Document 1 discloses an ablation instrument having a hose-like base with two ablation electrodes disposed at the distal end thereof. The hose is flexible so that it can be bent in various directions when the probe is inserted into the working channel of an endoscope.

[0003] Furthermore, Patent Document 2 discloses a surgical instrument for use with a flexible endoscope, which comprises a catheter in which a surgical tool is disposed, the catheter comprising a defined curve and an opening in the region of the curve, from which the tool guided within the catheter can exit.

[0004] US Patent No. 5,399,633 discloses another instrument, particularly for endoscopic treatment of the bile duct, which includes a distal arcuate curved end traversed by a wire-like electrode.

[0005] For performing surgery in difficult to access body areas, US Pat. No. 5,393,633 discloses an instrument having a distal end that is bent back at an acute angle.

[0006] US Patent No. 5,399,633 describes a HF surgical instrument for endoscopic and / or laparoscopic use inside the rectum, the instrument being curved at its distal end, the defined curvature of the instrument facilitating guidance of the instrument within the channel of the endoscope, the distal end of the instrument having a rigidly curved shape.

[0007] Further prior art is provided by US Pat. No. 5,399,623 and US Pat. No. 5,499,633. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] European Patent Application Publication No. 3788974 [Patent Document 2] U.S. Pat. No. 4,474,174 [Patent Document 3] U.S. Patent No. 6,017,340 [Patent Document 4] US Patent No. 2022065 [Patent Document 5] European Patent No. 0536440 [Patent Document 6] European Patent No. 0947171 [Patent Document 7] European Patent Application Publication No. 1076523 Summary of the Invention [Problem to be solved by the invention]

[0009] For the correct operation of an ablation probe, it is essential that the electrodes in contact with the tissue do not become too hot in order to avoid drying of the tissue in contact with the electrodes. To achieve this, the inner lumen of the hose-like instrument can be used as a cooling channel, which must furthermore be fluid permeable when the probe is moved into a curved configuration by the endoscope.

[0010] It is an object of the present invention to provide an ablation instrument that can be transferred to a curved shape during use in an endoscope without limiting its functionality, and thus must allow particularly large angulations and tight bending radii. It is also an object of the present invention to provide a method for manufacturing such an ablation instrument. [Means for solving the problem]

[0011] This object is achieved by claims 1 and 15.

[0012] The ablation tool according to the invention comprises as a base a flexible hose having at least one lumen extending from the proximal end to the distal end of the hose. This lumen can be used as a cooling channel to prevent the electrode arranged at the distal end of the hose from being overheated, i.e. to cool the electrode. For this purpose, the electrode can be arranged in a section of the hose that does not bend without the application of an external force. The hose comprises a curved section adjacent to the electrode, in which the hose follows an arc without external forces acting on the ablation tool. The preferably straight distal end section of the hose supporting the electrode, the section along the arc and the section adjacent to the section proximally, also preferably straight, of the hose are configured in a flexible manner. This allows the initially unbent section to be curved as required. The curved section can then be gradually bent or transferred to a more straight, extended shape. The ablation tool, even with the curved section, can then be inserted into or removed from the straight working channel of the endoscope. During this process, the curved section transitions to an uncurved shape.

[0013] The stiffness of the curved section can be greater than the stiffness of a section of the ablation instrument proximally adjacent to the curved section, and the stiffness of the curved section can be greater than the stiffness of a section of the ablation instrument distally adjacent to the curved section. However, the stiffness of the distal section of the ablation instrument can alternatively be greater than the stiffness of the curved section, which may facilitate insertion of the ablation instrument into hard tissue (e.g., a solid tumor).

[0014] The curved section is preferably provided in a hose region that is located in a curved region of the endoscope when the distal end of the probe exits the working channel of the endoscope so that the one or more electrodes are inserted into the tissue to be treated. The ablation instrument may also include multiple curved sections, if desired.

[0015] The curved section preferably defines a curvature angle that is approximately half the curvature to be provided by the ablation instrument. For example, if an angulation (i.e. bending) of 145° (e.g. 160°) or more is desired, the curved section preferably defines an angle of 30°-70° with respect to the longitudinal direction. Other angles are possible depending on the requirements. On the one hand, the ablation instrument can be transferred to an extended shape without breaking in order to pass through the working channel of the endoscope and into the patient's tissue. On the other hand, the curved section of the ablation instrument can be curved up to an angulation angle of 140°-160° with each bending of the distal end of the endoscope, resulting in a larger curvature of the hose at the curved section, but without the risk of the hose kinking and thus of its lumen collapsing.

[0016] The lumen of the hose is preferably closed at the distal end. A solidifiable plastic forming a plug closing the hose end may serve to close the hose. However, a closure piece is preferably inserted at the hose end, at least partially made of an electrically conductive material, for example metal. If the closure piece is provided with individual electrical connections, which can extend, for example, through the lumen of the hose, the electrical connections can be used as electrodes to facilitate the insertion of the instrument into the living tissue and / or for hemostasis (coagulation). Furthermore, in order to prevent the instrument from being damaged during withdrawal from the coagulated tissue, the closure piece can be connected to a traction means extending from the distal end to the proximal end of the hose.

[0017] A capillary channel may be provided within the hose to direct coolant to the distal end of the ablation tool to receive and dissipate heat generated by the electrodes. The capillary channel may be configured within the hose itself, for example as a second lumen. Alternatively, the capillary channel may be configured within a capillary tube disposed within the lumen and extending from the proximal end to the distal end. The capillary channel may have one or more openings that allow coolant to enter the lumen of the hose proximate the electrodes.

[0018] The electrodes preferably surround the hose in such a way that they have the same effect in all radial directions. For example, the electrodes can be constructed as cylindrical electrodes or by electrical conductors spirally wound around the hose. The orientation of the axis of the ablation instrument is therefore irrelevant to the effect on the tissue. Thus, when inserted into an extended straight endoscope that then bends, the ablation instrument can be rotated about its axis to assume a rotational position in which the curvature of the ablation instrument extends in the same direction as the curvature of the endoscope.

[0019] At the distal end of the hose, at least one additional electrode can be arranged in the non-curved section. The distal end section of the hose, located distal to the curved section, in this case supports at least two electrodes, which are connected to two poles of a generator and can be used, for example, for tissue ablation, in particular for tumor ablation. The generator preferably generates a high-frequency voltage so that a current can be passed through the tissue in contact with the two electrodes in order to coagulate the tissue. In principle, however, it is also possible to use only one electrode in the ablation instrument, in which case a neutral electrode must be attached to the patient as a counter electrode. However, a configuration with two electrodes has advantages, especially during use in high-ohmic environments, for example during ablation of solid tumors in lung tissue. One or more electrodes can be arranged in the entire or part of the curved section of the instrument.

[0020] In the ablation device according to the invention, a coating is disposed on the hose, which forms a gap or gap-like gap with the hose. The coating can extend in particular from the proximal end of the ablation device through the curved section to the electrode or the insulation adjacent to the electrode. The formation of a gap between the hose and the coating provides a relative axial movement between the coating and the gap, which contributes to the flexibility of the ablation device.

[0021] In order to provide a rigid connection between the coating of the hose and the hose in the curved section, the gap can be filled with a plastic, in particular a two-component plastic. This plastic can be used to define the curvature of the ablation tool in the curved section. The plastic is preferably a flexible plastic so that the curvature can be eliminated or increased by applying further external forces. The plastic is preferably a solidifiable plastic, i.e. a plastic that can be injected into the gap during the manufacture of the ablation tool and thereby simultaneously or subsequently transfer the curved section to its curved shape and solidify. The ablation tool thus comprises a section with a permanent curvature after the plastic has solidified. As mentioned above, the hose and the coating are in fact flexible, but in the unacted state they are configured to be straight, i.e. without curvature. The plastic filling of the gap results in a stiffer cross section, so that the lumen is less sensitive to collapsing in the area where the plastic filling has been applied, by twisting the ablation tool.

[0022] Further details of the embodiments of the invention, and possibly even further aspects of the invention, can be derived from the drawings, the associated specification, and the claims. [Brief description of the drawings]

[0023] [Figure 1]FIG. 1 is a schematic diagram of an ablation instrument inserted into an endoscope and connected to a delivery device. [Diagram 2] FIG. 2 is a partial view of an ablation instrument according to the present invention. [Diagram 3] FIG. 3 is an enlarged side view of the distal end of the ablation instrument according to FIG. [Figure 4] FIG. 4 is a longitudinal cutaway view of the distal end of the ablation instrument according to FIG. [Diagram 5] FIG. 5 is a schematic longitudinal cutaway view of a portion of the curved section of the ablation instrument according to FIGS. 1-4. [Figure 6] FIG. 6 is a schematic longitudinal cutaway view of a modified embodiment of a portion of the curved section of the ablation instrument according to FIGS. 1-4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] 1 shows an ablation probe 11 inserted into an endoscope 10, with a distal end 12 of the ablation probe 11 protruding from a working channel of the endoscope 10. However, a proximal end 13 of the ablation probe 11 is connected to a supply device 14 or devices that provide electrical current, voltage, and coolant to the ablation probe 11.

[0025] The endoscope 10 comprises a longitudinally straight shank 15 extending along an axial direction A, the distal end 16 of which can be slightly bent by means of an operating element 17, e.g., an adjustment wheel, adjustment lever, etc., provided at the proximal end of the shank 15. Proximate to this operating element 17, the endoscope 10 comprises one or more connections 18, 19, depending on the number of working channels present, via which probes, instruments, etc. can be inserted into the respective working channels of the endoscope 10.

[0026] The endoscope 10 is preferably provided for operating in narrow and angled internal cavities of a patient's body. For example, the endoscope 10 can be used to treat lung tissue, in particular tumors therein. The distal end 16 of the endoscope 10 can be brought to a straight shape for this purpose by respective actuation of the operating elements 17, or can further be bent at an angle of, for example, up to 140° or more (150°, 160°) relative to the axial direction A. This can result in a bending radius of less than 15 mm.

[0027] FIG. 2 shows the ablation probe 11 based on the distal end 12 and a section proximally adjacent to the distal end 12, including a curved section 20 directly adjacent to the distal end 12, where the ablation probe 11 is curved without the action of an external force. Conversely, the distal end 12 and the section starting from the curved section 20 and extending to the proximal end 13 of the probe are preferably straight without the action of an external force. This straight section of the ablation probe 11 starting from the curved section 20 and extending proximally defines a longitudinal direction, which coincides with the axial direction A of the working channel of the shank 15 when the ablation instrument 11 is inserted in the working channel. The angle α defined by the curved section 20 with the distal end 12 and the axial direction A is preferably half the maximum angulation that must be obtained by the distal end 16 of the shaft 15. For example, if a maximum angulation or bending of 150° relative to the axial direction A must be obtained, the angle α may be preferably between 30° and 70°, preferably about 50° (+ / −20°), whereby the required deformation of the ablation instrument 11 from its initial shape to its maximum extended shape or from its initial shape to its maximum bent shape, respectively, is so small that twisting of the ablation probe at the bending position is not of concern.

[0028] The ablation probe 11 comprises at its distal end 12 at least one, preferably two electrodes 21, 22, which may be rigid or flexible. The electrodes 21, 22 may be identical to each other. They have the same electrical activity in each radial direction. In other words, the electrodes 21, 22 extend in the circumferential direction of the ablation probe 11. As is particularly evident from FIG. 3, the electrodes 21, 22 may be formed by a spirally wound conductor. An insulator 23 may be provided between the electrodes 21, 22.

[0029] As can be seen from FIG. 4, the two electrodes 21, 22 and preferably also a sleeve-like insulator 23 can be arranged in a hose 24 that extends from the proximal end 13 of the ablation tool 11 over its entire length, through the electrodes 21, 22, to an instrument tip 25. The instrument tip 25 is formed by an end piece 26 closing a lumen 27 surrounded by the hose 24. For example, the end piece 26 can be made of metal and can include a cross-shaped tip. An insulating element 28 can partially cover the end piece 26 and can extend over the hose 24. The end piece 26 can be connected by a traction means 29, for example in the form of a wire, to the proximal end of the ablation tool 11 or to a section of the tool that remains outside the endoscope during the use of the ablation tool in the endoscope. Furthermore, in the lumen 27 a fluid line can be arranged that conducts a coolant from the proximal end to the distal end 12 of the ablation tool 11 in order to cool the electrodes 21, 22 with the coolant. The fluid line may include a capillary 30, particularly in the distal region, which may also serve for traction force transmission. In order to obtain a cooling effect in the region of the electrodes 21, 22, the capillary 30 may include one or more coolant outlet openings in said region, for example at the distal end or wall of the capillary 30.

[0030] As shown in Figures 4 and particularly 5, the hose 24 is surrounded by a coating 31 at least away from the distal end 12, and the inner diameter of the coating 31 is slightly greater than the outer diameter of the hose 24, thereby defining a gap 32 between the hose 24 and the coating 31. The coating 31 may thereby extend from the proximal end 13 to one of the electrodes 21, 22. Optionally, an insulator ring 33 may be disposed between the distal end of the coating 31 and the electrode 22, adjacent to the electrode 22.

[0031] A unique feature of the ablation device 11 of the present invention is the curved sections 20 which have gaps 32 filled with plastic 34. However, it is preferred that the plastic filling is substantially limited to the curved sections 20 rather than extending along the entire length of the ablation device 11. However, it is also possible to fill larger areas of the gaps 32 or even the entire gaps 32 with plastic 34.

[0032] Instead of the insulator ring 33, a ring 35 made of metal or plastic can also be provided, which acts in particular as a centering element, as is evident from figure 6. The ring 35 comprises a tubular extension 36 which extends into the gap 32 and centers the coating 31 with respect to the hose 24. The plastic 34 filling the gap 32 of the curved section 20 can extend and seal between the coating 31 and the extension 36.

[0033] The plastic 34 is preferably a hardenable plastic, for example a two-component plastic, which is injected in liquid form into the gap 32, in particular into the curved section 20, during the manufacture of the instrument. To form the curved section 20, the curved section 20 is transferred into a curved shape immediately before or immediately after the injection of the plastic, after which the plastic 34 is hardened. For this purpose, the ablation instrument 11 can be placed in a respective holding device which forces the curved section 20 into an arc shape. After the solidification of the plastic, the ablation instrument 11 can be removed from the curved form, whereby the areas of the ablation instrument 11 which were held in a curved shape during the solidification of the plastic 34 form the curved section 20. However, the remaining sections of the ablation instrument 11 are provided in an elongated shape.

[0034] The ablation tool 11 thus far described operates as follows.

[0035] For use on a patient, the endoscope 10 is first inserted into the patient, for example into the bronchial system of the patient, and placed at the site to be treated. Already prior to this, or at the latest here, the ablation instrument 11 is moved through the working channel of the endoscope 10 via the connection 18 to the surgical site. This causes the pre-bent ablation instrument 11 according to FIG. 2 to elastically transition into an extended shape and advance up to the curved end 16 of the shank 15. The curved section 20 of the ablation instrument 11 has a tendency to quickly return to its pre-bent shape, so that as soon as it reaches the curved distal end 16 of the shank 15, it performs an axially rotating movement (at least if the curved section 20 does not by chance already have the correct rotational orientation about the axis A). At the same time, the ablation instrument 11 can advance axially to penetrate or insert its probe tip, i.e. the end piece 26, into the tissue to be treated. For this purpose, the end piece 26 can also be applied with voltage and current as required to facilitate insertion into more compact tissue, for example tumor tissue, or to coagulate slight bleeding. The supply of electric current to the end piece 26 can be realised via a traction means 29, or even a capillary tube 30 or individual conductors.

[0036] The pre-bent portion provided by the curved section 20 allows the distal end 16 of the shank 15 to bend with a very small bending radius, e.g. less than 15 mm, and even to a large obtuse angle, e.g. more than 145°, relative to the axial direction A, without having to modify the kinking of the hose 24 and thus the collapse of the lumen 27. Furthermore, the solidified adhesive or plastic 34 and the cover 31 have a support effect and also avoid any tendency of kinking of the hose 24. As a result, the coolant delivered via the capillary tube 30 can flow freely through the lumen 27 and return to the device 14 or to an outlet provided close to the proximal end 13, without being blocked and thus reducing the cooling effect on the electrodes 21, 22 or causing ruptures even in the case of acute angles of the ablation tool 11. The tool according to the invention thus allows the treatment of tumors or other tissue parts that are otherwise difficult to access and can only be reached by angling the end 16 of the endoscope 10 at an acute angle.

[0037] The internally cooled ablation instrument 11 according to the invention comprises adjacent to the distal end 12 a curved section 20, in which the ablation instrument 11 is curved with respect to its axial direction A. The magnitude of this angle is preferably defined as 1 / 3 to a maximum of 2 / 3, preferably half, of the maximum angulation. The maximum angulation can be significantly greater than an absolute value of 140°. The pre-bent part of the curved section 20 effectively avoids kinking of the hose of the ablation instrument and thus a poor functioning of the electrode cooling and the occurrence of high damming pressures. In so doing, the ablation instrument 11 according to the invention allows for a greater freedom of operation with a much greater regard for medical aspects and considerations compared to a fully extended ablation instrument. The safety of the procedure for the patient is significantly increased. [Explanation of symbols]

[0038] 10 Endoscopy 11 Ablation probe 12 Distal end of ablation probe 11 13 Proximal end of ablation probe 11 14 Apparatus for operation of the ablation probe 11 15 Shank of endoscope 10 16 Distal end of shank 15 17 Operational elements of the endoscope 10 18, 19 Connection portion of endoscope 10 A axis direction 20 Curved region of ablation probe 11 α angle 21, 22 electrodes 23 Insulators 24 Horse 25 Instrument tip 26 End Piece 27 Lumen 28 Insulators 29 Traction means 30 Capillary 31 Coating 32 Gap between coating 31 and hose 24 33 Insulators 34 Plastics 35 Ring 36 Extension

Claims

1. An ablation instrument (11), in particular for thermally deactivating a tissue volume by application of an electric current, comprising: a flexible hose (24) including at least one lumen (27) extending from a proximal end (13) to a distal end (12) of the hose (24); at least one electrode (21, 22) disposed at the distal end (12) of the hose (24); The ablation instrument (11) includes a curved section (20) in which the hose (24) is configured along a circular arc without an external force being applied to the ablation instrument (11). Ablation instruments.

2. The lumen (27) is closed at the tip of the distal end (12). The ablation tool of claim 1 .

3. To close the hose (24), a closure piece (26) is provided which is connected to a traction means (29) extending proximally from the distal end (12). The ablation tool of claim 2 .

4. A capillary channel including one or more openings is disposed within the hose (24) adjacent to the at least one electrode (21). An ablation tool according to any one of claims 1 to 3.

5. The capillary channel is formed in a capillary (30) that extends through the lumen. The ablation tool of claim 4.

6. The electrode (21) surrounds the hose (24), and the electrode (21) is formed by a conductor wound in a spiral shape around the hose (24). An ablation tool according to any one of claims 1 to 3.

7. The electrodes (22) are disposed outside the curved section (20). An ablation tool according to any one of claims 1 to 3.

8. At least one additional electrode (22) is disposed on the non-curved section of the distal end (12) of the hose (24). An ablation tool according to any one of claims 1 to 3.

9. The two electrodes (21, 22) are arranged at a distance from each other, but are similarly configured apart from each other. The ablation tool of claim 8.

10. A coating (31) is disposed on the hose (24). The ablation tool of claim 1 .

11. A gap (32) is formed between the coating (31) and the hose (24). The ablation tool of claim 10.

12. At least one electrical conductor is disposed within the gap (32) and extends proximally from the electrode (21). The ablation tool of claim 11.

13. At least the curved section (20) of the gap (32) is filled with plastic (34). An ablation tool according to claim 10 or 11.

14. The plastic (34) is a flexible plastic. The ablation tool of claim 13.

15. 14. A method for manufacturing an ablation device according to claim 13, comprising the steps of: The plastic (34) is a hardenable plastic that is injected into the gap (32); The method includes transitioning the curved section of the ablation instrument (11) into an arc shape and hardening the plastic (34). method.

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