WO2001067976A1

WO2001067976A1 - Electrosurgical instrument comprising a reduced electrode surface area

Info

Publication number: WO2001067976A1
Application number: PCT/EP2001/002878
Authority: WO
Inventors: Herbert Maslanka
Original assignee: Herbert Maslanka
Priority date: 2000-03-14
Filing date: 2001-03-14
Publication date: 2001-09-20
Also published as: AU4246001A

Abstract

The invention relates to an electrosurgical instrument. Said instrument comprises an electrode (7) which is connected at the patient facing end of the instrument to an electrode supply line (5), a current-conductive electrode core (15) and an insulating sheath (19) that partially covers the electrode (15). The instrument is characterised in that in at least one partial section (21) of the electrode core (15), the exposed surface area (17) of the electrode is reduced by a section of the insulating sheath (19) containing a large number of micro-cavities (23).

Description

Electrosurgical instrument with reduced electrode area

description

The invention relates to an electrosurgical instrument and a method for its production.

An electrosurgical instrument in the form of a high-frequency surgical, monopolar-connected loop electrode is known from German patent specification 21 32 808 and is often used as an additional device for endoscopes in order to remove growths, for example gastric and intestinal polyps. This is done by separating the growths by pulling in the loop electrode connected to a power source via the electrode lead by means of electrotomy.

The known loop electrode type has two loop sections which merge integrally into one another at the electrode tip. A semicircular bend is provided at the area of the electrode tip, which ensures that the loop sections are spread open when they are pushed out of the tube and that they are drawn into the tube.

From German published patent application 28 08 546, an electrosurgical instrument operated with high-frequency energy is known, which is used for cutting structures in human body cavities. This instrument comprises a metal cable consisting of an arcuate actuation wire and a straight cutting wire. An insulating sheathing is provided on the actuating wire, which prevents adjacent tissue from being injured or accidentally cut during the cutting process. In the case of, for example, a loop electrode, the current strength provided by the energy source is often not sufficient to heat the tissue in order to carry out a clean, bleeding-free coagulation cut with the loop electrode. Rather, the separation process is completed by the growth that is to be separated being plucked off by pulling the loop electrode into the tube and consequently by the pinching effect of the loop sections associated with the reduction in the area spanned by the loop electrode. There are limits to the use of stronger energy sources insofar as the increased electrical energy can possibly lead to inconvenience or even health damage for the patient to be treated. Furthermore, the use of stronger energy sources stands in the way of economic aspects with regard to the manufacture of the electrosurgical instrument.

Loop electrodes, which are provided with an insulating jacket to reduce the effective electrode area in some areas, are known from US Pat. Nos. 5,318,564 and 5,078,716. Loop electrodes of this type limit the electrode area, so that on the one hand it is possible to work with a reduced current or voltage and on the other hand the risk of tissue being inadvertently injured is reduced.

A rod-shaped electrosurgical electrode is known from German utility model DE 94 90 477 U 1 (W096 / 1 9739), which, apart from its electrode tip, is coated with a material that is both electrically and thermally insulating, for example made of plastic or ceramic. Electrical insulation reduces the risk of unintentional injuries, and the thermal insulation properties reduce the tendency of the electrode to crust when the tissue is electrosurgically coagulated. The sheath is additionally provided with openings in the area of the tip, which expose the conductive surface of the electrode. It is an object of the invention to provide an electrosurgical instrument which manages with reduced electrical energy both in terms of its coagulation properties and in terms of its tissue cutting properties.

To achieve this object, the invention is based on an electrosurgical instrument which comprises an electrode connected to an end of an electrode lead near the patient with an electrically conductive electrode core made of metal and an insulating jacket which partially covers the surface of the electrode core that can be used electrosurgery and is made of a material exists, the electrical conductivity of which is many times lower than the electrical conductivity of the electrode core.

The improvement according to the invention is characterized in that the insulating sheath contains at least in a partial area of the surface of the electrode core that can be used electrosurgically, a multiplicity of micro-openings completely penetrating the insulating sheath.

The invention is based on the consideration that different high-frequency voltages or currents are set on the high-frequency generator feeding the electrode of the instrument for the coagulation of the tissue on the one hand and the cutting of the tissue on the other hand. A lower electrical power is generally required for the coagulation, since the coagulation effect occurs due to the heating of the tissue. To cut the tissue, the high-frequency power is increased to such an extent that the electrode generates a plasma arc towards the tissue. With the low high-frequency currents required for coagulation, the capacitive coupling of the electrode to the tissue is sufficient in individual cases to maintain a sufficiently high high-frequency coagulation current, even if the conductivity of the insulating jacket should be very low. On the other hand, the micro-openings provide non-insulated areas in the insulating jacket that are used in the high-frequency plasma cutting of the tissue form plasma channels in which an arc can burn. Since these are micro-openings, the effective electrode area is relatively small and the high-frequency electrical power is concentrated on the total cross-sectional area of the micro-openings. The tissue can therefore be cut with comparatively low radio frequency power. It goes without saying that the microperforation of the insulating jacket also improves the coagulation effect of the electrode, expediently at least the part of the insulating jacket containing the micro-openings in order to increase the electrical conductivity of its base material acting as an electrical insulator, for example made of plastic or ceramic, electrically conductive particles, for example Can contain carbon particles (soot) or metal particles (metal powder). Such an electrode ensures a sufficient high-frequency current flow both in coagulation mode and in cutting mode.

In the region of the electrode having the micro-openings, the electrode surface is preferably reduced by approximately 50% to approximately 99%, preferably by approximately 70% to 99%, by the insulating jacket. The width of the openings, corresponding to the average diameter, if the openings are approximately the same width as long or the width of elongated gap-shaped openings, can be 0.005 to 1 mm, preferably 0.01 to 0.5 mm, or the 0, 01 to 50 times, preferably 1, 1 to 10 times, particularly preferably 0.5 to 2 times the average thickness of the insulating jacket. The layer thickness of the insulating jacket is preferably 0.02 to 0.3 mm, particularly preferably 0.05 to 0.1 2 mm.

The micro-openings in the insulating jacket can be made in different ways. For example, the insulating material layer can first be applied to the closed surface and the openings subsequently made in a precisely predetermined form, in particular mechanically or by exposure to radiation, for example by means of a laser. Also photolithographic Fish techniques come into consideration. A further possibility for producing the openings is that rings of insulating material are placed one behind the other on the electrode core, so that gaps remain between the rings, which then form the openings which leave the effective electrode surface open. In order to ensure a tight fit of these rings on the electrode core, the rings can be formed from heat-shrinkable material, which have shrunk after being placed on the electrode core.

It is also possible to first coat the electrode core with hardening or hardenable insulating material on the closed surface and then to deform the electrodes in such a way that the insulating sheath cracks to form the micro-openings. This process is particularly economical.

The insulating jacket can be sprayed, sputtered, painted, extruded or applied by dipping on the electrode core. There is also the possibility of forming the micro-openings by spraying or sputtering on droplets of a non-closed layer of insulating material, which keeps the manufacturing effort very low.

The insulating jacket can be formed from lacquers, polyamides, polyimides or a fluoroplastic, in particular from FEP, ETFE, ETCFE, PCTFE, PEEK, PTFE, preferably MFA, PFA, FEP or a mixture of at least two of these materials. Expediently, electrically conductive particles, such as carbon black or metal powder, can also be mixed in to increase the conductivity.

The electrode configuration according to the invention is suitable for a large number of electrode shapes, including the loop electrodes mentioned above, but solid electrode bodies are also possible, in particular balls with a diameter of, for example, 1 to 5 mm or knife-like bodies, preferably with a length of 1 to 15 mm (scalpel-like instruments), or elongated, approximately rod-shaped bodies, or also flattened bodies, approximately rounded at the periphery.

The electrode can also be divided into a pair of electrodes that can be moved towards one another in the manner of pliers.

The instrument can be used for external use, in which case the electrode can be connected to an insulating grip part via an insulating, elongated neck, or for endoscopic use, in which case the covered neck can be designed as a rigid or flexible rod. The preferred application is in monopolar electrodes, in which the electrode forms one pole and the patient's body the other. The electrode core can also be divided into two or more differently polarized sections for bipolar operation.

In general, the coagulation properties, but especially the cutting properties, can be improved the greater the area covered by the insulating jacket, i.e. the larger the electro-surgical instrument is.

Further advantages, features and properties of the invention can be found in the description of preferred embodiments according to the invention with reference to the accompanying drawings, in which:

Figure 1 is a cross-sectional view of the loop electrode side

Schematically represents the area of an electrosurgical instrument according to the invention, with essentially circular openings in the insulation;

Figure 2 is a cross-sectional view according to section line II-II of Figure 1;

Figure 3 shows schematically a variant of the instrument of Figure 1; Figure 4 is a view similar to Figure 1, but in which the insulation openings are formed by cracks;

Figure 5 shows an instrument similar to Figure 1, but with annular gap

Openings in the insulation; Figure 6 is a cross-sectional view according to section line VI-VI in Figure 5;

FIG. 7 shows a cross-sectional view along section line VII-VII in FIG. 5;

FIG. 8 shows a view of a spherical electrode head of an electrosurgical instrument according to a further embodiment;

FIG. 9 shows a view of a knife-like electrode head of an electrosurgical instrument according to yet another embodiment;

10a shows a side view of a forceps-like electrode head of an electrosurgical instrument according to yet another embodiment, and FIG. 10b shows a view according to arrow X in FIG. 10a.

The part of an electrosurgical instrument 1 shown in FIG. 1 comprises a flexible and externally insulating tube 3, which is made of poly-tetra-fluoro-ethylene. The tube 3 can also be made from a rigid insulating material. In the flexible tube 3, a flexible electrode lead 5 is slidably guided, which is coupled at its end remote from the patient to an actuating device (not shown) and is electrically connected to an energy source (not shown). The electrode lead 5 can also be rigid.

The end 6 of the electrode lead 5 near the patient carries a loop electrode 7 symmetrical to the tube axis, with two loop sections 9 and 11 extending between the end 6 of the loop electrode 7 remote from the patient and an electrode tip remote from the electrode lead 5. The loop electrode 7 can be displaced relative to the tube 3 by means of the actuating device (not shown) and the electrode feed line 5 coupled to the latter so that its loop line sections 9, 1 1 to grasp the growth to be removed of the patient to be treated (not shown) resiliently spread as soon as they are pushed out of the tube 3, and they are completely retractable into the tube 3 to carry out the coagulation process.

In the extended state, the loop electrode 7 can assume other loop shapes in addition to the shape shown in FIG. In particular, a hexagonal loop shape (not shown) or a loop shape (not shown) angled to the longitudinal axis of the part of the electrode lead 5 near the patient, which is used advantageously in the cutting of difficult-to-reach growths.

The loop sections 9, 11 span a flat loop plane, the longitudinal axis of the part of the electrode lead 5 near the patient lying in the loop plane. The position of the loop plane does not essentially change with respect to the part of the electrode lead 5 near the patient when the loop sections 9, 11 are drawn in.

The loop sections 9, 11 are attached to the end 6 of the electrode lead 5 remote from the patient by means of a metal sleeve 13 and electrically coupled to the latter. In the embodiment of the loop electrode 7 according to FIG. 1, the patient-oriented ends of the loop sections 9, 11 merge integrally into one another.

The structure of the loop sections 9, 1 1 is clear from Figures 2 and 3. The loop electrode 7 is formed by a wire cable 1 5 carrying the electrical current, which has a (1 × 4) strand structure. Other strand structures (1 x7, 3x7, 1 x9) can also be used. The wire rope 1 5 is completely surrounded by an insulating jacket 1 9 (see FIG. 2) except for an effective electrode surface 1 7. In the loop electrode 7 according to FIG. 1, the effective electrode area, that is to say the surface sections 1 7 of the wire rope 1 5 exposed to the outside, is limited by a plurality of continuous micro-openings 23 in the insulating sheath 19 distributed over the loop 7. The openings 23 are here, at least on average, approximately as wide as they are long. The distribution density of the openings 23 can be uniform over the entire loop 7 or can be denser at the actual cutting area of the loop, namely the tip 21, than at the remaining loop sections 9 and 11. The openings can also be provided only in the area of the tip 21 and / or predominantly on the inside of the loop, while the insulation remains completely closed on the remaining loop areas. In the loop area containing the openings 23, the outward-facing surface of the wire 15 is reduced by approximately 50%, preferably 70 to 80%, by the insulating sheath between the openings 23.

An advantage when using a wire rope 15 with a strand structure is shown with regard to the anchoring of the insulating sheath 19, in particular next to the openings 23 in the insulating sheath 19. The groove 29 lying between two adjacent strands 25, 27 becomes clear when the insulating material is applied filled in on the wire rope 1 5. The insulating material takes on the contour of the groove 29 and accordingly the shape of a tapered dome, which cooperates with the groove 29 of the wire rope 15 to anchor it. Such an anchoring means prevents the insulating sheath 19, 23 from slipping off the loop electrode 7, especially when it is being used, and thereby exposing the electrode surface which could possibly impair healthy patient tissue.

In plan view, at least on average, the openings can be substantially as long as they are wide, for example approximately circular or polygonal, or they can also be elongated, with a middle one Opening diameter or average gap width from 0.005 to 0.5 mm. The layer thickness of the insulating sheath on the wires 1 5 outside the groove 29 is approximately 0.02 to 0.3 mm. The insulating jacket can be sprayed on from plastic, optionally subsequently heat-treated (sintered) at a temperature of 300 to 400 ° C., in particular in the case of PTFE, or also by immersion treatment. In the case of non-area-wide spraying, the remaining gaps form the openings 23. When the insulation sheathing is applied area-wide, the openings are subsequently machined in mechanically or by means of a laser. Preferred insulating materials are fluoroplastics, such as FEP, PFA (which is particularly easy to spray and highly sticky), or PEEK, polyimides and others.

The insulating sheath can be made of an electrically essentially completely insulating material, so that at low high-frequency currents the capacitive portion of the load resistance formed by the electrode reaches a remarkable size, albeit depending on the size of the micro-openings or that in the micro-openings exposed electrode surface flowing high frequency current contributes to the coagulation effect. When plasma cutting the tissue, the effective electrode area reduced to the total area of the micro-openings ensures that even with a comparatively low high-frequency power of the generator, plasma arcs can form in the micro-openings. The electrode is therefore equally suitable for coagulation as well as for plasma cutting of tissue.

In order to increase the electrical conductivity of the insulating jacket, electrically conductive particle or powder material, for example carbon black powder or metal powder, can be added to the normally electrically insulating base material of the insulating jacket. However, the electrical conductivity of the insulating jacket is clear in every case, for example many times lower than the electrical conductivity of the electrode components made of metal. FIG. 3 shows a construction variant in the manner of a papillotome, in which an electrode wire 7a is stretched between the free end of an arc 31 held on a tube or free handle 3a.

FIG. 4 shows the tip 25 of a loop electrode similar to that of FIG. 1, but in a variant in which the wire 15 is coated with a hardenable plastic or lacquer in a densely insulating manner before it is deformed. After the insulating sheath has hardened, the wire 15 is deformed, for example bent and stretched, micro-openings in the form of jumps 23 'being formed in the relatively hard insulating sheath, which then define the effective electrode area. The direction of bending or deformation for producing the jumps 23 'can coincide with the direction of deformation for obtaining the ready-to-use electrode loop, but can also be different, as a result of which the direction and orientation of the jumps 23' - towards the inside or outside of the loop - to be able to control, such that the jumps are at least predominantly on the inside of the loop.

FIG. 5 shows an instrument similar to FIG. 1, but the insulating sheath 19 is formed from a large number of heat-shrinkable tube sections 19 ", one behind the other and then heat-shrunk, between the ends of one another Micro-openings in the form of columns 23 "in which the wire 15 is exposed, so that the column 23" defines the effective electrode areas (cf. FIG. 7). The gap density can be constant over the loop length or can also be variable, in particular in the area the tip 21 is denser than on the remaining loop sections 9, 11. The structure of this electrode also corresponds to the electrode of FIG. 1, so that reference is made to the associated description. FIG. 8 shows a rigid electrosurgical instrument with a spherical electrode 41 which is attached to the free end of an insulated rod-shaped neck 43. The neck 43 is attached to a handle 45. The electrode lead 5 leads away from the rear end of the handle. The electrode 41 has a diameter of approximately 1 to 5 mm and is used for hemostasis, desolation of tissue, removal of warts etc. The insulating sheath of the ball and the micro-openings 23 therein correspond to the embodiment in FIG. 1. Reference is made to the associated description.

FIG. 9 shows an instrument similar to FIG. 8, but with a knife-like or scalpel-like electrode 41 'with a length of 1 to 15 mm. The neck 43, the handle 45 and the electrode lead 5 correspond to FIG. 8.

Depending on the application, other electrode shapes are also possible. such as spoon-shaped, rod-shaped or rigid ring-shaped electrodes.

FIGS. 10a and 10b show a forceps-like electrosurgical instrument, the electrode 51 of which is divided into two electrode tongs 53, 55 which are resiliently tensioned away from one another and enlarged at the end. In this case, the two pliers 53, 55 can be electrically connected to one another for monopolar operation, or electrically separated for bipolar operation. The handle and the electrode feed correspond to Figure 8.

Claims

Expectations

1 . Electrosurgical instrument, comprising an electrode (7, 7a; 41, 41 ', 51) connected to an end of an electrode lead (5) near the patient with an electrically conductive electrode core

(1 5) made of metal and an insulating jacket (1 9) partially covering the surface of the electrode core (15) that can be used electrosurgically, made of a material whose electrical conductivity is many times lower than the electrical conductivity of the electrode core (1 5), characterized in that the insulating jacket (19) contains a plurality of micro-openings (23; 23 '; 23 ") which penetrate the insulating jacket (19) at least in a partial area of the surface of the electrode core (15) which can be used electrosurgically.

2. Electrosurgical instrument according to claim 1, characterized in that the insulating jacket (1 9) essentially covers the entire surface of the electrode core (1 5) that can be used electrosurgery.

3. Electrosurgical instrument according to claim 2, characterized in that the insulating jacket (1 9) contains micro-openings (23; 23 '; 23 ") essentially in the region of the entire surface of the electrode core (1 5) that can be used electrosurgically.

4. Electrosurgical instrument according to claim 1 or 2, characterized in that in the partial area (21) of the insulating jacket containing the micro-openings (23; 23 '; 23 ") the free electrode surface through the insulating jacket (1 9) by approx. 50 % to about 99%, preferably reduced by about 70% to 99%.

5. Electrosurgical instrument according to one of claims 1 to 4, characterized in that the width of the micro-openings is 0.005 to 1 mm, preferably approximately 0.01 to 0.5 mm.

6. Electrosurgical instrument according to one of the preceding claims, characterized in that the width of the micro-openings is 0.01 to 50 times, preferably 1 to 10 times, particularly preferably 0.5 to 2 times the thickness of the insulating jacket (1 9), in particular with a layer thickness of 0.02 to 0.3 mm, preferably from 0.05 to 0.1 2 mm.

7. Electrosurgical instrument according to one of the preceding claims, characterized in that the micro-openings (23) are subsequently introduced into a previously applied insulating material layer.

8. Electrosurgical instrument according to claim 7, characterized in that the micro-openings (23) are introduced mechanically or by exposure to radiation, in particular by means of a laser.

9. Electrosurgical instrument according to one of claims 1 to 6, characterized in that the micro-openings are cracks (23 ') generated in the insulating jacket (1 9') by deformation, in particular bending or stretching, of the insulated electrode core.

1 0. Electrosurgical instrument according to claim 9, characterized in that the insulating jacket (1 9 ') is embrittled to a degree that allows crack formation before the electrode core is deformed.

1 1. Electrosurgical instrument according to one of the preceding claims, characterized in that the insulating jacket (1 9, 19 ') is sprayed, sputtered, lacquered, extruded or applied by dipping onto the electrode core.

1 2. Electrosurgical instrument according to one of claims 1 to 6, characterized in that rings (1 9 ") made of insulating material are placed one behind the other on the electrode core (1 5) and gaps (23") remaining between the rings (1 9 ") which form micro-openings that leave the effective electrode surface free.

1 3. Electrosurgical instrument according to claim 1 2, characterized in that the rings (1 9 ") are formed from heat-shrinking material, in particular shrink tubing, and after being placed on the electrode core (1 5) are shrunk.

14. Electrosurgical instrument according to one of claims 1 to 6, characterized in that the micro-openings (23) are formed by applying, in particular spraying or sputtering, droplets to form an insulating material layer that is flat except for the micro-openings.

1 5. Electrosurgical instrument according to one of the preceding claims, characterized in that the insulating jacket (1 9) is formed from lacquer, polyamides, polyimides or a fluoroplastic, in particular from FEP, ETFE, ECTFE, PCTFE, PEEK, PTFE, preferably from MFA , PFA, FEP or a mixture of at least two of these materials.

1 6. Electrosurgical instrument according to one of the preceding claims, characterized in that the insulating jacket (1 9) made of an electrically insulating material, in particular synthetic material with a portion of electrically conductive particles, in particular plastic or metal, is formed.

1 7. Electrosurgical instrument according to one of the preceding claims, characterized in that the electrode (1 5) forms a loop (7) which is at least partially retractable into a tube (3).

1 8. Electrosurgical instrument according to claim 1 7, characterized in that the electrode area containing the micro-openings (23) on the apex (1 5) near the patient of the non-retracted part

Loop (7) lies.

1 9. Electrosurgical instrument according to claim 1 7 or 18, characterized in that the electrode area containing the micro-openings (23) lies essentially on the inside of the loop.

20. Electrosurgical instrument according to one of claims 1 to 1 6, characterized in that the electrode forms a solid body (41, 41 ').

21. Electrosurgical instrument according to claim 20, characterized in that the electrode forms a round body (41), in particular a ball, or a knife-like body (41 ').

22. Electrosurgical instrument according to one of claims 1 to 1 6, characterized in that the electrode (51) is divided into a pair of electrodes (53, 55) which can be moved towards one another in the manner of forceps.

23. Electrosurgical instrument according to one of claims 20 to 21, characterized in that the electrode is attached to an insulating handle part (45) via an insulating, jacketed, elongated neck (43).

24. Electrosurgical instrument according to claim 23, characterized in that the covered neck (43) is rigid or flexible.

25. Electrosurgical instrument according to one of the preceding claims, characterized in that the electrode in the instrument forms a monopolar electrode.

26. A method for producing an electrosurgical instrument, in which an insulating jacket (1 9) is applied to an electrode core (1 5) made of metal, the electrical conductivity of which is many times lower than the electrical conductivity of the electrode core (1 5), characterized in that that the insulating jacket (1 9) is first applied in a closed manner to at least part of the surface of the electrode core (1 5) that can be used electrosurgically and then micro openings are subsequently introduced into the insulating jacket mechanically or by exposure to radiation or by deformation, in particular bending or stretching, or that Insulating sheath (19) is formed on at least part of the surface of the electrode core (15) that can be used electrosurgically by spraying or sputtering on drops to form a layer containing micro-openings.