GB2580645A

GB2580645A - Electrosurgical apparatus

Info

Publication number: GB2580645A
Application number: GB1900747.5A
Authority: GB
Inventors: Hoodless Richard
Original assignee: Gyrus Medical Ltd
Current assignee: Gyrus Medical Ltd
Priority date: 2019-01-18
Filing date: 2019-01-18
Publication date: 2020-07-29
Anticipated expiration: 2039-01-18
Also published as: GB201900747D0; GB2580645B

Abstract

An electrosurgical apparatus 1 for coagulating tissue, the apparatus comprising: a tube 8 having proximal and distal ends, tube 8 being straight for most of its length so defining a longitudinal tube axis 12, where tube 8 defines a conduit though which an ionisable gas can be supplied to an aperture the tube’s distal end, and where tube 8 comprises an inner rigid component 9 covered by a polymeric sheath 21 that’s movable between advanced (Fig.3b) and retracted (Fig.3a) positions with respect to the inner rigid-component 9; and an electrode 17 for ionising the gas prior to it exiting the tube’s distal end aperture. In the advanced position, electrode 17 is situated within tube 8 and in the retracted position electrode 17 extends through the aperture at the tube’s distal end at a non-zero angle with respect to the tube’s longitudinal axis 12. Preferably electrode 17 is curved so its proximal end is parallel with the tube’s longitudinal axis 12 and its distal end is at the non-zero angle, where rigid inner-component 9 is straight for its entire length and sheath 21 is pre-formed so it forms itself into a curved shape once it extends beyond the inner rigid-component 9.

Description

ELECTROSURGICAL APPARATUS

This invention relates to an electrosurgical apparatus and in particular to the coagulation of tissue using an ionisable gas such as argon. Argon beam coagulators have 5 been known for many years, and examples are given in US patents 4,040,426, 5,720,745, 6,039,736 and 6,197,026. The first example is an end-effect instrument, in which the ionised gas exits through the end of the instrument, while the latter two examples are directed at side-effect instruments, in which the ionised gas exits the instrument though an aperture in the side of the instrument. Such instruments are often referred to as APC 10 instruments (Argon Plasma Coagulation).

US patent 5,693,044 proposes an instrument in which an electrode can be either retracted within a housing such that the instrument acts as a non-contact APC instrument, or advanced out of the housing such that the instrument acts as a tissue-contacting cutting instrument. The present invention attempts to provide an improved version of such a multi-purpose instrument.

Accordingly, an electrosurgical apparatus is provided for coagulating tissue, the apparatus comprising: a rigid tube having a proximal end and a distal end, the tube being straight for at least the majority of its length so as to define a longitudinal axis, the tube defining a conduit though which ionisable gas can be supplied to the distal end of the tube, the tube comprising an inner rigid component covered by a sheath of polymeric material, the tube including an end aperture such that the ionisable gas is capable of exiting the distal end of the tube, an electrode for ionising the ionisable gas prior to the gas exiting the tube, an electrical connection for connecting the electrode to the output of an electrosurgical generator, characterised in that the sheath is movable between advanced and retracted positions with respect to the inner rigid component, and that the apparatus includes an actuator for moving the sheath between its advanced and retracted positions, the advanced position being such that the electrode is situated within the tube, and the retracted position being such that the electrode extends through the aperture from the distal end of the tube, and that in its retracted position the electrode extends from the distal end of the tube with the distal end of the electrode at a non-zero angle to the longitudinal axis of the tube.

By providing an electrode where the distal end is at a non-zero angle to the longitudinal axis, the apparatus allows for improved orientation of the electrode with respect to tissue, better manipulation of tissue, and improved access to areas previously difficult to access with a linear longitudinal electrode. The angle provided by the distal end of the electrode can make it easier to resect tissue. The electrode conveniently extends from the distal end of the tube with the distal end of the electrode at an angle of 10 between 5 and 90 degrees to the longitudinal axis of the tube, preferably between 10 and 60 degrees, and typically between 15 and 45 degrees to the longitudinal axis of the tube. The tube comprises an inner rigid component covered by a sheath of polymeric material. Typically, the inner rigid component is an inner tube formed from a metallic material, although other rigid materials such as stiff polymers or composite materials can be used to provide the inner component. The sheath and the electrode are translatable one with respect to the other so as to change the sheath between its advanced and retracted positions. The electrode is stationary, and the sheath is advanced and retracted with respect to the electrode. When the sheath is advanced to cover the electrode, the apparatus is suitable for the non-contact coagulation of tissue. When the sheath is retracted so as to expose the electrode, the apparatus is suitable for the contact cutting and resection of tissue.

Where present, the combination of the inner component and the outer sheath constitutes the "tube", and the electrode is either situated within (when the sheath is in its advanced position) or extends from (when the sheath is in its retracted position) the combination of the inner component and the sheath.

According to one arrangement, the electrode is straight, and is positioned within an end portion of the tube which is at the non-zero angle to the longitudinal axis of the majority of the tube. Thus the electrode is not in itself curved, but merely positioned at an offset angle to the longitudinal axis of the tube. Where the tube comprises a rigid inner component and an outer sheath, the rigid inner component is conveniently formed with a distal section at the non-zero angle to the longitudinal axis of the tube. When the sheath is advanced over the inner component to cover the, the sheath conforms to the angled distal section of the inner component and extends at the same offset angle. Conversely, when the sheath is withdrawn, exposing the, the electrode extends at the non-zero angle to the longitudinal axis of the tube.

Alternatively, the electrode is curved such that its proximal end is parallel with the longitudinal axis of the tube, and its distal end is at the non-zero angle to the longitudinal axis of the majority of the tube. Where the tube comprises a rigid inner component and an outer sheath, the rigid inner component is conveniently straight for its entire length. The sheath is preferably preformed such that it forms itself into a curved shape once it extends beyond the inner component. When the sheath is advanced over the inner component to cover the electrode, the sheath assumes its preformed curved shape following the curve of the electrode. Conversely, when the sheath is withdrawn, exposing the electrode, the distal end of the curved electrode extends at the non-zero angle to the longitudinal axis of the tube.

Alternatively, instead of preforming the sheath into a curved shape, the sheath is conceivably provided with a guide member such that, once the sheath extends beyond the inner component, the guide member forms the sheath into a curved shape. The guide member urges the sheath into its curved shape once it projects from the rigid inner component, following the contour of the curved electrode. Conveniently, the guide member comprises a guidewire, typically formed from a shape memory alloy.

Whichever arrangement is employed, when the sheath is in its advanced position, the distance between the electrode and the sheath is the same at all positions along the electrode. By having the sheath follow the contour of the electrode, whether it be curved or angled, the geometry surrounding the electrode is consistent, thereby ensuring consistent and repeatable ionisation of the gas surrounding the electrode. Conveniently, where provided, the inner component is also provided with an inner layer of insulating material, typically a polymeric material. This helps to prevent ionisation of the gas travelling along the tube until it reaches the electrode.

Where the electrode is a needle electrode, its dimensions are the same in all radial directions. However, conceivably, the electrode has a length, a height and a width, the height of the electrode being greater than its width so as to define a vertical axis and a vertical plane. Regardless of whether the electrode has a vertical axis, the plane in which the electrode extends offset to the longitudinal axis can make a difference. In one arrangement, when the sheath is in its retracted position, the electrode extends from the distal end of the tube in a plane which contains the longitudinal axis of the tube. Alternatively, when the sheath is in its retacated operating position, the electrode conceivably extends from the distal end of the tube in a plane which does not contain the longitudinal axis of the tube. These arrangements help to provide increased dexterity for the instrument, and the ability for the electrode to access difficult to reach tissue structures. By providing an electrode with a distal end offset to the longitudinal axis of the tube, the surgeon can use the instrument to manipulate and treat tissue in a variety of positions.

The invention will now be further described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a plan view of an electrosurgical instrument in accordance with the present invention, Figure 2 is a schematic sectional plan view of the distal portion of the electrosurgical instrument of Figure 1, Figure 3a is a schematic sectional plan view of the distal portion of an alternative embodiment of electrosurgical instrument in accordance with the present invention, the instrument shown in a first operating position, Figure 3b is a schematic sectional plan view of the distal portion of the electrosurgical instrument of Figure 3a, the instrument shown in a second operating position, Figure 4a is a schematic sectional plan view of the distal portion of an alternative embodiment of electrosurgical instrument in accordance with the present invention, the instrument shown in a first operating position, Figure 4b is a schematic sectional plan view of the distal portion of the electrosurgical instrument of Figure 4a, the instrument shown in a second operating position, Figure 5a is a cross-sectional end view of an alternative embodiment of electrosurgical instrument in accordance with the present invention, Figure 5b is a schematic sectional plan view of the distal portion of the electrosurgical instrument of Figure 4a, Figure 6 is a schematic perspective view of an electrosurgical instrument similar to that shown in Figure 2, and Figure 7 is a schematic perspective view of an alternative embodiment of electrosurgical instrument similar to that shown in Figure 2.

Referring to Figure 1, an APC instrument shown generally at 1 comprises a flexible elongate tube 2 having a proximal end 3 and a distal end 4. A connector 5 is present at the proximal end of the tube, for connecting the instrument 1 to an electrosurgical generator (not shown). The tube 2 is in two parts, a first proximal length 6 formed of PTFE, and a second distal length 7 formed of Polyurethane. At the distal end 4 of the tube 2 is a rigid tube 8, which will now be described in more detail.

Referring to Figure 2, the rigid tube 8 is formed from an inner component in the form of a stainless-steel pipe 9, coated on its inner surface with a layer of insulating polymeric material 10 such as Polyimide. The pipe 9 has a straight section 11 extending the majority of its length, such that the rigid tube has a longitudinal axis 12. The distal end of the pipe 9 has a preformed bent section 13, the bent section being formed by means of a curved section 14 and a straight end section 15. The effect of the curved section 14 is that the straight end section 15 extends at an angle of approximately 30 degrees to the longitudinal axi s 12.

Located in fixed relationship within the pipe 9 is an electrode holder 16, the electrode holder being a mounting for a needle electrode 17. The electrode 17 extends both proximally and distally of the electrode holder 16, a lead 18 providing a connection for the supply to the electrode of an electrosurgical voltage from the electrosurgical generator. The lead is covered with an insulating coating 19 such as PTFE, to prevent any arcing or capacitive coupling between the lead 18 and the stainless-steel pipe 9. The electrode 17 extends distally of the electrode holder 16 to form a tissue treatment section 20, the tissue treatment section 20 extending at an angle of approximately 30 degrees to the longitudinal axis 12.

External to the stainless-steel pipe 9 is an outer sheath 21, also of PTFE. The sheath 21 is translatable over the pipe 9 between retracted and advanced positions. In a first operating position (shown in dashed lines in Figure 2) the sheath 21 is advanced beyond the end of the pipe 9 such that the electrode 17 does not extend from the end of the sheath. In this position, in use, an ionisable gas such as argon is supplied through the elongate tube 2, along the pipe 9 and over the electrode 17. A high voltage electrosurgical voltage is supplied to the electrode 17 via the lead 18, such that the argon gas is ionised into a plasma, which emerges from the open end of the sheath. The plasma impinges on tissue situated near to the end of the instrument 1, causing it to be coagulated. Alternatively, the sheath 21 is retracted (by an actuator-not shown) such that the tissue treatment section 20 of the electrode 17 is exposed. In this second operating position the instrument can be used as a contact tissue cutting and resection device. The tissue treatment section 20 of the electrode is placed in contact with tissue, and a different electrosurgical energy is supplied to the electrode 17 from the electrosurgical generator. Tissue coming into contact with the tissue treatment section 20 is cut by the electrosurgical energy, enabling tissue cutting and tissue resection to take place. As the electrode 17 extends at an angle of approximately 30 degrees to the longitudinal axis 12, the tissue treatment section 20 can access tissue even if it is not immediately in front of the instrument 1. Furthermore, rotating the tube 8 about the longitudinal axis 12 causes the tissue treatment section 20 to be moved in different directions, allowing access to a range of tissue locations.

Figure 3a shows an alternative embodiment of instrument, in which similar components are designated with like reference numerals. The stainless-steel pipe 9 is as before, except that the curved section 14 is omitted such that the pipe is linear along its entire length. The electrode holder 16 is as before, with an electrode 17 connected to an electrosurgical generator (not shown) by means of lead 18. The electrode 17 is different from that of Figure 2, in that it has a curved shape such that while the proximal end of the electrode adjacent the electrode holder is aligned with the longitudinal axis 12, the distal end 22 of the electrode is at an angle of approximately 30 degrees to the longitudinal axis 12.

The PTFE outer sheath 21 is translatable over the pipe 9 between retracted and advanced positions as before. However, when the sheath 21 is preformed into a curved shape such that when it is advanced beyond the end of the pipe 9 the extended portion of the sheath curves so as to match the curvature of the electrode 17, as shown in Figure 3a. In the position shown in Figure 3a, an ionisable gas is supplied as before, and a high voltage electrosurgical voltage is supplied to the electrode 17 via the lead 18, such that the argon gas is ionised into a plasma. The plasma impinges on tissue situated near to the end of the instrument 1, causing it to be coagulated.

When the instrument is required to act as a contact tissue resection instrument, the sheath 21 is retracted over the pipe as shown in Figure 3b. In this position, the tissue treatment section 20 of the electrode 17 is exposed, such that when it is placed in contact with tissue, and a electrosurgical energy supplied to the electrode 17, the tissue coming into contact with the tissue treatment section 20 is cut and/or resected. As the distal end 22 of the electrode is at an angle to the longitudinal axis 12, the tissue treatment section 20 can access tissue even if it is not immediately in front of the instrument 1.

Figures 4a and 4b show an alternative embodiment in which an extra layer is provided between the pipe 9 and the outer sheath 21. This layer 23 is formed from a low friction material such as PTFE, and allows the sheath 21 to move easily over the pipe 9.

Other than the provision of the low friction layer 23, the construction and operation of the apparatus of Figures 4a and 4b is identical with that of Figures 3a and 3b.

In Figures 5a and 5b, the sheath 21 is not preformed into a curved shape, but urged into such a curved shape by a guidewire 24. The guidewire 24 is formed of nitinol, and has been formed into a naturally curved shape. The guidewire is received within a channel 25 located within the sheath 21, such that when the sheath is extended beyond the distal end of the pipe 9, the guidewire urges the sheath 21 to assume a curved configuration matching the curvature of the electrode 17.

As before, the sheath can either be extended beyond the pipe 9 to cover the electrode 17 for argon gas coagulation of tissue (the position shown in Figure 5b), or withdrawn back over the pipe 9 to expose the curved electrode 17 for contact tissue cutting. When extended, the sheath is formed into a curve to maintain a substantially constant spacing between the electrode and the sheath, despite the curvature of the electrode 17.

Figure 6 shows an arrangement similar to that of Figure 2 in which the pipe 9 has a curved section 14 and a straight end section 15 such that the end section extends at an angle to the longitudinal axis 12. In Figure 6, the end section 15 extends in a plane 25 which contains the longitudinal axis 12.

Figure 7 shows an alternative arrangement in which the curved section 14 is such that the end section 15 extends in a different plane 26. The plane 26 does not contain the longitudinal axis 12 of the tube 8. This more complex curvature of the instrument allows the user to access more difficult to reach tissue, and manipulate tissue impossible to reach with a straight instrument.

Those skilled in the art will appreciate that other constructions can be envisaged without departing from the scope of the present invention. For example, the electrode 17 illustrated in Figures 2 to 4 is a needle electrode, so its dimensions are the same in all radial directions. Therefore, the plane in which the electrode extends at an angle to the longitudinal axis is immaterial. However, an alternative construction is envisaged in which the electrode has a length, a height and a width, the height of the electrode being greater than its width so as to define a vertical axis and a vertical plane. In this instance, where the electrode has a geometry defining a vertical plane, the plane in which the electrode extends offset to the longitudinal axis can make even more of a difference.

The embodiments illustrated in Figure 1 to 4 are monopolar arrangements, with a single electrode present on the instrument, and a return electrode in the form of a remote patient plate. Alternatively, bipolar versions of the instrument are possible, depending on the intended use, and different versions of the system can be envisaged for different endoscopic procedures.

Claims

Claims 1. An electrosurgical apparatus for coagulating tissue, comprising: a rigid tube having a proximal end and a distal end, the tube being straight for at least the majority of its length so as to define a longitudinal axis, the tube defining a conduit though which ionisable gas can be supplied to the distal end of the tube, the tube comprising an inner rigid component covered by a sheath of polymeric material, the tube including an end aperture such that the ionisable gas is capable of exiting the distal end of the tube, an electrode for ionising the ionisable gas prior to the gas exiting the tube, an electrical connection for connecting the electrode to the output of an electrosurgical generator, characterised in that the sheath is movable between advanced and retracted positions with respect to the inner rigid component, and that the apparatus includes an actuator for moving the sheath between its advanced and retracted positions, the advanced position being such that the electrode is situated within the tube, and the retracted position being such that the electrode extends through the aperture from the distal end of the tube, and that in its retracted position the electrode extends from the distal end of the tube with the distal end of the electrode at a non-zero angle to the longitudinal axis of the tube.
2. Apparatus according to claim 1, wherein the electrode extends from the distal end of the tube with the distal end of the electrode at an angle of between 5 and 90 degrees to the longitudinal axis of the tube.
3. Apparatus according to claim 2, wherein the electrode extends from the distal end of the tube with the distal end of the electrode at an angle of between 10 and 60 degrees to the longitudinal axis of the tube.
4. Apparatus according to claim 3, wherein the electrode extends from the distal end of the tube with the distal end of the electrode at an angle of between 15 and 45 degrees to the longitudinal axis of the tube.
5. Apparatus according to any preceding claim, wherein the inner rigid component is an inner tube formed from a metallic material.
6. Apparatus according to any preceding claim, wherein the electrode is straight, the electrode being positioned within an end portion of the tube which is at the non-zero angle to the longitudinal axis of the majority of the tube.
7. Apparatus according to any of claims 1 to 5, wherein the electrode is curved such that its proximal end is parallel with the longitudinal axis of the tube, and its distal end is at the non-zero angle to the longitudinal axis of the majority of the tube.
8. Apparatus according to claim 7, wherein the rigid inner component is straight for its entire length.
9. Apparatus according to claim 7 or claim 8, wherein the sheath is preformed such that it forms itself into a curved shape once it extends beyond the inner component.
Apparatus according to claim 7 or claim 8, wherein the sheath is provided with a guide member such that, once the sheath extends beyond the inner component, the guide member forms the sheath into a curved shape.
11. Apparatus according to claim 10, wherein the guide member comprises a guidewire.
12. Apparatus according to claim 11, wherein the guidewire is formed of a shape memory alloy.
13. Apparatus according to any preceding claim, wherein, when the sheath is in its advanced position, the distance between the electrode and the sheath is the same at all positions along the electrode.
14. Apparatus according to any preceding claim, wherein the rigid inner component is also provided with an inner layer of insulating material.
15. Apparatus according to claim 14, wherein the inner layer of insulating material comprises a polymeric material.
16. Apparatus according to any preceding claim, wherein, when the sheath is in its retracted position, the electrode extends from the distal end of the tube in a plane which contains the longitudinal axis of the tube.
17. Apparatus according to any of claims 1 to 15, wherein, when the sheath is in its retracted position, the electrode extends from the distal end of the tube in a plane which does not contain the longitudinal axis of the tube.