GB2549279A

GB2549279A - Electrode assembly

Info

Publication number: GB2549279A
Application number: GB1606099.8A
Authority: GB
Inventors: Atwell Tony
Original assignee: Gyrus Medical Ltd
Current assignee: Gyrus Medical Ltd
Priority date: 2016-04-11
Filing date: 2016-04-11
Publication date: 2017-10-18
Anticipated expiration: 2036-04-11
Also published as: GB2549279B

Abstract

An electrode assembly for use in a resectoscope, the assembly comprising an electrode (30) and a support 34 for the electrode 30; the support 34 including one or more depth stop members 38, 39 having a substantially planar surface. The depth stop(s) 38, 39 establishing a predetermined distance x between the planar surface and the electrode 30 so as to regulate the depth of tissue removed. The depth stop member(s) 38, 39 further being tillable so as to be capable of closely following the profile of the tissue being treated to ensure an even cut, even over an uneven surface. In a preferable embodiment the electrode 30 is formed as a U-shaped loop comprising side members 31, 32 and a bottom member 33 running therebetween. In this embodiment the depth stops 38, 39 may tilt in at least two directions - about axes extending both orthogonal to and parallel to the bottom member 33 of the loop. A claim is also provided for a method of using the assembly for removing a bladder tumour.

Description

ELECTRODE ASSEMBLY

This invention relates to an electrode assembly for a surgical instrument for the treatment of tissue, particularly an electrosurgical endoscopic instrument. Such systems are commonly used for the vaporisation and/or coagulation of tissue in surgical intervention, most commonly in “keyhole” or minimally invasive surgery.

One type of electrosurgical procedure is endoscopic urological surgery using a resectoscope. Such systems are well known in the art, examples being given in US Patents 5,007,907 and 6,322,494. Such systems include an electrosurgical instrument deployable by means of a resectoscope, and an electrosurgical generator powering the instrument. Instruments used in electrosurgical urology surgery are either bipolar, in which case two electrodes are present at the distal end of the instrument, or monopolar, in which case one electrode is present on the instrument and a second electrode is provided in the form of a patient return plate.

Bladder tumour resection is often difficult due to the curved shape of the tissue, and the fact that there is no clear dissection plane visible to the surgeon. Deviating from the ideal depth of tissue removal either means that insufficient tissue is removed, or the too much tissue is removed, including the possibility of perforating the bladder.

The present invention attempts to provide a solution to this problem by providing an electrode assembly for use in a resectoscope, the electrode assembly comprising a tissue treatment element, a support for the tissue treatment element, connection means for connecting the tissue treatment element to a source of electrosurgical energy, and one or more depth stop members connected to the support and including a substantially planar surface, the one or more depth stop members establishing a predetermined distance between the planar surface and the tissue treatment element so as to regulate the depth of tissue removed by the tissue treatment element, characterised in that the one or more depth stop members are mounted on the support so as to be capable of tilting in at least one direction so as to be capable of following the profile of tissue being treated.

Not only do the depth stop members regulate the depth of tissue resection, but they also tilt in order to follow the profile of the tissue, even if the profile is curved.

Preferably, the one or more depth stop members are mounted on the support so as to be capable of tilting in at least two directions. In this way, the surgeon is able to remove a constant depth of tissue, even if the tissue is being removed from an organ having a curved surface.

The tissue treatment element conceivably comprises a roller electrode, or a slider electrode such as a button electrode. More preferably, the tissue treatment element comprises a generally U-shaped loop, with first and second side members and a bottom member running therebetween. These loop-type electrodes are commonly used for tissue resection, often to remove small strips of tissue having a relatively constant thickness.

According to one convenient arrangement, the bottom member is generally linear defining a bottom member longitudinal axis. Thus, the U-shaped loop has a flat bottom, rather than a curved or V-shaped profile. Conveniently, the one or more depth stop members are mounted on the support so as to be capable of tilting about an axis running parallel to the bottom member longitudinal axis, preferably tilting about the bottom member longitudinal axis itself. In this way, the one or more depth stop members can tilt up and down as the profile of the tissue changes as the loop is moved forwardly or rearwardly with respect to the tissue. This allows the loop to remove a relatively constant depth of tissue despite the tissue surface curving upwardly or downwardly in the direction of travel of the tissue treatment element.

Alternatively or additionally, the one or more depth stop members are mounted on the support so as to be capable of tilting about an axis running orthogonal to the bottom member longitudinal axis. In this way, the one or more depth stop members are able to tilt from side to side with respect to the direction of travel of the tissue treatment element. This allows the loop to remove a relatively constant depth of tissue despite the tissue surface curving sideways across the direction of travel of the tissue treatment element. Preferably, the one or more depth stop members are mounted on the support so as to be capable of tilting about both axes, those running parallel and orthogonal to the bottom member longitudinal axis. Thus, even if the tissue surface is curved like the surface of a sphere, the one or more depth stop members are able to tilt in order to regulate the depth of tissue removal so as to remove a relatively constant depth of tissue from the bowl-shaped surface of the organ.

The one or more depth stops conveniently comprise a pair of plates. According to a preferred arrangement, the bottom member changes from a generally linear shape to a generally curved shape when the plates tilt about an axis running orthogonal to the bottom member longitudinal axis. This means that the cutting loop is able to remove a relatively flat piece of tissue from a relatively flat tissue surface, and a curved piece of tissue from a curved tissue surface.

The invention further resides in an electrode assembly for use in a resectoscope, the electrode assembly comprising a tissue treatment element in the form of a generally U-shaped loop, with first and second side members and a bottom member running therebetween, a support for the tissue treatment element, connection means for connecting the tissue treatment element to a source of electrosurgical energy, a pair of depth stop members connected to the support and each including a substantially planar surface, the depth stop members establishing a predetermined distance between the planar surface and the tissue treatment element so as to regulate the depth of tissue removed by the tissue treatment element, characterised in that the depth stop members are mounted on the support so as to be capable of tilting in at least one direction that the tissue treatment electrode is capable of removing a uniform depth of tissue even when the tissue surface is curved. Typically the pair of depth stop members are mounted on the support so as to be capable of tilting in at least two directions.

The invention also resides in a method of surgically removing a bladder tumour comprising the steps of i) introducing a resectoscope into a surgical site within the body of a patient, the resectoscope including a lumen, ii) introducing an elongate electrode assembly into the lumen, the elongate electrode assembly comprising a tissue treatment element, a support for the tissue treatment element, and one or more depth stop members disposed from the support and including a substantially planar surface, the one or more depth stop members being mounted on the support so as to be capable of tilting in at least one direction, iii) connecting the tissue treatment element to a source of electrosurgical energy, and iv) moving the electrode assembly in a curved motion over the surface of the bladder with the one or more depth stop members tilting to follow the curved surface of the bladder so as to establish a predetermined distance between the planar surface and the tissue treatment element, such that a substantially even depth of tissue is removed by the tissue treatment element along the curved motion of movement of the electrode assembly.

The invention will now be further described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of an electrosurgical system including an electrode assembly in accordance with the present invention,

Figure 2 is an exploded view of a resectoscopic instrument used as part of the electrosurgical system of Figure 1,

Figures 3 A to 3E are schematic views of an active electrode assembly according to the present invention, shown in different positions during use,

Figure 4 shows an enlarged view of a part of the electrode assembly of Figure 3 A, and

Figure 5 shows a further view of a part of the electrode assembly of Figure 3 A.

Referring to Figure 1, a generator 1 has an output socket 2 providing a radio frequency (RF) output for an instrument 3 via a connection cord 4. Activation of the generator may be performed from the instrument 3 via a connection in cord 4 or by means of a footswitch unit 5, as shown, connected to the rear of the generator by a footswitch connection cord 6. In the illustrated embodiment footswitch unit 5 has two footswitch pedals 7 and 8 for selecting a coagulation mode and a cutting mode of the generator respectively. The generator front panel has push buttons 9 and 10 for respectively setting coagulation and cutting power levels, which are indicated in a display 11. Push buttons 12 are provided as a means for selection between alternative coagulation and cutting waveforms.

As shown in Figure 2, the instrument 3 is deployed through a resectoscope 13 including an inner sheath 14, an outer sheath 15, and a rod lens telescope/light source assembly 16. The instrument 3 is part of a working element, indicated generally by the reference W, to the right of the dotted line shown in FIG. 2, and including a bipolar electrode assembly 17. The electrode assembly is conceivably collapsible for insertion and then deployable once in position within the body of the patient for the treatment of tissue.

The sheaths 14 and 15 provide for the circulation of a fluid medium to an operating site, with the outer sheath 15 being used for fluid delivery via input connector 18, and the inner sheath being used for aspiration of the fluid via suction connector 30. The outer sheath 15 locks over the inner sheath 14, forming a watertight seal. Typically, the inner sheath 14 has a diameter of 24Fr, and the outer sheath 15 has a diameter of 27 Fr. The telescope assembly 16 provides the means of illuminating and viewing the operative site via a light source (not shown) connected thereto by a connector 19. The viewing angle of the telescope is generally at 30° to its axis.

The working element W may be either passive or active, that is to say the cutting stroke of the electrode may be as the result of a spring bias or against the force of a spring bias. The resectoscope 13 includes a telescope support tube 20 having a telescope connector 21 at its proximal end, and a sealing block 22 located part way along the support tube 20, the inner sheath 14 being connected to the sealing block. Both of these interfaces are watertight. An electrode support tube 23 is attached to the underside of the telescope support tube 20 on the distal side of the sealing block 22 for the majority of its length. Two spring-loaded links 24 and an insulation block 25, located between the sealing block 22 and the telescope connector 21, make up the mechanism. The active mechanism is arranged so that the spring-loaded links 24 assist the forward stroke, while, in the passive version the links aid the backward stroke. In general, the range of travel is about 25 mm.

The bipolar electrode assembly 17 includes an active electrode 26 in the form of a loop, roller, slider or button, and a return electrode 27 located on the shaft of the electrode assembly. The electrodes 26 & 27 are connected to the generator 1 via cord 4 connected via socket 28. The electrode support tube 23 is also formed of electrically conductive material, and constitutes a further return electrode, also connected to the generator 1 via cord 4.

Figures 3A to 3E show an active electrode assembly 40 including an active electrode 26 in the form of a loop 30, comprising side portions 31 & 32 interconnected by a bottom portion 33. The loop 30 is carried by an electrode support 34 in the form of an inverted “U” and consisting of a pair of arms 35 & 36 meeting at a top portion 37. At the distal end of the arm 35 is a flat plate 38, and a similar flat plate 39 is located at the distal end of the arm 36. The loop 30 extends between the flat plates 38 & 39, with the side portion 31 depending from the plate 38 and the side portion 32 from the plate 39.

Figure 3A shows the electrode assembly 40 being used against a tissue surface (not shown) which is essentially flat, such that the plates 38 & 39 lie substantially horizontal. The plates define a predetermined distance “x” between the bottom of the plates and the bottom portion 33 of the loop. This distance “x” is the depth of tissue which will be cut as the electrode assembly 40 is moved with respect to the tissue with the plates 38 & 39 resting on the surface thereof.

Figure 3B shows the electrode assembly 40 being used on tissue which is sloping downwardly. As shown in Figure 3B, the plates 38 & 39 tilt downwardly, causing a corresponding tilting in the loop 30. However, the distance between the bottom of the plates and the bottom portion 33 of the loop is still the same, resulting in tissue with a depth of distance “x” being removed as the electrode is moved relative to the tissue.

Similarly, Figure 3C shows the electrode assembly 40 being used on tissue which is inclined. In this instance plates 38 & 39 tilt upwardly, causing a corresponding tilting in the loop 30. As before, the distance between the bottom of the plates and the bottom portion 33 of the loop is still the same, resulting in tissue with a depth of distance “x” being removed, whatever the surface profile of the tissue.

Figures 3D & 3E show the electrode assembly 40 being used on tissue which is curved transversely to the loop 30. In this instance the plate 38 tilts downwardly from outside to in, while the plate 39 tilts upwardly from inside to out, each plate tilting to accommodate the curvature of the tissue. The tilting of the plates 38 & 39 causes the loop 30 to deform, with the bottom portion 33 becoming curved instead of linear as shown in Figures 3D & 3E. The curved bottom portion 33 means that the loop 30 will cut a curved profile into the tissue, such that the depth of tissue cut by the loop will still match the surface profile of the tissue, regulated by the distance “x” between the bottom of the plates and the bottom portion 33 of the loop. In practice, the surface profile of the tissue may be complex, resulting in a combination of longitudinal and lateral tilting of the plates 38 & 39. As the plates conform to the surface of the tissue as much as possible, the depth of tissue removed by the loop 30 will be relatively constant, whatever the profile.

Figures 4 & 5 show the mounting of the plates 38 & 39 with respect to the arms 35 & 36 which allow the plates to tilt in two directions. Referring to Figure 4, arm 35 has a circular hole 41 towards its distal end, and a spindle 42 passes through the hole. The spindle links two welded buttons 43 & 44 connecting the spindle 42 to the plate 38. A slot 45 cut into the plate 38 accommodates the end of the arm 35, and the side portion 31 of the loop 30 is attached to the button 44. A similar arrangement exists at the end of arm 36, with similar components given the same reference numerals, as shown in Figure 5.

When the electrode assembly is placed against tissue with an inclining or declining profile, the plates 38 & 39 will be tilted upwardly or downwardly as shown in Figures 3B or 3C. In these instances, the spindles 42 will rotate in the holes 41 to allow the plates 38 & 39 to tilt accordingly. It will be appreciated that the holes 41 are of a larger diameter than that of the spindles 42, such that when the electrode assembly is placed against tissue which has a transversely curved profile, the plates 38 & 39 can tilt sideways with the spindles 42 becoming angled in the holes 41. This is the situation shown in Figure 5, in which the bottom portion 33 of the loop also becomes curved to match the tissue profile.

Those skilled in the art will appreciate that arrangements other than those described above can be employed without departing from the scope of the present invention. For example, while the embodiments of Figures 3 to 5 illustrate the use of a loop electrode, other electrodes such as rollers, sliders or buttons can be employed, with the plates 38 & 39 still ensuring that a predetermined distance “x” is maintained between the bottom of the plates and the cutting surface of the electrode, whatever the profile of the tissue.

Claims

1. An electrode assembly for use in a resectoscope, the electrode assembly comprising a tissue treatment element, a support for the tissue treatment element, connection means for connecting the tissue treatment element to a source of electrosurgical energy, and one or more depth stop members connected to the support and including a substantially planar surface, the one or more depth stop members establishing a predetermined distance between the planar surface and the tissue treatment element so as to regulate the depth of tissue removed by the tissue treatment element, characterised in that the one or more depth stop members are mounted on the support so as to be capable of tilting in at least one direction so as to be capable of following the profile of tissue being treated.

2. An electrode according to claim 1, wherein the one or more depth stop members are mounted on the support so as to be capable of tilting in at least two directions

3. An electrode according to claim 1 or claim 2, wherein the tissue treatment element comprises a roller electrode.

4. An electrode according to claim 1 or claim 2, wherein the tissue treatment element comprises a slider electrode.

5. An electrode according to claim 4, wherein the slider electrode comprises a button electrode.

6. An electrode according to claim 1 or claim 2, wherein the tissue treatment element comprises a generally U-shaped loop, with first and second side members and a bottom member running therebetween.

7. An electrode according to claim 6, wherein the bottom member is generally linear defining a bottom member longitudinal axis.

8. An electrode according to claim 7, wherein the one or more depth stop members are mounted on the support so as to be capable of tilting about an axis running parallel to the bottom member longitudinal axis.

9. An electrode according to claim 8, wherein the one or more depth stop members are mounted on the support so as to be capable of tilting about the bottom member longitudinal axis.

10. An electrode according to claim 7, wherein the one or more depth stop members are mounted on the support so as to be capable of tilting about an axis running orthogonal to the bottom member longitudinal axis.

11. An electrode according to claims 6 to 10, wherein the one or more depth stop members are mounted on the support so as to be capable of tilting about axes running parallel and orthogonal to the bottom member longitudinal axis.

12. An electrode according to any preceding claim, wherein the one or more depth stops comprise a pair of plates.

13. An electrode according to claims 10 and 12, wherein the bottom member changes from a generally linear shape to a generally curved shape when the plates tilt about an axis running orthogonal to the bottom member longitudinal axis.

14. An electrode assembly for use in a resectoscope, the electrode assembly comprising a tissue treatment element in the form of a generally U-shaped loop, with first and second side members and a bottom member running therebetween, a support for the tissue treatment element, connection means for connecting the tissue treatment element to a source of electrosurgical energy, a pair of depth stop members connected to the support and each including a substantially planar surface, the depth stop members establishing a predetermined distance between the planar surface and the tissue treatment element so as to regulate the depth of tissue removed by the tissue treatment element, characterised in that the depth stop members are mounted on the support so as to be capable of tilting in at least one direction that the tissue treatment electrode is capable of removing a uniform depth of tissue even when the tissue surface is curved.

15. An electrode according to claim 14, wherein the pair of depth stop members are mounted on the support so as to be capable of tilting in at least two directions.

16. A method of surgically removing a bladder tumour comprising the steps of i) introducing a resectoscope into a surgical site within the body of a patient, the resectoscope including a lumen, ii) introducing an elongate electrode assembly into the lumen, the elongate electrode assembly comprising a tissue treatment element, a support for the tissue treatment element, and one or more depth stop members disposed from the support and including a substantially planar surface, the one or more depth stop members being mounted on the support so as to be capable of tilting in at least one direction, iii) connecting the tissue treatment element to a source of electrosurgical energy, and iv) moving the electrode assembly in a curved motion over the surface of the bladder with the one or more depth stop members tilting to follow the curved surface of the bladder so as to establish a predetermined distance between the planar surface and the tissue treatment element, such that a substantially even depth of tissue is removed by the tissue treatment element along the curved motion of movement of the electrode assembly.