High-frequency treatment tool

Provided is a high-frequency treatment tool including: a sheath; an electrode member being advancable and retractable in the sheath; a distal end member disposed at a distal end of the sheath, wherein the electrode member includes a columnar portion; an electrode distal end portion provided at a distal end of the columnar portion and radially extending in an outward direction; and a stopper portion disposed at a proximal end side of the columnar portion, the stopper portion having the shape of a solid of revolution about a center axis of the electrode member, the distal end member has a tapered inner surface narrowing toward the distal end, a recessed portion is formed in a portion of the stopper portion, the electrode distal end portion has a small-diameter portion recessed in a radial direction, and the channel and the small-diameter portion are located at the same position in the circumferential direction.

TECHNICAL FIELD

The present invention relates to a high-frequency treatment tool.

BACKGROUND ART

A high-frequency treatment tool that treats body tissue, such as mucosae, by applying high-frequency current to the body tissue is known (for example, refer to PTL 1).

This high-frequency treatment tool has a structure in which a bar electrode unit is inserted into a through hole of an electrically insulating cap member provided at a distal end of a sheath such that the bar electrode unit can be advanced or retracted in the axis direction and a liquid, which has been sent through the sheath, can be released forward through a liquid feed opening of the cap member.

A radially spreading distal end portion is provided at a distal end of the bar electrode unit. Thus, by forming at least part of the liquid feed opening to be exposed on the outer side of the distal end portion in a front view of the cap member, the liquid to be released from the liquid feed opening is prevented from becoming blocked by the back side of the distal end portion of the bar electrode unit. According to the high-frequency treatment tool described in PTL 1, the liquid feed opening has a non-circular structure constituted by a small-diameter portion that is adjacent to and supports the bar electrode unit and a large diameter portion exposed on the outer side of the distal end portion.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

An aspect of the present invention provides a high-frequency treatment tool that includes an elongated cylindrical sheath to be inserted into a body; a straight bar-shaped electrode member to which high-frequency current is to be supplied, the electrode member being disposed so as to be advancable and retractable in the sheath in a longitudinal axis direction; a distal end member that is disposed at a distal end side of the sheath and that has a through hole through which the electrode member is passed; and a liquid feeding unit that is connected to a proximal end of the sheath that is configured to release a liquid forward in the longitudinal axis direction of the sheath through a channel formed in the sheath and a gap between the electrode member and the through hole in communication with the channel. The electrode member includes a bar-shaped columnar portion; an electrode distal end portion being provided at a distal end of the columnar portion and radially extending in a radially outward direction; and a stopper portion disposed at a proximal end side of the columnar portion with respect to the distal end member, the stopper portion being fixed to the electrode distal end portion via the columnar portion and substantially having the shape of a solid of revolution centered on a center axis of the electrode member. The distal end member has a tapered inner surface that abuts against the stopper portion in the longitudinal axis direction when the electrode member is maximally moved forward from a distal end of the distal end member, the tapered inner surface narrowing toward the distal end. A recessed portion that constitutes a channel through which the liquid can be distributed in a state in which the tapered inner surface and the stopper portion abut against each other is formed in the stopper portion, the recessed portion being formed in a portion in a circumferential direction about the center axis. Distribution of the liquid is limited such that the liquid flows out toward a distal end side of the stopper portion only through the recessed portion as the entire circumference of the stopper portion except for the recessed portion abuts against the tapered inner surface. The electrode distal end portion has a small-diameter portion in at least part in a circumferential direction, the small-diameter portion being recessed in a radial direction of the electrode distal end portion. The channel constituted by the recessed portion and the small-diameter portion are located at the same position in the circumferential direction, and the small-diameter portion is located in front of the liquid flowing out from the recessed portion in the longitudinal axis direction so that the liquid is released in a straight line in the forward direction through the small-diameter portion even when the electrode member is rotated about the center axis.

DESCRIPTION OF EMBODIMENTS

A high-frequency treatment tool1according to an embodiment of the present invention will now be described with reference to the drawings.

The high-frequency treatment tool1according to this embodiment is, for example, a treatment tool whose distal end is guided into the body through a channel provided in an insertion unit of an endoscope. As illustrated inFIG. 1, the high-frequency treatment tool1is equipped with a flexible sheath2formed to have an elongated cylindrical shape that is insertable into a channel; an advancable and retractable electrode member3at a distal end of the sheath2; an operation unit4at a proximal end of the sheath2, the operation unit being configured to push and pull the electrode member3; and a liquid feeding unit5that causes a liquid to be released from the distal end of the sheath2via an inner cavity (channel)2aof the sheath2.

A plug-shaped distal end member6is fixed to the distal end of the sheath2so as to close the inner cavity2a. As illustrated inFIG. 2, the distal end member6has a through hole6apenetrating in the longitudinal axis direction. The through hole6aallows the electrode member3to pass therethrough and move therein. The through hole6ahas a circular cross section, and a tapered inner surface6bhaving the shape of an inner surface of a circular cone that narrows toward the distal end is provided on the proximal end of the through hole6a. The sheath2and the distal end member6are composed of an electrically insulating material.

The electrode member3is composed of a conductive material. The electrode member3includes a columnar portion3athat has a diameter sufficiently smaller than that of the through hole6aand has a circular cross section; a triangular flat plate-shaped electrode distal end portion3bthat is provided at the distal end of the columnar portion3aand radially extends in a radially outward direction; and a stopper portion7that is provided at the proximal end of the columnar portion3aand has a columnar shape having a cross-sectional shape larger in diameter than the columnar portion3aand being concentric with the columnar portion3a. The stopper portion7has a tapered surface7aat the distal end, the tapered surface7ahaving a shape complementary to the tapered inner surface6b.

Groove-shaped recessed portions9that are recessed in the radially inward direction and extend in the longitudinal axis direction are respectively provided in the tapered surface7aat three positions spaced from one another in the circumferential direction. As illustrated inFIG. 3, the recessed portions9lie at positions that respectively correspond to the centers of the sides of the triangular electrode distal end portion3bin the circumferential direction.

As illustrated inFIG. 4, the electrode distal end portion3bhas such a shape that the circumscribed circle A is larger than the through hole6a, and the inscribed circle B is smaller than the through hole6a. Preferably, the circumscribed circle A has a diameter of 1.2 and the through hole6ahas a diameter of 0.8. In this manner, when the electrode member3is maximally moved toward the proximal end with respect to the distal end member6, most of the electrode member3becomes housed inside the sheath2, and the rear surface of the electrode distal end portion3babuts a distal end surface6cof the distal end member6so that further retraction is restricted. Here, as illustrated inFIG. 4, the circular through hole6ais prevented from becoming fully closed by the electrode distal end portion3b, and protrudes in the radially outward direction from the electrode distal end portion3bso as to partially open so as to form an opening10.

As illustrated inFIG. 1, when the electrode distal end portion3bis maximally moved toward the distal end with respect to the distal end member6, the electrode member3protrudes forward from the distal end surface6cof the distal end member6, and the tapered surface7aof the stopper portion7abuts the tapered inner surface6bof the distal end member6so that further advancement is restricted. Here, the tapered surface7ahaving a shape complementary to the tapered inner surface6bmakes close contact with the tapered inner surface6bby surface contact, so that the electrode member3is firmly supported by the distal end member6. In addition, when the tapered surface7aconcentric with the columnar portion3aof the electrode member3is brought into close contact with the tapered inner surface6bconnected to the through hole6a, the center axis of the electrode member3becomes coincident with that of the through hole6a(in other words, centering is achieved).

The operation unit4includes a handle4bthat has a finger hole4aand is installed at the proximal end of the sheath2; a movable unit4cthat can move relative to the handle4bin the longitudinal axis direction of the sheath2; and a wire4dthat is disposed in the inner cavity2aof the sheath2and is composed of a conductive material that connects the movable unit4cand the electrode member3to each other. In the drawing, reference numeral4edenotes a finger hole formed in the movable unit4c.

When the movable unit4cis moved toward the distal end of the sheath2with respect to the handle4b, a pressing force is transmitted to the electrode member3via the wire4d, and the electrode member3advances with respect to the distal end member6. When the movable unit4cis moved toward the proximal end of the sheath2with respect to the handle4b, a pressing force is transmitted to the electrode member3via the wire4d, and the electrode member3is retracted to be withdrawn into the through hole6aof the distal end member6of the electrode member3.

A power supply (not illustrated in the drawing) is connected to the proximal end of the wire4dso that high-frequency current can be supplied to the electrode member3via the wire4d.

The handle4bhas a connecting port8in communication with the inner cavity2aof the sheath2.

The liquid feeding unit5is a syringe, a pump, or the like, connected to the connecting port8, and is configured to feed a liquid, such as saline, into the inner cavity2aof the sheath2by activation of the liquid feeding unit5.

The effects of the high-frequency treatment tool1of this embodiment configured as described above will now be described.

Endoscopic submucosal dissection is performed by using the high-frequency treatment tool1of this embodiment as follows. The operation unit4is operated so that, as illustrated inFIG. 4, the sheath2is guided into the body from the distal end of the sheath2through a channel in the insertion unit of an endoscope while the electrode member3is being maximally retracted, and then the distal end of the sheath2is allowed to protrude from the distal end of the insertion unit of the endoscope.

As a result, the distal end portion of the sheath2enters the view of the endoscope, and the operator performs treatment by checking the image on a monitor screen acquired by the endoscope. When the electrode member3is maximally retracted, only the electrode distal end portion3bof the electrode member3is exposed at the distal end surface6cof the distal end member6. Thus, even when high-frequency current is applied to the electrode member3under this condition, tissues are prevented from becoming deeply incised, and what is known as marking, i.e., cauterizing only the tissue surfaces, can be performed.

In other words, the operator presses the distal end surface6cof the distal end member6against portions that surround what appears to be a lesion to be excised in an endoscopic image displayed on a monitor screen, and electrifies the electrode member3so as to form a mark that surrounds the lesion to be excised and that serves as a guide for the subsequent treatment.

Subsequently, the operation unit4is operated so that, as illustrated inFIG. 3, the electrode member3is allowed to protrude from the distal end surface6cof the distal end member6, and high-frequency current is applied to incise the tissue and insert the distal end member6to a portion near the submucosal layer under the lesion. Next, the operation unit4is operated so as to create a state in which the electrode member3is maximally retracted, and the liquid feeding unit5is activated so as to release a liquid, such as saline, from the opening10in the distal end surface6c. As a result, the liquid is locally injected to the submucosal layer, and the lesion becomes afloat.

Under this condition, the sheath2is withdrawn from the submucosal layer, the operation unit4is again operated so that the electrode member3is made to protrude, and then the tissue around the lesion is incised by using, as a guide, the mark formed by the marking.

In the event of bleeding during incising, the liquid feeding unit5is activated so that a liquid, such as saline, is released from the opening10in the distal end surface6cof the distal end member6so as perform washing.

In such a case, the electrode member3is maximally advanced with respect to the sheath2, and the electrode distal end portion3bis made to protrude from the distal end surface6cof the distal end member6. As a result, the tapered surface7aof the stopper portion7makes close contact with the tapered inner surface6bof the distal end member6, and the electrode member3becomes fixed while being centered with respect to the through hole6a. Even in a state in which the tapered surface7aand the tapered inner surface6bare brought into close contact with each other, the respective spaces in front of and behind the stopper portion7remain in communication with each other due to the recessed portions9formed in the tapered surface7a.

Under this condition, when the liquid feeding unit5is activated, the liquid sent through the inner cavity2aof the sheath2passes through gaps C formed by the recessed portions9and between the tapered surface7aand the tapered inner surface6b, then passes through a cylindrical gap C between the columnar portion3aand the through hole6a, and is released to the anterior of the distal end member6.

The flow of the fluid flowing in the gap C between the columnar portion3aand the through hole6agenerates the force that causes the columnar portion3ato vibrate. However, since the tapered surface7ais in close contact with the tapered inner surface6band thus the electrode member3is firmly supported by the distal end member6, vibration of the columnar portion3ais suppressed, and the fluid can be stably released to the anterior of the distal end member6.

In other words, even when the inner diameter of the through hole6ais sufficiently large relative to the outer diameter of the columnar portion3a, the columnar portion3ais supported as a result of the close contact between the tapered surface7aand the tapered inner surface6bto prevent vibration of the columnar portion3a. Thus, there is an advantage in that it becomes possible to secure a sufficiently large flow area between the through hole6aand the columnar portion3a, and the fluid can be smoothly released at a high flow rate. Thus, blood can be more assuredly and rapidly washed away.

Furthermore, since there is no need to support the columnar portion3aby the through hole6ato prevent vibration in the radial direction, there is an advantage in that the through hole6aitself can be formed to have a simple circular cross section with an inner diameter sufficiently larger than the outer diameter of the columnar portion3a, which makes the production thereof easier.

During incising of the tissue surrounding the lesion, the liquid locally injected to the submucosal layer may become absorbed by other regions, and the lesion may start to sink down. In that case, the distal end member6is again pressed against the submucosal layer to locally inject the liquid. In this case also, since the liquid is released while having the electrode member3maximally retracted, the electrode member3does not penetrate the tissue beyond what is necessary.

In this case also, according to the high-frequency treatment tool1of this embodiment, when the electrode member3is maximally retracted so that the electrode distal end portion3babuts the distal end surface6cof the distal end member6, the large through hole6aprotrudes from the electrode distal end portion3bin the radially outward direction and remains open. Thus, the liquid can be released from this opening10. In particular, since the recessed portions9formed in the tapered surface7aand portions of the electrode distal end portion3bthat have small protruding amounts in the radial direction (small-diameter portions) have matching phases, the fluid that flowed through the recessed portions9is not completely blocked by the electrode distal end portion3band can be smoothly released forward.

In this embodiment, the electrode distal end portion3bhas a triangular flat plate shape. However, the shape is not limited to this, and any electrode distal end portion3bthat has radially protruding portions and radially recessed portions alternately arranged in the circumferential direction, such as a polygonal shape having four or more sizes, a star shape, or an elliptical shape, may be employed. Any shape may be employed as long as the circumscribed circle A of these shapes is larger than the through hole6aand the inscribed circle B is smaller than the through hole6a. In such cases, it is preferable to form groove-shaped recessed portions9at positions that correspond to the radially recessed portions (small-diameter portions).

In this embodiment, the stopper portion7that has the tapered surface7athat surface-contacts the tapered inner surface6bis described as an example; alternatively, as illustrated inFIGS. 5 and 6, a stopper portion that has the shape of a solid of revolution, such as a columnar edge7bor a spherical surface7c, and makes linear contact with the tapered inner surface6bin an annular manner may be employed instead of the tapered surface7a.

Moreover, although the groove-shaped recessed portions9that enable distribution of a fluid between the tapered inner surface6band the tapered surface7ain close contact with each other are formed in the tapered surface7a, the recessed portions9may be formed in the tapered inner surface6b, as illustrated inFIG. 7, instead.

In this embodiment, the recessed portions9of the stopper portion7have a groove shape, but this is not limiting. As illustrated inFIGS. 8 and 9, a D cut portion11that extends along the longitudinal axis direction of the sheath2and grooves12that flank the D cut portion11about the longitudinal axis of the sheath2and are equally spaced from each other may be employed instead of the recessed portions9. Reference numeral13denotes a hole formed to enable brazing the wire4dto the stopper portion7, and reference numeral14denotes a hole formed to enable brazing the columnar portion3ato the stopper portion7.

In this case, as illustrated inFIG. 10, a gap E is formed between the tapered surface7aand the tapered inner surface6aby the D cut portion11, and a gap F is formed between the tapered surface7aand the tapered inner surface6aby the grooves12. In this manner, the gap E formed by the D cut portion11wider than the grooves12allows a higher flow rate per unit time than the gap F formed by the groove12. Thus, the total flow rate per unit time can be increased by using the entire circumference of the stopper portion7.

As a result, the above-described embodiment leads to the following aspect.

An aspect of the present invention provides a high-frequency treatment tool that includes an elongated cylindrical sheath to be inserted into a body; a straight bar-shaped electrode member to which high-frequency current is to be supplied, the electrode member being disposed so as to be advancable and retractable in the sheath in a longitudinal axis direction; a distal end member that is disposed at a distal end side of the sheath and that has a through hole through which the electrode member is passed; and a liquid feeding unit that is connected to a proximal end of the sheath that is configured to release a liquid forward in the longitudinal axis direction of the sheath through a channel formed in the sheath and a gap between the electrode member and the through hole in communication with the channel. The electrode member includes a bar-shaped columnar portion; an electrode distal end portion being provided at a distal end of the columnar portion and radially extending in a radially outward direction; and a stopper portion disposed at a proximal end side of the columnar portion with respect to the distal end member, the stopper portion being fixed to the electrode distal end portion via the columnar portion and substantially having the shape of a solid of revolution centered on a center axis of the electrode member. The distal end member has a tapered inner surface that abuts against the stopper portion in the longitudinal axis direction when the electrode member is maximally moved forward from a distal end of the distal end member, the tapered inner surface narrowing toward the distal end. A recessed portion that constitutes a channel through which the liquid can be distributed in a state in which the tapered inner surface and the stopper portion abut against each other is formed in the stopper portion, the recessed portion being formed in a portion in a circumferential direction about the center axis. Distribution of the liquid is limited such that the liquid flows out toward a distal end side of the stopper portion only through the recessed portion as the entire circumference of the stopper portion except for the recessed portion abuts against the tapered inner surface. The electrode distal end portion has a small-diameter portion in at least part in a circumferential direction, the small-diameter portion being recessed in a radial direction of the electrode distal end portion. The channel constituted by the recessed portion and the small-diameter portion are located at the same position in the circumferential direction, and the small-diameter portion is located in front of the liquid flowing out from the recessed portion in the longitudinal axis direction so that the liquid is released in a straight line in the forward direction through the small-diameter portion even when the electrode member is rotated about the center axis.

Treatment, such as incision of body tissue, is performed by increasing the protruding amount of the electrode distal end portion by advancing the electrode member with respect to the sheath and then supplying high-frequency current to the electrode member. In performing incision or detachment of tissue, the radially extending electrode distal end portion is hooked to the surrounding tissue so that the treatment can be performed stably without slipping.

Under this condition, when the electrode member is advanced, the stopper portion disposed on the proximal end of the electrode member abuts the tapered inner surface of the distal end member disposed at the distal end of the sheath and allowing the electrode to pass through the through hole, and thus further advancement is restricted. Since the stopper portion is formed to substantially have the shape of a solid of revolution, when the stopper portion abuts the tapered inner surface, portions of the stopper portion at positions surrounding the electrode member abut against the tapered inner surface simultaneously so that the electrode member can remain centered with respect to the through hole.

During the course of this, the recessed portion formed in the tapered inner surface or the stopper portion forms a channel between the tapered inner surface and the stopper portion abutting against each other. When bleeding occurs in the site being treated, the liquid feeding unit is activated so that a liquid is released forward in the longitudinal axis direction of the sheath through the channel formed in the sheath and a gap between the electrode member and the through hole in the distal end member at the distal end of the sheath, and, as a result, the liquid can be released near the bleeding site so as to perform washing.

Moreover, the channel, which is formed by the recessed portion when the stopper portion and the tapered inner surface abut against each other, and the small-diameter portion of the electrode distal end portion are always maintained to be in phase with each other. Even when the electrode distal end portion is rotated about the longitudinal axis with respect to the through hole, the liquid released from the channel can always be released in a straight line in the forward direction through the small-diameter portion of the electrode distal end portion.

In this case also, the electrode member is firmly supported since the tapered inner surface and the stopper portion abut against each other at positions that surround the electrode member; thus, even when a liquid flows in the gap between the electrode member and the through hole, the electrode distal end portion is held so as not to vibrate.

In other words, according to this aspect, the electrode member is not supported by the through hole; alternatively, the tapered inner surface disposed in the distal end member and the stopper portion disposed in the electrode member contact each other so as to enable centering and firm support. Thus, a sufficiently large gap can be secured between the through hole and the electrode member. As a result, the liquid released forward via the gap can be released without being obstructed by the electrode distal end portion and without vibration of the electrode member.

In the aspect described above, the stopper portion may have a tapered surface that is brought into surface-contact with the tapered inner surface.

In this manner, due to the surface contact between the stopper portion and the tapered inner surface, the electrode member centered in the through hole can be more firmly supported by the distal end portion.

In the aspect described above, a distal end opening of the through hole may have a circular projection shape in the longitudinal axis direction, and a projection shape of the electrode distal end portion in the longitudinal axis direction may have a non-circular shape constituted by a circumscribed circle larger than a bore of the distal end opening and an inscribed circle smaller than the bore.

In this manner, when the electrode member is maximally retracted with respect to the sheath, a portion of the non-circular electrode distal end portion protruding in the radial direction abuts against the distal end surface of the distal end member with respect to the distal end opening of the circular through hole, and further retraction is restricted. In addition, the distal end opening of the circular through hole has portions protruding in the radial direction from the non-circular electrode distal end portion, and through these portions, the liquid released from the distal end opening is released in a straight line in the forward direction without being completely blocked by the electrode distal end portion.

In the aspect described above, the recessed portion may be formed in the stopper portion.

In this manner, the channel, which is formed by the recessed portion when the stopper portion and the tapered inner surface abut against each other, and the electrode distal end portion are always maintained in phase with each other. Even when the electrode distal end portion is rotated about the longitudinal axis with respect to the through hole, changes in the channel caused by the electrode distal end portion are prevented.

In the aspect described above, the small-diameter portion may include a plurality of small-diameter portions equally spaced from one another in a circumferential direction, and the recessed portions may be disposed at positions that correspond to the small-diameter portions.

In this manner, the flow of the liquid released in a straight line toward the anterior of the electrode distal end portion through the recessed portions and the small-diameter portions can be prevented from becoming uneven in the circumferential direction of the electrode distal end portion and can be released forward in a more straight manner.

In the aspect described above, the distal end member may be an electrically insulating member protruding from a distal end of the sheath.

In the aspect described above, the recessed portion has the shape of a groove that extends in the longitudinal axis direction.

The advantageous effects of the present invention are that smooth liquid feeding and stable electrode support can both be achieved, and production is facilitated.

REFERENCE SIGNS LIST