Abstract:
A high frequency operation device comprises: a flexible sheath of an electric insulation member that is insertable into an operation device insertion channel in an endoscope; a high frequency knife mounted on the flexible sheath; and an operation section connected to the flexible sheath to project the high frequency knife from a leading end of the flexible sheath, wherein the high frequency knife comprises first and second electrode members incorporated in a telescopic manner; wherein the operation section comprises: first and second drive members respectively that moves the first and second electrode members; and a connecting member that links together the first and second drive members and removes linkage between the first and second drive members, and wherein the high frequency operation device comprises: a first stage regulation portion that regulates a projecting length of the second electrode member, formed at the flexible sheath; and a second stage regulation portion that regulates a projecting length of the first electrode member from a leading end of the second electrode member, formed at the second electrode member.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a high frequency operation device which can be inserted into an operation device insertion channel formed in an endoscope to perform operations such as an operation to dissect a lesion mucous membrane and an operation to separate the dissected lesion mucous membrane. 
         [0003]    2. Description of the Related Art 
         [0004]    When, in an endoscopic examination, a lesion portion such as a tumor is found in the mucous membrane portion of an esophagus, a stomach, a duodenum, a large intestine or the like within inner wall of the body cavity, there is performed an operation to excise or remove the lesion mucous membrane portion using a high frequency operation device. In the operation to remove the lesion mucous membrane portion, in the related art, there has been widely used Endoscopic Mucosal Resection (EMR) method using a high frequency snare. However, this EMR method is not capable of removing a large lesion portion at a time but needs several times of removing operations, and also there is a fear that the lesion portion can be left in part. To solve this problem, recently, there has been employed Endoscopic Submucosal Dissection (ESD) method. According to this ESD method, an operation is executed in two stages: that is, firstly, the periphery of the lesion portion of the mucous membrane is cut open and, next, the lesion mucous membrane including a portion of a mucous membrane lower layer is separated from a muscular layer. According to the ESD method, there is provided an advantage that, even for a large lesion portion, the lesion mucous membrane portion can be removed completely by a single operation with no leftover. 
         [0005]    A high frequency operation device used in the ESD method is structured such that a high frequency knife can be projected from and retreated into the leading end of a flexible sheath having an electric insulative property. Also, to the base end portion of the flexible sheath, there is connected an operation section; and, the flexible sheath can be inserted into an operation device insertion channel formed in an endoscope. As a high frequency operation device of this type, for example, there is known a high frequency operation device which is disclosed in JP-A-2004-313537. This known high frequency operation device is structured such that an operation wire is inserted into the interior portion of a flexible sheath, a knife portion serving as a high frequency operation section is connected to the leading end of the operation wire, and an operation section is connected to the base end portion of the flexible sheath. The operation section includes a slider connected to the main body shaft thereof, and the base end portion of the operation wire is connected to the slider; and, by pushing and pulling the slider along the main body shaft, the knife portion connected to the operation wire can be projected from and retreated into the leading end of the flexible sheath. 
         [0006]    To form the knife portion, a plate-shaped electrode having a disk plate shape or a triangular plate shape is connected to the leading end of a stick-shaped electrode. And, there is also disclosed a knife portion in which a hook knife is formed by bending the leading end portion of a stick-shaped electrode. And, according to the disclosure of JP-A-2004-313537, by using an operation device including a knife portion with a plate-shaped electrode mounted thereon, it is possible to perform an operation to dissect a lesion mucous membrane and an operation to separate the thus dissected lesion mucous membrane. JP-A-2004-313537 further teaches that, when there is produced a bleeding portion while the operation is under execution, by pressing the plate-shaped electrode against the bleeding portion, the bleeding can be stopped. 
         [0007]    When incising a lesion mucous membrane, it is necessary not to invade a muscular layer which is situated downwardly of a mucous membrane lower layer. For example, when a high frequency knife is contacted with the muscular layer in a state where a high frequency current flows in the high frequency knife, there is a possibility that there can be opened up a hole in the muscular layer and, as a result of this, there can occur excessive bleeding. When incising the mucous membrane, in order to separate the mucous membrane from the muscular layer, generally, a swelling solution such as a normal saline solution or a distention solution composed of hyaluronic acid is locally injected into the mucous membrane lower layer to swell the mucous membrane to be dissected. However, even when the mucous membrane is swollen by such local injection, there is a possibility that invasion of the high frequency knife into the muscular layer cannot be prevented. Since the high frequency knife is structured such that it can be projected from and retreated into the leading end of the flexible sheath, when the projecting length of the high frequency knife from the flexible sheath is regulated, the high frequency knife can be prevented from touching the muscular layer, thereby being able to secure the safety of the incising operation. 
         [0008]    Here, referring to the regulation of the projecting length of the high frequency knife from the flexible sheath, while the maximum projection length is set equal to or longer than the thickness of the mucous membrane and equal to or smaller than the total thickness of the mucous membrane and mucous membrane lower layer, the high frequency knife is projected from the leading end of the flexible sheath and is pressed against the mucous membrane to dissect the lesion mucous membrane. In this case, the high frequency knife can be held for the leading end thereof not to reach the muscular layer. 
         [0009]    When separating and removing the lesion mucous membrane, after the mucous membrane is dissected, the thus dissected mucous membrane must be separated. This mucous membrane separation operation is carried out by sliding the high frequency knife into the mucous membrane lower layer and cutting fibrous substances which constitute the mucous membrane lower layer. In this operation, while keeping the high frequency knife substantially parallel to the mucous membrane, it is operated such that it is swung right and left. Therefore, to carry out this mucous membrane separation operation efficiently, preferably, the projecting length of the high frequency knife from the flexible sheath may be set long to some extent. 
         [0010]    In short, when the lesion mucous membrane is dissected and separated according to the ESD method, preferably, for the mucous membrane dissection operation, the projecting length of the high frequency knife from the flexible sheath may be limited and, for the mucous membrane separation operation, the projecting length of the high frequency knife may be set long. However, the high frequency operation device disclosed in JP-A-2004-313537 does not include a mechanism which can change the projecting length of the high frequency knife from the flexible sheath according to the kinds of the operations. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention aims at solving the above problems found in the related-art high frequency operation device. Thus, it is an object of the invention to provide a high frequency operation device which, when carrying out the two kinds of operations, that is, the incising operation and separating operation, can adjust the projecting length of a high frequency operation section from the flexible sheath to the optimum length according to the respective operations. 
         [0012]    In attaining the above object, according to the invention, there is provided a high frequency operation device comprising: a flexible sheath of an electric insulation member, the flexible sheath being insertable into an operation device insertion channel in an endoscope; a high frequency knife mounted on the flexible sheath; and an operation section connected to the flexible sheath to project the high frequency knife from a leading end of the flexible sheath, wherein the high frequency knife comprises first and second electrode members incorporated in a telescopic manner; wherein the operation section comprises: first and second drive members respectively that moves the first and second electrode members; and a connecting member that links together the first and second drive members and removes linkage between the first and second drive members, and wherein the high frequency operation device comprises: a first stage regulation portion that regulates a projecting length of the second electrode member, the first stage regulation portion being formed at the flexible sheath; and a second stage regulation portion that regulates a projecting length of the first electrode member from a leading end of the second electrode member, the second stage regulation portion being formed at the second electrode member. 
         [0013]    When the present high frequency operation device is used to perform the operation to dissect the lesion mucous membrane portion and the operation to separate the dissected lesion mucous membrane portion, as regards the operation to dissect the lesion mucous membrane portion using the high frequency knife disposed on the leading end portion of the flexible sheath, the dissection operation is an operation to cut into the body tissues using the high frequency knife. Therefore, from the viewpoint of the operation efficiency of the dissection operation, preferably, the high frequency knife may be structured as a stick-shaped electrode. And, it is also possible to use other knives having proper structures such as a hook knife which can be made by bending the leading end portion of a stick-shaped electrode or an IT knife including an electric insulation member mounted on the leading end portion thereof. Also, the separation operation is an operation to swing the high frequency knife right and left. Therefore, in this operation, preferably, there may be used a straight-shaped knife or a stick-shaped electrode with the leading end portion thereof curved. 
         [0014]    In order to cut open the mucous membrane, the projecting length of the high frequency knife from the leading end of the flexible sheath must be equal to or larger than the thickness of the mucous membrane layer. And, in order to prevent the leading end of the high frequency knife from touching the muscular layer, the projecting length must be equal to or smaller than the total thickness of the mucous membrane layer and mucous membrane lower layer. This is a first stage stroke and thus the first and second electrode members, which constitute the high frequency knife formed into a telescopic manner, can be projected from the leading end of the flexible sheath by an amount corresponding to the thus set projecting length while they are held at the reduced state thereof. Also, when separating the mucous membrane layer, the high frequency knife is directed substantially parallel to the mucous membrane layer and muscular layer; and, therefore, a second stage stroke is added to the first stage stroke, whereby the high frequency knife is projected further longer. What is projected at the then time is the second electrode member, whereas the first electrode member is held at the first stage stroke end position. Thanks to this, the high frequency knife can be projected from the leading end of the flexible sheath by an amount proper for efficient execution of the mucous membrane separation operation. 
         [0015]    The first stage stroke is used to link together the first and second drive members, while the second stage stroke is used to project the first electrode member further from the first stage stroke end position. The linking member for linking together the first and second drive members and for removing such linkage, preferably, may be made of, for example, a set screw or a pin, or may be formed as a snap action mechanism. That is, it may preferably be structured such that it can link together the first and second drive members and can remove such linkage without using a tool. 
         [0016]    The first drive member and first electrode member can be connected together using a first transmission member made of a flexible wire or the like. On the other hand, the second drive member and second electrode member can be connected together using a second transmission member. The second transmission member can be made of a wire which is arranged parallel to the first transmission member; however, preferably, the first transmission member may be made of a wire, the second transmission member may be made of a tube or a coil, and the wire may be inserted into the tube or coil. And, at least one of the first and second electrode members is or both of them are made of a conductive member, and one of them is or both of them are electrically connected to a high frequency power supply. Since the first and second electrode members are connected together in a telescopic manner and are thus contacted with each other, one of the first and second transmission members may be connected to the high frequency power supply, or the transmission members may be used only to transmit a drive force and the power may be supplied through a cable which is provided separately. 
         [0017]    Although the first stage and second stage regulation portions may be disposed on the operation section side, in order to be able to move by all means the high frequency knife up to a given position regardless of the state of the flexible state, preferably, the projecting amount at least in the first stage may be regulated on the leading end side of the flexible sheath. Also, preferably, the projecting amount between the telescopically connected first and second electrode members may be also be regulated on the leading end side of the flexible sheath. The first stage regulation portion can be composed of a stopper ring which is mounted on the leading end of the flexible sheath; and, the second stage regulation portion can be structured such that the first electrode member is contacted with the base end portion of the second electrode member. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a structure view of the whole of a high frequency operation device according to an embodiment of the invention; 
           [0019]      FIG. 2  is a section view of the leading end portion of the high frequency operation device shown in  FIG. 1 ; 
           [0020]      FIG. 3  is a front view of the operation section side of the high frequency operation device; 
           [0021]      FIG. 4  is a section view of the main body shaft of the operation section of the high frequency operation device in the slit direction thereof; 
           [0022]      FIG. 5  is an enlarged section view taken along the portion X-X shown in  FIG. 4 ; 
           [0023]      FIG. 6  is an external view of a high frequency operation device according to an embodiment of the invention, showing a state where it is guided out from an operation device insertion channel formed in an endoscope; 
           [0024]      FIG. 7  is a section view of the tissues of the human body, showing a state where a dissection operation is being performed using the high frequency operation device; and 
           [0025]      FIG. 8  is a section view of the tissues, showing a state where a mucous membrane separation operation is being performed. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Now, description will be given below of a preferred embodiment according to the invention with reference to the accompanying drawings. In the present embodiment, description will be given of a high frequency operation device which is used to dissect and separate a lesion mucous membrane. By the way, it goes without saying that the high frequency operation device of the invention can also be used to carry out other kinds of operations.  FIG. 1  shows the whole structure of the present high frequency operation device. 
         [0027]    In  FIG. 1 , reference numeral  1  designates a high frequency operation device. The present high frequency operation device  1  includes a flexible sheath  2  which is made of a long insulation tube, while the base end portion of the flexible sheath  2  is connected to an operation section  3 . The operation section  3  is composed of a main body shaft  4  and a slider  5  which is fitted with the main body shaft  4 , can be slided in the axial direction of the main body shaft  4  and can be operated with the fingers of an operator. Reference numeral  6  stands for a high frequency power supply  6 ; and, to the high frequency power supply  6 , there is removably connected a cable  7 , while the cable  7  can be removably connected to a terminal part  8  which is mounted on the slider  5 . 
         [0028]    On the leading end portion of the flexible sheath  2 , as shown in  FIG. 2 , there is mounted a high frequency knife  10 . The high frequency knife  10  is composed of a stick-shaped electrode member  11  having a semi-spherical-shaped leading end portion, and a cylindrical-shaped second electrode member  12  which is fitted with the first electrode member  11 . The first electrode member  11  is structured such that the base end side thereof is formed as a large diameter portion  11   a  and the leading end side thereof is formed as a small diameter portion  11   b . Also, the cylindrical-shaped second electrode member  12  is fitted with the first electrode member  11  in such a manner that it can be slided, while the inner surface side thereof has a stepped structure. In other words, the second electrode member  12  is structured such that the base end side thereof is formed as a small thickness portion  12   a  which can be slided together with the large diameter portion  11   a  of the first electrode member  11 , while the leading end side thereof is formed as a large thickness portion  12   b  which can be slided with respect to the small diameter portion  11   b . And, these first and second electrode members  11  and  12  can be switched in shape substantially between a reduced state, in which only the semi-spherical surface portion of the first electrode member  11  is projected from the second electrode member  12 , and an extended state in which the first electrode member  11  is greatly projected from the second electrode member  12 . 
         [0029]    Into the inner surface of the leading end portion of the flexible sheath  2 , there is inserted a stopper ring  13  made of a pipe-shaped member which is formed of heat-resistant hard electrical insulation material such as ceramic, while the stopper ring  13  is fixed to the above-mentioned inner surface by bonding or the like. The inside diameter of the stopper ring  13  is set slightly smaller than the outside diameter of the second electrode member  12  and, therefore, the second electrode member  12  is slidably inserted into the stopper ring  13 . And, the most base-side end portion of the second electrode member  12  is formed as an enlarged diameter portion  12   c ; and, the enlarged diameter portion  12   c  has a dimension larger than the inside diameter of the stopper ring  13 . 
         [0030]    According to the above structure, while no operation is being carried out, the high frequency knife  10 , as shown in  FIG. 2A , is held at its retreat position where the high frequency knife  10  is stored within the flexible sheath  2 . As shown in  FIG. 2B , when the first and second electrode members  11  and  12  are moved from this state to project integrally from the flexible sheath  2  while they are held at the reduced state, the enlarged diameter portion  12   c  of the second electrode member  12  is contacted with the base end face of the stopper ring  13  and the high frequency knife  10  is thereby turned into a dissection operation position. In this state, the second electrode member  12  provides the most projecting position thereof and, therefore, the enlarged diameter portion  12   c  of the second electrode member  12  and the end face of the stopper ring  13  cooperate together in constituting a first state regulation portion. Here, in this reduced state, there intervenes a given clearance between the large thickness portion  12   b  of the second electrode member  12  and the large diameter portion  11   a  of the first electrode member  11 . 
         [0031]    The first electrode member  11 , as shown in  FIG. 2C , can be moved until the second electrode member  12  is projected most and the large diameter portion  11   a  is contacted with a stepped portion provided by the large thickness portion  12   b  of the second electrode member  12 , whereby the first electrode member  11  provides the extended state where it is projected most from the flexible sheath  2 . That is, the state, where the first electrode member  11  is projected most from the second electrode member  12 , provides the separation operation position of the high frequency knife  10 . At the then time, the stepped portion provided by the large thickness portion  12   b  of the second electrode member  12  is contacted with the stepped portion provided by the large diameter portion  11   a  formed in the first electrode member  11 , thereby providing a second stage regulation portion. 
         [0032]    In this manner, the high frequency knife  10 , which is composed of the first and second electrode members  11  and  12 , is structured such that it can be projected in the two stages. And, in order to operate the high frequency knife  10  so as to project in the two stages, the operation section  3  is structured as shown in  FIGS. 3 to 5 . That is, the slider  5 , which is slidably mounted on the main body shaft  4 , comprises a first drive part  20 , a second drive part  21 , and a linking member  22  which connects together the first and second drive parts  21  and  22  in such a manner that they can link to each other and also their mutual linkage can be removed. And, as shown in  FIGS. 4 and 5 , in the main body shaft  4 , there is formed a slit  23  which extends substantially over the entire length of the main body shaft  4 ; and, not only a wire  24 , which functions as a first transmission member, inserted into the flexible sheath  2  and connected to the first electrode member  11  but also a coil  25  functioning as a second transmission member which is connected to the second electrode member  12  and through which the wire  24  is inserted, are extended into the slit  23  through a passage portion  4   a  opened up in the main body shaft  4 . 
         [0033]    Within the slit  23 , there are further disposed a first sliding piece  26  connected to the first drive part  20  and a second sliding piece  27  connected to the second drive part  21 . To the second sliding piece  27 , there is connected the coil  25 , while the wire  24  is guided out from the end portion of the coil  25  and the end portion of the wire  24  is connected to the first sliding piece  26 . And, the terminal part  8 , in the slider  5 , is mounted on the second drive part  21  thereof, while the terminal part  8  is electrically connected to the coil  25 . Therefore, the coil  25  is made of a coil-shaped metal wire rod which can conduct electricity. Also, at least the second sliding piece  27  is also made of a conductive member. And, to the terminal part  8 , there are electrically connected not only the second electrode member  12  through the coil  25  but also the first electrode member  11  which is contacted with the second electrode member  12  in such a manner it is slidable with respect to the second electrode member  12 . 
         [0034]    Here, the first drive part  20  is connected to the second drive part  21  through the linking member  22  and, to serve this purpose, the connecting member  22  is made of a long plate-shaped member having an elongated bore  22   a , while the leading end portion of the connecting member  22  is connected continuously with the second drive part  21 . And, into the elongated bore  22   a , there is inserted a connecting screw  28 , while the connecting screw  28  is threadedly inserted into the first drive part  20 . Therefore, when the connecting screw  28  is tightened, the first and second drive parts  20  and  21  are connected together; and, when the connecting screw  28  is loosened, the first drive part  20  can be slided alone along the main body shaft  4 . Here, the linking member  22  having the elongated bore  22   a  is disposed on each side across the main body shaft  4 . Specifically, the connecting screw  28  is mounted on one side linking member  22 ; and, into the elongated bore  22   a  of the other side linking member  22 , there is engaged a projection  20   a  which is provided on the first drive part  20 . Further, into the second drive part  21 , there is threadedly inserted a set screw  29 . Therefore, when the set screw  29  is tightened, the leading end portion thereof is pressed against the main body shaft  4 , with the result that the second drive part  21  can be fixedly held on the main body shaft  4 . 
         [0035]    The high frequency operation device  1  having the above structure, as shown in  FIG. 6 , is inserted into the body cavity of the human body through an operation device insertion channel C formed in an endoscope insertion part S including an observation portion W and, when a lesion mucous membrane is found existing on the inner wall of the body cavity such as esophagus, stomach, duodenum, and large intestine, the high frequency operation device  1  is used to perform an operation to separate and remove such lesion mucous membrane portion. Now, description will be given below of an example of the operation to excise the lesion mucous membrane. This excise operation is carried out, for example, when, as the result of examination using an endoscope S, the existence of a lesion portion in the mucous membrane is confirmed. Also, this operation is carried out in two stages, that is, in one stage where the mucous membrane is dissected and in the other state where it is separated. 
         [0036]    Firstly, to dissect the mucous membrane, the operation section  3  of the high frequency operation device  1  is operated, that is, the first and second drive parts  20  and  21  of the slider  5  are turned by the linking member  22  into such a state that they can be operated in linking with each other, and they are moved from the retreat position up to the dissection operation position. In other words, not only the first and second drive parts  20  and  21  are connected together through the linking member  22  by operating the connecting screw  28 , but also the set screw  29  is loosened. As a result of this, the whole of the slider  5  can be slided along the main body shaft  4 . 
         [0037]    By operating the slider  5 , as shown in  FIG. 2B , the first and second electrode members  11  and  12 , which constitute the high frequency knife  10 , are projected a given length from the leading end of the flexible sheath  2  in the reduced state where only the semi-spherical surface portion of the first electrode member  11  is projected from the second electrode member  12 . The projecting length of the high frequency knife  10  from the flexible sheath  2  at the then time is set larger than the thickness of a mucous membrane layer LU and smaller than the total thickness of the mucous membrane LU and mucous membrane lower layer LM. In this state, when power is supplied from a high frequency power supply  6 , a high frequency current is allowed to flow in the high frequency knife  10 , so that the mucous membrane layer LU can be cut open. 
         [0038]    On the leading end portion of the flexible sheath  2 , there is mounted the stopper ring  13 , while the stopper ring  13  is disposed at the same position as the leading end face of the flexible sheath  2 . Therefore, the contact area of the leading end of the flexible sheath  2  with the mucous membrane layer LU is large and, when the leading end face of the flexible sheath  2  is pressed lightly against the mucous membrane layer LU, the leading end face can be kept from pushing the mucous membrane layer LU. Also, the first stage regulation portion for regulating the projecting length of the high frequency knife  10  at the dissection operation position is interposed between the enlarged diameter portion  12   c  of the second electrode member  12  and the end face of the stopper ring  13 , that is, it is disposed in the leading end portion of the flexible sheath  2 . Therefore, the projecting length from the leading end of the flexible sheath  2  can be adjusted very accurately. By operating the high frequency knife  10  in this manner, not only the mucous membrane layer LU can be dissected positively but also the high frequency knife  10  can be prevented from reaching a position where it could possibly touch a muscular layer LB existing below of the mucous membrane lower layer LM, and thus the high frequency knife  10  can be prevented from injuring the muscular layer LB. And, when the mucous membrane lower layer LM is swollen by previously injecting a hyaluronic acid solution, a normal saline solution or the like into the mucous membrane lower layer LM locally, a safer operation can be realized. 
         [0039]    The dissection operation is performed over the whole periphery of the lesion portion and, as a result of this, the mucous membrane layer LU existing in the periphery of the outer peripheral portion of the lesion mucous membrane is cut open and thus the mucous membrane lower layer LM is exposed. However, simply by cutting open the whole periphery of a lesion mucous membrane area D, the mucous membrane LU cannot be removed. That is, since the mucous membrane layer LU and muscular layer LB are connected together by the mucous membrane lower layer LM formed of fibers, it is necessary to cut the fibers and separate the mucous membrane layer LU from the muscular layer LB. 
         [0040]    In this separation operation, while applying a high frequency current to the high frequency knife  10  from the high frequency power supply  6 , the flexible sheath  2  is moved horizontally or is swung around to burn the mucous membrane lower layer LM due to the action of the high frequency current, thereby cutting the fibers. That is, the high frequency knife  10  is extended in a direction substantially parallel to the mucous membrane layer LU and muscular layer LB. Therefore, even when the high frequency knife  10  is projected fairly greatly from the leading end of the flexible sheath  2 , there is no fear that the high frequency knife  10  can invade and injure the muscular layer LB; or rather, in order to perform the mucous membrane separation operation with efficiency, it is necessary to make longer the projecting length of the high frequency knife  10  from the flexible sheath  2 . 
         [0041]    As can be seen from the above description, in a state where the second drive part  21  constituting the slider  5  is set at the dissection operation position, by tightening the set screw  29 , the second drive part  21  is fixed to the main body shaft  4 . Also, by loosening the connecting screw  28 , the linkage between the first and second drive parts  20  and  21  through the linking member  22  is removed. In this state, when the first drive part  20  is slided along the main body shaft  4 , not only the second electrode member  12  is kept in a state where it is projected from the leading end of the flexible sheath  2 , but also the first electrode member  11  is projected from the second electrode member  12  which shows a cylindrical shape. This provides a separation operation position in which the high frequency knife  10  is held in its extended state and is contacted with the second stage regulation portion composed of the step provided by the large thickness portion  12   b  of the second electrode member  12  and the step of the large diameter portion  11   a  of the first electrode member  11 . 
         [0042]    In this state, by swinging the high frequency knife  10 , the mucous membrane lower layer LM can be separated. Here, since the second and first electrode members  12  and  11  are projected greatly from the leading end of the flexible sheath  2  and the high frequency current is applied to these two electrode members  12  and  11 , the high frequency knife  10  can perform the mucous membrane separation operation with efficiency. And, the operation to swing the high frequency knife  10  can be carried out easily, for example, by curving the leading end portion of the endoscope insertion portion S. Thanks to this, the mucous membrane can be separated quickly and efficiently. 
         [0043]    According to the invention, while the high frequency operation device is left inserted into the operation device insertion channel of the endoscope, two kinds of operations, that is, an operation to dissect a mucous membrane and an operation to separate thus dissected mucous membrane can be carried out safely and efficiently. 
         [0044]    The entire disclosure of each and every foreign patent application from which the benefit of foreign priority has been claimed in the present application is incorporated herein by reference, as if fully set forth.