Abstract:
A medical treatment instrument for an endoscope includes: an insulated sheath; a treatment member that is provided at a distal end of the sheath; and a wire loop that surround the treatment member and is capable of expansion and contraction by an operation at a proximal side of the sheath.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a medical instrument for an endoscope to be passed through a medical instrument insert channel of an endoscope in use, and used for dissection or exsection of mucous tunics of anatomy by distributing high-frequency current.  
         [0002]     A medical instrument for an endoscope generally has a structure in which a distal electrode to which high-frequency current can be distributed is projected forward from the distal end of an electrically insulating sheath, whereby mucous tunics or the like which is in contact with the distal electrode is dissected by Joule heat by distributing high-frequency current to the distal electrode which is pressed against the surface of the mucous tunics.  
         [0003]     However, when the distal portion of the endoscope is significantly displaced because an operator touches a curved operating knob of the endoscope or because a patient harrumphs and hence the anatomy side is suddenly moved during the operation of high-frequency medical treatment, an unscripted portion of the anatomy may accidentally be dissected.  
         [0004]     As a countermeasure of this problem, in the related art, there is a device in which the distal electrode is formed by a flexible metallic strand wire or the like so that the movement of the distal electrode with respect to a diseased part does not occur abruptly, even when the positional relationship between the distal end of the endoscope and the anatomy changes unexpectedly. (For example, JP-A-2002-153484)  
         [0005]     When the distal electrode is formed of the metallic strand wire, the distal electrode does not come apart from the dissected portion owing to bending motion of the distal electrode as long as the change of the positional relationship between the distal end of the endoscope and the anatomy is within a certain range, and hence a phenomenon in which dissection of the unscripted portion of the anatomy can be prevented from occurring.  
         [0006]     However, when the positional relationship between the distal end of the endoscope and the anatomy is changed unexpectedly by more than several centimeters, the change cannot be absorbed by such bending motion of the distal electrode, and hence there is a risk for dissecting the unscripted portion of the anatomy.  
         [0007]     Another kind of a medical instrument for an endoscope is known which is a beak-shaped medical instrument for an endoscope configured in such a manner that a pair of beak-shaped electrodes which are connected to a high-frequency power supply and open and close like a beak by remote control at the proximal end of a sheath are disposed at the distal end of the sheath which is to be inserted into and removed from the medical instrument insert channel of an endoscope. (for example, JP-A-2000-271128)  
         [0008]     When performing dissection or the like of anatomy with a beak-shaped medical instrument for an endoscope, an operation including the steps of clamping the anatomy with the beak-shape electrodes to which high-frequency current is distributed, dissecting the same, advancing the instrument a little, closing the same again, and dissecting the same is repeated.  
         [0009]     However, when the positional relationship between the distal end of the endoscope and the anatomy is moved unexpectedly and significantly because a patient harrumphs or an operator erroneously operates a curved operating knob of the endoscope when the beak-shaped electrodes are opened or completely closed during such high-frequency operation, it takes a lot of trouble to performing a guiding operation for restoring the beak-shaped electrodes accurately to a portion to be dissected of the diseased part, and hence dissection or exsection of the anatomy may not be performed smoothly.  
       SUMMARY OF THE INVENTION  
       [0010]     Accordingly, it is an object of the present invention to provide a medical instrument for an endoscope in which an distal electrode does not come apart from a diseased part even when the positional relationship between the distal end of the endoscope and the anatomy is changed unexpectedly and significantly during a high-frequency exsectioning operation, so that a high-frequency medial treatment can be performed safely.  
         [0011]     It is another object of the present invention to provide a beak-shaped medical instrument for an endoscope in which a beak-shaped electrode does not come apart from a diseased part even when the positional relationship between the distal end of an endoscope and anatomy during the high-frequency operation, and hence the high-frequency operation can be performed smoothly.  
         [0012]     In order to solve the aforesaid object, the invention is characterized by having the following arrangement.  
         [0000]     (1) A medical treatment instrument for an endoscope comprising:  
         [0013]     an insulated sheath;  
         [0014]     a treatment member that is provided at a distal end of the sheath; and  
         [0015]     a wire loop that surround the treatment member and is capable of expansion and contraction by an operation at a proximal side of the sheath.  
         [0016]     (2) The medical treatment instrument according to (1), wherein a pair of through holes are formed on a side wall of the sheath in a vicinity of the distal end of the sheath and a wire constituting the wire loop moves in and out through the through holes so that the wire loop is expanded and contracted.  
         [0000]     (3) The medical treatment instrument according to (1), wherein the sheath is adapted to be inserted into and removed from a medical instrument insert channel of the endoscope.  
         [0000]     (4) The medical treatment instrument according to (1), wherein  
         [0017]     the treatment member includes an electrode to which high-frequency current is adapted to be distributed, and  
         [0018]     the wire loop is insulated from the electrode.  
         [0019]     (5) The medical treatment instrument according to (4), wherein a conductive wire electrically connected to the distal electrode is inserted into and disposed in the sheath, and an operation wire to be operated from the sheath side for causing expansion and contraction of the wire loop is inserted into and disposed in the sheath alongside of the conductive wire so as to be capable of moving in the fore-and-back direction.  
         [0020]     (6) The medical treatment instrument according to (4), wherein a portion of the distal electrode projected from the distal end of the sheath is formed into a plate shape, and a surface of the projected plate-shaped portion and the wire loop are substantially flush with each other.  
         [0000]     (7) The medical treatment instrument according to (4), wherein an amount of projection of the distal electrode projecting forward from the distal end of the sheath can be adjusted by an operation at the proximal side of the sheath.  
         [0000]     (8) The medical treatment instrument according to (7), wherein the distal electrode can be projected from and retracted into the sheath.  
         [0000]     (9) The medical treatment instrument according to (4), wherein the distal electrode includes a pair of beak-shaped electrodes which open and close by remote control at the proximal side of the sheath, and  
         [0021]     wherein the wire loop surrounds a front space to which the pair of beak-shaped electrodes oppose is designed to be expanded and contracted independently from the opening and closing of the pair of beak-shaped electrodes by the operation at the proximal side of the sheath.  
         [0022]     (10) The medical treatment instrument according to (9), wherein through holes are formed through the pair of beak-shaped electrodes so as to penetrate therethrough in the opening and closing direction thereof, so that a proximal portions of a wire constituting the wire loop are led through an inner side of the pair of beak-shaped electrodes from the through holes into the sheath, respectively.  
         [0000]     (11) The medical treatment instrument according to (1), wherein  
         [0023]     high-frequency current is adapted to be distributed to the wire loop, and  
         [0024]     the wire loop is insulated from the electrode.  
         [0025]     According to the present invention, since the wire loop is disposed so as to surround the distal electrode so as to be capable of being expanded and contracted by the operation at the proximal side of the sheath, the dissecting operation by the treatment member can be performed by surrounding and lightly tightening the portion around the diseased part to be dissected. Therefore, even when the positional relationship between the distal end of the endoscope and the anatomy is changed unexpectedly and significantly during the high-frequency dissecting operation, the treatment member does not come apart from the diseased part and hence the high-frequency operation can be performed safely. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]      FIG. 1  is a cross-sectional plan view of a distal portion of a medical instrument for an endoscope according to a first embodiment of the present invention.  
         [0027]      FIG. 2  is a perspective view, partly broken, of the distal portion of the medical instrument for an endoscope according to the first embodiment of the invention.  
         [0028]      FIG. 3  is a general structure of the medical instrument for an endoscope according to the first embodiment.  
         [0029]      FIG. 4  is a perspective view showing a state of a dissecting operation of mucous tunics with the medical instrument for an endoscope according to the first embodiment of the invention.  
         [0030]      FIG. 5  is a perspective view, partly broken, of the distal portion of the medical instrument for an endoscope according to a second embodiment of the present invention.  
         [0031]      FIG. 6  is a plan view of a final operating element of the medical instrument for an endoscope according to the second embodiment of the invention.  
         [0032]      FIG. 7  is a cross-sectional side view of a distal portion of a beak-shaped medical instrument for an endoscope according to a third embodiment.  
         [0033]      FIG. 8  is a side view of a final operating element of the beak-shaped medical instrument for an endoscope according to the third embodiment of the present invention.  
         [0034]      FIG. 9  is a perspective view showing a state in which a high-frequency operation is performed using the beak-shaped medical instrument for an endoscope according to the third embodiment of the present invention.  
         [0035]      FIG. 10  is a cross-sectional side view of the distal end portion of the beak-shaped medical instrument for an endoscope according to a fourth and fifth embodiments of the present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0036]     Referring now to the drawings, embodiments of the present invention will be described.  
       FIRST EMBODIMENT  
       [0037]      FIG. 1  is a cross-sectional plan view of a distal portion of a medical instrument for an endoscope according to a first embodiment of the present invention, and  FIG. 2  is a perspective view thereof, showing that a flexible sheath  1  to be inserted into or moved from an insertion channel of the medical instrument for an endoscope is formed of an electrically insulating tube such as a Polytetrafluoroethylene tube.  
         [0038]     A distal electrode  2  formed of conductive metal is projecting forward from the distal portion of the flexible sheath  1 . In this embodiment, the portion of the distal electrode  2  projecting from the flexible sheath  1  is formed into a flat-plate shape, and a cylindrical proximal portion  2   a  formed integrally therewith is fitted into and fixed to the distal end of the flexible sheath  1 . Note that the distal electrode  2  is one of members constituting a treatment member according to the invention.  
         [0039]     The side surface of the proximal portion  2   a  of the distal electrode  2  is formed with a projection which is bitten into the inner peripheral surface of the flexible sheath  1 . However, the structure of fixation of the distal electrode  2  with respect to the flexible sheath  1  may be any other means such as screwing or bonding.  
         [0040]     Reference numeral  3  designates a conductive wire for supplying high-frequency current to the distal electrode  2 , which is inserted into and disposed in the entire length of the flexible sheath  1  and is bonded at the distal portion thereof to the proximal portion  2   a  of the distal electrode  2  by soldering or the like. The conductive wire  3  may be either a bare wire or a coated wire.  
         [0041]     The side wall of the flexible sheath  1  is formed with a pair of through-holes  4  at symmetrical positions of about 180° from the obliquely front direction respectively, and a wire constituting a wire loop  5  disposed so as to surround the distal electrode is inserted through the pair of through holes  4  into the flexible sheath  1 .  
         [0042]     The wire loop  5  is formed, for example, of polyester fiber or fluorine contained resin, having heat-resistant property and electrically insulating property, and the positional relationship with respect to the distal electrode  2  is set to be substantially flush with the surface (plate surface) of the distal electrode  2 .  
         [0043]     The wire constituting the wire loop  5  must simply be electrically insulated with respect to the distal electrode  2 , and hence it may be, for example, a fine stainless wire covered with a fluorine contained resin tube.  
         [0044]     The proximal portions of the wire loop  5  positioned in the flexible sheath  1  are connected to an operating wire  7 , which is inserted into and disposed alongside with the conductive wire  3  in the flexible sheath  1  so as to be capable of moving in the fore-and-aft direction, via a connecting pipe  6 .  
         [0045]     Therefore, by operating the operating wire  7  to move in the fore-and-aft direction as indicated by an arrow A at the proximal side, the wire loop  5  disposed so as to surround the distal electrode  2  at the front of the flexible sheath  1  is expanded and contracted as indicated by a chain double-dashed line in  FIG. 1 .  
         [0046]      FIG. 3  shows a general structure of the medical instrument for an endoscope according to the present embodiment, showing that the side surface of an operating body  21  of a final operating element  20  connected to the proximal end of the flexible sheath  1  is provided with a connecting terminal  23  to which a high-frequency power supply cable, not shown, so as to project therefrom, and the proximal portion thereof is connected to the proximal end of the conductive wire  3 . Therefore, by connecting the high-frequency power supply cord to the connecting terminal  23 , high-frequency current can be distributed to the distal electrode  2  via the conductive wire  3 .  
         [0047]     The proximal end of the operating wire  7  is connected to an operating portion  22  disposed at the operating body  21  so as to be slidable. When the operating portion  22  is slid as indicated by the arrow A, the movement thereof is transmitted to the distal side thereof by the operating wire  7  so as to expand and contract the wire loop  5 .  
         [0048]     When performing a dissecting operation of mucous tunics via the endoscope using the medical instrument for an endoscope configured as described above, as shown in  FIG. 4 , high-frequency current is distributed in a state in which the distal electrode  2  is pressed against a diseased part  100  in a state in which the diseased part  100  to be dissected is surrounded by and lightly tightened by the wire loop  5 , while observing the distal portion of the medical instrument for an endoscope projecting from a medical instrument insertion channel  51  of an endoscope  50 .  
         [0049]     Accordingly, the mucous tunics of the anatomy to which the distal electrode  2  is in contact is dissected, and even when the positional relationship between the distal end of the endoscope  50  and the diseased part  100  is significantly changed (or apt to be changed) because the operator touches the curved operating knob of the endoscope or the patient harrumphs, since the diseased part  100  is tightened by the wire loop  5 , the position of the distal electrode  2  with respect to the diseased part  100  does not change, and hence the high-frequency dissecting operation can be performed safely.  
       SECOND EMBODIMENT  
       [0050]      FIG. 5  shows a distal portion of the medical instrument for an endoscope according to a second embodiment of the invention, showing that the distal electrode  2  is disposed so as to be capable of moving in the axial direction so as to be projected from and retracted into the distal end of the flexible sheath  1 .  
         [0051]     In the present embodiment, since the distal electrode  2  is formed into a rod-shape, and the conductive wire  3  is inserted into and disposed within the flexible sheath  1  so as to be capable of moving in the fore-and-aft direction. The distal electrode  2  is disposed so as to pass through the center hole on a lid member  1   a  attached to the distal end of the flexible sheath  1  so that a stopper  2   a  formed at the proximal end of the distal electrode  2  comes into abutment of the back surface of the lid member  1   a.    
         [0052]     Therefore, by operating the conductive wire  3  to move in the fore-and-aft direction as indicated by an arrow B at the distal end, the distal electrode  2  is projected from the distal end of the flexible sheath  1  as indicated by an arrow C, and the amount of projection can be adjusted as desired. At this time, the stopper  2   a  abuts against the back surface of the lid member  1   a , and hence the distal electrode  2  does not project from the distal end of the flexible sheath  1  more than the fixed amount.  
         [0053]      FIG. 6  shows a final operating element  20  for the medical instrument for an endoscope according to the second embodiment, showing that a second operating portion  24  for operating the conductive wire  3  so as to move in the fore-and-aft direction as indicated by the arrow B is slidably mounted to the final operating element body  21 , and the connecting terminal  23  is provided on the second operating portion  24 .  
       THIRD EMBODIMENT  
       [0054]      FIG. 7  shows a distal portion of a beak-shaped medical instrument for an endoscope according to a third embodiment of the present invention, in which a distal end supporting body  102  formed of electrically insulating material such as ceramic is connected to the distal end of a flexible sheath  101  formed of an electrically insulating flexible tube such as a Polytetrafluoroethylene tube.  
         [0055]     A pair of beak-shaped electrodes  103  formed of conductive metal such as stainless steel into the shape of a biopsy forceps cup are supported at the position in the vicinity of the distal end of a slit  102   a  formed along the entire length of the distal end supporting body  102  except for the portion at the rear end by a spindle  104  so as to be capable of opening and closing toward the front like a beak, and drive arms  103   a  formed integrally with the respective beak-shaped electrodes  103  are disposed within the slit  102   a  at the position rearwardly of the spindle  104 . Note that the pair of beak-shaped electrodes  103  is one of the members constituting the treatment member according to the invention.  
         [0056]     A operating wire  105  formed of conductive material for opening and closing the beak-shaped electrodes  103  is inserted into and disposed in the flexible sheath  101  along the entire length thereof so as to be capable of moving forward and backward in the axial direction, and a pair of conductive drive wires  105   a  bifurcated from the wire  105  and connected by a connecting pipe  106  are connected to the drive arms  103   a , respectively.  
         [0057]     Therefore, the pair of beak-shaped electrodes  103  can be opened and closed like a beak about the spindle  104  when moving the electrode opening and closing wire  105  in the fore-and-aft direction from the proximal side of the flexible sheath  101 , and high-frequency current can be distributed to the respective beak-shaped electrodes  103  via the electrode opening and closing wire  105 . In  FIG. 7 , the closed state of the beak-shaped electrodes  103  is shown by a solid line, and the opened state of the same is shown by a chain double dashed line.  
         [0058]     The portions which correspond to the backs and the bottoms of the pair of beak-shaped electrodes  103  are formed with through holes  103   b ,  103   c  respectively, so that the proximal portions of a wire of a wire loop  107  formed of synthetic resin wire, such as polyester fiber or fluorine contained resin, having both heat resistance property and electrical insulating property are led through the through holes  103   b  on the backs of the respective beak-shaped electrodes  103 , and then into the flexible sheath  101  through the through holes  103   c  on the bottoms thereof.  
         [0059]     The wire which constitutes the wire loop  107  must simply be electrically insulated from the beak-shaped electrodes  103 , and hence may be the stainless steel wire covered by the fluorine resin contained tubes, for example.  
         [0060]     The proximal ends (both ends) of the wire loop  107  are connected to a distal end of the wire loop opening and closing wire  108  disposed so as to be capable of moving forward and backward in the axial direction alongside with the electrode opening and closing wire  105  in the flexible sheath  101  via a connecting tube  109 .  
         [0061]     The wire loop opening and closing wire  108  can be moved forward and backward from the proximal side of the flexible sheath  101  independently from the electrode opening and closing wire  105 , and the wire loop  107  is expanded and contracted in conjunction with the forward and backward movement of the wire loop opening and closing wire  108 .  
         [0062]     In  FIG. 7 , the contracted state of the wire loop  107  is shown by a solid line, and the expanded state of the same is shown by a chain double-dashed line, The wire loop  107  extends from the through holes  103   b  formed on the respective beak-shaped electrodes  103  so as to surround the space at the front to which the pair of beak-shaped electrodes  103  oppose.  
         [0063]      FIG. 8  shows a final operating element  120  provided on the proximal side of the beak-shaped medical instrument for an endoscope of this embodiment, and an electrode opening and closing handle  122  for moving the electrode opening operating wire  105  forward and backward and a wire loop opening and closing portion  124  for moving the wire loop opening and closing wire  108  forward and backward are disposed on a final operating element body  121  so as to be capable of sliding independently from each other.  
         [0064]     The electrode opening and closing handle  122  is formed with a connecting terminal  123  to which a high-frequency power supply cable, not shown, is connected so as to project therefrom, and the proximal end of the electrode opening and closing operating wire  105  is connected to the proximal portion thereof. Therefore, by connecting the high-frequency power supply cord is connected to the connecting terminal  123 , high-frequency current can be distributed to the beak-shaped electrodes  103  via the electrode opening and closing wire  105 .  
         [0065]     In this arrangement, when the electrode opening and closing operating handle  122  is operated forward and backward, the pair of beak-shaped electrode  103  are opened and closed via the electrode opening and closing wire  105 , and when the wire loop opening and closing operating handle  124  is moved forward and backward, the wire loop  107  is expanded and contracted via the wire loop opening and closing wire  108 . These operations can be performed independently from each other.  
         [0066]     When performing dissecting operation of mucous tunics via the endoscope using the beak-shaped medical instrument for an endoscope, as shown in  FIG. 9 , high-frequency current is distributed in a state in which the pair of beak-shaped electrodes  103  clamp a diseased part  200  in a state in which the diseased part  200  to be dissected is surrounded by and lightly tightened by the wire loop  107 , while observing the distal portion of the medical instrument for an endoscope projecting from a medical instrument insertion channel  151  of an endoscope  150  via a observation port  152 .  
         [0067]     Accordingly, even when the positional relationship between the distal end of the endoscope  150  and the diseased part  200  is significantly changed (or apt to be changed) because the operator touches the curved operating knob of the endoscope or the patient harrumphs, when mucous tunics of tissue which is clamped by the beak-shaped electrodes  103  is dissected and the pair of beak-shaped electrodes  103  are completely closed, or when the beak-shaped electrodes  103  are opened subsequently, since the diseased part  200  is tightened by the wire loop  107 , the position of the beat-shaped electrodes  103  with respect to the diseased part  200  does not change, and hence the high-frequency dissecting operation can be continued smoothly by moving the beat-shaped electrode  103  forward and then closed.  
       FOURTH EMBODIMENT  
       [0068]      FIG. 10  shows a fourth embodiment of the present invention, in which a pair of through holes  1   a  are formed on a side wall of the flexible sheath  101  in the vicinity of the distal end thereof at the symmetrical positions of about 180° from the obliquely front direction respectively, and the proximal portions of the wire, which constitutes the wire loop  107  are led into the flexible sheath  101  through the respective through holes  101   a . In this arrangement, the same operations and effects as the third embodiment described above can be obtained.  
         [0069]     In this embodiment, the pair of beak-shaped electrodes  103  are formed into scissors having no cutting edges and are electrically insulated from each other, and one of the beak-shaped electrode  103  is connected to the cathode side of the high-frequency power supply, and the other beak-shaped electrode  103  is connected to the anode side.  
         [0070]     As described above, the shape of the beak-shaped electrodes  103  in the present invention may by any type, and may be applied both to the beak-shaped medical instrument for an endoscope of a mono-polar type as in the third embodiment, and the beak-shaped medical instrument for an endoscope of a bipolar type as in the fourth embodiment.  
       FIFTH EMBODIMENT  
       [0071]     Because the structure of the fifth embodiment is almost same to that of the fourth embodiment, the fifth embodiment will be described with reference to  FIG. 10 .  
         [0072]     Difference between the fourth embodiment and the fifth embodiment is in the high-frequency current supply. That is, in the fifth embodiment, the high-frequency current is supplied to the wire loop  107  instead of the pair of beak-shaped electrodes  103 , and the pair of beak-shaped electrodes  103  is insulated from the wire loop  107 .  
         [0073]     The operation of the medical treatment according to the fifth embodiment will be described.  
         [0074]     When performing dissecting operation of mucous tunics with using the endoscope using the beak-shaped medical instrument according to the fifth embodiment, the pair of beak-shaped electrodes  103  clamps the diseased part and the wire loop  107  lightly tightens the diseased part. Then, the wire loop  107  is contracted by operating the wire at the proximal side of the sheath until the diseased part is dissected from the body while the high-frequency current is applied to the wire loop  107 . According to the fifth embodiment, since the pair of beak-shaped electrodes  103  clamp the diseased part while the wire loop  107  dissects the diseased part, the position of the wire loop  107  with respect to the diseased part does not change, and hence the high-frequency dissecting operation can be continued smoothly by contracting the wire loop  107 .  
         [0075]     Of course, the present invention is not limited to the embodiments described above and shown in the drawings, and can be realized by any modification without departing from the scope of the invention. For example, the medical instrument for an endoscope does not have to be designed to perform the high-frequency dissecting operation, and a cutter for simply cutting the diseased part may be employed as a treatment member provided at a distal end of the sheath.