Patent Publication Number: US-2011077666-A1

Title: Ligating band dispenser device

Description:
CROSS-REFERENCE 
     This application claims the benefit of U.S. Provisional Application No. 61/247,285 filed on Sep. 30, 2009, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to the field of tissue ligation, and more particularly to an improved device for dispensing ligating bands. 
     BACKGROUND INFORMATION 
     Physicians have used elastic ligating bands to treat lesions, including internal hemorrhoids and mucositis and for performing mechanical hemostasis. For ligating tissue inside a body cavity, orifice, or lumen, physicians often use an endoscope to access the target tissue and ligate it. In one such form of endoscopic ligation, the physician uses the endoscope to position a stretched elastic band over the target tissue and then release the band onto the tissue so that the band contracts and catches the tissue. 
     The object of such ligation is to position a ligating band, which is usually elastic, over the targeted lesion or blood vessel section by first stretching the band beyond its undeformed diameter and then drawing the tissue to be ligated within the band. Thereafter the band is released so that it contracts, applying inward pressure on the section of tissue caught within the band. The effect of the inward pressure applied by the band is to cut off circulation through the targeted tissue, thereby causing the tissue to die. The body then sloughs off the dead tissue, or the dead tissue may be aspirated into an endoscope or a similar device. 
     Ligating instruments have been the subject of a number of patents, including U.S. Pat. No. 5,269,789 to Chin et al.; U.S. Pat. No. 5,356,416 to Chu et al.; U.S. Pat. No. 5,398,844 to Zaslaysky et al.; U.S. Pat. No. 5,857,585 to Tolkoff et al.; U.S. Pat. No. 5,853,416 to Tolkoff; U.S. Pat. No. 5,913,865 to Fortier et al.; U.S. Pat. No. 6,235,040 to Chu et al.; U.S. Pat. No. RE 36,629 to Zaslaysky et al.; and U.S. Pat. No. 7,063,709 to Fortier. The disclosures of these prior U.S. patents are expressly incorporated by reference herein. 
     U.S. Pat. No. 5,398,844 to Zaslaysky et al. allows a user to place several ligating bands at desired locations without removing the device from the patient&#39;s body to reload ligating bands. It uses multiple pull strings to deploy the ligating bands. 
     U.S. Pat. No. 5,913,865 to Fortier et al. (“the Fortier &#39;865 patent”) describes a distal end for a ligating band dispenser that allows a plurality of ligating bands to be actuated sequentially by the same trigger line. The supporting structure as shown in the embodiments of FIGS. 1 and 17 of the Fortier &#39;865 patent includes a plurality of slots in the distal end of the device that are arranged so that the trigger line need only pass through each slot once. The Fortier &#39;865 patent describes how the slots can have alternating depths, such that alternating shallow slots and deeper slots are disposed on the distal end for retaining the trigger line. 
     SUMMARY OF THE INVENTION 
     The invention is directed to improvements in ligating band dispenser devices and in methods for deploying ligating bands. 
     A disclosed embodiment provides for a ligating band dispenser device for mounting on a distal end of an endoscope comprising a ligating band support structure having a longitudinal axis, an outer surface, a proximal end and a distal end, with the ligating band support structure being adapted to be mounted on the distal end of the endoscope. The device also comprises one or more ligating bands mounted around the outer surface of the ligating band support structure, a ligating band deployment structure having an engagement structure for engaging and deploying the ligating bands, and a displacement mechanism adapted to displace the ligating band deployment structure in an axial direction distally and proximally relative to the ligating band support structure. In this embodiment, the ligating band deployment structure has a first engagement position in which the engagement structure engages a first ligating band, a deployment position distal to the first engagement position in which the engagement structure causes the engaged ligating band to deploy from the distal end of the ligating band support structure, and a second engagement position in which the engagement structure engages a second ligating band. The displacement mechanism displaces the ligating band deployment structure distally from the first engagement position to the deployment position to deploy the first ligating band. The displacement mechanism also displaces the ligating band deployment structure proximally from the deployment position to the second engagement position to engage the second ligating band, and the displacement mechanism displaces the ligating band deployment structure distally from the second engagement position to the deployment position to deploy the second ligating band. 
     Another embodiment provides for a ligating band dispenser device for mounting on a distal end of an endoscope comprising a ligating band support structure having a longitudinal axis, an outer surface, a proximal end and a distal end. The device also comprises one or more ligating bands mounted around the outer surface of the ligating band support structure, a ligating band deployment structure adapted to be mounted on the distal end of the endoscope and having an engagement structure for engaging and deploying the ligating bands, and a displacement mechanism adapted to displace the ligating band support structure in an axial direction distally and proximally relative to the ligating band deployment structure. In this embodiment, the ligating band support structure has a first engagement position in which the engagement structure engages a first ligating band, a deployment position proximal to the first engagement position in which the engagement structure causes the engaged ligating band to deploy from the distal end of the ligating band support structure, and a second engagement position in which the engagement structure engages a second ligating band. The displacement mechanism displaces the ligating band support structure proximally from the first engagement position to the deployment position to deploy the first ligating band. The displacement mechanism also displaces the ligating band support structure distally from the deployment position to the second engagement position to engage the second ligating band, and the displacement mechanism displaces the ligating band support structure proximally from the second engagement position to the deployment position to deploy the second ligating band. 
     Another embodiment provides a method of deploying a plurality ligating bands, comprising providing a ligating band dispensing device comprising a ligating band support structure having a longitudinal axis, an outer surface, a proximal end and a distal end, a plurality of ligating bands mounted around the outer surface of the ligating band support structure, a ligating band deployment structure having an engagement structure for sequentially engaging and deploying each of the ligating bands, and a displacement mechanism adapted to displace one of the ligating band deployment structure and ligating band support structure in an axial direction distally and proximally relative to the other of the ligating band deployment structure and ligating band support structure. In this embodiment, the method also comprises positioning the ligating band dispensing device in a first engagement position in which the engagement structure of the ligating band deployment structure engages a first ligating band mounted around the outer surface of the ligating band support structure, actuating the ligating band dispensing device from the first engagement position to a deployment position to deploy the first ligating band from the distal end of the ligating band support structure, positioning the ligating band dispensing device in a second engagement position in which the engagement structure of the ligating band deployment structure engages a second ligating band mounted around the outer surface of the ligating band support structure, and actuating the ligating band dispensing device from the second engagement position to the deployment position to deploy the second ligating band from the distal end of the ligating band support structure. 
     Depending on the embodiment, the invention can have advantages including simplicity of design, simplicity of manufacturing, reduced manufacturing costs, more reliable deployment, reduced complications during deployment, improved visibility, improved suction of tissue to be ligated, improved ease of use, avoidance of trigger line tangling or interference, improved room in the endoscope working channel, and/or improved overall performance. These and other features and advantages of the disclosed devices and methods are described in, or apparent from, the following detailed description of various exemplary embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments will be more readily understood through the following detailed description, with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a ligating band dispenser device according to a first embodiment; 
         FIG. 2  is a perspective view of a ligating band dispenser device according to a second embodiment; 
         FIG. 3  is a perspective view of a ligating band dispenser device according to a third embodiment; 
         FIG. 4  is a perspective view of the ligating band dispenser device of  FIG. 1  with the outer cylinder in a resting position; 
         FIG. 5  is a perspective view of the ligating band dispenser device of  FIG. 1  in the first engagement position; 
         FIG. 6  is a perspective view of the ligating band dispenser device of  FIG. 1  moving from the first engagement position to the deployment position; 
         FIG. 7  is a perspective view of the ligating band dispenser device of  FIG. 1  after the ligating band has been deployed; 
         FIG. 8  is a schematic of the flexible engagement element of the first and second embodiments shown in  FIGS. 1 and 2 ; 
         FIG. 9  is a schematic of another embodiment of a flexible engagement element; 
         FIG. 10  is a schematic of another embodiment of a flexible engagement element; 
         FIG. 11  is a schematic of another embodiment of a flexible engagement element; 
         FIGS. 12   a - 12   c  are perspective views of three embodiments of a ligating band dispenser device mounted on an endoscope with a trigger wire mechanism for retracting the outer cylinder for dispensing the ligating bands; 
         FIG. 13  is a schematic of one embodiment of an exemplary actuator for dispensing the ligating bands; 
         FIG. 14  is a schematic of another embodiment of an exemplary actuator for dispensing the ligating bands; and 
         FIG. 15  illustrates an alternative embodiment in which the outer cylinder is fixed relative to the endoscope and the inner cylinder is movable relative to the endoscope to deploy the ligating bands. 
     
    
    
     DETAILED DESCRIPTION 
     For a general understanding of the features of the illustrated embodiments of the invention, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to designate like elements. 
     As illustrated in  FIG. 1 , a ligating band dispenser  10  according to a first embodiment includes a ligating band support structure in the form of a substantially cylindrical inner structure  20  which has a central bore or channel  15  extending axially through the inner structure  20 . The central channel  15  is wide enough to accept tissue into the channel and allow visualization through it, for example, when the ligating band dispenser  10  is attached to the distal end of endoscope  5 . As illustrated, the reference letter P indicates the proximal side of the device, and the reference letter D indicates the distal side of the device. In this embodiment, the ligating band dispenser  10  includes a flexible connector  6  which allows the ligating band dispenser  10  to be attached to the distal tip of endoscope  5 . A plurality of elastic ligating bands  30  are received in a stretched condition around the inner structure  20 . 
     Inner structure  20  has a longitudinal axis extending from a proximal end to a distal end. Inner structure  20  also has an outer surface. As illustrated in  FIGS. 1-3 , ligating bands  30  are mounted around the outer surface of inner structure  20  by stretching the ligating bands  30  onto and around the outer surface. Ligating bands  30  may be held on the outer surface by the compressive force of the elasticity of the bands or by any means known conventionally in the art including, but not limited to, transverse ridges or grooves on the outer surface of the inner structure as disclosed in, for example, U.S. Pat. No. 7,063,709 to Fortier. 
     As illustrated in  FIGS. 1-3 , a ligating band dispenser  10  according to these illustrated embodiments also includes a ligating band deployment structure in the form of an outer structure  40  positioned outside the outer surface of inner structure  20 . In these embodiments, outer structure  40  comprises two main parts, a mounting portion  41  and an engagement structure  45 . As illustrated in  FIGS. 1-3 , the shape of the outer structure  40  may be substantially cylindrical and configured to surround the outer surface of inner structure  20  in a circumferential direction. 
     The engagement structure  45  extends distally in an axial direction from the mounting portion  41  of the outer structure  40 . The engagement structure  45  is used to sequentially engage and deploy each of the plurality of ligating bands  30 , as described further below. In the embodiments of  FIGS. 1-3 , the engagement structure  45  comprises flexible engagement elements  50  in the shape and form of arms that extend distally from the mounting portion  41 . The flexible engagement elements  50  further comprise an engagement surface  55  that, as the device is used, sequentially abuts and engages each of the plurality of ligating bands  30 . In use, as described further below, the engagement surface  55  pushes each of the ligating bands  30  distally to deploy each of the ligating bands  30  from the distal end of the inner structure  20 . 
     According to the first embodiment, the inner structure  20  also comprises at least one track  25  extending in the direction of the longitudinal axis of inner structure  20 . As illustrated in  FIG. 1 , inner structure  20  may comprise a plurality of tracks  25 , and each track  25  may accommodate a flexible engagement element  50 . In this embodiment, each flexible engagement element  50  has a corresponding track  25  allowing movement of the flexible engagement element  50  within its respective track  25  to guide the flexible engagement element  50  along the axial direction of the inner structure  20  during engagement and deployment of the ligating bands  30 . The depth and shape of the tracks  25  are not particularly limited, but may generally be configured to the shape of the portion of the flexible engagement element  50  that travels within each track. The tracks  25  facilitate the engagement and deployment of the ligating bands  30  by allowing the engagement surface  55  to engage the ligating band  30  below the inner radial surface of the ligating band  30 , which enhances the rolling or sliding action of the ligating band  30  as its moves distally along the outer surface of the inner structure  20 . 
       FIGS. 2 and 3  illustrate a second and third embodiment, respectively, wherein the ligating band support structure or inner structure  20  does not have tracks. In these embodiments, the innermost radial surface or edge of the flexible engagement elements  50  rests or contacts the inner structure  20  on the outer surface. In these embodiments, at least a bottom portion of the engagement surface  55  engages the ligating band directly and pushes the ligating band distally as it slides or rolls off the distal end of the inner structure  20 . 
     The ligating band dispenser  10  also comprises a displacement mechanism illustrated in part in  FIGS. 1-3  and further in  FIGS. 12   a - 12   c . In  FIGS. 1-3  and  12   a - 12   c , the displacement mechanism is adapted to displace the outer structure  40  in an axial direction distally and proximally relative to the inner structure  20 . In alternative embodiments (such as that illustrated in  FIG. 15  as described further herein), the displacement mechanism is adapted to displace an inner structure in an axial direction proximally and distally relative to the outer structure. In  FIGS. 1-3  and  12   a - 12   c , the displacement mechanism includes a trigger line  100 , as illustrated in  FIGS. 12   a - 12   c , adapted to pull the outer structure in an axial direction. Depending on the embodiment, a trigger line  100  may be used to pull the outer structure in a proximal direction, a distal direction, or both. The displacement mechanism may also include a spring  60 . The spring  60  may be used to move the outer structure  40  in a distal or proximal direction. In the embodiments illustrated in  FIGS. 1-3 , a spring  60  biases the outer structure  40  in the distal direction. 
     Referring now to  FIG. 3 , a third embodiment is described. As illustrated in  FIG. 3 , each flexible engagement element  50  of the ligating band deployment structure or outer structure  40  may include a hinged tooth  80  for engaging the ligating bands  30  and at least one hinge  90  for attaching each hinged tooth  80  to the remainder of the outer structure  40 . In an engagement position, the hinged tooth  80  extends radially inwardly to engage a ligating band  30  and push it forward. In this embodiment, each hinge  90  is configured to permit rotation of the hinged tooth  80  from its engagement position, such that when the outer structure  40  is moved proximally (or, in an alternative embodiment, when the inner structure is moved distally), the hinge  90  allows rotation of the hinged tooth  80  so that it can ride over a ligating band  30 . Each hinge  90  is also configured to prevent rotation of the hinged tooth  80  from the engagement position when the outer structure  40  is moved distally so that when the outer structure  40  is moved distally the hinged tooth  80  forces the ligating band  30  distally over the outer surface of the inner structure  20 . 
     The hinged tooth  80  and hinge  90  may be constructed in a variety of ways that will be apparent to persons skilled in the art. For example, the hinged tooth  80  may be configured to be operated by a spring mechanism that holds the hinged tooth  80  in a resting position disturbed only by the proximal movement of the outer structure  40 . In alternative embodiments, the hinged tooth  80  may be configured to be controlled independently of the outer structure  40  such as, for example, by a separate trigger line or by automated electric means. In other alternative embodiments, the flexible engagement element of the ligating band deployment structure may comprise another flexible component, a component suspended from the remainder of the ligating band deployment structure, or a component attached to the remainder of the ligating band deployment structure by a “living hinge.” 
     The operation of the embodiment of  FIG. 1  is illustrated in  FIGS. 4-7 , but it will be understood that other embodiments, such as the embodiments of  FIGS. 2 and 3 , may operate in a similar manner. For the purpose of example only, the use of the ligating band dispenser  10  will be described with reference to the human esophagus. However, one of ordinary skill in the art will recognize that the ligating band dispenser  10  may be used throughout the human body where ligation is desired and may be accomplished using a device as disclosed. 
     After attaching the ligating band dispenser  10  to the distal end of an endoscope  5  via the flexible connector  6 , the user, for example a physician, inserts the endoscope into the esophagus of the patient. The physician guides the endoscope  5  coupled with the ligating band dispenser  10  to find the distressed tissue, such as, for example, a varix on the esophageal surface. In this regard, it will be understood that the placement of the ligating band dispenser  10  on the endoscope  5  is such that the peripheral view of the endoscope is maximized as described in, for example, the Fortier &#39;865 patent. It will be further understood that the inner structure  20  may be made of a transparent or translucent material so as to enhance the physician&#39;s view of the ligating bands  30  situated on the inner structure  20  and to enhance the overall peripheral vision of the endoscope. 
     It is contemplated that the outer cylinder  40  described in embodiments disclosed herein may also temporarily be moved to enhance the peripheral vision of the endoscope in certain situations. For example, the outer cylinder  40  may be retracted by the displacement mechanism so that the physician can obtain a better view. 
     Once the physician identifies a varix to be ligated, the physician moves the distal end of the inner structure  20  situated at the distal end of the endoscope  5  over the varix on the esophageal tissue. The varix may already be raised, or it may be enhanced with a fluid injection beneath the tissue. Once the distal end of the inner structure  20  is positioned over the varix, if desired, suction may be applied by any suitable means to force the distressed tissue into the channel  15  of the inner structure  20 . The distal-most surface of the inner structure  20  may be a flat and substantially smooth surface, as illustrated in  FIGS. 1-7 , so as to provide a good surface for maintaining suction between the inner structure  20  and the esophageal tissue. 
     While disclosed embodiments describe a flat and smooth distal surface of inner structure  20 , the surface of inner structure  20  may also be configured to further enhance suction, such as, for example, by treatment of the surface with a biochemical tissue adhesive or micro perforations for use in a more advanced vacuum system in addition to, or replacing, conventional endoscopic suction elements. 
     Up until this point, the ligating band dispenser  10  remains in a resting or start position, which may be as illustrated in  FIG. 4 . In the resting position illustrated in  FIG. 4 , the outer structure  40  is positioned such that the engagement surfaces  55  of the engagement elements  50  are distal to the first (i.e., the distal-most) ligating band  30 . In alternative embodiments, the resting position can have the outer structure  40  positioned in other positions. 
     After suction has been established, the displacement mechanism is actuated to displace the outer structure  40  proximally into the first engagement position, as illustrated in  FIG. 5 . In the first engagement position, the engagement surfaces  55  of the engagement elements  50  are proximal to the first (i.e., the distal-most) ligating band  30 , such that the first band  30  is engaged by the engagement surfaces  55 . The resting position of the device may also be the first engagement position, such that the ligating band dispenser is initially provided in the position shown in  FIG. 5 . 
     When the outer structure  40  is in the first engagement position, the first band  30  can be deployed by movement of the outer structure  40  distally to the deployment position.  FIG. 6  shows the outer structure  40  moving from the first engagement position to the deployment position. When the outer structure  40  advances far enough distally, it pushes the ligating band off of the distal end of the inner structure  20  so that it deploys around the tissue.  FIG. 7  shows the outer structure  40  in the deployment position, showing the ligating band deployed from the device. 
     After deployment of the first ligating band  30 , the outer structure  40  may be refracted proximally to engage the next (second) ligating band  30 . Accordingly, the displacement mechanism displaces the outer structure  40  proximally from the deployment position to the second engagement position to engage the second ligating band  30 . Then, the displacement mechanism displaces the outer structure  40  distally from the second engagement position to the deployment position to deploy the second ligating band  30 . Subsequent ligating bands  30  are deployed in a sequential manner, as described herein with respect to the first and second ligating bands, until all bands have been deployed or the procedure is otherwise terminated. 
     Referring again to the first and second embodiments as illustrated in  FIGS. 1 and 2 , the engagement structure  40  as shown in those figures includes at least one flexible engagement element  50 , and each flexible engagement element  50  includes an engagement surface  55 .  FIGS. 8-11  illustrate alternative structures for the flexible engagement element  50 . As illustrated in  FIGS. 8-11 , the flexible engagement element  50  includes a flexible arm  75  and finger  70  that protrudes inwardly in a radial direction toward the outer surface of the inner structure  20  from the flexible arm  75  to contact the inner structure  20 . The distal-most surface of the finger  70  may be the engagement surface  55 . The finger  70  may have an engagement surface  55  that extends substantially orthogonal to the longitudinal axis of the inner structure  20 , as illustrated in  FIG. 8 . 
     The proximal surface of the finger  70 , in certain embodiments, may be sloped from the bottom of the proximal surface to the top of the proximal surface. In the embodiment illustrated in  FIG. 8 , the angle of this slope relative to the inward radial-most surface  57  of the finger  70  is less than 90°, or it may have other configurations, such as less than 50°, as illustrated in  FIG. 10 . The sloping of this proximal surface facilitates movement of the flexible engagement element  50  over a ligating band when the outer structure  40  is displaced proximally. The sloping may be curved, straight, or any other suitable configuration. In other embodiments, the proximal-most surface of the finger  70  may be substantially orthogonal to the axial direction of the inner structure  20 , similar to the distal-most surface illustrated in  FIG. 9 . 
     In other embodiments, each engagement surface  55  may be configured to the shape of the ligating band  30  to be deployed to enhance engagement of the flexible engagement element  50  with the ligating band  30  during deployment.  FIG. 11  illustrates one such embodiment. In  FIG. 11 , the finger  70  is sloped distally in a radially inward direction from the flexible arm  75  so as to create a distal space between the finger  70  and the flexible arm  75  that fits the ligating band  30 . Conforming the engagement element  50  in this manner enhances the contact between the engagement element  50  and the ligating band  30  to reduce disengagement during deployment. While the engagement surface of finger  70  in  FIG. 11  that engages the ligating band  30  is illustrated as concave, an alternative design may be used in which the engagement surface is convex, which would allow the ligating band  30  to more easily slide off of the finger  70  for deployment. In  FIG. 11 , the proximal surface of the finger  70  is convex, which facilitates the movement of the finger  70  over the ligating bands when the ligating band deployment structure is moved in a proximal direction from the deployment position to an engagement position. 
     It is further contemplated that the inner structure  20  and/or the outer structure  40  may be coated with a lubricious coating, for example TEFLON (polytetrafluoroethylene), or treated with a lubricant to facilitate movement of the outer structure  40  across the outer surface of the inner structure  20  or to facilitate movement of the ligating bands across the surface of the inner structure  20 . 
     While  FIGS. 8-11  illustrate various forms of flexible engagement elements for the engagement structure of the outer structure, it will be appreciated that other forms are possible. For example, the engagement structure may comprise one or more flexible fingers or hinges that extend inwardly from a cylinder of the outer structure. Alternatively, the engagement structure may comprise one or more rigid arms, each having one or more flexible arms or hinges. Alternatively, the engagement structure may comprise one or more flexible arms, with or without fingers or hinges. Other configurations are possible within the scope of the invention. 
       FIGS. 12   a - 12   c  illustrate various forms for the displacement mechanism. In the embodiments illustrated in  FIGS. 12   a  and  12   c , the trigger line  100  is pulled proximally to displace the outer structure  40  proximally, and the spring  60  displaces the outer structure  40  distally. Thus, for example, the trigger line  100  is pulled to move the outer structure  40  from the resting position to the first engagement position. Then, the spring  60  displaces the outer structure  40  from the first engagement position to the deployment position to deploy the first band  30 . Then, the trigger line  100  is pulled to displace the outer structure  40  from the deployment position to the second engagement position. Then, the spring  60  displaces the outer structure  40  from the second engagement position to the deployment position to deploy the second band  30 . This action can be repeated to sequentially deploy the bands  30 . 
     In alternative embodiments, such as illustrated in  FIG. 12   b , the trigger line  100  is pulled proximally to displace the outer structure  40  distally, and the spring  60  provides a proximal force on the outer structure  40  to displace the outer structure  40  proximally. Thus, for example, the trigger line  100  is pulled to displace the outer structure  40  from the first engagement position to the deployment position to deploy the first band  30 . Then, the spring  60  displaces the outer structure proximally from the deployment position to the second engagement position. Next, the trigger line  100  is pulled to displace the outer structure  40  from the second engagement position to the deployment position to deploy the second band  30 . This action can be repeated to sequentially deploy the bands  30 . 
     The embodiments illustrated in  FIGS. 12   a - 12   c  will now be described in more detail. As illustrated in  FIG. 12   a , the trigger line  100  extends inside outer channel  110 , which runs along the outside of endoscope  5  axially from the proximal end to the distal end. The distal end of the trigger line  100  is mounted on the proximal end of outer structure  40  at the location marked by an “x.” The distal end of the trigger line  100  is mounted on the outer structure  40  by any suitable means. In this embodiment, pulling on the trigger line  100  creates a direct proximal force on the outer structure  40 . 
     In the embodiment illustrated in  FIG. 12   b , the trigger line  100  extends through an inner channel  115 , which runs through the inside of endoscope  5  axially from the proximal end to the distal end. The trigger line  100  then runs through the channel of the inner structure  20  and around the distal end of the inner structure  20 . The trigger line  100  then returns in a proximal direction to be mounted to the proximal end of outer structure  40  at the location marked by an “x,” which is accomplished by any suitable means. The trigger line  100  runs under the ligating bands  30 . In this example, the trigger line  100  runs through one of the plurality of tracks  25  to avoid entanglement with the ligating bands  30  during deployment. Trigger line  100  may further run through a slot (not shown) in the engagement surface  55  of the flexible engagement element  50  and underneath the engagement structure  45  to be mounted on the mounting portion  41  of the outer structure  40 . Alternatively, a separate track not associated with an engagement element can be provided for the trigger line  100 . In an alternative arrangement, the trigger line  100  in  FIG. 12   b , instead of being attached as shown, can extend further proximally, turn back distally around a hook or through a hole mounted at the proximal end of the inner structure  20  and then attach to the outer structure  40 , such that pulling the trigger line  100  proximally pulls the outer structure proximally as in the embodiments illustrated in  FIGS. 12   a  and  12   c . With such an arrangement, the spring  60  can be arranged to force the outer structure  40  distally. Alternative configurations and placement of the trigger line  100  are possible within the scope of the invention, as would be understood by persons of ordinary skill in the art. 
     In the embodiment illustrated in  FIG. 12   c , the trigger line  100  extends through an inner channel  115 , which runs through the inside of endoscope  5  axially from the proximal end to the distal end. The trigger line  100  then extends through an opening  125  in the inner structure  20  located between the distal end of the inner structure  20  and the distal end of the endoscope  5 . The trigger line  100  is then mounted on the proximal end of outer structure  40  on the mounting portion  41  by any suitable means. The opening  125  may have a suitable seal so as not to adversely impact the suction through the inner structure  20 . 
     In each of the embodiments illustrated in  FIGS. 12   a - 12   c , the force applied by the trigger line  100  and the spring  60  operate to balance and control movement of the outer structure  40 . In this regard, such movement may be controlled by the operator from a proximal end of the endoscope outside the patient&#39;s body. When the trigger line  100  is used to move the outer structure  40  proximally and a spring  60  is used to push the outer structure  40  distally, the trigger line  100  may be pulled in increasing increments from the proximal end of the endoscope  5 . That is, the trigger line  100  may be pulled a first distance to engage the first band  30 , then released to allow the spring action to deploy the first band  30 , then the trigger line  100  may be pulled a second distance greater than the first distance to engage the second band  30 , then released to allow the spring action to deploy the second band  30 , and so on. A gauge or controller may be provided at the proximal end to insure that the trigger line  100  is pulled the correct distance each time. When the trigger line  100  is used to move the outer structure  40  distally and a spring  60  is used to pull the outer structure  40  proximally, the trigger line  100  may be released in increasing increments from the proximal end of the endoscope  5 . That is, the trigger line  100  may be released a first distance to allow the spring  60  to pull the outer structure  40  back proximally a first distance to engage the first band  30 , then the trigger line  100  may be pulled to move the outer structure  40  distally to deploy the first band  30 , then the trigger line  100  may be released a second distance greater than the first distance to allow the spring  60  to pull the outer structure  40  back proximally a second distance to engage the second band  30 , then the trigger line  100  may be pulled to move the outer structure  40  distally to deploy the second band  30 , and so on. A gauge or controller may be provided at the proximal end to insure that the trigger line  100  is released the correct distance each time. 
     In alternative embodiments, the displacement mechanism may include an actuator  200  or  300  located at the proximal end of the endoscope  5  for pulling the trigger line  100  in a proximal direction in sequential increments so as to cause the engagement structure  50  of the outer structure  40  to sequentially engage each of the ligating bands  30  for sequential deployment of each of the ligating bands  30  from the distal end of the inner structure  20 , as illustrated in  FIGS. 13 and 14 . 
     In the embodiment illustrated in  FIG. 13 , the actuator  200  comprises a rack and pinion system for controlling movement of the outer structure  40  in the axial direction. For purposes of this embodiment, the actuator  200  is described relative to the embodiment of the displacement mechanisms illustrated in  FIGS. 12   a  and  12   c . It will be understood, however, that this embodiment could be configured to be used with other displacement mechanisms. 
     As illustrated in  FIG. 13 , an exemplary rack and pinion system includes a pinion  210  and a rack  230 . The rack  230  has teeth  232  that engage teeth  212  on pinion  210 . The pinion  210  is coupled to a spool  220  on which the trigger line  100  can be wound. The rack is coupled to a spring  240  which in turn is attached to a housing  250  (shown schematically). The pinion  210  can be mounted with respect to the housing  250  for rotation within the housing  250 . The rack  230  can be mounted with respect to the housing  250  for sliding back and forth within the housing  250 . 
     In the embodiment of  FIG. 13 , the housing  250  can have an index mark I, and the rack can have a set of indicia as shown, such as the numbers 1 through 7, corresponding to the engagement positions for the ligating bands  30 . To move the outer structure  40  to the first engagement position, the physician moves the rack  230  in the proximal direction (shown by the arrow P) until the indicia “1” lines up with the index mark I. This rotates the pinion  210  by the proper distance so as to pull the trigger wire  100  proximally the correct amount in order to move the outer structure proximally to the first engagement position. Then, upon release of the rack  230 , the spring action of spring  240  returns the rack  230 , and the spring action of the spring  60  moves the outer structure  40  to the deployment position, deploying the first band. Then, to move the outer structure  40  to the second engagement position, the physician moves the rack  230  in the proximal direction until the indicia “2” lines up with the index mark I. Then, upon release, the spring action of spring  240  returns the rack  230 , and the spring action of the spring  60  moves the outer structure  40  to the deployment position, deploying the second band. This action is repeated to sequentially deploy the bands. 
     The rack  230  may be attached to a suitable finger trigger or other mechanism to allow it to be actuated. In addition, the rack may cooperate with a stop mechanism that sequentially stops the rack  230  at each sequential stopping place for the sequential bands. For example, the rack  230  can have a pin that cooperates with a series of slots, the length of each slot corresponding to the distance required to move to the engagement position for a respective band  30 . Upon first retraction of the rack  230 , the pin moves within the first slot to move the rack  230  to the first engagement position. Then, upon release, the pin moves to the second slot, such that upon second retraction of the rack  230 , the pin moves within the second slot, longer than the first, so as to move the rack  230  to the second engagement position. Various other mechanisms may be used to insure retraction of the rack  230  by the correct distance each time. For example, the retraction distance may be computer controlled. 
     In another embodiment, illustrated in  FIG. 14 , the actuator  300  may comprise a disk and peg system for controlling movement of the outer structure  40  in the axial direction. For purposes of this embodiment, the actuator  300  is described relative to the embodiment of the displacement mechanism illustrated in  FIGS. 12   a  and  12   c . It will be understood, however, that this embodiment could be configured to be used with other displacement mechanisms. 
     As illustrated in  FIG. 14 , an exemplary disk and peg system includes a corrugated disk  310  that includes breakable pegs  315  and spool  320 .  FIG. 14  also depicts trigger line  100  running through outer channel  110  or inner channel  115  of the endoscope  5 , a distal end of the trigger line  100  being mounted on the proximal end of outer structure  40 . In this embodiment, the trigger line  100  is configured to be fixed on the spool  320  and wrapped around the radial-most surfaces of the each breakable peg  315 . Although fixed to the corrugated disk  310 , breakable pegs  315  are configured to hold the trigger line  100  taut against the spring  60  acting on the outer structure  40  until the point of deployment, whereupon the increasing distal pushing force of the spring  60  acting on the outer structure  40  increases to a point at which it breaks the breakable peg  315 . The breakable pegs  315  can be made of any suitable material with a predetermined strength high enough to resist the distal force of the spring to the point before deployment but low enough to break under the increased distal force from the spring  60  as the corrugated disk  310  is actuated. 
     In practice, for example, when the engagement structure  45  is in a resting position, the physician actuates the corrugated disk  310  in a clockwise direction pulling the trigger line  100  in a proximal direction, which moves the outer structure proximally, against the distal counteractive force of the spring  60 , into the first engagement position. As the corrugated disk  310  is actuated, the counteractive distal force from the spring  60  on the trigger line  100  increases such that once the outer structure  40  reaches the engagement position, as shown in  FIG. 5 , the distal force from the spring  60  acting on the outer structure  40  and thus the trigger line  100  provides a high enough force to break the clockwise-most breakable peg  315 . Under this force, the clockwise-most breakable peg  315  breaks, disengaging the trigger line  100  from the clockwise-most breakable peg  315  and creating slack in the trigger line  100 . With slack in the trigger line  100 , the distal force of the spring  60  moves the outer structure  40  distally into the deployment position, as shown in  FIG. 6 . To move the outer structure into the second engagement position, the physician again actuates the corrugated disk  310  in a clockwise direction. The slack in the trigger line  100  remaining from the previous deployment is spooled around spool  320  until the trigger line is again taut against the next clockwise-most breakable peg  315 . The next clockwise-most breakable peg  315  is slightly stronger that the first one, such that the outer structure  40  can be pulled farther back, to the second engagement position engaging the second ligating band, before the second peg breaks. Once the outer structure  40  reaches the second engagement position, the force from the spring  60  breaks the second peg, and the spring forces the outer structure  40  to the deployment position, deploying the second band. It will be appreciated that each successive peg is slightly stronger than the one before it, to allow the outer structure  40  to be pulled back to sequentially increasing distances, in order to reach each of the ligating bands  30  in succession. 
     While the illustrated embodiments show a manually operated trigger line  100 , it is also envisioned that the trigger line  100  may be replaced by or part of an automated system for applying the appropriate force to pull the outer structure  40  distally or proximally. For example, the force to move the outer structure  40  may be supplied by electrical actuation, hydraulic actuation, heat actuation, shape memory material actuation, or electroactive material actuation (e.g., metals, polymers, gel). Similarly, the spring  60  may also be replaced by or part of an automated system for applying the compressive or distal force, such as, for example, an electric or hydraulic pump, or other forms of electrical actuation, hydraulic actuation, heat actuation, shape memory material actuation, or electroactive material actuation. In one example embodiment in which the displacement mechanism does not include a trigger line, the ligating band support structure and the ligating band deployment structure may each be attached to a tube, one inside the other, with the tubes moveable with respect to each other to move the device between the engagement positions and the deployment position. Other constructions for the displacement mechanism and its actuation are possible. For example, the displacement mechanism may include a handle and trigger arrangement, a dial mechanism and ratchet, or other suitable displacement mechanisms that are currently known in the art. 
     As illustrated in  FIG. 15 , a ligating band dispenser  10  according to another embodiment may include features of the embodiments disclosed herein except that the outer structure  40  is mounted on the endoscope and the inner structure  20  is moved proximally and distally by the displacement mechanism. In this embodiment, the displacement mechanism displaces the inner structure  20  proximally from the first engagement position to the deployment position to deploy the first ligating band  30 , the displacement mechanism displaces the inner structure  20  distally from the deployment position to the second engagement position to engage the second ligating band  30 , and the displacement mechanism displaces the inner structure  20  proximally from the second engagement position to the deployment position to deploy the second ligating band  30 , and so on. Compared to the embodiments depicted in  FIGS. 1-3  with a spring  60  and mounting portion  41 , as illustrated in  FIG. 15 , the mounting portion  41  is extended proximally to mount the outer structure  40  to the endoscope. 
     In this embodiment, an alternative seal structure (not shown) may be provided for maintaining appropriate suction while the inner structure  20  is moved relative to the outer structure  40 . While  FIG. 15  illustrates the inner structure  20  as a sliding structure, alternative configurations for the inner structure  20  are possible, such as, for example, a collapsing or telescoping structure. 
     While embodiments such as those illustrated in  FIGS. 1-3  and  15  have the ligating band deployment structure as an outer structure that is positioned outside the outer surface of the ligating band support structure, in alternative embodiments the ligating band deployment structure may be positioned radially inside of, or underneath, the ligating bands. Thus, for example, the ligating band support structure may have one or more tracks or grooves beneath the ligating bands for accommodating one or more engagement elements of the ligating band deployment structure. The engagement elements may be in the form of arms, fingers, or teeth as disclosed herein. The arms, fingers, or teeth may project radially outwardly between the ligating bands to advance the ligating bands relative to the ligating band support structure similar to other embodiments described herein. The displacement and actuation of the components may be similar to other embodiments as described herein. 
     Disclosed embodiments have been described with reference to several exemplary embodiments. There are many modifications of the disclosed embodiments which will be apparent to those of skill in the art. It is understood that these modifications are within the teaching of the present invention which is to be limited only by the claims.