TELESCOPING SERIAL ELASTIC BAND LIGATOR

Abstract: A ligating band dispenser has a plurality of elastic ligating bands at least one of which is supported on each of a series of partially nested cylinders. Inner and intermediate cylinders comprise axially sliding cylinders for dispensing the ligating bands. An outer cylinder, which may be attached to the distal end of an elongated introducer, surrounds at least the proximal portion of the intermediate cylinder and is adapted to receive the sliding cylinders slide into its distal end. A trip wire is connected to the inner cylinder and extends proximally therefrom through the elongated introducer. The trip wire is adapted to cause an axially sliding motion of the sliding cylinders during an application of force to the trip wire. A restraining means is associated with each sliding cylinder to restrain sliding motion thereof during the application of force to the trip wire. Finally, a releasing means is provided to release the restraining means associated with one of the sliding cylinders upon the application of the pulling force. The released sliding cylinder slides in response to the applied pulling force while a distal end of one of the intermediate and outer cylinders pushes the ligating band therefrom. According to this construction, at least two ligating bands may be independently dispensed onto tissue at one or more designated sites thereby accomplishing ligation thereof.

Description: TELESCOPING SERIAL ELASTIC BAND LIGATOR Background of the Invention Field of the Invention This invention generally relates to ligating instruments and more particularly to instruments for dispensing a plurality of ligating bands to one or more internal sites within a patient's body in a single ligation procedure, without removing the instrument between successive ligating band placements. Brief Description of Related Art The treatment of various types of lesions including internal hemorrhoids by ligation is well known. The object of ligation is to position an elastic cord, or ligating band, at the lesion to stop circulation through tissue and allow the tissue to necrose whereupon the body sloughs off the necrotic or dead tissue. Surgical ligation has also been employed in female and male sterilization procedures. In the case of tubal ligation in female patients, ligating rings or bands are placed on a folded-over loop portion of each Fallopian tube, blocking the path from uterus to ovaries, and thereby preventing fertilization of an ovum. In the case of male sterilization, a ligating band may similarly be placed on a folded-over loop portion of the vas deferens, thus preventing passage of spermatozoa from the testes. The following United States Letters Patent disclose various embodiments of ligating instruments: 3,760,810 to Van Hoorn; 4,257,419 to Goltner, et al.; and 4,735, 194 to Stiegmann. U.S. Pat. No. 3,760,810 to Van Hoom discloses an instrument for facilitating the placement of a single ligating band or set of bands. The instrument includes, at its distal end, a ligating band dispenser comprising two rigid, concentric tubes. The tubes can slide with respect to each other under the control of a trigger mechanism at the proximal end of the instrument. A rigid endoscope having internal passages forming a suction path and a light path interconnect the trigger mechanism and dispenser. The inner tube can be loaded with a set of one or more elastic rings or ligating bands. A separate stopper bar attaches to the instrument to prevent premature dispensing. When the instrument is located proximate to a lesion, a surgeon removes the stopper bar and applies vacuum to draw tissue into a hollow passage at the distal end of the instrument. Pulling on the trigger retracts the inner tube. A radial surface or shoulder on the outer tube engages the ligating band so it can not displace with the inner tube. As the inner tube is withdrawn from the ligating band, it collapses onto the tissue. U.S. Pat. No. 4,257,419 to Goltner, et al. discloses a rigid endoscope that includes a ligating band dispenser with an inner tube that moves with respect to an outer tube to dispense a ligating band. This dispenser is oriented at right angles to the rigid endoscope and includes a structure for moving the inner tube of the dispenser in this configuration. U.S. Pat. No. 4,735,194 to Stiegmann discloses a flexible endoscope ligating instrument in which a flexible endoscope structure includes a biopsy channel and a suction channel extending between the proximal and distal ends. A dispenser, like the dispenser structure shown in the Van Hoom and Goltner patents, includes an inner tube that moves axially with respect to an outer tube at the distal end of the instrument. The outer tube connects to the distal end of the endoscope. An operating mechanism in the form of a pull wire with a weighted handle maintains tension on the inner tube so it does not displace axially outward while the instrument is being positioned. For some applications it is suggested that the endoscope structure be inserted through an overtube to prevent premature dispensing. Suction can be applied to draw tissue into a central aperture of the dispenser. Then a surgeon pulls the handle and retracts the inner tube axially past the distal end of the outer tube to force the ligating band off the instrument onto the tissue. Each of the foregoing instruments dispenses a single ligating band or a single set of ligating bands at a single location. None of the patents suggests dispensing ligating bands at discrete locations. The Nan Hoom patent does disclose the possibility of depositing plural ligating bands. However, Van Hoom seems only to suggest dispensing plural ligating bands at a single site in a single operation. The apparatus disclosed in the Nan Hoom, Goltner or Stiegmann patents apparently would have to rely on a surgeon's sense of touch in order to displace the inner tube by an incremental distance corresponding to the thickness of a stretched ligating band to deposit a plurality of bands at different sites. That would be very difficult to accomplish. With the foregoing described devices, when it is desired to deposit ligating bands at different sites, the common practice was to withdraw the entire instrument from the patient and load a new ligating band onto the inner tube. Loading ligating bands on an instrument requires special tools and could be time consuming particularly if the special tooling must be retrieved to install each ligating band individually while the instrument is withdrawn. Each of these instruments requires some structure, such as special stoppers or overtubes, for preventing the premature dispensing of the ligating band. Consequently, none of these instruments was readily adapted for dispensing ligating bands at different sites without withdrawing the instrument after each individual site is ligated. Aimed at solving the aforementioned problems, the following United States Letters Patent disclose various embodiments of ligating instruments which are designed to deposit or place a plurality of ligating bands at one or more internal sites within a patient without the necessity of withdrawing the ligating instrument to reload successive ligating bands: 3,985,138 to Jarvik; 4,226,239 to Polk et al. ; 3,870,048 to Yoon; 5,207,690 to Rohrabacher et al.; and 5,269,789 to Chin. U.S. Patent No. 3,985,138 to Jarvik discloses a ligature gun for placing a plurality of preformed suture loops which are tightened around bleeders after emplacement. The successive preformed suture loops are advanced to the dispensing end of the ligature gun by rotation of a threaded rod onto which the loops have been preloaded. The Jarvik ligature gun comprises large number of mechanical parts and is relatively complex in design and operation. U.S. Patent No. 3,870,048 to Yoon discloses the use of elastic bands or rings in tubal ligation. The Yoon device is constructed so as to permit two or more ligating rings to be loaded at the same time, but discharged separately at different times and in succession to one another, even at different locations, all without removing the ligating device from the patient's body cavity. Yoon's device is also relatively complex. U.S. Patent No. 4,226,239 to Polk et al. also describes a surgical ligating instrument for tubal ligation within a human or animal body, by the application of two or more elastic ligating rings without the necessity of removing the instrument from the patient for each ligating ring. In the device of Polk et al. , a number of ligating rings are stretched over a cylindrical shaft which is slidably and concentrically received within an outer cylindrical sleeve. As the cylindrical shaft is withdrawn proximally with respect to the outer sleeve, the outer sleeve successively forces the ligating rings off of the shaft, preferably one at time. The extent of relative motion between the shaft and the sleeve is controlled by a mechanical stop at the proximal end of the shaft, located in the pistol handle of the instrument. The surgeon can be sure that a only single band has been placed only if the mechanical stop is precisely calibrated to the width of an individual ligating ring. U.S. Patent No. 4,860,746 discloses a device similar to that of Polk et al. U.S. Patent No. 5,207,690 to Rohrabacher et al. teaches that successive ligating rings may be slipped off of the cylindrical shaft onto which they have been preloaded by the use of separate forceps. U.S. Patent No. 5,269,789 to Chin et al. discloses a ligating band dispenser located at the distal end of an elongated introducer, which dispenser responds to manipulation of an operating structure at the proximal end of the introducer. The dispenser comprises first and second coaxially located, interfitted segments that support ligating bands at a plurality of axially spaced positions thereon. Each segment includes a spaced ligating band engagement structure for engaging portions of each ligating band or set of bands. One of the segments connects to the operating structure for being moved between first and second positions relative to the other of the segments. This motion dispenses one of the ligating bands from the distal end of the ligating instrument and moves the remaining ligating bands distally with respect to the dispensing means thereby to position a successive ligating band for being dispensed at a different site, as in some of the aforementioned devices as well. The Chin et al. instrument, however, is an improvement over those devices in that it is specially constructed to prevent more than a single ligating band from being dispensed in response to a single actuation of the operating structure. On the other hand, the ligating bands are initially greatly stretched when loaded onto the Chin et al. instrument, bringing about the necessity of a relatively strong spring in order to slide the bands distally. The surgeon's hand must work against this spring when actuating the device. Moreover, advancement of the ligating bands toward the dispensing end of the device requires the bands to be stretched even further than their initial stretched conditions. Such stretching requires even greater force to applied by the surgeon's hand. U.S. Patent No. 5,356,416 to Chu et al. discloses a device similar to Chin et al. further including a sclerotherapy needle for administering a sclerotherapy agent as an alternative to ligating a lesion. Objects and Summary of the Invention Therefore, it is an object of this invention to provide an instrument that can dispense plural ligating bands in sequence at discrete sites. Another object of this invention is to provide a ligating instrument that can deposit plural ligating bands in sequence without requiring the instrument to be removed from a patient after each ligation. Still another object of this invention is to provide a ligating band dispenser for attachment to diverse introducer structures including rigid and flexible endoscopes for ligating tissue. The present invention permits multiple band firing without the need to retracting, reloading, and reinserting the dispenser. As a result, reintubation is required only after several ligating bands have been fired. Generally, a single intubation with the ligating band dispenser of the present invention is sufficient to ligate the tissue at at least one internal tissue site within a patient's body. This affords a savings in time and reduces patient discomfort during the procedure. According to the invention, a ligating band dispenser located at the distal end of an elongated introducer responds to manipulation of an operating structure at the proximal end of the introducer. The dispenser supports a plurality of elastic ligating bands on a series of cylinders. An inner cylinder has proximal and distal portions and is adapted to support at least one ligating band in a stretched condition on or about its distal portion. A intermediate cylinder also has proximal and distal portions, and further has a distal end. Th intermediate cylinder is positioned about or surrounding at least the proximal portion of th inner cylinder and is adapted to support at least another ligating band in a stretched condition on or about its distal portion. The inner and intermediate cylinders comprise axially slidin cylinders for dispensing the ligating bands. An outer cylinder which is removably attachabl to the distal end of the elongated introducer, is positioned about or surrounding at least th proximal portion of the intermediate cylinder. The outer cylinder has a distal end into whic the sliding cylinders slide. A trip wire is connected to the inner cylinder and extends proximally therefrom through the elongated introducer. The trip wire is adapted to cause an axially sliding motion of the sliding cylinders during an application of force to the trip wire. A restraining means is associated with each sliding cylinder to restrain sliding motion thereo during the application of force to the trip wire. Finally, a releasing means is provided to release the restraining means associated with one of the sliding cylinders upon the application of the pulling force. The released sliding cylinder slides in response to the applied pulling force while the distal end of either the intermediate or outer cylinder pushes the ligating band therefrom. According to this construction, at least two ligating bands may be independently dispensed onto tissue at one or more designated sites thereby accomplishing ligation thereof. The intermediate cylinder may comprise a succession of intermediate cylinders, each of which is positioned about or surrounding the proximal portion of a preceding cylinder. Each of the succession of cylinders has at least a further ligating band thereabout. The successive cylinders are arranged so that they telescope sequentially with successive applications of pulling forces on the pull wire to push the bgating bands from one of the preceding and inner cylinders. According to this construction, a plurality of ligating bands may be independently dispensed onto tissue at one or more designated sites, for example, five ligating bands, without reloading the dispenser or the necessity of reintubating the patient. The releasing means is preferably configured to release the restraining means associated with another of the sliding cylinders upon each successive application of the pulling force. The dispenser also preferably includes complementary apertures and protuberances formed on adjacent ones of the inner, intermediate, and outer cylinders. The protuberances of one cylinder are received in the slots of an adjacent cylinder. The apertures have predetermined lengths such that the travel of each of the sliding cylinders is defined by the predetermined lengths of the apertures. More generally, the ligating band dispenser may support a plurality of elastic ligating bands on a series of supporting members. A first support member has proximal and distal portions and is adapted to support at least one ligating band in a stretched condition about its distal portion. A second support member has proximal and distal portions, and further has a distal end. The second support member is positioned about or surrounding at least the proximal portion of the first support member and is adapted to support at least another ligating band in a stretched condition on or about its distal portion. The first and second support members comprise axially sliding support members for dispensing the ligating bands. A fixed member which is removably attachable to the distal end of the elongated introducer, is positioned about or surrounding at least the proximal portion of the second support member. The fixed member has a distal end into which the sliding support members slide. A trip wire is connected to the first support member and extends proximally therefrom through the elongated introducer. The trip wire is adapted to cause an axially sliding motion of the sliding support members during an application of force to the trip wire. A restraining means is associated with each sliding support member to restrain sliding motion thereof during the application of force to the trip wire. Finally, a releasing means is provided to release the restraining means associated with one of the sliding support members upon the application of the pulling force. The released sliding support member slides in response to the applied pulling force while the distal end of one of the second support and fixed members pushes the bgating band therefrom. According to this construction, at least two ligating bands may be independently dispensed onto tissue at one or more designated sites thereby accomplishing ligation thereof. These and other features and advantages of the invention will be readily apparent from the following detailed description of certain embodiments taken in conjunction with the accompanying unsealed drawings. Brief Description of the Drawings The appended claims particularly point out and distinctly claim the subject matter of this invention. The various objects, advantages and novel features of this invention will be more fully apparent from a reading of the following detailed description in conjunction with the accompanying drawings in which like reference numerals refer to like parts, and in which: FIG. 1 is a perspective view of a first embodiment of a ligating instrument dispenser constructed in accordance with this invention; FIG. 2 is an exploded, perspective view of the dispenser of the embodiment of FIG. 1 showing several slidably mounted cylinders in spaced relation to one another and their spring tab-type locking mechanisms; FIG. 2 A is a perspective view of a modified dispenser of FIG. 1 in which the locking mechanism is a spring; FIG. 2B is a bottom view, partially broken away, of the embodiment of FIG. 1; FIG. 3 is a cross sectional view taken along line 3-3 of FIG. 1, showing the device in assembled form and in a fully loaded state immediately prior to placement of a bgating band; FIG. 4 is a cross sectional view taken along line 4-4 in FIG. 3; FIG. 5 is a cross sectional view taken along line 5-5 in FIG. 3; FIG. 6 is an enlarged view of FIG. 3 showing the device in a partially activated state prior to delivery of a ligating band; FIG. 7 is a cross sectional view taken along line 7-7 in FIG.6; FIG. 8 is now showing the device immediately after delivery of a ligating band; FIG. 9 is a cross sectional view of a second embodiment of a bgating instrument dispenser according to this invention, showing the device in assembled form and in a fully loaded state immediately prior to placement of a ligating band; FIG. 10 is a cross sectional view taken along line 10-10 in FIG. 9; FIG. 11 is a cross sectional view of the embodiment of FIG. 9 showing the device in a partially activated state just prior to firing a ligating band; FIG. 12 is a cross sectional view of a third embodiment of a bgating instmment dispenser according to this invention, showing the device in assembled form and in a fully loaded state; FIG. 12 A is a cross sectional view of the embodiment of FIG. 12 in an actuated state just after dispensing a ligating band; FIG. 13 is a cross sectional view of a fourth embodiment of a ligating instmment dispenser according to this invention, showing the device in assembled form and in a fully loaded state immediately prior to placement of a ligating band; FIG. 14 is a cross sectional view taken along line 14-14 in FIG. 13; FIG. 13A is a perspective view of one of the pull wires of FIG. 13; FIGS. 15A - 15C is a cross sectional view taken along line 15A, B, C - 15A, B, C in FIG. 13, showing altemative lumen configurations for housing a tip wire and one or more pull wires for use with the embodiment of FIG. 13; and FIG. 16 is a cross sectional view of the embodiment of FIG. 13, now showing the device after delivery of a second bgating band; FIG. 17 is a cross sectional view taken along line 17-17 in FIG. 15; FIG. 18 is a cross sectional view of a fifth embodiment of a bgating instmment dispenser according to this invention, showing the device in assembled form and in a fully loaded state immediately prior to placement of a bgating band, and showing a trip wire; and FIG. 19 is a cross sectional view taken along line 19-19 in FIG. 18, with the trip wire shown in a rotated state relative to FIG. 18. Detailed Description of Several Embodiments FIG. 1 depicts, in perspective view, a first embodiment of a bgating instmment 30 that serially dispenses elastic bgating bands during a succession of operations by a surgeon. The bgating instmment 30 generally includes an introducer in the form of an elongated, rigid tubular housing 32. A proximal end portion 34 of the instmment 30 comprises a proximal actuator or controller 36 for causing a bgating band to be dispensed by the instmment 30. The housing 32 is formed in a hollow tubular form to provide a central or axial passage that communicates a proximal vacuum connection 38 to a distally mounted ligature dispenser 40, as will be explained in greater detail below. The proximal controller 36 is connected to the dispenser 40 by a pull or trip wire that passes through a proximal seal (not shown) located within the proximal end portion 34 of the instmment 30. Variations of such a proximal actuator and pull wire operating structure have been incorporated in bgating instmment s. The specificaUy disclosed embodiment is merely representative of such diverse implementations. The proximal seal referred to above allows suction to be appbed by the vacuum connection 38 and the central passage of the instmment to and through the dispenser 40, while abowing proximal manipulation of the trip wire. With such a proximal seal in place, suction appbed to the vacuum connection 38 draws tissue into the dispenser 40 for bgation, as will be made clear below. While a specially designed bgating instmment 30 has been illustrated, it will be readily apparent to those of ordinary skill in the relevant art that the dispenser 40 may be connected, such as by a friction fit, to the end of a conventional endoscope having a central lumen therethrough and access ports at the proximal working end to permit the application of suction and the passage of a trip wire externally of the endoscope handle. In such a case. the surgeon may simply pull on the trip wire itself to debver a bgating ring, or she may attach a clamp of any suitable kind to the trip wire, for ease of manipulation. None of these differences affects the scope of the present invention, which is directed to the construction and operation of dispenser 40 itself. The bgating instmment 30 or a conventional endoscope may further include means for providing visualization of internal body tissue distal of the dispenser 40, such as a conventional fiber optic and lens arrangement (not shown) or the like. In use, such visualization means generaby assists the surgeon in guiding the dispenser 40 to the desired tissue site to be bgated. Referring generally to FIGS. 2 though 8, in which like component parts are consistently numbered for ease of reference, the component parts and manner of assembly of a first embodiment of the dispenser 40 of the bgating instmment 30 of FIG. 1 are shown in detail. First Embodiment FIG. 2 shows an exploded, perspective view of the dispenser 40. In the illustrated embodiment, the dispenser 40 comprises four telescoping support members, illustrated as cylinders, three of which are axially sbdably mounted and have bgating bands or rings 50 disposed thereon. The axial movable cylinders include, in radial succession (as shown from right to left), an inner cylinder 42 and first and second intermediate cylinders 44, 46. The bgating bands 50a, 50b, and 50c are disposed on or about a distal portion of these cylinders, respectively (see tG. 2B). The bgating bands 50 are preferably formed of isoprene and are circular having a generally square sobd body cross section. So formed, each band 50 has a flat, smooth inside surface 52 for mounting on the cybnders 42, 44, and 46. An outer cylinder 48, shown broken away in FIG. 2, is rigidly coupled to the housing 32. As illustrated, the outer diameter of each cybnder and the inner diameter of an adjacent cybnder are chosen so that the annular gap therebetween is sufficient to permit unrestricted or free sbding of the cybnders, yet insufficient to permit the bgating bands 50 to fit or be pinched therebetween when pushed therefrom, as explained more fully below. According to one aspect of the invention, the bgating bands 50 are successively dispensed by releasing a lock mechanism 54 that restrains axial, telescoping movement of a cylinder (supporting the bgating band) into an adjacent cybnder. As used herein, a "lock mechanism" refers to a mechanism that provides a positive stop on the dispenser 40 whereby a single bgating band is dispensed with a single actuation of an actuator, such as the proximal controller 36. In the embodiment of -FIGS. 3-8, the lock mechanism comprises spring tabs 54a, 54b, and 54c adapted to normally project radially inwardly in their relaxed state to impede proximal sbding motion of cybnders 42, 44, and 46. The spring tabs 54 may be formed integral to the first and second intermediate cylinders and the outer cybnder, respectively, when the cybnders are formed by, for example, an injection molding process. Alternatively, a region of material that outlines the spring tabs 54 may be removed on three sides thereof to define the spring tabs 54, for example, using a sbtting saw, and then plastically deforming the cut out spring tabs 54 about a wrapping tool or the like by a col bending process to rebably impart a curve within prescribed tolerances sufficient to form the lock mechanism function as previously described, and as shown in FIGS. 2 and 2B. In FIG. 2A, a perspective view of a modified lock mechanism 54A is shown with some parts rotated and other parts omitted for clarity. The lock mechamsm 54 A comprises an arcuate spring element 55 preferably located in an annular slot 57 formed in each of the outer 48 and first and second intermediate 44, 46 cybnders. The spring element 55 may be made by conventional spring forming techniques. The cybnders are provided with a slot 59 which is in register with the annular slot 57. A curved tip portion 61 of the spring element 55 is adapted to project through the slot 59 and extend into the cylinders 44, 46, and 48 in the same manner as the spring tabs 54 to provide a lock mechanism to restrain proximal motion of the assembled cybnders (see, for example, FIGS. 2B and 3). The extent of axial travel of the cylinders 42, 44, 46 are limited by axial slots 56, 58, 60 in adjacent cybnders. With reference now to FIGS. 2 and 2B, the latter of which shows a bottom view, partiaUy broken away, of the assembled dispenser 40, the axial restraint mechanism can be better appreciated. The outer cybnder 48 has an axial slot 58 that receives a protuberance 62 extending radially outwardly from the second intermediate cybnder 46 to interlock the two cylinders. Likewise, the second intermediate cylinder 46 has an axial slot 60 which receives a protuberance 64 extending radially outwardly from the first intermediate cybnder 44 to interlock those two cybnders. Finally, the first intermediate cylinder 44 has an axial slot 60 which receives a protuberance 66 extending radially outwardly from the inner cylinder 42 to interlock those two cylinders. Alternatively, any pair of the previously described slots 56, 58, 60 and protuberances 62, 64, 66, respectively, could be located in reverse, that is with radially inwardly extending protuberances engaging a suitably positioned slot, and still achieve the aforementioned interlocking of the cylinders 42, 44, 46 and 48. In the preferred embodiment, the slots 56, 58, and 60 are circumferentially displaced or offset, for example, by thirty degrees, to add structural integrity to the dispenser 40 and to better ensure that the relative abgnment of the cylinders 42, 44, 46, and 48 remains intact. Relative motion among the cybnders can be limited, restrained, or both, in other ways, as can be readily appreciated. Each of the protuberances is mounted on a flexible tab to facibtate assembly of the dispenser 40. In the fully loaded, initial state of FIGS. 1 to 5, each of protuberances 62, 64, 66 is maintained at the distal end of a respective slot 56, 58, 60 by the circumferentially directed spring tabs of the lock mechanism 54, described in further detail below. Except for FIG. 8, the slots 56, 60, and 62 and protuberances 58, 64, and 66 have been omitted for clarity. Referring now to FIG. 3, and also simultaneously to cross-sectional views shown in FIGS. 4 and 5, the dispenser 40 is shown in its assembled, fully loaded and initial state of operation. Tubular housing 32 of the bgating instmment 30 is shown, broken away, for the sake of clarity. In practice, a proximal cylindrical portion 68 of a cap 70 is frictionally engaged about tubular housing 32, with the distal end face 72 of tubular housing 32 abutting a boss or mounting stop 74 in cap 70. Altematively, cap 70 and housing 32 may be secured together by other means, for example, an adhesive. The cap 70 may be formed of substantiaUy transparent polycarbonate, or of another, flexible material suitable for establishing a friction fit over the distal end face 72 of the tubular housing 32. The endoscope has a biopsy channel 76 extending to the proximal end 34. The biopsy channel 76 (or another channel that extends from end to end) contains a trip wire 78 used to dispense the bgating bands 50a, 50b, and 50c. Ligating band 50a is stretched over and about the distal end of inner cylinder 42 so that its flat surface 52a is along the exterior surface of the inner cybnder 42 and is positioned so that the distal end 80 of the first intermediate cylinder 44 abuts the bgating band 50a. The bgating band or ring 50b is similarly stretched over and about the distal end of the first intermediate cybnder 44 and abuts a distal end 82 of the second intermediate cylinder 46. Finally, bgating ring 50c is stretched over and about the second intermediate cybnder 46 and abuts a distal end 84 of the outer cybnder 48. A lubricous coating or other surface contour may be interposed between a bgating band and its supporting cylinder or, more generally, supporting member. Manipulation of the proximal controller 36 by a surgeon enables the successive firing of the bands 50a, 50b, and 50c onto any tissue 90 that may b drawn into a hollow distal end 92 of the dispenser 40 by suction, as described below. Th proximal controller 36 is linked to the telescoping cybnders 42, 44, 46, and 48 by the trip wire 78 and a release mechanism 100. The release mechanism 100 comprises a pivot 102 which is secured to the inner cybnder 42 and is axially movable therewith in a proximal direction (to the left in the figure) when the spring tab 54a of the first intermediate cylinder 44 is displaced radiaby outwardly to a position clear of the proximal end 106 of the inner cybnder 42. Manipulation of the proximal controller 36 provides tension in the trip wire 78. The trip wire is anchored to the pivot 102 by a trip wire anchor 108 secured in an aperture or notch, such that the tensioned trip wire 78 causes the pivot 102 to rotate about a pivot pin 110 against the restoring force of a pivot spring 112. The pivot spring 112 nominally biases the pivot 102 in a locked position whereby the locking spring tab 54a prevents axial motion of the cylinder 42 and the dispensing of bgating band 50a. As the pivot 102 rotates about pivot pin 110, a pivot arm or "bird's beak" 114 presses upon the spring tab 54a to cause the same to displace radially outwardly. When the spring tab 54a has been displaced so that the proximal end 106 of the inner cybnder 42 is clear of the tab 54a (see FIG. 7), the tensioned trip wire 78 draws the inner cybnder 42 proximally. Meanwhile, the distal end 80 of the first intermediate cybnder 44 restrains proximal motion of the bgating band 50a as the inner cylinder 42 is telescoped proximally under the flat surface 52a. Continued proximal motion forces the band 50a distally off of the inner cylinder 42 and of the dispenser 40 onto or over the tissue 90 thereby accompbshing bgation thereof (see -FIG. 8). The bgating bands 50b and 50c remain loaded for subsequent placement at the same (or different) location as the bgating band 50a. The tissue 90 may be a varix, an internal hemorrhoid, or other internal body structure, as the case may be. To prevent the firing of multiple bgating bands with a single manipulation of the proximal controUer 36, the pivot arm 114 is coupled to the pivot 102 by a traibng bnk which comprises a pivot arm pin 116 and a pivot arm spring 118. FIG. 6 illustrates the dispenser 40 in a fully loaded yet intermediate or transient position during the telescoping of the inner cybnder 42 just prior to placing bgating band 50a. As shown in FIG. 6, the trailing link enables the pivot arm 114 to depress the spring tab 54a sufficient to clear the proximal end 106 of the inner cybnder 42, yet ensures that a pivot arm tip 120 folds under (or drags behind) the pivot 102 with the proximal movement of the release mechanism 100 with each telescoping cybnder. Preferably, the surgeon or other person manipulating the proximal controller 36 appUes a steady pull to the trip wire 78 once the tissue 90 is aspirated into the dispenser 40. The pivot arm tip 120 folds under the pivot 102 as the pivot 102 is towed proximaby by the force appbed to the trip wire 78. When the pulling force is released from the trip wire 78, the pivot arm tip 120 returns to its nominal, unfolded rest position, as shown in FIGS. 3 and 8. As a result, the pivot arm tip 120 engages the lock mechamsm 54 of only one cybnder with each actuation of the proximal controller 36. It has been empiricaUy determined that the pulling force on the trip wire 78 may cause a mild elastic stretching of the trip wire until such a time that a force sufficient to overcome the static frictional seating of the bgating band 50 has been provided. Only after a force sufficient to release the static frictional seating and cause movement of the sbding cylinder (42, 44, or 46) has been appbed, will that cylinder move or snap into a surrounding cybnder. Until such time, however, an elastic force may develop in the trip wire 78 in the direction of the pulling force. Ultimately, the pulling force and elastic force will overcome the break away friction required to displace the bgating band 50 from the sliding cybnder (42, 44, or 46). At this moment, the elastic force will temporarily provide a force that is greater than the bgating band's coefficient of dynamic friction so that the proximal movement of the sbding cylinder is maintained even if the pulling force is released. The proximal movement of the sliding cybnder draws the distal attachment point of the trip wire 78 toward the proximal controller 36 and thereby releases the elastic stretch of the trip wire 78, if any. The energy stored in the elasticaUy stretched trip wire, if stretched, precludes any "half-pub" condition, in which the operator or surgeon may release the pulling force from the trip wire 78 prematurely, that is, after the sbding cylinder has been released but prior to displacing the bgating band. As a result, there is bttle or no risk that a half-pub condition will result in which the trip wire 78 has been pulled without causing a bgating band to be dispensed or allowing a subsequent pull to result in two bands being fired. According to the invention, the lock mechanism provides a positive stop which precludes the possibility of firing multiple bgation bands 50 with a single actuation of the proximal controller 36 and which permits the surgeon to apply a steady force to the trip wire 78 with confidence that only one bgating band will be dispensed. Nevertheless, to further reduce the risk of misfiring, and as a modification of the foregoing, the travel of the cylinders may be tailored to decrease the likelihood that the pivot arm tip 120 (which is axially repositioned with the telescoping movement of the inner cylinder 42) will engage more than one spring tab 54. For example, the total axial movement of the trip wire 78 to dispense the ligating band 50a may be less than that required to dispense the bgating band 50b, and the axial movement of the trip wire 78 to dispense the bgating band 50b may be less than that required to dispense the bgating band 50c. In FIG. 6, the pivot arm tip 120 engages the spring tab 54a of the first intermediate cybnder 44 to permit the inner cybnder 42 to telescope into the intermediate cybnder 44 and thereby dispense the bgating band 50a, as previously described. This trailing bnk rebably releases the lock mechamsm 54 of the cylinder that is closest to the innermost, loaded cylinder, which in the illustration of FIG. 6 is the inner cybnder 42. Further, by the construction of the release mechanism 100, including the trailing linkage on the bird's beak, the surgeon is assured that only a single bgating ring has been dispensed by dispenser 40 of the bgating instmment 30. Also, the dispenser 40 is adapted so that the pivot arm tip 120 is positioned over the spring tab 54b (see FIG. 8) once the bgating band 50a has been dispensed and the inner cybnder 42 telescoped into the first intermediate cybnder 44. Until the tension to the trip wire 78 is released, the traibng bnk maintains the bird's beak distal to the lock mechamsm of the next loaded cylinder (see FIG. 6, where the bird's beak 120 has moved proximaby with the dispensing of the bgating band 50a, but remains distal to the next lock mechanism 54b. Accordingly, the release mechanism 100 will release spring tab 54b upon subsequent actuation of the proximal controller 36 so that bgating band 50b can be dispensed, and so on, until the last (outermost) bgating band is dispensed. Preferably, the dispenser 40 is mounted onto the tubular housing 32 such that the release mechanism 100 is rotationally abgned with the biopsy channel 76 or other channel through which the trip wire 78 extends. The proximal cylindrical portion 68 of the cap 70 of the dispenser 40 may include an abgnment marker to assist in this preferred rotational abgnment. In FIG. 7, the pivot arm tip 120 is shown having a portion 121 that extends from the tip 120 to contact the lock mechanism 54 with a reduced frictional coefficient, as by shaping or coating the portion 121. In order to place a bgating band on a varix, internal hemorrhoid, or other internal body structure, as the case may be, the distal end of the instmment is positioned adjacent such tissue in conventional manner. Suction is then appbed via vacuum connection 38. In this way, the tissue 90 to be bgated is drawn within central bore 92 of the dispenser 40 as shown in dotted lines in -FIG. 3. In this position, the instmment may be actuated to place a bgating band 50 (first bgating band 50a) on the tissue to achieve bgation, as wul now be explained with reference to -FIG. 8. Inner and intermediate cylinders 42, 44, and 46, like all other components of the instmment 30, include a hollow central passage for the appbcation of suction at the distal end of the device. Upon the next successive actuation of the bgating device, band 50b will be dispensed, and then band 50c, and so on. -FIG. 8 illustrates the dispenser 40 immediately after delivery of the first bgating band 50a onto tissue 90. The debvery of the bgating band 50a caused the inner cybnder 42 to telescope into the first intermediate cybnder 44 until the protuberance 66 reached the proximal end of the slot 60 and caused the trailing link to fold under the pivot 102. The tension appbed to the trip wire 78 to dispense the ligating band 50a has been released in FIG. 8, as seen by the upright (normally biased) position of the bird's beak 114. Subsequent manipulation of the proximal controUer 36 again causes the pivot arm tip 120 to release the lock mechamsm of the innermost, loaded cylinder, which is now the spring tab 54b of the second intermediate cylinder 44. Once the spring tab 54b is depressed clear of a proximal edge 122 of the first intermediate cybnder 44, the first intermediate cybnder (along with the inner cylinder 42 and the release mechamsm 100) telescopes into the second intermediate cybnder 46 to dispense the bgating band 50b. As with the dispensing of bgating band 50a, the trailing bnk precludes dispensing additional bgating bands by folding over so as to not release the lock mechanism of the next loaded cylinder (which, in this illustration, is cybnder 46 with bgating band 50c thereabout). The dispenser 40 could be modified so that the spring tabs 54 secure the nested or telescoped cybnders together. In FIG. 8, the nested inner cylinder 42 is secured to the first intermediate cybnder 44 by the engagement of the spring tab 54a of the latter to an aperture 126 of the former. In particular, once the pivot arm tip 120 has engaged the lock mechanism 54a and has depressed the spring tab 54a sufficient to clear the proximal end 106 of the inner cylinder 42, the proximal end 106 of the inner cybnder 42 sbdes into the first intermediate cylinder 44 against the resilient restoring force of the spring tab 54a which may be adapted to project into the space occupied by the inner cylinder 42. When the inner cybnder 42 is sbd proximally a distance sufficient to dispense the bgating band 50a, the spring tab 54a is clear to return to its relaxed state within the aperture 126, just distal to the proximal end 106 of the inner cylinder 42. Likewise, the second intermediate cybnder 46 can be secured to the inner and first intermediate cybnders by engagement of spring tab 54b into the radiaby inwardly projecting space immediately below and in register with the spring tab 54a. Each of the cylinders in a particular constmction of the dispenser 40 can be similarly secured once the cybnders are telescoped. However, alignment of the locking mechanism 54 of each cybnder is not critical to the invention nor to the stmctural integrity of the dispenser 40. The presently preferred inside/outside diameters of the cybnders in the three telescoping cylinder embodiment of FIGS. 1-8 are (with ± 0.005 inch tolerances) as foUows: for the inner cylinder are 0.365/0.414 inches, for the first intermediate cybnder are 0.418/0.448 inches, and for the second intermediate cylinder are .452/0.482 inches. The presently preferred dimensions of bgating bands 50a, 50b, and 50c in the unstretched condition are as follows: 0J875 inch outside diameter, 0.0625 inch inside diameter, and 0.0625 inch axial length. When positioned on or about the distal portion of the sbding cybnders 42, 44, and 46, the bgating bands 50a, 50b, 50c are typically stretched about eight to ten times their nominal, unstretched inside diameters. As can be appreciated, the force nominaUy required to displace or deploy the bgating band 50a mounted on the inner cylinder is less than that required to displace or deploy the bgating band 50c mounted on the second intermediate cylinder. The appbcation of a suitable displacement force to the dispenser 40, regardless of the aforementioned lock mechanism 54, preferentiaUy favors the release of the bgating bands in the fobowing order: 50a, 50b, and then 50c. The dispenser 40 is inherently adapted to preferentially favor the firing of one band before another, and may further include coatings or varied surface configurations on the outside surfaces of the telescoping cybnders to further enhance a desired order of band firing, for example, from the innermost support member to the outermost support member. Either treatment functions to reduce the relative frictional forces of removing a given band 50 from the outer surface of one of the telescoping cylinders. Altematively, certain of the bands 50 can be adapted to have a relatively higher frictional seating on the outside surface of the telescoping cybnders, for example, by increasing the axial length of the band so that it contacts a greater portion of the cybnder or support member surface. The cybnders 42, 44, and 46 preferably have respective overab lengths as follows: 0.327 inches, 0.342 inches, and 0.357 inches. The outer cybnder 48 preferably has a 0.486 inch inside diameter, 0.542 inch outside diameter, and 0.406 inch axial length. The proximal cylindrical portion 68 of the cap 70 of the dispenser 40 preferably extends 0.381 proximal of the outer cybnder 48 for a friction fit to the tubular housing 32. Second Embodiment In FIGS. 9-11, a second embodiment of a bgating instmment dispenser 240 constmcted in accordance with this invention is illustrated. In this second embodiment, the lock mechanism 254 comprises axially directed spring tabs 254a, 254b, and 254c to restrain the dispensing of bgating bands 50a, 50b, and 50c, respectively. In FIG. 9, the dispenser 240 is shown in its assembled form on the housing 32 and in a fully loaded state immediately prior to placement of the bgating band 50a. In this second embodiment, the proximal controUer 36 is linked by the trip wire 78 to a release mechamsm 200 which permits the cybnders 42, 44, 46, and 48 to telescope and thereby dispense the bgating bands 50. The release mechamsm 200 is simpler in construction than the release mechanism 100 of -FIGS. 3-8. It comprises a pivot 202 which is secured to the inner cybnder 242 by a "bving hinge" 210. Living hinges are known in the art and generally comprise a resiliently flexible material hingedly linking two elements together. Preferably, the living hinge 210 is integrally formed with (for example, by an injection molding process) and disposed between the inner cybnder 242 and the pivot 202. The release mechamsm 200 also includes a pivot arm 214 hingedly connected to the pivot 202 by a hinge 216, which is also preferably a bving hinge in this embodiment. A bird's beak 220 having a camming surface 222 permits the bird's beak to fold radially inward (in a counter-clockwise direction) when it contacts the upstanding (radiaUy inwardly extending) walls 224, 226 of the first and second intermediate cylinders 244, 246, respectively, as the pivot 202 is withdrawn proximaby. FIG. 11 shows the dispenser 240 in a partiaUy activated state just prior to firing a bgating band. In operation, the complementary lock mechanism 254 and release mechanism 200 operate in the same way as the lock and release mechanism 54, 100 of the embodiment of FIGS. 3-8 to bgate a tissue 90. In particular, manipulation of the proximal controber 36 provides tension in the trip wire 78. The trip wire is anchored to the pivot 202 by a trip wire anchor 208 in an aperture or notch such that the tensioned trip wire 78 causes the pivot 202 to rotate about the bving hinge 210, the bving hinge 210 being naturally formed (nominaby biased) to rest in a state such that the beak 220 is clear of contact of the lock mechanism 254 (see FIG. 9). The locking spring tab 254a prevents axial motion of the cybnder 242 and the dispensing of bgating band 50a (see FIG. 10) when the beak 220 is in its rest state. As the pivot 202 rotates about bving hinge 210, the bird's beak 220 presses upon the spring tab 254a to cause the same to displace radiaUy outwardly. When spring tab 254a has been displaced so that the proximal end 206 of the inner cybnder 242 is clear of the tab 254a (see FIG. 11), the tensioned trip wire 78 draws the inner cylinder 242 proximally. Meanwhile, the distal end 280 of the first intermediate cybnder 244 prevents the bgating band 50a from moving proximaby with the telescoping motion of the inner cylinder 242. Continued proximal motion forces the flat surface 52a of the bgating band 50a distaUy off of the inner cybnder 242 and of the dispenser 240 onto or over the tissue 90 thereby accompbshing bgation thereof, as shown in FIG. 8 in connection with the first embodiment. The bgating bands 50b and 50c remain loaded for subsequent placement at the same (or different) location as the bgating band 50a. As previously noted, the dispenser 240 is designed to preferentially dispense the bgating band on the innermost, loaded telescoping cylinder before any other cybnder. The hinge 216 operates as a trailing link, in a similar manner as the pivot arm assembly 114, 116, 118 of the previous embodiment, to prevent multiple band firing or dispensing with a single manipulation of the proximal controUer 36. As shown in FIG. 11 , the trailing bnk enables the pivot arm to depress the spring tab 254a sufficient to clear the proximal end 206 of the inner cylinder 242, yet ensures that the beak 220 folds under (or drags behind) the pivot 202 with the proximal movement of the release mechanism 200 with each telescoping cybnder. As a result, the beak 220 engages the lock mechanism 254 of only one cybnder with each actuation of the proximal controller 36, as previously described. In FIG. 11 , the beak 220 engages the spring tab 254a of the first intermediate cybnder 244 to permit the inner cybnder 242 to telescope into the intermediate cybnder 244 and thereby dispense the bgating band 50a. This embodiment of the trailing link incorporating a bving hinge 216 rebably releases the lock mechanism 254 of the cybnder that is closest to the innermost, loaded cylinder, which in the illustration of FIG. 11 is the inner cybnder 242. Further, by the constmction of the release mechamsm 200, including the trailing linkage on the pivot arm 214, the surgeon is assured that only a single bgating ring is dispensed by dispenser 240 with a single pub of the proximal controUer 36. The resultant debvery of each bgating band 50 is substantiaUy as shown in FIG. 8; the stmctural differences from the previously described embodiment have no material impact on the operation of the dispenser 240. Third Embodiment FIG. 12 iUustrates a third embodiment of a bgating instmment dispenser 340, constmcted in accordance with this invention, in a fuUy loaded state prior to dispensing any bgating bands 50. In this embodiment, the lock mechanism comprises expanded (or perhaps inflated) toroidal bags 354 which are positioned between the telescoping cybnders to axiaUy space the cylinders by at least approximately the width of a bgating band 50. The toroidal bags 354 may be placed in an expanded state by filling with a liquid or gas (at either atmospheric or superatmospheric pressures), as appropriate for the particular body passageway being bgated (for example, air may be used to expand the toroidal bags 354 when the dispenser is used in the esophagus, whereas saline may be used when the dispenser is used in a tubal bgation procedure). Cybnders 342, 344, 346, 348 are provided with radiaUy inwardly extending waUs 362, 364, 366, 368, respectively, which are seated against the expanded toroidal bags 354. Together, the expanded toroidal bags 354 and the walls 362, 364, 366, 368 of this embodiment comprise a positive stop that restrains the cylinders from nesting or firing multiple bgation bands 50 with a single actuation of the proximal controUer 36. Because the expanded toroidal bags 354 have an axial length of approximately the same magnitude as the bgating bands 50, the expanded toroidal bags 354 not only restrain proximal motion of the cybnders, but also prevent inadvertent dispensing of more than one bgating band 50. Only when the toroidal bag 354 is permitted to change to an unexpanded state, can a cylinder move proximaUy and thereby dispense a bgating band 50. In FIG. 12A, toroidal bag 354 is shown in an unexpanded state with the inner cybnder 342 partiaUy nested in the first intermediate cybnder 344 after having dispensed the first bgating band, band 50a. A release mechanism 300 similar in constmction to the release mechamsm 200, which has previously been described in detaU, includes a beak 320 including a surface adapted to puncture a toroidal bag 354 when a pivot 302 is rotated with respect to the inner cybnder 342 about a bving hinge 310. In its nominal rest position, the beak 320 is clear of contact of the toroidal bags 354. The beak 320 is preferably connected to the pivot arm 314 by a living hinge 316 which nominaUy orients the beak 320 toward the toroidal bags 354 for puncturing same when the trip wire 78 is puUed and the pivot 302 rotates. The hinge 316 folds the beak 320 radiaUy inward (in a counter-clockwise direction) upon contact with any of the upstanding waUs 364, 366, 368 of the first intermediate, second intermediate, and outer cylinders 344, 346, 348, respectively (see FIG. 12A). In use, the complementary lock mechanism 354 and release mechamsm 300 function as do the previously described lock and release mechanisms to ensure that a single bgating band 50 is dispensed with a single actuation of the proximal controUer 36. The movement of the cylinders and the mounting of the bgating bands 50 is substantiaUy as previously described; accordingly, the foUowing discussion pertains to the specifics of the lock mechanism 354 and the release mechanism 300 as employed in this embodiment. When a surgeon manipulates the proximal controUer 36 to apply a proximal pulling force (to the left in the figure) to the trip wire 78 a pivot arm 314 is caused to rotate counter-clockwise which in turn causes the beak 320 to engage and puncture the toroidal bag 354. In FIG. 12 A, the beak 320 has punctured the toroidal bag 354a. Immediately after the toroidal bag 354a is punctured, the pulling force entrains the inner cybnder 342 proximaUy (by virtue of its attachment to the release mechanism 300) to dispense the bgating band 50a and bgate the tissue 90, as previously described. The punctured toroidal bag 354a, if not already unexpanded, is forcibly brought to an unexpanded state by the convergence in space of the inner cylinder's waU 362 and the first intermediate cylinder's waU 364. MeanwhUe, the hinge 316 causes the beak 320 to be redirected once the beak 320 contacts the waU 364 so that the puncturing surface does not face the more proximaUy located toroidal bags 354 (bags 354b and 354c in FIG. 12A). As a result, the surgeon's continued appbcation of a pulling force on the trip wire 78 does not cause additional bands to fire because the toroidal bags 354b and 354c remain in an expanded or inflated condition and thereby provide a positive stop against proximal motion of either the first or second intermediate cylinders 344, 346, and against dispensing the bands 50b or 50c. However, release of the proximal controUer 36 permits the release mechamsm 300 to return to its nominal rest position and the beak 320 to re-orient toward the toroidal bags 354 (see FIG. 12) for puncturing another bag upon a subsequent actuation of the proximal controUer 36. Fourth Embodiment With reference now to FIGS. 13-17, a fourth embodiment of a bgating instmment dispenser constructed in accordance with this invention is iUustrated. A dispenser 440 again comprises telescoping cybnders 442, 444, 446 having bgating bands 50 disposed thereon. In FIG. 13, the dispenser 440 is shown assembled onto the tubular housing 32 and in a fully loaded state immediately prior to placement of a bgating band on the tissue 90. The inner cybnder 442 includes a boss 402 having an axially directed aperture 404 therethrough for receiving the trip wire 78A. The trip wire 78A is anchored distal to the boss 402 by an anchor 408. The trip wire 78 A extends proximally through, for example, the biopsy channel 76 to the proximal end of the tubular housing 32. A pulling force appbed to the trip wire 78A draws the inner cybnder 442 proximally (to the left in the figure) when a pull wire locking mechanism 454 (described below) is released. The trip wire 78A may be rotatably mounted in the aperture 404, although this is not critical to this fourth embodiment. According to the constmction of this embodiment, the puU wire locking mechanism 454 comprises selectively removable spacers interposed axiaUy between each of the cybnders 442, 444, 446, and 448. Cybnders 442, 444, 446, and 448 have proximal waUs 462, 464, 466, 468, respectively, which preferably extend radiaUy inwardly, against which are seated the selectively removable spacers. Together, the spacers and the waUs 462, 464, 466, 468 of this embodiment comprise a positive stop which precludes the possibiUty of firing multiple bgation bands 50 with a single actuation of the proximal controUer 36. The spacers comprise puU wires 454a, 454b, and 454c which extend from the proximal end of the tubular housing 32 for manipulation by the surgeon to the dispenser 440. Preferably, the puU wires 454 are flattened at their respective distal ends to have a flattened dimension that is approximately the width of a bgating band 50, or greater (see FIG. 13A). In addition, the puU wires are preferably reshaped into an arcuate configuration, for example, into a loop, and bent so that the loop is oriented transverse to the center line of the dispenser 440, that is, so the loop generaUy traverses the diameter of one of the telescoping cybnders. In the fuUy loaded state of FIG. 13, the puU wire 454a has been formed into a loop of greater diameter than the inside diameter of the first intermediate cybnder 444 so that the flattened portion of the puU wire precludes proximal motion of the inner cybnder 442 even if a pulling force is appbed to the trip wire 78A by the proximal controUer 36. Likewise, the puU wire 454b has a distal loop of greater diameter than the inside diameter of the second intermediate cybnder 446 so that the flattened portion of the puU wire precludes proximal motion of the first intermediate cybnder 444 and the puU wire 454c has a distal loop of greater diameter than the inside diameter of the outer cybnder 448 so that the flattened portion of the puU wire precludes proximal motion of the second intermediate cylinder 446. At the proximal end of the tubular housing 32, the puU wires 454a, 454b, and 454c may be coded (for example, with different colors, labels, or both) so that the surgeon can selectively retract one of puU wires 454a, 454b, and 454c and thereafter apply a pulling force to the trip wire 78A to draw the cybnders proximaUy and dispense the bgating bands 50, as previously described. FIGS. 15 A, 15B, and 15C illustrate cross sections of various channel 76 configurations that may be provided in the tubular housing 32, or in a multUumen catheter 476 inserted therethrough. Each figure illustrates a lumen 478A for the trip wire 78A and a plurabty of lock mechanism lumens for the puU wires 454a, 454b, and 454c. In FIG. 15A, the lock mechanism lumens 480a, 480b, and 480c are respectively adapted to accommodate puU wires 454a, 454b, and 454c, as weU as their flattened portions. In FIG. 15B, is a variation in which the lock mechanism lumens 482a, 482b, and 482c are respectively adapted to accommodate pull wires 454a, 454b, and 454c of irregular cross section. FIG. 15C is similar to fig. 15B, but includes an additional lumen 486 to accommodate an additional puU wire, for example, a puU wire 454d to dispense a fourth bgation band 50d, or for a Seldinger guide wire or other catheter or catheter mounted device. In FIG. 16, puU wires 454a and 454b have been retracted and tension appbed to the trip wire 78A to successively dispense the bgating bands 50a and 50b at distinct locations on the tissue 90 to accompbsh bgation thereof. The puU wire 454c has not been retracted and therefore provides a positive stop to the telescoping motion of the cybnders 442 and 444. In particular, the puU wire 454c, being interposed between the outer cybnder 448 and the second intermediate cybnder 446, precludes further telescoping motion of the cybnders 442 and 444, and inadvertent dispensing of the bgatmg band 50c which remains mounted on the second intermediate cybnder 446. The embodiment of FIGS. 13-17 need not include the aforementioned slots 56, 60, and 62 and complementary protuberances 58, 64, and 66 to maintain stmctural integrity and bmit the travel of the cybnders 442, 444, 446, and 448. Referring now to FIG. 17, there is seen a friction membrane 488 disposed in the proximal end waU 468 of the outer cybnder 448 in the path of the trip wire 78A. The friction membrane 488 has a round, central bore 490 that is preferably just sbghtly larger in diameter than the nominal diameter of the trip wire 78A. The bore 490 is surrounded by flaps 492 adapted to deflect in response to the passage of an object through the bore 490 that is sbghtly larger than the diameter of the bore 490. The trip wire 78 A has a ribbed distal segment 494 having a cross section that is formed larger than the nominal diameter of the trip wire's 78 A proximal segment, and selected to frictionaUy passes through the bore 490 by causing the flaps 492 to deflect. By drawing the trip wire 78A through the channel 76 or catheter 476 a distance sufficient to cause the distal ribbed segment 494 to engage the flaps 492, the assembly is secured and there is bttle risk of the cylinders 442, 444, 446, and 448 separating when the dispenser 440 is used. In combination with the waUs 462, 464, 466, and 468 which seat the flattened distal end of the puU wires 454, the proximal travel of any of the sbding cybnders 442, 444, and 446 is bmited. The friction membrane 488 may be molded in the outer cybnder 448 to comprise a single element. Fifth Embodiment With reference now to Figs. 18 and 19, a fifth embodiment of a bgating instmment dispenser 540 according to this invention is illustrated. The dispenser 540 includes telescoping cylinders 542, 544, 546 having bgating bands 50 disposed thereon. In FIG. 18, the dispenser 540 is shown assembled onto the tubular housing 32 and in a fuUy loaded state. The inner cybnder 542 includes a boss 502 having an axiaUy directed aperture 504 therethrough (see FIG. 19) for receiving a keyed trip wire 78B. The trip wire 78B is anchored on the distal side of the boss 502 by an anchor 508 which may be a separate element attached to the trip wire 78B, or a deformed or reshaped portion of the trip wire 78B itself. The trip wire is mounted for axial rotation independent of the inner cylinder 542 in the aperture 404; however, the trip wire 78B is axiaUy fixed with respect to the inner cylinder 542 by the anchor 508 so that a pulling force on the trip wire 78B causes the cylinders to telescope and thereby dispense a bgating band 50. The trip wire 78B extends proximaUy through, for example, a biopsy channel 76 to the proximal end of the tubular housing 32, and has a keyed distal portion comprising flared segments 594a, 594b, and 594c that are adapted to preclude inadvertent or premature dispensing of a bgating band 50, as described next. The flared segments 594a, 594b, and 594c are separated by wire segments 596, 598 of substantiaUy the same cross section as the proximal segment of the trip wire 78B. According to the constmction of this embodiment, the outer cybnder 548 includes a boss or mounting stop 568 having a keyed aperture 590 formed therein (see FIG. 19) for receiving the keyed trip wire 78B and for conveying actuation forces to the telescoping cylinders 542, 544, 546 so that the bgating bands 50a, 50b, and 50c can be dispensed. In combination with the flared segments 594a, 594b, and 594c, the keyed aperture 590 comprises the positive stop mechanism of this embodiment. The flared segments 594a, 594b, and 594c may comprise a series of rotationaUy displaced, keyed or otherwise formed wire segments. In FIG. 18, the flared segment 594a is keyed in a generaUy vertical direction, the next flared segment 594b is keyed in a generaUy horizontal direction, that is, approximately 90° offset from segment 594a, and the flared segment 594c is keyed in a generaUy vertical direction, also approximately 90° offset from the previous segment, segment 594b. The keyed aperture 590 can be of any non-circular shape that complements the formations on the trip wire 78B to provide the aforementioned positive stop mechamsm, for example, sinusoidal, trapezoidal, rectangular, and so on. AU that is required is that the keyed aperture 590 be formed in a manner sufficient to prevent premature firing of any of the bgatmg bands 50, that is, be formed to restrain axial movement of the trip wire 78B unless the flared segment 594 just distal to the keyed aperture 590 is first rotated into abgnment with the keyed aperture 590. Along this line of reasoning, note that the positive stop mechanism is achievable with a wide variety of keyed or otherwise formed wire segments 594, and by other modifications to the trip wire 78B such as by attaching elements that selectively pass through the keyed aperture 590 when suitably rotationaUy abgned, as by soldering, welding, brazing, adhering, and the like, and by flattening or deforming the flared wire segments. In each of these forms, the positive stop mechanism results whenever the keyed segments are seriaUy positioned with differing rotational orientations, as shown in -FIG. 18. In operation, the surgeon manipulates a proximal controUer 36 to rotate the keyed trip wire 78B untU the segment 594a is abgned with the keyed aperture 590, as shown in FIG. 19. Once so abgned, the trip wire 78B can be puUed to draw the inner cybnder 542 proximaUy. The dispenser 540 is designed to first dispense the least stretched bgating band, band 50a, as the other bands are stretched around larger diameter cybnders and thereby require progressively greater displacement forces to dispense them, as previously described. The dispenser 540 may be adapted to preferentiaUy favor the firing of one band before another using coatings or varied surface configurations to reduce the relative frictional forces that otherwise oppose the dispensing of a particular band 50. With the trip wire 78B abgned as shown in FIGS. 18 and 19, it is puUed proximaUy to dispense the bgating band 50a. The trip wire 78B tows the inner cybnder 542 proximaUy untU the segment 594b abuts the keyed aperture 590, as shown in Fig. 19. At this stage, the dispenser 540 is in a partiaUy loaded state (substantiaUy as shown in FIG. 8 with respect to the relative location of the cylinders and bands only), with the inner cybnder 542 fuUy telescoped into the first intermediate cylinder 544, and the bgating bands 50b and 50c loaded on the first and second intermediate cylinders 544, 546, respectively. Because the segment 594b has its keyed portion rotationaUy offset from that of segment 594a, the segment 594b cannot pass through the keyed aperture 590, and continued pulling on the trip wire 78B does not permit additional bgating bands to be dispensed. The dispenser 540 and tubular housing 32 may now be repositioned within the patient and the segment 596 of the trip wire 78B rotated in the keyed aperture 590 until the distal segment 594b is abgned therewith. When the segment 594b is so abgned with the keyed aperture 590 (not shown), the bgating band 50b can be dispensed (as that is typicaUy the band with the next lowest frictional force opposing its displacement) by pulling on the trip wire 78B. Now, the dispenser 540 has the inner cybnder 542 fuUy telescoped into the first intermediate cybnder 544, and the first intermediate cylinder 544 fully telescoped into the second intermediate cybnder 546, and only the second intermediate cybnder 546 has a bgating band 50c loaded on it to be dispensed (compare to FIG. 15). The trip wire 78B is now positioned with the segment 594c abutting the keyed aperture 590 and is not able to pass therethrough until after the segment 598 of the trip wire 78B is rotated to abgn the flared segment 594c. FinaUy, the dispenser 540 and tubular housing 32 may be again repositioned within the patient, and the trip wire 78B can dispense the only remaining bgating band, band 50c, by pulling the abgned trip wire 78B. Conclusion In summary, several embodiments of a mult-firing bgating band dispenser apparatus that may be mounted on a conventional endoscope or other catheter are disclosed. Each embodiment provides a positive stop mechanism to ensure that only one band fires with a single actuation of the proximal controUer 36. The cylinders 42, 44, 46 (and cybnders 242, 244, 246, 342, 344, 346, 442, 444, 446, 542, 544, and 546, the "sUding cybnders") and cybnder 48 (and cylinders 248, 348, 448, and 548, the "outer cybnders") are preferably formed of substantiaUy transparent polycarbonate. When each of the sbding and outer cybnders is made of a substantiaUy transparent plastic material, a wide field of view is afforded when the bgating instmment 30 or endoscope includes conventional viewing optics. Altematively, the sbding and outer cybnders may be made of steel or other comparatively high strength, rigid material so that each cybnder can have a smaU waU thickness yet retain sufficient rigidity to resist coUapsing under the hoop stress caused by the bgating bands 50 stretched thereover. The use of stainless steel cybnders, or other relatively stiff, high strength thin material, aUows multiple cylinders to be incorporated into the dispenser structure so that additional bands 50, for example, five bands, can be dispensed without reloading or withdrawal of the instmment 30 from the patient. In its fuUy loaded state, some "tunnel vision" is to be expected due to a restriction of the field of view because the dispenser 40 (and dispensers 240, 340, 440, and 540) and the bands 50 extend beyond the distal end face 72 of tubular housing 32, or beyond the end of the conventional endoscope, and thus beyond the viewing optics. A dispensing apparatus may readUy be modified, however, so that the viewing optics extends at least partiaUy distaUy through the telescoping cylinders, thus reducing this effect. Other structures for providing the definite, telescoping motion of the sbding cybnders could be substituted for the disclosed mechanism. In addition, the lock mechamsm s (54, 254, 354, 454, and 554) of the various embodiments can readUy be interchanged for one another, or for an equivalent mechanism that prevents inadvertent firing of a bgating band by restraining axial motion of the cybnders. The embodiments shown in FIGS. 1 through 19 disclose a bgating band dispenser for a bgating instmment. The dispenser can dispense a single bgating band at a given location, or multiple bgating bands at a single location, or one or more bands at different locations. The surgeon may perform multiple bgating operations at different locations without having to withdraw the bgating instmment after each bgating band is dispensed. In general, the number of bands B that can be dispensed, provided one band is disposed on each cybnder C, is C - 1. The cybnders can be configured to accommodate additional bands by increasing one or more of the cylinder's axial length and adjusting size of the slot 56, 58, 60 for that cybnder so that the additional axial travel that would be required can be accommodated. The cybnders that support the bgating bands 50 need not be cylindrical. Support members of varying cross-sections may be provided, for example, square, rectangular, triangular, etc. Thus, a first support member may replace the inner cylinder, a second support member may replace the intermediate cybnder(s), and a fixed member may replace the outer cylinder. * The foregoing embodiments have been described with respect to certain presently preferred dimensions that provide a dispenser that is suitable for deploying bgating bands 50 on any soft tissue in conjunction with an endoscope, for example, varices in the fundal region or stomach lining, or certain sized varices or internal hemorrhoids. However, other dimensions may be more particularly suitable for bgating a particular varix, internal hemorrhoid, or internal body structure or duct, as the case may be. Accordingly, the present invention is not limited in its utility to the foregoing dimensions. Although this structure has been shown with respect to a particular bgating instmment 30, it will be apparent that dispensers 40, 240, 340, 440, and 540 constmcted in accordance the disclosed embodiments are readUy adapted for connection with a wide variety of structures including those based upon rigid or flexible endoscopic structures, as previously mentioned herein. It will also be apparent that these dispensers are rebable, readUy producible, and structuraUy sound. The use of the disclosed trailing links and keyed apertures prevents premature dispensing of the bgating bands so that the requirement for the use of over tubes or separate stoppers is not required with bgating instruments incorporating this invention. The bgating instrument is simple to use because it is merely necessary for the surgeon to position the bgating instmment and then actuate the trip wire 78. There is no need for the surgeon to sense the amount of travel required for depositing a single bgating band or a single set of bgating bands. WhUe this invention has been disclosed in terms of a particular embodiment and certain modifications, it will be apparent that many other modifications can be made to the specificaUy disclosed apparatus without departing from the invention. Therefore, it is the intent of the appended claims to cover aU such variations and modifications as come within the true spirit and scope of this invention.

Claims: What is Claimed Is: 1. A bgating band dispenser for dispensing a plurabty of elastic bgating bands onto at least one internal tissue site within a patient's body, comprising: an inner cybnder having proximal and distal portions, the inner cybnder being adapted to support at least one bgating band in a stretched condition about the distal portion thereof; an intermediate cylinder having proximal and distal portions and a distal end, the intermediate cybnder being positioned about at least the proximal portion of the inner cybnder and adapted to support at least another bgating band in a stretched condition about the distal portion thereof, the inner and intermediate cybnders comprising axiaUy sbding cybnders; an outer cybnder positioned about at least the proximal portion of the intermediate cylinder, the outer cybnder having a distal end, the sbding cybnders being axiaUy sbdably mounted with respect to the outer cybnder; a trip wire connected to the inner cybnder and extending proximaUy therefrom , the trip wire being adapted to cause an axiaUy sbding motion of the sbding cybnders during an appbcation of force to the trip wire; restraining means associated with each sbding cybnder for restraining sbding motion thereof during the appbcation of force to the trip wire; and releasing means for releasing the restraining means associated with one of the sbding cybnders upon the appbcation of the pulling force, whereby the released sbding cybnder sbdes and the distal end of one of the intermediate and outer cybnders pushes the bgating band therefrom during the appbcation of the pulling force. 2. The dispenser as in claim 1, wherein the intermediate cybnder comprises first and second intermediate cybnders, one of which is positioned about the proximal portion of the other, and wherein each of the first and second intermediate cybnders is respectively adapted to support a different one of the bgating bands in a stretched condition about the distal portion thereof. 3. The dispenser as in claim 1, wherein the restraining means comprise one of an axiaUy directed spring tab and a circumferentiaUy directed spring tab. 4. The dispenser as in claim 1, wherein the restraining means comprise a plurabty of spacers, the spacers being separately, removably disposed proximate to eac sUding cylinder. 5. The dispenser as in claim 1, wherein the restraining means comprises an expanded toroidal bag. 6. The dispenser as in claim 5, wherein the releasing means comprises: a pivot coupled to the inner cylinder; an arm coupled to the pivot and positionable to engage the expanded toroidal bag upon the appbcation of the pulling force, the arm including a surface adapted to puncture the expanded toroidal bag when positioned in contact therewith. 7. The dispenser as in claim 6, wherein the arm is hingedly coupled to the pivot for rotation relative to the pivot. 8. The dispenser as in claim 7, wherein the arm is adapted to engage the expanded toroidal bag upon the appbcation of the pulling force and rotate toward the pivot with the sbding of the inner cylinder. 9. The dispenser as in claim 1 , wherein the restraining means comprises: a keyed aperture fixedly positioned with respect to the sbding cybnders; and a keyed distal segment on the trip wire. 10. The dispenser as in claim 9 , wherein the keyed distal segment comprises a plurabty of rotationaUy offset elements. 11. The dispenser as in claim 10, wherein the rotationaUy offset elements are one of deformed in or attached to the trip wire. 12. The dispenser as in claim 10, wherein the trip wire is mounted for axial rotation in the inner cylinder, whereby the keyed distal segment is rotated with respect to the keyed aperture untU abgned. 13. The dispenser as in claim 1, wherein the releasing means comprises: a pivot having an arm, the pivot being pivotaUy coupled to the inner cybnder. 14. The dispenser as in claim 13, wherein the pivotal coupling of the pivot is by one of a pivot pin and a bving hinge. 15. The dispenser as in claim 14, wherein the pivotal coupling includes biasing means to maintain the arm in a position clear of the restraining means except when the pulling force is being appbed to the trip wire. 16. The dispenser as in claim 13, wherein the arm is positionable with respect to the inner cybnder to engage the restraining means associated with one of the sbding cylinders upon the appUcation of the pulling force. 17. The dispenser as in claim 13, wherein the arm is hingedly coupled to the pivot. 18. The dispenser as in claim 17, wherein the hinged coupling of the arm is by one of a pivot pin and a bving hinge. 19. The dispenser as in claim 18, wherein the hinged coupling includes biasing means to maintain the arm in a position to engage the restraining means upon appbcation of the pulling force to the trip wire, the force appbed by the biasing means being overcome during the sbding of the inner cybnder by the frictional forces of the engagement of the arm and the release mechamsm, whereby the engaged arm hinges toward the pivot with the sbding of the inner cybnder. 20. The dispenser as in claim 1, further comprising a hoUow tubular housing, wherein the dispenser is mounted at the distal end thereof. 21. The dispenser as in claim 20, wherein the hoUow tubular housing is one of a flexible endoscope and a rigid introducer. 22. The dispenser as in claim 20, further comprising: means secured to the trip wire and positioned at the proximal end of the tubular housing for moving the trip wire proximaUy to cause dispensing of a bgating band. 23. The dispenser as in claim 20, further comprising: means for drawing an internal tissue site within the distal portion of the inner cybnder. 24. The dispenser as in claim 1, further comprising: a tubular housing having a proximal handle end, a distal end, and a lumen therebetween, the outer cybnder being fixedly coupled to the distal end of the housing. 25. The dispenser as in claim 24, wherein the trip wire is connected at a proximal end thereof to the proximal handle end. 26. The dispenser as in claim 1, wherein the dispenser is made of one of stainless steel and polycarbonate. 27. The dispenser as in claim 1 , wherein the sbding cybnders are mounted for telescoping movement. 28. The dispenser as in claim 27, wherein adjacent telescoping sbding cylinders have inside and outside diameters chosen to have an annular gap therebetween that is insufficient to permit the bgating bands to become crimped when the sbding cybnders sbde. 29. The dispenser as in claim 1, wherein the sbding cybnders are coaxiaUy mounted. 30. The dispenser as in claim 1, wherein the intermediate cybnder is positioned in surrounding relation to at least the proximal portion of the inner cybnder and the outer cylinder is positioned in surrounding relation to at least the proximal portion of the intermediate cybnder. 31. The dispenser as in claim 1, wherein the intermediate cybnder comprises a succession of intermediate cylinders, each of which is positioned about the proximal portion of a preceding cybnder and has at least a further bgating band thereabout, the succession of cybnders being arranged so that they telescope sequentiaUy with successive appbcations of pulling forces on the puU wire to push the bgating bands from one of the preceding and inner cybnders. 32. The dispenser as in claim 1, wherein the releasing means releases the restraining means associated with another of the sbding cybnders upon a successive appbcation of the pulling force. 33. The dispenser as in claim 1, further comprising complementary apertures and protuberances formed on adjacent ones of the inner, intermediate, and outer cybnders, the apertures having predetermined lengths, the protuberances of one cybnder being received in the slots of an adjacent cybnder, whereby the travel of the sbding cyUnders is defined by the predetermined lengths of the apertures. 34. A bgating band dispenser for dispensing a plurabty of elastic bgating bands onto at least one internal tissue site within a patient's body, comprising: a first support member having proximal and distal portions, the first support member being adapted to support at least one bgating band in a stretched condition about the distal portion thereof; a second support member having proximal and distal portions and a distal end, the second support member being positioned about at least the proximal portion of the first support member and adapted to support at least another bgating band in a stretched condition about the distal portion thereof, the first and second support members comprising axiaUy sbding support members; a fixed member positioned about at least the proximal portion of the second support member, the fixed member having a distal end, the sbding support members being axiaUy slidably mounted with respect to the fixed member; a trip wire connected to the first support member and extending proximaUy therefrom, the trip wire being adapted to cause an axiaUy sbding motion of the sbding support members when puUed, whereby the distal end of one of the second support and fixed members pushes the bgating band therefrom; restraining means associated with each sUding support member for restraining sbding motion thereof during the appbcation of force to the trip wire; and releasing means for releasing the restraining means associated with one of the sbding support members upon the appbcation of the pulling force. 35. The dispenser as in claim 34, wherein the first and second support members and the fixed member are generaUy hoUow. 36. The dispenser as in claim 34, wherein the second support member comprises a succession of intermediate support members, each of which is positioned about the proximal portion of a preceding support member and has at least a further bgating band thereabout, the succession of support members being arranged so that they telescope sequentiaUy with successive appncations of pulling forces on the puU wire to push the bgating bands from one of the preceding and first support members. 37. The dispenser as in claim 34, wherein the releasing means releases the restraining means associated with another of the sbding support members upon a successive appbcation of the pulling force. 38. The dispenser as in claim 34, further comprising complementary apertures and protuberances formed on adjacent ones of the sbding support members and the fixed member, the apertures having predetermined lengths, the protuberances of one support member being received in the slots of an adjacent support member, whereby the travel of the sbding support members is defined by the predetermined lengths of the apertures. 39. The dispenser as in claim 34, wherein the restraining means comprises one of an axiaUy directed spring tab and a circumferentiaUy directed spring tab. 40. The dispenser as in claim 34, wherein the restraining means comprises: a keyed aperture fixedly positioned with respect to the sbding support members; and a keyed distal segment on the trip wire. 41. The dispenser as in claim 40, wherein the keyed distal segment comprises a plurabty of rotationaUy offset elements. 42. The dispenser as in claim 41 , wherein the rotationaUy offset elements are one of deformed in or attached to the trip wire. 43. The dispenser as in claim 41 , wherein the trip wire is mounted for axial rotation in the first support member, whereby the keyed distal segment is rotated with respect to the keyed aperture untU abgned. 44. The dispenser as in claim 34, wherein the releasing means comprises: a pivot having an arm, the pivot being pivotaUy coupled to the first support member. 45. The dispenser as in claim 44, wherein the pivotal coupling includes biasing means to maintain the arm in a position clear of the restraining means except when the pulling force is being appbed to the trip wire. 46. The dispenser as in claim 44, wherein the arm is positionable with respect to the first support member to engage the restraining means associated with one of the sbding support members upon the appbcation of the pulling force. 47. The dispenser as in claim 44, wherein the arm is hingedly coupled to the pivot. 48. The dispenser as in claim 47, wherein the hinged coupling includes biasing means to maintain the arm in a position to engage the restraining means upon appbcation of the pulling force to the trip wire, the force appbed by the biasing means being overcome during the sbding of the first support member by the frictional forces of the engagement of the arm and the release mechanism, whereby the engaged arm hinges toward the pivot with the sbding of the first support member. 49. The dispenser as in claim 34, further comprising: a tubular housing having a proximal handle end, a distal end, and a lumen therebetween, the fixed member being fixedly coupled to the distal end of the housing, the trip wire extending proximaUy through the lumen. 50. The dispenser as in claim 34, wherein adjacent sbding support members have inside and outside dimensions chosen to have a gap therebetween that is insufficient to permit the bgating bands to become crimped when the sbdmg support members sbde. 51. The dispenser as in claim 34, wherein the second support member is positioned in surrounding relation to at least the proximal portion of the first support member and the fixed member is positioned in surrounding relation to at least the proximal portion of the first support member.

Inventors: AZNOIAN HAROLD MARK, GILLETTE PAUL D, GOLDEN DONALD, LAMPORT RONALD B, RAFIEE NASSER, WATSON THOMAS E JR, AZNOIAN, HAROLD, MARK, GILLETTE, PAUL, D., GOLDEN, DONALD, LAMPORT, RONALD, B., RAFIEE, NASSER, WATSON, THOMAS, E., JR.
Applicants: AZNOIAN HAROLD MARK, BARD INC C R, GILLETTE PAUL D, GOLDEN DONALD, LAMPORT RONALD B, RAFIEE NASSER, WATSON THOMAS E JR, AZNOIAN, HAROLD, MARK, C.R. BARD, INC., GILLETTE, PAUL, D., GOLDEN, DONALD, LAMPORT, RONALD, B., RAFIEE, NASSER, WATSON, THOMAS, E., JR.
Application year: 1995
Main classification: A61B17
IPC codes: A61B17