Balloon actuated ligating band dispenser

A ligating band dispenser includes a cylindrical inner sleeve and at least a partially encompassing balloon, where the inner sleeve supports one or more expanded ligating bands external to the balloon. This ligating band dispenser allows the introduction of a pressurized fluid between the inner sleeve and the balloon, proximal to a distal-most, stored ligating band, to effect the distal displacement and dispensing of one or more stored ligating bands.

BACKGROUND OF THE INVENTION
 Ligation is a medical procedure in which, for example, an elastic ligating
 band, is placed about tissue to prevent fluid flow therethrough. Where a
 ligating band is placed about, for example, a ballooning varix, polyp,
 hemorrhoid, or pre-cancerous lesion, a contracted ligating band induces
 fusion and healing in the base tissue and subjects the ligated tissue to
 necrosis. The necrotic tissue eventually separates from the surrounding
 tissue and passes into the human system. Alternatively, ligation may also
 be used for purposes of sterilization, wherein a ligating band may be
 placed over a folded loop portion of a Fallopian tube or a vas deferens to
 prevent the passage of internal reproductive fluids.
 Means for delivering ligating bands, or ligating band dispensers, take
 various forms. One such form is a dedicated ligating band dispenser
 instrument which has a dispensing portion at a distal end, an actuating
 mechanism at a proximal end, and a typically rigid shaft therebetween.
 These instruments are useful for ligating tissue in which the user has
 access to the tissue to be ligated, e.g., tissue exposed through an
 invasive surgical procedure.
 In contrast, ligating band dispensers may be positioned on the distal tip
 of an endoscope or a laparoscope. An endoscope is a conventional medical
 device used for viewing, exploring, and delivering therapies to internal
 regions of a patient. A laparoscope is a specialized endoscope for viewing
 a patient's peritoneal cavity. Unlike dedicated ligating band dispensing
 instruments, an endoscope allows minimally invasive exploration of regions
 which would otherwise require more significant surgical procedures.
 FIGS. 1 and 2 illustrate a conventional endoscope. Endoscope 10 has a
 control portion 12 and an insertion portion 14 terminating at insertion
 tip 16. Insertion portion 14 is of such a length to permit access to
 internal regions of a patient.
 FIG. 2 illustrates the face of insertion tip 16. A number of channels
 extend from the control portion 12 to the insertion tip 16, where the
 channels terminate in functional outlets 18-26. For the purposes of this
 example, outlet 18 is a light source; outlet 20 is a wide-field image
 sensing device, which transmits a video or fiber optic signal to a coupled
 monitor or eyepiece (not shown) at control portion 12; outlet 22 enables
 the delivery of a stream of water or air for clearing the image receiving
 device or flushing an internal bodily region; and outlet 24 is an outlet
 to a working (or biopsy) channel. Inlet 28 of the working channel can be
 coupled to a suction device or a lavage fluid source (not shown) or can
 receive various medical instrumentation (not shown) for passage through
 the working channel and outlet 24. Optional outlet 26, for larger diameter
 endoscopes, is an outlet for a second working channel. A second working
 channel allows additional operations in a manner consistent with the
 working channel described above.
 For a ligation procedure, a ligating band dispenser, mounted on insertion
 tip 16 of a hosting endoscope 10, is inserted into a patient, for example,
 through the mouth, to observe certain internal regions. A user navigates
 the insertion tip 16 in accordance with images produced by the
 image-sensing device of outlet 20. Once tissue has been targeted for
 ligation, the distal end of the dispenser is positioned adjacent to the
 targeted tissue. The user applies a vacuum to the appropriate outlet of
 insertion tip 16 (e.g., outlet 24), or passes instrumentation (e.g.,
 forceps) through the work channel and outlet 24, to draw the targeted
 tissue into a volume defined by the inner periphery of the dispenser.
 The user then dispenses a ligating band (two dispensers and their
 dispensing mechanisms are discussed in greater detail below). Upon
 dispensing a ligating band, the dispensed ligating band attempts to assume
 its non-expanded dimensions. As the subject tissue is positioned within
 the inner periphery of the ligating band, constriction of the band
 effectively ligates the subject tissue. The applied suction is ceased, and
 the insertion tip 16 is moved away from the ligated tissue and further
 exploration may be undertaken, if necessary.
 Conventional endoscope ligating band dispensers commonly employ dispensing
 mechanisms which unnecessarily complicate a ligating procedure. Two
 examples of conventional mechanisms include a dispenser having a plurality
 of draw strings 1002 which are individually coupled to each of the stored
 ligating bands 1000 (FIG. 3), and a dispenser having a mechanically
 actuated housing which engages and requires movement of all stored
 ligating bands 1000 for each dispensing operation (FIG. 4).
 In reference to FIG. 3, draw strings 1002 extend from each ligating band
 1000 and around the distal end of the dispenser before extending
 proximally through the work channel of a receiving endoscope 10.
 Application of a proximally-directed force to a single draw string 1002
 effects distal movement and dispensing of a coupled ligating band 1000.
 As shown, each ligating band 1000 must be individually and properly coupled
 to at least one draw string 1002 to allow band control. As the number of
 stored ligating bands 1000 increase, the number of draw strings 1002, and
 the criticality of their placement, increases. The draw strings 1002 must
 be optimally positioned to ensure reliable dispensing of a distal-most
 ligating band, to avoid obstruction of the image sensing device of the
 hosting endoscope, and to avoid filling the volume defined by the
 dispenser and effectively decreasing the tissue capacity of the dispenser.
 Understandably, the construction of this dispenser requires considerable
 care and is necessarily labor intensive.
 Referring to FIG. 4, another conventional dispenser example includes a
 mechanically actuated housing having a movable inner element 1008 and a
 fixed outer element 1010. Outer element 1010 carries a plurality of
 expanded ligating bands 1000, excepting the distal-most ligating band
 1000a, which is carried by inner element 1008. For dispensing ligating
 band 1000a, element 1008 is drawn proximally, causing the distal-most
 ligating band 1000a to be released when inner element 1008 is pulled
 within outer element 1010. During such movement, the remaining ligating
 bands 1000 are displaced by shoulders 1012 so that when inner element 1008
 returns distally, ligating bands 1000 are distally advanced.
 This dispenser requires an applied dispensing force having a magnitude
 sufficient to not only dispense a single ligating band but also distally
 displace the remaining stored ligating bands in preparation for a next
 ligation. As the number of stored ligating bands increase, the force
 necessary to move the ligating bands as a group also increases.
 Consequently, a user may experience some level of awkwardness during a
 procedure due to the force which may be necessary to dispense one or more
 ligating bands. Of further concern, this dispenser requires a number of
 working components to effect the dispensing of a ligating band, thus
 likely increasing the costs of the dispenser (i.e., assembly and
 materials) and functionally increasing the opportunity for a device
 malfunction.
 Consequently, a need exists for a simple ligating band dispenser which
 offers safe, reliable, cost effective delivery of multiple ligating bands.
 SUMMARY OF THE INVENTION
 The present invention is directed to a ligating band dispenser. According
 to one aspect of the present invention, a ligating band dispenser is
 provided with an inner member and a flexible member receiving and at least
 partially encompassing the inner member. The relative positioning of the
 inner member to the flexible member defines a space therebetween. The
 dispenser further includes at least one fluid lumen which has an outlet in
 fluid communication with the space.
 Accordingly to another aspect of the present invention, the above dispenser
 includes a valve mechanism. The valve mechanism enables the selective
 distribution of pressurized fluid, delivered through the at least one
 fluid lumen, to substantially discrete portions of the space defined by
 the flexible member and the inner member.
 In operation, a ligating procedure utilizing such a dispenser would
 generally include at least positioning a ligating band dispenser of the
 above description on a distal end of an insertion portion of an endoscope.
 The ligating band dispenser should support at least one ligating band, and
 its at least one fluid lumen should be in fluid communication with a
 pressurized fluid source. The insertion portion, including the dispenser,
 is then inserted into a patient and navigated to a desired tissue site.
 Adjacent to the tissue site, tissue which is to be ligated is drawn within
 a volume defined by the dispenser. Pressurized fluid is delivered from the
 source to the at least one lumen to dispense a ligating band.
 An object of the present invention is to provide a ligating band dispenser
 having simple, accurate functionality to independently and sequentially
 dispense one or more ligating bands.
 Another object of the present invention is to provide a ligating band
 dispenser having a minimal number of working components to effect the
 dispensing of a ligating band.
 Another object of the present invention is to provide a ligating band
 dispenser which dispenses a stored ligating band through controlling
 delivery of a pressurized fluid.
 Other objects and advantages of the present invention will be apparent to
 those of ordinary skill in the art having reference to the following
 specification together with the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 FIG. 5 illustrates ligating band dispenser 200. Dispenser 200 generally
 includes sleeve 202 and an at least partially encompassing thin flexible,
 fluid-impermeable balloon positioned about a distal end of sleeve 202. The
 proximal end of balloon (or membrane) 204 is secured to sleeve 202, where
 a hermetic seal 206 is established between sleeve 202 and balloon 204.
 Where balloon 204 is largely cylindrical, a proximal, circumferential seal
 206 is formed. Alternatively, where balloon 204 extends only about some
 arcuate portion of sleeve 202, seal 206 should preferably be formed along
 all but the distal edge of the balloon 204, or balloon 204 may be a
 continuous member which overlaps itself for the arcuate portion of sleeve
 202 (FIG. 11) and, if desired, permits sealing only along its proximal
 end. Seal 206 may be established through bonding sleeve 202 to balloon 204
 and/or placing a band (FIGS. 7b and 8b) about balloon 204 to tightly
 secure balloon 204 to sleeve 202.
 In a first embodiment, sleeve 202 includes fluid inlet 208. Fluid inlet 208
 receives multi-lumen tube 210 and is in fluid communication with fluid
 lumens 212a-212d. Tube 210 delivers a pressurized fluid, for example, air,
 water, or saline, to fluid lumens 212a-212d from a pressurized fluid
 source (not shown) at or about control portion 12 of a hosting endoscope
 10. For this embodiment, tube 210 runs external to insertion portion 14 of
 the hosting endoscope 10; however, a functionally equivalent pressurized
 fluid lumen may be provided by any one of the appropriate lumen of
 insertion portion 14 of an endoscope 10.
 Fluid inlet 208 individually accommodates the multiple lumens of tube 210,
 where each lumen of tube 210 is exclusively coupled to a corresponding
 lumen of fluid lumens 212a-212d. In this example, fluid lumens 212a-212d
 are formed within the walls of sleeve 202 and progressively extend
 distally from fluid inlet 208. Alternatively, an additional element (not
 shown) may be joined to the inner periphery of sleeve 202, where channels
 are formed along a surface which is joined to sleeve 202. The relationship
 between the additional element and the sleeve 202 form fluid lumens
 212a-212d. For either variation, fluid lumen 212d extends distally from
 fluid inlet 208 for a first distance, fluid lumen 212c extends distally
 beyond fluid lumen 212d, fluid lumen 212b extends distally beyond fluid
 lumen 212c, and fluid lumen 212a extends to a distal-most point. Each
 fluid lumen respectfully terminates at orifices 214a-214d, which extend
 from an outer periphery of sleeve 202 to their respective fluid lumens
 212a-212d.
 Expanded ligating bands 50 are positioned about sleeve 102 and external to
 balloon 204. Stored ligating bands 50 subdivide a space defined between
 sleeve 202 and balloon 204 into discrete chambers 216, where the
 circumferential constriction of each expanded ligating band 50 forms a
 transient seal between sleeve 202 and balloon 204. It is preferred that
 ligating bands 50 are spaced along the length of sleeve 202 so that at
 least one orifice 214x is positioned between each ligating band 50 (or
 ligating band 50 and seal 206) and is in fluid communication with each
 chamber 216.
 For a dispensing operation, a distal-most ligating band 50 may be dispensed
 through the pressurization of a chamber 216 proximal to the distal-most
 ligating band 50. As an example, and in reference to FIG. 6, pressurized
 fluid is directed through orifice 214b to pressurize that chamber 216
 immediately proximal to ligating band 50b. As pressure within chamber 216
 increases, ligating band 50b is caused to displace distally. Distal
 movement of stored ligating bands 50 may occur through rolling, sliding,
 or some combination thereof, depending on the material and geometry of
 ligating band 60 and/or the lubrication present. When ligating band 50b
 passes orifice 214a, pressurized fluid is directed through orifice 214a to
 maintain distal movement of ligating band 50b to a release position.
 As illustrated by this example, the material of balloon 204 should balance
 competing performance requirements, where balloon 204 should have a
 sufficient durometer to prevent excessive ballooning when subjected to
 pressurization, but balloon 204 must also allow the formation of a driving
 annular surface wave suitable for initiating and maintaining the distal
 movement of ligating bands 50.
 As an alternative to inlet 208 coupling each lumen of multi-lumen tube 210
 to a respective fluid lumen of lumens 212a-212d, a valve mechanism (not
 shown) may be provided to selectively direct pressurized fluid from a
 single lumen tube 210 to each lumen of lumens 212a-212d.
 FIGS. 7a and 7b illustrate a second embodiment of dispenser 200, wherein
 like elements maintain like references. For this embodiment, sleeve 202
 has only a single fluid lumen 212 having an orifice 214 positioned between
 seal 206 and a proximal-most ligating band 50d.
 Referring to FIG. 7b, to dispense a distal-most ligating band 50b, a
 pressurized fluid is introduced through orifice 214. As pressure in
 chamber 216d reaches a predetermined level (where the predetermined level
 is a function of the circumferential force applied by ligating bands 50
 and the material characteristics of balloon 204) ligating band 50d is
 caused to displace in a manner to release the transient seal established
 by ligating band 50d and allow pressurization of chamber 216c.
 Displacement of ligating band 50d is limited to that which occurs prior to
 an equalization of pressure in chamber 216c and chamber 216d. This process
 of chamber pressurization continues with the pressurization of chamber
 216b. As pressure increases in chamber 216b, ligating band 50b will
 displace, allowing the pressurized fluid to escape to atmospheric
 conditions distal to ligating band 216b. As the pressure proximal to and
 distal to ligating band 50b is imbalanced, ligating band 50b is advanced
 distally to a dispensing point.
 FIG. 10a illustrates an alternative configuration for the second
 embodiment. Specifically, a seal between sleeve 202 and insertion tip 16
 is relocated proximally, thus enabling a direct fluid lumen 212 to be
 formed in a portion of sleeve 202. As shown in FIG. 10a, fluid lumen 212
 opens into that space between balloon 204 and sleeve 202, where balloon
 204 is attached to sleeve 202 to permit fluid communication through fluid
 lumen 212 to that space between sleeve 202 and balloon 204. For the
 alternative embodiment of FIG. 11, fluid lumen 212 opens into a space
 defined by balloon 204.
 FIGS. 8a and 8b illustrate a modification of the second embodiment of
 dispenser 200. In addition to the configuration described above, dispenser
 200 includes filament 220. Filament 220 extends from the outer periphery
 of member 202 to the volume defined by member 202 through aperture 218. It
 is preferred that aperture 218 be positioned generally adjacent to orifice
 214 of fluid lumen 212. Alternatively, filament 220 may pass through fluid
 lumen 212.
 Filament 220 is a valve mechanism to direct pressurized fluid to a selected
 chamber 216x. Filament 220 originates at control portion 12 of a hosting
 endoscope 10, extends through tube 210 (or a lumen of insertion portion 14
 and aperture 218), to lie along the exterior periphery of sleeve 202 in a
 direction largely parallel to a longitudinal axis of sleeve 202. For the
 purposes of the example illustrated in FIG. 8b, filament 220 initially
 extends for distance d into chamber 216b.
 For a dispensing operation, and in further reference to FIG. 8b, a
 pressurized fluid is introduced into chamber 216d. Filament 220 directs
 the delivered pressurized fluid to chamber 216b, which is immediately
 proximal to ligating band 50b, by disrupting each seal (see FIG. 9) formed
 between sleeve 202 and balloon 204 by the circumferential constriction of
 each ligating band 50. Increasing pressure within chamber 216b effects
 distal movement of ligating band 50b to a dispensing position. Following
 dispensing of ligating band 50b, filament 220 is withdrawn proximally
 until a distal end of filament 220 is within chamber 216c.
 The effective nominal distance between chamber 216b and chamber 216c is a
 function of the expanded cross-sectional diameter of ligating band 50c
 and/or the spacing between ligating bands 50b and 50c. This effective
 nominal distance is approximately 1-2 mm. Consequently, moving filament
 220 from one chamber 216x to the next requires a high degree of precision.
 To provide a user greater control over the valve mechanism, filament 220
 may be wound about the exterior periphery of sleeve 202 in a prescribed
 pattern. As one example, FIG. 8c illustrates a looped configuration of
 filament 220 which results in filament 220 extending beneath each proximal
 ligating bands 50 two or more times. In addition to improving control over
 the valve mechanism, this configuration further increases the flow path
 around the filament 220 and thereby the pressurization response time for
 pressure equalization in each of the affected chambers 216x during a
 dispensing operation.
 As an alternative to filament 220, tube 210 may be slidably engaged by a
 portion of sleeve 202, thus allowing tube 210 to perform the same function
 as filament 220 by directly delivering pressurized fluid to a distal-most
 chamber 216x. More preferably, tube 210 may carry a movable extension of
 tube 210, which itself initially extends along sleeve 202 and may be
 retracted along sleeve 202 to sequentially dispense stored ligating bands
 50. Referring to FIG. 10b to illustrate the functionality of the movable
 extension of tube 210, the distal end of the movable extension of tube 210
 is initially positioned just proximal to a distal-most ligating band 50b.
 After ligating band 50b is dispensed, the extension of tube 210 is
 retracted proximally to a position proximal to the then distal-most
 ligating band 50c.
 For the above examples, ligating band dispenser 200 is shown to be fixed on
 an insertion tip 16 of a hosting endoscope 10. As an alternative
 embodiment, dispenser 200 may be adapted to move relative to an insertion
 tip 16 of a hosting endoscope 10 and controlled in accordance with that
 disclosed within co-pending application, Ser. No. 09/062,281, filed Apr.
 17, 1998.
 Ligating band dispenser 200 may be further used with an endoscope, as
 illustrated in the above examples, or manufactured or included as part of
 a dedicated ligating instrument (not shown).
 While the invention has been described herein relative to a number of
 particularized embodiments, it is understood that modifications of, and
 alternatives to, these embodiments, such modifications and alternatives
 realizing the advantages and benefits of this invention, will be apparent
 to those of ordinary skill in the art having reference to this
 specification and its drawings. It is contemplated that such modifications
 and alternatives are within the scope of this invention as subsequently
 claimed herein, and it is intended that the scope of this invention
 claimed herein be limited only by the broadest interpretation of the
 appended claims to which the inventors are legally entitled.