Patent Abstract:
A ligating band dispenser comprises a substantially cylindrical first support surface capable of holding a plurality of first ligating bands. The first support surface has a first channel extending substantially axially therethrough and a plurality of first slots extending away from a distal end thereof through at least a portion of the first support surface. A plurality of increased diameter abutting portions define a plurality of segments of a pull line extending through the slots with each of the abutting portions being retained within the channel by contact with a corresponding one of the slots. Each of the segments loops around a corresponding one of the ligating bands to releasably couple the pull line to the ligating bands.

Full Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to the field of tissue ligation, and more particularly to an improved device for dispensing ligating bands.  
         BACKGROUND INFORMATION  
         [0002]    Physicians have used elastic ligating bands to treat lesions, including internal hemorrhoids and mucositis and for performing mechanical hemostasis. The object of such ligation is to position a ligating band, which is usually elastic, over the targeted lesion or blood vessel section by first stretching the band beyond its undeformed diameter and then drawing the tissue to be ligated within the band. Thereafter the band is released so that it contracts, applying inward pressure on the section of tissue caught within the band. The effect of the inward pressure applied by the band is to stop all circulation through the targeted tissue, thereby causing the tissue to die. The body then sloughs off the dead tissue and the tissue passes naturally through the body.  
           [0003]    U.S. Pat. No. 5,398,844 to Zaslavsky et al. (“the Zaslavsky patent”) and U.S. Pat. No. 5,356,416 to Chu et al. (“the Chu patent”), which are incorporated herein by reference, describe ligating band dispensing devices each including a substantially cylindrical support surface over which elastic ligating bands are stretched. The cylindrical support surface is typically attached to the distal end of an endoscope which is advanced into the body to a target area. A user then applies suction through the endoscope to draw the tissue to be ligated into the cylindrical support surface and releases a ligating band to contract around the tissue.  
           [0004]    Previous ligating band dispensers allowed a user to dispense only a single ligating band at a time. That is, after a single ligating band was dispensed, if a user wanted to ligate another portion of tissue, the user would remove the device from the patient&#39;s body, load a new ligating band on the device and reinsert the device to the desired area within the patient&#39;s body. The devices of the Zaslavsky and Chu patents allow a user to place several ligating bands at desired locations without removing the device from the patient&#39;s body to reload ligating bands. However, the Zaslavsky patent teaches the use of multiple strings to deploy the multiple bands (i.e. a separate pull string for each band), while the Chu patent teaches a ligator including multiple housing and piston segments to deploy the multiple bands.  
           [0005]    U.S. Pat. No. 5,624,453 to Ahmed shows a device in which multiple cords 103 extend from a line element 105 to engage each of a plurality of ligating bands 50. Specifically, each of the cords 103 includes a plurality of knots 109 which are located proximally of each band 50 so that, when the line 105 is drawn proximally, each of the cords 103 is drawn proximally with one knot 109 on each cord 103 being moved distally an equal distance. Each of the knots 109 is substantially equally spaced about the circumference of the adapter 102 so that the force applied via the line 105 is distributed around the circumference of each of the bands 50 and an incrementally increasing amount of slack ensures that when the distal most remaining band 50 is deployed, none of the remaining bands is moved toward the edge of the adapter 102.  
           [0006]    However, the multiple cords 103 extend distally across the field of vision of the endoscope impairing the vision of the operator. In addition, these symmetrically distributed cords 103 cause the line 105 to extend substantially centrally through the lumen of the endoscope, thereby limiting the operator&#39;s ability to use this lumen to operate other devices. Finally, as seen in FIG. 18, the cords 103 extend within the adapter 102 in a substantially cone shaped form, coming together at the connector 106. This may impede the drawing of lesion tissue into the adapter 102 under suction or, alternatively, may result in unintended deployment of the bands 50 as the tissue drawn into the adapter 102 pushes the connector 106 proximally. Finally, assembling a device as described in this patent can be very labor intensive—requiring proper placement of all of the multiple cords 103 and the corresponding slack segments with each of the cords being arranged so that the knots 109 are properly positioned with respect to the bands 50.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention is directed to a ligating band dispenser, comprising a substantially cylindrical support surface capable of holding a plurality of ligating bands, the support surface having a channel extending substantially axially therethrough, wherein a plurality of slots extend away from a distal end of the support surface through at least a portion of the support surface. The ligating band dispenser includes a pull line having a plurality of increased diameter abutting portions, each of the abutting portions having a diameter greater than a diameter of the pull line, the abutting portions defining a plurality of segments therebetween, wherein the pull line extends through the slots with each of the abutting portions being retained within the channel by contact with a corresponding one of the slots and wherein each of the segment segments loops around a corresponding one of the ligating bands.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a schematic drawing illustrating an exemplary pull string according to the present invention.  
         [0009]    [0009]FIG. 2 is a side view of an exemplary ligating band dispenser according to the present invention.  
         [0010]    [0010]FIG. 3 is a partially cut away side view of an exemplary ligating band dispenser according to the present invention having a second dispensing layer.  
         [0011]    [0011]FIG. 4 is a side view of another exemplary ligating band dispenser according to the present invention having an alternate arrangement of the pull string and the ligating bands.  
         [0012]    [0012]FIG. 5 is a side view of an exemplary ligating band dispenser according to the present invention utilizing a second exemplary pull string arrangement.  
         [0013]    [0013]FIG. 6 is a partially cut away side view of another exemplary ligating band dispenser utilizing the pull string arrangement of FIG. 5.  
         [0014]    [0014]FIG. 7 is a side view of an exemplary ligating band dispenser according to the present invention having a plurality of grooves on an external face.  
         [0015]    [0015]FIG. 8 is an end view of the ligating band dispenser of FIG. 7.  
         [0016]    [0016]FIG. 9 in an end view of an exemplary embodiment of a two-layer ligating band dispenser according to the present invention having a plurality of grooves on the external faces.  
         [0017]    [0017]FIG. 10 is a side view of an exemplary ligating band dispenser according to the present invention utilizing a third exemplary pull string arrangement.  
         [0018]    [0018]FIG. 11 is a side view of an exemplary ligating band dispenser according to the present invention utilizing a fourth exemplary pull string arrangement.  
         [0019]    [0019]FIG. 12 is a side view of an exemplary ligating band dispenser according to the present invention utilizing a fifth exemplary pull string arrangement.  
         [0020]    [0020]FIG. 13 is a side view of an exemplary ligating band dispenser according to the present invention utilizing a sixth exemplary pull string arrangement.  
         [0021]    [0021]FIG. 14 is a cross-sectional view of an exemplary ligating band dispenser including a guide ring for a pull string.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]    [0022]FIG. 1 shows a schematic view of a pull string  801  according to the present invention. Pull string  801  includes, for example, a plurality of knots  501 - 507  arranged along its length, the knots being separated by a plurality of string segments  401 - 406 . It can be understood that many different elements could take the place of and perform the function of knots  501 - 507 . For example, solid objects could be glued, clamped, or otherwise fixed to the pull string  801 . Alternatively (or in addition), a liquid could be applied to points on the string, the liquid beading and then hardening into a solid. Other variations are possible. For purposes of clarity, the description below employs only the term “knot,” but that term is intended to include those embodiments described above as well as other suitable embodiments. It should thus not be construed as a limitation on the present invention.  
         [0023]    [0023]FIG. 2 shows an embodiment of a ligating band dispenser including the pull string of FIG. 1. The ligating band dispenser includes, for example, a substantially cylindrical housing having a distal support surface  100  and an adaptor  101  designed to couple the ligating band dispenser to an endoscope or other suitable device (not shown). While being substantially cylindrical, the housing may have features not shown in the drawings such as a slight taper towards the distal end (the distal end being located to the right in the Figures). The ligating band dispenser includes, for example, a substantially cylindrical channel  111  (not shown on the side views) extending therethrough. Support surface  100  includes, for example, a plurality of slots  301 - 306 , which are smaller, for example, than the knots  501 - 506 . FIG. 2 illustrates a ligating band dispenser holding, for example, six ligating bands  201 - 206 , but the ligating device may include any suitable number of bands.  
         [0024]    The ligating band dispenser may also include, for example, a substantially cylindrical casing  103  attached to the ligating band dispenser, for example, at or near the proximal end of the distal support surface  100 . Casing  103  may cover the distal support surface  100  to ease insertion of the device and to ensure that bands  201 - 206  remain in place while the device travels through the body. As can be seen from FIG. 2, casing  103  may extend further distally than support surface  100 . Casing  103  may also include, for example, an outlet hole  105  near its distal end so that pull string  801  may be drawn beyond support surface  100 , outside casing  103  and away from the lesion and bands  201 - 206 . Further, casing  103  may include an inlet hole  107  near its proximal end so that pull string  801  may be threaded, for example, into adaptor  101  and through the endoscope to the operator.  
         [0025]    The arrangement of bands  201 - 206  and pull string  801  begins, for example, with the proximal-most band  201  (that is, the band appearing furthest to the left of FIG. 2). Knot  501  is placed and retained, for example, behind slot  301 . The term “behind” in this context designates a position within channel  111 . As shown schematically in the Figures, slots  301 - 306  may be shaped, for example, to accommodate knots  501 - 507  in a position behind slots  301 - 306  and to retain knots  501 - 507  in place. With knot  501  retained in place, the pull string  801  may be threaded through slot  301 , so that pull string  801  is outside the ligating band dispenser, and extended proximally along the distal support surface  100 . Band  201  is then stretched over support surface  100  and placed, for example, over pull string  801  near the proximal end of support surface  100 . Once band  201  is in place, the pull string  801  may, for example, be looped back over band  201 . Pull string  801  is then threaded, for example, down through slot  301  and back up through slot  302 . In this manner, knot  502  is retained, for example, between slots  301  and  302  (e.g. behind slot  302 ). Therefore, as shown in the exemplary arrangement of FIG. 2, string segment  401  is wrapped around band  201 , with any slack portion  601  of string segment  401  resting, for example, along the distal support surface  100  proximal to band  201 . Slack portion  601  may, of course, be longer or shorter than pictured in FIG. 2 and other Figures.  
         [0026]    With knot  502  retained, for example, behind slot  302 , pull string  801  can again be extended proximally along the support surface  100 . Band  202  may then be stretched over the support surface  100  and placed, for example, just distal of band  201 . For purposes of clarity, FIG. 2 illustrates some distance between the bands  201 - 206 . Bands  201 - 206 , however, may contact each other if desired. Once band  202  is in place, pull string  801  may be looped over band  202  and threaded through slots  302  and  303  so that knot  503  is retained behind slot  303 . The slack portion  602  of string segment  402  (the portion of pull string  801  looped around band  202 ) may extend proximally over the support surface  100  and be tucked under band  201 .  
         [0027]    In the same manner, pull string  801  may again be extended proximally over support surface  100 . Band  203  may then be placed over pull string  801  and support surface  100 , and pull string  801  may be looped back over band  203  and wound through the appropriate slots. This process may continue until remaining bands  604 - 606  are arranged in the same manner. Specifically, each band  604 - 606  is placed, for example, distally of the previous bands, with the corresponding knot  504 - 506  retained behind a corresponding slot  304 - 306 . Knot  507  may also be retained, for example, behind slot  306 , thereby ensuring that pull string  801  does not migrate distally. It may be noted that, when referring to pull string  801 , “distally” refers to a direction along pull string  801  itself away from the operator, without reference to “distal” or “proximal” portions of the support surface  100 .  
         [0028]    As shown in FIG. 2, the slack portions  603 - 606  of string segments  403 - 406  may be extended proximally over the support housing and, for example, over any proximal bands except band  201 . Slack portions  603 - 606  may then, for example, be tucked under band  201 . It will understood that as each band  601 - 606  is placed on support surface  100 , the corresponding slack increases in each case unless string segments  401 - 406  decrease in length. While string segments  401 - 406  of decreasing length may be employed, in an exemplary embodiment string segments  401 - 406  are equal or substantially equal in length. In this exemplary embodiment, pull string  801  may then be drawn by a spooler (not shown), which may take up the same amount of thread with rotation, for example the amount of thread required to deploy one of bands  201 - 206 .  
         [0029]    To deploy bands  201 - 206 , the ligating band dispenser is fixed, for example, to the end of an endoscope (not shown), inserted into the body, and maneuvered to the desired location. Once the ligating device reaches the desired location, suction, for example, is applied to the lesion as known in the art so that the lesion is drawn, for example, into channel  111 . The operator may then draw pull string  801  proximally (or cause pull string  801  to be so drawn), so that string segment  401  arranged around band  206  is drawn, for example, through the outlet hole  105  and proximally to the operator. Pull string  801  thus takes up the slack portion  606  and begins to urge band  206  toward the distal end of support surface  100 . Because knot  506  is retained behind slot  306 , the portion of the pull string  801  arranged around bands  201 - 205  is not drawn toward the operator, and bands  201 - 205  remain in place.  
         [0030]    Upon reaching the distal end of the support surface  100 , band  206  will deploy to ligate the tissue drawn into the channel  111 . The deployment may be facilitated, for example, by a taper or bevel of the distal end of support surface  100  (not shown). With the band deployed, knot  506  is freed from slot  306 . When the pull string  801  is further drawn to the operator, knot  506  will exit, for example, the outlet hole  105 , allowing band  205  to be deployed in a manner described above. This process may continue with an operator ligating successive portions of tissue with each of the bands  202 - 206  until all of the bands  202 - 206  have been deployed.  
         [0031]    When the ligating band dispenser is fixed to the distal end of an endoscope, the support surface  100  is preferably oriented so that the point where the string  801  extends from the distal rim of the support surface  100  is as close as possible to the lumen of the endoscope through which the string  801  extends back to the operator. This ensures that the string  801  does not interfere with either the field of vision or the drawing of tissue into the channel  111 .  
         [0032]    [0032]FIG. 3 illustrates a second exemplary embodiment of a ligating band dispenser according to the present invention. This second exemplary embodiment includes a second substantially cylindrical support layer  100   a  disposed, for example, within support layer  100 . Second support layer  100   a  could also be disposed outside support layer  100 , for example between support layer  100  and outer casing  103 . FIG. 3 also shows support layer  100  extending, for example, further distally than second support layer  100   a , but this configuration may also be reversed. Second support layer  100   a  contains, for example, additional slots (represented by slot  301   a ), which have the same configuration, for example, as slots  301 - 306 . Second support layer  100   a  allows the ligating device to hold a greater number of bands without unsuitably extending the length of the ligating band dispenser.  
         [0033]    Additional bands (not shown) may be arranged on second support layer  100   a , for example, in the same manner as bands  201 - 206  are arranged on support layer  100 . Pull string  801  may include additional knots to deploy the additional bands (represented by knot  501   a ). These additional bands may, for example, be placed on the ligating band dispenser prior to bands  201 - 206 . Bands  201 - 206  may then be arranged as described above. In this manner, band  206  will, for example, be deployed first, followed by bands  201 - 205  in descending order. After bands  201 - 206  are deployed, the additional knots will deploy the additional bands, for example one at a time as described above, until all bands are deployed.  
         [0034]    [0034]FIGS. 4 and 5 illustrate an alternative arrangement of the bands and pull string  801 . The dispenser of FIG. 4 deploys, for example, three bands  201 - 203 . Accordingly, pull string  801  includes, for example, only four knots  501 - 504 , separated by three string segments  401 - 403 . The dispenser, however, still includes, for example, six slots  301 - 306 . To arrange bands  201 - 203 , knot  501  and knot  502  are placed and retained, for example, behind slots  301  and  303 , respectively. String segment  401 , which forms a loop with knots  501  and  502  retained, is extended proximally and placed against the external face of the support surface  100 . Band  201  may then be stretched over support surface  100  and placed over string segment  401 . With band  201  in place, string segment  401  may be folded, for example, back over band  201  and looped between slots  501  and  502 , as shown in FIG. 5. This arrangement forms two loops  401   a  and  401   b  around band  201 , which will both urge band  201  distally when the pull string  801  is drawn towards the operator.  
         [0035]    Two slack portions  601  and  602  of loops  401   a  and  401   b  are also formed. These may lay proximally against the external face of the support surface  100 , and may, for example, be of equal length. Alternatively, slack portion  602  may be pulled proximally, thereby extending slack portion  602  and decreasing slack portion  601  until slack portion  601  is minimized (i.e. until loop  401  a has no slack portion  601 ). In this manner, when band  201  is deployed, all the slack portions  601  and  602  will be taken up before either loop  401   a  or loop  401   b  applies a force to band  201 .  
         [0036]    Once band  201  is placed on the support surface  100 , the pull string  801  may be threaded up slot  303  and back down slot  304 , and knot  503  may be retained, for example, behind slot  305 . String segment  402  is extended, for example, proximally along the external face of the support surface  100 , and band  202  is then placed over string segment  402 . With band  202  in place, string segment  402  may be folded back over band  202  and looped around slots  503  and  504 . This creates loops  402   a  and  402   b  and slack portions  603  and  604 , which may be arranged as described above. Slack portion  603 , slack portion  604 , or both may be tucked, for example, under band  201 .  
         [0037]    Band  203  may be similarly placed on the support surface  100 . Knot  504  may be retained behind slot  306  to prevent, for example, distal migration of the pull string  801 . In addition, slack portion  605 , slack portion  606 , or both may each be tucked, for example, under band  201 ,  202 , or both.  
         [0038]    Note that outer casing  103 , while not shown in FIGS. 4 and 5, may be included in this exemplary embodiment. Other elements not specifically described in conjunction with this particular exemplary embodiment may also be included. It can be understood that this is generally true for each exemplary embodiment described herein: for purposes of clarity, certain elements shown in one pictured embodiment may not appear in other pictured embodiments, but these elements may be included when not shown if desired.  
         [0039]    [0039]FIG. 6 illustrates an exemplary ligating band dispenser with the band/pull line arrangement of FIGS. 4 and 5, having, for example, a second support layer  100   a . The second support layer  100   a  shown in FIG. 6 may have, for example, the same structure as the second support layer of FIG. 3. Likewise, the arrangement of the second support layer  100   a  of FIG. 6 is analogous to the arrangement of the second support layer of FIG. 3. Specifically, additional bands (not shown) may be placed on second support layer  100   a  using, for example, the arrangement described above with respect to the embodiment of FIGS. 4 and 5. Once the additional bands have been loaded, bands  201 - 203  may be loaded, for example, as described with respect to the embodiment of FIGS. 4 and 5. In use, band  203  will, for example, be deployed first, followed by bands  202  and  201 . The additional bands may then be deployed, with the distal-most additional band being deployed first, for example, followed by the remaining additional bands.  
         [0040]    [0040]FIGS. 7 and 8 illustrate another exemplary embodiment of a ligating band dispenser according to the present invention, the ligating band dispenser including a plurality of axially-running grooves  109  formed on the external face of support surface  100 . Grooves  109 , which reduce friction between bands  201 - 206  (not shown) and support surface  100 , are formed, for example, around the entire circumference of support surface  100 . In addition, slots  301 - 306  may each be aligned, for example, along the center of one of grooves  109 .  
         [0041]    [0041]FIG. 9 shows an end view of a ligating band dispenser having grooves  109  of FIGS. 7 and 8. The exemplary embodiment of FIG. 9 includes a second support surface  100   a . As with the embodiment of FIGS. 7 and 8, slots  301 - 306 , as well as slots  301   a - 306   a  of support surface  100   a , may be aligned, for example, with grooves  109 . Moreover, slots  301 - 306  may, as a group, be circumferentially offset from slots  301   a - 306   a . This offset allows the pull wire  801 , for example, to traverse the slots  301 - 306 ,  301   a - 306   a  without excessive circumferential motion. In addition, the relatively small distance between slots  306  and  301   a  eliminates the possibility of the pull string  801  not having sufficient length to loop around the bands associated with slots  306  and  301  a.  
         [0042]    FIGS.  10 - 13  illustrate further exemplary embodiments of a ligating band dispenser according to the present invention. The embodiments shown in FIGS.  10 - 13  may deploy, for example, six bands  201 - 206 , but a greater of lesser number of bands may be included. In these embodiments, support surface  100  does not, for example, include any of slots  301 - 306  to retain knots  501 - 506 . Instead, knots  501 - 506  are actively employed, for example, to urge bands  201 - 206  towards the distal end of support surface  100  for deployment.  
         [0043]    In the embodiment of FIG. 10, in order to arrange bands  201 - 206  and pull string  801 , knot  501  of pull string  801  is arranged, for example, on the external face of support surface  100 , with pull string  801  extending from knot  501  distally along support surface  100 . As shown in FIG. 10, knot  501  is disposed, for example, at the extreme distal end of pull string  801 . Band  201  may then be stretched over support surface  100  and pull string  801 , and placed over pull string  801  just distal of knot  501 . Pull string  801  is then wound, for example, around support surface  100 , for example clockwise when viewed from the distal end of the ligating band dispenser, so that knot  501  rests distal of band  201 . The length of string segments  401 - 405  may be such that the pull string  801  winds, for example, approximately once around support surface  100  before the next knot (in this case, knot  502 ) rests against support surface  100 .  
         [0044]    Once knot  502  rests against support surface  100 , band  202  may be stretched over support surface  100  and placed over pull string  801  just distal of knot  502 . Again, pull string  801  may be wound, for example, around support surface  100  until knot  503  rests against support surface  100 , at which point band  203  may be placed over pull string  801  just distal of knot  503 . This process may continue until all bands  201 - 206  are arranged on the support surface  100 .  
         [0045]    To deploy bands  201 - 206 , the ligating band dispenser may be placed over a lesion as described above and the lesion may be drawn into the distal end of the ligating band dispenser as known in the art. Once in place, pull string  801  may be drawn, for example, proximally through the endoscope (not shown) towards an operator. As pull string  801  is drawn proximally, knot  506  will be drawn distally along support surface  100 , contacting band  206  and pulling band  206  towards the distal end of support surface  100  and eventually deploying band  206 . As knot  506  is pulled, pull string  801  unwinds, for example, around support surface  100 , taking up any slack in pull string  801 . After band  206  is deployed and any slack taken up (which may be accomplished, for example, with one turn of a spool taking up pull string  801 ), the ligating band dispenser is ready to deploy band  205 .  
         [0046]    As described above, when the ligating band dispenser is fixed to the distal end of an endoscope, the support surface  100  is preferably oriented so that the point where the string  801  extends from the distal rim of the support surface  100  is as close as possible to the lumen of the endoscope through which the string  801  extends back to the operator. This ensures that the string  801  does not interfere with either the field of vision or the drawing of tissue into the channel  111 . This also allows the operator to employ the lumen to introduce other devices to the distal end of the endoscope.  
         [0047]    [0047]FIG. 11 illustrates another exemplary embodiment of a ligating band dispenser having an arrangement similar to the dispenser of FIG. 10. In the embodiment shown in FIG. 11, however, a plurality of knots may be employed between each pair of bands  201 - 206 . For example, knot  506  of FIG. 10 corresponds to knots  506   a - 506   d  of FIG. 11. These additional knots ensure that even if one of knots  506   a - 506   d  (e.g. knot  506   a  in FIG. 11) slips under band  206 , band  206  will not be stranded on support surface  100 . Of course, more or less than four knots may be used. In addition, although FIG. 11 shows only one knot behind band  201 , additional knots may be included behind band  201  as well.  
         [0048]    [0048]FIGS. 12 and 13 illustrate alternative arrangements of string segments  401 - 405 , which essentially form slack between knots  501 - 506 . In the arrangement of FIG. 12, string segments  401 - 405  are, for example, looped and arranged proximally along support surface  100 . These may be tucked, for example, under any bands proximal to the corresponding knot, tucked under all such bands, or lain over top of such bands. In the arrangement of FIG. 13, string segments  401 - 405  are wound, for example, around support surface  100  as in FIG. 10. In the arrangement of FIG. 13, however, the direction of winding changes for each consecutive string segment  401 - 405 , creating a “zig-zag” path of the pull string  801 .  
         [0049]    [0049]FIG. 14 illustrates a further exemplary feature of a ligating band dispenser according to the present invention, a guide ring  115 . To prevent any precession of the pull string  801  around the support surface  100 , pull string  801  may be threaded, for example, through guide ring  115 . Guide ring  115  may be disposed, for example, on the internal face of support surface  100  (i.e. within channel  111 ). Guide ring  115  may, of course, be present in any of the embodiments described above.  
         [0050]    The present invention has been described with respect to several exemplary embodiments. There are many modifications of the disclosed embodiments which will be apparent to those of skill in the art. It is understood that these modifications are within the teaching of the present invention which is to be limited only by the claims.

Technology Classification (CPC): 0