Patent Publication Number: US-10786256-B2

Title: Cap with band deployment features

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a Continuation of U.S. patent application Ser. No. 14/295,893 filed Jun. 4, 2014, now U.S. Pat. No. 10,105,143, which claims priority to U.S. Provisional Application Ser. No. 61/831,331 filed Jun. 5, 2013. The entire disclosure of the above patents/applications is expressly incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     This disclosure relates generally to medical devices. More particularly, the disclosure relates to use of a cap for deploying bands. The cap and bands may be used for endoscopic mucosal resection (EMR) procedures. 
     BACKGROUND OF THE DISCLOSURE 
     Cancerous or benign lesions of the gastro-intestinal (GI) tract often start in the mucosal layer of the stomach or intestines. With improved diagnostics and screening, such lesions are generally identified before they affect the stomach and/or the intestines. Treatments and therapies for treating lesions have involved invasive surgical resection of the affected tissue or lesion. Early identification and treatment of such lesions, through methods including local excision of the mucosa, accessed via natural orifices, may be preferred as they are less invasive. 
     An example of a less invasive technique for treating tissue defects or lesions, including conditions related to varices, chronic liver disease, hemorrhoids, and the like, is band ligation. In band ligation, the affected or target tissue is bound with a band to form a pseudo polyp, thus establishing a ligated tissue. The ligated tissue may be removed using a removal device, such as a snare. 
     For band ligation, the band is delivered into the body as part of a ligation unit or device, which is configured to be steered and positioned adjacent the target tissue. Typically, ligation units are inserted into natural body cavities or through an incision, at a distal end of an endoscope. 
     In some ligation units, ligation bands may be tightly arranged over a cap-like structure, and deployed over the target tissue. Strings or sutures may be employed to advance the bands towards a distal end of the device to release the bands from the ligation unit. In some cases, portions of the band may slide along the surface of the cap, instead of rolling along the surface of the cap. Such a situation may lead to a twisted, angular, inverted, and/or otherwise undesirable deployment of the band, causing the tissue to be held improperly. For example, the band may fail to compress the tissue appropriately when deployed, causing the formation of a necked or otherwise misshaped polyp, or causing an increase in the risk of perforating underlying tissue layers. 
     To address such conditions, surface features can be provided on the cap-like structure to engage the bands during their deployment. Such surface features may, however, limit visibility through and around the cap-like structure, depending on their characteristics. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure describes a medical device for ligating a portion of tissue in a patient&#39;s body. 
     According to an embodiment of the present disclosure, a medical device for deploying a ligation band may include a tubular body. The tubular body may include a proximal end, a distal end, a radially inner surface defining a lumen through the tubular body, and a radially outer surface. The radially outer surface may include protrusions arranged in rows extending at least partially around a proximal region of the radially outer surface. Protrusions in adjacent rows may be separated by a first distance. Surface features may extend at least partially around a distal region of the radially outer surface. Adjacent surface features may be separated by a second distance larger than the first distance. 
     According to another embodiment of the present disclosure, a medical device for deploying a ligation band may include a tubular body. The tubular body may include a proximal end, a distal end, and a radially inner surface defining a lumen through the tubular body. The radially inner surface may include at least one radially inwardly extending protrusion configured to engage an imaging device. A proximal region of the tubular body may be proximal to the at least one radially inwardly extending protrusion, and a distal region of the tubular body may be distal to the at least one radially inwardly extending protrusion. The tubular body may also include a radially outer surface. The radially outer surface may include protrusions arranged in circumferentially extending rows on the radially outer surface, in the proximal region of the tubular body. Adjacent rows may be separated by a first distance. The radially outer surface may also include grooves extending circumferentially on the radially outer surface, in the distal region of the tubular body. Adjacent grooves may be separated by a second distance larger than the first distance. 
     According to another embodiment of the present disclosure, a medical device for deploying a ligation band may include a tubular body. The tubular body may include a proximal end, a distal end, a radially inner surface defining a lumen through the tubular body, and a radially outer surface. The radially outer surface may include a distal region, a proximal region, and a plurality of radially inwardly extending grooves formed in the radially outer surface, in the proximal region. 
     Additional objects and advantages of the described embodiments will be set forth in part in the description that follows, and in part will be apparent from the description, or, may be learned by practicing the disclosure. The objects and/or advantages of the disclosure will be realized and attained by way of the elements and combinations particularly pointed out in the appended claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the described embodiments, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the present disclosure, and together with the description, serve to explain the principles of the disclosure. 
         FIG. 1A  is an isometric view of an exemplary ligation cap affixed to a distal end of a sheath, such as an endoscope, according to aspects of the present disclosure; 
         FIG. 1B  is a cross-sectional side view of the cap of  FIG. 1A ; 
         FIGS. 2A, 2B, and 2C , are cross-sectional side views depicting alternative embodiments of the cap, according to aspects of the present disclosure; 
         FIG. 3A  is an isometric view of an embodiment of a cap, according to aspects of the present disclosure; 
         FIG. 3B  is a cross-sectional side view of the cap of  FIG. 3A , according to aspects of the present disclosure; 
         FIG. 4A  is cross-sectional side view of another embodiment of a cap, according to aspects of the present disclosure; 
         FIG. 4B  is an enlarged view of microstructures, according to aspects of the present disclosure; 
         FIG. 4C  is another enlarged view of microstructures, according to aspects of the present disclosure; 
         FIG. 5A  is an isometric view of a cap, according to aspects of the present disclosure; 
         FIG. 5B  is a cross-sectional side view of the cap of  FIG. 5A , according to aspects of the present disclosure; 
         FIGS. 6A and 6B  are cross-sectional side views of caps, according to aspects of the present disclosure; 
         FIGS. 7A-7F  are cross-sectional side views of the cap of  FIG. 5A , in use, according to aspects of the present disclosure; 
         FIG. 8  is a medical device, including a cap, according to aspects of the present disclosure; 
         FIGS. 9A-9D  are cross-sectional side views showing the medical device of  FIG. 8 , in use, according to aspects of the present disclosure; and 
         FIGS. 10A-10C  are perspective views of alternative embodiments of a cap, according to aspects of the present disclosure. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. The term “distal” refers to the end farthest away from a medical professional when introducing a device in a patient. The term “proximal” refers to the end closest to the medical professional when placing a device in the patient. 
     Overview 
     Embodiments of the present disclosure relate to devices configured for ligating tissue. For example, embodiments of the disclosed device may facilitate ligation of infectious, dead, or otherwise undesired tissue, which may form conditions such as hemorrhoids, mucositis, early gastrointestinal cancer, lesions, or varices, and/or may include undesired patches of tissue disposed on, for example, the mucosal walls of the colon, esophagus, stomach, or duodenum. 
     In some embodiments, a medical device may include a cap configured for attachment to a distal end of a sheath or a suitable elongate device, such as a catheter shaft, endoscope, laparoscope, colonoscope, ureteroscope, or the like. The cap may include an outer surface, a proximal end, a distal end, and a cavity extending through the cap, between those ends. The cavity may be open at its proximal and distal ends. One or more bands may be disposed on a proximal end portion of the cap, over the outer surface. The outer surface may include one or more band deployment features between the proximal and distal ends of the cap. The one or more band deployment features may provide for a regulated or controlled rolling motion of the bands, and subsequent release of the bands from the cap. A suture may be coupled to the bands to pull the bands along the cap, and release the bands from the cap, one at a time, from the distal end of the cap onto tissue. 
     Exemplary Embodiments 
     The cap embodiments disclosed herein may be employed along with an elongate device, which may include an endoscope, to introduce and deliver the caps to a target site within a patient&#39;s body. It is contemplated, however, that the present disclosure may be used along with other introduction devices, sheaths, or systems, such as trocars, catheter sheaths, laparoscopes, colonoscopes, ureteroscopes, or the like. 
       FIG. 1A  is an exemplary ligation cap  100 , configured to be secured to a distal end  152  of an endoscope  150 . The cap  100  may include a tubular body, and may include an outer surface  102 . One or more ligation bands  104  may be positioned around a proximal end portion  106  of the cap  100 . Seven bands  104  may be accommodated around the outer surface  102 , but it should be understood that fewer or more bands  104  may be used depending on the type of procedure being performed. Towards the distal end portion  108  of the cap, a suture  110  that extends through a cavity  111  of the cap  100 , may be disposed. The suture  110  may be configured to pull at least one of the bands  104 , facilitating releasing of each of the bands  104  from the distal end portion  108  of the cap  100 . Over the outer surface  102 , grooves  112  may be disposed. The suture  110  may extend over one side of the outer surface  102 , and the grooves  112  may be disposed on an opposite side of the outer surface  102 . 
     The cap  100 , and the other ligation caps disclosed herein, may be configured to be permanently or temporarily secured to the distal end  152  of the endoscope  150 , via suitable securing mechanisms. Permanent securing mechanisms may include, for example, adhesives, welding, soldering, or the like, while temporary securing mechanisms may include snap-fit, screw-fit, luer-lock, or the like. In some instances, the cap  100  may be integral with the endoscope  150 . 
     Further, the cap  100  may be application specific, and may be relatively small enough for being appropriately inserted and navigated to reach a target site through natural body cavities or through an incision. For example, external dimensions of the cap  100  may vary from application to application. For example, if the cap  100  is anally inserted to resect internal hemorrhoids, the dimensions of the cap  100  may be considerably smaller than a similar device used in connection with treating esophageal varices. Understandably, the shape and size of a corresponding endoscope may vary as well. A plurality of differently sized or configured caps may be provided in a kit, allowing a user to select a cap from the kit based on the type of procedure to be performed. 
     Additionally, the cap  100  may be designed for multiple or single use applications. For single-use applications, for example, the cap  100  may have a temporary attachment mechanism, such as a screw-fit, and may thus be stored and disposed of in hermetically sealed and sterile packaging. On the other hand, a multiple-use device may be adapted to be sterilized, and thus, may be designed with materials able to withstand extreme temperature, chemical reactions, pressure variations, etc. For enabling a multiple use, the cap  100  may be made from high grade materials that are compliant to be fixed and removed regularly, such that a repeated use is possible. Furthermore, a multiple use cap  100  may also be permanently affixed to the endoscope  150 , and may be sterilized along with the endoscope  150  for repeated applications. 
     At the distal end portion  108 , the cap  100  may be rounded off or chamfered to facilitate band deployment. A rounded off or chamfered edge  126  at the distal end portion  108  may also make the cap  100  atraumatic, reducing likelihood of tissue damage when coming in contact with tissue during its travel to a target site. 
     In some embodiments, the cap  100  may be made from a transparent or a semi-transparent material, such that visualization through the cap  100  by an operator or a surgeon is possible. For example, the distal end  152  of the endoscope  150  may have an imaging device, such as a sensor or camera with a lens (not shown), positioned therein. For example, the imaging device may be inserted through the endoscope  150  from a proximal end portion of the endoscope  150 . The imaging device may be inserted through the endoscope  150  to a position near a proximal end portion  106  of the cap  100 . It is also contemplated that the imaging device and/or the distal end  152  of the endoscope may be inserted past the proximal end portion  106  of the cap  100  to a stop (described in more detail below), and positioned within the cavity  111  of the cap  100 . The field of view of the imaging device may include regions visible to the imaging device beyond the distal end portion  108  of the cap  100 , and regions visible to the imaging device peripherally through side walls of the cap  100 . 
     The cavity  111  may be a substantially cylindrical lumen, communicating with a lumen (not shown in  FIG. 1A , but shown in  FIG. 8 ) of the endoscope  150 , at the cap&#39;s proximal end portion  106 . Surfaces of the cap  100  that form the cavity  111  may be substantially smooth and flat. The cavity  111 , at the proximal end portion  106 , may be dimensioned to fit over or mate with the distal end  152  of the endoscope  150 . Shapes and dimensions of the cavity  111  and the endoscope  150  may correspond to each other by, for example, being complementary, enabling the cavity  111  to be operably assembled flush to the lumen (not shown) structured within the endoscope  150 . 
     It is also contemplated that surfaces of the cap  100  that form the cavity  111  may include a step (not shown) similar to a step  1006  shown in  FIG. 10A , dividing the cavity  111  into a larger diameter proximal portion and a smaller diameter distal portion. Additionally or alternatively, surfaces of the cap  100  that form the cavity  111  may include one or more protrusions (not shown), extending radially inward from the surfaces, similar to one or more protrusions  1002  shown in  FIG. 10A . The one or more protrusions may abut a structure on the endoscope  152 , such as the distal end  152  of the endoscope  150 , and/or a structure on the imaging device, acting as a stop to help a user position the endoscope  150  and/or imaging device relative to the cap  100  in a consistent and repeatable manner. For example, the one or more protrusions may abut the imaging device such that the grooves  112 , and/or bands  104  engaging the grooves  112 , may be outside of (e.g., proximal to) the field of view of the imaging device. The grooves  112  and/or bands  104  thereon may be outside of the field of view even if portions of the grooves  112  and/or bands  104  thereon may be distal to the imaging device. 
     At the distal end portion  108  of the cap  100 , the suture  110  may extend distally within the cavity  111 , bend around the distal end portion  108  of the cap  100 , and extend proximally to the bands  104 . At least a portion of the suture  110  may extend proximally through the endoscope  150 . A proximal portion of the suture  110  may extend proximally out from a proximal end  154  of the endoscope  150 , all the way till the distal end portion  108  of the cap  100 . While in operation, a predetermined proximal pull on the suture  110  may deploy one band  104  at a time from the cap  100 .  FIG. 1B  depicts the suture  110  being wrapped around the bands  104  disposed on the outer surface  102  of the cap  100 . 
     The suture  110  may wrap over each band  104  in a sequential fashion. In detail, beyond a first wrap, the suture  110  may extend back and bend over the edge  126 , before extending forth and being wrapped over the next band  104 . Similarly, all the bands  104  may be sequentially wrapped by a single suture  110 . In such an instance, a first proximal pull on the band  104  would facilitate pulling a first band  104  towards the distal end portion  108  of the cap  100 , for eventual release onto tissue. For releasing the second, third, and subsequent ligations bands  104 , the suture  110  may be pulled a second, a third, and subsequent times. Further description of the suture  110  and bands  104 , their operation, and possible alternative arrangements, are described in U.S. Pat. No. 5,913,865, which is incorporated herein by reference in its entirety. 
     The bands  104  disposed over the outer surface  102  may be resilient, formed of a material such as rubber. The bands  104  may be configured to roll over at least a portion of the outer surface  102 , when engaged by grooves  112 . The bands  104  are substantially ring-shaped elastic structures similar to rubber bands, and are configured to constrict and ligate tissue. Generally, the bands  104  may have a square cross-section that promotes turning or rolling of the band  104  over the outer surface  102 . Other cross-sectional profiles of the band  104  may be envisioned as well, and those may include rectangular, triangular, hexagonal, round, elliptical, irregular, and other suitable profiles. 
     The outer surface  102  may include two regions. A first region  122  (see  FIG. 1B ) may include deployment features, such as the grooves  112 , facilitating the rolling of the bands  104  over the outer surface  102 , instead of facilitating pure sliding of the bands  104  over the outer surface  102 . The grooves  112  may be disposed at least partially around the outer surface  102 . Further, the grooves  112  may extend only partially around a circumference of the outer surface  102  to help ensure that grooves  112  minimally obstruct a field of view of the imaging device. The grooves  112  may be widest at their centers, and may become thinner towards their ends. The widths of the grooves  112  may approach zero at their ends, forming pointed groove ends. The grooves  112  may be deepest at their centers, and may become shallower towards their ends. The depths of the grooves  112  may approach zero at their ends. The lengths, width features, and depth features of the grooves  112  may be configured to reduce obstructions to visibility through the cap  100  from the perspective of the imaging device (not shown), and the user viewing images sent by the imaging device. For example, the surfaces of the deployment features (e.g. grooves  112 , spikes or protrusions  218 ,  518 ) may be angled or positioned relevant to the imaging device to minimize any obstruction or distortion to the image detected by the imaging device. This may be achieved by aligning the planar surface of a deployment feature with the line of sight (i.e. sightline or visual axis) of the imaging device. The lengths, width features, and depth features of the grooves  112  may also be configured to generate forces on or in certain parts of the bands  104  at certain moments during deployment of the bands  104 , while not generating forces on or in other parts of the bands  104  at those moments. This selective generation of forces on the bands  104  may facilitate their rolling deployment. 
     Certain embodiments may include fewer or more of the grooves  112  than the number shown. Additionally, shapes, sizes and positioning of the grooves  112  may vary from that which is depicted. Moreover, an amount of spacing between each of the grooves within the set of grooves  112  may vary. 
     The grooves  112  may extend part of the way along the outer surface&#39;s longitudinal length  116 , beyond which a second region  124  may extend to the distal end portion  108  of the cap  100 . Such a placement of the set of grooves  112  may vary, with the set of grooves  112  ending either before, at, or after the halfway mark along the longitudinal length  116 . The second region  124  may be free of grooves  112 . 
     The first region  122  or the second region  124  may optionally include a tapered profile in which an outer diameter of the region decreases toward the distal end portion  108 . In some embodiments, the entire outer surface  102 , structured over both the regions  122  and  124 , may taper along the longitudinal length  116 , to the distal end portion  108 . The tapering profile of the cap  100  may encourage movement of the bands  104  toward the distal end portion  108 . 
       FIG. 1B  depicts a cross-sectional view of the cap  100  illustrating a side profile of the grooves  112  disposed along the outer surface&#39;s longitudinal length  116 . A triangular cross-sectional profile  114  of the grooves  112  is shown, where a leading/proximal surface of the groove  112  may incline more than a following/distal surface. Portions of the bands  104  may contact the outer surface  102  of the cap  100 , while other portions of the bands  104  may extend over the grooves  112 . As such, the grooves  112  may reduce surface contact and/or friction between the bands  104  and the outer surface  102  of the cap  100 . 
     The grooves  112  may receive portions of the bands  104  as they move along the outer surface  102 . For example, proximal and distal edges of the grooves  112  may act as teetering points for the bands  104 . The bands  104  may teeter on the edges of the grooves  112 , tilt, and then rotate into the grooves  112 . For example, corner portions of the bands  104  may tilt and then rotate into and out of the grooves  112  as the bands  104  move distally along the cap  100 . The reduced surface contact between the bands  104  and the outer surface  102 , and/or the presence of teetering points for the bands  104 , may encourage rolling of the bands  104  as they move distally along outer surface  102 . Other embodiments of the grooves  112  may be envisioned as well, and the forthcoming description includes discussion related to those embodiments. 
     Accordingly, embodiments of the cap  100  depicted in  FIGS. 2A, 2B, and 2C , include alternate forms of the grooves  112  disposed within a corresponding first region  222 . More specifically,  FIG. 2A  illustrates the cap  100  with a set of grooves  112  having a trapezoidal profile  214 , while  FIG. 2B  depicts a cap  100  having a profile  214 ′ with sharp points or edges for engaging the bands  104 . Some embodiments may include, but are not limited to, rectangular and/or irregular cross-sectional profiles. As described above, the grooves  112  may reduce surface contact between the bands  104  and the outer surface  102 , and/or provide teetering points for the bands  104  (e.g., at edges of the grooves  112 ), to encourage tilting and then rolling of the bands  104  as they move distally along the outer surface  102 . 
     Optionally, the set of grooves  112  may be replaced by or augmented with spikes, other protrusions, their combinations, and the like. Accordingly,  FIG. 2C  depicts a cross-sectional profile of the cap  100 , having a set of spikes or protrusions  218 , in place of the set of grooves  112 , disposed over the outer surface  102 . The protrusions  218  may initiate rolling of the bands  104 . The protrusions  218  may reduce surface contact between the bands  104  and the outer surface  102 , since only portions of the radially-inner surfaces of the bands  104  will contact the outer surface  102 . The protrusions  218  may act as teetering points for the bands  104 . For example, peaks of the protrusions  218  may act as teetering points for the bands  104 . As the bands  104  come into contact with the protrusions  218 , the teetering points may encourage tilting and rotating of portions of the bands  104 , into and out of gaps between the protrusions  218 . The reduced surface contact and/or teetering points may encourage rolling of bands  104  as they move distally along the outer surface  102 . 
     As discussed above, the grooves  112  and all its embodiments, when applied, may be transparent, or at least semi-transparent, enabling light to pass through those areas. Such a feature may enable an environment disposed beyond and around the distal end portion  108  of the cap  100  to be visible from within the cavity  111 , from the perspective of an imaging device (not shown) at or near the distal end  152  of the endoscope  150 . 
     Other embodiments of the frictional surface or the set of grooves  112  are also contemplated. For example, the grooves  112 , or the spikes or protrusions  218 , may be provided at an angle over the outer surface  102 . In some embodiments, a rubberized layer disposed over the outer surface  102  may provide a requisite amount of friction or traction to initiate and sustain the rolling motion of the bands  104  during deployment. Such employment of a rubberized grip may prove economical and easy to manufacture, while being equally efficient as well. Another embodiment may include the outer surface  102  being made or covered by the same material as the bands  104 . 
       FIG. 3A  illustrates an exemplary cap  300 , with the outer surface  302  having two regions, similar to the ones discussed above. Here, while the rest of the structure of the cap  300  may remain substantially similar, a corresponding outer surface  302  may include a first set of grooves  112  positioned at a proximal end portion  306 , and a second set of grooves  112 ′ positioned closer to a distal end portion  308  of the cap  300 . If the bands  104  begin to slide or slip, the grooves  112 ′ may engage the bands  104  to provide a correction factor and reduce strain in the bands  104 , and/or to encourage further rolling of the bands  104 . Further, because the grooves  112 ′ are cut into the cap  300 , they also help to minimize band strain during deployment, and the amount of force needed to move the bands during deployment. It is contemplated that grooves  112 ′, similar to grooves  112 , may provide teetering points (e.g., at edges of grooves  112 ′) for bands  104 , to encourage teetering, tilting, and rolling of the bands  104  as they move distally along the outer surface  302 . 
       FIG. 3B  illustrates a side cross-sectional view of the cap  300 , depicting the two regions, which are marked as a first region  322 , and a second region  324 . Notably, the two regions  322  and  324  may include differently configured set of grooves  112  and  112 ′. For example, the set of grooves  112  may include a triangular cross-sectional profile  114 , while the set of grooves  112 ′ may include a rectangular or a trapezoidal cross-sectional profile  214 . 
     It is also contemplated that the spacing between the most distal groove  112 ′, and the distal end portion  308  of the cap  300 , may be less than the minimum distance travelled by the band  104  during the band&#39;s 360° rolling motion. Such a structure may enable the band&#39;s release from the cap  300 , when travelling beyond the distal most groove  112 ′. It is also contemplated that a space between adjacent grooves  112 ′ may be greater than a space between adjacent grooves  112 . Additionally or alternatively, there may be fewer grooves  112 ′ than grooves  112 . Such an arrangement may facilitate visualization at the distal end portion  308  of the cap  300  when viewing through the cavity  311  from the proximal end portion  306  of the cap  300 , using the imaging device (not shown). 
     Relatively closely spaced set of grooves  112  in the first region  322  may facilitate or induce a rolling motion of the bands  104  towards the distal end portion  308 . This is because pulling the bands  104  toward the distal end portion  308  may cause the bands  104  to at least partially enter into an adjacent groove disposed in the direction of the distal end portion  308 . The pulling force may be generated by the suture  110 . The second region  324  may also facilitate the rolling motion and exit of the bands  104  at the distal end portion  308  of the cap  300 . 
       FIG. 4A  shows a cross-section of another embodiment of an exemplary cap  400  with an outer surface  402 . Here, while the rest of the structure of the cap  400  may remain substantially similar, the outer surface  402  may include a pattern, such as a micropattern  412  composed of an array of microstructures  422 . The micropattern  412  may extend along at least a portion of a longitudinal length  416  of the cap  400 . The portion of the longitudinal length  416  may include a proximal portion or a distal portion. It is also contemplated that the micropattern  412  may extend along all of the longitudinal length  416 . The micropattern  412  may be disposed circumferentially along at least a portion of a circumference of the outer surface  402 . In one embodiment, the micropattern  412  may extend around an entire circumference of the outer surface  402 . It is also contemplated that the micropattern  412  may be in the form of a circumferential band, a spiral or helix, an irregular or random form, and/or any other suitable form or combination of forms to help achieve a desired band deployment characteristic. 
     As depicted in  FIGS. 4B and 4C , the micropattern  412  may include a plurality of microstructures  422  spaced apart from each other. In FIG,  4 B, the microstructures  422  may include pillars or fibers (e.g., nanopillars or nanofibers) of circular cross-section, arranged in form of a matrix, with gaps between adjacent microstructures  422 . In  FIG. 4C , the microstructures  422  may include pillars or fibers (e.g., nanopillars or nanofibers) of square-shaped cross-section, arranged in a matrix, with a smaller gap between adjacent microstructures  422 . The microstructures  422  may also have other cross-sections, such as rectangular, elliptical, triangular, or the like. While it is contemplated that the microstructures  422  may be arranged in a the form of a grid, it is also contemplated that the microstructures  422  may be arranged in a diagonal pattern, a staggered pattern, a random or irregular pattern, and/or any other suitable pattern or combination of patterns to achieve a desired band deployment characteristic. 
     The small scale of the microstructures  422  allow the microstructures  422  to be present on the outer surface  402  of the cap  400  with little effect on visibility through the cap  400  from the perspective of the imaging device (not shown). It is contemplated that the micropatterns  412  and microstructures  422  can be formed on the outer surface  402  by molding, overmolding, extruding, chemical-etching, or machining, such as skiving, compressing material between dies, laser etching, or making by any other suitable method. 
     Based on the density and/or dimensions of the microstructures  422 , certain characteristics may be imparted to the material on which the microstructures  422  are applied. For example, applying a first micropattern of first microstructures having a first width, to a first portion of the outer surface  402 , may cause an increase in the gripping force exerted by the first portion of the outer surface  402  on the band  104 , due to the micropattern having a first microstructure density at least partially determined by the first width. Applying a second micropattern of second microstructures having a larger second width, to a second portion of the outer surface  402 , may cause a decrease in the gripping force exerted by the second portion of the outer surface  402  on the band  104 , due to the micropattern having a second microstructure density that is less than the first microstructure density, at least partially determined by the second width. 
     In some embodiments, the microstructures, and spaces between them, may be nanometer scale, or micrometer scale. For example, the microstructures and/or the spaces may have widths between approximately 100 nm and 500 micrometers. In one embodiment, the first microstructures may include nanofibers (e.g., carbon nanotubes sprayed onto a flat epoxy resin, or thin polypropylene fibers) having a diameter between 100 and 600 nm. The second microstructures may include similar nanofibers, but ones having a diameter between 5 and 14 micrometers. It is also contemplated that the first microstructures may include micropillars with a diameter of approximately 105 micrometers, a height of 150 micrometers, and spacing (between micropillars) of approximately 100 to 340 micrometers. Thus, the first microstructures may have a spacing-to-diameter ratio of approximately 0.952 to 3.238. The second microstructures may include micropillars with different diameters and/or spacing, and in particular, a spacing-to-diameter ratio greater than the spacing-to-diameter ratio for the first microstructures (e.g., greater than 3.238). 
     It is also contemplated that the microstructures may be compound structures. For example, the microstructures may include bristles, each around 30-130 micrometers long. The bristles may explode into a spray of 100 to 1,000 branches that form the points of contact with a surface, such as the surface of a band  104 . The tip of each branch may flatten into a spatula only about 10 nm thick. Such an arrangement may increase the gripping forces between the microstructures and the band  104 , allowing adhesion between the microstructures and the band  104  even when one or the other is wet. 
     By changing microstructure characteristics (e.g., size, shape, and/or composition), and/or by changing micropattern characteristics (e.g., size, pattern design, and/or microstructure spacing), the gripping force exerted by the microstructures and micropatterns may be adjusted up or down. Many combinations of the above characteristics may be employed to achieve one or more intended effects. Thus, the examples of microstructure and micropattern characteristics provided above are exemplary only, and not intended to be exhaustive or limiting. 
     One way the first micropattern may increase the gripping force is by making a first portion of the outer surface  402 , on which the first micropattern is applied, more hydrophobic. That is, a fluid contacting the first portion may bead and roll off the first portion more easily than other portions of the outer surface  402  that do not have the first micropattern. This may reduce the amount of fluid on the first portion. By reducing the amount of fluid on the first portion, sliding of the bands  104  on the first portion, caused by wetting of the first portion, may be reduced. For hydrophobicity, microstructures and microstructure spacing may be selected such that droplets of water tend to stand on tips of the microstructures, such that the droplets may roll off the tips of the microstructures with little force. 
     The second micropattern may decrease the gripping force by making a second portion of the outer surface  402 , on which the second micropattern is applied, less hydrophobic. That is, a fluid contacting the second portion may tend to spread on and wet the second portion more easily than on the first portion. This wetting may make increase the likelihood of sliding of the bands  104  on the second portion. 
     In some instances, depending on environment of use, applying a micropattern on the outer surface  402  to make the outer surface less hydrophobic, and more hydrophilic, may provide other benefits. For example, hydrophilic coatings may have reduced fouling or protein aggregation when in use. This is because proteins may slough off of hydrophilic coatings. By making the outer surface  402  more hydrophilic, long-term visibility through the cap  400  may be improved, since proteins would tend to slough off of the outer surface  402 , instead of adhering to or building on the outer surface  402  and blocking or otherwise limiting visibility. 
     By applying the first micropattern to a distal portion of the outer surface  402 , the gripping force of the distal portion may be enhanced, causing rolling of the bands  104  as they move along the distal portion of the outer surface  402 . The first micropattern may be applied in the region of the cap  400  analogous to the regions  124 ,  224 , or  324 . It is also contemplated that the first micropattern may be applied to the regions  124 ,  224 , or  324 , including on the grooves  112 ′. In another embodiment, the first micropattern may be applied to a proximal portion of the outer surface  402 , causing the gripping force of the proximal portion to be enhanced, allowing the proximal portion to cause rolling of the bands  104  in a manner similar to the grooves  112 . For example, the first micropattern may be applied in the region of the cap  400  analogous to the regions  122 ,  222 , or  322 . It is also contemplated that the first micropattern may be applied to the regions  122 ,  222 , or  322 , including on the grooves  112 ,  214 ,  214 ′, or  218 . 
     The second micropattern may be applied to portions of the outer surface  402  in which gripping force should be reduced. For example, the second micropattern may be applied to portions of the outer surface on which the first micropattern has not been applied. It is also contemplated that the first and second micropatterns may be arranged in alternating bands along the length of the outer surface  402 . 
     By controlling the gripping force using one or more micropatterns  412 , the positioning of the bands  104  during deployment can be controlled. For example, rolling of a band  104  may be initiated for a first part of the band  104 , at a certain time during deployment, by providing the first micropattern on a first region of the outer surface  402  engaging the first part of the band  104 . Rolling of a second part of the band  104  may not be initiated at that time, for a second part of the band  104 , by omitting the first micropattern or providing the second micropattern on a second region of the outer surface  402  engaging the second part of the band  104 . Tilting of the band  104  due, for example, to one part of the band  104  lagging behind another part of the band  104 , may also be controlled, by using one or more micropatterns  412  to speed up or slow down portions of the band  104  during deployment. 
     Additional embodiments of the present disclosure are shown in  FIGS. 5A and 5B , which disclose a cap  500 , with a first region  522  (see  FIG. 5B ) including protrusions  518 , for initiating rolling of the bands  104 , and a second region  525  (see  FIG. 5B ) including grooves  112 ′. Further,  FIG. 5B  illustrates a cross-sectional side view of the cap  500 , where the set of protrusions  518  and set of grooves  112 ′ are depicted over an outer surface  502  of the cap  500 . A lumen  511 , similar in form and function to cavity  111 , may extend from the proximal end portion  506  to the distal end portion  508  of the cap  500 . Alternatively, it is contemplated that the cross-sectional side view of the cap  500  may be similar to the cross-sectional side view of the cap  1000  shown in  FIG. 10A . 
     Referring to  FIGS. 5A and 10A , according to one aspect of the present disclosure, a first plane extending through a center of the distal groove  112 ′, and perpendicular to a longitudinal axis of the cap, may lie approximately 0.350 inches from a parallel second plane extending through a proximal end of the one or more protrusions  1002 . The first plane may be positioned approximately 0.100 inches from a distal end of the cap  1000 , to help ensure that the bands  104  will not become jammed on the cap  1000  prior to deployment. A parallel third plane extending through a center of the proximal groove  112 ′, may lie approximately 0.150 inches from the second plane. The spacing of the planes and grooves  112 ′ encourages rolling of the bands  104 , to help ensure that rolling deployment of the bands  104  may be achieved with minimal impact on visualization through the cap  500  via the imaging device (not shown). The second plane may be distal to the most distal row of the protrusions  518 . Alternatively, the second plane may be proximal to the most distal row of the protrusions  518 , but the second plane may be distal enough that the most distal row of the protrusions  518  may not obstruct a peripheral field of vision of an imaging device (not shown) in the cavity  511 . 
     In one embodiment of the present disclosure, the grooves  112 ′ may have a width of approximately 0.050 inches at their centers. In another embodiment of the present disclosure, the grooves  112 ′ may have a width of approximately 0.070 inches at their centers. In one embodiment of the present disclosure, the grooves  112 ′ may have a depth of approximately 0.020 inches at their centers, tapering off to a depth approaching zero at their ends. Edges of the grooves  112 ′, such as proximal and/or distal edges of the grooves  112 ′, may act as teetering points for bands  104 . The reduced surface contact and/or teetering points may encourage teetering, tilting, and rolling of the bands  104  as they move distally along the outer surface  502 . 
     Bands  104  may be positioned around a proximal end portion  506  of the cap  500 , with inner surfaces of the bands  104  resting on outer surfaces of the protrusions  518 . The protrusions  518  may be arranged in substantially parallel circumferentially extending rows, and/or in substantially parallel longitudinally extending columns. A suture  110  may lie in gaps between adjacent columns as the suture  110  extends proximally along the outer surface  502  and around the bands  104 . The protrusions  518  may reduce surface contact between the bands  104  and the outer surface  502 . Edges of the protrusions  518 , such as the proximal and/or distal edges at their peaks, may act as teetering points for bands  104 , encouraging portions of bands  104  to teeter, tilt, and rotate into and out of the gaps between the protrusions  518 . The reduced surface contact and/or teetering points may encourage rolling of the bands  104  as they move distally along the outer surface  502 . 
     At the distal end portion  108  of the cap  500 , one or more slots or channels  113  ( FIG. 5A ) may be provided to guide portions of the suture  110  as the suture  110  extends distally within the cavity  511 , bends around the distal end portion  508  of the cap  500 , and extends proximally to the bands  104 . At least a portion of the suture  110  may extend proximally through an endoscope, similar to the endoscope  150  ( FIG. 1A ). 
     On a side of the outer surface  502  diametrically opposite the protrusions  518 , the cap  500  may include one or more ridges or rails  523 . Each rail  523  may be substantially linear, and may extend in a longitudinal direction along the outer surface  502 . The rails  523  may lift portions of the inner surfaces of the bands  104  off of the outer surface  502 , decreasing the frictional force between those portions of the bands  104  and the outer surface  502 . This may help position the bands  104  during deployment so that the desired rolling effect can be achieved. 
       FIGS. 6A and 6B  depict a cap  600 , where a first region  622  and a second region  624  may include grooves  112 ′ that may have alternative cross-sectional profiles, such as triangular (see  FIG. 6B ) and trapezoidal (see  FIG. 6A ). The grooves  112 ′ may provide teetering points for the bands  104 , to encourage rolling of the bands  104  as they move distally along the outer surface  602 . 
     Another embodiment of the present disclosure is shown in  FIG. 10A .  FIG. 10A  shows a side perspective view of a cap  1000 . The cap  1000  is similar to the cap  500 , in that the cap  1000  includes protrusions  518  arranged in columns and/or rows, and grooves  112 ′, similar to the arrangement shown in  FIG. 5A . The protrusions  518  may be configured to engage radially inner surfaces of a plurality of bands  104  ( FIGS. 5A and 5B ), and to initiate rolling of the plurality of bands  104 . Alternatively, it is contemplated that bands  104  may be seated, at least partially, in the cavities between protrusions  518 . Since only some portions of the bands  104  contact the protrusions  518 , surface contact between the bands  104  and the outer surface of the cap  1000  is reduced. Edges of the protrusions  518 , such as the proximal and/or distal edges at their peaks, may act as teetering points. When surfaces of the bands  104  engage the teetering points, portions of the bands  104  may teeter, tilt, and rotate into and out of the gaps between the protrusions  518 . The reduced surface contact and/or teetering points may encourage rolling of the bands  104  as they move distally along the cap  1000 . 
     The grooves  112 ′ may engage the plurality of bands  104  as they move distally along the cap  1000 , and may encourage further rolling of the plurality of bands  104 . Edges of the grooves  112 ′, such as their proximal and/or distal edges, may also provide teetering points to cause teetering, tilting, and rotation of bands  104  into and out of the grooves  112 ′, as the bands  104  move along the cap  1000 . The cap  1000  may also include a central lumen  1004 , a step  1006 , and one or more protrusions  1002 . 
     A first plane extending through a center of the distal groove  112 ′, and perpendicular to a longitudinal axis of the cap  1000 , may lie approximately 0.350 inches from a parallel second plane extending through a proximal end of the one or more protrusions  1002 . A parallel third plane extending through a center of the proximal groove  112 ′, may lie approximately 0.150 inches from the second plane. The spacing between the planes ensures that visualization through the cap  1000 , using an imaging device  1007  configured to abut the protrusions  1002 , is minimally obstructed. For example, when the imaging device  1007  abuts the protrusions  1002 , the imaging device  1007  may be positioned such that the protrusions  518 , and/or bands  104  on the protrusions  518 , are outside of (e.g., proximal to) a field of view  1009  through a lens  1008  of the imaging device  1007 . The protrusions  518  and/or bands  104  thereon may be outside of the field of view  1009  even if portions of the protrusions  518  and/or bands  104  thereon may be distal to the imaging device  1007 . 
     Another embodiment of the present disclosure is shown in  FIG. 10B .  FIG. 10A  shows a side perspective view of a cap  1100 . The cap  1100  is similar to the caps  500  and  1000 , in that the cap  1100  includes protrusions  518  arranged in columns and/or rows in a manner similar to the arrangements shown in  FIGS. 5A and 10A . The cap  1100  differs in that it includes two additional circumferential rows of protrusions  518 ′, similar to rows of protrusions  518 , in place of the grooves  112 ′. The protrusions  518  may initiate rolling of the bands  104 , and the protrusions  518 ′ may encourage further rolling of the bands  104 . Edges of the protrusions  518 ′, such as the proximal and/or distal edges at their peaks, may provide teetering points for encouraging teetering, tilting, and rotating of the bands  104  into and out of the gaps between the protrusions  518 ′, as they move distally along the cap  1100 . The cap  1100  is similar to the cap  1000 , in that the cap  1100  may include a central lumen  1004 , a step  1006 , and one or more protrusions  1002 . 
     A first plane extending through a center of the distal row of protrusions  518 ′, and perpendicular to a longitudinal axis of the cap  1100 , may lie approximately 0.350 inches from a parallel second plane extending through a proximal end of the one or more protrusions  1002 . A parallel third plane extending through a center of the proximal row of protrusions  518 ′, may lie approximately 0.150 inches from the second plane. The spacing between the planes ensures that visualization through the cap  1100 , using an imaging device (not shown) abutting the protrusions  1002 , is minimally obstructed. 
     Another embodiment of the present disclosure is shown in  FIG. 10C .  FIG. 10C  shows a top perspective view of a cap  1200 . The cap  1200  is similar to the caps  500 ,  1000 , and  1100 , in that the cap  1200  includes protrusions  519  arranged in columns and rows, to initiate rolling of the bands  104 , in a manner similar to the arrangement of the protrusions  518  shown in  FIGS. 5A, 10A, and 10B . The protrusions  519  may reduce surface contact between bands  104  and the outer surface of the cap  1200 , and/or provide teetering points at the edges at their peaks, to encourage teetering, tilting, and rotating of portions of bands  104  into and out of gaps between the protrusions  519 , thereby encouraging rolling of the bands  104  as they move distally along the cap  1200 . 
     The cap  1200  is similar to the cap  1100 , in that the cap  1200  includes two additional circumferential rows of protrusions  519 ′, similar to rows of protrusions  518 ′, in a position analogous to the position occupied by rows  518 ′. The protrusions  519  may initiate rolling of the bands  104 , and the protrusions  519 ′ may encourage further rolling of the bands  104 . Radially-inner portions of the bands  104  may be seated in gaps between the protrusion  519 ′. Alternatively, radially-inner surfaces of the bands  104  may sit on peaks of the protrusions  519 ′, supported, for example, by two or more longitudinally-adjacent peaks. 
     Edges of the protrusions  519 ′, such as the edges at their peaks, may provide teetering points for encouraging teetering, tilting, and rotating of the bands  104  into and out of the gaps between the protrusions  519 ′, as they move distally along the cap  1200 . The cap  1200  is similar to the cap  1000 , in that the cap  1200  may include a central lumen  1004 , a step  1006 , and one or more protrusions  1002 . The protrusions  519  and  519 ′ have a triangular or wedge shape, unlike the protrusions  518  and  518 ′, which may have a trapezoidal or pyramidal shape. 
     It is contemplated that each of the protrusions  518 ,  518 ′,  519 , and  519 ′ may have a width of approximately 0.023 inches and a height of approximately 0.035 inches, a width of approximately 0.028 inches and a height of approximately 0.025 inches, or a width of approximately 0.028 inches and a height of approximately 0.035 inches. Other dimensions may also be used. The exact dimensions used may depend on a number of factors including, for example, the type of band being used. 
     It is also contemplated that the above-described micropatterns  412  and microstructures  422  may be applied to regions of the outer surface of any of the caps  500 ,  600 ,  1000 ,  1100 , or  1200 . For example, micropatterns  412  and microstructures  422  to enhance gripping between the outer surface and the bands  104  may be applied to a region of the outer surface distal to the one or more protrusions  1002  that form a stop for the imaging device (not shown), including on any grooves or protrusions in that region of the outer surface. 
     The series of  FIGS. 7A-7F  shows the cap  500  in use. The series may be applicable to any of the other cap embodiments described herein.  FIG. 7A  shows an exemplary rolling motion of a single band  104  enabled through a pull, depicted through the arrow C, of the suture  110  from a proximal end  806  of an endoscope  802  (see  FIG. 8 ). The endoscope  802  may be the endoscope  150  discussed in connection with  FIG. 1A , or may be similar to the endoscope  150 . Pulling the suture  110  in the direction of arrow C may initiate distal movement of the band  104 . As the band  104  encounters a deployment feature, such as one or more of the protrusions  518 , the protrusions  518  force at least a portion of the band  104  to teeter, tilt, and roll, particularly at the section where the suture  110  is wrapped around the band  104 . There may be some sliding before or after the roll. This section of the band  104  is referred to as section  732 , and the rolling motion is indicated by the arrow A. Another section  734  of the band  104 , lying substantially opposite to the section  732 , may also roll, or may slide for an extent of travel and roll for another extent of travel. A corresponding rolling motion at the portion  734  is depicted using the arrow B. The rolling of the section  732  may cause portions of the band  104  to twist, leading to rolling of the section  734 . Additionally or alternatively, rolling of the section  734  may be initiated or assisted by applying the micropattern  412  to portions of the outer surface  502  that contact the section  734 . 
     The section  732  may be more distal than the section  734 , due to the force exerted on the section  732  by the suture  110 . Thus, the band  104  may be tilted as it travels distally along the cap  500 . This may cause different sections of the band  104  to roll at different times. While some tilting may be desirable, the degree of tilting may be controlled using the rails  523  to reduce frictional contact between the section  734  and the outer surface  502 . The degree of tilting may also be controlled by increasing or reducing the gripping force between portions of the band  104  and the outer surface  502 , using appropriate micropatterns  412 . 
     In  FIG. 7B , the section  732  of the band  104  is shown to have accomplished at least a first roll, which may be anywhere from a 90° roll to a 360° roll, while the suture  110  continues to pull the band  104  distally through the second region  524 . The section  734  may exit the first region  522  and may slide and/or roll towards the second region  524 . 
       FIG. 7C  depicts both the section  732  and the section  734  in the second region  524 . Engagement between the section  732  and the groove  112 ′ a  may cause the section  732  to teeter, tilt, and roll. Thereafter, in  FIG. 7D , as the proximal pulling of the suture  110  continues, the band  104  continues to move distally. In some cases, section  732  may slide for an extent instead of rolling. The same may be true for section  734 . When the section  732  reaches the second groove  112 ′ b,  the section  732  may teeter, tilt, and roll, and enter at least partially within the second groove  112 ′ b  (as shown in  FIG. 7E ). Rolling of the section  732  may initiate rolling of the section  734 . 
     As the band  104  reaches the distal end portion  508 , continued pulling of the suture  110  may deploy the band from the cap  500 . The chamfered edge  526  at the distal end portion  508  may facilitate deployment of the band  104  from the distal end portion  508 . It is contemplated that by the time the band  104  reaches the distal end portion  508 , the sections  732  and  734  may be substantially aligned such that the deploy off the distal end portion  508  substantially simultaneous. Put another way, the tilting of the band  104  due to the section  734  initially lagging behind the section  732 , may decrease as the band  104  proceeds distally along the cap  500 . Positioning of section  734  relative to section  732  may be adjusted or controlled using, for example, one or more micropatterns  412  to slow down or speed up one section relative to the other. 
       FIG. 8  depicts a medical device  800 , forming an endoscopic system according to aspects of the present disclosure. The medical device  800  includes a an endoscope  802 , an endoscopic shaft  803 , a cap, such as the cap  500 , secured at the endoscope&#39;s distal end  804 , and a handle assembly  808  disposed at a proximal end  806 . It should be understood that any of the other caps described in this disclosure may be used in place of the cap  500 . 
     The endoscopic shaft  803  may have one or more working channels or lumens, such as a lumen  830 , extending through the endoscopic shaft  803 . The lumen  830  may carry medical devices such as a vacuum suction mechanism, endoscopic imaging device, light source, snare, and/or any other suitable medical device. The suture  110  may be operatively coupled to a rotary trigger disposed as part of the handle assembly  808 , at the proximal end  806  of the medical device  800 . The suture  110  may pass through the lumen  830 , to the cap  500 , and eventually to the bands  104 . 
     The series of  FIGS. 9A to 9D  depict an application procedure of the medical device  800 , which may be employable with any of the embodiments of the caps discussed in the present disclosure.  FIG. 9A  depicts the medical device  800 , equipped with the cap  500 , proceeding towards a target area of tissue  950  on an internal wall  952  of a patient&#39;s body. An arrow D depicts the movement of the medical device  800 . 
     Moving further towards the undesired tissue  950 , an operator may position the medical device  700  in contact with, and/or at least partially around, the target tissue  950 . A suction mechanism (not shown) may generate a vacuum force (arrow F) through the endoscope lumen  830 , thus pulling the undesired tissue  950  into the cavity  511 . A proximal pull on the suture  110 , enabled through the handle assembly  808 , may enable the band  104  to be released around the target tissue  950  (along the path of arrow E), ligating the target tissue  950 . The release of the band  104  may occur in the manner discussed in connection with the series of  FIGS. 7A to 7F . 
     Subsequently, once the band  104  is released over the target tissue  950 , a ligated tissue or pseudo polyp  954  is obtained, as shown in  FIG. 9C . Thereafter, a tissue resection device, such as a snare, may be brought forth from within the lumen  830  or outside of the endoscope  800 , for carrying out a tissue resection operation (such as an EMR) on the newly formed ligated tissue  954 . 
     Embodiments of the present disclosure may be used in any medical or non-medical environment. In addition, at least certain aspects of the aforementioned embodiments may be combined with other aspects of the embodiments, or removed, without departing from the scope of the disclosure. 
     Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.