Patent Publication Number: US-2017360459-A1

Title: Retrieval device and related methods of use

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority from U.S. Provisional Application No. 61/784,469, filed on Mar. 14, 2013, the entirety of which is incorporated by reference herein. 
    
    
     FIELD OF THE DISCLOSURE 
     Embodiments of the present disclosure relate generally to medical devices and procedures. Particularly, embodiments of the present disclosure relate to medical devices to perform tissue resection and/or retrieval during minimally invasive medical procedures. 
     BACKGROUND 
     Tissue resection procedures, such as polypectomy, are carried out by inserting introduction sheaths, such as endoscopes or laparoscopes, into the body of a patient through incisions or natural anatomical openings (e.g., oral, vaginal, and/or anal cavities). Traditionally, such devices employ snares, typically designed as loops, for performing tissue resection procedures. State of the art snares used for various tissue resection procedures have a tendency to slip off of tissue that is intended to be ensnared, often requiring repeated efforts to capture the tissue before the resection procedures can be successfully performed. 
     One factor affecting snare slippage is that the snare loop is typically drawn towards the snare shaft as the snare is closed, disrupting the distal snare tip, which often acts as an anchor relative to the tissue surface. 
     The present disclosure is directed to overcoming one or more of the issues described above and/or other shortcomings in the art. 
     SUMMARY 
     Embodiments of the present disclosure relate to medical devices for performing tissue-ensnaring procedures during, e.g., tissue resection from inside a patient&#39;s body. 
     In accordance with an aspect of the present disclosure, the medical device includes two or more bars, a snare loop and a constricting element. Each bar includes a proximal end, and one or more distal ends, such that the snare loop may be coupled to the distal ends of the bars. Further, the constricting element may be movably coupled to the bars, such that the constricting element expands the snare loop when positioned at the proximal end of the plurality of bars while the constricting element collapses the snare loop when positioned at the distal end of the plurality of bars, thus, keeping the distal end of the snare loop stationary with respect to the tissue. 
     In accordance with another aspect of the disclosure, a method for manipulating a tissue is described. The method includes introduction of the medical device into a body such that the distal end of the snare loop of the device is placed on the tissue. Thereafter, the snare loop is collapsed keeping the distal end of the snare loop stationary with respect to the tissue. 
     In accordance with the disclosure, another method for manipulating a tissue is described. The method includes introduction of the medical device into a body such that the distal end of the snare loop of the device is placed on the tissue. Thereafter, the snare loop is collapsed by moving a constricting element of the medical device distally, thus, keeping the distal end of the snare loop stationary with respect to the tissue. 
     In accordance with the disclosure, another method for manipulating a tissue is described. The method includes introduction of the medical device into a body such that the distal end of the snare loop of the device is placed on the tissue. Thereafter, the snare loop is collapsed by extending an actuation tube of the medical device distally, thus, keeping the distal end of the snare loop stationary with respect to the tissue while the tissue is manipulated. 
     Additional objects and advantages of the present disclosure will be set forth in part in the description which follows, and in part will be understood from the description, or may be learned by practice of the claimed invention. 
     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 invention, 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. 1  is a schematic illustration of the perspective view of a distal portion of an exemplary retrieval device with expanded configuration of its snare loop. 
         FIG. 2  is a schematic illustration of an exemplary snare apparatus of the retrieval device of  FIG. 1  with the snare loop in an expanded configuration. 
         FIG. 3  is a schematic illustration of the retrieval device of  FIG. 2  with the snare loop in a collapsed configuration. 
         FIG. 4  is a schematic illustration of a second embodiment of an exemplary snare apparatus of the retrieval device of  FIG. 1  with the snare loop in an expanded configuration. 
         FIG. 5  is a schematic illustration of the retrieval device of  FIG. 4  with the snare loop in a collapsed configuration. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like parts. The term “distal” refers to the end farthest away from a user when introducing a device into a patient. The term “proximal” refers to the end closest to the user when placing the device into the patient. 
     Overview 
     Embodiments of the present disclosure relate to medical devices used to retrieve and/or sever unwanted tissue as well as other unwanted material, such as stones, within a patient&#39;s body. For example, embodiments of the disclosed device may facilitate removal of unwanted tissue, such as cancerous polyps or lesions, from within a patient&#39;s body, including tissue disposed, e.g., on the mucosal walls of the colon, esophagus, stomach, or duodenum. A physician may also desire to resect tissue in order to conduct a biopsy or other examination. For convenience, the medical devices discussed here are referred to as “retrieval devices,” it being understood that such devices are equally useful for severing unwanted tissue. 
     In some embodiments, a retrieval device may include a plurality of bars, a snare loop, and a constricting element. Each bar includes a distal end and a proximal end. The distal end of the bars may be coupled to the snare loop while the proximal ends may be in close proximity to each other. The proximal ends of the bars may be enclosed in, or surrounded by, an elongate shaft. Further, the constricting element may be movably coupled to the bars such that when the constricting element is placed at the proximal end of the bars, the snare loop is in an expanded position and when the constricting element is placed at the distal end of the bars, the snare loop is in a collapsed position. The movement of the constricting element is controlled by an actuating element, such as, for example, a guidewire, a resilient mechanism like a spring, or other suitable mechanism. The actuating element may pass through the elongate shaft. In various embodiments, the constricting element may be cylindrical, rectangular, oval, elliptical, conical, and similar configurations. 
     In various embodiments of the disclosure, the operation of the retrieval device includes collapsing the snare loop such that the distal end of the snare loop remains stationary with respect to the targeted tissue, thereby enabling steady grip of the tissue. 
     Exemplary Embodiments 
       FIG. 1  illustrates a perspective view of a distal portion of an exemplary retrieval device  100  depicting an expanded configuration of its snare loop, according to an embodiment of the present disclosure. The retrieval device  100  may be configured to be introduced into a patient&#39;s body through an incision or a suitable natural opening. In addition, the retrieval device  100  may be configured to be advanced to a desired location within a patient&#39;s body with the aid of a suitable introduction sheath, such as, e.g., an endoscope  10  that can further include a steerable elongate sheath  12  having a distal end  14 , a proximal end (not shown) and one or more working channels extending therebetween. 
     As discussed above, endoscope  10  may include one or more working channels, wherethrough an operator may introduce one or more medical devices to extend out of the distal end  14  of elongate sheath  12 . For example, during a resectomy procedure, an operator may introduce a suction device into one channel and another instrument, such as retrieval device  100 , for example, into another channel. Additionally, from time to time during the procedure, the operator may insert a light source, a camera, an injector, or a morcellator within the one or more channels. The proximal end of the elongate sheath  12  may be connected to a hub assembly or handle (not shown) for operating the endoscope  10 . The retrieval device  100  may include an elongate shaft  102  that further includes a proximal end (not shown), a distal end  104 , and a lumen  106 . The lumen  106  may be in communication with a distal opening  108  at the distal end  104  of the shaft  102 , and the lumen  106  may extend through the entire length of the shaft  102 . The elongate shaft  102  may be configured to be steerable independently of endoscope  10  using, e.g., a control wire or other similar mechanism. Further, the elongate shaft  102  may be coupled to the sheath  12  through its proximal end while supporting a medical device  110  at its distal end  104 . The medical device  110  includes two or more bars  112 ( a ),  112 ( b ), one or more constricting elements  114 , and a snare loop  116 . 
       FIG. 2  illustrates an expanded configuration of the snare loop  116  of the medical device  110 . The medical device  110  includes two or more bars  112 ( a ) and  112 ( b ), at least one constricting element  114 , and the snare loop  116 . Each bar  112 ( a ) or  112 ( b ) has a distal end  202 ( a ) or  202 ( b ) respectively, and a proximal end which may extend into the opening  108  of the distal end  104  of the shaft  102  (see  FIG. 1 ). The bars  112 ( a ) and  112 ( b ) may be in close proximity to each other at their proximal ends while, towards their distal ends  202 ( a ) and  202 ( b ), the bars  112 ( a ) and  112 ( b ) may be farther apart and coupled to the snare loop  116 . In an embodiment, the bars  112 ( a ) and  112 ( b ) along with the snare loop  116  may therefore form a V-shaped structure. 
     The snare loop  116  may be coupled to the bars  112 ( a ) and  112 ( b ) via a fixed connection like welding or may be detachably connected to the bars  112 ( a ) and  112 ( b ) via, for example, without limitation, a hook. The constricting element  114  may be movably coupled to the bars  112 ( a ) and  112 ( b ) such that the edges of the constricting element  114  slide on the bars  112 ( a ) and  112 ( b ) while the body of the constricting element  114  is placed in between the bars  112 ( a ) and  112 ( b ). In an embodiment, the distance between the two bars  112 ( a ) and  112 ( b ) towards the proximal end may be equal to the width of the constricting element  114 . The constricting element  114  includes an actuating mechanism (shown in  FIG. 3 ) that moves/slides the element  114  over the bars  112 ( a ) and  112 ( b ). In various embodiments, the actuation mechanism may include a guidewire, a spring mechanism or the like. 
     The bars  112 ( a ) and  112 ( b ) may be relatively rigid as compared to the snare loop  116 . Alternatively, or in addition, the bars  112 ( a ) and  112 ( b ) may be supported by corresponding stiffening elements extending along with them. In an embodiment, the stiffening bars  112 ( a ) and  112 ( b ) may be hollow and may enclose the snare wire. Alternatively, the stiffening bars  112 ( a ) and  112 ( b ) may be solid. The wire used for the snare loop  116  and the bars  112 ( a ) and  112 ( b ) may be the same or different in structure and composition. For example, the snare loop  116  may be narrower and more rigid than the snare wire of the bars  112 ( a ) and  112 ( b ). The stiffening bars  112 ( a ) and  112 ( b ) could be manufactured from a variety of suitable biocompatible materials available to the art, such as nitinol, stainless steel, or polyimide. The chosen material may be based on desired stiffness, resilience, and other properties, as will be understood by those skilled in the art. 
     The snare wire may include a braided wire, multiple wires, or other suitable wires known to those skilled in the art. In addition, the material employed to manufacture such wires may include, but is not limited to, a rigid, a flexible, or a semi-rigid material. Exemplary materials may include metals, polymers, composites, alloys, or the like. The snare wire and/or the stiffening bars  112 ( a ) and  112 ( b ) may be coated with a suitable friction reducing material such as TEFLON®, polyetheretherketone, polyimide, nylon, polyethylene, or other lubricious polymer coatings, to reduce surface friction with the surrounding tissues. Alternatively, snare wire and/or the stiffening bars  112 ( a ) and  112 ( b ) may be made of, or covered with, an insulating layer, for example, a hydrophilic layer of polymers known in the art, to prevent inadvertent cauterizing of surrounding tissue. 
     In one embodiment, the snare loop  116  may be a wire configured to sever or retrieve unwanted tissue. Further, the snare loop  116  may be configured in a variety of shapes, such as a continuous loop, multiple loops, a basket, and the like. In one implementation, the snare loop  116  is substantially circular in shape, however, other configurations may include ellipsoids. 
     The constricting element  114  may slide over the bars  112 ( a ) and  112 ( b ) from the snare loop  116  to the proximal end of the bars  112 ( a ) and  112 ( b ). In various embodiments, the constricting element  114  may be cylindrical, oval, elliptical, rectangular, conical (similar configurations) in shape. Additionally, the constricting element  114  may include one or more holes through which an actuation element (for example, a guidewire) or snare wire may pass. 
     As shown in  FIG. 2 , the constricting element  114  when placed at the proximal end of the bars  112 ( a ) and  112 ( b ), may allow snare loop  116  to expand. For example, snare loop  116  may be configured to self expand and/or bars  112 ( a ),  112 ( b ) may be configured to self expand. The constricting element  114  may be arranged in a way such that a distally directed force on the constricting element  114  closes the snare loop  116  by drawing the distal end of the bars  202 ( a ) and  202 ( b ) towards each other. Distal forces may be applied on the constricting element  114  via the actuation element (shown in  FIG. 3 ) coupled to the constricting element  114  which may be made of a conductive material, such as nitinol, stainless steel, and polyimide, to serve as an electrical path for cautery. In one embodiment, the distal ends of the bars  112 ( a ) and  112 ( b ) may include one or more features configured to act as a stop on movement of the constricting element  114  to prevent constricting element  114  to advance beyond a distal end of the bars  112 ( a ) and  112 ( b ). 
     A variety of mechanisms known in the art may be employed to selectively move/slide the constricting element  114  to expand or retract the snare loop  116 . In one example, a push-pull mechanism, for example an actuation wire, may be employed as the actuation element for either manually or automatically expanding and/or retracting the snare loop  116 . The movement of the constricting element  114  changes the area captured by the snare loop  116  without displacing/moving the snare loop with respect to the targeted tissue. In the expanded configuration, the snare loop  116  can be in a largest possible target acquisition area configuration based on the dimensions of the snare loop  116 . 
       FIG. 3  illustrates the collapsed configuration of the snare loop  116 . In the collapsed configuration, the constricting element  114  is moved towards the distal end  202 ( a ) and  202 ( b ) of the bars  112 ( a ) and  112 ( b ) respectively, while snare  116  is held stationary relative to a tissue surface. The distal movement of the constricting element  114  forces the snare loop  116  to collapse as the ends of the snare loop  116  coupled to the bars  112 ( a ) and  112 ( b ) are brought in close proximity. The distal movement of the constricting element  114  may be facilitated by an actuation element  302 . In the embodiment, the actuation element  302  is released to facilitate distal movement of the constricting element  114 . 
     Optionally, a locking mechanism may be provided at the distal end  202 ( a ) and  202 ( b ) of the bars  112 ( a ) and  112 ( b ) respectively, to lock the constricting element  114 , thereby reducing inadvertent movement of the constricting element  114  and enabling a steady grip of the tissue. 
     Now referring to the operation of the above embodiment, the device  110  is introduced into the body. While the device  110  is inserted, the snare loop  116  may remain in collapsed configuration with the constricting element  114  being placed at the distal end  202 ( a ) and  202 ( b ) of the bars  112 ( a ) and  112 ( b ) respectively. The movement of the inserted device  110  within the body is controlled till the snare loop  116  is placed on the targeted tissue. In an embodiment, the distal end  304  of the snare loop  116  is placed on the tissue after the device  110  is inserted into the body. The distal end  304  may, without limitation, include an outward projection in the loop  116  to help grip the tissue. 
     Thereafter, the snare loop  116  is expanded using the actuation element  302  coupled to the constricting element  114 . When proximal forces are applied by the actuation element  302  to the constricting element  114 , the element  114  moves towards the proximal end of the bars  112 ( a ) and  112 ( b ), thereby expanding the snare loop  116  to the desired area. In an embodiment, the snare loop  116  may be expanded to attain an area that fits the targeted tissue. The snare loop  116  and the bars  112 ( a ),  112 ( b ) remain stationary with respect to the tissue as the element  114  is moved proximally. It may be seen that the movement of the element  114  may only allow lateral movement of the snare  116  or the bars  112 ( a ) and  112 ( b ) while limiting any longitudinal movement of the snare  116  or the bars  112 ( a ) and  112 ( b ) with respect to the tissue. This enables the snare  116  to remain steady and address any slippage issues. The snare loop  116  may be adjusted such that it covers/surrounds the targeted tissue. Such adjustment may be achieved by the application of distal/proximal forces one or more times on the constricting element  114 . 
     Once the snare  116  surrounds/covers the tissue, the tissue is manipulated. In an embodiment, the snare loop  116  may be configured for electrocauterization procedures to manipulate the tissue. Here, the snare loop  116  and/or constricting element  114  may be configured to conduct sufficient electric current to generate the heat required for electrocautery. In this embodiment, the snare loop  116  may also be substantially hollow with holes disposed on a surface (e.g., an internal surface) to provide, e.g., irrigation or lubrication during electrocauterization or any other medical procedure. Furthermore, the snare loop  116  can be configured to withstand repeated heat cycling without developing “hot spots” and breaking down. Further, the general characteristics of suitable materials and configurations of the snare loop  116  are known in the art to be able to select adequate materials and configurations for snare loop  116 . In one embodiment, the snare loop  116  may be made of a suitable biocompatible material, e.g., stainless steel or nitinol. 
     After the tissue is manipulated, the constricting element  114  is moved towards the distal end  202 ( a ) and  202 ( b ) of the bars  112 ( a ) and  112 ( b ) respectively. The constricting element  114  moves on application of distal forces by the actuation element  302 . Such forces may be applied by releasing the actation element  302  which in turn pushes the element  114  distally. The movement of the constricting element  114  from the proximal end to the distal end collapses the snare loop  116  as the distal ends  202 ( a ) and  202 ( b ) of the bars and the ends of the snare loop tied to the bars  112 ( a ) and  112 ( b ) come in close proximity to each other. It may thus be seen that the distal end  302  of the snare loop  116  remains stationary with respect to the tissue while the constricting element  114  is manipulated to expand/retract the snare loop  116 . Even though the constricting element  114  is moved from the proximal end to the distal end or vice versa, the distal end  304  of the snare loop  116  and the device  110  remain in place without any longitudinal movement/displacement. 
     It may be apparent to a person skilled in the art that the teachings of the present disclosure as illustrated above are not limited to the above embodiment. In fact, the teachings of the present disclosure can be carried out using alternative embodiments such as described below as a second embodiment. In various embodiments, the actuation element may include without limitation, a guidewire, a spring mechanism, an actuation tube, a bracket, or a plate with one or more holes and the similar configurations. 
       FIG. 4  illustrates an expanded configuration of the snare loop  116  attached to the retrieval device  100  according to a second embodiment of the present disclosure. The distal end  104  of the elongate shaft  102  may include an actuation element in the lumen  106  of the shaft  102  and the actuation element may be capable of sliding within the shaft  102 . In an embodiment, the actuation element includes without limitation, an actuation tube  402 . The tube  402  may include a proximal portion (not shown) and a distal end  404 . The tube  402  may extend from the shaft  102  such that it protrudes past the distal end  104  of the shaft  102  with the proximal end of the tube  402  enclosed/surrounded by the distal end  104  of the shaft  102 . In one example, the proximal end of the tube  402  may be operatively attached to the shaft  102  using one or more sliders. The degree of flexibility of the tube  402  may be predetermined based on a variety of factors. Such factors include, but are not limited to, (1) the ability of the tube  402  to retract within the shaft  102 , and/or (2) the amount of stiffness required to be imparted to the snare loop  116 . 
     In addition, the tube  402  may include a lumen  406  (shown in  FIG. 5 ) extending between the distal end  404  and the proximal end of the tube  402 . Snare  116  may be disposed within the lumen  406 . The tube  402  may be, e.g., a rigid cylindrical hollow bar configured to expand or collapse the snare loop  116  during use. In various embodiments, the length of the tube  402  may be such that it is less than, equal to or longer than the length of the shaft  102 , depending upon the requirements of stiffness of the shaft  102 . In an embodiment with the length of the tube  402  being less than the length of the shaft  102 , the snare wire may be terminated on the inner side of the shaft  102 . Alternatively, the snare wire may extend through the entire length of the lumen of the tube  402  and the shaft  102 . 
     The tube  402  may further include a handle (not shown) that may slide the tube  402  in the lumen  106  of the shaft  102 . An actuation wire of snare  116  (not shown in the figures) extends through the lumen  406  of the tube  402  and lumen  106  of the shaft  102 . 
     As shown in  FIG. 4 , the snare loop  116  is completely expanded. To achieve this configuration of the snare  116 , the tube  402  is completely retracted such that it is fully surrounded by the shaft  102 . This results in the snare  116  being completely exposed and attain an expanded configuration. In an embodiment, the snare  116  may self-expand once the tube  402  is retracted in the absence of any controlling/manipulating forces. 
     The snare  116  may be made of such material that provides a required stiffness to the loop while it is in the expanded configuration and preferentially assumes a set shape when expanded, such as a circle or ellipse. The shaft  102  and the tube  402  can be made of the same or different types of materials, including those mentioned above, based on the degree of flexibility required for each of the them for accessing the targeted tissue. The shaft  102  and the tube  402  may be coated with a suitable friction reducing material such as TEFLON®, polyetheretherketone, polyimide, nylon, polyethylene, or other lubricious polymer coatings, to reduce surface friction with the surrounding tissues. The tube  402  may be made of, or covered with, an insulating layer, such as, for example, a hydrophilic layer of polymers known in the art, to prevent inadvertent cauterizing of surrounding tissue. 
     Further, the shaft  102 , the tube  402 , and the snare loop  116  may be coated with an antimicrobial covering to inhibit any microbial growth on its surface. For instance, the coating may include an anti-bacterial covering, which may contain an inorganic antibiotic agent, disposed in a polymeric matrix that adheres the antibiotic agent onto the surface of the snare loop  116 . Furthermore, a drug-releasing coating may be applied to the surface of the snare loop  116  for assisting in delivery of drugs to the targeted tissue during operation. 
       FIG. 5  illustrates a collapsed view of the snare loop  116  according to the second embodiment of the present disclosure. In the collapsed configuration of the snare loop  116 , the tube  402  is extended out of the shaft  102 . This results in drawing/forcing the proximal ends of the snare  116  towards each other, with the tube  402  covering the snare loop  116  partially or completely. Though the snare loop  116  collapses, the distal end of the snare  116 , shaft  102 , and the snare wire (enclosed within the lumen of the shaft  102 ) remain in stationary with respect to the targeted tissue. The movement of the tube  402  may be controlled by the handle coupled to the tube  402 . The wire of which the snare loop  116  is formed may be sufficiently flexible to retract the snare loop  116  in the collapsed position. 
     Referring to the operation of the second embodiment, when the retrieval device is inserted into the human body, the snare loop  116 , in a collapsed configuration, may be placed on the tissue to be resected using a camera, and similar configurations. The distal end  304  of the snare loop  116  may include an outward projection to ensure that the snare loop is properly secured to the tissue. The tube  402  may be completely extended for the snare  116  to be in collapsed configuration. Thereafter, the snare loop may be expanded by moving the handle of the actuation tube  402  in the proximal direction to encompass or cover the desired tissue or area to be ensnared. The tissue may be manipulated by electrocautering, abrazing, or other methods known in the art. The snare  116  may then be collapsed by extending the tube  402  from the shaft  102  such that the tube  402  partially or completely surrounds the snare  116 . The tube  402  may be extended on application of distal forces on the handle that controls the movement of the tube  402 . 
     By securing the distal end of the snare loop  116  onto the tissue or organ and adjusting the area of the snare loop required to hold the tissue using a movable actuation element, for example tube  402 , the shaft  102  and the snare  116  are not required to be moved thereby eliminating the problem of snare loop slippage. The movement of the tube  402  distally/proximally results in manipulation of the snare  116  keeping the snare wire, the distal end of the snare loop  116 , and the shaft  102  in place with respect to the targeted tissue. 
     It should be apparent that the retrieval device  100  of the present disclosure is useful to perform surgical, diagnostic, and therapeutic procedures in a wide variety of bodily locations. For example, removal of polyps detected during a routine colonoscopy could quickly be accomplished using the method discussed above. Additionally, stones or unwanted deposits can be engaged and removed from a variety of body lumens such as ureters, bladders, or the urethra. These and other procedures can be accomplished within the scope of the present disclosure. 
     Embodiments of the present disclosure may be used in any medical or non-medical procedure, including any medical procedure where appropriate resection of undesired body tissue is required. 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 invention being indicated by the following claims.