Patent Publication Number: US-2021178120-A1

Title: Tissue retraction device and delivery system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of Ser. No. 16/399,459, filed Apr. 30, 2019, which claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application No. 62/665,441, filed May 1, 2018, the entire disclosure of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure pertains to medical devices, and methods for manufacturing medical devices. More particularly, the present disclosure pertains to a tissue retraction device and related delivery system. 
     BACKGROUND 
     A wide variety of intracorporeal medical devices have been developed for medical use, for example, intravascular use. Some of these devices include guidewires, catheters, and the like. These devices are manufactured by any one of a variety of different manufacturing methods and may be used according to any one of a variety of methods. Of the known medical devices and methods, each has certain advantages and disadvantages. There is an ongoing need to provide alternative medical devices as well as alternative methods for manufacturing and using medical devices. 
     BRIEF SUMMARY 
     This disclosure provides design, material, manufacturing method, and use alternatives for medical devices. An example tissue retraction device includes a first tissue engagement member coupled to an elastic member by a coupling assembly. The coupling assembly including a first coupler body having a first end region and a first compression member. Further, the first end region of the first coupler body is configured to extend into a portion of a lumen of the elastic member and the compression member is designed to compress the elastic member onto the first coupler body such that the elastic member is fixedly engaged with the coupler body. 
     Alternatively or additionally to any of the embodiments above, wherein the first end region of the first coupler body includes a channel extending around the circumference thereof. 
     Alternatively or additionally to any of the embodiments above, wherein the first compression member is designed to compress the elastic member into at least a portion of the channel of the first coupler body. 
     Alternatively or additionally to any of the embodiments above, wherein the compression member includes a compression ring. 
     Alternatively or additionally to any of the embodiments above, wherein the compression member includes a suture. 
     Alternatively or additionally to any of the embodiments above, wherein the coupling assembly further comprising a connection member, wherein the connection member is designed to couple the coupler body to the first tissue engagement member. 
     Alternatively or additionally to any of the embodiments above, wherein the connection member includes a post member and an attachment member, wherein a first end region of the post member is coupled to the attachment member, and wherein the post member is configured to extend through an aperture of the coupler body. 
     Alternatively or additionally to any of the embodiments above, wherein the post member further includes a second end region opposite the first end region, and wherein the first end region of the post member includes a first diameter, and wherein the second end region of the post member includes a second diameter larger than the first diameter. 
     Alternatively or additionally to any of the embodiments above, wherein the aperture includes a first inner diameter, and wherein the second diameter of the post member is larger than the first inner diameter of the aperture. 
     Alternatively or additionally to any of the embodiments above, wherein the first tissue engagement member includes a first tissue engagement portion and a first spring, and wherein the attachment member is designed to engage the first spring. 
     Alternatively or additionally to any of the embodiments above, wherein the attachment member is substantially C-shaped. 
     Alternatively or additionally to any of the embodiments above, wherein the attachment member includes a first fitting and a second fitting, and wherein the first fitting and the second fitting are designed to mate with one another. 
     Alternatively or additionally to any of the embodiments above, wherein the first fitting and the second fitting are designed to couple the first spring with the first end region of the post member. 
     Alternatively or additionally to any of the embodiments above, further comprising a second tissue engagement member, and wherein the elastic member extends between the first tissue engagement member and the second tissue engagement member. 
     Alternatively or additionally to any of the embodiments above, further comprising a tubular support member including a lumen extending therein, and wherein at least a portion of the elastic member extends within the lumen of the support member. 
     Alternatively or additionally to any of the embodiments above, wherein the support member is positioned between the first tissue engagement member and the second tissue engagement member. 
     Another tissue retraction device includes: 
     a first tissue clip coupled to an elastic member by a first coupling assembly, and a second tissue clip coupled to the elastic member by a second coupling assembly, and wherein the first and second coupling assemblies each include:
         a coupler body having a first end region; and   a compression member;       

     wherein the first end region of each of the coupler bodies is configured to extend into a portion of the lumen of the elastic member; 
     wherein each of the compression members are designed to compress the elastic member onto each of the coupler bodies such that the elastic member is fixedly engaged to each of the coupler bodies. 
     Alternatively or additionally to any of the embodiments above, wherein the first end region of the each of the coupler bodies includes a channel extending around the circumference thereof. 
     Alternatively or additionally to any of the embodiments above, wherein each of the compression members is designed to compress the elastic member within at least a portion of the channel of each of the coupler bodies. 
     A method of dissecting tissue includes: 
     advancing a tissue retraction device to a target site, the tissue retraction device including:
         a first tissue engagement member coupled to an elastic member by a coupling assembly, the coupling assembly including:
           a first coupler body having a first end region; and   a first compression member;   
           wherein the first end region of the first coupler body is configured to extend into a portion of a lumen of the elastic member;   wherein the compression member is designed to compress the elastic member onto the first coupler body such that the elastic member is fixedly engaged with the coupler body;       

     manipulating the first tissue engagement member between a first configuration and a second open configuration; and 
     attaching the first tissue engagement member to the target site. 
     The above summary of some embodiments is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The Figures, and Detailed Description, which follow, more particularly exemplify these embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure may be more completely understood in consideration of the following detailed description in connection with the accompanying drawings, in which: 
         FIG. 1  is a partial cross-sectional side view of an example tissue retraction device positioned within a body lumen; 
         FIG. 2  is a perspective view of an example tissue retraction device; 
         FIG. 3  is an exploded view of the example tissue retraction device shown in  FIG. 2 ; 
         FIG. 4  illustrates an example tissue engagement member; 
         FIG. 5  is a perspective view of another example tissue retraction device; 
         FIG. 6  is an exploded view of the example tissue retraction device shown in  FIG. 5 ; 
         FIGS. 7-9  illustrate example tissue engagement members; 
         FIGS. 10-14  illustrate a methodology for deploying and attaching an example tissue retraction device. 
     
    
    
     While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the disclosure to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure. 
     DETAILED DESCRIPTION 
     For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification. 
     All numeric values are herein assumed to be modified by the term “about”, whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (e.g., having the same function or result). In many instances, the terms “about” may include numbers that are rounded to the nearest significant figure. 
     The recitation of numerical ranges by endpoints includes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). 
     As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. 
     It is noted that references in the specification to “an embodiment”, “some embodiments”, “other embodiments”, etc., indicate that the embodiment described may include one or more particular features, structures, and/or characteristics. However, such recitations do not necessarily mean that all embodiments include the particular features, structures, and/or characteristics. Additionally, when particular features, structures, and/or characteristics are described in connection with one embodiment, it should be understood that such features, structures, and/or characteristics may also be used in connection with other embodiments whether or not explicitly described unless clearly stated to the contrary. 
     The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention. 
     A number of medical procedures, including intravascular procedures, procedures along the digestive and/or biliary tract, thoracic procedures, etc. utilize medical devices to access tissue intended for removal (e.g., “target tissue”) within the body. For example, in some current medical procedures (e.g., Endoscopic Submucosal Dissection (ESD), Peroral Endoscopic Myotomy (POEM), cholecystectomy, Video-Assisted Thoracoscopic Surgery (VATS)), physicians may utilize an endoscope or similar medical device to access and remove cancerous lesions. Further, as part of the procedure, the physician may utilize an endoscope capable of both accessing the target tissue site while also permitting a cutting device to be deployed therethrough to excise the target tissue. Additionally, in some instances, the endoscope may incorporate features which assist the physician in visualizing and performing the tissue dissection procedure. For example, some endoscopes may include a light and/or camera designed to illuminate the body lumen as the scope is navigated and positioned adjacent to the target tissue site. Additionally, some endoscopes may also include a lumen (e.g., a working channel) through which a cutting member or other accessory medical devices may be deployed and utilized. 
     While physicians are becoming more proficient at extracting cancerous lesions from within the body (e.g., within the digestive tract, abdominal cavity, thoracic cavity, etc.), the extraction methods continue to be inefficient and time-consuming. For example, in some instances poor visualization of the tissue dissection process may result in a prolonged tissue dissection procedure. In another example, the actual tissue that the physician is attempting to dissect may, itself, obstruct the pathway of the tools which the physician is using during the procedure. Therefore, in some instances it may be desirable to utilize a medical device which assists in improving the visualization of the target tissue while also mitigating the obstruction of dissection tools the physician is utilizing. Therefore, in some instances it may be desirable to utilize a tissue retraction device which lifts and retracts the region of tissue to be dissected by the physician. Disclosed herein are medical devices such as a tissue retraction device and delivery system that are designed to lift and retract the target tissue. 
       FIG. 1  is a partial cross-sectional side view of an example tissue retraction delivery system  10  including a distal portion  12  and a proximal portion  14 .  FIG. 1  shows the distal portion  12  of the tissue retraction system  10  positioned within an example body lumen  16 . Further,  FIG. 1  shows that the proximal portion  14  of the tissue retraction system  10  may extend out of the body lumen  16  to a position outside the body. As shown in  FIG. 1 , the tissue retraction system may include a tissue retraction device  22 . Additionally, the tissue retraction system  10  may include a delivery catheter  26 . The delivery catheter  26  may be constructed from a semi-rigid or compliant material such as a thermoplastic elastomer, silicone rubber, nylon, polyurethane, polyethylene terephthalate (PET), latex, or similar materials. The delivery catheter  26  may have a distal end region  28  and a proximal end region  30 . Further, a lumen  32  may extend through the delivery catheter  26  from proximal end region  30  to the distal end region  28 . As illustrated, the tissue retraction device  22  may be positioned along the distal end region  28  and within the lumen  32  of the delivery catheter  26 . 
     Additionally,  FIG. 1  illustrates that the delivery catheter  26  (including the tissue retraction device  22 ) may extend through an example medical device  18 . As discussed above, in  FIG. 1  the medical device  18  may take the form of an endoscope, laproscope, needle, catheter, guide tube, or the like. The medical device  18  may include a distal portion  23  and a proximal portion  25 . Further,  FIG. 1  illustrates that the distal portion  23  of the medical device  18  may be advanced within a portion of a body lumen  16  to a position adjacent a target tissue  50 , such as a lesion, while the proximal portion  25  of the medical device  18  may extend out of the body lumen  16  to a position outside the body. 
     Medical device  18  may include a lumen  21  extending from the proximal portion  25  to the distal portion  23  of the medical device  18 . In some examples, the lumen  21  may be referred to as the “working channel” of the medical device  18 . The lumen  21  may be designed to permit a variety of medical devices to pass therethrough. For example, a physician may pass or exchange a variety of medical devices through the working channel  21  over the course of a given medical procedure. For example, as illustrated in  FIG. 1 , the delivery catheter  26  (including the tissue retraction device  22 ) may extend through the lumen  21  of the medical device  18 . In other words,  FIG. 1  illustrates that a physician may insert the distal end  28  of the delivery catheter  26  into the proximal portion  25  of the medical device  18  (which is outside the body), advance the delivery catheter  26  through the lumen  21  whereby the distal end  28  of the delivery catheter may eventually extend out of the distal portion  23  of the medical device  18  to a position adjacent the target tissue  50 . 
     The proximal end  30  of the delivery catheter  26  may include a control member  42 . The control member  42  may be utilized as a grip to control the translation of the delivery catheter  26 . Further, the control member  42  may also permit a user to rotate the delivery catheter  26 . As will be described in greater detail below, the control member  42  may be utilized by a physician to advance the distal end  28  of the delivery catheter  26  to a position adjacent a target tissue  50  prior to deploying the tissue retraction device  22  from the distal end  28  of the delivery catheter  26 . 
     In some examples, the medical device  18  may include additional features. For example, the medical device  18  shown in  FIG. 1  may include an accessory feature  20  (e.g., light, camera, etc.) positioned on the distal portion  23  of the medical device  18 . Further, other medical devices  18  having additional features may be utilized in conjunction with the tissue retraction system  10 . 
     As illustrated in  FIG. 1 , in some examples the tissue retraction system  10  may include a manipulating device  34  (“manipulator”) designed to advance (e.g., push, deploy, etc.) the tissue retraction device  22  out of the distal end  28  of the delivery catheter  26 . As will be described in greater detail below, once the manipulator  34  has pushed the tissue retraction device  22  out of the delivery catheter  26 , it may also be used to position and/or manipulate the tissue retraction device  22  within the body lumen  16 . 
     As shown in  FIG. 1 , the manipulator  34  may extend within the lumen  32  of the delivery catheter  26 . In other words,  FIG. 1  illustrates that a distal end  38  of the manipulator  34  may extend from the proximal end  30  of the delivery catheter  26  (which is outside the body), through the lumen  32  of the delivery catheter  26  whereby the distal end  38  of the manipulator  34  may be positioned adjacent the proximal end of the tissue retraction device  22 . 
     The proximal end  40  of the manipulator  34  may include a handle member  44 . Handle member  44  may include one or more finger grips  45  which permit a user to grasp and thereby advance (e.g., translate) the distal end  38  of the manipulator within the lumen  32  of the delivery catheter  26 . In other words, by grasping and manipulating the handle  44 , a user may be able to translate the manipulator  34  along the longitudinal axis of the delivery catheter  26 . The handle design illustrated in  FIG. 1  is a schematic. Other handle designs are contemplated. For example, handle designs that include different grip arrangements, ergonomic features, etc. that may be utilized with the tissue retraction system  10  (and components thereof) described herein are contemplated. 
     The distal end  38  of the manipulator  34  may include a grasping member  39  (e.g., forceps, jaws, etc.). When positioned within the lumen  32  of the delivery catheter  26 , the grasping member  39  may be in a closed position (e.g., the jaws of the grasping member  39  may be closed and contacting one another). Further, the handle member  44  may be designed to control the opening and/or closing of the grasping member  39 . In other words, when the grasping member  39  is advanced to a position outside of the lumen  32  of the delivery catheter  26 , a user may manipulate the handle member  44  to open and/or close the grasping member  39 . 
     As described above, the manipulator  34  may be utilized to deploy the tissue retraction device  22  out of the distal end  28  of the delivery catheter  26 . Specifically, it can be appreciated that, when positioned adjacent to tissue target  50 , a user may advance the manipulator  34  in a proximal-to-distal direction within the lumen  32  of the delivery catheter  26  such that the grasping member  39  may contact and push the proximal end of the tissue retraction device  22  out of the distal end  28  of the delivery catheter  26 . 
     In at least some examples contemplated herein, the manipulator  34  and the tissue retraction device  22  may be positioned within the delivery catheter  26  as depicted in  FIG. 1  prior to the delivery catheter  26  being advanced through the lumen  21  of the medical device  18 . In other words, in some examples, both the manipulator  34  and the tissue retraction device  22  may be “pre-loaded” into the delivery catheter  26  prior to being inserted and advanced through the working channel  21  of the medical device  18  to a position adjacent to target tissue  50 . In other examples, however, only the tissue retraction device  22  may be preloaded into the delivery catheter  26  and advanced within the lumen  21  of the medical device  18  to a position adjacent to target tissue  50 , after which the manipulator  34  may be separately inserted into the lumen  21  of the medical device  18  and advanced to a position in which grasping member  39  is adjacent and/or contacting the proximal end of the tissue retraction device  22 . 
     It can be appreciated from the above discussion that the tissue retraction system  10  may be designed such that the delivery catheter  26  and the manipulator  34  may be moved (e.g., translated, rotated, etc.) relative to one another. For example, once the distal end  28  of the delivery catheter  26  is positioned adjacent to the target tissue  50  (with the manipulator  34  positioned adjacent to the distal end of the tissue retraction device  22 ), a user may grasp both the control member  42  and the handle member  44 . This may permit the user to maintain the distal end  28  of the delivery catheter  26  in a fixed position while advancing the manipulator  34  in a distal direction such that the grasping member  39  moves distally relative to the distal end  28  of the delivery catheter  26 . It can be appreciated that this relative movement may push the tissue retraction device  22  out of the distal end  28  of the delivery catheter  26 . 
     In other examples, it can be appreciated that instead of a user advancing the manipulator  34  in a distal direction to deploy the tissue retraction device  22 , the user may, alternatively, retract the delivery catheter  26  while maintaining the manipulator  34  in a fixed position. The retraction of the delivery catheter  26  may “uncover” the tissue retraction device  22 , thereby releasing it from the lumen  32  of the delivery catheter  26 . 
       FIG. 2  illustrates an example tissue retraction device  22 . The tissue retraction device  22  may include one or more engagement members  51  (e.g., clip, clasp, fastener, clamp, etc.). For example,  FIG. 2  illustrates that the tissue retraction device  22  may include a first engagement member  52   a  and a second engagement member  52   b . The first engagement member  52   a  may include a first end  54   a  and a second end  56   a . The first end  54   a  may include one or more jaws  61   a  (e.g., end effectors). The jaws  61   a  may be designed such that they move relative to one another.  FIG. 2  further illustrates that the second end  56   a  of the first engagement member  52   a  may include a spring  60   a . It can be appreciated that the spring  60   a  may be designed to provide a compressive force that is translated through the body of the first engagement member  52   a  to the jaw members  61   a , thereby biasing the jaw members  61   a  in a closed position (e.g., a position in which the jaw members  61   a  are contacting one another). 
     In some examples, the ends of the jaw members  61   a  may not necessarily contact one another while in a closed position. The jaw members  61   a  may be spaced apart from one another while in a closed position. Spacing the jaw members  61   a  apart from one another while in a closed position may permit additional compressive force to be generated when in contact with tissue. This additional compressive force could be termed “preload.” The range of preload forces could vary from about 5 grams of force to about 200 grams of force, or about 15 grams of force to about 40 grams of force. 
     It can be appreciated that the engagement members  51  depicted in the examples disclosed herein are schematic. In other words, it is contemplated that the engagement members  51  described herein may include alternative design arrangements, features, geometries etc. without departing from the scope of the examples contemplated herein. For example, it is contemplated that the spring  60   a  of the first engagement member  52   a  may be positioned between the first end  54   a  and the second end  56   a  of the first engagement member  52   a ). Additionally, it is contemplated that the jaws (e.g., end effectors) may have a variety of different shapes and/or geometries without departing from the scope of the examples contemplated herein. Other variations are contemplated. 
       FIG. 2  further illustrates that the first engagement member  52   a  may include one or more gripping members  58   a . For example,  FIG. 2  illustrates that the gripping member  58   a  may be formed from the same material as the jaw member  61   a . In other words, the jaw  61   a  and the gripping member  58   a  may be formed as a monolithic component. For example, the jaws  61   a  (e.g., end effectors) and the gripping members may be metal injection molded (MIM), conventionally machined, stamped, additive manufactured or the like. However, this is not intended to be limiting. Rather, it is contemplated that the jaw  61   a  and the gripping member  58   a  may be formed as two separate components which are attached (e.g., welded, glued, press fit, etc.) together to form the structure shown in  FIG. 2 . Additionally,  FIG. 2  illustrates that, in some examples, a portion of the gripping member  58   a  may be designed to engage, mate, interconnect, attached to, etc. the spring  60   a . For example,  FIG. 2  illustrates a portion of the spring  60   a  extending into a channel of the gripping member  58   a . The spring  60   a  may be rigidly attached (e.g., weld, affixed, etc.) to the gripping member  58   a.    
     As described above, after the tissue retraction device  22  has been deployed out of the distal end  28  of the delivery catheter  26 , the manipulator  34  may be utilized to position and/or attach the tissue retraction device  22  to the target tissue  50  within body lumen  16 . It can be appreciated that the gripping members  58   a  may be designed to engage the grasping member  39  (located on the distal end  38  of the manipulator  34 ). In other words, the gripping members  58   a  may provide an interface for which the grasping member  39  may engage, attach, grip, grab, capture, etc. the first engagement member  52   a.    
     Furthermore, the gripping members  58   a  may be designed such that they permit the manipulator  34  to efficiently acquire, position (and/or reposition), and open/close the jaws  61   a  of the first engagement member  52   a . While  FIG. 2  depicts the gripping members  58   a  positioned between the first end  54   a  and/or the second end  56   a  of first engagement member  52   a , it is contemplated that the gripping members  58   a  may be located along other portions of first engagement member  52   a . For example, the gripping members  58   a  may be positioned on the first end  54   a  and/or the second end  56   a  of first engagement member  52   a.    
     As discussed above, the tissue retraction device  22  may include more than one tissue engagement member (e.g., another engagement member in addition to the first tissue engagement member  52   a  described above). For example,  FIG. 2  illustrates that the tissue retraction device  22  may include a second tissue engagement member  52   b . The second tissue engagement member  52   b  may be similar in form and function to the first tissue engagement member  52   a . For example, the second tissue engagement member  52   b  may include a first end  54   b  and a second end  56   b . The first end  54   b  may include one or more jaws  61   b . The jaws  61   b  may be designed such that they move relative to one another.  FIG. 2  further illustrates that the second end  56   b  of the second tissue engagement member  52   b  may include a spring  60   b . It can be appreciated that the spring  60   b  may be designed to provide a compressive force that is translated through the body of the second engagement member  52   b  to the jaw members  61   b , thereby biasing the jaw members  61   b  in a closed position (e.g., a position in which the jaw members  61   b  are contacting one another). It can be appreciated that the second engagement member  52   b  depicted in the examples disclosed herein is schematic. In other words, it is contemplated that the second engagement member  52   b  described herein may include alternative design arrangements, features, geometries, etc. without departing from the scope of the examples contemplated herein. For example, it is contemplated that the spring  60   b  of the second engagement member  52   b  may be positioned between the first end  54   b  and the second end  56   b  of the second engagement member  52   b ). Other variations are contemplated. 
       FIG. 2  further illustrates that the first engagement member  52   a  may include one or more gripping members  58   b . For example,  FIG. 2  illustrates that the gripping member  58   b  may be formed from the same material as the jaw member  61   b . In other words, the jaw  61   b  and the gripping member  58   b  may be formed as a monolithic component. For example, the jaws  61   a  (e.g., end effectors) and the gripping members may be metal injection molded (MIM), conventionally machined, stamped, additive manufactured or the like. However, this is not intended to be limiting. Rather, it is contemplated that the jaw  61   a  and the gripping member  58   a  may be formed as two separate components which are attached (e.g., welded, glued, press fit, etc.) together to form the structure shown in  FIG. 2 . Additionally,  FIG. 2  illustrates that, in some examples, a portion of the gripping member  58   b  may be designed to engage, mate, interconnect, attached to, etc. the spring  60   b . For example,  FIG. 2  illustrates a portion of the spring  60   b  extending into a channel of the gripping member  58   b . The spring  60   b  may be rigidly attached (e.g., weld, affixed, etc.) to the gripping member  58   b.    
       FIG. 2  further illustrates that the tissue retraction device  22  may include one or a tether  62  (depicted as the dashed line in  FIG. 2 ) coupled to the first engagement member  52   a , the second engagement member  52   b  or both the first engagement member  52   a  and the second engagement member  52   b . The tether  62  may be a tubular member having a lumen extending therein. The tether  62  may be referred to as an elastic member, band, rope, cord, leash, strap, strand, etc. The tether  62  may include a variety of cross-sectional geometries. For example, the tether may be circular, rectangular, triangular, or the like. Further, the tether  62  may be bioabsorbable. 
     In at least some examples, the tether  62  may be elastomeric. In some examples, the tether  62  may be constructed from an elastomeric material such as latex, Nitrile® rubber, ethylene propylene diene rubber, silicone rubber, chloroprene, polychloroprene (e.g., Neoprene®), polyolefin, thermoplastic elastomer, polyisoprene, etc. 
     The tether member  62  may elongate from a first, unelongated (e.g., relaxed) position to a second, elongated position. It can be appreciated that when the tissue retraction device  22  is in an elongated position, the tissue elongation device is in tension, and therefore includes a retraction force which is pulling the first engagement member  52   a  toward the second engagement member  52   b  along the longitudinal axis of the tissue retraction device  22 . 
     As described above, prior to being deployed from the delivery catheter  26 , the tissue retraction device  22  may be positioned in an unelongated, relaxed state within the distal end  28  of the delivery catheter. Furthermore, proper alignment of the tissue retraction device  22  within the delivery catheter  26  (prior to deployment) must be maintained to ensure that the tissue retraction device  22  is efficiently deployed within the body lumen  16 . For example, it is important to prevent the tissue retraction device  22  from folding and/or wrapping upon itself (e.g., folding back on itself) while being advanced and/or manipulated within the distal end  28  of the delivery catheter  26 . 
       FIG. 2  illustrates that in some examples, the tissue retraction device  22  may include a support member  64 . In some instances, the support member  64  may be a tubular member having a lumen  53  extending therein. For example, the tissue retraction device  22  shown in  FIG. 2  illustrates the tether member  62  extending within the lumen  53  of the support member  64 . Additionally,  FIG. 2  illustrates that the support member  64  may extend between (e.g., be positioned between) the first tissue engagement member  52   a  and the second tissue engagement member  52   b . While  FIG. 2  depicts the support member  64  as a tubular member, other cross-sectional shapes of support member  64  are contemplated. For example, the cross-sectional shape of the support member  64  may be rectangular, triangular, ovular, square, or the like. Additionally, it is contemplated that the tissue retraction device  22  may include more than one support member  64 . For example, the tissue retraction device  22  may include 1, 2, 3, 4 or more support members. 
     As described above,  FIG. 2  shows that the support member  64  may be disposed along the tether member  62 . For example, in some examples the tether member  62  may extend through the lumen  53  of the support member  64 . In at least some examples, the support member  64  may permit the tether  62  to compress into the lumen  53  of the support member  64 . Therefore, diameter of the lumen  53  of the support member  64  may be wide enough to permit the tether  62  to curl upon itself to be “stored” within the lumen of the support member  64 . Allowing the tether  62  to be stored within the lumen of the support member  64  may prevent the tether  62  from being entangled with the first engagement member  52   a.    
     Additionally, in at least some examples described herein, the support member  64  may include sufficient stiffness and column strength to withstand compression during packaging and storage prior to device delivery. Possible materials include polypropylene, PET, thermoplastic elastomers (TPE), polyethylene (PE), or high density polyethylene (HDPE) such as Celanese GUR HOSTALLOY  731 . 
       FIG. 2  further illustrates that the tether  62  may be coupled to the tissue engagement member  52   a  via a coupler body  36   a  and a connection member  46   a . As will be described in greater detail below, the connection member  46   a  may include a post member  48   a  and an attachment member  47   a .  FIG. 2  further illustrates that a proximal end of the coupler body  36   a  may extend within the lumen  53  of the tether member  62 . A compression member  49   a  may be positioned overtop both the proximal end of the coupler body  36   a  and the tether  62 , whereby the compression member  49   a  may radially compress the tether  62  onto the proximal end of the coupler body  36   a  with sufficient force to fixedly attach the tether  62  to the coupler body  36   a . In other words, the tether  62  may be attached to the coupler body  36   a  by “sandwiching” the tether  62  between the coupler body  36   a  and the compression  49   a . The compression member  49   a  may include a variety of different structures without departing from the scope of the examples contemplated herein. For example, the compression member  49   a  may include a compression ring, a suture, a clamp, a string, a knot, a crimped ultrasonic weld, a loop, etc. 
     As will be described in greater detail below, the post member  48   a  may extend through an aperture  57   a  formed in the coupler body  36   a , whereby a proximal end of the post member  48   a  may be prevented from being pulled through the aperture  57   a . In other words, as will be illustrated in  FIG. 3  below, the post member  48   a  may include a proximal end which is designed to allow the post member  48   a  to rotate while preventing the post member  48   a  from separating from the coupler body  36   a.    
     Additionally,  FIG. 2  illustrates that the distal end of post member  48   a  may be attached to the attachment member  47   a . For example,  FIG. 2  illustrates that the attachment member  47   a  may include a curved portion (e.g., a substantially C-shaped portion), which may resemble a partial ring.  FIG. 2  further illustrates that the attachment member  47   a  may extend through the looped portion of the spring  60   a , thereby coupling the attachment member  47   a  to the tissue engagement member  52   a  via the spring  60   a . Additionally,  FIG. 2  illustrates that the attachment member  47   a  may be attached to the distal end of the post member  48   a , thereby coupling the attachment member  47   a  to the coupler body  36   a  via the post member  48   a . It can be appreciated, therefore, that the connection member  46   a  (which includes the attachment member  47   a  and the post member  48   a ) together with the coupler body  36   a  and the compression ring  49   a , may couple the tissue engagement member  52   a  to the tether member  62 . 
     It is noted that be above description my also apply to coupling the second tissue engagement member  52   b  with the tether  62 . For example, the second tissue engagement member  52   b  may be coupled to a coupler body  36   b  via a connection member  46   b . Similar to that described above, the connection member  46   b  may include an attachment member  47   b  and a post member  48   b . The attachment member  47   b  may be coupled to the spring  60   b . Additionally, the attachment member  47   b  may be attached to the post member  48   b . The post member  48   b  may extend through an aperture  57   b  (not visible in  FIG. 2 ) in the coupler body  36   b , as described above. Further, the tether  62  may be attached to the coupler body  36   b  via radial compression of the compression ring  49   b  onto the coupler body  36   b.    
       FIG. 3  is an exploded view of one end of the tissue retraction device  22  described above.  FIG. 3  illustrates the individual components utilized to couple the tether member  62  to the tissue engagement member  52   a , as described above. For example,  FIG. 3  illustrates the tissue engagement member  52   a , which includes spring  60   a . As shown in  FIG. 3 , the spring  60   a  may include a coiled portion through which the attachment member  47   a  may extend. As described above and further illustrated in  FIG. 3 , the attachment member  47   a  may include a curved portion  75   a  which resembles a partial ring. Additionally, the attachment member  47   a  may include an opening  67   a  which, for purposes of assembly, may permit the attachment to be inserted into the coiled portion of the spring  60   a.    
       FIG. 3  further illustrates both the compression member  49   a  and the coupler body  36   a . In some examples the coupler body  36   a  may include a channel  55   a  which extends circumferentially around the coupler body  36   a . The channel  55   a  may be designed to mate with the compression member  49   a . For example, the width, depth and/or profile of the channel  55   a  may mate with the width, thickness and/or profile of the compression member  49   a . As described above, the tether  62  may be radially compressed between the coupler body  36   a  and the compression member  49   a  to fixedly attach the tether  62  to the coupler body  36   a.    
     Additionally,  FIG. 3  illustrates that the coupler body  36   a  may include an aperture  57   a  through which the post member  48   a  may extend. The diameter of the aperture  57   a  is depicted as “X 1 ” in  FIG. 3 . Additionally,  FIG. 3  illustrates that the post member  48   a  may include a first end region  59   a  and a second end region  63   a . The second end region  63   a  of the post member  48   a  may include a tapered portion. The tapered portion may include a diameter “Y 1 ” which is greater than the diameter X 1  of the aperture  57   a . It can be appreciated that the post member  48   a  may include a length which permits the post member  48   a  to extend through the aperture  57   a  whereby the first end region  59   a  may be fixedly attached to the attachment member  47   a . For example, the first end region  59   a  of the post member  48   a  may be welded to the attachment member  47   a . It can further be appreciated that after the post member  48   a  is extended through the coupler body  36   a  and attached to the attachment member  47   a , the coupler body  36   a  may be coupled to the attached combination of the attachment member  47   a  and the post member  48   a.    
       FIG. 3  further illustrates that the lumen  53  of the tether  62  may be sized such that it may be positioned over a portion of the coupler body  36   a . For example, the tether  62  may be positioned overtop the proximal portion of the coupler body  36   a  such that a portion of the tether  62  may be positioned along the channel  55   a . As described above, the compression member  49   a  may be positioned overtop the tether  62  such that it radially compresses the tether  62  onto the coupler body  36   a , thereby attaching the tether  62  to the coupler body  36   a.    
       FIG. 4  illustrates an example tissue engagement member  52   a . As discussed above, the tissue engagement member  52   a  may include a jaw members  61   a , gripping members  58   a  and a coiled spring  60   a .  FIG. 4  further illustrates that the spring portion  60   a  may include one or more stems  68   a  that engage (e.g., mate) with a groove portion  69   a  located in the gripping member  58   a . It is contemplated that the stems  68   a  may be attached within the groove  69   a  with a variety of techniques. For example, the stem  68   a  may be welded, press fit, glued, etc. within the groove portion  69   a.    
     Additionally,  FIG. 4  illustrates that the jaws  61   a  may each include one or more teeth  65 . It can be appreciated that the teeth  65  may include a variety of different of shapes which are oriented in a variety of different configurations. Each jaw  61   a  illustrated in  FIG. 4  may include two teeth  65 , wherein the teeth  65  of one jaw  61   a  may mirror the teeth  65  of the other jaw  61   a . In other words, the teeth  65  of the “top” jaw may be aligned with the teeth  65  of the “bottom” jaw. Further,  FIG. 4  illustrates that the particular arrangement of the teeth results in an aperture  66  located in a central region of the teeth  65 . Furthermore, it can be appreciated that the jaws  61   a  may be designed to exhibit a slope facing the coiled portion  60   a  of the first engagement member  52   a . For example,  FIG. 4  illustrates that the “face” of each jaw  61   a  defining each of the teeth  65  may be sloped inward at an angle, depicted as “0” in  FIG. 4 .  FIG. 4  illustrates that the angle may create a sharp point that may engage tissue more aggressively. The direction of the slope enhances tissue engagement by discouraging captured tissue from disengaging. 
       FIG. 5  illustrates another example tissue retraction device  122 . The tissue retraction device  122  may be similar in form and function to the tissue retraction device  22  described above. For example, the tissue retraction device may include a first tissue engagement member  52   a  (including jaws  61   a , gripping members  58   a  and spring  60   a ) and a second tissue engagement member  52   b  ((including jaws  61   b , gripping members  58   b  and spring  60   b ). Additionally, the first tissue engagement member  52   a  may be coupled to a tether  62  via a connection member  146   a  and a coupler body  136   a . Similarly, the second tissue engagement member  52   b  may be coupled to the tether  62  via a connection member  146   b  and a coupler body  136   b . As discussed above, the tissue retraction device  122  may include a support member  64  disposed along the tether  62 . 
       FIG. 6  is an exploded view of one end of the tissue retraction device  122  described above. Similar to that described above with respect to  FIG. 3 ,  FIG. 6  illustrates the individual components utilized to couple the tether  62  to the tissue engagement member  52   a  shown in  FIG. 5 . For example,  FIG. 6  illustrates the tissue engagement member  52   a , which includes the gripping members  58   a  and the spring  60   a . Additionally,  FIG. 6  illustrates the tether  62  including the lumen  53  extending therein. However,  FIG. 6  further illustrates the individual components of the connection member  146   a  (described in  FIG. 5 ) and which, in conjunction with the coupler body  136   a , couple the tissue engagement member  52   a  with the tether  62 . 
     To that end, the connection member  146   a  (described in  FIG. 5 ) may include a post member  148   a , a first fitting  167   a  and a second fitting  168   a . The post member may include a first end  159   a  and a second end  163   a . It can be appreciated that the first fitting  167   a  and the second fitting  168   a  may be designed to mate with one another. In other words, the first fitting  167   a  and the second fitting  168   a  may be two separate components which “snap” together to form a single component. Additionally, it can be further appreciated that the first fitting  167   a  and the second fitting  168   a  may include one or more “voids” or “protrusions” which are designed to capture both the coiled portion of the spring  60   a  and a projection  170   a  located on the first end  159   a  of the post member  148   a.    
     For example, the projection  170   a  may be designed to engage a void  171   a , half of which is formed in the first fitting  167   a  and half of which is formed in the second fitting  168   a  (it is noted that the half of the void  171   a  formed in the first fitting  167   a  cannot be seen in  FIG. 6 ). Additionally,  FIG. 6  illustrates a first protrusion  172   a  extending outward from the second fitting  168   a  which is designed to mate with a second protrusion  173   a  extending outward from the first fitting  167   a . As discussed above, the first protrusion  172   a  and the second protrusion  173   a  may be designed to interlock within one another through an opening  174   a  formed in the spring portion  60   a , thereby capturing the spring portion  60   a  between the first fitting  167   a  and a second fitting  168   a.    
     Additionally,  FIG. 6  illustrates that the coupler body  136   a  may include an aperture  157   a  through which the post member  148   a  may extend. The diameter of the aperture  157   a  is depicted as “X2” in  FIG. 6 . Additionally,  FIG. 6  illustrates that the post member  148   a  may include a first end region  159   a  and a second end region  163   a . The second end region  163   a  of the post member  148   a  may include an enlarged portion. The enlarged portion may include a diameter “Y2” which is greater than the diameter X2 of the aperture  157   a . It can be appreciated that the post member  148   a  may include a length which permits the post member  148   a  to extend through the aperture  157   a , whereby the projection  170   a  of the first end region  159   a  may be fixedly attached with the void  171   a  formed via the first fitting  167   a  and the second fitting  168   a . It can further be appreciated that after the post member  148   a  is extended through the coupler body  136   a  and attached to the first fitting  167   a  and the second fitting  168   a , the coupler body  136   a  may be coupled to the attached combination of the first fitting  167   a , the second fitting  168   a  and the post member  148   a.    
       FIG. 6  further illustrates that the lumen  53  of the tether  62  may be sized such that it may be positioned over a portion of the coupler body  136   a . For example, the tether  62  may be positioned overtop the proximal portion of the coupler body  136   a  such that a portion of the tether  62  may be positioned along a channel  155   a  (extending circumferentially around the coupler body  136   a ). As described above, a compression member (e.g., compression ring, suture, band, clamp, etc.) may be positioned overtop the tether  62  such that it radially compresses the tether  62  onto the coupler body  136   a , thereby attaching the tether  62  to the coupler body  136   a.    
       FIGS. 7-9  illustrate different example tissue engagement members. The tissue engagement members illustrated in  FIGS. 7-9  may differ in size, shape, geometry, etc. without departing from the scope of the examples contemplated herein. For example, the particular shape and geometries of the end effectors (e.g., jaws, teeth, gripping members, etc.) disclosed herein may be different. However, it is contemplated that any of the features disclosed with respect to an example tissue engagement member may be compatible with any other tissue engagement member disclosed herein. 
       FIG. 7  illustrates another example tissue engagement member  251 . The tissue engagement member  251  may be similar in form and function to the tissue engagement member  51  described above. For example, the tissue engagement member  251  may include jaws  261 , gripping members  258  and a spring  260 . Additionally,  FIG. 7  illustrates that each of the jaws  261  may include a single, flat tooth  265 , wherein each tooth  265  faces the other. As described above with respect to the tissue engagement member  52   a  shown in  FIG. 4 , each tooth  265  may be sloped such that it is angled toward the coiled portion  260 . The direction of the slope enhances tissue engagement by discouraging captured tissue from disengaging. 
       FIG. 8  illustrates another example tissue engagement member  351 . The tissue engagement member  351  may be similar in form and function to other tissue engagement members described above. For example, the tissue engagement member  351  may include jaws  361 , gripping members  358  and a spring  360 . Additionally,  FIG. 8  illustrates that the “top” jaw  361  of  FIG. 8  may include a first tooth  365  and a second tooth  375 , wherein the first tooth  365  is wider than the second tooth  375 . Additionally, the first tooth  365  may be spaced away from the second tooth  375  to create a gap  366  between the first tooth  365  and the second tooth  375 . Similarly, the “bottom” jaw  361  of  FIG. 8  may include a first tooth  365  and a second tooth  375 , wherein the first tooth  365  is wider than the second tooth  375 . Additionally, the first tooth  365  may be spaced away from the second tooth  375  to create a gap  366  between the first tooth  365  and the second tooth  375 . Additionally, it can be appreciated that the teeth may be arranged such that the first tooth  365  of the top row is aligned with the gap  366  of the bottom row, while the first tooth  365  of the bottom row is aligned with the gap  366  of the top row. In other words, teeth of the top row are designed to interdigitate with the teeth of the bottom row. 
     Furthermore, it can be appreciated that each of the first teeth  365  and each of the second teeth  375  may be sloped such that they are angled toward the coiled portion  360  (as described above with respect to other tissue engagement members). The direction of the slope enhances tissue engagement by discouraging captured tissue from disengaging. 
       FIG. 9  illustrates another example tissue engagement member  451 . The tissue engagement member  451  may be similar in form and function to other tissue engagement members described above. For example, the tissue engagement member  451  may include jaws  461 , gripping members  458  and a spring  460 . Additionally,  FIG. 9  illustrates that the jaw  461  may each include one or more teeth  465 . It can be appreciated that the teeth  465  may include a variety of different of shapes which are oriented in a variety of different configurations. Each jaw  461  illustrated in  FIG. 9  may include two teeth  465 , wherein the teeth  465  of one jaw  461  may mirror the teeth  465  of the other jaw  461 . In other words, the teeth  465  of the “top” jaw may be aligned with the teeth  465  of the “bottom” jaw. Further,  FIG. 9  illustrates that the particular arrangement of the teeth  465  results in an aperture  466  located in a central region of the teeth  465 . 
     Furthermore, as described above with respect to other tissue engagement members, each tooth  465  may be sloped such that it is angled toward the coiled portion  460 . The direction of the slope enhances tissue engagement by discouraging captured tissue from disengaging. 
       FIGS. 10-14  illustrate a series of steps to deploy and utilize the tissue retraction system  10  described above. The tissue retraction device  22  may be utilized to lift and reposition target tissue which has been dissected by a clinician. As will be made clear by the following illustrations, as the clinician cuts away target tissue, the tissue retraction device may lift and reposition it, thereby providing the clinician with an unobstructed view of the ongoing procedure. 
       FIG. 10  illustrates a first step in utilizing the tissue retraction system  10  in a dissection procedure. As described above and illustrated in  FIG. 10 , the clinician may first advance the manipulator  34  in a proximal-to-distal direction (relative to the distal end  28  of the delivery catheter  26 ). This forward movement of the manipulator will force the grasping member  39  of the manipulator to push the tissue retraction device  22  forward and out the distal end  28  of the delivery catheter  26 .  FIG. 10  illustrates the tissue retraction device  22  having been advanced out of the distal end  28  of the delivery catheter  26 , whereby it is positioned adjacent to the tissue target  50  (e.g., a cancerous lesion). 
       FIG. 11  illustrates an example second step in utilizing the tissue retraction system  10  in a dissection procedure.  FIG. 11  illustrates that a clinician may manipulate the distal end  38  of the manipulator  34  to grasp the first engagement member  52   a  (for clarity, the grasping member  39  is shown in a closed configuration in  FIG. 11 . It can be appreciated that the grasping member  39  may open up to grasp the first engagement member  52   a ). For example, the clinician may manipulate the handle  44  of the tissue retraction system  10  to open the jaws of the grasping member  39 . Once opened, the jaws of the grasping member may engage the gripping members  58   a  of the first engagement member  52   a . After engaging the gripping members  58   a , the clinician may close the jaws of the grasping member  39 , thereby opening the jaws  61   a  of the first engagement member  52   a . Using the grasping member  39 , the clinician may then position the jaws  61   a  onto the surface of the target tissue  50 . By releasing the grasper  39  from the gripping members  58   b , the jaws  61   a  of the first engagement member  52   a  may close and attach the jaws  61   a  (and, by extension, the first engagement member  52   a ) to the surface of target tissue  50 . 
       FIG. 12  illustrates an example third step in utilizing the tissue retraction system  10  in a dissection procedure.  FIG. 12  illustrates that a clinician may manipulate the distal end  38  of the manipulator  34  to grasp the second engagement member  52   b  (for clarity, the grasper  39  is shown in a closed configuration in  FIG. 12 ). It can be appreciated that the grasper  39  may open up to grasp the second engagement member  52   b . For example, the clinician may manipulate the handle  44  (described above) of the tissue retraction system  10  to open the jaws of the grasper  39 . Once opened, the jaws of the grasper may engage the gripping members  58   b  of the second engagement member  52   b . After engaging the gripping members  58   b , the clinician may close the jaws of the grasper  39 , thereby opening the jaws  61   b  of the second engagement member  52   b . The clinician may then pull on the second engagement member  52   b , thereby lengthening the tissue retraction device  22  (as described above with respect to  FIG. 2A  and  FIG. 3 ). Once the tissue retraction device is elongated to a desired length (which may be confirmed visually via reference markers  66  as described above), the clinician may position the jaws  61   b  of the second engagement member  52   b  onto the surface of the target tissue site  50 . By releasing the grasping member  39  from the gripping members  58   b , the jaws  61   b  of the second engagement member  52   b  may close, thereby attaching the jaws  61   b  (and, by extension, the second engagement member  52   b ) to the inner surface of body lumen  16 . 
       FIG. 13  illustrates an example fourth step in utilizing the tissue retraction system  10  in a dissection procedure.  FIG. 13  illustrates that after the tissue retraction device  22  has been attached to both the target tissue site  50  and to the inner surface of the body lumen  16  at a position spaced away from the target tissue site (which places the tissue retraction device  22  in tension), the clinician may exchange the manipulator  34  for a cutting tool  74 . The cutting tool  74  may include a cutting member  76  positioned at the target tissue  50 . Further, the cutting tool  74  may be advanced within the working channel  21  of the medical device  18  as described above. 
       FIG. 14  illustrates an example fifth step in utilizing the tissue retraction system  10  in a dissection procedure.  FIG. 14  illustrates the clinician performing the tissue dissection by utilizing the cutting tool  74  to cut a portion of the target tissue  50 . As can be appreciated from  FIG. 14 , as the cutting tool  74  cuts a portion of the target tissue  50 , the tissue retraction device  22  retracts (via the retraction of tether members  62   a / 62   b ), and thereby lifts the dissected portion  78  of the target tissue  50  up and away from the plane of tissue being cut by the physician. By lifting and retracting the dissected portion  78  of the target tissue  50 , a clear, unobstructed view of the procedure is maintained for the clinician. It is noted that, if necessary, the engagement members  52   a / 52   b  of the tissue retraction system  10  may be repositioned. In other words, adjustments in tension and/or direction may be imparted into the tissue retraction system  10  as desired. 
     It should be noted that the features of any of the tissue retraction systems described with respect to particular figures and/or embodiments are not limited to that particular example. Rather, it is contemplated that all of the features or examples disclosed with respect to a single example may be incorporated into any other example disclosed herein. 
     The materials that can be used for the various components of tissue retraction system  10  and the various devices disclosed herein may include those commonly associated with medical devices. For simplicity purposes, to the extent the following discussion makes reference to tissue retraction system  10 , it is not intended to limit the devices and methods described herein only to tissue retraction system  10 , as the discussion may be applied to other similar devices disclosed herein. 
     Tissue retraction system  10  and/or other components of tissue retraction system  10  may be made from a metal, metal alloy, polymer (some examples of which are disclosed below), a metal-polymer composite, ceramics, combinations thereof, and the like, or other suitable material. Some examples of suitable polymers may include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, for example, DELRIN® available from DuPont), polyether block ester, polyurethane (for example, Polyurethane  85 A), polypropylene (PP), polyvinylchloride (PVC), polyether-ester (for example, ARNITEL® available from DSM Engineering Plastics), ether or ester based copolymers (for example, butylene/poly(alkylene ether)phthalate and/or other polyester elastomers such as HYTREL® available from DuPont), polyamide (for example, DURETHAN® available from Bayer or CRISTAMID® available from Elf Atochem), elastomeric polyamides, block polyamide/ethers, polyether block amide (PEBA, for example available under the trade name PEBAX®), ethylene vinyl acetate copolymers (EVA), silicones, polyethylene (PE), Marlex high-density polyethylene, Marlex low-density polyethylene, linear low density polyethylene (for example REXELL®), polyester, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polytrimethylene terephthalate, polyethylene naphthalate (PEN), polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), poly paraphenylene terephthalamide (for example, KEVLAR®), polysulfone, nylon, nylon-12 (such as GRILAMID® available from EMS American Grilon), perfluoro (propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefin, polystyrene, epoxy, polyvinylidene chloride (PVdC), poly(styrene-b-isobutylene-b-styrene) (for example, SIBS and/or SIBS 50A), styrene ethylene buthylene styrene (SEBS), Thermoplastic Elastomers (TPE) (such as Medalist® available from Teknor Apex and/or Mediprene® available from Hexpol TPE), polycarbonates, ionomers, biocompatible polymers, other suitable materials, or mixtures, combinations, copolymers thereof, polymer/metal composites, and the like. In some embodiments the sheath can be blended with a liquid crystal polymer (LCP). 
     Some examples of suitable metals and metal alloys include stainless steel, such as 304V, 304L, and 316LV stainless steel; mild steel; nickel-titanium alloy such as linear-elastic and/or super-elastic nitinol; other nickel alloys such as nickel-chromium-molybdenum alloys (e.g., UNS: N06625 such as INCONEL® 625, UNS: N06022 such as HASTELLOY® C-22®, UNS: N10276 such as HASTELLOY® C276®, other HASTELLOY® alloys, and the like), nickel-copper alloys (e.g., UNS: N04400 such as MONEL® 400, NICKELVAC® 400, NICORROS® 400, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such as MP35-N® and the like), nickel-molybdenum alloys (e.g., UNS: N10665 such as HASTELLOY® ALLOY B2®), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten or tungsten alloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like); platinum enriched stainless steel; titanium; combinations thereof; and the like; or any other suitable material. 
     In at least some embodiments, portions or all of tissue retraction system  10  and/or other components of tissue retraction system  10  may also be doped with, made of, or otherwise include a radiopaque material. Radiopaque materials are understood to be materials capable of producing a relatively bright image on a fluoroscopy screen or another imaging technique during a medical procedure. This relatively bright image aids the user of tissue retraction system  10  and/or other components of tissue retraction system  10  in determining its location. Some examples of radiopaque materials can include, but are not limited to, gold, platinum, palladium, tantalum, tungsten alloy, polymer material loaded with a radiopaque filler, and the like. Additionally, other radiopaque marker bands and/or coils may also be incorporated into the design of tissue retraction system  10  and/or other components of tissue retraction system  10  to achieve the same result. 
     In some embodiments, a degree of Magnetic Resonance Imaging (MRI) compatibility is imparted into tissue retraction system  10  and/or other components of tissue retraction system  10 . For example, tissue retraction system  10  and/or other components of tissue retraction system  10 , or portions thereof, may be made of a material that does not substantially distort the image and create substantial artifacts (e.g., gaps in the image). Certain ferromagnetic materials, for example, may not be suitable because they may create artifacts in an MRI image. Tissue retraction system  10  and/or other components of tissue retraction system  10 , or portions thereof, may also be made from a material that the MRI machine can image. Some materials that exhibit these characteristics include, for example, tungsten, cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such as MP35-N® and the like), nitinol, and the like, and others. 
     It should be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps without exceeding the scope of the disclosure. This may include, to the extent that it is appropriate, the use of any of the features of one example embodiment being used in other embodiments. The disclosure&#39;s scope is, of course, defined in the language in which the appended claims are expressed.