Tissue resection device and related methods of use

In accordance with an aspect of the present disclosure, the medical device includes a snare member having a proximal portion and a distal portion. The medical device also includes an operating member extending proximally of the snare member. The operating is enabled to extend and retract the snare member from a sheath. The snare member includes a transition portion extending between the proximal portion and the distal portion. The transition portion connects the proximal portion to the distal portion. The distal portion has a different cross-sectional area than the proximal section of the snare member.

SUMMARY

FIELD

Embodiments of the present disclosure relate generally to medical devices and procedures. In particular, embodiments of the present disclosure relate to medical devices and methods for tissue resection within the body of a patient.

BACKGROUND

A wide variety of medical techniques and instruments have been developed for diagnosis as well as treatment within the body of a patient, such as in the gastrointestinal (GI) tract. Medical procedures, including Endoscopic Mucosal Resection (EMR), Endoscopic Sub-mucosal Resection (ESR), Polypectomy, Mucosectomy, etc., are minimally invasive methods for severing and retrieving malignant and non-malignant lesions, e.g., polyps. Procedures such as, EMR involve resection of a lesion or unwanted tissue from a tissue wall within a body lumen. Snares have been commonly used during such medical procedures for resecting tissue from a target site. During resection procedures, physicians ensnare or capture a target tissue within a loop of the snare. Often, a physician may apply a downward force on the snare in an effort to improve snare traction around the target tissue and resect the target tissue closer to its base on the tissue wall. However, when such a downward force is applied, a distal portion of conventional snares have a tendency to deflect away from the tissue wall. Such snares may be stiff and may have insufficient traction on the tissue, and often require repeated efforts to resect the tissue before the procedure can be successfully completed. Stiffness may lead to deflection of the snare from the tissue wall, (e.g., deflection away from a tissue plane defined by the tissue wall). Also, deflection of the snare before resection can lead to an “angled cut” instead of an “even cut” (e.g., a cut substantially parallel to or coplanar with the tissue plane). As such, conventional snares conform poorly to the tissue plane during resection.

Furthermore, conventional snares often include a snare loop of uniform cross-section. As noted above, such snares tend to be stiff and deflect away from the tissue plane during resection. Additionally, the performance of such snares may suffer. For example, in embodiments employing electrosurgical energy, a uniform cross-section snare loop may include a greater surface area than a snare with a varied cross-section. A greater surface area may result in reduced current density delivered to the target tissue during cutting. Additionally, conventional thick (e.g., uniform cross-section) snare loops, due to their inherent stiffness, often require greater force to extend and retract the snare loop during a procedure, thereby reducing the smoothness and/or responsiveness of actuation by a physician. This, likewise, limits the geometry of the loop itself, since a round, open snare loop requires greater deformation in order to be drawn into a snare sheath, and stiff, opposing sides of the snare loop tend to twist away from the tissue plane during extension and refraction. Indeed, an excessively stiff snare loop can also increase risk of unintended tissue trauma and perforation.

A tool or device with increased flexibility and control for better functional performance and improved traction may provide consistent capture, excision, and/or removal of unwanted tissue without unintentionally damaging healthy surrounding tissue.

The exemplary features of the present disclosure are directed to improvements in tissue resection devices and methods.

Embodiments of the present disclosure relate to medical devices and methods for performing tissue resection.

In accordance with an aspect of the present disclosure, the medical device may include a snare member having a proximal portion and a distal portion. The medical device may also include an operating member extending proximally of the snare member. The operating member may be enabled to extend and retract the snare member. Further, the snare member may include a transition portion extending between the proximal portion and the distal portion. The transition portion may connect the proximal portion to the distal portion, wherein the distal portion may have a different cross-sectional area than the proximal section of the snare member.

The medical device may further include one or more of the following features: the cross-sectional area of the distal portion may be smaller than the cross-sectional area of the proximal portion and the cross-sectional shape of the distal portion may be circular and the cross-sectional shape of the proximal portion may be non-circular; at least one traction member that may extend along a first portion of the snare member, wherein the at least one fraction member may be a continuous spiral coiled around the first portion of the snare member; the at least one traction member may be a first traction member and the medical device may further include a second traction member extending along a second portion of the snare member opposite the first portion of the snare member, the second traction member may be a continuous spiral coiled around the second portion of the snare member; a plurality of traction members may be formed of a continuous piece of material with the snare member, wherein each of the plurality of traction members may be spaced from an adjacent traction member of the plurality of tractions members and may be configured to extend radially outwardly from the snare member; each of the plurality of traction members may have a cross-sectional shape selected from the following: rectangular, semi-circular, ovular, and polygonal, and wherein a first series of traction members is disposed on a first portion of the snare member and a second series of traction members is disposed on a second portion of the snare member opposite the first portion of the snare member; at least one of the plurality of traction members may have a different cross-sectional shape than at least one other of the plurality of traction members; and each of the plurality of the traction members may extend in the same direction outward from the snare member.

In accordance with another aspect of the present disclosure, a medical device may include a snare member having a proximal portion and a distal portion. The medical device may also include an operating member extending proximally of the snare member. The operating member may be configured to extend and retract the snare member. The snare member may include a transition portion extending between the proximal portion and the distal portion, connecting the proximal portion to the distal portion. The distal portion may be more flexible than the proximal section of the snare member.

The medical device may further include one or more of the following features: a cross-sectional area of the distal portion may be smaller than a cross-sectional area of the proximal portion, and a cross-sectional shape of the distal portion may be circular and a cross-sectional shape of the proximal portion may be non-circular; at least one traction member may extend along a first portion of the snare member, wherein the at least one fraction member may be a continuous spiral coiled around the first portion of the snare member; the at least one traction member may be a first traction member, the medical device may further include a second traction member which may extend along a second portion of the snare member opposite the first portion of the snare member, the second traction member may be a continuous spiral coiled around the second portion of the snare member; a plurality of traction members may be formed of a continuous piece of material with the snare member, each of the plurality of traction members may be spaced from an adjacent traction member of the plurality of traction members and may be configured to extend radially outwardly from the snare member; each of the plurality of the fraction members may have a cross-sectional shape selected from the following: rectangular, square, semi-circular, ovular, and polygonal, and a first series of traction members may be disposed on a first portion of the snare member and a second series of fraction members may be disposed on a second portion of the snare member opposite the first portion of the snare member; and at least one of the plurality of traction members may have a different cross-sectional shape than at least one other of the plurality of traction members.

In accordance with another aspect of the present disclosure, a method of forming a medical device may include forming a loop of a snare member. The snare member may have a proximal portion and a distal portion. The method may further include modifying the snare member to form a transition portion extending between the proximal portion and the distal portion. The transitional portion may connect the proximal portion to the distal portion. Modifying the snare member may include altering a cross-sectional area of the distal portion so as to be different than the cross-sectional area of the proximal portion.

The method may further include one or more of the following features: the cross-sectional area of the distal portion may be smaller than the cross sectional area of the proximal portion, and a cross-sectional shape of the distal portion may be circular and a cross-sectional shape of the proximal portion may be non-circular; forming at least first and second traction members, the first fraction member may extend along a first portion of the snare member, wherein the first traction member may be a continuous spiral coiled about the first portion of the snare member, the second traction member may extend along a second portion of the snare member opposite the first portion of the snare member, and the second traction member may be a continuous spiral coiled about the second portion of the snare member; forming a plurality of traction members which may be of a continuous piece of material with the snare member, each of the plurality of traction members may be spaced from an adjacent fraction member of the plurality of traction members and may be configured to extend radially outwardly from the snare member; and each of the plurality of the fraction members may have a cross-sectional shape selected from the following: rectangular, square, semi-circular, ovular, and polygonal, and a first series of traction members may be disposed on a first portion of the snare member and a second series of traction members may be disposed on a second portion of the snare member opposite the first portion of the snare member.

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 features. The objects and advantages of the claimed features will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.

DETAILED DESCRIPTION

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 will be used throughout the drawings to refer to the same or like parts. The term “distal” refers to the direction that is away from the user and into the patient's body. By contrast, the term “proximal” refers to the direction that is closer to the user and away from the patient's body.

Overview

Embodiments of the present disclosure relate to medical devices and methods of manufacture and use for resecting and/or retrieving unwanted tissue such as cancerous tissues or lesions within a patient's body. For example, tissue disposed on the mucosal walls of the colon, esophagus, stomach, or duodenum may be targeted. A physician may desire to resect the tissue in order to conduct a biopsy or other examination. It should be noted that medical devices presented in the present disclosure can be used both for resecting and for retrieving target tissue or objects. However, for convenience, the term “resection device” will be used throughout this application.

In some embodiments, a resection device may include a snare member, and an operating member. The resection device may be used in conjunction with an elongate sheath e.g., an endoscope, a snare sheath or the like. The elongate sheath may include a lumen extending from a proximal end to a distal end of the elongate sheath. The distal end of the elongate sheath may include a distal opening at which the lumen may terminate. The snare member may be configured to transition between a first collapsed configuration within the lumen of the elongate sheath, and a second expanded configuration in which the snare member is caused to extend outwards from the distal opening of the elongate sheath. The operating member may be configured to extend and retract the snare member such that the snare member may transition between the expanded and the collapsed configurations. The operating member may include an actuating mechanism such as a push-pull member extending proximally of the snare member. Exemplary push-pull members will be discussed in detail with reference to subsequent figures.

Embodiments

FIG. 1illustrates an exemplary resection device10, according to an embodiment of the present disclosure. The resection device10may include a snare member100and an operating member, which may be a push-pull member108. The snare member100may include a distal portion102, a proximal portion104, and one or more transition portions106extending between the proximal portion104and the distal portion102.

The distal portion102and the proximal portion104of the snare member100may have different cross-sectional areas. For example, the distal portion102of the snare member100may have a smaller cross-sectional area than that of the proximal portion104. The distal portion102, due to its smaller cross-sectional area may exhibit increased flexibility. In particular, the increased flexibility of the distal portion102may allow improved conformance of the snare member100to the tissue plane during a resection procedure. That is, since the distal portion102is more flexible than the proximal portion104, the distal portion102may bend and remain in contact with the tissue wall during a resection procedure. Said differently, the improved conformance of the snare member100with the tissue plane may allow distal portion102of the snare member100to deform and stay in contact with a tissue plane so as to capture the target tissue.

Variations in the cross-sectional area of the snare member100may be achieved by removing at least a portion of the material of the distal portion102through cutting, grinding, drawing, etching, machining, turning, stretching, hammering, and/or the like. In some embodiments, variations in cross-sectional area of the snare member100may be achieved by forming the distal portion102and the proximal portion104with materials having different material properties. For example, material variation could be achieved in a geometrically uniform or non-uniform cross-section snare member100by applying a heat-treating process to a portion (e.g., either the distal portion102or the proximal portion104) of the snare member100, or the snare member100may be constructed of varying materials that are welded and/or fused together. A combination of geometrical and material cross-sectional variations may be used for a more pronounced differentiation. For example, the snare loop100may be constructed of a first core material and a second coating material disposed about and co-extruded with the core material. The second coating material may be removed by any appropriate technique, such as, for example, grinding, turning, etching, etc., to form a reduced cross-sectional area distal portion102of snare member100.

In some embodiments, variations in cross-section of the distal portion102and the proximal portion104may be achieved by varying cross-sectional shapes of the distal portion102and the proximal portion104. For example, the distal portion102may have a circular or elliptical cross-sectional shape while the proximal portion104may have a rectangular or superelliptical cross-sectional shape. The cross-section of the distal portion102may allow it to be flexible and engage the tissue. However, the cross-section of the proximal portion104may provide suitable stiffness to enhance controllability and traction of the snare member100.

As noted above, one or more transition portions106may extend between the proximal portion104and the distal portion102. For example, two transition portions106, positioned at opposing sides of snare member100, may be employed as shown inFIG. 1. Transition portions106may be configured to bridge the proximal portion104to the distal portion102of snare member100. Transition portions106include a variable geometrical cross-section. The variable geometrical cross-section of transition portions106may include a cross-sectional change which may be abrupt, sharp, or sudden. However, in some embodiments, the change in the cross-sectional area of the transition portions106may be a gradual taper. In such cases, the tapering may be linear (e.g., flat) or concave (e.g., rounded, arcuate) so as to include a radius of curvature.

The snare member100may be a wire in the form of a loop configured for surrounding and thereby severing and/or retrieving undesirable tissue. In some embodiments, the snare member100can be a monofilament wire or a multifilament wire. The multifilament wire may be bonded, twisted together, crimped, and/or braided. In the illustrated embodiment, the snare member100may form a substantially circular loop shape. However, in some embodiments, the snare member100may be configured to have any suitable loop shape such as, but not limited to, oval, hexagonal, rectangle, square, irregular, polygonal, semicircular, octagonal or the like. Further, the snare member100can be formed using any suitable biocompatible material such as, but not limited to metals, polymers, alloys, or the like. Exemplary materials include steel, tungsten, NITINOL, or titanium, and so forth.

In some embodiments, the snare member100may be configured for electro-cauterization procedures. The snare member100and the push-pull member108may be formed from suitable conducting material, e.g., stainless steel, or NITINOL. The snare member100may be configured to transmit electric current within specific ranges and be able to withstand repeated heating cycles during electro-cauterization procedure. In some instances, the electric current passing through the reduced cross-sectional area of the distal portion102may be of higher density than the electric current passing through the proximal portion104having a larger cross-sectional area. Increased current density in the distal portion102may enable improved cutting of target tissue along the distal portion102.

The push-pull member108(also referred to as legs) of the snare member100may connect the snare member100to a handle (not shown) located on a proximal end (not shown) of the resection device outside the patient's body. The push-pull member108may be operable to extend and retract the snare member100and thereby transition the snare member100between the collapsed configuration and expanded configuration. For example, when a user applies an axial force in a distal direction through the handle, the push-pull member108may extend (e.g., push) the snare member100outwards from the elongate sheath (e.g., sheath420shown inFIG. 4), thus moving the snare member100into the expanded configuration. Similarly, when a user applies an axial force in a proximal direction through the handle, the push-pull member may retract (e.g., pull) the snare member100into the elongate sheath, thus moving the snare member100into the collapsed configuration. In some embodiments, the push-pull member108and the snare member100may be made of a continuous, e.g., monolithically formed unitary structure. However, in other embodiments, the push-pull member108and the snare member100may be discrete and coupled to one another using any suitable technique known in art. Exemplary techniques may include, welding, soldering, or heat bonding.

FIG. 2illustrates an exemplary resection device20including a plurality of traction members210, according to an embodiment of the present disclosure. While the embodiment ofFIG. 2illustrates a plurality of traction members210, it is understood that in some embodiments, a single traction member210may be incorporated. The snare member200may include a distal portion202and a proximal portion204. The distal portion202may have a cross-sectional area smaller than that of the proximal portion204as discussed above. Additionally, similarly to the embodiment ofFIG. 1, snare member200may include transition portions206extending between the distal portion202and the proximal portion204of the snare member200. Also, the snare member200may be coupled to push-pull member208. The push-pull member208may be operable to extend and retract the snare member200and thereby transition the snare member200between the collapsed configuration and expanded configuration.

In the embodiment shown inFIG. 2, the fraction members210may extend radially outward from the snare member200. The traction members210may be disposed on both the distal portion202and the proximal portion204of the snare member200. However, in some embodiments, the traction members210may extend only along the distal portion202. The traction members210may be designed such that traction (friction) between the snare member200and the target tissue may be enhanced. Increased traction between the fraction members210and the target tissue may facilitate improved gripping of the target tissue by the snare member200. The traction members210may also facilitate improved gripping of the target tissue due to an increase in surface area of the snare member200in contact with the target tissue.

The traction members210may be discrete projections such as circular rings/discs disposed on the distal portion202of the snare member200. Alternatively, traction members210may include any cross-sectional shape configured to engage tissue. For example, traction members210may include sharpened outer edges, or projections such as barbs, blades, conical protrusions, or teeth. In an embodiment, the traction members210may include rings and conical projections arranged in a pattern of alternating series over the distal portion202. The shapes and configurations of the traction members210discussed herein are exemplary in nature, and it is understood that various other cross-sectional shapes such as rectangular, square, semicircular, ovular, hexagonal, pentagonal may also be employed.

In some embodiments, the traction members210may be formed from a separate element and disposed over the distal portion202of the snare member200. The fraction members210may be temporarily or permanently coupled to the snare member200using any suitable technique such as but not limited to, welding, soldering, heat bonding, adhesive bonding, or the like. In addition, the traction members210may be comprised of tubular sections of material, such as nylon or polyolefin, that are configured to shrink or collapse when exposed to an energy source, such as heat or light, or chemical bath. The traction members210may also be applied by spraying or mask coating discrete sections of the distal portion202of the snare member200with a material to enhance traction, such as silicone or urethane. Alternatively, the traction members210may be integrally, e.g., monolithically formed with the snare member200. Techniques such as but not limited to, grinding, etching, drawing, and so forth, may be used to form the traction members210integrally with the snare member200.

In some embodiments, elements of the distal portion202of the snare member200may be coated, sprayed, or otherwise covered with a lubricious covering, such as polytetrafluoroethylene (PTFE), such that traction members210are the exposed (e.g. uncoated, masked, or uncovered) portions of the distal portion202.

FIG. 3illustrates an exemplary embodiment of a resection device30including one or more stress relief portions312, according to an embodiment of the present disclosure. The resection device may include a snare member300. The snare member300may include a distal portion302and a proximal portion304. The distal portion302may have a smaller cross-sectional area than that of the proximal portion304as discussed above. Additionally, similarly to the embodiment ofFIG. 1, snare member300may include transition portions306extending between the distal portion302and the proximal portion304of the snare member200. In this embodiment, the transition portions306may include a gradual taper. Also, the snare member300may be coupled to push-pull member308. The push-pull member308may extend and retract the snare member300and thereby transition the snare member300between the collapsed configuration and expanded configuration. Further, the snare member300may also include one or more traction members similar to the traction members210ofFIG. 2.

As noted above, the snare member300may include one or more stress relief portions312. In some embodiments, the stress relief portions312can be formed by removing small portions such as “corners” along an interior of the snare member300as shown inFIG. 3. Small portions of the snare member300may be removed by any appropriate means, such as, for example, cutting, etc. In operation, as the snare member300is tightened about target tissue by being pulled into a sheath or the like, it may transition from the expanded configuration into a partially collapsed configuration. That is, as the snare member300is pulled into the sheath, the snare member may transition from a fully expanded shape to a semi-expanded configuration in which the size of the snare member300extending distally of the sheath has been reduced. During such an operation, stress may be induced within the snare member300. Such stress, however, may be directed towards the stress relief portions312and away from remaining portions, e.g., segments314, of the snare member300. As such, the loop of snare member300may maintain the desired shape, e.g., rectangular shape as shown inFIG. 3, longer while being retracted into the sheath. In other words, since the snare member300concentrates stress along stress relief portions312while allowing segments314to be relieved of stress build up, the snare member300is enabled to maintain its desired shape for a longer range of motion between the fully expanded configuration and the collapsed configuration within the sheath.

In some embodiments, the stress relief portions312may be disposed along the entire length of the snare member300. In some embodiments, the snare member300may be shaped as a rectangular loop and include four stress relief portions312at the corners (e.g., points at which the snare loop changes directions) of the snare member300as shown inFIG. 3. In other embodiments, the snare member300may be hexagonal in shape and may include six stress relief portions312. The number of stress relief portions312discussed herein are exemplary in nature, and for a person skilled in the art it is understood that various number of stress relief portions312such as, two, three, four, five, six, seven, eight, nine or the like may be contemplated.

FIG. 4illustrates an exemplary embodiment of a resection device40having a variation in cross-sectional shape of a snare member400, according to an embodiment of the present disclosure. The design and other considerations described for the snare member100may optionally also apply to the snare member400. In one exemplary embodiment, the snare member400may include a distal portion402with a circular cross-sectional shape and a proximal portion404with a rectangular cross-sectional shape. As such, the distal portion402may exhibit increased flexibility relative to the proximal portion404. Primarily, the increased flexibility of the distal portion402may allow for improved conformance of the snare member400to the tissue plane during a resection procedure. The improved conformance of the snare member400with the tissue plane may allow distal portion402of the snare member400to deform and stay in contact with a tissue plane so as to capture the target tissue. Further, one or more transition portions406may extend between the proximal portion404and the distal portion402. In some embodiments, the proximal portion404and the distal portion402may be discrete elements coupled together at the transition portions406. Exemplary techniques for coupling the distal portion402and the proximal portion404may include, soldering, welding, thermal boding, or pressure bonding.

The snare member400may include a continuous traction member410that may facilitate the snare member400in improved gripping of the tissue by increasing the traction between the snare member400and the target tissue. The traction member410may extend radially in all directions along the snare member400. In some embodiments, the traction member410may be disposed over at least a portion of the distal portion402. In some embodiments, a pair of the traction members410may be disposed bilaterally on the distal portion402or on either side of the snare member400. In other embodiments, the traction member410may be present all along the snare member400i.e., on the proximal portion404as well as the distal portion402.

FIG. 5illustrates an enlarged view of a portion of the resection device40ofFIG. 4. The snare member400is shown in a straight configuration, e.g., prior to being formed into a rounded loop of snare member400. The distal portion402of the snare member400may have circular cross-sectional shape whereas the proximal portion404of the snare member400may have a rectangular cross-sectional shape. The transition portion406may be abrupt (e.g., sharp, nongradual) as it extends from the proximal portion404with rectangular cross-sectional shape to the distal portion402with circular cross-sectional shape. Alternatively, as described above, the transition portion406may comprise a gradual taper. The traction member410may extend distally from the transition portion406over at least a portion of the distal portion402in a helical, e.g., spiral arrangement so as to be continuous along its length. In some embodiments, the traction member410may be in the form of a double helical structure. In some embodiments, the traction member410may be arranged helically or spirally around a circumference of the snare member400along its complete length. The traction member410may be formed by any suitable technique such as, but not limited to, grinding, molding, machining, or etching. In some embodiments, the traction member410may be formed by disposing a sharp wire around the snare member400. The traction member410may also be coupled to the snare member400by a suitable technique such as welding, soldering, and so forth. Accordingly, the traction member410may be either monolithically formed with the snare member400or discreetly formed and later coupled with snare member400.

FIG. 6illustrates an exemplary embodiment of a resection device50depicting an arrangement of fraction members510over a portion of a snare member500, according to an embodiment of the present disclosure. As shown, the snare member500may include one or more traction members510of varying sizes extending radially outward. Any suitable arrangement of the discrete traction members510may be used. In some embodiments, the discrete traction members510may vary in shape selected from rectangular, square, semicircular, triangular, conical or the like. An alternating arrangement of the discrete traction members510with different shapes may also be contemplated. As shown inFIG. 5, the discrete traction members510extend along one side of the snare member500. That is, upon being formed into a loop of the snare member500, each of the fraction members510may extend towards a center of the loop of the snare member500. Alternatively, however, traction members510may be disposed so as to extend from any side of the snare member500. Accordingly, it is envisioned that the snare member500may have staggered discrete traction members510.

FIGS. 7A and 7Billustrate an exemplary embodiment of a resection device during and upon completion of manufacturing, according to an embodiment of the present disclosure. As shown inFIG. 7A, the resection device60is in a straight configuration prior to formation into a loop. The resection device60may include a snare member600and a push-pull member608extending from the snare member. In some embodiments, the push-pull member608may act as a conducting means for electro-cauterization procedures, as described above. The snare member600may include one or more transitional portions606bridging a larger cross-sectional area proximal portion604with a smaller cross-sectional area distal portion602. The snare member600may also include traction members610similar to the traction members210,410, and/or510discussed above. The snare member600may include two or more complementary mating members614aand614b. The complementary mating members614aand614bmay be configured such that mating surfaces of each of the complementary mating members614aand614bare configured to couple to one another so as to form a loop, e.g., snare member600. The complimentary mating members614aand614bmay be configured to couple with one another through any appropriate engagement means, for example, a snap fit, a screw fit, a press fit, or the like. In some embodiments, the complementary mating members614amay include protrusions and/or teeth and the complementary mating member614bmay include recess or holes to receive the protrusions or teeth thereby securing the two complementary mating members614aand614btogether. As shown inFIGS. 7A and 7B, the complementary mating members614aand614bmay have a larger cross-sectional area in comparison to a cross-sectional area of the snare member600.

FIG. 8Aillustrates an exemplary embodiment of coupler820for coupling a portion of a snare member in a closed loop configuration according to an embodiment of the present disclosure. The coupler820may be employed for attaching or coupling together the push-pull member830(shown inFIG. 8B) to secure the snare member. The coupler820may include a clip840such that the clip840includes one or more recesses822defined to receive the push-pull member830. In some embodiments, the coupler820may be a sheath, band, housing or the like. The clip840may be dimensioned such that the clip840may couple with the push-pull member830by a suitable means including, but not limited to, a snap fit arrangement, an interference fit arrangement, and the like. The clip840may be disposed at different locations along the length of the push-pull member830. In one embodiment, the clip820may be disposed proximate to the proximal portion (e.g., proximal portion604ofFIGS. 7A-7B). However, in other embodiments, the clip840may be disposed at a proximal end of the push-pull member830.

The push-pull member830may be formed with a reduced portion832as shown inFIG. 8B. The reduced portion832may have a reduced dimension (e.g., diameter) that may be inserted into the pair of recesses822of the clip840. The reduced portion832may be formed using suitable techniques such as grinding, etching, machining or the like. In some embodiments, the push-pull member830may be formed using NITINOL wire. In some embodiments, the reduced portion832may be created by stretching. As such, the NITINOL wire may be stretched so as to form reduced portion832, which is subsequently placed within the recesses822of the clip840. Upon placement of the reduced portion832into clip840, the push-pull member830may be allowed to substantially return to its original size thereby forming a press-fit engagement between clip840and reduced portion832.

Another embodiment of forming a medical device (e.g.,10,20, and30) is disclosed. The method may include forming a loop of a snare member having a proximal portion and a distal portion. Once the loop of the snare member is formed, the snare member may be modified by varying the cross-sectional area of the distal portion so as to be different than a cross-sectional area of the proximal portion. In some cases, the cross-sectional area of the distal portion may be varied by removing a portion of material of the distal portion. The snare member may be modified to form a transition portion extending between the proximal portion and the distal portion. Some embodiments of the method may include forming one or more traction members that may extend along the snare member.

Characteristics of the embodiments include devices and methods with increased flexibility and control. Thus, the disclosed embodiments may provide the capability of resecting unwanted tissue with reduced risk of perforation of and/or damage to healthy surrounding tissue. The device with varied cross-sectional area may result in increased current density delivered to the unwanted target tissue during cutting, and thus, may allow for improved efficiency during cutting.

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. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the description. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.