Mechanically expanding sheath tip

Abstract

The expandable sheath systems disclosed herein are movable between a neutral configuration and an expanded configuration. The expandable sheath system (300) includes a sheath (301) having a first layer (302) that includes a proximal region and a distal region. The first layer (302) least partially defines a central lumen (308) extending axially therethrough. The expandable sheath system also include a second layer (310) radially outward of the first layer (302), the second layer including a proximal region and a distal region. The distal regions of the first and second layers are coupled. The second layer (310) is movable relative to the first layer (310) between a neutral configuration, in which a diameter of the central lumen at the distal region (DD) of the first layer is substantially the same as a diameter of the central lumen at the proximal region (DP) of the first layer, and an expanded configuration.

Description

MECHANICALLY EXPANDING SHEATH TIPCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 662,677, filed June 21, 2024, which is incorporated by reference in its entirety for all purposes.FIELD

[0002] The present application is directed to a sheath and introducer / dilator for use with catheter-based technologies for repairing and / or replacing heart valves, as well as for delivering an implant, such as a prosthetic valve to a heart via the patient’s vasculature.BACKGROUND

[0003] Endovascular delivery catheter assemblies are used to implant prosthetic devices, such as a prosthetic valve, at locations inside the body that are not readily accessible by surgery or where access without invasive surgery is desirable. For example, aortic, mitral, tricuspid, and / or pulmonary prosthetic valves can be delivered to a treatment site using minimally invasive surgical techniques.

[0004] Percutaneous interventional medical procedures utilize the large blood vessels of the body reach target destinations rather than surgically opening target site. There are many types of diseases states that can be treated via interventional methods including coronary blockages, valve replacements (TAVR) and brain aneurysms. These techniques involve using wires, catheters, balloons, electrodes and other thin devices to travel down the length of the blood vessels from the access site to the target site. The devices have a proximal end which the clinician controls outside of the body and a distal end inside the body which is responsible for treating the disease state. Percutaneous interventional procedures offer several advantages over open surgical techniques. First, they require smaller incision sites which reduces scarring and bleeding as well as infection risk. Procedures are also less traumatic to the tissue, so recovery times are reduced. Finally, interventional techniques can usually be performed much faster, and with fewer clinicians participating in the procedure, so overall costs are lowered. In some cases, the need for anesthesia is also eliminated, further speeding up the recovery process and reducing risk.

[0005] A single procedure typically uses several different guidewires, catheters, and balloons to achieve the desired effect. One at a time, each tool is inserted and then removed from theaccess site sequentially. For example, a guidewire is used to track the correct location within the body. Next a balloon may be used to dilate a section of narrowed blood vessel. Last, an implant may be delivered to the target site. Because catheters are frequently inserted and removed, introducer sheaths are used to protect the local anatomy and simplify the procedure.

[0006] An introducer sheath can be used to safely introduce a delivery apparatus into a patient's vasculature (for example, the femoral artery). Introducer sheaths are conduits that seal onto the access site blood vessel to reduce bleeding and trauma to the vessel caused by catheters with rough edges. An introducer sheath generally has an elongated sleeve that is inserted into the vasculature and a housing that contains one or more sealing valves that allow a delivery apparatus to be placed in fluid communication with the vasculature with minimal blood loss. Once the introducer sheath is positioned within the vasculature, the shaft of the delivery apparatus is advanced through the sheath and into the vasculature, carrying the prosthetic device. Expandable introducer sheaths, formed of highly elastomeric materials, allow for the dilating of the vessel to be performed by the passing prosthetic device. However, portions of the sheath resist expansion requiring higher push forces for advancement of the delivery apparatus and implant to the treatment location. Increased push forces are also experienced when the sheath, delivery apparatus and / or implant encounter a narrowed or hardened blood vessel, a calcific lesion, or other blockage / occlusion that may impede delivery of the medical device to the treatment location.

[0007] In some instances, it is possible for a medical device used during a procedure to become damaged or inoperable while positioned in a body lumen of a patient. In such cases, it is desirable to retrieve the medical device from the body lumen. Because some medical devices, such as expandable balloons, can adopt radially-wide or irregular configurations when damaged, typical sheaths may not be able to facilitate their retrieval.

[0008] Accordingly, there remains a need for systems and methods that reduce the push force needed to introduce the delivery device and implant to the treatment location within a patient’s blood vessel. Additionally, there remains a need for systems and methods that facilitate retrieval of intraluminal medical devices.SUMMARY OF THE INVENTION

[0009] Aspects of the present expandable sheath system can minimize trauma to the vessel and damage to the sheath and prosthetic device by reducing push forces through the blood vesseland / or sheath by providing a combined introducer-dilator that can be used to dilate the blood vessel and or sheath before the delivery dcvicc / implant is introduced. Some examples can comprise a sheath with a smaller profile than that of prior art introducer sheaths. Furthermore, certain examples can reduce the length of time a procedure takes, as well as reduce the risk of a longitudinal or radial vessel tear, or plaque dislodgement because lower push force is required and only one sheath is used, rather than several different sizes of sheaths and / or dilators. Furthermore, some examples facilitate retrieval of devices that may become damaged during use.

[0010] An example expandable sheath system according to the present disclosure includes: an expandable sheath. The expandable sheath includes a first layer including a proximal region, a distal region, and at least partially defining a central lumen extending axially therethrough and a second layer radially outward of the first layer, the second layer including a proximal region and a distal region. The distal region of the second layer is coupled to the distal region of the first layer. The second layer is movable relative to the first layer. For example, the expandable sheath system is movable between a neutral configuration, in which a diameter of the central lumen at the distal region of the first layer is substantially the same as a diameter of the central lumen at the proximal region of the first layer, and an expanded configuration, in which the diameter of the central lumen at the distal region of the first layer is radially expanded relative to the diameter of the central lumen at the proximal region of the first layer.

[0011] An example expandable sheath system according to the present disclosure includes an expandable sheath. The expandable sheath includes a first layer including a proximal region, a distal region, and at least partially defining a central lumen extending axially therethrough. The first layer is heat set to be in an expanded configuration, in which a diameter of the central lumen at the distal region of the first layer is radially expanded relative to a diameter of the central lumen at the proximal region of the first layer. The expandable sheath also includes a second layer radially outward of the first layer. The second layer includes a proximal region and a distal region. The first layer is movable relative to the second layer. For example, the expandable sheath system is movable between the expanded configuration and a neutral configuration, in which the diameter of the central lumen at the distal region of the first layer is substantially the same as the diameter of the central lumen at the proximal region of the first layer.

[0012] An example method of controlling expansion and contraction of an expandable sheath system according to the present disclosure includes: moving an expandable sheath from a neutralconfiguration toward an expanded configuration by moving a second layer of the expandable sheath proximally relative to a first layer of the expandable sheath In the neutral configuration, a diameter of a central lumen defined at a distal region of the first layer is substantially the same as a diameter of the central lumen at a proximal region of the first layer. In the expanded configuration, the diameter of the central lumen at the distal region of the first layer is radially expanded relative to the diameter of the central lumen at the proximal region of the first layer.

[0013] An example method of retrieving a medical device according to the present disclosure includes; (i) positioning a distal tip of an expandable sheath adjacent a medical device, the distal tip including a first layer at least partially defining a central lumen extending therethrough and a second layer radially outward of the first layer, wherein a distal region of the first layer is coupled to a distal region of the second layer and a constrained portion of the first layer longitudinally offset from the distal region of the first layer is configured to resist radial expansion of the first layer at the constrained portion; (ii) moving the expandable sheath from a neutral configuration, in which a diameter of a central lumen defined at a distal region of the first layer is substantially the same as a diameter of the central lumen at a proximal region of the first layer, toward an expanded configuration, in which the diameter of the central lumen at the distal region of the first layer is radially expanded relative to the diameter of the central lumen at the proximal region of the first layer, by moving the second layer proximally relative to the first layer or the first layer distally relative to the second layer, wherein the diameter of the central lumen at the distal region of the first layer is at least the size of the medical device; and (iii) retracting the medical device into the central lumen of the expandable sheath.

[0014] Various aspects of the examples described herein can be combined based on desired sheath system characteristics.BRIEF DESCRIPTION OF DRAWINGS

[0015] The device is explained in even greater detail in the following drawings. The drawings are merely exemplary and certain features may be used singularly or in combination with other features. The drawings are not necessarily drawn to scale.

[0016] FIG. 1 is an elevation view of an expandable sheath along with an endovascular delivery appar atus for implanting a prosthetic implant.

[0017] FIG. 2 is an elevation view of an expandable sheath including an introducer locking hub, a sheath locking sleeve, and an introducer.

[0018] FIG. 3 is an elevation view of the expandable sheath of FIG. 2 along with an endovascular delivery apparatus for implanting a prosthetic implant.

[0019] FIG. 4 is an elevation view of an expandable sheath a sheath hub, an introducer locking hub, and a sheath locking sleeve of FIG. 2.

[0020] FIG. 5A is a cross-sectional view of the sheath hub, introducer locking hub, and sheath locking sleeve of FIG. 2.

[0021] FIG 5B is a cross-sectional view of the introducer cap, the sheath hub, the introducer locking hub, and the sheath locking sleeve of FIG. 2.

[0022] FIG. 6 is a cross-sectional view of the introducer cap, sheath hub, introducer locking hub, and sheath locking sleeve of FIG. 2.

[0023] FIG. 7 is a distal end view of the sheath locking sleeve of FIG. 2 and the proximal fluid seal of FIGS 5A-B.

[0024] FIG. 8A is a first elevation view of the introducer locking hub of FIG. 2 coupled to an introducer.

[0025] FIG. 8B is a second (rotated) elevation view of the introducer locking hub of FIG. 2 coupled to the introducer.

[0026] FIG. 8C is a distal end view of the introducer locking hub of FIG. 2 coupled to the introducer.

[0027] FIG. 8D is a partial side view of the introducer locking hub of FIG. 2 coupled to the introducer.

[0028] FIG. 8E is a partial perspective view of the introducer locking hub of FIG. 2 coupled to the introducer.

[0029] FIG. 8F is a partial perspective view of the introducer locking hub of FIG. 2 coupled to the introducer.

[0030] FIG. 9A is a distal end view of the introducer locking hub of FIG. 2.

[0031] FIG. 9B is a first elevation view of the introducer locking hub of FIG. 2.

[0032] FIG. 9C is a proximal end view of the introducer locking hub of FIG. 2.

[0033] FIG. 9D is a first perspective view of the introducer locking hub of FIG. 2.

[0034] FIG. 9E is a second elevation view of the introducer locking hub of FIG. 2.

[0035] FIG. 9F is a second perspective view of the introducer locking hub of FIG. 2.

[0036] FIG. 10A is a distal end view of the sheath locking sleeve of FIG. 2.

[0037] FIG. 1 OB is a first elevation view of the sheath locking sleeve of FIG. 2.

[0038] FIG. 10C is a proximal end view of the sheath locking sleeve of FIG. 2.

[0039] FIG. 10D is a first perspective view of the sheath locking sleeve of FIG. 2.

[0040] FIG. 10E is a second elevation view of the sheath locking sleeve of FIG. 2.

[0041] FIG. 10F is a second perspective view of the sheath locking sleeve of FIG. 2.

[0042] FIG. 11 is a side elevation cross-sectional view of a portion of the expandable sheath of FIGS. 1 and 2.

[0043] FIG. 12 is a magnified view of a portion of the expandable sheath of FIGS. 1 and 2.

[0044] FIG. 13A is a magnified view of a portion of the expandable sheath of FIGS. 1 and 2 with the outer layer removed for purposes of illustration.

[0045] FIG. 13B is a magnified view of a portion of the braided layer of the sheath of FIGS. 1 and 2.

[0046] FIG. 14 is a magnified view of a portion of the expandable sheath of FIGS. 1 and 2 illustrating expansion of the sheath as a prosthetic device is advanced through the sheath.

[0047] FIG. 15 is a side view of the expandable sheath of FIGS. 1 and 2.

[0048] FIG. 16 is a magnified cross-sectional section view of the sheath of FIG. 15 along section line 16-16.

[0049] FIG. 17 is cross-sectional view of the unexpanded sheath of FIG. 16 along section line 17-17.

[0050] FIG. 18 is cross-sectional view of the unexpanded sheath of FIG. 15 along section line 18-18.

[0051] FIG. 19 is cross-sectional view of the unexpanded sheath of FIG. 15 along section line 19-19.

[0052] FIG. 20 is cross-sectional view of the expanded sheath of FIG. 15 along section line 19-19.

[0053] FIG. 21 is a side view of the expandable sheath of FIGS. 1 and 2.

[0054] FIG. 22 is a cross-sectional view of the unexpanded sheath of FIG. 21 along section line 22-22.

[0055] FIG. 23 is a cross-sectional view of the expanded sheath of FIG. 21 along section line 22-22.

[0056] FIG. 24A is a side view of an example expandable sheath in a neutral configuration.

[0057] FIG. 24B is a side view of the expandable sheath of FIG. 24A in an expanded configuration.

[0058] FIG. 24C is a side view of the expandable sheath of FIG. 24A in a contracted configuration.

[0059] FIG. 25 is a side view of an example expandable sheath in a neutral configuration.

[0060] FIG. 26A is a side view of an example expandable sheath in a neutral configuration.

[0061] FIG. 26B is a side view of the expandable sheath of FIG. 26A in an expanded configuration.

[0062] FIG. 27A is a side view of an example expandable sheath in a neutral configuration.

[0063] FIG. 27B is a side view of the expandable sheath of FIG. 27A in a contracted configuration.

[0064] FIG. 28A is a side view of an example expandable sheath in a neutral configuration.

[0065] FIG. 28B is a side view of the expandable sheath of FIG. 28A in an expanded configuration.

[0066] FIG. 28C is a side view of the expandable sheath of FIG. 28A in a contracted configuration.

[0067] FIG. 29A is a side view of an example expandable sheath in a neutral configuration.

[0068] FIG. 29B is a side view of the expandable sheath of FIG. 29A in an expanded configuration.

[0069] FIG. 29C is a side view of the expandable sheath of FIG. 29A in a contracted configuration.

[0070] FIG. 30 is a side view of an example expandable sheath in a neutral configuration.

[0071] FIG. 31 is a side view of an example expandable sheath moving from a neutral configuration to an expanded configuration.

[0072] FIG. 32 is a side view of an example expandable sheath moving from a neutral configuration to an expanded configuration.

[0073] FIG. 33 is a side view of an example expandable sheath moving from a neutral configuration to an expanded configuration to retrieve a medical device.

[0074] FIG. 34A is a side view of an example expandable sheath in a neutral configuration.

[0075] FIG. 34B is a side view of the expandable sheath of FIG. 34A in an expanded configuration.DETAILED DESCRIPTION

[0076] The following description of certain examples of the inventive concepts should not be used to limit the scope of the claims. Other examples, features, aspects, implementations, and advantages will become apparent to those skilled in the art from the following description. As will be realized, the device and / or methods are capable of other different and obvious aspects, all without departing from the spirit of the inventive concepts. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not restrictive.

[0077] For purposes of this description, certain aspects, advantages, and novel features of the aspects of this disclosure are described herein. The described methods, systems, and apparatus should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed examples, alone and in various combinations and sub-combinations with one another. The disclosed methods, systems, and apparatus are not limited to any specific aspect, feature, or combination thereof, nor do the disclosed methods, systems, and apparatus require that any one or more specific advantages be present or problems be solved.

[0078] Features, integers, characteristics, compounds, chemical moieties, or groups described in conjunction with a particular aspect or example of the present disclosure are to be understood to be applicable to any other aspect or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract, and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The present disclosure is not restricted to the details of any foregoing examples. The present disclosure extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract, and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0079] It should be appreciated that any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated hereinby reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.

[0080] As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another aspect includes from the one particular’ value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0081] “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0082] The terms “proximal” and “distal” as used herein refer to regions of a sheath, catheter, or delivery assembly. “Proximal” means that region closest to handle of the device, while “distal” means that region farthest away from the handle of the device.

[0083] “Axially” or “axial” as used herein refers to a direction along the longitudinal axis of the sheath.

[0084] Throughout the description and claims of this specification, the word “comprise” and variations of the word, such as “comprising” and “comprises,” means “including but not limited to,” and is not intended to exclude, for example, other additives, components, integers or steps. “Exemplary” means “an example of’ and is not intended to convey an indication of a preferred or ideal aspect. “Such as” is not used in a restrictive sense, but for explanatory purposes.

[0085] Disclosed examples of an expandable sheath can minimize trauma to the vessel by allowing for temporary expansion of a portion of the introducer sheath to accommodate the delivery apparatus, followed by a return to the original diameter once the device passes through. Disclosed examples of the introducer sheath prevent the introducer / dilator from separating from the sheath during insertion by locking of the proximal hub of the introducer / dilator to the proximal hub of the sheath. Fixing the introducer / dilator and the sheath prevents theintroducer / dilator from moving backward during insertion, thereby maintaining a snug fit and smooth transition between the introducer / dilator and the distal end of the sheath. Furthermore, present examples can reduce the length of time a procedure takes, as well as reduce the risk of a longitudinal or radial vessel tear, or plaque dislodgement because only one sheath is required, rather than several different sizes of sheaths. Examples of the present expandable sheath can avoid the need for multiple insertions for the dilation of the vessel.

[0086] Disclosed herein are elongate introducer sheaths that are particularly suitable for delivery of implants in the form of implantable heart valves, such as balloon-expandable implantable heart valves. Balloon-expandable implantable heart valves are well-known and will not be described in detail here. An example of such an implantable heart valve is described in U.S. Patent No. 5,411,552, and also in U.S. Patent No. 9,393,110, both of which are hereby incorporated by reference. The expandable introducer sheaths disclosed herein may also be used to deliver other types of implantable medical device, such as self-expanding and mechanically expanding implantable heart valves, stents or filters. Beyond transcatheter heart valves, the introducer sheath system can be useful for other types of minimally invasive surgery, such as any surgery requiring introduction of an apparatus into a subject’s vessel. For example, the introducer sheath system can be used to introduce other types of delivery apparatus for placing various types of intraluminal devices (for example, stents, stented grafts, balloon catheters for angioplasty procedures, etc.) into many types of vascular and non-vascular body lumens (for example, veins, arteries, esophagus, ducts of the biliary tree, intestine, urethra, fallopian tube, other endocrine or exocrine ducts, etc.). The term “implantable” as used herein is broadly defined to mean anything - prosthetic or not - that is delivered to a site within a body. A diagnostic device, for example, may be an implantable.

[0087] FIG. 1 illustrates an exemplary sheath 8 in use with a representative delivery apparatus 10, for delivering an implant 12, or other type of implantable (for example, tissue heart valve), to a patient. The delivery apparatus 10 can include a steerable guide catheter 14 (also referred to as a flex catheter) and a balloon catheter 16 extending through the guide catheter 14, and a nose catheter 15 extending through the balloon catheter 16. The guide catheter 14, balloon catheter 16, and nose catheter 15 in the illustrated example are adapted to slide longitudinally relative to each other to facilitate delivery and positioning of the implant 12 at an implantation site in a patient’s body as described in detail herein. It is contemplated that the sheath 8 can beused with any type of elongated delivery apparatus used for implanting balloon-expandable prosthetic valves, self-expanding prosthetic valves, and other prosthetic devices.

[0088] As described in more detail herein, in general, the sheath 8 comprises an elongate expandable tube that, in use, is inserted into a vessel (for example, transfemoral vessel, femoral artery, iliac artery) by passing through the skin of patient, such that the distal end of the sheath 8 is inserted into the vessel. Sheath 8 includes a hemostasis valve and / or sealing features at the proximal end of the sheath, for example, in the sheath hub 20, that provide hemostasis and prevents blood leakage from the patient through the sheath 8. The sheath 8, including an introducer 6, is advanced into the patient’s vasculature. Once positioned the introducer 6 is removed and the delivery apparatus 10 is inserted into / through the sheath 8, and the prosthetic device (implant 12) then be delivered and implanted within patient.

[0089] FIGS. 2 and 3, the introducer device / sheath assembly includes a sheath hub 20 at a proximal end of the device and an expandable sheath 8 extending distally from the sheath hub 20. The sheath 8 is coupled to the sheath hub 20 which in turn is removably coupled to a sheath locking system 18. The sheath locking system 18 allows the introducer 6, or other device desired to be removably couped (axially and rotatably) to the sheath 8.

[0090] As illustrated in FIGS. 2-6, the sheath hub 20 can function as a handle for the device. Sheath hub 20 also provides a housing for necessary seal assemblies and an access point for a secondary lumen (for example, fluid lumen) in fluid communication with the central lumen of the sheath hub 20. The seal assembly 24, as described herein and as shown in FIGS. 5A and 5B, is included in the sheath hub 20. The seal assembly 24 includes a proximal seal 24a, an intermediate seal 24b, and a distal seal 24c. When assembled, the introducer 6 passes through the seal assembly and extends distal of the sheath 8. The proximal seal 24a, the intermediate seal 24b, and the distal seal 24c are each formed to prevent unwanted fluid from advancing in the proximal direction through the sheath hub 20 and proximal of the seal assembly 24. They are each openable and closable to provide pressure variation to affect the desired fluid flow from a physician or technician.

[0091] The distal end of the sheath hub 20 includes threads 21 for coupling to a threaded sheath hub cap 22. The sheath 8 is provided between the sheath hub 20 and the sheath hub cap 22 such that coupling the sheath hub cap 22 to the sheath hub 20 fixes the sheath 8 to the sheath hub 20. The sheath hub cap 22 is a cylindrical cap having a cap body having a proximal end and a distalend and defining a central lumen extending longitudinally between the proximal end and the distal end. The sheath hub cap 22 has a larger diameter at its proximal end than at its distal end.

[0092] The sheath hub 20 further has receiving slots 48 for coupling the sheath locking system 18, particularly the locking sleeve 28, to the sheath hub 20. The receiving slots 48 are openings which extend around a portion of the diameter of the sheath hub 20 and are sized and configured to accept the interference diameters 66 of the locking sleeve 28. Coupling between the receiving slots 48 and the interference diameters 66 axially and rotationally fixes the locking sleeve 28 and the sheath hub 20 relative to each other.

[0093] FIG. 2 illustrates the sheath 8 of FIG. 1 including a sheath locking system 18 which prevents axial and rotational translation of the introducer 6 with respect to the sheath 8. Example locking systems are disclosed in PCT / US2021 / 050006, entitled “Expandable Sheath Including Reverse Bayonet Locking Hub,” the disclosure of which is incorporated herein by reference. It is contemplated that the locking system disclosed herein can also be used to couple the sheath 8 / sheath hub 20 with other delivery apparatus components, catheters, dilators, etc. including the same mating features.

[0094] The sheath locking system 18 keeps the introducer 6 fixed with respect to the sheath 8 during insertion without requiring a physician or technician to hold the introducer 6 and the sheath 8 in place at the distal end. As illustrated in FIGS. 8A-8B, the sheath locking system 18 includes a locking sleeve 28 and an introducer locking hub 30 (including corresponding introducer 6). The locking sleeve 28 is coupled to the sheath 8 via the sheath hub 20. The locking sleeve 28 engages the introducer locking hub 30 and is moveable between a locked and unlocked position, thereby fixing the position of the introducer 6 and the sheath 8 and preventing movement therebetween, particularly during insertion into the patient. As will be described in more detail herein, the sheath locking system 18 keeps the introducer 6 from separating from the sheath 8 and prevents gaps from forming that can cause patient abrasions and unintended fluid flow between the introducer 6 and the sheath 8 during insertion.

[0095] FIGS. 2, 5A-5B and 6, and illustrate the locking sleeve 28 coupled to the introducer locking hub 30 and the sheath hub 20. As will be described in more detail herein, the locking sleeve 28 includes a guide 31 that engages a locking channel 38 provided on the introducer locking hub 30. The guide 31 moves within the locking channel 38 between an unlocked position, where the locking sleeve 28 is rotationally and axially movable with respect to theintroducer locking hub 30, and a locked position (FIG. 2), where the locking sleeve 28 is axially fixed with respect to the introducer locking hub 30.

[0096] The locking sleeve 28 is illustrated, for example, in FIGS. 10A-10F. The locking sleeve 28 includes an elongated sleeve body 29 with a central lumen 56 extending longitudinally between the proximal end 58 and distal end 60 of the sleeve body 29. As provided in FIG. 6, the central lumen 56 defines a generally cylindrical inner surface 62 of the sheath locking sleeve 28. The central lumen 56 has a diameter of at least 0.3 inches. In some examples, the diameter ranges between 0.3 inches and 0.6 inches. Preferably, the diameter is about 0.40 inches. The distal end 60 of the sleeve body 29 also has a frustoconical outer surface 64 that tapers about the distal end 60 to help with positioning the locking sleeve 28 within the sheath hub 20 and abutting the seal assembly 24 (FIGS. 5B and 5B). The locking sleeve 28 also has a plurality of interference diameters 66 that extend radially from the outer surface of the sleeve body 29 around (all or a portion of) the circumference of the locking sleeve 28. As illustrated in FIGS. 5A and 6, the distal interference diameters 66 are sized and configured to engage corresponding recesses and / or slots 48 provided in the sheath hub 20 for securing the locking sleeve 28 to the sheath hub 20, and the distal interference diameter 66 seat against the proximal end of the sheath hub 20.

[0097] The locking sleeve 28 includes a guide 31 projecting from the outer surface 68 of the locking sleeve 28. The guide 31 engages a corresponding shaped locking channel 38 in the introducer locking hub 30. The guide 31 extends radially from the outer surface 68 and at least partially around the circumference of the outer surface 68. As provided in FIG. 6, the top surface of the guide 31 does not extend beyond the outer surface of the introducer locking hub 30 when the locking sleeve 28 and the introducer locking hub 30 are coupled. For example, the height of the guide 31 corresponds to the wall thickness of the introducer locking hub 30 proximate the guide when the locking sleeve 28 and the introducer locking hub 30 are coupled. In some examples, the top surface of the guide 31 is recessed with respect to the outer surface of the introducer locking hub 30. That is, the height of the guide 31 is less than the wall thickness of the introducer locking hub 30. In some examples, the height of the guide 31 is greater than a wall thickness of the introducer locking hub 30 such that the top surface of the guide 31 extends beyond the outer surface of the introducer locking hub 30 when the locking sleeve 28 and the introducer locking hub 30 are coupled. In some examples, the height / axial length of the guide 31is between about 0.050 inches and about 0.10 inches. In some examples that height / axial length of the guide 31 is about 0.075 inches.

[0098] As illustrated in FIGS. 10D-10F, the guide 31 is a cylindrically shaped projection. However, it is contemplated that the guide 31 may have any other regular or i rrcgular shape that would facilitate movement of the guide 31 within the locking channel 38 of the introducer locking hub 30. For example, the guide 31 may have an elongated hexagon shape. The guide 31 can have a diameter / width ranging from about 0.05 inches to about 0.20 inches. Preferably the guide 31 has a diameter / width of about 0.100 inches.

[0099] In general, the locking sleeve 28 can comprise polycarbonate, but in some examples, the locking sleeve 28 can comprise rigid plastic, or any other material suitable for providing a strong locking connector for an introducer 6 (metal, composite, etc.).

[0100] FIGS. 2-6 illustrate the introducer locking hub 30 coupled to the locking sleeve 28. FIGS. 8A-8F show the introducer locking hub 30 coupled to the introducer 6. FIGS. 9A-9F provide multiple view of the introducer locking hub 30. As described herein, the introducer 6 is fixedly coupled to the introducer locking hub 30. The introducer locking hub 30 couples with the locking sleeve 28 to fix the position the introducer 6 (axially and rotationally) with respect to the locking sleeve 28 / sheath 8. Each of the introducer 6 and introducer locking hub 30 are described in more detail as follows.

[0101] FIGS. 8A-8F illustrate the introducer locking hub 30 with the introducer 6 coupled thereto. Example introducer sheaths are described, for example in U.S. Patent Nos. 8,690,936 and 8,790,387, the disclosures of which are incorporated herein by reference. As provided in the cross-sectional views of FIGS. 5A and 5B, the introducer 6 is coupled to the introducer locking hub 30 and extends beyond the distal end of the introducer locking hub 30 body and into the sheath 8. When coupled to the sheath hub 20, the introducer 6 extends through the central lumen 56 of the locking sleeve 28, the sheath hub 20 and the central lumen of the sheath 8. As will be descried herein, the sheath 8 generally comprises a radially expandable tubular structure. Passage of the introducer 6 through the sheath 8 and into a patient’s vasculature causes the blood vessel to radially expand to about the diameter of the sheath 8. That is, the diameter of the central lumen of the sheath 8 is generally abuts the outer diameter of the introducer 6 such that the introducer 6 provides a mechanism to expand a patient’s vessel to accept the sheath.

[0102] As provided in FIGS. 8A-8F, the introducer 6 is formed as an elongate body with a central lumen extending therethrough. As shown in FIGS. 5A and 5B, the central lumen of the introducer is aligned with the central lumens of the introducer locking hub 30, the sheath hub 20 and the sheath 8. The introducer 6 is received within a recessed opening 39 provided on an interior surface of the introducer locking hub 30, the recessed opening 39 axially aligned with the central lumen 45 of the introducer locking hub 30. The introducer 6 is coupled to the introducer locking hub 30 at the recessed opening 39. In an example system, the introducer 6 has a diameter corresponding to, or less than, the diameter of the recessed opening 39. In some examples, the introducer 6 is fixedly coupled to the introducer locking hub 30 at the recessed opening 39. For example, the introducer 6 is coupled to the recessed opening 39 of the introducer locking hub 30 by at least one of a press fit, an interference fit, a snap fit, a mechanical fastener, a chemical fastener (for example, an adhesive), a weld, a thermal process, and / or any other suitable coupling process known in the art.

[0103] As described herein, the introducer 6 has a central lumen that aligns with the central lumen 45 of the introducer locking hub 30. This joined lumen allows for the passage of surgical equipment and / or medical devices to the treatment site (for example, a guide wire). In an example system, and as provided in FIGS. 5A and 5B, the central lumen of the introducer 6 has a diameter corresponding to at least a portion of the diameter of the central lumen 45 of the introducer locking hub 30. In general, the corresponding diameter portion is adjacent the distal end of the central lumen 45. In some examples, the diameter of the central lumen 45 at the distal end of the introducer locking hub 30 is slightly larger than the diameter of the central lumen passing through the introducer 6. The central lumen 45 can also define a decreasing tapered portion 41 between the proximal end and the distal end of the introducer locking hub 30 (see FIG. 6). The corresponding diameter portion and decreasing tapered portion 41 allows for smooth transition and delivery of surgical equipment and / or medical device through the introducer locking hub 30 and into the central lumen of the introducer 6.

[0104] As illustrated in FIGS. 9A-9F, the introducer locking hub 30 includes a introducer locking hub body 32 having a proximal end 70 and a distal end 72 and defining a central lumen 45 extending therethrough. The introducer locking hub body 32 has a first (middle) portion 33, a second (distal) portion 35 which extends distally from the first portion 33 and a third (proximal) portion 37 which extends proximally from the first portion 33. The first portion 33 includes thecylindrically-shaped recessed opening 39 for receiving and retaining the introducer 6 and an outer surface 43. In some examples, the recessed opening 39 has a diameter ranging between 0.15 inches and about 0.25 inches. In some examples, the recessed opening 39 has a diameter ranging between 0.17 inches and about 0.20 inches. In some examples, the recessed opening has a diameter of about 0.194 inches.

[0105] The third (proximal) portion 37 of the introducer locking hub 30 includes the decreasing tapered portion 41 of the central lumen 45. The decreasing taper portion 41 defining a frustoconical shape with decreasing taper / diameter from the proximal to the distal end of the sheath. It is contemplated that the tapered portion 41 has a minimum diameter of about 0.007 inches and a maximum diameter of about 0.194 inches.

[0106] As illustrated in FIGS. 5A and B, when coupled, the central lumen 56 of the locking sleeve 28 is aligned with the central lumen 45 of the introducer locking hub 30. In some examples, the central lumen 56 of the locking sleeve 28 is coaxial with the central lumen 45 of the introducer locking hub 30. When coupled, the proximal end of the locking sleeve 28 is received within the central lumen 45 of the introducer locking hub 30. The proximal end surface of the locking sleeve 28 is adjacent a shoulder 50 provided on an inner surface of the central lumen 45 of the introducer locking hub 30. As illustrated in FIGS. 5 A and 5B, the central lumen 45 of the introducer locking hub 30 includes a first portion 52 having a first diameter adjacent the proximal end of the introducer locking hub 30, and a second portion 54 having a second, larger, diameter adjacent the distal end of the introducer locking hub 30. The recessed opening 39 can be considered either a component of the first portion 52 of the central lumen 45, or a separate component of the central lumen 45 located between the first (proximal) portion 52 and the second (distal) portion 54. When the locking sleeve 28 and introducer locking hub 30 are coupled, at least a portion of the sleeve body 29 of the locking sleeve 28 is received within the second portion 54 (larger portion) of the central lumen 45 of the introducer locking hub 30. The central lumen 56 of the locking sleeve 28 is aligned with the central lumen 45 of the introducer locking hub 30 such that they are co-axial and form a smooth inner surface along the combined central lumens of the introducer locking hub 30 and the locking sleeve 28.

[0107] As described herein, the locking sleeve 28 couples to the introducer locking hub 30 via engagement between the guide 31 on the locking sleeve 28 and the locking channel 38 provided in the introducer locking hub 30. As provided in FIGS. 9A-9F, the introducer locking hub 30includes two locking channels 38. However, it is contemplated that the introducer locking huh 30 can include one locking channel 38 or more than two locking channels 38. The locking channel 38 can be is formed a recess or groove in a surface of the introducer locking hub 30, as a slotted opening, a clip, or as any other feature capable of receiving and securing the guide 31 projecting from the outer surface of the locking sleeve 28 with the introducer locking hub 30. Illustrated in FIG. 9B, the locking channels 38 provide an interface to secure the locking sleeve 28 to the introducer locking hub 30 and ensure a fixed axial position between the introducer 6 and the sheath 8.

[0108] The locking channel 38 is formed on the distal end of the introducer locking hub 30. The locking channel 38 includes an opening on the distal end surface that leads to an angled guide portion 40 that transitions to a locking portion 42. The guide portion 40 is configured to direct the guide 31 of the locking sleeve 28 in an axial and circumferential direction along the side wall of the guide portion 40 towards the locking portion 42 upon rotation of the introducer locking hub 30 and / or the locking sleeve 28. The locking portion 42 is configured to securely engage the guide 31, fixing the axial position of the introducer locking hub 30 with respect to the locking sleeve 28. As illustrated in FIG. 9B, the guide portion 40 of the locking channel 38 extends from the distal end of the introducer locking hub 30 axially towards the proximal end of the introducer locking hub 30 and circumferentially around the introducer locking hub 30. For example, the guide portion 40 of the locking channel 38 can be described as extending helically around / along a length of the introducer locking hub 30 or on an angle from the distal end of the introducer locking hub 30.

[0109] As illustrated in FIGS. 9B and 9D, the locking portion 42 of the locking channel 38 extends at an angle from the end of the guide portion 40. As provided in FIG. 9B, the angle between the centerline of the guide portion 40 and the centerline of the locking portion 42 is greater than 90-degrees. In some examples, the angle between the centerline of the guide portion 40 and the centerline of the locking portion 42 is about 120-degrees. In an example system, the locking portion 42 extends around a portion of the circumference of the introducer locking hub 30. The locking portion 42 can extend parallel to the distal end of the introducer locking hub 30. In an example system, the length of the guide portion 40 (measured along its centerline) is greater than a length of the locking portion 42 (measured along its centerline). In some examples, the length of the guide portion 40 equals or is less than a length of the locking portion 42.

[0110] The locking portion 42 can include a catch 44 for securing the guide 31 within the locking portion 42 of the locking channel 38 and forming a partial barrier for the guide 31 within the locking portion 42. As illustrated in FIG. 9B, the catch 44 includes a projection that extends from a side wall 74 of the locking portion 42 and releasably secures the guide 31 within the locking channel 38. The catch 44 extends from the side wall 42a of the locking portion 42 in a proximal direction towards the center line of the locking portion 42 and has a height sufficient to retain the guide 31 between the catch 44 and the end of the locking portion 42.

[0111] The distal end surface 72 of the introducer locking hub 30 can include features for biasing the guide 31 towards and into the locking channel 38. For example, the distal end of the introducer locking hub 30 can include a tapered surface angled toward an opening of the locking channel 38. As illustrated in FIG. 9B, the distal end 72 of the introducer locking hub 30 includes a first tapered surface 76 (angled towards a leading edge of the opening of the locking channel 38 and a second tapered surface 78 angled towards the trailing edge of the opening of the locking channel 38.

[0112] In use, engagement between the guide 31 and the guide portion 40 of the locking channel 38 is configured to bias the locking sleeve 28 in a proximal axial direction toward the proximal end 70 of the introducer locking hub 30 (towards a locked position) when the locking sleeve 28 is rotated in a first axial direction. In this direction the guide 31 advances toward the locking portion 42 of the locking channel 38 into the locked position. Alternatively, engagement between the guide 31 and the locking portion 42 of the locking channel 38 is configured to bias the locking sleeve 28 in a distal axial direction toward the distal end of the introducer locking hub 30 (towards an unlocked position) when the locking sleeve 28 is rotated in a second (opposite) axial direction. In the second direction, the guide 31 advances away from the locking portion 42 of the locking channel 38, to the unlocked position. When the guide 31 is in the locked position and retained with by locking portion 42 by catch 44, rotation in the second direction causes the guide 31 to bias against the catch 44 overcoming the oppositional forces of the catch 44, and moving the guide 31 from the locked to the unlocked position.

[0113] As illustrated in FIGS. 8A-9F, the outer surface of the introducer locking hub body 32 includes gripping features and / or surfaces for a physician or technician to use when manipulating the introducer locking hub 30. As provided in FIG. 9B, the introducer locking hub body 32 can include a two recessed gripping surfaces 34 on opposite sides of the longitudinal axis of theintroducer locking hub 30. When the introducer locking hub 30 is viewed from the side, the gripping surfaces 34 define a dog-bonc / barbcll shape to the hub body 32, i.c., a shape having a smaller diameter / width center portion and larger diameter / width end portions. In an example system, the gripping surfaces 34 are provided along at least 40% of the length of the introducer locking hub body 32. In some examples, the gripping surfaces 34 are provided along at least 50% of the length of the introducer locking hub body 32.

[0114] In general, the introducer locking hub 30 can comprise polycarbonate, but in some examples the introducer locking hub 30 can comprise rigid plastic, or any other material suitable for providing a locking mechanism for an introducer 6 (metal, composite, etc.).

[0115] As described herein, the introducer device / sheath assembly includes an expandable sheath 8 extending distally from the sheath hub 20. The expandable sheath 8 has a central lumen to guide passage of the delivery apparatus 10 for the medical device / prosthetic heart valve. In some examples, the introducer device / sheath assembly need not include the sheath hub 20. For example, the sheath 8 can be an integral part of a component of the sheath assembly, such as the guide catheter.

[0116] As described herein, the expandable sheath 8 can comprise a highly elastomeric materials that allows for the dilating of the vessel to be performed by the passing prosthetic device. Example expandable introducer sheaths 8 are disclosed in U.S. Patent No. 8,690,936, entitled “Expandable Sheath for Introducing an Endovascular Delivery Device into a Body,” U.S. Patent No. 8,790,387, entitled “Expandable Sheath for Introducing an Endovascular Delivery Device into a Body,” U.S. Patent No. 10,639,152, entitled “Expandable Sheath and Methods of Using the Same,” U.S. Patent No. 10,792,471, entitled “Expandable Sheath,” U.S. Patent No. Application No. 16 / 407,057, entitled “Expandable Sheath with Elastomeric Cross Sectional Portions,” U.S. Patent No. 10,327,896, entitled “Expandable Sheath with Elastomeric Cross Sectional Portions,” U.S. Patent No. 11,273,062, entitled “Expandable Sheath,” Application No. PCT / US2021 / 019514, entitled “Expandable sheath for introducing an endovascular delivery device in to a body,” Application No. PCT / US2021 / 031227, entitled “Expandable sheath for introducing an endovascular delivery device into a body,” Application No. PCT / US2021 / 031275, entitled “Expandable sheath for introducing an endovascular delivery device into a body,” U.S. Application No. 17 / 113,268, entitled “Expandable Sheath and Method of Using the Same,” Application No. PCT / US2021 / 058247, entitled “Self-Expanding, TwoComponent Sheath,” Application No. PCT / US2022 / 012785, entitled “Expandable Sheath,” U.S. Patent No. 11,051,939, entitled “Active Introducer Sheath System,” Application No. PCT / US2022 / 012684, entitled “Introducer with Sheath Tip Expander,” U.S. Application No. 17 / 078,556, entitled “Advanced Sheath Patterns,” Application No. PCT / US2021 / 025038, entitled “Low temperature hydrophilic adhesive for use in expandable sheath for introducing an endovascular delivery device into a body,” Application No. PCT / US2021 / 050006, entitled “Expandable Sheath Including Reversable Bayonet Locking Hub,” U.S. Provisional Application No. 63 / 280,251, entitled “Expandable Sheath Gasket to Provide Hemostasis,” U.S. Provisional Application No. 63 / 530,144, entitled “Introducer / Dilator with Folded Balloon,” and U.S. Provisional Application No. 63 / 502,907, entitled “Lead Screw Driven Sheath Dilator,” the disclosures of which are herein incorporated by reference.

[0117] In certain examples, the expandable sheath 8 can comprise a plurality of coaxial layers extending along at least a portion of the length of the sheath 8. The structure of the coaxial layers is described in more detail herein with respect to FIGS. 11-23. Example expandable sheaths including coaxial layers are described, for example, in U.S. Patent Application No. 16 / 378,417, entitled “Expandable Sheath,” and U.S. Patent Application No. 17 / 716,882, entitled “Expandable Sheath,” the disclosures of which are herein incorporated by reference.

[0118] Various examples of the coaxial layered structure of the sheath 8 are described herein. For example, in reference to the example sheath 8 illustrated in FIGS. 11-14, the expandable sheath 8 can include a number of layers including an inner layer 102 (also referred to as an inner layer), a second layer 104 disposed around and radially outward of the inner layer 102, a third layer 106 disposed around and radially outward of the second layer 104, and a fourth outer layer 108 (also referred to as an outer layer) disposed around and radially outward of the third layer 106. In the illustrated configuration, the inner layer 102 can define the lumen 112 of the sheath extending along a central axis 114 through which the delivery apparatus travels into the patient’s vessel in order to deliver, remove, repair, and / or replace a prosthetic device, moving in a direction along the longitudinal axis of the sheath 8.

[0119] Referring to FIG. 12, when the sheath 8 is in an unexpanded state, various layers of the sheath, for example, the inner layer 102 and / or the outer layer 108, can form longitudinally- extending folds or creases such that the surface of the sheath comprises a plurality of folds or ridges 126. The ridges 126 can be circumferentially spaced apart from each other bylongitudinally-extending valleys 128. When the sheath expands beyond its natural diameter Di, the ridges 126 and the valleys 128 can level out or be taken up as the surface radially expands and the circumference increases, as further described herein. When the sheath 8 collapses back to its natural diameter, the ridges 126 and valleys 128 can reform.

[0120] In certain examples, the inner layer 102 and / or the outer layer 108 can comprise a relatively thin layer of polymeric material. For example, the thickness of the inner layer 102 can be from 0.01 mm to 0.5 mm, 0.02 mm to 0.4 mm, or 0.03 mm to 0.25 mm. In some examples, the thickness of the outer layer 108 can be from 0.01 mm to 0.5 mm, 0.02 mm to 0.4 mm, or 0.03 mm to 0.25 mm.

[0121] In certain examples, the inner layer 102 and / or the outer layer 108 can comprise a lubricious, low-friction, and / or relatively non-elastic material. For example, the inner layer 102 and / or the outer layer 108 can comprise a polymeric material having a modulus of elasticity of 400 Mpa or greater. Exemplary materials can include ultra-high-molecular-weight polyethylene (UHMWPE) (for example, Dyneema®), high- molecular- weight polyethylene (HMWPE), or polyether ether ketone (PEEK). With regard to the inner layer 102 in particular, such low coefficient of friction materials can facilitate passage of the prosthetic device through the lumen 112. Other suitable materials for the inner and outer layers can include polyimide, polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), ethylene tetrafluoroethylene (ETFE), nylon, polyethylene, polyamide, polyether block amide (for example, Pebax), and / or combinations of any of the above. In some examples, the sheath 8 can include a lubricious liner on the inner surface of the inner layer 102. Examples of suitable lubricious liners include materials that can further reduce the coefficient of friction of the inner layer 102, such as PTFE, polyethylene, polyvinylidene fluoride, and combinations thereof. Suitable materials for a lubricious liner also include other materials desirably having a coefficient of friction of 0.1 or less.

[0122] Additionally, some examples of the sheath 8 can include an exterior hydrophilic coating on the outer surface of the outer layer 108. Such a hydrophilic coating can facilitate insertion of the sheath 8 into a patient’s vessel, reducing potential damage. Examples of suitable hydrophilic coatings include the Harmony™ Advanced Lubricity Coatings and other Advanced Hydrophilic Coatings available from SurModics, Inc., Eden Prairie, MN. DSM medical coatings (available from Koninklijke DSM N.V, Heerlen, the Netherlands), as well as other hydrophilic coatings(for example, PTFE, polyethylene, polyvinylidene fluoride), are also suitable for use with the sheath 8. Such hydrophilic coatings may also be included on the inner surface of the inner layer 102 to reduce friction between the sheath and the delivery apparatus, thereby facilitating use and improving safety. In some examples, a hydrophobic coating, such as Perylene, may be used on the outer surface of the outer layer 108 or the inner surface of the inner layer 102 in order to reduce friction.

[0123] In certain examples, the second layer 104 can be a braided layer. FIGS. 13A and 13B illustrate the sheath 8 with the outer layer 108 removed to expose the elastic third layer 106. With reference to FIGS. 13A and 13B, the braided second layer 104 can comprise a plurality of members or filaments 110 (for example, metallic or synthetic wires or fibers) braided together. The braided second layer 104 can have any desired number of filaments 110, which can be oriented and braided together along any suitable number of axes. For example, with reference to FIG. 13B, the filaments 110 can include a first set of filaments 110A oriented parallel to a first axis A, and a second set of filaments HOB oriented parallel to a second axis B. The filaments 110A and HOB can be braided together in a biaxial braid such that filaments 110A oriented along axis A form an angle 0 with the filaments 110B oriented along axis B. In certain examples, the angle 0 can be from 5° to 70°, 10° to 60°, 10° to 50°, or 10° to 45°. In the illustrated example, the angle 0 is 45°. In some examples, the filaments 110 can also be oriented along three axes and braided in a triaxial braid, or oriented along any number of axes and braided in any suitable braid pattern. The braided second layer 104 can extend along substantially the entire length L of the sheath 8, or alternatively, can extend only along a portion of the length of the sheath. In particular examples, the filaments 110 can be wires made from metal (for example, Nitinol, stainless steel, etc.), or any of various polymers or polymer composite materials, such as carbon fiber. In certain examples, the filaments 110 can be round, and can have a diameter of from 0.01 mm to 0.5 mm, 0.03 mm to 0.4 mm, or 0.05 mm to 0.25 mm. In some examples, the filaments 110 can have a flat cross-section with dimensions of 0.01 mm x 0.01 mm to 0.5 mm x 0.5 mm, or 0.05 mm x 0.05 mm to 0.25 mm x 0.25 mm. In one aspect, filaments 110 having a Hat cross-section can have dimensions of 0.1 mm x 0.2 mm. However, other geometries and sizes are also suitable for certain aspects. If braided wire is used, the braid density can be varied. Some examples have a braid density of from ten picks per inch to eighty picks per inch, and can include eight wires, sixteen wires, or up to fifty-two wires in various braid patterns. In someexamples, the second layer 104 can be laser cut from a tube, or laser-cut, stamped, punched, etc., from sheet stock and rolled into a tubular configuration. The second layer 104 can also be woven or knitted, as desired.

[0124] The third layer 106 can be a resilient, elastic layer (also referred to as an elastic material layer). In certain examples, the elastic third layer 106 can be configured to apply radially inward force to the underlying inner layer 102 and second layer 104 in a radial direction (for example, toward the central axis 114 of the sheath) when the sheath expands beyond its natural diameter by passage of the delivery apparatus through the sheath. Stated differently, the elastic third layer 106 can be configured to apply encircling / radially inward pressure to the layers of the sheath beneath the elastic third layer 106 to counteract expansion of the sheath. The radially inwardly directed force is sufficient to cause the sheath to collapse radially back to its unexpanded state after the delivery apparatus is passed through the sheath.

[0125] In the illustrated example, the elastic third layer 106 can comprise one or more members configured as strands, ribbons, or elastic bands 116 helically wrapped around the braided second layer 104. For example, in the illustrated aspect the elastic third layer 106 comprises two elastic bands 116A and 116B wrapped around the braided second layer 104 with opposite helicity, although the elastic layer may comprise any number of bands depending upon the desired characteristics. The elastic bands 116A and 116B can be made from, for example, any of a variety of natural or synthetic elastomers, including silicone rubber, natural rubber, any of various thermoplastic elastomers, polyurethanes such as polyurethane siloxane copolymers, urethane, plasticized polyvinyl chloride (PVC), styrenic block copolymers, polyolefin elastomers, etc. In some examples, the elastic layer can comprise an elastomeric material having a modulus of elasticity of 200 MPa or less. In some examples, the elastic third layer 106 can comprise a material exhibiting an elongation to break of 200% or greater, or an elongation to break of 400% or greater. The elastic third layer 106 can also take other forms, such as a tubular layer comprising an elastomeric material, a mesh, a shrinkable polymer layer such as a heatshrink tubing layer, etc. In lieu of, or in addition to, the elastic third layer 106, the sheath 8 may also include an elastomeric or heat-shrink tubing layer around the outer layer 108. Examples of such elastomeric layers are disclosed in U.S. Publication No. 2014 / 0379067, U.S. Publication No. 2016 / 0296730, and U.S. Publication No. 2018 / 0008407, which are incorporated herein byreference. In some examples, the elastic third layer 106 can also be radially outward of the polymeric outer layer 108.

[0126] In certain examples, one or both of the inner layer 102 and / or the outer layer 108 can be configured to resist axial elongation of the sheath 8 when the sheath expands. More particularly, one or both of the inner layer 102 and / or the outer layer 108 can resist stretching against longitudinal forces caused by friction between a prosthetic device and the inner surface of the sheath 8 such that the length L remains substantially constant as the sheath expands and contracts. As used herein with reference to the length L of the sheath, the term “substantially constant” means that the length L of the sheath increases by not more than 1%, by not more than 5%, by not more than 10%, by not more than 15%, or by not more than 20%. Meanwhile, with reference to FIG. 13B, the filaments 110A and 110B of the braided second layer 104 can be allowed to move angularly relative to each other such that the angle 0 changes as the sheath expands and contracts. This, in combination with the longitudinal ridges 126 in the inner layer 102 and outer layer 108, can allow the lumen 112 of the sheath to expand as a prosthetic device is advanced through it.

[0127] For example, the inner layer 102 and the outer layer 108 can be heat-bonded during the manufacturing process such that the braided second layer 104 and the elastic third layer 106 are encapsulated between the inner layer 102 and outer layer 108. More specifically, in some examples the inner layer 102 and the outer layer 108 can be adhered to each other through the spaces between the filaments 110 of the braided second layer 104 and / or the spaces between the elastic bands 116. The inner layer 102 and outer layer 108 can also be bonded or adhered together at the proximal and / or distal ends of the sheath. In some examples, the inner layer 102 and outer layer 108 are not adhered to the filaments 110. This can allow the filaments 110 to move angularly relative to each other, and relative to the inner layer 102 and outer layer 108, allowing the diameter of the braided second layer 104, and thereby the diameter of the sheath, to increase or decrease. As the angle 0 between the filaments 110A and 110B changes, the length of the braided second layer 104 can also change. For example, as the angle 0 increases, the braided second layer 104 can foreshorten, and as the angle 0 decreases, the braided second layer 104 can lengthen to the extent permitted by the areas where the inner layer 102 and outer layer 108 are bonded. However, because the braided second layer 104 is not adhered to the inner layer 102 and outer layer 108, the change in length of the braided layer that accompanies a change in the angle0 between the filaments 1 10A and 11OB does not result in a significant change in the length L of the sheath.

[0128] FIG. 14 illustrates radial expansion of the sheath 8 as a prosthetic device (for example, implant 12) is passed through the sheath 8 in the direction of arrow 132 (for example, distally). As the prosthetic device (implant 12) is advanced through the sheath 8, the sheath can resiliently expand to a second diameter D2 that corresponds to a size or diameter of the prosthetic device. As the prosthetic device (implant 12) is advanced through the sheath 8, the prosthetic device can apply longitudinal force to the sheath in the direction of motion by virtue of the frictional contact between the prosthetic device and the inner surface of the sheath. However, as noted herein, the inner layer 102 and / or the outer layer 108 can resist axial elongation such that the length L of the sheath remains constant, or substantially constant. This can reduce or prevent the braided layer second 104 from lengthening, and thereby constricting the lumen 112.

[0129] Meanwhile, the angle 9 between the filaments 110A and 110B can increase as the sheath expands to the second diameter D2 to accommodate the prosthetic valve. This can cause the braided second layer 104 to foreshorten. However, because the filaments 110 are not engaged or adhered to the inner layer 102 or outer layer 108, the shortening of the braided second layer 104 attendant to an increase in the angle 0 does not affect the overall length L of the sheath. Moreover, because of the longitudinally-extending ridges 126 formed in the inner layer 102 and outer layer 108, the inner layer 102 and outer layer 108 can expand to the second diameter D2 without rupturing, in spite of being relatively thin and relatively non-elastic. In this manner, the sheath 8 can resiliently expand from its natural diameter Di to a second diameter D2 that is larger than the diameter Di as a prosthetic device is advanced through the sheath, without lengthening, and without constricting. Thus, the force required to push the prosthetic implant through the sheath is significantly reduced.

[0130] Additionally, because of the radial force applied by the elastic third layer 106, the radial expansion of the sheath 8 can be localized to the specific portion of the sheath occupied by the prosthetic device. For example, with reference to FIG. 14, as the prosthetic device (implant 12) moves distally through the sheath 8, the portion of the sheath immediately proximal to the prosthetic device (for example, implant 12) can radially collapse back to the initial diameter Di under the influence of the elastic third layer 106. The inner layer and outer layer 108 can also buckle as the circumference of the sheath is reduced, causing the ridges 126 and the valleys 128to reform. This can reduce the size of the sheath required to introduce a prosthetic device of a given size. Additionally, the temporary, localized nature of the expansion can reduce trauma to the blood vessel into which the sheath is inserted, along with the surrounding tissue, because only the portion of the sheath occupied by the prosthetic device expands beyond the sheath’s natural diameter and the sheath collapses back to the initial diameter once the device has passed. This limits the amount of tissue that must be stretched in order to introduce the prosthetic device, and the amount of time for which a given portion of the vessel must be dilated.

[0131] In some examples layered sheath 8 structure, FIGS. 15-23 illustrate various features of the coaxial layered structure of the expandable sheath 8 of FIG. 1 according to another aspect. Similar reference numbers are used to describe like elements. It is to be understood that the variations (for example, materials and alternate configurations) described herein with reference to FIGS. 11-14 can also apply to the example shown in FIGS. 15-23. Furthermore, the variations described herein with reference to FIGS. 15-23 can also be applied to the sheath described in FIGS. 11-14.

[0132] Similar to various examples of the sheath 8 described herein in reference to FIGS. 11- 14, the sheath 8 of FIGS. 15-23 includes a plurality of layers. For example, the sheath 8 illustrated in FIGS. 15-23, also includes an inner layer 202 and an outer layer 204 disposed around the inner layer 202. The inner layer 202 can define a central lumen 212 through which the delivery apparatus travels into the patient’s vessel in order to deliver, remove, repair, and / or replace a prosthetic device, moving in a direction along the longitudinal axis X. Similar to the sheath illustrated in FIGS. 11-14, as the prosthetic device passes through the sheath 8, the sheath 8 locally expands from a first, resting / unexpanded diameter to a second, expanded diameter to accommodate the prosthetic device. After the prosthetic device passes through a particular' location of the sheath 8, each successive expanded portion or segment of the sheath 8 at least partially returns to the smaller, resting / unexpanded diameter. In this manner, the sheath 8 can be considered self-expanding, in that it does not require use of a balloon, dilator, and / or obturator to expand.

[0133] Similar to the examples herein, the inner and outer layers 202, 204 can comprise any suitable materials. Suitable materials for the inner layer 202 include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), nylon, polyethylene, polyether block amide (for example, Pebax), and / or combinations thereof. In an example sheath 8, the inner layer 202 cancomprise a lubricious, low-friction, or hydrophilic material, such as PTFE. Such low coefficient of friction materials can facilitate passage of the prosthetic device through the lumen defined by the inner layer 202. In some examples, the inner layer 202 can have a coefficient of friction of less than about 0.1. Some examples of the sheath 8 can include a lubricious liner on the inner surface of the inner layer 202. Examples of suitable lubricious liners include materials that can further reduce the coefficient of friction of the inner layer 202, such as PTFE, polyethylene, polyvinylidene fluoride, and combinations thereof. Suitable materials for a lubricious liner also include other materials desirably having a coefficient of friction of about 0.1 or less.

[0134] Suitable materials for the outer layer 204 include nylon, polyethylene, Pebax, HDPE, polyurethanes (for example, Tecoflex), and other medical grade materials. In one example, the outer layer 204 can comprise high density polyethylene (HDPE) and Tecoflex (or other polyurethane material) extruded as a composite. In some examples, the Tecoflex can act as an adhesive between the inner layer 202 and the outer layer 204 and may only be present along a portion of the inner surface of the outer layer 204. Other suitable materials for the inner and outer layers are also disclosed in U.S. Patent Nos. 8,690,936 and 8,790,387, which are incorporated herein by reference.

[0135] Additionally, some examples of the sheath 8 include an exterior hydrophilic coating on the outer surface of the outer layer 204. Such a hydrophilic coating can facilitate insertion of the sheath 8 into a patient’s vessel. Examples of suitable hydrophilic coatings include the Harmony™ Advanced Lubricity Coatings and other Advanced Hydrophilic Coatings available from SurModics, Inc., Eden Prairie, MN. DSM medical coatings (available from Koninklijke DSM N.V., Heerlen, the Netherlands), as well as other hydrophilic coatings (for example, PTFE, polyethylene, poly vinylidene fluoride), are also suitable for use with the sheath 8.

[0136] FIGS. 15-23 illustrate an example sheath system 200. FIG. 16 provides a partial crosssection of the distal end of the sheath 8 along section line 16-16 identified in FIG. 15. As described herein, the sheath 8 can be inserted into a vessel (for example, the femoral or iliac arteries) by passing through the skin of patient, such that a soft tip portion 206 at the distal end 210 of the sheath 8 is inserted into the vessel. As best seen in FIG. 16, the soft tip portion 206 can comprise, in some examples, low density polyethylene (LDPE) and can be configured to minimize trauma or damage to the patient’s vessels as the sheath is navigated through the vasculature. For example, the soft tip portion 206 can be slightly tapered to facilitate passagethrough the vessels. The soft tip portion 206 can he secured to the distal end 210 of the sheath 8, such as by thermally bonding the soft tip portion 206 to the inner and outer layers of the sheath 8. Such a soft tip portion 206 can be provided with a lower hardness than the other portions of the sheath 8. In some examples, the soft tip portion 206 can have a Shore hardness from about 25D to about 40D. The soft tip portion 206 is configured to be radially expandable to allow a prosthetic device to pass through the distal opening of the sheath 8. For example, the soft tip portion 206 can be formed with a weakened portion, such as an axially extending score line or perforated line that is configured to split and allow the soft tip portion 206 to expand radially when the prosthetic device passes therethrough.

[0137] FIG. 17 shows a cross-sectional view of the sheath 8 taken near the distal end 210 of the sheath 8 as indicated by section line 17-17 in FIG. 16. As illustrated in FIGS. 16 and 17, the sheath 8 can include at least one radiopaque filler or marker, such as a discontinuous, or C- shaped, band / marker 216 positioned near the distal end 210 of the sheath 8. The marker 216 can be associated with the inner and / or outer layers 202, 204 of the sheath 8. For example, as shown in FIG. 17, the marker 216 can be positioned between the inner layer 202 and the outer layer 204. In some examples, the marker 216 can be associated with the outer surface of the outer layer 204. In some examples, the marker 216 can be embedded or blended within the inner or outer layers 202, 204.

[0138] FIGS. 18 and 19 show additional cross-sections taken at different points along the sheath 8. FIG. 18 shows a cross-section of a segment of the sheath near the proximal end 214 of the sheath 8, as indicated by section line 18-18 in FIG. 15. At this location, the sheath 8 includes the inner layer 202, outer layer 204, elastic outer layer 250 / outer jacket, and the strain relief layer 26. At this location, near the proximal end of the sheath 8, the inner and outer layers 202, 204 are substantially tubular. Here the inner and outer layers 202, 204 can be formed without any slits or folded portions in the layers. By contrast, as described herein, the inner and outer layers 202, 204 at different locations along the sheath 8 (for example, at the point indicated by section line 19-19 in FIG. 15 and / or the point indicated by line section 22-22 in FIG. 21) can have a different configuration.

[0139] As shown in FIG. 19, the inner layer 202 can be arranged to form a substantially cylindrical central lumen 212 therethrough. Inner layer 202 can include one or more folded portions 218. In the example shown in FIG. 19, inner layer 202 is arranged to have one foldedportion 218 that can be positioned on either side of the inner layer 202. Inner layer 202 can be continuous, in that there arc no breaks, slits, or perforations in inner layer 202. Outer layer 204 can be arranged in an overlapping fashion such that an overlapping portion 220 overlaps at least a part of the folded portion 218 of the inner layer 202. As shown in FIG. 19, the overlapping portion 220 also overlaps an underlying portion 222 of the outer layer 204. The underlying portion 222 can be positioned to underlie both the overlapping portion 220 of the outer layer 204, as well as the folded portion 218 of the inner layer 202. Thus, the outer layer 204 can be discontinuous, in that it includes a slit or a cut in order to form the overlapping portion 220 and underlying portion 222. In other words, a first edge 224 of the outer layer 204 is spaced apart from a second edge 225 of the outer layer 204 so as not to form a continuous layer.

[0140] As shown in FIG. 19, the sheath 8 can also include a thin layer of bonding or adhesive material 228 positioned between the inner layer 202 and outer layer 204. In one example, the adhesive material 228 can comprise a polyurethane material such as Tecoflex. The adhesive material 228 can be positioned on an inner surface 230 of at least a portion of the outer layer 204 so as to provide adhesion between selected portions of the inner layer 202 and outer layer 204. For example, the outer layer 204 may only include a Tecoflex layer (adhesive material 228) around the portion of the inner surface 230 that faces the lumen-forming portion of the inner layer 202. In other words, the Tecoflex layer (adhesive material 228) can be positioned so that it does not contact the folded portion 218 of the inner layer 202 in some examples. In some examples, the Tecoflex can be positioned in different configurations as desired for the particular application. For example, as shown in FIG. 19, the Tecoflex layer can be positioned along the entire inner surface 230 of the outer layer 204. In some examples, the Tecoflex layer can be applied to the outer surface of the inner layer 202 instead of the inner surface of the outer layer 204. The Tecoflex layer can be applied to all or selected portions on the inner layer 202; for example, the Tecoflex layer can be formed only on the portion of the inner layer 202 that faces the lumen-forming portion of the outer layer 204 and not on the folded portion 218. The configuration of FIG. 19 allows for radial expansion of the sheath 8 as an outwardly directed radial force is applied from within (for example, by passing a medical device such as a prosthetic heart valve through the central lumen 212). As radial force is applied, the folded portion 218 can at least partially separate, straighten, and / or unfold, and / or the overlapping portion 220 and theunderlying portion 222 of the outer layer 204 can slide circumferentially with respect to one another, thereby allowing the diameter of central lumen 212 to enlarge.

[0141] In this manner, the sheath 8 is configured to expand from a resting / unexpanded configuration (FIG. 19) to an expanded configuration shown in FIG. 20. In the expanded configuration, as shown in FIG. 20, a gap 232 can form between the longitudinal edges of the overlapping portion 220 and the underlying portion 222 of the outer layer 204. As the sheath 8 expands at a particular location, the overlapping portion 220 of the outer layer 204 can move circumferentially with respect to the underlying portion 222 as the folded portion 218 of the inner layer 202 unfolds. This movement can be facilitated by the use of a low-friction material for inner layer 202, such as PTFE. Further, the folded portion 218 can at least partially separate and / or unfold to accommodate a medical device having a diameter larger than that of central lumen 212 in the resting / unexpanded configuration. As shown in FIG. 20, in some examples, the folded portion of the inner layer 202 can completely unfold, so that the inner layer 202 forms a cylindrical tube at the location of the expanded configuration.

[0142] Similar to the example sheath 8 in FIG. 14, the sheath 8 is configured to locally expands at a particular location corresponding to the location of the medical device along the length of the central lumen 212, and then locally contracts once the medical device has passed that particular location. Thus, a bulge may be visible, traveling longitudinally along the length of the sheath 8 as a medical device is introduced through the sheath 8, representing continuous local expansion and contraction as the device travels the length of the sheath 8. Each segment of the sheath 8 will locally contract after removal of any radial outward force such that the sheath 8 at least partially returns to the original resting / unexpanded diameter of central lumen 212. Similar to the example sheath described herein, an elastic outer layer 250 can (optionally) be provided along the sheath 8, urging the inner and outer layers 202, 204 back to the unexpanded configuration.

[0143] The layers 202, 204 of sheath 8 can be configured having the folded portion 218 as shown in FIG. 19 along at least a portion of the length of the sheath 8. In some examples, the inner and outer layers 202, 204 can be configured as shown in FIG. 19 along the length A (FIG. 15) such that the folded portion 218 extends from a location adjacent the soft tip portion 206 to a location closer to the proximal end 214 of the sheath 8, adjacent and / or under the distal end of the strain relief layer 26. In this matter, the sheath 8 is expandable and contractable only along aportion of the length of the sheath corresponding to length A (which can correspond to the section of the sheath inserted into the narrowest section of the patient’s vasculature).

[0144] In some examples, the folded portion 218 portion extends from a location adjacent the soft tip portion 206 under the strain relief layer 26, as illustrated in FIG. 21. In this example, the folded structure of the inner layer 202 extends from the soft tip portion 206, under the strain relief layer 26 and along the tapered portion 248 of the strain relief layer 26.

[0145] FIGS. 22 and 23 illustrate cross-sectional views of the sheath 8 taken along the strain relief layer 26 at section line 22-22 in FIG. 21. In this example, the folded portion 218 of the inner layer 202 extends under the strain relief layer 26. FIG. 22 shows a cross-section of the sheath 8 in a resting / unexpanded configuration having an inner diameter Di. FIG. 23 shows a cross-section of the sheath 8 in a (partially) expanded configuration, having an inner diameter D2, where D2 is greater than Di.

[0146] As shown in FIGS. 22-23, in some examples, the overlapping portion 220 does not overlap the entire folded portion 218 of the inner layer 202, and thus a portion of the folded portion 218 can be directly adjacent to the strain relief layer 26 in locations where the strain relief layer 26 is present. In locations where the strain relief layer 26 is not present, part of the folded portion 218 may be visible from the outside of the sheath 8, as seen in FIG. 21 (and / or visible through an elastic outer layer 250 described in more detail herein). In these examples, the sheath 8 can include a longitudinal seam 234 where the overlapping portion 220 terminates at the folded portion 218. In use, the sheath 8 can be positioned such that the seam 234 is posterior to the point of the sheath that is 180 degrees from the seam 234 (for example, facing downward in the view of FIG. 21). As shown in FIG. 21, the seam 234 need not extend the entire length of the sheath 8, and end at a transition point between portions of the sheath having a folded inner layer and portions of the sheath not having a folded inner layer.

[0147] In some examples, the folded portion 218 can include a weakened portion 236, such as a longitudinal perforation, score line, and / or slit, along at least a portion of the length of the inner layer 202. The weakened portion 236 / slit allows for the two adjacent ends 238, 240 of the folded portion 218 / inner layer 202 to move relative to one another as the sheath 8 expands to the expanded configuration shown in FIG. 23. For example, the sheath 8 locally expands as a medical device is inserted therethrough, causing the weakened portion 236 to split / separate.

[0148] In each of the example sheaths 8 described herein, the sheath 8 may include an elastic outer layer 250 that expands with the sheath 8. The clastic outer layer 250 can provide an inwardly directed radial force that directs the sheath to a folded / unexpanded configuration. Similar to the strain relief layer 26, elastic outer layer 250 can also provide hemostasis (for example, prevent blood loss during implantation of the prosthetic device).

[0149] The elastic outer layer 250 can be positioned around at least a portion of the strain relief layer 26, outer layer 108, 204 and / or the inner layers of the sheath 8. As illustrated in FIGS. 21- 23, the elastic outer layer 250 can surround the entire circumference of outer layer 204, and can extend longitudinally along any portion of the length of the sheath 8, including along (over or under) the strain relief layer 26. The elastic outer layer 250 extends for a length along at least a portion of the main body of the sheath 8. In some examples, the elastic outer layer 250 extends to a point adjacent the distal end 210, or can extend all the way to the distal end 210 of sheath 8. For example, the elastic outer layer 250 extends over the entire length of the sheath 8.

[0150] As shown in FIGS. 17-20, 22 and 23, the elastic outer layer 250 can be a continuous tubular layer, without slits or other discontinuities. The elastic outer layer 250 extends between strain relief layer 26 and the outer surface of the outer layer 204. In some examples, the elastic outer layer 250 extends over the outer surface of the strain relief layer 26 and the outer surface of the outer layer 204. In some examples, the elastic outer layer 250 extends both over the strain relief layer 26 and / or between the outer layer of the sheath 8 and the strain relief layer 26.

[0151] The elastic outer layer 250 can comprise any pliable, elastic material(s) that expand and contract, preferably with a high expansion ratio. Preferably, the materials used can include low durometer polymers with high elasticity, such as Pebax, polyurethane, silicone, and / or polyisoprene. Materials for the elastic outer layer 250 can be selected such that it does not impede expansion of the inner and outer layers of the sheath 8. The elastic outer layer 250 can have a thickness ranging from, for example, about 0.001 inches to about 0.010 inches. In some examples, the elastic outer layer 250 can have a thickness of about 0.003 inches to about 0.006 inches. The elastic outer layer 250 can be configured to stretch and expand as the sheath expands, as shown in the expanded configuration in FIG. 20.

[0152] As illustrated in FIGS. 2, 15, and 21, the sheath 8 in each of the examples described herein may include a strain relief layer 26. The strain relief layer 26 is provided adjacent the proximal end of the sheath 8 and extends along / over the outer surface of the sheath 8. In someexamples, the strain relief layer 26 is provided over the outer layer 108, 204 of the sheath 8. The strain relief layer 26 forms a smooth transition between the sheath hub 20 and the sheath 8 and facilitates mating of the sheath 8 with the sheath hub 20.

[0153] Additionally, and as will be described in more detail herein, the strain relief layer 26 provides a region of higher durometer or stiffness that restricts expansion of the underlying sheath layers. This helps to ensure hemostasis between the portions of the sheath 8 inside the patient and the sheath hub (external to the patient). The increased durometer and / or stiffness along the strain relief layer 26 prevents blood from flowing between the various layers of the sheath 8 exterior to the patient during the procedure, helping to withstand the blood pressure that would otherwise cause the sheath to “balloon up” with body fluid / blood. Additionally, the strain relief layer 26 can be sized and configured to form a seal with the patient’s artery when inserted, such that blood is substantially prevented from flowing between the strain relief layer 26 and the vessel wall. For example, although the strain relief layer 26 does not extend all the way to the distal end 210 of the sheath 8, the strain relief layer 26 can extend distally enough along the sheath 8 that when the sheath 8 is fully inserted into the patient a portion of the strain relief layer 26 extends through and seals against the arteriotomy site.

[0154] As described herein, the strain relief layer 26 is provided over the outer layer 108, 204 of the sheath 8. The strain relief layer 26 can be bonded to the outer layer 108, 204 to prevent the strain relief layer 26 from sliding over the outer layer and “bunching up” in response to the friction forces applied by the surrounding tissue during insertion of the sheath 8 into the patient’s vasculature. For example, the strain relief layer 26 can be bonded at the proximal end and / or distal end of the outer layer 108, 204. At the proximal and distal ends, the strain relief layer 26 can be bonded to the outer layer 204 around the full circumference of the outer layer. At the distal end of the sheath 8, the strain relief layer 26 can additionally and / or alternatively be bonded to the inner layer) s) of the sheath 8. For example, the strain relief layer 26 can be bonded to the distal end surface of the inner layer 102, 202.

[0155] FIGS. 18, 22 and 23 illustrate cross-sectional views of the sheath 8 along the strain relief layer 26. FIG. 18 shows a cross-section of a segment of the sheath near the proximal end 214 of the sheath 8, as indicated by line 18-18 in FIG. 15. Similarly, FIGS. 22 and 23 show cross-section segments of various example sheaths near the proximal end 214 of the sheath 8 and closer to the distal end of the strain relief layer 26, as indicated by section line 22-22 in FIG. 21.As illustrated in each of FIGS. 15-23, the sheath 8 at this location can comprise a liner / inner layer 202, outer layer 204, adhesive material 228, an optional clastic outer layer 250, and the strain relief layer 26.

[0156] The strain relief layer 26 extends circumferentially around at least a portion of the inner layer 202 and outer layer 204. The strain relief layer 26 extends from the proximal end 214 of the sheath 8 towards the distal end 210 of the sheath 8. As shown in FIG. 21 (and FIG. 15), the strain relief layer 26 extends for a length L along at least a portion of the main body of the sheath 8. In some examples, the strain relief layer 26 extends to a point adjacent the distal end 210, or can extend all the way to the distal end 210 of sheath 8. In some examples, the longitudinal length L of the strain relief layer 26 can range from about 10 cm to the entire length of the sheath 8.

[0157] The strain relief layer 26 extends to / adjacent the proximal end 214 of the sheath 8 and provides a compression fit over the distal end of the sheath hub 20 thereby coupling the sheath 8 to the sheath hub 20. Additionally, or alternatively, the strain relief layer 26 secured between the sheath hub 20 and the sheath hub cap 22 or other fastening device for by coupling the proximal end of the sheath to the sheath hub 20. In some examples, the strain relief layer 26 does not extend all the way to the proximal end 214 of the sheath 8.

[0158] It is understood that strain relief layer 26, as shown herein, can have similar composition and characteristics of the inner and outer layers as disclosed herein. Various compositions are disclosed, for example, in Application No. PCT / US2021 / 301275, entitled “Expandable sheath for introducing an endovascular delivery device into a body,” the disclosure of which is herein incorporated by reference.

[0159] The strain relief layer 26 can comprise any lubricious, low-friction, and / or relatively non-elastic material. Preferably the materials used can include high durometer polymers, with low elasticity. In some examples, the strain relief layer 26 is composed of the same and / or similar material to the inner layer 202 and / or outer layer 204. For example, as described herein regarding the inner layer 102 and / or outer layer 108, exemplary materials can include polyurethane (for example, high density polyethylene), ultra-high-molecular-weight polyethylene (UHMWPE) (for example, Dyneema®), high-molecular- weight polyethylene (HMWPE), or poly ether ether ketone (PEEK). Other suitable materials strain relief layer 26 can include polyimide, polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), ethylene tetrafluoroethylene (ETFE), nylon, polyethylene, polyamide, poly ether block amide (forexample, Pebax), and / or combinations of any of the herein. Materials for the strain relief layer 26 can be selected such that it impedes expansion of the underlying layers of the sheath 8.

[0160] The strain relief layer 26 can have a thickness ranging from, for example, about 0.001 inches to about 0.010 inches. In some examples, the strain relief layer 26 can have a thickness of from about 0.003 inches to about 0.006 inches. The wall thickness is measured radially between the inner surface of the strain relief layer 26 and the outer surface of the strain relief layer 26.

[0161] In some examples, the material composition and / or wall thickness can change along the length of the strain relief layer 26. For example, the strain relief layer 26 can be provided with one or more segments, where the composition and / or thickness changes from segment to segment. In an example aspect, the Durometer rating of the composition changes along the length of the strain relief layer 26 such that segments near the proximal end comprise a stiffer material or combination of materials, while segments near the distal end comprise a softer material or combination of materials. Similarly, the wall thickness of the strain relief layer 26 in segments near the proximal end can be thicker / greater than the wall thickness of the elastic outer layer 250 near the distal end.

[0162] As illustrated in FIGS. 15 and 21, the strain relief layer 26 has a proximal end and a distal end and a central lumen extending longitudinally therethrough. The strain relief layer 26 includes a generally tubular shaped proximal portion 242 adjacent the proximal end of the strain relief layer 26, and a generally tubular shaped distal portion 246 adjacent the distal end of the strain relief layer 26. The strain relief layer 26 includes a frustoconical shaped tapered portion 248 extending between the proximal portion 242 and the distal portion 246 of the strain relief layer 26, such that the diameter of the strain relief layer 26 at the proximal portion 242 is greater than the diameter of the strain relief layer 26 at the distal portion 246 of the strain relief layer 26. The tapered portion 248 and the flared proximal portion 242 help ease the transition of the medical device / delivery apparatus when passing between the larger diameter sheath hub 20 to the smaller diameter of the sheath 8.

[0163] As described herein, the strain relief layer 26 is made of a material that is stiffer than the other sheath 8 layers such that the strain relief layer 26 inhibits expansion of the portion of the sheath disposed along / under the strain relief layer 26. Because radial expansion is limited along the strain relief layer 26, higher push forces are necessary to advance the medical device through the central lumen of the sheath 8. In some examples, the highest push forces through the sheath 8are experienced near the proximal and distal ends of the sheath 8, through the strain relief layer 26 (for example, through the tapered portion of the strain relief layer 26), and at proximal and distal ends of the strain relief layer 26.

[0164] As described herein, it is desirable to reduce push forces required to insert the medical device / delivery apparatus through the central lumen of the sheath 8. In some examples, the thickness and / or composition of the strain relief layer 26 and / or sheath 8 can be adjusted to improve the performance of the sheath 8 and reduce the push force. In some examples, dilating or expanding the sheath 8 (or a portion thereof) before the medical device / delivery apparatus is introduced helps to reduce the initial push force through the sheath 8. Pre-dilating the sheath 8 releases and / or loosens any bonding or adhesion of the sheath 8 layers that occurs during the manufacturing process, for example, bonding between the inner and outer layers 202, 204, bonding between the folded portion 218 and outer layer 204, bonding between the inner / outer layers and the strain relief layer 26. Pre-dilating can also break or separate the weakened portion 236 of folded portion 218 of the inner layer 202, separating adjacent ends 238, 240 of the folded portion 218, as described herein and illustrated in FIG. 23. With the sheath 8 layers able to move freely with respect to the other, the medical device / delivery apparatus is pushed through the sheath 8 lumen at a much lower force.

[0165] In some instances, intraluminal medical devices introduced into a patient’s body lumen may become damaged. As used herein, intraluminal devices include any device that is placed in a body lumen. Various examples of intraluminal devices include stents, stented grafts, expandable balloons, and implant catheters. While in some examples, the body lumen is vascular' (for example, veins and arteries), further examples of body lumens may be non- vascular (for example, esophagus, ducts of the biliary tree, intestine, urethra, fallopian tube, other endocrine or exocrine ducts). In such instances, it is desirable to retrieve the intraluminal medical device from the patient to reduce the risk of injury and / or to reinitiate the procedure. However, it is possible that such a medical device could be irregularly shaped, too large in size, or otherwise configured in such a way that the medical device cannot be easily retrieved within the lumen of an introducer sheath. In some instances, an intraluminal medical device may begin at a size and shape that would allow capture and retrieval through a lumen of a sheath but adopts an irregular shape or expanded sizes when damaged. For example, in some instances, it is possible for an expandable balloon, such as a balloon inflatable delivery system, to rupture radially such that aportion of the balloon is oriented convex relative to the delivery apparatus. In such instances, traditional sheaths may not be able to accommodate the medical device. Accordingly, it is desirable for a sheath, particularly a distal region of the sheath, to be expandable so as to facilitate retrieval of an intraluminal medical device.

[0166] The present disclosure provides an example expandable sheath system 300 that can be used retrieve intraluminal medical devices from a body lumen of a patient. The expandable sheath system 300 is described in reference to FIGS. 24A-34B and includes an expandable sheath 301 that includes a first layer 302 and a second layer 310 radially outward of the first layer 302, the first layer 302 defining a lumen extending longitudinally within the first layer 302. The expandable sheath system 300 is movable between a neutral configuration and an expanded configuration and / or contracted configuration by moving the first layer 302 and the second layer 310 relative to each other. As provided herein, moving the first layer 302 relative to the second layer 310 or the second layer 310 relative to the first layer 302 in an axial direction expands or contracts the central lumen 308 at a distal region 306 of the first layer 302.

[0167] It is contemplated herein that the expandable sheath system 300 can be used individually and / or with other components described herein in reference to FIGS. 1-23, such as the delivery apparatus 10 or the implant 12. Furthermore, it is contemplated that the expandable sheath system 300 can be formed and used individually and / or be integrated into another expandable sheath, including the sheath 8 as described herein or sheaths having different layered sheath structures than those described herein.

[0168] FIGS. 24A-24C show side views of the expandable sheath system 300. As shown in FIG. 24A, the expandable sheath system 300 includes an expandable sheath 301 that can include a number of layers including a first layer 302 and a second layer 310 disposed radially outward of the first layer 302. The first layer 302 includes a proximal region 304 and a distal region 306 and the second layer 310 includes a proximal region 312 and a distal region 314. In the illustrated example, an optional outer layer 328 is disposed radially outward of the second layer 310. Furthermore, as provided herein, the first layer 302, second layer 310, and outer layer 328 are radially expandable. Additionally, the first layer 302, second layer 310, and / or outer layer 328 may optionally include any of the characteristics described herein with respect to the inner layer 102, second layer 104, third layer 106, and / or outer layer 108 in reference to FIGS. 11-14. For instance, in some examples, the first layer 302, second layer 310, and / or outer layer 328 mayoptionally include a lubricious and / or low-friction material. In further examples, the outer layer 328 may optionally be clastic. For example, the outer layer 328 may include one or more of polyethylene (for example, high-density polyethylene or low-density polyethylene), silicon, or polyurethane. In further examples, the outer layer 328 may be in the form of a coating disposed over the second layer 310. In still further examples, the expandable sheath 301 may include one or more additional layers including any of the characteristics described herein.

[0169] In the illustrated examples, the outer layer 328 extends along an entire length of the second layer 310. However, in further examples, the outer layer 328 may optionally extend over only a portion of the length of the second layer 310. For example, the outer layer 328 may optionally extend over only a length of the second layer 310 corresponding to the distal region 314. In yet further examples, the outer layer 328 may optionally extend over only the distal-most ends of the first layer 302 and / or distal region 314.

[0170] In the illustrated configuration, the first layer 302 defines a central lumen 308 of the expandable sheath 301 extending longitudinally between the proximal region 304 and the distal region 306 of the first layer 302. The most distal portion of the distal region 306 defines a distal opening 315 of the central lumen 308 through which retrieval instruments may travel into the patient’s body lumen and through which a medical device may be removed along the longitudinal axis of the expandable sheath 301. The central lumen 308 has distal diameter (DD) defined by the diameter of the central lumen 308 near the distal region 306 of the first layer 302 and a proximal diameter (DP) defined by the diameter of the central lumen 308 near the proximal region 304 of the first layer 302. In some aspects, the proximal diameter (DP) is measured at a location distal to a proximal tapered portion 248 as shown in FIG. 21. As provided herein, the diameter of the central lumen 308 of the expandable sheath 301 may be configured to increase or decrease sharply or gradually along the length of the central lumen 308 between the distal region 306 and the proximal region 304. As used herein, in some aspects, the term distal diameter (DD) refers to the diameter of the central lumen 308 at the most distal portion of the first layer 302 (for example, the distal opening 315) and the term proximal diameter (DP) refers to the diameter of the central lumen 308 at the most proximal portion of the first layer 302.

[0171] Advantageously, the first layer 302 and the second layer 310 are movable relative to each other in an axial direction along the longitudinal axis of the expandable sheath 301. In the illustrated example, the first layer 302 and second layer 310 are depicted as spaced apart forillustrative purposes. However, as contemplated herein, the first layer 302 and second layer 310 may be in direct contact along all or part of respective lengths of the first layer 302 and second layer 310. In such examples, the first layer 302 and second layer 310 are slidable relative to each other where in direct contact. Furthermore, as shown in the illustrated example, the distal region 306 of the first layer 302 and the distal region 314 of the second layer 310 are coupled together such that relative axial movement along the longitudinal axis causes the central lumen 308 to flare radially outward or contract radially inward at the distal region 306. Specifically, in the illustrated example, the first layer 302 and the second layer 310 are formed from a single continuous layer of material that is folded back onto itself so as to form the distal region 306 of the first layer 302 and the distal region 314 of the second layer 310. However, in other examples, such as the expandable sheath system 300 shown in FIG. 25, the first layer 302 and the second layer 310 are two discretely formed layers that are joined at the distal region 306 of the first layer 302 and the distal region 314 of the second layer 310. In such examples, the distal region 306 of the first layer 302 may be coupled to the distal region 314 of the second layer 310 by at least one of a chemical bond, weld, and / or adhesive, so long as the distal region 306 of the first layer 302 remains coupled to the distal region 314 of the second layer 310 as the first layer 302 and second layer 310 move with respect to each other. When coupled, the distal region 306 of the first layer 302 and the distal region 314 of the second layer 310 together define a distal tip 307 of the expandable sheath 301.

[0172] In the illustrated example shown in FIG. 24A, the expandable sheath system 300 also includes an optional collar 316 that extends around the first layer 302 between the first layer 302 and the second layer 310. In the illustrated example, the collar 316 extends around an entire circumference of the first layer 302. However, in further examples, the collar 316 may optionally extend around only a portion of the circumference of the first layer 302. In some examples, including the illustrated example, the collar 316 resists radially outward expansion, thereby resisting radial expansion of the first layer 302 at the location along the first layer 302 at which the collar 316 is positioned, as shown in FIG. 24B. Specifically, the collar 316 is positioned at a location along the first layer 302 longitudinally offset from the distal region 306. The region of the first layer 302 over which the collar 316 extends is herein referred to as the constrained portion 318 of the first layer 302. Furthermore, the collar 316 may optionally resist radially inward contraction of the first layer 302, as shown in FIG. 24C. In further examples, the collar316 may be coupled to the first layer 302. For example, the collar 316 may be coupled to the first layer 302 by at least one of a chemical bond, weld, and / or adhesive.

[0173] The present disclosure provides methods of controlling expansion and contraction of an expandable sheath system 300. In the example illustrated in FIG. 24A, the expandable sheath system 300 is in the neutral configuration. In the neutral configuration, the distal diameter (DD) of a central lumen 308 is substantially the same as the proximal diameter (DP) of the central lumen 308. As used herein with the central lumen 308, the terms “substantially the same” and “substantially constant” mean that diameter of the central lumen 308 at a first reference location (for example, at the distal diameter (DD)) increases or decreases by not more than 1%, by not more than 5%, or by not more than 10% relative to the diameter of the central lumen 308 at a second reference location (for example, at the proximal diameter (DP)).

[0174] FIG. 24B shows the expandable sheath system 300 moved into the expanded configuration. In the expanded configuration, the distal diameter (DD) of the central lumen 308 of the expandable sheath 301 is radially expanded relative to the proximal diameter (DP). In other words, the diameter of the distal opening 315 increases as the expandable sheath system300 moves from the neutral configuration to the expanded configuration. As provided herein, moving the expandable sheath system 300 to the expanded configuration involves deflecting the distal region 306 of the first layer 302 away from the longitudinal axis of the expandable sheath301 so as to radially expand the distal diameter (DD) at or near the distal opening 315. In some examples, the expandable sheath 301 can be regarded as being in the expanded configuration when the distal diameter (DD) at or near’ the distal opening 315 of the central lumen 308 is 150 to 250% greater than the proximal diameter (DP) of the central lumen 308. For example, the expandable sheath 301 can be regarded as being in the expanded configuration when the distal diameter (DD) at or near the distal opening 315 of the central lumen 308 is 175 to 225% greater than the proximal diameter (DP) of the central lumen 308.

[0175] As shown in FIG. 24B and further described herein, moving the second layer 310 proximally relative to the first layer 302 causes the distal region 314 of the second layer 310 to exert a proximally-directed force on the distal region 306 of the first layer 302 that is transformed into a force with a radially-outward component. In response, the distal region 306 of the first layer 302 flares outward, thereby increasing the distal diameter (DD). Advantageously, increasing the distal diameter (DD) facilitates easier retrieval of transluminal medical devices.

[0176] Furthermore, in the illustrated example, the location along the first layer 302 at which the distal region 306 begins to flare outward is at least in part controlled by the axial location of the collar 316 relative to the distal region 306, as previously described. Specifically, FIG. 24B shows the central lumen 308 having a substantially constant diameter between the proximal diameter (DP) and the constrained portion 318 under the collar 316. Then, in response to the proximally-directed force on the distal region 306 of the first layer 302, the distal region 306 flares smoothly outward beginning at the collar 316. In further examples, a comparable effect may be achieved by moving the first layer 302 distal relative to the second layer 310.

[0177] FIG. 24C shows the expandable sheath system 300 moved into the contracted configuration. In the contracted configuration, the distal diameter (DD) of the central lumen 308 of the expandable sheath 301 is radially reduced relative to the proximal diameter (DP). In other words, the diameter of the distal opening 315 decreases as the expandable sheath system 300 moves from the neutral configuration to the contracted configuration. As provided herein, moving the expandable sheath system 300 to the contracted configuration involves deflecting the distal region 306 of the first layer 302 toward from the longitudinal axis of the expandable sheath 301 so as to radially reduce the distal diameter (DD) at or near' the distal opening 315. In some examples, the expandable sheath 301 can be regarded as being in the contracted configuration when the distal diameter (DD) at or near the distal opening 315 of the central lumen 308 is 20 to 40% less than the proximal diameter (DP) of the central lumen 308. For example, the expandable sheath 301 can be regarded as being in the contracted configuration when the distal diameter (DD) at or near the distal opening 315 of the central lumen 308 is 25 to 33% less than the proximal diameter (DP) of the central lumen 308.

[0178] As shown in FIG. 24C and further described herein, moving the second layer 310 distally relative to the first layer 302 causes the distal region 314 of the second layer 310 to exert a distally-directed force on the distal region 306 of the first layer 302 that is transformed into a force with a radially-inward component. In response, the distal region 306 of the first layer 302 pinches inward, thereby decreasing the distal diameter (DD) such that the central lumen 308 narrows toward the distal region 306 of the first layer 302. Advantageously, decreasing the distal diameter (DD) reduces push forces needed to advance the expandable sheath 301 into the body lumen of the patient. Such a configuration of the distal region 306 also allows for improved atraumatic advancement through the body lumen. In some examples, reducing the push forcesneeded to advance the expandable sheath 301 through the body lumen as described herein can reduce the need for an introducer. Furthermore, decreasing the distal diameter (DD) provides the added advantage of improving retention of the transluminal medical device once drawn into the central lumen 308 during retrieval.

[0179] Furthermore, in the illustrated example, the location along the first layer 302 at which the distal region 306 begins to pinch inward is at least in part controlled by the axial location of the collar 316 relative to the distal region 306, as previously described. Specifically, FIG. 24C shows the central lumen 308 having a substantially constant diameter between the proximal diameter (DP) and the constrained portion 318 under the collar 316. Then, in response to the distally-directed force on the distal region 306 of the first layer 302, the distal region 306 smoothly pinches inward beginning at the collar 316. In further examples, a comparable effect may be achieved by moving the first layer 302 proximal relative to the second layer 310.

[0180] In various examples, including the example shown in FIGS. 24A-24C, the expandable sheath system 300 is reversibly movable between the neutral configuration and the expanded configuration and / or between the neutral configuration and the contracted configuration. For example, the expandable sheath system 300 may be moved from the contracted configuration to the expanded configuration by passing the expandable sheath system 300 through the intermediary neutral configuration. Conversely, the expandable sheath system 300 may be moved from the expanded configuration to the contracted configuration by passing the expandable sheath system 300 through the intermediary neutral configuration.

[0181] The extent to which the distal diameter (DD) expands from the neutral configuration to the expanded configuration or contracts from the neutral configuration to the contracted configuration may be controlled by varying the material properties of the various layers and / or the position of the collar’ 316. For example, the stiffness of the first layer 302 and / or second layer 310 may be decreased to facilitate greater expansion / contraction of the distal diameter (DD) at or near- the distal opening 315 or increased to reduce expansion / contraction of the distal diameter (DD) at or near the distal opening 315. Furthermore, the modulus of elasticity of an additional layer, such as the outer layer 328, may be increased to provide an increased radially inward force urging the expandable sheath 301 toward the neutral / contracted configuration. In further examples, the collar 316 may optionally be formed from a rigid material so as to define a set limit to the radial expansion of the first layer 302. In yet further examples, the collar 316 mayoptionally be elastic so as to vary the extent to which the first layer 302 is permitted to radially expand, such as in response to the amount of radially-outward force acting on the collar 316. For example, the collar 316 may optionally permit greater expansion of the distal opening 315 upon application of greater tension forces applied to the second layer 310. In still further examples, instead of or in addition to varying the material properties of the layers, the axial position of the collar 316 along the first layer 302, and therefore the position of the constrained portion 318, may be varied. For example, the spacing at which the collar 316 is longitudinally offset from the distal region 306 may be increased to facilitate greater expansion / contraction of the distal diameter (DD) at or near the distal opening 315 or increased to reduce expansion / contraction of the distal diameter (DD) at or near the distal opening 315.

[0182] In some examples, including the example illustrated in FIG. 24A, the first layer 302 and second layer 310 include an optional braid 319. Specifically, the first layer 302 and second layer 310 are formed from a braided material. However, in further examples, the expandable sheath 301 may optionally include a separate braided layer distinct from or integrated into the first layer 302 and / or second layer 310. Advantageously, the braid 319 provides structural support to the layers of the expandable sheath 301. For instance, in some examples, the braid 319 may be configured to resist deflection relative to the longitudinal axis of the expandable sheath 301. In this way, the materials and configuration of the braid 319 may also be selected to control the extent to which the distal diameter (DD) expands from the neutral configuration to the expanded configuration or contracts from the neutral configuration to the contracted configuration. For instance, in the illustrated example, the braid 319 extends along an entire length of the first layer 302 and second layer 310. However, in further examples, the first layer 302 and / or second layer 310 may include a braid 319 at only their respective distal regions. In such examples, confining the braid 319 to the distal region 306 of the first layer 302 and / or the distal region 314 of the second layer 310 reduces the length of expandable sheath 301 that the braid 319 may be conditioned to urge toward the expanded or contracted configuration.

[0183] In some examples, the braid 319 may be formed from flat wires to reduce the thickness of the layer including the braid 319 as well as the overall diameter of the expandable sheath system 300. Furthermore, flat wires provide the added advantage of facilitating controlled deflection of the braid 319 relative to the longitudinal axis of the expandable sheath 301. For example, a braid 319 that includes wires having a rectangular cross-section will tend to deflect ina direction perpendicular to relatively longer sides of the braid 319. In other words, wires having a non- symmetrical cross-section will tend to deflect in a direction parallel to the relatively thinner side. In further examples, the braid 319 may include round wires. For example, a braid 319 that includes wires having a round cross-section may be deflected in any direction.Furthermore, some examples of the expandable sheath 301 include a braid 319 made out of both flat and round wires.

[0184] In some examples, the braid 319 may optionally be formed from a shape-memory material, such as nitinol. For example, the braid 319 may be formed from nitinol heat set such that the first layer 302 and second layer 310 are heat set in the neutral configuration. In further examples described herein, such as in FIGS. 29A - 29C and 32, the braid 319 may be formed from nitinol heat set such that the first layer 302 and second layer 310 are heat set in the expanded configuration.

[0185] In various examples, the extent to which the distal diameter (DD) at or near’ the distal opening 315 is configured to expand is selected to exceed the dimensions of a medical device targeted for retrieval from the body lumen of a patient. In some examples, the central lumen 308 can have a diameter (including the distal diameter (DD) at or near’ the distal opening 315) of 2.5 mm to 5 mm when in the neutral configuration. When the expandable sheath 301 moves into the expanded configuration for retrieval of a medical device, the central lumen 308 can have a diameter (including the distal diameter (DD) at or near the distal opening 315) of 4 mm to 15 mm. For example, the diameter can be 4.3 mm to 11 mm.

[0186] Referring now to FIGS. 26A-26B, an example expandable sheath system 300 is provided that includes a pull-ring 324 coupled to the distal region 314 of the second layer 310. Pull- wires 326 are coupled to the pull-ring 324 and extend toward the proximal region 312 of the second layer 310 in a position radially outward from the second layer 310. In FIG. 26A, the expandable sheath system 300 is shown in a neutral configuration. As shown in FIG. 26B, application of proximally-directed tension on the pull- wires 326 moves the second layer 310 proximally relative to the first layer 302, thereby moving the expandable sheath system 300 from the neutral configuration to the expanded configuration. While in the illustrated example, the pull-ring 324 is coupled to the distal region 314 of the second layer 310, in further examples, the pull-ring 324 may optionally be coupled directly to the distal region 306 of the first layer 302 or to any other layer of the expandable sheath system 300 so long as proximally directed tension istransformed into a force with a radially-outward component that increases the distal diameter (DD) at or near the distal opening 315. Additionally, the pull-ring 324 shown in the illustrated example is configured to elastically expand as the expandable sheath system 300 moves from the neutral configuration to the expanded configuration and contract as the expandable sheath system 300 is returned from the expanded configuration back to the neutral configuration. In this way, the pull-ring 324 may also serve to control the extent of the expansion of the distal diameter (DD) at or near the distal opening 315. However, in other examples, the pull-ring 324 may be configured to maintain a set diameter such that retraction of the pull-ring 324 in the proximal direction creates a proximally-directed force on the distal region 306 and / or distal region 314 that is transformed into a force with a radially-outward component, thereby increasing the distal diameter (DD) at or near the distal opening 315. Furthermore, the pull-ring 324 and pull- wires 326 may be used in combination with any of the other methods provided herein to move the expandable sheath system 300 from the neutral configuration to the expanded configuration. For example, a proximally-directed tension may be applied to the pull-wires 326 in combination with a distally-directed force applied to the first layer 302.

[0187] Referring now to FIGS. 27A-27B, an example expandable sheath system 300 is provided that includes a pull-ring 324 coupled to the distal region 306 of the first layer 302. Pullwires 326 are coupled to the pull-ring 324 and extend toward the proximal region 304 of the first layer 302 in a position radially inward from the first layer 302. In FIG. 27A, the expandable sheath system 300 is shown in a neutral configuration. As shown in FIG. 27B, application of proximally-directed tension on the pull-wires 326 moves the first layer 302 proximally relative to the second layer 310, thereby moving the expandable sheath system 300 from the neutral configuration to the expanded configuration. While in the illustrated example, the pull-ring 324 is coupled to the distal region 306 of the first layer 302, in further examples, the pull-ring 324 may optionally be coupled to the distal region 314 of the second layer 310 or to any other layer of the expandable sheath system 300 so long as proximally directed tension is transformed into a force with a radially-inward component that reduces the distal diameter (DD) at or near the distal opening 315. Additionally, the pull-ring 324 shown in the illustrated example is configured to elastically contract as the expandable sheath system 300 moves from the neutral configuration to the contracted configuration and expand as the expandable sheath system 300 is returned from the contracted configuration back to the neutral configuration. In this way, the pull-ring 324 mayalso serve to control the extent of reduction of the distal diameter (DD) at or near the distal opening 315. Furthermore, the collar’ 316 may also urge the expandable sheath system 300 toward the contracted configuration. However, in other examples, the pull-ring 324 may be configured to maintain a set diameter such that retraction of the pull-ring 324 in the proximal direction creates a proximally-directed force on the distal region 306 and / or distal region 314 that is transformed into a force with a radially-inward component, thereby reducing the distal diameter (DD) at or near the distal opening 315. Furthermore, the pull-ring 324 and pull- wires 326 may be used in combination with any of the other methods provided herein to move the expandable sheath system 300 from the neutral configuration to the contracted configuration. For example, a proximally-directed tension may be applied to the pull- wires 326 in combination with a distally-directed force applied to the second layer 310.

[0188] Turning to FIGS. 34A-34B, an example expandable sheath system 300 is provided. In the illustrated example shown in FIG. 34A, the second layer 310 of the expandable sheath 301 has a length that is shorter than the length of the first layer 302. Specifically, the second layer 310 extends along the distal region 306 of the first layer 302, but the proximal region 312 of the second layer 310 terminates before reaching the proximal region 304 of the first layer 302. In the illustrated example, the proximal region 312 of the second layer 310 terminates at a location between the distal opening 315 and an opening of a microlumen channel 327, described below. However, in further examples, the shortened second layer 310 may optionally terminate at any location along the length of the first layer 302.

[0189] Furthermore, the pull-ring 324 is coupled to the proximal region 312 of the second layer 310 such that the pull-ring 324 is longitudinally spaced apart from the distal tip 307. As shown, pull-wires 326 are coupled to the pull-ring 324 and extend along an outer surface of the first layer 302 toward the proximal region 304 of the first layer 302 such that they may be operated by a user.

[0190] In some examples, the extent to which the distal diameter (DD) at or near the distal opening 315 is able to increase in the expanded configuration may be controlled by varying the location at which the proximal region 312 of the second layer 310 and couples to the pull-ring 324. In other words, distal expansion may be controlled by varying the location of the pull-ring 324 relative to the distal region 306 of the first layer 302. For example, providing the proximal region 312 / pull-ring 324 relatively further away from the distal region 306 increases the distaldiameter (DD) at or near the distal opening 315 in the expanded configuration. Conversely, providing the proximal region 312 / pull-ring 324 relatively closer to the distal region 306 reduces the distal diameter (DD) of the of the distal opening 315 in the expanded configuration.

[0191] In some examples, including the illustrated example, the expandable sheath 301 may optionally include a microlumen channel 327 extending longitudinally along the expandable sheath 301 that is sized and configured to permit passage of the pull- wires 326 therethrough. As shown, the microlumen channel 327 is defined along an outer surface of the first layer 302. However, in further examples, the microlumen channel 327 may be defined within or between any of the other layers contemplated herein. For example, the microlumen channel 327 may be defined between the first layer 302 and an outer layer 328 disposed radially outward from the first layer 302. In the illustrated example, a distal opening 329 of the microlumen channel 327 is provided at a location just proximate the proximal region 312 of the second layer 310. As such, the pull- wires 326 extending proximally from the proximal region 312 of the second layer 310 extend through the microlumen channel 327 toward the proximal region 312 of the first layer 302.

[0192] The expandable sheath system 300 shown in FIG. 34A is in the neutral configuration. However, as shown in FIG. 34B, application of proximally-directed tension on the pull- wires 326 moves the second layer 310 proximally relative to the first layer 302, thereby moving the expandable sheath system 300 from the neutral configuration to the expanded configuration. As shown, the proximally-directed tension is transformed into a force with a radially-outward component that increases the distal diameter (DD) at or near the distal opening 315.

[0193] In some aspects, push-wires or push-rods can be included, whether additional to the pull-wire 326 or as an alternative to the pull-wire 326.

[0194] Furthermore, the illustrated example includes an outer layer 328 in the form of a coating. Specifically, the outer layer 328 is disposed only at the distal tip 307 of the expandable sheath 301 so as to reduce the risk of vascular trauma upon expansion of the distal opening 315.

[0195] Referring now to FIGS. 28A-28C, an example expandable sheath system 300 is provided that includes expandable sheath 301 with an optional first hollow member 320 coupled to the first layer 302. The first hollow member 320 shown in FIG. 28A comprises a rigid material that is reflowed with the first layer 302 and is configured to transmit an axial force along the length of the first layer 302 over which it extends. As used herein, the term “reflowed” caninclude various methods of bonding, welding, or otherwise adhering the first hollow member 320 with the first layer 302. For example, the first hollow member 320 and first layer 302 may be bonded by any one or more of laser bonding, split die bonding, radial compression bonding, and / or lamination. Accordingly, moving the first hollow member 320 distally moves the distal region 306 of the first layer 302 distally, and moving the first hollow member 320 proximally moves the distal region 306 of the first layer 302 proximally. Because the first hollow member 320 can be configured to extend to the proximal region 304 of the first layer 302, a user may direct an axial force on the first hollow member 320 from location removed from the distal region 306 of the first layer 302. Thus, the first hollow member 320 advantageously facilitates movement of the first layer 302 relative to the second layer 310.

[0196] As shown in FIG. 28A, the first hollow member 320 is longitudinally offset from the distal region 306 of the first layer 302 similar to the collar 316 described herein. Like the collar 316, the extent to which the distal diameter (DD) at or near the distal opening 315 is able to increase in the expanded configuration and / or contract in the contracted configuration may be controlled by varying the material used to form the first hollow member 320 and / or by varying the location along the first layer 302 at which the first hollow member 320 is reflowed. For example, the first hollow member 320 may include a stiffer material to limit deflection of the first layer 302 relative to the longitudinal axis of the expandable sheath 301 or may include a less stiff material to facilitate greater deflection of the 302 relative to the longitudinal axis of the expandable sheath 301. For example, the first hollow member 320 can include one or more polyurethanes (such as Pebax®, ChronoSil®, and Tecoflex™). In some examples, the one or more polyurethanes can be laminated in layers of Dyneema®. In further examples, providing the first hollow member 320 relatively farther away from the distal region 306 increases the distal diameter (DD) at or near the distal opening 315 in the expanded configuration and increases contraction of the distal opening 315 in the contracted state. Conversely, providing the first hollow member 320 relatively closer to the distal region 306 reduces the distal diameter (DD) at or near- the distal opening 315 in the expanded configuration and reduces reduction of the distal diameter (DD) at or near the distal opening 315 in the contracted configuration. While the first hollow member 320 in the illustrated example is reflowed with the first layer 302, the first hollow member 320 may be discrete element, such as a hollow tube disposed radially inward of the first layer 302. For example, the example expandable sheath system 300 shown in FIG. 31includes a first hollow member 320 as a hollow tube disposed radially inward relative to the first layer 302. In the illustrated example, a collar 316 is provided around the first layer 302 at a location corresponding to a distal end of the first hollow member 320, thereby coupling the first layer 302 to the first hollow member 320.

[0197] Furthermore, like the collar’ 316, the first hollow member 320 advantageously resists radially-outward expansion, thereby resisting radial expansion of the first layer 302 at the location along the first layer 302 at which the first hollow member 320 is positioned.Accordingly, in such examples, the constrained portion 318 of the first layer 302 corresponds to the region of the first layer 302 over which the first hollow member 320 and / or collar 316 extends. In some examples, the first hollow member 320 comprises a rigid polymer, for example, polycarbonate. However, any material may be selected for the first hollow member 320 so long as the first hollow member 320 is able to transmit axial forces to the distal region 306 of the first layer 302.

[0198] The expandable sheath 301 shown in FIGS. 28A-28C also includes an optional second hollow member 322 reflowed with the second layer 310. The second hollow member 322 may include any of the qualities described herein with reference to the first hollow member 320, but instead relative to the second layer 310. As shown in FIG. 28B, moving the first hollow member 320 distally relative to the second hollow member 322 and / or the second hollow member 322 proximally relative to the first hollow member 320 moves the expandable sheath system 300 from the neutral configuration to the expanded configuration. Conversely, as shown in FIG. 28C, moving the first hollow member 320 proximally relative to the second hollow member 322 and / or the second hollow member 322 distally relative to the first hollow member 320 moves the expandable sheath system 300 from the neutral configuration to the contracted configuration.

[0199] Turning now to FIGS. 29A-29C, another configuration of the expandable sheath system 300 is provided. In the illustrated example, the expandable sheath 301, the first layer 302 and the second layer 310 may include any of the qualities described herein with reference to FIGS. 24A- 28C, except that the distal region 306 of the first layer 302 is not coupled to the distal region 314 of the second layer 310. For example, the second layer 310 may be a cannula or sheath through which the first layer 302 is delivered into the body lumen. Accordingly, as shown in FIG. 29B, the distal region 306 of the first layer 302 is pre-conditioned to expand radially outward when moved beyond the distal region 314 of the second layer 310 so as to move the expandable sheathsystem 300 from the neutral configuration to the expanded configuration. For example, the distal region 306 of the illustrated example is heat set in the expanded configuration. Specifically, the example expandable sheath 301 provided in FIG. 29 A includes a braid 319 extending to the distal region 306 of the first layer 302. The braid 319 in the illustrated example is formed from nitinol, however, in further examples, the braid 319 may be selected from any material capable of urging the distal region 306 radially outward when moved distally beyond the distal region 314. In the illustrated example, the braid 319 extends an entire length of the first layer 302. However, in further examples, the first layer 302 may optionally contain a braid 319 only at the distal region 306. In yet further examples, the expandable sheath 301 may optionally not contain a braid 319. Additionally, the expandable sheath system 300 may optionally include any of the additional layers described herein with reference to FIGS. 2 A-28C, such as the outer layer 328. Furthermore, in examples such as the one referenced in FIGS. 29A-29C, the distal tip 307 of the expandable sheath 301 is defined on the first layer 302 alone.

[0200] In some examples, including the example illustrated in FIG. 29A, the expandable sheath 301 includes a first hollow member 320 similar to the first hollow member 320 described herein with reference to FIGS. 28A-28C. Accordingly, the expandable sheath system 300 may be moved from the neutral configuration illustrated in FIG. 29A to the expanded configuration illustrated in FIG. 29B by applying an distally-directed axial force to the first hollow member 320, thereby moving the distal region 306 of the first layer 302 distally relative to the distal region 314 of the second layer 310. Conversely, the expandable sheath system 300 may be moved toward the neutral configuration from the expanded configuration by applying a proximally-directed axial force to the first hollow member 320, thereby moving the distal region 306 of the first layer 302 proximally relative to the distal region 314 of the second layer 310.

[0201] In further examples, including the example illustrated in FIG. 29A, the expandable sheath system 300 includes a pull-ring 324 coupled to the distal region 306 of the first layer 302. As shown, pull- wires 326 coupled to the pull-ring 324 extend toward the proximal region 304 of the first layer 302 in a position radially inward from the first layer 302. In FIG. 29C, application of proximally-directed tension on the pull-wires 326 moves the first layer 302 proximally relative to the second layer 310, thereby moving the expandable sheath system 300 from the neutral configuration to the contracted configuration. As shown, the proximally-directed tensionis transformed into a force with a radially-inward component that reduces the distal diameter (DD) at or near the distal opening 315.

[0202] Referring to FIG. 30, an expandable sheath system 300 including an expandable sheath 301 according to various configurations provided herein is shown in the neutral configuration. Specifically, the illustrated expandable sheath 301 is formed from a single nitinol braid 319 that is folded back over itself, thereby forming a first layer 302 that is continuous with a second layer 310. As shown, the folding over of the first layer 302 to form the second layer 310 occurs at the distal tip 307, where the distal region 306 of the first layer 302 transitions into the distal region 314 of the second layer 310. As shown, the first layer 302 is reflowed with a polymeric first hollow member 320.

[0203] Referring to FIG. 31, an expandable sheath system 300 including an expandable sheath 301 according to various configurations provided herein is shown transitioning from the neutral configuration to the expanded configuration. Specifically, the illustrated expandable sheath 301 is formed from a single nitinol braid 319 that is folded back over itself, thereby forming a first layer 302 continuous that is continuous with a second layer 310. As shown, the folding over of the first layer 302 to form the second layer 310 occurs at the distal tip 307, where the distal region 306 of the first layer 302 and the distal region 314 of the second layer 310. As shown, the first layer 302 is reflowed with a polymeric first hollow member 320. Furthermore, the expandable sheath system 300 includes a collar 316 disposed around the first layer 302. As shown, application of a proximally-directed axial force to the second layer 310 moves the expandable sheath system 300 from the neutral configuration to the expanded configuration such that the distal diameter (DD) at or near the distal opening 315 increases.

[0204] Referring to FIG. 32, an expandable sheath system 300 including an expandable sheath301 according to various configurations provided herein is shown transitioning from the neutral configuration to the expanded configuration. In various aspects, the expandable sheath system 300 shown in FIG. 32 is similar’ to the example expandable sheath system 300 previously described with respect to FIGS. 29A-29C. Specifically, the illustrated expandable sheath 301 includes a first layer 302 in which the distal region 306 is not coupled to the distal region 314 of the second layer 310. The second layer 310 is formed as a sheath through which the first layer302 is moved. In the illustrated example, the distal region 314 of the second layer 310 is tapered toward the distal opening 315 to facilitate atraumatic advancement through a body lumen of apatient. As shown, the first layer 302 includes a braid 319. In particular, the braid 319 is formed from nitinol that is heat set to be in the expanded configuration. Specifically, the braid 319 in the illustrated example does not extend along an entire length of the first layer 302. Rather, the braid 319 is located only at or near the distal region 314 of the first layer 302. The braid 319 shown in FIG. 32 further includes a polymeric laminate extending between sections of the braid 319. In the illustrated example, the expandable sheath system 300 is shown moving from the neutral configuration to the expanded configuration by providing a distally-directed axial force to the proximal region 304 of the first layer 302 so as to move the distal region 306 of the first layer 302 beyond the distal region 314 of the second layer 310. As shown, when the distal region 306 of the first layer 302 extends beyond the distal region 314 of the second layer 310, the distal diameter (DD) at or near the distal opening 315 increases.

[0205] As provided herein, the present disclosure includes various methods of retrieving a medical device, such as a transluminal medical device from a body lumen of a patient. Referring to FIG. 33, an expandable sheath system 300 including an expandable sheath 301 according to various configurations provided herein is shown transitioning from the neutral configuration to the expanded configuration and retrieving a medical device. Specifically, the medical device is a ballon catheter that suffered a radial rupture such that the balloon catheter was divided into two radially- wide portions, one concave and the other convex relative to the central lumen 308. As shown, the portion of the balloon catheter that is convex relative to the central lumen 308 (in other words, opens distally) tapers into the central lumen 308 and thus is more readily retrievable. Conversely, the portion of the balloon catheter that is concave relative to the central lumen 308 (in other words, opens proximally) includes margins that are irregular and wider than the distal diameter (DD) at or near the distal opening 315 in the unexpanded neutral configuration. Accordingly, the concave portion of the balloon catheter is not configured for easy retraction into the sheath 301, as it could catch on the distal tip 307 during retrieval.

[0206] The method of retrieving a medical device includes positioning a distal tip 307 of the expandable sheath 301 adjacent a medical device, as shown in FIG. 33. This step may include advancing the expandable sheath 301 through a body lumen of a patient. The method further includes moving the expandable sheath 301 from the neutral configuration toward the expanded configuration by moving the second layer proximally relative to the first layer or the first layer distally relative to the second layer. The particular expandable sheath system 300 in theillustrated example is analogous to the expandable sheath system 300 described herein with reference to FIG. 30. Accordingly, the expandable sheath system 300 is moved from the neutral configuration to the expanded configuration by applying a proximally-directed axial force to the second layer 310, thereby moving the distal region 314 of the second layer 310 relative to the distal region 306 of the first layer 302. In response, the distal diameter (DD) at or near the distal opening 315 increases such that the distal region 306 of the first layer 302 flares outward such that the distal diameter (DD) is at least the size of the medical device. As shown, the medical device is then retracted into the central lumen 308 of the expandable sheath 301, after which the medical device may be removed from the patient.

[0207] The medical device and delivery apparatus can then be advanced into the sheath 8, particularly the portion of the sheath 8 including the strain relief layer 26. In some examples, the medical device is contracted or compressed radially as it passes through the strain relief layer 26, from the proximal portion 242, through the tapered portion 248 and into the smaller diameter distal portion 246.

[0208] As the medical device and delivery apparatus are advanced through the strain relief layer 26, they exert an outwardly directed radial force against the central lumen of the sheath 8, causing the strain relief layer 26 (and corresponding portion of the sheath 8) proximate the medical device / delivery apparatus to locally expand from an unexpanded configuration to an expanded configuration.

[0209] The medical device is then advanced beyond the distal end 27 of the strain relief layer 26, into the lumen of the sheath 8 beyond the strain relief layer 26. As the medical device is advanced through the sheath 8 beyond the strain relief layer 26, the sheath 8 locally expands from the unexpanded configuration to the expanded configuration at a location proximate the medical device in response to the outwardly directed radial force of the medical device exerted against the inner layer / central lumen 212 of the sheath 8. In some examples, the sheath 8 corresponds to the layered sheath 8 structure described in reference to FIGS. 11-23. The sheath 8 includes an inner layer and / or outer layer, and a folded portion, for example, ridges 126 and valleys 128 of the fourth (outer) layer 108 (FIGS. 11-14), and folded portion 218 of the inner layer 202 (FIGS. 15-23). Locally expanding the lumen of the layered sheath 8 causes a length of the folded portion to at least partially unfold. Similarly, locally contracting the sheath 8 at least partially back to the unexpanded configuration causes a length of the folded portion to urge backto a folded configuration. For example, in reference to the sheath 8 of FIGS. 15-23, the outer layer is a discontinuous outer layer and includes an overlapping portion (for example, overlapping portion 220) and an underlying portion (for example, underlying portion 222). With the sheath 8 in the unexpanded configuration, the folded portion 218 is disposed between the overlapping portion 220 overlaps the underlying portion 222 (FIG. 19). As the sheath 8 locally expands to the expanded configuration, a length of the overlapping portion 220 moves circumferentially with respect to the underlying portion 220, at least partially unfolding the folded portion 218. As illustrated in FIG. 20, when the layered sheath is fully expanded, the inner layer 202 extends into the gap 232 formed between the longitudinal edges of the overlapping portion 220 and the underlying portion 222 of the outer layer 204.

[0210] As the medical device passes through the lumen of the sheath 8 / strain relief layer 26, the sheath 8 / strain relief layer 26 locally contracts at least partially back to the unexpanded configuration when the medical device has passed. When used to deliver a medical device within a patient, the medical device is then passed through the distal opening of the sheath 8 and delivered to the treatment site. The position of the medical device can be moved or adjusted until the medical device is adequately positioned within the patient.

[0211] With the medical device delivered to the treatment site, any delivery apparatus / components coupled to the medical device are then removed from the medical device and withdrawn from / through the central lumen 212 of the sheath 8. In some examples, withdrawing the medical device from the central lumen 212 of the sheath 8 further includes locally contracting the sheath 8 at least partially back to the unexpanded configuration as the medical device passes through the central lumen 212, for example, by the radially inward force of an elastic outer layer 250 / outer jacket provided over the sheath 8.

[0212] The sheath 8 is then withdrawn from the patient’s blood vessel and the opening in the blood vessel and skin closed.

[0213] In some examples, the sheath 8 includes an elastic outer layer 250 that extends at least partially over the outer layer and / or the strain relief layer 26. The elastic outer layer 250 locally expands and contracts as the medical device is advanced through the lumen of the sheath 8. In some examples, the elastic outer layer 250 urges the various layers of the sheath 8 to an unexpanded configuration.

[0214] The medical device described herein can include a prosthetic device mounted in a radially crimped state on a delivery apparatus, and the act of advancing the prosthetic device through the lumen of the sheath 8 comprises advancing the delivery apparatus and the prosthetic device through lumen of the sheath 8 and into the vasculature of the patient. In some examples, the prosthetic device comprises a prosthetic heart valve and the method further comprises implanting the prosthetic heart valve at a treatment site within the patient. In some examples, the prosthetic heart valve is mounted on a balloon catheter of the delivery apparatus as the prosthetic heart valve is advanced through the sheath 8. In some examples, the sheath 8 is inserted into a femoral artery of the patient.

[0215] In view of the many possible examples to which the principles of the disclosed disclosure can be applied, it should be recognized that the illustrated examples are only preferred examples of the disclosure and should not be taken as limiting the scope of the disclosure. Rather, the scope of the disclosure is defined by the following claims. We, therefore, claim as our disclosure all that comes within the scope and spirit of these claims.

[0216] EXEMPLARY ASPECTS

[0217] Example 1. An expandable sheath system comprising: an expandable sheath comprising: a first layer including a proximal region, a distal region, and at least partially defining a central lumen extending axially therethrough; and a second layer radially outward of the first layer, the second layer including a proximal region and a distal region, the distal region of the second layer being coupled to the distal region of the first layer, wherein the second layer is movable relative to the first layer, wherein the expandable sheath system is movable between a neutral configuration, in which a diameter of the central lumen at the distal region of the first layer is substantially the same as a diameter of the central lumen at the proximal region of the first layer, and an expanded configuration, in which the diameter of the central lumen at the distal region of the first layer is radially expanded relative to the diameter of the central lumen at the proximal region of the first layer.

[0218] Example 2. The expandable sheath system according to any example herein, particularly example 1, wherein moving the second layer proximally relative to the first layer or the first layer distally relative to the second layer moves the expandable sheath system toward the expanded configuration.

[0219] Example 3. The expandable sheath system according to any example herein, particularly examples 1-2, wherein the expandable sheath system is further movable between the neutral configuration and a contracted configuration, in which the diameter of the central lumen at the distal region of the first layer is radially reduced relative to the diameter of the central lumen at the proximal region of the first layer.

[0220] Example 4. The expandable sheath system according to any example herein, particularly examples 1-3, wherein moving the second layer distally relative to the first layer or the first layer proximally relative to the second layer moves the expandable sheath system toward the contracted configuration.

[0221] Example 5. The expandable sheath system according to any example herein, particularly examples 1-4, wherein in the expanded configuration, the diameter of the central lumen flares smoothly outward toward the distal region of the first layer.

[0222] Example 6. The expandable sheath system according to any example herein, particularly examples 1-5, wherein the first layer and the second layer are formed from a continuous material folded onto itself.

[0223] Example 7. The expandable sheath system according to any example herein, particularly examples 1-6, wherein the first layer and the second layer comprise a braid.

[0224] Example 8. The expandable sheath system according to any example herein, particularly example 7, wherein the first layer and the second layer are braided only at their respective distal regions.

[0225] Example 9. The expandable sheath system according to any example herein, particularly examples 7-8, wherein the braid comprises round wires.

[0226] Example 10. The expandable sheath system according to any example herein, particularly examples 7-9, wherein the braid comprises flat wires.

[0227] Example 11. The expandable sheath system according to any example herein, particularly examples 7-10, wherein the braid comprises nitinol.

[0228] Example 12. The expandable sheath system according to any example herein, particularly examples 1-11, wherein at least one of the first layer and second layer are heat set in the neutral configuration.

[0229] Example 13. The expandable sheath system according to any example herein, particularly examples 1-12, wherein a collar extends around a constrained portion of the firstlayer that is longitudinally offset from the distal region of the first layer, thereby resisting radial expansion of the first layer at the constrained portion.

[0230] Example 14. The expandable sheath system according to any example herein, particularly examples 1-13, wherein a constrained portion of the first layer is reflowed with a first hollow member, thereby resisting radial expansion of the first layer at the constrained portion.

[0231] Example 15. The expandable sheath system according to any example herein, particularly example 14, wherein moving the first hollow member distally moves the first layer distally relative to the second layer, thereby moving the expandable sheath system toward the expanded configuration.

[0232] Example 16. The expandable sheath system according to any example herein, particularly examples 14-15, wherein moving the first hollow member proximally moves the first layer proximally relative to the second layer, thereby moving the expandable sheath system toward the contracted configuration.

[0233] Example 17. The expandable sheath system according to any example herein, particularly examples 14-16, wherein a portion of the second layer is reflowed with a second hollow member.

[0234] Example 18. The expandable sheath system according to any example herein, particularly example 17, wherein moving the second hollow member proximally moves the second layer proximally relative to the first layer, thereby moving the expandable sheath system toward the expanded configuration.

[0235] Example 19. The expandable sheath system according to any example herein, particularly examples 17-18, wherein moving the second hollow member distally moves the second layer distally relative to the first layer, thereby moving the expandable sheath system toward the contracted configuration.

[0236] Example 20. The expandable sheath system according to any example herein, particularly examples 1-19, wherein the expandable sheath system further comprises a pull-ring coupled to the second layer and pull-wires coupled to the pull-ring, wherein proximal tension on the pull- wires moves the second layer proximally relative to the first layer, thereby moving the expandable sheath system toward the expanded configuration.

[0237] Example 21 . The expandable sheath system according to any example herein, particularly example 20, wherein the second layer extends along only a portion of the first layer, wherein the pull-ring is coupled to the proximal end of the second layer.

[0238] Example 22. The expandable sheath system according to any example herein, particularly examples 20-21, wherein the first layer further defines a microlumen channel extending along a radially outward surface of the first layer, wherein the microlumen channel is sized and configured to facilitate passage of the pull-wires therethrough.

[0239] Example 23. The expandable sheath system according to any example herein, particularly examples 1-22, wherein the expandable sheath further comprises an outer layer radially outward of the second layer.

[0240] Example 24. The expandable sheath system according to any example herein, particularly example 23, wherein the outer layer is elastic.

[0241] Example 25. The expandable sheath system according to any example herein, particularly examples 23-24, wherein the outer layer is configured to urge the second layer toward the neutral configuration.

[0242] Example 26. The expandable sheath system according to any example herein, particularly examples 23-25, wherein the outer layer is disposed along a length of the second layer only at the distal region of the second layer.

[0243] Example 27. The expandable sheath system according to any example herein, particularly examples 23-26, wherein the outer layer comprises one or more of polyethylene, silicon, or polyurethane.

[0244] Example 28. An expandable sheath system for retrieving a medical device, the expandable sheath system comprising: an expandable sheath comprising: a first layer including a proximal region, a distal region, and at least partially defining a central lumen extending axially therethrough, wherein the first layer is heat set to be in an expanded configuration, in which a diameter of the central lumen at the distal region of the first layer is radially expanded relative to a diameter of the central lumen at the proximal region of the first layer; and a second layer radially outward of the first layer, the second layer including a proximal region and a distal region, wherein the first layer is movable relative to the second layer, wherein the expandable sheath system is movable between the expanded configuration and a neutral configuration, inwhich the diameter of the central lumen at the distal region of the first layer is substantially the same as the diameter of the central lumen at the proximal region of the first layer.

[0245] Example 29. The expandable sheath system of example 28, wherein the first layer comprises a braid.

[0246] Example 30. The expandable sheath system according to any example herein, particularly examples 28-29, wherein the first layer comprises a braid at only the distal region of the first layer.

[0247] Example 31. The expandable sheath system according to any example herein, particularly examples 28-30, wherein the second layer does not comprise a braid.

[0248] Example 32. The expandable sheath system according to any example herein, particularly examples 28-31, wherein moving the first layer distally relative to the second layer allows the distal region of the first layer to extend distally beyond the distal region of the second layer, thereby moving the expandable sheath system from the neutral configuration to the expanded configuration.

[0249] Example 33. The expandable sheath system according to any example herein, particularly examples 28-32, wherein a constrained portion of the first layer is reflowed with a first hollow member, thereby resisting radial expansion of the first layer at the constrained portion.

[0250] Example 34. The expandable sheath system according to any example herein, particularly example 33, wherein moving the first hollow member distally moves the first layer distally relative to the second layer, thereby moving the expandable sheath system toward the expanded configuration.

[0251] Example 35. The expandable sheath system according to any example herein, particularly examples 33-34, wherein moving the first hollow member proximally moves the first layer proximally relative to the second layer, thereby moving the expandable sheath system toward the neutral configuration.

[0252] Example 36. The expandable sheath system according to any example herein, particularly examples 28-35, wherein the expandable sheath system further comprises a pull-ring coupled to the first layer and pull-wires coupled to the pull-ring, wherein proximal tension on the pull- wires moves the first layer proximally relative to the second layer, thereby moving the expandable sheath system toward a contracted configuration, in which the diameter of the centrallumen at the distal region of the first layer is radially reduced relative to the diameter of the central lumen at the proximal region of the first layer, and wherein the expandable sheath further comprises an outer layer radially outward of the first layer, and wherein the outer layer comprises one or more of polyethylene, silicon, or polyurethane.

[0253] Example 37. A method of controlling expansion and contraction of an expandable sheath system, the method including: moving an expandable sheath from a neutral configuration toward an expanded configuration by moving a second layer of the expandable sheath proximally relative to a first layer of the expandable sheath, wherein in the neutral configuration, a diameter of a central lumen defined at a distal region of the first layer is substantially the same as a diameter of the central lumen at a proximal region of the first layer, and wherein in the expanded configuration, the diameter of the central lumen at the distal region of the first layer is radially expanded relative to the diameter of the central lumen at the proximal region of the first layer.

[0254] Example 38. The method according to any example herein, particularly example 37, further comprising moving the expandable sheath from the expanded configuration toward the neutral configuration by moving the second layer distally relative to the first layer.

[0255] Example 39. The method according to any example herein, particularly examples 37-38, further comprising moving the expandable sheath from the neutral configuration toward a contracted configuration by moving the second layer distally relative to the first layer, wherein in the contracted configuration, the distal region of the first layer is coupled to a distal region of the second layer, and the diameter of the central lumen at the distal region of the first layer is radially reduced relative to the diameter of the central lumen at the proximal region of the first layer.

[0256] Example 40. The method according to any example herein, particularly examples 37-39, wherein the step of moving the expandable sheath from a neutral configuration toward an expanded configuration further comprises applying proximal tension to pull- wires extending from a pull-ring coupled to the second layer of the expandable sheath.

[0257] Example 41. The method according to any example herein, particularly example 40, wherein applying proximal tension to pull-wires moves the pull-ring proximally relative to the first layer.

[0258] Example 42. The method according to any example herein, particularly examples 37-41 , wherein a constrained portion of the first layer is longitudinally offset from the distal region of the first layer and is configured to resist radial expansion of the first layer at the constrained portion.

[0259] Example 43. The method according to any example herein, particularly example 42, wherein the constrained portion of the first layer is reflowed with a first hollow member, thereby resisting radial expansion of the first layer at the constrained portion.

[0260] Example 44. The method according to any example herein, particularly examples 42-43, wherein the step of moving the expandable sheath from a neutral configuration toward an expanded configuration further comprises moving the first hollow member distally to move the first layer distally relative to the second layer.

[0261] Example 45. The method according to any example herein, particularly examples 42-44, wherein the step of moving the expandable sheath from the neutral configuration toward a contracted configuration further comprises moving the first hollow member proximally to move the first layer proximally relative to the second layer.

[0262] Example 46. The method according to any example herein, particularly examples 42-45, wherein a portion of the second layer is reflowed with a second hollow member.

[0263] Example 47. The method according to any example herein, particularly example 46, wherein the step of moving the expandable sheath from a neutral configuration toward an expanded configuration further comprises moving the second hollow member proximally to move the second layer proximally relative to the first layer.

[0264] Example 48. The method according to any example herein, particularly examples 46-47, wherein the step of moving the expandable sheath from the neutral configuration toward a contracted configuration further comprises moving the second hollow member distally to move the second layer distally relative to the first layer.

[0265] Example 49. The method according to any example herein, particularly examples 37-48, wherein the step of moving the expandable sheath from a neutral configuration toward an expanded configuration further comprises applying proximal tension to pull- wires extending from a pull-ring coupled to the second layer to move the second layer proximally relative to the first layer.

[0266] Example 50. A method of retrieving a medical device, the method including: positioning a distal tip of an expandable sheath adjacent a medical device, the distal tip comprising a first layer at least partially defining a central lumen extending therethrough and a second layer radially outward of the first layer, wherein a distal region of the first layer is coupled to a distal region of the second layer and a constrained portion of the first layer longitudinally offset from the distal region of the first layer is configured to resist radial expansion of the first layer at the constrained portion; moving the expandable sheath from a neutral configuration, in which a diameter of a central lumen defined at a distal region of the first layer is substantially the same as a diameter of the central lumen at a proximal region of the first layer, toward an expanded configuration, in which the diameter of the central lumen at the distal region of the first layer is radially expanded relative to the diameter of the central lumen at the proximal region of the first layer, by moving the second layer proximally relative to the first layer or the first layer distally relative to the second layer, wherein the diameter of the central lumen at the distal region of the first layer is at least the size of the medical device; and retracting the medical device into the central lumen of the expandable sheath.

Claims

CLAIMSWhat is claimed is:

1. An expandable sheath system comprising: an expandable sheath comprising: a first layer including a proximal region, a distal region, and at least partially defining a central lumen extending axially therethrough; and a second layer radially outward of the first layer, the second layer including a proximal region and a distal region, the distal region of the second layer being coupled to the distal region of the first layer, wherein the second layer is movable relative to the first layer, wherein the expandable sheath system is movable between a neutral configuration, in which a diameter of the central lumen at the distal region of the first layer is substantially the same as a diameter of the central lumen at the proximal region of the first layer, and an expanded configuration, in which the diameter of the central lumen at the distal region of the first layer is radially expanded relative to the diameter of the central lumen at the proximal region of the first layer.

2. The expandable sheath system of claim 1, wherein moving the second layer proximally relative to the first layer or the first layer distally relative to the second layer moves the expandable sheath system toward the expanded configuration.

3. The expandable sheath system of any of claims 1-2, wherein the expandable sheath system is further movable between the neutral configuration and a contracted configuration, in which the diameter of the central lumen at the distal region of the first layer is radially reduced relative to the diameter of the central lumen at the proximal region of the first layer.

4. The expandable sheath system of any of claims 1-3, wherein moving the second layer distally relative to the first layer or the first layer proximally relative to the second layer moves the expandable sheath system toward the contracted configuration.

5. The expandable sheath system of any of claims 1-4, wherein the first layer and the second layer arc formed from a continuous material folded onto itself.

6. The expandable sheath system of any of claims 1-5, wherein a collar extends around a constrained portion of the first layer that is longitudinally offset from the distal region of the first layer, thereby resisting radial expansion of the first layer at the constrained portion.

7. The expandable sheath system of any of claims 1-6, wherein a constrained portion of the first layer is reflowed with a first hollow member, thereby resisting radial expansion of the first layer at the constrained portion.

8. The expandable sheath system of claim 7, wherein moving the first hollow member distally moves the first layer distally relative to the second layer, thereby moving the expandable sheath system toward the expanded configuration, and wherein moving the first hollow member proximally moves the first layer proximally relative to the second layer, thereby moving the expandable sheath system toward the contracted configuration.

9. The expandable sheath system of any of claims 7-8, wherein a portion of the second layer is reflowed with a second hollow member, wherein moving the second hollow member proximally moves the second layer proximally relative to the first layer, thereby moving the expandable sheath system toward the expanded configuration, and wherein moving the second hollow member distally moves the second layer distally relative to the first layer, thereby moving the expandable sheath system toward the contracted configuration.

10. The expandable sheath system of any of claims 1-9, wherein the expandable sheath further comprises an outer layer radially outward of the second layer.

11. The expandable sheath system of claim 10, wherein the outer layer is elastic, andwherein the outer layer is configured to urge the second layer toward the neutral configuration.

12. The expandable sheath system of any of claims 10-11, wherein the outer layer is disposed along a length of the second layer only at the distal region of the second layer.

13. A method of controlling expansion and contraction of an expandable sheath system, the method including; moving an expandable sheath from a neutral configuration toward an expanded configuration by moving a second layer of the expandable sheath proximally relative to a first layer of the expandable sheath, wherein in the neutral configuration, a diameter of a central lumen defined at a distal region of the first layer is substantially the same as a diameter of the central lumen at a proximal region of the first layer, and wherein in the expanded configuration, the diameter of the central lumen at the distal region of the first layer is radially expanded relative to the diameter of the central lumen at the proximal region of the first layer.

14. The method of claim 13, further comprising; moving the expandable sheath from the expanded configuration toward the neutral configuration by moving the second layer distally relative to the first layer; and moving the expandable sheath from the neutral configuration toward a contracted configuration by moving the second layer distally relative to the first layer, wherein in the contracted configuration, the distal region of the first layer is coupled to a distal region of the second layer, and the diameter of the central lumen at the distal region of the first layer is radially reduced relative to the diameter of the central lumen at the proximal region of the first layer.

15. The method of any of claims 13-15, wherein a constrained portion of the first layer is longitudinally offset from the distal region of the first layer and is configured to resist radial expansion of the first layer at the constrained portion.

16. The method of claim 15, wherein the constrained portion of the first layer is reflowed with a first hollow member, thereby resisting radial expansion of the first layer at the constrained portion.

17. The method of any of claims 15-16, wherein moving the expandable sheath from a neutral configuration toward an expanded configuration further comprises moving the first hollow member distally to move the first layer distally relative to the second layer.

18. The method of any of claims 15-17, wherein moving the expandable sheath from the neutral configuration toward a contracted configuration further comprises moving the first hollow member proximally to move the first layer proximally relative to the second layer.

19. The method of any of claims 15-18, wherein a portion of the second layer is reflowed with a second hollow member, wherein moving the expandable sheath from a neutral configuration toward an expanded configuration further comprises moving the second hollow member proximally to move the second layer proximally relative to the first layer; and wherein moving the expandable sheath from the neutral configuration toward a contracted configuration further comprises moving the second hollow member distally to move the second layer distally relative to the first layer.

20. A method of retrieving a medical device, the method including: positioning a distal tip of an expandable sheath adjacent a medical device, the distal tip comprising a first layer at least partially defining a central lumen extending therethrough and a second layer radially outward of the first layer, wherein a distal region of the first layer is coupled to a distal region of the second layer and a constrained portion of the first layer longitudinally offset from the distal region of the first layer is configured to resist radial expansion of the first layer at the constrained portion; moving the expandable sheath from a neutral configuration, in which a diameter of a central lumen defined at a distal region of the first layer is substantially the same as a diameter ofthe central lumen at a proximal region of the first layer, toward an expanded configuration, in which the diameter of the central lumen at the distal region of the first layer is radially expanded relative to the diameter of the central lumen at the proximal region of the first layer, by moving the second layer proximally relative to the first layer or the first layer distally relative to the second layer, wherein the diameter of the central lumen at the distal region of the first layer is at least the size of the medical device; and retracting the medical device into the central lumen of the expandable sheath.

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