Multi-part in-sheath dilator

Abstract

A dilator (200) for expanding a lumen and methods of making and using the same are provided. The dilator includes a first shaft (202) and a second shaft (208) that are axially aligned for insertion into the lumen. The dilator includes a bump (234) extending circumferentially around a distal end of the first shaft and a proximal end of the second shaft. The bump comprises a leading end (236), a trailing end (238) opposite the leading end, and a central region (240) extending between the leading end and the trailing end, wherein the central region of the bump comprises a bump outer diameter greater than the outer diameters of the first shaft and second shaft for dilating the central lumen. Extension of the bump over the distal end of the first shaft and the proximal end of the second shaft forms a coupling.

Description

MULTI PART IN-SHEATH DILATORCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 690,747, filed September 4, 2024, which is incorporated by reference in its entirety for all purposes.TECHNICAL FIELD

[0002] The present application is directed to an expandable sheath and introducer 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 or a pump, 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 to reach target destinations rather than surgically opening a target site. There are many types of diseases or 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 that overall costs are lowered. In some cases, the need for anesthesia is also eliminated, further speeding up the recovery process and reducing risk.SUMMARY

[0005] Aspects of the present expandable sheath and dilator system can reduce trauma to the vessel and damage to the sheath and prosthetic device by reducing the push force through thevessel and the number of components and steps of the procedure. Some aspects avoid damage to the blood vessel during efforts to advance or dilate the expandable sheath. Additional aspects of the present expandable sheath can reduce trauma to the vessel by allowing for temporary expansion of a portion of the introducer sheath to accommodate a delivery apparatus, followed by a return to the original diameter once the delivery apparatus passes through. Some aspects can comprise a sheath with a smaller profile than that of prior art introducer sheaths. Furthermore, certain implementations 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 less push force is required and only one sheath is used, rather than several different sizes of sheaths.

[0006] An implementation of the present disclosure provides a dilator for expanding an expandable sheath, wherein the dilator includes a first shaft having a first rigidity, a second shaft having a second rigidity, and a bump extending around distal end of the first shaft and the proximal end of the second shaft. Advancing the dilator through a lumen of the expandable sheath causes the expandable sheath to stretch axially and / or radially.

[0007] In one of its configurations, the present disclosure provides a dilator for expanding a central lumen of a sheath. This configuration can be provided with any one or more of the features described elsewhere herein, in particular with those of the examples described hereafter. However, this somewhat basic configuration can also be provided with any one or more of the features shown in the figures and / or described in conjunction with the figures, either in addition to or alternatively to the features of the examples described hereafter.

[0008] In some examples, the dilator includes a first shaft, a second shaft, and a bump. In some examples, the first shaft includes a proximal end and a distal end and has a first outer diameter. In some examples, the second shaft includes a proximal end and a distal end and has a second outer diameter.

[0009] In some examples, the first shaft and second shaft are axially aligned for insertion into the lumen.

[0010] In some examples, the bump extends circumferentially around the distal end of the first shaft and the proximal end of the second shaft. In some examples, the bump includes a leading end, a trailing end opposite the leading end, and a central region extending between the leading end and the trailing end.

[0011] In some examples, the central region of the bump includes a bump outer diameter greater than the first and second outer diameters of the first shaft and second shaft, respectively, for dilating the lumen.

[0012] In some examples, extension of the bump over the distal end of the first shaft and the proximal end of the second shaft forms a coupling.

[0013] In one of its configurations, the present disclosure provides a dilator for expanding a central lumen of a sheath. The dilator can include: a first shaft comprising a first outer surface and including a proximal end and a distal end, the first shaft having a first outer diameter; a second shaft comprising a second outer surface including a proximal end and a distal end, the second shaft having a second outer diameter; and a bump extending circumferentially around the distal end of the first shaft and the proximal end of the second shaft, the bump comprising a leading end, a trailing end opposite the leading end, a central region extending between the leading end and the trailing end. In some examples, the bump optionally includes a projection extending radially inwardly. In some examples, at least one of the first and second shafts optionally defines a negative space, wherein the projection of the bump extends into the negative space to form a mechanical coupling fixing and aligning the first shaft and the second shaft along a common axis for insertion into the lumen.

[0014] In some examples, the techniques described herein relate to a method of making a dilator for expanding a central lumen of a sheath for passage of a medical device, the method optionally including: positioning a first shaft proximal a second shaft; aligning the first shaft and the second shaft along a common axis; abutting a distal end of the first shaft with a proximal end of the second shaft; heating a thermoplastic material and depositing the heated thermoplastic material into a bump extending around the distal end of the first shaft and the proximal end of the second shaft; and shaping the bump to have a tapered leading end and a tapered trailing end.

[0015] In some examples, the techniques described herein relate to a method of expanding a central lumen of a sheath for passage of a medical device, the method optionally including: positioning a first shaft proximal a second shaft; aligning the first shaft and the second shaft along a common axis; forming a bump around a proximal end of the first shaft and distal end of the first shaft, the bump comprising tapered leading and trailing ends, wherein the bump forms a coupling between the first and second shafts; aligning the coupled first and second shafts with an axis of a lumen; inserting the coupled first and second shafts into the lumen, wherein the bump exerts a radially outward force upon the lumen; and locally expanding the lumen from an initial condition and diameter to a locally expanded condition and expanded diameter by application of the radially outward force of the bump.

[0016] In one of its configurations, the present disclosure provides a dilator for expanding a central lumen of a sheath. The dilator can comprise a first shaft having a first rigidity and asecond shaft having a second rigidity, where the first shaft and second shaft are axially aligned. The dilator can also include a projection extending over at least a portion of the first shaft and at least a portion of the second shaft and circumferentially covering an outer surface of the dilator. A central region of the projection can have a diameter greater than outer diameters of the first shaft and the second shaft.

[0017] This configuration can be provided with any one or more of the features described elsewhere herein. This somewhat basic configuration can be provided with any one or more of the features shown in the figures and / or described in conjunction with the figures, either in addition to or alternatively to the features of the examples described hereafter.BRIEF DESCRIPTION OF DRAWINGS

[0018] FIG. 1 is a side view of an exemplary delivery apparatus for a cardiovascular prosthetic device.

[0019] FIG. 2 is a side view of an exemplary introducer device assembly.

[0020] FIG. 3 is a side view of an expandable sheath that can be used in combination with the introducer device assembly of FIG. 2.

[0021] FIG. 4 is a side cross-sectional view of a portion of the expandable sheath of FIG. 3.

[0022] FIG. 5 is a magnified side view of a portion of the expandable sheath of FIG. 3.

[0023] FIG. 6A is a magnified side view of a portion of the expandable sheath of FIG. 3 with the outer layer removed for purposes of illustration.

[0024] FIG. 6B is a magnified side view of a portion of the braided layer of the sheath of FIG. 3.

[0025] FIG. 7 is a magnified side view of a portion of the expandable sheath of FIG. 3 illustrating expansion of the sheath as a prosthetic device is advanced through the sheath.

[0026] FIG. 8 is an example dilator, the dilator including a first shaft, a second shaft, and a bump extending around the distal end of the first shaft and the proximal end of the second shaft.

[0027] FIG. 9 is a side cross-sectional view of the dilator of FIG. 8 taken along section line A-A.

[0028] FIG. 10 is a magnified side cross-sectional view of the dilator of FIG. 8 taken along A-A.

[0029] FIG. 11 is a magnified side cross-sectional view of a dilator, according to various examples.

[0030] FIG. 12 is a magnified side cross-sectional view of a dilator, according to various examples.

[0031] FIG. 13 is a flow chart of a method of making a dilator, according to some examples.

[0032] FIG. 14 is a flow chart of a method of expanding a central lumen of a sheath for the passage of a medical device, according to some examples.DETAILED DESCRIPTION

[0033] 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.

[0034] 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 aspects, 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.

[0035] 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 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 aspects. 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.

[0036] 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 materialincorporated herein by 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.

[0037] 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.

[0038] "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.

[0039] 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.

[0040] “Axially” or “axial” as used herein refers to a direction along the longitudinal axis of the sheath.

[0041] 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.

[0042] As previously described, the present disclosure relates to techniques and devices used in percutaneous interventional medical procedures. A single interventional 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 the access 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.

[0043] 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 or hub that contains one or more sealing valves that allow a delivery apparatus to be placed in fluid communication with the vasculature with reduced 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 or accommodating structure, allow for the dilating of the vessel to be performed by the passing prosthetic device.

[0044] One method to reduce push forces through the blood vessel and reduce vessel trauma is to provide a sheath and introducer with as minimum a diameter as possible or with a distal tapering end. However, very small diameter sheaths present challenges of strength and durability. For example, a very small diameter sheath may have lower push force through the vessel, but it may be more likely to tear or expand in a non-reversible manner during insertion into the patient’ s vasculature in response to the required push forces for sheath placement and / or after as the prosthetic valve is passed therethrough, which increases risk of trauma to the vessel.

[0045] Another method to reduce the push forces required to insert a delivery apparatus or medical device into the sheath is pre-dilating the sheath. Pre-dilating the sheath releases and / or loosens any bonding or adhesion of the sheath layers that occurs during the manufacturing process and can also break or separate weakened or folded portions of the sheath so that sheath layers are freely movable with respect to each other. However, this method requires significant physical strength of the user (i.e., grip and arm strength) to advance the dilator into the sheath.

[0046] Accordingly, there remains a need for improved systems and methods for delivering implants non-invasively through patient vasculature.

[0047] The expandable introducer sheaths and related componentry described herein can be used to deliver a prosthetic device through a patient’s vasculature to a procedure site within the body. The sheath can be constructed to be highly expandable and radially collapsible. Disclosed aspects of the expandable sheath can reduce trauma to the vessel by reducing push forces required to advance the sheath through the blood vessel, and / or reducing push forces required to advance the medical device and / or delivery apparatus through the sheath. In someimplementations, the expandable sheath can reduce 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 therethrough. In some examples, the sheath is advanced into the blood vessel in a radially collapsed / non- expanded configuration. For example, the sheath can releasably couple to an introducer to permit axial lengthening and radial compression of the sheath. In certain examples, the introducer has a coupling mechanism to releasably couple to the sheath in a natural / uncompressed configuration and maintain coupling between the sheath and the introducer as the sheath moves to the radially collapsed / compressed configuration. In some examples, an introducer coupled to a sheath applies axial force to the sheath in a distal direction, increasing the length of the sheath. In some examples, the application of axial force to the sheath in a distal direction also decreases the diameter of the sheath. In certain examples, the system includes an optional locking mechanism for coupling the sheath and introducer, fixing the axial and rotational movement of the introducer relative to the sheath in a collapsed / lengthened state. In some implementations, the sheath can be pre-dilated / at least partially expanded prior to delivery of the medical device / delivery apparatus. Pre-dilating and / or radially collapsing / lengthening the sheath can be done during sheath prep, prior to sheath insertion into the patient and / or with the sheath at least partially inserted into the patient. Various aspects of the sheath system structure provide for an expandable sheath / introducer that can be safely and predictably collapsed / contracted for advancement through the patient’s blood vessel and expands during medical device / delivery apparatus delivery. This reduces the length of time a procedure takes, as well as reduces the risk of a longitudinal or radial vessel tear, and damage to the expandable sheath.

[0048] Example expandable introducer sheaths are disclosed, for example, 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 deliverydevice 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, Two Component 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.

[0049] FIG. 1 illustrates an exemplary sheath 40 in use with a representative delivery apparatus 10, such as a prosthetic heart valve or other prosthetic implant, to a patient. The delivery apparatus 10 illustrated can generally include a steerable guide catheter 14 and a balloon catheter 16 extending through the guide catheter 14. A prosthetic device, such as a prosthetic heart valve (prosthetic device 12), can be positioned on the distal end of the balloon catheter 16. The guide catheter 14 and the balloon catheter 16 can be adapted to slide longitudinally relative to each other to facilitate delivery and positioning of a prosthetic heart valve (prosthetic device 12) at an implantation site in a patient's body. The sheath 40 is an elongated, expandable tube that can include a hemostasis valve at the proximal end of the sheath to stop blood leakage. The guide catheter 14 includes a handle portion 18 and an elongated guide tube or shaft extending from the handle portion 18.

[0050] The prosthetic heart valve (prosthetic device 12) can be delivered into a patient’s body in a radially compressed configuration and radially expanded to a radially expanded configuration at the desired deployment site. In the illustrated example, the prosthetic heart valve (prosthetic device 12) is a plastically expandable prosthetic valve that is delivered into the patient’s body in a radially compressed configuration on a balloon of the balloon catheter 16 (as shown in FIG. 1) and then radially expanded to a radially expanded configuration at the deployment site by inflating the balloon (or by actuating another type of expansion device of the delivery apparatus 10). Further details regarding a plastically expandable heart valvethat can be implanted using the devices disclosed herein are disclosed in U.S. Publication No. 2012 / 0123529, which is incorporated herein by reference. In some examples, the prosthetic heart valve (prosthetic device 12) can be a self-expandable heart valve that is restrained in a radially compressed configuration by a sheath or other component of the delivery apparatus 10 and self-expands to a radially expanded configuration when released by the sheath or other component of the delivery apparatus 10. Further details regarding a selfexpandable heart valve that can be implanted using the devices disclosed herein are disclosed in U.S. Publication No. 2012 / 0239142, which is incorporated herein by reference. In still some examples, the prosthetic heart valve (prosthetic device 12) can be a mechanically expandable heart valve that comprises a plurality of struts connected by hinges or pivot joints and is expandable from a radially compressed configuration to a radially expanded configuration by actuating an expansion mechanism that applies an expansion force to the prosthetic valve.

[0051] Further details regarding a mechanically expandable heart valve that can be implanted using the devices disclosed herein are disclosed in U.S. Publication No. 2018 / 0153689, which is incorporated herein by reference. In still some examples, a prosthetic valve can incorporate two or more of the above-described technologies. For example, a self-expandable heart valve can be used in combination with an expansion device to assist expansion of the prosthetic heart valve.

[0052] FIG. 2 illustrates an example of an introducer device assembly 20. The introducer device assembly 20 may include the sheath 40 and an introducer 100. The introducer 100 may be positioned within a central lumen 42 (indicated in FIG. 4) of the sheath 40, as shown in FIG. 2. An optional control housing 22 may be positioned at a proximal end of the introducer device assembly 20 and may include a sheath hub 24 and an introducer hub 30. The sheath hub 24 and introducer hub 30 may optionally couple together, as shown in FIG. 2.

[0053] The sheath 40 and introducer 100 are shown in an insertion configuration, for insertion together into the patient's vasculature. Upon insertion into the patient's vasculature, the introducer 100 may be withdrawn longitudinally from the sheath 40, leaving the sheath 40 within the patient's vasculature. Features of the sheath 40 and the introducer 100 individually are discussed below, as well as the operation of the sheath 40 and introducer 100 together.

[0054] The sheath 40 comprises an elongated body that may have a cylindrical shape. The sheath 40 has a distal end 43 and a proximal end 44, and a length LI (see FIG. 3) extending from the distal end 43 to the proximal end 44. The sheath 40 is configured to be inserted intoa patient's vasculature. The sheath 40 may optionally comprise an introducer sheath that is used to introduce a delivery apparatus 10 into the patient's vasculature.

[0055] The vasculature may comprise the blood vessels of the patient's body which may include the femoral artery or other vessels of the patient's body. The vasculature, such as the femoral artery, may be narrow or stiff, and may be difficult to easily insert a delivery apparatus 10 therein. For example, the delivery apparatus 10 may be larger than the vasculature or may be unwieldy to penetrate through the skin or vasculature of the patient to pass therethrough by itself. Also, the vasculature may be too fragile to receive the delivery apparatus 10 without use of an introducer sheath.

[0056] The sheath 40 accordingly may optionally be inserted into the patient’s vasculature prior to the delivery apparatus 10 being introduced, to provide an entryway or guide path for the delivery apparatus 10 to introduce the delivery apparatus 10 into the patient’s vasculature. After the sheath 40 is inserted, the sheath 40 may remain positioned within and surrounded by the patient’s vasculature. The delivery apparatus 10 may then be passed through the lumen of the sheath 40 for introduction into the patient’s body. The sheath 40 may remain in the vasculature until a desired time to remove the sheath 40.

[0057] The sheath 40 may be inserted into the vasculature percutaneously or a portion of the patient’s body may be surgically opened for the sheath 40 to access the vasculature. The delivery apparatus 10 passes through the lumen of the sheath 40 to reach a desired position in the patient’s body. As shown in FIG. 1, the delivery apparatus 10 may pass through an opening at the proximal end of the sheath 40 for passage through the central lumen 42 of the sheath 40 and the vasculature of the patient. For example, in some implementations, the delivery apparatus 10 passes through an opening at the proximal end of the sheath 40 provided at the control housing 22 shown in FIG. 2.

[0058] The delivery apparatus 10 and the assemblies disclosed herein may optionally be used in transcatheter aortic valve implantation (TAVI). The delivery apparatus 10 and the systems disclosed herein may optionally be utilized for transarterial access, including transfemoral access, to a patient’s heart.

[0059] The sheath 40 may optionally include a strain relief portion 46 at the proximal end 44 of the sheath 40. The strain relief portion 46 may be sized larger than a proximate portion of the sheath 40 and may seal the entry point of the vasculature, to reduce the possibility of blood or other fluid being released between the exterior surface of the sheath 40 and the vasculature. The strain relief portion 46 provides a transition between the larger diameter proximal opening of the sheath 40 and the smaller diameter distal portion / opening of thesheath 40 as the prosthetic device 12 and / or introducer 100 are inserted into the central lumen 42 of the sheath 40. In some examples, a seal 48 is optionally positioned along the length of the sheath 40 to further prevent blood or other fluid flow from passing around the sheath 40 toward and out of the proximal end 44 of the sheath 40.

[0060] FIG. 3 illustrates a side view of an exemplary expandable sheath 40 that can be used in the introducer device assembly of FIG. 2. As shown in FIG. 3, the sheath hub 24 is optionally positioned at the proximal end 44 of the sheath 40. The sheath hub 24 may optionally include an internal chamber for the delivery apparatus 10 to be passed through to be delivered to the patient's vasculature. The sheath hub 24 may be configured to remain external to the patient's vasculature when the sheath 40 is inserted therein and may be configured to remain external to the patient's skin for a percutaneous implantation of the sheath 40. The sheath hub 24 may be configured for a user (such as a surgeon) to grip to manipulate the sheath 40.

[0061] The sheath hub 24 may optionally comprise a cylindrical body and may include a coupler 29 for coupling to another housing or component of the system. The sheath hub 24 may optionally include a fluid port 26 for passing fluid such as blood to or from the patient's vasculature. Tubing 27 with a valve 28 may be coupled to the fluid port 26, for passing fluid through the fluid port 26 and for sealing flow of the fluid through the fluid port 26.

[0062] In some examples, the introducer sheath need not include a sheath hub 24. For example, the sheath 40 can be an integral part of a component of the delivery apparatus 10, such as the guide catheter. For example, the sheath can extend from the handle portion 18 of the guide catheter. Additional examples of introducer devices and expandable sheaths can be found in U.S. Patent No. 11,273,062, which is incorporated by reference in its entirety.

[0063] Figs. 4 and 5 illustrate a cross-sectional view and a side view, respectively, of a portion of the expandable sheath 40. As shown in FIG. 5, the sheath 40 can have a natural, unexpanded outer diameter DI. In certain examples, the expandable sheath 40 may optionally include a plurality of co-axial layers extending along at least a portion of the length LI of the sheath (FIG. 3). For example, with reference to FIG. 4, the expandable sheath 40 can include a first layer / inner layer 52 (also referred to as an inner layer), a second layer / braided layer 54 disposed around and radially outward of the inner layer 52, a third layer / elastic layer 56 disposed around and radially outward of the braided layer 54, and a fourth layer / outer layer 58 (also referred to as an outer layer) disposed around and radially outward of the elastic layer 56. In the illustrated configuration, the inner layer 52 can define the central lumen 42 extending along a central axis Cl. In some examples, the sheath 40 may optionally includethe inner layer 52 without the outer layer 58, or the outer layer 58 without the inner layer 52, depending upon the particular characteristics desired.

[0064] Referring to FIG. 5, when the sheath 40 is in an unexpanded state, the inner layer 52 and / or the outer layer 58 can form longitudinally-extending folds or creases such that the surface of the sheath comprises a plurality of ridges 62 (also referred to herein as “folds”). The ridges 62 can be circumferentially spaced apart from each other by longitudinally- extending valleys 64. When the sheath expands beyond its natural diameter DI, the ridges 62 and the valleys 64 can level out or be taken up as the surface radially expands and the circumference increases, as further described herein. When the sheath collapses back to its natural diameter, the ridges 62 and valleys 64 can reform.

[0065] In some examples, the inner layer 52 and / or the outer layer 58 can comprise a relatively thin layer of polymeric material. For example, in some examples, the thickness of the inner layer 52 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 certain aspects, the thickness of the outer layer 58 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.

[0066] In some examples, the inner layer 52 and / or the outer layer 58 can comprise a lubricious, low-friction, and / or relatively non-elastic material. In some examples, the inner layer 52 and / or the outer layer 58 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 52 in particular, such a low coefficient of friction materials can facilitate passage of the prosthetic device through the central lumen 42. Other suitable materials for the inner and outer layers can include polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), ethylene tetrafluoroethylene (ETFE), nylon, polyethylene, polyether block amide (for example, Pebax), and / or combinations of any of the above. Some examples of a sheath 40 can include a lubricious liner on the inner surface of the inner layer 52. Examples of suitable lubricious liners include materials that can further reduce the coefficient of friction of the inner layer 52, 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.

[0067] Additionally, some examples of the sheath 40 can include an optional exterior hydrophilic coating on the outer surface of the outer layer 58. Such a hydrophilic coating can facilitate insertion of the sheath 40 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 NV, Heerlen, the Netherlands), as well as other hydrophilic coatings (for example, PTFE, polyethylene, poly vinylidene fluoride), are also suitable for use with the sheath 40. Such hydrophilic coatings may also be optionally included on the inner surface of the inner layer 52 to reduce friction between the sheath and the delivery apparatus 10, thereby facilitating the use and improving safety. Tn some examples, a hydrophobic coating, such as Perylene, may be used on the outer surface of the outer layer 58 or the inner surface of the inner layer 52 in order to reduce friction.

[0068] In certain examples, the second layer / braided layer 54 can includes a braided material. Figs. 6 A and 6B illustrate the sheath 40 with the outer layer 58 removed to expose the elastic layer 56. With reference to Figs. 6A and 6B, the braided layer 54 can comprise a plurality of members or filaments 60 (for example, metallic or synthetic wires or fibers) braided together. The braided layer 54 can have any desired number of filaments 60, which can be oriented and braided together along any suitable number of axes. For example, with reference to FIG. 6B, the filaments 60 can include a first set of filaments 60A oriented parallel to a first axis A, and a second set of filaments 60B oriented parallel to a second axis B. The filaments 60 A and 60B can be braided together in a biaxial braid such that filaments 60A oriented along axis A form an angle 0 with the filaments 60B 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 60 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.

[0069] The braided layer 54 can extend along substantially the entire length LI of the sheath 40, or alternatively, can extend only along a portion of the length of the sheath. In particular examples, the filaments 60 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 60 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 60 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 example, filaments 60 having a flat crosssection can have dimensions of 0.1 mm x 0.2 mm. However, other geometries and sizes are also suitable for certain examples. If a 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 some examples, the braided layer 54 can be laser cut from a tube, or laser-cut, stamped, punched, etc., from sheet stock and rolled into a tubular configuration. The braided layer 54 can also be woven or knitted, as desired.

[0070] The third layer / elastic layer 56 can be a resilient, elastic layer (also referred to as an elastic material layer). In certain examples, the elastic layer 56 can be configured to apply force to the underlying inner layer 52 and braided layer 54 in a radial direction (for example, toward the central axis Cl of the sheath) when the sheath expands beyond its natural diameter by passage of the delivery apparatus lOthrough the sheath 40. Stated differently, the elastic layer 56 can be configured to apply encircling pressure to the layers of the sheath 40 beneath the elastic layer 56 to counteract expansion of the sheath. The radially inwardly directed force is sufficient to cause the sheath 40 to collapse radially back to its unexpanded state after the delivery apparatus 10 is passed through the sheath 40.

[0071] In the illustrated example, the elastic layer 56 can optionally comprise one or more members configured as strands, ribbons, or bands 66 helically wrapped around the braided layer 54. For example, in the illustrated sheath 40, the elastic layer 56 comprises two elastic bands 66A and 66B wrapped around the braided layer with opposite helicity, although the elastic layer 56 may comprise any number of bands depending upon the desired characteristics. The elastic bands 66A and 66B 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.

[0072] In some examples, the elastic layer 56 can comprise an elastomeric material having a modulus of elasticity of 200 MPa or less. In some examples, the elastic layer 56 can comprise a material exhibiting an elongation to break of 200% or greater, or an elongation to break of 400% or greater. The elastic layer 56 can also take other forms, such as a tubular layer comprising an elastomeric material, a mesh, a shrinkable polymer layer such as a heat-shrink tubing layer, etc. In lieu of, or in addition to, the elastic layer 56, the sheath 40 may also include an optional elastomeric or heat-shrink tubing layer around the outer layer 58. Examples of such elastomeric layers are disclosed in U.S. Patent Nos. 9,301,841, 10,792,471, and 10,856,981, which are incorporated herein by reference. In some examples, the elastic layer 56 can also be radially outward of the polymeric outer layer 58.

[0073] In some examples, one or both of the inner layer 52 and / or the outer layer 58 can be configured to resist axial shortening of the sheath 40 when the sheath expands radially. More particularly, one or both of the inner layer 52 and / or the outer layer 58 can resist stretching against longitudinal forces caused by friction between a prosthetic device and the inner surface of the sheath such that the length LI remains substantially constant as the sheath expands and contracts radially. As used herein with reference to the length LI of the sheath, the term “substantially constant” means that the length LI 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. 6B, the filaments 60 A and 60B of the braided layer 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 62 (folds) in the inner layer 52 and outer layer 58, can allow the central lumen 42 to expand as a prosthetic device is advanced through it.

[0074] In some examples, the inner layer 52 and the outer layer 58 can be heat-bonded during the manufacturing process such that the braided layer 54 and the elastic layer 56 are encapsulated between the inner layer 52 and the outer layer 58. More specifically, in certain examples, the inner layer 52 and the outer layer 58 can be adhered to each other through the spaces between the filaments 60 of the braided layer 54 and / or the spaces between the elastic bands 66. The inner layer 52 and outer layer 58 can also be bonded or adhered together at the proximal end 44 and / or distal end 43 of the sheath 40. In certain examples, the inner layer 52 and outer layer 58 are not adhered to the filaments 60. This can allow the filaments 60 to move angularly relative to each other, and relative to the inner layer 52 and outer layer 58, allowing the diameter of the braided layer 54, and thereby the diameter of the sheath, to increase or decrease. As the angle 0 between the filaments 60A and 60B changes, the length of the braided layer 54 can also change. For example, as the angle 0 increases, the braided layer 54 can foreshorten, and as the angle 0 decreases, the braided layer 54 can lengthen to the extent permitted by the areas where the inner layer 52 and outer layer 58 are bonded.However, because the braided layer 54 is not adhered to the inner layer 52 and outer layer 58, the change in length of the braided layer that accompanies a change in the angle 0 between the filaments 60A and 60B does not result in a significant change in the length LI of the sheath.

[0075] FIG. 7 illustrates radial expansion of the sheath 40 as a prosthetic device 12 is passed through the sheath 40 in the direction of arrow 82 (for example, distally). As the prosthetic device 12 is advanced through the sheath 40, the sheath 40 can resiliently expand to a seconddiameter D2 that corresponds to a size or diameter of the prosthetic device 12. As the prosthetic device 12 is advanced through the sheath 40, the prosthetic device 12 can apply longitudinal force to the sheath 40 in the direction of motion by virtue of the frictional contact between the prosthetic device 12 and the inner surface of the sheath 40. However, as noted above, the inner layer 52 and / or the outer layer 58 can be optionally configured to resist axial elongation such that the length LI of the sheath 40 remains constant, or substantially constant. This can reduce or prevent the braided layer 54 from lengthening, and thereby constricting the central lumen 42.

[0076] Meanwhile, in some examples, the angle 0 between the filaments 60 A and 60B can increase as the sheath 40 expands to the second diameter D2 to accommodate the prosthetic device 12. This can cause the braided layer 54 to foreshorten. However, because the filaments 60 are not engaged or adhered to the inner layer 52 or outer layer 58, the shortening of the braided layer 54 attendant to an increase in the angle 0 does not affect the overall length LI of the sheath. Moreover, because of the longitudinally-extending ridges 62 / folds formed in the inner layer 52 and outer layer 58, the inner layer 52 and outer layer 58 can expand to the second diameter D2 without rupturing, in spite of being relatively thin and relatively nonelastic. In this manner, the sheath 40 can resiliently expand from its natural diameter DI to a second diameter D2 that is larger than the diameter DI as a prosthetic device 12 is advanced through the sheath 40, without lengthening, and without constricting. Thus, the force required to push the prosthetic device 12 through the sheath 40 is significantly reduced.

[0077] Additionally, because of the radial force applied by the elastic layer 56, the radial expansion of the sheath 40 can be localized to the specific portion of the sheath 40 occupied by the prosthetic device 12. For example, with reference to FIG. 7, as the prosthetic device 12 moves distally through the sheath 40, the portion of the sheath 40 immediately proximal to the prosthetic device 12 can radially collapse back to the initial diameter DI under the influence of the elastic layer 56. The inner layer 52 and outer layer 58 can also buckle as the circumference of the sheath 40 is reduced, causing the ridges 62 and the valleys 64 to reform. This can reduce the size of the sheath 40 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 40 is inserted, along with the surrounding tissue, because only the portion of the sheath 40 occupied by the prosthetic device 12 expands beyond the sheath’s natural diameter and the sheath 40 collapses back to the initial diameter once the device has passed. This limits the amount of tissue stretched in order to introduce theprosthetic device 12, and the amount of time for which a given portion of the vessel is dilated to allow the prosthetic device 12 to pass.

[0078] In addition to the advantages above, the expandable sheath 40 examples described herein can provide surprisingly superior performance relative to known introducer sheaths. For example, it is possible to use a sheath 40 configured as described herein to deliver a prosthetic device having a diameter that is two times larger, 2.5 times larger, or even three times larger than the natural outer diameter of the sheath 40. For instance, in one example, a crimped prosthetic heart valve having a diameter of 7.2 mm was successfully advanced through a sheath configured as described above and having a natural outer diameter of 3.7 mm. As the prosthetic valve was advanced through the sheath 40, the outer diameter of the portion of the sheath 40 occupied by the prosthetic valve increased to 8 mm. In some examples, it was possible to advance a prosthetic device having a diameter more than two times the outer diameter of the sheath 40 through the sheath 40, during which the outer diameter of the sheath 40 resiliently increased by 216%. In another example, a sheath 40 with an initial or natural outer diameter of 4.5 mm to 5.0 mm can be configured to expand to an outer diameter of 8 mm to 9 mm.

[0079] As provided above, various sheaths are described herein. In some instances, significant push forces are sometimes required to insert the prosthetic device 12 / delivery apparatus 10 through the central lumen of the sheath 40.

[0080] FIG. 8 illustrates an example dilator 200 that includes a first shaft 202 and a second shaft 208. As shown, a bump 234 extends around ends of the first shaft 202 and second shaft 208. In some examples, the bump 234 forms a coupling between the first shaft 202, the second shaft 208, and the bump 234. Advantageously, the bump 234 extends radially over the first shaft 202 and the second shaft 208, such that passing the bump 234 through the central lumen of the sheath 40 conditions the central lumen 42 of the sheath 40. As used herein, the term “conditioning” includes preparing the central lumen 42 for passage of medical device therethrough. In various examples, “conditioning” the central lumen 42 means expanding or pre-dilating the central lumen 42 of the sheath 40 prior to passage of a medical device, thereby reducing the push forces required to insert the medical device (such as prosthetic device 12 / delivery apparatus 10) therethrough. For example, the dilator 200 may be used to pre-dilate the central lumen 42 of the sheath 40 to ease passage of the prosthetic device 12 / delivery apparatus 10. Furthermore, the coupling formed between the first shaft 202 and second shaft 208 allows for separate manufacturing of the first shaft 202 and second shaft 208 such that the shafts may have different rigidities, where one shaft has a relativelyincreased rigidity to allow for pushability while the other shaft has a relatively reduced rigidity for atraumatic advancement of the dilator 200 through the sheath 40. As used herein, the term “pushability” refers to the capacity for a member to transmit force in response to a force applied to the member. For example, a shaft exhibits “pushability” when it receives an axially-directed push force and transmits that force in a direction parallel with the originating push force.

[0081] As shown in FIGS. 8 and 9, the dilator 200 includes a first shaft 202 that has a proximal end 204 and a distal end 206. In the example illustrated in FIG. 8, the first shaft 202 has a first outer diameter (ODi). As shown in FIG. 8, the first outer diameter (ODi) of the first shaft 202 is constant between the proximal end 204 and the distal end 206 of the first shaft 202. However, in further examples, the first outer diameter (ODi) may optionally include a first proximal outer diameter and a smaller first distal outer diameter such that the first shaft 202 tapers from the proximal end 204 toward the distal end 206. Additionally, as shown in FIG. 9, the first shaft 202 includes an optional a first shaft lumen 216 extending between the proximal end 204 and the distal end 206 along an axis “X”. In some examples, the first shaft lumen 216 can be used for insertion of a guidewire therethrough.

[0082] FIG. 10 shows an enlarged view of the example dilator 200 shown in FIG. 9 taken along section line A-A. Specifically, FIG. 10 shows a first circumferential wall 218 of the first shaft 202 having a first wall thickness defined between a first inner diameter (IDi) of the first shaft lumen 216 and the first outer diameter (ODi) of the first shaft 202. However, in examples that do not include a first shaft lumen 216, the first wall thickness of the first circumferential wall 218 corresponds to the first outer diameter (ODi) of the first shaft 202.

[0083] As will be described in more detail herein, the rigidity of the dilator 200 can be varied along its length. For example, in some implementations, the first shaft 202 and second shaft 208 may have different rigidities. This allows proximal regions of the dilator 200 to be rigid for receiving and transmitting a push force for advancement of the dilator 200 through the central lumen 42, while allowing distal regions of the dilator 200 to remain flexible for reducing the risk of vascular trauma incurred as the dilator 200 advances through the sheath and / or patient’ s vasculature.

[0084] In various examples, including the example shown in FIGS. 8 and 9, the first shaft 202 has a first rigidity. In some examples, the first rigidity may be a first buckling rigidity. As used herein, the terms rigidity and stiffness are used interchangeably. The first rigidity of the first shaft 202 may be controlled by varying the material composition of the first shaft 202 and / or by varying parameters such as the first outer diameter (ODi), first inner diameter(IDi), and first wall thickness of the first circumferential wall 218. In other words, the rigidity of the first shaft 202 may be controlled by combining structural and / or material characteristics along the length of the first shaft 202. For example, the first shaft 202 may be manufactured to include a first material having a relatively increased modulus of elasticity such that the first shaft 202 demonstrates a relatively increased stiffness. In further examples, the first outer diameter (ODi) or first wall thickness of the first circumferential wall 218 may be increased to provide relatively increased stiffness. In some examples, increasing the rigidity of the first shaft 202 allows the first shaft 202 to receive and transmit an axial force applied by a user when inserting the dilator 200 into the central lumen 42 of the sheath 40. In some examples, the first shaft 202 may optionally have a Shore D durometer ranging from 35D to 90D. In some examples, the first shaft 202 may optionally have a Shore D durometer ranging from 60D to 80D. In some examples, the first shaft 202 may optionally have a Shore D durometer ranging from 63D to 75D. Accordingly, the first shaft 202 provides longitudinal and radial stiffness when received within the sheath 40.

[0085] In the example illustrated in FIG. 11, the first shaft 202 has a first outer surface 224 sized and configured to be received within the sheath 40. As shown in FIG. 11 , the first shaft 202 defines a first negative space 228 extending radially inward from the first outer surface 224 for receiving material of the bump 234 that will assist in coupling the first shaft 202 to the bump 234, as further described herein. Specifically, the first negative space 228 is sized and configured to slow cooling of bump material introduced into the negative space 230, thereby improving coupling between the first shaft 202 and the bump 234. In the illustrated example, the first negative space 228 has 90° walls and forms an annular groove in the second shaft 208 that extends circumferentially about an entire circumference of the second shaft 208. However, in some examples, the first negative space 228 may optionally have walls that are curved or extend at angles other than 90°. In further examples, the first negative space 228 may optionally extend radially inward from only an annular portion of the second outer surface 226. In yet further examples, the first negative space 228 may be in the form of depressions or surface roughness defined on the second outer surface 226, so long as such features facilitate coupling with the bump 234 as provided herein.

[0086] Additionally, in the example illustrated in FIG. 9, the proximal end 204 of the first shaft 202 is directly coupled to a dilator hub 300. Specifically, the first shaft 202 is received within a recess 302 of the dilator hub 300 such that the proximal end 204 of the first shaft 202 is received within a seat 304 of the dilator hub 300. As shown, the proximal end 204 abuts the seat 304 so that the first shaft lumen 216 is in communication with a dilator hub lumen 306.Accordingly, the dilator hub lumen 306 permits the introduction of a component, for example a guide wire, into the first shaft lumen 216. However, in further examples, the first shaft 202 may optionally be indirectly coupled to the dilator hub 300. In still further examples, the dilator 200 need not be coupled to a dilator hub such as dilator hub 300 at all.

[0087] FIGS. 8 and 9 also show the dilator 200 including a second shaft 208. As shown, the second shaft 208 has a proximal end 210 and a distal end 212. In the example illustrated in FIG. 8, the second shaft 208 has a second outer diameter (OD2) that has a constant diameter for a short axial length and then tapers from a second proximal outer diameter (OD2’) near the proximal end 210 of the second shaft 208 to a smaller second distal outer diameter (OD2”) near the distal end 212 of the second shaft 208. In further examples, the second outer diameter (OD2) may optionally be constant between the proximal end 210 and a distal end 212 of the second shaft 208. In some examples, the distal end 212 optionally includes a contoured or rounded distal end surface to ease entry into the central lumen 42 of the sheath 40 and further reduce trauma and / or damage to the sheath 40 or vasculature during advancement. Additionally, as shown in FIG. 9, similar to the first shaft 202, the second shaft 208 includes an optional second shaft lumen 220 extending between the proximal end 210 and the distal end 212. In some examples, the second shaft lumen 220 can be used for insertion of a guidewire therethrough, providing a continuous dilator lumen 214 with the first shaft lumen 216.

[0088] FIG. 10 shows a second circumferential wall 222 of the second shaft 208. Specifically, FIG. 10 shows the second circumferential wall 222 of the second shaft 208 having a second wall thickness defined between a second inner diameter (ID2) of the second shaft lumen 220 and the second outer diameter (OD2) of the second shaft 208. However, in examples that do not include a second shaft lumen 220, the second wall thickness of the second circumferential wall 222 corresponds to the second outer diameter (OD2) of the second shaft 208.

[0089] In various examples, including the example shown in FIGS. 8 and 9, the second shaft 208 has a second rigidity. In some examples, the second rigidity may be a second buckling rigidity. As described in more detail herein, the first rigidity of the first shaft 202 can be the same as and / or vary from the second rigidity of the second shaft 208. The second rigidity of the second shaft 208 may be controlled by varying the material composition of the second shaft 208 and / or by varying parameters such as the second outer diameter (OD2, OD2’, OD2”), second inner diameter (ID2), and second wall thickness of the second circumferentialwall 222. In other words, the rigidity of the second shaft 208 may be controlled by combining structural and / or material characteristics along the length of the second shaft 208.

[0090] In some examples, the second shaft 208 may be manufactured to include a second material that is different from the first material. In such examples, the second material may have a relatively reduced modulus of elasticity compared to the first material such that the second shaft 208 demonstrates a relatively reduced stiffness compared to the first shaft 202. In further examples, the second outer diameter (OD2, OD2’, OD2”) or second wall thickness of the second circumferential wall 222 may be reduced to provide relatively reduced stiffness compared to the first shaft 202. In some examples, reducing the rigidity of the second shaft 208 relative to the first shaft 202 allows the second shaft 208 to more easily deflect away from the common axis “X’- as a user inserts the dilator 200 into the central lumen 42 of the sheath 40. In some examples, the first shaft 202 may optionally have a Shore D durometer ranging from 35D to 90D. In some examples, the second shaft 208 may optionally have a Shore D durometer ranging from 60D to 80D. In some examples, the second shaft 208 may optionally have a Shore D durometer ranging from 63D to 75D. Accordingly, the second shaft 208 is able to more easily deform when advanced through non-linear patient vasculature, thereby facilitating atraumatic advancement of the dilator 200.

[0091] In the example illustrated in FIG. 11, the second shaft 208 has a second outer surface 226 sized and configured to be received within the sheath 40. As shown in FIG. 11, the second shaft 208 defines a second negative space 230 extending radially inward from the second outer surface 226 for receiving material of the bump 234 that will assist in coupling the second shaft 208 to the bump 234, as further described herein. Specifically, the second negative space 230 is sized and configured to slow cooling of bump material introduced into the negative space 230, thereby improving coupling between the second shaft 208 and the bump 234. In the illustrated example, the second negative space 230 has 90° walls and forms an annular groove in the second shaft 208 that extends circumferentially about an entire circumference of the second shaft 208. However, in some examples, the second negative space 230 may optionally have walls that are curved or extend at angles other than 90°. In further examples, the second negative space 230 may optionally extend radially inward from only an annular portion of the second outer surface 226. In yet further examples, the second negative space 230 may be in the form of depressions or surface roughness defined on the second outer surface 226, so long as such features facilitate coupling with the bump 234 as provided herein.

[0092] Returning now to FIGS. 8 and 9, the bump 234 extends circumferentially around the distal end 206 of the first shaft 202 and the proximal end 210 of the second shaft 208. As shown, the bump 234 is an enlarged region, such as a radially expanded region of the dilator 200. In the illustrated examples, the bump 234 extends circumferentially around entire outer surfaces of the distal end 206 and proximal end 210 of the respective first shaft 202 and second shaft 208. However, in further examples, the bump 234 may extend around or along only portions of the distal end 206 and proximal end 210.

[0093] In the example illustrated in FIGS. 8-10, the bump 234 includes (based on a direction of insertion) a leading end 236, a trailing end 238 opposite the leading end 236, and a central region 240 extending between the leading end 236 and the trailing end 238. As shown in FIG. 10, the central region 240 includes the bump outer diameter (OD3) that is greater than both the outer diameter (ODi) of the first shaft 202 and the outer diameter (OD2) of the second shaft 208. In some examples, the bump outer diameter (OD3) may optionally be 18 F to 27 F. For instance, the bump outer diameter (OD3) may optionally be 20 F. In further examples, the first distal outer diameter of the first shaft 202 and the second proximal outer diameter (OD2’) of the second shaft 208 may optionally be 12 F. In still further examples, the bump outer diameter (OD3) may be determined according to the desired diameter of an expansion region of the central lumen 42 of the sheath 40 formed by passage of the bump 234. For example, the bump outer diameter (OD3) may be selected to correspond to the size of the medical or delivery apparatus that is to be advanced through the central lumen 42 of the sheath 40.

[0094] In the illustrated example, the leading end 236 tapers from the bump outer diameter (OD3) of the central region 240 to the second outer diameter (OD2) of the second shaft 208, and the trailing end 238 tapers from the bump outer diameter (OD3) of the central region 240 to the first outer diameter (ODi ) of the first shaft 202. In some examples, the leading end 236 of the bump 234 tapers from the bump outer diameter (OD3) to the second proximal outer diameter (OD2’) of the second shaft 208 and the trailing end 238 of the bump 234 tapers from the bump outer diameter (OD3) to the first distal outer diameter (ODi) of the first shaft 202. The angles at which the leading end 236 and trailing end 238 taper and the lengths of the leading end 236 and trailing end 238 may be adapted for a desired amount of push forces, as well as the onset and reduction of such forces during insertion and passage through the central lumen 42. For example, the leading end 236 may be tapered so as to form a shallow angle with the second shaft 208 so as to reduce push force while inserting the dilator 200 into the central lumen 42 of the sheath. For example, the angle formed by the taper of the leadingend 236 may optionally be 5° to 30°. For example, the angle formed by the taper of the leading end 236 may optionally be 10° to 20°. For example, the angle formed by the taper of the leading end 236 may optionally be 15°.

[0095] Turning now to FIG. 11, the bump 234 may optionally include a projection 242 that extends radially inward to facilitate coupling the bump 234 with the first shaft 202 and the second shaft 208 as described herein. Specifically, in the example shown in FIG. 11, the bump 234 includes a first projection 244 and a second projection 246. As shown, each of the first projection 244 and second projection 246 extend radially inward from an inner surface of the bump 234. In the illustrated example, the first projection 244 includes a first shoulder 248 that extends between first and second ends of the first projection 244, and the second projection 246 includes a second shoulder 250 that extends between first and second ends of the second projection 246. In the example shown, the first shoulder 248 and the second shoulder 250 each extend circumferentially about an entire circumference of the bump 234 to form an annular first shoulder 248 and annular second shoulder 250. In yet further examples, the first projection 244 and / or the second projection 246 may optionally be in the form of surface roughness or ridges that extend radially inward, so long as such features facilitate coupling with the first shaft 202 and second shaft 208 as provided herein.

[0096] As illustrated in FIG. 11, the projection 242 extends radially inward into the first negative space 228 and second negative space 230 to form a mechanical coupling between the first shaft 202, the second shaft 208, and the bump 234. Specifically, the first projection 244 extends into the first negative space 228 of the first shaft 202 and the second projection 246 extends into the second negative space 230 of the second shaft 208. In further examples, coupling between the first shaft 202, the second shaft 208, and the bump 234 may optionally be facilitated with chemical bonding, thermal bonding, welding, and / or adhesives. In the illustrated example, the walls of the first shoulder 248 engage with the walls of the first negative space 228 and the walls of the second shoulder 250 engage with the walls of the second negative space 230.

[0097] In the example illustrated in FIG. 11, the first shoulder 248 and second shoulder 250 have 90° walls. However, in further examples, the first shoulder 248 and / or second shoulder 250 may optionally extend radially inward from only a portion of the circumference of the bump 234. In further examples, the first shoulder 248 and / or second shoulder 250 may optionally be curved or extend at angles other than 90°. For example, the walls of the first shoulder 248 and second shoulder 250 may optionally be 45° to 90°. For instance, FIG. 12 shows an example dilator 200 including a distal wall of the first shoulder 248 and a proximalwall of the second shoulder 250 having an angle of approximately 45°. As shown, the first shoulder 248 and second shoulder 250 extend axially inward to form a dovetail shape where an axial length of the central region 240 increases toward the common axis “X’'. In the example illustrated in FIG. 12, the first negative space 228 of the first shaft 202 and the second negative space 230 of the second shaft 208 are formed at acute angles complementary to those of the intended first shoulder 248 and second shoulder 250. As shown in FIG. 12, the first negative space 228 defines an angled distal wall extending proximally at an angle of approximately 45°, and the second negative space 230 defines an angled proximal wall extending distally at an angle of approximately 45° and the second negative space 230. In some examples, the first negative space 228 may optionally define an angled proximal wall extending distally at an angle of approximately 45° so as to form a complementary first shoulder 248 of the first projection 244 that extends in an axially proximal direction. Similarly, in some examples, the second negative space 230 may optionally define an angled distal wall extending proximally at an angle of approximately 45° so as to form a complementary second shoulder 250 of the second projection 246 that extends in an axially distal direction. Furthermore, in some examples, both proximal and distal walls of the first shoulder 248 are formed at acute angles so as to form an “A”-shaped first shoulder 248. Additionally, in some examples both proximal and distal walls of the second shoulder 250 are formed at acute angles so as to form an “A”-shaped second shoulder 250. Forming the walls of the first shoulder 248 and second shoulder 250 at an angle less than 90° such that the first projection 244 and second projection 246 extend in an axially inward and / or outward directions in addition to a radially inward direction improves mechanical coupling by preventing radially outward withdrawal of the first projection 244 and second projection 246.

[0098] Advantageously, the mechanical coupling between the bump 234 and the first shaft 202 and between the bump 234 and the second shaft 208 facilitates securing of the first shaft 202 and second shaft 208 relative to one another. In the illustrated example, the mechanical coupling holds the distal end 206 of the first shaft 202 in an abutting relationship relative to the proximal end 210 of the second shaft 208. As shown in FIG. 11, the distal end 206 of the first shaft 202 abuts the proximal end 210 of the second shaft 208 within a portion of the dilator 200 over which the bump 234 extends, where the first shaft 202 and the second shaft 208 are aligned along the common axis “X”. Axial alignment of the first shaft 202 and second shaft 208 facilitates insertion of the dilator 200 into the central lumen 42 of the sheath 40.

[0099] Specifically, the first shaft 202 and the second shaft 208 abut within the central region 240 of the bump 234. As shown, the distal end 206 and proximal end 210 abut midway along a length of the central region 240. However, in further examples, the distal end 206 and proximal end 210 may optionally abut at a location offset from the midline of the central region 240 or in a region of the bump 234 corresponding to the leading end 236 or trailing end 238. In yet further examples, the distal end 206 of the first shaft 202 and the proximal end 210 of the second shaft 208 may not directly abut. Rather, the first shaft 202 and second shaft 208 may be spaced apart from one another but nonetheless mechanically coupled by the bump 234. In such examples, the bump 234 may optionally define a negative space between the distal end 206 of the first shaft 202 and the proximal end 210. In still further examples, the distal end 206 of the first shaft 202 and the proximal end 210 of the second shaft 208 may optionally be received within axially aligned negative spaces defined on opposite sides of the bump 234.

[0100] Additionally, axial alignment of the first shaft 202 and second shaft 208 also aligns the first shaft lumen 216 and the second shaft lumen 220, thereby forming a continuous dilator lumen 214 extending between the proximal end 204 of the first shaft 202 and the distal end 212 of the second shaft 208 along the common axis “X”. In some examples, the continuous dilator lumen 214 may be used to receive a guide wire therethrough. However, in further examples, the dilator 200 may be solid (in other words, the first shaft 202 and / or second shaft 208 may not define lumens therethrough).

[0101] Advantageously, coupling the first shaft 202 and the second shaft 208 with the bump 234 allows the first shaft 202 to be manufactured separately from the second shaft 208. Accordingly, the first shaft 202 may be manufactured to have a first rigidity and the second shaft may be manufactured to have a second rigidity that is different from the first rigidity. In some examples, a differential between the first and second rigidities allow the proximal end 204 of the first shaft 202 to be rigid for receiving and transmitting a push force for advancement of the dilator 200 through the central lumen 42, while the distal end 212 of the second shaft 208 remain flexible for reducing the risk of vascular trauma incurred as the dilator 200 advances through the sheath 40 and / or patient’s vasculature. In various examples, the second shaft rigidity may optionally be less than the first shaft rigidity. For example, the second buckling rigidity of the second shaft 208 may be less than the first buckling rigidity of the first shaft 202. In some examples, the second rigidity of the second shaft 208 may optionally be 2.5% to 50% less than the rigidity of the first rigidity of the first shaft 202. In some examples, the second rigidity of the second shaft 208 may optionally be 5% to 30% lessthan the rigidity of the first rigidity of the first shaft 202. In some examples, the second rigidity of the second shaft 208 may optionally be 10% to 20% less than the rigidity of the first rigidity of the first shaft 202. In some examples, the second rigidity of the second shaft 208 may optionally be approximately 15% less than the rigidity of the first rigidity of the first shaft 202.

[0102] As described above, in some examples, the differential in rigidities between the first shaft 202 and the second shaft 208 may at least partially be the result of differences in material selection between the first shaft 202 and the second shaft 208. In some examples, the first material of the first shaft 202 and / or second material of the second shaft 208 may optionally be selected from polymeric materials. Such materials offer the advantage of being easily tunable to various stiffnesses. For example, in some examples, the first shaft 202 and / or the second shaft 208 may optionally comprise polyethylene, such as LDPE and HDPE at various ratios. In some examples, the first shaft 202 and / or the second shaft 208 may optionally comprise poly acetate (nylon) and poly ether block amide at various ratios.

[0103] In further examples, the differential in rigidities between the first shaft 202 and the second shaft 208 may at least partially be the result of differences between the first wall thickness of the first circumferential wall 218 and the second wall thickness of the second circumferential wall 222. For example, the first wall thickness of the first circumferential wall 218 may optionally be greater than the second wall thickness of the second circumferential wall 222. In further examples, the second wall thickness of the second circumferential wall 222 may optionally taper from the proximal end 210 towards the distal end 212, resulting in a second shaft 208 that has a variable rigidity that decreases from the proximal end 210 toward the distal end 212 and is less than that of the first shaft 202. In still further examples, the first outer diameter (ODi) of the first shaft 202 may optionally be greater than the second outer diameter (OD2) of the second shaft 208 such that the first rigidity of the first shaft 202 is greater than the second rigidity of the second shaft 208. In yet further examples, the first inner diameter (IDi) of the first shaft lumen 216 may optionally be less than the second inner diameter (ID2) of the second shaft lumen 220, thereby resulting in a second shaft 208 that is less rigid than the first shaft 202.

[0104] Advantageously, the differential between the first and second rigidities allows the proximal end 204 of the first shaft 202 to be rigid enough to receive and transmit a push force for advancement of the dilator 200 through the central lumen 42, while the distal end 212 of the second shaft 208 remains flexible enough to permit atraumatic advancement of the dilator 200 through the patient’s vasculature.

[0105] As provided herein, the dilator 200 is sized and configured for insertion into a sheath (for example, sheath 40). In some examples, the assembled dilator 200 may optionally have a length a ranging from 25 cm to 100 cm. For example, in a sheath system used for femoral access, the length of the dilator 200 is approximately 45 cm.

[0106] Referring now to FIG. 13, a method 400 of making the dilator 200 for expanding a lumen of a sheath (for example, central lumen 42 of sheath 40) for passage of a medical device is shown, according to various examples. It should be appreciated that method 400 may generally be performed by a human actor; however, examples are contemplated herein where the method 400 is at least partially performed by an automated manufacturing system. It will be appreciated that certain steps of the method 400 may be optional and, in some examples, the method 400 may be implemented using less than all of the steps. It will also be appreciated that the order of steps shown in FIG. 13 is not intended to be limiting.

[0107] At step 402, the first shaft 202 is positioned proximate with respect to the second shaft 208 and the step 404, the first shaft 202 and the second shaft 208 are aligned along a common axis, such as the axis “X”. At step 406, the distal end 206 of the first shaft 202 and the proximal end 210 of the second shaft 208 are abutted. At step 408, a thermoplastic material (also described herein as the bump material) is heated such that it is flowable.

[0108] At step 410, the heated thermoplastic material is deposited into a region surrounding the distal end 206 of the first shaft 202 and the proximal end 210 of the second shaft 208 so as to form a bump 234 upon cooling. Advantageously, the heated bump material allows for chemical bonding between the heated thermoplastic material of bump 234 and the first material of the first shaft 202 and between the heated thermoplastic material of the bump 234 and the second material of the second shaft 208, thereby coupling of the bump 234 with the first shaft 202 and the second shaft 208.

[0109] In some examples, the step 410 of depositing the heated thermoplastic material around the distal end 206 of the first shaft 202 and the proximal end 210 of the second shaft 208 may optionally include flowing the heated thermoplastic material into the first negative space 228 of the first shaft 202 and the second negative space 230 of the second shaft 208. In some examples, the method 400 may optionally include cooling the heated thermoplastic material within the first negative space 228 to form the first projection 244 and cooling the heated thermoplastic material within the second negative space 230 to form the second projection 246, as shown in the example illustrated in FIG. 11.

[0110] As described in various examples herein, the bump 234 is tapered from the central region 240 toward the leading end 236 and from the central region 240 to toward the trailingend 238. Because of these tapers, heated bump material flowed into regions that will form the leading end 236 and trailing end 238 cools more quickly than the heated bump material flowed into the central region 240. Such rapid cooling of the thermoplastic material may interfere with the bonding between the thermoplastic material that will form the bump 234 and the first and second materials of the first shaft 202 and second shaft 208.

[0111] In addition to providing improved mechanical coupling between the first projection 244 and second projection 246 and the first shaft 202 and second shaft 208, the first negative space 228 and the second negative space 230 also act as reservoirs for the heated bump material to pool, thereby slowing the rate of cooling of the heated bump material in the leading end 236 and trailing end 238.

[0112] Advantageously, extending the cooling period of the heated bump material facilitates improved chemical bonding between the heated thermoplastic material of the first projection 244 and the first material of the first negative space 228 and between the heated thermoplastic material of the second projection 246 and the second material of the second negative space 230, thereby reinforcing the coupling of the bump 234 with the first shaft 202 and the second shaft 208.

[0113] At step 412, the bump 234 is shaped to have a tapered leading end 236 and a tapered trailing end 238. In some examples, the step 412 of shaping the bump 234 may optionally occur concurrently with step 410. For example, the step 410 of depositing the heated thermoplastic material around the distal end 206 of the first shaft 202 and the proximal end 210 of the second shaft 208 may optionally include flowing the heated thermoplastic material into a mold that defines the central region 240, the leading end 236, and the trailing end 238. In such examples, the tapered leading end 236 and the tapered trailing end 238 are formed as the heated thermoplastic material cools. However, in some examples, the leading end 236 and the trailing end 238 are shaped from the bump 234 after the bump 234 is cooled.

[0114] In various examples provided herein, the manufacturing process of overmolding may optionally be used to perform the step 410 of depositing the heated thermoplastic material around the distal end 206 of the first shaft 202 and the proximal end 210 of the second shaft 208 to form the bump 234. In further examples, overmolding may optionally be used to shape the leading end 236 and / or trailing end 238 according to the step 412.

[0115] In various examples provided herein, the manufacturing process of injection molding may optionally be used to perform the step 410 of depositing the heated thermoplastic material around the distal end 206 of the first shaft 202 and the proximal end 210 of the second shaft 208 to form the bump 234. In further examples, injection molding mayoptionally be used to shape the leading end 236 and / or trailing end 238 according to the step 412.

[0116] Referring now to FIG. 14, a method 500 of expanding a lumen of a sheath (for example, central lumen 42 of sheath 40) for passage of a medical device is shown, according to various examples. As provided herein, the bump 234 has a bump outer diameter (OD3) that is greater than an inner diameter of the central lumen 42 of the sheath 40. Accordingly, the bump 234 exerts a radially outward directed force on the central lumen 42 (for example, exerts a radially outward force on the inner layer 52 of the sheath 40) when the dilator 200 is advanced through the central lumen 42 of the sheath 40.

[0117] As described herein, pre-dilating the strain relief portion 46 or the sheath 40, or a portion thereof, with the dilator 200 can help to reduce push forces required to insert the medical device 12 / delivery apparatus 10 through the central lumen 42 of the sheath 40. For example, pre-dilating the sheath 40 releases and / or loosens any bonding or adhesion of the sheath 40 layers that occurs during the manufacturing process, e.g., bonding between the inner 52, the braided layer 54, the elastic layer 56, and / or the outer layer 58. With the sheath 40 layers able to move more freely with respect to the other, the prosthetic device 12 / delivery apparatus 10 is pushed through the central lumen 42 of sheath 40 at a reduced force. Such pre-dilation may be achieved by passing the dilator 200 into the central lumen 42 of sheath 40. This can be done during sheath 40 preparation, prior to sheath 40 insertion into the patient and / or with the sheath 40 at least partially inserted into the patient.

[0118] It should be appreciated that method 500 may generally be performed by a human actor; however, examples are contemplated herein where the method 500 is at least partially performed by an automated manufacturing system. It will be appreciated that certain steps of the method 500 may be optional and, in some examples, the method 500 may be implemented using less than all of the steps. It will also be appreciated that the order of steps shown in FIG. 14 is not intended to be limiting.

[0119] At step 502, the first shaft 202 is positioned proximate with respect to the second shaft 208 and the step 504, the first shaft 202 and the second shaft 208 are aligned along a common axis (for example, the axis “X”). At step 506, the bump 234 is formed around the distal end 206 of the first shaft 202 and the proximal end 210 of the second shaft 208. Specifically, the bump 234 tapers from the central region 240 to the leading end 236 and from the central region 240 to the trailing end 238. As provided herein, the bump 234 forms a coupling between the first shaft 202 and the second shaft 208. At step 508, the first shaft 202 and the second shaft 208 are aligned with the axis of the central lumen 42 (for example, the centralaxis Cl of the sheath 40). At step 510, the coupled first shaft 202 and second shaft 208 are inserted into the central lumen 42. At step 512, the central lumen 42 is locally expanded from an initial condition and diameter to a locally expanded condition and diameter by application of the radially outward force of the bump 234, which has a bump 234 outer diameter (OD3) greater than the inner diameter of the central lumen 42. In some examples, the bump 234 has a profile that approximates the profile of a medical device (for example, the prosthetic device 12). Accordingly, advancing the dilator 200 through the central lumen 42 pre-dilates the central lumen 42 of the sheath 40 such that the medical device can subsequently be advanced through central lumen 42 with reduced push force.

[0120] A method of using example sheaths 40 described herein to implant a medical device (for example, prosthetic device 12) into a patient is described. The introducer 100 and sheath 40 as described herein is provided. The distal end of the introducer 100 is inserted into the proximal end 44 of the sheath 40 and advanced into the central lumen 42 of the sheath 40 as shown in FIG.2. The introducer 100 is advanced within the central lumen 42 of the sheath 40 in a distal direction toward the distal end 43 of the sheath 40.

[0121] The sheath 40 and introducer 100 are at least partially inserted into the patient’s blood vessel and advanced to the treatment site. In some examples, the expandable sheath 40 is inserted into the femoral artery or other vessels of the patient’s body. The vasculature, such as the femoral artery, may be narrow or stiff, and may be difficult to easily insert a delivery apparatus 10 therein. For example, the delivery apparatus 10 may be larger than the vasculature, or may be unwieldy to penetrate through the skin or vasculature of the patient to pass therethrough by itself. Also, the vasculature may be too fragile to receive the delivery 10 apparatus without the use of an introducer sheath 40. In the second, collapsed / narrowed, configuration the combined sheath 40 and introducer 100, the push force needed to advance the sheath 40 / introducer 100 into and through the patient’s blood vessel is reduced helping to minimize trauma to the vessel.

[0122] In some examples, a guidewire is optionally positioned at the treatment site and the sheath 40 and introducer 100 are advanced over the guidewire.

[0123] Once the combined sheath 40 and introducer 100 are positioned at or proximate to the treatment site, the introducer 100 is then withdrawn in a proximal direction within the central lumen 42 of the sheath 40. The introducer 100 is then fully withdrawn from the central lumen 42 of the sheath 40, leaving the sheath 40 within the patient’s vasculature.

[0124] The dilator 200 as described herein is then provided for expanding the central lumen 42 of the sheath 40 for passage of the medical device therethrough. For example, in someimplementations as described herein, passing the dilator 200 through the central lumen 42 of the sheath 40 pre-dilates or expands a portion of the sheath 40 and / or blood vessel corresponding to the location of the dilator 200 and / or bump 234. Providing this initial expansion reduces the push force necessary to advance the medical device and / or delivery system through the sheath 40 and / or blood vessel.

[0125] The distal end 212 of the second shaft 208 of the dilator 200 is advanced at least partially within the central lumen 42 of the sheath 40. The first shaft 202 and second shaft 208 of the dilator 200 are sized and configured to be received (for example, slidably and or rotatably received) within the central lumen 42 of the sheath hub 24. The dilator 200 is further advanced within the sheath 40 until the dilator hub 300 is positioned adjacent the proximal end of the sheath hub 24. In some examples, the dilator hub 300 is coupled to the coupler 29 of the sheath hub 24.

[0126] The sheath 40 and / or strain relief portion 46 expand in response to an outwardly directed radial force exerted against the central lumen 42 of the sheath 40 by the bump 234 of the dilator 200. Because the bump outer diameter (OD3) is greater than the inner diameter of the sheath 40, movement of the bump 234 within the central lumen 42 of the sheath 40 causes the sheath 40 and / or the corresponding portion of the strain relief portion 46 to radially expand.

[0127] Once the desired length of the sheath 40 and / or strain relief portion 46 is expanded, the dilator 200 is withdrawn from the central lumen 42 of the sheath 40. In some examples, the 40 and / or strain relief portion 46 are radially biased in an inward direction such that withdrawing the dilator 200 from the sheath 40 causes the sheath 40 and / or strain relief portion 46 to at least partially (locally) contract back toward the unexpanded configuration.

[0128] With the dilator 200 withdrawn from the central lumen 42 of the sheath 40 a desired amount, the dilator 200 can be uncoupled from the sheath 40 / sheath hub 24.

[0129] While pre-dilating the sheath 40 using the dilator 200 is described as following positioning the sheath 40 at the treatment site, in some examples, the dilator 200 may be used to pre-dilate the sheath 40 prior to inserting the sheath 40 into the patient.

[0130] With the dilator 200 removed, the medical device is introduced into the proximal end of the central lumen 42 of the sheath 40. Because the sheath 40 and / or strain relief portion 46 have been pre-dilated / expanded, the push forces necessary to advance the medical device through the sheath 40 and / or strain relief portion 46 are reduced compared to a non-dilated sheath.

[0131] With the central lumen 42 of the sheath 40 clear, the medical device is then advanced into the central lumen 42 of the sheath 40. Accessing the treatment site may require creating an opening in the heart tissue (for example, foramen ovalis) of the patient. In some examples, a cutting instrument can be advanced through the sheath 40 to create an opening in the patient’s heart tissue.

[0132] The medical device, for example an implant, is advanced through the central lumen 42 of the sheath 40 and beyond the distal opening to the treatment site within the blood vessel and / or heart tissue. Tn some examples, the sheath 40 is sized and configured such that advancing the medical device through the sheath 40 causes the sheath 40 to locally expand from an unexpanded configuration at a first diameter to an expanded configuration at a second, larger, diameter in response to an outwardly directed radial force exerted on the central lumen by the medical device, and then locally contract at least partially back to the unexpanded configuration as the medical device moves within the central lumen 42. With the distal end of the sheath 40 positioned at the treatment site, the medical device is deployed beyond distal opening of the sheath 40 and delivered to the patient.

[0133] In some examples, the medical device / implant is a prosthetic device 12 (such as a prosthetic heart valve) mounted in a radially crimped state on a delivery apparatus 10, and advancing the prosthetic device 12 through the central lumen 42 of the sheath 40 includes advancing the delivery apparatus 10 and the prosthetic device 12 through central lumen 42 of the sheath 40 and into a vasculature of the patient. In some examples, the prosthetic device 12 comprises a prosthetic device 12 and the method further comprises implanting the prosthetic device 12 at a treatment site within the patient. In some examples, the prosthetic device 12 is mounted on a balloon catheter of the delivery apparatus 10 as the prosthetic device 12 is advanced through the sheath 40.

[0134] Exemplary Aspects

[0135] In view of the described processes and compositions, hereinbelow are described certain more particularly described aspects of the disclosures. These particularly recited aspects should not, however, be interpreted to have any limiting effect on any different claims containing different or more general teachings described herein, or that the “particular” aspects are somehow limited in some way other than the inherent meanings of the language and formulas literally used therein.

[0136] Example 1: A dilator for expanding a central lumen of a sheath for passage of a medical device, the dilator comprising: a first shaft including a proximal end and a distal end, the first shaft having a first outer diameter; a second shaft including a proximal end and adistal end, the second shaft having a second outer diameter, wherein the first shaft and second shaft are axially aligned to facilitate insertion into the central lumen; and a bump extending circumferentially around the distal end of the first shaft and the proximal end of the second shaft, the bump comprising a leading end, a trailing end opposite the leading end, and a central region extending between the leading end and the trailing end, wherein the central region of the bump comprises a bump outer diameter greater than the first and second outer diameters of the first shaft and second shaft, respectively, for dilating the central lumen, and wherein extension of the bump over the distal end of the first shaft and the proximal end of the second shaft forms a coupling.

[0137] Example 2: The dilator according to any example herein, particularly example 1, wherein the first shaft has a first rigidity, and the second shaft has a second rigidity less than the first rigidity.

[0138] Example 3: The dilator according to any example herein, particularly example 2, wherein the first shaft defines a first shaft lumen having a first inner diameter, the first shaft comprising a first circumferential wall having a first wall thickness defined between the first inner diameter and the first outer diameter; and wherein the second shaft defines a second shaft lumen having a second inner diameter, the second shaft comprising a second circumferential wall having a second wall thickness defined between the second inner diameter and the second outer diameter.

[0139] Example 4: The dilator according to any example herein, particularly examples 2-3, wherein the first outer diameter of the first shaft is greater than the second outer diameter of the second shaft.

[0140] Example 5: The dilator according to any example herein, particularly examples 2-4, wherein the first shaft comprises a first material, and the second shaft comprises a second material; wherein the first material has a first material rigidity, and the second material has a second material rigidity lesser than the first material rigidity for atraumatic advancement of the second shaft through the central lumen.

[0141] Example 6: The dilator according to any example herein, particularly examples 2-5, wherein the first shaft has a first buckling rigidity, and the second shaft has a second buckling rigidity, wherein the first buckling rigidity is greater than the second buckling rigidity for increased pushability of the dilator through the central lumen.

[0142] Example 7: The dilator according to any example herein, particularly examples 1-6, wherein the first outer diameter further comprises a first proximal outer diameter and a first distal outer diameter, and wherein the second outer diameter further comprises a secondproximal outer diameter and a second distal outer diameter; wherein the leading end of the bump tapers from the bump outer diameter to the second proximal outer diameter of the second shaft, and the trailing end of the bump tapers from the bump outer diameter to the first distal outer diameter of the first shaft.

[0143] Example 8: The dilator according to any example herein, particularly example 7, wherein the first distal outer diameter of the first shaft and the second proximal outer diameter of the second shaft are each 12 F.

[0144] Example 9: The dilator according to any example herein, particularly examples 1 -8, wherein the bump outer diameter is 20 F.

[0145] Example 10: The dilator according to any example herein, particularly examples 1-9, wherein the central lumen is defined within a medical sheath.

[0146] Example 11: A dilator for expanding a lumen of a sheath for passage of a medical device, the dilator comprising: a first shaft comprising a first outer surface and including a proximal end and a distal end, the first shaft having a first outer diameter; a second shaft comprising a second outer surface including a proximal end and a distal end, the second shaft having a second outer diameter; and a bump extending circumferentially around the distal end of the first shaft and the proximal end of the second shaft, the bump comprising a leading end, a trailing end opposite the leading end, a central region extending between the leading end and the trailing end, and a projection extending radially inwardly, wherein at least one of the first and second shafts defines a negative space, and wherein the projection of the bump extends into the negative space to form a mechanical coupling fixing and aligning the first shaft and the second shaft along a common axis for insertion into the central lumen.

[0147] Example 12: The dilator according to any example herein, particularly example 11, wherein the distal end of the first shaft abuts the proximal end of the second shaft.

[0148] Example 13: The dilator according to any example herein, particularly examples 11- 12, wherein the negative space comprises a first negative space and a second negative space.

[0149] Example 14: The dilator according to any example herein, particularly example 13, wherein the first negative space is defined by the first shaft and extends radially inward from the first outer surface, and the second negative space is defined by the second shaft and extends radially inward from the second outer surface.

[0150] Example 15: The dilator according to any example herein, particularly example 14, wherein the first negative space extends circumferentially about the first shaft, and the second negative space extends circumferentially about the second shaft.

[0151] Example 16: The dilator according to any example herein, particularly example 15, wherein the first negative space extends about an entire circumference of the first shaft to form an annular groove therein, and the second negative space extends about an entire circumference of the second shaft to form an annular groove therein.

[0152] Example 17: The dilator according to any example herein, particularly examples 15- 16, wherein the projection comprises a first projection and a second projection, each extending radially inward from the bump.

[0153] Example 18: The dilator according to any example herein, particularly example 17, wherein the first projection comprises a first shoulder extending between first and second ends of the first projection, and the second projection comprises a second shoulder extending between first and second ends of the second projection.

[0154] Example 19: The dilator according to any example herein, particularly example 18, wherein the first shoulder and the second shoulder each extend circumferentially about the bump.

[0155] Example 20: The dilator according to any example herein, particularly example 19, wherein the first shoulder and the second shoulder each extend about an entire circumference of the bump to form respective first and second annular shoulders.

[0156] Example 21: The dilator according to any example herein, particularly examples 11-20, wherein the negative space comprises a first negative space defined by and extending radially inward from the first shaft, and a second negative space defined by and extending radially inward from the second shaft, wherein the first shaft comprises a first material and the second shaft comprises a second material, wherein the projection comprises a first projection and a second projection, each extending radially inward from the bump and comprising a bump material, wherein the first and second projections are formed from heated bump material flowed into the first and second negative spaces, respectively, and wherein the first and second negative spaces are configured to slow cooling of the heated bump material, thereby improving chemical bonding between the bump and the first shaft and between the bump and the second shaft.

[0157] Example 22: The dilator according to any example herein, particularly examples 11-21, wherein the central region of the bump comprises a bump outer diameter greater than the first and second outer diameters of the first shaft and the second shaft, respectively, for dilating the central lumen.

[0158] Example 23: A method of making a dilator for expanding a lumen of a sheath for passage of a medical device, the method comprising: positioning a first shaft proximal asecond shaft; aligning the first shaft and the second shaft along a common axis; abutting a distal end of the first shaft with a proximal end of the second shaft; heating a thermoplastic material and depositing the heated thermoplastic material into a bump extending around the distal end of the first shaft and the proximal end of the second shaft; and shaping the bump to have a tapered leading end and a tapered trailing end.

[0159] Example 24: The method of making a dilator according to any example herein, particularly example 23, wherein the first shaft defines a first negative space, and the second shaft defines a second negative space, wherein depositing the thermoplastic material into a region extending around the distal end of the first shaft and the proximal end of the second shaft further comprises depositing the thermoplastic material into the first and second negative spaces.

[0160] Example 25: The method of making a dilator according to any example herein, particularly example 24, wherein depositing the heated thermoplastic material into the first negative space forms a first projection, and depositing the heated thermoplastic material into the second negative space forms a second projection, each projection extending radially inward from the bump.

[0161] Example 26: The method of making a dilator according to any example herein, particularly example 25, wherein the method further comprises cooling the first projection formed within the first negative space and cooling the second projection formed within the second negative space, thereby forming a mechanical coupling between the bump and each of the first and second shafts.

[0162] Example 27: The method of making a dilator according to any example herein, particularly example 26, wherein the thermoplastic material deposited into the first and second negative spaces cools at a rate relatively slower than the thermoplastic material deposited outside the first and second negative spaces, thereby facilitating chemical bonding between the thermoplastic material of the bump and the distal end of the first shaft and the proximal end of the second shaft.

[0163] Example 28: The method of making a dilator according to any example herein, particularly examples 23-27, wherein depositing the thermoplastic material into a bump extending around the distal end of the first shaft and the proximal end of the second shaft further comprises overmolding the thermoplastic material over the first and second shafts.

[0164] Example 29: The method of making a dilator according to any example herein, particularly examples 23-28, wherein depositing the thermoplastic material into a bump extending around the distal end of the first shaft and the proximal end of the second shaftfurther comprises injection molding the thermoplastic material over the first and second shafts.

[0165] Example 30: A method of expanding a lumen of a sheath for passage of a medical device, the method comprising: positioning a first shaft proximal a second shaft; aligning the first shaft and the second shaft along a common axis; forming a bump around a proximal end of the first shaft and distal end of the first shaft, the bump comprising tapered leading and trailing ends, wherein the bump forms a coupling between the first and second shafts; aligning the coupled first and second shafts with an axis of a central lumen; inserting the coupled first and second shafts into the central lumen, wherein the bump exerts a radially outward force upon the central lumen; and locally expanding the central lumen from an initial condition and diameter to a locally expanded condition and expanded diameter by application of the radially outward force of the bump.

[0166] Example 31: The method of expanding a lumen of a sheath for passage of a medical device according to any example herein, particularly example 30, wherein the central lumen is defined within an expandable medical sheath.

[0167] Example 32: The method of expanding a lumen of a sheath for passage of a medical device according to any example herein, particularly example 31, wherein the bump has a profile approximating that of a medical device.

[0168] Example 33: A dilator for expanding a lumen of a sheath, the dilator comprising: a first shaft having a first rigidity; a second shaft having a second rigidity, wherein the first shaft and second shaft are axially aligned; and a projection extending over at least a portion of the first shaft and at least a portion of the second shaft and circumferentially covering an outer surface of the dilator, wherein a central region of the projection has a diameter greater than outer diameters of the first shaft and second shaft.

[0169] In view of the many possible aspects to which the principles of the disclosed disclosure can be applied, it should be recognized that the illustrated aspects 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.

Claims

WHAT IS CLAIMED IS:

1. A dilator expanding a central lumen of a sheath, the dilator comprising: a first shaft including a proximal end and a distal end, the first shaft having a first outer diameter; a second shaft including a proximal end and a distal end, the second shaft having a second outer diameter, wherein the first shaft and second shaft are axially aligned for insertion into the central lumen; and a bump extending circumferentially around the distal end of the first shaft and the proximal end of the second shaft, the bump comprising a leading end, a trailing end opposite the leading end, and a central region extending between the leading end and the trailing end, wherein the central region of the bump comprises a bump outer diameter greater than the first and second outer diameters of the first shaft and second shaft, respectively, for dilating the central lumen, and wherein extension of the bump over the distal end of the first shaft and the proximal end of the second shaft forms a coupling.

2. The dilator of claim 1, wherein the first shaft has a first rigidity, and the second shaft has a second rigidity less than the first rigidity.

3. The dilator of claim 2, wherein the first shaft defines a first shaft lumen having a first inner diameter, the first shaft comprising a first circumferential wall having a first wall thickness defined between the first inner diameter and the first outer diameter; and wherein the second shaft defines a second shaft lumen having a second inner diameter, the second shaft comprising a second circumferential wall having a second wall thickness defined between the second inner diameter and the second outer diameter.

4. The dilator of any one of claims 2-3, wherein the first outer diameter of the first shaft is greater than the second outer diameter of the second shaft.

5. The dilator of any one of claims 2-4, wherein the first shaft comprises a first material, and the second shaft comprises a second material;wherein the first material has a first material rigidity, and the second material has a second material rigidity lesser than the first material rigidity for atraumatic advancement of the second shaft through the central lumen.

6. The dilator of any one of claims 2-5, wherein the first shaft has a first buckling rigidity, and the second shaft has a second buckling rigidity, wherein the first buckling rigidity is greater than the second buckling rigidity for increased pushability of the dilator through the central lumen.

7. The dilator of any one of claims 1-6, wherein the first outer diameter further comprises a first proximal outer diameter and a first distal outer diameter, and wherein the second outer diameter further comprises a second proximal outer diameter and a second distal outer diameter; wherein the leading end of the bump tapers from the bump outer diameter to the second proximal outer diameter of the second shaft, and the trailing end of the bump tapers from the bump outer diameter to the first distal outer diameter of the first shaft.

8. A dilator for expanding a lumen of a sheath, the dilator comprising: a first shaft comprising a first outer surface and including a proximal end and a distal end, the first shaft having a first outer diameter; a second shaft comprising a second outer surface including a proximal end and a distal end, the second shaft having a second outer diameter; and a bump extending circumferentially around the distal end of the first shaft and the proximal end of the second shaft, the bump comprising a leading end, a trailing end opposite the leading end, a central region extending between the leading end and the trailing end, and a projection extending radially inwardly, wherein at least one of the first and second shafts defines a negative space, and wherein the projection of the bump extends into the negative space to form a mechanical coupling fixing and aligning the first shaft and the second shaft along a common axis for insertion into the central lumen.

9. The dilator of claim 8, wherein the distal end of the first shaft abuts the proximal end of the second shaft.

10. The dilator of any one of claims 8-9, wherein the negative space comprises a first negative space and a second negative space.

11. The dilator of claim 10, wherein the first negative space is defined by the first shaft and extends radially inward from the first outer surface, and the second negative space is defined by the second shaft and extends radially inward from the second outer surface.

12. The dilator of claim 11 , wherein the first negative space extends circumferentially about the first shaft, and the second negative space extends circumferentially about the second shaft.

13. The dilator of claim 12, wherein the projection comprises a first projection and a second projection, each extending radially inward from the bump.

14. The dilator of claim 13, wherein the first projection comprises a first shoulder extending between first and second ends of the first projection, and the second projection comprises a second shoulder extending between first and second ends of the second projection, wherein the first shoulder and the second shoulder each extend circumferentially about the bump, wherein the first shoulder and the second shoulder each extend about an entire circumference of the bump to form respective first and second annular shoulders.

15. The dilator of any one of claims 8-14, wherein the negative space comprises a first negative space defined by and extending radially inward from the first shaft, and a second negative space defined by and extending radially inward from the second shaft, wherein the first shaft comprises a first material and the second shaft comprises a second material, wherein the projection comprises a first projection and a second projection, each extending radially inward from the bump and comprising a bump material, wherein the first and second projections are formed from heated bump material flowed into the first and second negative spaces, respectively, andwherein the first and second negative spaces are configured to slow cooling of the heated bump material, thereby improving chemical bonding between the bump and the first shaft and between the bump and the second shaft.

16. The dilator of any one of claims 8-15, wherein the central region of the bump comprises a bump outer diameter greater than the first and second outer diameters of the first shaft and the second shaft, respectively, for dilating the central lumen.

17. A method of making a dilator for expanding a lumen of a sheath, the method comprising: positioning a first shaft proximal a second shaft; aligning the first shaft and the second shaft along a common axis; abutting a distal end of the first shaft with a proximal end of the second shaft; heating a thermoplastic material and depositing the heated thermoplastic material into a bump extending around the distal end of the first shaft and the proximal end of the second shaft; and shaping the bump to have a tapered leading end and a tapered trailing end.

18. The method of claim 17, wherein the first shaft defines a first negative space, and the second shaft defines a second negative space, wherein depositing the thermoplastic material into a region extending around the distal end of the first shaft and the proximal end of the second shaft further comprises depositing the thermoplastic material into the first and second negative spaces.

19. The method of claim 18, wherein depositing the heated thermoplastic material into the first negative space forms a first projection, and depositing the heated thermoplastic material into the second negative space forms a second projection, each projection extending radially inward from the bump.

20. The method of claim 19, further comprising cooling the first projection formed within the first negative space and cooling the second projection formed within the second negative space, thereby forming a mechanical coupling between the bump and each of the first and second shafts,wherein the thermoplastic material deposited into the first and second negative spaces cools at a rate relatively slower than the thermoplastic material deposited outside the first and second negative spaces, thereby facilitating chemical bonding between the thermoplastic material of the bump and the distal end of the first shaft and the proximal end of the second shaft.

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