Expandable introducer sheath

Abstract

Various implementations include an expandable sheath (40) including an expansion element (150) that facilitates movement of the distal tip between an unexpanded and an expanded configuration. The system includes an expandable sheath for deploying a medical device comprising: a tubular layer having a distal tip (130) coaxial with the tubular wall portion and having a central lumen extending therethrough. The distal tip is movable between an unexpanded configuration in which the distal tip has a first outer diameter (D1) and an expanded configuration in which the distal tip has a second, larger, outer diameter due (D2) to an outwardly directed radial force exerted on the central lumen of the distal tip. The distal tip includes an expansion element to facilitate movement of the distal tip from the unexpanded configuration to the expanded configuration.

Description

EXPANDABLE INTRODUCER SHEATHRELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 609,639, filed December 13, 2023, entitled "EXPANDABLE INTRODUCER SHEATH," the contents of which are 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 to a heart via the patient's vasculature.BACKGROUND OF THE INVENTION

[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 overall costs are lowered. In some cases, the need for anesthesia is also eliminated, further speeding up the recovery process and reducing risk.

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

[0006] An introducer sheath can be used to safely introduce a delivery apparatus into a patient's vasculature (for example, the femoral artery). Introducer sheaths are conduits that seal onto the access site blood vessel to reduce bleeding and trauma to the vessel caused by catheters with rough edges. An introducer sheath generally has an elongated sleeve that is inserted into the vasculature and a housing that contains one or more sealing valves that allow a delivery apparatus to be placed in fluid communication with the vasculature with minimal blood loss. Once the introducer sheath is positioned within the vasculature, the shaft of the delivery apparatus is advanced through the sheath and into the vasculature, carrying the prosthetic device. Expandable introducer sheaths, formed of highly elastomeric materials, allow for the dilating of the vessel to be performed by the passing prosthetic device.

[0007] One method to reduce push forces required to advance the delivery device through the sheath is to pre-dilate the sheath by passing a relatively large dilator (for example, 22 French dilator) into the sheath. This is done during sheath prep, prior to sheath insertion into the patient and / or with the sheath at least partially inserted into the patient. The challenge with this method is that it can be difficult with regard to physical strength of the user (for example, grip and arm strength) to advance the dilator into sheath, possible trauma to the patient's blood vessel during sheath dilation, and possible damage to the sheath caused by the dilator. Additionally, it is important that the dilator pass all the way to the distal end of the sheath while also avoiding splitting of the sheath and / or distal end of the sheath, which could cause difficulty or vessel injury during the delivery device insertion / removal process.

[0008] Accordingly, there remains a need for devices, systems, and methods that allow the sheath body and distal tip to expand reducing the initial push force when introducing the delivery system and implant, while also preventing damage to the sheath and the patient's vasculature.SUMMARY OF THE INVENTION

[0009] Aspects of the present expandable sheath and introducer system can minimize trauma to the vessel and damage to the sheath and prosthetic device by reducing push forces through the sheath. Some aspects ensure that the sheath is not damaged during efforts to dilate or expand the distal end of the sheath. Additional aspects of the present expandable sheath can minimize trauma to the vessel by allowing for temporary expansion of a portion of the introducer sheath to accommodate a deliverysystem, followed by a return to the original diameter once the delivery system 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 lower push force is required and only one sheath is used, rather than several different sizes of sheaths.

[0010] An implementation of the present disclosure provides an expandable sheath for deploying a medical device including a distal tip that moves between an unexpanded configuration and an expanded configuration. The expandable sheath comprising: a tubular layer including: a tubular wall portion having a proximal end and a distal end, and defining a central lumen extending therethrough; and a distal tip provided at the distal end of the tubular wall portion coaxial with the tubular wall portion and having a central lumen extending therethrough; where the distal tip is movable between an unexpanded configuration in which the distal tip has a first outer diameter and an expanded configuration in which the distal tip has a second, larger, outer diameter due to an outwardly directed radial force exerted on the central lumen of the distal tip, and where the distal tip includes an expansion element to facilitate movement of the distal tip from the unexpanded configuration to the expanded configuration. In some implementations, the expansion element comprises at least one of a folded portion, cut, slit, weakened portion, score-line, perforation and / or thinned / recessed portion extending along the distal tip. In some implementations, the expansion element comprises a weakened portion that is configured to split or separate allowing the distal tip to expand radially toward the expanded configuration.

[0011] Another implementation of the present disclosure provides a method of delivering a medical device and expanding an introducer sheath comprising: providing the sheath comprising: a radially expandable cylindrical outer layer having a proximal end and a distal end, and defining a central lumen extending longitudinally between the proximal end and the distal end; and a distal tip provided at the distal end of the outer layer, the distal tip having a decreasing tapered outer surface providing a transition between the sheath and an introducer extending through the sheath and distal tip; where the distal tip is movable between an expanded configuration in which the distal tip has a first outer diameter and an unexpanded configuration in which the distal tip has a second, larger, outer diameter due to an outwardly directed radial force exerted on a central lumen of the distal tip; wherein the distal tip includes an expansion element configured to open and / or separate to facilitate movement of the distal tip from the unexpanded configuration to the expanded configuration; advancing the sheath, with the introducer provided therein, at least partially into a blood vessel of a patient; withdrawing the introducer from the central lumen of the sheath; advancing a dilator into the central lumen of thesheath; advancing the dilator through a central lumen of the distal tip causing the distal tip to move from the unexpanded configuration to the expanded configuration at a location proximate the dilator in response to an outwardly directed radial force of the dilator exerted against the central lumen of the distal tip; withdrawing the dilator from the central lumen of the sheath; advancing a medical device through the central lumen of the sheath; and advancing the medical device beyond a distal opening of the sheath to the treatment site. In some implementations, advancing the dilator through the central lumen of the distal tip causes the expansion element to open and / or separate as the distal tip moves to the expanded configuration.

[0012] A further implementation of the present disclosure provides an expandable sheath for deploying a medical device comprising: a tubular layer including: a tubular wall portion having a proximal end and a distal end, and defining a central lumen extending therethrough; and a distal tip provided at the distal end of the tubular wall portion coaxial with the tubular wall portion and having a central lumen extending therethrough; wherein the distal tip is movable between an unexpanded configuration in which the distal tip has a first outer diameter and an expanded configuration in which the distal tip has a second, larger, outer diameter due to an outwardly directed radial force exerted on the central lumen of the distal tip, where, in the unexpanded configuration, the distal tip has a diameter less than a diameter of the tubular wall portion, and where the distal tip includes a folded portion extending along a length of the distal tip, where moving the distal tip from the unexpanded configuration to the expanded configuration causes the folded portion to at least partially unfold.

[0013] Another implementation of the present disclosure provides a method of forming an expandable sheath including: providing a tubular layer including a tubular wall portion having a uniform outer diameter; forming a distal tip at a distal end of the tubular wall portion, where the distal tip has a diameter less than a diameter of the tubular wall portion; and folding at least a portion of the distal tip to include a folded portion extending along a length of the distal tip forming a tapered outer surface of the distal tip.

[0014] A further implementation of the present disclosure provides a method of delivering a medical device and expanding an introducer sheath comprising: providing the sheath including: a radially expandable cylindrical outer layer having a proximal end and a distal end, and defining a central lumen extending longitudinally between the proximal end and the distal end; and a distal tip provided at (mounted on / coupled to) the distal end of the outer layer, the distal tip having a transition between the sheath and an introducer extending through the sheath and distal tip; where the distal tip is movable between an expanded configuration in which the distal tip has a first outer diameter and an unexpandedconfiguration in which the distal tip has a second, larger, outer diameter due to an outwardly directed radial force exerted on a central lumen of the distal tip, where, in the unexpanded configuration, the distal tip has a diameter less than a diameter of the outer layer, the distal tip including a folded portion extending along a length of the distal tip, where moving the distal tip from the unexpanded configuration to the expanded configuration causes the folded portion to at least partially unfold. The method further comprises: advancing the sheath, with the introducer provided therein, at least partially into a blood vessel of a patient; withdrawing the introducer from the central lumen of the sheath; advancing a dilator into the central lumen of the sheath; advancing the dilator through a central lumen of the distal tip causing the distal tip to move from the unexpanded configuration to the expanded configuration at a location proximate the dilator in response to an outwardly directed radial force of the dilator exerted against the central lumen of the distal tip causing the folded portion to at least partially unfold; withdrawing the dilator from the central lumen of the sheath; advancing a medical device through the central lumen of the sheath; and advancing the medical device beyond a distal opening of the sheath to the treatment site.

[0015] Various aspects of the implementations described above can be combined based on desired sheath system characteristics.BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 illustrates an exemplary delivery apparatus for a cardiovascular prosthetic device.

[0017] Fig. 2 illustrates an exemplary introducer device assembly.

[0018] Fig. 3 illustrates a side view of an expandable sheath that can be used in combination with the introducer device assembly of Fig. 2.

[0019] Fig. 4 is a side cross-sectional view of a portion of the expandable sheath of Fig. 3.

[0020] Fig. 5 is a magnified view of a portion of the expandable sheath of Fig. 3.

[0021] Fig. 6A is a magnified view of a portion of the expandable sheath of Fig. 3 with the outer layer removed for purposes of illustration.

[0022] Fig. 6B is a magnified view of a portion of the braided layer of the sheath of Fig. 3.

[0023] Fig. 7 is a magnified 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.

[0024] Fig. 8 is a perspective view of an example sheath having a distal end portion folded around an introducer.

[0025] Fig. 9 is an enlarged cross-sectional view of the distal end portion folded around the introducer.

[0026] Fig. 10 is a perspective view of the distal end of the sheath in an expanded configuration.

[0027] Fig. 11 is a perspective view of the distal end of an example sheath including an expansion element in an unexpanded configuration.

[0028] Fig. 12 is a perspective view of the distal end of the example sheath of Fig. 11 in an expanded configuration.

[0029] Fig. 13 is a perspective view of the distal end of an example sheath including an opening expansion element in an expanded configuration.

[0030] Fig. 14 is a perspective view of the distal end of an example sheath including an opening expansion element in an expanded configuration.

[0031] Fig. 15 is a perspective view of the distal end of the example sheath of Fig. 13 and / or Fig. 14 in an unexpanded configuration.

[0032] Fig. 16 is a perspective view of the distal end of the example sheath of Fig. 13 and / or Fig. 14 in an unexpanded configuration.

[0033] Fig. 17 is a side view of an example sheath having a reduced diameter distal tip in an expanded configuration.

[0034] Fig. 18 is an end view of the example sheath of Fig. 17 in an unexpanded configuration.

[0035] Fig. 19 is a side view of an example sheath in an expanded configuration.

[0036] Fig. 20 is an end view of the example sheath of Fig. 19 in an unexpanded configuration.DETAILED DESCRIPTION OF THE INVENTION

[0037] 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.

[0038] 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 limitedto 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.

[0039] Features, integers, characteristics, compounds, chemical moieties, or groups described in conjunction with a particular aspect or example of the present disclosure are to be understood to be applicable to any other aspect or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract, and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The present disclosure is not restricted to the details of any foregoing 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.

[0040] It should be appreciated that any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated 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.

[0041] 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.

[0042] "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.

[0043] 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.

[0044] "Axially" or "axial" as used herein refers to a direction along the longitudinal axis of the sheath.

[0045] 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.

[0046] The expandable introducer sheaths described herein can be used to deliver a prosthetic device through a patient's vasculature to a procedure site within the body. Disclosed aspects of the expandable sheath can minimize trauma to the vessel by allowing for temporary expansion of a portion of the introducer sheath to accommodate the delivery system, followed by a return to the original diameter once the device passes through. To reduce push forces required to advance the delivery system through the sheath, the sheath can be pre-dilate / at least partially expanded prior to delivery of the medical device / delivery system. This 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. It is important that the dilator pass all the way to the distal end of the sheath while also avoiding splitting of the sheath and / or distal end of the sheath, which could cause difficulty or vessel injury during the delivery device insertion / removal process. Various aspects of the sheath structure, including the structure of the distal end portion of the sheath, described herein provide for an expandable sheath / distal end portion that can be safely and predictably dilatated in advance of medical device / delivery system 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.

[0047] 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 forintroducing an endovascular delivery device in to a body / ' Application No. PCT / US2021 / 031227, entitled "Expandable sheath for introducing an endovascular delivery device into a body / ' Application No. PCT / US2021 / 031275, entitled "Expandable sheath for introducing an endovascular delivery device into a body," U.S. Application No. 17 / 113,268, entitled "Expandable Sheath and Method of Using the Same," Application No. PCT / US2021 / 058247, entitled "Self-Expanding, 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.

[0048] 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 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 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.

[0049] The prosthetic heart valve 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 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). Further details regarding a plastically expandable heart valve that can be implantedusing 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 12 can be a selfexpandable heart valve that is restrained in a radially compressed configuration by a sheath or other component of the delivery apparatus and self-expands to a radially expanded configuration when released by the sheath or other component of the delivery apparatus. 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 some examples, the prosthetic heart valve 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. 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 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.

[0050] FIG. 2 illustrates an example of an introducer device assembly 20. The assembly 20 may include the sheath 40 and an introducer 100. The introducer 100 may be positioned within a sheath lumen 50 (indicated in Fig. 4) of the sheath 40, as shown in Fig. 2. A control housing 22 may be positioned at a proximal end of the assembly and may include a sheath hub 24 and an introducer hub 30. The sheath hub 24 and introducer hub 30 may couple together, as shown in Fig. 2.

[0051] 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.

[0052] The sheath 40 comprises an elongate body that may have a cylindrical shape. The sheath 40 has a sheath distal end 42 and a sheath proximal end 44, and a length LI (see Fig. 3) extending from the sheath distal end 42 to the sheath proximal end 44. The sheath 40 is configured to be inserted into a patient's vasculature. The sheath 40 may comprise an introducer sheath that is used to introduce a delivery apparatus into the patient's vasculature.

[0053] 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, maybe narrow or stiff, and may be difficult to easily insert a delivery apparatus therein. For example, the delivery apparatus 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 without use of an introducer sheath.

[0054] The sheath 40 accordingly may be inserted into the patient's vasculature prior to the delivery apparatus being introduced, to provide an entryway or guide path for the delivery apparatus 10 to introduce the delivery apparatus 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.

[0055] 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 (the control housing 22 is not shown in Fig. 1) for passage through the lumen of the sheath 40 and the vasculature of the patient.

[0056] The delivery apparatus and the assemblies disclosed herein may be used in transcatheter aortic valve implantation (TAVI). The delivery apparatus and the systems disclosed herein may be utilized for transarterial access, including transfemoral access, to a patient's heart.

[0057] The sheath 40 may include a strain relief portion 46 at the sheath proximal end 44. 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. A seal 48 may be 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 sheath proximal end 44.

[0058] 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 may be positioned at the sheath proximal end 44. The sheath hub 24 may include an internal chamber (not shown) 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 implantationof the sheath 40. The sheath hub 24 may be configured for a user (such as a surgeon) to grip to manipulate the sheath 40.

[0059] The sheath hub 24 may 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 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.

[0060] In alternative 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 40 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.

[0061] 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 can comprise a plurality of co-axial layers extending along at least a portion of the length LI of the sheath 40 (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 sheath lumen 50 extending along a central axis Cl. In alternative examples, the sheath 40 may optionally include the inner layer 52 without the outer layer 58, or the outer layer 58 without the inner layer 52, depending upon the particular characteristics desired.

[0062] 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 40 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 below. When the sheath 40 collapses back to its natural diameter, the ridges 62 and valleys 64 can reform.

[0063] In certain 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.

[0064] In certain examples, the inner layer 52 and / or the outer layer 58 can comprise a lubricious, low- friction, and / or relatively non-elastic material. In particular 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) (e.g., 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 sheath lumen 50. Other suitable materials for the inner and outer layers can include polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), ethylene tetrafluoroethylene (ETFE), nylon, polyethylene, polyether block amide (e.g., Pebax), and / or any of the combinations described herein. 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.

[0065] Additionally, some examples of the sheath 40 can include an 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 N.V, Heerlen, the Netherlands), as well as other hydrophilic coatings (e.g., PTFE, polyethylene, polyvinylidene fluoride), are also suitable for use with the sheath 40. Such hydrophilic coatings may also be included on the inner surface of the inner layer 52 to reduce friction between the sheath 40 and the delivery system, thereby facilitating the use and improving safety. In 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.

[0066] In certain examples, the second layer / braided layer 54 can include a braided material. Figs. 6A 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(e.g., 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 60A and 60B can be braided together in a biaxial braid such that filaments 60A oriented along axis A form an angle 9 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 9 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.

[0067] 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 40. In some examples, the filaments 60 can be wires made from metal (e.g., 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 cross-section 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.

[0068] 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 (e.g., toward the central axis Cl of the sheath) when the sheath 40 expands beyond its natural diameter by passage of the delivery apparatus through 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 40. The radially inwardly directed force is sufficient to cause the sheath 40 to collapse radially back to its unexpanded state after the delivery apparatus is passed through the sheath 40.

[0069] In the illustrated example, the elastic layer 56 can comprise one or more members configured as strands, ribbons, or bands 66 helically wrapped around the braided layer 54. For example, in theillustrated 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 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.

[0070] In some examples, the elastic layer can comprise an elastomeric material having a modulus of elasticity of 200 MPa or less. In some examples, the elastic 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 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.

[0071] In certain examples, one or both of the inner layer 52 and / or the outer layer 58 can be configured to resist axial elongation of the sheath 40 when the sheath 40 expands. 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 40 such that the length LI remains substantially constant as the sheath 40 expands and contracts. As used herein with reference to the length LI of the sheath 40, the term "substantially constant" means that the length LI of the sheath 40 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 60A 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 40 expands and contracts. This, in combination with the longitudinal ridges 62 / folds in the inner layer 52 and outer layer 58, can allow the sheath lumen 50 to expand as a prosthetic device is advanced through it.

[0072] For example, 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 52and outer layer 58 can also be bonded or adhered together at the proximal end 44 and / or distal end 42 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 40, 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 40.

[0073] 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 (e.g., distally). As the prosthetic device 12 is advanced through the sheath 40, the sheath 40 can resiliently expand to a second diameter D2 that corresponds to a size or diameter of the prosthetic device. As the prosthetic device 12 is advanced through the sheath 40, the prosthetic device can apply longitudinal force to the sheath 40 in the direction of motion by virtue of the frictional contact between the prosthetic device and the inner surface of the sheath 40. However, as noted herein, the inner layer 52 and / or the outer layer 58 can 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 sheath lumen 50.

[0074] Meanwhile, the angle 0 between the filaments 60A and 60B can increase as the sheath 40 expands to the second diameter D2 to accommodate the prosthetic valve. This can cause the braided layer 54 to foreshorten. However, because the filaments 60 are not engaged or adhered to the inner layer 52 and 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 40. 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 non-elastic. 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 is advanced through the sheath 40, without lengthening, and without constricting. Thus, the force required to push the prosthetic implant through the sheath 40 is significantly reduced.

[0075] 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. 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 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 that must be stretched in order to introduce the prosthetic device, and the amount of time for which a given portion of the vessel must be dilated.

[0076] 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 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. 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 herein and having a natural outer diameter of 3.7 mm. As the prosthetic valve was advanced through the sheath, the outer diameter of the portion of the sheath occupied by the prosthetic valve increased to 8 mm. In other words, it was possible to advance a prosthetic device having a diameter more than two times the outer diameter of the sheath through the sheath, during which the outer diameter of the sheath resiliently increased by 216%. In another example, a sheath with an initial or natural outer diameter of 4.5 mm to 5 mm can be configured to expand to an outer diameter of 8 mm to 9 mm.

[0077] The sheath 40 can include a distal tip 130 that provides a smooth transition between the introducer 80 and / or dilator and the sheath 40 during insertion into the patient's vasculature. In some examples, the sheath 40 is generally defined as a tubular structure (tubular layer) including a tubular wall portion 120 with a central lumen 124 extending therethrough. The distal tip 130 is provided at the distal end 122 of a tubular wall portion 120 coaxial with the tubular wall portion 120 and includes a central lumen extending therethrough. 1

[0078] Fig. 8 is a perspective view of the distal end of the sheath 40 showing the distal tip 130. Fig. 9 is an enlarged cross-sectional view of the distal tip 130 along the section lines provided in Fig. 8. In some examples, the distal tip 130 is mounted on and / or otherwise coupled to the distal end 122 of the tubular wall portion 120. In some examples, the distal tip 130 is separately formed and coupled to the distal end 122 of the tubular wall portion 120. The distal tip 130 can be formed from the same or a portion of the material of the tubular wall portion 120. In some examples the distal tip 130 is an extension of an outer cover extending longitudinally along the sheath 40 in the proximal direction. The distal tip 130 can be formed of, for example, one or more layers of a similar or the same material used to form the outer layer 58 of the sheath 40. In some examples, the distal tip 130 includes an extension of the outer layer 58 of the sheath 40, with or without one more additional layers added by separate processing techniques. The distal tip 130 can include anywhere from 1 to 8 layers of material (including 1, 2, 3, 4, 5, 6, 7, and 8 layers of material). In some examples, the distal tip 130 comprises multiple layers of a Dyneema® material. As described herein, the sheath 40 includes an elastic outer layer 58 and an inner layer 52. In some examples, the outer tubular layer 58 and the inner tubular layer 52 are coupled (for example, reflowed) together at the distal tip 130. For example, the outer tubular layer 58 and the inner tubular layer 52 comprising coupled polymeric layers (for example, Dyneema layers). In some examples, the coupled portion of the outer layer 58 and the inner layer 52 form the distal tip 130.

[0079] In some examples, as described herein, the tubular layer 110 portion of the sheath 40 includes a braided layer 54. The braided layer 54 is provided between the outer tubular layer 58 and the inner tubular layer 52. In some examples, the distal tip 130 extends distally beyond a longitudinal portion of the sheath 40 that includes braided layer 54 and elastic layer 56. That is, braided layer 54 does not extend into the distal tip 130, such that the coupled portion of the outer tubular layer 58 and the inner tubular layer 52 extends beyond the braided layer 54 forming the distal tip 130. In some examples, the braided layer 54 may extend distally beyond the elastic layer 56, and the distal tip 130 may extend distally beyond both the braided layer 54 and elastic layer 56, as shown in FIGS. 8-9.

[0080] Fig. 10 is a perspective view of the distal end of the sheath 40 showing the distal tip 130 in an expanded configuration. Similar to the sheath 40 / tubular wall portion 120, the distal tip 130 is configured to expand due to the outwardly directed radial force exerted on the central lumen of the distal tip 130, for example, by a medical device passing therethrough. In some examples, the distal tip 130 is movable between an unexpanded configuration in which the distal tip 130 has a first outer diameter (DI) and an expanded configuration in which the distal tip 130 has a second, larger, outerdiameter (D2). As shown in Fig. 8, in the unexpanded configuration, the distal tip 130 has a diameter less than the diameter of the tubular wall portion 120. In the expanded configuration as provided in Fig. 10.

[0081] As shown in Fig. 8, the distal tip 130 may have a smaller unexpanded diameter than the tubular wall portion 120 of the sheath 40, giving the distal tip 130 a tapered appearance. This smooths the transition between the introducer 80 and / or dilator and the sheath 40, ensuring that the sheath 40 does not get lodged against the tissue during insertion into the patient. In the unexpanded configuration, the tapered outer surface 132 defined by the distal tip 130 extents between a distal end 112 of the tubular layer 110 and the tubular wall portion 120 of the tubular layer 110. For example, in the unexpanded configuration, the distal tip 130 defines a decreasing tapered outer surface 132 that extends between the tubular wall portion 120 and the distal end 112 of the tubular layer 110 / sheath 40. In some examples, in the unexpanded configuration, the distal tip 130 defines a tubular structure having a frusto-conical shaped outer surface 132.

[0082] In the expanded configuration, as illustrated for example in Fig. 10, the distal tip 130 expands radially outward. In some examples, in the expanded configuration, the tapered outer surface 132 of the distal tip 130 transitions to having a generally uniform diameter along the length of the distal tip 130. That is, in some examples, in the expanded configuration, the distal tip 130 defines a tubular shape having a generally constant outer diameter. For example, in the expanded configuration, a diameter at the distal end 136 of the distal tip 130 corresponds with a diameter at a proximal end 138 of the distal tip 130 such that the distal tip 130 also has a tubular shape.

[0083] In some examples, in the expanded configuration, the distal tip 130 flares outward at its distal end 136. In some examples, in the expanded configuration, the diameter at the distal end 136 of the distal tip 130 is greater than the diameter at the distal end 136 of the distal tip 130 in the unexpanded configuration. In some examples, in the unexpanded configuration, the diameter at the distal end 136 of the distal tip 130 ranges from 3.5mm to 4.5mm. In some examples, the unexpanded diameter of the distal end 136 of the distal tip 130 is approximately 4.0mm. Likewise, in some examples the expanded diameter of the distal end 136 of the distal tip 130 ranges from 8.5mm to 9.5mm. In some examples the expanded diameter of the distal end 136 of the distal tip 130 is 9.0mm. In some examples, the expanded diameter of the distal end 136 of the distal tip 130 is 9.5mm.

[0084] In some examples, the distal tip 130 includes an expansion element 150 to facilitate movement of the distal tip 130 from the unexpanded configuration to the expanded configuration. As described herein, the expansion element 150 can include a folded portion, a weakened portion, cut, slit, score-line, perforation and / or thinned or recessed portion extending along the distal tip 130 that facilitatesmovement of the distal tip 130 between the unexpanded and the expanded configuration. The expansion element 150 allows for the expansion of the distal tip 130 upon the passage of the delivery system, and ease the retraction of the delivery system back into the sheath 40 once the procedure is complete.

[0085] At least a portion of the expansion element 150 extends axially along a length of the distal tip 130. As illustrated in Figs. 11-16, 18, the expansion element 150 extends axially long the distal tip 130 from the distal end 136 of the distal tip 130 toward the proximal end 138 of the distal tip 130 / toward the tubular wall portion 120. In some examples, the expansion element 150 extends along a portion of the overall length of the distal tip 130. In some examples, expansion element 150 extends along a majority of the length of the distal tip 130. For example, the expansion element 150 may include a weakened portion 152 that extends along a majority of the length of the distal tip 130. It is contemplated, when the distal tip 130 includes a plurality of expansion elements 150, the various expansion elements 150 can have uniform / consistent length or the various expansion elements 150 can vary in length. In some examples, the width of the expansion element 150 extends circumferentially around the distal tip 130. For example, where the expansion element 150 comprises a weakened portion, slit, groove, and / or perforation, the expansion element 150 having a width measured circumferentially around the distal tip 130.

[0086] In some examples, the expansion element 150 is configured to unfold, open and / or otherwise separate during expansion of the distal tip 130, allowing the diameter of the distal tip 130 (the outer diameter and the diameter of the central lumen) to increase from a first unexpanded diameter, to a second, larger, expanded diameter. Providing the expansion element 150 on the distal tip 130 helps to control and predict the expansion of the distal tip 130. In some examples, the expansion element 150 ensures that that distal tip 130 will expand at pre-determined location by a pre-determined amount, controlled by the location and size of the expansion element 150 along the distal tip 130. Controlling the location and amount of expansion of the distal tip 130 allows the larger diameter medical device / delivery system to pass through the distal tip 130 of the expandable sheath 40, while also avoiding the uncontrolled tearing of the distal tip 130.

[0087] As illustrated in the example sheaths 40 described herein, the distal tip 130 can include plurality of expansion elements 150 spaced circumferentially around the distal tip 130 and / or longitudinally / axially along the distal tip 130. In some examples, the number and spacing of the expansion elements 150 is provided to allow for uniform expansion of the distal tip 130. For example, controlling the size and spacing of the expansion elements 150 around the circumference of the distaltip 130 and / or a long a length of the distal tip 130 allows for the controlled and consistent expansion of the distal tip 130.

[0088] In the example distal tip 130 illustrated in Figs. 8-9, the expansion element 150 includes a folded portion 200 extending along a length of the distal tip 130. Moving the distal tip 130 from the unexpanded configuration to the expanded configuration causes the folded portion 200 to at least partially unfold. Figs. 8 and 9 show the distal tip 130 folded around an introducer 80 and / or dilator in the unexpanded configuration (e.g., crimped, collapsed, and / or folded). Fig. 10 shows the distal tip 130 after being opened by a passing delivery system.

[0089] As described herein, in the unexpanded configuration the distal tip 130 defines a tapered outer surface 132. In some examples, the smaller unexpanded diameter and / or tapered appearance is the result of the expansion element 150. For example, where the expansion element 150 comprises a folded portion 200, multiple folds (for example, 1, 2, 3, 4, 5, 6, 7, or 8 folds) positioned circumferentially (evenly or unevenly spaced) around the distal tip 130. For example, a circumferential segment of the distal tip 130 can be brought together and then laid against the adjacent outer surface of the distal tip 130 to create an overlapping fold. In the unexpanded configuration, the overlapping portions of the fold extend longitudinally along the distal tip 130. Exemplary folding methods and configurations are described in U.S. Application Number 14 / 880,109 and U.S. Application Number 14 / 880,111, each of which are hereby incorporated by reference in their entireties.

[0090] In the example distal tip 130 illustrated in Fig. 11, the expansion element 150 includes a weakened portion 152 extending along a length of the distal tip 130. The weakened portion 152 is configured to split and / or separate allowing the distal tip 130 to expand radially toward the expanded configuration and can be included as an alternative, or in addition to folding of the distal tip 130. Fig. 11 illustrates the distal tip 130 of the sheath 40 in the unexpanded configuration, with the first and second side edges 161, 163 adjacent to one another. As illustrated in Fig. 12, the distal tip 130 expands and the weakened portion 152 separates, the first side edge 161 and the second side edge 163 separate and a gap is formed between them as they are moved apart from each other. In some examples, as the weakened portion 152 separates, the distal tip 130 flares open such that the diameter at the distal end 136 of the distal tip 130 is larger than the diameter at the proximal end 138 of the distal tip 130.

[0091] The weakened portion 152 includes a perforation, score-line, and / or groove cut into the wall thickness of the distal tip 130. In some examples, the weakened portion 152 extends from the outer surface 135 of the distal tip 130 into a wall thickness of the distal tip 130. Alternatively and / or additionally the distal tip 130 can include weakened portion(s) 152 that extend from the inner surface ofthe distal tip 130 into the wall thickness of the distal tip 130. In some examples, the weakened portion 152 extends through a minority (less than half) of the wall thickness of the distal tip 130. In some examples, the weakened portion 152 extends through a majority of the wall thickness of the distal tip 130. In some examples, for example where the weakened portion 152 comprises a perforation, a portion of the weakened portion 152 extends through the entire wall thickness of the distal tip 130.

[0092] In the example distal tip 130 illustrated in Fig. 13, the expansion element 150 includes an opening 160 extending from the distal end 136 of the distal tip 130. As the distal tip 130 moves from the unexpanded configuration to the expanded configuration, the opening 160 is exposed allowing the distal tip 130 to expand radially toward the larger diameter expanded configuration. In some examples, the opening 160 includes a cut, slit, and / or window extending through the wall thickness of the distal tip 130.

[0093] Fig. 13 provides a perspective view of the distal end of the sheath 40 showing the distal tip 130 in the expanded configuration. As illustrated in Fig. 13, the opening 160 includes a first side edge 161 and a second side edge 163 extending from the distal end 136 of the distal tip 130 and toward the tubular wall portion 120. In some examples, the first side edge 161 and the second side edge 163 extend a direction generally parallel with the longitudinal axis of the distal tip 130. The opening 160 includes a proximal edge 165 extending between a proximal end 162 of the first side edge 161 and a proximal end 164 of the second side edge 163. In some examples, the proximal edge 165 extends circumferentially and / or longitudinally between the proximal end 162 of the first side edge 161 and a proximal end 164 of the second side edge 163. As provided in Fig. 13, in the expanded configuration, the first side edge 161 and the second side edge 163 are spaced apart from each other such that the opening 160 is formed between the first side edge 161, second side edge 163, and the proximal edge 165. In some examples, the circumferential width of the opening 160, measured between the first side edge 161 and the second side edge 163, measures from 10% to 50% of the total circumference of the distal tip 130 of the tubular layer 110.

[0094] Fig. 14 provides a perspective view of the distal end of the sheath 40 showing the distal tip 130 in the expanded configuration including a tapered opening. As provided in Fig. 14, the expanded configuration, the first side edge 161 and the second side edge 163 extend transverse / circumferentially away from each other. In some examples, the first side edge 161 and second side edge 163 extend proximally and meet / join at an apex of the opening 160. That is, the first side edge 161 and the second side edge 163 extend from a common proximal end, such that the opening 160 forms an opening havinga wider distal end. In such examples, the first side edge 161 and second side edge 163 may form a triangle-shaped opening 160.

[0095] Fig. 15 provides a perspective view of the distal end of the sheath 40 showing the distal tip 130 in the unexpanded configuration. In the unexpanded configuration, the first side edge 161 and the second side edge 163 extend adjacent to each other. As shown in Fig. 15, in the unexpanded configuration, at least a portion of each of the first side edge 161 and the second side edge 163 overlap forming a tapered outer surface 132 of the distal tip 130. In some examples, the tapered outer surface 132 of the distal tip 130 provides a transition between the sheath 40 and the introducer 80 and / or dilator, ensuring that the sheath 40 does not damage patient tissue / blood vessel during insertion into the patient.

[0096] In some examples, as shown in Fig. 16, in the unexpanded configuration, the first side edge 161 and second side edge 163 extend in a direction generally parallel with the longitudinal axis of the distal tip 130 such that the first side edge 161 and second side edge 163 contact / abut each other. In some examples, in the unexpanded configuration, first side edge 161 and second side edge 163 are adjacent but spaced apart such that a narrow, longitudinally extending opening is formed therebetween.

[0097] In the example distal tip 130 illustrated in Figs. 17 and 18, the expansion element 150 provided on a reduced diameter distal tip 130. In particular, the distal tip 130 is provided having both an expanded and unexpanded diameter less than the diameter of the tubular wall portion 120 of the sheath 40. By providing a folded portion 200 type expansion element 150 along the reduced diameter distal tip 130, compared to providing the folded portion 200 on a distal tip 130 having the same diameter as the tubular wall portion 120, results in fold(s) having shorter overlapping portions.

[0098] Figs. 17 and 18 show side and end views of the sheath 40 with the folded portion 200 provided on a reduced diameter distal tip 130. As provided in Fig. 18 (and Fig. 20), in each of the example sheaths 40, the distal tip 130 includes a plurality of folded portions 200 spaced circumferentially around the distal tip 130. In some examples, the distal tip 130 includes three folded portions 200 extending along a length of the distal tip 130, the folded portions 200 spaced circumferentially around the distal tip 130. Fig. 17 shows a side view of the sheath 40 in the expanded configuration and Fig. 18 provides an end view of the sheath 40 in the unexpanded configuration. In comparison, Figs. 19 and 20 show side and end views of a sheath 40 with the folded portion 200 provided on a distal tip 130 having a uniform diameter with the tubular wall portion 120 of the sheath 40. As shown in Fig. 18 compared to Fig. 20, the where the folded portion 200 is provided on a reduced diameter distal tip 130, the folded portion 200 has shorter overlapping portions. Providing shorted folds / overlapping portions, helps to ensure thatthe folded portion 200 more fully unfolds when a dilator and / or medical device is advanced through the distal tip 130. This reduces the risk of the dilator / medical device catching and / or tearing the sheath 40.

[0099] As described herein, as the sheath 40 / distal tip 130 of Figs. 17 and 18 moves from the unexpanded to the expanded configuration, the folded portion 200 at least partially unfolds and the diameter of the distal tip 130 increases from a first outer diameter (DI) to a second, larger, outer diameter (D2). As illustrated in Fig. 17, in the expanded configuration, the second outer diameter (D2) of the distal tip 130 is less than the outer diameter of the tubular wall portion 120 of the sheath 40. In some examples, and as shown in Fig. 17, in the expanded configuration, the folded portion 200 of the distal tip 130 at least partially unfolds and the distal tip 130 defines has uniform diameter along a length of the distal tip 130. In some examples, in the expanded configuration, the distal tip 130 has a uniform diameter along the entire length of the distal tip 130. In some examples, in the unexpanded configuration, the inner diameter of the distal tip 130 ranges from 10F to 14F. In some examples, in the unexpanded configuration, the inner diameter of the distal tip 130 is 12F. In some examples, in the expanded configuration, the inner diameter of the distal tip 130 ranges from 24F to 30F. In some examples, in the expanded configuration, the inner diameter of the distal tip 130 is 27F.

[0100] As illustrated in Fig. 17, in the expanded configuration, and similarly provided in the unexpanded configuration, the reduced diameter distal tip 130 includes a distal end portion 137 and a transition portion 139 extending between the distal end portion 137 and the tubular wall portion 120 of the tubular layer 110. As provided in Fig. 17, the diameter of the distal end portion 137 is less than the diameter of the tubular wall portion 120. For example, the diameter of the tubular wall portion 120 can range from 26F to 28F and the diameter of the distal tip 130 / distal end portion 137 can range from 23F to 25F. In some examples, the diameter of the tubular wall portion 120 is 27F and the diameter of the distal tip 130 / distal end portion 137 is 24F.

[0101] As shown in Fig. 17, in some examples, the distal end portion 137 defines a tubular structure extending proximally from the distal end 136 of the distal tip 130 toward the tubular wall portion 120 of the sheath 40. The distal end portion 137 has a generally uniform diameter along its length in the unexpanded and / or expanded configuration. In some examples, in the expanded configuration, the distal tip 130 defines a flared outer surface. That is, as the distal tip 130 / distal end portion 137 moves to / toward the expanded configuration, the diameter of the distal end portion 137 increases along a distal portion of the distal end portion 137 approaching the distal end 136. As described herein, the tubular wall portion 120 of the sheath 40 includes an outer tubular layer 58, an inner tubular layer 52, and a braided layer 54 provided between the outer tubular layer 58 and the inner tubular layer 52. Insome examples, as illustrated in Fig. 17, at least a portion of the braided layer 54 extends into the distal tip 130. In some examples, the braided layer 54 extends along the transition portion 139 and along at least a portion of the distal end portion 137.

[0102] As illustrated in Fig. 17, the transition portion 139 extends between the tubular layer 110 of the sheath 40 and the distal end portion 137 of the distal tip 130. The transition portion 139 has a decreasing diameter extending from the tubular wall portion 120 towards the distal end portion 137 / distal end 136 of the distal tip 130. In some examples, the transition portion 139 defines a decreasing taper between the tubular wall portion 120 and the distal end portion 137 of the distal tip 130. In some examples, the transition portion 139 has a step-like shape, and provides a step-like surface between the tubular wall portion 120 and the distal end portion 137 of the distal tip 130.

[0103] In some examples, the distal tip 130 includes an outer cover 180 provided over the expansion element 150. In some examples the outer cover 180 is provided over the expansion element 150 to conceal / protect the expansion element 150 from the environment during advancement of the sheath 40 within the patient's body in the unexpanded / crimped configuration. In some examples, the outer cover 180 is configured to open, separate and / or tear during expansion of the distal tip 130. For example, the outer cover 180 can be provided as a thin film over the distal tip 130 that is configured to tear along with the expansion element 150 when the distal tip 130 expands.

[0104] In some examples, the outer cover 180 is made from an elastic material configured to expand and / or stretch over the expansion element 150 / opening 160 during expansion of the distal tip 130. In some examples, the outer cover 180 is composed of an extensible material, such as low density polyethylene (LDPE) or ultra-high molecular weight polyethylene (UHMWPE), configured to expand / stretch when the distal tip 130 expands when the medical device passes therethrough.

[0105] In some examples, the distal tip 130 can be formed integrally with the tubular wall portion 120 of the sheath 40, that is, the distal tip 130 can be molded, extruded, and / or otherwise formed with the tubular wall portion 120 of the sheath 40. In some examples, the distal tip 130 is separately formed and coupled to the distal end of the tubular wall portion 120 of the sheath 40. In either instance, the distal tip 130 is formed at the distal end 122 of the tubular wall portion 120. In some examples as described herein, particularly in reference to Figs. 17 and 18, the diameter of the distal tip 130 can be less than the diameter of the tubular wall portion 120. Here, the tubular wall portion 120 can be heat formed on a mandrel having an increased diameter portion corresponding to the tubular wall portion 120 and a reduced diameter portion corresponding to the distal tip 130. In some examples, where the tubular wall portion 120 includes an outer tubular layer 58, an inner tubular layer 52, and a braided layer 54provided between the outer tubular layer 58 and the inner tubular layer 52, the various layers of the sheath 40 can be positioned along the mandrel such that the braided layer 54 is provided along the increased diameter portion and also along a length of the reduced diameter portion, such that when the sheath 40 is formed the braided layer 54 extends along a portion of the distal tip 130. Mounted on the mandrel, the outer tubular layer 58, inner tubular layer 52, and braided layer 54 are coupled together by a heat process such that the various layers of material are reflowed together.

[0106] In some examples, a distal tip 130 can be added, the sheath 40 and distal tip 130 can be crimped and / or folded, and the crimping / folding of the distal tip 130 and sheath 40 can be maintained, by the following method. As mentioned above, the distal tip 130 can be an extension of the outer tubular layer 58, inner tubular layer 52, and braided layer 54 of the sheath 40. It can also be a separate, multilayer tubing that is heat bonded to the remainder of the sheath 40 prior to the tip crimping processing steps. In some examples, the separate, multilayer tubing is heat bonded to a distal extension of the outer layer 58 of the sheath 40 to form the distal tip 130. In some examples, at least a portion of the distal tip 130 is folded or crimped to include the folded portion 200 extending along a length of the distal tip 130.Folding the distal tip 130 can form a tapered outer surface 132 along the distal tip 130. In some examples, a plurality of folded portions 200 at folded along a length of the distal tip 130. In some examples, because the diameter of the distal tip 130 is less than the diameter of the tubular wall portion 120, the circumferential (overlapping) length of the folds is less than those sheaths 40 where the distal tip 130 has an initial diameter corresponding to the tubular wall portion 120. For example, where the diameter of the distal tip 130 is less than the diameter of the tubular wall portion 120, there is less material that can be formed / folded into the folded portion 200. Advantageously, the shorter length of the resulting folds helps to ensure that all of the folds are opened when the introducer 80 and / or dilator is advanced through the sheath 40, allowing a prosthetic valve to be advanced without posing a risk of engagement between the prosthetic valve and the sheath 40 and tearing of the sheath 40.

[0107] For crimping of the sheath 40 after tip attachment, the sheath 40 is heated on small mandrel. The distal tip 130 can be folded around the mandrel to create the folded configuration shown in FIG. 8. The folds be added to the distal tip 130 prior to the tip crimping process, or at an intermediate point during the tip crimping process. In some examples, the small mandrel can be from about 2 millimeters to about 4 millimeters in diameter (including about 2.2 millimeters, about 2.4 millimeters, about 2.6 millimeters, about 2.8 millimeters, about 3.0 millimeters, about 3.2 millimeters, about 3.4 millimeters, about 3.6 millimeters, about 3.8 millimeters and about 4.0 millimeters).

[0108] Similarly, other types of expansion elements 150 can be added to the distal tip 130 prior to the tip folding or crimping process, or at an intermediate point during the tip folded or crimping processes. For example, a weakened portion 152 and or opening 160 type expansion element 150 can be added to the distal tip 130 by a cutting, etching (e.g., laser etching) or otherwise reducing the material of the distal tip 130 at the location of the expansion element 150.

[0109] During crimping and / or securing the distal tip 130 is an unexpanded configuration, the heating temperature will be lower than the melting point of the material used. This can cause the material to shrink on its own to a certain extent. For example, such as those where Dyneema® materials are utilized as part of the sheath outer layer 58 and / or distal tip 130 materials, a sheath crimping process begins by heating the sheath 40 on a 3 millimeter mandrel to about 125 degrees Celsius (lower than Dyneema® melting point of about 140 degrees Celsius). This causes the sheath 40 to crimp itself to about a 6 millimeter outer diameter. At this point, the sheath 40 and distal tip 130 are allowed to cool. A heat shrink tube can then be applied. In some examples, the heat shrink tube can have a melting point that is about the same as the melting point of the distal tip 130 material. The sheath 40 with the heat shrink tube extending over the sheath 40 and the distal tip 130 is heated again (for example, to about 125 degrees Celsius for sheaths including Dyneema® outer layers and distal tip 130), causing the sheath 40 to crimp to an even smaller diameter. At the distal tip 130, a higher temperature can be applied (for example, from about 145 degrees Celsius to about 155 degrees Celsius for Dyneema® material) causing the layers of material to melt together in the folded configuration shown in FIG. 8 (the folds and / or other expansion element 150 can be added at any point during this process). The bonds at the distal tip 130 induced by the high temperature melting step will still be weak enough to be broken by a passing delivery system. As a final step, the heat shrink tube is removed, and the shape of the sheath 40 remains at the crimped and / or unexpanded diameter.

[0110] A method for delivering a medical device through an expandable sheath as described herein (for example, to a procedure site) is provided. In this example, as shown in Fig. 2, an introducer 80 is advanced into the central lumen of the sheath 40. In some examples, the introducer 80 is coupled to the sheath 40 such that axial movement between the introducer 80 and the sheath 40 is eliminated. Preventing movement and gapping between the introducer / dilator 80 and the sheath 40 during insertion reduces the risk of trauma to the patient's vasculature.

[0111] The sheath 40 with the introducer 80 provided therein is advanced at least partially into the patient's blood vessel. With the sheath distal end 42 in the desired position, the introducer 80 is removed from the central lumen of the sheath 40.T1

[0112] In some examples, a dilator is advanced through the central lumen of the sheath 40. In some examples, this causes the sheath 40 to move from the unexpanded configuration to / toward the expanded configuration at a location proximate the dilator in response to the outwardly directed radial force of the dilator exerted against the central lumen of the sheath 40.

[0113] The dilator can be used to initially expand the sheath 40 helping to reduce the needed push forces when the delivery device and / or prosthetic device is moved through the sheath 40. In some examples, the dilator is advanced through the central lumen of the distal tip 130. This causes the distal tip 130 to move from the unexpanded configuration to the expanded configuration at a location proximate the dilator in response to an outwardly directed radial force of the dilator exerted against the central lumen of the distal tip 130. In some examples, advancing the dilator through the central lumen of the distal tip 130 causes the expansion element 150 to open and / or separate as the distal tip 130 moves to / toward the expanded configuration. In some examples, where the sheath 40 and / or distal tip 130 include a folded portion 200, advancing the dilator through the sheath 40 and / or distal tip 130 causes a length of the folded portion 200 to at least partially unfold. The dilator is then removed from the central lumen of the distal tip 130 and the sheath 40.

[0114] The medical device is then advanced through the central lumen of the sheath 40 and beyond a distal opening of the sheath 40 to the treatment site. Fig. 1 shows the example device for delivering the prosthetic device. In some examples, as the medical device is advanced through the central lumen of the sheath 40, the sheath 40 locally expand from the unexpanded configuration to / toward the expanded configuration at the location proximate the medical device in response to the outwardly directed radial force of the medical device exerted against the various layers of the sheath 40.

[0115] In some examples, where the sheath 40 includes an outer layer 50 and / or outer cover 180, the outer layer 50 and / or outer cover 180 can provide an inwardly directed radial force causing the sheath 40 and / or distal tip 130 to move from the expanded state towards the unexpanded state. According, as the dilator and / or medical device move through the sheath 40 and / or distal tip 130, the sheath 40 and / or distal tip 130 locally contracts at least partially back to the unexpanded configuration.

[0116] The medical device described herein can include a prosthetic device mounted in a radially crimped state on a delivery apparatus, and the act of advancing the prosthetic device through the lumen of the sheath 40 comprises advancing the delivery apparatus and the prosthetic device through lumen of the sheath 40 and into the vasculature of the patient. In some examples, the prosthetic device comprises a prosthetic heart valve and the method further comprises implanting the prosthetic heart valve at a treatment site within the patient. As described herein, the prosthetic heart valve is mountedon a balloon catheter of the delivery apparatus as the prosthetic heart valve is advanced through the sheath 40.

[0117] Exemplary Aspects

[0118] 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.

[0119] Example 1: An expandable sheath for deploying a medical device comprising: a tubular layer including: a tubular wall portion having a proximal end (e.g., a flared proximal end for coupling to a sheath hub) and a distal end, and a central lumen extending therethrough; and a distal tip provided at the distal end of the tubular wall portion coaxial with the tubular wall portion and having a central lumen extending therethrough, wherein the distal tip is movable between an unexpanded configuration in which the distal tip has a first outer diameter and an expanded configuration in which the distal tip has a second, larger, outer diameter due to an outwardly directed radial force exerted on the central lumen of the distal tip (for example, by a medical device passing therethrough), and wherein the distal tip includes an expansion element (for example, split, weakened portion, folded portion) to facilitate movement of the distal tip from the unexpanded configuration to the expanded configuration.

[0120] Example 2: An expandable sheath according to any example herein, particularly example 1, wherein the distal tip includes a plurality of expansion elements spaced circumferentially around the distal tip.

[0121] Example 3: An expandable sheath according to any example herein, particularly examples 1-2, wherein the expansion element comprises at least one of a folded portion, cut, slit, weakened portion, score-line, perforation and / or thinned / recessed portion extending along the distal tip.

[0122] Example 4: An expandable sheath according to any example herein, particularly examples 1-3, wherein at least a portion of the expansion element extends axially along a length of the distal tip.

[0123] Example 5: An expandable sheath according to any example herein, particularly examples 1-4, wherein the expansion element extends from a distal end of the distal tip.

[0124] Example 6: An expandable sheath according to any example herein, particularly examples 1-5, wherein the expansion element extends along a portion of an overall length of the distal tip.

[0125] Example 7: An expandable sheath according to any example herein, particularly examples 1-6, wherein the expansion element has a width extending circumferentially around the distal tip.

[0126] Example 8: An expandable sheath according to any example herein, particularly examples 1-7, wherein the expansion element comprises a weakened portion that is configured to split or separate allowing the distal tip to expand radially toward the expanded configuration (for example, when the medical device passes therethrough).

[0127] Example 9: An expandable sheath according to any example herein, particularly example 8, wherein the weakened portion extends from an outer surface of the distal tip into a wall thickness of the distal tip.

[0128] Example 10: An expandable sheath according to any example herein, particularly examples 1-9, wherein the expansion element comprises an opening (for example, cut, slit, window) that is configured to open or separate allowing the distal tip to expand radially toward the expanded configuration (for example, when the medical device passes therethrough), wherein the opening includes a first side edge and a second side edge, the first side edge and the second side edge extending from a distal end of the distal tip toward the tubular wall portion.

[0129] Example 11: An expandable sheath according to any example herein, particularly example 10, wherein, in the unexpanded configuration, the first side edge and the second side edge extend adjacent to each other.

[0130] Example 12: An expandable sheath according to any example herein, particularly example 10, wherein, in the expanded configuration, the first side edge and the second side edge extend circumferentially away from each other.

[0131] Example 13: An expandable sheath according to any example herein, particularly example 10, wherein the opening further includes a proximal edge extending circumferentially between a proximal end of the first side edge and a proximal end of the second side edge, wherein, in the expanded configuration, the first side edge and the second side edge are spaced apart from each other such that the opening is formed between the first side edge, second side edge and the proximal edge.

[0132] Example 14: An expandable sheath according to any example herein, particularly example 10, wherein in the unexpanded configuration, at least a portion of each of the first side edge and the second side edge overlap forming a tapered outer surface of the distal tip.

[0133] Example 15: An expandable sheath according to any example herein, particularly examples 1-14, wherein, in the unexpanded configuration, the distal tip defines a tapered outer surface extending between a distal end of the tubular layer and the tubular wall portion of the tubular layer (for example, in the unexpanded configuration, the distal tip defines a decreasing tapered outer surface that extends between the tubular wall portion and the distal end of the tubular layer).

[0134] Example 16: An expandable sheath according to any example herein, particularly examples 1-15, wherein the distal tip defines a tubular structure having a frusto-conical shaped outer surface in the unexpanded configuration.

[0135] Example 17: An expandable sheath according to any example herein, particularly examples 1-16, wherein, in the expanded configuration, the distal tip flares outward at a distal end of the distal tip.

[0136] Example 18: An expandable sheath according to any example herein, particularly examples 1-17, wherein, in the expanded configuration, a diameter at a distal end of the distal tip is greater than a diameter at the distal end of the distal tip in the unexpanded configuration.

[0137] Example 19: An expandable sheath according to any example herein, particularly examples 1-18, wherein, in the expanded configuration, a diameter at a distal end of the distal tip corresponds with a diameter at a proximal end of the distal tip.

[0138] Example 20: An expandable sheath according to any example herein, particularly examples 1-19, further including an outer cover provided over the expansion element.

[0139] Example 21: An expandable sheath according to any example herein, particularly example 20, wherein the outer cover is configured to open (for example, separate and / or tear) during expansion of the distal tip.

[0140] Example 22: An expandable sheath according to any example herein, particularly example 20, wherein the outer cover is made from an elastic material configured to expand (for example, stretch) over the expansion element / opening during expansion of the distal tip.

[0141] Example 23: An expandable sheath according to any example herein, particularly examples 1-22, wherein tubular layer includes: an outer tubular layer (for example, and elastic outer tubular layer), and an inner tubular layer, the outer tubular layer and the inner tubular layer are coupled together (for example, reflowed together) at the distal tip, (for example, the outer tubular layer and the inner tubular layer comprising polymeric layers), wherein a coupled portion of the outer tubular layer and the inner tubular layer form the distal tip.

[0142] Example 24: An expandable sheath according to any example herein, particularly example 23, wherein the tubular layer includes: a braided layer provided between the outer tubular layer and the inner tubular layer, where the braided layer does not extend into the distal tip, wherein the coupled portion of the outer tubular layer and the inner tubular layer extends beyond the braided layer forming the distal tip.

[0143] Example 25: A method of delivering a medical device and expanding an introducer sheath comprising: providing the sheath comprising: a radially expandable cylindrical outer layer having aproximal end and a distal end, and defining a central lumen extending longitudinally between the proximal end and the distal end; and a distal tip provided at (for example, mounted on / coupled to) the distal end of the outer layer, the distal tip having a decreasing tapered outer surface providing a transition between the sheath and an introducer extending through the sheath and distal tip; where the distal tip is movable between an expanded configuration in which the distal tip has a first outer diameter and an unexpanded configuration in which the distal tip has a second, larger, outer diameter due to an outwardly directed radial force exerted on a central lumen of the distal tip; and wherein the distal tip includes an expansion element configured to open and / or separate to facilitate movement of the distal tip from the unexpanded configuration to the expanded configuration. The method further comprising: advancing the sheath, with the introducer provided therein, at least partially into a blood vessel of a patient; withdrawing the introducer from the central lumen of the sheath; advancing a dilator into the central lumen of the sheath; advancing the dilator through a central lumen of the distal tip causing the distal tip to move from the unexpanded configuration to the expanded configuration at a location proximate the dilator in response to an outwardly directed radial force of the dilator exerted against the central lumen of the distal tip; withdrawing the dilator from the central lumen of the sheath; advancing a medical device through the central lumen of the sheath; and advancing the medical device beyond a distal opening of the sheath to the treatment site.

[0144] Example 26: A method according to any example herein, particularly example 25, wherein advancing the dilator through the central lumen of the distal tip causes the expansion element to open and / or separate as the distal tip moves to the expanded configuration.

[0145] Example 27: A method according to any example herein, particularly examples 25-26, wherein advancing the dilator and / or medical device through the central lumen of the sheath causes the sheath to locally expand from an unexpanded configuration to an expanded configuration at a location proximate the dilator and / or medical device in response to an outwardly directed radial force of the dilator and / or medical device exerted against the central lumen of the sheath, wherein the outer layer provides an inwardly directed radial force that causes the sheath to locally contract at least partially back to the unexpanded configuration as the dilator and / or medical device passes through the central lumen.

[0146] Example 28: A method according to any example herein, particularly example 27, wherein the sheath includes an inner layer having at least one folded portion extending along a length of the inner layer, and wherein locally expanding the central lumen of the sheath causes a length of the folded portion to at least partially unfold.

[0147] Example 29: A method according to any example herein, particularly examples 27-28, wherein the outer layer provides an inwardly directed radial force causing the sheath to move from the expanded configuration towards the unexpanded configuration.

[0148] Example 30: A method according to any example herein, particularly examples 28-29, wherein the outer layer is provided over the inner layer, where the outer layer is discontinuous and includes an overlapping portion and an underlying portion, wherein when the sheath is in the unexpanded configuration, the overlapping portion overlaps the underlying portion with the folded portion of the inner layer disposed between the overlapping portion and the underlying portion, and a tubular strain relief layer provided over the inner layer that limits radial expansion of the sheath, where the strain relief layer extends at least partially over the outer layer.

[0149] Example 31: A method according to any example herein, particularly examples 25-30, wherein the medical device is a prosthetic device mounted in a radially crimped state on a delivery apparatus.

[0150] Example 32: A method according to any example herein, particularly example 31, wherein the prosthetic device comprises a prosthetic heart valve and the method further comprises implanting the prosthetic heart valve at a treatment site within the patient.

[0151] Example 33: A method according to any example herein, particularly example 32, wherein the prosthetic heart valve is mounted on a balloon catheter of a delivery apparatus as the prosthetic heart valve is advanced through the sheath.

[0152] Example 34: expandable sheath for deploying a medical device comprising: a tubular wall portion having a proximal end a distal end, and defining and a central lumen extending therethrough; and a distal tip provided at (for example, mounted on / coupled to) the distal end of a tubular wall portion coaxial with the tubular wall portion and having a central lumen extending therethrough; wherein the distal tip is movable between an unexpanded configuration in which the distal tip has a first outer diameter and an expanded configuration in which the distal tip has a second, larger, outer diameter due to an outwardly directed radial force exerted on the central lumen of the distal tip (for example, by a medical device passing therethrough), wherein, in the unexpanded configuration, the distal tip has a diameter less than a diameter of the tubular wall portion, and wherein the distal tip includes a folded portion extending along a length of the distal tip, where moving the distal tip from the unexpanded configuration to the expanded configuration causes the folded portion to at least partially unfold.

[0153] Example 35: An expandable sheath according to any example herein, particularly example 34, wherein, in the unexpanded configuration, the distal tip includes a transition portion extending between the tubular wall portion of the tubular layer and a distal end portion of the distal tip.

[0154] Example 36: An expandable sheath according to any example herein, particularly example 35, wherein the transition portion has a decreasing taper between the tubular wall portion and the distal end portion of the distal tip.

[0155] Example 37: An expandable sheath according to any example herein, particularly examples 35-36, wherein the transition portion has a step-like shape, and provides a step-like surface between the tubular wall portion and the distal end portion of the distal tip.

[0156] Example 38: An expandable sheath according to any example herein, particularly examples 35-37, wherein the distal end portion of the distal tip has a generally uniform diameter.

[0157] Example 39: An expandable sheath according to any example herein, particularly examples SASS, wherein, in the expanded configuration, the folded portion of the distal tip is at least partially unfolded and the distal tip defines a uniform diameter along a length of the distal tip.

[0158] Example 40: An expandable sheath according to any example herein, particularly examples SASS, wherein, in the expanded configuration, the folded portion of the distal tip is at least partially unfolded and the distal tip defines a flared outer surface.

[0159] Example 41: An expandable sheath according to any example herein, particularly examples 34- 40, wherein the distal tip includes a plurality of folded portions spaced circumferentially around the distal tip.

[0160] Example 42: An expandable sheath according to any example herein, particularly examples 34- Al, wherein the tubular wall portion includes: an outer tubular layer; an inner tubular layer; and a braided layer provided between the outer tubular layer and the inner tubular layer, where at least a portion of the braided layer extends into the distal tip.

[0161] Example 43: An expandable sheath according to any example herein, particularly examples 34- 42, wherein the distal tip includes an expansion element (for example, split, weakened portion, folded portion) to facilitate movement of the distal tip from the unexpanded configuration to the expanded configuration. In some examples, the expansion element is configured to open and / or separate during expansion of the distal tip.

[0162] Example 44: A method of forming an expandable sheath including: providing a tubular layer including a tubular wall portion having a uniform outer diameter; forming a distal tip at a distal end of the tubular wall portion, where the distal tip has a diameter less than a diameter of the tubular wallportion; and folding at least a portion of the distal tip to include a folded portion extending along a length of the distal tip forming a tapered outer surface of the distal tip.

[0163] Example 45: A method according to any example herein, particularly example 44, wherein folding at least a portion of the distal tip includes folding a plurality of folded portions along a length of the distal tip.

[0164] Example 46: A method according to any example herein, particularly examples 44-45, wherein the distal tip molded to the tubular wall portion.

[0165] Example 47: A method according to any example herein, particularly examples 44-46, wherein the tubular wall portion heat formed on a mandrel having an increased diameter portion and a reduced diameter portion corresponding to the distal tip.

[0166] Example 48: A method according to any example herein, particularly examples 44-47, wherein the tubular wall portion includes an outer tubular layer, an inner tubular layer, and a braided layer provided between the outer tubular layer and the inner tubular layer, wherein the outer tubular layer, inner tubular layer, and braided layer are coupled together by a heat process (for example, reflowed together).

[0167] Example 49: A method according to any example herein, particularly example 48, wherein at least a portion of the braided layer extends into the distal tip.

[0168] Example 50: A method of delivering a medical device and expanding an introducer sheath comprising:

[0169] Example 50: A method of delivering a medical device and expanding an introducer sheath comprising: providing the sheath comprising: a radially expandable cylindrical outer layer having a proximal end and a distal end, and defining a central lumen extending longitudinally between the proximal end and the distal end; and a distal tip provided at (for example, mounted on / coupled to) the distal end of the outer layer, the distal tip having a transition between the sheath and an introducer extending through the sheath and distal tip; where the distal tip is movable between an expanded configuration in which the distal tip has a first outer diameter and an unexpanded configuration in which the distal tip has a second, larger, outer diameter due to an outwardly directed radial force exerted on a central lumen of the distal tip, where, in the unexpanded configuration, the distal tip has a diameter less than a diameter of the outer layer, the distal tip including a folded portion extending along a length of the distal tip, where moving the distal tip from the unexpanded configuration to the expanded configuration causes the folded portion to at least partially unfold. The method further comprising: advancing the sheath, with the introducer provided therein, at least partially into a blood vessel of apatient; withdrawing the introducer from the central lumen of the sheath; advancing a dilator into the central lumen of the sheath; advancing the dilator through a central lumen of the distal tip causing the distal tip to move from the unexpanded configuration to the expanded configuration at a location proximate the dilator in response to an outwardly directed radial force of the dilator exerted against the central lumen of the distal tip causing the folded portion to at least partially unfold; withdrawing the dilator from the central lumen of the sheath; advancing a medical device through the central lumen of the sheath; and advancing the medical device beyond a distal opening of the sheath to the treatment site.

[0170] 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:

1. An expandable sheath for deploying a medical device comprising: a tubular layer including: a tubular wall portion having a proximal end and a distal end, and defining a central lumen extending therethrough; and a distal tip provided at the distal end of the tubular wall portion coaxial with the tubular wall portion and having a central lumen extending therethrough; wherein the distal tip is movable between an unexpanded configuration in which the distal tip has a first outer diameter (DI) and an expanded configuration in which the distal tip has a second, larger, outer diameter (D2) due to an outwardly directed radial force exerted on the central lumen of the distal tip, wherein the distal tip includes an expansion element to facilitate movement of the distal tip from the unexpanded configuration to the expanded configuration.

2. The sheath of claim 1, wherein the distal tip includes a plurality of expansion elements spaced circumferentially around the distal tip.

3. The sheath of claim 1, wherein the expansion element comprises at least one of a folded portion, cut, slit, weakened portion, score-line, perforation and / or thinned / recessed portion extending along the distal tip.

4. The sheath of claim 1, wherein at least a portion of the expansion element extends axially along a length of the distal tip.

5. The sheath of claim 1, wherein the expansion element extends from a distal end of the distal tip.

6. The sheath of claim 1, wherein the expansion element has a width extending circumferentially around the distal tip.

7. The sheath of claim 1, wherein the expansion element comprises a weakened portion that is configured to split or separate allowing the distal tip to expand radially toward the expanded configuration, wherein the weakened portion extends from an outer surface of the distal tip into a wall thickness of the distal tip.

8. The sheath of claim 5, wherein the expansion element comprises an opening that is configured to open or separate allowing the distal tip to expand radially toward the expanded configuration, wherein the opening includes a first side edge and a second side edge, the first side edge and the second side edge extending from the distal end of the distal tip toward the tubular wall portion.

9. The sheath of claim 8, wherein, in the unexpanded configuration, the first side edge and the second side edge extend adjacent to each other, and wherein, in the expanded configuration, the first side edge and the second side edge extend circumferentially away from each other.

10. The sheath of claim 8, wherein the opening further includes a proximal edge extending circumferentially between a proximal end of the first side edge and a proximal end of the second side edge, wherein, in the expanded configuration, the first side edge and the second side edge are spaced apart from each other such that the opening is formed between the first side edge, second side edge and the proximal edge.

11. The sheath of claim 10, wherein in the unexpanded configuration, at least a portion of each of the first side edge and the second side edge overlap forming a tapered outer surface of the distal tip.

12. The sheath of claim 1, wherein, in the unexpanded configuration, the distal tip defines a tapered outer surface extending between a distal end of the tubular layer and the tubular wall portion of the tubular layer, and wherein the distal tip defines a tubular structure having a frusto-conical shaped outer surface in the unexpanded configuration.

13. The sheath of claim 1, wherein, in the expanded configuration, the distal tip flares outward at a distal end of the distal tip.

14. The sheath of claims 1, wherein, in the expanded configuration, a diameter at a distal end of the distal tip is greater than a diameter at the distal end of the distal tip in the unexpanded configuration.

15. The sheath of claim 1, wherein, in the expanded configuration, a diameter at a distal end of the distal tip corresponds with a diameter at a proximal end of the distal tip.

16. The sheath of claim 1, further including an outer cover provided over the expansion element.

17. The sheath of claim 16, wherein the outer cover is configured to open during expansion of the distal tip.

18. The sheath of claim 1, wherein tubular layer includes: an outer tubular layer, and an inner tubular layer, the outer tubular layer and the inner tubular layer are coupled together at the distal tip, wherein a coupled portion of the outer tubular layer and the inner tubular layer form the distal tip.

19. The sheath of claim 23, wherein the tubular layer includes: a braided layer provided between the outer tubular layer and the inner tubular layer, where the braided layer does not extend into the distal tip, wherein the coupled portion of the outer tubular layer and the inner tubular layer extends beyond the braided layer forming the distal tip.

20. A method of delivering a medical device and expanding an introducer sheath comprising: providing the sheath comprising: a radially expandable cylindrical outer layer having a proximal end and a distal end, and defining a central lumen extending longitudinally between the proximal end and the distal end; and a distal tip provided at the distal end of the outer layer, the distal tip having a decreasing tapered outer surface providing a transition between the sheath and an introducer extending through the sheath and distal tip; where the distal tip is movable between an expanded configuration in which the distal tip has a first outer diameter and an unexpanded configuration in which the distal tip has a second, larger, outer diameter due to an outwardly directed radial force exerted on a central lumen of the distal tip; wherein the distal tip includes an expansion element configured to open and / or separate to facilitate movement of the distal tip from the unexpanded configuration to the expanded configuration; advancing the sheath, with the introducer provided therein, at least partially into a blood vessel of a patient; withdrawing the introducer from the central lumen of the sheath; advancing a dilator into the central lumen of the sheath; advancing the dilator through a central lumen of the distal tip causing the distal tip to move from the unexpanded configuration to the expanded configuration at a location proximate the dilator in response to an outwardly directed radial force of the dilator exerted against the central lumen of the distal tip; withdrawing the dilator from the central lumen of the sheath; advancing a medical device through the central lumen of the sheath; and advancing the medical device beyond the distal opening of the sheath to the treatment site.

21. An expandable sheath for deploying a medical device comprising: a tubular layer including: a tubular wall portion having a proximal end, a distal end, and defining a central lumen extending therethrough; and a distal tip provided at the distal end of a tubular wall portion coaxial with the tubular wall portion and having a central lumen extending therethrough; wherein the distal tip is movable between an unexpanded configuration in which the distal tip has a first outer diameter and an expanded configuration in which the distal tip has a second, larger, outer diameter due to an outwardly directed radial force exerted on the central lumen of the distal tip, wherein, in the unexpanded configuration, the distal tip has a diameter less than a diameter of the tubular wall portion, wherein the distal tip includes a folded portion extending along a length of the distal tip, where moving the distal tip from the unexpanded configuration to the expanded configuration causes the folded portion to at least partially unfold.

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