Spacer for expandable introducer sheath

Abstract

Disclosed herein are introducer sheaths (312). The introducer sheath assembly (300) includes an introducer sheath (312) for deploying a medical device, a spacer (350) adjacent a proximal end (316) of the introducer sheath (312), wherein the spacer (350) defines an effective spacer length corresponding to a decrease in the effective length (Leff) of the introducer sheath (312).

Description

SPACER FOR EXPANDABLE INTRODUCER SHEATHCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 674,064, filed July 22, 2024, which is incorporated by reference in its entirety for all purposes.TECHNICAL FIELD

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

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

[0004] Percutaneous interventional medical procedures utilize the large blood vessels of the body to reach target destinations rather than surgically opening a target site. There are many types of diseases or states that can be treated via interventional methods including coronary blockages, valve replacements (TAVR) and brain aneurysms. These techniques involve using wires, catheters, balloons, electrodes and other thin devices to travel down the length of the blood vessels from the access site to the target site. The devices have a proximal end which the clinician controls outside of the body and a distal end inside the body, which is responsible for treating the disease state. Percutaneous interventional procedures offer several advantages over open surgical techniques. First, they require smaller incision sites, which reduces scarring and bleeding as well as infection risk. Procedures are also less traumatic to the tissue, so recovery times are reduced. Finally, interventional techniques can usually be performed much faster, and with fewer clinicians participating in the procedure, so 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 site sequentially. 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 / proximal hub or handle 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] In example sheath system, the structure of at the proximal end of the sheath is complicated by the need to provide hemostasis between the sheath and the patient and the risk of ballooning or damage to the sheath due to the patient’s internal blood pressure and the inadvertent flow of blood into the portion of the sheath external to the patient. Entry site bleeding is known to cause pain and prolong hospitalization time. Additionally, it is difficult to provide universal length sheath that will prevent hemostasis due to differences in patient anatomy, for example, the thickness of the fat layer at the insertion site. Accordingly, there remains a need for improvements to the devices, systems and methods of introducing expandable sheaths that are customizable to accommodate variations in patient anatomy while also ensuring hemostasis at the treatment site.SUMMARY

[0008] Aspects of the disclosure provide an introducer sheath having an effective length that can be customized to accommodate variations in patient anatomy while also ensuring hemostasis atthe treatment site. This helps to prevent entry site bleeding, reduce hospitalization and procedure time, and provides a sheath system that is intuitive and easy to operate.

[0009] In one of its basic configurations, the present disclosure provides a sheath system for deploying a medical device including spacer coupled to the introducer sheath for adjusting the effective length of the sheath. This basic configuration can preferably be provided with any one or more of the features described elsewhere herein, in particular with those of the examples described hereafter. However, it should be understood that the basic configuration can preferably also be provided with any one or more of the features shown in the figures and / or described in conjunction with the figures, either in addition to or alternatively to the features of the examples described hereafter.

[0010] In some implementations, the techniques described herein relate to an introducer sheath assembly including: an introducer sheath for deploying a medical device, a spacer adjacent a proximal end of the introducer sheath, wherein the spacer defines an effective spacer length (Ls) corresponding to a decrease in an effective length (Leff) of the introducer sheath.

[0011] In some implementations, the techniques described herein relate to an introducer sheath assembly including: an introducer sheath for deploying a medical device, the introducer sheath having a distal end and a proximal end with a central lumen extending therebetween.

[0012] In some implementations, the introducer sheath assembly includes a spacer adjacent a proximal end of the introducer sheath, the spacer having a spacer body extending between a distal surface and an opposite proximal surface.

[0013] In some implementations, the spacer extends around at least a portion of a circumference of the introducer sheath.

[0014] In some implementations, the spacer body defines an effective spacer length (Ls) corresponding to a decrease in an effective length (Leff) of the introducer sheath.

[0015] In some implementations, at least a portion of the introducer sheath is configured to locally expand from an unexpanded configuration in the which the central lumen has a first diameter to an expanded configuration in which the central lumen has a second diameter that is larger than the first diameter, and then locally contract at least partially back to the unexpanded configuration.

[0016] In some implementations, the techniques described herein relate to a method for controlling an effective length of an introducer sheath, the method including: providing anintroducer sheath including a central lumen extending therethrough, at least a portion of the sheath is configured to locally expand from an unexpanded configuration in the which the central lumen has a first diameter to an expanded configuration in which the central lumen has a second diameter that is larger than the first diameter, and then locally contract at least partially back to the unexpanded configuration; and advancing a spacer onto the introducer sheath to a location adjacent a proximal end of the introducer sheath, the spacer having a spacer body extending between a distal surface and an opposite proximal surface, wherein the spacer extends around an entire circumference of the introducer sheath, the spacer body defining a spacer length (Ls), wherein the introducer sheath has an initial effective length (Leff) measured between the proximal end and a distal end of the introducer sheath, wherein positioning the spacer on the introducer sheath at the location adjacent the proximal end of the introducer sheath results in a corresponding decrease in the initial effective length (Leff) of the introducer sheath to a decreased effective length (Ldec), the difference between the initial effective length (Leff) and the decreased effective length (Ldec) corresponds to the spacer length (Ls).

[0017] In some implementations, the techniques described herein relate to a method for controlling an effective length of an introducer sheath, the method including: providing an introducer sheath including a central lumen extending therethrough, at least a portion of the sheath is configured to locally expand from an unexpanded configuration in the which the central lumen has a first diameter to an expanded configuration in which the central lumen has a second diameter that is larger than the first diameter, and then locally contract at least partially back to the unexpanded configuration; and coupling a spacer to the introducer sheath at a location adjacent a proximal end of the introducer sheath, the spacer having a body extending between a distal surface and an opposite proximal surface, wherein the spacer extends around a portion of a circumference of the introducer sheath, the spacer body defining a spacer length (Ls); wherein the introducer sheath as an initial effective length (Leff) measured between the proximal end and a distal end of the introducer sheath, wherein positioning the spacer on the introducer sheath at the location adjacent the proximal end of the introducer sheath results in a corresponding decrease in the initial effective length (Leff) of the introducer sheath to a decreased effective length (Ldec), the difference between the initial effective length (Leff) and the decreased effective length (Ldec) corresponds to the spacer length (Ls).

[0018] In some implementations, the techniques described herein relate to a method of delivering a medical device into a blood vessel of a patient, including: inserting an introducer sheath at least partially into the blood vessel of the patient, the sheath including a central lumen extending therethrough, at least a portion of the sheath is configured to locally expand from an unexpanded configuration in the which the central lumen has a first diameter to an expanded configuration in which the central lumen has a second diameter that is larger than the first diameter, and then locally contract at least partially back to the unexpanded configuration; advancing a distal end of the introducer sheath to a first location proximate a treatment site; positioning a spacer onto the introducer sheath at a location, the spacer defining a lumen between a distal surface and a proximal surface opposite the distal surface, the spacer extending around at least a portion of a circumference of the introducer sheath, the spacer defining a spacer length (Ls); advancing the distal end of the introducer sheath toward the treatment the treatment site until the distal surface of the spacer abuts a surface of a patient's skin; advancing a medical device through the central lumen of the introducer sheath to the treatment site within the blood vessel; and delivering the medical device to the treatment site; wherein the introducer sheath has an initial effective length (Lett) measured between the proximal end and a distal end of the introducer sheath, wherein positioning the spacer on the introducer sheath results in a corresponding decrease in the initial effective length (Leff) of the introducer sheath to a decreased effective length (Ldec), a difference between the initial effective length (Leff) and the decreased effective length (Ldec) corresponds to the spacer length (Ls).

[0019] Various aspects of the examples described above can be combined based on desired sheath system characteristics.BRIEF DESCRIPTION OF DRAWINGS

[0020] FIG. 1 is a side view of an exemplary delivery apparatus for a cardiovascular prosthetic device.

[0021] FIG. 2 is a side view of an exemplary introducer device assembly.

[0022] FIG. 3 is a side view of an expandable sheath that can be used in combination with the introducer device assembly of FIG. 2.

[0023] FIG. 4 is a side cross-sectional view of a portion of the expandable sheath of FIG. 3.

[0024] FIG. 5 is a magnified side view of a portion of the expandable sheath of FIG. 3.

[0025] 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.

[0026] FIG. 6B is a magnified side view of a portion of the braided layer of the sheath of FIG. 3.

[0027] FIG. 7 is a magnified side view of a portion of the expandable sheath of FIG. 3 illustrating expansion of the sheath as a prosthetic device is advanced through the sheath.

[0028] FIG. 8 is a sheath assembly according to another example.

[0029] FIG. 9 is a partial exploded view of the sheath assembly of FIG. 8.

[0030] FIG. 10 is a side cross-sectional view of the sheath assembly of FIG. 8.

[0031] FIG. 11 is a partial exploded view of the sheath assembly of FIG. 8 including additional spacers.

[0032] FIG. 12 is an end view of an example spacer.

[0033] FIG. 13 is an end view of an example spacer.

[0034] FIG. 14A is a side perspective view of an example spacer.

[0035] FIG. 14B is an end view of the spacer of FIG. 14A.

[0036] FIG. 14C is a side perspective view of an example spacer.

[0037] FIG. 14D is an end view of the spacer of FIG. 14C.

[0038] FIG. 14E is a side perspective view of the example spacers of FIGS. 14A-14D.

[0039] FIG. 15 is a side perspective view of an example spacer.

[0040] FIG. 16 provides a schematic representation of the example sheath assembly of FIG. 8 in use.

[0041] FIG. 17 provides a schematic representation of the example sheath assembly of FIG. 8 in use.

[0042] In the drawings, like reference numbers and designations in the various drawings indicate like elements.DETAILED DESCRIPTION

[0043] 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, allwithout departing from the spirit of the inventive concepts. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not restrictive.

[0044] For purposes of this description, certain aspects, advantages, and novel features of the aspects of this disclosure are described herein. The described methods, systems, and apparatus should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed aspects, alone and in various combinations and sub-combinations with one another. The disclosed methods, systems, and apparatus are not limited to any specific aspect, feature, or combination thereof, nor do the disclosed methods, systems, and apparatus require that any one or more specific advantages be present or problems be solved.

[0045] 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.

[0046] 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.

[0047] 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 beexpressed 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.

[0048] "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.

[0049] 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.

[0050] “Axially” or “axial” as used herein refers to a direction along the longitudinal axis of the sheath.

[0051] 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.

[0052] The expandable introducer sheaths and related componentry described herein can be used to deliver a prosthetic device through a patient’s vasculature to a procedure site within the body. The sheath can be constructed to be highly expandable and radially collapsible. Disclosed aspects of the expandable sheath can minimize trauma to the vessel by reducing push forces required to advance the sheath through the blood vessel, and / or reducing push forces required to advance a medical device and / or delivery system through the sheath. In some implementations, the expandable sheath can minimize trauma to the vessel by allowing for temporary expansion of a portion of the introducer sheath to accommodate a delivery system, followed by a return to an original diameter once the device passes therethrough.

[0053] 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 EndovascularDelivery Device into a Body,” U.S. Patent No. 10,639, 152, entitled “Expandable Sheath and Methods of Using the Same,” U.S. Patent No. 10,792,471, entitled “Expandable Sheath,” U.S. Patent No. Application No. 16 / 407,057, entitled “Expandable Sheath with Elastomeric Cross Sectional Portions,” U.S. Patent No. 10,327,896, entitled “Expandable Sheath with Elastomeric Cross Sectional Portions,” U.S. Patent No. 11,273,062, entitled “Expandable Sheath,” Application No. PCT / US2021 / 019514, entitled “Expandable sheath for introducing an endovascular delivery device in to a body,” Application No. PCT / US2021 / 031227, entitled “Expandable sheath for introducing an endovascular delivery device into a body,” Application No. PCT / US2021 / 031275, entitled “Expandable sheath for introducing an endovascular delivery device into a body,” U.S. Application No. 17 / 113,268, entitled “Expandable Sheath and Method of Using the Same,” Application No. PCT / US2021 / 058247, entitled “Self-Expanding, 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.

[0054] FIG. 1 illustrates an exemplary sheath 212 in use with a representative delivery apparatus 100, such as a prosthetic heart valve or other prosthetic implant, to a patient. The delivery apparatus 100 illustrated can generally include a steerable guide catheter 104 and a balloon catheter 160 extending through the guide catheter 104. A prosthetic device, such as a prosthetic heart valve (prosthetic device 102), can be positioned on the distal end of the balloon catheter 160. The guide catheter 104 and the balloon catheter 160 can be adapted to slide longitudinally relative to each other to facilitate delivery and positioning of a prosthetic heart valve (prosthetic device 102) at an implantation site in a patient's body.

[0055] As described in more detail herein, the sheath 212 is an elongated, expandable tube that is inserted into a vessel (for example, transfcmoral vessel, femoral artery, iliac artery) by passing through the skin of patient, such that the distal end of the sheath 212 is inserted into the vessel. The sheath 212 includes a hemostasis valve and / or sealing features at the proximal end of the sheath 212, for example, in the sheath hub 204, that provide hemostasis and prevents blood leakage from the patient through the sheath 212. During the treatment procedure, the sheath 212, including an introducer 240, is advanced into the patient’s vasculature. Once positioned the introducer 240 is removed and the guide catheter 104 is inserted into / through the sheath 212, and the prosthetic heart valve (prosthetic device 102) then be delivered and implanted within patient. The guide catheter 104 includes a handle portion 108 and an elongated guide tube or shaft extending from the handle portion 108.

[0056] The prosthetic heart valve (prosthetic device 102) can be delivered into a patient’s body in a radially compressed configuration and radially expanded to a radially expanded configuration at the desired deployment site. In the illustrated example, the prosthetic heart valve (prosthetic device 102) 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 160 (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 balloon-expandable expandable heart valve that can be implanted using the devices disclosed herein are disclosed in U.S. Patent No. 5,411,552, and also in U.S. Patent No. 9,393,110, both of which are incorporated herein by reference. Further details regarding a plastically expandable heart valve that can be implanted using the devices disclosed herein are disclosed in U.S. Publication No. 2012 / 0123529, which is incorporated herein by reference. The expandable introducer sheaths disclosed herein may also be used to deliver other types of implantable medical device, such as self-expanding and mechanically expanding implantable heart valves, stents or filters. For example, the prosthetic heart valve (prosthetic device 102) can be a self-expandable heart valve that is restrained in a radially compressed configuration by a sheath or other component of the delivery apparatus and self-expands to a radially expanded configuration when released by the sheath or other component of the delivery apparatus. Further details regarding a self-expandable heart valve that can be implanted using the devices disclosed herein are disclosed in U.S. Publication No.2012 / 0239142, which is incorporated herein by reference. In still some examples, the prosthetic heart valve (prosthetic device 102) 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 still some examples, a prosthetic valve can incorporate two or more of the above-described technologies. For example, a self-expandable heart valve can be used in combination with an expansion device to assist expansion of the prosthetic heart valve.

[0057] Beyond transcatheter heart valves, the introducer sheath system can be useful for other types of minimally invasive surgery, such as any surgery requiring introduction of an apparatus into a subject’s vessel. For example, the introducer sheath system can be used to introduce other types of delivery apparatus for placing various types of intraluminal devices (for example, stents, stented grafts, balloon catheters for angioplasty procedures, etc.) into many types of vascular and non-vascular body lumens (for example, veins, arteries, esophagus, ducts of the biliary tree, intestine, urethra, fallopian tube, other endocrine or exocrine ducts, etc.). The term “implantable” as used herein is broadly defined to mean anything - prosthetic or not - that is delivered to a site within a body. A diagnostic device, for example, may be an implantable.

[0058] FIG. 2 illustrates an example of an introducer device assembly 200. The assembly 200 may include the sheath 212 and an introducer 240. The introducer 240 may be positioned within a central lumen 214 (indicated in FIG. 4) of the sheath 212, as shown in FIG. 2. An optional control housing 202 may be positioned at a proximal end of the assembly and may include a sheath hub 204 and an introducer hub 210. The sheath hub 204 and introducer hub 210 may optionally couple together, as shown in FIG. 2.

[0059] The sheath 212 and introducer 240 are shown in an insertion configuration, for insertion together into the patient’s vasculature. Upon insertion into the patient’s vasculature, the introducer 240 may be withdrawn longitudinally from the sheath 212, leaving the sheath 212 within the patient’s vasculature. Features of the sheath 212 and the introducer 240 individually are discussed below, as well as the operation of the sheath 212 and introducer 240 together.

[0060] The sheath 212 comprises an elongated body that may have a cylindrical shape. The sheath 212 has a distal end 213 and a proximal end 216, and a length LI (sec FIG. 3) extending from the distal end 213 to the proximal end 216. The sheath 212 is configured to be inserted into a patient's vasculature. The sheath 212 may optionally comprise an introducer sheath that is used to introduce a delivery apparatus into the patient's vasculature.

[0061] The vasculature may comprise the blood vessels of the patient's body which may include the femoral artery or other vessels of the patient's body. The vasculature, such as the femoral artery, may be narrow or stiff, and may be difficult to easily insert a delivery apparatus 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.

[0062] The sheath 212 accordingly may optionally be inserted into the patient’s vasculature prior to the delivery apparatus 100 being introduced, to provide an entry way or guide path for the delivery apparatus 100 to introduce the delivery apparatus 100 into the patient’s vasculature. After the sheath 212 is inserted, the sheath 212 may remain positioned within and surrounded by the patient’s vasculature. The delivery apparatus 100 may then be passed through the lumen of the sheath 212 for introduction into the patient’s body. The sheath 212 may remain in the vasculature until a desired time to remove the sheath 212.

[0063] The sheath 212 may be inserted into the vasculature percutaneously or a portion of the patient’s body may be surgically opened for the sheath 212 to access the vasculature. The delivery apparatus 100 passes through the lumen of the sheath 212 to reach a desired position in the patient's body. As shown in FIG. 1, the delivery apparatus 100 may pass through an opening at the proximal end of the sheath 212 for passage through the central lumen 214 of the sheath 212 and the vasculature of the patient. For example, in some implementations, the delivery apparatus 100 passes through an opening at the proximal end of the sheath 212 provided at the control housing 202 shown in FIG. 2.

[0064] 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.

[0065] The sheath 212 may optionally include a strain relief portion 218 at the proximal end 216 of the sheath 212. The strain relief portion 218 may be sized larger than a proximate portion of the sheath 212 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 212 and the vasculature. The strain relief portion 218 provides a transition between the larger diameter proximal opening of the sheath 212 and the smaller diameter distal portion / opening of the sheath 212 as the medical device and / or introducer 240 are inserted into the central lumen 214 of the sheath 212.In some examples, a seal 220 is optionally positioned along the length of the sheath 212 to further prevent blood or other fluid flow from passing around the sheath 212 toward and out of the proximal end 216 of the sheath 212.

[0066] FIG. 3 illustrates a side view of an exemplary expandable sheath 212 that can be used in the introducer device assembly of FIG. 2. As shown in FIG. 3, the sheath hub 204 is optionally positioned at the proximal end 216 of the sheath 212. The sheath hub 204 may optionally include an internal chamber for the delivery apparatus 100 to be passed through to be delivered to the patient's vasculature. The sheath hub 204 may be configured to remain external to the patient's vasculature when the sheath 212 is inserted therein and may be configured to remain external to the patient's skin for a percutaneous implantation of the sheath 212. The sheath hub 204 may be configured for a user (such as a surgeon) to grip to manipulate the sheath 212.

[0067] The sheath hub 204 may optionally comprise a cylindrical body and may include a coupling feature for coupling the sheath hub 204 to another housing or component of the sheath system. The sheath hub 204 may optionally include a fluid port 206 for passing fluid such as blood to or from the patient's vasculature. Tubing 207 with a valve 208 may be coupled to the fluid port 206, for passing fluid through the fluid port 206 and for sealing flow of the fluid through the fluid port 206.

[0068] In some examples, the introducer sheath 212 need not include a sheath hub 204. For example, the sheath 212 can be an integral part of a component of the delivery apparatus 100, such as the guide catheter. For example, the sheath 212 can extend from the handle portion 108 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.

[0069] FIGS. 4 and 5 illustrate a cross-sectional view and a side view, respectively, of a portion of the expandable sheath 212. As shown in FIG. 5, the sheath 212 can have a natural,unexpanded outer diameter DI . Tn certain examples, the expandable sheath 212 may optionally include a plurality of co-axial layers extending along at least a portion of the length LI of the sheath (FIG. 3). For example, with reference to FIG. 4, the expandable sheath 212 can include a first layer / inner layer 222 (also referred to as an inner layer), a second layer / braided layer 224 disposed around and radially outward of the inner layer 222, a third layer / elastic layer 226 disposed around and radially outward of the braided layer 224, and a fourth layer / outer layer 228 (also referred to as an outer layer) disposed around and radially outward of the elastic layer 226. In the illustrated configuration, the inner layer 222 can define the central lumen 214 extending along a central axis Cl. In some examples, the sheath 212 may optionally include the inner layer 222 without the outer layer 228, or the outer layer 228 without the inner layer 222, depending upon the particular characteristics desired.

[0070] Referring to FIG. 5, when the sheath 212 is in an unexpanded state, the inner layer 222 and / or the outer layer 228 can form longitudinally-extending folds or creases such that the surface of the sheath comprises a plurality of ridges 232 (also referred to herein as “folds”). The ridges 232 can be circumferentially spaced apart from each other by longitudinally-extending valleys 234. When the sheath 212 expands beyond its natural diameter DI, the ridges 232 and the valleys 234 can level out or be taken up as the surface radially expands and the circumference increases, as further described below. When the sheath 212 collapses back to its natural diameter, the ridges 232 and valleys 234 can reform.

[0071] In some examples, the inner layer 222 and / or the outer layer 228 can comprise a relatively thin layer of polymeric material. For example, in some examples, the thickness of the inner layer 222 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 228 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.

[0072] In some examples, the inner layer 222 and / or the outer layer 228 can comprise a lubricious, low-friction, and / or relatively non-elastic material. In some examples, the inner layer 222 and / or the outer layer 228 can comprise a polymeric material having a modulus of elasticity of 400 MPa or greater. Exemplary materials can include ultra-high-molecular- weight polyethylene (UHMWPE) (for example, Dyneema®), high-molecular- weight polyethylene (HMWPE), or polyether ether ketone (PEEK). With regard to the inner layer 222 in particular, a low coefficient of friction materials can facilitate passage of the prosthetic device through thecentral lumen 214. Other suitable materials for the inner and outer layers can include polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (cPTFE), ethylene tetrafluoroethylene (ETFE), nylon, polyethylene, polyether block amide (for example, Pebax), and / or combinations of any of the above. Some examples of the sheath 212 can include a lubricious liner on the inner surface of the inner layer 222. Examples of suitable lubricious liners include materials that can further reduce the coefficient of friction of the inner layer 222, 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.

[0073] Additionally, some examples of the sheath 212 can include an optional exterior hydrophilic coating on the outer surface of the outer layer 228. Such a hydrophilic coating can facilitate insertion of the sheath 212 into a patient’s vessel, reducing potential damage. Examples of suitable hydrophilic coatings include the Harmony™ Advanced Lubricity Coatings and other Advanced Hydrophilic Coatings available from SurModics, Inc., Eden Prairie, MN. DSM medical coatings (available from Koninklijke DSM N.V, Heerlen, the Netherlands), as well as other hydrophilic coatings (for example, PTFE, polyethylene, polyvinylidene fluoride), are also suitable for use with the sheath 212. Such hydrophilic coatings may also be optionally included on the inner surface of the inner layer 222 to reduce friction between the sheath 212 and the delivery apparatus 100, 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 228 or the inner surface of the inner layer 222 in order to reduce friction.

[0074] In certain examples, the second layer / braided layer 224 can includes a braided material. FIGS. 6 A and 6B illustrate the sheath 212 with the outer layer 228 removed to expose the elastic layer 226. With reference to FIGS. 6A and 6B, the braided layer 224 can comprise a plurality of members or filaments 230 (for example, metallic or synthetic wires or fibers) braided together. The braided layer 224 can have any desired number of filaments 230, which can be oriented and braided together along any suitable number of axes. For example, with reference to FIG. 6B, the filaments 230 can include a first set of filaments 230A oriented parallel to a first axis A, and a second set of filaments 230B oriented parallel to a second axis B . The filaments 230A and 230B can be braided together in a biaxial braid such that filaments 230A oriented along axis A form an angle 0 with the filaments 230B oriented along axis B. In certain examples, the angle 0 can befrom 5° to 70°, 10° to 60°, 10° to 50°, or 10° to 45°. In the illustrated example, the angle 0 is 45°. In some examples, the filaments 230 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.

[0075] The braided layer 224 can extend along substantially the entire length LI of the sheath 212, or alternatively, can extend only along a portion of the length of the sheath 212. In some examples, the filaments 230 can be wires made from metal (for example, Nitinol, stainless steel, etc.), or any of various polymers or polymer composite materials, such as carbon fiber. In some examples, the filaments 230 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 230 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 230 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 224 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 224 can also be woven or knitted, as desired.

[0076] The third layer / elastic layer 226 can be a resilient, elastic layer (also referred to as an elastic material layer). In certain examples, the elastic layer 226 can be configured to apply force to the underlying inner layer 222 and braided layer 224 in a radial direction (for example, toward the central axis Cl of the sheath) when the sheath 212 expands beyond its natural diameter by passage of the delivery apparatus through the sheath 212. Stated differently, the elastic layer 226 can be configured to apply encircling pressure to the layers of the sheath 212 beneath the elastic layer 226 to counteract expansion of the sheath 212. The radially inwardly directed force is sufficient to cause the sheath 212 to collapse radially back to its unexpanded state after the delivery apparatus is passed through the sheath 212.

[0077] In the illustrated example, the elastic layer 226 can optionally comprise one or more members configured as strands, ribbons, or bands 236 helically wrapped around the braided layer 224. For example, in the illustrated sheath 212, the elastic layer 226 comprises two elastic bands 236 elastic bands 236A and 236B wrapped around the braided layer 224 with opposite helicity,although the elastic layer 226 may comprise any number of bands depending upon the desired characteristics. The clastic bands 236A and 236B 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.

[0078] In some examples, the elastic layer 226 can comprise an elastomeric material having a modulus of elasticity of 200 MPa or less. In some examples, the elastic layer 226 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 226 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 226, the sheath 212 may also include an optional elastomeric or heat-shrink tubing layer around the outer layer 228. 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 226 can also be radially outward of the polymeric outer layer 228.

[0079] In some examples, one or both of the inner layer 222 and / or the outer layer 228 can be configured to resist axial shortening of the sheath 212 when the sheath expands radially. More particularly, one or both of the inner layer 222 and / or the outer layer 228 can resist stretching against longitudinal forces caused by friction between a prosthetic device 102 and the inner surface of the sheath 212 such that the length LI remains substantially constant as the sheath 212 expands and contracts radially. As used herein with reference to the length LI of the sheath 212, the term “substantially constant” means that the length LI of the sheath increases by not more than 1%, by not more than 5%, by not more than 10%, by not more than 15%, or by not more than 20%. Meanwhile, with reference to FIG. 6B, the filaments 230A and 230B of the braided layer 224 can be allowed to move angularly relative to each other such that the angle 0 changes as the sheath 212 expands and contracts. This, in combination with the longitudinal ridges 232 (folds) in the inner layer 222 and outer layer 228, can allow the central lumen 214 to expand as a prosthetic device is advanced through it.

[0080] In some examples, the inner layer 222 and the outer layer 228 can be heat-bonded during the manufacturing process such that the braided layer 224 and the elastic layer 226 areencapsulated between the inner layer 222 and the outer layer 228. More specifically, in certain examples, the inner layer 222 and the outer layer 228 can be adhered to each other through the spaces between the filaments 230 of the braided layer 224 and / or the spaces between the elastic bands 236. The inner layer 222 and outer layer 228 can also be bonded or adhered together at the proximal and / or distal ends of the sheath 212. In certain examples, the inner layer 222 and outer layer 228 are not adhered to the filaments 230. This can allow the filaments 230 to move angularly relative to each other, and relative to the inner layer 222 and outer layer 228, allowing the diameter of the braided layer 224, and thereby the diameter of the sheath 212, to increase or decrease. As the angle 9 between the filaments 230A and 230B changes, the length of the braided layer 224 can also change. For example, as the angle 0 increases, the braided layer 224 can foreshorten, and as the angle 9 decreases, the braided layer 224 can lengthen to the extent permitted by the areas where the inner layer 222 and outer layer 228 are bonded. However, because the braided layer 224 is not adhered to the inner layer 222 and outer layer 228, the change in length of the braided layer 224 that accompanies a change in the angle 9 between the filaments 230 A and 230B does not result in a significant change in the length LI of the sheath 212.

[0081] FIG. 7 illustrates radial expansion of the sheath 212 as a prosthetic device 102 is passed through the sheath 212 in the direction of arrow 245 (for example, distally). As the prosthetic device 102 is advanced through the sheath 212, the sheath 212 can resiliently expand to a second diameter D2 that corresponds to a size or diameter of the prosthetic device 102. As the prosthetic device 102 is advanced through the sheath 212, the prosthetic device 102 can apply longitudinal force to the sheath 212 in the direction of motion by virtue of the frictional contact between the prosthetic device 102 and the inner surface of the sheath 212. However, as noted herein, in some implementations, the inner layer 222 and / or the outer layer 228 can be optionally configured to resist axial elongation such that the length LI of the sheath 212 remains constant, or substantially constant. This can reduce or prevent the braided layer 224 from lengthening, and thereby constricting the central lumen 214.

[0082] Meanwhile, in some examples, the angle 0 between the filaments 230A and 230B can increase as the sheath 212 expands to the second diameter D2 to accommodate the prosthetic device 102. This can cause the braided layer 224 to foreshorten. However, because the filaments 230 are not engaged or adhered to the inner layer 222 or outer layer 228, the shortening of thebraided layer 224 attendant to an increase in the angle 0 does not affect the overall length LI of the sheath 212. Moreover, because of the longitudinally-extending ridges 232 (folds) formed in the inner layer 222 and outer layer 228, the inner layer 222 and outer layer 228 can expand to the second diameter D2 without rupturing, in spite of being relatively thin and relatively non-elastic. In this manner, the sheath 212 can resiliency expand from its natural diameter DI to a second diameter D2 that is larger than the diameter DI as a prosthetic device 102 is advanced through the sheath 212, without lengthening, and without constricting. Thus, the force required to push the prosthetic device 102 through the sheath 212 is significantly reduced.

[0083] Additionally, because of the radial force applied by the elastic layer 226, the radial expansion of the sheath 212 can be localized to the specific portion of the sheath 212 occupied by the prosthetic device 102. For example, with reference to FIG. 7, as the prosthetic device 102 moves distally through the sheath 212, the portion of the sheath 212 immediately proximal to the prosthetic device 102 can radially collapse back to the initial diameter DI under the influence of the elastic layer 226. The inner layer 222 and outer layer 228 can also buckle as the circumference of the sheath 212 is reduced, causing the ridges 232 and the valleys 234 to reform. This can reduce the size of the sheath 212 required to introduce a prosthetic device 102 of a given size. Additionally, the temporary, localized nature of the expansion can reduce trauma to the blood vessel into which the sheath 212 is inserted, along with the surrounding tissue, because only the portion of the sheath 212 occupied by the prosthetic device 102 expands beyond the sheath’s natural diameter and the sheath 212 collapses back to the initial diameter once the device has passed. This limits the amount of tissue stretched in order to introduce the prosthetic device 102, and the amount of time for which a given portion of the vessel is dilated to allow the prosthetic device 102 to pass.

[0084] In addition to the advantages above, the expandable sheath 212 examples described herein can provide surprisingly superior performance relative to known introducer sheaths. For example, it is possible to use a sheath 212 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 212. For instance, in one example, a crimped prosthetic heart valve having a diameter of 7.2 mm was successfully advanced through a sheath configured as described above and having a natural outer diameter of 3.7 mm. As the prosthetic valve was advanced through the sheath 212, the outer diameter of the portion of the sheath 212 occupied bythe 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 212 through the sheath 212, during which the outer diameter of the sheath 212 resiliently increased by 216%. In another example, a sheath 212 with an initial or natural outer diameter of 4.5 mm to 5.0 mm can be configured to expand to an outer diameter of 8 mm to 9 mm.

[0085] FIG. 8 is a side view of an example sheath assembly 300 that includes at least one spacer 350 that allows the effective length of the sheath to be customized to accommodate variations in patient anatomy while also ensuring hemostasis at the treatment site. FIG. 9 provides an exploded view of the sheath assembly 300 of FIG. 8, and FIG. 10 provides a partial side cross- sectional view of the sheath assembly 300.

[0086] As illustrated in FIG. 8, the sheath assembly 300 includes an introducer sheath 312 and a spacer 350 provided on the sheath 312 for adjusting the effective length (Leff) of the sheath 312, where the effective length (Leff) of the sheath 312 corresponds to the length of the sheath 312 sized and configured to be inserted into the patient.

[0087] It is contemplated that the sheath 312 of the present sheath assembly 300 can include the layered sheath 212 described herein in reference FIGS. 4-7, and / or any other sheath structure disclosed herein. As illustrated in FIG. 8, the proximal end 316 of the sheath 312 is coupled to the sheath hub 304. The central lumen 314 of the sheath 312 extends between the proximal end 316 and the distal end 313 of the sheath 312 and is axially aligned with the central lumen of the sheath hub 304. As described herein, at least a portion of the sheath 312 is configured to locally expand from an unexpanded configuration in the which the central lumen 314 has a first diameter to an expanded configuration in which the central lumen 314 has a second diameter that is larger than the first diameter. The sheath 312 is configured to then locally contract at least partially back to the unexpanded configuration.

[0088] As illustrated in FIGS. 8-10, the sheath assembly 300 includes a spacer 350 provided on the sheath 312 for adjusting the effective length (Leff) of the sheath 312. As described herein, the effective length (Leff) of the sheath 312 corresponds to the length of the sheath 312 sized and configured to be inserted into the patient. For example, in systems not including a spacer 350, the effective length (Leff) of the sheath 312 is measured between the distal end 313 of the sheath 312 and the sheath hub 304 / locking nut 305.

[0089] By coupling the spacer 350 (and / or multiple spacers 350) to the sheath assembly 300, the user is able to adjust the effective length (Leff) of the sheath 312 and provide a sheath 312 customizable to accommodate variations in patient anatomy. For example, the effective length (Leff) of the sheath 312 can be adjusted to accommodate variations in the thickness of the fat, skin and tissue layers between the surface of the patient’s skin and the opening in the vasculature. As illustrated in FIGS. 8 and 10, when assembled, the spacer 350 is located adjacent to the proximal end 316 of the sheath 312 and / or adjacent the sheath hub 304 / locking nut 305 when included. In use, as described herein, the spacer 350 forms the contact surface between the sheath assembly 300 and the patient’s skin, preventing further movement of the sheath 312 within the vasculature. As such, the effective length (Leff) of the sheath 312 is measured between the distal end surface 354 of the spacer 350 and the distal end 313 of the sheath 312.

[0090] In some implementations, the sheath 312 is coupled to the sheath hub 304 via a locking nut 305. As illustrated in FIG. 10, sheath 312 is positioned between the sheath hub 304 and the locking nut 305 such that coupling the locking nut 305 to the sheath hub 304 fixes the sheath 312 to the sheath hub 304. In some implementations, the sheath 312 is received within the central lumen of the locking nut 305 and over a proximal end of the sheath hub 304 such that coupling the locking nut 305 to the sheath hub 304 couples the sheath 312 to the sheath hub 304, for example, by compression of the sheath 312 against the sheath hub 304 when tightening the locking nut 305. As provided in FIG. 10, in some implementations, the sheath hub 304 includes a threaded outer surface for coupling with a corresponding threaded inner surface on the locking nut 305. As illustrated in FIG. 10, in some implementations, the sheath hub 304 includes a distally tapering shoulder that extends distally beyond the threaded surface. The shoulder has a size and shape corresponding to portions of the central lumen of the locking nut 305 and provides a support surface for the sheath 312 when compressed against the central lumen of the locking nut 305.

[0091] As illustrated in FIGS. 8 and 10, when assembled, the spacer 350 is located adjacent the distal end of the locking nut 305. In some implementations, when assembled, the proximal surface 356 of the spacer 350 abuts the locking nut 305. In some implementations, the central lumen 353 of the spacer 350 and / or the proximal surface 356 of the spacer 350 includes a mating feature sized and configured to engage a corresponding portion of the sheath hub 304 / locking nut 305. As such, the sheath hub 304 / locking nut 305 is aligned with and / or coupled to the spacer350, helping to align the central lumen 353 of the spacer 350 with the central lumen of the sheath hub 304 / locking nut 305. In some implementations, the mating feature fixes the rotational and / or axial position of the spacer 350 with respect to the sheath hub 304 / locking nut 305.

[0092] As illustrated in FIG. 10, the spacer body 352 defines an effective spacer length (Ls). When provided on the sheath 312, the spacer length (Ls) of the spacer 350 shortens the length of the sheath 312 available for insertion into the patient. That is, when the spacer 350 is provided on the sheath 312, the spacer length (Ls) corresponds to a decrease in the initial effective length (Leff) of the sheath 312.

[0093] In some implementations, as illustrated FIG. 11, the sheath assembly 300 includes an additional spacer 370 (and / or spacers 370) for further adjusting / decreasing the effective length (Leff) of the sheath 312. FIG. 11 provides an exploded view of the sheath assembly 300 including two additional spacers 370 (first additional spacer 370A and second additional spacer 370B). As illustrated in FIG. 11, the spacer length (Ls) can vary between the spacer 350 and the additional spacer 370. It is contemplated that the sheath assembly 300 can a single spacer 350, or a spacer 350 and any number of additional spacers 370 for adjusting the effective length (Lcff) of the sheath 312 to a desired effective length (Left).

[0094] FIG. 11 illustrates an example sheath assembly 300 including a spacer 350 and two additional spacers 370. In some implementations, the additional spacers 370 are located along the sheath 312 distal to the spacer 350. As provided in FIG. 11, in some implementations, the spacer 350 axially located along the sheath 312 between the sheath hub 304 and the additional spacers 370 / first additional spacer 370A. As illustrated in FIG. 11, the first additional spacer 370A is provided axially along the sheath 312 distal to the spacer 350 at a position adjacent the spacer 350, and the second additional spacer 370B is provided axially along the sheath 312 distal to the first additional spacer 370A at a position adjacent the first additional spacer 370A. As provided in FIG. 11, in some implementations, the first additional spacer 370A is positioned abutting the distal end surface 354 of the spacer 350, and the second additional spacer 370B positioned adjacent the distal end surface of the first additional spacer 370A.

[0095] Where the sheath assembly 300 includes multiple spacers (spacer 350 and / or additional spacer(s) 370), the combined spacer length of each of the spacers defines the combined effective spacer length (Ltotai). For example, as illustrated in FIG. 11, the spacer length (Ls) of the spacer 350 is combined with the spacer length (Ls’) of the first additional spacer 370A and the spacerlength (Ls’) of the second additional spacer 370B to determine the combined effective spacer length (L total)-

[0096] In some implementations, the spacer 350 and additional spacer(s) 370 have the same spacer length. In some implementations, the spacer length (Ls) of the spacer 350 is different from the spacer length (Ls’) of the additional spacer(s) 370. In some implementations, the spacer length varies between each of the additional spacers 370 and the spacer 350. In some implementations, as illustrated in FIG. 11, where the sheath assembly 300 includes at least two additional spacers 370, the spacer length (Ls) of the spacer 350 can be different from the spacer length (Ls’) of either of the additional spacers 370 (first additional spacer 370A and / or second additional spacer 370B).

[0097] As illustrated in FIGS. 8-10, in general, the spacer 350 has a generally annular shaped spacer body 352 having a central lumen 353 extending between the proximal surface 356 and the opposing distal surface 354 of the spacer 350. Similarly, the additional spacer(s) 370 can define a generally annular shaped spacer body 372 having a central lumen 373 extending between the proximal surface 376 and the opposing distal surface 374 of the additional spacer(s) 370. That is, in some implementations, the spacer body 352 of the spacer 350, and / or body portion 372 of the additional spacer 370, extends around the entire circumference of the introducer sheath 312 when assembled. Because the spacer body 352 extends around the entire circumference of the spacer 350, the spacer 350 is loaded onto the sheath 312 by advancing the sheath 312 within the central lumen 353 of the spacer 350. For example, the proximal end 316 or distal end 313 of the sheath 312 can be advanced into the central lumen 353 of the spacer 350 until the spacer 350 is located at the desired position along the sheath 312. For example, the spacer 350 can be advanced along the sheath 312 to a location adjacent to the proximal end 316 of the sheath 312 and abuts the sheath hub 304 / locking nut 305.

[0098] In some implementations, the spacer body 352 of the spacer 350, and / or spacer body 372 of the additional spacer 370, extends around a portion of the circumference of the introducer sheath 312. For example, in some implementations as illustrated in FIG. 12, the spacer 350 and / or additional spacer 370 includes gap 326 extending longitudinally through a side wall of the spacer 350 / additional spacer 370. In some implementations, the spacer 350 / additional spacer 370 defines an open C-shaped spacer body 352 / spacer body 372. As shown in FIG. 12, the gap 362 is formed between the opposing end surfaces of the open C-shaped spacer body 352 / spacer body372. For example, the spacer 350 / additional spacer 370 can include a first arm portion 358 and a second ami portion 360, where the gap 362 is defined between the end surfaces of the first arm portion 358 and the second arm portion 360.

[0099] In some implementations, the (circumferential) width of the gap 362 is configured to increase so the spacer 350 can be loaded onto the sheath 312. For example, the width of the gap 362 can be increased to accommodate the diameter and / or circumference of the introducer sheath 312. That is, in some implementations, the spacer 350 / additional spacer 370 can flex, bend, or otherwise elastically deform, increasing the width of the gap 362, and allowing the spacer 350 / additional spacer 370 to be advanced over the sheath 312 (for example, over the side of the sheath 312). In some implementations, the spacer 350 and / or additional spacer 370 is loaded onto the sheath 312 by flexing and / or bending the spacer to increase the width of the gap 362 so that it is greater than the outer diameter of the sheath 312, advancing the spacer 350 and / or additional spacer 370 over the sheath 312 in a direction transverse to a longitudinal axis of the sheath 312, and decreasing the width of the gap 362 to a width less than the outer diameter of the sheath 312. Because the width of the gap 362 returns to a width less than the outer diameter of the sheath 312, the spacer 350 / additional spacer 370 will not release (in a transverse direction) from the sheath 312. Moreover, as described herein, because the spacer 350 can be loaded in a transverse direction onto the sheath 312 (for example, over the side of the sheath 312), it is not necessary to fully withdraw the sheath 312 from the patient’s blood vessel when loading the spacer 350 thereon.

[0100] In some implementations, spacer 350 / additional spacer 370 are configured to elastically expand and contract between an open configuration (shown in FIG. 12, where the width of the gap 362 is greater than the width / outer diameter of the sheath 312) and closed configuration (shown in FIG. 13, where the width of the gap 362 is less than the width / outer diameter of the sheath 312.

[0101] In some implementations, the spacer 350 / additional spacer 370 are biased toward the closed configuration such that the spacer 350 / additional spacer 370 automatically return to the closed configuration after being positioned over the sheath 312. In some implementations, the spacer 350 / additional spacer 370 are not biased toward the closed configuration and an inwardly / circumferentially directed force is required to return the spacer 350 / additional spacer 370 to the closed configuration. In some implementations, as illustrated in FIG. 12, in the closedconfiguration, the first arm portion 358 and the second arm portion 360 define a continuous outer edge extending in a circumferential direction around the spacer 350 / additional spacer 370. As such, the outer diameter / surface of the spacer body defines a partially cylindrical outer surface, with a circular / curved shape in cross-section.

[0102] In some implementations, the spacer 350 / additional spacer 370 includes a hinge 363 or pivot point for moving between the open and closed configuration. FIG. 13 illustrates an example spacer 350 / additional spacer 370 including a first arm portion 358 coupled to a second arm portion 360 at a hinge 363. The first arm portion 358 and second arm portion 360 are pivotably coupled at the hinge 363 such that the first arm portion 358 and second arm portion 360 pivot toward and away from the longitudinal axis of the spacer 350 / additional spacer 370 between the open and closed configuration.

[0103] In some implementations, the spacer 350 / additional spacer 370 is movable along and / or around the outer surface of the sheath 312. For example, in some implementations, the diameter of the central lumen 353 of the spacer 350 and / or diameter of the central lumen 373 of the additional spacer 370 can be greater than that outer diameter of the sheath 312 so that the spacer 350 / additional spacer 370 is movable along and / or around the sheath 312. Moving the spacer 350 / additional spacer 370 along and / or around the sheath 312 allows the user to position the spacer adjacent the locking nut 305 / sheath hub 304.

[0104] In some implementations, as illustrated in FIG. 10, at least a portion of the inner diameter of the spacer 350 / additional spacer 370 corresponds with the outer diameter of the sheath 312. For example, in some implementations, at least a portion of the diameter of the central lumen 353 of the spacer 350 and / or the diameter of the central lumen 373 of the additional spacer 370 corresponds with or is slightly less than the outer diameter of the sheath 312. As such, when the spacer 350 / additional spacer 370 is coupled to the sheath 312, its axial and / or circumferential position along the sheath 312 is fixed. In some implementations, the diameter of the central lumen 353 of the spacer 350 / additional spacer 370 corresponds to or is slightly less than the outer diameter of the sheath 312 such that movement of the spacer 350 / additional spacer 370 along the sheath 312 is limited by interference between the central lumen 353 / central lumen 373 and the outer surface of the sheath 312.

[0105] In some implementations, the outer diameter of the spacer 350 and / or additional spacer 370 is less than the outer diameter of the sheath hub 304, ensuring that the view of the incisionsite is not inhibited. In some implementations, the outer diameter of the spacer 350 and / or additional spacer 370 is larger than the width of the incision through the patient’s skin / tissuc, preventing distal most spacer 350 and / or additional spacer 370 from inadvertently being drawn into the patient, ensuring contact between the patient’s skin and the spacer 350 / additional spacer 370 controls the length of the sheath 312 received with the patient.

[0106] In some implementations, the spacer 350 is sized and configured to couple with an adjacent spacer 350 and / or additional spacer 370. For example, in some implementations, the spacer 350 and / or additional spacer 370 includes a mating feature configured to engage with a corresponding mating feature provided on an adjacent spacer 350 / additional spacer 370. Engagement of the mating feature rotationally and / or axially fixes the adjacent spacers. In some implementations, the mating features provided on the spacer 350 / additional spacer 370 allow them to releasably couple with an adjacent spacer. For example, the mating features allow the spacers to temporarily couple with each other and then release or otherwise separate. In some implementations, the mating features fixedly couples the spacer 350 / additional spacer 370 with an adjacent spacer. That is, once coupled, the adjacent spacers remain coupled and cannot be separated without damaging the spacers. In some implementations, the mating features includes at least one of a press fit, interference fit, snap fit, keyed slot, a weld, a thermal process, and / or any other mechanical fastener, chemical fastener (for example, an adhesive), or other suitable coupling process known in the art.

[0107] FIGS. 14A-14D illustrate perspective and end views of an example spacer 350 and additional spacer 370 including a mating feature for coupling the spacers together. Coupling adjacent spacers allows the user to construct a variable length spacer for mounting on the sheath 312 to adjust the effective length of the sheath 312 before and / or while positioning the sheath 312 within the patient’s vasculature. In some implementations, coupling adjacent spacers also ensures the spacers maintain a position adjacent to each other when adjusting the effective length of the sheath 312.

[0108] In some implementations, the spacer 350 includes a shoulder for coupling with corresponding shoulder on an adjacent spacer 350 / additional spacer 370. For example, FIG. 14A provides a perspective view of an example spacer 350 including a shoulder 366 projecting from an end surface (for example, proximal surface 356) of the spacer 350 and FIG. 14C provides an end view of the spacer 350 of FIG. 14A. FIG. 14B provides a perspective view of the exampleadditional spacer 370 including a shoulder 386 projecting from the opposing end surface (for example, distal surface 374) of the additional spacer 370, and FIG. 14D provides an end view of the spacer 370 of FIG. 14B.

[0109] As illustrated in FIG. 14E, the shoulder 366 provided on the spacer 350 (FIG. 14A) is sized and configured to mate with the corresponding shoulder 386 provided on the additional spacer 370 (FIG. 14B). In some implementations, the shoulder 366 of the spacer 350 releasably couples with the shoulder 386 of the additional spacer 370. In some implementations, the shoulder 366 of the spacer 350 fixedly couples with the shoulder 386 of the additional spacer 370. The shoulder 366 provided on the spacer 350 includes a protruding region 364 and a recessed region 368, and the shoulder 386 provided on the additional spacer 370 includes a correspondingly- shaped recessed region 388 and protruding region 384. FIG. 14E illustrates the spacer 350 coupled to the additional spacer 370. As provided in FIG. 14E, the protruding region 364 of the spacer 350 is received within the recession region 388 of the additional spacer 370, and the protruding region 384 of the additional spacer 370 is received within the recessed region 368 of the spacer 350.

[0110] In some implementations, as described herein, the adjacent spacers 350 / additional spacers 370 are coupled together before being coupled to or otherwise mounted on the sheath 312. In some implementations, the adjacent spacers 350 / additional spacers 370 are coupled together after they have been separately coupled or mounted on the sheath 312. As illustrated in FIG. 14E, in some implementations, when coupled together, the central lumen 353 of the spacer 350 axially aligns with the central lumen 373 of the additional spacer 370, as such the spacer 350 and additional spacer 370 can be easily coupled to or mounted on the sheath 312 by advancing the sheath 312 into the combined central lumen 353 / central lumen 373 of the spacers.

[0111] As described herein, the sheath 312 of sheath assembly 300 can include the layered sheath 212 described herein in reference FIGS. 4-7, and any other sheath structure disclosed herein. In some implementations, the sheath 312 includes a stiff portion adjacent the proximal end of the sheath 212 for sealing the entry point into the patient’s vasculature and helping to ease the transition of the prosthetic device 102 from the sheath hub 304 and into the sheath 312. As described herein, in some implementations, the sheath 212 includes a strain relief portion 218 extending distally from the proximal end of the sheath 212. The strain relief portion 218 provides a smooth transition from the sheath hub 204 to the sheath 212 helping to couple the sheath 312 tothe sheath hub 304, while also resisting expansion of the underlying portion of the sheath 212. In some implementations, strain relief portion 218 is composed of a stiffer and / or less elastomeric material than the underlying layers of the sheath 212 and restricts expansion as the prosthetic device 102 is advanced therethrough. For example, in some implementations, strain relief portion 218 is composed of a material having a higher durometer than the underlying layers of the sheath 212, including the inner layer 222 and / or outer layer 228. In some implementations, the sheath 312 includes a strain relief portion 218 extending distally from the proximal end 316 of the sheath 312.

[0112] In some implementations, the sheath 312 includes a sleeve 380 extending along a proximal portion of the sheath 312. Similar to the strain relief portion 218, the sleeve 380 provides a stiff component extending distally from the proximal end 316 of the sheath 312. In some implementations, the sleeve 380 has a size, structure, and / or composition similar- to the strain relief portion 218. In some implementations, the sleeve 380 coupled to the proximal end of the sheath 312 instead of the strain relief portion 218. In some implementations, the sleeve 380 is provided on the sheath 312 in addition to the strain relief portion 218.

[0113] In some implementations, the length of the sleeve 380 corresponds to the desired and / or approximate length of the portion of the sheath 312 external to the patient when the sheath 312 is received within the patient’s vasculature for delivering a prosthetic device 102. In some implementations, the length of the sleeve 380 corresponds to the desired and / or approximate length of the portion of the sheath 312 extending between the sheath hub 304 / locking nut 305 and the vein / blood vessel entry point. In some implementations, as described herein, the sleeve 380 will extend at least partially into the blood vessel. For example, in some implementations, when the sheath 312 is used for delivering a prosthetic device 102, the sleeve 380 extends from the sheath hub 304 and at least partially into the patient’s vasculature. In some implementations, sheath assembly 300 can include several sleeves 380 of various lengths, where the length of the sleeve 380 can be selected based on the thickness of the patient’s skin and fat layers at the insertion site. As described herein in reference to FIGS. 16 and 17, the it is desirable to position the distal end of the sleeve 380 at and / or just within the vein entry point. As such, and as described herein, it may be necessary to limit or otherwise control the length of the sheath 312 received within the patient by coupling the spacer 350 / additional spacer 370 to the sheath 312 to limit advancement of the sheath 312 within the patient’s blood vessel.

[0114] As illustrated in FIG. 10, in some implementations the sleeve 380 can have a tapered proximal end and an elongated body portion extending distally from the tapered proximal end. In some implementations, the tapered proximal end of the sleeve 380 has a taper corresponding to the tapered inner and / or outer surface of the distal end of the sheath hub 304. As such, the sleeve 380 provides a smooth transition for the prosthetic device 102 passing through the sheath hub 304, sleeve 380, and into the sheath hub 304.

[0115] In some implementations, the sheath 312 is coupled to the sleeve 380. For example, the sheath 312 can be coupled to the sleeve 380 by a mechanical fastener and / or chemical fastener (for example, an adhesive). In some implementations, the sheath 312 is coupled to the 380 by a thermal process including, for example, a weld, reflowing the material of the sheath 312 with the material of the sleeve 380.

[0116] In some implementations, the sheath 312 is received within the central lumen of the sleeve 380. In some implementations, the sleeve 380 is received within the central lumen 314 of the sheath 312. In some implementations, the proximal end 316 of the sheath 312 extends beyond the proximal end of the sleeve 380. For example, a portion of the sheath 312 may extend beyond the proximal end of the sleeve 380 such that the sheath 312 and sleeve 380 are secured to the sheath hub 304 by compression of the sheath 312 between the locking nut 305 and the sheath hub 304.

[0117] In some implementations, similar to the strain relief portion 218, the sleeve 380 helps to secure the sheath 312 to the sheath hub 304. For example, in some implementations, the sleeve 380 can be secured to the sheath hub 304 by compression between the locking nut 305 and the sheath hub 304. That is, in some implementations, a portion of the sleeve 380 is positioned between the locking nut 305 and the sheath hub 304 such that coupling the locking nut 305 to the sheath hub 304 fixes the sleeve 380 to the sheath hub 304. As illustrated in FIG. 10, when assembled the proximal end of the sleeve 380 abuts the distal end of the sheath hub 304, and the tapered portion of the sleeve 380 extends through the central opening of the locking nut 305.

[0118] As provided in FIG. 10, in some implementations, the at least a portion of the sheath 312 positioned along the sleeve 380 has a diameter corresponding to the diameter of the central lumen 353 of the spacer 350 (and / or diameter of the central lumen 373 of the additional spacer 370). As a result, when the spacer 350 / additional spacer 370 is positioned over the sheath 312 itsaxial and / or circumferential position along and / or around the sheath 312 is fixed, or movement along / around the sheath 312 is limited as described herein.

[0119] In some implementations, the inner surface of the central lumen 314 of the spacer 350 has a size and shape corresponding to the size and shape of the sleeve 380. For example, FIG. 15 provides an example spacer 350 having a tapered inner surface 355 extending from the proximal surface 356 of the spacer 350. In some implementations, the tapered inner surface 355 has a size and shape corresponding to the size and shape of the tapered portion of the sleeve 380. As such, when the spacer 350 is received on the sheath 312, the spacer 350 is positioned along the proximal portion of the sheath 312 such that the tapered inner surface 355 of the spacer 350 aligns with the tapered portion of the sleeve 380.

[0120] A method of adjusting the effective length of an introducer sheath is provided. As described herein, in some implementations, it is desirable to adjust the effective length of the sheath to accommodate the intervening skin, fat layer, and other body tissue between the body entry and the blood vessel entry. In particular, in examples including a strain relief portion 218 and / or sleeve 380 it is desirable that the portion of the sheath 312 distal the strain relief portion 218 / sleeve 380 be fully received within the patient’s vasculature, and not be external to the vein and / or body entry. As described herein, this helps to ensure hemostasis between the patient and the sheath 312 and also helps to prevent bleeding at the entry site. However, because the strain relief portion 218 / sleeve 380 provides a stiffer more rigid component of the sheath 312, positioning the portion of the sheath 312 including the strain relief portion 218 / sleeve 380 too deeply inside the blood vessel can result in trauma to the blood vessel structure. Positioning a spacer 350 at the proximal end of the sheath 312, the user is able to control the effective length of the sheath 312 received within the blood vessel, and as a result control the length of the strain relief portion 218 / sleeve 380 received within and / or extending through the entry to the blood vessel. Variations in patient anatomy, in particular the thickness of the intervening skin, fat layer, and other body tissue between the body entry and the blood vessel entry, mean that a single sheath 312 / sleeve 380 / strain relief portion 218 length is not universal to all patients. As described herein, depending on patient anatomy it may be desirable to use a spacer 350 to adjust the effective length of the introducer sheath 312. Spacers 350 having varying length may be provided, and the spacer 350 (or combination of spacers) can be selected to achieve a desired reduction in the effective length of the sheath 312.

[0121] FIGS. 16 and 17 provide schematic representations positioning the sheath 312 / sheath assembly 300 for delivering a medical device with respect to two different patient anatomies. As illustrated in FIG. 16, when used with a patient having a thicker skin / fat layer, the sheath assembly 300 may not require the use of a spacer 350. Because the patient has a thicker skin / fat layer, a longer effective length of the sheath 312 is required to reach the treatment site. In particular, the thicker skin / fat layer results in a greater length of the sleeve 380 / strain relief portion 218 extending within the patient between the opening in the skin and the blood vessel entry point, without resulting in an undesirable length of the sleeve 380 / strain relief portion 218 being received within the blood vessel.

[0122] However, as illustrated in FIG. 17, when used with a patient having a comparatively thinner skin / fat layer, the sheath assembly 300 may require the use of a spacer 350. Because the patient has a comparatively thinner skin / fat layer, a shorter effective length of the sheath 312 is required to reach the treatment site. In particular, the thinner skin / fat layer results in a shorter length of the sleeve 380 / strain relief portion 218 extending within the patient between the opening in the skin and the blood vessel entry point, without resulting in an undesirable length of the sleeve 380 / strain relief portion 218 being received within the blood vessel. As described herein, providing a sheath 312 with a shorter effective length helps to minimize the length of the sheath 312 exterior to the patient during the treatment procedure, ensuring hemostasis at the sheath entry site through the skin and blood vessel.

[0123] A method for adjusting the effective length of the example sheath 312 is described herein. While this example is described in reference to the sheath 312 provided in FIGS. 8-11, it is contemplated that a corresponding method may be used to adjust the effective length of any sheath described herein.

[0124] In some implementations, the sheath 312 has an initial effective length (Leff) measured between the proximal end 316 and the distal end 313 of the sheath 312. In some implementations, where a sheath hub 304 is used, the initial effective length (Left) measured between the distal end 313 of the sheath 312 and the distal most portion of the sheath hub 304, including the distal end of the locking nut 305.

[0125] A spacer 350 having a spacer length (Ls) is selected based on the desired decrease in the effective length (Leff) of the sheath 312. In some implementations, multiple spacers 350 are selected to achieve the desired decrease in the effective length (Leff) of the sheath 312. Forexample, in some implementations, as illustrated in FIG. 1 1 , multiple spacers including spacer 350, first additional spacer 370A, and second additional spacer 370B arc selected to achieve the desired decrease in the effective length (Leff) of the sheath 312.

[0126] The selected spacer 350 is positioned on the sheath 312 as described herein. For example, in some implementations, the spacer 350 is loaded onto the sheath 312 by advancing the distal end sheath 312 or the proximal end 316 of the sheath 312 into and through the central lumen 353 of the spacer 350. In some implementations, the spacer 350 includes a longitudinally extending gap 362 on the spacer body 352. The spacer 350 is coupled to the sheath 312 by widening the gap 362 as described herein and advancing the sheath 312 through the gap 362.

[0127] As illustrated in FIGS. 8 and 17, the spacer 350 is positioned / located on the sheath 312 at a location adjacent the proximal end 316 of the sheath 312. In some implementations, the spacer 350 is advanced along the sheath 312 until the proximal surface 356 of the spacer 350 is located adjacent the proximal end 316 of the sheath 312. For example, where the proximal end 316 of the sheath 312 coupled to a sheath hub 304, the spacer 350 is advanced along the sheath 312 until the proximal surface 356 of the spacer 350 abuts the sheath hub 304 / locking nut 305.

[0128] As a result, positioning the spacer 350 on the sheath 312 at the proximal end of the sheath 312 results in a corresponding decrease in the initial effective length (Leff) of the sheath 312 to a decreased effective length (Ldec), where the difference between the initial effective length (Leff) and the decreased effective length (Ldec) corresponds to the spacer length (Ls). The decreased effective length (Ldec) can be measured between the distal end surface 354 of the spacer 350 and the distal end 313 of the sheath 312. As described herein, the desired spacer 350 is identified having the spacer length (Ls) that will result in the desired decreased effective length (Ldec) corresponding to the desired length of the sheath 312 to be received within a patient.

[0129] As described herein, in some implementations multiple spacers 350 are positioned the sheath 312 to achieve the desired effective length (Leff) and / or decreased effective length (Ldec). Accordingly, in some implementations, an additional spacer 370 is positioned on the sheath 312 as described herein. The additional spacer 370 is then advanced on the sheath 312 to a location adjacent to the spacer 350. For example, the additional spacer 370 can be positioned on the sheath 312 such that the proximal surface 376 of the additional spacer 370 abuts the distal end surface 354 of the spacer 350. In some implementations, as described herein, the adjacent spacers 350 and / or additional spacer 370 can be fixedly and / or releasably coupled together. Insome implementations, the adjacent spacer 350 and additional spacer 370 can be coupled together before they arc loaded onto the sheath 312. While in some implementations, the adjacent spacer 350 and additional spacer 370 can be coupled together after they have been loaded onto the sheath 312. It is contemplated that any number of spacers 350 and / or additional spacers 370 can be provided on the sheath 312 to achieve the desired effective length of the sheath 312.

[0130] As described herein, loading the spacer 350 onto the sheath 312 results in a decrease in the initial effective length (Leff) to a decreased effective length (Ldec) of the sheath 312. Likewise, loading the any additional spacers 370 onto the sheath 312 results in a corresponding decrease in the decreased effective length (Ldec) of the sheath 312 to a second decreased effective length (Ldec2), where the difference between the initial effective length (Leff) and the second decreased effective length (Ldec ) corresponds with a combined length of the spacer 350 and any additional spacers 370 loaded onto the sheath 312.

[0131] A method of using example sheaths 212 described herein to implant a prosthetic device into a patient is described. While this example is described in reference to the sheath 312 provided in FIGS. 8-17, it is contemplated that a corresponding method may be used to adjust the effective length of any sheath described herein.

[0132] In some implementations, the desired effective length (Leff) of the sheath 312 is determined before the treatment procedure and before the sheath 312 is inserted into the patient. Accordingly, any needed combination of spacer 350 and / or additional spacers 370 can be loaded onto the sheath 312 as described herein to achieve the desired effective length (Leff) of the sheath 312.

[0133] In some implementations, the desired effective length (Leff) of the sheath 312 is not determined until the sheath 312 is at least partially positioned within the patient. Accordingly, the sheath 312 is advanced at least partially into the patient’s blood vessel before the spacer 350 and / or additional spacer 370 is loaded thereon.

[0134] In some implementations, an introducer 240 is optionally used to help advance the sheath 312 toward the treatment site. In these implementations, the distal end of the introducer 240 is inserted into the proximal end 316 of the sheath 312 and advanced into the central lumen 314 of the sheath 312 (as shown for example in FIG.2). The introducer 240 is advanced within thecentral lumen 312 of the sheath 312 in a distal direction toward the distal end 313 of the sheath 312.

[0135] The combined expandable sheath 312 and introducer 240 are least partially inserted into the patient’s blood vessel and advanced to the treatment site. In some examples, the expandable sheath 312 is inserted into the femoral artery or other vessels of the patient’s body. The vasculature, such as the femoral artery, may be narrow or stiff, and may be difficult to easily insert a delivery apparatus 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 the use of an introducer sheath 312.

[0136] In some examples, a guidewire is optionally positioned at the treatment site and the sheath 312 and introducer 240 are advanced over the guidewire.

[0137] With the sheath 312 advanced at least partially to the treatment site, the need for a spacer 350 and / or additional spacers 370 is determined based on the thickness of the fat / skin layer at the body opening.

[0138] In some implementations, as illustrated in FIG. 17, the desired spacer length (Ls) and / or desired effective length (Leff) if the sheath 312 is determined based on the length of the sheath 312 extending external to the patient while the desired length of the strain relief portion 218 and / or sleeve 380 received within the blood vessel / through the vessel opening. For example, the sheath 312 can be advanced within the patient’s blood vessel until a desired length of the strain relief portion 218 and / or sleeve 380 is received within the blood vessel so as not to damage the vessel during the procedure. With the sheath 312 positioned, the length of the sheath 312 external to the patient, for example the length of the sheath 312 extending between the body entry and the distal end of the sheath hub 304 / locking nut 305 is measured and a corresponding spacer length (Ls) is determined. As described herein, in some implementations, a combination of spacers 350 and additional spacers 370 may be needed to achieve the desired spacer length (Ls).

[0139] In some implementations, the sheath 312 is then at least partially withdrawn from the blood vessel and the spacer 350 and / or additional spacer 370 is coupled thereto as described herein.

[0140] With the spacer 350 and / or additional spacer 370 coupled to the sheath 312, the sheath 312 is then advanced within the patient’s blood vessel toward the treatment site. In some implementations, as illustrated in FIG. 17, the sheath 312 is advanced within the blood vessel toward the treatment the treatment site until the distal surface 354 of the spacer 350 abuts the surface of the patient’s skin (and / or the distal end surface of the distal most spacer). As such, the only the desired effective length (Leff) (for example the decreased effective length (Ldec)) of the sheath 312 is received within the patient’s blood vessel, such that only the desired length of the sleeve 380 / strain relief portion 218 is extends through the vessel opening and into the blood vessel.

[0141] Once the combined sheath 312 and introducer 240 are positioned at the treatment site, the introducer 240 is then withdrawn in a proximal direction within the central lumen 314 of the sheath 312. The introducer 240 is then fully withdrawn from the central lumen 314 of the sheath 312, leaving the sheath 312 within the patient’s vasculature. With the central lumen 314 of the sheath 312 clear, the medical device is then advanced into the central lumen 314 of the sheath 312. Accessing the treatment site may require creating an opening in the heart tissue (for example, foramen ovalis) of the patient. In some examples, a cutting instrument can be advanced through the sheath 212 to create an opening in the patient’s heart tissue.

[0142] The medical device, for example an implant, is advanced through the central lumen 314 of the sheath 312 and beyond the distal opening to the treatment site within the blood vessel and / or heart tissue. In some examples, the sheath 312 is sized and configured such that advancing the medical device through the sheath 312 causes the sheath 312 to locally expand from an unexpanded configuration at a first diameter to an expanded configuration at a second, larger, diameter in response to an outwardly directed radial force exerted on the central lumen by the medical device, and then locally contract at least partially back to the unexpanded configuration as the medical device moves within the central lumen 314. With the distal end of the sheath 312 positioned at the treatment site, the medical device is deployed beyond distal opening of the sheath 312 and delivered to the patient.

[0143] In some examples, the medical device / implant is a prosthetic device 102 mounted in a radially crimped state on a delivery apparatus, and advancing the prosthetic device 102 through the central lumen 314 of the sheath 312 includes advancing the delivery apparatus and the prosthetic device through central lumen 314 of the sheath 312 and into a vasculature of thepatient. In some examples, the prosthetic device comprises a prosthetic heart valve and the method further comprises implanting the prosthetic heart valve at a treatment site within the patient. In some examples, the prosthetic heart valve is mounted on a balloon catheter of the delivery apparatus as the prosthetic heart valve is advanced through the sheath 312.

[0144] Exemplary Aspects

[0145] 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.

[0146] Example 1. An introducer sheath assembly comprising: an introducer sheath for deploying a medical device, a spacer adjacent a proximal end of the introducer sheath, wherein the spacer defines an effective spacer length (Ls) corresponding to a decrease in an effective length (Lcff) of the introducer sheath.

[0147] Example 2. An introducer sheath assembly according to any example herein, particularly example 1, further comprising: an introducer sheath for deploying a medical device, the introducer sheath having a distal end and a proximal end with a central lumen extending therebetween; a spacer adjacent a proximal end of the introducer sheath, the spacer having a spacer body extending between a distal surface and an opposite proximal surface, wherein the spacer extends around at least a portion of a circumference of the introducer sheath, wherein the spacer body defines an effective spacer length (Ls) corresponding to a decrease in an effective length (Leff) of the introducer sheath, wherein at least a portion of the introducer sheath is configured to locally expand from an unexpanded configuration in the which the central lumen has a first diameter to an expanded configuration in which the central lumen has a second diameter that is larger than the first diameter, and then locally contract at least partially back to the unexpanded configuration.

[0148] Example 3. The introducer sheath assembly according to any example herein, particularly examples 1-2, wherein the effective length (Leff) of the introducer sheath corresponds to a portion of the introducer sheath that is sized and configured to be received within a patient, where theeffective length Leff and is measured between a distal end of the introducer sheath and the distal surface of the spacer.

[0149] Example 4. The introducer sheath assembly according to any example herein, particularly examples 1-3, wherein the spacer comprises an additional spacer provided adjacent the spacer along the introducer sheath, the additional spacer having a spacer body extending between a distal surface and an opposite proximal surface of the additional spacer. In some implementations, the sheath assembly includes one additional spacer. In further implementations, the sheath assembly includes at least two additional spacers. In some implementations, the additional spacer is positioned adjacent to the proximal surface of the spacer.

[0150] Example 5. The introducer sheath assembly according to any example herein, particularly example 4, wherein a combined length of the effective spacer length (Ls) of the spacer body and effective spacer length (Ls1) of the additional spacer body defines a combined effective spacer length (L total)-

[0151] Example 6. The introducer sheath assembly according to any example herein, particularly examples 4-5, wherein the effective spacer length (Ls1) of the additional spacer is different from the effective spacer length (Ls) of the spacer. In some implementations, where the sheath assembly includes at least two additional spacers, it is contemplated that that effective spacer length (Ls) of the spacer is different from the effective spacer length (Ls1) of either of the additional spacers.

[0152] Example 7. The introducer sheath assembly according to any example herein, particularly examples 2-6, wherein the spacer further comprises a body that extends around an entire circumference of the introducer sheath.

[0153] Example 8. The introducer sheath assembly according to any example herein, particularly examples 2-7, wherein the spacer body extends only around a portion of a circumference of the introducer sheath and is movable between an open configuration and a closed configuration.

[0154] Example 9. The introducer sheath assembly according to any example herein, particularly examples 2-8, wherein the spacer is elastically deformable between an open and closed configuration.

[0155] Example 10. The introducer sheath assembly according to any example herein, particularly examples 7-9, wherein in the open configuration, the body of the spacer comprises a first arm portion movably coupled to a second arm portion. In some implementations, in theclosed configuration, the first arm portion and the second arm portion define a continuous outer edge extending in a circumferential direction around the spacer.

[0156] Example 11. The introducer sheath assembly according to any example herein, particularly examples 8-10, wherein the spacer body further comprises a hinge for moving the spacer between the open configuration and the closed configuration.

[0157] Example 12. The introducer sheath assembly according to any example herein, particularly examples 4-11, wherein the body of at least one of the spacer and / or the additional spacer comprises an open C-shaped body, wherein a gap is defined between opposing end surfaces of the open C-shaped body of the spacer and / or additional spacer. In some implementations, the gap is defined between the end surfaces of the first arm portion and the second arm portion.

[0158] Example 13. The introducer sheath assembly according to any example herein, particularly example 12, wherein a width of the gap is configured to increase to accommodate the circumference of the introducer sheath.

[0159] Example 14. The introducer sheath assembly according to any example herein, particularly example 13, wherein the spacer is configured to flex so as to increase the width of the gap. Interlocking spacers

[0160] Example 15. The introducer sheath assembly according to any example herein, particularly examples 4-14, wherein the spacer and / or the additional spacer includes a mating feature (for example, shoulders provided on the corresponding spacer and additional spacer) configured to engage with one another.

[0161] Example 16. The introducer sheath assembly according to any example herein, particularly example 15, wherein the mating feature includes a shoulder provided on the spacer and / or the additional spacer, wherein a first shoulder extends from the proximal surface of the spacer, the first shoulder configured to mate with a complementary shoulder extending from the distal surface of the additional spacer when positioned adjacent the spacer.

[0162] Example 17. The introducer sheath assembly according to any example herein, particularly examples 3-16, further comprising: a sheath hub positioned at a proximal end of the introducer sheath, the sheath hub having an elongated body having a distal end and a proximal end; and a locking nut operatively coupled to the distal end of the sheath hub, the locking nut securing the introducer sheath to the sheath hub.

[0163] Example 18. The introducer sheath assembly according to any example herein, particularly examples 17, wherein the proximal surface of a proximal most one of the spacer or the additional spacer abuts the locking nut.

[0164] Example 19. The introducer sheath assembly according to any example herein, particularly examples 17-18, further comprising: a sleeve provided along a proximal portion of the introducer sheath, where a proximal end of the sleeve is coupled to the sheath hub. In some implementations, the sleeve helps to couple the introducer sheath to the sheath hub. In some implementations, the sleeve defines a rigid or semi-rigid component for supporting the proximal end of the sheath and helping to ensure hemostasis along the sheath at the treatment site.

[0165] Example 20. The introducer sheath assembly according to any example herein, particularly example 19, wherein an inner surface of the spacer body of the spacer and / or additional spacer has a size and shape corresponding to a size and shape of the sleeve.

[0166] Example 21. The introducer sheath assembly according to any example herein, particularly example 20, wherein the inner surface includes a tapered portion having a size and shape corresponding to a tapered portion of the sleeve.

[0167] Example 22. A method for controlling an effective length of an introducer sheath, the method including: providing an introducer sheath including a central lumen extending therethrough, at least a portion of the sheath is configured to locally expand from an unexpanded configuration in the which the central lumen has a first diameter to an expanded configuration in which the central lumen has a second diameter that is larger than the first diameter, and then locally contract at least partially back to the unexpanded configuration; and advancing a spacer onto the introducer sheath to a location adjacent a proximal end of the introducer sheath, the spacer having a spacer body extending between a distal surface and an opposite proximal surface, wherein the spacer extends around an entire circumference of the introducer sheath, the spacer body defining a spacer length (Ls), wherein the introducer sheath has an initial effective length (Leff) measured between the proximal end and a distal end of the introducer sheath, wherein positioning the spacer on the introducer sheath at the location adjacent the proximal end of the introducer sheath results in a corresponding decrease in the initial effective length (Leff) of the introducer sheath to a decreased effective length (Ldec), the difference between the initial effective length (Leff) and the decreased effective length (Ldec) corresponds to the spacer length (Ls).

[0168] Example 23. The method according to any example herein, particularly example 22, wherein the spacer length (Ls) is determined such that the decreased effective length (Ldec) corresponds with a desired length of the introducer sheath to be received within a patient, wherein the decreased effective length (Ldec) is measured between the distal end surface of the spacer and the distal end of the introducer sheath.

[0169] Example 24. The method according to any example herein, particularly examples 22-23, further including: advancing an additional spacer onto the introducer sheath to a location adjacent the spacer resulting in a corresponding decrease in the decreased effective length (Ldec) of the introducer sheath to a second decreased effective length (Ldec2), wherein the difference between the initial effective length (Leff) and the second decreased effective length (Ldec?) corresponds with a combined length of the spacer and the additional spacer.

[0170] Example 25. The method according to any example herein, particularly examples 22-24, wherein the spacer is advanced onto the introducer sheath by advancing the distal end or the proximal end of the introducer sheath into a central lumen of the spacer, the method further including: further advancing the introducer sheath through the central lumen of the spacer until a proximal end of the spacer is positioned at the location adjacent the proximal end of the introducer sheath.

[0171] Example 26. The method according to any example herein, particularly example 25, wherein the proximal end of the introducer sheath is coupled to a sheath hub; wherein further advancing the introducer sheath includes advancing the spacer onto the sheath to a location where the spacer abuts the sheath hub.

[0172] Example 27. A method for controlling an effective length of an introducer sheath, the method including: providing an introducer sheath including a central lumen extending therethrough, at least a portion of the sheath is configured to locally expand from an unexpanded configuration in the which the central lumen has a first diameter to an expanded configuration in which the central lumen has a second diameter that is larger than the first diameter, and then locally contract at least partially back to the unexpanded configuration; and coupling a spacer to the introducer sheath at a location adjacent a proximal end of the introducer sheath, the spacer having a body extending between a distal surface and an opposite proximal surface, wherein the spacer extends around a portion of a circumference of the introducer sheath, the spacer body defining a spacer length (Ls); wherein the introducer sheath as an initial effective length (Leff)measured between the proximal end and a distal end of the introducer sheath, wherein positioning the spacer on the introducer sheath at the location adjacent the proximal end of the introducer sheath results in a corresponding decrease in the initial effective length (Leff) of the introducer sheath to a decreased effective length (Ldec), the difference between the initial effective length (Left) and the decreased effective length (Ldec) corresponds to the spacer length (Ls).

[0173] Example 28. The method according to any example herein, particularly example 27, wherein the spacer length (Ls) is determined such that the decreased effective length (Ldec) corresponds with a desired length of the introducer sheath to be received within a patient, wherein the decreased effective length (Ldec) is measured between the distal end surface of the spacers and the distal end of the introducer sheath.

[0174] Example 29. The method according to any example herein, particularly examples 27-28, further including: coupling an additional spacer to the introducer sheath at a location adjacent the spacer, resulting in a corresponding decrease in the decreased effective length (Ldec) of the introducer sheath to a second decreased effective length (LdCC2), wherein the difference between the initial effective length (Left) and the second decreased effective length (Ldeci) corresponds with a combined length of the spacer and the additional spacer.

[0175] Example 30. The method according to any example herein, particularly examples 27-29, wherein the spacer includes a longitudinally extending gap in the body portion, wherein the spacer is coupled to the introducer sheath by widening the gap and advancing the introducer sheath through the gap.

[0176] Example 31. The method according to any example herein, particularly examples 27-30, wherein the spacer comprises an open C-shaped body with a gap defined between opposing end surfaces of the C-shaped body, where coupling the spacer to the introducer sheath includes: increasing a width of the gap to a width greater than an outer diameter of the introducer sheath; advancing the spacer over the introducer sheath in a direction transverse to a longitudinal axis of the introducer sheath; positioning the spacer at least partially around a circumference of the introducer sheath; and decreasing the width of the gap to a width less than the outer diameter of the introducer sheath.

[0177] Example A method of delivering a medical device into a blood vessel of a patient, comprising: inserting an introducer sheath at least partially into the blood vessel of the patient,the sheath including a central lumen extending therethrough, at least a portion of the sheath is configured to locally expand from an unexpanded configuration in the which the central lumen has a first diameter to an expanded configuration in which the central lumen has a second diameter that is larger than the first diameter, and then locally contract at least partially back to the unexpanded configuration; advancing a distal end of the introducer sheath to a first location proximate a treatment site; positioning a spacer onto the introducer sheath at a location, the spacer defining a lumen between a distal surface and a proximal surface opposite the distal surface, the spacer extending around at least a portion of a circumference of the introducer sheath, the spacer defining a spacer length (Ls); advancing the distal end of the introducer sheath toward the treatment the treatment site until the distal surface of the spacer abuts a surface of a patient's skin; advancing a medical device through the central lumen of the introducer sheath to the treatment site within the blood vessel; and delivering the medical device to the treatment site; wherein the introducer sheath has an initial effective length (Leff) measured between the proximal end and a distal end of the introducer sheath, wherein positioning the spacer on the introducer sheath results in a corresponding decrease in the initial effective length (Lcff) of the introducer sheath to a decreased effective length (Ldec), a difference between the initial effective length (Leff) and the decreased effective length (Ldec) corresponds to the spacer length (Ls).

[0178] Example 33. The method according to any example herein, particularly example 32, wherein the spacer length (Ls) is determined such that the decreased effective length (Ldec) corresponding to a desired length of the introducer sheath to be received within a patient, wherein the decreased effective length (Ldec) is measured between the distal end surface of the spacer and the distal end of the introducer sheath.

[0179] Example 34. The method according to any example herein, particularly examples 32-33, further including: positioning an additional spacer on the introducer sheath at a location adjacent the spacer resulting in a corresponding decrease in the decreased effective length (Ldec) of the introducer sheath to a second decreased effective length (Ldec2), wherein the difference between the initial effective length (Leff) and the second decreased effective length (Ldec2) corresponds with a combined length of the spacer and the additional spacer.

[0180] Example 35. The method according to any example herein, particularly example 34, wherein the additional spacer is positioned on the introducer sheath such that a proximal surface of the additional spacer abuts a distal surface of the spacer.

[0181] Example 36. The method according to any example herein, particularly examples 32-35, wherein the proximal end of the introducer sheath is coupled to a sheath hub; wherein further advancing the introducer sheath includes advancing the spacer onto the sheath to a location where the spacer abuts the sheath hub.

[0182] Example 37. The method according to any example herein, particularly examples 32-36, further including: withdrawing a delivery apparatus from the introducer sheath; and withdrawing the introducer sheath from the patient's blood vessel.

[0183] Example 38. The method according to any example herein, particularly examples 32-37, wherein the medical device is a prosthetic device mounted in a radially crimped state on a delivery apparatus.

[0184] Example 39. The method according to any example herein, particularly example 38, wherein the prosthetic device comprises a prosthetic heart valve and the method further includes implanting the prosthetic heart valve at the treatment site within the patient.

[0185] Example 40. The method according to any example herein, particularly example 39, wherein the prosthetic heart valve is mounted on a balloon catheter of the delivery apparatus as the prosthetic heart valve is advanced through the introducer sheath.

[0186] Example 41. The method according to any example herein, particularly examples 32-40, wherein the introducer sheath is inserted into a femoral artery of the patient.

[0187] 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 introducer sheath assembly comprising: an introducer sheath for deploying a medical device, the introducer sheath having a distal end and a proximal end with a central lumen extending therebetween; a spacer adjacent a proximal end of the introducer sheath, the spacer having a spacer body extending between a distal surface and an opposite proximal surface, wherein the spacer extends around at least a portion of a circumference of the introducer sheath, wherein the spacer body defines an effective spacer length (Ls) corresponding to a decrease in an effective length (Left) of the introducer sheath, wherein at least a portion of the introducer sheath is configured to locally expand from an unexpanded configuration in the which the central lumen has a first diameter to an expanded configuration in which the central lumen has a second diameter that is larger than the first diameter, and then locally contract at least partially back to the unexpanded configuration.

2. The introducer sheath assembly of claim 1, wherein the effective length (Left) of the introducer sheath corresponds to a portion of the introducer sheath that is sized and configured to be received within a patient, where the effective length (Leff) and is measured between a distal end of the introducer sheath and the distal surface of the spacer.

3. The introducer sheath assembly of any one of claims 1-2, wherein the spacer comprises an additional spacer provided adjacent the spacer along the introducer sheath, the additional spacer having a spacer body extending between a distal surface and an opposite proximal surface of the additional spacer, wherein a combined length of the effective spacer length (Ls) of the spacer body and effective spacer length (Ls’) of the additional spacer body defines a combined effective spacer length (Ltotai).

4. The introducer sheath assembly of claim 3, wherein the effective spacer length (Ls’) of the additional spacer is different from the effective spacer length (Ls) of the spacer.

5. The introducer sheath assembly of any one of claims 1 -4, wherein the spacer further comprises a body that extends around an entire circumference of the introducer sheath.

6. The introducer sheath assembly of any one of claims 1-5, wherein the spacer body extends only around a portion of a circumference of the introducer sheath and is movable between an open configuration and a closed configuration.

7. The introducer sheath assembly of claim 6, wherein the spacer body further comprises a hinge for moving the spacer between the open configuration and the closed configuration.

8. The introducer sheath assembly of any one of claims 3-7, wherein the spacer body of at least one of the spacer and / or the additional spacer comprises an open C-shaped body, wherein a gap is defined between opposing end surfaces of the open C-shaped body of the spacer and / or additional spacer.

9. The introducer sheath assembly of any one of claims 3-8, wherein the spacer and / or the additional spacer includes a mating feature configured to engage with one another.

10. The introducer sheath assembly of claim 9, wherein the mating feature includes a shoulder provided on the spacer and / or the additional spacer, wherein a first shoulder extends from a proximal surface of the spacer, the first shoulder configured to mate with a complementary shoulder extending from the distal surface of the additional spacer when positioned adjacent the spacer.

11. The introducer sheath assembly of any one of claims 2-10, further comprising: a sheath hub positioned at a proximal end of the introducer sheath, the sheath hub having an elongated body having a distal end and a proximal end; and a locking nut operatively coupled to the distal end of the sheath hub, the locking nut securing the introducer sheath to the sheath hub.

12. The introducer sheath assembly of claim 11 , further comprising: a sleeve provided along a proximal portion of the introducer sheath, where a proximal end of the sleeve is coupled to the sheath hub, wherein an inner surface of the spacer body of the spacer and / or additional spacer has a size and shape corresponding to a size and shape of the sleeve.

13. A method for controlling an effective length of an introducer sheath, the method including: providing an introducer sheath including a central lumen extending therethrough, at least a portion of the sheath is configured to locally expand from an unexpanded configuration in the which the central lumen has a first diameter to an expanded configuration in which the central lumen has a second diameter that is larger than the first diameter, and then locally contract at least partially back to the unexpanded configuration; and advancing a spacer onto the introducer sheath to a location adjacent a proximal end of the introducer sheath, the spacer having a spacer body extending between a distal surface and an opposite proximal surface, wherein the spacer extends around an entire circumference of the introducer sheath, the spacer body defining a spacer length (Ls), wherein the introducer sheath has an initial effective length (Left) measured between the proximal end and a distal end of the introducer sheath, wherein positioning the spacer on the introducer sheath at the location adjacent the proximal end of the introducer sheath results in a corresponding decrease in the initial effective length (Leff) of the introducer sheath to a decreased effective length (Ldec), a difference between the initial effective length (Leff) and the decreased effective length (Ldec) corresponds to the spacer length (Ls).

14. The method of claim 13, wherein the spacer length (Ls) is determined such that the decreased effective length (Ldec) corresponds with a desired length of the introducer sheath to be received within a patient, wherein the decreased effective length (Ldec) is measured between the distal end surface of the spacer and the distal end of the introducer sheath.

15. The method of any one of claims 13-14, further including: advancing an additional spacer onto the introducer sheath to a location adjacent the spacer resulting in a corresponding decrease in the decreased effective length (Ldec) of the introducer sheath to a second decreased effective length (Ldec2), wherein the difference between the initial effective length (Leftj and the second decreased effective length (Ldec2) corresponds with a combined length of the spacer and the additional spacer.

16. The method of any one of claims 13-15, wherein the spacer is advanced onto the introducer sheath by advancing the distal end or the proximal end of the introducer sheath into a central lumen of the spacer, the method further including: further advancing the introducer sheath through the central lumen of the spacer until a proximal end of the spacer is positioned at the location adjacent the proximal end of the introducer sheath.

17. A method for controlling an effective length of an introducer sheath, the method including: providing an introducer sheath including a central lumen extending therethrough, at least a portion of the sheath is configured to locally expand from an unexpanded configuration in the which the central lumen has a first diameter to an expanded configuration in which the central lumen has a second diameter that is larger than the first diameter, and then locally contract at least partially back to the unexpanded configuration; and coupling a spacer to the introducer sheath at a location adjacent a proximal end of the introducer sheath, the spacer having a body extending between a distal surface and an opposite proximal surface, wherein the spacer extends around a portion of a circumference of the introducer sheath, the spacer body defining a spacer length (Ls); wherein the introducer sheath as an initial effective length (Leff) measured between the proximal end and a distal end of the introducer sheath, wherein positioning the spacer on the introducer sheath at the location adjacent the proximal end of the introducer sheath results in a corresponding decrease in the initial effectivelength (Leff) of the introducer sheath to a decreased effective length (Ldec), a difference between the initial effective length (Leff) and the decreased effective length (Ldec) corresponds to the spacer length (Ls), wherein the spacer length (Ls) is determined such that the decreased effective length (Ldec) corresponds with a desired length of the introducer sheath to be received within a patient, wherein the decreased effective length (Ldec) is measured between the distal end surface of the spacers and the distal end of the introducer sheath.

18. The method of claim 17, further including: coupling an additional spacer to the introducer sheath at a location adjacent the spacer, resulting in a corresponding decrease in the decreased effective length (Ldec) of the introducer sheath to a second decreased effective length (Ldec2), wherein the difference between the initial effective length (Leff) and the second decreased effective length (Ldec2) corresponds with a combined length of the spacer and the additional spacer.

19. The method of any one of claims 17-18, wherein the spacer comprises an open C-shaped body with a gap defined between opposing end surfaces of the C-shaped body, where coupling the spacer to the introducer sheath includes: increasing a width of the gap to a width greater than an outer diameter of the introducer sheath; advancing the spacer over the introducer sheath in a direction transverse to a longitudinal axis of the introducer sheath; positioning the spacer at least partially around a circumference of the introducer sheath; and decreasing the width of the gap to a width less than the outer diameter of the introducer sheath.

20. A method of delivering a medical device into a blood vessel of a patient, comprising: inserting an introducer sheath at least partially into the blood vessel of the patient, the sheath including a central lumen extending therethrough, at least a portion of the sheath isconfigured to locally expand from an unexpanded configuration in the which the central lumen has a first diameter to an expanded configuration in which the central lumen has a second diameter that is larger than the first diameter, and then locally contract at least partially back to the unexpanded configuration; advancing a distal end of the introducer sheath to a first location proximate a treatment site; positioning a spacer onto the introducer sheath at a location, the spacer defining a lumen between a distal surface and a proximal surface opposite the distal surface, the spacer extending around at least a portion of a circumference of the introducer sheath, the spacer defining a spacer length (Ls); advancing the distal end of the introducer sheath toward the treatment the treatment site until the distal surface of the spacer abuts a surface of a patient’s skin; advancing a medical device through the central lumen of the introducer sheath to the treatment site within the blood vessel; and delivering the medical device to the treatment site; wherein the introducer sheath has an initial effective length (Left) measured between the proximal end and a distal end of the introducer sheath, wherein positioning the spacer on the introducer sheath results in a corresponding decrease in the initial effective length (Leff) of the introducer sheath to a decreased effective length (Ldec), a difference between the initial effective length (Leff) and the decreased effective length (Ldec) corresponds to the spacer length (Ls).

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