Combined introducer and expandable sheath

Abstract

To provide an improved sheath for delivery of endovascular systems used for implanting heart valves and other prostheses.SOLUTION: Disclosed herein is a combined introducer and expandable sheath having an inner member and an outer elastomeric jacket. The inner member has radially folded tapered segments in an unexpanded state that are mechanically unfolded and moved toward an inner wall of the elastomeric jacket by a medical device moving through a lumen of the inner member. The compressive outer elastomeric jacket returns the expanded inner member to the radially folded, unexpanded state once the medical device has passed through the expanded lumen of the inner member. The structure can include a distal region that tapers to a rounded tip. A proximal region also tapers to mate with a hemostasis value housing.SELECTED DRAWING: Figure 3A

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Application No. 62 / 778,698, filed December 12, 2018, and entitled “Combined Introducer and Expandable Sheath,” the contents of which are incorporated by reference.

[0002] The present application relates to embodiments of a sheath for use with catheter-based techniques to introduce a prosthesis, such as a heart valve or other implant, into a patient's vasculature. [Background technology]

[0003] Intravascular delivery catheter assemblies are used to implant prosthetic devices, such as prosthetic heart valves, in locations within the body that are not easily accessible by surgery or where it is desirable to reach them without invasive surgery. For example, aortic, mitral, tricuspid, and / or pulmonary prosthetic valves can be delivered to the treatment site using minimally invasive surgical techniques, including transcatheter delivery methods.

[0004] A sheath can be used to safely introduce a delivery device into a patient's vasculature (e.g., the femoral artery). A sheath generally has an elongated sleeve that is inserted into the vasculature and a housing that includes one or more sealing valves that allow the delivery device to be placed in fluid communication with the vasculature while minimizing blood loss.

[0005] Radially expandable intravascular sheaths reduce the overall profile of the sheath, reducing the risk of damaging the vessel. Some radially expandable sheaths have complex mechanisms, such as latching mechanisms, that maintain the shaft or sheath in an expanded configuration after a device having a diameter larger than the original diameter of the sheath is introduced. Other radially expandable sheaths may incorporate elastic and folding structures to allow them to expand during the passage of a medical device and collapse after the medical device has been passed.

[0006] Despite advances in dilated endovascular sheath technology, delivery and / or removal of prostheses and other elements to and from patients still poses risks to patients. For example, accessing blood vessels such as the femoral artery remains problematic because the sheath and delivery system have a relatively large profile and therefore may tear the blood vessel longitudinally and radially during insertion. Traditional methods of accessing blood vessels prior to introducing a sheath include dilating the blood vessel using multiple tapered introducers (also called dilators) of progressively larger diameters. Such repeated insertions and dilations increase the time of the procedure and the risk of injury to the blood vessel. Repeated insertions and dilations also pose the additional risk of dislodging calcified plaque within the blood vessel, which may cause thrombosis.

[0007] Thus, there remains a need for further improved sheaths for delivering endovascular systems used to implant heart valves and other prosthetic devices. Summary of the Invention [Means for solving the problem]

[0008] The combined sheath and introducer disclosed herein (introducer sheath) includes a rounded tapered distal tip and a thick tapered segment with a small inner diameter that is radially folded over to extend the distance between the outer diameter and the inner diameter. The introducer sheath is stiffer / harder than conventional sheaths. Thus, the introducer sheath can be used without a dilator as it will not distort or bend when inserted into a patient's vascular site.

[0009] Thus, an exemplary combined introducer and expandable sheath according to principles described herein may include an elongate inner member having a plurality of radially folded tapered segments in an unexpanded state extending longitudinally along a longitudinal axis, the inner member defining an inner lumen having an inner diameter, and an elongate outer elastomeric jacket extending at least partially over the inner member and having a spring bias toward the inner lumen of the inner member, the inner member providing the combined introducer and expandable sheath with sufficient stiffness for insertion into a patient's vasculature. The inner member may define a longitudinally extending central lumen. The plurality of radially folded tapered segments may deploy toward an inner surface of the outer elastomeric jacket to expand the inner diameter of the inner lumen upon insertion of a medical delivery device into the lumen. In one aspect, the elongate inner member is compressible against a portion of the inner surface of the outer elastomeric jacket to expand the inner diameter of the elongate inner member to an expanded configuration, for example, for passing an implant. In another aspect, the inner member is compressible independently of the outer elastomeric jacket located distal to the seal.

[0010] The combined introducer and expandable sheath may include a strain relief extending distally from a proximal end of the outer elastomeric jacket. The outer elastomeric jacket may be attached to the strain relief. The inner member may include a rounded tapered distal tip. The inner member may have a fixed longitudinal position relative to the outer elastomeric jacket. In one aspect, the outer elastomeric jacket is fused to the inner member.

[0011] The inner lumen can be at least partially defined by the inner surface of the radially folded tapered segment in the unexpanded state. The thickness t of the tapered segment measured in the unexpanded state from the inner surface of the tapered segment to the outer surface of the tapered segment is between 0.045 inches (1.14 mm) and 0.07 inches (1.78 mm). In some embodiments of the combined introducer and expandable sheath, each radially folded tapered segment widens as it expands radially outward. A selected tapered segment can be connected to a circumferentially adjacent first tapered segment at an inner connection point and to a circumferentially adjacent second tapered segment at an outer connection point. In the unexpanded state, the inner connection point can be disposed adjacent to the inner lumen of the inner member and the outer connection point can be disposed adjacent to the outer surface of the inner member. The inner and outer connection points can be radially thinner than the tapered segments of the inner member. In this manner, the inner member of the combined introducer and expandable sheath thins and widens to extend around the circumference of the inner member. A plurality of outwardly extending gaps can extend radially outward from the inner lumen (between adjacent tapered segments), and a plurality of inwardly extending gaps can extend radially inward from the outer surface of the inner member. Each of the inwardly and outwardly extending gaps extends at least a portion of the length of the inner member.

[0012] In accordance with principles described herein, a method of delivering a prosthesis includes positioning a combined introducer and expandable sheath within a vascular site of a patient, the combined introducer and expandable sheath including an elongate inner member having a plurality of radially folded tapered segments in an unexpanded state extending longitudinally along a longitudinal axis, the inner member defining an inner lumen having an inner diameter, and an elongate outer elastomeric jacket extending at least partially over the inner member and having a spring bias toward the inner lumen of the inner member. The method may include the steps of: inserting the prosthesis into the inner lumen of the inner member, the inner member being in a radially outward localized force on the inner surface of the inner member, locally deploying the radially folded tapered segments of the inner member to an expanded configuration, and pushing the prosthesis out of the outer elastomeric jacket to return the inner member to an unexpanded state after the prosthesis exits the lumen. The method may further include positioning the combined introducer and expandable sheath at the vascular site without performing any prior expansion step. The radially folded tapered segments may be deployed toward the inner surface of the outer elastomeric jacket to expand the inner diameter of the lumen when inserting the medical delivery device into the lumen. In some embodiments, the step of deploying the radially folded tapered segments further includes widening gaps extending inward and outward between adjacent tapered segments. The step of deploying the plurality of radially folded tapered segments may further include bending the inner member at a plurality of inner connection points and a plurality of outer connection points. [Brief description of the drawings]

[0013] [Figure 1A] FIG. 13 is a diagram of a delivery device being deployed through a sheath. [Figure 1B]FIG. 13 is a diagram of a delivery device being deployed through a sheath. [Figure 1C] FIG. 1 is a side view of a conventional expandable sheath. [Diagram 2] FIG. 1 is a perspective view of a conventional expandable sheath. [Figure 3A] 1 is a cross-sectional view of a combined introducer and expandable sheath in an unexpanded state according to principles described herein. [Figure 3B] FIG. 3B is an enlarged view of FIG. 3A. [Figure 4] 1 is a cross-sectional view of a combined introducer and expandable sheath in an expanded state according to principles described herein. [Diagram 5] 1 illustrates a combined introducer and inner member of an expandable sheath according to principles described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The following description of specific examples of the inventive concept should not be used to limit the scope of the claims. Other examples, features, aspects, embodiments, and advantages will become apparent to those skilled in the art from the following description. As will be recognized, the device and / or method are capable of other different and obvious aspects, all of which are possible without departing from the spirit of the inventive concept. Thus, each drawing and each description should be regarded as illustrative in nature, and not restrictive.

[0015] For the purposes of this description, certain aspects, advantages, and novel features of the disclosed embodiments are described herein. The described methods, systems, and devices should not be construed as limiting in any way. Instead, the present disclosure is directed to all novel and non-obvious features and aspects of the various disclosed embodiments, each alone, and to various combinations and subcombinations of those features and aspects. The disclosed methods, systems, and devices are not limited to any particular aspect, feature, or combination thereof, and the disclosed methods, systems, and devices do not require that any particular advantage or advantages exist or that any particular problem or problems are solved.

[0016] It is to be understood that any feature, integer, feature, compound, chemical moiety, or group described in connection with a particular aspect, embodiment, or example of the invention may be applicable to any other aspect, embodiment, or example described herein, unless incompatible. All of the features disclosed herein (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 in which at least some of such features and / or steps are mutually exclusive. The invention is not limited to the details of any of the foregoing embodiments. The invention extends to any novel one or any novel combination of the features disclosed herein (including any accompanying claims, abstract, and drawings), or any novel one or any novel combination of the steps of any method or process so disclosed.

[0017] Any patent, publication, or other disclosure that is said to be incorporated by reference in whole or in part is to be understood to be incorporated herein only to the extent that the incorporated content does not contradict existing definitions, descriptions, or other disclosures set forth in this disclosure. Thus, to the extent necessary, the disclosures expressly set forth herein supersede any conflicting content incorporated herein by reference. Any content or portion thereof that is said to be incorporated by reference herein but that contradicts existing definitions, descriptions, or other disclosures set forth herein is incorporated only to the extent that there is no contradiction between the incorporated content and the existing disclosures.

[0018] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" one particular value and / or to "about" another particular value. When such a range is expressed, another embodiment 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 embodiment. It will be further understood that the endpoints of each range are significant in relation to the other endpoint, as well as independently of the other endpoint.

[0019] "Optional" or "optionally" means that the described event or circumstance may or may not occur, and that the description includes instances in which the event or circumstance occurs and instances in which the event or circumstance does not occur.

[0020] Throughout the description and claims of this specification, the word "comprise" and variations of this word such as "comprising" and "comprises" mean "including, but not limited to," and are not intended to exclude other additives, components, integers, or steps, etc. "Exemplary" means "an example of," and is not intended to convey an indication of a preferred or ideal embodiment. "Etc." is not used in a limiting sense, but rather is used for descriptive purposes.

[0021] The terms "proximal" and "distal" as used herein refer to regions of a sheath, catheter, or delivery assembly. "Proximal" means the region closest to the handle of the device, while "distal" means the region furthest from the handle of the device.

[0022] The terms "tube" or "tubular" as used herein are not meant to limit the shape to a circular cross-section. Instead, "tube" or "tubular" may refer to any elongated structure having a closed cross-section and a lumen extending axially therethrough. A tube may have several selectively positioned slits or openings. However, a tube nevertheless constitutes a closed structure sufficient to contain other components within its lumen.

[0023] As mentioned above, current procedures for inserting prosthesis delivery sheaths can be damaging to the vascular site. One reason for this includes the use of introducers (also called dilators), which are rigid, tapered solid rods that are inserted into the vascular site to gradually widen the site in preparation for the introduction of the sheath. Repeated insertion of these dilators can damage the vascular site and in some cases can dislodge plaque, which can lead to further complications during surgery. Additionally, expandable sheaths are being made to have smaller diameters, creating problems with accommodating the expansion mechanism in smaller spaces.

[0024] Disclosed herein is a combined introducer and expandable sheath (hereinafter introducer sheath). The introducer sheath constitutes an expandable sheath that can be inserted without the need for a preliminary dilation step using a conventional introducer. This one-piece structure serves the purpose of both introducer and sheath, eliminating the time and risk associated with dilating a vessel. Wide radial folds that increase the wall thickness of the inner member allow for a high degree of dilatation. The distal region is tapered to a rounded tip to facilitate dilatation of the vessel site. The proximal region is also tapered and is mated with a hemostasis valve housing.

[0025] 1A-1C show a conventional delivery device 110 and sheath 9 for delivering a prosthetic implant, such as a prosthetic heart valve, to a patient. It should be understood that the delivery device 110 described herein is merely exemplary and that other similar delivery systems can be used with the disclosed introducer sheath 10. The delivery device 110 illustrated herein generally includes a steerable guide catheter 114 and a balloon catheter 116 extending within the guide catheter 114. The guide catheter 114 and the balloon catheter 116 shown in FIGS. 1A-1B are adapted to slide longitudinally relative to one another to facilitate delivery and placement of the prosthetic heart valve to an implantation site within the patient's body. The guide catheter 114 includes a handle portion 120 and an elongated guide tube or shaft 122 extending from the handle portion 120 (FIG. 1B).

[0026] FIG. 1C shows a conventional expandable sheath 9 used to introduce the delivery device 110 and the prosthesis into the patient's body. The conventional expandable sheath 9 has a generally tubular configuration that defines a central lumen for guiding the passage of a delivery system for a prosthetic heart valve. At the proximal end, the expandable sheath 9 includes a hemostatic valve that prevents leakage of pressurized blood. Generally, in use, the distal end of the sheath 9 is advanced into the patient's blood vessel (such as the femoral artery) by sliding the lumen of the sheath 9 over an already inserted introducer (which may have the shape of a stiff tapered rod). The introducer is then removed through the lumen of the sheath 9. The delivery device 110 (with its implant) can then be inserted into the lumen of the sheath 9 through the hemostatic valve and advanced through the patient's vasculature where the implant is delivered and implanted in the patient.

[0027] Generally, as described above, when a conventional sheath 9 is inserted into a patient's blood vessel, an introducer (also called a dilator) must be inserted into the vasculature prior to the sheath 9. The introducer is sufficiently rigid so as not to distort or bend upon insertion, and then the more flexible conventional sheath 9 can be inserted into the blood vessel over the introducer. During a conventional procedure, the introducer is removed after the sheath 9 is inserted into the patient's blood vessel (and before the delivery device 110 is inserted through the sheath 9). In accordance with the principles described herein, the combined introducer and expandable sheath has a unitary structure that acts as both a sheath and an introducer, thus eliminating the preliminary steps of dilating the vascular site and removing the introducer prior to inserting the delivery device.

[0028] In one embodiment, the combined introducer and expandable sheath 10 (hereafter introducer sheath 10) includes an outer elastomeric jacket 330 that extends along the longitudinal axis of the sheath, as shown in Figure 2. Figures 3A and 4 show a cross section of the introducer sheath 10, where the same structure serves as both the sheath and the dilator. Figure 5 shows an embodiment of the inner member of the introducer sheath 10 (without the outer jacket elastomer 330 for convenience of illustration).

[0029] 3A illustrates a cross-section of the introducer sheath 10 in an unexpanded state. As shown, the introducer sheath 10 includes an outer elastomeric jacket 330 and an inner member 334 within the elastomeric jacket 330. In the unexpanded state, the inner member 334 defines an inner lumen 338 having an inner diameter ID. In an exemplary embodiment, the unexpanded inner diameter of the inner member 334 (i.e., the diameter of the inner lumen 338) may be about 0.04 inches (1.02 mm) (sized to fit a guidewire having an outer diameter of about 0.038 inches (0.97 mm). In the unexpanded state, the outer diameter OD of the introducer sheath 10, including the elastomeric jacket 330, may be from about 0.13 inches (3.30 mm) to about 0.18 inches (4.57 mm). In the expanded state (shown in FIG. 4), the inner diameter ID (expanded ID) of the inner member 334 can be from about 0.28 inches (7.11 mm) to about 0.33 inches (8.38 mm). This large expanded inner diameter ID is imparted by the large interior surface area provided by the many radial folds such that, in cross section, the total circumference of the unexpanded interior surface of the inner member 334 (including the surfaces within the radial folds) is greater than the circumference of a circle having a diameter of 0.30 inches (7.62 mm). In the expanded state, the outer diameter OD of the introducer sheath 10 can be from about 0.34 inches (8.64 mm) to about 0.37 inches (9.40 mm).

[0030] In an unexpanded state, the inner member 334 comprises a plurality of radially folded tapered segments 342. The inner lumen 338 is defined at least in part by a plurality of inner surfaces of the tapered segments 342. As shown in FIG. 3A, each tapered segment 342 widens as it extends radially outward (from an inner surface 343 of the tapered segment 342 to an outer surface 345 of the tapered segment 342). Generally, the thickness t of a tapered segment (measured from the inner surface 343 to the outer surface 345 when the introducer sheath 10 is in an unexpanded state) can range from about 0.045 inches (1.14 mm) to about 0.07 inches (1.78 mm). This thickness is relatively large compared to conventional sheaths, which generally have wall thicknesses of 0.010 inches (0.25 mm) to about 0.020 inches (0.51 mm). This relatively large thickness provides greater column strength to the introducer sheath 10 disclosed herein and helps eliminate the need for an introducer / dilator during the insertion procedure. Additionally, the relative thickness of the radial folds is greater than current expandable sheaths that utilize folds as part of the expansion mechanism. This larger thickness of the radial folds allows for a much higher degree of expansion (greater difference between unexpanded and expanded outer diameters) and facilitates the design of a sheath with a smaller profile.

[0031] An enlarged portion of FIG. 3A is shown in FIG. 3B. As shown in FIG. 3B, a selected tapered segment 347 is connected to a circumferentially adjacent first tapered segment 349 at an inner connection point 359, which is disposed adjacent to an inner lumen 338 defined by the inner member 334. The same selected tapered segment 347 is connected to a circumferentially adjacent second tapered segment 351 at an outer connection point 361, which is disposed adjacent to an outer surface 353 of the inner member 334. The connection points 359, 361 are radially thinner than the tapered segments 342 of the inner member 334, thereby causing the inner member 334 to thin and widen (e.g., as shown in FIG. 4) and extend along the circumference of the inner member 334. In this manner, the inner member 334 defines a plurality of outwardly extending gaps 355 that extend radially outward from the inner lumen 338, as shown in FIG. 3A. The outwardly extending gap 355 extends at least a portion of the length of the inner member 334, as shown in Figure 5. A plurality of inwardly extending gaps 357 extend radially inward from the outer surface of the inner member 334 and extend at least a portion of the length of the inner member 334, as shown in Figures 3A and 5. Each of the outwardly and inwardly extending gaps 355, 357 is defined at least in part by two adjacent tapered segments 342. During expansion, the inner member 334 flexes at the inward and outward connection points 359, 361, causing the tapered segments 342 to separate and widen the inwardly and outwardly extending gaps 355, 357, as shown in Figure 4.

[0032] FIG. 4 shows a cross section of the introducer sheath 10 in an expanded state. As shown, upon expansion, the elastomeric jacket 330 thins and the radially folded tapered segments 342 of the inner member 334 unfold towards the elastomeric jacket 330, expanding / widening the lumen 338. This expansion is achieved by inserting a medical delivery device. The device may be, for example, a transcatheter heart valve (THV) delivery device that is placed over a guidewire through the lumen of the inner member 334. The medical delivery device mechanically pushes open the tapered segments 342 of the inner member 334 as shown in FIG. 4. The outer elastomeric jacket 330 also expands to a larger outer diameter, and the medical device is inserted into the lumen 338 of the inner member 334. When the medical device is removed, the outer jacket material allows the folded inner member 334 to return to its unexpanded / folded state after the THV has passed, providing sufficient elasticity to provide hemostasis for the inner member exterior flow path.

[0033] FIG. 5 illustrates an inner member 334 of an introducer sheath 10 according to the principles described herein. As shown in its unexpanded / folded state, the inner member 334 is substantially cylindrical and can be pushed out by a proximal bump / taper 346. The proximal bump / taper 346 facilitates mating of the introducer sheath 10 to a wider hemostasis valve housing during the manufacturing process. Additionally, the ratio of outer diameter to inner diameter in the bump / taper 346 region is greater than the ratio of outer diameter to inner diameter in other regions along the length of the introducer sheath 10. This greater OD / ID allows for more wall material (greater wall thickness t) and better force transmission along the length of the introducer sheath 10. At the distal end, the inner member 334 may include a rounded tapered tip 350 to aid in dilatation of the vasculature during introduction of the introducer sheath 10.

[0034] The inner member 334 may be fixed relative to the outer elastomeric jacket or jackets, or may "float" relative to the outer sheath. For example, the inner member 334 and the outer elastomeric jacket 330 may be attached in a fixed position, such as by adhesive or thermal bonding, so that they do not move relative to one another or may be connected to one another. For example, the inner member 334 and the outer elastomeric jacket 330 may be attached to the tip 350 of the introducer sheath 10 or may be attached along a portion of the length of the introducer sheath 10.

[0035] The inner member 334 and the outer elastomeric jacket 330 may be formed independently or in an integral process. If formed independently, the elastomeric jacket 330 may be expanded by known means, the inner member 334 may be inserted into the elastomeric jacket 330, and the elastomeric jacket 330 may be contracted around the inner member 334. The compression of the elastomeric jacket 330 around the inner member 334 may be sufficient to reduce movement between the elastomeric jacket 330 and the inner member 334 sufficiently to perform the functions described herein.

[0036] The material of the inner member 334 provides the elastomeric jacket 330 with stiffness for catheter insertion, high lubricity for passage of guidewires and THVs, and high flexibility, and therefore low expansion forces. For example, the inner member 334 may be made of materials such as high density polyethylene, fluoropolymers, Teflon, or other materials. In some embodiments, the inner member 334 may have a hardness of about 45D to about 65D. Thus, the introducer sheath 10 provides sufficient stiffness to allow it to be inserted through the patient's skin and into the circulatory system. Alternatively, a co-extruded inner member is used to achieve the desired properties at the required location.

[0037] Although the foregoing embodiments of the present disclosure have been described in some detail for purposes of illustration and example for purposes of clarity and understanding, it will be apparent to those skilled in the art that certain changes and modifications may be practiced within the spirit and scope of the present disclosure. It is intended that the scope of the invention disclosed herein should not be limited by the particular disclosed embodiments described above, but should be determined solely by a fair reading of the following claims. [Explanation of symbols]

[0038] 9 Sheaths, conventional and expandable sheaths 10 Introducer sheath, combined introducer and expandable sheath 110 Conventional Delivery Devices 114 Guide Catheter 116 Balloon Catheter 120 Handle 122 Shaft 330 outer elastomer jacket 334 Inner member 338 Inner Lumen 342 Multiple radially folded tapered segments 343 Inside 345 Exterior 346 Proximal Bump / Taper 347 Tapered Segment 349 circumferentially adjacent first tapered segments 350 rounded tapered tip 355 Outward Gap 357 Inward Gap 359 Inner Connection Point 361 Outer connection point

Claims

1. A combined introducer and expandable sheath, comprising: an elongate inner member having a plurality of radially folded tapered segments in an unexpanded state extending longitudinally along a longitudinal axis, the inner member having an inner diameter and defining a longitudinally extending inner lumen; an elongated outer elastomeric jacket extending at least partially over the inner member and having a spring bias toward the inner lumen of the inner member; a plurality of outwardly extending gaps extending radially outward from the inner lumen and extending between adjacent tapered segments; and a plurality of inwardly extending gaps extending radially inward from an outer surface of the inner member.

1. A combined introducer and expandable sheath comprising:

2. 2. The combined introducer and expandable sheath of claim 1, wherein the plurality of radially folded tapered segments deploy toward an inner surface of the outer elastomeric jacket to expand the inner diameter of the inner lumen upon insertion of a prosthesis into the inner lumen.

3. The combined introducer and expandable sheath of claim 1 , wherein the inner member further comprises a rounded, tapered distal tip.

4. 4. The combined introducer and expandable sheath of claim 1, wherein the inner member has a fixed longitudinal position relative to the outer elastomeric jacket.

5. 5. The combined introducer and expandable sheath of claim 1, wherein in an unexpanded state, the inner lumen is defined at least in part by inner surfaces of the plurality of radially folded tapered segments.

6. 6. The combined introducer and expandable sheath of claim 1, wherein at least one of the plurality of tapered segments has a thickness t of the at least one tapered segment measured in an unexpanded state from an inner surface of the at least one tapered segment to an outer surface of the at least one tapered segment, in the range of 0.045 inches (1.14 mm) to 0.07 inches (1.78 mm).

7. 7. The combined introducer and expandable sheath of claim 1, wherein each of the plurality of radially folded tapered segments widens as it expands radially outward.

8. 8. The combined introducer and expandable sheath of claim 7, wherein each of the plurality of radially folded tapered segments is connected to a first circumferentially adjacent one of the plurality of radially folded tapered segments at an inner connection point and to a second circumferentially adjacent one of the plurality of radially folded tapered segments at an outer connection point.

9. 9. The combined introducer and expandable sheath of claim 8, wherein in the unexpanded state, the inner connection point is disposed adjacent to the inner lumen of the inner member and the outer connection point is disposed adjacent to an outer surface of the inner member.

10. 10. The combined introducer and expandable sheath of claim 8 or 9, wherein the inner and outer connection points are radially thinner than the radially folded tapered segments.

11. 11. The combined introducer and expandable sheath of claim 9 or 10, wherein the inner member thins and flares to extend around a circumference of the inner member.

12. The combined introducer and expandable sheath of claim 1 , wherein the inwardly and outwardly extending gaps each extend at least a portion of the length of the inner member.

13. 1. A method of delivering a prosthetic device, comprising: Positioning the combined introducer and expandable sheath at a delivery site, the combined introducer and expandable sheath comprising: an elongate inner member having a plurality of radially folded tapered segments in an unexpanded state extending longitudinally along a longitudinal axis, the inner member defining an inner lumen having an inner diameter; an elongated outer elastomeric jacket extending at least partially over the inner member and having a spring bias toward the inner lumen of the inner member; Equipped with the inner member providing rigidity to the combined introducer and expandable sheath during introduction to the delivery site; introducing a prosthesis into the inner lumen of the inner member; advancing the prosthesis through the inner lumen whereby the prosthesis exerts a localized radially outward force on an inner surface of the inner member; locally deploying the radially folded tapered segments of the inner member to an expanded configuration, the deploying of the radially folded tapered segments further comprising widening inwardly and outwardly extending gaps between adjacent tapered segments; pushing the inner member out of the outer elastomeric jacket after the prosthesis has exited the lumen to return to an unexpanded state; A method of delivering a prosthetic device comprising:

14. 14. The method of delivering a prosthetic device according to claim 13, further comprising the step of placing the combined introducer and expandable sheath at the delivery site without performing any prior expansion step.

15. 14. The method of delivering a prosthetic device according to claim 13, wherein the step of deploying the radially folded tapered segments further comprises bending the inner member at a plurality of inner connection points and a plurality of outer connection points.

16. A combined introducer and expandable sheath, comprising: an elongate inner member having a plurality of radially folded tapered segments in an unexpanded state extending longitudinally along a longitudinal axis, the inner member having an inner diameter and defining a longitudinally extending inner lumen; an elongated outer elastomeric jacket extending at least partially over the inner member and having a spring bias toward the inner lumen of the inner member; Equipped with at least one of the plurality of tapered segments has a thickness t of the at least one tapered segment measured in an unexpanded state from an inner surface of the at least one tapered segment to an outer surface of the at least one tapered segment, the thickness t being in the range of 0.045 inches (1.14 mm) to 0.07 inches (1.78 mm); A combined introducer and expandable sheath.

17. 17. The combined introducer and expandable sheath of claim 16, wherein the plurality of radially folded tapered segments deploy toward an inner surface of the outer elastomeric jacket to expand the inner diameter of the inner lumen upon insertion of a prosthesis into the inner lumen.

18. 20. The combined introducer and expandable sheath of claim 16, wherein the inner member further comprises a rounded, tapered distal tip.

19. 19. The combined introducer and expandable sheath of any one of claims 16 to 18, wherein the inner member has a fixed longitudinal position relative to the outer elastomeric jacket.

20. 20. The combined introducer and expandable sheath of any one of claims 16 to 19, wherein in an unexpanded state, the inner lumen is defined at least in part by inner surfaces of the plurality of radially folded tapered segments.

21. 21. The combined introducer and expandable sheath of any one of claims 16 to 20, wherein each of the plurality of radially folded tapered segments widens as it expands radially outward.

22. 22. The combined introducer and expandable sheath of claim 21, wherein each of the plurality of radially folded tapered segments is connected to a first circumferentially adjacent one of the plurality of radially folded tapered segments at an inner connection point and to a second circumferentially adjacent one of the plurality of radially folded tapered segments at an outer connection point.

23. 17. The combined introducer and expandable sheath of claim 16, wherein in the unexpanded state, the inner connection point is disposed adjacent to the inner lumen of the inner member and the outer connection point is disposed adjacent to an outer surface of the inner member.

24. 22. The combined introducer and expandable sheath of claim 16 or 21, wherein the inner and outer connection points are radially thinner than the radially folded tapered segments.

25. 23. The combined introducer and expandable sheath of claim 21 or 22, wherein the inner member thins and flares to extend around a circumference of the inner member.

26. 26. The combined introducer and expandable sheath of any one of claims 21 to 25, further comprising a plurality of outwardly extending gaps extending radially outward from the inner lumen and extending between adjacent tapered segments, and a plurality of inwardly extending gaps extending radially inward from an outer surface of the inner member, each of the inwardly and outwardly extending gaps extending at least a portion of the length of the inner member.

27. 1. A method of delivering a prosthetic device, comprising: Positioning the combined introducer and expandable sheath at a delivery site, the combined introducer and expandable sheath comprising: an elongate inner member having a plurality of radially folded tapered segments in an unexpanded state extending longitudinally along a longitudinal axis, the inner member defining an inner lumen having an inner diameter; an elongated outer elastomeric jacket extending at least partially over the inner member and having a spring bias toward the inner lumen of the inner member; Equipped with the inner member providing rigidity to the combined introducer and expandable sheath during introduction to the delivery site; introducing a prosthesis into the inner lumen of the inner member; advancing the prosthesis through the inner lumen whereby the prosthesis exerts a localized radially outward force on an inner surface of the inner member; locally deploying the radially folded tapered segments of the inner member to an expanded configuration, the deploying the radially folded tapered segments further comprising bending the inner member at a plurality of inner connection points and a plurality of outer connection points; pushing the inner member out of the outer elastomeric jacket after the prosthesis has exited the lumen to return to an unexpanded state; A method of delivering a prosthetic device comprising:

28. 30. The method of delivering a prosthetic device according to claim 27, further comprising the step of placing the combined introducer and expandable sheath at the delivery site without performing any prior expansion step.

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