Expandable sheath for introducing an intravascular delivery device into the body - Patent Application 20070122997

Abstract

Embodiments of the expandable sheath can be used in conjunction with a catheter assembly to introduce a prosthetic device, such as a heart valve, into a patient. Such embodiments can minimize trauma to the blood vessel by allowing a portion of the introducer sheath to temporarily expand to accommodate a delivery apparatus and then return to its original diameter once the prosthetic device has passed. Some embodiments include a sheath with an inner layer and an outer layer, where folds of the inner layer extend through slits in the outer layer and portions of the outer layer overlap the folds of the inner layer. Some embodiments include a resilient outer cover disposed outside the outer layer. Embodiments of the expandable sheath of the present invention can provide advantages over prior art introducer sheaths by avoiding the need for multiple insertions to expand the blood vessel.

Description

[Technical Field]

[0001] The present application relates to embodiments of a sheath for use in catheter-based techniques for repairing and / or replacing heart valves and for delivering prosthetic devices, such as prosthetic valves, to the heart via a patient's vasculature. [Background technology]

[0002] Intravascular delivery catheter assemblies are used to implant prosthetic devices, such as prosthetic valves, in locations within the body that are not easily accessible by surgery or where access without invasive surgery is desirable. For example, aortic, mitral, tricuspid, and / or pulmonary valve prosthetic valves can be delivered to treatment sites using minimally invasive surgical techniques.

[0003] An introducer sheath can be used to safely introduce a delivery device into a patient's vascular system (e.g., the femoral artery). The introducer sheath generally includes an elongated sleeve that is inserted into the vascular system and a housing that houses one or more sealing valves, allowing the delivery device to be placed in fluid communication with the vascular system with minimal blood loss. Conventional introducer sheaths typically require a tubular loader inserted through a seal within the housing to provide an unobstructed path through the housing for a valve mounted on the balloon catheter. Because the conventional loader extends from the proximal end of the introducer sheath, it reduces the available working length of the delivery device that can be inserted through the sheath and into the body.

[0004] Prior to introducing a delivery system, conventional methods of accessing a vessel, such as the femoral artery, involve dilating the vessel using multiple dilators or sheaths of progressively increasing diameter. This repeated insertion and vessel dilation increases the time required for the procedure and can increase the risk of injury to the vessel.

[0005] Radially expanding intravascular sheaths have been disclosed, and such sheaths tend to have complex mechanisms, such as ratcheting mechanisms, that maintain the shaft or sheath in an expanded configuration when a device of a diameter larger than the original diameter of the sheath is introduced.

[0006] However, delivering and / or removing prosthetic devices and other materials into and from patients still poses significant risks to the patient. Additionally, accessing the vessel remains a challenge due to the relatively large profile of the delivery system, which can cause longitudinal and radial tearing of the vessel during insertion. The delivery system can also detach calcified plaque within the vessel, posing an additional risk of blood clots caused by the detached plaque. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent Application Serial No. 12 / 249,867 [Patent Document 2] U.S. Patent Application No. 13 / 312,739 [Patent Document 3] U.S. Patent Application Serial No. 14 / 248,120 [Patent Document 4] U.S. Patent Application Serial No. 14 / 324,894 [Patent Document 5] U.S. Patent Application No. 15 / 057,953 [Patent Document 6] U.S. Patent Application No. 15 / 997,587 [Patent Document 7] U.S. Patent Application No. 16 / 149,953 [Patent Document 8] U.S. Patent Application Serial No. 16 / 149,956 [Patent Document 9] U.S. Patent Application Serial No. 16 / 149,960 [Patent Document 10] U.S. Patent Application Serial No. 16 / 149,969 [Patent Document 11] U.S. Patent Application Publication No. 2010 / 0094392 Summary of the Invention [Problem to be solved by the invention]

[0008] Thus, there remains a need in the art for improved introducer sheaths for endovascular systems used to implant valves and other prosthetic devices. [Means for solving the problem]

[0009] Expandable sheath embodiments of the present invention can minimize trauma to the vessel by allowing a portion of the introducer sheath to temporarily expand to accommodate a delivery system and then return to its original diameter once the delivery system has passed. Some embodiments can include a sheath with a smaller profile than that of prior art introducer sheaths. Furthermore, because only one sheath is required rather than several different sized sheaths, certain embodiments can reduce the length of time required for the procedure as well as the risk of longitudinal or radial vessel tearing or plaque detachment. Expandable sheath embodiments of the present invention can require only a single vessel insertion, as opposed to multiple insertions required for vessel expansion.

[0010] One embodiment of a sheath for introducing a prosthetic device includes an inner layer and an outer layer. At least a portion of the sheath can be designed or configured to locally expand from a first diameter to a second diameter as the prosthetic device is pushed through the lumen of the sheath, and then at least partially return to the first diameter once the prosthetic device has passed. Some embodiments can further include a resilient outer cover disposed about the outer layer.

[0011] The inner layer can be composed of polytetrafluoroethylene (PTFE), polyimide, polyetheretherketone (PEEK), polyurethane, nylon, polyethylene, polyamide, or a combination thereof. The outer layer can be composed of PTFE, polyimide, PEEK, polyurethane, nylon, polyethylene, polypropylene, polyamide, polyether block amide, polyether block ester copolymer, thermoset silicone, latex, polyisoprene rubber, high density polyethylene (HDPE), Tecoflex™, or a combination thereof. In one embodiment, the inner layer can be composed of PTFE, and the outer layer can be composed of a combination of HDPE and Tecoflex™. If present, the elastic outer cover can comprise any suitable material, such as any suitable heat shrink material. Examples include Pebax, polyurethane, silicone, and / or polyisoprene.

[0012] The disclosed sheath embodiments include opposing proximal and distal ends. In some embodiments, a hemostatic valve can be included at or near the proximal end of the sheath. In some embodiments, the outer diameter of the sheath decreases along a gradient from the proximal end to the distal end of the sheath. In other embodiments, the outer diameter of the sheath is substantially constant along at least a majority of the length of the sheath.

[0013] An embodiment of a sheath for introducing a prosthetic device into a body can include a continuous inner layer defining a lumen therethrough, the inner layer having a folded portion, and a discontinuous outer layer having an overlapping portion and an underlying portion. In some embodiments, the inner layer can have at least two folded portions. The outer layer can be configured such that the overlapping portion overlaps the underlying portion, where at least a portion of the folded portion of the inner tubular layer is disposed between the overlapping portion and the underlying portion. At least a portion of the sheath is configured to expand to accommodate the prosthetic device.

[0014] In some embodiments, at least a portion of the sheath is configured such that multiple segments of the sheath locally expand, one at a time, from a resting configuration having a first diameter to an expanded configuration having a second diameter greater than the first diameter to facilitate passage of a prosthetic device through the lumen of the inner layer. Each segment can have a defined length along the longitudinal axis of the sheath, and each sheath segment can be configured to at least partially return to the first diameter upon passage of a prosthetic device. In some embodiments, when each sheath segment is in the expanded configuration, a length of folded portion corresponding to the length of the segment at least partially unfolds (e.g., by separating and / or straightening). A length of overlapping portion corresponding to the length of the segment can be configured to move relative to the underlying portion as each sheath segment expands from the resting configuration to the expanded configuration.

[0015] In one specific embodiment, the inner layer is composed of PTFE and the outer layer is composed of HDPE and / or Tecoflex™. The inner and outer layers can be heat fused together in some embodiments. In some embodiments, the inner layer is composed of woven and / or braided filaments, such as PTFE, PET, PEEK, and / or nylon yarn filaments.

[0016] Some disclosed expandable sheaths can further include a resilient outer cover disposed on the outer surface of the outer layer. The resilient outer cover can comprise, for example, heat shrink tubing. Some sheaths include one or more radiopaque markers or fillers, such as a C-shaped band located between the inner and outer layers near the distal end of the sheath. Some examples include a soft tip secured to the distal end of the sheath.

[0017] In some embodiments, the inner layer can include at least one folded portion and at least one weakened portion. The discontinuous outer layer has an outer surface and an inner surface and a longitudinal gap, and a portion of the inner layer can extend through the longitudinal gap. The at least one folded portion of the inner layer can be located adjacent to a portion of the outer surface of the outer layer. In some embodiments, the weakened portion can include a scoreline along at least a portion of the inner layer and / or a slit along at least a portion of the inner layer. The weakened portion can be located in the at least one folded portion of the inner layer. In some embodiments, the longitudinal gap can be located between a first end and a second end of the outer layer.

[0018] In some embodiments, the expandable sheath can include a hydrophilic inner liner defining a generally horseshoe-shaped lumen therethrough, the inner liner including at least two weakened portions and a resilient covering disposed radially outward of the inner liner. In some embodiments, when the sheath is in the expanded configuration, the inner liner splits at the weakened portions to form a discontinuous inner liner.

[0019] Methods for fabricating a sheath are also disclosed. One method includes providing a mandrel having a first diameter, providing a first tube having a second diameter greater than the first diameter, mounting the first tube onto the mandrel, collecting excess material from the first tube, and folding the excess material to one side to form a folded portion of the inner layer. A second tube can then be provided, and the second tube can be cut to form a coiled layer. Adhesive can be applied to at least a portion of the coiled layer, and the coiled layer can be mounted on the first tube such that the adhesive is disposed between the first tube and the coiled layer. The folded portion can be elevated to position a portion of the coiled layer under the folded portion.

[0020] Some methods include applying heat to the first tube, the coiled layer, and the mandrel to heat-fuse the first tube and the coiled layer together. In some methods, a resilient outer covering can be secured to an outer surface of the coiled layer. In some methods, a soft tip portion can be coupled to a distal end of the expandable sheath to facilitate passing the expandable sheath through a patient's vasculature.

[0021] In another embodiment, a sheath for introducing a prosthetic device into a body comprises an inner tubular layer including a longitudinal slit and partially defining an inner lumen, an outer tubular layer surrounding the inner layer, the outer tubular layer including longitudinally extending folding flaps that overlie a portion of the outer surface of the outer layer when the sheath is in an unexpanded state, and a tie layer disposed therebetween and bonding the inner tubular layer to the outer tubular layer, such that outward radial force from a prosthetic device moving through the lumen widens the longitudinal slit and deploys the folding flaps, allowing the sheath to expand.

[0022] In yet another embodiment, a method of delivering a prosthetic device to a treatment site includes inserting an expandable sheath into a subject's vasculature; advancing a prosthetic device through a lumen of the expandable sheath, the prosthetic device exerting an outward radial force on an inner tubular layer of the expandable sheath; expanding a width of a longitudinal slit in the inner tubular layer via the outward radial force; deploying a longitudinally extending flap in the outer tubular layer via the outward radial force; reducing a width of the longitudinal slit in the inner tubular layer upon removal of the outward radial force; and delivering the prosthetic device to the treatment site.

[0023] In yet another embodiment, a method of manufacturing a sheath for introducing a prosthetic device into a body includes the steps of loading an inner layer onto a tapered mandrel, applying heat to the inner layer, flaring a proximal section of the inner layer under heat, attaching a tie layer to a main section of the inner layer, cutting longitudinal slits in the inner layer and the tie layer, loading the inner layer and tie layer with the longitudinal slits onto a mandrel, loading an outer layer over the tie layer, folding the outer layer to create a longitudinally extending flap, heat setting the folded outer layer, and removing the expandable sheath from the mandrel.

[0024] In yet another embodiment, a sheath for introducing a prosthetic device into a body comprises: an inner layer including first and second folds and overlapping folds extending circumferentially between the first and second folds (e.g., when the sheath is in an unexpanded configuration), the folds including at least two radial overlaps of the inner layer, the continuous inner layer defining a lumen therethrough; a discontinuous outer layer having an overlapping portion and an underlying portion and extending at least partially around the inner layer, with at least a portion of the folded portion of the inner layer disposed between the overlapping portion and the underlying portion; an adhesive layer (e.g., a tie layer) disposed between the inner layer and the outer layer to at least partially adhere the inner layer to the outer layer; an outer jacket extending around the outer layer; At least a portion of the sheath is configured to locally expand from an unexpanded configuration in which the lumen has a first diameter to an expanded configuration in which the lumen has a second diameter greater than the first diameter due to a radially outward force exerted by the medical device against the inner layer, and then locally contract as the prosthetic device passes through the lumen to at least partially return to the unexpanded configuration.

[0025] In another embodiment, a sheath for introducing a prosthetic device into a body comprises: a continuous inner layer including first and second folds and overlapping folds extending circumferentially between the first and second folds, the folds including at least two radial overlaps of the inner layer, and defining a lumen therethrough; a discontinuous outer layer having an overlapping portion and an underlying portion and extending at least partially around the inner layer, with at least a portion of the folded portion of the inner layer disposed between the overlapping portion and the underlying portion; a tie layer disposed between the inner layer and the outer layer to at least partially adhere the inner layer to the outer layer; an outer jacket extending around the outer layer; At least a portion of the sheath is configured to locally expand from an unexpanded configuration in which the lumen has a first diameter to an expanded configuration in which the lumen has a second diameter greater than the first diameter due to a radially outward force exerted by the medical device against the inner layer, and then locally contract back to at least partially the unexpanded configuration as the prosthetic device passes through the lumen, and a lubricant is provided between the outer jacket and the outer layer.

[0026] In yet another embodiment, a method of delivering a prosthetic device to a treatment site includes: introducing an expandable sheath into the vascular system of a subject; advancing a prosthetic device through a lumen of the expandable sheath, the prosthetic device exerting an outward radial force on an inner tubular layer of the expandable sheath; locally expanding the lumen of the sheath at the local axial location due to an outward radial force exerted by the prosthetic device against an inner surface of the lumen during advancement of the prosthetic device through the local axial location, The step of locally expanding the lumen comprises: circumferentially moving the first fold of the inner layer proximate the second fold of the inner layer to shorten an overlap of the inner layer extending circumferentially between the first and second folds; and expanding the outer layer along at least one elongated gap generally aligned with the axis of the lumen, the elongated gap being disposed adjacent to at least one of the folds; Expanding the outer layer along the at least one elongated gap includes moving a first portion of the outer layer away from a second portion of the outer layer as the first fold moves proximate the second fold, the gap being defined between the first and second portions; the inner layer and the outer layer being at least partially adhered via a tie layer extending therebetween; contracting the lumen of the sheath by at least partially returning to an unexpanded configuration as the prosthetic device passes through the lumen; and delivering the prosthetic device to the treatment site.

[0027] In yet another embodiment, a method for manufacturing a sheath for introducing a prosthetic device into a body includes: providing a continuous inner layer including first and second folds and overlapping folds extending circumferentially between the first and second folds, the folds including at least two radial overlaps of the inner layer, the continuous inner layer defining a lumen therethrough; providing a discontinuous outer layer having an overlapping portion and an underlying portion and extending at least partially around the inner layer, with at least a portion of the folded portion of the inner layer disposed between the overlapping portion and the underlying portion; providing a tie layer disposed between the inner layer and the outer layer to at least partially adhere the inner layer to the outer layer; joining the inner layer to the outer layer; providing a lubricant at a location proximate to a longitudinally extending edge of the overlapping portion; providing an outer jacket about the outer layer and joining the outer jacket to the outer layer at at least one of their proximal and distal ends.

[0028] In another embodiment, a sheath for introducing a prosthetic device into a body comprises: a continuous inner layer including first and second folds and overlapping folds extending circumferentially between the first and second folds, the folds including at least two radial overlaps of the inner layer, and defining a lumen therethrough; a discontinuous outer layer having an overlapping portion and an underlying portion and extending at least partially around the inner layer, with at least a portion of the folded portion of the inner layer disposed between the overlapping portion and the underlying portion; a coiled wire along the length of the sheath that provides a uniform bend in the sheath to prevent kinking; a tie layer disposed between the inner layer and the outer layer to at least partially adhere the inner layer to the outer layer; an outer jacket extending around the outer layer; At least a portion of the sheath is configured to locally expand from an unexpanded configuration in which the lumen has a first diameter to an expanded configuration in which the lumen has a second diameter greater than the first diameter due to a radially outward force exerted by the medical device against the inner layer, and then locally contract back at least partially to the unexpanded configuration as the prosthetic device passes through the lumen.

[0029] In yet another embodiment, a method of delivering a prosthetic device to a treatment site includes: introducing an expandable sheath into the vascular system of a subject; advancing a prosthetic device through a lumen of the expandable sheath, the prosthetic device exerting an outward radial force on an inner tubular layer of the expandable sheath; locally expanding the lumen of the sheath at the local axial location due to an outward radial force exerted by the medical device against an inner surface of the lumen during advancement of the prosthetic device through the local axial location, The step of locally expanding the lumen comprises: circumferentially moving the first fold of the inner layer proximate the second fold of the inner layer to shorten an overlapping portion of the inner layer extending circumferentially between the first and second folds; and expanding the outer layer along at least one elongated gap generally aligned with the axis of the lumen located adjacent to at least one of the folds; Extending the outer layer along the at least one elongated gap includes moving a first portion of the outer layer away from a second portion of the outer layer as the first fold moves proximate the second fold, a gap being defined between the first and second portions; a coiled wire structure embedded in the inner layer and / or the outer layer, the coiled wire increasing kink resistance and column strength of the expandable sheath; contracting the lumen of the sheath by at least partially returning to an unexpanded configuration as the prosthetic device passes through the lumen; and delivering the prosthetic device to the treatment site.

[0030] The foregoing and other features and advantages of the present invention will become more apparent from the following detailed description which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is an elevational view of a sheath according to the present disclosure together with an intravascular delivery device for implantation of a prosthetic valve. [Figure 2A] FIG. 2A is a cross-sectional view of an example sheath for introducing a prosthetic device into a patient. [Figure 2B]FIG. 2B is a cross-sectional view of an example sheath for introducing a prosthetic device into a patient. [Figure 2C] FIG. 2C is a perspective view of one component of an example sheath for introducing a prosthetic device into a patient. [Figure 2D] FIG. 2D is a cross-sectional view of an example sheath for introducing a prosthetic device into a patient. [Figure 3] FIG. 3 is an elevational view of the sheath shown in FIG. [Figure 4A] FIG. 4A is an elevational view of one embodiment of a sheath according to the present disclosure having a varying outer diameter. [Figure 4B] FIG. 4B is an elevational view of one embodiment of a sheath according to the present disclosure having a varying outer diameter. [Figure 5] FIG. 5 is an elevational view of one embodiment of a sheath expanded in a first location to house a delivery system. [Figure 6] FIG. 6 is an elevational view of an embodiment of a sheath expanded at a second location further from the sheath. [Figure 7] FIG. 7 is a cross-sectional view of another embodiment of a sheath further comprising an outer covering or shell. [Figure 8] FIG. 8 is an elevational view of one embodiment of a sheath with an outer covering or shell. [Figure 9] FIG. 9 is a partial elevational view of one embodiment of an intermediate tubular layer that can be used to construct a sheath according to the present disclosure. [Figure 10] FIG. 10 is a partial elevational view of another embodiment of an intermediate tubular layer having a variable diamond design. [Figure 11] FIG. 11 is a partial elevational view of another embodiment of an intermediate tubular layer having a diamond design with spring struts. [Figure 12] FIG. 12 is a partial elevation view of another embodiment of an intermediate tubular layer having a diamond design with straight struts. [Figure 13]FIG. 13 is a partial elevation view of another embodiment of an intermediate tubular layer having a sawtooth design with spring struts. [Figure 14] FIG. 14 is a partial elevation view of another embodiment of an intermediate tubular layer having a sawtooth design with straight struts. [Figure 15] FIG. 15 is a partial elevation view of another embodiment of an intermediate tubular layer having a diamond design with straight struts. [Figure 16] FIG. 16 is a partial elevational view of another embodiment of an intermediate tubular layer having a helical or spiral design. [Figure 17] FIG. 17 is a partial elevation view of another embodiment of an intermediate tubular layer having a diamond design with non-straight struts. [Figure 18] FIG. 18 is a partial elevation view of another embodiment of an intermediate tubular layer having an alternative diamond design with non-straight struts. [Figure 19] FIG. 19 is a partial elevational view of another embodiment of an intermediate tubular layer having yet another diamond design with non-straight struts. [Figure 20] FIG. 20 is a partial elevation view of another embodiment of an intermediate tubular layer having a diamond design with struts. [Figure 21] FIG. 21 is a partial elevational view of another embodiment of an intermediate tubular layer having a similar design to that shown in FIG. 20, but with additional struts. [Figure 22] FIG. 22 is a partial elevation view of another embodiment of an intermediate tubular layer having a diamond design with spiral struts. [Figure 23] FIG. 23 is a partial elevation view of another embodiment of an intermediate tubular layer having a diamond design with adjacent struts. [Figure 24] FIG. 24 is a cross-sectional view of one embodiment of a sheath having a longitudinal notch. [Figure 25] FIG. 25 is a cross-sectional view of one embodiment of a sheath having a longitudinal cut in the inner layer. [Figure 26]FIG. 26 is a cross-sectional view of one embodiment of a sheath having multiple notches or cuts in the outer tubular layer. [Figure 27A] FIG. 27A is a cross-sectional view of one embodiment of a sheath in which the outer tubular layer includes a longitudinal cut and in the unexpanded configuration, the inner layer extends into the gap created by the cut in the outer tubular layer. [Figure 27B] FIG. 27B is a cross-sectional view of one embodiment of a sheath in an unexpanded configuration. [Figure 27C] FIG. 27C is a cross-sectional view of one embodiment of a sheath in an unexpanded configuration. [Figure 27D] FIG. 27D is a cross-sectional view of one embodiment of a sheath in an unexpanded configuration. [Figure 27E] FIG. 27E is a cross-sectional view of one embodiment of a sheath in an unexpanded configuration. [Figure 28] FIG. 28 is a cross-sectional view of the sheath of FIG. 27A in an expanded configuration. [Figure 29A] FIG. 29A is a cross-sectional view of one embodiment of a sheath having overlapping sections. [Figure 29B] FIG. 29B is a cross-sectional view of one embodiment of a sheath having overlapping sections. [Figure 29C] FIG. 29C is a cross-sectional view of one embodiment of a sheath having overlapping sections. [Figure 29D] FIG. 29D is a cross-sectional view of one embodiment of a sheath having overlapping sections. [Figure 30] FIG. 30 is a block diagram of one embodiment of a method for fabricating a sheath according to the present disclosure. [Figure 31] FIG. 31 is a block diagram of another embodiment of a method for fabricating a sheath according to the present disclosure. [Figure 32A] FIG. 32A is a cross-sectional view of one method step of the method shown in FIGS. [Figure 32B] FIG. 32B is a cross-sectional view of one method step of the method shown in FIGS. [Figure 32C]FIG. 32C is a cross-sectional view of one method step of the method shown in FIGS. [Figure 32D] FIG. 32D is a cross-sectional view of one method step of the method shown in FIGS. [Figure 32E] FIG. 32E is a cross-sectional view of one method step of the method shown in FIGS. [Figure 32F] FIG. 32F is a cross-sectional view of one method step of the method shown in FIGS. [Figure 32G] FIG. 32G is an elevational view of one method step of the method shown in FIGS. [Figure 32H] FIG. 32H is a cross-sectional view of one method step of the method shown in FIGS. [Figure 33] FIG. 33 is a plan view of one embodiment of a sheath having partial slits or score lines. [Figure 34] FIG. 34 is a plan view of another embodiment of a sheath having partial slits or score lines. [Figure 35] FIG. 35 is an elevational view of an expandable sheath and exemplary housing according to the present disclosure. [Figure 36] 36 is an enlarged cutaway view of the distal end of the sheath of FIG. 35. FIG. [Figure 37] 37 is a cross-sectional view of the distal end of the sheath of FIG. 35 taken along line 37-37 in FIG. [Figure 38] 38 is a cross-sectional view of the proximal end of the sheath of FIG. 35 taken along line 38-38 in FIG. [Figure 39] 39 is a cross-sectional view of the sheath of FIG. 35 in the resting (unexpanded) configuration taken along line 39-39 in FIG. [Figure 40] FIG. 40 is a cross-sectional view of the sheath of FIG. 39 in an expanded configuration. [Figure 41] FIG. 41 is a cross-sectional view of an expandable sheath having a resilient outer cover according to another embodiment. [Figure 42]42 is a cross-sectional view of the sheath of FIG. 41 taken along line 42-42 in FIG. [Figure 43] FIG. 43 is a cross-sectional view of the sheath shown in FIG. 42 in an expanded configuration. [Figure 44] FIG. 44 is a cross-sectional view of another embodiment of an expandable sheath. [Figure 45] FIG. 45 shows the sheath of FIG. 44 in an expanded configuration. [Figure 46] FIG. 46 is a cross-sectional view of another embodiment of an expandable sheath. [Figure 47] FIG. 47 shows the sheath of FIG. 46 in an expanded configuration. [Figure 48] FIG. 48 is a cross-sectional view of another embodiment of an expandable sheath in accordance with the present disclosure. [Figure 49] FIG. 49 is a cross-sectional view of another embodiment of an expandable sheath. [Figure 50] FIG. 50 is a cross-sectional view of an exemplary sheath in an unexpanded configuration. [Figure 51] FIG. 51 is a cross-sectional view of the sheath of FIG. 50 in an expanded configuration. [Figure 52] FIG. 52 is a cross-sectional view of the sheath of FIG. 50, including an outer jacket. [Figure 53] 53 is a cross-sectional view of the sheath of FIG. 35 in a resting (unexpanded) configuration, including the outer jacket, taken along line 39-39 in FIG. [Figure 54] 54 is a cross-sectional view of the sheath of FIG. 53 in the resting (unexpanded) configuration taken along line 39-39 in FIG. [Figure 55] FIG. 55 is a cross-sectional view of the sheath of FIG. 54 in an expanded configuration. [Figure 56] FIG. 56 is a cross-sectional view of the sheath of FIG. 54 in a rest (unexpanded) configuration, including a lubricant between the outer layer and the outer jacket. [Figure 57] FIG. 57 is a cross-sectional view of the sheath of FIG. 54 in a resting (unexpanded) configuration, including a lubricant and a bonding strip. [Figure 58]58 is a bottom perspective view of the sheath of FIG. 57. FIG. [Figure 59] 59 is a bottom perspective view of the sheath of FIG. 57. FIG. [Figure 60] FIG. 60 is a top perspective view of the sheath of FIG. [Figure 61] 61 is a cross-sectional view of the sheath of FIG. 63 in the resting (unexpanded) configuration taken along line 39-39 in FIG. [Figure 62] FIG. 62 is an elevational view of an expandable outer jacket according to another embodiment. [Figure 63] 63 is a cross-sectional view of the expandable sheath of FIG. 64 taken along section line AA of FIG. 62. [Figure 64] 64 is a cross-sectional view of the expandable outer jacket in the rest (unexpanded) configuration taken along section line BB of FIG. 62. [Figure 65] 65 is a partial cross-sectional view of the outer jacket of FIG. 64. FIG. [Figure 66] 66 is a cross-sectional view of another exemplary outer jacket in a resting (unexpanded) configuration, including a single reinforcing member, taken along section line BB of FIG. 62. DETAILED DESCRIPTION OF THE INVENTION

[0032] As used in this application and the claims, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise. Furthermore, the term "includes" means "comprises." Furthermore, the terms "coupled" and "associated" generally mean electrically, electromagnetically, and / or physically (e.g., mechanically or chemically) coupled or connected and do not exclude the presence of intermediate elements between coupled or associated items.

[0033] Although the operations of exemplary embodiments of the disclosed methods may be described in a particular order for convenience of presentation, it should be understood that the disclosed embodiments may encompass orders of operations other than the particular order disclosed. For example, operations described in a sequence may, in some cases, be rearranged or performed simultaneously. Furthermore, descriptions and disclosures provided in connection with one particular embodiment are not limited to that embodiment and may apply to any disclosed embodiment.

[0034] Moreover, for simplicity, the accompanying figures may not show the various ways in which the disclosed systems, methods, and apparatus can be used in combination with other systems, methods, and apparatus (which would be readily discernible by one of ordinary skill in the art based on this disclosure). Additionally, the description may use terms such as "manufacture" and "provide" to describe the disclosed methods. These terms are high-level abstractions of actual operations that may be performed. The actual operations corresponding to these terms may vary depending on the particular implementation and would be readily discernible by one of ordinary skill in the art based on this disclosure.

[0035] Disclosed embodiments of an expandable sheath can minimize trauma to a vessel by temporarily expanding a portion of the introducer sheath to accommodate a delivery system and then returning to its original diameter once the device has passed. Some embodiments can include a sheath with a smaller profile (e.g., smaller diameter in the resting configuration) than that of prior art introducer sheaths. Furthermore, embodiments of the present invention can not only reduce procedure time but also reduce the risk of longitudinal or radial vessel rupture or plaque detachment because only one sheath is needed rather than several different sizes. Embodiments of an expandable sheath of the present invention can avoid the need for multiple insertions to dilate a vessel. Such expandable sheaths can be useful in many types of minimally invasive procedures, such as any surgery that requires the introduction of a device into a subject's blood vessel. For example, the sheath can be used to introduce other types of delivery devices for placing various types of intraluminal devices (e.g., stents, prosthetic heart valves, stented grafts, etc.) into many types of vascular and non-vascular body lumens (e.g., veins, arteries, esophagus, ducts of the biliary tree, intestines, urethra, fallopian tubes, other endocrine or exocrine ducts, etc.).

[0036] FIG. 1 illustrates a sheath 8 according to the present disclosure used with a representative delivery apparatus 10 for delivering a prosthetic device 12, such as a bioprosthetic heart valve, to a patient. The apparatus 10 can include a steerable guide catheter 14 (also referred to as a flex catheter), a balloon catheter 16 extending through the guide catheter 14, and a nose catheter 18 extending through the balloon catheter 16. In the illustrated embodiment, the guide catheter 14, the balloon catheter 16, and the nose catheter 18 are adapted to slide longitudinally relative to one another to facilitate delivery and placement of the valve 12 at an implantation site within the patient, as described in detail below. Generally, the sheath 8 is inserted through the patient's skin and into a blood vessel, such as a transfemoral vessel, such that the distal end of the sheath 8 is inserted into the vessel. The sheath 8 can include a hemostasis valve at the opposite proximal end of the sheath. The delivery apparatus 10 can be inserted into the sheath 8, and the prosthetic device 12 can then be delivered and implanted within the patient.

[0037] 2A, 2B, and 2D show cross-sectional views of an exemplary embodiment of a sheath 22 for use with a delivery device such as that shown in FIG. Exemplary expandable sheaths are also disclosed in U.S. patent application Ser. No. 12 / 249,867, filed Oct. 10, 2008 (now U.S. Patent No. 8,690,936), U.S. patent application Ser. No. 13 / 312,739, filed Dec. 6, 2011 (now U.S. Patent No. 8,790,387), U.S. patent application Ser. No. 14 / 248,120, filed Apr. 8, 2014 (now U.S. Patent No. 9,301,840), U.S. patent application Ser. No. 14 / 324,894, filed Jul. 7, 2014 (now U.S. Patent No. 9,301,841), U.S. patent application Ser. No. 15 / 057,953, filed Mar. 1, 2016 (now U.S. Patent No. 9,987,134), U.S. patent application Ser. No. 15 / 997,587, filed June 4, 2018; U.S. Patent Application No. 16 / 149,953, filed October 2, 2018 (now U.S. Patent No. 10,524,905); U.S. Patent Application No. 16 / 149,956, filed October 2, 2018 (now U.S. Patent No. 10,517,720); U.S. Patent Application No. 16 / 149,960, filed October 2, 2018 (now U.S. Patent No. 10,524,906); and U.S. Patent Application No. 16 / 149,969, filed October 2, 2018 (now U.S. Patent No. 10,524,907), the disclosures of which are incorporated herein by reference.

[0038] FIG. 2C shows a perspective view of one embodiment of an inner layer 24 for use with the sheath 22. The sheath 22 includes an inner layer, such as an inner polymeric tubular layer 24, an outer layer, such as an outer polymeric tubular layer 26, and an intermediate tubular layer 28 disposed between the inner and outer polymeric tubular layers 24, 26. The sheath 22 defines a lumen 30 through which a delivery device can be passed into a patient's vasculature to deliver, remove, repair, and / or replace a prosthetic device. Such an introducer sheath 22 may also be useful for other types of minimally invasive procedures, such as any procedure requiring the introduction of a device into a subject's vasculature. For example, the sheath 22 may also be used to introduce other types of delivery devices for placing various types of endoluminal devices (e.g., stents, stented grafts, etc.) into many types of vascular and non-vascular body lumens (e.g., veins, arteries, esophagus, ducts of the biliary tree, intestines, urethra, fallopian tubes, other endocrine or exocrine ducts, etc.).

[0039] The outer polymeric tubular layer 26 and the inner polymeric tubular layer 24 can be constructed of, for example, PTFE (e.g., Teflon®), polyimide, PEEK, polyurethane, nylon, polyethylene, polyamide, polyether block amide (e.g., PEBAX®), polyether block ester copolymer, polyester, fluoropolymer, polyvinyl chloride, thermoset silicone, latex, polyisoprene rubber, polyolefin, other medical grade polymers, or combinations thereof. The middle tubular layer 28 can be constructed of a shape memory alloy such as Nitinol, and / or stainless steel, cobalt chrome, Spectra fiber, polyethylene fiber, aramid fiber, or combinations thereof.

[0040] The inner polymeric tubular layer 24 may advantageously provide a low coefficient of friction on its inner surface. For example, the inner polymeric tubular layer 24 may have a coefficient of friction of less than about 0.1. Some embodiments of the sheath 22 may include a lubricious liner on the inner surface 32 of the inner polymeric tubular layer 24. Such a liner may facilitate passage of a delivery device through the lumen 30 of the sheath 22. Examples of suitable lubricious liners include materials that can reduce the coefficient of friction of the inner polymeric tubular layer 24, such as PTFE, polyethylene, polyvinylidene fluoride, and combinations thereof. Suitable materials for lubricious liners also include other materials for which a coefficient of friction of about 0.1 or less is desirable.

[0041] The inner diameter of the intermediate tubular layer 28 varies depending on the application and size of the delivery system and prosthetic device. In some embodiments, the inner diameter ranges from about 0.005 inches to about 0.400 inches. The thickness of the intermediate tubular layer 28 can vary depending on the amount of radial expansion desired and the strength required. For example, the thickness of the intermediate tubular layer 28 can be from about 0.002 inches to about 0.025 inches. The thicknesses of the inner and outer polymeric tubular layers 24, 26 can also vary depending on the particular application of the sheath 22. In some embodiments, the thickness of the inner polymeric tubular layer 24 ranges from about 0.0005 inches to about 0.010 inches, and in one particular embodiment, the thickness is about 0.002 inches. The outer polymeric tubular layer 26 can have a thickness of from about 0.002 inches to about 0.015 inches, and in one particular embodiment, the outer polymeric tubular layer 26 has a thickness of about 0.010 inches.

[0042] The hardness of each layer of sheath 22 can also vary depending on the particular application and desired properties of sheath 22. In some embodiments, outer polymeric tubular layer 26 has a Shore hardness of about 25 durometer to about 75 durometer.

[0043] Additionally, some embodiments of the sheath 22 can include an external hydrophilic coating on the outer surface 34 of the outer polymeric tubular layer 26. Such a hydrophilic coating can facilitate insertion of the sheath 22 into a patient's blood vessel. Examples of suitable hydrophilic coatings include Harmony® advanced lubricious coatings and other advanced hydrophilic coatings available from SurModics, Inc. of Eden Prairie, Minnesota. DSM Medical Coatings (available from Koninklijke DSM NV, Heerlen, The Netherlands), as well as other hydrophilic coatings, are also suitable for use with the sheath 22.

[0044] In some embodiments, the outer surface 34 of the outer polymeric tubular layer 26 can be modified. For example, a surface modification, such as plasma etching, can be performed on the outer surface 34. Similarly, other surfaces, both outer and inner, can be surface modified, depending on the particular embodiment and desired application. In some embodiments, the surface modification can improve adhesion between layers in the area of ​​the modification.

[0045] The sheath 22 can also include at least one radiopaque filler or marker. The radiopaque filler or marker can be associated with the outer surface 34 of the outer polymeric tubular layer 26. Alternatively, the radiopaque filler or marker can be embedded or incorporated within the outer polymeric tubular layer 24. Similarly, a radiopaque filler or marker can be associated with the surface of the inner polymeric tubular layer 24 or the intermediate tubular layer 28, or embedded within either or both of those layers.

[0046] Materials suitable for use as radiopaque fillers or markers include, for example, barium sulfite, bismuth trioxide, titanium dioxide, bismuth subcarbonate, or combinations thereof. The radiopaque filler can be mixed with or embedded in the material used to form the outer polymeric tubular layer 26 and can comprise from about 5% to about 45% by weight of the outer polymeric tubular layer. Depending on the particular application, more or less radiopaque material can be used in some embodiments.

[0047] In some embodiments, the inner polymeric tubular layer 24 can be constructed as a substantially uniform cylindrical tube. In alternative embodiments, the inner polymeric tubular layer 24 can have at least one discontinuous section along its longitudinal axis to facilitate radial expansion of the inner polymeric tubular layer 24. For example, the inner polymeric tubular layer 24 can have one or more longitudinal notches and / or cuts 36 extending along at least a portion of the length of the sheath 22. Such notches or cuts 36 can facilitate radial expansion of the inner polymeric tubular layer 24, thereby accommodating the passage of a delivery device or other device. Such notches and / or cuts 36 can be located near the inner surface 32, near the outer surface 37, and / or substantially through the entire thickness of the inner polymeric layer 24. In embodiments having multiple notches and / or cuts 36, such notches and / or cuts 36 can be positioned substantially equally spaced from one another around the circumference of the inner polymeric layer 24. Alternatively, the notches and cuts 36 can be spaced randomly relative to one another or in any other desired pattern. Some or all of the notches and / or cuts 36 can extend longitudinally along substantially the entire length of the sheath 22. Alternatively, some or all of the notches and / or cuts 36 can extend longitudinally along only a portion of the length of the sheath 22.

[0048] 2B and 2C (showing only the inner polymeric tubular layer 24), in some embodiments, the inner polymeric tubular layer 24 includes at least one notch or cut 36 that extends longitudinally and parallel to the axis defined by the lumen 30, extending substantially the entire length of the sheath 22. That is, upon introduction of a delivery device, the inner polymeric tubular layer 24 can split open along the notch and / or cut 36 and expand, thereby accommodating the delivery device.

[0049] Additionally or alternatively, as shown in FIG. 2D , the outer polymeric tubular layer 26 can include one or more notches and / or cuts 36. The notches and / or cuts 36, in some embodiments, do not extend the entire thickness of the outer tubular layer 26. The notches and / or cuts 36 can be separable upon radial expansion of the sheath 22. The outer polymeric tubular layer 26 can be longitudinally retractable or retractable away from the intermediate tubular layer 28 and the inner polymeric tubular layer 24. In embodiments having a retractable outer polymeric tubular layer 26, the outer polymeric tubular layer 26 can be retracted to accommodate or facilitate passage of a delivery device through the lumen 30 and then replaced back into place on the sheath 22.

[0050] FIG. 3 shows an elevational view of the sheath 22 shown in FIG. 2A. In this view, only the outer polymeric tubular layer 26 is visible. The sheath 22 includes a proximal end 38 and a distal end 40 opposite the proximal end 38. The sheath 22 may include a hemostatic valve inside the lumen of the sheath 22 at or near the proximal end 38 of the sheath 22. Additionally, the sheath 22 may include a soft tip 42 at the distal end 40 of the sheath 22. Such a soft tip 42 may be provided with a lower hardness than the remainder of the sheath 22. In some embodiments, the soft tip 42 may have a Shore hardness of about 25D to about 40D.

[0051] As shown in FIG. 3 , the original unexpanded outer diameter of the sheath 22 can be substantially constant throughout the length of the sheath 22, from the proximal end 38 to the distal end 40. In alternative embodiments, such as those shown in FIGS. 4A-4B , the original unexpanded outer diameter of the sheath 22 can decrease from the proximal end 38 to the distal end 40. As shown in the embodiment in FIG. 4A , the original unexpanded outer diameter can decrease along a gradient from the proximal end 38 to the distal end 40. In alternative embodiments, such as those shown in FIG. 4B , the original unexpanded outer diameter of the sheath 22 can decrease progressively along the length of the sheath 22, with the largest original unexpanded outer diameter near the proximal end 38 and the smallest original unexpanded outer diameter near the distal end 40 of the sheath 22.

[0052] As shown in FIGS. 5-6 , the sheath 22 can be designed to locally expand when a prosthetic device is passed through the lumen of the sheath 22 and then substantially return to its original shape once the prosthetic device has passed through that portion of the sheath 22. For example, FIG. 5 shows the sheath 22 having a localized bulge 44 representing the device passing through the internal lumen of the sheath 22. FIG. 5 shows the device near the area where the device will be introduced into the sheath 22, near the proximal end 38 of the sheath 22. FIG. 6 shows the sheath 22 of FIG. 5 with the device further along the sheath 22. The localized bulge 44 is now closer to the distal end 40 of the sheath 22 and is therefore about to be introduced into the patient's vasculature. As is evident from FIGS. 5 and 6 , once the localized bulge associated with the device passes through a portion of the lumen of the sheath 22, that portion of the sheath 22 can automatically return to its original shape and size due, at least in part, to the material and construction of the sheath 22.

[0053] The sheath 22 has an unexpanded inner diameter (not visible in FIGS. 5-6 ) equal to the inner diameter of the inner polymeric tubular layer and an unexpanded outer diameter 46 equal to the outer diameter of the outer polymeric tubular layer 26. The sheath 22 is designed to be expanded to expanded inner and outer diameters 48 that are larger than the unexpanded inner and outer diameters 46, respectively. In one exemplary embodiment, the unexpanded inner diameter is approximately 16 Fr and the unexpanded outer diameter 46 is approximately 19 Fr, while the expanded inner diameter is approximately 26 Fr and the expanded outer diameter 48 is approximately 29 Fr. Depending on the size requirements of the delivery device for various applications, different sheaths 22 can be provided with different expanded and unexpanded inner and outer diameters. Additionally, some embodiments may provide more or less expansion depending on the specific design parameters, materials, and / or configurations used.

[0054] In some embodiments of a sheath according to the present disclosure, as shown in cross section in FIG. 7 and in elevation in FIG. 8, the sheath 22 can further include an outer covering, such as an outer polymeric covering 50, disposed on an outer surface 52 of the outer polymeric tubular layer 26. The outer polymeric covering 50 can provide a protective covering for the underlying sheath 22. In some embodiments, the outer polymeric covering 50 can contain the self-expanding sheath in a crimped or constrained state and then release the self-expanding sheath upon removal of the outer polymeric covering 50. For example, in some embodiments of a self-expanding sheath, the intermediate layer 28 can comprise nitinol and / or other shape memory alloy, and the intermediate layer 28 can be crimped or radially compressed to a reduced diameter within the outer polymeric tubular layer 26 and the outer polymeric covering 50. Once the self-expanding sheath is at least partially inserted into the patient's blood vessel, the outer polymeric covering 50 can be slid back, peeled, or otherwise at least partially removed from the sheath. To facilitate removal of the outer polymeric covering 50, a portion of the outer polymeric covering 50 can remain outside the patient's blood vessel, and that portion can be pulled back or removed from the sheath to allow the sheath to expand. In some embodiments, substantially the entire outer polymeric covering 50 can be inserted into the patient's blood vessel along with the sheath. In these embodiments, an external mechanism attached to the outer polymeric covering 50 can be provided to enable the outer polymeric covering to be at least partially removed from the sheath once the sheath is inserted into the patient's blood vessel.

[0055] When no longer constrained by the outer polymeric covering 50, the radially compressed intermediate layer 28 can self-expand, expanding the sheath along the length of the intermediate layer 28. In some embodiments, upon withdrawal of the sheath from the vessel after completion of the surgical procedure, portions of the sheath can radially collapse and at least partially return to their original crimped state. In some embodiments, such collapse can be facilitated and / or accelerated by additional devices or layers that can be attached to portions of the sheath prior to insertion of the sheath into the vessel.

[0056] In some embodiments, the outer polymer covering 50 is not adhered to other layers of the sheath 22. For example, the outer polymer covering 50 may be slidable relative to the underlying sheath so that it can be easily removed or retracted from its initial position on the sheath 22.

[0057] As seen in FIG. 8 , the outer polymeric covering 50 can include one or more peel tabs 54 to facilitate manual removal of the outer polymeric covering 50. The outer polymeric covering 50 can be automatically or manually retractable and / or splittable to facilitate radial expansion of the sheath 22. The peel tabs 54 can be positioned approximately 90 degrees from any cuts or notches present in the outer polymeric covering 50 and approximately 180 degrees offset from each other. In an alternative embodiment, the peel tabs 54 can extend substantially around the circumference of the outer polymeric covering 50 to form a single circular peel tab 54.

[0058] Suitable materials for the outer polymeric covering 50 are similar to those suitable for the inner and outer polymeric tubular layers and can include PTFE and / or high density polyethylene.

[0059] Turning now to the intermediate tubular layer 28, several different configurations are possible. The intermediate tubular layer 28 is generally a thin-walled, hollow, substantially cylindrical tube containing a wire or strut arrangement, pattern, configuration, or arrangement, although other geometries can be used. The intermediate tubular layer 28 can extend along substantially the entire length of the sheath 22 or along only a portion of the length of the sheath 22. Suitable wires can be round, ranging from about 0.0005 inches to about 0.10 inches in diameter, or flat, ranging from about 0.0005 inches by 0.003 inches to about 0.003 inches by 0.007 inches. However, other geometries and sizes are also suitable for certain embodiments. When braided wire is used, the braid density can vary. Some embodiments have a braid density of about 30 picks per inch to about 80 picks per inch and can include up to 32 wires in various braid patterns.

[0060] One representative example of an intermediate tubular layer includes a braided nitinol composite, which is at least partially encapsulated by inner and outer polymeric tubular members disposed on the inner and outer surfaces of the intermediate tubular layer, respectively. Such encapsulation by the polymeric layer can be achieved, for example, by fusing the polymeric layer to the intermediate tubular layer or by dip-coating the intermediate tubular layer. In some embodiments, the inner polymeric tubular member, intermediate tubular layer, and outer polymeric tubular layer can be placed on a mandrel, and the layers can then be thermally fused or melted to one another by placing the assembly in an oven or otherwise heating it. The mandrel can then be removed from the resulting sheath. In other embodiments, the inner polymeric tubular member can be applied to the surface of the mandrel using dip coating. The intermediate tubular layer can then be applied, and the inner polymeric tubular member can be cured. The assembly can then be dip-coated again, for example, by applying a thin coating of polyurethane, which becomes the outer polymeric tubular member of the sheath. The sheath can then be removed from the mandrel.

[0061] Additionally, the intermediate tubular layer 28 can be braided or laser cut to form a pattern or structure, for example, to make the intermediate tubular layer 28 suitable for radial expansion. Figures 9-23 show partial elevational views of various intermediate tubular layer structures. Some of the illustrated structures, such as those shown in Figures 11-14 and 23, include at least one discontinuity. For example, struts 56, 58, 60, 62, and 64, shown in Figures 11, 12, 13, 14, and 23, respectively, result in a discontinuous intermediate tubular layer 28 in that struts 56, 58, 60, 62, and 64 separate adjacent sections of the intermediate tubular layer 28 from one another, where the sections are spaced apart along a longitudinal axis parallel to the sheath lumen. That is, the structure of the intermediate tubular layer 28 can vary from section to section, varying along the length of the sheath.

[0062] The structures shown in Figures 9-23 are not necessarily drawn to scale. The structural components and elements may be used alone or in combination within a single intermediate tubular layer 28. The scope of the intermediate tubular layer 28 is not intended to be limited to these particular structures, which are merely illustrative examples.

[0063] Alternative embodiments of sheaths for introducing prosthetic devices are also described. For example, FIGS. 24-26 show cross-sectional and perspective views, respectively, of a sheath 66 for introducing a prosthetic device into a body. The sheath 66 includes an inner layer, such as an inner polymer layer 68, an outer layer, such as a polymer tubular layer 70, and a hemostatic valve (not shown). The inner polymer layer 68 and the outer polymer tubular layer 70 at least partially enclose a lumen 72 through which a delivery device and prosthetic device can pass from outside the patient's body into the patient's vasculature. One or both of the inner polymer layer 68 and the outer polymer layer 70 can include at least one longitudinal notch and / or cut to facilitate radial expansion of the sheath.

[0064] For example, FIG. 24 illustrates longitudinal notches 74 in the inner polymer layer 68, which can facilitate radial expansion of the sheath 66. The longitudinal notches 74 can separate or split open completely upon application of a radial force from insertion of a delivery apparatus or prosthetic device. Similarly, FIG. 25 illustrates longitudinal cuts 76 in the inner polymer layer 68, which can also facilitate radial expansion of the sheath 66. The outer polymer layer 70 can additionally or alternatively include one or more longitudinal cuts 76 or notches 74. Such cuts and / or notches can extend substantially through the entire thickness of the layer in either the inner polymer layer 68 or the outer polymer layer 70, or can extend only partially through the thickness of the layer. The cuts and / or notches can be located on or near the inner or outer surface, or both, of the inner and / or outer polymer layers 68, 70.

[0065] FIG. 26 shows a perspective view of one embodiment of the inner polymeric layer 68 having longitudinal notches 74 and longitudinal cuts 76. More or fewer notches 74 and / or cuts 76 may be provided. For clarity, the outer polymeric layer 70 is not shown in FIG. 26. As shown in FIG. 26, the longitudinal notches 74 and / or cuts 76 may extend along only a portion of the length of the sheath 66. In alternative embodiments, one or more notches 74 and / or cuts 76 may extend along substantially the entire length of the sheath 66. Furthermore, the notches 74 and / or cuts 76 may be arranged randomly or in a pattern.

[0066] One particular embodiment of the sheath 66 comprises a sheath having a notch or cut in the outer polymeric layer 70 or the inner polymeric layer 68 that extends longitudinally along approximately 75% of the length of the sheath 66. When such a notch or cut extends only partially through the associated layer, it can have a relatively low tear force, such as a tear force of about 0.5 lbs, such that the notch splits open relatively easily during use.

[0067] The inner polymer layer 68 and the outer polymer layer 70 can optionally be bonded together or otherwise physically associated with one another. The amount of adhesion between the inner polymer layer 68 and the outer polymer layer 70 can vary across the surfaces of the layers. For example, there can be little or no adhesion around or near notches and / or cuts in the layers so as not to interfere with the radial expansion of the sheath 66. Adhesion between the layers can be created, for example, by thermal bonding and / or coating. An example of the sheath 66 can be formed from an extruded tube, which can serve as the inner polymer layer 68. The inner polymer layer 68 can be surface treated, for example, by plasma etching, chemical etching, or other suitable surface treatment methods. By treating the surface of the inner polymer layer 68, the outer surface of the inner polymer layer 68 can have areas with modified surface angles, which can provide better adhesion between the inner polymer layer 68 and the outer polymer layer 70. The treated inner polymer layer can be dip-coated, for example, in a polyurethane solution to form the outer polymer layer 70. In some configurations, polyurethane may not adhere well to untreated surface areas of the inner polymer layer 68. That is, by surface treating only the surface areas of the inner polymer layer 68 that are spaced from the area of ​​expansion (e.g., portions of the inner polymer layer 68 near the notches 74 and / or cuts 76), the outer polymer layer 70 can be adhered to some areas of the inner polymer layer 68, while other areas of the inner polymer layer 68 remain free to slide relative to the outer polymer layer 70, thereby allowing the diameter of the sheath 66 to expand. That is, the areas around or near the notches 74 and / or cuts 76 experience little or no adhesive force between the layers, while the other areas of the inner and outer polymer layers 68, 70 can be adhesively secured or otherwise physically associated with one another.

[0068] As with the previously disclosed embodiments, the embodiment shown in FIGS. 24-26 can be applied to sheaths having a wide range of inner and outer diameters. Applications can utilize sheaths of the present disclosure having inner polymer layer 68 inner diameters that are expandable to expanded diameters from about 3 Fr to about 26 Fr. The expanded diameter can vary slightly along the length of the sheath 66. For example, the expanded outer diameter at the proximal end of the sheath 66 can range from about 3 Fr to about 28 Fr, while the expanded outer diameter at the distal end of the sheath 66 can range from about 3 Fr to about 25 Fr. Sheath 66 embodiments can be expanded to expanded outer diameters ranging from about 10% larger than the original unexpanded outer diameter to about 100% larger than the original unexpanded outer diameter.

[0069] In some embodiments, the outer diameter of the sheath 66 gradually decreases from the proximal end of the sheath 66 to the distal end of the sheath 66. For example, in one embodiment, the outer diameter can gradually decrease from about 26 Fr at the proximal end to about 18 Fr at the distal end. The diameter of the sheath 66 can gradually transition along substantially the entire length of the sheath 66. In other embodiments, the transition or decrease in diameter of the sheath 66 can occur only along a portion of the length of the sheath 66. For example, the transition can occur along the length from the proximal end to the distal end, in which case the length can range from about 0.5 inches to the entire length of the sheath 66.

[0070] Suitable materials for the inner polymer layer 68 have high elastic strength and include those materials discussed in connection with other embodiments, particularly Teflon (PTFE), polyethylene (e.g., high-density polyethylene), fluoropolymers, or combinations thereof. In some embodiments, the inner polymer layer 68 preferably has a low coefficient of friction, such as a coefficient of friction of about 0.01 to about 0.5. Some preferred embodiments of the sheath 66 include an inner polymer layer 68 having a coefficient of friction of about 0.1 or less.

[0071] Similarly, suitable materials for the outer polymeric layer 70 include those discussed in connection with other embodiments, as well as other thermoplastic elastomers and / or highly resilient materials.

[0072] The Shore hardness of the outer polymer layer 70 can vary for different applications and embodiments. Some embodiments include an outer polymer layer having a Shore hardness of about 25A to about 80A, or about 20D to about 40D. One particular embodiment includes a readily available polyurethane with a Shore hardness of 72A. Another particular embodiment includes a polyethylene inner polymer layer dipped in polyurethane or silicone to produce the outer polymer layer.

[0073] The sheath 66 may also include radiopaque fillers or markers, as described above. In some embodiments, different radiopaque markers or bands may be applied to different portions of the sheath 66. For example, radiopaque markers may be bonded to the inner polymer layer 68, the outer polymer layer 70, and / or disposed between the inner and outer polymer layers 68, 70.

[0074] 27A-27E and 28 show cross-sectional views of various embodiments of a sheath 66 in an unexpanded state (FIGS. 27A-27E) and an expanded state (FIG. 28) according to the present disclosure. The sheath 66 includes a split outer polymeric tubular layer 70 having a longitudinal cut 76 through the thickness of the outer polymeric tubular layer 70 such that the outer polymeric tubular layer 70 includes a first portion 78 and a second portion 80 separable from one another along the cut 76. An expandable inner polymeric layer 68 is associated with an inner surface 82 of the outer polymeric tubular layer 70, and in the unexpanded configuration shown in FIG. 27A, a portion of the inner polymeric layer 68 extends through the gap created by the cut 76 and can be compressed between the first and second portions 78, 80 of the outer polymeric tubular layer 70. 28 , upon expansion of the sheath 66, the first and second portions 78, 80 of the outer polymeric tubular layer 70 separate from one another and the inner polymeric layer 68 expands into a substantially cylindrical tube. In some embodiments, two or more longitudinal cuts 76 may be provided through the thickness of the outer polymeric tubular layer 70. In such embodiments, a portion of the inner polymeric layer 68 may extend through each of the longitudinal cuts 76 provided in the outer polymeric tubular layer 70.

[0075] Preferably, the inner polymeric layer 68 is composed of one or more materials that are resilient and suitable for folding and / or pleating. For example, FIG. 27A shows an inner polymeric layer 68 having a folding region 85. As can be seen in FIGS. 27A-27E, the sheath 66 can have one or more folding regions 85. Such folding regions 85 can be radially disposed and substantially conform to the circumference of the outer polymeric tubular layer 70. At least a portion of the folding region 85 can be disposed adjacent to the outer surface 83 of the outer polymeric tubular layer 70. Furthermore, as shown in FIGS. 27B and 27E, at least a portion of the folding region(s) 85 can be overlapped by an outer covering, such as an outer polymeric covering 81. The outer polymeric covering 81 can be adjacent to at least a portion of the outer surface 83 of the outer polymeric tubular layer 70. The outer polymer covering 81 serves to at least partially contain the folded region 85 of the inner polymer layer 68 and may also prevent the folded region 85 from separating from the outer polymer tubular layer 70, for example, when the sheath 66 is subjected to bending. In some embodiments, the outer polymer covering 81 may be at least partially adhered to the outer surface 83 of the outer polymer tubular layer 70. The outer polymer covering 81 may also increase the rigidity and / or durability of the sheath 66. Furthermore, as shown in FIGS. 27B and 27E, the outer polymer covering 81 does not have to entirely overlap the circumference of the sheath 66. For example, the outer polymer covering 81 may have a first end and a second end, and the ends do not contact each other. In these embodiments, only a portion of the folded region 85 of the inner polymer layer 68 overlaps the outer polymer covering 81.

[0076] In embodiments having multiple folding regions 85, the regions can be evenly offset from one another around the circumference of the outer polymeric tubular layer 70. Alternatively, the folding regions can be off-center, differently sized, and / or randomly spaced from one another. While portions of the inner polymeric layer 68 and the outer tubular layer 70 can be glued or otherwise bonded to one another, the folding regions 85 are preferably not glued or bonded to the outer tubular layer 70. For example, adhesion between the inner polymeric layer 68 and the outer tubular layer 70 can be highest in areas of minimum expansion.

[0077] One particular embodiment of a sheath, shown in Figures 27A-28, comprises a polyethylene (e.g., high-density polyethylene) outer polymeric tubular layer 70 and a PTFE inner polymeric layer 68. However, other materials are suitable for each layer, as discussed above. In general, materials suitable for use in the outer polymeric tubular layer 70 include materials with a high stiffness or strength modulus that can assist in the expansion and contraction of the inner polymeric layer 68.

[0078] In some embodiments, the outer polymeric tubular layer 70 is composed of the same material or combination of materials along the entire length of the outer polymeric tubular layer 70. In alternative embodiments, the material composition may vary along the length of the outer polymeric tubular layer 70. For example, the outer polymeric tubular layer may be provided with one or more segments that vary in composition from segment to segment. In one particular embodiment, the durometer rating of the composition varies along the length of the outer polymeric tubular layer 70, such that the segment near the proximal end comprises a stiffer material or combination of materials, while the segment near the distal end comprises a softer material or combination of materials. This may allow the sheath 66 to have a relatively stiff proximal end at the point where the delivery device is introduced, while still having a relatively soft distal tip at the point of entry into the patient's vasculature.

[0079] As with other disclosed embodiments, the embodiment of sheath 66 shown in Figures 27A-28 can be provided in a variety of sizes and dimensions. For example, sheath 66 can have an unexpanded inner diameter of about 3 Fr to about 26 Fr. In some embodiments, sheath 66 has an unexpanded inner diameter of about 15 Fr to about 16 Fr. In some embodiments, the unexpanded inner diameter of sheath 66 can range from about 3 Fr to about 26 Fr at or near the distal end of sheath 66, while the unexpanded inner diameter of sheath 66 can range from about 3 Fr to about 28 Fr at or near the proximal end of sheath 66. For example, in one unexpanded embodiment, sheath 66 can transition from an unexpanded inner diameter of about 16 Fr at or near the distal end of sheath 66 to an unexpanded inner diameter of about 26 Fr at or near the proximal end of sheath 66.

[0080] The sheath 66 can have an unexpanded outer diameter of about 3 Fr to about 30 Fr, and in some embodiments has an unexpanded outer diameter of about 18 Fr to about 19 Fr. In some embodiments, the unexpanded outer diameter of the sheath 66 can range from about 3 Fr to about 28 Fr at or near the distal end of the sheath 66, while the unexpanded outer diameter of the sheath 66 can range from about 3 Fr to about 30 Fr at or near the proximal end of the sheath 66. For example, in one unexpanded embodiment, the sheath 66 can transition from an unexpanded outer diameter of about 18 Fr at or near the distal end of the sheath 66 to an unexpanded outer diameter of about 28 Fr at or near the proximal end of the sheath 66.

[0081] The thickness of the inner polymer layer 68 can vary, but in some preferred embodiments is from about 0.002 inches to about 0.015 inches. In some embodiments, expansion of the sheath 66 can result in an expansion of the unexpanded outer diameter of from about 10% or less to about 430% or more.

[0082] 27A-28, as well as the other embodiments shown and described, can be provided with a radiopaque filler and / or a radiopaque tip marker, as described above. The sheath 66 can be provided with a radiopaque tip marker at or near the distal end of the sheath 66. Such a radiopaque tip marker can be constructed of materials such as those suitable for radiopaque fillers, platinum, iridium, platinum / iridium alloys, stainless steel, other biocompatible metals, or combinations thereof.

[0083] 50 and 51 show cross-sectional views of an expandable sheath 166 having an inner tubular layer 168 with a longitudinal slit 169. In some embodiments, the longitudinal slit 169 extends the entire length of the inner tubular layer 168. An outer tubular layer 170 surrounds the inner tubular layer 168 and includes longitudinally extending folding flaps 171. In some embodiments, the folding flaps 171 extend the entire length of the outer tubular layer 170. The folding flaps 171 overlie portions of the outer surface 183 of the outer tubular layer 170 when the sheath is in an unexpanded state (FIG. 50). As a prosthetic device moves through the lumen 172 of the sheath 166, it exerts an outward radial force on the inner tubular layer 168, which widens the longitudinal slit 169 and deploys the folding flaps 171. FIG. 51 shows the sheath 166 in an unexpanded state with the longitudinal slit 169 widened and the outer tubular layer 170 unfolded.

[0084] Folding flap 171 of outer tubular layer 170 has a base 173. Base 173 can be disposed radially outward from longitudinal slit 169. In some embodiments, base 173 is centered within longitudinal slit 169. Folding flap 171 further includes an overlying portion 175 extending longitudinally from base 173 to a longitudinally extending crease 179 at the edge of flap 171. Longitudinal overlying portion 175 overlies and is separated from longitudinally extending underlying portion 177 by crease 179. Underlying portion 177 contacts outer surface 183 of outer tubular layer 170 when the sheath is in an unexpanded state, as shown in FIG. 50 .

[0085] Some embodiments of the sheath 166 may include multiple longitudinally extending folding flaps overlying portions of the outer surface 183 of the outer tubular layer 170, positioned at various locations around the circumference of the sheath 166. For example, 2, 3, 4, 5, 6, 7, 8, 9, or 10 longitudinally extending folding flaps may be positioned around the circumference. In some embodiments, the multiple folding flaps are evenly spaced around the circumference of the sheath 166.

[0086] The folding flaps 171 extend circumferentially around a portion of the sheath 166. In some embodiments, the longitudinally extending flaps 171 extend around about 20% to about 40% (including about 20%, about 21%, about 22%, about 23%, about 24%, about 25%, about 26%, about 27%, about 28%, about 29%, about 30%, about 31%, about 32%, about 33%, about 34%, about 35%, about 36%, about 37%, about 38%, about 39%, and about 40%) of the circumference of the outer tubular layer 170 when the sheath 166 is in an unexpanded state. In one example, for a sheath having a 14F (4.7 mm) unexpanded outer diameter, the folding flaps extend approximately 85 to 120 degrees, or approximately 23% to 35% of the circumference (resulting in a lumen having an expanded diameter of approximately 7.6 mm to approximately 8.4 mm, which can be used for a valve having a crimped outer diameter of 6.4 mm and an expanded outer diameter of 26 mm).

[0087] In FIG. 51 , the wall thickness of flap 171 is labeled t, and the wall thickness of the remainder of outer tubular layer 170 is labeled T. In some embodiments, a portion of flap 171 (e.g., underlying portion 177 or overlying portion 175) can have a wall thickness t that is thinner than the wall thickness (T) of the remainder of the outer tubular layer. Variations in wall thickness promote uniform column strength around the circumference of sheath 166, which reduces kinking and minimizes the overall outer diameter of the sheath. Wall thickness variations can also facilitate the folding process. In some embodiments, the entire flap 171 has a wall thickness t that is thinner than the wall thickness T of the remainder of the outer tubular layer. In one example, wall thickness t can be approximately from about 0.003 inches to about 0.007 inches, while wall thickness T can be approximately from about 0.008 inches to about 0.012 inches. In other embodiments, such as that shown in FIG. 51, the wall thickness t of the flap 171 is approximately equal to the wall thickness T of the remainder of the outer tubular layer 170 .

[0088] The outer tubular layer 170 is formed of a material with a low coefficient of friction, a high tensile modulus, and a high tensile strength to improve force transmission through the length of the sheath 166 while reducing kinking. Good force transmission means that the force applied by the practitioner to advance the sheath is predictable, responsive, and consistent along the length of the sheath. However, an excessively high tensile modulus can limit the ability of the longitudinally extending flaps 171 to open, which can inhibit force transmission. A desirable range of tensile modulus of elasticity for the outer tubular layer 170 is from about 300 MPa to about 2000 MPa (including about 300 MPa, about 400 MPa, about 500 MPa, about 600 MPa, about 700 MPa, about 800 MPa, about 900 MPa, about 1000 MPa, about 1100 MPa, about 1200 MPa, about 1300 MPa, about 1400 MPa, about 1500 MPa, about 1600 MPa, about 1700 MPa, about 1800 MPa, about 1900 MPa, and about 2000 MPa). In some embodiments, the tensile modulus may preferably be at least 700 MPa. High axial and radial stiffness allows the sheath to be easily inserted and to resist collapse within the body.

[0089] The tensile strength of the outer tubular layer 170 may be at least 50 MPa. High tensile strength helps prevent the material from tearing while the prosthetic device is advanced through the sheath.

[0090] Exemplary materials for forming the outer tubular layer 170 of the embodiment shown in Figures 50 and 51 include high density polyethylene (HDPE), polyamide, copolyamide, polyether block amide (PEBAX®), or a blend of polyamides. Materials with shape memory properties are advantageous because they can impart a bias to the outer tubular layer 170 toward a collapsed state (e.g., by heat setting). This facilitates refolding of the outer tubular layer 170 after passage of the prosthetic device. PEBAX® is an exemplary shape memory material that can be heat set to a collapsed state.

[0091] In some embodiments, the outer surface 183 of the outer tubular layer 170 can include a hydrophilic coating. In some embodiments, a bond can be created between the underlying portion 177 of the folding flap 171 and the outer surface 183 of the outer tubular layer 170. This bond can be a thermal bond (with portions of the contact layers melted together) or a separate layer of adhesive.

[0092] As discussed above, in the embodiment shown in Figures 50 and 51, the inner tubular layer 168 includes a longitudinal slit 169. The inner tubular layer 168 includes a first longitudinally extending end 178 and a second longitudinally extending end 180, with the first and second longitudinally extending ends 178, 180 defining the longitudinal slit 171.

[0093] The inner tubular layer 168 forms a low-friction barrier between a passing prosthetic device and the higher-friction outer tubular layer 170. When the sheath 166 is in an unexpanded state, the inner tubular layer 168 extends around at least 80% (or at least 85%, or at least 90%, or at least 95%) of the circumference of the lumen 172. The high degree of coverage limits contact between a passing prosthetic device and the high-friction outer tubular layer 170. In some embodiments, the inner tubular layer 168 has a coefficient of friction (static or dynamic) according to ASTM D1894 of 0.30 or less. In other embodiments, the coefficient of friction is 0.25 or less.

[0094] In some embodiments, the low-friction inner tubular layer 168 includes or is formed of a material having a tensile modulus of at least about 300 MPa (and up to about 1400 MPa) to provide good push-force transmission while providing kink resistance. This material can be, for example, high-density polyethylene or a fluoropolymer. Exemplary fluoropolymers include polytetrafluoroethylene, ethylene fluorinated ethylene propylene, or perfluoroalkoxy.

[0095] A tie layer 174 can be disposed between the two layers, thereby adhering the inner tubular layer 168 to the outer tubular layer 170. The tie layer 174 can be formed of polyurethane or a functionalized polyolefin in some embodiments. In some embodiments, the contact surface of the inner tubular layer 168 can be etched to improve bonding to the tie layer. For example, an inner tubular layer 168 including or formed of a fluoropolymer can have its surface etched to improve thermal bonding to the tie layer 174.

[0096] Some embodiments of the sheath 166 shown in FIGS. 50 and 51 can also include an outer jacket 181, as shown in FIG. 52. The outer jacket 181 is elastomeric (having a relatively low tensile modulus compared to the inner and outer tubular layers 168, 170). As mentioned above, in some embodiments, the outer tubular layer 170 can include or be formed of a shape-memory material (e.g., a heat-set polymer such as PEBAX®) that facilitates refolding of the outer tubular layer 170 after expansion. In some embodiments, the sheath 166 can include an elastomeric outer jacket 181 that extends over and surrounds the outer tubular layer 170. The outer jacket 181 and shape-memory mechanism can be used alone or in conjunction with each other to facilitate refolding (i.e., the elastomeric outer jacket 181 can extend over the outer tubular layer 170, which includes a shape-memory material). Refolding of outer tubular layer 170 preferably allows sheath 166 to return to its original outer diameter or to a value close to its original outer diameter (e.g., within about 10%, about 20%, about 30%, about 40%, or about 50% of the original outer diameter). Elastomeric outer jacket 181 can include or be formed entirely of a material such as low durometer polyurethane (e.g., less than Shore 85A), styrene elastomer (e.g., less than Shore 85A), latex, or low durometer PEBAX® (e.g., less than Shore 35D).

[0097] 50-52 includes a first step of inserting an expandable sheath 166 into a subject's vasculature and advancing a prosthetic device through the lumen 172 of the expandable sheath 166. The prosthetic device exerts an outward radial force on the inner tubular layer 168 of the expandable sheath 166. In some embodiments, the outward radial force is transmitted through the inner tubular layer 168, the bonding layer 174, and the outer tubular layer 170. The outward radial force expands the width of a longitudinal slit 169 in the inner tubular layer 168. In some embodiments, the expansion of the longitudinal slit 169 is propagated along the entire length of the expandable sheath.

[0098] The outward radial force further deploys the longitudinally extending flaps 171 of the outer tubular layer 170, expanding the expandable sheath. Deployment of the flaps 171 can include circumferentially sliding the longitudinally extending overlying portions 175 relative to the longitudinally extending underlying portions 177 of the flaps 171. The underlying portions 177 can slide circumferentially relative to the outer surface 183 of the outer tubular layer 170. In some embodiments, deployment of the longitudinally extending flaps 171 occurs at a location radially outward from the longitudinal slits 169 in the inner tubular layer 168. Deployment of the flaps 171 can extend the entire length of the expandable sheath 166 in some embodiments.

[0099] The longitudinal slits 169 in the inner tubular layer 168 narrow in width when the outward radial force is removed (i.e., the prosthetic device is passed through). The slits 169 may narrow back to their original width or to a value close to their original width (e.g., within 10% of their original width). The width reduction can occur along the entire length of the sheath 166. The prosthetic device is then delivered to the treatment site.

[0100] The longitudinally extending flaps 171 at least partially refold when the prosthetic device ceases to exert an outward radial force (i.e., it has passed). In some embodiments, the longitudinally extending flaps 171 refold on themselves due to a shape memory bias toward the folded state. In some embodiments, an inward radial force is applied to the outer surface 183 of the outer tubular layer 170 (e.g., by the elastomeric outer jacket 181) to refold the longitudinally extending flaps 171.

[0101] An exemplary method for manufacturing a sheath is as follows: These steps are not meant to be limiting. The steps given may be rearranged as needed. Other steps may be added, and in other instances, some steps may not be required. Dimensions are approximate. 1) Starting with a PTFE inner layer having an inside diameter (ID) of approximately 0.200 inches and a wall thickness of approximately 0.004 inches, 2) Loading the PTFE inner layer onto a tapered mandrel from approximately 0.200 inches to approximately 0.187 inches, 3) Stretching under heat onto a 0.187 inch outer diameter (OD) mandrel section, 4) Flaring under heat the proximal end of the 0.200 inch ID PTFE to 0.340 inch ID, 5) Loading a tie layer, such as Tecoflex 80A, having an approximately 0.200 inch ID and 0.004 inch wall thickness onto the PTFE inner layer along the body section (optionally, the tie layer can be applied after expanding the inner layer with air pressure), 6) Covering with, for example, FEP (fluorinated ethylene propylene) heat shrink tubing and applying heat to adhere the tie layer to the inner layer, 7) 8) remove FEP heat shrink tubing, if used; 9) create a longitudinal slit along the body section of the assembly; 10) load the slitted subassembly onto a 0.187 inch OD mandrel; 11) load the outer layer onto the body; 12) heat set the folds, for example, by inserting the fold-covered subassembly inside heat shrink tubing and placing the assembly in an oven; 13) remove shrink tubing, if used; and 14) remove the sheath from the mandrel. In some embodiments, an outer elastomeric jacket is applied over the heat-set outer layer before removal from the mandrel.

[0102] 29A-29D are cross-sectional views of other possible configurations of a sheath 66 for introducing a prosthetic device into a patient's vasculature. The sheath 66 includes a polymeric tubular layer 84 having an inner surface 86 and an outer surface 88. The thickness of the polymeric tubular layer 84 extends from the inner surface 86 to the outer surface 88. As shown in FIGS. 29B-29D, the polymeric tubular layer 84 can be formed with at least a first corner portion 90 of reduced thickness adjacent the inner surface 86 and a second corner portion 92 of reduced thickness adjacent the outer surface 88, with the second portion 92 at least partially overlapping the first portion 90. FIG. 29A shows a similar configuration in which the second portion 92 at least partially overlaps the first portion 90 in a partial coil configuration. In the embodiment of FIG. 29A, the second portion 92 and the first portion 90 can have the same thickness.

[0103] In preferred embodiments, the first and second portions 90, 92 are not adhered to one another. In some embodiments, best seen in FIG. 29A, there may be a small gap 94 between the first and second portions 90, 92, which can give the sheath 66 the appearance of having two lumens 72, 94. FIGS. 29A-29D show the sheath 66 in an unexpanded configuration. Preferably, upon expansion of the sheath 66, the ends of the first and second portions 90, 92 abut or closely contact one another, reducing or eliminating the gap between them.

[0104] In some embodiments, the sheath 66 can include a partial slit or scoreline along at least a portion of its length. For example, as shown in FIG. 33 , the sheath 66 can include an outer polymeric tubular layer 70 over an inner polymeric layer 68. The inner polymeric layer can extend through a cut in the outer polymeric tubular layer 70 to form a folded region 85 on the outer surface of the outer polymeric tubular layer 70, as also shown in FIG. 27C . The folded region 85 of the inner layer, in some embodiments, terminates before the outer polymeric tubular layer 70 (i.e., the outer polymeric tubular layer 70 is longer than the inner layer). As shown in FIG. 33 , in these embodiments, the sheath 66 can include a partial slit or scoreline 77 that can extend from the end (distal end) 75 of the folded region 85 to the distal end 40 of the sheath 66. In some embodiments, the scoreline 77 can facilitate expansion of the sheath 66.

[0105] The scoreline 77 can be substantially centrally located relative to the folding region 85. In alternative embodiments, the scoreline 77 can be located elsewhere relative to the folding region 85. The sheath 66 can also include one or more scorelines 77. For example, as shown in FIG. 34, the one or more scorelines 77 can be peripherally located relative to the folding region 85. The one or more scorelines 77 can be located anywhere around the circumference of the outer polymeric tubular layer 70. As can be seen in FIG. 33, in embodiments including a radiopaque marker 69, the scoreline 77 can extend, for example, from the distal end of the radiopaque marker 69 substantially to the distal end 40 of the sheath 66.

[0106] 35 and 36 illustrate an expandable sheath 100 according to the present disclosure that can be used in a delivery apparatus for delivering a prosthetic device, such as a biological heart valve, into a patient. Generally, the delivery apparatus can include a steerable guide catheter (also called a flex catheter) (e.g., as shown in FIG. 1 ), a balloon catheter extending through the guide catheter, and a nose catheter extending through the balloon catheter. The guide catheter, balloon catheter, and nose catheter can be adapted to slide longitudinally relative to one another to facilitate delivery and placement of the valve at an implantation site within the patient's body. It should be noted, however, that the sheath 100 can be used with any type of elongated delivery apparatus used to implant balloon-expandable prosthetic valves, self-expanding prosthetic valves, and other prosthetic devices. Generally, the sheath 100 can be inserted into a blood vessel (e.g., the femoral or iliac artery) by passing through the patient's skin so that the soft-tip portion 102 at the distal end 104 of the sheath 100 is inserted into the blood vessel. The sheath 100 may also include a proximal flared end 114 to facilitate mating with the introducer housing 101 and the catheter described above (e.g., the proximal flared end 114 may provide a compression fit onto the housing tip and / or the proximal flared end 114 may be secured to the housing 101 via a nut or other fastening device or by joining the proximal end of the sheath to the housing). The introducer housing 101 may contain one or more valves, as known in the art, that form a seal around the outer surface of a delivery device when inserted therethrough. A delivery device may be inserted into and through the sheath 100, allowing the prosthetic device to be advanced through the patient's vasculature and implanted within the patient.

[0107] The sheath 100 can include multiple layers. For example, the sheath 100 can include an inner layer 108 and an outer layer 110 disposed about the inner layer 108. The inner layer 108 defines a lumen through which a delivery device can travel in a direction along the longitudinal axis X and into a patient's blood vessel to deliver, remove, repair, and / or replace a prosthetic device. As a prosthetic device passes through the sheath 100, the sheath locally expands from a first resting diameter to a second expanded diameter to accommodate the prosthetic device. After the prosthetic device passes through a particular location in the sheath 100, each over-expanded portion or segment of the sheath 100 at least partially returns to its smaller, resting diameter. In this manner, the sheath 100 can be considered self-expanding in that it does not require the use of a balloon, dilator, and / or obturator to expand.

[0108] The inner and outer layers 108, 110 may be constructed of any suitable material. Suitable materials for the inner layer 108 include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), nylon, polyethylene, polyether block amide (e.g., Pebax), and / or combinations thereof. In one specific embodiment, the inner layer 108 may be constructed of a lubricious, low-friction, or hydrophilic material, such as PTFE. Such a low coefficient of friction material can facilitate passage of a prosthetic device through the lumen defined by the inner layer 108. In some embodiments, the inner layer 108 may have a coefficient of friction of less than about 0.1. Some embodiments of the sheath 100 may include a lubricious liner on the inner surface of the inner layer 108. Examples of suitable lubricious liners include materials that can further reduce the coefficient of friction of the inner layer 108, such as PTFE, polyethylene, polyvinylidene fluoride, and combinations thereof. Suitable materials for the lubricous liner also include other materials that desirably have a coefficient of friction of about 0.1 or less.

[0109] Suitable materials for the outer layer 110 include nylon, polyethylene, Pebax, HDPE, polyurethane (e.g., Tecoflex™), and other medical-grade materials. In one embodiment, the outer layer 110 can be constructed of high-density polyethylene (HDPE) and Tecoflex™ (or other polyurethane material) extruded as a composite. In some embodiments, the Tecoflex™ can act as an adhesive between the inner layer 108 and the outer layer 110 and need only be present along a portion of the inner surface of the outer layer 110. Other suitable materials for the inner and outer layers are also disclosed in U.S. Patent Application Publication No. 2010 / 0094392, which is incorporated herein by reference.

[0110] Additionally, some embodiments of the sheath 100 can include an external hydrophilic coating on the outer surface of the outer layer 110. Such a hydrophilic coating can facilitate insertion of the sheath 100 into a patient's blood vessel. Examples of suitable hydrophilic coatings include Harmony® Advanced Lubricious Coatings and other advanced hydrophilic coatings available from SurModics, Inc. of Eden Prairie, Minnesota. DSM Medical Coatings (available from Koninklijke DSM NV, Heerlen, The Netherlands), as well as other hydrophilic coatings (e.g., PTFE, polyethylene, polyvinylidine fluoride), are also suitable for use with the sheath 100.

[0111] As best seen in FIG. 36 , the soft-tip portion 102, in some embodiments, can be constructed from low-density polyethylene (LDPE) and configured to minimize trauma or damage to a patient's blood vessels as the sheath is navigated through the vasculature. For example, in some embodiments, the soft-tip portion 102 can be slightly tapered to facilitate passage through a blood vessel. The soft-tip portion 102 can be secured to the distal end 104 of the sheath 100, such as by thermally bonding the soft-tip portion 102 to an inner or outer layer of the sheath 100. Such a soft-tip portion 102 can have a lower hardness than the rest of the sheath 100. In some embodiments, the soft-tip 102 can have a Shore hardness of about 25D to about 40D. The tip portion 102 can be configured to be radially expandable to allow a prosthetic device to pass through a distal opening in the sheath 100. For example, the tip portion 102 can be formed with weakened portions, such as axially extending score lines or perforation lines, which are configured to split when a prosthetic device passes through the tip portion (as shown in the examples of Figures 33 and 34), allowing the tip portion to expand radially.

[0112] FIG. 37 shows a cross-sectional view of the sheath 100 taken near the distal end 104 of the sheath 100. As shown in FIGS. 36 and 37 , the sheath 100 can include at least one radiopaque filler or marker, such as a discontinuous or C-shaped band 112, disposed near the distal end 104 of the sheath 100. The marker 112 can be associated with the inner and / or outer layers 108, 110 of the sheath 100. For example, as shown in FIG. 37 , the marker 112 can be disposed between the inner layer 108 and the outer layer 110. In alternative embodiments, the marker 112 can be associated with the outer surface of the outer layer 110. In some embodiments, the marker 112 can be embedded or incorporated within the inner or outer layer 108, 110.

[0113] The C-shaped band 112 serves as a radiopaque marker or filler, allowing the sheath 100 to be visible under fluoroscopy during use within a patient. The C-shaped band 112 can be composed of any suitable radiopaque material, such as barium sulfite, bismuth trioxide, titanium dioxide, bismuth subcarbonate, platinum, iridium, and combinations thereof. In one specific embodiment, the C-shaped band can include 0% platinum and 10% iridium. In other embodiments, the marker 112 need not be a C-shaped band. Other shapes, designs, and configurations are also possible. For example, in some embodiments, the marker 112 can extend around the entire circumference of the sheath 100. In other embodiments, the marker 112 can include multiple small markers spaced around the sheath 100.

[0114] 38 and 39 show additional cross-sections taken at different points along the sheath 100. FIG. 38 shows a cross-section of a segment of the sheath near the proximal end 106 of the sheath 100, as indicated by line 38-38 in FIG. 35. The sheath 100 at this location may include an inner layer 108 and an outer layer 110. At this location, near the proximal end of the sheath, the layers 108, 110 may be substantially tubular, with no slits or folds within the layers. In contrast, the layers 108, 110 at different locations along the sheath 100 (e.g., the point indicated by line 39-39 in FIG. 35) may have different configurations.

[0115] As shown in FIG. 39 , the inner layer 108 can be arranged to form a substantially cylindrical lumen 116 therethrough. The inner layer 108 can include one or more folds 118. In the example shown in FIG. 39 , the inner layer 108 is arranged to have one fold 118 that can be located on one side of the inner layer 108. The fold 118 includes a first fold (e.g., a longitudinally extending fold line), a second fold, and an overlap extending circumferentially therebetween (when the sheath is in the unexpanded configuration). As shown in FIG. 39 , the fold 118 includes a radial overlap that at least doubles the inner layer 108. The inner layer 108 can be continuous, in that there are no breaks, slits, or perforations in the inner layer 108. The outer layer 110 can be arranged in an overlapping manner such that the overlapping portion 120 overlaps at least a portion of the folded portion 118 of the inner layer 108. As shown in FIG. 39 , the overlapping portion 120 also overlaps an underlying portion 122 of the outer layer 110. The underlying portion 122 can be positioned to underlie both the overlapping portion 120 of the outer layer 110 and the folded portion 118 of the inner layer 108. That is, the outer layer 110 can be discontinuous in that it includes slits or cuts to form the overlapping portion 120 and the underlying portion 122. In other words, the first edge 124 of the outer layer 110 is spaced from the second edge 126 of the outer layer 110 so as not to form a continuous layer.

[0116] As shown in FIG. 39 , the sheath 100 can also include a thin layer of bonding or adhesive material 128, also referred to as a tie layer, disposed between the inner and outer layers 108, 110. In one embodiment, the adhesive material 128 can be comprised of a polyurethane material such as Tecoflex® or etched PTFE tubing. The adhesive material 128 can be disposed on at least a portion of the inner surface 130 of the outer layer 110 to provide adhesion between selected portions of the inner and outer layers 108, 110. For example, the outer layer 110 can include the adhesive layer 128 only around the portion of the inner surface 130 that faces the lumen-forming portion of the inner layer 108. In other embodiments, the adhesive layer 128 can be disposed such that it does not contact the folded portion 118 of the inner layer 108. In other embodiments, the adhesive layer 128 can be disposed in a different configuration as desired for a particular application. For example, as shown in FIG. 39 , the adhesive layer 128 can be disposed along the entire inner surface 130 of the outer layer 110. In an alternative embodiment, the adhesive layer can be applied to the outer surface of the inner layer 108 instead of the inner surface of the outer layer. The adhesive layer 128 can be applied to all or selected portions of the inner layer 108; for example, the adhesive layer 128 can be formed only on the portion of the inner layer facing the lumen-forming portion of the outer layer, and not on the folded portion. The configuration of FIG. 39 allows the sheath 100 to radially expand when an outward radial force is applied from the inside (e.g., by passing a medical device, such as a prosthetic heart valve, through the lumen 116). When the radial force is applied, the folded portion 118 at least partially separates, straightens, and / or unfolds, and / or the overlapping portion 120 and the underlying portion 122 of the outer layer 110 can slide circumferentially relative to one another, thereby expanding the diameter of the lumen 116.

[0117] In this manner, the sheath 100 is configured to expand from a resting configuration ( FIG. 39 ) to an expanded configuration shown in FIG. 40 . In the expanded configuration, an annular gap 132 can be formed between the longitudinal edge of the overlapping portion 120 and the longitudinal edge of the underlying portion 122 of the outer layer 110, as shown in FIG. 40 . When the sheath 100 expands at a particular location (i.e., expands locally at the location of the prosthetic device being passed therethrough), the overlapping portion 120 of the outer layer 110 can move circumferentially relative to the underlying portion 122 as the folded portions 118 of the inner layer 108 unfold. This movement can be facilitated by the use of a low-friction material for the inner layer 108, such as PTFE. Additionally, the folded portions 118 can at least partially separate and / or unfold to accommodate a medical device having a larger diameter than the lumen 116 in the resting configuration. As shown in FIG. 40, in some embodiments, the folded portions of the inner layer 108 are allowed to fully unfold, such that the inner layer 108 forms a cylindrical tube in the expanded configuration.

[0118] The sheath 100 can be configured to locally expand at specific locations along the length of the lumen 116 corresponding to the location of a medical device, and then locally contract once the medical device has passed that specific location. That is, as a medical device is introduced through the sheath, a bulge is visible that moves longitudinally along the length of the sheath, demonstrating successive local expansions and contractions as the device moves down the length of the sheath 100. In some embodiments, each segment of the sheath 100 can locally contract after removal of the outward radial force, thereby allowing each segment of the sheath 100 to resume its original resting diameter of the lumen 116. In some embodiments, each segment of the sheath 100 can locally contract after removal of the outward radial force, thereby at least partially returning to its original resting diameter of the lumen 116.

[0119] The layers 108, 110 of the sheath 100 can be configured along at least a portion of the length of the sheath 100, as shown in Figure 39. In some embodiments, the layers 108, 110 can be configured along a length A (Figure 35) that extends from adjacent the soft tip portion 102 to near the proximal end 106 of the sheath 100, as shown in Figure 39. In this regard, the sheath is expandable and contractible only along a portion of the sheath length corresponding to length A (which typically corresponds to the section of the sheath inserted into the narrowest cross section of the patient's vasculature).

[0120] The sheath 100 of FIG. 35 can include an outer jacket 140 extending over the outer layer 100. FIGS. 53 and 54 show additional cross sections taken at different points along the sheath 100. Similar to FIG. 38, FIG. 53 shows a cross section of a segment of the sheath near the proximal end 106 of the sheath 100, as indicated by line 38-38 in FIG. 35. The sheath 100 at this location can include an inner layer 108, an outer layer 110, an adhesive layer 128, and an outer jacket 140. At this location near the proximal end of the sheath, the layers 108, 110, and the outer jacket 140 can be substantially tubular, without slits or folds in the layers. In contrast, layers 108, 110 at different locations along sheath 100 (e.g., at the points indicated by line 39-39 in FIG. 35) may have different configurations, while outer jacket 140 remains substantially tubular without slits or creases.

[0121] As shown in FIG. 54 and described above with respect to FIG. 39 , the inner layer 108 can be arranged to form a substantially cylindrical lumen 116 extending therethrough. The inner layer 108 can include one or more folded portions 118. The outer layer 110 can be arranged in an overlapping manner such that, when the sheath is in an unexpanded state, the overlapping portion 120 overlaps at least a portion of the folded portion 118 of the inner layer 108, as well as an underlying portion 122 (positioned to underlie the folded portion 118 of the inner layer 108). The sheath 100 is configured to locally expand from an unexpanded configuration, in which the lumen 116 has a first diameter, to an expanded configuration, in which the lumen 116 has a second diameter greater than the first diameter. The sheath 100 expands in response to an outward radial force exerted by a medical device on the inner layer 108 when the medical device passes through the lumen 116. During expansion, the first crease / fold edge moves closer to the second crease / fold edge, shortening the folded portion 118. As shown in FIG. 55 , in some embodiments, the folded portion 118 of the inner layer 108 can fully unfold, such that the inner layer 108 forms a cylindrical tube in the expanded configuration. When the sheath is expanded, a portion of the inner layer 108 expands through an opening / gap in the outer layer 110, where the opening is formed by the longitudinally extending edge of the overlapping portion 120 and the longitudinally extending edge of the underlying portion 122. Once the prosthetic device has passed, the sheath 100 then locally contracts and at least partially returns to the unexpanded configuration.

[0122] As described above, the sheath 100 includes an inner layer 108. The inner layer 108 can be surface treated, for example, by plasma etching, chemical etching, or other suitable surface treatment methods. By treating the surface of the inner layer 108, the outer surface of the inner layer 108 can have areas with modified surface angles, which can provide better adhesion between the inner layer 108 and the outer layer 110. As described above, the inner layer 108 can be composed of polytetrafluoroethylene (PTFE), polyimide, polyetheretherketone (PEEK), polyurethane, nylon, polyethylene, polyamide, or combinations thereof. In the exemplary sheath 100, the inner layer 108 is composed of an etched PTFE material. It is contemplated that the inner layer 108 can have a fully etched outer surface or a partially etched outer surface. When partially etched, the unetched portions of the outer surface of the inner layer 108 can extend longitudinally along the length of the inner layer 108 and / or can extend circumferentially around the periphery of the inner layer 108. For example, desired unetched locations on the inner layer 108 can be masked or otherwise covered during the etching process to prevent etching at those locations. It is also contemplated that the entire outer surface of the inner layer 108 can be etched to remove etching at desired locations of the unetched surface.

[0123] In the exemplary sheath 100, the unetched portions are provided along those surfaces of the inner layer 108 that contact the outer surface of the outer layer 110. That is, those portions of the inner layer 108, excluding the tie layer 130, do not include etching. For example, it is contemplated that no etching is included between the inner surface of the folded portion 118 of the inner layer 108 and the underlying portion 122 of the outer layer 110. Excluding etching where the inner layer 108 and the outer surface of the outer layer 110 directly contact each other helps facilitate release of the inner surface of the folded portion 118 and the outer layer 110 during expansion of the sheath 100.

[0124] Again, as disclosed above, the wall thickness of the inner layer can vary, but in some embodiments, the wall thickness of the inner layer 108 ranges between about 0.002 inches and about 0.006 inches (including about 0.002 inches, about 0.003 inches, about 0.004 inches, about 0.005 inches, and about 0.006 inches). In other embodiments, the wall thickness of the inner layer ranges between about 0.003 inches and about 0.005 inches. In yet other embodiments, the wall thickness of the inner layer 108 ranges between about 0.0035 inches and about 0.0045 inches (including about 0.0035 inches, about 0.0040 inches, and about 0.0045 inches).

[0125] As mentioned above, the sheath 100 includes an outer layer 110 that applies a radially inward force to the inner layer 108. Generally, the outer layer 110 can be constructed of a polymeric material. As mentioned above, the outer layer 110 can be constructed of PTFE, polyimide, PEEK, polyurethane, nylon, polyethylene, polypropylene, polyamide, polyether block amide, polyether block ester copolymer, thermoset silicone, latex, polyisoprene rubber, high density polyethylene (HDPE), Tecoflex™, or a combination thereof. In one exemplary embodiment, the inner layer 108 can be constructed of PTFE, and the outer layer 110 can be constructed of a combination of HDPE and Tecoflex™. The outer layer 110 can have a thickness ranging between about 0.007 inches and about 0.013 inches (including 0.007 inches, about 0.008 inches, about 0.009 inches, about 0.010 inches, about 0.011 inches, about 0.012 inches, and about 0.013 inches). In another embodiment, the outer layer 110 can have a thickness ranging between about 0.008 inches and about 0.012 inches. In another embodiment, the outer layer 110 can have a thickness ranging between about 0.009 inches and about 0.011 inches.

[0126] As mentioned above, the sheath 100 includes an outer jacket 140 that extends over and surrounds the outer layer 110. The outer layer 110 may be discontinuous in that it includes slits or cuts to form the overlapping and underlying portions 120, 122, as mentioned above, whereas the outer jacket 140 may include a continuous outer layer that covers the inner and outer layers 108, 110.

[0127] The outer jacket 140 can be constructed of a rubber-elastic material, such as a soft polymer material, that has good elasticity while also being abrasion- and tear-resistant. Typically, the outer jacket 140 has a relatively low tensile modulus compared to the inner and outer layers 108, 110. Examples of materials for the outer jacket 140 include thermoplastic polyurethanes, such as Neusoft® and Tecoflex™ 80A B20. In some embodiments, the outer jacket 140 is constructed of an elastomer (e.g., a elastomeric polymer) with a Shore hardness (durometer) ranging between about 10 and about 95 Shore A. The outer jacket 140 can be composed of an elastomer having an elongation at break in the range between about 40% and about 800% (including about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, about 100%, about 150%, about 200%, about 250%, about 300%, about 350%, about 400%, about 450%, about 500%, about 550%, about 600%, about 650%, about 700%, and about 800%). The outer jacket 140 can be constructed of an elastomer having a wall thickness ranging between about 0.003 inches and about 0.015 inches (including about 0.003 inches, about 0.004 inches, about 0.005 inches, about 0.006 inches, about 0.007 inches, about 0.008 inches, about 0.009 inches, about 0.010 inches, about 0.011 inches, about 0.012 inches, about 0.013 inches, about 0.014 inches, and about 0.015 inches). The wall thickness is measured radially between the inner surface of the outer jacket 140 and the outer surface of the outer jacket 140.

[0128] In some embodiments, the outer jacket 140 is constructed of a single material or combination of materials that has a constant thickness along the entire length of the outer jacket 140. In alternative embodiments, the material composition and / or wall thickness can vary along the length of the outer jacket 140. For example, the outer jacket 140 can have one or more segments that vary in composition and / or thickness from segment to segment. In one embodiment, the durometer rating of the composition varies along the length of the outer jacket 140, such that the segment near the proximal end is constructed of a stiffer material or combination of materials, while the segment near the distal end is constructed of a softer material or combination of materials. Similarly, the wall thickness of the outer jacket 140 in the segment near the proximal end can be thicker / greater than the wall thickness of the outer jacket 140 near the distal end.

[0129] 61 and described in more detail below with respect to FIGS. 62-65, outer jacket 140 includes one or more axial reinforcing members 145 that extend longitudinally along all or a portion of outer jacket 140. Reinforcing members 145 provide rigidity to prevent axial bunching of outer jacket 140 during insertion into a patient's vasculature without sacrificing the low radial expansion force of outer jacket 140.

[0130] As shown in FIG. 35 , the sheath 100 can include a tapered segment adjacent to a flared end 114 at the proximal end of the sheath 100. Referred to as a strain relief section, the tapered segment and flared end 114 help facilitate the transition between the smaller diameter portion of the sheath 100 and the housing 101. The thickness and / or composition of the outer jacket 140 can be adjusted to increase the durometer and / or stiffness along the strain relief section. Because this portion of the sheath 100 is typically outside the patient's body during a procedure, providing the outer jacket 140 with a greater durometer and / or stiffness along the strain relief section helps it withstand blood pressure that would otherwise cause the outer jacket 140 to “balloon up” with bodily fluids / blood. As a result, the sheath 100 has a relatively stiff proximal end at the point where it introduces a delivery device, yet has a relatively soft distal tip at the point of entry into the patient's vasculature.

[0131] The outer jacket 140 can be bonded to the outer layer 110 to prevent the outer jacket 140 from sliding over and “bunching up” the outer layer 110 in response to frictional forces exerted by surrounding tissue during insertion of the sheath 100 into the patient's vasculature. For example, the outer jacket 140 can be bonded to the proximal and / or distal ends of the outer layer 110. At the proximal and distal ends, the outer jacket 140 can be bonded to the outer layer 110 around the entire circumference of the outer layer. At the distal end of the sheath 100, the outer jacket 140 can alternatively be bonded to the inner layer 108. For example, the outer jacket 140 can be bonded to the distal end surface of the inner layer 108.

[0132] As shown in FIG. 57, the outer jacket 140 can be bonded 144 to the outer layer 110 at a peripheral location opposite the fold-over portion 118 of the inner layer 108. As provided in FIGS. 58-59, the bond 144 can be a spot bond or a linear bond line extending along all or a portion of the outer layer 110. As provided in FIG. 57, the bond 144 line / spot will also have a width, which extends around the circumference of the outer layer 110. For example, the bond line can cover from about 5° to about 90° of the circumference of the outer layer 110 (including about 5°, about 10°, about 15°, about 20°, about 25°, about 30°, about 35°, about 40°, about 45°, about 50°, about 55°, about 60°, about 65°, about 70°, about 75°, about 80°, about 85°, and about 90°).

[0133] The outer jacket 140 can be bonded to the outer layer 110 and / or inner layer 108 using mechanical and / or chemical (e.g., adhesive) fasteners known in the art. In one embodiment, the sheath 100, outer jacket 140, and outer layer 110 and / or inner layer 108 may have similar melting temperatures. Accordingly, an exemplary bonding method includes a thermally bonded bond between the outer jacket 140, outer layer 110, and / or inner layer 108. For example, the bond between the outer jacket 140 and outer layer 110 can be achieved by laser welding and / or thermal compression (e.g., using thermal compression jaws), allowing for precise control of the location of the bond line.

[0134] 54 and described with respect to FIG. 39, an adhesive layer 128 (e.g., a tie layer) is provided between the inner layer 108 and the outer layer 110 to at least partially adhere the inner layer 108 to the outer layer 110. That is, the adhesive layer 128 is selectively provided / placed between the inner layer 108 and the outer layer 110 to join the inner and outer layers 108, 110 at selected locations of the adhesive layer 128.

[0135] As shown in FIG. 54 (and FIG. 39 ), adhesive layer 128 is provided on the outer surface of inner layer 108 and / or on the inner surface 130 of outer layer 110. For example, adhesive layer 128 can be provided partially or completely around the outer surface of inner layer 108. Additionally or alternatively, adhesive layer 128 can be provided partially and / or completely around the inner surface 130 of outer layer 110. As shown in FIG. 54 , adhesive layer 128 extends between the outer layer 110 and the overlapping folded portion 118 of inner layer 108. That is, adhesive layer 128 extends between the outer surface of folded portion 118 of inner layer 108 and the corresponding inner surface of overlapping portion 120 of outer layer 110. 54, adhesive layer 128 does not extend between the inner surface of overlapping folded portion 118 of inner layer 108 and the corresponding surface of portion 122 underlying the outer surface of outer layer 110. Eliminating adhesive layer 128 on the portion of the sheath between the inner surface of folded portion 118 and underlying portion 122 facilitates expansion of the sheath and prevents undesired adhesion / sticking between the inner and outer layers 108, 110 at this location.

[0136] The adhesive material 128 can include a material having a Shore A hardness (durometer) of less than about 90A. For example, the adhesive material 128 can include a thermoplastic polyurethane, such as an aliphatic polyether-based thermoplastic polyurethane (TPU). An exemplary TPU is Tecoflex™ 80A. The adhesive layer 128 can also be composed of an aromatic polyether- or polyester-based thermoplastic polyurethane, such as Pellethane™ 80A. The adhesive layer can also be composed of a polyolefin or polyamide, including, for example, a maleic anhydride-modified polyolefin (PE, PP, or EVA), such as Orevac™ resin.

[0137] The thickness (wall thickness) of adhesive layer 128 can vary, but in some embodiments, the thickness of adhesive layer 128 ranges from about 0.002 inches to about 0.005 inches (including about 0.002 inches, about 0.003 inches, about 0.004 inches, and about 0.005 inches). In other embodiments, the thickness of adhesive layer 128 ranges from about 0.0025 inches to about 0.0040 inches (including about 0.0025 inches, about 0.0030 inches, about 0.0035 inches, and about 0.0040 inches). In yet other embodiments, the thickness of adhesive layer 128 ranges from about 0.0025 inches to about 0.0035 inches (including about 0.0025 inches, about 0.0030 inches, and about 0.0035 inches).

[0138] In some embodiments, the sheath 100 can include a lubricant to reduce friction and facilitate expansion / contraction between the outer layer 110 and the outer jacket 140. The lubricant 142 allows the outer layer 110 and the inner layer 108 to easily expand under the outer jacket 140, ensuring that the hemostatic and atraumatic benefits provided by the addition of the outer jacket 140 do not impair the pushing force performance of the sheath 100. That is, the lubricant 142 reduced the pushing force required to move a prosthetic device through the central lumen 116 of the inner layer 108 during delivery of the prosthetic device and corresponding local expansion of the sheath 100.

[0139] As shown in FIG. 56 , the lubricant 142 can be selectively applied along the outer surface of the outer layer 110 near the longitudinally extending edge 126 of the overlapping portion 120. In some embodiments, a portion of the folded portion 118 of the inner layer 108 extends along the outer surface of the outer layer 110 beyond the longitudinally extending edge 126 of the overlapping portion 120. In this embodiment, the lubricant 142 is also provided along the protruding portion of the folded portion 118 of the inner layer 108 that extends along the outer surface of the outer layer 110 (beyond the edge 126). In this location, the lubricant 142 also reduces friction between the outer jacket 140 and the inner layer 108 during expansion of the sheath 100. As shown in FIG. 56 , the lubricant 142 extends around the circumference of the outer layer 110 beyond the protruding portion of the folded portion 118.

[0140] The lubricant is applied as a band (or spot) that extends both circumferentially and longitudinally along the outer layer 110 (and the protruding portion of the inner layer 108). In the exemplary sheath 100, the lubricant 142 is applied as a band that extends both circumferentially around the outer layer 110 and longitudinally along the length of the outer layer 110. To prevent migration, the lubricant 142 can be composed of a thermosetting material, such as a material that hardens at room temperature. As a result, the material is applied in the desired location along the outer layer 110 and will not migrate during assembly and / or use of the sheath 100. The lubricant 142 can be composed of a medical-grade lubricant, such as silicone. Exemplary lubricants include medical-grade curable silicone lubricants, including platinum-catalyzed thermoset silicone lubricants such as NuSil™ MED10-6670 (thermoset), PTFE lubricants such as Duraglide™ (room temperature curable) and / or CHRISTO-LUBE™.

[0141] FIG. 60 illustrates an additional embodiment of the sheath 100 of FIG. 35. In this embodiment, the sheath 100 can include a coiled wire 160, or a coiled wire mesh, along the length of the sheath 100. The coiled wire 160 provides uniform bending of the sheath and prevents kinking. The coiled wire 160 can be embedded in the outer layer 110. For example, the coiled wire 160 can be co-extruded with the outer layer 110. Alternatively, the coiled wire 160 can be disposed between the outer layer and the adhesive layer 128. In another embodiment, the coiled wire 160 is at least partially embedded within both the outer layer 110 and the adhesive layer 128. For example, the coiled wire 160 can be disposed on the outer surface of the adhesive layer 128, with the outer layer 110 reflowed on top.

[0142] 60, the coiled wire 160 defines a helical path around the longitudinal axis of the sheath 100. This exemplary coiled wire 160 includes overlapping helical paths around the longitudinal axis of the sheath 100, resulting in a continuous diamond-shaped pattern along the length of the sheath.

[0143] The coiled wire 160 can be comprised of a metal or polymer wire. For example, the coiled wire 160 can be comprised of PET, PEEK, stainless steel, and / or Nitinol. The coiled wire 160 can be comprised of a flat wire, a round wire, or a combination thereof. The diameter / thickness of the individual wires of the coiled wire 160 ranges from about 0.002 inches to about 0.008 inches (including about 0.002 inches, about 0.003 inches, about 0.004 inches, about 0.005 inches, about 0.006 inches, about 0.007 inches, and about 0.008 inches). In another example, the diameter / thickness of the individual wires of the coiled wire 160 ranges from about 0.004 inches to about 0.007 inches. In yet another example, the diameter / thickness of the individual wires of the coiled wire 160 is about 0.006 inches. The pitch / distance between adjacent coils of the coiled wire 160 can correspond to the diameter / thickness of the coiled wire. For example, if the diameter / thickness of a single coil of the coiled wire is approximately 0.006 inches, then the spacing / pitch between that wire and the next adjacent coiled wire is approximately 0.006 inches.

[0144] 53-60 includes first inserting the expandable sheath 100 into the vasculature of a subject and advancing a prosthetic device through the inner layer 108 / lumen 116 of the sheath 100. The prosthetic device exerts an outward radial force on the inner layer 108 of the expandable sheath 100. In some embodiments, the outward radial force is transmitted through the inner layer 108, the adhesive layer 128, and the outer layer 110. The lumen 116 of the sheath 100 expands at the axial location of the prosthetic device due to the outward radial force exerted by the prosthetic device against the inner surface of the lumen during advancement. During expansion of lumen 116, the first fold (folded edge) of folding portion 118 is moved circumferentially closer to the second fold (folded edge), shortening the overlapping portion of folding portion 118 that extends circumferentially between the first and second folds, thereby increasing the circumference of lumen 116.

[0145] As the sheath 100 expands at a particular location (i.e., expands locally at the location of the prosthetic device being passed), the overlapping portion 120 of the outer layer 110 can move circumferentially relative to the underlying portion 122 as the folded portions 118 of the inner layer 108 at least partially separate and / or unfold, widening / expanding an elongated gap 132 in the outer layer 110. The sheath thereby expands to accommodate a medical device having a diameter larger than the diameter of the lumen 116 in the resting (unexpanded) configuration. As shown in FIG. 55 , in some embodiments, the folded portions of the inner layer 108 can fully unfold, resulting in the inner layer 108 forming a cylindrical tube at the expanded configuration. As shown in FIGS. 54 and 55 , during expansion, the elongated gap 132 is generally aligned with the longitudinal axis of the lumen 116 such that the unfolded portions of the inner layer 108 expand into the gap 132.

[0146] In the unexpanded configuration, the outer diameter of the sheath 100 can be less than about 0.030 inches (including less than about 0.029 inches, less than about 0.028 inches, less than about 0.027 inches, less than about 0.026 inches, less than about 0.025 inches, and less than about 0.024 inches). Preferably, the outer diameter of the unexpanded sheath ranges between about 0.024 inches and about 0.026 inches. In the fully expanded configuration, the inner diameter of the sheath 100 can be greater than 0.040 inches. Preferably, the inner diameter of the expanded sheath 100 ranges between 0.046 inches and 0.054 inches (including about 0.046 inches, about 0.047 inches, about 0.048 inches, about 0.049 inches, about 0.050 inches, about 0.051 inches, about 0.052 inches, about 0.053 inches, and about 0.054 inches).

[0147] As described above, the inner and outer layers 108, 110 can be bonded to one another using an adhesive layer 128. The adhesive layer 128 prevents both longitudinal and radial movement between the inner and outer layers 108, 110. As a result, expansion of the sheath 100 can be limited to these regions, excluding the adhesive layer 128. For example, as shown in FIG. 54 , because the adhesive layer 128 is not provided between the inner surface of the folded portion 118 and the underlying portion 122 of the outer layer, expansion of the sheath results in the inner surface of the folded portion expanding into the gap 132 created between the first and second edges 124, 126 of the expanded outer layer 110.

[0148] Once the prosthetic device has passed through the lumen 116 (or a particular location along the lumen), the sheath lumen 116 can at least partially contract and return to its unexpanded configuration. The outer layer 110 can exert an inward radial force on the inner layer 108, urging them to return to their original, folded configuration. Similarly, if a coiled wire 160 is included, the coiled wire can exert an inward radial force on the outer layer 110 and the inner layer 108, urging them to return toward their unexpanded configuration. Similarly, if an outer jacket 140 is included, the outer jacket 140 can exert an inward radial force on the outer layer 110 and the inner layer 108, urging them to return to their unexpanded configuration.

[0149] A prosthetic device can be delivered to a delivery site within a patient through the distal end of the sheath 100. The prosthetic device can include a self-expanding heart valve or a stented heart valve. At the delivery site, the heart valve can be expanded through the distal end of the elongated lumen 116. Once outside the lumen 116, the heart valve can be expanded and the sheath 100 can be removed from the treatment site.

[0150] An exemplary method of fabricating a sheath is as follows. These steps are not meant to be limiting. Given steps can be reordered as needed. Other steps may be added, and in other embodiments, some steps may not be required. A continuous inner layer 108 is provided that defines a lumen therethrough. The inner layer 108 is formed to include first and second folds and an overlapping fold 118 extending circumferentially between the first and second folds. The overlapping fold 118 is formed to include at least two radial overlaps of the inner layer 108. The inner layer 108, including the fold 118, can be extruded. Alternatively, the fold 118 can be formed after the inner layer 108 is extruded (e.g., formed onto a cylindrical tubular structure).

[0151] A discontinuous outer layer 110 is disposed (at least partially) around the inner layer 108. The outer layer 110 includes an overlapping portion 120 and an underlying portion 122, and is formed such that at least a portion of the folded portion 118 of the inner layer 108 is disposed between the overlapping portion 122 and the underlying portion 120. In some embodiments, the inner layer 108 and the outer layer 110 are coextruded. In alternative embodiments, the inner layer 108 and the outer layer 110 are formed separately and then interconnected.

[0152] An adhesive layer 128 is provided between the inner layer 108 and the outer layer 110 to (at least partially) bond the inner layer 108 to the outer layer 110. The adhesive layer 128 can be applied to and bond the inner and outer layers 108, 110 axially along the length of the sheath, for example, along a portion of the entire length of the sheath or along the entire length of the sheath. In one embodiment, the adhesive layer 128 is coextruded with the outer layer 110. In yet another embodiment, the adhesive layer 128 is coextruded with the inner layer 108. In an alternative exemplary method, the adhesive layer 128 can be applied to the outer surface of the inner layer 108 and / or the inner surface of the outer layer 110.

[0153] After the adhesive layer 128 is applied at desired locations along the inner and / or outer layer 110, the outer layer 110 is applied over the inner layer 108. The outer layer 110 can then be bonded to the inner layer 108 by heat-curing the adhesive layer 128. The adhesive layer 128 can be composed of a material that can be cured at temperatures above room temperature, in which case a heat treatment can be applied to the assembled inner layer 108 / outer layer 100. The adhesive layer 128 can also be composed of a material that cures at room temperature. Thus, after application of the adhesive layer 128 (at a temperature below room temperature) and assembly of the outer layer 100 onto the inner layer 108, the temperature of the combined layers can be raised to room temperature.

[0154] As shown in FIG. 56 , the lubricant 142 can be selectively applied to desired locations along the length of the outer layer 110 and / or the outer jacket 140. As described above, the lubricant 142 can be placed on the outer surface of the outer layer 110 near the longitudinally extending edge 126 of the overlapping portion 120, on any portion of the folded portion 118 that extends / protrudes beyond the edge 126, and / or on any portion of the outer surface of the outer layer 110 adjacent the protruding portion of the folded portion 118. The lubricant 142 can be applied as a band extending around a portion of the circumference of the outer layer, the band of lubricant 142 also extending longitudinally along the length of the outer layer 110. After the lubricant 142 has been selectively applied to the outer surface of the outer layer 110, the outer jacket 140 can be applied over the outer layer 110. As outlined above, the lubricant 142 can be comprised of a thermosetting material, in which case a heat treatment can be applied to the outer layer 110 / outer jacket 140. The lubricant 142 can also be comprised of a material that hardens at room temperature. Thus, after application of the lubricant 142 (which may be below room temperature), the temperature of the outer layer 110 can be raised to room temperature (either separately or in combination with the outer jacket 140).

[0155] The outer jacket 140 can then be applied over / around the outer layer 110 and bonded to the outer layer 110 at at least one of the proximal and distal ends of the outer layer 110. The outer jacket 140 can also be bonded to the outer layer 110 along the length of the outer layer 110. The outer jacket 140 can be bonded to the outer layer 110 via a heat treatment process, such as a reflow process, in which the outer layer 110 and the outer jacket are heated to a sufficiently high temperature to at least partially melt the outer layer 110 and the outer jacket 140, and then fused together as the heat is removed and the assembly cools. The entire sheath 100 assembly may be reflowed to reduce the overall outer diameter and restore / ensure a circular shape in cross section.

[0156] As discussed above, select portions of the outer surface of the inner layer 108 may include a surface treatment, such as a surface etch. In an exemplary method, the surface treatment of the inner layer 108 is performed before applying the outer layer 110. It is contemplated that it may be desirable to exclude etching from those surfaces of the inner layer 108 that contact the outer surface of the outer layer 110. For example, etching may not be included between the inner surface of the folded portion 118 of the inner layer 108 and the underlying portion 122 of the outer layer 110. Excluding etching from the portion where the outer surfaces of the inner layer 108 and the outer layer 110 are in direct contact facilitates release of the inner surface of the folded portion 118 and the outer layer 110 during expansion of the sheath 100.

[0157] In some cases, it may be necessary to release ("break") an undesired bond that occurs between the outer layer 110 and the inner layer 108. This bond can occur due to etching on the outer surface of the inner layer 108 that allows it to adhere directly to the outer layer 110 (with or without the adhesive layer 128). An undesired bond can also occur if the outer layer 110 is able to flow over the folded inner layer 108 and "grabs" it during the reflow process.

[0158] However, when the inner layer 108 is not etched along those locations that exclude the adhesive layer 128, e.g., those portions adjacent to the underlying portion of the outer layer 110, undesired bonding between the outer layer 110 and the inner layer 108 at these locations is limited. Thus, preconditioning the sheath to release undesired bonding between the inner layer 108 and the outer layer 110 may not be necessary because bonding has not yet occurred (or is unlikely to occur).

[0159] Nonetheless, any undesired bond between the inner layer 108 and the underlying portion 122 of the outer layer 110 can be released while maintaining the desired bond at the proximal and distal ends of the sheath 100. For example, a mandrel can be passed at least partially through the lumen 116 of the inner layer 108 to expand the inner layer 108 and the outer layer 110 and break / release any undesired bond between the underlying portion 122 of the inner layer 108 and the outer layer 110.

[0160] Figures 41-49 illustrate additional embodiments and variations on the general sheath 100 described above. It should be understood that the variations (e.g., materials and alternative configurations) described above with reference to Figures 35-40 also apply to the embodiments shown in Figures 41-49. Additionally, the variations described below with reference to Figures 41-49 are also applicable to the sheaths described in Figures 35-40.

[0161] 41-43 illustrate a sheath 700 that further includes a strain relief covering, also referred to as an elastic outer covering, or elastic covering 702, disposed around at least a portion of the inner layer 704 and the outer layer 706. As shown in FIG. 41 , the elastic covering 702 can extend a length L along at least a portion of the body of the sheath 700. In some embodiments, the elastic covering 702 can extend from the proximal end 708 of the sheath 700 toward the distal end 709 of the sheath. In some embodiments, the elastic covering 702 extends only partway along the length of the sheath 700. In alternative embodiments, the elastic covering 702 can extend to a point adjacent the distal end 709 or can extend all the way to the distal end 709 of the sheath 700. Furthermore, the elastic outer covering 702 need not extend all the way to the proximal end 708 of the sheath 700. In some embodiments, the elastic outer covering 702 can extend only partway toward the proximal end 708. In some embodiments, the longitudinal length L of the elastic covering 702 can range from about 10 cm to the entire length of the sheath 700.

[0162] As shown in FIGS. 42 and 43 , the elastic covering 702 can be a continuous tubular layer without slits or other discontinuities. The elastic covering 702 can be positioned to surround the entire circumference of the outer layer 706 and can extend longitudinally along any portion of the length of the sheath 700. The elastic outer covering 702 can be constructed of any flexible, resilient material that preferably expands and contracts at a high expansion ratio. Preferably, materials used include low-durometer polymers with high elasticity, such as Pebax, polyurethane, silicone, and / or polyisoprene. The material for the elastic outer covering 702 can be selected so that it does not interfere with the expansion of the sheath 700. Indeed, the elastic outer covering 702 can stretch and expand as the sheath 700 expands, such as by a folded or scored inner liner moving relative to itself.

[0163] The elastic outer covering 702, in some embodiments, can provide hemostasis (e.g., prevent blood loss during implantation of the prosthetic device). For example, the elastic outer covering 702 can be sized or configured to form a seal with the patient's artery when inserted, thereby substantially preventing blood from flowing between the elastic outer covering 702 and the vessel wall. The elastic outer covering 702 can be inserted such that it passes through an arteriotomy. For example, in embodiments in which the elastic outer covering 702 does not extend completely to the distal end 709 of the sheath 700, the elastic covering 702 can extend distally far enough such that at least a portion of the elastic outer covering extends through the arteriotomy site when the sheath 700 is fully inserted into the patient.

[0164] The thickness of the resilient outer cover can range, for example, from about 0.001 inches to about 0.010 inches. In some embodiments, the outer cover can have a thickness of from about 0.003 inches to about 0.006 inches. The resilient outer cover can be configured to expand as the sheath expands, as shown in the expanded configuration in FIG. 43.

[0165] FIG. 42 shows a cross-section of sheath 700 in a resting configuration having an inner diameter D1. FIG. 43 shows a cross-section of sheath 700 in an expanded configuration having an inner diameter D2, where D2 is greater than D1. Similar to the embodiment of FIGS. 35-40 , sheath 700 can include an inner layer 704 having a folded portion 710 and an outer layer 706 having an overlapping portion 712 and an underlying portion 714. Overlapping portion 712 overlaps at least a portion of folded portion 710 of the inner layer, and underlying portion 714 underlies at least a portion of folded portion 710. As shown in FIGS. 42-43 , in some embodiments, overlapping portion 712 does not overlap the entire folded portion 710 of inner layer 704, and thus a portion of folded portion 710 can be directly adjacent to elastic outer covering 702 where elastic covering 702 is present. Where elastic covering 702 is not present, a portion of folded portion 710 may be visible from the outside of sheath 700, as can be seen in FIG. 41 . In these embodiments, sheath 700 may include a longitudinal seam 722 where overlapping portion 712 terminates at folded portion 710. In use, the sheath may be positioned so that seam 722 is behind a point on the sheath that is 180 degrees from seam 722 (e.g., facing downward in the view of FIG. 41 ). Seam 722 is also visible in FIG. 41 , which illustrates that seam 722 need not extend the entire length of the sheath. In some embodiments, the proximal end portion of the sheath includes two layers without folded portions (e.g., similar to FIG. 38 ), while the distal end portion of the sheath includes two layers with folded portions (e.g., similar to FIG. 39 ). In some embodiments, the seam 722 can terminate at a transition point between a portion of the sheath that has a folded inner layer and a portion of the sheath that does not have a folded inner layer.

[0166] In some embodiments, the folded portion 710 can include a weakened portion, such as a longitudinal perforation, score line, and / or slit 716, along at least a portion of the length of the inner layer 704. The slit 716 can allow two adjacent ends 718, 720 of the folded portion 710 to move relative to one another as the sheath 700 expands to the expanded configuration shown in FIG. 43 . As a device having an outer diameter larger than the initial resting inner diameter of the sheath 700 is inserted through the sheath 700, the device can cause localized expansion of the sheath 700, expanding the sheath 700 at the partial score line location or split line location 716. The weakened portion 716 can extend longitudinally along any portion of the expandable sheath 700.

[0167] 44 and 45 show another embodiment of an expandable sheath 800 having an initial diameter in a resting configuration ( FIG. 44 ) and a larger expanded diameter in an expanded configuration ( FIG. 45 ). The sheath 800 can include a resilient outer cover 802, an inner layer 804, and an outer layer 806. The inner layer 804 can include first and second folded portions 808, 810. The folded portions 808, 810 can be arranged to fold away from each other in opposite directions around the circumference of the sheath 800. For example, the folded portion 808 can be folded to the right in the view of FIG. 44 , and the folded portion 810 can be folded to the left such that they do not overlap each other but share a common segment 812 that is part of both folded portions 808, 810. In contrast to the previous example, the outer layer 806 does not include an overlapping portion in this example, but rather has first and second underlying portions 814, 816 that respectively underlie the first and second folded portions 808, 810. The inner layer 804 can extend through the gaps between the ends of adjacent underlying portions 814, 816 (e.g., between the first and second ends of the discontinuous outer layer 806).

[0168] Each folded portion 808, 810 can include weakened portions 818, such as slits, score lines, and / or perforations. The weakened portions 818 can allow the expandable sheath 800 to easily expand without high radial forces. As the sheath 800 expands, segments 812 along the top of the folded portions 808, 810 of the inner layer 804 can be configured to split away from the rest of the folded portions 808, 810, and the first and second underlying portions 814, 816 can move away from each other to create an enlarged lumen within the inner layer 804. The weakened portions 818 can allow the segments 812 to easily split away from the inner layer 804 as the sheath 800 expands.

[0169] 46-47 illustrate another embodiment of an expandable sheath 900. The sheath 900 can include an inner layer 902 and a resilient cover 904 surrounding the inner layer 902. Although not shown, the sheath 900 can further include an intermediate layer disposed between the inner layer 902 and the resilient cover 904. If present, the intermediate layer can closely follow the contours of the inner layer 902.

[0170] The inner layer 902 can be molded to include one or more folds 906 arranged to form a generally horseshoe-shaped lumen 908 that extends longitudinally through the sheath 900 along the inner surface of the inner layer 902. The folds 906 can be arranged to form an area 910 that is aligned with the lumen 908 and located radially inward from the resilient covering 904. In some embodiments, the area 910 can include one or more voids (e.g., smaller lumens or openings extending through the area 910). In some embodiments, the area 910 can be filled with material (e.g., HDPE) reflowed from an intermediate layer during fabrication of the sheath. In some embodiments, the area 910 can be filled with material reflowed from the resilient covering 904 during the sheath manufacturing process.

[0171] The inner layer 902 can include one or more weakened portions 912, such as score lines, perforations, or slits. The weakened portions 912 can be configured to split, separate, or widen in the presence of a radial force as the sheath expands from its initial, resting configuration ( FIG. 46 ) to an expanded configuration ( FIG. 47 ). As the sheath 900 expands, material from the areas 910 can cover gaps 914 formed in the weakened portions 912, thereby keeping the lumen 908 substantially sealed.

[0172] FIG. 48 illustrates another embodiment of an expandable sheath 1000 having an inner layer 1002 and a discontinuous outer layer 1004. The sheath 1000 is similar to the sheath 800 of FIG. 44, except that the sheath 1000 is shown without an elastic outer covering and further, the inner layer 1002 is continuous without weakened portions at the folds 1006. As shown in FIG. 48, the inner layer 1002 can be configured with one or more folds 1006 (e.g., two folds disposed on the outer surface of the outer layer 1004), with a portion 1008 of the outer layer 1004 extending between the folds 1006 and an outer surface 1010 of the inner layer 1002 that underlies the folds 1006.

[0173] Figure 49 illustrates another embodiment of an expandable sheath 1100 having an inner layer 1102 and an outer layer 1104. The sheath 1100 is similar to the sheath 100 illustrated in Figure 39 in that the inner layer 1102 can be continuous with the folded portion 1106 and the outer layer 1104 can be discontinuous with an overlapping portion 1108 that overlaps at least a portion of the folded portion 1106 and an underlying portion 1110 that is underlying at least a portion of the folded portion 1106. Thus, the underlying portion 1110 can be disposed between the outer surface 1112 of the lumen-forming portion of the inner layer 1102 and the folded portion 1106.

[0174] The inner layer 1002, 1102 of the sheaths 1000, 1100 of Figures 48-49, respectively, can be optimized to operate slightly differently from the inner layer of the sheaths described above. For example, a different material can be used for the inner liner to enhance seam durability and softness (although such materials can also be used in the other expandable sheath embodiments described above). For example, materials such as woven or braided filaments can be used. Such fabrics, filaments, or threads can be composed of, for example, PTFE, PET, PEEK, and / or nylon threads or filaments. These materials can advantageously provide a soft, flexible layer that can be easily formed into a desired shape or fold. Furthermore, such materials can withstand high temperatures as well as have high tensile strength and tear resistance. Nevertheless, these materials can also be resilient and provide a soft distal edge to minimize kinking and reduce traumatic insertion into a patient's vessel.

[0175] In yet another embodiment, the outer jacket disclosed herein can comprise at least two polymer layers. In yet another embodiment, the outer jacket disclosed herein can comprise at least one intermediate reinforcing layer / member disposed between the first and second polymer layers of the outer jacket. In yet another embodiment, the at least one intermediate reinforcing layer / member is a polymer layer. FIGS. 62-65 illustrate an expandable outer jacket including a longitudinally extending reinforcing member 145. The outer jacket 140 can be used with any of the expandable sheaths described herein. The reinforcing member 145 prevents axial bunching of the outer jacket 140 during insertion into the patient's vasculature without sacrificing the low radial expansion force of the outer jacket 140. The reinforcing member 145 is typically constructed of a stiffer material than the main body of the outer jacket 140 (e.g., Pebax, polyurethane, nylon, flat wire). The resistance of the reinforcing members 145 to elongation and / or compression prevents bunching / crumpling of the outer jacket 140 during insertion, while still allowing the outer jacket 140 to expand radially.

[0176] FIG. 62 is an elevation view of outer jacket 140 showing the tapered segment adjacent the flared end at the proximal end of the sheath. FIG. 63 is a cross-sectional view of outer jacket 140 taken along section AA in FIG. 62. As mentioned above, the tapered portion is referred to as a strain relief section, and the tapered segment and flared proximal end facilitate the transition between the smaller diameter portion of sheath 100 and housing 101. The length of the proximal end (LI) can range from 1.600 inches to 2.400 inches. In some embodiments, the length of the proximal end is approximately 2.000 inches. The length of the tapered segment (L2) can range from 2.000 inches to 3.000 inches. In some embodiments, the length of the tapered segment (L2) is approximately 2.500 inches. The overall length (L3) of outer jacket 140 / sheath 100 can range from 17.600 inches to 26.400 inches. In some embodiments, the overall length (L3) of the outer jacket 140 / sheath 100 is about 22,000 inches.

[0177] As shown in FIG. 62 , the diameter of the outer jacket 140 at the proximal end is larger than the diameter of the outer jacket 140 at the distal end. This allows the outer jacket 140 to slide over the inner and outer layers 108, 110 without having to be expanded. For example, the diameter of the outer jacket 140 at the proximal end can range from 0.264 inches to 0.396 inches. In some embodiments, the diameter of the outer jacket 140 at the proximal end is approximately 0.330 inches. The diameter of the outer jacket 140 at the distal end can range from 0.176 inches to 0.264 inches. In some embodiments, the diameter of the outer jacket at the distal end is approximately 0.220 inches.

[0178] The wall thickness of the outer jacket 140 can range from 0.0040 inches to 0.0066 inches. In some embodiments, the thickness of the outer jacket 140 is approximately 0.0055 inches. The wall thickness of the outer jacket 140 can remain constant along the entire length of the outer jacket 140. However, in some embodiments, the thickness of the outer jacket 140 at the proximal end (T1) is greater than the thickness of the outer jacket 140 at the distal end (T2).

[0179] In yet another embodiment, the outer jacket 140 can include two or more reinforcing members 145. In such an embodiment, the two or more reinforcing members 145 can be positioned as individual strips circumferentially between the inner and outer polymeric layers at a predetermined distance from each other. FIG. 64 is a cross-sectional view of the outer jacket 140 taken along section line BB in FIG. 62. As shown in FIG. 64, the outer jacket 140 includes three reinforcing members 145. In some embodiments, the outer jacket 140 includes only one reinforcing member 145 (FIG. 66). In other embodiments, the outer jacket includes up to eight reinforcing members 145. When two or more reinforcing members 145 are used, the reinforcing members are equally spaced around the circumference of the outer jacket 140. As further shown in FIG. 64, the reinforcing members 145 can have a rectilinear shape (e.g., rectangular) in cross section. However, other regular or irregular shapes are contemplated.

[0180] In yet another embodiment, the reinforcing members 145 have a finite width that is less than the circumference of the outer jacket 140. The total combined width (w) of the reinforcing members 145 can range from 10% to 50% of the circumference of the outer jacket 140. In yet another embodiment, the total combined width of the strips is about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, or about 50% of the circumference of the elongated tube.

[0181] FIG. 65 includes a partial view of the outer jacket 140 of FIG. 64. As shown in FIG. 65, the circumferential width of the reinforcing member 145 can range from 0.025 inches to 0.100 inches. In some embodiments, the distal end of the outer jacket 140 has a diameter of 0.200 inches, and the circumferential width of the reinforcing member 145 can range from 0.025 inches to 0.100 inches. In some exemplary, non-limiting embodiments, the diameter of the outer jacket at the distal end is about 0.200", and the width of the reinforcing member is about 0.03", about 0.035", about 0.04", about 0.045", about 0.05", about 0.055", about 0.06", about 0.065", about 0.07", about 0.075", about 0.08", about 0.085", about 0.09", and about 0.095", about 0.10", about 0.105", about Between about 0.025" and about 0.100", with exemplary values ​​of 0.110", about 0.115", about 0.120", about 0.125", about 0.130", about 0.135", about 0.140", and about 0.145". The widths shown above are exemplary and it is understood that if the distal outer diameter of the outer jacket has a size different from 0.200", the reinforcing member width can be adjusted in the same or different ratios.

[0182] In yet another embodiment, the reinforcing member has a finite width that is less than the circumference of the elongate tube. In such an embodiment, at least one reinforcing member 145 can be inserted as a strip between the first and second polymer layers of the outer jacket 140. In some exemplary, non-limiting embodiments, if the outer jacket has a distal outer diameter of about 0.200", the strip of reinforcing member 145 has a width between about 5% and about 50% of the circumference of the outer jacket. In yet another embodiment, the total combined width of the strips is about 5%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, or about 50% of the circumference of the outer jacket. The widths set forth above are exemplary, and it is understood that if the distal outer diameter of the elongate sheath has a size different from 0.200", the reinforcing member 145 width can be adjusted in the same or different proportions.

[0183] In yet another embodiment, the outer jacket 140 can include two or more reinforcing members 145. In such embodiments, the two or more reinforcing members 145 can be disposed as individual strips circumferentially spaced a predetermined distance from one another between the first and second polymer layers. In embodiments in which two or more reinforcing members 145 are disposed between the first and second polymer layers of an elongated tube, the combined total width of all strips is about 5% to about 50% of the circumference of the outer jacket 140. In yet another embodiment, the combined total width of the reinforcing members 145 is about 5%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, or about 50% of the circumference of the outer jacket.

[0184] In embodiments in which reinforcing member 145 is present as one or more strips circumferentially disposed along the length of outer jacket 140, the width of reinforcing member 145 can be the same along the length or can vary along the length. In embodiments in which reinforcing member 145 width varies along the length of outer jacket 140, such reinforcing member 145 can have any of the width values ​​described above.

[0185] In yet other embodiments, the at least one reinforcing member 145 is configured to provide axial reinforcement to the outer jacket 140 and, consequently, to the sheath in which the outer jacket 140 may be used. In such exemplary embodiments, the at least one reinforcing member 145 may be disposed along the length of the outer jacket 140 or along a portion of the length of the outer jacket 140. In some embodiments, the portion of the length of the outer jacket 140 on which at least the reinforcing member 145 is disposed is disposed at the distal and / or proximal end of the outer jacket 140. In still other embodiments, the reinforcing member 145 may be disposed anywhere along the length of the outer jacket 140.

[0186] 64 , outer jacket 140 includes a two-layer structure, inner layer 146 and outer layer 147, where the outer layer provides abrasion resistance (e.g., between the sheath and calcified lesions) and good resistance to hydrophilic coating processes, and the inner layer is a more lubricious material (e.g., to prevent the outer jacket from sticking to the outer layer of the sheath during expansion) and provides better pressure or expansion resistance and hemostasis. In some embodiments, inner layer 146 (first polymer layer) forms the inner surface of outer jacket 140, outer layer 147 (second polymer layer) forms the outer surface of the outer jacket, and reinforcing member 145 is disposed between the outer surfaces of inner layer 146 and outer layer 147.

[0187] In some embodiments, inner layer 146 is constructed of Pebax or polyurethane having a Shore D durometer of 25D to 35D. In some embodiments, inner layer 146 includes PTFE powder, optional inorganic fillers, and optional adhesion-reducing additives to reduce friction when sheath outer layer 110 expands by sliding against outer jacket 140. In some embodiments, outer layer 147 of outer jacket 140 is constructed of polyurethane or polyurethane / styrene block copolymer (SBC) having a Shore A durometer of less than about 60, such as Neusoft 597-50A having a Shore A durometer of about 55A. In one embodiment, inner layer 146 is constructed of polyether block amide, such as Pebax, having a Shore D durometer of less than about 35.

[0188] In yet another exemplary, non-limiting embodiment, the inner layer 146 forms the inner surface of the outer jacket and is comprised of a first compound composition comprising: greater than 0% and less than 100% by weight, based on the total weight of the first compound composition, of a polymer including a polyether block amide, a polyurethane, or a combination thereof; less than about 65% by weight, based on the total weight of the first compound composition, of an inorganic filler; and up to about 20% by weight, based on the total weight of the first compound composition, of a solid lubricant filler.

[0189] Any of the inorganic fillers and solid lubricant fillers disclosed above can be present in any amount as disclosed. For example, the inorganic filler can be bismuth oxychloride, barium sulfate, bismuth subcarbonate, calcium carbonate, aluminum trihydrate, barite, kaolin clay, limestone, or any combination thereof. In yet another embodiment, the inorganic filler can be present in an amount of at least 10 wt. %. In yet another embodiment, the inorganic filler can be present in an amount of less than about 50 wt. % based on the total weight of the first compound composition.

[0190] In yet another embodiment, the solid lubricant filler can consist of a PTFE filler.

[0191] The first compound can also include any of the additives disclosed above. For example, the compound can include at least one stickiness-reducing compound in an amount of about 1% to about 20% by weight.

[0192] In yet another exemplary embodiment, the polymer present in the first compound can have a Shore D hardness of from about 20D to about 35D, with exemplary values ​​of about 22D, about 25D, about 27D, about 30D, and about 32D.

[0193] In yet another embodiment, the durometer of the polymer in the inner layer 146 (first polymer layer) composition at the proximal end of the outer jacket 140 can be different from the durometer of the polymer in the inner layer 146 (first polymer layer) composition at the distal end of the outer jacket 140.

[0194] In yet another embodiment, the polymer in the first compound can include PEBAX®, while in other embodiments, the polymer in the first compound can include polyurethane. In yet another embodiment, the first compound can include polyamide.

[0195] In yet another embodiment, the outer layer 147 (second polymer layer) can be comprised of any of the disclosed polymers. In some embodiments, the outer layer 147 can be comprised of a second compound composition comprising from greater than 0% to 100% by weight of a second polymer comprising a polyether block amide, a polyurethane, or a composition thereof. In yet another embodiment, the outer layer 147 can be comprised of a polyamide. In still other embodiments, the second compound can also be comprised of any of the fillers or additives disclosed above. In some embodiments, the second compound does not include a solid lubricant filler as disclosed herein. Meanwhile, in yet another embodiment, the second compound can include a tack-reducing additive as described in this disclosure. In some embodiments, the second polymer can be a polyurethane. In yet another embodiment, the polyurethane is a thermoplastic polyurethane. Meanwhile, in yet another embodiment, the second polymer can be a blend including a polyurethane, including a styrene block copolymer. In yet another embodiment, the blend can further include additional polymers and copolymers. For example, an ether-based polymer can be present in the blend. In some exemplary, non-limiting embodiments, the second polymer can be selected from commercially available polymers sold under the Neusoft™ trade name. In yet another embodiment, the second polymer can have a Shore A durometer of about 20 A to about 75 A, including exemplary values ​​of about 25 A, about 30 A, about 35 A, about 40 A, about 45 A, about 50 A, about 55 A, about 60 A, about 65 A, and about 70 A. In yet another embodiment, the second polymer can have a Shore A durometer of less than 60 A. In some exemplary embodiments, the second polymer can be Neusoft™ 597-50A.

[0196] As shown in FIG. 65, the inner layer 146 is thicker than the outer layer 147. Generally, the thickness of the inner layer ranges from 0.0010 inches to 0.0025 inches. In some embodiments, the inner layer has a thickness of approximately 0.00154 inches. The thickness of the outer layer ranges from 0.002 inches to 0.004 inches. In some embodiments, the outer layer has a thickness of approximately 0.003 inches.

[0197] In yet another embodiment, the thickness of the inner layer 146 (first polymer layer) is about 1.1 mils, about 1.2 mils, about 1.3 mils, about 1.4 mils, about 1.5 mils, about 1.6 mils, about 1.7 mils, about 1.8 mils, about 1.9 mils, about 2.0 mils, 2.1 mils, about 2.2 mils, about 2.3 mils, about 2.4 mils, about 2.5 mils, about 2.6 mils, about 2.7 mils, about 2.8 mils, about 2.9 mils. , about 3.0 mils, about 3.1 mils, about 3.2 mils, about 3.3 mils, about 3.4 mils, about 3.5 mils, about 3.6 mils, about 3.7 mils, about 3.8 mils, about 3.9 mils, about 4.1 mils, about 4.2 mils, about 4.3 mils, about 4.4 mils, about 4.5 mils, about 4.6 mils, about 4.7 mils, about 4.8 mils, and about 4.9 mils.

[0198] In yet another embodiment, the thickness of the outer layer 147 (second polymer layer) is about 1.1 mils, about 1.2 mils, about 1.3 mils, about 1.4 mils, about 1.5 mils, about 1.6 mils, about 1.7 mils, about 1.8 mils, about 1.9 mils, about 2.0 mils, 2.1 mils, about 2.2 mils, about 2.3 mils, about 2.4 mils, about 2.5 mils, about 2.6 mils, about 2.7 mils, about 2.8 mils, about 2.9 mils, about 3.0 mils, about 3.1 mils, about 3.2 mils, about 3.3 mils, From about 1 mil to about 6 mils, including exemplary values ​​of about 3.4 mils, about 3.5 mils, about 3.6 mils, about 3.7 mils, about 3.8 mils, about 3.9 mils, about 4.1 mils, about 4.2 mils, about 4.3 mils, about 4.4 mils, about 4.5 mils, about 4.6 mils, about 4.7 mils, about 4.8 mils, about 4.9 mils, about 5.1 mils, about 5.2 mils, about 5.3 mils, about 5.4 mils, about 5.5 mils, about 5.6 mils, about 5.7 mils, about 5.8 mils, and about 5.9 mils.

[0199] In yet another embodiment, the thickness of the reinforcing member 145 is about 1.1 mils, about 1.2 mils, about 1.3 mils, about 1.4 mils, about 1.5 mils, about 1.6 mils, about 1.7 mils, about 1.8 mils, about 1.9 mils, about 2.0 mils, 2.1 mils, about 2.2 mils, about 2.3 mils, about 2.4 mils, about 2.5 mils, about 2.6 mils, about 2.7 mils, about 2.8 mils, about 2.9 mils, about 3.0 mils, about 3.1 mils, about 3.2 mils, about 3.3 mils, about 3.4 mils, about 3.5 mils, about 3.6 mils, about 3.7 mils, about 3.8 mils, about 3.9 mils, about 4.0 mils, about 4.1 mils, about 4.2 mils, about 4.3 mils, about 4.4 mils, about 4.5 mils, about 4.6 mils, about 4.7 mils, about 4.8 mils, about 4.9 mils, about 5.0 mils, about 5.1 mils, about 5.2 mils, about 5.3 mils, about 5.4 mils, about 5.5 mils, about 5.6 mils, about 5.7 mils, about 5.8 mils, about 5.9 mils, about 6.0 mils, about 6.1 mils, about 6.2 mils, about 6.3 mils, about 6.4 mils, about 6.5 mil mils, about 3.6 mils, about 3.7 mils, about 3.8 mils, about 3.9 mils, about 4.1 mils, about 4.2 mils, about 4.3 mils, about 4.4 mils, about 4.5 mils, about 4.6 mils, about 4.7 mils, about 4.8 mils, about 4.9 mils, about 5.1 mils, about 5.2 mils, about 5.3 mils, about 5.4 mils, about 5.5 mils, about 5.6 mils, about 5.7 mils, about 5.8 mils, and about 5.9 mils, and can be anywhere between about 1 mil and about 6 mils.

[0200] As shown in FIGS. 64 and 65 , the reinforcing member 145 is at least partially embedded within the inner layer 146. In some embodiments, the thickness of the reinforcing member 145 is less than the thickness of the inner layer 146. For example, as shown in FIG. 65 , the reinforcing member 145 has a thickness ranging from 0.0005 inches to 0.0015 inches. In some embodiments, the reinforcing member 145 has a thickness of approximately 0.001 inches. In an exemplary configuration, the reinforcing member 145 has a thickness of 0.001 inches and the inner layer has a thickness of 0.00154 inches. In another embodiment, not shown, the reinforcing member 145 has a thickness corresponding to the thickness of the inner layer 146. In yet another embodiment, the reinforcing member 145 has a thickness greater than the thickness of the inner layer 146. In some embodiments, the inner layer 146 and the reinforcing member 145 are co-extruded. Similarly, inner layer 146, reinforcing member 145, and outer layer 147 are co-extruded with reinforcing member 145 disposed between inner layer 146 and outer layer 147. In other embodiments, inner layer 146 is disposed over reinforcing member 145, and the two components are bonded or fused together by at least one of heat or compression.

[0201] As noted above, the reinforcing member 145 is constructed from a material that is stiffer than the main body portion (inner layer 146, outer layer 147) of the outer jacket 140 and has a low coefficient of friction (e.g., high-density polyethylene). In some embodiments, the reinforcing member 145 is constructed from a polymer that is compatible with the inner and outer layers, including, for example, high durometer Pebax or polyurethane. The reinforcing member 145 can also be constructed from a material having a Shore D durometer ranging from 45D to 76D.

[0202] In some embodiments, the reinforcing member is constructed from a material excluding PTFE powder or inorganic fillers, thereby providing axial compressive / tensile stiffness (from the high durometer material) and friction against axial bundling (without the PTFE powder).

[0203] In a particular embodiment, outer layer 147 is constructed from NEUSOFT 597-50, inner layer 146 is constructed from Pebax 25D containing PTFE and BaSO4, and reinforcing member 145 is constructed from Pebax 35D containing PTFE and BaSO4. In a further embodiment, outer layer 147 is constructed from NEUSOFT 597-50, inner layer 146 is constructed from Pebax 25D containing PTFE and BaSO4, and reinforcing member 145 is constructed from Pebax 4033. In another embodiment, outer layer 147 is constructed from NEUSOFT 597-50, inner layer 146 is constructed from Pebax 25D containing PTFE and BaSO4, and reinforcing member 145 is constructed from Pebax 5533.

[0204] In some embodiments, reinforcing member 145 can be comprised of any of the polymers disclosed herein. In some embodiments, reinforcing member 145 can be comprised of the first compound disclosed above. In still other embodiments, reinforcing member 145 can be comprised of the second compound disclosed above. In yet other embodiments, reinforcing member 145 can be comprised of the first compound. In still other embodiments, reinforcing member 145 can be comprised of any polymer known in the art and suitable for the desired application. In some embodiments, reinforcing member 145 can be comprised of a polyether block amide, a polyurethane, or a combination thereof. In yet other embodiments, reinforcing member 145 is a polyether block amide, such as PEBAX®. In yet other embodiments, reinforcing member 145 is a polyurethane. In such exemplary embodiments, reinforcing member 145 does not include a solid lubricant filler, such as PTFE. In still other embodiments, reinforcing member 145 does not include an inorganic filler. In yet another embodiment, the reinforcing member 145 can be constructed of a polymer including PEBAX® or polyurethane having a Shore D durometer between about 45D and about 90D, including exemplary values ​​of about 50D, about 55D, about 60D, about 65D, about 70D, about 72D, about 75D, about 80D, and about 85D.

[0205] In yet another embodiment, the reinforcing member 145 can be composed of a polyolefin. In yet another embodiment, the reinforcing member 145 can be composed of polyethylene, polypropylene, graft-modified polyethylene, or polypropylene. In yet another embodiment, the reinforcing member 145 can be composed of grafted low-density polyethylene (LDPE), grafted medium-density polyethylene, grafted ultra-low-density polyethylene (ULDPE), grafted high-density polyethylene (HDPE), grafted heterogeneously branched linear low-density polyethylene (LLDPE), grafted homogeneously branched linear ethylene polymer, substantially linear ethylene polymer, grafted polypropylene, or ethylene vinyl acetate (EVA), or any combination thereof. In such exemplary embodiments, maleic anhydride or acrylic acid can be used to graft the disclosed polymers. In yet another embodiment, at least one reinforcing member 145 can be composed of maleic anhydride or acrylic acid-grafted low-density polyethylene. In yet another embodiment, at least the reinforcing member 145 can be composed of polypropylene grafted with maleic anhydride or acrylic acid. In yet another embodiment, the reinforcing member 145 can be composed of ethylene vinyl acetate grafted with maleic anhydride or acrylic acid. In yet another embodiment, the reinforcing member 145 can be composed of a maleic anhydride grafted polyolefin sold under the trademark OREVAC®.

[0206] In some embodiments, the reinforcing member 145 can bond the inner and outer layers 146, 147 together and help bond the elongated tube as a whole to the inner sheath member. By way of example, the reinforcing member 145 is constructed from a thermally bondable strip of tie-layer material. The tie-layer material is comprised of a polyolefin backbone, including, for example, LDPE, LLDPE, EVA, HDPE, PP, or a polyolefin copolymer with grafted functional groups, such as maleic anhydride or acrylic acid, as described below. The tie layer is thermally bonded to the inner layer 146 of polyolefin-like HDPE and extruded as a strip within the polyamide, copolyamide, or polyurethane layer of the outer jacket 140. Potential tie-layer materials for thermally bondable tie layers include OREVAC® grafted polyolefins available from Arkema. In some examples, maleic anhydride-grafted LLDPE (linear low-density polyethylene) Orevac 18300M is used as a strip. In some embodiments, the thermally bondable strip is fused to the inner layer 146 using heat and / or compression.

[0207] In yet another aspect, the outer jacket 140 disclosed herein, including the reinforcing member, can exhibit an expansion force of less than about 50 N, less than about 49 N, less than about 48 N, less than about 47 N, less than about 46 N, less than about 45 N, less than about 44 N, less than about 43 N, less than about 42 N, less than about 41 N, or less than about 40 N.

[0208] In yet another aspect, the outer jacket disclosed herein, including the reinforcing member, can exhibit a burst pressure of greater than about 8 psi, greater than about 8.5 psi, greater than about 9 psi, greater than about 9.5 psi, greater than about 10 psi, greater than about 10.5 psi, greater than about 11 psi, greater than about 11.5 psi, greater than about 12 psi, greater than about 12.5 psi, greater than about 13 psi, greater than about 13.5 psi, greater than about 14 psi, greater than about 14.5 psi, or greater than about 15 psi.

[0209] Various methods can be used to manufacture the sheaths discussed above and below throughout this disclosure. For example, a method for making the sheaths shown in FIGS. 2A-2D can include providing a mandrel and attaching an inner layer to the mandrel, such as by spray coating or dip coating the mandrel. A middle layer, such as a mesh structure, can then be attached to the inner layer. An outer layer can be attached over the middle layer, such as by a second spray coating or dip coating step. The method can also include etching or surface treating at least a portion of the inner layer. The method can also include providing one or more notches and / or cuts in the inner and / or outer layers. The cuts and / or notches can be provided, for example, by laser cutting or etching one or more layers.

[0210] In some embodiments of methods for making sheaths, such as the sheaths shown in Figures 2A-2D, the layers can be pre-formed and placed on a mandrel and then fused or heat-bonded together. For example, in one method, an inner layer is attached to a mandrel. A middle layer can be attached to the outer surface of the inner layer. An outer layer can be attached to the outer surface of the middle layer. Heat shrink tubing can be applied and the assembly can be heated to heat-bond and compress the inner, middle, and / or outer layers together under the heat shrink tubing.

[0211] FIG. 30 shows a block diagram of one method for manufacturing a sheath for use with a delivery device in minimally invasive surgery. One or more mandrels can be provided (step 300). The mandrel can be coated with an external coating, such as a Teflon coating, and the diameter of the mandrel can be predetermined based on the desired size of the resulting sheath. A liner, which will become the inner polymer layer of the sheath, such as a PTFE liner or a high-density polyethylene liner, can be attached to the mandrel (step 302). The liner can be etched and / or surface treated using conventional etching and surface treatment methods before being attached to the mandrel. FIG. 32A shows a cross-sectional view of the sheath at steps 300 and 302 of FIG. 30. The coated mandrel 96 is inserted within the lumen 72 of the inner polymer layer 68. The circumference of the inner polymer layer 68 is greater than the circumference of the mandrel 96, allowing the excess inner polymer layer 68 to gather above the mandrel 96.

[0212] The layer of material that will become the outer polymeric tubular layer, such as a layer comprising polyurethane or polyolefin, may be cut or notched through all, substantially all, or a portion of its thickness (step 304). Such cuts or notches may extend longitudinally along the length of the layer, and may extend along substantially the entire length of the outer polymeric tubular layer. In alternative embodiments, the cuts or notches may be provided along only a portion of the outer polymeric tubular layer. For example, the outer polymeric tubular layer may be cut starting at the distal end of the outer polymeric tubular layer, with the cut terminating before the proximal end of the outer polymeric tubular layer. In one embodiment, the cuts may terminate at a transition where the outer diameter of the outer polymeric tubular layer increases or decreases. In one particular embodiment, the cuts or notches may extend longitudinally along approximately 75% of the length of the sheath.

[0213] The cut or notched outer polymeric tubular layer can be applied, positioned, glued, attached, heat fused or bonded, dip coated, and / or otherwise bonded to the etched inner liner (step 306). Figure 32B shows a cross-sectional view of the sheath at step 306 of Figure 30, where the outer polymeric tubular layer 70 has been attached to the inner polymeric layer 68 such that a portion of the inner polymeric layer 68 extends through the cut formed between the first and second portions 78, 80 of the outer polymeric tubular layer 70.

[0214] In alternative embodiments, the outer polymeric tubular layer can be notched or cut after being attached to the inner liner / mandrel assembly. The outer polymeric tubular layer can optionally be provided with additional layers, such as a hydrophilic coating and / or a polyurethane dip coating. After such an outer polymeric tubular layer is attached to the inner liner / mandrel arrangement, a portion of the inner liner can protrude through the notch in the outer polymeric tubular layer. For example, a splitting tool can be used to fold the protruding portion of the inner liner onto the outer surface of the outer polymeric tubular layer (step 308). In some embodiments, the protruding portion of the inner liner is folded along the entire length of the resulting sheath, while in other embodiments, the protruding portion of the inner liner is only present along a portion of the length of the sheath or is only folded along a portion of the length of the resulting sheath. FIG. 32C shows a cross-sectional view of the sheath at step 308 of FIG. 30. Using a split tool 98, the excess portion of the inner polymeric layer 68 is folded over a portion of the outer surface 83 of the outer polymeric tubular layer 70. Figure 32D shows a cross-sectional view of the sheath after completion of step 308 of Figure 30. The split tool 98 has been removed, completing the folding of the excess portion of the inner polymeric layer 68. Figure 32E shows a cross-sectional view of an outer covering, such as an outer polymeric covering 99, that may be attached to overlap a portion of the folded portion of the inner polymeric layer 68. The outer polymeric covering 99 contacts at least a portion of the outer surface 83 of the outer polymeric tubular layer 70.

[0215] A soft, atraumatic tip can be provided at the distal end of the resulting sheath (step 310). Additional outer layers can be applied, if desired. A layer of heat shrink tubing, such as fluorinated ethylene propylene (FEP) heat shrink tubing, can then be placed over the entire assembly (step 312). An appropriate amount of heat is applied, thereby shrinking the heat shrink tubing and compressing the sheath layers together, thereby allowing the sheath components to be thermally bonded or fused together, if desired. Once the sheath components are bonded together, the heat shrink tubing can be removed (step 314). Finally, the proximal end of the sheath can be glued or otherwise attached to the housing of the catheter assembly, and the sheath can be removed from the mandrel (step 316).

[0216] FIG. 31 shows a block diagram of an alternative embodiment of a method for fabricating a sheath. An inner liner, such as an etched PTFE tube, can be attached to a tapered mandrel, such as a 16 Fr tapered mandrel, and trimmed to the appropriate length (step 200). A second mandrel, such as a 0.070-inch diameter mandrel, can be inserted into the lumen of the inner liner so that the mandrels are disposed side-by-side within the inner liner (step 202). FIG. 32F shows a cross-sectional view of the sheath at steps 200 and 202 of FIG. 31. An inner liner or inner polymer layer 68 is applied over the first tapered mandrel 96. A second mandrel 97 is inserted into the lumen 72 of the inner polymer layer 68, created by the excess portion of the inner polymer layer 68, as described.

[0217] A notched or cut outer polymeric tubular layer, such as a high-density polyethylene tube with a longitudinal notch or cut, can be slid over the tapered mandrel and a portion of the inner liner, starting at the distal end of the tapered mandrel (step 204). The second mandrel can then be removed (step 206). FIG. 32G shows a perspective view of the sheath at steps 204 and 206 of FIG. 31. An outer polymeric tubular layer 70 with a longitudinal cut is applied over the tapered mandrel 96 and the inner polymeric layer 68. The outer tubular layer fits over the portion of the inner polymeric layer around the tapered mandrel 96, and the portion of the inner polymeric layer 68 around the second mandrel 97 extends through the longitudinal cut in the outer polymeric tubular layer 70.

[0218] A split tool can be inserted into the portion of the lumen of the inner liner previously occupied by the second mandrel (step 208). The split tool can then be used to form folds and / or pleats in the excess portion of the inner liner, which now extends through the longitudinal cut in the outer polymeric tubular layer (step 210). A radiopaque marker band can optionally be applied at the distal end of the sheath (step 212). Heat shrink tubing, such as EEP heat shrink tubing, can be applied over the entire sheath, and heat can be applied to compress the sheath components and bond or fuse them together (step 214). The split tool, heat shrink tubing, and second mandrel can then be removed (step 216). The sheath can then be utilized with a delivery device, such as by bonding the proximal end of the sheath to the polycarbonate housing of the delivery device or to a catheter assembly (step 218).

[0219] Figure 32H shows an elevational view of the sheath at step 218 of Figure 31. Once fabricated by the methods and processes described, the sheath 66 can be attached or joined to the housing 101, such as by joining the proximal end of the sheath 66 to the polycarbonate housing 101.

[0220] In another embodiment, the disclosed expandable sheath can be fabricated using a reflowed mandrel process. A mandrel can be provided, with the size of the mandrel defining the inner diameter of the sheath lumen in the resting configuration. A tube of material, such as PTFE tubing, that will become the inner liner of the sheath can be given an inner diameter larger than that of the mandrel (e.g., a 9 mm PTFE tube can be fitted onto a 6 mm mandrel). The PTFE tube can be prepared into its final folded configuration by fitting it onto the mandrel and folding the excess material of the PTFE tube over one or both sides. An HDPE tube, which serves as the outer layer, can then be placed over the PTFE liner. This two-layer assembly can then be heat-fused together. For example, a reflow process can be performed, in which the assembly is heated to a sufficiently high temperature to at least partially melt the inner and / or outer layers, which then fuse together as the heat is removed and the assembly cools.

[0221] The resilient covering can be placed over at least a portion of the fused layer (e.g., over the proximal portion of the sheath) and held in place using a thermal process. In some embodiments, the same thermal process can bond the sheath layers and the resilient covering. In other embodiments, a first thermal process can be used to fuse the sheath layers together, and a second thermal process can be used to secure the resilient covering to the sheath. In some embodiments, the resilient covering can be heat shrink tubing that is applied over the expandable sheath and heated to a temperature high enough to shrink the tubing around the sheath. Then, in some embodiments, a distal soft tip can be attached to the shaft of the expandable sheath.

[0222] In some embodiments, the outer layer can be coextruded with an adhesive layer, such as a layer formed of Tecoflex™, whereby Tecoflex™ is disposed on the inner surface of the outer layer—thus disposing Tecoflex™ between the inner and outer layers within the finished sheath. In these embodiments, the HDPE tube can be coated with Tecoflex™ on its inner surface. The HDPE tube can be slit along its length, opened, flattened, and then cut, in some embodiments, using a template. For example, for certain applications, a template can be used to cut and remove portions of the outer layer. The cut HDPE can then be placed over the inner layer on a mandrel. In some embodiments, only a portion of the outer layer has Tecoflex™ adhesive. In these embodiments, the Tecoflex™-free section is only partially fused to the inner layer. In some embodiments, the entire inner surface of the outer layer has Tecoflex™, and the inner surface of the outer layer can be placed so that it contacts the inner layer on the mandrel. To position the inner and outer layers, as shown in the sheath of Figure 39, the fold of the inner layer can be lifted and the edges of the outer layer can be tucked under the folds.

[0223] The sheaths of the present disclosure can be used in a variety of methods for introducing a prosthetic device into a patient's vasculature. One such method includes placing an expandable sheath within the patient's blood vessel, passing the device through an introducer sheath, expanding the portion of the sheath surrounding the device to conform to the profile of the device, and automatically retracting the expanded portion of the sheath to its original size after the device has passed through the expanded portion. In some methods, the expandable sheath can be sutured to the patient's skin at the insertion site, so that once the sheath is inserted an appropriate distance into the patient's vasculature, it will not move as the implantable device begins to pass through it.

[0224] The disclosed embodiments of the expandable sheath can be used with other delivery and minimally invasive surgical components, such as introducers and loaders. In one embodiment, the expandable sheath can be flushed to purge any air from within the sheath, for example, using a flush port 103 (FIG. 35). An introducer can be inserted into the expandable sheath, and the introducer / sheath combination can be inserted completely into the vasculature over a guide device, such as a 0.35-inch guidewire. Preferably, the seam formed by the intersection of the folded portion of the inner layer and the overlapping portion of the outer layer can be oriented downward (rearward). Once the sheath and introducer are fully inserted into the patient's vasculature, in some embodiments, the expandable sheath can be sutured in place at the insertion site. In this manner, the expandable sheath can be substantially prevented from migrating once positioned within the patient.

[0225] The introducer can then be removed, and a medical device, such as a transcatheter heart valve, can be inserted into the sheath, optionally using a loader. Such methods further include placing a crimped biological heart valve onto a distal end portion of an elongate delivery device and inserting the crimped valved elongate delivery device through an expandable sheath. The delivery device can then be advanced through the patient's vasculature to the treatment site where the valve will be implanted.

[0226] Typically, the medical device has an outer diameter larger than the diameter of the sheath in its original configuration. The medical device can be advanced toward the implantation site through the expandable sheath, which can locally expand to accommodate the medical device as the device passes. The radial force exerted by the medical device can be sufficient to locally expand the sheath to its expanded diameter (e.g., expanded configuration) only in the area where the medical device is currently located. Once the medical device has passed a specific location in the sheath, the sheath can at least partially contract to the smaller diameter of its original configuration. Thus, the expandable sheath can be expanded without the use of an inflatable balloon or other dilator. Once the medical device is implanted, the sheath and the sutures holding it in place can be removed. In some embodiments, it is preferable to remove the sheath without rotating it.

[0227] (Example) Example 1 1. An expandable sheath comprising: an inner tubular layer including a longitudinal slit and partially defining an inner lumen; an outer tubular layer surrounding the inner layer, the outer tubular layer including longitudinally extending folding flaps that overlie portions of an outer surface of the outer layer when the sheath is in an unexpanded state; and a tie layer disposed therebetween to bond the inner tubular layer to the outer tubular layer, wherein an outward radial force from a prosthetic device moving through the inner lumen widens the longitudinal slit and deploys the folding flaps, thereby enabling expansion of the sheath.

[0228] Example 2 The sheath of any embodiment herein, particularly embodiment 1, wherein the base of the folding flap is disposed radially outward from the longitudinal slit.

[0229] Example 3 10. The sheath of any embodiment herein, particularly embodiment 1 or 2, wherein the folding flaps include an overlying longitudinally extending portion separated from an underlying longitudinally extending portion by the sheath.

[0230] Example 4 The sheath of any embodiment herein, particularly embodiment 3, wherein the underlying portion contacts an outer surface of the outer tubular layer when the sheath is in the unexpanded state.

[0231] Example 5 The sheath of any of the embodiments herein, particularly embodiments 3-4, wherein the base of the folding flap extends the length of the outer tubular layer and the overlying and underlying portions extend between the base and the sheath.

[0232] Example 6 The sheath of any of the Examples herein, particularly Examples 3-5, wherein the overlying portion, the underlying portion, or both, has a thinner wall thickness than the remainder of the outer tubular layer.

[0233] Example 7 The sheath of any of the embodiments herein, particularly embodiments 1-6, wherein the longitudinally extending flaps extend around about 20% to about 40% of the circumference of the outer tubular layer when the sheath is in an unexpanded state.

[0234] Example 8 The sheath of any of the embodiments herein, particularly embodiments 1-7, wherein the outer tubular layer is formed from a material having a tensile modulus of elasticity of at least 300 MPa.

[0235] Example 9 The sheath of any example herein, particularly example 8, wherein the outer tubular layer is formed from a material having a tensile modulus of elasticity between 300 MPa and 2,000 MPa.

[0236] Example 10 The sheath of any of the embodiments herein, particularly embodiments 1-9, wherein the outer tubular layer is formed from a material having a tensile strength of at least 50 MPa.

[0237] Example 11 The sheath of any of the embodiments herein, particularly embodiments 1-10, wherein the outer tubular layer is formed from a shape memory material.

[0238] Example 12 The sheath of any embodiment herein, particularly embodiments 1-11, wherein the outer tubular layer is formed from a polyamide, a copolyamide, a polyether block amide (PEBAX), or a blend of polyamides.

[0239] Example 13 The sheath of any of the embodiments herein, particularly embodiments 1-12, wherein the outer tubular layer further comprises at least one additional, longitudinally extending fold flap overlying a portion of the outer surface of the outer layer when the sheath is in an unexpanded state.

[0240] Example 14 The sheath of any of the embodiments herein, particularly embodiments 1-13, wherein the outer surface of the outer tubular layer further comprises a hydrophilic coating.

[0241] Example 15 The sheath of any of the embodiments herein, particularly embodiments 1-14, wherein the longitudinal slit extends the entire length of the inner tubular layer.

[0242] Example 16 The sheath of any of the embodiments herein, particularly embodiments 1-15, wherein the inner tubular layer includes a first longitudinally extending end and a second longitudinally extending end, the first and second longitudinally extending ends defining the longitudinal slit.

[0243] Example 17 The sheath of any embodiment herein, particularly embodiments 1-16, wherein the inner tubular layer comprises a material having a static or dynamic coefficient of friction of less than 0.3.

[0244] Example 18 The sheath of any of the embodiments herein, particularly embodiments 1-17, wherein the inner tubular layer extends around at least 80% of the circumference of the lumen when the sheath is in an unexpanded state.

[0245] Example 19 The sheath of any of the embodiments herein, particularly embodiments 1-18, wherein the inner tubular layer is formed from a material having a tensile modulus of elasticity of at least 300 MPa.

[0246] Example 20 The sheath of any embodiment herein, particularly embodiments 1-19, wherein the inner tubular layer comprises HDPE or a fluoropolymer.

[0247] Example 21 The sheath of any embodiment herein, particularly embodiments 1-20, wherein the tie layer comprises a polyurethane or a functionalized polyolefin.

[0248] Example 22 The sheath of any embodiment herein, particularly embodiments 1-21, further comprising an elastomeric outer jacket surrounding the outer tubular layer.

[0249] Example 23 1. A method of delivering a prosthetic device to a treatment site, the method comprising: inserting an expandable sheath into a subject's vascular system; advancing the prosthetic device through a lumen of the expandable sheath, the prosthetic device exerting an outward radial force on an inner tubular layer of the expandable sheath; expanding a width of a longitudinal slit in the inner tubular layer via the outward radial force; deploying a longitudinally extending flap in an outer tubular layer via the outward radial force; reducing a width of the longitudinal slit in the inner tubular layer when the outward radial force is removed; and delivering the prosthetic device to the treatment site.

[0250] Example 24 The method of any embodiment herein, particularly embodiment 23, wherein the deployment of the flap occurs at a location radially outward from the longitudinal slit.

[0251] Example 25 The method of any of the embodiments herein, particularly embodiment 23 or 24, further comprising at least partially refolding the longitudinally extending flaps when the advancing prosthetic device ceases to exert the outward radial force.

[0252] Example 26 The method of any of the embodiments herein, particularly embodiments 23-25, wherein the longitudinally extending flaps are refolded by a shape memory bias of the outer tubular layer toward a folded state.

[0253] Example 27 The method of any of the embodiments herein, particularly embodiments 23-26, further comprising applying an inward radial force to an outer surface of the outer tubular layer to refold the longitudinally extending flaps.

[0254] Example 28 The method of any embodiment herein, particularly embodiment 27, wherein the inward radial force is exerted by an elastomeric outer jacket.

[0255] Example 29 The method of any of the embodiments herein, particularly embodiments 23-28, further comprising transmitting the outward radial force from the inner tubular layer through a tie layer to the outer tubular layer.

[0256] Example 30 The method of any of the embodiments herein, particularly embodiments 23-29, wherein the expansion of the longitudinal slit and the subsequent contraction of the longitudinal slit are propagated along the entire length of the expandable sheath.

[0257] Example 31 The method of any of the embodiments herein, particularly embodiments 23-30, wherein the step of unfolding the longitudinally extending flaps comprises circumferentially sliding the upper longitudinally extending portion against the lower longitudinally extending portion.

[0258] Example 32 The method of any of the embodiments herein, particularly embodiment 31, wherein the step of unfolding the longitudinally extending flap comprises sliding the underlying longitudinally extending portion circumferentially against the outer surface of the outer tubular layer.

[0259] Example 33 1. A method of manufacturing an expandable sheath, comprising the steps of: loading an inner layer onto a tapered mandrel; applying heat to the inner layer; flaring a proximal section of the inner layer under heat; attaching a tie layer to a main section of the inner layer; cutting longitudinal slits in the inner layer and the tie layer; loading the inner layer and tie layer with the longitudinal slits onto a (second) mandrel; loading an outer layer over the tie layer; folding the outer layer to create a longitudinally extending flap; heat setting the folded outer layer; and removing the expandable sheath from the mandrel.

[0260] Example 34 The method of any example herein, particularly example 33, wherein the tie layer is attached after the inner layer is pneumatically expanded.

[0261] Example 35 The method of any example herein, particularly Example 33 or 34, further comprising adhering the tie layer to the inner layer using heat shrink tubing; and removing the heat shrink tubing from the tie layer.

[0262] Example 36 The method of any example herein, particularly example 35, further comprising removing the heat shrink tubing from the tie layer.

[0263] Example 37 The method of any of the embodiments herein, particularly embodiments 33-36, wherein the step of heat-setting the folded outer layer further comprises attaching a heat shrink tube to the folded outer layer and removing the heat shrink tube after the folded outer layer is heat-set.

[0264] Example 38 The method of any example herein, especially example 37, further comprising removing the heat shrink tubing after heat setting the folded outer layer.

[0265] Example 39 1. A sheath for delivering a medical device, comprising: a continuous inner layer including first and second folds and overlapping folds extending circumferentially between the first and second folds, the folds including at least two radial overlaps of the inner layer, the continuous inner layer defining a lumen therethrough; a discontinuous outer layer having an overlapping portion and an underlying portion and extending at least partially around the inner layer, with at least a portion of the folded portion of the inner layer disposed between the overlapping portion and the underlying portion; an adhesive layer disposed between the inner layer and the outer layer, at least partially adhering the inner layer to the outer layer; an outer jacket extending around the outer layer, at least a portion of the sheath configured to locally expand due to a radially outward force exerted by a medical device against the inner layer from an unexpanded configuration in which the lumen has a first diameter to an expanded configuration in which the lumen has a second diameter greater than the first diameter, and then locally contract to at least partially return to the unexpanded configuration as the prosthetic device passes through the lumen.

[0266] Example 40 The sheath of any embodiment herein, particularly embodiment 39, wherein the outer jacket comprises an elastomeric material.

[0267] Example 41 The sheath of any embodiment herein, particularly embodiment 39 or 40, wherein the outer jacket comprises a thermoplastic polyurethane (e.g., Neusoft, and Tecoflex™ 80A B20).

[0268] Example 42 The sheath of any example herein, particularly Examples 39-41, wherein the outer jacket comprises an elastomer (e.g., a resilient polymer) having a Shore A hardness (durometer) ranging from about 10 to about 95 Shore A.

[0269] Example 43 The sheath of any embodiment herein, particularly embodiments 39-42, wherein the outer jacket comprises an elastomer having an elongation at break ranging from about 40% to about 800%.

[0270] Example 44 The sheath of any embodiment herein, particularly embodiments 39-43, wherein the outer jacket comprises an elastomer having a wall thickness ranging from about 0.003 inches to about 0.015 inches.

[0271] Example 45 The sheath of any of the embodiments herein, particularly embodiments 39-44, wherein the wall thickness of the outer jacket varies along the length of the outer jacket.

[0272] Example 46 The sheath of any embodiment herein, particularly embodiment 45, wherein the wall thickness of the outer jacket increases along the length of the outer jacket adjacent the proximal end of the sheath.

[0273] Example 47 The sheath of any of the embodiments herein, particularly embodiments 45-46, wherein the sheath includes a tapered segment adjacent the proximal end of the sheath, and the thickness of the outer jacket increases along the tapered segment.

[0274] Example 48 The sheath of any of the embodiments herein, particularly embodiments 39-47, wherein the outer jacket is bonded to the outer layer.

[0275] Example 49 The sheath of any of the embodiments herein, particularly embodiments 39-48, wherein the outer jacket is joined to the outer layer at a proximal end of the outer layer.

[0276] Example 50 The sheath of any of the embodiments herein, particularly embodiments 39-49, wherein the outer jacket is joined to the outer layer at a distal end of the outer layer.

[0277] Example 51 The sheath of any of the embodiments herein, particularly embodiments 39-50, wherein the outer jacket is joined to the outer layer along the length of the outer layer between the proximal and distal ends of the outer layer.

[0278] Example 52 The sheath of any of the embodiments herein, particularly embodiments 39-50, wherein the distal end of the outer jacket is joined to the inner layer.

[0279] Example 53 The sheath of any embodiment herein, particularly embodiment 52, wherein the outer jacket is bonded to a distal end surface of the inner layer.

[0280] Example 54 The sheath of any of the embodiments herein, particularly embodiments 39-53, wherein the outer jacket is joined to at least one of the proximal end of the outer layer, the distal end of the outer layer, and the distal end of the inner layer by chemical and / or mechanical fasteners.

[0281] Example 55 The sheath of any of the embodiments herein, particularly embodiment 54, wherein the mechanical fastener comprises a thermally bonded bond between the outer jacket and at least one of the outer layer and the inner layer.

[0282] Example 56 The sheath of any of the embodiments herein, particularly embodiments 39-54, wherein the outer jacket extends the entire length of the outer layer.

[0283] Example 57 A sheath described in any of the examples herein, particularly examples 39 to 56, wherein the first fold is configured to move closer to the second fold during passage of the medical device through the lumen to shorten the folded portion at a local axial location, and the shortening of the folded portion corresponds to a local expansion of the lumen.

[0284] Example 58 The sheath of any of the embodiments herein, particularly embodiments 39 to 57, wherein when the outer layer is expanded, the inner layer extends through a longitudinally extending opening in the outer layer.

[0285] Example 59 A sheath described in any of the embodiments herein, particularly embodiment 58, wherein the longitudinally extending opening is located between a longitudinally extending edge of the overlapping portion and a longitudinally extending edge of the underlying portion.

[0286] Example 60 The sheath of any example herein, particularly examples 39-59, wherein the inner layer is comprised of etched PTFE.

[0287] Example 61 The sheath of any example herein, particularly example 60, wherein the inner layer is composed entirely of etched PTFE.

[0288] Example 62 The sheath of any embodiment herein, particularly embodiment 60, wherein the inner layer is comprised of partially etched PTFE.

[0289] Example 63 The sheath of any example herein, particularly example 62, wherein the unetched portion of the outer surface of the inner layer extends longitudinally along the length of the inner layer and / or extends circumferentially around the periphery of the inner layer.

[0290] Example 64 The sheath of any of the examples herein, particularly Examples 62-63, wherein the unetched portion of the inner layer is located along the portion of the inner layer that contacts the outer surface of the outer layer.

[0291] Example 65 The sheath of any of the examples herein, particularly Examples 62-63, wherein the unetched portion of the inner layer is located along an area excluding the tie layer, and when the sheath is unexpanded, a surface of the inner layer adjacent the underlying portion of the outer layer is unetched.

[0292] Example 66 The sheath of any of the embodiments herein, particularly embodiments 39-65, wherein the inner layer has a wall thickness ranging from about 0.002 inches to about 0.006 inches.

[0293] Example 67 The sheath of any of the embodiments herein, particularly embodiments 39-65, wherein the inner layer has a wall thickness ranging from about 0.003 inches to about 0.005 inches.

[0294] Example 68 The sheath of any of the embodiments herein, particularly embodiments 39-65, wherein the inner layer has a wall thickness ranging from about 0.0035 inches to about 0.0045 inches.

[0295] Example 69 The sheath of any of the embodiments herein, particularly embodiments 39-68, wherein the outer layer exerts a radially inward force on the inner layer.

[0296] Example 70 The sheath of any of the embodiments herein, particularly embodiments 39-68, wherein the outer layer is comprised of at least one polymeric material.

[0297] Example 71 The sheath of any example herein, particularly example 70, wherein the outer layer is comprised of at least one of HDPE, nylon, and propylene.

[0298] Example 72 The sheath of any of the embodiments herein, particularly embodiments 39-71, wherein the outer layer has a wall thickness ranging from about 0.007 inches to about 0.013 inches.

[0299] Example 73 The sheath of any of the embodiments herein, particularly embodiments 39-71, wherein the outer layer has a wall thickness ranging from about 0.008 inches to about 0.012 inches.

[0300] Example 74 The sheath of any of the embodiments herein, particularly embodiments 39-71, wherein the outer layer has a wall thickness ranging from about 0.009 inches to about 0.011 inches.

[0301] Example 75 The sheath of any of the embodiments herein, particularly embodiments 39-74, wherein the tie layer extends at least partially around the outer surface of the inner layer.

[0302] Example 76 The sheath of any embodiment herein, particularly embodiment 75, wherein the tie layer extends around the entire outer surface of the inner layer.

[0303] Example 77 The sheath of any of the embodiments herein, particularly embodiments 39-74, wherein the tie layer extends at least partially around the inner surface of the outer layer.

[0304] Example 78 The sheath of any embodiment herein, particularly embodiment 77, wherein the tie layer extends around the entire inner surface of the outer layer.

[0305] Example 79 The sheath of any of the embodiments herein, particularly embodiments 39-78, wherein the tie layer extends between the outer layer and the overlapping folded portion of the inner layer.

[0306] Example 80 A sheath described in any of the embodiments herein, particularly embodiment 79, wherein the tie layer extends between the outer surface of the overlapping folded portion of the inner layer and the corresponding surface of the overlapping portion of the outer layer.

[0307] Example 81 A sheath described in any of the examples herein, particularly examples 79-80, wherein the tie layer does not extend between the inner surface of the overlapping folded portion of the inner layer and the corresponding surface of the underlying portion of the outer surface of the outer layer.

[0308] Example 82 The sheath of any of the embodiments herein, particularly embodiments 39-81, wherein the tie layer adheres at least a portion of the inner layer to a corresponding portion of the outer layer.

[0309] Example 83 The sheath of any embodiment herein, particularly any of embodiments 39-82, wherein the tie layer comprises a material having a Shore A hardness (durometer) of less than 90A.

[0310] Example 84 The sheath of any embodiment herein, particularly embodiment 83, wherein the tie layer is comprised of a thermoplastic polyurethane.

[0311] Example 85 The sheath of any example herein, particularly example 84, wherein the tie layer is comprised of an aliphatic polyether-based thermoplastic polyurethane (TPU).

[0312] Example 86 The sheath of any example herein, particularly example 85, wherein the tie layer is composed of Tecoflex™ 80A.

[0313] Example 87 The sheath of any embodiment herein, particularly embodiment 84, wherein the tie layer is comprised of an aromatic polyether or polyester-based thermoplastic polyurethane.

[0314] Example 88 The sheath of any example herein, particularly Example 87, wherein the tie layer is composed of Pellethane™ 80A.

[0315] Example 89 The sheath of any of the examples herein, particularly Examples 39 to 82, wherein the tie layer is comprised of a polyolefin or a polyamide.

[0316] Example 90 The sheath of any example herein, particularly example 89, wherein the tie layer is comprised of a maleic anhydride-modified polyolefin (PE, PP, or EVA).

[0317] Example 91 The sheath of any example herein, particularly Example 90, wherein the tie layer is comprised of Orevac™ resin.

[0318] Example 92 The sheath of any of the embodiments herein, particularly embodiments 39-91, wherein the tie layer has a wall thickness ranging from about 0.002 inches to about 0.005 inches.

[0319] Example 93 The sheath of any of the embodiments herein, particularly embodiments 39-91, wherein the tie layer has a wall thickness ranging from about 0.0025 inches to about 0.0040 inches.

[0320] Example 94 The sheath of any of the embodiments herein, particularly embodiments 39-91, wherein the tie layer has a wall thickness ranging from about 0.0025 inches to about 0.0035 inches.

[0321] Example 95 1. A sheath for delivering a medical device, comprising: a continuous inner layer including first and second folds and overlapping folds extending circumferentially between the first and second folds, the folds including at least two radial overlaps of the inner layer, the continuous inner layer defining a lumen therethrough; a discontinuous outer layer having an overlapping portion and an underlying portion and extending at least partially around the inner layer, with at least a portion of the folded portion of the inner layer disposed between the overlapping portion and the underlying portion; a tie layer disposed between the inner layer and the outer layer to at least partially adhere the inner layer to the outer layer; an outer jacket extending around the outer layer; A sheath, wherein at least a portion of the sheath is configured to locally expand from an unexpanded configuration in which the lumen has a first diameter to an expanded configuration in which the lumen has a second diameter larger than the first diameter due to a radially outward force exerted by a medical device against the inner layer, and then locally contract to at least partially return to the unexpanded configuration as the prosthetic device passes through the lumen, and wherein a lubricant is provided between the outer jacket and the outer layer.

[0322] Example 96 The sheath of any of the embodiments herein, particularly embodiment 95, wherein the lubricant is provided on an outer surface of the outer layer proximal to a longitudinally extending edge of the overlapping portion.

[0323] Example 97 The sheath of any of the embodiments herein, particularly embodiments 95-96, wherein at least a portion of the folded portion of the inner layer extends beyond the longitudinally extending edge of the overlapping portion and along the outer surface of the outer layer.

[0324] Example 98 The sheath of any of the embodiments herein, particularly embodiment 97, wherein the lubricant is provided along the portion of the folded portion of the inner layer that extends along the outer surface of the outer layer.

[0325] Example 99 A sheath as described in any of the embodiments herein, particularly embodiment 98, wherein the lubricant is provided along a portion of the outer surface of the outer layer adjacent to the portion of the folded portion of the inner layer extending along the outer surface of the outer layer.

[0326] Example 100 The sheath of any of the embodiments herein, particularly embodiments 95-99, wherein the lubricant reduces friction between the outer layer and the outer jacket during expansion of the sheath.

[0327] Example 101 The sheath of any of the embodiments herein, particularly embodiments 95-100, wherein the lubricant reduces friction between the inner layer and the outer jacket during expansion of the sheath.

[0328] Example 102 The sheath of any of the embodiments herein, particularly embodiments 95-101, wherein the lubricant is applied as a band around a portion of the circumference of the outer layer, the band of lubricant extending longitudinally along the length of the outer layer.

[0329] (Example 103) The sheath of any embodiment herein, particularly any of embodiments 95-102, wherein the lubricant comprises a curable material.

[0330] Example 104 The sheath of any example herein, particularly example 103, wherein the lubricant is hardenable at room temperature.

[0331] Example 105 The sheath of any embodiment herein, particularly embodiments 95-104, wherein the lubricant is comprised of medical grade silicone.

[0332] Example 106 The sheath of any of the Examples herein, particularly Examples 95-105, wherein the lubricant comprises at least one of Med10-6670, Duraglide™, and / or Christo-Lube™.

[0333] (Example 107) 1. A method of delivering a prosthetic device to a treatment site, comprising: introducing an expandable sheath into the vascular system of a subject; advancing the prosthetic device through the lumen of the expandable sheath, the prosthetic device exerting an outward radial force on an inner tubular layer of the expandable sheath; locally expanding the lumen of the sheath at a local axial location due to an outward radial force exerted by the prosthetic device against an inner surface of the lumen during advancement of the prosthetic device through the local axial location, The step of locally expanding the lumen comprises: circumferentially moving a first fold of the inner layer proximate a second fold of the inner layer to shorten an overlap portion of the inner layer extending circumferentially between the first and second folds; and expanding the outer layer along at least one elongated gap disposed adjacent to at least one of the folds and generally aligned with the axis of the lumen; expanding the outer layer along the at least one elongated gap includes moving a first portion of the outer layer away from a second portion of the outer layer as the first fold moves proximate the second fold, the gap being defined between the first and second portions; the inner layer and the outer layer being at least partially adhered via a tie layer extending therebetween; contracting the lumen of the sheath by at least partially returning to an unexpanded configuration as the prosthetic device passes through the lumen; delivering the prosthetic device to a treatment site.

[0334] Example 108 The method of any embodiment herein, particularly embodiment 107, wherein an outer jacket extends around the outer layer and provides an inward radial force against the outer layer.

[0335] Example 109 The method of any of the embodiments herein, particularly embodiments 107-108, wherein the tie layer extends between an outer surface of the overlapping folded portion of the inner layer and a corresponding surface of the overlapping portion of the outer layer, the tie layer adhering the inner layer to the outer layer.

[0336] Example 110 The method of any of the embodiments herein, particularly embodiments 107-109, wherein the tie layer does not extend between an inner surface of the overlapping folded portion of the inner layer and a corresponding surface of the underlying portion of the outer surface of the outer layer such that the outer layer and the inner layer are not adhered together, and during expansion, the inner surface of the overlapping folded portion of the inner layer expands into the elongated gap of the outer layer.

[0337] Example 111 The method of any of the embodiments herein, particularly embodiments 107-110, wherein the step of expanding the outer layer along at least one gap further comprises expanding the gap over the overlapping portion of the inner layer.

[0338] Example 112 The method of any of the embodiments herein, particularly embodiments 107-111, further comprising extending the inner layer into the gap.

[0339] Example 113 The method of any of the embodiments herein, particularly embodiments 107-112, further comprising combining the first and second folds to eliminate the overlap at the local axial location.

[0340] Example 114 The method of any of the embodiments herein, particularly embodiments 107-113, further comprising expanding the inner layer into a substantially tubular, unfolded cross-section at the local axial location.

[0341] Example 115 The method of any of the embodiments herein, particularly embodiments 107-114, further comprising applying a radial force to the gap in the outer layer to expand a width of the outer layer along the gap.

[0342] Example 116 The method of any embodiment herein, particularly embodiment 115, further comprising moving one of the folds closer to the gap while applying the radial force.

[0343] Example 117 The method of any of the embodiments herein, particularly embodiment 116, further comprising: the gap being adjacent to the first fold; and passing the first fold radially under the gap as the first fold moves closer to the second fold.

[0344] Example 118 The method described in any of the examples herein, particularly examples 107 to 117, wherein the step of introducing the prosthetic device comprises introducing a stented heart valve into the proximal end of the lumen, and further comprises the step of extending the stented heart valve out of the distal end of the elongated lumen.

[0345] Example 119 The method of any embodiment herein, particularly embodiment 118, further comprising expanding the stented heart valve after it exits the elongated lumen.

[0346] Example 120 The method of any of the embodiments herein, particularly embodiments 107-119, wherein a lubricant is disposed between the outer jacket and the outer layer proximal to a longitudinal edge of the overlapping portion, the lubricant reducing friction between the inner layer and the outer jacket during expansion of the sheath.

[0347] Example 121 1. A method of manufacturing a sheath for delivering a medical device, comprising: providing a continuous inner layer including first and second folds and overlapping folds extending circumferentially between the first and second folds, the folds including at least two radial overlaps of the inner layer, the continuous inner layer defining a lumen therethrough; providing a discontinuous outer layer having an overlapping portion and an underlying portion and extending at least partially around an inner layer, at least a portion of the folded portion of the inner layer being disposed between the overlapping portion and the underlying portion; providing a tie layer disposed between the inner layer and the outer layer to at least partially adhere the inner layer to the outer layer; bonding the inner layer to the outer layer; providing a lubricant at a location proximate a longitudinally extending edge of the overlapping portion; providing an outer jacket about the outer layer and joining the outer jacket to the outer layer at at least one of the proximal and distal ends thereof.

[0348] Example 122 The method of any example herein, particularly example 121, wherein the inner layer is joined to the outer layer by the tie layer.

[0349] Example 123 The method of any of the embodiments herein, particularly embodiment 122, wherein the tie layer is disposed axially along the length of at least one of the inner layer and the outer layer, and the inner layer is axially joined to the outer layer along the length of the sheath via the tie layer.

[0350] Example 124 The method of any of the examples herein, particularly Examples 121-123, wherein the tie layer bonds the inner layer to the outer layer by heat setting.

[0351] Example 125 The method of any example herein, particularly example 124, wherein the tie layer bonds the inner layer to the outer layer by heat curing at room temperature.

[0352] Example 126 The method of any example herein, particularly example 124, wherein the tie layer bonds the inner layer to the outer layer by heat curing at a temperature above room temperature.

[0353] Example 127 The method of any of the embodiments herein, particularly Examples 121-126, wherein the outer layer and the tie layer are coextruded.

[0354] Example 128 The method of any of the embodiments herein, particularly embodiments 121-127, wherein the lubricant is provided on an outer surface of the outer layer proximate a longitudinally extending edge of the overlapping portion.

[0355] Example 129 The method of any embodiment herein, particularly embodiment 128, wherein at least a portion of the folded portion of the inner layer extends beyond the longitudinally extending edge of the overlapping portion and along the outer surface of the outer layer.

[0356] Example 130 The method of any example herein, particularly example 129, wherein the lubricant is disposed along the portion of the folded portion of the inner layer that extends along the outer surface of the outer layer.

[0357] Example 131 The method of any example herein, particularly example 130, wherein the lubricant is disposed along a portion of the outer surface of the outer layer adjacent the portion of the folded portion of the inner layer that extends along the outer surface of the outer layer.

[0358] Example 132 The method of any of the embodiments herein, particularly embodiments 121-131, wherein the lubricant is applied as a band extending around a portion of the circumference of the outer layer, the band of lubricant extending longitudinally along the length of the outer layer, and the lubricant is applied to the outer layer before the outer jacket is applied.

[0359] Example 133 The method of any of the embodiments herein, particularly embodiments 121-132, wherein the lubricant comprises a thermosetting material.

[0360] Example 134 The method of any example herein, particularly example 133, wherein the lubricant is curable at room temperature.

[0361] Example 135 The method of any example herein, particularly examples 121-134, further comprising etching at least a portion of an outer surface of the inner layer.

[0362] Example 136 The method of any example herein, particularly example 135, wherein the unetched portion of the outer surface of the inner layer extends longitudinally along the length of the inner layer and / or extends circumferentially around the periphery of the inner layer.

[0363] Example 137 The method of any of the embodiments herein, particularly embodiments 135-136, wherein the unetched portion of the inner layer is located along the portion of the inner layer that contacts the outer layer.

[0364] Example 138 The method of any of the embodiments herein, particularly embodiments 135-137, wherein the unetched portions of the inner layer are along those locations excluding the tie layer.

[0365] Example 139 The method of any example herein, particularly examples 135-138, wherein a surface of the inner layer adjacent the underlying portion of the outer layer is not etched when the sheath is unexpanded.

[0366] Example 140 The method of any of the embodiments herein, particularly embodiments 121-139, wherein the outer jacket is joined to the outer layer at both the proximal and distal ends of the outer jacket and outer layer.

[0367] Example 141 The method of any of the embodiments herein, particularly embodiments 121-140, wherein the outer jacket is connected to the outer layer along the length of the outer layer.

[0368] Example 142 The method of any of the embodiments herein, particularly embodiments 121-141, wherein the outer jacket is bonded to the outer layer by heat treatment.

[0369] (Example 143) The method of any of the embodiments herein, particularly embodiments 121-142, further comprising releasing any bond formed between the inner layer and the underlying portion of the outer layer, wherein the proximal and distal ends of the inner and outer layers remain joined.

[0370] Example 144 The method of any example herein, particularly example 143, wherein the tie layer is not provided along the underlying portion of the outer layer, and a bond between the inner layer and the outer layer along the tie layer remains intact.

[0371] Example 145 The method of any of the embodiments herein, particularly embodiments 143-144, wherein a mandrel is passed at least partially through the lumen of the inner layer to release any bond between the inner layer and the underlying portion of the outer layer.

[0372] Example 146 The method of any of the examples herein, particularly Examples 121-145, further comprising reflowing (rerolling) to reduce the outer diameter and restore the circular shape.

[0373] Example 147 1. A sheath for delivering a medical device, comprising: a continuous inner layer including first and second folds and overlapping folds extending circumferentially between the first and second folds, the folds including at least two radial overlaps of the inner layer, the continuous inner layer defining a lumen therethrough; a discontinuous outer layer having an overlapping portion and an underlying portion and extending at least partially around the inner layer, with at least a portion of the folded portion of the inner layer disposed between the overlapping portion and the underlying portion; a coiled wire along the length of the sheath that provides a uniform bend in the sheath to prevent kinking; a tie layer disposed between the inner layer and the outer layer to at least partially adhere the inner layer to the outer layer; an outer jacket extending around the outer layer; A sheath, wherein at least a portion of the sheath is configured to locally expand from an unexpanded configuration in which the lumen has a first diameter to an expanded configuration in which the lumen has a second diameter greater than the first diameter due to a radially outward force exerted against the inner layer by a medical device, and then locally contract as the prosthetic device passes through the lumen to at least partially return to the unexpanded configuration.

[0374] Example 148 The sheath of any embodiment herein, particularly embodiment 147, wherein the coiled wire is embedded in the outer layer.

[0375] Example 149 The sheath of any embodiment herein, particularly embodiments 147-148, wherein the coiled wire is coextruded with the outer layer.

[0376] Example 150 The sheath described in any of the embodiments herein, particularly embodiment 147, wherein the coiled wire is disposed between the outer layer and the tie layer.

[0377] Example 151 The sheath of any of the embodiments herein, particularly embodiment 147, wherein the coiled wire is at least partially embedded within both the outer layer and the tie layer.

[0378] Example 152 The sheath of any embodiment herein, particularly embodiment 147, wherein the coiled wire is disposed on an outer surface of the bonding layer, and the outer layer is reflowed onto the sheath.

[0379] Example 153 The sheath of any of the embodiments herein, particularly embodiments 147-152, wherein the coiled wire comprises a metal wire or a polymer wire.

[0380] Example 154 The sheath of any of the embodiments herein, particularly embodiments 147-153, wherein the coiled wire is made of at least one of PET, PEEK, stainless steel, and Nitinol.

[0381] Example 155 The sheath described in any of the embodiments herein, particularly embodiments 147-154, wherein the coiled wire defines a helical path about the longitudinal axis of the sheath.

[0382] Example 156 The sheath described in any of the embodiments herein, particularly embodiments 147-155, wherein the coiled wire defines an overlapping helical path about the longitudinal axis of the sheath.

[0383] Example 157 The sheath described in any embodiment herein, particularly embodiment 156, wherein the overlapping helical paths define a continuous diamond pattern along the length of the sheath.

[0384] Example 158 The sheath of any embodiment herein, particularly embodiments 147-157, wherein the coiled wire is a flat wire.

[0385] Example 159 The sheath of any of the embodiments herein, particularly embodiments 147 to 157, wherein the coiled wire is a round wire.

[0386] Example 160 The sheath of any embodiment herein, particularly embodiments 147-159, wherein the coiled wire has a thickness of about 0.002" to about 0.008".

[0387] Example 161 The sheath of any embodiment herein, particularly embodiments 147-158, wherein the coiled wire has a thickness of about 0.003" to about 0.007".

[0388] Example 162 The sheath of any embodiment herein, particularly embodiments 147-159, wherein the coiled wire has a thickness of about 0.004" to about 0.007".

[0389] Example 163 The sheath of any embodiment herein, particularly embodiments 147-159, wherein the coiled wire has a thickness of about 0.006".

[0390] Example 164 The sheath of any of the embodiments herein, particularly embodiments 147-163, wherein the distance between adjacent coils of the coiled wire corresponds to the diameter of the coiled wire.

[0391] Example 165 The sheath of any embodiment herein, particularly embodiments 147-164, wherein the distance between adjacent coils of the coiled wire is about 0.006".

[0392] Example 166 The sheath of any embodiment herein, particularly embodiment 165, wherein the coiled wire has a diameter of about 0.006".

[0393] Example 167 The sheath of any of the embodiments herein, particularly embodiments 147-166, wherein a lubricant is provided between the outer jacket and the outer layer to reduce friction during expansion of the sheath.

[0394] Example 168 The sheath described in any of the embodiments herein, particularly embodiment 167, wherein the lubricant is provided on an outer surface of the outer layer proximal to the longitudinally extending edge of the overlapping portion.

[0395] Example 169 A sheath described in any of the examples herein, particularly example 168, wherein at least a portion of the folded portion of the inner layer extends beyond the longitudinally extending edge of the overlapping portion and along the outer surface of the outer layer, and the lubricant is provided along the portion of the folded portion of the inner layer that extends along the outer surface of the outer layer to reduce friction between the inner layer and the outer layer during expansion of the sheath.

[0396] (Example 170) 1. A method of delivering a prosthetic device to a treatment site, comprising: introducing an expandable sheath into the vascular system of a subject; advancing the prosthetic device through the lumen of the expandable sheath, the prosthetic device exerting an outward radial force on an inner tubular layer of the expandable sheath; locally expanding the lumen of the sheath at a local axial location due to an outward radial force exerted by a medical device against an inner surface of the lumen during advancement of the prosthetic device through the local axial location, The step of locally expanding the lumen comprises: circumferentially moving a first fold of the inner layer proximate a second fold of the inner layer to shorten an overlap portion of the inner layer extending circumferentially between the first and second folds; and expanding the outer layer along at least one elongated gap disposed adjacent to at least one of the folds and generally aligned with the axis of the lumen; Extending the outer layer along at least one elongated gap comprises: moving a first portion of the outer layer away from a second portion of the outer layer as the first fold moves proximate the second fold, the gap being defined between the first and second portions; a coiled wire structure embedded in the inner layer and / or the outer layer, the coiled wire increasing kink resistance and column strength of the expandable sheath; contracting the lumen of the sheath by at least partially returning to an unexpanded configuration as the prosthetic device passes through the lumen; and delivering the prosthetic device to a treatment site.

[0397] Example 171 The method of any embodiment herein, particularly embodiment 170, wherein the coiled wire exerts an inward radial force on the inner layer.

[0398] Example 172 The method of any embodiment herein, particularly embodiments 170-171, wherein an outer jacket extends around the outer layer and provides an inward radial force against the outer layer.

[0399] (Example 173) The method of any of the embodiments herein, particularly embodiments 170-172, wherein the tie layer extends between an outer surface of the overlapping folded portion of the inner layer and a corresponding surface of the overlapping portion of the outer layer, the tie layer adhering the inner layer to the outer layer.

[0400] Example 174 The method of any of the embodiments herein, particularly embodiments 170-173, wherein the tie layer does not extend between an inner surface of the overlapping folded portion of the inner layer and a corresponding surface of the underlying portion of the outer surface of the outer layer, such that the outer layer and the inner layer are not adhered together.

[0401] Example 175 The method of any of the embodiments herein, particularly embodiments 170-174, wherein the step of expanding the outer layer along at least one gap further comprises expanding the gap over the overlapping portion.

[0402] Example 176 The method of any of the embodiments herein, particularly embodiments 170-175, further comprising extending the inner layer into the gap.

[0403] Example 177 The method of any of the embodiments herein, particularly embodiments 170-176, further comprising combining the first and second folds to eliminate the overlap at the local axial location.

[0404] Example 178 The method of any of the embodiments herein, particularly embodiments 170-177, further comprising expanding the inner layer into a substantially tubular, unfolded cross-section at the local axial location.

[0405] (Example 179) The method of any of the embodiments herein, particularly embodiments 170-178, further comprising applying a radial force to the gap in the outer layer to expand the width of the outer layer along the gap.

[0406] Example 180 The method of any embodiment herein, particularly embodiment 179, further comprising moving one of the folds closer to the gap while applying the radial force.

[0407] Example 181 The method of any of the embodiments herein, particularly embodiment 180, further comprising: the gap being adjacent to the first fold; and passing the first fold radially under the gap as the first fold moves closer to the second fold.

[0408] Example 182 The method described in any of the examples herein, particularly examples 170 to 181, wherein the step of introducing the prosthetic device comprises introducing a stent-mounted heart valve into the proximal end of the lumen, and further comprises the step of extending a soft tissue heart valve out of the distal end of the elongated lumen.

[0409] (Example 183) The method of any embodiment herein, particularly embodiment 182, further comprising expanding the stented heart valve after it exits the elongated lumen.

[0410] Example 184 The method of any of the embodiments herein, particularly embodiments 170-183, wherein a lubricant is disposed between the outer jacket and the outer layer proximal to a longitudinally extending edge of the overlapping portion, and the lubricant reduces friction between the inner layer and the outer jacket during expansion of the sheath.

[0411] Example 185 An elastomeric jacket for an expandable and retrievable sheath, the sheath including an axial reinforcing member embedded within the elastomeric jacket.

[0412] Example 186 The elastomeric jacket of any example herein, particularly example 185, wherein the elastomeric jacket has an expansion force of less than 50 N.

[0413] Example 187 The elastomeric jacket of any of the examples herein, particularly Examples 185-186, wherein the elastomeric jacket has a burst pressure of greater than 8 psi.

[0414] Example 188 The elastomeric jacket of any example herein, particularly Examples 185-187, wherein the reinforcement member is constructed from a material having a Shore D durometer ranging from 45D to 76D.

[0415] Example 189 The elastomeric jacket of any embodiment herein, particularly embodiments 185-188, wherein the reinforcement member is constructed from a high durometer polyether block amide, polyamide, or polyurethane.

[0416] Example 190 The elastomeric jacket of any of the embodiments herein, particularly embodiments 185-189, wherein the elastomeric jacket comprises at least one layer of material and at least one reinforcing member.

[0417] (Example 191) The elastomeric jacket of any embodiment herein, particularly embodiment 190, wherein the at least one reinforcing member is constructed of a material compatible with the at least one layer of the elastomeric jacket.

[0418] Example 192 The elastomeric jacket of any embodiment herein, particularly embodiment 185, wherein the reinforcing member comprises a heat-bondable member embedded within the elastomeric jacket.

[0419] (Example 193) The elastomeric jacket of any example herein, especially example 192, wherein the thermally bondable component is made of a polyolefin backbone material comprising at least one of LDPE (low density polyethylene), LLDPE (linear low density polyethylene), EVA (ethylene vinyl acetate), HDPE (high density polyethylene), PP (polypropylene), or a polyolefin copolymer having grafted functional groups comprising at least one of maleic anhydride or acrylic acid.

[0420] (Example 194) The elastomeric jacket of any embodiment herein, particularly embodiments 192-193, wherein the heat-bondable member is fused to the elastomeric jacket by at least one of heat and pressure.

[0421] Example 195 The elastomeric jacket of any of the embodiments herein, particularly embodiments 185-194, wherein the reinforcing member reduces axial bunching of the elastomeric outer jacket during insertion into a patient's vasculature.

[0422] In view of the many embodiments to which the principles of the disclosed invention may be applied, the illustrated embodiments are merely preferred embodiments of the invention and should not be considered as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. It is therefore claimed that all inventions fall within the scope and spirit of these claims. [Explanation of symbols]

[0423] 8 Sheath 10 Delivery device 12 Prosthetic Devices 14 Guide catheter 16 Balloon catheter 18 Nose Catheter 22 Sheath 24 Inner layer 26 outer polymer tubular layer 28 Intermediate tubular layer 30 lumen 32 Inner surface 34 Outer surface 36 Notches or Cuts 37 Outer surface 38 Proximal end 40 distal end 42 Soft Tip 44 Bulge 46 Unexpanded Outer Diameter 48 Expanded Outer Diameter 50 outer polymer covering 54 Peel Tab 56, 58, 60, 62, 64 struts 66 Sheath 68 Inner polymer layer 69 Radiopaque Marker 70 outer polymer tubular layer 72 Lumen 74 Longitudinal notch 76 Longitudinal cut 77 scoreline 78 First Part 80 Second Part 81 outer polymer covering 83 External surface 85 folding regions 90 First corner 92 Second corner 94 Lumen, gap 96 Mandrel 100 sheath, outer layer 101 Introducer housing 102 Soft tip part 104 Distal end 108 Inner layer 110 Outer layer 112 Marker, C-band 114 Proximal Flared End 116 Lumen 118 Folding part 120 overlapping area 122 Bottom part 124 The First Edge 126 The Second Edge 128 Adhesive materials, adhesive layers 130 Inner surface 132 Gap 140 outer jacket 142 Lubricants 144 Junction 160 coiled wire 166 Expandable Sheath 168 Inner tubular layer 169 Longitudinal slit 170 Outer tubular layer 171 Folding flap 172 Lumen 173 base 174 Binding layer 175 Upper part 177 Bottom part 179 creases 183 External surface 700 sheath 702 Elastic Cover 704 Lumen, inner layer 706 Outer layer 708 Proximal end 709 Distal end 710 Folding part 712 overlapping part 714 Lower part 716 Weakened Part 722 seam 800 sheath 802 outer cover 804 Inner layer 806 outer layer 808 First Fold 810 Second Fold 900 sheath 902 Inner layer 904 Elastic Cover 906 Folding part 908 Lumen 910 Area 1000 sheath 1002 Inner layer 1004 Outer layer 1006 Folds 1100 Sheath 1102 Inner layer 1104 Outer layer 1106 Folding part 1108 overlapping part 1110 Bottom part

Claims

1. 1. A sheath for delivering a medical device, comprising: a continuous inner layer defining a lumen therethrough and including first and second folds and overlapping folds extending circumferentially between the first and second folds, the folds including at least two radial overlaps of the inner layer; a discontinuous outer layer extending at least partially around the inner layer, the outer layer having an overlapping portion disposed radially outward from the folded portion of the inner layer and an underlying portion disposed radially inward from the folded portion of the inner layer, at least a portion of the folded portion of the inner layer being located between the overlapping portion and the underlying portion; a tie layer disposed between the inner layer and the outer layer to at least partially adhere the inner layer to the outer layer; an outer jacket extending around the outer layer; A sheath, wherein at least a portion of the sheath is configured to locally expand from an unexpanded configuration in which the lumen has a first diameter to an expanded configuration in which the lumen has a second diameter larger than the first diameter due to a radially outward force exerted by a medical device against the inner layer, and then locally contract as a prosthetic device passes through the lumen to at least partially return to the unexpanded configuration.

2. The sheath of claim 1 , wherein the wall thickness of the outer jacket varies along the length of the outer jacket.

3. The sheath of any one of claims 1 to 2, wherein the wall thickness of the outer jacket increases along the length of the outer jacket adjacent the proximal end of the sheath.

4. The sheath of any one of claims 1 to 3, wherein the sheath includes a tapered segment adjacent a proximal end of the sheath, the thickness of the outer jacket increasing along the length of the tapered segment.

5. The sheath of any one of claims 1 to 4, wherein the outer jacket is joined to the outer layer along the length of the outer layer between the proximal and distal ends of the outer layer.

6. the outer jacket includes an axially extending reinforcing member embedded within the outer jacket to reduce axial bunching of the elastomeric outer jacket during insertion into a patient's vasculature, and the outer jacket includes a first polymer layer and a second polymer layer; the reinforcing member is constructed from a material having a Shore D durometer in the range of 45D to 76D; The sheath of any one of claims 1 to 5, wherein the outer jacket has a burst pressure of greater than 8 psi.

7. the first fold is configured to move proximate the second fold during passage of the medical device through the lumen to shorten the fold at a local axial location, the shortening of the fold corresponding to a local dilation of the lumen; the inner layer extends through a longitudinally extending opening in the outer layer when the outer layer is expanded; 7. The sheath of claim 1, wherein the longitudinally extending opening is located between a longitudinally extending edge of the overlapping portion and a longitudinally extending edge of the underlying portion.

8. the inner layer is made of etched PTFE; The sheath of any one of claims 1 to 7, wherein the unetched portion of the inner layer is provided along a portion of the inner layer that contacts the outer surface of the outer layer.

9. the unetched portions of the inner layer are disposed along these locations excluding the tie layer; The sheath of claim 8 , wherein a surface of the inner layer adjacent the underlying portion of the outer layer is not etched when the sheath is unexpanded.

10. The sheath of any one of claims 1 to 9, wherein the tie layer extends at least partially around an outer surface of the inner layer.

11. The sheath of any one of claims 1 to 10, wherein the tie layer extends between the outer layer and the overlapping folded portion of the inner layer.

12. The sheath of claim 11 , wherein the tie layer extends between an outer surface of the overlapping folded portion of the inner layer and a corresponding surface of the overlapping portion of the outer layer.

13. 13. The sheath of claim 11, wherein the tie layer does not extend between an inner surface of the overlapping folded portion of the inner layer and a corresponding surface of the underlying portion of the outer surface of the outer layer.

14. 1. A sheath for delivering a medical device, comprising: a continuous inner layer including first and second folds and overlapping folds extending circumferentially between the first and second folds, the folds including at least two radial overlaps of the inner layer, the continuous inner layer defining a lumen therethrough; a discontinuous outer layer extending at least partially around the inner layer, the outer layer having an overlapping portion disposed radially outward from the folded portion of the inner layer and an underlying portion disposed radially inward from the folded portion of the inner layer, at least a portion of the folded portion of the inner layer being disposed between the overlapping portion and the underlying portion; a tie layer disposed between the inner layer and the outer layer to at least partially adhere the inner layer to the outer layer; an outer jacket extending around the outer layer; A sheath, wherein at least a portion of the sheath is configured to locally expand from an unexpanded configuration in which the lumen has a first diameter to an expanded configuration in which the lumen has a second diameter larger than the first diameter due to a radially outward force exerted by a medical device against the inner layer, and then locally contract as a prosthetic device passes through the lumen to at least partially return to the unexpanded configuration, and wherein a lubricant is provided between the outer jacket and the outer layer.

15. The sheath of claim 14 , wherein the lubricant is disposed on an outer surface of the outer layer proximal to a longitudinally extending edge of the overlapping portion.

16. at least a portion of the folded portion of the inner layer extends beyond the longitudinally extending edge of the overlapping portion and along an outer surface of the outer layer; The sheath of any one of claims 14 to 15, wherein the lubricant is provided along the portion of the folded portion of the inner layer that extends along an outer surface of the outer layer.

17. 17. The sheath of claim 16, wherein the lubricant is disposed along a portion of the outer surface of the outer layer adjacent the portion of the folded portion of the inner layer that extends along the outer surface of the outer layer.

18. 18. The sheath of any one of claims 14 to 17, wherein the lubricant is applied as a band around a portion of the circumference of the outer layer, the band of lubricant extending longitudinally along the length of the outer layer.

Images