Expandable sheath

Abstract

To provide an expandable sheath.SOLUTION: The expandable sheath has a first polymeric layer and a braided layer positioned radially outward of the first polymeric layer. The braided layer includes a plurality of filaments braided together. The expandable sheath further includes a resilient elastic layer positioned radially outward of the braided layer. The elastic layer is configured to apply radial force to the braided layer and the first polymeric layer. The expandable sheath further includes a second polymeric layer positioned radially outward of the elastic layer and bonded to the first polymeric layer such that the braided layer and the elastic layer are encapsulated between the first and second polymeric layers. Methods of making and using the devices disclosed herein are also disclosed, as are crimping devices that may be used in the methods of making the devices disclosed herein.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 62 / 655,059, filed Apr. 9, 2018, and U.S. Provisional Patent Application No. 62 / 722,958, filed Aug. 26, 2018. Each of these applications is hereby incorporated by reference in its entirety for all purposes.

[0002] This application relates to an expandable introducer sheath for an artificial device such as a trans - catheter heart valve, and a method of manufacturing the same.

Background Art

[0003] An intravascular delivery catheter assembly is used to implant an artificial device such as an artificial valve at a body location that is not easily accessible surgically or where access without an invasive surgical procedure is desirable. For example, an artificial aortic valve, an artificial mitral valve, an artificial tricuspid valve, and / or an artificial pulmonary valve can be delivered to a treatment site using minimally invasive surgical techniques.

[0004] An introducer sheath can be used to safely introduce a delivery device into a patient's blood vessel (e.g., the femoral artery). Generally, an introducer sheath has an elongated sleeve that is inserted into the blood vessel and a housing that houses one or more sealing valves, and these sealing valves allow the delivery device to be placed in fluid communication with the blood vessel with minimal blood loss. Such an introducer sheath can be radially expandable. However, such a sheath tends to have a complex mechanism such as a ratchet mechanism to maintain the sheath in an expanded configuration when a device having a diameter larger than the diameter of the sheath body is introduced. Also, existing expandable sheaths can tend to axially elongate as a result of the application of longitudinal forces associated with passing an artificial device through the sheath. Such elongation causes the diameter of the sheath to correspondingly shrink, thereby increasing the force required to insert an artificial device through the narrowed sheath.

Prior Art Documents

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2012 / 0123529 [Patent Document 2] U.S. Patent Application Publication No. 2012 / 0239142 [Patent Document 3] U.S. Patent Application Publication No. 2018 / 0153689 [Patent Document 4] U.S. Patent Application Publication No. 2014 / 0379067 [Patent Document 5] U.S. Patent Application Publication No. 2016 / 0296730 [Patent Document 6] U.S. Patent Application Publication No. 2018 / 0008407 [Patent Document 7] U.S. Patent Application No. 14 / 880,109 [Patent Document 8] U.S. Patent Application No. 14 / 880,111 [Overview of the project] [Problems that the invention aims to solve]

[0006] Therefore, there is still a need in the art for improved introducer sheaths for intravascular systems used to implant valves and other prosthetic devices. [Means for solving the problem]

[0007] The expandable sheath disclosed herein comprises a first polymer layer and a braided layer positioned radially outward from the first polymer layer. The braided layer comprises a plurality of interwoven filaments. The expandable sheath further comprises a resilient elastic layer positioned radially outward from the braided layer. The elastic layer is configured to apply radial forces to the braided layer and the first polymer layer. The expandable sheath disclosed herein further comprises a second polymer layer positioned radially outward from the elastic layer, the second polymer layer being bonded to the first polymer layer such that the braided layer and the elastic layer are encased between the first and second polymer layers. As a medical device passes through the sheath, the diameter of the sheath expands from the first diameter to the second diameter around the medical device, while the first and second polymer layers resist axial stretching of the sheath such that the length of the sheath remains substantially constant. The sheath elastically returns to its first diameter due to the radial force applied by the elastic layer as the medical device passes through.

[0008] In some embodiments, the first and second polymer layers have a plurality of longitudinally extending folds when the sheath is at a first diameter. These longitudinally extending folds form a plurality of circumferentially spaced ridges and a plurality of circumferentially spaced grooves. As a medical device passes through the sheath, the ridges and grooves may flatten out, causing the sheath to expand radially.

[0009] The elastic layer may comprise one or more elastic bands wound helically on the braided layer. In some embodiments, two elastic bands are wound in opposite helical directions.

[0010] As described above, the braided layer is positioned radially outward from the first polymer layer but radially inward from the second polymer layer. The filaments of the braided layer can be movable between the first and second polymer layers so that the length of the sheath remains substantially constant while the braided layer can expand radially as the medical device passes through the sheath, and in some embodiments, the filaments of the braided layer are not engaged or adhered to the first or second polymer layer at all. The filaments of the braided layer can also be elastically buckled when the sheath is at a first diameter. In this embodiment, the first and second polymer layers can be fitted to each other in a plurality of open spaces between the filaments of the braided layer. Some embodiments may include one or more longitudinally extending cords fitted to the braided layer.

[0011] The outer cover may extend longitudinally beyond the distal ends of the first polymer layer, braided layer, elastic layer, and second polymer layer to form overhangs. In some embodiments, the outer cover includes one or more longitudinally extending slits, brittle portions, or grooves. In some embodiments, the outer cover is formed from a heat-shrinkable material. In some embodiments, the outer cover is an elastomer.

[0012] Furthermore, methods for producing expandable sheaths are disclosed herein. These methods include the steps of: positioning a braided layer radially outward of a first polymer layer positioned on a mandrel (the braided layer comprising a plurality of interwoven filaments, and the mandrel having a first diameter); applying an elastic layer radially outward of the braided layer (the elastic layer being configured to apply radial forces to the first polymer layer and the braided layer); applying a second polymer layer radially outward of the elastic layer; applying heat and pressure to the first polymer layer, the braided layer, the elastic layer, and the second polymer layer (so that the first polymer layer and the second polymer layer bond to each other and enclose the braided layer and the elastic layer, thereby forming an expandable sheath); and removing the expandable sheath from the mandrel so that the expandable sheath can be at least partially radially contracted to a second diameter less than the first diameter under the radial forces applied by the elastic layer.

[0013] In some embodiments, the step of applying the elastic layer further includes the step of wrapping one or more elastic bands around the braided layer. These elastic bands can be applied in a stretched configuration. Alternatively, after the step of applying the braided layer, the first polymer layer and the braided layer can be removed from the mandrel, and the elastic layer can be applied in a relaxed or moderately stretched state (the elastic layer is then stretched before the step of applying the second polymer layer by placing the first polymer layer, the braided layer, and the elastic layer back onto the mandrel).

[0014] In some embodiments, the step of applying heat and pressure during the process of fabricating an expandable sheath may be achieved by placing a mandrel in a container containing a thermally expandable material and heating the thermally expandable material in the container. In some embodiments, a radial pressure of 100 MPa or more is applied to the mandrel via the thermally expandable material. In some embodiments, the step of applying heat and pressure further includes applying a heat shrink tubing layer on a second polymer layer and applying heat to the heat shrink tubing layer.

[0015] Some embodiments of a method for fabricating a sheath include the step of elastically buckling the filaments of the braided layer of the sheath as the sheath is radially contracted to a second diameter. Some embodiments include the step of attaching one or more longitudinally extending cords to the braided layer to prevent axial elongation of the braided layer.

[0016] In some embodiments, the detached expandable sheath is pressure-fitted into the outer cover, so that the outer cover may extend distally from the distal ends of the first polymer layer, braided layer, elastic layer, and second polymer layer in the overhang. The outer cover can be formed from a heat-shrinkable tube and / or an elastomer.

[0017] These methods may further include the step of crimping the expandable sheath to a third diameter smaller than the first and second diameters. In some embodiments, the method of crimping the expandable sheath includes the steps of supporting the inner surface of the entire length of the uncrimped sheath on an elongated mandrel having a conical end portion (the conical end portion is nested within the constricted lumen of the crimping mechanism), advancing the expandable sheath through the constricted lumen over the constricted lumen while the uncrimped portion is supported by the mandrel, and compressing the sheath to a third crimped diameter by pressure from the inner surface of the constricted lumen of the crimping piece. In some embodiments, the step of crimping an expandable sheath includes contacting the end of the sheath with a plurality of radially arranged disc-shaped rollers, advancing the sheath through the plurality of disc-shaped rollers, and compressing the sheath to a third crimped diameter by the pressure from the circular edges of each disc-shaped roller as the disc-shaped rollers roll along the outer surface of the sheath. In some embodiments, the step of crimping an expandable sheath includes applying a first heat shrink tube to the outer surface of the sheath, compressing the sheath by shrinking the first heat shrink tube to an intermediate diameter, removing the first heat shrink tube, applying a second heat shrink tube to the outer surface of the sheath, compressing the sheath by shrinking the second heat shrink tube to a diameter smaller than the intermediate diameter, and removing the second heat shrink tube. The sheath can be progressively shrunk by applying smaller and smaller heat shrink tubes until it is compressed to a third diameter.

[0018] Also, methods of forming laminate products are disclosed herein. These methods can include placing two or more material layers inside a container such that the two or more material layers are surrounded by a thermally expandable material. Some embodiments include heating the thermally expandable material within the container such that the thermally expandable material expands and applies heat and pressure to the two or more material layers to form a laminate product. These methods can further include positioning the two or more material layers on a mandrel.

[0019] Also, assemblies are disclosed herein. These assemblies can include an expandable sheath. The expandable sheath can further include a distal end portion that is elastically expandable between a first diameter and a second diameter. Some embodiments include a vascular dilator disposed within the sheath. The vascular dilator can include a tapered nose cone and a retaining member that at least partially extends over the distal end portion of the sheath and is configured to hold the distal end portion of the sheath at the first diameter. In some embodiments, the distal end portion is heat-cured into an expanded configuration and the elastic layer of the sheath terminates proximal to the distal end portion of the sheath. In some embodiments, the distal end portion of the braided layer is heat-cured into a flare configuration. In some embodiments, the retaining member is a polymeric heat shrink layer. In some embodiments, the retaining member is an elastomer and is configured to compress the distal end portion of the sheath. In some embodiments, the retaining member is adhered or welded to the sheath. In some embodiments, the retaining mechanism includes a shaft disposed between the dilator and the sheath. In some embodiments, the shaft includes a releasable coupling that can be mechanically engaged with both the dilator and the sheath and manually actuated to be released. In some embodiments, the retaining mechanism can include one or more balloons disposed between the dilator and the sheath.

[0020] Also, a method of delivering a medical device is disclosed herein. The method of delivering a medical device can include inserting an assembly into a blood vessel. The assembly can include a vascular dilator disposed within an expandable sheath. The vascular dilator can include a tapered nose cone. The expandable sheath can include a first polymer layer, a braided layer radially outward of the first polymer layer, an elastic layer radially outward of the braided layer, and a second polymer layer radially outward of the elastic layer. These methods can include withdrawing the vascular dilator through the sheath. These methods can include advancing a medical device having a maximum diameter up to three times greater than a first diameter of the sheath through the sheath. Further, these methods can include resisting axial elongation of the sheath so that the length of the sheath is maintained substantially constant as the medical device is advanced through the sheath. Also, these methods can include returning the sheath to the first diameter by a radial force applied by the elastic layer. In some embodiments, the step of inserting the assembly into the blood vessel can further include engaging the vascular dilator and the sheath by compressing a retaining member against the sheath. In some embodiments, the step of advancing the vascular dilator distally of the sheath can further include breaking an adhesive bond between the retaining member and the sheath. These methods can further include manually actuating a releasable coupling that mechanically engages both the dilator and the sheath prior to the step of advancing the vascular dilator distally of the sheath. These methods can further include contracting one or more balloons disposed between the dilator and the sheath prior to the step of advancing the vascular dilator distally of the sheath.

[0021] In some embodiments, the vasodilator may further include a retaining member configured to hold the distal end portion of the sheath to a first diameter. These methods may further include advancing the vasodilator distally to the sheath so that the retaining member releases the distal end portion of the sheath and the distal end portion of the sheath expands to a second diameter. In some embodiments, the step of inserting the assembly into the blood vessel may include engaging the vasodilator and the sheath by pressing the protruding portion of the outer cover of the sheath against the outer surface of the vasodilator. In some embodiments, the step of advancing the medical device through the sheath may include flattening ridges and grooves formed by a plurality of longitudinally extending folds. In some embodiments, the step of resisting axial elongation of the sheath may include straightening the buckled filaments of the braided layer.

[0022] Furthermore, a crimping mechanism is disclosed herein. The crimping mechanism may comprise a first end surface, a second end surface, and a longitudinal axis extending through the first and second end surfaces. The crimping mechanism may comprise a plurality of disc-shaped rollers arranged radially around the longitudinal axis. Each disc-shaped roller has a circular edge, a first side surface, a second side surface, and a central axis, the central axis extending between the center point of the first side surface and the center point of the second side surface, and the plurality of disc-shaped rollers are oriented such that the central axis of each disc-shaped roller extends perpendicular to the longitudinal axis of the crimping mechanism.

[0023] The crimping mechanism may include an axially extending passage that extends along the longitudinal axis of the crimping mechanism and is at least partially defined by the circular edges of a plurality of radially arranged disc-shaped rollers.

[0024] In some embodiments, each disc-shaped roller is at least partially positioned between the first and second end surfaces of the crimping mechanism. In some embodiments, each disc-shaped roller is held in a radial configuration by a plurality of radially positioned connectors, each mounted to the crimping mechanism. In some embodiments, each radially positioned connector comprises a first arm and a second arm extending across a selected disc-shaped roller from a circular edge to the central portion of the disc-shaped roller, and a bolt mounted to the first and second arms and extending between them, wherein the rod is positioned without being fixed within a lumen defined between the center points of the first and second side surfaces of the disc-shaped roller, thereby allowing the disc-shaped roller to rotate about its central axis. In some embodiments, each radially positioned connector is mounted to the crimping mechanism by one or more fasteners. In some embodiments, each disc-shaped roller is held in a radial configuration by a plurality of radially positioned connectors, and the position of each of the plurality of connectors is fixed to the first end surface of the crimping mechanism.

[0025] Furthermore, devices for crimping elongated sheaths are also included herein. A device for crimping an elongated sheath may comprise an elongated base and an elongated mandrel positioned above the elongated base. The elongated mandrel may have a conical end portion. The device for crimping an elongated sheath may further comprise a retaining mechanism mounted on the elongated base and supporting the elongated mandrel in an elevated position. The retaining mechanism may comprise a first end piece comprising a crimping mechanism. The crimping mechanism may comprise a constricted lumen opposite the conical end portion of the mandrel. The crimping mechanism may further comprise a second end piece, which is movable relative to the elongated base, thereby adjusting the distance between the first and second end pieces.

[0026] In some embodiments, the conical end portion of the mandrel is positioned on the conical end portion without being fixed within the constricted lumen of the first end piece to facilitate the passage of an elongated sheath through the constricted lumen. In some embodiments, the elongated base may comprise at least one elongated sliding track, and the second end piece is slidably engaged with at least one elongated sliding track by at least one reversible fastener. In some embodiments, the reversible fastener may comprise a bolt extending through the second end piece, the elongated sliding track, and the elongated base. In some embodiments, the mandrel may comprise a cylindrical end portion extending outward from the conical end portion, the cylindrical end portion defining the end of the mandrel. In some embodiments, the constricted lumen of the crimping mechanism may comprise a first tapered portion opening toward the second end piece of the instrument, the first tapered portion having a narrow end opening toward the cylindrical portion of the constricted lumen of the crimping mechanism. In some embodiments, the crimping lumen of the crimping mechanism may further comprise a second tapered portion that opens away from the second end piece and first tapered portion of the instrument, the second tapered portion having a narrow end that opens into the cylindrical portion of the crimping lumen of the crimping mechanism.

[0027] In some embodiments, the second polymer layer may extend longitudinally beyond the distal ends of the first polymer layer, the braided layer, and the elastic layer, thereby forming the distal end portion of the sheath. In some embodiments, this distal end portion may have multiple circumferential folds when the sheath is in a shrink configuration. Furthermore, in some embodiments, the distal end portion may comprise multiple polymer material layers. [Brief explanation of the drawing]

[0028] [Figure 1] This figure shows a delivery system for an artificial cardiovascular device according to one embodiment. [Figure 2] This figure shows an expandable sheath that can be used in combination with the delivery system shown in Figure 1, according to one embodiment. [Figure 3] Figure 2 is a magnified view of a portion of the expandable sheath. [Figure 4] Figure 2 is a lateral elevation cross-sectional view of a portion of the expandable sheath. [Figure 5A] This is an enlarged view of a portion of the expandable sheath shown in Figure 2, with the outer layer removed for illustrative purposes. [Figure 5B] Figure 2 is a magnified view of a portion of the braided layer of the sheath. [Figure 6] Figure 2 is a magnified view of a portion of the expandable sheath, showing the expansion of the sheath as the artificial device is advanced through it. [Figure 7] This is an enlarged partial cross-sectional view showing the constituent layers of the sheath shown in Figure 2, which is arranged on a mandrel. [Figure 8] This is an enlarged view showing another embodiment of the expandable sheath. [Figure 9] This is a cross-sectional view of an apparatus that may be used to form an expandable sheath according to one embodiment. [Figure 10A] This figure shows another embodiment of the braided layer, configured so that the filaments of the braided layer buckle when the sheath is in a radially contracted state. [Figure 10B] This figure shows another embodiment of the braided layer, configured so that the filaments of the braided layer buckle when the sheath is in a radially contracted state. [Figure 10C] This figure shows another embodiment of the braided layer, configured so that the filaments of the braided layer buckle when the sheath is in a radially contracted state. [Figure 10D] This figure shows another embodiment of the braided layer, configured so that the filaments of the braided layer buckle when the sheath is in a radially contracted state. [Figure 11] This is a lateral cross-sectional view of an assembly of an expandable sheath with a vasodilator. [Figure 12] Figure 11 shows a vascular dilator in an assembly embodiment. [Figure 13] This is a side view of another assembly embodiment comprising an expandable sheath and a vascular dilator. [Figure 14] This is a side view of the assembly embodiment shown in Figure 13, with the vasodilator pushed so as to be partially separated from the expandable sheath. [Figure 15] This is a side view of the assembly embodiment shown in Figure 13, with the vasodilator pushed so that it is completely detached from the expandable sheath. [Figure 16] This is a side view of the assembly embodiment shown in Figure 13, with the vasodilator retracted into the expandable sheath. [Figure 17] This is a side view of the assembly embodiment shown in Figure 13, with the vasodilator further retracted into the expandable sheath. [Figure 18] This is a side view of the assembly embodiment shown in Figure 13, with the vasodilator fully retracted into the expandable sheath. [Figure 19] This is a lateral cross-sectional view of another assembly embodiment comprising an expandable sheath and a vascular dilator. [Figure 20] This figure shows one embodiment of a vasodilator that may be used in combination with an expandable sheath as described herein. [Figure 21] This figure shows one embodiment of a vasodilator that may be used in combination with an expandable sheath as described herein. [Figure 22] This is a partially cutaway side view showing a partial cross-section of one embodiment of an expandable sheath having an outer cover and an overhang. [Figure 23] This figure shows an example embodiment of an outer cover having longitudinal grooves. [Figure 24] This figure shows the end portion of one embodiment of the braided layer of an expandable sheath. [Figure 25A] This is a perspective view of an embodiment of a roller-based crimping mechanism for crimping an expandable sheath. [Figure 25B] Figure 25A is a side view of the disc-shaped roller and connector of the crimping mechanism. [Figure 25C] Figure 25A is a top view of the disc-shaped roller and connector of the crimping mechanism shown. [Figure 26] This figure shows one embodiment of a device for crimping an elongated expandable sheath. The circled portion of this device is enlarged as an illustration on the left side of the figure. [Figure 27] This figure shows one embodiment of an expandable sheath having an inner layer with engraved lines. [Figure 28] This figure shows a further embodiment of the braided layer of the expandable sheath. [Figure 29] This is a perspective view of an embodiment of a further expandable sheath. [Figure 30] Figure 29 is a perspective view of the embodiment in which the outer heat shrink tube layer is partially cut away from the inner sheath layer. [Figure 31] This is a side view of the sheath embodiment before the delivery system is moved through it. [Figure 32] This is a side view of a sheath embodiment in which the heat shrink tubing layer has been split as the delivery system moves through it. [Figure 33] This is a side view of a sheath embodiment, in which the heat shrink tubing layer is completely split along the length of the sheath as the delivery system moves completely through it. [Figure 34] This is a perspective view of a sheath embodiment, with the distal end portion folded around the introducer. [Figure 35] This is a magnified cross-sectional view of the distal end portion folded around the introducer. [Modes for carrying out the invention]

[0029] The expandable introducer sheaths described herein may be used to deliver prosthetic devices through a patient's blood vessels to a procedure site in the body. The sheath may be configured to have high radial expandability and contractility while limiting axial elongation of the sheath and thus undesirable narrowing of the lumen. In one embodiment, the expandable sheath comprises a braided layer, one or more relatively thin inelastic polymer layers, and an elastic layer. The sheath is capable of elastically expanding from its original diameter to an expanded diameter as the prosthetic device is advanced through the sheath, and returning to its original diameter under the influence of the elastic layer after the prosthetic device has passed. In some embodiments, one or more polymer layers may be configured to engage with the braided layer, allowing for radial expansion of the braided layer while preventing axial elongation of the braided layer, which would otherwise result in elongation and narrowing of the sheath.

[0030] Figure 1 shows a typical delivery device 10 for delivering medical devices such as artificial heart valves or other artificial implants to a patient. This delivery device 10 is illustrative and may be used in combination with any embodiment of the expandable sheath described herein. Similarly, the sheaths described herein may be used in combination with any of the various known delivery devices. The illustrated delivery device 10 may generally comprise a maneuverable guide catheter 14 and a balloon catheter 16 extending through the guide catheter 14. An artificial device such as an artificial heart valve 12 may be positioned on the distal end of the balloon catheter 16. The guide catheter 14 and the balloon catheter 16 may be configured to slide longitudinally relative to each other to facilitate delivery and positioning of the artificial heart valve 12 at the implantation site in the patient's body. The guide catheter 14 comprises a handle portion 18 and an elongated guide tube or elongated guide shaft 20 extending from the handle portion 18.

[0031] The artificial heart valve 12 is delivered into the patient's body in a radially compressed configuration and can be radially expanded into a radially expanded configuration at a desired deployment site. In the illustrated embodiment, the artificial heart valve 12 is a plastically expandable artificial valve that is delivered into the patient's body in a radially compressed configuration on the balloon of a balloon catheter 16 (as shown in Figure 1) and then radially expanded into a radially expanded configuration at the deployment site by inflating the balloon (or by activating another type of expansion device of the delivery device). Further details regarding a plastically expandable heart valve that can be implanted using the device disclosed herein are disclosed in U.S. Patent Application Publication 2012 / 0123529, which is incorporated herein by reference. In other embodiments, the artificial heart valve 12 can be a self-expanding heart valve that is constrained in a radially compressed configuration by a sheath or other components of the delivery device and self-expands into a radially expanded configuration when released by the sheath or other components of the delivery device. Further details relating to a self-expanding heart valve that can be implanted using the devices disclosed herein are disclosed in U.S. Patent Application Publication 2012 / 0239142, which is incorporated herein by reference. In yet another embodiment, the artificial heart valve 12 may be a mechanically expandable heart valve comprising a plurality of struts connected by a hinge or pivot joint, and expandable from a radially compressed configuration to a radially expanded configuration by acting on an expansion mechanism that applies an expansion force to the artificial valve. Further details relating to a mechanically expandable heart valve that can be implanted using the devices disclosed herein are disclosed in U.S. Patent Application Publication 2018 / 0153689, which is incorporated herein by reference. In yet another embodiment, the artificial valve may incorporate two or more of the above-described technologies. For example, a self-expanding heart valve can be used in combination with an expansion device to assist in the expansion of the artificial heart valve.

[0032] Figure 2 shows an assembly 90 (which may also be called an introducer device or introducer assembly) that may be used to introduce a delivery device 10 and an artificial device 12 into the patient's body according to one embodiment. The introducer device 90 may comprise a housing 92 located at the proximal end of the device and an expandable sheath 100 extending distally from the housing 92. The housing 92 may function as a handle for the device. The expandable sheath 100 has a central lumen 112 (Figure 4) for guiding the passage of the delivery device for the artificial heart valve. Typically, during use, the distal end of the sheath 100 is delivered through the patient's skin and inserted into a blood vessel such as the femoral artery. The delivery device 10, together with its implant 12, can then be inserted through the housing 92 and sheath 100 and advanced through the patient's blood vessels to the treatment site, which is where the implant is to be delivered and implanted in the patient. In some embodiments, the introducer housing 92 may include a hemostatic valve that prevents leakage of pressurized blood by forming a seal around the outer surface of the guide catheter 14 when inserted into the housing.

[0033] In alternative embodiments, the introducer device 90 does not need to include a housing 92. For example, the sheath 100 can be an integral part of a component of the delivery device 10, such as a guide catheter. For example, the sheath may extend from the handle 18 of the guide catheter.

[0034] Figure 3 shows the expandable sheath 100 in more detail. Referring to Figure 3, the sheath 100 may have an intrinsic non-expanded outer diameter D1. In some embodiments, the expandable sheath 100 may comprise a plurality of coaxial layers extending along at least a portion of the sheath length L (Figure 2). For example, referring to Figure 4, the expandable sheath 100 may comprise a first layer 102 (also called an inner layer), a second layer 104 disposed around the first layer 102 and radially outward, a third layer 106 disposed around the second layer 104 and radially outward, and a fourth layer 108 (also called an outer layer) disposed around the third layer 106 and radially outward. In the illustrated configuration, the inner layer 102 may define the lumen 112 of the sheath extending along the central axis 114.

[0035] Referring to Figure 3, when the sheath 100 is in a non-expanded state, the inner layer 102 and / or outer layer 108 can form longitudinally extending folds or wrinkles, and the surface of the sheath has a plurality of ridges 126 (also referred to herein as “folds”). These ridges 126 can be spaced apart from each other circumferentially by longitudinally extending grooves 128. When the sheath expands beyond its original diameter D1, the ridges 126 and grooves 128 can be flattened or eliminated as the surface expands radially and the circumferential length increases, as will be further described below. When the sheath shrinks back to its original diameter, the ridges 126 and grooves 128 can be reformed.

[0036] In some embodiments, the inner layer 102 and / or outer layer 108 may comprise relatively thin polymer material layers. For example, in some embodiments, the thickness of the inner layer 102 can be between 0.01 mm and 0.5 mm, 0.02 mm and 0.4 mm, or 0.03 mm and 0.25 mm. In some embodiments, the thickness of the outer layer 108 can be between 0.01 mm and 0.5 mm, 0.02 mm and 0.4 mm, or 0.03 mm and 0.25 mm.

[0037] In some embodiments, the inner layer 102 and / or outer layer 108 may include smooth materials, low-friction materials, and / or relatively inelastic materials. In certain embodiments, the inner layer 102 and / or outer layer 108 may include polymer materials having an elastic modulus of 400 MPa or greater. Examples of materials may include ultra-high molecular weight polyethylene (UHMWPE) (e.g., Dyneema®), high molecular weight polyethylene (HMWPE), or polyether ether ketone (PEEK). With respect to the inner layer 102 in particular, such low-friction materials may facilitate the passage of artificial devices through the lumen 112. Other suitable materials for the inner and outer layers may include polytetrafluoroethylene (PTFE), stretched polytetrafluoroethylene (ePTFE), ethylene tetrafluoroethylene (ETFE), nylon, polyethylene, polyether block amide (e.g., Pebax), and / or any combination of the above. Some embodiments of the sheath 100 may be provided with a lubricating liner on the inner surface of the inner layer 102. Examples of suitable lubricating liners include materials that can further reduce the coefficient of friction of the inner layer 102, such as PTFE, polyethylene, polyvinylidene fluoride, and combinations thereof. Other suitable materials for the lubricating liner may preferably have a coefficient of friction of 0.1 or less.

[0038] Furthermore, some embodiments of the sheath 100 may be provided with an external hydrophilic coating on the outer surface of the outer layer 108. Such a hydrophilic coating may facilitate insertion of the sheath 100 into the patient's blood vessels and reduce the likelihood of injury. Examples of suitable hydrophilic coatings include Harmony® Advanced Lubricity Coatings and other Advanced Hydrophilic Coatings, available from SurModics, Inc., Eden Prairie, MN. DSM medical coatings (available from Koninklijke DSM NV, Heerlen, the Netherlands) and other hydrophilic coatings (e.g., PTFE, polyethylene, polyvinylidene fluoride) are also suitable for use with the sheath 100. Such a hydrophilic coating may also be included on the inner surface of the inner layer 102 to facilitate use and improve safety by reducing friction between the sheath and the delivery system. In some embodiments, a hydrophobic coating such as perylene may be used on the outer surface of the outer layer 108 or on the inner surface of the inner layer 102 to reduce friction.

[0039] In some embodiments, the second layer 104 can be a braided layer. Figures 5A and 5B show the sheath 100 with the outer layer 108 removed to expose the elastic layer 106. Referring to Figures 5A and 5B, the braided layer 104 may comprise a plurality of braided members or filaments 110 (e.g., metal or synthetic wire or fiber). The braided layer 104 can have any desired number of filaments 110, which can be oriented and braided along any suitable number of axes. For example, referring to Figure 5B, the filaments 110 may comprise a first set of filaments 110A oriented parallel to a first axis A, and a second set of filaments 110B oriented parallel to a second axis B. These filaments 110A and 110B can be braided together as a biaxial braid such that the filaments oriented along axis A form an angle θ between the filaments 110A oriented along axis B and the filaments 110B oriented along axis B. In some embodiments, the angle θ can be between 5° and 70°, 10° and 60°, 10° and 50°, or 10° and 45°. In the illustrated embodiment, the angle θ is 45°. In other embodiments, the filaments 110 can be oriented along three axes and braided as a triaxial braid, or oriented along any number of axes and braided in any suitable braid pattern.

[0040] The braided layer 104 may extend substantially along the entire length L of the sheath 100, or alternatively, along only a portion of the length of the sheath. In certain embodiments, the filament 110 can be a wire made from metal (e.g., nitinol, stainless steel, etc.) or any various polymer or polymer composite material such as carbon fiber. In some embodiments, the filament 110 is circular and may have a diameter between 0.01 mm and 0.5 mm, 0.03 mm and 0.4 mm, or 0.05 mm and 0.25 mm. In other embodiments, the filament 110 may have a flat cross-section with dimensions between 0.01 mm × 0.01 mm to 0.5 mm × 0.5 mm, or 0.05 mm × 0.05 mm to 0.25 mm × 0.25 mm. In one embodiment, the filament 110 with a flat cross-section may have dimensions of 0.1 mm × 0.2 mm. However, other shapes and sizes are also suitable for some embodiments. When braided wire is used, various braiding densities are possible. Some embodiments have braiding densities from 10 picks / inch to 80 picks / inch and can feature 8 wires, 16 wires, or up to 52 wires in various braiding patterns. In other embodiments, the second layer 104 can be formed by laser cutting of a tube, or by laser cutting, pressing, punching, etc., of a sheet material and winding it into a tubular structure. The layer 104 can also be woven or knitted as desired.

[0041] The third layer 106 can be an elastic layer (also called an elastic material layer). In some embodiments, the elastic layer 106 may be configured to apply a radial force (for example, toward the central axis 114 of the sheath) to the layers below 102 and 104 when the sheath expands beyond its original diameter as the delivery device passes through it. In other words, the elastic layer 106 may be configured to counteract the expansion of the sheath by applying an encircling pressure to the layers of the sheath below the elastic layer 106. This radial inward force is sufficient to cause the sheath to contract radially back to its unexpanded state after the delivery device has passed through it.

[0042] In the illustrated embodiment, the elastic layer 106 may comprise one or more members configured as strands, ribbons, or bands 116 helically wound around the braided layer 104. For example, in the illustrated embodiment, the elastic layer 106 comprises two elastic bands 116A and 116B helically wound in opposite directions around the braided layer, but these elastic layers may comprise any number of bands depending on the desired characteristics. The elastic bands 116A and 116B may be made from any natural or synthetic elastomer, including, for example, silicone rubber, natural rubber, any various thermoplastic elastomers, polyurethanes such as polyurethane siloxane copolymers, urethanes, plasticized polyvinyl chloride (PVC), styrene block copolymers, polyolefin elastomers, etc. In some embodiments, the elastic layer may comprise an elastomer material having an elastic modulus of 200 MPa or less. In some embodiments, the elastic layer 106 may comprise a material exhibiting elongation at break of 200% or more or 400% or more. Furthermore, the elastic layer 106 may take other forms, such as a tubular layer containing an elastic material, a mesh, or a shrinkable polymer layer such as a heat-shrinkable tube layer. Alternatively, instead of or in addition to the elastic layer 106, the sheath 100 may have an elastomer layer or a heat-shrinkable tube layer around the outer layer 108. Examples of such elastomer layers are disclosed in U.S. Patent Application Publication 2014 / 0379067, U.S. Patent Application Publication 2016 / 0296730, and U.S. Patent Application Publication 2018 / 0008407, which are incorporated herein by reference. In other embodiments, the elastic layer 106 may be radially outward of the polymer layer 108.

[0043] In some embodiments, one or both of the inner layer 102 and / or outer layer 108 may be configured to resist axial stretching of the sheath 100 during sheath expansion. More specifically, one or both of the inner layer 102 and / or outer layer 108 may resist stretching against longitudinal forces caused by friction between the prosthetic device and the inner surface of the sheath, thereby keeping the length L substantially constant during sheath expansion and contraction. Where the length L of the sheath is used herein by reference, the term “substantially constant” means that the length L of the sheath increases by only 1%, 5%, 10%, 15%, or 20% or less. On the other hand, referring to Figure 5B, the filaments 110A and 110B of the braided layer may be able to move angularly relative to each other such that the angle θ changes during sheath expansion and contraction. This, combined with the longitudinal folds 126 of layers 102 and 108, may allow for expansion of the lumen 112 of the sheath as the artificial device is advanced through the sheath.

[0044] For example, in some embodiments, the inner layer 102 and the outer layer 108 can be heat-bonded during the manufacturing process such that the braided layer 104 and the elastic layer 106 are encased between layers 102 and 108. More specifically, in some embodiments, the inner layer 102 and the outer layer 108 can be bonded to each other through the spaces between the filaments 110 of the braided layer 104 and / or the spaces between the elastic bands 116. Alternatively, layers 102 and 108 can be joined or bonded together at the proximal and / or distal ends of the sheath. In some embodiments, layers 102 and 108 are not mounted on the filaments 110. This allows the filaments 110 to move angularly relative to each other and to layers 102 and 108, thereby increasing or decreasing the diameter of the braided layer 104 and therefore the diameter of the sheath. As the angle θ between filaments 110A and 110B changes, the length of the braided layer 104 may also change. For example, as the angle θ increases, the braided layer 104 shortens, and as the angle θ decreases, the braided layer 104 can stretch to an extent permitted by the region where layers 102 and 108 are joined. However, because the braided layer 104 is not bonded to layers 102 and 108, even if the length of the braided layer changes with a change in the angle θ between filaments 110A and 110B, no significant change in the sheath length L occurs as a result.

[0045] Figure 6 shows the radial expansion of the sheath 100 as the prosthetic device 12 passes through the sheath in the direction of the arrow 132 (e.g., distally). As the prosthetic device 12 advances through the sheath 100, the sheath may elastically expand to a second diameter D2 corresponding to the size or diameter of the prosthetic device. As the prosthetic device 12 advances through the sheath 100, the prosthetic device may exert a longitudinal force on the sheath in the direction of movement due to frictional contact between the prosthetic device and the inner surface of the sheath. However, as described above, the inner layer 102 and / or outer layer 108 may resist axial elongation such that the length L of the sheath remains constant or substantially constant. This can reduce or prevent the elongation of the braided layer 104 and, therefore, the compression of the lumen 112.

[0046] On the other hand, the angle θ between filaments 110A and 110B may increase as the sheath expands to a second diameter D2 to accommodate the artificial valve. This may shorten the braided layer 104. However, because filaments 110 do not engage with or adhere to layer 102 or 108, the shortening of the braided layer 104 with an increase in angle θ does not affect the overall length L of the sheath. Furthermore, the longitudinally extending folds 126 formed in layers 102 and 108 allow layers 102 and 108 to expand to a second diameter D2 without tearing, instead of becoming relatively thin and relatively inelastic. In this way, the sheath 100 can elastically expand from its original diameter D1 to a second diameter D2 greater than diameter D1 without stretching and compression as the artificial device is advanced through the sheath. Thus, the force required to push the artificial implant through the sheath is significantly reduced.

[0047] Furthermore, the radial force applied by the elastic layer 106 can localize the radial expansion of the sheath 100 to a specific portion of the sheath occupied by the prosthetic device. For example, referring to Figure 6, as the prosthetic device 12 is moved distally through the sheath, the portion of the sheath immediately proximal to the prosthetic device 12 may radially contract back to its initial diameter D1 under the influence of the elastic layer 106. Also, layers 102 and 108 may buckle as the circumference of the sheath decreases, reforming the ridge 126 and groove 128. This allows for a reduction in the size of the sheath required to introduce a prosthetic device of a given size. Moreover, the temporary and localized nature of the expansion can reduce trauma to the blood vessel and surrounding tissue into which the sheath is inserted, because the portion of the sheath occupied by the prosthetic device expands beyond the sheath's original diameter, and the sheath contracts back to its initial diameter after the device has passed. This limits the amount of tissue that must be stretched for the introduction of the artificial device and the amount of time that a given portion of the blood vessel must be expanded.

[0048] In addition to the advantages described above, the embodiments of expandable sheaths described herein can deliver performance that is remarkably superior to known introducer sheaths. For example, sheaths configured as described herein can be used to deliver prosthetic devices having a diameter that is twice, 2.5 times, or even three times the sheath's original outer diameter. For example, in one embodiment, a crimped prosthetic heart valve having a diameter of 7.2 mm was successfully advanced through a sheath configured as described above with an original outer diameter of 3.7 mm. As the prosthetic valve advanced through the sheath, the outer diameter of the portion of the sheath occupied by the prosthetic valve expanded to 8 mm. In other words, it is possible to advance a prosthetic device with a diameter more than twice the sheath's outer diameter through this sheath, during which the sheath's outer diameter elastically expanded by 216%. In another example, a sheath with an initial or original outer diameter of 4.5 mm to 5 mm can be configured to expand to an outer diameter of 8 mm to 9 mm.

[0049] In an alternative embodiment, the sheath 100 may optionally have layer 102 without layer 108, or layer 108 without layer 102, depending on the desired specific features.

[0050] Figures 10A to 10D show another embodiment of the braided layer 104 configured to buckle the filament 110. For example, Figure 10A shows a unit cell 134 of the braided layer 104 in a configuration corresponding to the braided layer in a fully expanded state. For example, the expanded state shown in Figure 10A may correspond to the diameter D2 described above, and / or the diameter of the braided layer while the sheath 100 is in its initial configuration before the sheath contracts radially to its functional design diameter D1, as further described below with reference to Figure 7. The angle θ between filament 110A and filament 110B can be, for example, 40°, and the unit cell 134 has a length L along the x-direction. x It is possible to have (note the Cartesian coordinate axes shown in the figure). Figure 10B shows a portion of the braided layer 104 having an array of unit cells 134 in an expanded state.

[0051] In the illustrated embodiment, the braided layer 104 is disposed between the polymer layer 102 and the polymer layer 108 as described above. For example, the polymer layers 102 and 108 can be bonded or laminated to each other at the end of the sheath 100 and / or between the filaments 110 in the open space 136 defined by the unit cell 134. Thus, referring to Figures 10C and 10D, when the sheath 100 shrinks radially to its functional diameter D1, the diameter of the braided layer 104 may shrink as the angle θ decreases. However, the bonded polymer layers 102 and 108 can suppress or prevent the braided layer 104 from stretching as it shrinks radially. This allows the filaments 110 to buckle elastically in the axial direction, as shown in Figures 10C and 10D. The degree of buckling is determined by the length L of the unit cell 134. x However, it is possible for the sheath's contracted diameter and fully expanded diameter to be the same or substantially the same. This means that the total length of the braided layer 104 can be kept constant or substantially constant between the sheath's original diameter D1 and its expanded diameter D2. As the sheath expands from its initial diameter D1 during the passage of the medical device, the filament 110 can be straightened by releasing its buckling, allowing the sheath to expand radially. Once the medical device has passed through the sheath, the braided layer 104 is returned to its initial diameter D1 by the elastic layer 106, and the filament 110 can again elastically buckle. When using the configurations shown in Figures 10A to 10C, it is also possible to accommodate artificial valves with diameters twice, 2.5, or even three times larger than the sheath's original diameter D1.

[0052] Next, moving on to the method for fabricating the expandable sheath, Figure 7 shows layers 102-108 of the expandable sheath 100 disposed on a cylindrical mandrel 118 according to one embodiment. In some embodiments, the mandrel 118 may have a diameter D3 that is larger than the desired original outer diameter D1 of the finished sheath. For example, in some embodiments, the ratio of the mandrel diameter D3 to the outer diameter D1 of the sheath can be 1.5:1, 2:1, 2.5:1, 3:1, or greater. In some embodiments, the mandrel diameter D3 can be equivalent to the expanded diameter D2 of the sheath. In other words, the mandrel diameter D3 can be the same as or approximately the same as the desired expanded diameter D2 of the sheath when the artificial device is advanced through the sheath. Therefore, in some embodiments, the ratio of the expanded outer diameter D2 of the sheath to the contracted outer diameter D1 of the sheath when not expanded can be 1.5:1, 2:1, 2.5:1, 3:1, or greater.

[0053] Referring to Figure 7, the expandable sheath 100 can be manufactured by winding or placing an ePTFE layer 120 around a mandrel 118, followed by a first polymer layer 102. In some embodiments, the ePTFE layer can assist in the removal of the sheath 100 from the mandrel 118 at the completion of the assembly process. The first polymer layer 102 may be in the form of a prefabricated sheet applied by winding around the mandrel 118, or it may be applied to the mandrel by dipping, electrospinning, etc. A braided layer 104 may be placed around the first layer 102, followed by an elastic layer 106. In embodiments where the elastic layer 106 comprises one or more elastic bands 116, these bands 116 may be helically wound around the braided layer 104. In other embodiments, the elastic layer 106 may be made by dipping, electrospinning, etc. Next, the outer polymer layer 108 is wrapped around or applied to the elastic layer 106, after which another ePTFE layer 122 and one or more heat shrink tube layers or heat shrink tape layers 124 may be provided.

[0054] In certain embodiments, the elastic band 116 may be applied to the braided layer 104 in a stretched, taut, or elongated state. For example, in some embodiments, the band 116 may be applied to the braided layer 104 stretched to twice its original relaxed length. This allows the finished sheath to contract radially under the influence of the elastic layer when removed from the mandrel, thereby allowing the elastic layer to relax accordingly, as described below. In other embodiments, the layer 102 and the braided layer 104 can be removed from the mandrel, the elastic layer 106 may be applied in a relaxed or moderately stretched state, and this assembly may then be placed back on the mandrel so that the elastic layer is radially expanded and stretched to a taut state before the outer layer 108 is applied.

[0055] Next, the assembly may be heated to a temperature high enough to cause the heat shrink layer 124 to shrink and compress layers 102-108 together. In some embodiments, the assembly may be heated to a temperature high enough to cause the polymer inner layer 102 and polymer outer layer 108 to become flexible and tacky, bonding to each other in the open space between the braided layer 104 and the elastic layer 106, and enveloping the braided layer and the elastic layer. In other embodiments, the inner layer 102 and outer layer 108 may be reflowed or melted so that they flow around and through the braided layer 104 and the elastic layer 106. In one exemplary embodiment, the assembly may be heated at 150°C for 20-30 minutes.

[0056] After heating, the sheath 100 can be removed from the mandrel 118, and the heat shrink tube 124 and ePTFE layers 120 and 122 can be removed. Once removed from the mandrel 118, the sheath 100 can shrink at least partially radially to its original design diameter D1 under the influence of the elastic layer 106. In some embodiments, the sheath can optionally shrink radially to the design diameter with the assistance of a crimping mechanism. Due to the resulting reduction in circumference, the filament 110 can buckle together with the inner layer 102 and outer layer 108 to form a longitudinally extending fold 126, as shown in Figures 10C and 10D.

[0057] In some embodiments, PTFE layers may be placed between the ePTFE layer 120 and the inner layer 102 and / or between the outer layer 108 and the ePTFE layer 122 to facilitate the separation of the inner polymer layer 102 and the outer polymer layer 108 from the ePTFE layers 120 and 122, respectively. In further embodiments, one of the inner layer 102 and the outer layer 108 may be omitted as described above.

[0058] Figure 8 shows another embodiment of the expandable sheath 100, comprising one or more members configured as threads or cords 130 that extend longitudinally along the sheath and are attached to the braided layer 104. Although only one cord 130 is illustrated in Figure 8, in practice the sheath may comprise two, four, six, or the like cords arranged along the periphery of the sheath at equal angular gaps. These cords 130 may be sutured to the outside of the braided layer 104, but other configurations and attachment methods are also possible. By being attached to the braided layer 104, the cords 130 may be configured to prevent axial stretching of the braided layer 104 as the prosthetic device passes through the sheath. The cords 130 may be used in combination with or separately from the elastic layer 106. The cords 130 may also be used in combination with one or both of the inner layer 102 and / or outer layer 108, depending on the desired specific characteristics. Additionally, the code 130 may be placed on top of the inside of the braided layer 104 (for example, between the inner layer 102 and the braided layer 104).

[0059] Furthermore, the expandable sheath 100 can be manufactured by other means. For example, Figure 9 shows a device 200 comprising a heating system schematically illustrated in containment containers 202 and 214. The device 200 is particularly suitable for forming devices (medical devices or devices for non-medical applications) consisting of two or more material layers. Devices formed by the device 200 may be formed from two or more coaxial material layers, such as the sheath 100, or from a shaft for a catheter. Alternatively, devices formed by the device 200 may be formed from two or more non-coaxial layers, such as two or more layers stacked on top of each other.

[0060] The containment container 202 may define an internal volume or chamber 204. In the illustrated embodiment, the container 202 may be a metal tube having a closed end 206 and an open end 208. The container 202 may be at least partially filled with a thermally expandable material 210 having a relatively high coefficient of thermal expansion. In certain embodiments, the thermally expandable material 210 may have a coefficient of thermal expansion of 2.4 × 10 -4 It may have a thermal expansion coefficient of 5.9 × 10°C or higher. Examples of thermally expandable materials include elastomers such as silicone materials. Silicone materials have a thermal expansion coefficient of 5.9 × 10°C. -4 / ℃~7.9×10 -4 It is possible to have a thermal expansion coefficient between / °C.

[0061] A mandrel similar to the mandrel 118 in Figure 7, and having layers of sheath material of a desired combination arranged around it, can be inserted into the thermally expandable material 210. Alternatively, the mandrel 118 can be inserted into the chamber 204, and the remaining volume of the chamber can be filled with the thermally expandable material 210 so that the mandrel is surrounded by the material 210. The mandrel 118 is schematically illustrated for illustrative purposes. Thus, the mandrel 118 can be cylindrical, as shown in Figure 7. Similarly, the inner surface of the material 210 and the inner surface of the container 202 can have a cylindrical shape corresponding to the shape of the mandrel 118 and the final shape of the sheath 100. To facilitate the placement of a cylindrical or circular mandrel 118, the container 202 may comprise two parts connected to each other by a hinge, which allows these two parts to move between an open configuration for positioning the mandrel inside the container and a closed configuration extending around the mandrel. For example, the upper and lower halves of the container shown in Figure 9 may be connected to each other by a hinge located on the closed side of the container (the left side of the container in Figure 9).

[0062] The open end 208 of the container 202 can be closed with a cap 212. The container 202 can then be heated by a heating system 214. Heating by the heating system 214 expands the material 210 within the chamber 204, applying radial pressure to the material layers on the mandrel 118. This combination of heat and pressure can cause the layers on the mandrel 118 to bond or adhere to each other to form a sheath. In some embodiments, it is possible to apply a radial pressure of 100 MPa or more to the mandrel 118 using the apparatus 200. The amount of radial pressure applied to the mandrel can be controlled by, for example, the type, quality, and thermal expansion coefficient of the selected material 210, the thickness of the material 210 surrounding the mandrel 118, and the temperature at which the material 210 is heated.

[0063] In some embodiments, the heating system 214 can be an oven in which a container 202 is placed. In some embodiments, the heating system may comprise one or more heating elements positioned around the container 202. In some embodiments, the container 202 can be an electrical resistance heating element or an induction heating element controlled by the heating system 214. In some embodiments, the heating elements may be embedded within a thermally expandable material 210. In some embodiments, the material 210 may be configured as a heating element by adding conductive filler material, such as carbon fibers or metal particles.

[0064] The apparatus 200 may offer several advantages over known sheath manufacturing methods, including the application of a uniform radial force with high controllability along the longitudinal direction of the mandrel 118 and high repeatability. Furthermore, the apparatus 200 may enable reductions in material costs and labor by facilitating the rapid and precise heating of the thermally expandable material 210, thereby reducing or eliminating the need for heat shrink tubing and / or heat shrink tape. The amount of radial force applied can also be varied along the longitudinal direction of the mandrel, for example, by changing the type or thickness of the surrounding material 210. In some embodiments, multiple vessels 202 can be processed within a single fixture, and / or multiple sheaths can be fabricated within a single vessel 202. The apparatus 200 may also be used to fabricate other devices, such as shafts or catheters.

[0065] In one specific method, the sheath 100 may be formed by placing layers 102, 104, 106, and 108 on a mandrel 118, with the thermally expandable material 210 surrounding the outermost layer 108, and then placing this mandrel with these layers inside a container 202. Optionally, one or more inner layers 120 of ePTFE (or similar material) and one or more outer layers 122 of ePTFE (or similar material) may be used to facilitate the removal of the finished sheath from the mandrel 118 and material 210 (as shown in Figure 7). The assembly is then heated in a heating system 214 to reflow layers 102 and 108. After subsequent cooling, these layers 102 and 108 are at least partially bonded to each other and at least partially encase layers 104 and 106.

[0066] Figure 11 shows another embodiment in which the expandable sheath 100 is configured to receive a device configured as a plain introducer or vasodilator 300. In certain embodiments, the introducer device 90 may include a vasodilator 300. Referring to Figure 12, the vasodilator 300 may include a shaft member 302, which includes a tapered expander configured as a nose cone 304 located at the distal end portion of the shaft member 302. The vasodilator 300 may further include a capsule or retaining member 306 extending proximal from the proximal end portion 308 of the nose cone 304, with a circumferential space 310 defined between the outer surface of the shaft member 302 and the inner surface of the retaining member 306. In some embodiments, the retaining member 306 may be configured as a thin polymer layer or polymer sheet, as will be further described below.

[0067] Referring to Figures 11 and 13, the first end portion or distal end portion 140 of the sheath 100 may be received within the space 310 such that the sheath engages with the nose cone 304 and / or the retaining member 306 extends beyond the distal end portion 140 of the sheath. In use, the combined or assembled vascular dilator 300 and sheath 100 can be inserted into the blood vessel through the incision. The tapered cone shape of the nose cone 304 helps to minimize trauma to the blood vessel and surrounding tissue while assisting in the gradual dilation of the blood vessel and access site. Once the assembly has been inserted to the desired depth, the vascular dilator 300 can be advanced further into the blood vessel (e.g., distally) with the sheath 100 held in a stable position, as shown in Figure 14.

[0068] Referring to Figure 15, the vasodilator 300 can be advanced distally through the sheath 100 until the retaining member 306 is removed from the distal end portion 140 of the sheath 100. In some embodiments, the helically wound elastic layer 106 of the sheath may terminate proximal to the distal end portion 142 of the sheath. Thus, when the distal end portion 140 of the sheath is not covered, this distal end portion (which may be thermosetting) can flare out or expand, increasing the diameter of the opening at the distal end 142 from a first diameter D1 (Figure 13) to a second, larger diameter D2 (Figure 15). The vasodilator 300 can then be pulled back through the sheath 100, as shown in Figures 16 to 18, leaving the sheath 100 in place within the blood vessel.

[0069] The vasodilator 300 may be equipped with various active and / or passive mechanisms for engaging with and retaining the sheath 100. For example, in some embodiments, the retaining member 306 may be equipped with a polymer heat-shrinkable layer that can be contracted around the distal end portion of the sheath 100. In the embodiment shown in Figure 1, the retaining member may be equipped with an elastic member configured to compress the distal end portion 140 of the sheath 100. In yet another embodiment, the retaining member 306 and the sheath 100 may be bonded or welded (e.g., heat-bonded) together in such a manner that the adhesive bond between the retaining member 306 and the sheath 100 can be broken by the application of a selected amount of force, thereby allowing the vasodilator to be withdrawn. In some embodiments, the end portions of the braided layer 104 may be heat-cured so that pressure is applied to the corresponding portion of the vasodilator 300 by flaring out or expanding radially inward or outward.

[0070] Referring to Figure 19, the assembly may include a mechanically operated retaining mechanism, such as a shaft 312 disposed between the dilator shaft member 302 and the sheath 100. In some embodiments, the shaft 312 can be detachably coupled to the sheath 100, and can be operated from outside the body (i.e., can be manually deactivated).

[0071] Referring to Figures 20 and 21, in some embodiments, the shaft member 302 may comprise one or more balloons 314, which are arranged circumferentially along the outer surface and configured to engage with the sheath 100 when inflated. The balloons 314 can be selectively deflated to remove the sheath 100 and withdraw the vasodilator. For example, when inflated, the balloons compress the captured distal end portion of the sheath 100 against the inner surface of the capsule 306, helping to hold the sheath in place relative to the vasodilator. When the balloons are deflated, the vasodilator can be moved more easily relative to the sheath 100.

[0072] In another embodiment, the expandable sheath configured as described above may further comprise a shrinkable polymer outer cover, such as a heat-shrinkable tubing layer 400 shown in Figure 22. The heat-shrinkable tubing layer 400 may be configured to allow a smooth transition between the vascular dilator 300 and the distal end portion 140 of the sheath. The heat-shrinkable tubing layer 400 may also constrain the sheath to a selected initial small outer diameter. In some embodiments, the heat-shrinkable tubing layer 400 extends fully over the length of the sheath 100 and may be attached to the sheath handle by mechanical fastening means such as clamps, nuts, adhesives, thermal welding, laser welding, or elastic clamps. In some embodiments, the sheath is pressure-fitted into the heat-shrinkable tubing layer during manufacturing.

[0073] In some embodiments, the heat-shrinkable tubing layer 400 may extend distally beyond the distal end portion 140 of the sheath as a distal overhang 408, as shown in Figure 22. A vascular dilator can be inserted through the sheath membrane 112 and beyond the distal edge of the overhang 408. The overhang 408 conforms tightly to the vascular dilator being inserted to facilitate the insertion of the dilator-sheath combination by providing a smooth transition between the diameter of the dilator and the diameter of the sheath. Once the vascular dilator is removed, the overhang 408 remains in the vessel as part of the sheath 100. The heat-shrinkable tubing layer 400 offers the further advantage of shrinking the entire outer diameter of the sheath along its longitudinal axis.

[0074] In some embodiments, the heat shrink tubing layer may be configured to crack open as a delivery device, such as the delivery device 10, advances through the sheath. For example, in some embodiments, the heat shrink tubing layer may have one or more longitudinally extending openings, slits, or brittle elongated grooves 406, such as those shown in Figure 22, configured to initiate cracking of the layer at a selected position. As the delivery device 10 advances through the sheath, the heat shrink tubing layer 400 continues to crack open, thereby allowing the sheath to expand with little force as described above. In some embodiments, the sheath does not need to have an elastic layer 106 so as to automatically expand from its initial reduced diameter when the heat shrink tubing layer cracks open. The heat shrink tubing layer 400 may include polyethylene or other suitable material.

[0075] Figure 23 shows a heat-shrinkable tube layer 400 that may be positioned around the expandable sheath described herein, according to one embodiment. In some embodiments, the heat-shrinkable tube layer 400 may have a plurality of cuts or grooves 402, which extend axially along the tube layer 400 and terminate at distal stress relief features configured as circular openings 404. It is also expected that the distal stress relief features may be configured as any other regular or irregular curved shapes, such as elliptical and / or oval openings. Furthermore, distal stress relief features of various shapes along and around the heat-shrinkable tube layer 400 are also expected. As the delivery device 10 advances through the sheath, the heat-shrinkable tube layer 400 can be split and opened along the grooves 402, and the distally positioned openings 404 can prevent further splitting or cracking of the tube layer along each groove. Therefore, the heat shrink tubing layer 400 remains attached to the sheath along the length of the sheath. In the illustrated embodiment, the grooves and associated openings 404 are offset from each other longitudinally and circumferentially, or arranged in a staggered pattern. Thus, as the sheath expands, the grooves 402 can form a rhomboid structure. The grooves can also extend in other directions, such as helically around the longitudinal axis of the sheath, or in a zigzag pattern.

[0076] In other embodiments, cracking or splitting of the heat-shrinkable tube layer may be induced by various other means, such as forming a weak region on the tube surface, for example by applying a chemical solvent, cutting, carving, or ablating the surface with an instrument or laser, and / or by reducing the wall thickness or forming cracks in the tube wall (for example by femtosecond laser ablation).

[0077] In some embodiments, the heat shrink tubing layer may be attached to the sheath body by adhesive, welding, or any suitable fastening means. Figure 29 shows a perspective view of a sheath embodiment comprising an inner layer 802, a braided layer 804, an elastic layer 806, an outer layer 808, and a heat shrink tubing layer 809. The heat shrink tubing layer 809 comprises a crack 811 and a perforation 813 extending along the heat shrink tubing layer 809. The heat shrink tubing layer 809 is bonded to the outer layer 808 at an adhesive seam 815. For example, in some embodiments, the heat shrink tubing layer 809 can be bonded by welding, thermal bonding, chemical bonding, ultrasonic bonding, and / or the use of adhesives (including, but not limited to, thermal adhesives such as LDPE fiber thermal adhesive) at the seam 815. The outer layer 808 may be bonded to the heat shrink tubing layer 809 axially or helically along the sheath at the seam 815. Figure 30 shows the sheath with the heat shrink tubing layer 809 before the delivery system passes through and moves along it. Figure 32 shows a perspective view of the sheath, where the heat shrink tubing layer 809 is partially ripped open and undone as the delivery system expands the diameter of the sheath during passage. The heat shrink tubing layer 809 is held in place by the adhesive seam 815. By attaching the heat shrink tubing layer 809 to the sheath in this way, it is possible to help maintain the heat shrink tubing layer 809 attached to the sheath after the layer has ripped and the sheath has expanded, as shown in Figure 33, where the delivery system 817 moves through the entire sheath, ripping the heat shrink tubing layer 809 along the entire length of the sheath.

[0078] In another embodiment, the expandable sheath may have a distal end or distal tip portion comprising an elastic thermoplastic material (e.g., Pebax), which may be configured to provide an interlocking fit or interference fit shape with a corresponding portion of the vascular dilator 300. In some embodiments, the outer layer of the sheath may contain polyamide (e.g., nylon) to allow the distal end portion to be welded to the body of the sheath. In some embodiments, the distal end portion may have intentionally weakened sections, grooves, slits, etc., to allow the distal end portion to crack open as the delivery device is advanced through the distal end portion.

[0079] In another embodiment, the entire sheath may have an elastomer outer cover extending longitudinally from the handle to the distal end portion 140 of the sheath, which extends outward to form a protrusion similar to the protrusion 408 shown in Figure 22. This elastomer protrusion tightly conforms to the shape of the vascular dilator but remains as part of the sheath when the vascular dilator is removed. As the delivery system passes, the elastomer protrusion expands and then contracts to allow the delivery system to pass through. The elastomer protrusion or the entire elastomer outer cover may have intentionally weakened portions, grooves, slits, etc., so that the distal end portion may split open as the delivery device is advanced past the distal end portion.

[0080] Figure 24 shows an end portion (e.g., a distal end portion) of another embodiment of a braided layer 104 where portions 150 of the braided filaments 110 are bent to form loops 152, and these filaments loop or extend back in the opposite direction along the sheath. The filaments 110 may be arranged such that the loops 152 of the various filaments 110 are axially offset from one another in the braid. The number of braided filaments 110 may decrease as we move toward the distal end (to the right in the drawing). For example, the filament indicated by 5 may first form a loop 152, followed by the filaments indicated by 4, 3, and 2, and the filament 1 may form the most distal loop 152. Thus, the number of filaments 110 in the braid decreases toward the distal direction, which may increase the radial flexibility of the braided layer 104.

[0081] In another embodiment, the distal end portion of the expandable sheath may contain a polymer such as Dyneema®, which may be tapered relative to the diameter of the vascular dilator 300. Bridging portions, such as dashed cuts or engraved lines, may be applied to the distal end portion to allow it to crack open and / or expand in a repeatable manner.

[0082] The crimping of the expandable sheath embodiments described herein can be carried out in various ways as described above. In further embodiments, the sheath can be crimped by using a conventional short crimper multiple times longitudinally along a longer sheath. In other embodiments, the sheath can be shrunk to a specified crimp diameter in one or a series of steps in which the sheath is surrounded within a heat shrink tubing and shrunk under heat. For example, a first heat shrink tubing can be applied to the outer surface of the sheath, the sheath can be compressed to an intermediate diameter by the shrinkage (by heat) of the first heat shrink tubing, the first heat shrink tubing can be removed, a second heat shrink tubing can be applied to the outer surface of the sheath, the second heat shrink tubing can be compressed to a diameter smaller than the intermediate diameter by heat, and the second heat shrink tubing can be removed. This can be continued for as many times as necessary to achieve the desired crimped sheath diameter.

[0083] The crimping of the expandable sheath embodiments described herein can be carried out in various ways as described above. A roller-based crimping mechanism 602, such as that shown in Figures 25A to 25C, may be advantageous for crimping elongated structures such as the sheaths disclosed herein. This crimping mechanism 602 has a first end surface 604, a second end surface 605, and a longitudinal axis aa extending between the first end surface 604 and the second end surface 605. A plurality of disc-shaped rollers 606a-f are arranged radially around the longitudinal axis aa, and each of the disc-shaped rollers 606a-f is at least partially positioned between the first and second surfaces of the crimping mechanism 602. Six rollers are shown in the illustrated embodiments, but the number of rollers may be changed. Each disc-shaped roller 606 is mounted to a larger crimping mechanism by a connector 608. Figure 25B shows a lateral cross-section of an individual disc-shaped roller 606 and connector 608, and Figure 25C shows a top view of an individual disc-shaped roller 606 and connector 608. As shown in Figure 25C, an individual disc-shaped roller 606 has a circular edge 610, a first side surface 612, a second side surface 614, and a central axis cc extending between the first side surface 612 and the second side surface 614. The multiple disc-shaped rollers 606a-f are arranged radially around the longitudinal axis aa of the crimping mechanism 602 such that the central axis cc of each disc-shaped roller 606 is oriented perpendicular to the central axis aa of the crimping mechanism 602. The circular edge 610 of the disc-shaped roller partially defines a passage that extends axially through the crimping mechanism 602 along the longitudinal axis aa.

[0084] Each disc-shaped roller 606 is held in a fixed position in a radial arrangement by connectors 608 mounted to the crimping mechanism 602 by one or more fasteners 619, such that the position of each of the multiple connectors is fixed relative to the first end surface of the crimping mechanism 602. In the illustrated embodiment, the fasteners 619 are positioned radially outward of the disc-shaped roller 606, adjacent to the outer portion of the crimping mechanism 602. In the illustrated embodiment, two fasteners 619 are used to position each connector 608, but the number of fasteners 619 can be changed. As shown in Figures 25B and 25C, the connector 608 has a first arm 616 and a second arm 618. The first arm 616 and the second arm 618 extend on the disc-shaped roller 606 from the radially outward portion of the circular edge 610 to the central portion of the disc-shaped roller 606. The bolt 620 extends through the first arm 616 and the second arm 618, and through the central lumen of the disc-shaped roller 606, which penetrates along the central axis cc from the center point of the front surface 612 to the center point of the rear surface 614 of the disc-shaped roller 606. The bolt 620 is positioned without being fixed within the lumen, while having a substantial gap / space that allows the disc-shaped roller 606 to rotate about the central axis cc.

[0085] During use, the elongated sheath is advanced from the first side 604 of the crimping mechanism 602 through the axial passage between the rollers to the second side 605 of the crimping mechanism 602. The pressure from the circular edge 610 of the disc-shaped roller 606 reduces the diameter of the sheath to its crimped diameter as the disc-shaped roller 606 rolls along the outer surface of the elongated sheath.

[0086] Figure 26 shows one embodiment of a crimping device 700 designed to facilitate crimping of elongated structures such as sheaths. The crimping device comprises an elongated base 704, an elongated mandrel 706 positioned above the elongated base 704, and a holding mechanism 708 mounted on the elongated base 704. The holding mechanism 708 supports the mandrel 706 in an elevated position above the base 704. The holding mechanism includes a first end piece 710 with a crimping mechanism 702. The mandrel 706 includes a conical end portion 712 nested within a first tapered portion 713 of the constricted lumen 714 of the first end piece 710. The conical end portion 712 of the mandrel 706 is positioned without being fixed within the constricted lumen 714, and sufficient space or gap between the conical end portion 712 and the lumen 714 allows the passage of an elongated sheath through the constricted lumen 714 across the conical end portion 712 of the mandrel 706. During use, the conical end portion 712 helps to avoid circumferential buckling of the sheath during crimping. In some embodiments, the mandrel 706 may further comprise a cylindrical end portion 724, which extends outward from the conical end portion 712 and defines the end portion 726 of the mandrel 706.

[0087] The first tapered portion 713 of the constricted lumen 714 opens toward the second end piece 711 of the retaining mechanism 708 such that the widest side of the tapered portion is located on the inner surface 722 of the first end piece 710. In the illustrated embodiment, the first tapered portion 713 narrows to a narrow end 715 that connects to a narrow cylindrical portion 716 of the constricted lumen 714. In this embodiment, the narrow cylindrical portion 716 defines the minimum width diameter of the constricted lumen 714. The cylindrical end portion 724 of the mandrel 706 is nested within the narrow cylindrical portion 716 of the constricted lumen 714 without being fixed in place, and sufficient space or gap between the cylindrical end portion 724 and the narrow cylindrical portion 716 of the lumen allows for the passage of an elongated sheath. The elongated nature of the narrow cylindrical portion 716 may facilitate the smoothing of the crimped sheath after it has passed over the conical end portion 712 of the mandrel. However, this length of the cylindrical portion 716 of the constricted lumen 714 is not intended to limit the invention, and in some embodiments, the crimping mechanism 702 may comprise only the first tapered portion 713 of the constricted lumen 714, but still have the effect of crimping the elongated sheath.

[0088] As shown in Figure 26, at the opposite end of the first end piece 710, a second tapered portion 718 of the constricted lumen 714 extends from the narrow cylindrical portion 716, with the widest side of the tapered portion located on the outer surface 720 of the first end piece 710. The narrow end 719 of the second tapered portion 718 connects to the narrow cylindrical portion 716 of the constricted lumen 714 inside the crimping mechanism 702. In some embodiments, the second tapered portion 718 of the constricted lumen 714 may be omitted.

[0089] The retaining mechanism 708 further comprises a second end piece 711 positioned on the opposite side of the first end piece 710 in the elongated base 704. The second end piece 711 is movable relative to the elongated base 704, thereby making the distance between the first end piece 710 and the second end piece 711 adjustable, and thus capable of supporting mandrels of various sizes. In some embodiments, the elongated base 704 may comprise one or more elongated sliding tracks 728. The second end piece 711 may be slidably engaged with the sliding track 728 by at least one reversible fastener 730, such as, but not limited to, a bolt, extending through or through the second end piece 711 and the elongated sliding track 728. To move the second end piece 711, the user loosens or removes the reversible fastener 730, slides the second end piece 711 to the desired position, and replaces or tightens the reversible fastener 730.

[0090] During use, a sheath at its uncrimped diameter may be positioned on the elongated mandrel 706 of the crimping device 700 shown in Figure 26, such that the inner surface of the entire length of the uncrimped sheath is supported by the mandrel. The uncrimped sheath is then advanced over the conical end portion 712 through the constricted lumen 714 of the crimping mechanism 702. The uncrimped sheath is crimped to a smaller crimped diameter by pressure from the inner surface of the constricted lumen 714. In some embodiments, the sheath advances through both the first tapered portion 713 and the cylindrical portion 716 of the constricted lumen 714, and then exits from the crimping mechanism 702. In some embodiments, the sheath advances through the first tapered portion 713, the cylindrical portion 716, and the second tapered portion 718 of the constricted lumen 714, and then exits from the crimping mechanism 702.

[0091] In some embodiments, the crimping mechanism 602 shown in Figure 25A may be positioned within a larger crimping device, such as the crimping device 700 shown in Figure 26. For example, the crimping mechanism 602 may be positioned within the first end piece 710 of the crimping device 700, either in place of or in combination with the crimping mechanism 702. For example, the rolling crimping mechanism 602 may completely replace the constricted lumen 714 of the crimping mechanism 702, or the rolling crimping mechanism 602 may be nested within the narrow cylindrical portion 716 of the constricted lumen 714 of the crimping mechanism 702, so that the first tapered portion 713 can feed the expandable sheath through a plurality of radially arranged disc-shaped rollers 606.

[0092] Figures 34 to 36 show sheath embodiments comprising a distal end portion 902, which can be an extension of the outer cover extending longitudinally proximal along the sheath. Figure 34 shows the distal end portion 902 folded (in a crimped and shrunk configuration) around the introducer. Figure 35 shows a cross-section of the distal end portion 902 folded (in a crimped and shrunk configuration) around the introducer 908. Figure 36 shows the distal end portion 902 after being opened by passing it through a delivery system. The distal end portion 902 may be formed from, for example, one or more layers of the same or identical material used to form the outer layer of the sheath. In some embodiments, the distal end portion 902 comprises an extension of the outer layer of the sheath, with or without another additional layer added by a separate processing technique. This distal end portion may comprise any one to eight material layers (including material layers 1, 2, 3, 4, 5, 6, 7, and 8). In some embodiments, the distal end portion comprises multiple layers of Dyneema® material. The distal end portion 902 may extend distally beyond the longitudinal portion of the sheath comprising the braided layer 904 and the elastic layer 906. In fact, in some embodiments, the braided layer 904 may extend distally beyond the elastic layer 906, and the distal end portion 902 may extend distally beyond both the braided layer 904 and the elastic layer 906, as shown in Figures 34 to 36.

[0093] The distal end portion 902 may have a tapered appearance by having a smaller contraction diameter than the more proximal portion of the sheath. This ensures a smooth transition between the introducer / dilater and the sheath, thereby preventing the sheath from being positioned in contact with tissue while being inserted into the patient. This smaller contraction diameter may result from multiple folds (e.g., 1, 2, 3, 4, 5, 6, 7, or 8 folds) being circumferentially positioned (uniformly or unevenly spaced) around the distal end portion. For example, overlapping folds may be formed by circumferential segments of the distal end portion being integral with and then facing each other on adjacent outer surfaces of the distal end portion. In the contraction configuration, the overlapping portions of the folds extend longitudinally along the distal end portion 902. Examples of creasing methods and creasing configurations are described in U.S. Patent Applications 14 / 880,109 and 14 / 880,111, which are incorporated herein by reference in their entirety. Notches can be used as an alternative or as an addition to the folds of the distal end portion. Both notches and folds of the distal end portion 902 allow for expansion of the distal end portion as it passes through the delivery system and facilitate the retraction of the delivery system into the sheath upon completion of the procedure.

[0094] In some embodiments, a distal end portion is added, and the sheath and this end portion are crimped, and the crimp of the distal end portion and the sheath can be maintained by the following method. As described above, the distal end portion 902 can be an extension of the outer layer of the sheath. Alternatively, a separate multilayer tube can be heat-bonded to the rest of the sheath before the end portion crimping step. In some embodiments, this separate multilayer tube is heat-bonded to the distal extension of the outer layer of the sheath to form the distal end portion 902. To crimp the sheath after the end portion is attached, the sheath is heated on a small mandrel. The distal end portion 902 can be folded around the mandrel to form the folded configuration shown in Figure 34. The folds can be added to the distal end portion 902 before the end portion crimping process or at an intermediate point during the end portion crimping process. In some embodiments, the small mandrel can have a diameter of approximately 2 mm to approximately 4 mm (including approximately 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3.0 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, and 4.0 mm). The heating temperature will be lower than the melting point of the material being used. This allows the material to automatically shrink to a certain degree. For example, in some embodiments, such as when Dyneema® material is used as part of the material for the outer layer and / or distal end portion of the sheath, the sheath crimping process is initiated by heating the sheath to approximately 125 degrees Celsius on a 3 mm mandrel (below the melting point of Dyneema®, which is approximately 140 degrees Celsius). This crimps the sheath to an outer diameter of approximately 6 mm. At this point, the sheath and distal end region 902 are allowed to cool. A heat shrink tube may then be applied. In some embodiments, the heat shrink tube can have a melting point that is substantially the same as the melting point of the material at its distal end.The heat shrink tubing extends over the sheath and distal end portion 902, and the sheath is heated again (to approximately 125 degrees Celsius in the case of a sheath with an outer layer and distal end portion of Dyneema®) to crimp the sheath to an even smaller diameter. At the location of the distal end portion 902, a higher temperature is applied (e.g., approximately 145 to 155 degrees Celsius in the case of Dyneema® material) to weld these material layers together in the folded configuration shown in Figure 34 (these folds can be added at any point during this process). The joint at the distal end portion 902 induced by the high-temperature melting step remains fragile enough to break as it passes through the delivery system. In the final step, the heat shrink tubing is removed, leaving the sheath shape at the crimped diameter.

[0095] Embodiments of the sheath described herein may include various lubricating outer coatings comprising a hydrophilic coating or a hydrophobic coating, and / or surface blooming additives or surface blooming coatings.

[0096] Figure 27 shows another embodiment of the sheath 500 having a tubular inner layer 502. The inner layer 502 may be formed from an elastic thermoplastic material such as nylon and may have a plurality of cuts or grooves 504 along its length so that the tubular layer 502 is divided into a plurality of long, thin ribs or sections 506. As the delivery device 10 advances through the tubular layer 502, the grooves 504 elastically expand or open, thereby widening the ribs 506 and increasing the diameter of the layer 502 to accommodate the delivery device.

[0097] In other embodiments, the notches 504 can be configured as openings or notches having various geometric shapes, such as rhombic, hexagonal, or combinations thereof. In the case of hexagonal openings, these openings can be irregular hexagons with relatively long axial dimensions to reduce the shortening of the sheath when the sheath is expanded.

[0098] The sheath 500 may further comprise an outer layer (not shown), which may contain a relatively low durometer hardness elastic thermoplastic material (e.g., Pebax, polyurethane, etc.) and may be bonded to the inner nylon layer (e.g., by adhesive, or by welding such as thermal welding or ultrasonic welding). By attaching the outer layer to the inner layer 502, the axial movement of the outer layer relative to the inner layer during radial expansion and contraction of the sheath can be reduced. The outer layer may also form the distal end of the sheath.

[0099] Figure 28 shows another embodiment of the braided layer 600 that can be used in combination with any of the sheath embodiments described herein. The braided layer 600 may comprise a plurality of braided portions 602 in which the filaments of the braided layer are braided together, and unbraided portions 604 in which the filaments are not braided together and extend axially without being twisted together. In some embodiments, the braided portions 602 and unbraided portions 604 may be alternating along the length portions of the braided layer 600, or may be incorporated in any other suitable pattern. The ratio of the length of a given braided layer 600 to the braided portions 602 and unbraided portions 604 may allow for selection and control of the expansion and contraction characteristics of the braided layer.

[0100] In some embodiments, the distal end portion of the sheath (and / or vascular dilator) can be reduced from the inner diameter of the sheath (e.g., 8 mm) to 3.3 mm (10 F), and can be reduced to the diameter of the guidewire, thereby allowing the sheath and / or vascular dilator 300 to move along the guidewire.

[0101] General considerations This description will explain some aspects, advantages, and novel features of embodiments of the present disclosure. These disclosed methods, apparatus, and systems should not be construed as limiting. Rather, this disclosure covers all novel and non-obvious features and aspects of various embodiments of the disclosure, individually and in various combinations and subcombinations thereof. These methods, apparatus, and systems are not limited to any particular aspect or feature, or any combination thereof, and the embodiments of the present disclosure do not require the existence of any one or more particular advantages or solutions to any problem.

[0102] Some operations of the embodiments of this disclosure are described in a particular order for convenience, but it should be understood that this method of description is inclusive of reordering unless required by specific expressions shown hereafter. For example, operations described sequentially may be performed in a different order or simultaneously in some examples. Furthermore, for simplicity, the accompanying drawings may not show the various forms in which the disclosed methods may be used in combination with other methods. In addition, this description sometimes uses terms such as “provides” or “achieves” to describe the methods of this disclosure. These terms are high-level abstractions of the actual operations performed. The actual operations corresponding to these terms may be modified depending on their particular implementation and will be readily recognizable to those skilled in the art.

[0103] In this application and claims, the singular forms “a, an” and “the” include the plural unless otherwise explicitly stated in the context. Furthermore, the term “includes” means “equipped with.” Furthermore, the terms “combined” and “associated” generally mean being combined or linked electrically, electromagnetically, and / or physically (e.g., mechanically or chemically), and do not exclude the existence of intermediate elements between the combined or associated items unless there is a specifically contrasting expression.

[0104] In the context of this application, the terms “lower” and “upper” are used interchangeably with the terms “inflow” and “outflow,” respectively. Therefore, for example, the lower end of the valve is the inflow end of the valve, and the upper end of the valve is the outflow end of the valve.

[0105] In this specification, the term “proximal” refers to a location, orientation, or part of the device that is closer to the user and further away from the implantation site. In this specification, the term “distal” refers to a location, orientation, or part of the device that is further away from the user and closer to the implantation site. For example, proximal movement of a device is movement of the device toward the user, and distal movement of a device is movement of the device away from the user. The terms “longitudinal” and “axial” refer to axial extension in the proximal and distal directions, respectively, unless otherwise specified.

[0106] Unless otherwise indicated, all figures used herein or in the claims to represent dimensions, component quantities, molecular weights, percentages, temperatures, forces, and times, etc., should be understood to be modified by the term "approximately." Therefore, unless otherwise indicated implicitly or explicitly, the numerical parameters presented are approximations that can be determined by the desired properties required and / or the limits of detection under test conditions / methods well known to those skilled in the art. Where embodiments are fully and clearly identified from the prior art discussed, the embodiment numbers are not approximations unless the term "approximately" is referenced. Furthermore, not all alternative forms listed herein are equivalents.

[0107] In light of the numerous possible embodiments to which the principles of the disclosed technology may be applied, it should be understood that these exemplary embodiments are merely preferred examples and should not be construed as limiting the scope of this disclosure. Rather, the scope of this disclosure is at least the same as the scope of the appended claims. Accordingly, everything that falls within the scope and spirit of these claims is subject to the claims. [Explanation of symbols]

[0108] 10 Delivery device 12. Artificial heart valves, artificial devices, implants 14. Maneuverable guide catheter 16 Balloon catheter 18 Handle section 20 slender guide shafts 90 Assembly, Introducer Equipment 92 Introducer Housing 100 Expandable Sheath 102 First layer, inner layer, first polymer layer, polymer inner layer, polymer layer, inner polymer layer 104 The second layer, the braided layer 106 Third layer, elastic layer 108 Fourth layer, outer layer, outermost layer, outer polymer layer, polymer outer layer, polymer layer 110 components, filaments, braided filaments 110A filament 110B Filament 112 central lumens, see-through lumens 114 Central axis 116 strands, ribbons, bands, elastic bands 116A Elastic Band 116B Elastic Band 118 Cylindrical Mandrel 120 ePTFE layer, inner layer 122 ePTFE layer, outer layer 124 Heat shrink tube layer, heat shrink tape layer, heat shrink layer 126 Ridge, crease, 128 Longitudinal groove 130 Code 132 Arrow direction 134 Unit Cells 136 Space 140 Distal end portion 142 Distal end 150 portions 152 loops 200 equipment 202 Containment container 204 Chamber 206 Closed end 208 Open end 210 Thermally expandable materials 212 Cap 214 Heating System 300 vasodilators 302 Shaft component 304 Nose Cone 306 Holding member, capsule 308 Proximal end portion 310 Circumferential space 312 Shaft 314 Balloons 400 heat shrink tubing layer 402 Marked line 404 Circular opening 406 Long carved line 408 Overhang 500 sheath 502 Tubular inner layer 504 Marked line 506 Long, thin ribs or sections 600 braided layers 602 Roller base crimping mechanism, rolling crimping mechanism, braided section 604 First end surface, first side, unbraided portion 605 Second end surface, second side 606 Disc-shaped roller 606a-f Disc-shaped roller 608 connector 610 circular edge 612 First side surface, front surface 614 Second side surface, rear surface 616 First Arm 618 Second Arm 619 Fixtures 620 volts 700 Crimping Equipment 702 Crimping mechanism 704 Long and slender base 706 Long and slender mandrel 708 Retention mechanism 710 First end piece 711 Second end piece 712 Conical end portion 713 First tapered portion 714 stenotic lumens 715 Narrow end 716 Narrow cylindrical section 718 Second tapered portion 719 Narrow end 720 Outer surface 722 Inner surface 724 Cylindrical end portion 726 End 728 Long and narrow sliding track 730 Reversible Fixture 802 Inner layer 804 braided layer 806 Elastic layer 808 Outer layer 809 Heat shrink tubing layer 811 Crack 813 Perforation 815 Adhesive Seam 817 Delivery System 902 Distal end portion 904 Braided layer 906 Elastic layer 908 Introducer

Claims

1. An expandable sheath for deploying medical devices, The first polymer layer, A braided layer comprising a plurality of braided filaments arranged radially outward from the first polymer layer, wherein at least a portion of the plurality of filaments of the braided layer forms a multi-stage loop toward the distal end of the braided layer, and the number of filaments decreases toward the distal end of the braided layer, A second polymer layer disposed radially outward of the braided layer, wherein the braided layer is bonded to the first polymer layer such that the braided layer is encased between the first polymer layer and the second polymer layer, and the plurality of filaments of the braided layer are movable between the first polymer layer and the second polymer layer so that the braided layer can expand radially when a medical device passes through the sheath. Equipped with, As the medical device passes through the sheath, the diameter of the sheath expands from a first diameter to a second diameter around the medical device, and the first polymer layer and the second polymer layer resist axial elongation of the sheath such that the length of the sheath remains substantially constant. The sheath is an expandable sheath that elastically returns to the first diameter due to the radial force applied by the braided layer when the medical device passes through it.

2. The expandable sheath according to claim 1, wherein the first polymer layer and the second polymer layer have a plurality of longitudinally extending folds when the sheath is at the first diameter.

3. The expandable sheath according to claim 2, wherein the longitudinally extending fold forms a plurality of circumferentially spaced ridges and a plurality of circumferentially spaced grooves.

4. The expandable sheath according to claim 3, wherein when a medical device passes through the sheath, the ridges and grooves flatten out, causing the sheath to expand radially.

5. The expandable sheath according to claim 1, wherein the filaments of the braided layer are not engaged with or bonded to the first polymer layer or the second polymer layer.

6. The expandable sheath according to claim 1, wherein the first polymer layer and the second polymer layer are fitted together in a plurality of open spaces between the filaments of the braided layer.

7. The expandable sheath according to claim 1, wherein the loops are offset axially from one another in the braid.

8. The expandable sheath according to claim 1, wherein the number of braided filaments decreases toward the distal end of the braided layer.

9. The expandable sheath according to claim 1, wherein the second polymer layer extends toward the distal end of the sheath.

10. The expandable sheath according to claim 1, further comprising an outer cover that extends longitudinally beyond the distal ends of the first polymer layer, the braided layer, and the second polymer layer, forming an overhang.

11. The expandable sheath according to claim 10, wherein the outer cover comprises one or more longitudinally extending slits, weak portions, or grooves.

12. The expandable sheath according to claim 10, wherein the outer cover is formed from a heat-shrinkable material.

13. The expandable sheath according to claim 10, wherein the outer cover is made of elastomer.

14. The expandable sheath according to claim 1, further comprising a distal end portion that is elastically expandable between the first diameter and the second diameter, A vasodilator disposed within the sheath, comprising a tapered nose cone and a retaining member that at least partially extends over the distal end portion of the sheath and is configured to hold the distal end portion of the sheath to the first diameter, and An assembly comprising:

15. The assembly according to claim 14, wherein the distal end portion is thermocured into an extended configuration.

16. The assembly according to claim 14, wherein the distal end portion of the braided layer is heat-cured into a flared structure.

17. The assembly according to claim 14, wherein the retaining member is a polymer heat shrink layer.

18. The assembly according to claim 14, wherein the retaining member is an elastomer and is configured to compress the distal end portion of the sheath.

19. The assembly according to claim 14, wherein the retaining member is bonded or welded to the sheath.

20. The assembly according to claim 14, wherein the retaining member comprises a shaft disposed between the expander and the sheath, the shaft comprising a releasable coupling configured to mechanically engage with both the expander and the sheath and to be manually released.

21. The assembly according to claim 14, wherein the retaining member comprises one or more balloons disposed between the expander and the sheath.

22. An expandable sheath for deploying medical devices, The first polymer layer, A braided layer comprising a plurality of braided filaments arranged radially outward from the first polymer layer, wherein at least a portion of the plurality of filaments of the braided layer forms a multi-stage loop toward the distal end of the braided layer, and the number of filaments decreases toward the distal end of the braided layer, A second polymer layer disposed radially outward from the braided layer, wherein the braided layer is bonded to the first polymer layer such that it encloses the braided layer between the first polymer layer and the second polymer layer. Equipped with, As the medical device passes through the sheath, the diameter of the sheath expands from a first diameter to a second diameter around the medical device, and the first polymer layer and the second polymer layer resist axial elongation of the sheath such that the length of the sheath remains substantially constant. The sheath is an expandable sheath that elastically returns to the first diameter due to the radial force applied by the braided layer when the medical device passes through it.

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