Stent delivery system

Abstract

The stent delivery system is configured to deliver and release a self-expanding stent while improving power transmission efficiency and reducing energy loss. The stent delivery system includes an inner member including a stent receiving region, a proximal member including a buckling reduction member configured to reduce collapsibility within the proximal member, and a deployment sheath coaxially extending around the inner member and the proximal member and movable between a position where the deployment sheath constrains the self-expanding stent and a position where the deployment sheath does not constrain the self-expanding stent, the deployment sheath including an elongation reduction member configured to reduce extensibility within the deployment sheath. The reduced collapsibility of the proximal member and the reduced extensibility of the deployment sheath reduce energy loss within the stent delivery system.

Description

Technical Field

[0001] The present invention relates to medical devices and methods for fabricating and using medical devices. More specifically, the present invention relates to a stent delivery system. This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 359,409, filed Jul. 8, 2022, the entire disclosure of which is incorporated herein by reference.

Background Art

[0002] Various in-vivo medical devices have been developed for medical applications, such as intravascular applications. Some of these devices include stent delivery systems. These devices are manufactured by any one of a variety of different manufacturing methods and can be used according to any one of a variety of methods. Each of the known stent delivery devices, as well as methods for fabricating and using stent delivery devices, has specific advantages and disadvantages. There is still a need to provide alternative stent delivery devices and alternative methods for fabricating and using stent delivery devices.

Summary of the Invention

[0003] The present invention provides alternative means of design, materials, manufacturing methods, and use for a stent delivery system, including a self-expanding stent delivery system, a clip member for use with the stent delivery system, and methods for fabricating and using them.

[0004] One embodiment may be found in a stent delivery system configured to reduce energy loss within the stent delivery system and to deliver and deploy a self-expanding stent. The stent delivery system includes an inner member that includes a stent receiving region configured to receive the self-expanding stent. A proximal member extends coaxially around the inner member. The proximal member has a distal end that terminates in the vicinity of the stent receiving region. The proximal member includes a buckling reduction member configured to reduce collapsibility within the proximal member. A deployment sheath extends coaxially around the inner member and the proximal member. The deployment sheath is movable between a distal position in which the deployment sheath constrains the self-expanding stent and a proximal position in which the self-expanding stent is no longer constrained by the deployment sheath. The deployment sheath includes a stretch reduction member configured to reduce extensibility within the deployment sheath. The reduced collapsibility of the proximal member and the reduced extensibility of the deployment sheath reduce energy loss within the stent delivery system.

[0005] Alternatively or additionally, the stent delivery system may further include a gear rack assembly coupled to the deployment sheath and a handle coupled to the inner member and the deployment sheath. The handle includes an actuating member. The actuating member is coupled to the gear rack assembly such that the longitudinal positions of the gear rack assembly and the deployment sheath relative to the stent receiving region change upon actuation of the actuating member.

[0006] Alternatively or additionally, the deployment sheath may include an inner polymer layer and an outer polymer layer. The stretch reduction member is disposed between the inner polymer layer and the outer polymer layer.

[0007] Alternatively or additionally, the stretch reduction member may include a first braided member. Alternatively or additionally, the first braided member may be configured to resist stretching in response to an applied tensile force.

[0008] Alternatively or additionally, the buckling reduction member may be encapsulated within a polymer layer. Alternatively or additionally, the buckling reduction member may extend over a majority of the length of the proximal member.

[0009] Alternatively or additionally, the buckling reduction member may include a second braided member. Alternatively or additionally, the second braided member may be configured to resist buckling in response to an applied compressive force.

[0010] Alternatively or additionally, the stent delivery system may be adapted to deliver a self-expanding stent. Another embodiment may be found in a stent delivery system configured to improve force transmission efficiency within the stent delivery system to deliver and release a self-expanding stent. The stent delivery system includes an inner member including a stent receiving region configured to receive a self-expanding stent. A proximal member extends coaxially around the inner member. The proximal member extends proximally from near the stent receiving region. The proximal member includes a buckling reduction member configured to reduce collapsibility within the proximal member. A deployment sheath extends coaxially around the inner member and the proximal member. The deployment sheath is movable between a distal position where the deployment sheath constrains the self-expanding stent and a proximal position where the self-expanding stent is no longer constrained by the deployment sheath. The deployment sheath includes an elongation reduction member configured to reduce extensibility within the deployment sheath. The reduced collapsibility of the proximal member and the reduced extensibility of the deployment sheath improve force transmission efficiency within the stent delivery system.

[0011] Alternatively or additionally, the deployment sheath may include an inner polymer layer and an outer polymer layer. The elongation reduction member is disposed between the inner polymer layer and the outer polymer layer.

[0012] Alternatively or additionally, the extension reducing member may include a first braided member. Alternatively or additionally, the buckling reducing member may be encapsulated within a polymer layer. Alternatively or additionally, the buckling reducing member may extend over a majority of the length of the proximal member.

[0013] Alternatively or additionally, the buckling reducing member may include a second braided member. Another example may be found in a stent delivery system configured to deliver and deploy a self-expanding stent. The stent delivery system includes an inner member having a stent receiving region configured to receive a self-expanding stent. A proximal buffer extends coaxially around the inner member. The proximal buffer includes a buckling reducing braided member encapsulated within a polymer layer. A deployment sheath extends coaxially around the inner member and the proximal buffer. The deployment sheath includes an extension reducing braided member disposed between an inner polymer layer and an outer polymer layer, and the deployment sheath is movable between a distal position where the deployment sheath constrains the self-expanding stent and a proximal position where the self-expanding stent is no longer constrained by the deployment sheath.

[0014] Alternatively or additionally, the buckling reducing braided member may be configured to resist collapsing in response to an applied compressive force. Alternatively or additionally, the extension reducing braided member may be configured to resist stretching in response to an applied tensile force.

[0015] Alternatively or additionally, the stent delivery system may be adapted to deliver a peripheral stent. The above summary of some embodiments is not intended to describe every disclosed embodiment or every implementation of the present invention. The drawings and detailed description illustrate these embodiments more specifically.

[0016] The present invention can be more fully understood by considering the following detailed description of various embodiments of the present invention related to the drawings.

Brief Description of the Drawings

[0017]

Figure 1

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Modes for Carrying Out the Invention

[0018] Although the present invention is capable of various modifications and alternative forms, specific forms thereof are shown by way of example in the drawings and will be described in detail below. However, the present invention is not intended to be limited to the specific embodiments described below. Rather, it is intended to cover all modifications, equivalents, and alternative forms included within the spirit and scope of the present invention.

[0019] For the terms defined below, these definitions shall apply unless different definitions are provided in the claims or elsewhere in this specification. All numerical values are assumed to be modified by the term "about" whether or not explicitly indicated in this specification. The term "about" refers to a range of numerical values that a person of ordinary skill in the art would generally consider to be equivalent (e.g., having the same function or result) to the recited value. In many cases, the term "about" may include numbers rounded to the nearest significant digit.

[0020] The recitation of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). As used in this specification and the claims, the singular form "one" includes a plurality of referents unless the context clearly dictates otherwise. The term "or" as used in this specification and the claims is generally used in the sense of "and / or" unless the context clearly dictates otherwise.

[0021] The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered the same. The drawings are not necessarily to scale. The drawings illustrate exemplary embodiments and are not intended to limit the scope of the present invention.

[0022] FIG. 1 shows an exemplary stent delivery system 10. The system 10 can include a long shaft 12 and a handle 14 coupled to the shaft 12. Generally, the system 10 can be used to deliver a suitable stent, graft, internal organ, etc. to a region of interest within a body lumen of a patient. The body lumen can be a blood vessel located near the heart (e.g., within or near a cardiovascular vessel), within a peripheral blood vessel, within a neurovascular vessel, or at any other suitable location. In some cases, the stent delivery system 10 can include one or more features that reduce energy loss within the stent delivery system 10 while delivering a stent using the stent delivery system 10. These same one or more features can improve force transmission through the stent delivery system 10.

[0023] By improving force transmission through the stent delivery system 10, the individual components within the stent delivery system 10 are configured to perform their individual roles while maintaining good useful properties when delivering a stent, so that energy loss within the stent delivery system 10 can be reduced. When delivering a stent by the stent delivery system 10, one or more components of the stent delivery system 10 can be placed in a compressed state and one or more components of the stent delivery system 10 can be placed in a tensile state. In some cases, it can be useful to balance the specific properties of the components to be compressed and the components to be tensioned.

[0024] In some instances, reducing energy loss may include reducing compression within a component that is subject to a compressive force and / or reducing elongation within a component that is subject to a tensile force. When a component subject to a compressive force begins to buckle or compress, for example, some of the energy applied to the stent delivery system 10 by a user applying a particular force will cause the component to compress, and thus will not achieve the desired effect on the component, such as moving the component or providing resistance to movement when the component functions as a buffer, for example. Also, when a component subject to a tensile force begins to elongate, for example, some of the energy applied to the stent delivery system 10 by a user applying a particular force will cause the component to elongate, and thus will not achieve the desired effect on the component, such as pulling the component away from another component, for example.

[0025] Compression and / or elongation of components within the stent delivery system 10 causes energy loss because it utilizes the energy applied to deliver the stent by the stent delivery system 10. When a force is applied to the stent delivery system 10, reducing compression of a component subject to a compressive force means that less energy is consumed in compressing that component, and as a result, the force transmission efficiency is improved. When a force is applied to the stent delivery system 10, reducing elongation of a component subject to a tensile force means that less energy is consumed in elongating that component, and as a result, the force transmission efficiency is improved. Force transmission efficiency is an indicator that shows the magnitude of the force actually used to move the components of the stent delivery system 10 to deliver the stent out of the force applied to the stent delivery system 10, relative to the force lost due to compression and / or elongation of the components of the stent delivery system 10.

[0026] Reducing energy loss can be particularly useful when delivering stents such as self-expanding stents that have a relatively high radially outward force. For example, some longer stents have a relatively high radially outward force. Also, some stents with a large diameter have a relatively high radially outward force. In some cases, bare metal stents of a particular size can have a higher radially outward force compared to stents of the same size that include a coating on the stent. This is because the coating can vary the possible frictional force between the stent and the delivery device used to deliver the stent. In some cases, peripheral stents can have a relatively high radially outward force.

[0027] Components placed in a compressed state during delivery of the stent by the stent delivery system 10 can be configured to resist a decrease in length against the applied compressive force. As an example, components placed in a compressed state can be configured to include a buckling reduction member, as described below. This buckling reduction member functions to limit buckling, i.e., a decrease in length, of the component that includes the buckling reduction member.

[0028] Components placed in a tensile state during delivery of the stent by the stent delivery system 10 can be configured to resist elongation, i.e., an increase in length, against the applied tensile force. As an example, components placed in a tensile state during delivery of the stent by the stent delivery system 10 can be configured to include an elongation reduction member, as described below. This elongation reduction member functions to limit elongation, i.e., an increase in length, of the component that includes the elongation reduction member.

[0029] The deployment of the stent may include retraction of the deployment sheath 16 covering the stent proximally. The retraction of the deployment sheath 16 may generally include the actuation of an actuation member 18 disposed on the handle 14. In the example shown in FIG. 1, the actuation member 18 is a thumbwheel that can be rotated by a clinician to achieve retraction of the deployment sheath 16 proximally. A number of other actuation members are possible. Some other structures and features of the stent delivery system 10 can be seen in FIG. 1 and are labeled with reference numerals. Further description of these structures may be made below.

[0030] FIGS. 2-8 show at least some of the structural components that may be included as part of the stent delivery system 10. For example, the stent delivery system 10 may include an inner shaft or member 20, as shown in FIG. 2. In at least some embodiments, the inner member 20 may be a tubular structure and thus may include a lumen (not shown). The lumen may be a guidewire lumen that extends along at least a portion of the length of the inner member 20. Thus, the stent delivery system 10 can be advanced along a guidewire to a desired target location within a vascular structure. In additional or alternative embodiments, the lumen may be a perfusion / suction lumen that allows some or all of the components of the stent delivery system 10 to be washed, perfused, suctioned, etc.

[0031] The inner member 20 may include a stent receiving region 22 around which a stent (not shown, seen in FIGS. 3-4) may be disposed. The length and / or configuration of the stent receiving region 22 may be varied. For example, the stent receiving region 22 may have a length sufficient to dispose a stent thereon. As the length of the stent utilized in the stent delivery system 10 increases, the length of the stent receiving region 22 also increases.

[0032] One or more perfusion ports 24 may be disposed along or adjacent to the stent receiving region 22. The perfusion port 24 may penetrate the wall of the inner member 20 such that fluid can flow through the lumen of the inner member 20 and through the port 24. This may be desirable for several reasons. For example, the port 24 may enable a clinician to expel air bubbles that may be trapped adjacent to the stent by perfusing fluid through the port 24. Also, the port 24 may be used to aspirate fluid that may be disposed along the inner member 20. Further, the port 24 may assist in sterilization and / or other preparatory processing steps that may be involved in preparing the stent delivery system 10 for sale.

[0033] The tip 26 may be attached to or otherwise disposed at the distal end of the inner member 20. The tip 26 may generally have a rounded or smooth shape that provides a generally atraumatic distal end to the stent delivery system 10. For example, the tip 26 may have a smooth tapered distal portion 28 that is gently tapered. Also, the tip 26 may include a proximal ridge 30 configured such that the deployment sheath 16 can abut against it. Also, the tip 26 may include a tapered proximal portion 33. Many other shapes and / or configurations are possible for the tip 26.

[0034] Also, the tip 26 may include one or more notches or flats 32 formed in the tip 26. For the purposes of the present disclosure, it is understood that the flat 32 is a notch or flat of the tip 26 that reduces the outer dimension or outer profile of the tip 26. The name "flat" is derived from the fact that these regions may have a somewhat "flat" appearance compared to the remainder of the tip 26 that may generally have a rounded contour. However, the shape of the flat 32 is not meant to be limited to being flat or planar as many shapes are contemplated.

[0035] The flat portion 32 may enable a gap or space to be defined between the inner member 20 and the deployment sheath 16 when the deployment sheath 16 abuts against the proximal ridge 30 of the tip 26. This gap may enable fluid, such as the perfusion fluid passing through the port 24, to flow out from the deployment sheath 16. Thus, by using the flat portion 32 in combination with the port 24, it becomes possible to wash a part or all of the stent delivery system 10 or to discharge air bubbles.

[0036] Figure 3 shows the inner member 20 having some additional structures of the stent delivery system 10. In this figure, the stent 34 is disposed around the inner member 20 (for example, around the stent receiving region 22 of the inner member 20). In some examples, the stent 34 is a self-expanding stent. Thus, the stent 34 can be biased to expand outward. For this reason, the stent 34 may not be "mounted" on the inner member 20 in a strict sense, but rather may be disposed around the inner member 20 or may surround the inner member 20. The stent 34 can then be constrained within the deployment sheath 16. However, in other cases, the stent 34 can be directly mounted on the inner member 20 by crimping or any other suitable mechanical holding mechanism.

[0037] The intermediate tube 36 may be disposed to cover the inner member 20. In at least some cases, the intermediate tube 36 may extend from a position adjacent to the proximal end of the inner member 20 to a position proximal to the distal end of the inner member 20. The intermediate tube 36 may include a buffer portion 38. In practice, the buffer portion 38 may function by preventing unwanted proximal movement of the stent 34 during the manipulation and / or deployment of the stent 34.

[0038] The buffer portion 38 can have any suitable form. In some embodiments, the buffer portion 38 can be defined by a relatively short tube or sleeve disposed around the intermediate tube 36. The material utilized for this sleeve can be the same as or different from the material of the intermediate tube 36. The intermediate tube 36 can have a smooth transition portion with a tapered outer diameter or in other manners adjacent to the buffer portion 38. For example, a polymer material can be disposed or reflowed adjacent to the buffer portion 38 such that the outer diameter defines a smooth transition portion at the buffer portion 38 (which can include disposing the polymer material around a part or all of the buffer portion 38). Other configurations are possible and can be utilized in alternative embodiments.

[0039] In some examples, since the intermediate tube 36 functions to position the buffer portion 38, the intermediate tube 36 can be placed in a compressed state when the stent 34 is delivered by the stent delivery system 10. When the deployment sheath 16 is retracted proximally to deploy the stent 34, the deployment sheath 16 or its inner surface can apply a force to the stent 34 by the frictional force between the stent 34 and the inner surface of the deployment sheath 16. Due to this applied force, the stent 34 can be biased in the proximal direction. The buffer portion 38 positioned by the intermediate tube 36 as described above functions to resist this force applied to the stent 34, thereby enabling the stent 34 to remain in a predetermined position.

[0040] In some cases, the intermediate tube 36 may include a buckling reduction member configured to resist buckling in response to an applied compressive force. FIG. 4 is a side view of a portion of the intermediate tube 36, and FIG. 5 is a cross-sectional view of the intermediate tube 36 taken along line 5-5 of FIG. 4. The intermediate tube 36 includes a buckling reduction member 35 encapsulated within a polymer layer 37. In some cases, the buckling reduction member 35 may have a buckling strength sufficient to resist buckling due to the force applied to the intermediate tube 36 when the deployment sheath 16 is retracted to deploy the stent 34. For example, when the deployment sheath 16 is retracted proximally, a frictional force is generated between the deployment sheath 16 and the stent 34, and since the intermediate tube 36 resists the proximal movement of the stent 34, a compressive force may be applied to the intermediate tube 36 from the stent 34.

[0041] In some cases, the polymer layer 37 may include an inner portion 37a and an outer portion 37b, as shown. In some cases, for example, the intermediate tube 36 may be formed by dip coating to form the inner portion 37a. The buckling reduction member 35 may be disposed around the inner portion 37a. Thereafter, by continuing the dip coating to form the outer portion 37b, the buckling reduction member 35 may be encapsulated within the polymer layer 37. Other methods of encapsulating the buckling reduction member 35 within the polymer layer 37 are possible.

[0042] Upon receiving a compressive force applied to the intermediate tube 36, the buckling reduction member 35 can be configured to provide the intermediate tube 36 with high resistance against buckling, crushing, or a decrease in the length of the intermediate tube 36. The buckling reduction member 35 can provide additional strength to the intermediate tube 36 without unduly affecting the flexibility of the intermediate tube 36 itself and thus without unduly affecting the flexibility of the stent delivery system 10 itself. In some cases, the polymer layer 37 including the inner portion 37a and / or the outer portion 37b can contribute to improving the buckling resistance of the intermediate tube 36. In some examples, the resistance of the intermediate tube 36 to buckling can be considered as the sum of the buckling resistances potentially provided by each component forming the intermediate tube 36.

[0043] The buckling reduction member 35 can extend substantially over the entire length of the intermediate tube 36. In some cases, the buckling reduction member 35 can extend only over a part of the entire length of the intermediate tube 36. As an example, the buckling reduction member 35 can be disposed within a part of the intermediate tube 36 that extends within the handle 14. In some cases, the buckling reduction member 35 can include two or more separate portions of the buckling reduction member 35 each sealed within the polymer layer 37. Each portion is longitudinally spaced from the other portions.

[0044] The buckling reduction member 35 can take any of a variety of different forms. In some cases, the buckling reduction member 35 can be, for example, a slotted hypotube. In some cases, the buckling reduction member 35 can be a braided member such as a stainless steel braided flat wire ribbon. In some cases, the braided member can have a different pick count depending on the length. The braided member can be formed of flat wire or ribbon wire. The braided member can be formed of flat wire or ribbon wire formed of a polymer material or a metal material. Also, the diameter of one or more wires used to form the braided member can be varied.

[0045] Figure 6 shows an additional structure of the stent delivery system 10. Here, it can be seen that the deployment sheath 16 is disposed to cover the inner member 20, the intermediate tube 36, and the stent 34. The deployment sheath 16 is configured to be displaceable between a first position where the deployment sheath 16 overlaps the stent 34, as shown, for example, in Figure 6, and a second position where the deployment sheath 16 is retracted proximally to a position substantially proximal to the stent 34. Generally, the first position can be utilized during the manipulation of the stent delivery system 10 to an appropriate position within the body lumen, and the second position can be used to deploy the stent 34.

[0046] The deployment sheath 16 may include a flare portion 40 where the outer diameter of the deployment sheath 16 increases. In the portion 40, the wall thickness of the deployment sheath 16 may or may not be increased. The flare portion 40 may be desirable for several reasons. For example, the flare portion 40 may enable the deployment sheath 16 to have an appropriate inner dimension such that the deployment sheath 16 can be disposed around the stent 34 and the buffer portion 38.

[0047] In some cases, the deployment sheath 16 may be subject to a tensile force when the deployment sheath 16 is moved proximally as a result of frictional and other forces generated between the stent 34 and the inner surface of the deployment sheath 16. In some cases, the deployment sheath 16 may include an elongation reduction member 42 configured to resist elongation in response to the applied tensile force. In some examples, the elongation reduction member 42 may be configured to resist elongation in response to the applied force. The elongation reduction member 42 may be configured to have sufficient strength to balance the strength of the buckling reduction member 35.

[0048] The elongation reduction member 42 can provide additional strength to the deployment sheath 16 without unduly affecting the flexibility of the deployment sheath 16 itself and thus without unduly affecting the flexibility of the stent delivery system 10. The elongation reduction member 42 can take any of a variety of different forms. In some cases, the elongation reduction member 42 may be, for example, a slotted hypotube. In some cases, the elongation reduction member 42 may be a braided member such as a stainless steel braid. For example, the elongation reduction member 42 may include a braid, coil, mesh, combinations thereof, or any other suitable configuration. In some embodiments, the elongation reduction member 42 may extend along the entire length of the sheath 16. In other embodiments, the elongation reduction member 42 may extend along one or more portions of the length of the sheath 16. For example, the elongation reduction member 42 may extend along the flare portion 40.

[0049] In some cases, the elongation reduction member 42 may be a stainless steel braid having a total of 32 braided ribbons arranged in a 2×2 pattern. The stainless steel braid may have a low pick number and a high braiding angle. In some cases, the elongation reduction member 42 may include 32 individual ribbons configured in a 1×1 pattern and at a low braiding angle to provide various bending characteristics. Also, the elongation reduction member 42 may be configured as 16 wires in such a pattern and braiding angle, but with a substantially larger ribbon size (2 to 3 times that of the example described above) to provide the desired performance. In some cases, axially aligned wires may be included within the braiding pattern to further improve the elongation resistance. This is particularly beneficial for systems that require planarity in bending performance. The exact design configuration depends on the specific user requirements of the end device for clinical performance and can be adjusted to provide the required specifications. This can be done in cooperation with other members of the stent delivery system 10 to achieve an improvement in the force transmission efficiency of the stent delivery system 10.

[0050] Figures 7 and 8 provide further details regarding the deployment sheath 16. FIG. 7 is a side view of a portion of the deployment sheath 16, and FIG. 8 is a cross-sectional view of the deployment sheath 16, showing that the deployment sheath 16 includes an inner polymer layer 17 and an outer polymer layer 19, and an elongation reducing member 42 is disposed between the inner polymer layer 17 and the outer polymer layer 19. In some cases, the inner polymer layer 17 and / or the outer polymer layer 19 may contribute to reducing the stretchability of the deployment sheath 16. In some examples, the degree of reduction in stretchability of the deployment sheath 16 may be considered as the sum of the degrees of stretchability reduction potentially provided by each component forming the deployment sheath 16.

[0051] In some cases, the inner polymer layer 17 may be a lubricious polymer material such as, but not limited to, a perfluorinated material. In some cases, the inner polymer layer 17 may be PTFE (polytetrafluoroethylene). In some cases, the outer polymer layer 19 may be formed of any suitable polymer material. As an example, the outer polymer layer 19 may be formed of a nylon material such as those available from Vestamid. Pebax materials can also be used. The outer polymer layer 19 may be crosslinked, for example. Although the deployment sheath 16 has been described as having an elongation reducing member 42 disposed between the inner polymer layer 17 and the outer polymer layer 19, in some cases, the deployment sheath 16 may include one or more additional layers. Each of the additional layers may be configured to limit stretchability, for example.

[0052] Returning to FIG. 6, the deployment sheath 16 may further include a radiopaque marker or band 44. Generally, the marker band 44 may be disposed adjacent to the distal end 46 of the deployment sheath 16. One or more marker bands 44 may be disposed along other portions of the deployment sheath 16 or other portions of the stent delivery system 10. The marker band 44 may enable the distal end 46 of the deployment sheath 16 to be visualized under fluoroscopy during advancement of the stent delivery system 10 and / or deployment of the stent 34.

[0053] Also, FIG. 6 shows the distal end 46 of the deployment sheath 16 that abuts the proximal ridge 30. In this configuration, the stent 34 can be flushed (e.g., to remove air bubbles) by flowing fluid through the inner member 20 and the port 24. Because of the flat portion 32, the fluid can flow out of the deployment sheath 16 by passing through the gap formed between the inner member 20 and the deployment sheath 16 at the flat portion 32.

[0054] FIG. 9 shows the distal portion 48 of the handle 14. Here, it can be seen that the handle 14 is attached to the outer member 50. The outer member 50 is disposed around the deployment sheath 16 and can extend along a portion of the length of the deployment sheath 16. Thus, along at least a portion of the length of the stent delivery system 10, the stent delivery system 10 can include four coaxial tubular structures, namely, the outer member 50, the deployment sheath 16, the intermediate tube 36, and the inner member 20. In at least some embodiments, the outer member 50 can provide several desirable advantages to the stent delivery system 10. For example, the outer member 50 can include or be formed from a lubricious material that can reduce the friction associated with retracting the deployment sheath 16 proximally. Also, the outer member 50 can include a surface that can be clamped or latched so that the position of the stent delivery system 10 can be maintained without adversely affecting the retraction of the deployment sheath 16 (otherwise, it can be affected when the deployment sheath 16 is clamped). Also, many other desirable advantages can be achieved by using the outer member 50.

[0055] The deployment sheath 16 may pass proximally through the outer member 50 and extend proximally back within the handle 14. Also, both the intermediate tube 36 and the inner member 20 are returned within the handle 14 and disposed within the deployment sheath 16. The proximal end of the deployment sheath 16 may be attached to the gear rack assembly 52 using a fastener or clip 54, as shown in FIG. 10. Thus, proximal movement of the gear rack assembly 52 may cause similar proximal movement of the deployment sheath 16. The gear rack assembly 52 may include a plurality of teeth or gears 56. In practice, the teeth 56 may be configured to engage corresponding teeth or a gear arrangement (not shown) on the thumbwheel 18. As a result, rotation of the thumbwheel 18 may be utilized to proximally retract the gear rack assembly 52, and thus the deployment sheath 16, via the gear 56 and its gear arrangement. Other structural arrangements may also be utilized to achieve proximal retraction of the gear rack assembly 52 through actuation of the thumbwheel 18 or any other suitable actuating member.

[0056] Also, the gear rack assembly 52 may include a flared proximal end 58. When properly assembled, the body of the gear rack assembly 52 may be disposed within the handle 14 and the proximal end 58 may be disposed along the exterior of the handle 14. The gear rack assembly 52 may have an internally formed slot or groove 64 (not shown in FIG. 6, seen in FIG. 11). The groove 64 may extend along the length of the gear rack assembly 52, including along the proximal end 58. Since the proximal end 58 may generally be located in the vicinity of the proximal end of the inner member 20, the flared shape of the proximal end 58 and the orientation of the groove 64 may enable the proximal end 58 to function as a guidewire introducer or funnel that may assist a clinician in placing, holding, removing, and / or exchanging a guidewire extending through the inner member 20.

[0057] The materials that can be used for the various components of the stent delivery system 10 (and / or other systems disclosed herein) can include those commonly associated with medical devices. For simplicity, in the following description, reference is made to the shaft 12, the deployment sheath 16, and the inner member 20. However, this is not intended to limit the present invention and can also be applied to other similar members and / or components of the members or systems disclosed herein.

[0058] The shaft 12, the deployment sheath 16, the inner member 20, and / or other components of the stent delivery system 10 can be made of metal, metal alloy, polymer (some examples of which are disclosed below), metal-polymer composites, combinations thereof, etc., or any other suitable material. Some examples of suitable metals and metal alloys include stainless steels such as 304V, 304L, and 316LV stainless steel, mild steel, nickel-titanium alloys such as linear elastic and / or superelastic nitinol, other nickel alloys such as nickel-chromium-molybdenum alloys (e.g., UNS:N06625 such as INCONEL® 625, UNS:N06022 such as HASTELLOY® C-22®, UNS:N10276 such as HASTELLOY® C276®, other HASTELLOY® alloys, etc.), nickel-copper alloys (e.g., UNS:N04400 such as MONEL® 400, NICKELVAC® 400, NICORROS® 400, etc.), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS:R30035 such as MP35-N®), nickel-molybdenum alloys (e.g., UNS:N10665 such as HASTELLOY® ALLOY B2®), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten or tungsten alloys, cobalt-chromium alloys, cobalt-chromium-molybdenum alloys (e.g., UNS:R30003 such as ELGILOY®, PHYNOX®, etc.), platinum-enriched stainless steel, titanium, combinations thereof, or any other suitable material.

[0059] As noted above, within the family of commercially available nickel-titanium or nitinol alloys, there are those that exhibit useful mechanical properties that are chemically similar but different in kind from the conventional shape memory and superelastic types of the category called "linear elastic" or "non-superelastic." Linear elastic and / or non-superelastic nitinol can be distinguished from superelastic nitinol in that it does not exhibit a substantial "superelastic plateau" or "flag region" as shown by superelastic nitinol in its stress / strain curve. Instead, linear elastic and / or non-superelastic nitinol increases stress substantially linearly, or in a somewhat linear relationship but not necessarily perfectly linear, as recoverable strain increases, until plastic deformation begins, or at least in a more linear relationship than the superelastic plateau and / or flag region seen in superelastic nitinol. Thus, for the purposes of the present disclosure, linear elastic and / or non-superelastic nitinol can also be referred to as "substantially" linear elastic and / or non-superelastic nitinol.

[0060] In some cases, superelastic nitinol can tolerate up to about 8% strain before plastic deformation, whereas linear elastic and / or non-superelastic nitinol can be distinguished from superelastic nitinol in that it can tolerate up to about 2-5% strain while remaining substantially elastic (e.g., before plastic deformation). Both of these materials can be distinguished from other linearly elastic materials, such as stainless steel, which can tolerate only about 0.2-0.44% strain before plastic deformation (which can also be distinguished based on its composition).

[0061] In some embodiments, the linear elastic and / or non-superelastic nickel-titanium alloy is an alloy that does not exhibit any martensite / austenite phase change detectable by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) over a wide temperature range. For example, in some embodiments, the linear elastic and / or non-superelastic nickel-titanium alloy has no martensite / austenite phase change detectable by DSC and DMTA in the range of about -60 degrees Celsius (°C) to about 120 °C. Thus, the mechanical bending properties of such materials may generally be little affected by temperature over this very wide temperature range. In some embodiments, the mechanical bending properties of the linear elastic and / or non-superelastic nickel-titanium alloy at ambient temperature or room temperature are substantially the same as the mechanical properties at body temperature, e.g., in that they do not exhibit a superelastic plateau and / or flag region. In other words, the linear elastic and / or non-superelastic nickel-titanium alloy maintains its linear elastic and / or non-superelastic properties and / or characteristics over a wide temperature range and essentially has no yield point.

[0062] In some embodiments, the linear elastic and / or non-superelastic nickel-titanium alloy may be nickel in the range of about 50 to about 60 weight percent, with the balance being essentially titanium. In some embodiments, the composition is nickel in the range of about 54 to about 57 weight percent. An example of a suitable nickel-titanium alloy is the FHP-NT alloy commercially available from Furukawa Techno-Material Co., Ltd. located in Kanagawa Prefecture, Japan. Some examples of nickel-titanium alloys are disclosed in U.S. Pat. Nos. 5,238,004 and 6,508,803, which are incorporated herein by reference. Other suitable materials include ULTANIUM (trademark) (available from Neo-Metrics) and GUM METAL (trademark) (available from Toyota). In some other embodiments, a superelastic alloy, e.g., superelastic nitinol, may be used to achieve the desired properties.

[0063] In at least some embodiments, some or all of the shaft 12, the deployment sheath 16, and the inner member 20 may be doped with a radiopaque material, including those listed herein, or other suitable radiopaque materials, made from such materials, or include such materials.

[0064] In some embodiments, the stent delivery system 10 is provided with a degree of MRI compatibility. For example, in order to enhance the compatibility with a magnetic resonance imaging (MRI) machine, it may be desirable to make the shaft 12, the deployment sheath 16, and the inner member 20 in a manner that provides a degree of MRI compatibility. For example, the shaft 12, the deployment sheath 16, the inner member 20, or portions thereof may be made of a material that does not substantially distort the image and does not generate substantial artifacts (artifacts are gaps in the image). For example, certain ferromagnetic materials may not be suitable because they can generate artifacts in the MRI image. Also, the shaft 12, the deployment sheath 16, the inner member 20, or portions thereof may be made of a material that can be imaged by an MRI machine. Some materials exhibiting these properties include, for example, tungsten, cobalt-chromium-molybdenum alloys (such as UNS:R30003 like ELGILOY®, PHYNOX®, etc.), nickel-cobalt-chromium-molybdenum alloys (such as UNS:R30035 like MP35-N®), nitinol, and the like.

[0065] Some examples of suitable polymers that can be used to form the shaft 12, the deployment sheath 16, the inner member 20, and / or other components of the stent delivery system 10 include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, e.g., DELRIN® available from DuPont), polyether block ester, polyurethane (e.g., polyurethane 85A), polypropylene (PP), polyvinyl chloride (PVC), polyether-ester (e.g., ARNITEL® available from DSM Engineering Plastics), ether or ester copolymers (e.g., butylene / poly(alkylene ether) phthalate, and / or other polyester elastomers such as HYTREL® available from DuPont), polyamide (e.g., DURETHAN® available from Bayer or CRISTAMID® available from Elf Atochem), elastomeric polyamide, block polyamide / ether, polyether block amide (PEBA, e.g., available under the trade name PEBAX®), ethylene vinyl acetate copolymer (EVA), silicone, polyethylene (PE), Marlex® high density polyethylene, Marlex® low density polyethylene, linear low density polyethylene (e.g., REXELL®), polyester, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polytrimethylene terephthalate, polyethylene naphthalate (PEN), polyether ether ketone (PEEK), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polyparaphenylene terephthalamide (e.g., KEVLAR®), polysulfone, nylon, nylon-12 (EMS AmericanThose available from Grilon), such as GRILAMID (registered trademark), perfluoro(propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefin, polystyrene, epoxy, polyvinylidene chloride (PVdC), poly(styrene-b-isobutylene-b-styrene) (e.g., SIBS and / or SIBS50A), polycarbonate, ionomer, biocompatible polymer, other suitable materials, mixtures, combinations, or copolymers thereof, polymer / metal composites, etc. may be included. In some embodiments, the sheath is mixable with liquid crystal polymer (LCP). For example, the mixture can contain up to about 6% LCP.

[0066] In some embodiments, the outer surface of the stent delivery system 10 may include a coating, such as a lubricious, hydrophilic, protective, or other type of coating. Hydrophobic coatings, such as fluoropolymers, provide a dry lubricity that improves the handling and exchange of the device. Lubricious coatings improve maneuverability and lesion crossing ability. Suitable lubricious polymers include silicones, etc., as well as high-density polyethylene (HDPE), polytetrafluoroethylene (PTFE), polyarylene oxide, polyvinyl pyrrolidone, polyvinyl alcohol, hydroxyalkyl cellulose derivatives, polymers such as algin, saccharides, caprolactone, and mixtures and combinations thereof. Hydrophilic polymers can be blended among themselves or with a prescribed amount of water-insoluble compounds (including some polymers) to obtain a coating having suitable lubricity, adhesion, and solubility. Some other examples of such coatings and the materials and methods used to create such coatings can be found in U.S. Patent Nos. 6,139,510 and 5,772,609, the entire disclosures of which are incorporated herein by reference.

[0067] This disclosure should be understood to be merely exemplary in many respects. Without exceeding the scope of the present invention, changes can be made in detail, particularly with regard to the shape, size, and arrangement of steps. The scope of the present invention is, of course, defined by the language expressed in the appended claims.

Claims

**Claim 1** A stent delivery system configured to deliver and deploy a self-expanding stent while reducing energy loss within the stent delivery system, comprising: an inner member including a stent receiving region configured to receive a self-expanding stent; a proximal member coaxially extending around the inner member and having a distal end terminating in the vicinity of the stent receiving region, the proximal member including a buckling reduction member configured to reduce collapsibility within the proximal member; a deployment sheath coaxially extending around the inner member and the proximal member, the deployment sheath being movable between a distal position in which the self-expanding stent is constrained by the deployment sheath and a proximal position in which the self-expanding stent is no longer constrained by the deployment sheath, the deployment sheath including an elongation reduction member configured to reduce extensibility within the deployment sheath; The stent delivery system is provided, and the reduced collapsibility of the proximal member and the reduced extensibility of the deployment sheath reduce energy loss within the stent delivery system. **Claim 2** a gear rack assembly coupled to the deployment sheath; a handle coupled to the inner member and the deployment sheath; further comprising: The handle includes an actuating member, and the actuating member is coupled to the gear rack assembly such that the longitudinal positions of the gear rack assembly and the deployment sheath relative to the stent receiving region change upon actuation of the actuating member. The stent delivery system according to claim 1. **Claim 3** The deployment sheath includes an inner polymer layer and an outer polymer layer, and the elongation reduction member is disposed between the inner polymer layer and the outer polymer layer. The stent delivery system according to claim 1 or 2. **Claim 4** The elongation reduction member includes a first braided member. The stent delivery system according to any one of claims 1 to 3. **Claim 5** The first braided member is configured to resist elongation in response to an applied tensile force. The stent delivery system according to claim 4. **Claim 6** The buckling reduction member includes a second braided member. The stent delivery system according to any one of claims 1 to 5. **Claim 7** The second braided member is configured to resist buckling in response to an applied compressive force. The stent delivery system according to claim 6. **Claim 8** A stent delivery system configured to improve force transmission efficiency within the stent delivery system and deliver and release a self-expanding stent, an inner member including a stent receiving region configured to receive the self-expanding stent, a proximal member coaxially extending around the inner member and extending proximally from near the stent receiving region, the proximal member including a buckling reduction member configured to reduce compressibility within the proximal member, a deployment sheath coaxially extending around the inner member and the proximal member, the deployment sheath being movable between a distal position where the self-expanding stent is constrained by the deployment sheath and a proximal position where the self-expanding stent is no longer constrained by the deployment sheath, the deployment sheath including an elongation reduction member configured to reduce extensibility within the deployment sheath, wherein the reduced compressibility of the proximal member and the reduced extensibility of the deployment sheath improve force transmission efficiency within the stent delivery system. A stent delivery system.

9. The stent delivery system according to claim 8, wherein the deployment sheath includes an inner polymer layer and an outer polymer layer, and the elongation reduction member is disposed between the inner polymer layer and the outer polymer layer.

10. The stent delivery system according to claim 8 or 9, wherein the elongation reduction member includes a first braided member.

11. The stent delivery system according to any one of claims 8 to 10, wherein the buckling reduction member is encapsulated within a polymer layer.

12. The stent delivery system according to any one of claims 8 to 11, wherein the buckling reduction member includes a second braided member.

13. A stent delivery system configured to deliver and release a self-expanding stent, an inner member including a stent receiving region configured to receive the self-expanding stent, a proximal buffer coaxially extending around the inner member, the proximal buffer including a buckling reduction braided member encapsulated within a polymer layer, A deployment sheath that extends coaxially around the inner member and the proximal buffer portion, includes a stretch reduction braided member disposed between an inner polymer layer and an outer polymer layer, and is movable between a distal position where the self-expanding stent is constrained by the deployment sheath and a proximal position where the self-expanding stent is no longer constrained by the deployment sheath. A stent delivery system comprising the same. **Claim 14** The stent delivery system according to claim 13, wherein the buckling reduction braided member is configured to resist collapsing in response to an applied compressive force. **Claim 15** The stent delivery system according to claim 13 or 14, wherein the stretch reduction braided member is configured to resist stretching in response to an applied tensile force.

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