Friction pad for deployment and resheathing of endovascular implants

Abstract

An endovascular implant delivery system includes an endovascular implant having a tubular implant body and a central implant lumen. The system also includes a delivery catheter having an elongate sheath body and an inner sheath lumen. The endovascular implant is disposed within the inner sheath lumen when in a compressed delivery configuration. The system also includes a pusher member assembly slidably disposed in the inner sheath lumen. The pusher member assembly includes an elongate pusher member and a friction pad having a radially compressed state and a radially expanded state. The friction pad is disposed within the central implant lumen when in the radially compressed state. The friction pad includes a tubular pad body and a central pad lumen in which the pusher member is disposed. The tubular pad body has an elastomeric matrix material and an adjustment element embedded within and extending axially along the elastomeric matrix material.

Description

Technical Field

[0001] The present disclosure relates generally to minimally invasive assemblies for delivering intermediate implants, and more particularly to delivery assemblies for delivering medical implants, such as tubular stents or shunts, to a target implantation site in a patient's vasculature. Background Art

[0002] The use of intravascular implants such as stents, stent grafts, shunts, vascular occlusive devices, vena cava filters, etc. has become an effective method for treating many types of vascular diseases. Typically, a suitable intravascular implant is inserted into the patient's vascular system and a delivery system is used to navigate through the vascular system to the desired target site. Using currently available delivery systems, virtually any target site in the patient's vascular system can be accessed, including the coronary arteries, brain, and peripheral vasculature.

[0003] In a typical intravascular medical device delivery operation, a delivery catheter is introduced into the patient's vascular system percutaneously by a guide wire and / or by a guide sheath. Then the open distal end of the delivery catheter is navigated to the target implantation site using well-known technology. The intravascular implant is delivered through the lumen of the delivery catheter in a compressed (i.e., reduced diameter) delivery configuration. For example, a pusher member assembly with a pusher member (e.g., core wire) can be used to push the intravascular implant through the lumen of the delivery catheter, and the intravascular implant is temporarily attached to the pusher member. When the intravascular implant is located near the desired position in the vascular system, the intravascular implant can then be deployed (e.g., by withdrawing the delivery catheter relative to the intravascular implant) from the open distal end of the delivery catheter and placed in an expanded (i.e., increased diameter) deployment configuration to engage with the inner wall of the blood vessel. A radiopaque marker can be located at the distal tip of the delivery catheter so that the implantation site of the intravascular implant can be estimated under the assistance of medical imaging techniques (e.g., fluoroscopy).

[0004] In one method of delivering an intravascular implant, the intravascular implant may be mounted on a balloon, which may then be inflated to expand the intravascular implant radially outward to engage the inner wall of the vessel. In another method of delivering an intravascular implant, the intravascular implant may be self-expanding and loaded into the lumen of a catheter in an elastically compressed state, such that the intravascular implant, once deployed from the open distal end of the catheter, elastically expands without the assistance of a balloon.

[0005] Typically, once the intravascular implant is at least partially deployed from the delivery catheter, the physician may determine that the actual implantation site of the intravascular implant may be located away from the target implantation site of the intravascular implant, and therefore is clinically undesirable. For a variety of reasons, the actual implantation site of the intravascular implant may be clinically undesirable. For example, if the intravascular implant is a stent for bridging the neck of an aneurysm or diverting the flow from an aneurysm or a blood vessel, it is necessary to accurately implant the stent at the target implantation site. If the stent fails to cover the entire aneurysm, or the stent is located at a bend that may cause thrombosis or stroke, or the stent covers another blood vessel, it may be necessary to reposition the intravascular stent. In the case of a self-expanding intravascular implant, if the intravascular implant has not yet been deployed from the delivery catheter beyond the point of no return (i.e., the point where the intravascular implant cannot be retracted into the delivery catheter), the intravascular stent can be re-sheathed in the delivery catheter and repositioned so that the intravascular implant can be re-deployed at the target implantation site.

[0006] Referring to FIGS. 1-2 , an embodiment of a delivery system 1 for delivering an intravascular implant 2 at a target implantation site 3 within a blood vessel 4 (as shown in FIGS. 3A-3B and 4A-4B ). The delivery system 1 includes a delivery catheter 5 having an internal lumen 6, and a pusher member assembly 7 disposed within the internal lumen 6 of the delivery sheath 5. The pusher member assembly 7 includes a pusher member 8 and a proximal buffer 9a and a distal buffer 9b attached to the pusher member 8, thereby forming an annular space 10 between the buffers 9a, 9b. The proximal buffer 9a can be used as a radiopaque marker to indicate the proximal end of the intravascular implant 2, so that the complete deployment of the intravascular implant 2 from the delivery catheter 5 can be confirmed. The distal buffer 9b can be used as a radiopaque marker, which indicates a point of no return when the intravascular implant 2 is deployed from the delivery catheter 5, after which the intravascular implant 2 may no longer be re-sheathed into the delivery catheter 5. Other radiopaque markers (not shown) can be located at the distal end of the delivery catheter 5 and other locations along the pusher member 8. The pusher member assembly 7 may also include a protective device 11 located at the distal end of the intravascular implant 2. The pusher member assembly 7 also includes an elastomeric friction pad 12, which is arranged on the pusher member 8 in the annular space 10 between the buffers 9a, 9b. The proximal buffer 9a and the distal buffer 9b are used to hold the friction pad 12 therebetween. The pusher member assembly 7 also includes an atraumatic distal portion 13 attached to the distal end of the pusher member 8.

[0007] The intravascular implant 2 is disposed within the interior lumen 6 of the delivery catheter 5 between the outer surface 14 of the friction pad 12 and the inner surface 15 of the delivery catheter 5. The friction pad 12 is disposed within the interior lumen 6 of the delivery catheter 5 in a compressed state such that the friction pad 12 applies a radially outward force 16 against the inner surface 17 of the intravascular implant 2, while the interior lumen 6 of the delivery catheter 5 applies a radially inward force 18 against the outer surface 19 of the intravascular implant 2, as best shown in FIG. 2. In this manner, the intravascular implant 2 is frictionally engaged with the pusher member assembly 7 such that when the pusher member assembly 7 and the delivery catheter 5 are axially translated relative to each other (e.g., by translating the delivery catheter 5 in a proximal direction 18 while holding the pusher member assembly 7 in place), the intravascular implant 2 moves in unison with the pusher member assembly 7 to deploy the intravascular implant 2 from the distal port 19 of the delivery catheter 5 and into the blood vessel 4, as shown in FIGS. 3A and 3B.

[0008] Because the tensile strength of the intravascular implant 2 alone is very low, the friction pad 12 not only facilitates the deployment of the intravascular implant 2, but also facilitates the re-sheathing of the intravascular implant 2 within the interior lumen 6 of the delivery catheter 5 (e.g., by translating the delivery catheter 5 in the distal direction 21 while holding the pusher member assembly 7 in place), as shown in Figures 4A and 4B. As long as the intravascular implant 2 has not been deployed from the delivery catheter 5 beyond the point of no return (i.e., as long as the distal bumper 9b remains in the interior lumen 6 of the delivery catheter 5, indicating that the friction pad 12, which will tend to expand outside the constraints of the delivery catheter 5, is completely within the interior lumen 6 of the delivery catheter 5), the intravascular implant 2 can be re-sheathed back into the delivery catheter 5 with the help of the friction pad 12.

[0009] The performance characteristics of the friction pad 12 should be selected in a manner that frictionally engages the intravascular implant 2 to achieve the deployment and re-sheathing functions of the intravascular implant 2. For example, the friction pad 12 should have a low lateral bending stiffness paired with a low radial strength (high radial compressibility / expandability) that can be customized or calibrated so that the friction pad 12 engages the intravascular implant 2 while avoiding high orbital / re-sheathing forces that would otherwise prevent deployment, re-sheathing, or re-deployment of the intravascular implant 2 without damaging the intravascular implant 2 or generating particles from the ends of the intravascular implant 2. Specifically, in order to frictionally engage the intravascular implant 2 without excessively generating high tracking / resheathing forces, it is desirable that sufficient outward radial force 16 be applied by the friction pad 12 to the inner surface 17 of the intravascular implant 2, but not too great an outward radial force that generates excessive friction between the outer surface of the intravascular implant 2 and the inner surface of the delivery catheter 5, which may otherwise impede translation of the intravascular implant 2 within the interior lumen 6 of the delivery catheter 5 and / or resheathing of the intravascular implant 2 back into the interior lumen 6 of the delivery catheter 5. In addition, it is desirable that the lateral flexibility of the friction pad 12 be sufficiently low so that the friction pad 12 easily conforms to bends in the patient's vasculature, so that the friction pad 12 more easily tracks through bends in the patient's vasculature, thereby facilitating axial translation between the pusher member assembly 7 and the delivery catheter 5 as the friction pad 12 traverses bends in the patient's vasculature. Traditionally, an elastomeric friction pad having a low durometer (or elastic modulus) would provide the friction pad with such sufficiently low bending stiffness and low radial strength.

[0010] However, as shown in Fig. 5, the elastomeric friction pad 12 composed of a low durometer material has a relatively low columnar strength, making it susceptible to radially outward bulging (shown in dashed lines) in the radial direction 22 in response to an axial compressive force 24, such as caused by increased resistance to translation of the intravascular implant 2 within the interior lumen 6 of the delivery catheter 5 during deployment and / or re-sheathing of the intravascular implant 2. Such radial outward bulging of the friction pad 12 can prohibitively increase the tracking / re-sheathing force of the intravascular implant 2, while also increasing the likelihood of particle generation at the end of the intravascular implant 2. In some cases, the increased tracking / re-sheathing force may even cause the friction pad 12 to prolapse on the proximal bumper 9a or the distal bumper 9b, thereby rendering the delivery system 1 unusable.

[0011] Therefore, during deployment and / or re-sheathing of the intravascular implant, there is still a need to minimize the radial outward bulge of the friction pad while maintaining the desired radial compressibility / expandability and lateral flexibility of the friction pad in the presence of increased resistance to translation of the intravascular implant within the lumen of the delivery catheter. Summary of the invention

[0012] According to the present invention, an intravascular implant delivery system includes an intravascular implant (e.g., one of a stent, a stent graft, a shunt, a vascular occlusion device, and a vena cava filter) having a compressed delivery configuration and an expanded deployment configuration. The intravascular implant includes a tubular implant body and a central implant lumen extending axially through the tubular implant body. The intravascular implant delivery system also includes a delivery catheter having an elongated sheath body and an inner sheath lumen extending axially through the sheath body. The intravascular implant is arranged in the inner sheath lumen when in the compressed delivery configuration. The intravascular implant delivery system also includes a pusher member assembly that can be slidably arranged in the inner sheath lumen. The pusher member assembly includes an elongated pusher member (e.g., a delivery wire) and a friction pad having a radially compressed state and a radially expanded state. The friction pad is arranged in the central implant lumen when in the radially compressed state, and includes a tubular pad body and a central pad lumen extending axially through the tubular pad body. The pusher member is arranged in the central pad lumen.

[0013] In one embodiment, the pusher member assembly further comprises a proximal buffer and a distal buffer attached to the pusher member, thereby forming an annular space between the proximal buffer and the distal buffer, wherein the friction pad is disposed within the annular space. In another embodiment, the pusher member assembly and the delivery catheter are capable of axial translation relative to each other, and the friction pad is configured to frictionally engage the intravascular implant when the pusher member assembly and the delivery catheter are axially translated relative to each other, so that the intravascular implant and the pusher member assembly are axially translated in unison with each other to deploy the intravascular implant from the inner sheath lumen to its expanded expanded configuration. In this embodiment, the friction pad may be configured to frictionally engage the intravascular implant when the pusher member assembly and the delivery catheter are axially translated relative to each other, so that the intravascular implant and the pusher member assembly are axially translated in unison with each other to re-sheath the intravascular implant back to its compressed delivery configuration within the inner sheath lumen when it is at least in a partially expanded expanded configuration. The tubular pad body has an elastomeric matrix material forming the tubular pad body and at least one adjustment element embedded in the elastomeric matrix material and extending axially along the elastomeric matrix material. In one embodiment, a plurality of adjustment elements are arranged circumferentially in the elastomeric matrix material. In another embodiment, the tubular pad body is cylindrical. In yet another embodiment, the elastomeric matrix material of the friction pad is polyether block amide (PEBA). In yet another embodiment, each of the adjustment elements is elongated. In this case, each of the elongated adjustment elements may extend parallel to the longitudinal axis of the tubular pad body.

[0014] According to a first aspect of the invention, each of the adjustment elements has mechanical properties that are different from the mechanical properties of the elastomeric matrix material. In one embodiment, the adjustment element increases the ratio of the columnar strength to the radial strength of the tubular pad body. As an example, the elastic modulus of each of the adjustment elements may be greater than the elastic modulus of the elastomeric matrix material, and the columnar strength of the tubular pad body may be increased. In this case, each of the adjustment elements may be a solid beam and may have a hardness in the range of 25A to 35D. As another example, the elastic modulus of each of the adjustment elements may be less than the elastic modulus of the elastomeric matrix material, and the radial strength of the friction pad may be reduced. In this case, each of the adjustment elements may be gel or air, and may have a hardness greater than 35D.

[0015] According to a second aspect of the invention, the adjustment element increases the ratio of the columnar strength to the radial strength of the tubular pad body. As an example, the elastic modulus of each of the adjustment elements may be greater than the elastic modulus of the elastomeric matrix material, and the columnar strength of the tubular pad body may be increased. In this case, each of the adjustment elements may be a solid beam and may have a hardness in the range of 25A to 35D. As another example, the elastic modulus of each of the adjustment elements may be less than the elastic modulus of the elastomeric matrix material, and the radial strength of the friction pad may be reduced. In this case, each of the adjustment elements may be gel or air, and may have a hardness greater than 35D.

[0016] According to a third aspect of the invention, the adjustment element increases the columnar strength of the tubular pad body. For example, the elastic modulus of each of the adjustment elements may be greater than the elastic modulus of the elastomeric matrix material. In this case, each of the adjustment elements may be a solid beam and may have a hardness in the range of 25A to 35D.

[0017] According to a fourth aspect of the invention, the adjustment element reduces the radial strength of the tubular pad body. For example, the elastic modulus of each of the adjustment elements may be less than the elastic modulus of the elastomeric matrix material. In this case, each of the adjustment elements may be gel or air and may have a hardness greater than 35D.

[0018] Other and further aspects and features of embodiments of the disclosed invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings illustrate the design and utility of preferred embodiments of the present invention, wherein similar elements are represented by common reference numerals. It should be noted that the figures are not drawn to scale, and in all figures, elements with similar structures or functions are represented by the same reference numerals. It should also be noted that the figures are intended only to facilitate the description of the embodiments. They are not intended to be an exhaustive description of the present invention or to be a limitation on the scope of the present invention, which is limited only by the appended claims and their equivalents. In addition, the illustrated embodiments of the disclosed invention do not need to have all the aspects or advantages shown. The aspects or advantages described in conjunction with the specific embodiments of the disclosed invention are not necessarily limited to the embodiment, and even if not shown as such, they can be practiced in any other embodiment. In order to better understand how to obtain the above and other advantages and purposes of the present invention, a more specific description of the present invention briefly described above will be presented by reference to the specific embodiments of the present invention shown in the accompanying drawings. It should be understood that these drawings depict only typical embodiments of the present invention, and therefore should not be considered as limitations on its scope, and the present invention will be described and explained with additional specificity and detail by using the accompanying drawings, in which:

[0020] 1 is a longitudinal cross-sectional view of a prior art delivery system for delivering an intravascular implant into a patient.

[0021] 2 is a cross-sectional view of the delivery system of FIG. 1 taken along line 2 - 2 .

[0022] 3A-3B are plan views illustrating a prior art method of deploying an intravascular implant within the vasculature of a patient using the delivery system of FIG. 1 .

[0023] 4A-4B are plan views illustrating a prior art method of resheathing an intravascular implant using the delivery system of FIG. 1 .

[0024] 5 is a perspective view showing an elastomeric friction pad of a prior art delivery system, particularly showing the friction pad bulging radially in response to a compressive force.

[0025] Figure 6 is a plan view of one embodiment of an intravascular implant delivery system constructed in accordance with the present invention.

[0026] Fig. 7A yes Figure 6 A plan view of the distal end of an intravascular implant delivery system.

[0027] Figure 7B yes Fig. 7A A cross-sectional plan view of the distal end of a pusher member assembly of an intravascular implant delivery system.

[0028] Figure 7C yes Figure 7BA cutaway perspective view of a pusher member assembly.

[0029] Fig.7D Is Figure 7B A view of a pusher member assembly carrying an intravascular implant.

[0030] Fig. 7E yes Figure 7B A close-up plan view of the distal tip of the pusher member assembly.

[0031] Figure 7F It was taken along line 7F-7F Fig. 7A A close-up plan view of a portion of an intravascular implant delivery system.

[0032] Figure 7G yes Fig. 7A A close-up plan view of the distal tip of an intravascular implant delivery system of , particularly showing the intravascular implant when deployed.

[0033] Figure 7H It was taken along line 7H-7H Figure 7F Cross-sectional view of an intravascular implant delivery system.

[0034] Fig.7I It was taken along route 7I-7I Figure 7G Cross-sectional view of an intravascular implant delivery system.

[0035] Fig. 8A yes Figure 7B A perspective view of a friction pad of a pusher member assembly, particularly showing a reduction in diameter of the friction pad in response to a radial compressive force.

[0036] Figure 8B yes Fig. 8A 0014] A perspective view of a friction pad, particularly showing that the diameter of the friction pad does not increase in response to an axial compressive force.

[0037] Fig. 9 yes Fig. 8A A perspective view of one embodiment of a friction pad.

[0038] Fig. 9A It is taken along route 9A-9A Fig. 9 Cross-sectional view of the friction pad.

[0039] Fig.10 yes Fig. 8A A perspective view of one embodiment of a friction pad.

[0040] Fig. 10A It was taken along route 10A-10A Fig.10 Cross-sectional view of the friction pad.

[0041] Fig.11 yes Fig. 8A A perspective view of one embodiment of a friction pad.

[0042] Fig.11A It is taken along route 11A-11A Fig.11 Cross-sectional view of the friction pad.

[0043] Fig.12 yes Fig. 8A A perspective view of one embodiment of a friction pad.

[0044] Fig. 12A It is taken along route 12A-12A Fig.12 Cross-sectional view of the friction pad.

[0045] Fig.13 yes Fig. 8A A perspective view of one embodiment of a friction pad.

[0046] Fig.13A It is taken along route 13A-13A Fig.13 Cross-sectional view of the friction pad.

[0047] Fig. 13B It was taken along line 13B-13B Fig.13 Cross-sectional view of the friction pad. DETAILED DESCRIPTION

[0048] refer to Figure 6 and 7A to 7I , an embodiment of an implant delivery system 100 constructed according to one embodiment of the present invention will be described. The implant delivery system 100 generally includes an intravascular implant 102, a delivery catheter 104 for delivering the intravascular implant 102 to a target site in the vascular system of a patient, and a pusher member assembly 106 (such as a pusher member assembly 106) that can be slidably disposed in the delivery catheter 104 for coaxially carrying the intravascular implant 102. Fig. 7A and Fig.7D shown).

[0049] Implant delivery system 100 can be used in "on-wire" configuration, wherein delivery catheter 104 is introduced into the patient on a previously introduced guide wire (not shown), and delivery catheter 104 extends over the entire length of the guide wire (not shown). Alternatively, implant delivery system 100 can be used in "quick exchange" configuration, wherein a guide wire (not shown) extends only through the distal portion of delivery catheter 104 from a guide wire port (not shown). In other alternative embodiments, implant delivery system 100 can be introduced into the patient after the guide wire is withdrawn, leaving a guide sheath for delivery catheter 104 to navigate through the patient's vascular system in the guide sheath.

[0050] like Fig. 7A and Fig.7D As best shown in , the intravascular implant 102 takes the form of, for example, a stent, a stent graft, a shunt, a vascular occlusive device, a vena cava filter, etc. The intravascular implant 102 generally includes a tubular implant body 108 having a proximal portion 110 and a distal portion 112, and a central implant lumen 114 extending axially completely through the tubular implant body 108. The tubular implant body 108 is constructed of an elastic material such that the intravascular implant 102 assumes a compressed delivery configuration when radially constrained within the delivery catheter 104, and automatically assumes an expanded deployed configuration when released from the constraint of the delivery catheter 104 (i.e., when the intravascular implant 102 is deployed from the delivery catheter 104). The tubular implant body 108 can be made of a variety of biocompatible materials, such as, for example, stainless steel, Elgiloy non-magnetic alloy, nickel, titanium, nitinol, shape memory polymers, or combinations thereof, and can be constructed using well-known techniques, such as by etching or cutting a pattern from a tube or sheet of stent material, or by braiding / interweaving one or more wires or ribbons into a desired shape and pattern. The intravascular implant 102 can include other components that are welded, bonded, or otherwise joined to one another, and can optionally include non-porous, impermeable biocompatible materials, coverings, and the like. The intravascular implant 102 can optionally include a bioactive agent or therapeutic agent carried by or coated on the inner or outer surface of the tubular implant body 108.

[0051] The delivery catheter 104 may, for example, include a length of about 50 cm to 300 cm, and typically about 60 cm to 200 cm. The delivery catheter 104 is configured to enter a body cavity, such as a blood vessel (e.g., an intracranial vein or a carotid artery), for the desired treatment in the target site. For example, the target site may be within a small diameter blood vessel having a lumen diameter of 2 mm to 12 mm, and may be accessed through a tortuous vascular path, which may involve multiple vascular turns and multiple vascular branches. In such cases, the delivery catheter 12 has a small suitable diameter and a flexible construction.

[0052] The delivery catheter 104 includes an elongated sheath body 116 having a proximal portion 118 and a distal portion 120, and an inner sheath lumen 122 extending axially completely through the sheath body 116 (at Fig. 7A1). The inner sheath lumen 122 terminates at a distal port 124 at the end of the distal portion 120 of the sheath body 116. When the implant delivery system 100 is in use, the proximal portion 118 of the sheath body 116 remains outside the patient's body and accessible to the operator, while the size and dimensions of the distal portion 120 of the sheath body 116 are designed to reach a remote location of the vasculature to deliver the intravascular implant 102 to a target location in the patient's body, such as an occlusion in a blood vessel, an occlusion in a blood vessel adjacent to an aneurysm neck, a bifurcated vessel, etc. The size of the inner sheath lumen 122 is designed to accommodate the radially contracting intravascular implant 102 and the longitudinal movement of the pusher member assembly 106.

[0053] The delivery catheter 104 includes a proximal adapter 126 attached to the proximal portion 118 of the sheath body 116. The proximal adapter 126 includes a central bore 128 (shown in phantom) in communication with the internal lumen 122 of the sheath body 116. The central bore 128 terminates in a proximal port 130 for allowing the pusher member assembly 106 to be loaded into the delivery catheter 104. The proximal adapter 126 also includes at least one fluid port 132 in fluid communication with the internal lumen 122 for introducing fluid into the delivery catheter 104 to hydrate the pusher member assembly 106 and the intravascular implant 102. The delivery catheter 104 also includes a conical radiopaque marker 134 disposed on the distal portion 120 of the sheath body 116 proximal to the distal port 124 so that the position of the distal tip of the delivery catheter 104 within the patient's vasculature or relative to the partially or fully deployed intravascular implant 102 can be identified using medical imaging techniques (e.g., fluoroscopy). The delivery catheter 104 also includes an atraumatic distal tip 136 attached to the distal tip of the sheath body 116 .

[0054] The delivery catheter 104 may include one or more regions or multiple regions with different configurations and / or characteristics along its length. For example, the outer diameter of the distal portion 120 of the sheath body 116 may be less than the outer diameter of the proximal portion 118 to reduce the profile of the distal portion 120 and facilitate navigation in a tortuous vascular system. In addition, the distal portion 120 may be more flexible than the proximal portion 118. Typically, the proximal portion 118 may be formed of a harder material than the distal portion 120, so that the proximal portion 118 has sufficient pushability to advance through the patient's vascular system, while the distal portion 120 may be formed of a more flexible material so that the distal portion 120 can remain flexible and more easily tracked on a guidewire to enter a remote location in a tortuous region of the vascular system. In some cases, the proximal portion 118 may include a reinforcing layer, such as an interlaced layer or a coiled layer, to enhance the pushability of the delivery catheter 104. The delivery catheter 104 may include a transition region between the proximal portion 118 and the distal portion 120.

[0055] The sheath body 116 may be constructed of a suitable polymer material, metal, and / or alloy, such as polyethylene, stainless steel, or other suitable biocompatible materials, or combinations thereof. Examples of suitable metals and metal alloys may include: stainless steel, such as 304V, 304L, and 316L stainless steel; nickel-titanium alloys, such as superelastic (i.e., pseudoelastic) or linear elastic nitinol; nickel-chromium alloys; nickel-chromium-iron alloys; cobalt alloys; tungsten or tungsten alloys; tantalum or tantalum alloys, gold or gold alloys, MP35-N (having a composition of approximately 35% Ni, 35% Co, 20% Cr, 9.75% Mo, up to 1% Fe, up to 1% Ti, up to 0.25% C, up to 0.15% Mn, and up to 0.15% Si), etc.; or other suitable metals, or combinations or alloys thereof. Examples of some suitable polymers may include, but are not limited to, polyoxymethylene (POM), polybutylene terephthalate (PBT), polyether block esters, polyether block amides (PEBA), fluorinated ethylene propylene (FEP), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyurethane, polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), polyimide, polyamide, polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polysulfone, nylon, perfluoro(propyl vinyl ether) (PFA), polyetheresters, polymer / metal composites, or mixtures, blends, or combinations thereof.

[0056] The sheath body 116 may include a braided shaft construction of stainless steel flat wires encapsulated or surrounded by a polymer coating. As a non-limiting example, HYDROLENE is a polymer coating that can be used to cover the outer portion of the sheath body 116. Of course, the implant delivery system 100 is not limited to a specific configuration or type of delivery catheter 104, and other configurations known to those skilled in the art can be used for the sheath body 116 of the delivery catheter 12. The inner sheath lumen 122 can be advantageously coated with a lubricating coating (not shown), such as PTFE, to reduce the friction between the sheath body 116 and the pusher member assembly 106 and the intravascular implant 102 when axially translated within the inner lumen 122.

[0057] The pusher member assembly 114 is slidably disposed within the interior lumen 122 of the delivery catheter 104, with the intravascular implant 102 coaxially disposed between the delivery catheter 104 and the pusher member assembly 114. The pusher member assembly 114 is configured to engage the intravascular implant 102 upon axial translation of the pusher member assembly 114 relative to the delivery catheter 104 to deliver the intravascular implant 102 to a target site of the patient or to re-sheath the intravascular implant 102 back into the delivery catheter 104. The interface between the pusher member assembly 114 and the intravascular implant 102 will be described in further detail below.

[0058] The pusher member assembly 114 generally includes an elongated pusher member in the form of a delivery wire 138 having a proximal portion 140 extending proximally from a proximal adapter 126 of the delivery catheter 104 and which can be grasped by a physician to axially translate the pusher member assembly 114 within the internal lumen 122 of the delivery catheter 104; a distal portion 142 that carries the intravascular implant 102; and a transition portion 144 between the proximal portion 140 and the distal portion 142 for facilitating tracking of the pusher member assembly 114 within the internal lumen 122 of the delivery catheter 104.

[0059] The delivery line 138 may be made of a conventional guide wire, a twistable cable tube or a hypotube. In either case, there are many materials that can be used for the delivery line 138 to achieve the desired performance usually associated with a medical device. Some examples may include metals, metal alloys, polymers, metal-polymer composites, etc., or any other suitable material (e.g., a composite material of nickel-titanium alloy, stainless steel, nickel-titanium alloy and stainless steel). In some cases, the delivery line 138 may be made of the same material along its length, or in some embodiments, may include a portion or section made of different materials. In some embodiments, the material used to construct the delivery line 138 is selected to give different flexibility and stiffness properties to different parts of the delivery line 138. For example, the proximal portion 140, the distal portion 142 and the transition portion 144 of the delivery line 138 may be formed of different materials, such as materials with different elastic moduli, thereby resulting in differences in flexibility. For example, the proximal portion 140 may be formed of stainless steel, and the distal portion 142 and the intermediate portion 144 may be formed of nickel-titanium alloy. However, any suitable material or material combination may be used for the delivery line 138 as needed.

[0060] In the illustrated embodiment, the pusher member assembly 106 also includes a coil 146 attached to a transition portion 144 of the delivery wire 138. The diameter of the transition portion 144 with the coil 146 is closely toleranced to the diameter of the inner sheath lumen 122 of the delivery catheter 104 to facilitate stable tracking of the pusher member assembly 106 through the inner sheath lumen 122, while the coil 146 provides columnar support to the pusher member assembly 106 proximal to the distal portion 142 on which the intravascular implant 102 is disposed, while maintaining lateral flexibility of the pusher member assembly 106. The diameter of the distal portion 142 is reduced, thereby providing a platform on which the intravascular implant 102 in its compressed delivery configuration and other components of the pusher member assembly 106 (described in further detail below) are disposed, such that the outer diameter of the compressed intravascular implant 102 and the distal portion of the pusher member assembly 106 also closely tolerances the diameter of the interior lumen 122 of the delivery catheter 104 [is this correct?].

[0061] Pusher member assembly 106 also includes a non-traumatic distal tip member 148 attached to the distal end of delivery line 138. Distal tip member 148 allows blood vessel selection and promotes implant delivery system 100 to navigate to the target implantation site. Distal tip member 148 can be preformed to present a curved geometry (and in a preferred embodiment, a J-shaped geometry) when unconstrained, and present a straight geometry when constrained. Alternatively, distal tip member 148 can be soft, such as being composed of a soft coil member. Distal tip member 148 can be optionally radiopaque, to use medical imaging technology (e.g., fluoroscopy) to help its visualization. Pusher member assembly 106 also includes a protective device 150, which is attached to delivery line 138 via one or more locking members 152 for covering the distal portion of intravascular implant 102.

[0062] The pusher member assembly 106 also includes a proximal buffer 154 attached to the distal portion 142 distal to the transition portion 144 of the delivery line 138; and a distal buffer 156 attached to the distal portion 142 of the delivery line 138 distal to the proximal buffer 154 (e.g., via epoxy bonding), thereby forming an annular space 158 between the buffers 154, 156. The buffers 154, 156 can be made of a suitable biocompatible material, such as stainless steel or nitinol. Although each of the buffers 154, 156 is disc-shaped and sized to slide within the inner sheath lumen 122 of the delivery catheter 104, in alternative embodiments, the buffers 154, 156 can have any suitable shape. In the illustrated embodiment, the diameter of the proximal buffer 154 is closely matched to the diameter of the inner sheath lumen 122, while the distal buffer 156 has a tip that tapers toward the distal direction to minimize tissue trauma. The outer surfaces of the bumpers 154 , 156 may impart low friction due to the material from which they are formed. Alternatively or additionally, the outer surfaces of the bumpers 154 , 156 may be coated with a lubricious coating, such as polytetrafluoroethylene (PTFE), to facilitate movement of the bumpers 154 , 156 through the inner sheath lumen 122 .

[0063] like Figure 7CAs best shown in FIG. 1 , the pusher member assembly 106 also includes a friction pad 162 coaxially disposed within an annular space 158 between the bumpers 154, 156 around the delivery wire 138. Specifically, the friction pad 162 includes a tubular pad body 164 having a proximal portion 166 and a distal portion 168, and a central pad lumen 170 extending axially completely through the tubular pad body 164 and in which the delivery wire 138 is disposed. The distal surface of the proximal bumper 154 is adapted to abut the proximal portion 166 of the friction pad 162 such that when the pusher member assembly 106 is translated in a distal direction relative to the delivery sheath 104 (e.g., during deployment of the intravascular implant 102 from the delivery catheter 104), the friction pad 162 is axially translated with the delivery wire 138. In contrast, the proximal surface of the distal bumper 154 is used to abut the distal portion 168 of the friction pad 162 so that when the pusher member assembly 106 is translated in a proximal direction relative to the delivery sheath 104 (for example, during re-sheathing of the intravascular implant 102 within the delivery catheter 104), the friction pad 162 translates axially with the delivery wire 138.

[0064] One or both of the buffers 154, 156 can be radiopaque and thus also serve as markers that can be used to help locate the intravascular implant 102 relative to the delivery catheter 104 using medical imaging techniques (e.g., fluoroscopy). For example, such a radiopaque proximal buffer 154 can indicate the proximal end of the intravascular implant 102, so that the complete deployment of the intravascular implant 102 from the delivery catheter 104 can be confirmed, while such a radiopaque distal buffer 156 can indicate the point of no return when the intravascular implant 102 is deployed from the delivery catheter 104, after which the intravascular implant 102 may no longer be re-sheathed into the delivery catheter 104. To this end, the buffers 154, 156 can be constructed of a suitable radiopaque material, such as platinum, gold, tungsten, or alloys thereof, or other metals. The pusher member assembly 106 can optionally include additional radiopaque elements at any location along its length to facilitate visualization thereof using medical imaging techniques (e.g., fluoroscopy).

[0065] like Figure 7F and Figure 7HAs shown, the intravascular implant 102 in its compressed delivery configuration is disposed within the interior lumen 122 of the delivery catheter 104 in a coaxial arrangement with the distal portion of the pusher member assembly 106. In the illustrated embodiment, the intravascular implant 102 extends from the proximal end of the friction pad 162 to the distal tip of the delivery wire 138, such that the proximal portion 110 of the tubular implant body 108 of the intravascular implant 102 and the friction pad 162 are coaxially arranged; that is, the proximal portion 110 of the tubular implant body 108 is disposed between the outer surface 172 of the friction pad 162 and the inner surface 174 of the delivery catheter 104. In the illustrated embodiment, although the intravascular implant 102 extends from only a portion of the friction pad 162 to the distal tip of the delivery wire 138, it should be understood that the friction pad 162 can extend along the entire friction pad 162 to the distal tip of the delivery wire 138 or to a point proximal to the distal tip of the delivery wire 138, but the intravascular implant 102 can alternatively extend over the entire friction pad 162. In contrast, as shown in FIG. Figure 7G and Fig.7I As shown, although the intravascular implant 102 in its expanded, deployed configuration is no longer disposed within the interior lumen 122 of the delivery catheter 104 , it may still be coaxially disposed with the distal portion of the pusher member assembly 106 .

[0066] The friction pad 162 is configured to cooperate with the intravascular implant 102 so that the pusher member assembly 106 engages the intravascular implant 102 when the intravascular implant 102 is in a compressed delivery configuration within the interior lumen 122 of the delivery catheter 104 (eg, Figure 7F and Figure 7G ), and releases the intravascular implant 102 when the intravascular implant 102 is in an expanded, deployed configuration outside the internal lumen 122 of the delivery catheter 104 (as shown in FIG. Figure 7G and Fig.7I To this end, the friction pad 162 is elastically deformable so that it can be in a radially compressed state ( Figure 7F and Figure 7G and shown) and radial expansion state ( Figure 7H The cross-sectional dimensions of the friction pad 162 when in the radially expanded state (e.g., Fig.7I The diameter d1 shown is larger than the cross-sectional dimension of the interior lumen 114 of the intravascular implant 102 when in the compressed delivery configuration within the interior lumen 122 of the delivery catheter 104 (eg, Figure 7H d2) to ensure that the friction pad 162 frictionally engages the intravascular implant 102 when it is in a radially compressed state within the interior lumen 114 of the compressed intravascular implant 102. In contrast, the cross-sectional dimensions of the friction pad 162 when in a radially expanded state (e.g., Fig.7IThe diameter d1 shown is smaller than the cross-sectional dimension of the interior lumen 114 of the intravascular implant 102 when in an expanded deployed configuration outside the interior lumen 122 of the delivery catheter 104 (eg, Fig.7I The diameter d3 shown in FIG. 1 is preferably larger than the diameter d4 of the intravascular implant 102 , thereby ensuring that the friction pad 162 releases the intravascular implant 102 when it is in a radially expanded state within the interior lumen 114 of the intravascular implant 102 .

[0067] Specifically, Figure 7H As best shown in the figure, when the intravascular implant 102 is in a compressed delivery configuration within the inner sheath lumen 122, the friction pad 162 is disposed in a radially compressed state within the central implant lumen 114 of the intravascular implant 102 (i.e., coaxially disposed between the delivery line 138 and the intravascular implant 102) such that the friction pad 162 applies a radially outward force 176 against the inner surface 178 of the intravascular implant 102, while the inner sheath lumen 122 applies a radially inward force 180 to the outer surface 182 of the intravascular implant 102. In this manner, the proximal portion 162 of the intravascular implant 102 is frictionally engaged (i.e., clamped) by the pusher member assembly 106 so that when the pusher member assembly 106 and the delivery catheter 104 are axially translated relative to each other (e.g., by translating the delivery catheter 104 in a proximal direction while maintaining the pusher member assembly 106 in an appropriate position), the entire intravascular implant 102 moves in unison with the pusher member assembly 106 to deploy the intravascular implant 102 from the distal port 124 of the delivery catheter 104 and into its expanded, deployed configuration within the vessel.

[0068] In contrast, Fig.7I As best shown in FIG. 1 , when the intravascular implant 102 is in an expanded, deployed configuration outside the interior lumen 122 of the delivery catheter 104, despite the friction pad 162 being coaxially disposed between the delivery wire 138 and the intravascular implant 102 in the radially expanded state, no radially outward force is applied to the inner surface 178 of the intravascular implant 102. In this manner, the intravascular implant 102 is no longer frictionally engaged (i.e., clamped) by the pusher member assembly 106, allowing the pusher assembly 106 to move independently of the deployed intravascular implant 102 as the pusher member assembly 106 and the delivery catheter 104 are axially translated relative to each other (e.g., by translating the pusher member assembly 106 in a proximal direction while holding the delivery catheter 104 in place) to retain the deployed intravascular implant 102 in place when the pusher member assembly 106 is fully retracted into the distal port 124 of the delivery catheter 104.

[0069] Return to reference 7A to 7D, the friction pad 162 not only facilitates deployment of the intravascular implant 102, but also facilitates re-sheathing of the stent 102 within the interior lumen 122 of the delivery catheter 104 (e.g., by translating the delivery catheter 104 in the distal direction while holding the pusher member assembly 106 in place). As long as the intravascular implant 102 has not been deployed from the delivery catheter 104 beyond the point of no return (i.e., as long as the distal bumper 156 remains in the interior lumen 122 of the delivery catheter 104, indicating that the friction pad 162, which will tend to expand outside the constraints of the delivery catheter 104, is completely within the interior lumen 122 of the delivery catheter 104), the intravascular implant 102 can be re-sheathed back to its compressed delivery configuration within the delivery catheter 104 with the help of the friction pad 162.

[0070] In the illustrated embodiment, although the friction pad 162 is substantially cylindrical in nature, in alternative embodiments, the friction pad 162 can have a non-circular cross-sectional profile (e.g., octagonal). In the illustrated embodiment, the friction pad 162 is composed of an elastomeric matrix material. Such an elastomeric matrix material can be a high friction polymer, such as polyether block amide (PEBA), to promote frictional engagement with the intravascular implant 102. Alternatively, other types of suitable polymers for the elastomeric matrix material may include, but are not limited to, polyoxymethylene (POM), polybutylene terephthalate (PBT), polyether block esters, fluorinated ethylene propylene (FEP), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyurethane, polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), polyimide, polyamide, polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polysulfone, nylon, perfluoro(propyl vinyl ether) (PFA), polyetherester, polymer / metal composites, or mixtures, blends, or combinations thereof.

[0071] In an alternative embodiment, the friction pad 162 may be coated with a high friction viscous material. In another alternative embodiment, the friction pad 162, the outer surface of the friction pad 162 may be modified to provide a desired resistance for frictionally engaging the intravascular implant 102. For example, at least a portion of the outer surface of the friction pad 162 may be roughened by any suitable technique (such as sandblasting, plasma treatment, or knurling), or transverse grooves, protrusions, or rings may be formed on at least a portion of the outer surface of the friction pad 162.

[0072] In the illustrated embodiment, although a single friction pad 162 is disposed within the annular space 158 between the bumpers 154, 156, in alternative embodiments, a plurality of friction pads may be disposed within the annular space 158 between the bumpers 154, 156. Furthermore, although the friction pad 162 is designed to frictionally engage uniformly the length of the intravascular implant 102 between the bumpers 154, 156, the friction pad 162 or multiple friction pads may frictionally engage only a portion of the intravascular implant 102 between the bumpers 154, 156 non-uniformly.

[0073] As previously described, it is desirable for the tubular pad body 164 to have a relatively low radial strength so that the friction pad 162 can be radially compressed / expanded enough to apply a sufficient amount of radially outward force to frictionally engage the intravascular implant 102, a relatively low bending stiffness so that the friction pad 162 will also more easily track through bends in the patient's vasculature, and a relatively high columnar strength to prevent or at least minimize radially outward bulging of the tubular pad body 164 during deployment and / or re-sheathing of the intravascular implant 102 in the presence of increased resistance to translation of the intravascular implant 102 within the interior lumen 122 of the delivery catheter 104.

[0074] It should also be understood that the columnar strength of the tubular pad body 164 can be characterized based on the axial strain (i.e., the length of the tubular pad body 164 in the presence of a unit axial force (or axial stress) divided by the change in the length of the tubular pad body 164 in the absence of the axial force (or axial stress)), while the radial strength of the tubular pad body 164 can be characterized based on the radial strain (i.e., the length of the tubular pad body 164 in the presence of a unit axial force (or axial stress) divided by the change in the diameter of the tubular pad body 164 in the absence of the radial force (or radial stress)).

[0075] Notably, the friction pad 162 is constructed in such a manner that it has sufficiently high columnar strength and sufficiently low radial strength and bending stiffness such that radial outward protrusion of the friction pad 162 is minimized while increasing resistance to translation of the intravascular implant 102 relative to the lumen 122 of the delivery catheter 104 during deployment and / or re-sheathing of the intravascular implant 102, while allowing the friction pad 162 to frictionally engage the intravascular implant 102 and easily track through the patient's vasculature.

[0076] Specifically, Fig. 8A and Figure 8BAs shown, the tubular pad body 164 of the friction pad 162 includes an elastomeric matrix material 184 that forms the friction pad 162 and at least an adjustment element 186 (a plurality of adjustment elements 186 are shown) extending axially within the elastomeric matrix material 184. The adjustment element 186 can be embedded within the elastomeric matrix material 184 using any suitable process, such as, for example, by an extrusion process, by overmolding, or by a lamination process. In the illustrated embodiment, the adjustment element 186 is elongated and extends in a direction parallel to the longitudinal axis of the tubular pad body 164. However, it should be understood that the adjustment element 186 may extend obliquely relative to the longitudinal axis of the tubular pad body 164 (e.g., at no more than fifteen degrees from the longitudinal axis of the tubular pad body 164). As discussed in further detail below, the adjustment element 186 is used to adjust the mechanical properties of the tubular pad body 164, and therefore, the mechanical properties of the material that constitutes the adjustment element 186 are significantly different from the mechanical properties of the material that constitutes the elastomeric matrix material 184.

[0077] Notably, the adjustment element 186 is configured to increase the columnar strength of the tubular pad body 164 without excessively increasing the radial strength of the tubular pad body 164 (i.e., the radial strength of the tubular pad body 164 is not so great that the elasticity of the friction pad 162 is insufficient to have sufficient radially outward force to frictionally engage the intravascular implant 102), and to increase the bending stiffness of the tubular pad body 164, or to reduce the radial strength or lateral bending stiffness of the tubular pad body 164 without excessively reducing the columnar strength of the tubular pad body 164 (i.e., the columnar strength of the tubular pad body 164 is not so weak that the friction pad 162 bulges radially outward in the presence of increased resistance to translation of the intravascular implant 102 within the internal lumen 122 of the delivery catheter 104 during deployment and / or re-sheathing of the intravascular implant 102).

[0078] In one embodiment, the adjustment element 186 increases the ratio of the columnar strength to the radial strength of the tubular pad body 164 (i.e., the ratio of the columnar strength to the radial strength of the tubular pad body 164 with the axially extending element 186 is substantially greater than the ratio of the columnar strength to the radial strength of the tubular pad body 164 if the axially extending element was replaced with the same elastomeric material 184 that would otherwise occupy the space in the tubular pad body 164 where the axially extending element 186 would otherwise be). It should be understood that because the transverse bending stiffness of the tubular pad body 164 is directly related to the radial strength of the tubular pad body 164, as the ratio of the columnar strength to the radial strength of the tubular pad body 164 increases, the ratio of the columnar strength to the transverse bending stiffness of the tubular pad body 164 will also increase in much the same manner that a solid cylinder constructed of a rigid material will significantly increase the transverse bending stiffness of the solid cylinder.

[0079] Preferably, the number, cross-sectional size, cross-sectional shape, orientation, and composition of the adjustment elements 186 are selected to maximize the volume of the elastomeric matrix material 184. That is, the total volume of the adjustment elements 186 required to achieve the desired ratio of columnar strength to radial strength of the tubular pad body 164 should be minimized so as to minimize any deleterious effects on the radial strength (and bending stiffness) of the tubular pad body 164 if the adjustment elements 186 are used to increase the columnar strength of the tubular pad body 164, or to minimize any deleterious effects on the columnar strength of the tubular pad body 164 if the adjustment elements 186 are used to reduce the radial strength (and bending stiffness) of the tubular pad body 164. In other words, the adjustment elements 186 are designed to tune the mechanical properties (i.e., columnar strength and radial strength) of the tubular pad body 164, rather than dictate the mechanical properties of the tubular pad body 164. Therefore, it is preferred that the number and cross-sectional size of the adjustment elements 186 be minimized as much as possible. It is also preferred that the thickness of the cross-sectional shape of the adjustment elements 186 be as thin as possible. It should be understood that as the difference between the mechanical properties of the material constituting the adjustment element 186 and the mechanical properties of the material constituting the elastomeric matrix material 184 increases, the adjustment of the adjustment element 186 on the tubular pad body 164 will increase, and therefore, the cross-sectional size of the adjustment element 186 can be reduced.

[0080] like Fig. 8A As shown, due to the adjustment of the tubular pad body 164 by the adjustment element 186, the diameter of the friction pad 162 will respond to the radial compression force 188 (i.e., corresponding to Figure 7H 1 (eg, from diameter d1 to diameter d2) by the radially inward force 180 applied by the inner sheath lumen 122 of the delivery catheter 104 against the outer surface 182 of the intravascular implant 102). In contrast, Figure 8B As shown, the length or diameter (e.g., diameter d2) of the friction pad 162 does not substantially change in response to the axial compressive force 190 (i.e., a force caused by increased resistance to translation of the intravascular implant 102 relative to the lumen 122 of the delivery catheter 104 during deployment and / or re-sheathing of the intravascular implant 102).

[0081] refer to Fig. 9, the tubular pad body 164a of one embodiment of the friction pad 162a includes three elongated adjustment elements 186a that extend completely axially through the elastomeric matrix material 184. The adjustment elements 186a are arranged circumferentially within the elastomeric matrix material 184, and specifically, are circumferentially spaced 120 degrees from each other. Although the tubular pad body 164a includes three adjustment elements 186a, it should be understood that the tubular pad body 164a may include any number of adjustment elements 186a. However, preferably, the adjustment elements 186a are circumferentially spaced equidistant from each other. For example, if the tubular pad body 164a alternatively includes four adjustment elements 186a, it is preferred that they are circumferentially spaced 90 degrees from each other. In the illustrated embodiment, each of the adjustment elements 186a is cylindrical (i.e., it has a circular cross-section), such as Fig. 9A shown.

[0082] In alternative embodiments, one or more of the adjustment elements 186a may have other cross-sections, such as triangular, rectangular, oval, elliptical, etc. In addition, while in the illustrated embodiment, the cross-sectional size of each of the adjustment elements 186a is uniform along the length of the respective adjustment element, the cross-sectional size of one or more of the adjustment elements 186a may vary along the length of the respective adjustment element. In addition, while the cross-sectional size of all adjustment elements 186a is illustrated as being the same, the cross-sectional size of the adjustment elements 186a may differ from one another.

[0083] It should be appreciated that the cross-sectional size and composition of the adjustment element 186a may be selected to provide a desired ratio of columnar strength to radial strength (or bending stiffness) of the tubular pad body 164a. That is, the larger the cross-sectional size and / or the higher the hardness (or elastic modulus) of the adjustment element 186a, the greater the ratio of columnar strength to radial strength of the tubular pad body 164a, while the smaller the cross-sectional size and / or the lower the hardness (or elastic modulus) of the adjustment element 186a, the lower the ratio of columnar strength to radial strength of the tubular pad body 164a.

[0084] refer to Fig.10 The tubular pad body 164b of another embodiment of the friction pad 162b is Fig. 9 The tubular pad body 164a of the friction pad 162a of FIG. 1 differs in that, rather than including an elongated adjustment element 186a that extends completely through the elastomeric matrix material 184, the tubular pad body 164b includes three elongated adjustment elements 186b that extend axially only partially through the elastomeric matrix material 184. Thus, the adjustment elements 186b do not extend axially all the way to the proximal-facing surface 192 of the tubular pad body 164b or the distal-facing surface 194 of the tubular pad body 164b. Fig. 9ALike the adjustment elements 186a of the tubular pad body 164a shown, each of the adjustment elements 186b of the tubular pad body 164b is cylindrical (ie, it has a circular cross-section), such as Fig. 10A shown.

[0085] refer to Fig.11 The tubular pad body 164c of another embodiment of the friction pad 162c is Fig. 9 The tubular pad body 164a of the friction pad 162a of FIG. 1 differs in that, rather than including a single elongated adjustment element 186a extending axially within the elastomeric matrix material 184 at each circumferential location, the tubular pad body 164c includes a series of elongated adjustment elements 186c extending axially within the elastomeric matrix material 184 at each circumferential location. In the illustrated embodiment, three adjustment elements 186c (a relatively long center adjustment element 186c flanked by two relatively short adjustment elements 186c) extend axially within the elastomeric matrix material 184 at each circumferential location. Fig. 9A Like the adjustment elements 186a of the tubular pad body 164a shown, each of the adjustment elements 186c of the tubular pad body 164c is cylindrical (ie, it has a circular cross-section), as shown in FIG. Fig.11A shown.

[0086] refer to Fig.12 The tubular pad body 164d of yet another embodiment of the friction pad 162d is Fig. 9 The tubular pad body 164a of the friction pad 162a of the embodiment of the present invention differs in that the tubular pad body 164d includes an elongated adjustment element 186d having an arcuate cross-section, rather than an elongated adjustment element 186a having a circular cross-section, as shown in FIG. Fig. 12A In this manner, the sharp cross-sectional shape of the elongated adjustment element 186d better conforms to the circumference of the elastomeric matrix material 184. In this manner, the volume of the elongated adjustment element 186d can be minimized, thereby maximizing the volume of the elastomeric matrix material 184.

[0087] refer to Fig.13 The tubular pad body 164e of another embodiment of the friction pad 162e is Fig. 9 The tubular pad body 164d of the friction pad 162a of FIG. 1 is different in that the tubular pad body 164e includes an adjustment element 186e that is not elongated. In addition, the thickness of the arcuate cross-section of the adjustment element 186e is commensurately thinner than the reduced length of the adjustment element 186e, such as Fig.13A. In addition, the adjustment elements 186e are only provided in the ends of the elastomeric matrix material 184, leaving the center of the elastomeric matrix material 184 without any adjustment elements 186e. Thus, only the ends of the tubular pad body 164e are adjusted by the adjustment elements 186e, leaving the center of the tubular pad body 164e unadjusted, as shown in FIG. Fig. 13B As shown, the end of the tubular pad body 164e is adjusted.

[0088] Figures 9 to 13 The composition of the adjustment element 186 of the tubular pad body 164 shown in FIG. 1 will depend on the composition of the elastomeric matrix material 184. For example, the elastomeric matrix material 184 may have a relatively low durometer (e.g., in the range of 25A to 35D) and, therefore, a relatively low modulus of elasticity (Young's modulus). Materials for such an elastomeric matrix material 184 may include, for example, Silicone,

[0089] In this case, such an elastomeric matrix material 184 may provide sufficiently low radial strength (and therefore sufficiently high radial expandability / compressibility) to frictionally engage the intravascular implant 102 and sufficiently low bending stiffness to allow the friction pad 162 to track through the patient's vasculature. However, such an elastomeric matrix material 184 itself may not provide sufficiently high columnar strength to prevent or otherwise minimize outward bulging of the tubular pad body 164 in response to translation of the intravascular implant 102 within the interior lumen 122 of the delivery catheter 104 during deployment and / or re-sheathing of the intravascular implant 102.

[0090] In such a case, it is preferred that the modulus of elasticity of the adjustment elements 186 is greater than the modulus of elasticity of the elastomeric matrix material 184, thereby resulting in an increased ratio of the columnar strength to the radial strength of the tubular pad body 164 (by increasing the numerator of the ratio (columnar strength)). For example, each of the adjustment elements 186 can be a solid beam constructed of a suitable material, such as a metal or metal alloy, such as stainless steel, nitinol, cobalt chromium alloy, etc., or a high hardness polymer. In this manner, a sufficiently high columnar strength is provided to the tubular pad body 164 to prevent or otherwise minimize outward bulging of the tubular pad body 164 in response to translation of the intravascular implant 102 within the interior lumen 122 of the delivery catheter 104 during deployment and / or re-sheathing of the intravascular implant 102, while not increasing the radial strength of the tubular pad body 164 to the extent that it cannot frictionally engage the intravascular implant 102, and not increasing the bending stiffness of the tubular pad body 164 to the extent that the friction pad 162 cannot easily track through the patient's vasculature. Preferably, the adjustment elements 186 are not rigidly coupled together (i.e., the only material coupling the adjustment elements 186 together is the elastomeric matrix material 184) such that the adjustment elements 186 substantially "float laterally" relative to each other. Thus, any deleterious effects on the radial strength and bending stiffness of the tubular pad body 164 are minimized.

[0091] As another example, the elastomeric matrix material 184 may have a relatively high hardness (e.g., greater than 35D), and therefore a relatively high elastic modulus (Young's modulus). Materials for such an elastomeric matrix material 184 may include, for example Polyamide, polyurethane, polycarbonate, nylon, etc.

[0092] In such instances, such elastomeric matrix material 184 may provide sufficient columnar strength to prevent or otherwise minimize outward bulging of the tubular pad body 164 in response to translation of the intravascular implant 102 within the interior lumen 122 of the delivery catheter 104 during deployment and / or re-sheathing of the intravascular implant 102. However, such elastomeric matrix material 184 itself may not provide sufficiently low radial strength (and therefore sufficiently high radial expandability / compressibility) to frictionally engage the intravascular implant 102 or sufficiently low bending stiffness to allow the friction pad 162 to easily track through the patient's vasculature.

[0093] In such a case, it is preferred that the modulus of elasticity (i.e., density) of the adjustment elements 186 be less than the modulus of elasticity of the elastomeric matrix material 184, thereby resulting in an increase in the ratio of the columnar strength to the radial strength of the tubular pad body 164 (by reducing the denominator of the ratio (radial strength)). For example, each of the adjustment elements 186 may include gel or air. In this manner, a sufficiently low radial strength is provided to the tubular pad body 164 to frictionally engage the intravascular implant 102, while not reducing the columnar strength of the tubular pad body 164 to such an extent that outward bulging of the tubular pad 164 is not prevented or otherwise minimized during deployment and / or re-sheathing of the intravascular implant 102.

[0094] Although specific embodiments of the present invention have been shown and described, it should be understood that this is not intended to limit the present invention to the preferred embodiments, and it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention. Therefore, the present invention is intended to cover alternatives, modifications and equivalents that may be included within the spirit and scope of the present invention as defined by the claims.

Claims

1. An intravascular implant delivery system, comprising: an intravascular implant having a compressed delivery configuration and an expanded deployed configuration, the intravascular implant comprising a tubular implant body and a central implant lumen extending axially through the tubular implant body; a delivery catheter having an elongated sheath body and an inner sheath lumen extending axially through the sheath body, the intravascular implant being disposed within the inner sheath lumen when in the compressed delivery configuration; and A pusher member assembly, which can be slidably disposed in the inner sheath lumen, the pusher member assembly comprising a slender pusher member and a friction pad having a radially compressed state and a radially expanded state, the friction pad being disposed in the central implant lumen when in the radially compressed state, the friction pad comprising a tubular pad body and a central pad lumen extending axially through the tubular pad body, the pusher member being disposed in the central pad lumen, the tubular pad body having an elastomeric matrix material forming the tubular pad body and at least one adjusting element embedded in the elastomeric matrix material and extending axially along the elastomeric matrix material, each of the at least one adjusting element having mechanical properties different from those of the elastomeric matrix material.

2. An intravascular implant delivery system according to claim 1, wherein the pusher member assembly and the delivery catheter are capable of axially translating relative to each other, and the friction pad is configured to frictionally engage the intravascular implant when the pusher member assembly and the delivery catheter are axially translated relative to each other, so that the intravascular implant and the pusher member assembly translate axially in unison with each other to deploy the intravascular implant from the inner sheath lumen to its expanded deployed configuration.

3. An intravascular implant delivery system according to claim 2, wherein the friction pad is configured to frictionally engage the intravascular implant when the pusher member assembly and the delivery catheter are axially translated relative to each other, so that the intravascular implant and the pusher member assembly translate axially in unison with each other to re-sheath the intravascular implant back to its compressed delivery configuration within the inner sheath lumen when it is in at least a partially expanded deployed configuration.

4. The intravascular implant delivery system according to any one of claims 1 to 3, wherein the intravascular implant is one of a stent, a stent graft, a shunt, a vascular occlusive device, and a vena cava filter.

5. An intravascular implant delivery system according to any one of claims 1 to 4, wherein the pusher member assembly further comprises a proximal buffer and a distal buffer attached to the pusher member, thereby forming an annular space between the proximal buffer and the distal buffer, wherein the friction pad is disposed within the annular space.

6. An intravascular implant delivery system according to any one of claims 1 to 5, wherein the pusher member comprises a delivery wire.

7. An intravascular implant delivery system according to any one of claims 1 to 6, wherein the elastomeric matrix material of the friction pad is polyether block amide (PEBA).

8. The intravascular implant delivery system of any one of claims 1 to 7, wherein the at least one adjustment element increases the ratio of the columnar strength to the radial strength of the tubular cushion body.

9. The intravascular implant delivery system of any one of claims 1 to 8, wherein each of the at least one adjustment element is elongated.

10. The intravascular implant delivery system of claim 9, wherein each of the at least one elongated adjustment element extends parallel to a longitudinal axis of the tubular cushion body.

11. The intravascular implant delivery system of any one of claims 1 to 10, wherein the elastic modulus of each of the at least one adjustment element is greater than the elastic modulus of the elastomeric matrix material.

12. The intravascular implant delivery system of claim 11, wherein each of the at least one adjustment element is a solid beam.

13. The intravascular implant delivery system of claim 11, wherein the at least one adjustment element increases the columnar strength of the tubular cushion body.

14. The intravascular implant delivery system of claim 11, wherein the elastomeric matrix material has a durometer in the range of 25A to 35D.

15. The intravascular implant delivery system of any one of claims 1 to 10, wherein the elastic modulus of each of the at least one adjustment element is less than the elastic modulus of the elastomeric matrix material.

16. The intravascular implant delivery system of claim 15, wherein each of the at least one regulating element is a gel or air.

17. The intravascular implant delivery system of claim 15, wherein the at least one adjustment element reduces the radial strength of the tubular cushion body.

18. The intravascular implant delivery system of claim 15, wherein the elastomeric matrix material has a durometer greater than 35D.

19. The intravascular implant delivery system of any one of claims 1 to 18, wherein the at least one adjustment element comprises a plurality of adjustment elements.

20. The intravascular implant delivery system of claim 19, wherein the plurality of adjustment elements are circumferentially arranged within the elastomeric matrix material.

21. The intravascular implant delivery system of any one of claims 1 to 20, wherein the tubular cushion body is cylindrical.

22. An intravascular implant delivery system, the intravascular implant delivery system comprising: an intravascular implant having a compressed delivery configuration and an expanded deployed configuration, the intravascular implant comprising a tubular implant body and a central implant lumen extending axially through the tubular implant body; a delivery catheter having an elongated sheath body and an inner sheath lumen extending axially through the sheath body, the intravascular implant being disposed within the inner sheath lumen when in the compressed delivery configuration; and A pusher member assembly, which can be slidably disposed in the inner sheath lumen, the pusher member assembly comprising a slender pusher member and a friction pad having a radially compressed state and a radially expanded state, the friction pad being disposed in the central implant lumen when in the radially compressed state, the friction pad comprising a tubular pad body and a central pad lumen extending axially through the tubular pad body, the pusher member being disposed in the central pad lumen, the tubular pad body having an elastomeric matrix material forming the tubular pad body and at least one adjustment element embedded in the elastomeric matrix material, wherein the at least one adjustment element increases the ratio of the columnar strength to the radial strength of the tubular pad body.

23. An intravascular implant delivery system according to claim 22, wherein the pusher member assembly and the delivery catheter are capable of axially translating relative to each other, and the friction pad is configured to frictionally engage the intravascular implant when the pusher member assembly and the delivery catheter are axially translated relative to each other, so that the intravascular implant and the pusher member assembly translate axially in unison with each other to deploy the intravascular implant from the inner sheath lumen to its expanded deployed configuration.

24. An intravascular implant delivery system according to claim 23, wherein the friction pad is configured to frictionally engage the intravascular implant when the pusher member assembly and the delivery catheter are axially translated relative to each other, so that the intravascular implant and the pusher member assembly translate axially in unison with each other to re-sheath the intravascular implant back to its compressed delivery configuration within the inner sheath lumen when it is in at least a partially expanded deployed configuration.

25. The intravascular implant delivery system of claim 22, wherein the intravascular implant is one of a stent, a stent graft, a shunt, a vascular occlusive device, and a vena cava filter.

26. An intravascular implant delivery system according to claim 22, wherein the pusher member assembly further comprises a proximal buffer and a distal buffer attached to the pusher member, thereby forming an annular space between the proximal buffer and the distal buffer, wherein the friction pad is disposed within the annular space.

27. The intravascular implant delivery system of claim 22, wherein the pusher member is a delivery wire.

28. The intravascular implant delivery system of claim 22, wherein the elastomeric matrix material of the friction pad is polyether block amide (PEBA).

29. The intravascular implant delivery system of claim 22, wherein each of the at least one adjustment element is elongated.

30. The intravascular implant delivery system of claim 29, wherein each of the at least one elongated adjustment element extends parallel to a longitudinal axis of the tubular pad body.

31. The intravascular implant delivery system of claim 22, wherein each of the at least one adjustment element has an elastic modulus greater than an elastic modulus of the elastomeric matrix material.

32. The intravascular implant delivery system of claim 31 , wherein each of the at least one adjustment element is a solid beam.

33. The intravascular implant delivery system of claim 31 , wherein the at least one adjustment element increases the columnar strength of the tubular cushion body.

34. The intravascular implant delivery system of claim 31 , wherein the elastomeric matrix material has a durometer in the range of 25A to 35D.

35. The intravascular implant delivery system of claim 22, wherein each of the at least one adjustment element has an elastic modulus less than an elastic modulus of the elastomeric matrix material.

36. The intravascular implant delivery system of claim 35, wherein each of the at least one regulating element is a gel or air.

37. The intravascular implant delivery system of claim 35, wherein the at least one adjustment element reduces the radial strength of the tubular cushion body.

38. An intravascular implant delivery system according to claim 35, wherein the elastomeric matrix material has a durometer greater than 35D.

39. The intravascular implant delivery system of claim 22, wherein the at least one adjustment element comprises a plurality of adjustment elements.

40. The intravascular implant delivery system of claim 39, wherein the plurality of adjustment elements are circumferentially arranged within the elastomeric matrix material.

41. The intravascular implant delivery system of claim 22, wherein the tubular pad body is cylindrical.

42. An intravascular implant delivery system, the intravascular implant delivery system comprising: an intravascular implant having a compressed delivery configuration and an expanded deployed configuration, the intravascular implant comprising a tubular implant body and a central implant lumen extending axially through the tubular implant body; a delivery catheter having an elongated sheath body and an inner sheath lumen extending axially through the sheath body, the intravascular implant being disposed within the inner sheath lumen when in the compressed delivery configuration; and A pusher member assembly, which can be slidably disposed in the inner sheath lumen, the pusher member assembly comprising a slender pusher member and a friction pad having a radially compressed state and a radially expanded state, the friction pad being disposed in the central implant lumen when in the radially compressed state, the friction pad comprising a tubular pad body and a central pad lumen extending axially through the tubular pad body, the pusher member being disposed in the central pad lumen, the tubular pad body having an elastomeric matrix material forming the tubular pad body and at least one adjustment element embedded in the elastomeric matrix material, wherein the at least one adjustment element increases the columnar strength of the tubular pad body.

43. An intravascular implant delivery system according to claim 42, wherein the pusher member assembly and the delivery catheter are capable of axially translating relative to each other, and the friction pad is configured to frictionally engage the intravascular implant when the pusher member assembly and the delivery catheter are axially translated relative to each other, so that the intravascular implant and the pusher member assembly translate axially in unison with each other to deploy the intravascular implant from the inner sheath lumen to its expanded deployed configuration.

44. An intravascular implant delivery system according to claim 43, wherein the friction pad is configured to frictionally engage the intravascular implant when the pusher member assembly and the delivery catheter are axially translated relative to each other, so that the intravascular implant and the pusher member assembly translate axially in unison with each other to re-sheath the intravascular implant back to its compressed delivery configuration within the inner sheath lumen when it is in at least a partially expanded deployed configuration.

45. The intravascular implant delivery system of claim 42, wherein the intravascular implant is one of a stent, a stent graft, a shunt, a vascular occlusive device, and a vena cava filter.

46. ​​An intravascular implant delivery system according to claim 42, wherein the pusher member assembly further comprises a proximal buffer and a distal buffer attached to the pusher member, thereby forming an annular space between the proximal buffer and the distal buffer, wherein the friction pad is disposed within the annular space.

47. The intravascular implant delivery system of claim 42, wherein the pusher member is a delivery wire.

48. The intravascular implant delivery system of claim 42, wherein the elastomeric matrix material of the friction pad is polyether block amide (PEBA).

49. The intravascular implant delivery system of claim 42, wherein each of the at least one adjustment element is elongated.

50. The intravascular implant delivery system of claim 49, wherein each of the at least one elongated adjustment element extends parallel to a longitudinal axis of the tubular pad body.

51. The intravascular implant delivery system of claim 42, wherein each of the at least one adjustment element has an elastic modulus greater than an elastic modulus of the elastomeric matrix material.

52. The intravascular implant delivery system of claim 51, wherein each of the at least one adjustment element is a solid beam.

53. The intravascular implant delivery system of claim 51, wherein the at least one adjustment element increases the columnar strength of the tubular cushion body.

54. An intravascular implant delivery system according to claim 51, wherein the elastomeric matrix material has a durometer in the range of 25A to 35D.

55. The intravascular implant delivery system of claim 42, wherein the at least one adjustment element comprises a plurality of adjustment elements.

56. An intravascular implant delivery system according to claim 55, wherein the plurality of adjustment elements are arranged circumferentially within the elastomeric matrix material.

57. The intravascular implant delivery system of claim 42, wherein the tubular pad body is cylindrical.

58. An intravascular implant delivery system, the intravascular implant delivery system comprising: an intravascular implant having a compressed delivery configuration and an expanded deployed configuration, the intravascular implant comprising a tubular implant body and a central implant lumen extending axially through the tubular implant body; a delivery catheter having an elongated sheath body and an inner sheath lumen extending axially through the sheath body, the intravascular implant being disposed within the inner sheath lumen when in the compressed delivery configuration; and A pusher member assembly, which can be slidably disposed in the inner sheath lumen, the pusher member assembly comprising a slender pusher member and a friction pad having a radially compressed state and a radially expanded state, the friction pad being disposed in the central implant lumen when in the radially compressed state, the friction pad comprising a tubular pad body and a central pad lumen extending axially through the tubular pad body, the pusher member being disposed in the central pad lumen, the tubular pad body having an elastomeric matrix material forming the tubular pad body and at least one adjusting element embedded in the elastomeric matrix material, wherein the at least one adjusting element reduces the radial strength of the tubular pad body.

59. An intravascular implant delivery system according to claim 58, wherein the pusher member assembly and the delivery catheter are capable of axially translating relative to each other, and the friction pad is configured to frictionally engage the intravascular implant when the pusher member assembly and the delivery catheter are axially translated relative to each other, so that the intravascular implant and the pusher member assembly translate axially in unison with each other to deploy the intravascular implant from the inner sheath lumen to its expanded deployed configuration.

60. An intravascular implant delivery system according to claim 59, wherein the friction pad is configured to frictionally engage the intravascular implant when the pusher member assembly and the delivery catheter are axially translated relative to each other, so that the intravascular implant and the pusher member assembly translate axially in unison with each other to re-sheath the intravascular implant back to its compressed delivery configuration within the inner sheath lumen when it is in at least a partially expanded deployed configuration.

61. The intravascular implant delivery system of claim 58, wherein the intravascular implant is one of a stent, a stent graft, a shunt, a vascular occlusive device, and a vena cava filter.

62. An intravascular implant delivery system according to claim 58, wherein the pusher member assembly further comprises a proximal buffer and a distal buffer attached to the pusher member, thereby forming an annular space between the proximal buffer and the distal buffer, wherein the friction pad is disposed within the annular space.

63. The intravascular implant delivery system of claim 58, wherein the pusher member is a delivery wire.

64. The intravascular implant delivery system of claim 58, wherein the elastomeric matrix material of the friction pad is polyether block amide (PEBA).

65. The intravascular implant delivery system of claim 58, wherein each of the at least one adjustment element is elongated.

66. The intravascular implant delivery system of claim 65, wherein each of the at least one elongated adjustment element extends parallel to a longitudinal axis of the tubular pad body.

67. The intravascular implant delivery system of claim 58, wherein each of the at least one adjustment element has an elastic modulus less than an elastic modulus of the elastomeric matrix material.

68. The intravascular implant delivery system of claim 67, wherein each of the at least one regulating element is a gel or air.

69. The intravascular implant delivery system of claim 67, wherein the at least one adjustment element reduces the radial strength of the tubular cushion body.

70. The intravascular implant delivery system of claim 67, wherein the elastomeric matrix material has a durometer greater than 35D.

71. The intravascular implant delivery system of claim 58, wherein the at least one adjustment element comprises a plurality of adjustment elements.

72. An intravascular implant delivery system according to claim 71, wherein the plurality of adjustment elements are arranged circumferentially within the elastomeric matrix material.

73. The intravascular implant delivery system of claim 58, wherein the tubular pad body is cylindrical.

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