Catheter device for transluminal delivery of a self-expanding tubular implant to a body site

Abstract

A catheter device for transluminal delivery of a self-expanding tubular implant to a body site, the catheter device comprising: an inner catheter comprising a cylindrical distal end part having a wall, wherein the cylindrical distal end part is arranged to be received within a lumen of the implant in use, and a sheath coaxial with the inner catheter, wherein the sheath is arranged to encase the implant until, in use, the sheath is proximally withdrawn relative to the implant and the inner catheter to release or deploy the implant at the site, wherein the cylindrical distal end part comprises a first plurality of implant retaining elements that project radially outwardly from the cylindrical distal end part during withdrawal of the sheath to engage a radially inwardly facing surface of the implant to limit the implant from being carried proximally by the sheath relative to the cylindrical distal end part, characterized in that the first plurality of implant retaining elements are formed from a portion of the wall of the cylindrical distal end part and the first plurality of implant retaining elements are configured to assume a radially outwardly projecting configuration to engage the radially inwardly facing surface of the implant using a shape memory effect prior to withdrawal of the sheath.

Description

TECHNICAL FIELD

[0001] The present invention relates to a catheter device for transluminal delivery of a self-expanding tubular implant to a body site, to a method of manufacturing a shape memory alloy tube for a catheter device for transluminal delivery of a self-expanding tubular implant to a body site, and to a method of assembling a catheter assembly for transluminal delivery of a self-expanding tubular implant to a body site. BACKGROUND

[0002] Catheter devices are known. A catheter device can comprise an inner catheter and a sheath. An implant for delivery to a body site is loaded onto the inner catheter. To deliver the stent, the sheath is pulled back. The implant can be compressed on the inner catheter.

[0003] In such conventional catheter devices it has been found difficult to maintain a firm grip of the compressed implant on the inner catheter during sheath retraction. In particular, this has been found to be the case if the implant or the cover on the implant changes in weight, which is often the case due to material and process tolerances. Too large or too heavy implants can result in an over-compression and the associated deployment force can exceed the strength limit of the delivery system joint, resulting in a failure of the delivery system. Furthermore, it has been found that relatively small or light implants can lose grip on the inner catheter and thus can retract with the sheath, resulting in a complete failure of the deployment, or worse, a partial deployment of the implant.

[0004] In US 2010 / 0274226 Al, fingers are provided on the inner catheter. When the sheath is retracted, the implant can be damaged because it slides on the inner catheter, or the implant can be compressed axially and jammed inside the sheath, making deployment impossible.

[0005] To solve this problem, it is known to provide a resilient silicone sleeve on the inner catheter, on which a length of thin metal wire braid is placed to improve the grip.

[0006] The silicone sleeve is intended to provide radial flexibility and to accommodate for tolerance-related variations in the size and / or cover weight of the implant, while the radial compression of the catheter device (assembly) does not vary much and thus the deployment force does not vary much.

[0007] A disadvantage of this arrangement is that, although silicone is a very soft and flexible material, i.e. very compliant, the wall thickness of the sleeve is very thin due to space constraints, and the mechanical behavior of silicone can be described as linearly elastic. Thus, even at a very slow speed compared to a harder material, increased compression results in increased pushback, requiring a larger deployment force. SUMMARY

[0008] It is an object of the present invention to provide a catheter device which solves at least one of the above mentioned problems.

[0009] According to one aspect of the present invention, there is provided a catheter device for transluminal delivery of a self-expanding tubular implant to a body site, the catheter device comprising: an inner catheter comprising a cylindrical distal member having a wall, wherein the cylindrical distal member is arranged to be received within a lumen of the implant in use; and a sheath coaxial with the inner catheter, wherein the sheath is arranged to encase the implant until, in use, the sheath is proximally retracted relative to the implant and the inner catheter to release or deploy the implant at the site, wherein the cylindrical distal member comprises a first plurality of implant retaining elements which project radially outwardly from the cylindrical distal member during retraction of the sheath to engage a radially inwardly facing surface of the implant to limit the implant from being carried proximally by the sheath relative to the cylindrical distal member, characterised in that the first plurality of implant retaining elements are formed from a portion of the wall of the cylindrical distal member and the first plurality of implant retaining elements are configured to assume a radially outwardly projecting configuration to engage the radially inwardly facing surface of the implant using a shape memory effect prior to retraction of the sheath.

[0010] In this way, the plurality of retaining features improves the retention of the implant on the inner catheter over a larger range of implant weights, component sizes of the implant and the catheter device.

[0011] In one embodiment, the design of the plurality of retaining elements is such that the hinge portion is located in a plateau region of the material stress-strain curve of the plurality of retaining elements when engaged with the implant, such that the retaining elements exert more or less the same force on the implant regardless of how much they project (deflect) from the cylindrical member, so that how much they deflect is not important.

[0012] The performance of the plurality of retaining elements ensures a relatively constant frictional and retaining force on the outside of the inner catheter by the one-way elements formed by the first plurality of implant retaining elements or by the two-way elements formed by the first plurality of implant retaining elements and the second plurality of implant retaining elements. Due to the plateau region in the material stress-strain curve of the plurality of retaining elements, these retaining elements will accommodate different degrees of radial displacement while exerting a constant radial force regardless of how much the plurality of retaining elements project from the inner catheter. In this way, a relatively constant radial stress condition is ensured. Thus, a relatively constant frictional and deployment force is achieved over a range of implant weights, component sizes of the implant and the delivery system. Thus, the reliability of deployment is enhanced.

[0013] In one embodiment, at least one of the first plurality of implant retaining elements is a tab arranged to extend distally from a root line in the cylindrical distal member. In this way, the implant is prevented from moving in a proximal direction.

[0014] In another embodiment, the cylindrical distal member includes a second plurality of implant retaining elements configured to project radially outwardly from the cylindrical distal member to engage a radially inwardly facing surface of the implant using a shape memory effect, thereby limiting the implant from being carried distally relative to the cylindrical distal member. In this manner, the implant is prevented from moving in the distal direction. In the presence of distal and proximal tabs, the implant is prevented from moving in both directions.

[0015] In the following, in the distal wing (first retaining element), the wing is arranged to extend distally from the root line in the cylindrical distal part. In this way, the implant is prevented from moving in the proximal direction. Correspondingly, in the proximal wing (second retaining element), the wing is arranged to extend proximally from the root line in the cylindrical distal part. In this way, the implant is prevented from moving in the distal direction.

[0016] In another embodiment, the cylindrical distal component is made of Nitinol. In this way, the reliability of the implant deployment is enhanced because Nitinol has a relatively flat plateau region in its stress-strain curve, that is, it can adapt to strain changes with relatively small stress changes. In particular, this material property of Nitinol allows the first plurality of retaining elements and / or the second plurality of retaining elements to adapt to diameter changes with relatively small radial force changes, so that the degree of compression of the implant is less dependent on the spatial compression degree of the implant. In addition, in one embodiment, the first plurality of retaining elements and / or the second plurality of retaining elements are incorporated into the wall of the Nitinol inner catheter member, rather than being added on top of the existing inner catheter material. In this way, space is saved and can therefore be used to accommodate the implant. In other words, the available space for the implant in the catheter device is larger.

[0017] In yet another embodiment, at least one flexible section includes a plurality of staggered circumferentially extending slits to form a universal joint. In this manner, the slits impart enhanced bending capabilities to the component, thereby facilitating advancement of the distal end of the catheter device along particularly tortuous lumens to difficult-to-reach implantation sites within the body.

[0018] In yet another embodiment, at least the first plurality of retaining elements and the second plurality of retaining elements are arranged in the same implant retaining section. In this way, the reliability of deploying a short implant is enhanced.

[0019] In another embodiment, the first plurality of retaining elements and the second plurality of retaining elements are arranged circumferentially around the cylindrical distal member in at least one row, wherein the first plurality of retaining elements and the second plurality of retaining elements are arranged alternately along the at least one row. In this way, the reliability of deploying a short implant is further enhanced because this arrangement allows adjustment of the position of the implant (relative to the sheath, rather than relative to the inner catheter member) in both the proximal and distal directions.

[0020] In another embodiment, the first plurality of retention elements are disposed on the cylindrical distal member at locations arranged to be received by the distal region of the implant.

[0021] In yet another embodiment, the second plurality of retention elements are disposed on the cylindrical distal member at locations arranged to be received by the proximal region of the implant.

[0022] In this way, the reliability of deploying long implants is improved because during implant (stent) position adjustment, no matter which way the implant is moved by pushing or pulling the inner catheter, it is ensured that the implant is pulled rather than pushed, thereby preventing bending and jamming within the outer sheath.

[0023] Another advantage of the present invention is that it solves the problems associated with deploying long and flexible self-expanding implants, such as vascular implants, such as Nitinol stents or expanded polytetrafluoroethylene (ePTFE) covered Nitinol stents from a retractable oversheath type delivery system.

[0024] In one embodiment of the present invention, the first plurality of retaining elements and / or the second plurality of retaining elements are configured such that the forces applied to the implant by the first plurality of retaining elements and / or the second plurality of retaining elements within the deflection range of the hinge are substantially the same within the deflection range. In this way, the forces applied to the implant are the same regardless of the deflection, so tolerances are not so important. Further, the space required for the first plurality of retaining elements and / or the second plurality of retaining elements is minimized in the radial direction, thereby minimizing the radial dimensions of the catheter device.

[0025] In another embodiment, the first plurality of implant retaining elements can be located within the wall thickness. In this way, the first plurality of retaining elements and / or the second plurality of retaining elements do not require their own space, and thus the diameter of the catheter device is further reduced.

[0026] According to another aspect of the present application, there is provided a method of manufacturing a shape memory alloy tube for a catheter device for transluminal delivery of a self-expanding tubular implant to a body site, the method comprising: forming a hinge in the shape memory alloy tube, deforming the shape memory alloy tube by deflecting a portion of the shape memory alloy tube about the hinge, setting the deformed portion by heating the shape memory alloy such that the shape memory alloy is capable of assuming a configuration at body temperature in which the deformed portion is deflected radially outward about the hinge from the shape memory alloy tube.

[0027] According to yet another aspect of the present application, there is provided a method of assembling a catheter assembly for transluminal delivery of a self-expanding tubular implant to a body site, the catheter assembly comprising an inner catheter comprising a shape memory alloy tube, a sheath and a self-expanding implant, the method comprising the step of assembling the self-expanding implant on the shape memory alloy tube, wherein in the step of assembling the shape memory alloy tube is at a temperature which allows it to primarily accommodate the radially inward pressure exerted by the self-expanding implant on the shape memory alloy tube by martensitic twinning. BRIEF DESCRIPTION OF DRAWINGS

[0028] The present application and its embodiments will be further explained with reference to the drawings on the basis of examples, in which:

[0029] Figure 1 A catheter device and an implant according to an embodiment of the present application are shown;

[0030] Figure 2a A portion of an inner catheter according to an embodiment of the present application is shown in a relaxed position;

[0031] Figure 2b A portion of an inner catheter according to an embodiment of the present application is shown in a compressed position; Figure 2a

[0032] Figure 2c A portion of an inner catheter according to an embodiment of the present application is shown in a compressed position; Figure 2a Figure 2b A portion of an inner catheter according to an embodiment of the present application is shown in a compressed position;

[0033] Figure 3 An inner catheter according to an embodiment of the present application is shown.

[0034] Figure 4 Various views of various embodiments and various views of various embodiments are shown, showing various retention features according to embodiments of the present application;

[0035] Figure 5 Various views of various embodiments and various views of various embodiments are shown, showing various retention features according to embodiments of the present application; ​​

[0036] Figure 6a and Figure 6b showing inner catheter according to further embodiments of the application;

[0037] Figure 7a showing plan view of alloy tube to be formed into implant retaining feature;

[0038] Figure 7b showing Figure 7a showing cross section of alloy tube without showing wire;

[0039] Figure 7c showing Figure 7a showing side view of alloy tube shown in

[0040] Figure 7d showing Figure 7a showing cross section of alloy tube shown in DETAILED DESCRIPTION

[0041] In the drawings and in the following detailed description, like reference numerals indicate like features. The application is illustrated in the following described embodiments. The application is not limited to these embodiments which are shown by way of illustration.

[0042] In the following, reference is made to the terms "proximal" and "distal". In case of reference to a component or a part of a component being "proximal", it is to be understood that it refers to the component or the part of the component being arranged at a position towards the position of the handle of the device. While in case of reference to a component or a part of a component being "distal", it is to be understood that it refers to the component or the part of the component being arranged away (distal) from the position of the handle of the device.

[0043] Self-expanding implants such as Nitinol implants such as stents or stent grafts covered by ePTFE, when deployed from their compressed state inside the sheath of a pullback delivery system, the proximally directed (i.e. in the direction of the handle of the device) frictional force that arises between the constricting outer sheath and the implant is typically balanced by an axial compression force in the inner catheter 2. The inner catheter 2 leads all the way to the handle of the device and is typically also used as a lumen to accommodate a guidewire over which the delivery system often tracks from an entry point into the body through an artery or vein to the implant target site in the body, but also depending on tracking through other body tubes to the target site.

[0044] Traditionally, the frictional force is transferred from the implant 20 to the inner catheter 2 by a collar placed on the inner catheter proximal to the implant. When the sheath is retracted, the implant moves back against the collar and transfers the force from the proximal end of the implant to the collar, and thus to the inner catheter, and thus back to the delivery system handle. The inventors have found that when attempting to deploy a particularly long and flexible implant, the implant tends to bend under axial compression and become stuck within the sheath, thereby preventing successful deployment. Furthermore, if the cover extends beyond the metal frame of the covered implant, the frictional force of the entire implant sheath is transferred through the proximal end of the implant covered by ePTFE, which may cause the fragile ePTFE cover to break.

[0045] Have found that, realized more reliable expansion by a kind of arrangement, wherein the transmission of power from implant to inner conduit is realized by one or more parts of the whole interface between the outside of the inside of compressed implant and inner conduit.Have found that, in order to realize this point, purely based on friction, compared with the friction coefficient between the inside of the outside of compressed implant and sheath, need obvious relatively high friction coefficient between the outside of the inside of implant and inner conduit.In practice, make every effort to keep the friction force of implant outside as low as possible.Yet, have found that, be difficult to realize enough big difference between the relatively low friction coefficient on " implant outer surface and sheath " interface and the relatively high friction coefficient on " implant inner surface and inner conduit " interface, to prevent implant from any movement with respect to inner conduit steadily when sheath is retracted.Have found that, can strengthen the clamping on inner conduit by the surface of suitable structure inner conduit, make shape locking occur between the feature portion (such as, exposed stent strut edge or compressed covering fold) on the inside of implant and the feature portion on the outer surface of inner conduit.

[0046] In the embodiment of the present invention, the radial force of implant and conveying system assembly is as small as possible.Yet, because the level of the required power of retracting sheath is not only the function of the friction coefficient between implant and the sheath, and also the function of the level of the radial force between implant and the sheath, therefore expect to keep radial force as small as possible.This can for example be realized by minimizing the compression degree of implant, and it can be realized by maximizing the space that is used to hold implant in device.On the other hand, need implant be carried out minimal radial compression, to guarantee to have enough large friction force between implant and interior conduit.This implant compression degree must remain in the scope of restriction, and also should consider the dimensional tolerance of involved parts, implant size variation and the dimensional variation of covering weight or implant and covering weight or the dimensional variation of implant and conveying system assembly (they are such as taking out from packaging, preparing and following the tracks of by tortuous anatomical structure because aging, temperature variation, humidity variation or device process the external mechanical force that produces and cause).

[0047] Figure 1 A catheter device 10 and an implant 20 according to an embodiment of the present invention are shown. In this embodiment, the catheter device is used to deliver a self-expanding tubular implant 20 transluminally to a site within the body. The implant can be a vascular implant, such as a stent. Implant 20 can be covered with a covering, such as ePTFE, or can be an uncovered implant, such as a nitinol stent. The catheter device of this embodiment can be used in a pull-back oversheath-type delivery system. Figure 1 A pull-back delivery system is shown. The catheter device 10 includes an inner catheter 2. The inner catheter 2 may include a cylindrical distal end member 4 having a wall 6. The cylindrical distal end member 4 may be arranged to be received in the lumen of the implant 20 during use. The catheter device 10 may also include a sheath 8. The sheath 8 is coaxial with the inner catheter 2. The sheath 8 is arranged to fit over the implant 20 until the sheath 8 is retracted proximally relative to the implant 20 and the inner catheter 2 during use to release (deploy) the implant 20 at the site. The site is located at a distal position. The implant 20 is typically located on the inner catheter, at a distal position. Figure 1 The sheath 8 is shown partially retracted. Figure 1 , the sheath 8 has been retracted beyond the distal end of the implant 20. A direction 12 along the longitudinal axis of at least one of the inner catheter 2 and the sheath 8 indicates the direction in which the sheath 8 is retracted. It can be seen that the sheath 8 is retracted toward a proximal position, i.e., toward the device handle.

[0048] In this embodiment, the cylindrical distal component 4 includes a first plurality of implant retaining elements 14. The first plurality of implant retaining elements 14 project radially outward from the cylindrical distal component 4 during retraction of the sheath 8 to engage the radially inwardly facing surface of the implant 20, thereby limiting the proximal entrainment of the implant 20 by the sheath 8 relative to the cylindrical distal component 4. In this embodiment, the first plurality of implant retaining elements 14 are formed by a portion of the wall 6 of the cylindrical distal component 4. In addition, the first plurality of implant retaining elements are configured to utilize a shape memory effect to assume a radially outwardly projecting configuration prior to sheath retraction to engage the radially inwardly facing surface of the implant.

[0049] In particular, in order to maintain defined radial stress conditions in the space for accommodating the implants 20 between the interior of the sheath 8 and the exterior of the inner catheter 2, it is beneficial to have at least one element, preferably a plurality of implant holding elements 14, within the space that can assume different degrees of radial deflection without a significant change in the radial force to achieve these states of different degrees of radial deflection. The shape memory effect of the plurality of implant holding elements 14 achieves this result. Each of the plurality of implant holding elements 14 has a plateau region in its load-deformation (also known as stress-strain) curve. The implant holding elements are constituted by the wall 6 of the inner catheter 2. In one embodiment, the inner catheter 2 is a nitinol alloy. The one or more implant holding elements 14 are configured to utilize at least one of the super-elasticity and shape memory properties of the nitinol alloy. Preferably, the cylindrical distal end piece 4 is made of nitinol.

[0050] In one embodiment, at least one of the first plurality of implant holding elements 14 is a flap. The flap includes a hinge 16. The flap is arranged to extend distally from a root line in the cylindrical distal end piece 4. In this way, the implant 20 is prevented from moving in the proximal direction.

[0051] The cylindrical distal end piece 4 can include a second plurality of implant holding elements 18 (see Figure 6a and Figure 6b ). The second plurality of implant holding elements 18 are configured to utilize the shape memory effect to protrude radially outward from the cylindrical distal end piece to engage a radially inward facing surface of the implant 20 to limit the implant from being carried distally relative to the cylindrical distal end piece 4. In this way, the implant 20 is prevented from moving in the distal direction 31. In terms of the difference between the second plurality of implant holding elements 18 and the first plurality of implant holding elements 14, they are oriented in the opposite direction as the first plurality of implant holding elements 14. In particular, the flap is arranged to extend proximally from a root line in the cylindrical distal end piece 4. In embodiments of the invention, they are otherwise identical to the first plurality of implant holding elements 14.

[0052] In embodiments that include both the first plurality of implant holding elements 14 and the second plurality of implant holding elements 18 (e.g., that include both distal flaps and proximal flaps), the implant can be prevented from moving in both directions 31, 33.

[0053] As Figures 2a-2c and Figure 3The inner catheter 2 shown shows the implant retaining element 14 pointing toward the distal end 31 of the delivery system, in other words, the radially outwardly projecting portion (e.g., the deflected portion of the wing) is located distally relative to the hinge 16. In this way, the implant retaining feature 14 is arranged to prevent the implant (e.g., a stent or stent graft) from moving toward the proximal end 33 when the sheath 8 is retracted, as described above. In other embodiments (see Figures 6a-6b ), the implant retention feature 18 is arranged to point in the proximal direction 33, in other words, the radially outward protrusion (e.g., the deflected portion of the wing) is located proximally relative to the hinge 16 so as to prevent the implant from moving toward the distal end 31 when the sheath 8 is retracted.

[0054] In such Figure 6a In one embodiment shown, implant retaining elements 14, 18 arranged to point in two directions 31, 33, respectively, can be provided in the same implant retaining section 30 to prevent the implant 20 from moving in either direction 31, 33. This arrangement is advantageous if it is desired to be able to move the implant in either direction 31, 33 to precisely adjust its position in the sheath 8 after the implant is loaded on the inner catheter 2.

[0055] Further references Figure 6a , for a short implant, the implant retaining elements pointing toward the distal end 31 (first plurality of retaining elements 14) and toward the proximal end 33 (second plurality of retaining elements 18) can be arranged separately in the same implant retaining section 30 on the inner catheter 2. In one embodiment, the implant retaining section 30 comprises a plurality of rows. The implant retaining elements 14, 18 can be arranged in alternating directions in the rows 30. In one embodiment, the first plurality of implant retaining elements 14 and the second plurality of implant retaining elements 18 are circumferentially arranged around the cylindrical distal part 4 in at least one row 30, wherein the first plurality of implant retaining elements 14 and the second plurality of implant retaining elements 18 are arranged alternately along the at least one row. This arrangement allows the position of the implant 20 to be adjusted relative to the sheath 8 (rather than relative to the inner catheter 2) in both the proximal and distal directions.

[0056] refer to Figure 6bFor long implants, in one embodiment, implant holding elements 14 pointing in distal direction 31 are provided in a first implant holding section 30 at a distal position corresponding to the distal end of implant 20, and implant holding elements 18 pointing in proximal direction 33 are provided in a second implant holding section 36 at a relatively proximal position corresponding to the proximal end of implant 20. In one embodiment, the first plurality of holding elements 14 is arranged at a position on the cylindrical distal part 4 arranged to be received by the distal region of implant 20. The second plurality of holding elements 18 is arranged at a position on the cylindrical distal part 4 arranged to be received by the proximal region of implant 20. In this way, it is ensured that implant 20 is pulled and not pushed, whenever it is moved by pushing or pulling inner catheter 2 during implant position adjustment, thereby preventing bending and jamming within sheath 8.

[0057] Reference is made to Figures 2a-2c , describing the shape memory properties and superelastic properties of the plurality of implant holding elements. Figure 2a An alloy tube forming part of inner catheter 2 is shown. In Figure 2a , implant holding elements 14 are in a relaxed position. Figure 2b An alloy tube identical to Figure 2a is shown. In Figure 2b , implant holding elements 14 are in a compressed position.

[0058] Figure 2a and Figure 2b show the shape of implant holding elements. For example, in Figure 2a and Figure 2b , a first implant holding element 14 is shown. However, the shape of implant holding elements shown in Figure 2a and Figure 2b is applicable to one or more of the first and second implant holding elements 14, 18, respectively. Similarly, the following description with respect to Figure 2a , Figure 2b and Figure 2c is also applicable to one or more of the first and second implant holding elements 14, 18, respectively.

[0059] Figure 2c is a graphical representation showing stress-strain curves of an alloy tube, in particular implant holding elements 14 shown in Figure 2a and Figure 2b . Figures 2a to 2c The stress of implant holding elements 14 at articulation 16 is illustrated. Articulation 16 is the section around which the main deflection portion of implant holding elements 14, e.g. the deflection position of a flap, is made. Figure 2a Implant holding elements 14 in embodiments of Figure 4 andFigure 5 While shown and described, the invention is not limited in this respect.

[0060] exist Figures 2a-2c In the embodiment of the invention, the fins are cut from the wall 6 of an inner conduit, for example made of a Nitinol tube. The wall of the Nitinol tube serves as the inner conduit 2 supporting the implant. The ends of the fin shapes are arranged in a position extending slightly beyond the original diameter OD of the Nitinol tube from which the fins were cut, by a distance Δ. Figure 2a In the embodiment, the wing 14 has no stress at its hinge 16. Figure 2a As seen in FIG, the width of the tube including the extended fins is OD + Δ. Figure 2c The diagram illustrates how the implant retaining element 14, after some initial compression, applies a relatively constant outward force over a large range of deflections once the stress state at the hinge reaches the plateau region C shown in the diagram. Figure 2c As seen in the figure, point A shows Figure 2a The stress-strain relationship of the implant retaining elements 14, 18 in FIG. 1 is shown in FIG. Figure 2b 18. In the plateau region C, the stress applied by the implant retaining elements 14, 18 is constant regardless of the deflection of the implant retaining elements 14, 18.

[0061] A method for manufacturing a shape memory alloy tube (e.g., a Nitinol tube) for a catheter device is now described. In one embodiment, the method includes forming a hinge 16 in the shape memory alloy tube 2. The method also includes deflecting a portion of the shape memory alloy tube about the hinge 16 and setting the deformed portion by heating the shape memory alloy. Figure 2a In the embodiment shown, the deflection Δ is the position in which the heat-set shape memory alloy tube is located. In this position, the shape memory alloy can assume a configuration at body temperature where the deformed portion is deflected radially outward from the shape memory alloy tube about the hinge 16. Figure 2a In the embodiment shown, the deformed portion is deflected about the hinge 16 so that it deflects outwardly by a distance Δ. The portion of the alloy tube that is deflected about the hinge is the implant retaining element 14.

[0062] The shape memory alloy tube forms the inner catheter 2. The heat set portion of the alloy tube that is deflected around the hinge 16 forms the implant retaining element 14.

[0063] Figure 2c The graph in shows the relationship between the implant retaining element deflection force (y-axis) and the degree of implant retaining element deflection (x-axis).

[0064] Since the shape memory alloy tube is heat set in a deflected position, there is zero stress at the hinge once the alloy tube is heat set.Figure 2a The hinged portion of the heat set tube is shown in its relaxed position. Figure 2c On the stress-strain curve shown, point A (marked by the arrow) depicts Figure 2a The relaxed position of the hinge portion of the heat-set alloy tube depicted in FIG. 1 , point B (identified by the arrow) depicts the relaxed position of the hinge portion of the heat-set alloy tube depicted in FIG. Figure 2b The fully compressed position of the hinge portion of the heat-set alloy tube depicted in FIG. In the fully compressed position, there is a maximum stress at the hinge portion. In the compressed position, the diameter of the alloy tube is equal to the original diameter OD and the deflection (Δ) is zero degrees. Figure 2c As can be seen in the illustration in FIG, there is a plateau region C (identified by an arrow) in which the deflection force exerted by the implant retaining element remains substantially constant regardless of the degree of deflection of the implant retaining element 14. In this way, regardless of the degree of deflection of the implant retaining element, that is, regardless of the extent to which the implant retaining element 14 extends into the implant 20 or into the covering of the implant, the force exerted on the implant 20 or the covering of the implant remains substantially constant, so that the implant 20 can be more reliably retained when the sheath 8 is retracted.

[0065] like Figure 2c As shown, an alloy tube (e.g., a nitinol tube) exhibits hysteresis. It can be seen that there is a compression branch D and an expansion branch E. In both branches, there is a plateau region C. As described above, in each embodiment, the implant retaining element 14, 18 utilizes this plateau region C. The material stress-strain state follows different curve branches depending on whether the deformation direction is from A to B or from B to A.

[0066] According to one embodiment of the present invention, there is a method for assembling a catheter assembly for transluminal delivery of a self-expanding tubular implant to a site within the body. The catheter assembly includes an inner catheter 2 comprising a shape-memory alloy tube 2; a sheath 8; and a self-expanding implant 20. The method includes the steps of assembling the self-expanding implant 20 onto the shape-memory alloy tube 2, wherein during the assembly step, the shape-memory alloy tube 2 is subjected to a temperature that allows the shape-memory alloy tube to accommodate radially inward pressure exerted on it by the self-expanding implant 20, primarily through martensitic twinning. In this manner, the shape-memory alloy tube 2 is capable of retaining the self-expanding implant 20 on the inner catheter 2.

[0067] The total number of implant retaining elements, their size, their density (i.e., their circumferential and longitudinal spacing), the shape and roundness of their leading edges, and their bending stiffness (determined by the design of the hinge 16) affect their ability to reliably anchor the implant to the inner catheter 2 without damaging the fragile implant covering during loading, implant positioning, device handling, tracking, and deployment. Depending on the specific application and the implant to be deployed, the shape, number, and arrangement of the implant retaining elements, etc., can be selected accordingly. For example, Figure 3 , shows one arrangement. Figure 4 and Figure 5 Some additional examples of implant retention features according to embodiments of the present invention are depicted and described in further detail below.

[0068] In another embodiment, at least a plurality of the first and second pluralities of implant retaining elements 14, 18 are arranged along the length of the cylindrical distal component 4 so that the force exerted on the implant 20 by the at least first and second pluralities of implant retaining elements 14, 18 is evenly distributed along the length of the implant 20.

[0069] The first and second multiple implant retaining elements 14, 18 are not necessarily arranged at the ends of the compressed implant 20. Instead, there may be multiple positions arranged along the length of the long implant 20 to cope with the situation where the multiple implant retaining elements 14, 18 arranged below the distal end of the long implant 20 are detached from the implant 20 once their distal ends are unfolded. Therefore, another multiple implant retaining elements can be arranged further proximally, but not all the way to the proximal end of the implant 20, and then arranged to take over the retention of the implant 20 when the sheath 8 is retracted across the implant 20.

[0070] Refer to further example Figures 2a-2c , the wing 14 may include a hinge portion 16, the wing 14 being arranged to deflect around the hinge portion 16, and the engaging portion 19 being arranged to engage the implant. The hinge portion 16 may extend along a root line and the engaging portion 19 may extend along a contact line for contacting the implant 20. In one embodiment, the root line of the hinge portion 16 is shorter in the circumferential direction than the contact line of the engaging portion 19. In this way, the forces applied to the implant 20 (e.g. a covered implant covered with a fragile ePTFE coating) are distributed. In this way, damage to the covering can be avoided. In one embodiment, the length of the contact line can be up to twice as long as the root line. In this way, damage to the fragile ePTFE coating is also further reduced.

[0071] Figure 3 An inner catheter according to an embodiment of the present invention is shown. Figure 3In the embodiment, the cylindrical distal part 4 is arranged to receive the implant 20. The implant 20 is disposed on the cylindrical distal part 4. The cylindrical distal part 4 may also be referred to as the implant section of the inner catheter 2, since it is the section of the inner catheter 2 that receives the implant. In one embodiment, the cylindrical distal part 4 (implant section) is formed of a nickel-titanium alloy tube, such as Figure 3 The tube is divided into sections 30 with implant retention features 14. These sections 30 are connected by flexible sections 32 of nitinol tube.

[0072] In other words, the cylindrical distal member 4 includes at least one flexible section 32 and at least one implant retaining section 30 having at least one of the first and / or second plurality of implant retaining elements 14, 18. Preferably, the at least one flexible section 32 includes a plurality of staggered circumferentially extending slits 34 to form a universal joint. The slits 34 impart enhanced bending capabilities to the inner catheter 2, thereby facilitating advancement of the distal end of the catheter device along particularly tortuous lumens to implantation sites in the body that are difficult to reach. The slits 34 can be laser cut. In one embodiment, see Figure 3 , at least one implant retaining section 30 and at least one flexible section 32 are alternately arranged along the length of the cylindrical distal component 4 .

[0073] Figure 4 Various embodiments and views of various embodiments are shown, illustrating various retention features according to various embodiments of the present invention. Figure 5 Additional embodiments and various views of embodiments are shown, illustrating various retention features according to embodiments of the present invention.

[0074] like Figure 4 and Figure 5 As shown, the implant retaining element 14 can have various shapes. For example, the implant retaining element 14 can be a wing (see Figure 4 a) and b), arch (see Figure 4 b) in), V-shaped objects (see Figure 5 b)), barbs or spikes (see Figure 5 a) in the figure). Various shapes can be used alone or in combination with other shapes.

[0075] For more details, refer to Figure 4 and Figure 5 : Figure 4 a) to c) and Figure 5 Figures a) and b) show various shapes of implant retention features. Figure 4 i) and Figure 5 i) in FIG. 5 shows the cross-section of the alloy tube of each shape. Figure 4 ii) and Figure 5ii) in FIG. 1 shows a plan view of the alloy tube of each shape. Figure 4 iii) and Figure 5 iii) shows the side view of each shape of the alloy tube. Various shapes can be formed by laser cutting. The laser cut 40 for each of the various shapes is respectively Figure 4 and Figure 5 . Once the appropriate laser cuts 40 are formed according to the desired shape, the shape of the implant retention feature 14 is shaped so that the portion (e.g., the fin) distal to the hinge 16 (where the implant retention feature connects to the alloy tube 2) slightly extends beyond the original diameter by a distance Δ. The angle at which the implant retention element 14 protrudes from the body of the alloy tube 2 is adjusted so that when the implant retention element is compressed by the implant 20 crimped thereon, the region 16 where the implant retention feature 14 connects (i.e., articulates at the hinge 16) to the body of the alloy tube is located at the point along the material stress-strain curve (see Figure 4 ) of the stationary region C (see Figure 5 ). For example, in an embodiment where the alloy tube is a Nitinol tube, the shape of the implant retaining feature 14 is set so that the hinge 16 is in the region of the plateau region of the stress-strain curve of the Nitinol. In this way, the first and / or second plurality of retaining elements 14, 18 are configured so that the forces applied to the implant by the first and / or second retaining elements, respectively, within the deflection range of the hinge are substantially the same within the deflection range. An advantage of this arrangement is that the forces applied to the implant are the same regardless of the deflection, so tolerances are less important.

[0076] In one embodiment, when engaged with the implant 20, the hinge portion 16 is substantially located in a plateau region (zone) C of the material stress-strain curve of at least the first and second plurality of implant retaining elements 14, so that at least the first and second plurality of implant retaining elements 14 exert approximately the same force on the implant 20 regardless of how much they protrude (deflect) from the cylindrical distal portion 4.

[0077] With respect to the various shapes of the implant retaining elements 14, 18 contemplated, in one embodiment, the tabs 14 extend in an arcuate shape around the circumference of the cylindrical distal member 4. As described above, the first and / or second retaining elements 14, 18 can assume a configuration in which the first and / or second retaining elements 14 are deflected about the hinge 16. The hinge 16 can be referred to as a hinge portion 16.

[0078] In one embodiment, the first and / or second plurality of retaining elements 14, 18 are unpolished. In this manner, an implant (particularly, for example, an uncovered stent, such as an uncovered Nitinol stent) can be more effectively retained because the relatively rough surface of the implant retaining elements 14 can more easily engage the structure of the uncovered stent.

[0079] In various embodiments, the first and / or second plurality of implant retaining elements 14, 18 can be located within the wall thickness. In this way, the implant retaining elements 14, 18 do not require their own space and the diameter of the catheter device is reduced.

[0080] Figure 4 The present invention shows a retaining feature according to an embodiment of the present invention and a method of manufacturing a shape memory alloy tube according to an embodiment of the present invention. In particular, Figure 5 A plan view of the alloy tube to be formed into the implant retention feature 14 is shown. Figure 2c In the embodiment shown, the implant retention feature 14 is in the form of a tab having a length L. The length L extends from the base of the hinge 16 to the extent of the laser cut 40 in the longitudinal direction of the alloy tube 2. Figures 7a-7d , a length of wire 60 is shown. Wire 60 is used in forming implant retaining element 14 and is described in more detail below.

[0081] Figure 7a Shows Figures 7a-7d The cross section of the alloy tube is shown without showing line 60. Figure 7a In the cross section, the laser cut 40 is seen. The tabs have not yet been deflected or shaped.

[0082] Figure 7b Shows Figure 7a A side view of the alloy tube 2 shown in FIG. Figure 7b Shows Figure 7c The cross section of the alloy tube 2 is shown in FIG.

[0083] refer to Figure 7a , it can be seen that the tabs can be positioned for shape shaping with their free ends (ends away from the hinge 16) protruding beyond the original diameter OD of the alloy tube 2 by a distance Δ. Figure 7d 、 Figure 7a and Figures 7a to 7d As shown, this can be achieved by inserting a length of wire 60 across. Figure 7aIn the embodiment shown, a section of the nitinol material has been cut away by laser cuts 40 on either side of the fin, rather than just a single pass laser cut such as through the end of the fin. In this way, easy insertion of the lifting tool before the insertion line 60 is achieved. The implant retaining elements 14, 18 are configured so that the hinge portion 16 of the implant retaining elements 14, 18 is in a plateau region C corresponding to the deformation curve when the implant is curled around the implant retaining element (see FIG. Figure 7c Figure 7d Figures 7a-7d Figure 2c The width of the hinge 16 determines the level of force that the flaps 14 can exert when compressed inwardly, ie, the bending stiffness of the implant retaining elements 14, 18.

[0084] Another disclosure includes a catheter device for transluminally delivering a self-expanding tubular implant to a site within a body. The catheter device includes an inner catheter including a cylindrical distal member having a wall thickness, wherein the cylindrical distal member is arranged to be received within a lumen of the implant during use. The catheter device also includes a sheath coaxial with the inner catheter, wherein the sheath is arranged to envelop the implant until, during use, the sheath is proximally retracted relative to the implant and the inner catheter to release (deploy) the implant at the site, wherein the cylindrical distal member includes a first plurality of implant retaining elements that project radially outward from the cylindrical distal member during sheath retraction to engage a radially inward surface of the implant, thereby limiting proximal entrainment of the implant by the sheath relative to the cylindrical distal member. The first plurality of implant retaining elements can be located within the wall thickness, and the first plurality of implant retaining elements have shape memory and utilize a shape memory effect to assume a radially outwardly protruding configuration at body temperature prior to sheath retraction to effectively engage the radially inward surface of the implant. In this way, a more compact arrangement is possible.

[0085] In another embodiment, the first plurality of implant retention elements are located within the wall thickness at a temperature at which the implant is stored on the inner catheter.

[0086] An austenite finish temperature (Af temperature) below body temperature can be used to reduce the forces applied to the inner wall (of a covered implant) during storage of the device at room temperature. In this case, if it is desired to use "gripping" of a retaining element to transfer the implant from the closed crimping head to the sheath, the implant is loaded at a temperature above Af. During storage at temperatures below Af, the applied radial forces are reduced, which is beneficial because polymers exhibit time-dependent deformation behavior (creep), whereby continued pressure exerted by the retaining element on the inner covering of the implant may lead to localized damage to the covering.

[0087] When the device is deployed at body temperature above Af, the full radial force exerted by the retaining element is available.

[0088] The catheter device described herein can be used by a medical practitioner to deploy an implant 20 at a site of implantation in the body. Prior to use, the catheter device is stored in a package (not shown). The medical practitioner removes the catheter device from the package. The medical practitioner advances the catheter device along the body lumen to the implantation site. Once the implantation site has been reached, the additional sheath 8 is retracted by the medical practitioner in a proximal direction. By retracting the sheath 8, the implant 20 is deployed at the implantation site.

[0089] The invention is not limited to the embodiments shown and described above.

Claims

1. A catheter device for delivering a self-expanding tubular implant to a site in the body through a lumen, the catheter device comprising: an inner catheter comprising a cylindrical distal member having a wall, wherein the cylindrical distal member is arranged to be received within the lumen of the implant in use; and a sheath coaxial with the inner catheter, wherein the sheath is arranged to encase the implant until, in use, the sheath is proximally retracted relative to the implant and inner catheter to release the implant at the site, wherein the cylindrical distal member comprises a first plurality of implant retaining elements that project radially outward from the cylindrical distal member during sheath retraction to engage a radially inwardly facing surface of an implant, thereby limiting proximal entrainment of the implant by the sheath relative to the cylindrical distal member, wherein the first plurality of implant retaining elements are formed by a portion of a wall of the cylindrical distal member, and wherein the first plurality of implant retaining elements are configured to assume a radially outwardly protruding configuration prior to sheath retraction to engage the radially inwardly facing surface of the implant using a shape memory effect, wherein at least one of the first plurality of implant retaining elements is a wing arranged to extend distally from a root line in the cylindrical distal member, wherein the wing comprises a hinge portion and an engagement portion, the wing being arranged to deflect about the hinge portion, the engagement portion being arranged to engage the implant, wherein the hinge portion extends along the root line and the engagement portion extends along a contact line for contacting the implant, wherein the root line of the hinge portion is shorter in a circumferential direction than the contact line of the engagement portion.

2. The catheter device according to claim 1, wherein The cylindrical distal member includes a second plurality of implant retaining elements configured to project radially outwardly therefrom to engage a radially inwardly facing surface of an implant utilizing a shape memory effect to limit distal carryover of the implant relative to the cylindrical distal member.

3. The catheter device according to claim 2, wherein At least one of the second plurality of implant retaining elements is a tab arranged to extend proximally from a root wire in the cylindrical distal member.

4. The catheter device according to claim 2, wherein At least a plurality of implant retaining elements of the first plurality of implant retaining elements and the second plurality of implant retaining elements are arranged along the length of the cylindrical distal component so that the force exerted on the implant by at least the first plurality of implant retaining elements and the second plurality of implant retaining elements is evenly distributed along the length of the implant.

5. The catheter device of claim 1, wherein The contact wire can be at most twice as long as the root wire.

6. The catheter device according to any one of claims 1 to 5, wherein: The cylindrical distal component is made of Nitinol.

7. The catheter device of claim 2, wherein: The cylindrical distal member includes at least one implant retaining section having at least one of the first plurality of implant retaining elements and / or the second plurality of implant retaining elements and at least one flexible section.

8. The catheter device of claim 7, wherein: The at least one flexible section includes a plurality of staggered circumferentially extending slots to form a universal joint.

9. The catheter device according to claim 7, wherein The at least one implant retaining section and the at least one flexible section are alternately arranged along the length of the cylindrical distal member.

10. The catheter device according to any one of claims 7 to 9, wherein: At least the first plurality of implant retaining elements and the second plurality of implant retaining elements are disposed in the same implant retaining section.

11. The catheter device of claim 10, wherein: The first and second pluralities of implant retaining elements are circumferentially arranged in at least one row around the cylindrical distal member, wherein the first and second pluralities of implant retaining elements are alternately arranged along the at least one row.

12. The catheter device according to any one of claims 1-5, 7-9, wherein: The first plurality of implant retaining elements are disposed on the cylindrical distal member at locations arranged to be received by a proximal region of the implant.

13. The catheter device according to any one of claims 2-4, 7-9, wherein: The second plurality of implant retaining elements are disposed on the cylindrical distal member at locations arranged to be received by a distal region of the implant.

14. The catheter device of claim 12, wherein: The fins extend in an arc around the circumference of the cylindrical distal member.

15. The catheter device according to any one of claims 2-4, 7-9, wherein: The first plurality of implant retaining elements and / or the second plurality of implant retaining elements assume a configuration in which the first plurality of implant retaining elements and / or the second plurality of implant retaining elements are partially deflected about the hinge portion.

16. The catheter device according to any one of claims 2-4, 7-9, wherein: The first and / or second plurality of implant retaining elements are configured such that a force exerted on the implant by the first and / or second plurality of implant retaining elements, respectively, over a range of deflection of the hinge is substantially the same over the range of deflection.

17. The catheter device according to any one of claims 1-5, 7-9, wherein: The fin is configured as at least one of a barb, an arch, a V-shape, or a point.

18. The catheter device according to any one of claims 2-4, 7-9, wherein: The first plurality of implant retention elements and / or the second plurality of implant retention elements are unpolished.

19. The catheter device according to any one of claims 1-5, 7-9, wherein: The first plurality of implant retaining elements can be located within the wall thickness.

20. The catheter device according to any one of claims 2-4, 7-9, wherein: The hinge portion, when engaged with the implant, is substantially in a plateau region of the material stress-strain curve of at least the first plurality of implant retaining elements and the second plurality of implant retaining elements, such that at least the first plurality of implant retaining elements and the second plurality of implant retaining elements exert approximately the same force on the implant regardless of how much the first plurality of implant retaining elements and the second plurality of implant retaining elements protrude or deflect from the cylindrical distal component.

21. The catheter device according to any one of claims 1-5, 7-9, wherein The root line of the hinge portion is shorter in the circumferential direction than the contact line of the joint portion, thereby distributing the forces exerted on the covered implant covered with the polytetrafluoroethylene coating.

22. A method for manufacturing a shape memory alloy tube for use in a catheter device for delivering a self-expanding tubular implant to a site in the body through a lumen, the method comprising: A hinge is formed in a shape memory alloy tube, the shape memory alloy tube is deformed by deflecting a portion of the shape memory alloy tube about the hinge, and the deformed portion is set by heating the shape memory alloy tube so that the shape memory alloy tube can assume the configuration of a wing at body temperature in which the deformed portion is deflected radially outward from the shape memory alloy tube about the hinge, wherein the wing includes a hinge portion and a joining portion, the wing being arranged to deflect about the hinge portion, the joining portion being arranged to join the implant, wherein the hinge portion extends along a root line and the joining portion extends along a contact line for contacting the implant, wherein the root line of the hinge portion is shorter in a circumferential direction than the contact line of the joining portion.

23. A method of assembling a catheter assembly for delivering a self-expanding tubular implant to a site in a body through a lumen, the catheter assembly comprising an inner catheter comprising a shape memory alloy tube having fins, a sheath, and the self-expanding tubular implant, the method comprising the steps of: A self-expanding tubular implant is assembled on a shape memory alloy tube, wherein during the assembly step, the shape memory alloy tube is at a temperature that allows the shape memory alloy tube to adapt to radially inward pressure exerted on the shape memory alloy tube by the self-expanding tubular implant primarily through martensitic twinning, wherein the fin includes a hinge portion and a joining portion, the fin being arranged to deflect around the hinge portion, the joining portion being arranged to join the implant, wherein the hinge portion extends along a root line and the joining portion extends along a contact line for contacting the implant, wherein the root line of the hinge portion is shorter in a circumferential direction than the contact line of the joining portion.

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