Stent feeding system and method

Abstract

The present invention provides a stent, a stent delivery system, and a stent delivery method that allow for dynamic changes in the porosity of the stent during the delivery procedure. [Solution] Unlike conventional stents and procedures configured to be arranged with a predetermined degree of porosity, it is possible for a physician to generate a region of high stent porosity over a specific vascular feature portion 12 and a region of low stent porosity 120B over another vascular feature portion 12, and these variations in porosity can be generated using at least one stent 120 or stent layer.

Description

Related Applications

[0001] This application claims priority based on U.S. Provisional Application No. 62 / 934,410, filed on November 12, 2019, under the name "Dynamic Stent System", the entire content of which is incorporated herein by reference.

Background Art

[0002] Stents are placed within a patient's vasculature for a variety of therapeutic purposes, such as expanding a stenotic portion of a blood vessel or covering the opening of an aneurysm or similar vascular defect. Physicians typically select a stent for treating a patient based on one or more of the characteristics of the stent, such as the diameter, length, porosity, and ease of placement after expansion. Thus, stents are generally manufactured with a variety of options for diameter, length, and porosity to best fit the treatment needs of the patient.

[0003] Porosity refers to the ratio of the amount of pores, gaps, or openings in the stent wall, often expressed as a percentage. A relatively high porosity correlates with more open space (e.g., larger size and / or higher frequency of pore openings), while a relatively low porosity correlates with less open space (e.g., smaller size and / or lower frequency of pore openings). The desired porosity of the stent wall can be determined using one or more of many different characteristics of the stent, such as its wire diameter, its braiding pattern, and the number of layers forming the stent wall.

[0004] In some treatment situations, it may be desirable for the stent to have relatively high porosity, such that there are many and / or relatively large openings that penetrate the stent's sidewall. For example, Figure 1A shows an aneurysm 12 that bulges laterally along the sidewall of a patient's blood vessel 10. The aneurysm 12 may be treated by delivering embolic material, such as small coils sometimes known as microcoils, into the aneurysm 12. An intraluminal supported stent or "coil-assisted" stent 100 is typically positioned across the entire opening of the aneurysm 12 (either before or after delivery of the embolic material) to assist in receiving the embolic material. The intraluminal supported stent 100 is typically composed of relatively thick wires to fix its position within the blood vessel and to help allow the embolic delivery catheter to pass through if the embolic material is delivered after the stent. Therefore, these stents tend to have relatively high porosity (e.g., larger pore openings) in their structure, and do not always prevent or significantly reduce blood from entering the aneurysm 12.

[0005] On the other hand, it may be desirable for the stent to have relatively low porosity, such that there are a few and / or relatively small openings penetrating the side walls of the stent. To further reduce blood flow into the aneurysm 12, a physician may place a second flow diverter stent (not shown in Figure 1A) with much lower porosity by placing the intraluminal support stent 100 within the placed intraluminal support stent 100, or within a previously placed flow diverter stent. In other words, this flow diverter stent can be placed inside or outside the intraluminal support stent 100. Alternatively, some intraluminal support stents, such as stent 111 in Figure 1B, may have an internally installed flow diverter layer 113, as shown in U.S. Patent No. 9,439,791, the content of which is incorporated herein by reference. These types of stents are known as flow diverters and use a low-porosity flow diverter layer 113 to reduce blood flow into the aneurysm 12. This is one selectable treatment procedure and does not necessarily require the embolization coils described above. Thus, the flow-diversion stent 111 with lower porosity is distinguished from the intraluminal support stent 100 with higher porosity.

[0006] However, depending on the anatomical structure of the blood vessels at the patient's treatment site, it may be undesirable for the physician to block blood flow located immediately adjacent to the opening of the aneurysm 12. Returning to the examples in Figures 1A and 1B, another blood vessel 14 may be providing inflow into or outflow from blood vessel 10. While an intraluminal supported stent 100 may have sufficient porosity to allow blood flow between blood vessels 10 and 14, a flow-conversion stent 111 with lower porosity may undesirably block such a nearby blood vessel 14. In the case of cerebral aneurysms, the blood vessels in the brain are generally small, which can make it difficult to position a flow-conversion stent to cover the aneurysm without covering adjacent vessels.

[0007] Furthermore, while stent manufacturers generally offer a range of sizes, the desired size and porosity of a flow-diversion stent are not always readily available to physicians during treatment. In this regard, there is not always a single stent that can satisfy all the support and flow-diversion characteristics desired by physicians.

[0008] Furthermore, most stents currently on the market are constructed with a single porosity throughout their entire length. Thus, these uniformly porosity stents are not configured to have regions with different porosities, and are therefore typically only capable of performing one specific therapeutic function (e.g., either low porosity for fluid diversion or high porosity for coil-assisted stents, but not both).

[0009] Therefore, what is needed are stents, stent delivery systems, and / or stent delivery methods that allow physicians to better adjust the location within the patient where the area of ​​reduced porosity is placed, and the degree of porosity in that area. [Overview of the project]

[0010] Aspects of the present invention generally relate to stents, stent delivery systems, and stent delivery methods, which involve adjusting the stent porosity separately or in combination during delivery. During delivery, a physician can generate areas of high stent porosity across specific vascular features (e.g., adjacent vascular openings) and areas of low stent porosity across other vascular features (e.g., aneurysms), and these variations in porosity can be generated using at least one stent or stent layer. Thus, physicians can perform some procedures that previously required multiple stents using a single stent, and can dynamically adjust the stent porosity during the procedure as needed.

[0011] One embodiment includes a stent having at least a first region having relatively high resistance to longitudinal compression and a second region having relatively low resistance to longitudinal compression. In one example, one region configured to have relatively low resistance to longitudinal compression is softer than the other region configured to have relatively high resistance to longitudinal compression. The stent may further comprise a high-resistance region and a low-resistance region, such that there are one or more high-resistance regions and one or more low-resistance regions (e.g., one, two, three, four, five, or more regions, respectively).

[0012] The longitudinal compression resistance of different regions of a stent can be achieved in several different ways, such as by including wires of a larger diameter to increase resistance, wires of a smaller diameter to decrease resistance, by changing the braiding pattern, changing the wire material, or changing the coating or plating of a portion of the wire to increase or decrease resistance. These methods can be used individually or in combination with each other.

[0013] Another aspect of the present invention relates to a method for generating longitudinal compression in a stent during delivery by pushing an elongated stent pusher and pulling an outer delivery catheter. This pushing and pulling can be performed such that the longitudinal compression in the stent is substantially increased (i.e., there is more pushing than pulling), thereby compressing at least one region of the stent longitudinally and thus reducing its porosity or increasing its metal surface coverage. Depending on the ratio of pushing to pulling, various porosities can be achieved. Such pushing and pulling may be performed simultaneously or sequentially. Furthermore, this method can be used with stents configured to have greater and less longitudinal compression resistance, or with braided stents having a uniformly longitudinal compression resistance overall.

[0014] Another aspect of the present invention relates to a delivery system useful for indicating or generating a push-pull motion of a pusher relative to a delivery catheter. In one example, the pusher and / or delivery catheter may be provided with a plurality of measuring markers along their longitudinal direction to indicate their relative motion, thereby serving as a marker for a physician to indicate how much push-pull motion is achieved.

[0015] In another example, one or more handle devices can be used to push the stent pusher, pull the delivery catheter, or both. One or more handle devices can be configured to obtain a predetermined push-pull ratio between the stent pusher and the delivery catheter. [Brief explanation of the drawing]

[0016] These and other aspects, features, and advantages made possible by the embodiment of the present invention will be evident and apparent from the following description of embodiments of the present invention with reference to the accompanying drawings.

[0017] [Figure 1A] This is a side view of a stent placed throughout the entire aneurysm.

[0018] [Figure 1B] This is a side view of a fluid diversion stent positioned throughout the entire aneurysm.

[0019] [Figure 2] This is a side view of a stent having a region of reduced porosity according to one embodiment.

[0020] [Figure 3] This is a side view of a stent having regions of compression resistance in different longitudinal directions, according to one embodiment.

[0021] [Figure 4]A side view of a stent having regions of different longitudinal compression resistance according to one embodiment.

[0022] [Figure 5] A side view of a stent having regions of different longitudinal compression resistance according to one embodiment.

[0023] [Figure 6] A side view showing a stent delivery method according to one embodiment.

[0024] [Figure 7] A side view showing a stent delivery method according to one embodiment.

[0025] [Figure 8A] A view showing a changing braiding angle according to one embodiment. [Figure 8B] A view showing a changing braiding angle according to one embodiment.

[0026] [Figure 9] A graph showing the metal surface coverage ratio with respect to the braiding angle of an exemplary stent according to one embodiment.

[0027] [Figure 10] A graph showing the metal surface coverage ratio with respect to the braiding angle of an exemplary stent according to one embodiment.

[0028] [Figure 11] A graph showing the length of an exemplary stent with respect to the braiding angle of the stent according to one embodiment.

[0029] [Figure 12] A side view of a delivery system according to one embodiment.

[0030] [Figure 13] A side view of a delivery system according to one embodiment.

[0031] [Figure 14] This is a side view of a feeding system according to one embodiment.

[0032] [Figure 15] This is a side view of a feeding system according to one embodiment. [Modes for carrying out the invention]

[0033] Specific embodiments are described below with reference to the accompanying drawings. However, these embodiments may be embodied in many different forms and should not be construed as being limited to the embodiments described herein, and these embodiments are provided so as to ensure that this disclosure is thorough and complete and that the scope of the invention is fully conveyed to those skilled in the art. The terms used in the detailed description of the embodiments shown in the accompanying drawings are not intended to limit the aspects of the invention. In the drawings, similar numbers refer to similar elements. Although various embodiments are described, features of each embodiment can be used interchangeably with those of the other embodiments described. In other words, any of the features of each embodiment can be mixed or combined with each other, and embodiments should not be strictly construed as necessarily including only the features shown or described.

[0034] This embodiment generally relates to stents, stent delivery systems, and stent delivery methods, and involves adjusting the stent's porosity separately or in combination during delivery. During delivery, the physician can create areas of high stent porosity over specific vascular features (e.g., adjacent vascular openings) and areas of low stent porosity over other vascular features (e.g., aneurysms), and these variations in porosity can be generated using at least one stent or stent layer. In other words, the stent as a whole may have a generally uniform braiding angle during delivery, and the physician can change this braiding angle in specific areas during delivery to adjust the porosity. Thus, the physician can perform some procedures that previously required multiple stents using a single stent, and can dynamically adjust the stent's porosity during the procedure as needed. The braiding angle will be described in more detail below.

[0035] While this embodiment is generally described in relation to the treatment of aneurysms (e.g., use in fluid diversion or stent-assisted coil embolization), it should be understood that these stents and delivery methods can be used to treat a variety of other medical conditions, such as vascular stenosis and vasospasm (both involving treatment of narrowing or constriction of blood vessels). Therefore, while these stents and delivery methods may be particularly useful in treating aneurysms, this embodiment should not be limited to such treatments alone.

[0036] Figures 1A and 1B show exemplary treatment sites where an aneurysm 12 is connected to the side wall of a blood vessel 10. The aneurysm 12 may be treated by delivering an intraluminal support stent 100 across the entire opening of the aneurysm 12, and then delivering embolic material, such as small coils sometimes referred to as microcoils, into the aneurysm 12 through the stent 100. The intraluminal support stent 100 is generally composed of relatively thick wires to help fix its position within the blood vessel, and therefore tends to have relatively high porosity (e.g., larger pore openings) in its structure.

[0037] However, depending on the anatomical structure of the blood vessels at the patient's treatment site, it may be undesirable for the physician to block blood flow immediately adjacent to the opening of the aneurysm 12. For example, another blood vessel 14 may provide inflow into or outflow from blood vessel 10. While an intraluminal supported stent 100 may have sufficient porosity to allow blood flow between blood vessels 10 and 14, a flow-diversion stent with lower porosity, as shown in Figure 1B, may undesirably block such a nearby blood vessel 14.

[0038] Currently available stents generally employ a continuous porosity property. In other words, these stents are manufactured (e.g., braided and heat-treated) to form a uniform porosity over almost their entire length when placed in a relatively straight and uniform blood vessel. Thus, with typical stents, a physician cannot determine the porosity of a particular region of the stent during treatment. For example, if the vascular condition in Figure 1B is treated with a flow diversion stent 111 (e.g., low porosity is employed to reduce blood flow to the aneurysm 12), the continuous porosity property of typical stents ensures that nearby blood vessels 14 are also covered by a low-porosity region, because the entire stent has a similar porosity property. While the low-porosity property is useful in the vicinity of the aneurysm 12 (e.g., when stent 111 is used for flow diversion), this low-porosity property can cause a reduction in blood flow to nearby blood vessels 14, which may not necessarily be beneficial for the nearby blood vessels 14.

[0039] To address these problems, some embodiments presented herein utilize stents that can be generated by a physician during a treatment procedure, with portions or regions having different porosity.

[0040] Figure 2 shows a stent 120 according to one embodiment, which is fed to have regions of lower porosity and regions of higher porosity. Specifically, the illustrated stent 120 comprises a proximal region and a distal region 120A having relatively higher porosity compared to an intermediate region 120B with relatively lower porosity. Alternatively, the region of relatively lower porosity can be generated in either the proximal region or the distal region 120A, in both regions 120A, or over most or all of the entire stent 120.

[0041] As will be further detailed below, the delivery of a stent 120 having regions of different porosity can be achieved by 1) constructing the stent 120 so that regions of the stent are compressed more longitudinally during the delivery and placement procedure, 2) delivering the stent 120 via a combination of pushing and pulling of an internal delivery pusher and an external delivery catheter, or 3) a combination of both stent construction and delivery methods. In some embodiments, the stent 120 can be delivered to have regions of different porosity such that the stent 120 first has an initial (e.g., uniform) porosity, and then, upon delivery, forms one or more regions of different porosity. Stents having regions with reduced resistance to longitudinal compression may be useful in achieving such changes in porosity during the procedure, although stents with uniform resistance to longitudinal compression throughout are also available.

[0042] Longitudinal compression refers to the decrease in length between the proximal and distal ends (left and right sides in the diagram) of a stent region. Longitudinal compression resistance refers to the resistance obtained in the stent region against such longitudinal compression.

[0043] First, looking at the structure of the stent, the stent 120 can be manufactured so that certain areas are more easily compressed longitudinally, while other areas have relatively greater resistance to compression. When the stent 120 is deployed (for example, pushed distally), the areas with greater resistance to longitudinal compression will resist compression considerably overall, while the areas with less resistance will compress much more longitudinally, depending on the magnitude of the distal longitudinal force applied by the physician during the delivery procedure.

[0044] Figure 3 shows an example embodiment of a stent 130 having a proximal and distal region 130A with greater resistance to longitudinal compression and an intermediate region 130B with less resistance to longitudinal compression. Specifically, the stent 130 is braided with wires, and one or more wires have relatively greater resistance to bending than the remaining braided wires 101.

[0045] In one example, each compression-resistant region 130A can be braided using one or more longitudinal support wires 132 having a larger diameter than the remaining structural stent wires 101. For example, the wires 132 may have a diameter that is 1 to 50% larger than the remaining wires 101. In another example, the wires 132 may have a diameter that is approximately 0.0005 to 0.001 inches larger than the remaining wires 101. The wires 132 with the larger diameter will have higher strength than the remaining structural stent wires 101 with the smaller diameter, and will therefore resist compression better, resulting in region 130A having greater compression resistance than other regions of the stent 130.

[0046] In one example, the body of the stent (e.g., the entire length of the stent 130) can be braided with a single wire or multiple wires 101, and at least one wire 132 can be braided between one or more wires 101 in areas intended to resist longitudinal compression (e.g., area 130A). In this way, one or more wires 101 are braided throughout the entire stent 130, and one or more wires 132 of a larger diameter are selectively braided throughout the area 130A that resists compression of the stent 130.

[0047] Alternatively, at least one wire may be connected in a manner other than braiding. As seen in stent 144 in Figure 5, the wire 146A can be connected longitudinally along the length of stent 130 via a plurality of loosely configured connectors (not shown). The connectors allow each end of the wire 146A to slide along the wire 101 to which it is attached, so that the longitudinal wire 146A does not hinder or suppress radial expansion and contraction and the associated shortening (i.e., longitudinal contraction of the stent that occurs as the stent expands radially). In other words, the sliding connectors allow the wire 146A to slide and adapt to shortening during expansion. Alternatively, the longitudinal wire may consist of a plurality of wire divisions 146B (also seen in Figure 5), which can be arranged linearly or nonlinearly with respect to the longitudinal axis of stent 144. Using wires 146A, 146B, or a combination of these two wires, a region 144A with a larger longitudinal compression resistance can be created relative to a region 144B with a smaller longitudinal compression resistance.

[0048] In another embodiment, the aforementioned wire 132 can be constructed from a different material than that of wire 101 to create a difference in longitudinal compressibility. Such a difference in material can be applied in addition to, or as a substitute for, the aforementioned difference in diameter. For example, the stent wire 101 may be made of nitinol, while the compression resistance wire 132 is made of stainless steel, tantalum, or platinum. Furthermore, the difference in material can be created by other means, such as coating or electroplating a wire formed from the second material with the first material.

[0049] In another example, part or all of the wire 101 can be constructed from a stretch-filled tube. The stretch-filled tube wire can consist of a radiopaque core material (e.g., platinum or tantalum) and a shape-memory jacket, i.e., an outer layer (e.g., nitinol). One advantage of a stretch-filled tube wire stent is that, by incorporating radiopaque material within the wire, the entire length of the stent has some degree of radiopaque visibility, thereby reducing or eliminating the need for additional radiopaque markers. Furthermore, since stretch-filled tube stents are generally softer than conventional stents, the intermediate portion is more conformable, thereby allowing it to conform to the geometric shape of the treatment site. Thus, since stretch-filled tube stents do not require separate radiopaque material for visibility, they can potentially be smaller in size and are usually less rigid than conventional stents. As will be discussed separately herein, further techniques can be used to increase resistance to longitudinal compression in certain regions of a stent primarily composed of stretch-filled tubes. An example of a stent consisting of a stretched and filled wire can be found in U.S. Patent Application No. 16 / 685995, filed November 15, 2019, the contents of which are incorporated herein by reference.

[0050] Stents composed of stretched-filled wires can achieve relatively flexible longitudinal compression (compared to some other metal wires, such as nitinol), and since the stretched-filled wires can be radiopaque, it can be particularly easy for a physician to visualize the entire stent by fluoroscopy or similar techniques while applying a desired amount of longitudinal compression to the stent (the method of compression will be described later herein). Depending on the visualization technique, the physician may be able to observe the porosity of the entire stent and compress the stent until one or more regions of the stent achieve a desired change in porosity. In other words, the physician can not only easily see which regions of the stent are being subjected to longitudinal compression, but also see the relative amounts of compression and porosity being applied. In this regard, one embodiment of the herein also includes a method for visualizing a stretched-filled wire stent, applying longitudinal compression, and determining when a desired change in porosity has been achieved. The desired change in porosity can be determined relatively by comparing the uncompressible region of the stent with the compressible region (e.g., by visual inspection), or by measuring the pore size of the stent using a marker or measuring device (e.g., one incorporated into an X-ray fluoroscopy system).

[0051] In one embodiment, the stent structural wire 101 is a metal (e.g., nitinol, stainless steel, or cobalt-chromium) and can consist of one or more wires wound in a single-layer tube shape. In one embodiment, the stent consists of one or more stretched filling wires that are braided and wound in a single-layer tube shape.

[0052] In another example, different regions 130A and 130B may have different braiding patterns such that they increase or decrease resistance to longitudinal compression by different amounts. For example, spiral braiding, circumferential braiding, and multilayer braiding can be used in various regions of the stent 130.

[0053] As shown in Figure 4, it is possible to have most or all of the wires within regions 140A and 140B of the stent 140 have properties that increase or decrease longitudinal compression. For example, the proximal and distal regions 140A may be braided almost entirely with wire portions that have relatively high resistance to longitudinal compression, while the intermediate region 140B may be braided almost entirely with wire portions that have relatively low resistance to longitudinal compression.

[0054] These regions 140A and 140B can be created in various ways. For example, different regions can be braided separately and then joined together (e.g., by welding or tying wires). Each region can be wound with one or more wires of different diameters, different materials, different braiding patterns, or any combination thereof.

[0055] In another example, a single wire may be formed from divisions of a wire having different materials or diameters. These different divisions have lengths and spacing such that divisions of a particular material / size align in different areas of the stent. For example, when the wire is braided on a mandrel, a first division of the wire aligns with area 140A, and a second division of a different diameter / material aligns with area 140B.

[0056] In another example, the stent 140 may first be braided with one or more wires 101, and then treated to create a change in size or material in each region of the stent 140. In one method, the stent 140 may be braided with one or more structural wires 101, and the intermediate region 140B may be electropolished to reduce the diameter of the portion of the one or more wires 101 in region 140B, thereby reducing the resistance to longitudinal compression of region 140B compared to the adjacent region 140A. Alternatively, the stent 140 may be braided with one or more wires 101, and the proximal and distal portions 140A may be electroplated or coated to increase the diameter of the portion of the one or more wires 101 in region 140A, thereby increasing the resistance to compression along region 140A. Such coating or electroplating can create a new layer of the same material as part 101 on part 142 of the wire, but it is also possible to coat / plate part 142 with a different material.

[0057] Here again, regions 130A, 130B, 140A, and 140B of the stent 130 can be in positions different from those shown in Figures 3 and 4. For example, regions 130A and 130B can be reversed. In another example, the stent may have two, three, four, five, six, or more regions, each having a different combination of regions with different resistances to longitudinal compression.

[0058] Generally, a region with reduced longitudinal resistance is configured to compress with a force less than the force that moves or slides the distal end of the deployed stent within the patient's blood vessel. In other words, when a stent is being deployed, it is usually undesirable for the stent to slide within the patient's blood vessel, as this could cause the stent to shift from its intended target site. Since a distal pushing force is applied to the stent to cause longitudinal compression, it is preferable that the region with reduced longitudinal compressive resistance is compressed longitudinally before it overcomes the force that fixes the distal end of the stent. In some examples, the region with reduced longitudinal compressive resistance is configured to compress longitudinally when a longitudinal force ranging from approximately 1 to 5 pounds is applied to that region from a pusher.

[0059] A stent can be constructed using separate regions with different resistances to longitudinal compression, or it may be constructed so that the longitudinal compression changes gradually. For example, longitudinal compression may be most likely to occur in the center of the stent (meaning the lowest resistance to longitudinal compression occurs there) and gradually increase towards its proximal and distal ends. Such a stent can be constructed, for example, by braiding compression-resistant wires 132 that decrease in number from the ends of the stent towards the center. Alternatively, one or more compression-resistant wires 132 may have a diameter that decreases from the ends of the stent towards the center (meaning the diameter of the wires 132 is thickest at the ends and smallest in the center) and be braided together with wire 101. In another alternative, the stent may have a braiding pattern that gradually reduces its longitudinal compression resistance towards the center of the stent.

[0060] Stents 130 and 140 (or any other stent as described herein) may include radiopaque components to aid visualization during the procedure and to help indicate regions of different compressive resistance. For example, the compressive resistance wire 132 in Figure 3 may be made of or coated with a radiopaque material. In another example, a radiopaque marker, i.e., a wire coil 122, may be fixed or wrapped around wires 101, 132, or 142 at a location on the outer circumference of the stent, near the edges of regions of different compressive resistance (e.g., between region 130A and region 130B). In a particular example, the radiopaque markers are positioned at the proximal and distal ends of stent regions where the longitudinal compressive resistance is reduced.

[0061] The exemplary stents described herein are shown as intraluminal support stents formed from at least one single wire 101 braided into a tubular shape, having a plurality of loops 102 at both ends, with a plurality of radiopaque coils 104 on at least some of the loops 102. Such stents are generally described in U.S. Patent No. 9,439,791, the contents of which are incorporated herein by reference. Other embodiments and variations of such stents and exemplary feeding mechanisms can be found in U.S. Patents No. 1,0182,931, 1,032,2020, 1,033,5299, and 1,061,7544, these U.S. patents are also incorporated herein by reference. However, other braided stent configurations can also be used according to the embodiments described herein.

[0062] In some cases, a stent is classified as a flow diverter if the metal surface coverage of the device (meaning the total surface area of ​​the metal constituting the stent relative to the total surface area of ​​the stent) is at least 30%. Flow diverters generally have relatively high metal surface coverage and low porosity because these stents are configured to reduce blood flow to an aneurysm. Coil-assisted stents, on the other hand, can have a metal surface coverage of less than 30% (e.g., about 20% to 36%) and generally have lower metal surface coverage and higher porosity than flow diverters, as the stent pores are often used as entry points for a microcatheter that passes through one of the pores to deliver embolic material (e.g., embolic coils) to the aneurysm. In current medical practice, stents are generally classified as either intraluminal-supported stents or flow diverter stents (related to aneurysm treatment) due to their fixed porosity of a given size, and therefore, these stents are usually used for only one therapeutic purpose each.

[0063] In some cases, the stent can be delivered to have at least one highly porous portion that can be considered as an intraluminal support region and at least one less porous portion that can be considered as a flow diversion region. For example, the middle portion of the stent can be delivered to have lower porosity and be considered as a flow diversion region, while the end portion of the stent can have higher porosity and be considered as an intraluminal support region.

[0064] It should be emphasized that regions of different porosity in some embodiments of stents are generated and controlled during the delivery procedure to allow the physician to control where (i.e., regions of the stent) the porosity of the stent should be changed, and to what extent the porosity should be changed. At least some of the stents described herein, such as stents 100, 120, 130, and 140, can expand to a relatively uniform porosity on their own without significant longitudinal compression, and therefore this longitudinal compression remains an important mechanism for changing the initial porosity of such stents. For example, stents 100, 120, 130, and 140 may have regions with different numbers of wires or different wire thicknesses, which may not in itself have a significant effect on the porosity of different parts, and instead, these techniques are used to change the longitudinal compression characteristics in different regions of the stent. In the stent delivery procedure described herein, one or more regions of the stent are compressed longitudinally during the stent delivery procedure, thereby changing the porosity properties along different regions of the stent.

[0065] In this regard, this embodiment also includes one or more methods for arranging a stent to generate stent regions having different porosities. These methods can be used with standard intraluminal supported stents such as stent 100 (i.e., stents with relatively uniform resistance to longitudinal compression) or with stents such as stents 120, 130, and 140 that have regions with different longitudinal compressive strengths in order to vary the porosity. Furthermore, existing stents with variations in porosity (e.g., regions with higher porosity when compressed in a non-longitudinal direction) can also be used with the configuration techniques and arrangement methods described herein.

[0066] One embodiment relates to a method for generating longitudinal compression in a stent during stent placement. In an exemplary embodiment, this longitudinal compression is generated by advancing a pusher, i.e., an elongated stent placement mechanism, distally after a portion of the stent has been placed.

[0067] In another exemplary embodiment, longitudinal compression is generated by a combination of 1) advancing a pusher, i.e., an elongated stent placement mechanism, distally after a portion of the stent has been positioned, and 2) retracting the outer delivery catheter surrounding the stent. The pusher and delivery catheter can be pushed and pulled in various ratios to achieve the desired porosity of the stent. Pushing and pulling can be done simultaneously or alternately. Generally, pulling the outer delivery catheter exposes a portion of the stent, while advancing the inner pusher distally pushes the proximal portion of the stent forward distally. The distal end of the stent is usually fixed in place, as it is the first to expand and first to be fixed within the patient's blood vessel, thus compressing the proximal portion of the stent longitudinally and thereby increasing the porosity in the region of the stent closer to the delivery catheter.

[0068] Figures 6 and 7 illustrate an exemplary method for stent placement according to one embodiment. Typically, a guidewire (not shown) is advanced into the patient's body, with its distal end positioned at or near the target site, such as an aneurysm. Next, as shown in Figure 5, a relatively large guide catheter 158 is advanced along the guidewire, with its distal end positioned at or near the placement site, and the guidewire is then removed.

[0069] Next, a delivery device is advanced through a guide catheter. The delivery device may consist of a delivery catheter 150 having an elongated lumen, passage, or channel between its proximal and distal ends. The delivery device may also include an elongated pusher 152 that is longitudinally movable within the lumen, passage, or channel of the delivery catheter 150. Preferably, the pusher has a mechanism at or near its distal end that engages with the stent 120 so that the stent 120 is pushed distally by the pusher 152. Note that although this embodiment is shown illustratively with respect to the stent 120, any of the various stent embodiments to which the various approaches described herein are applied may be used to obtain a stent having regions with different porosity.

[0070] For example, the pusher may have a distal raised projection 154 and a proximal raised projection 156. These projections can be in the form of radiopaque cylinders, star shapes, or other similar shapes. Preferably, the distal raised projection 154 is sized to fit into an opening of the stent 120, such as a loop 102, and the proximal raised projection 156 is sized and positioned to contact the proximal end of the stent (e.g., the end of the stent loop 102). Thus, the stent 120 can be pushed distally or pulled back into the microcatheter as needed. Again, various different pushers and other stent engagement mechanisms, as found in the aforementioned patents incorporated herein by reference, can be used as alternatives.

[0071] As shown in Figure 6, the delivery catheter 150 is usually advanced distal to the aneurysm 12, or to the distal end of the target site. The pusher 152 may be held in place when the delivery catheter 150 is pulled proximal to expose the distal end of the stent 120, and the stent 120 engages with and fixes itself to the blood vessel 10 by expanding radially.

[0072] As shown in Figure 7, the pusher 152 is advanced distally by the physician, and the delivery catheter 150 is pulled back proximal, pushing the stent 120 longitudinally and creating an intermediate region 120B with higher porosity than the original, lower-porosity end region 120A. This pushing and pulling can be done simultaneously or alternately in small increments. The ratio or amount of pushing and pulling generally determines the porosity of the higher-porosity region 120B, along with other known factors such as wire size, braid pattern, and stent diameter.

[0073] Braided stents typically exhibit an exponential increase in metal surface coverage and a decrease in porosity as the braiding angle increases. Therefore, braided stents are often constructed and designed by adjusting the braiding angle based on the desired metal surface coverage and opening force. For example, Figure 8A shows an enlarged portion of stent 120 where a first wire 101A intersects with a second wire 101B, creating a braiding angle 101C between the longitudinal axis 103 of the stent 120 and one of the wires 101A. Figure 8B shows that as a region of stent 120 is compressed longitudinally, the braiding angle 101C increases, resulting in a decrease in the length 101D of the pores / openings (e.g., the rhombus shape in the figure) along the direction parallel to the stent axis 103. These openings or rhomboid sections narrow along the direction parallel to the stent's axis (i.e., between the left and right sides of the diagram), so in the longitudinally compressed region of the stent, the number of picks per inch increases, increasing the metal surface coverage and decreasing the porosity.

[0074] Figure 9 shows a graph of one exemplary simulation illustrating the change in metal surface coverage as the braiding angle changes for a 48-wire stent (corresponding to a typical single-layer flow diverter stent with a relatively large number of wires). Figure 10 shows a graph of another exemplary simulation illustrating the change in metal surface coverage as the braiding angle changes for a 16-wire stent (corresponding to a typical coil-assisted or intraluminal-supported stent with a relatively small number of wires). Generally, the metal surface coverage (%) can be quantified based on the braiding angle of each stent configuration. Note that while a specific number of wires is mentioned, this "number" of wires may also refer to the portion of wire located in the cross-section of the stent's braiding pattern. For example, a single wire can be braided back and forth between the proximal and distal ends of a stent to generate 16 or 48 (or other numbers of wires) "wires," i.e., wire portions. Therefore, in this regard, the term "(multiple) wires" should not necessarily be interpreted as referring to literally separate wire materials.

[0075] Metal surface coverage is the inverse of porosity; theoretically, adding the percentage of porosity to the percentage of metal surface coverage results in approximately 100%. While porosity represents the percentage of open space in the stent, metal surface coverage represents the percentage of the stent covered by the metal stent elements. Therefore, a low percentage of metal surface coverage corresponds to a high percentage of porosity, and a high percentage of metal surface coverage corresponds to a low percentage of porosity. Thus, a larger braiding angle corresponds to a higher percentage of metal surface coverage, and therefore to lower porosity.

[0076] These exemplary stents are composed of 16 wires with a diameter of approximately 60 microns, or 48 wires with a diameter of approximately 31.75 microns, resulting in a diameter of approximately 4 mm. By using mathematical principles regarding the relationship between the braiding angle, braiding pitch, and number of braiding turns, various configurations and corresponding percentages of metal surface coverage can be obtained. In two configurations, the metal surface coverage increases exponentially when the braiding angle exceeds approximately 60 degrees. Between approximately 30 and 60 degrees, the increase is more stable. In one embodiment, a braided stent configured with a braiding angle of approximately 60 degrees features a metal surface coverage of approximately 35%. The metal surface coverage can be increased by approximately 35% to 80% in the area of ​​interest by controlled longitudinal compression (along the longitudinal axis of the stent).

[0077] Figure 11 simulates compression for a 16-wire braided stent (e.g., Figure 10), showing the interrelationship between longitudinal compression, change in the braid angle of the device, and change in the length of the device, obtained by keeping the total length of the wires constant and varying the braid angle and braid pitch. A longitudinal compression of approximately 50% changes the braid angle from approximately 60 degrees to approximately 75 degrees, and the metal surface coverage increases from 22% to 42%, nearly doubling.

[0078] Table 1 below shows several examples of the amount to push the pusher and the amount to pull the delivery catheter to achieve a desired braiding angle and increase the porosity or surface coverage of a portion of the stent (e.g., the exemplary stent in Figure 10). Conventional stent delivery does not aim to provide substantial indentation or longitudinal compression. For example, the delivery catheter may be largely pulled back from the pusher to expose the stent and expand it radially. Alternatively, as seen in the first row of Table 1, the physician may push the pusher while pulling the outer delivery catheter to avoid causing substantial longitudinal compression to the stent. Thus, in conventional delivery methods, the initial braiding angle of a portion of the delivered stent is the same as the final braiding angle of the delivered stent, and no increase in surface coverage or decrease in porosity occurs.

[0079] Table 1 JPEG2026123037000002.jpg57166

[0080] Table 1 also shows that in at least one embodiment, increasing the distal pushing amount of the pusher 152 relative to the proximal pulling / retraction amount of the delivery catheter 150 results in a substantial longitudinal compression that increases the final braid angle in the region of the stent, leading to an increase in surface coverage or a decrease in porosity. The substantial amount of longitudinal compression applied to the stent 120 typically determines how much the final braid angle (e.g., Figure 8B) changes from the initial braid angle (e.g., Figure 8A), and thus determines the percentage increase in metal coverage in one region of the stent 120.

[0081] In one embodiment, the physician can grasp each device and, as described above, push the pusher 152 and pull the delivery catheter by hand. In one embodiment, the pusher 152, the delivery catheter 150, or both may be provided with multiple measurement markers that help indicate the relative positions of these devices and their positions relative to the outer guide catheter 158.

[0082] For example, Figure 12 shows the guide catheter 158, the delivery catheter 150, and the proximal end of the pusher 152. The pusher 152 may be provided with multiple measurement marks 161 along at least the proximal portion of its entire length to indicate the movement of the pusher 152 relative to the proximal end of the delivery catheter 150 (e.g., the delivery catheter hub 150A). Similarly, the delivery catheter 150 may be provided with multiple measurement marks 163 along at least the proximal portion of its entire length to indicate the movement of the delivery catheter 150 relative to the outer guide catheter 158 (e.g., the guide catheter hemostatic valve 158A). Thus, the physician can better determine the amount and ratio of pushing / pulling between the pusher 152 and the delivery catheter 150.

[0083] Figure 13 shows another embodiment, which includes a handle 160 connected to the proximal portion of the pusher 152, allowing the user to more accurately advance the pusher 152 distally via a user interface element such as a thumbwheel 162. For example, the thumbwheel 162 may be connected to a gear mechanism (e.g., rack and pinion 167) within the handle 160 (e.g., via a clamping mechanism), which is also further connected to the pusher 152. In one embodiment, the thumbwheel 162 may be configured to have a number of rotational clicks indicating the movement of a specific distance (e.g., 1 mm) of the pusher 152, so that the physician can better determine the amount of longitudinal compression and thereby better determine the final porosity of a region of the stent 120. The aforementioned markings may also be provided to further assist in indicating the relative movement between the pusher 152 and the delivery catheter 150.

[0084] Figure 14 shows an alternative embodiment of the handle 170 configured not only to move the pusher 152 but also to move the delivery catheter 150 in conjunction with it. In one example, the handle 170 may include a tube 172 positioned around the pusher 152 and connected to the proximal end of the delivery catheter (e.g., hub 150A). This configuration allows the handle 170 to push the pusher 152 distally and pull the delivery catheter 152 proximally.

[0085] In one embodiment, the thumbwheel 162 can simultaneously control the movement of both the pusher 152 and the delivery catheter 150. Furthermore, the gear mechanism within the handle 170 can be configured to push and pull at a predetermined ratio to achieve a predetermined porosity of the stent area (e.g., one of the ratios in Table 1). The handle 170 may further include a ratio adjustment member (e.g., a switch, wheel, button, etc.) to change the push / pull ratio. Thus, the physician can determine the desired amount of porosity on the handle 170 during the procedure.

[0086] Figure 15 shows another embodiment in which the pusher 152 can be moved using the aforementioned handle 160, and the delivery catheter 150 can be moved using a separate, similar handle 180. These handles 160, 180 can be configured to generate one or more push / pull ratios between the pusher 152 and the delivery catheter 150, and adjustment mechanisms can be provided so that the user can adjust the push / pull ratio to a desired amount. Furthermore, the aforementioned markings can be used to assist in monitoring the relative positional changes between these devices.

[0087] The aforementioned handles can be driven manually or by an electric motor via a thumbwheel or similar mechanism. In this regard, the handles may further include an electronic interface capable of monitoring and displaying positional changes and being electronically configurable to adjust or generate a desired push / pull ratio. In one embodiment, the electronic interface may be provided that, upon input by the user of stent characteristics such as manufacturer, model, number of braided wires, and size of the expansion diameter, and further input of a desired porosity or surface coverage of a region of the stent, automatically determines the appropriate amount of push / pull of the pusher 152 and delivery catheter 150. The electronic interface can determine this push / pull ratio by referring to a stored database or chart, or by performing calculations based on the input information.

[0088] The concept of a handle can have several further advantages when used in conjunction with a DFT stent (as previously described, which visualizes the entire stent without requiring additional radiopaque elements by using one or more stretched filling wires). One advantage is that a physician can use the handle to create a specific desired porosity or metallic surface coverage feature on at least a portion of the stent, and then visually determine whether the configured feature is suitable for a particular procedure (for example, whether the stent appears to be configured to form an intended target, i.e., whether a portion of a stent configured for the purpose of flow diversion is formed to accomplish this task). If further modifications are needed, the physician can use the handle to further alter the shape of the stent being delivered.

[0089] Furthermore, if the concept of such a handle is not applicable, and instead the physician uses a push / pull technique (pushing the stent while pulling the catheter to change the porosity characteristics of a portion of the stent), the use of DFT stents allows the physician to visually determine how the stent is responding to the use of that technique and then adjust the technique to adjust the stent to the desired porosity characteristics (e.g., pushing the pusher further or pulling the catheter further). In other words, the ability to visualize the stent as it changes its shape and porosity characteristics in real time has a clear advantage in terms of the physician's ability to determine how to adjust the stent during delivery.

[0090] It should be noted that this is a specific advantage of highly radiopaque stents such as DFTs, where the presence of DFT wires allows for visualization of the entire or substantially entire stent; however, such advantages can be observed to some extent in other stents where at least a significant portion of the stent is visualized. One advantage of DFT stents, however, is that there is no need to add further radiopaque components to the stent for visualization, and the entire stent itself can be easily visualized using only the structural DFT wires that form the stent.

[0091] While this embodiment has described providing a stent, system, and delivery method that induces longitudinal compression to reduce the porosity of the stent, it is clear that the reverse procedure is also possible. Specifically, a physician may position a stent that is relatively porosity-poor in its original state but capable of increasing porosity in specific regions. For example, this can be achieved using similar stent regions that vary longitudinal compression and a technique of pulling a pusher proximal to the delivery catheter.

[0092] While the present invention has been described in relation to specific embodiments and uses, those skilled in the art will be able to generate further embodiments and modifications in light of this teaching without departing from the spirit of the claimed invention or exceeding the scope of the claimed invention. Accordingly, it should be understood that the drawings and descriptions herein are provided as examples to facilitate understanding of the invention and should not be construed as limiting the scope of the invention.

Claims

1. One or more structural wires woven to form a tubular shape, A first stent region having a first longitudinal compression resistance, It comprises a second stent region having a second longitudinal compressive resistance smaller than the first longitudinal compressive resistance, The stent is configured to have a selective porosity by the user during placement. Stent.

2. The stent according to claim 1, wherein the first stent region and the second stent region are configured to be arranged having a first degree of porosity, and the second stent region is configured to be compressed longitudinally with respect to the first stent region during feeding to generate a second degree of porosity lower than the first degree of porosity.

3. The stent according to claim 2, further comprising one or more longitudinal support wires disposed in the first stent region such that the longitudinal compression resistance in the first stent region is increased compared to that in the second stent region.

4. The stent according to claim 2, wherein the one or more longitudinal support wires have a larger diameter than the one or more structural wires.

5. The stent according to claim 2, wherein the one or more longitudinal support wires are made of a different material from the one or more structural wires.

6. The stent according to claim 2, wherein the one or more structural wires are composed of stretched and filled tubes.

7. The stent according to claim 2, wherein the diameter of one or more structural wires is reduced within the second stent region.

8. The stent according to claim 2, wherein the one or more structural wires are arranged in a first braiding pattern in the first stent region and in a second braiding pattern in the second stent region.

9. The stent according to claim 2, further comprising a third stent region having the first longitudinal compression resistance, adjacent to the second stent region and located on the opposite side of the first stent region.

10. A method for positioning a stent, The steps include: expanding the distal end of the stent radially within the patient's blood vessel; The steps include pushing the elongated stent pusher connected to the stent distally, The procedure includes the step of pulling the delivery catheter surrounding the stent pusher in a proximal direction, The elongated stent pusher is pushed distally to a distance greater than the distance the delivery catheter is pulled, so as to cause longitudinal compression in the first region of the stent. method.

11. The method according to claim 10, wherein the ratio of the amount pushed to the amount pulled is 1.5 to 1.

12. The method according to claim 10, wherein the ratio of the amount pushed to the amount pulled is 2:

1.

13. The method according to claim 10, wherein the ratio of the amount pushed to the amount pulled is 3 to 1.

14. The method according to claim 10, wherein the first region of the stent has less resistance to longitudinal compression than the second region of the stent.

15. The method according to claim 10, further comprising the steps of pushing distally and / or pulling proximally via a handle mechanism connected to either the stent pusher or the delivery catheter.

16. A stent supply system, The first handle assembly is configured to be attached to a stent pusher and includes a position adjustment element configured to move the longitudinal position of the stent pusher relative to the surrounding delivery catheter. Supply system.

17. The delivery system according to claim 16, further comprising a plurality of measurement markers arranged on the stent pusher and configured to indicate the longitudinal position of the stent pusher relative to the delivery catheter.

18. The delivery system according to claim 16, wherein the first handle assembly is attached to the delivery catheter and further configured to move the delivery catheter relative to the stent pusher.

19. The delivery system according to claim 16, further comprising a second handle assembly attached to the delivery catheter and configured to move the delivery catheter relative to the stent pusher.

Images