Method for delivering a self-expanding stent to a venous sinus

Abstract

The present application discloses a method for delivering a self-expanding stent to a venous sinus, comprising: inserting a stent delivery system into the venous sinus; navigating the stent delivery system to position the stent at a target site in the venous sinus; deploying the stent at the target site by pulling a sheath backward over the stent; and removing the stent delivery system from the venous sinus by pulling a delivery tip through a lumen in the stent.

Description

[0001] This application is a divisional application of the Chinese invention patent application with the application date of March 8, 2018, application number 201880020912.1, and name “Method and system for delivering a self-expanding stent to a venous sinus” (the application number of the corresponding PCT international application is PCT / US2018 / 021527).

[0002] Cross-citation to related applications

[0003] This application claims priority to and the benefit of U.S. patent application No. 15 / 456,352, filed on March 10, 2017, which is hereby incorporated by reference in its entirety. Technical Field

[0004] Certain embodiments relate to stents and systems and methods for delivering stents. More specifically, certain embodiments relate to methods and systems for treating stenosis or collapse in a venous sinus by delivering a self-expanding stent. In various embodiments, the self-expanding stent includes a proximal end having a first radially outward expansion strength (RES) greater than a second radially outward expansion strength (RES) at a distal end of the stent. In a representative embodiment, the proximal end of the stent has a diameter greater than a diameter at the distal end of the stent. In certain embodiments, the stent delivery system and / or stent increases in flexibility from the proximal end to the distal end of the system and / or stent. Background Art

[0005] When blood leaving the brain is slowed due to restrictions in the venous sinuses, it leads to an increase in distal blood pressure, which can translate into an increase in cerebral fluid pressure. Patients experiencing increased intracranial pressure (ICP), in which the cerebrospinal fluid (CSF) pressure in the skull is already elevated, may suffer from headaches, vision loss, and / or tinnitus, among other things. The preferred methods for treating collapse and / or stenosis in the sigmoid and / or transverse sinuses are medications and / or the use of shunts to relieve CSF fluid pressure. However, the use of medications or shunts is not ideal because both are temporary solutions, each with associated risks.

[0006] Recently, a new surgery has been performed that includes placing a stent in the patient's sinus system to improve the collapse and / or stenosis in the sigmoid and / or transverse sinuses and restore improved blood flow out of the brain. The stents used in the new surgery are generally the same as those used in surgeries on other parts of the body (e.g., the carotid arteries). However, the sinus structure is not like any vein or artery in other parts of the body. Instead, the sinus is a space created at the junction of the dura mater and forms a cavity (i.e., a sinus) primarily along the inside of the skull. The dura mater is not lined with smooth muscle cells and is inelastic when compared to veins and arteries.

[0007] Figure 1 An exemplary venous sinus system with well-defined stent areas is shown. The venous sinus system comprises the venous channels found between the periosteal and meningeal layers of the dura mater of the brain. The venous sinus system receives blood from the internal and external veins of the brain, CSF from the subarachnoid space via the arachnoid granulations, and empties primarily into the internal jugular vein. Figure 1 As shown, the venous sinus system includes the transverse sinus, sigmoid sinus, and sigmoid node. The sigmoid sinus merges into the jugular vein at the sigmoid node. Figure 1 Also identified are exemplary stent areas for placement of stents to treat collapse and / or stenosis in the sigmoid and / or transverse sinuses.

[0008] Existing stent delivery systems and stents have several deficiencies for delivering stents to the venous sinuses. For example, existing stents and systems may be unable or difficult to navigate through the tortuous sigmoid node to place the stent in the stented area.

[0009] As another example, the properties of existing stents may be undesirable for placement in the sinuses. Typical carotid stents may be 4-6 cm long. However, after the carotid stent is placed in the sinus, a portion of the transverse sinus may collapse, particularly the portion distal to the stent's distal end. If the stent is placed at the junction of the sigmoid and transverse sinuses and is not long enough to support most or all of the transverse sinus, collapse of a portion of the transverse sinus may occur. Additionally, if collapse and / or stenosis are present at multiple locations in the sigmoid and / or transverse sinuses, multiple carotid stents may be required. Furthermore, a stent of inappropriate length may be incorrectly positioned in the bend in the sigmoid sinus, thereby blocking future access to the sinus (e.g., stent occlusion). For example, a stent that terminates within the bend rather than being positioned through the bend may block part or all of the sinus cavity at the bend.

[0010] Furthermore, existing stents typically have a set diameter. However, the middle and distal regions of the sigmoid sinus, on average, have a larger diameter (e.g., approximately 10-12 mm) than the distal portion of the transverse sinus (e.g., approximately 6-9 mm). Consequently, the diameter of existing stents positioned in both the sigmoid and transverse sinuses may be insufficient for at least one of the sinuses. For example, if a stent is too small for the vessel, a portion of the stent may remain dangling or floating freely within the vessel, potentially preventing proper growth of endothelial tissue on the stent struts. As another example, if a stent is too large for the vessel, various problems may arise because the radially outward expansion strength (RES) of a typical stent may be too strong for use in the venous sinuses. Specifically, stents intended for placement in large vessels (e.g., the carotid artery, femoral artery, or vein) may have a high RES required to treat occlusions, atherosclerotic plaques, and calcified lesions, and / or to withstand the external forces required to push the stent in. This high RES, combined with a stent size that is too large for the vessel, can lead to tissue death in contact with the stent struts due to the strong outward pressure exerted on the tissue. Another problem with high RES is that when the stent is too large for the vessel, the stent may push through the vessel wall and show up outside the vessel.

[0011] Existing stent designs can also have an abundance of struts. However, the venous sinus structure includes many small veins leading from the brain. Therefore, the number of struts in a typical stent increases the chance that one strut could block or partially inhibit venous inflow from the brain via the sinus.

[0012] Other limitations and disadvantages of conventional and traditional approaches will become apparent to those skilled in the art by comparing such a system with certain aspects of the present invention as set forth in the remainder of this application with reference to the accompanying figures. Summary of the Invention

[0013] Enhanced navigation of a stent delivery system for placing a stent is provided by increasing the flexibility of the stent delivery system and / or stent from the proximal end toward the distal end of the system and / or stent, substantially as shown and / or described in conjunction with at least one of the accompanying drawings, as more fully set forth in the specific embodiments.

[0014] These and other advantages, aspects and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 An exemplary sinus system with a defined stent area is shown in accordance with various embodiments.

[0016] Figure 2An exemplary stent is shown including a distal end and a proximal end, the distal end having greater flexibility than the proximal end, according to various embodiments.

[0017] Figure 3 Shown according to various embodiments Figure 2 An exemplary strut member of an exemplary stent.

[0018] Figure 4 Shown according to various embodiments Figure 2 1. An exemplary profile of an exemplary stent 100 having a smaller diameter at the distal end than at the proximal end.

[0019] Figure 5 Exemplary stent delivery systems are shown in accordance with various embodiments.

[0020] Figure 6 Shown according to various embodiments Figure 5 Detailed view of a portion of an exemplary stent delivery system.

[0021] Figure 7 Shown according to various embodiments Figure 5 A detailed view of the interior of the stent delivery system.

[0022] Figure 8 Shown according to various embodiments Figure 5 Detailed view of the exterior of the stent delivery system.

[0023] Figure 9 Exploded cross-sectional views of the interior of a stent delivery system, a stent, and the exterior of the stent delivery system are shown according to various embodiments, wherein the increasing flexibility of the stent delivery system as the stent is moved from the proximal end toward the distal end of the system and stent is illustrated by plotting onto an exemplary flexibility diagram.

[0024] Figure 10 is a flow chart illustrating exemplary steps that may be used to provide enhanced navigation of a stent delivery system for stent placement, according to various embodiments. DETAILED DESCRIPTION

[0025] Certain embodiments can provide enhanced navigation of a stent delivery system for stent placement by increasing the flexibility of the stent delivery system and / or the stent from a proximal end toward a distal end of the system and / or the stent. Various embodiments provide a self-expanding stent comprising a proximal end having a first radially outward expansion strength (RES) greater than a second radially outward expansion strength (RES) at a distal end of the stent. In a representative embodiment, the proximal end of the stent comprises a diameter greater than a diameter at the distal end of the stent. In certain embodiments, a stent delivery system can be configured to treat stenosis or collapse in a venous sinus by delivering a self-expanding stent.

[0026] The above summary and the following detailed description of certain embodiments will be better understood when read in conjunction with the accompanying drawings. It should be understood that the various embodiments are not limited to the arrangements and instrumentation shown in the drawings. It should also be understood that these embodiments may be combined, or other embodiments may be utilized, and that structural changes may be made without departing from the scope of the various embodiments. Therefore, the following detailed description should not be construed as limiting, and the scope of the present invention is defined by the appended claims and their equivalents.

[0027] As used herein, an element or step recited in the singular and preceded by the word "a" or "an" should be understood as not excluding a plurality of said elements or steps, unless such exclusion is expressly stated. Furthermore, reference to "one embodiment" is not intended to be interpreted as excluding the existence of additional embodiments that also include the described features. Furthermore, unless expressly stated to the contrary, an embodiment that "includes" or "has" one or more elements having a particular property may include additional elements that do not have that property. As referred to herein, the terms "proximal" and "distal" are relative to the delivery handle 210 of the stent delivery system 200 (also referred to as a catheter). For example, the distal ends 104, 204 of the stent 100 and catheter 200 are the ends that are first inserted into the patient's body cavity, and the proximal ends 102, 204 are opposite the distal ends 104, 204.

[0028] Figure 2 An exemplary stent 100 is shown including a distal end 104 and a proximal end 102 , the distal end 104 having greater flexibility than the proximal end 102 , in accordance with various embodiments. Figure 3 Shown according to various embodiments Figure 2 An exemplary strut member 112 of an exemplary stent 100 is shown. Figure 4 Shown according to various embodiments Figure 2 The exemplary profile of the exemplary stent 100 is shown in FIG. 1 , wherein the diameter of the distal end of the stent 100 is smaller than the diameter of the proximal end. Figure 2 and Figure 3 The bracket 100 may be shown in a plan view, but the top end of the bracket 100 will be connected to the bottom end to form the bracket 100 in a cylindrical form. Figures 2 to 4 , a self-expanding cylindrical stent 100 includes a distal end 104, a proximal end 102, and a plurality of circumferential strut segments 110. Strut segments 110 may include strut members 112 and longitudinal connecting members 118. Strut members 112 may be arranged in a pattern, such as a zigzag pattern having peaks 114 and valleys 116, or any other suitable pattern. Strut segments 110 may each be coupled to at least one other strut segment 110 via longitudinal connecting members 118.

[0029] Stents are typically implemented as open cell stents or closed cell stents. A closed cell stent has each peak and valley of each strut segment connected to the peaks or valleys of an adjacent strut segment, except for strut segments on the proximal and distal ends. On the other hand, an open cell stent has some peaks and / or valleys that are not connected to the peaks and / or valleys of adjacent strut segments. In a preferred embodiment, the stent 100 can be an open cell design, for example, to minimize the reduction in length of the stent 100 when the stent 100 is expanded from a pre-deployed state to a deployed state. In addition, the open cell stent structure has an enhanced ability to expand and conform to non-circular lumen walls (e.g., sinuses) compared to the closed cell structure. For example, the individual segments of the open cell stent are less dependent on adjacent segments than in a closed cell design. Therefore, the open cell segments are better suited to conform to the irregularities of non-circular lumens. Reference Figure 3 , the longitudinal connecting members 118 may be arranged in a periodic peak-to-valley connection scheme, for example, every three peaks are connected to every three valleys by longitudinal connecting members 118. Figure 3 A peak-to-valley connection scheme with three periods is shown in FIG, but other connection schemes and periods are contemplated. For example, the connection scheme may be a peak-to-peak connection scheme, a center-to-center connection scheme, a hybrid connection scheme, or any suitable connection scheme. As another example, the period may be two, four, a variable period, etc. Furthermore, the longitudinal connecting member 118 may be a flexible connection, an inflexible connection, a hybrid of flexible and inflexible connections, or any suitable connection.

[0030] The stent 100 can be sized to cover the sigmoid sinus and substantially the entire transverse sinus. For example, depending on the patient's size and height, the stent can be 6-9 cm long, with an average of approximately 7 cm. A properly sized stent maintains patency of both sinus structures while substantially eliminating the possibility of recollapse and substantially eliminating the possibility of stent occlusion.

[0031] The stent 100 can be made of nickel titanium (also known as nitinol) or any suitable material. In the case of a nitinol stent 100, the collapsed stent 100 can be inserted into a body lumen, where the body temperature warms the stent 100 and the stent 100 returns to its original expanded shape after the restraining sheath is removed, as described below with reference to Figures 5 to 10 Descriptive.

[0032] In various embodiments, the stent 100 can include segments 110 having strut members 112 of varying flexibility. Specifically, one or more segments 110 at the distal end 104 of the stent 100 can have greater flexibility than one or more segments 110 at the proximal end 102 of the stent 100. For example, Figure 2As shown, stent 100 can have a first group of flexible segments 120 and a second group of rigid segments 130. The first group of flexible segments 120 can include eight or any suitable number of segments 110, and the second group of rigid segments 130 can include fourteen or any suitable number of segments 110. Stent 100 can transition from the group of flexible segments 120 to the group of rigid segments 130 at a transition point 142 between the two groups 120, 130. Figure 3 Details are shown of the transition points 142 between the flexible segments 120 and the rigid segments 130. Additionally and / or alternatively, the stiffness of the segments 110 of the stent 100 can gradually increase from the distal end 104 to the proximal end 102 of the stent 100. For example, each segment 110 can have the same or greater flexibility as an adjacent segment 110 in the direction of the proximal end 102.

[0033] In one representative embodiment, the flexibility of the segments 110 can correspond to the radially outward expansion strength (RES) of the segments 110. For example, the group of flexible segments 120 can have a lower RES than the group of rigid segments 130. Thus, if the stent is placed in a venous sinus, the group of flexible segments 120 with a low RES at the distal end 104 of the stent 100 supports and holds open the transverse sinus region without applying excessive pressure to the dura mater lining. The group of rigid segments 130 at the proximal end of the stent 100 and having a greater RES than the flexible segments 120 are positioned in the sigmoid region, which can contain excessive arachnoid granulation ingrowth and / or stenosis, which may require greater force to open and restore better blood flow. The transition of the low RES distal end 104 of the stent 100 to the higher RES proximal end 102 can translate into a more flexible and integrated transition within the stent delivery system 200. Specifically, the integration of the stent 100 in the stent delivery system 200 provides for faster and easier delivery of the stent 100 by improving the ability to navigate the sigmoid node, for example, as described below with reference to FIG. Figure 9 Descriptive.

[0034] In various embodiments, the amount of RES and the flexibility of portions of the stent 100 can be configured based on the distance between the stent segments 110 and / or the length of the longitudinal connecting members 118, the number of longitudinal connecting members 118, the amount of strut members 112, and / or the width of the strut members 112 and / or the longitudinal connecting members 118. For example, a greater distance between the stent segments 110 and / or longer longitudinal connecting members 118 can correspond to a lower RES and greater flexibility. As another example, a greater number of longitudinal connecting members 118 can correspond to a higher RES and greater stiffness. Additionally, a greater number of strut members 112 can correspond to a higher RES and greater stiffness. Additionally, a narrower width of the strut members 112 and / or the longitudinal connecting members 118 can correspond to a lower RES and greater flexibility. For example, referring to Figure 3, the width of the strut members 112, strut member peaks 114, and longitudinal members 118 in the group of rigid segments 130 is referred to as W1. The width of the strut members 112, strut member peaks 114, and longitudinal members 118 in the group of flexible segments 120 is referred to as W2. The width W1 in the group of rigid segments 130 can be greater than the width W2 in the group of flexible segments 120. As an example, the width W1 of the strut members 112 and longitudinal members 118 in the group of rigid segments 130 can be approximately 0.0050 inches, and the width W1 of the strut member peaks 114 can be approximately 0.0065 inches. In the group of flexible segments 120, the width W2 of the strut members 112 and longitudinal connecting members 118 can be approximately 0.0045 inches, and the width W2 of the strut member peaks 114 can be approximately 0.0060 inches. In certain embodiments, an approximately 10% reduction in width W2 may correspond to an approximately 33% reduction in stiffness of the set of flexible segments 120 compared to the set of rigid portions 130 .

[0035] refer to Figure 4 , the stent 100 may be conical or stepped such that the lumen diameter D1 / D2 of the stent 100 is larger at the proximal end 102 than at the distal end 104. For example, Figure 4 The profile of a cylindrical stent 100 is shown, which is conical and has a larger lumen diameter D1 of the stent 100 at the proximal end 102 than the stent lumen diameter D2 at the distal end 104. Additionally and / or alternatively, the stent 100 may have a mix of straight and tapered portions. For example, the stent 100 may have straight portions at the distal end 104 and the proximal end 102, with a tapered portion between the straight portions. As another example, the stent 100 may have a straight portion at the distal end 104, followed by a tapered portion between the straight portion and the proximal end 102, or vice versa. The inclusion of the tapered portion ensures different lumen diameters D1 / D2 at the proximal end 102 and the distal end 104 of the stent 100. In a representative embodiment, the diameter D1 of the proximal end 102 of the stent 100 is larger than the diameter D2 at the distal end 104. For example, the diameter D1 at the proximal end 102 can be approximately 0.3937 inches, and the diameter D2 at the distal end 104 can be approximately 0.2756 inches. Thus, if the stent 100 is placed in a venous sinus, the smaller diameter D2 at the distal end 104 of the stent can be appropriately sized for the transverse sinus region, and the transition to the larger diameter D1 at the proximal end 102 of the stent 100 can be appropriately sized for the sigmoid sinus region. In this way, contact of the stent between the struts 112 and the dura mater wall in the transverse and sigmoid sinus regions can be maximized so that no portion of the stent 100 remains in the open blood flow of the lumen of the venous sinus.

[0036] Figure 5 An exemplary stent delivery system 200 is shown in accordance with various embodiments. Figure 6 Shown according to various embodiments Figure 5 Detailed views of portions 200A, 200B, 200C, 200D of an exemplary stent delivery system 200 are shown. Figure 7 Shown according to various embodiments Figure 5 Detailed view of the interior 200E of the stent delivery system 200 . Figure 8 Shown according to various embodiments Figure 5 Detailed view of the exterior 200F of the stent delivery system 200 . Figure 9 Exploded sectional views of an interior 200E of a stent delivery system 200, a stent 100, and an exterior 200F of the stent delivery system 200 are shown according to respective embodiments, wherein the flexibility of the stent delivery system 200 is shown to increase as the stent 100 moves from the proximal end 102, 202 toward the distal end 104, 204 of the system 200 as plotted onto an exemplary flexibility chart.

[0037] refer to Figures 5 to 9 , the stent delivery system 200 may include an outer portion 200F and an inner portion 200E extending between a proximal end 202 and a distal end 204 of the system 200 .

[0038] The interior 200E of the stent delivery system 200 can include a delivery handle 210 at a proximal end 202, a delivery tip 290 at a distal end 204, and a shaft 220 extending from the delivery handle into the delivery tip 290. The shaft 220 can include a proximal portion of the shaft 222 connected to the delivery handle 210, a central portion of the shaft 224, and a distal portion of the shaft 226 that includes and / or extends through a push coil 270 and a stent bed 280. In various embodiments, the shaft portions 222, 224, 226, 270, 280 can be tubular structures made of different materials and / or can have different outer diameters, for example, to increase flexibility along the longitudinal axis from the proximal end 202 to the distal end 204. For example, the proximal portion of the shaft 222 attached to the delivery handle and the central portion of the shaft 224 can be a hypotube or any suitable tube having a first diameter. The distal portion of the shaft 224 may have a second diameter that is smaller than the first diameter of the proximal portion 222 and the central portion 224 and / or may include portions, such as the helical portion 270 , that are made of a different material.

[0039] Stent bed 280 can be the portion of distal shaft 226 between push coil 270 and delivery tip 290. Stent bed 280 can be a thin-walled polyimide tube with constant stiffness. Stent bed 280 can extend through the lumen of pre-deployed stent 100, allowing the pre-deployed stent 100 to be positioned and supported on stent bed 280 until deployment. The pre-deployed stent 100 positioned on stent bed 280 can be maintained in the pre-deployed state by sheath 260, which can slide over stent 100 as described below. In various embodiments, the proximal and / or distal ends of stent bed 280 can include one or more markers, such as radiopaque markers, to enhance visualization of the position of the pre-deployed stent 100 within stent delivery system 200. For example, an operator of stent delivery system 200 can monitor navigation of system 200 via medical image data, such as fluoroscopic images, ultrasound images, or any other suitable medical imaging modality. The markers can be easily identified in the image data to assist the operator in accurately positioning stent delivery system 200 in the stented area.

[0040] The push coil 270 can be a portion of the distal shaft 226 at the proximal end of the stent bed 280. Additionally and / or alternatively, the push coil 270 can be concentrically disposed between the distal shaft 226 and the sheath 260. The push coil 270 can serve as a stop for the stent 100 positioned on the stent bed 280 by preventing the pre-deployed stent 100 from sliding from the stent bed 280 toward the proximal end 202. In various embodiments, the push coil 270 can have greater flexibility at the distal end of the push coil 270 than at the proximal end of the push coil 270. For example, the push coil 270 can have multiple sections, wherein each section has increasing flexibility from the proximal end of the push coil 270 to the distal end of the push coil 270 along the longitudinal axis.

[0041] Delivery tip 290 may include a distal end 294 and a proximal end 292. Delivery tip 290 may include an inner lumen configured to allow a guidewire 269 to pass through delivery tip 290, allowing the stent delivery system to slide over the guidewire 290 during navigation of the system to the stented area in a sinus or other body lumen. Delivery tip 290 may include an end transition 296 at the proximal end 292 of delivery tip 290. End transition 296 may have a larger outer diameter configured to prevent the outer sheath 260 of stent delivery system 200 from sliding distally over delivery tip 290. In a representative embodiment, delivery tip 290 may be made of a medical-grade polymer, such as a polyether block amide, e.g., PEBAX, and may have a durometer of approximately 35.

[0042] In various embodiments, the stent delivery system 200 can include a rapid exchange junction 268 that passes through the sheath 260 and into the distal shaft portion 226. A guidewire 269 extends within the guidewire lumen of the stent delivery system 200 from a lumen in the delivery tip 290 at the distal end 204 of the system 200 to a point where the guidewire lumen terminates outside the system 200 at the distal shaft portion 226 and the rapid exchange junction 268 at the distal sheath portion 266 proximate to the push coil 270. The rapid exchange junction 268 can facilitate rapid placement of the stent delivery system 200 over the guidewire 269 and allow for the use of a shorter guidewire than used in catheter-over-the-wire systems.

[0043] The outer portion 200F of the stent delivery system 200 may include sleeves 230, 240, 250 and a sheath 260. The sleeve may include a lock 230, a Tuohy-Borst valve 240, and a Luer wing 250. The lock 230 may be, for example, a standard Luer lock or any suitable lock for connecting the Tuohy-Borst valve 240 to the proximal portion 222 of the shaft 220. The lock 230 can be loosened to allow the sleeves 230, 240, 250 and the sheath 260 to slide on the shaft 220, and can be tightened to prevent such movement. The Tuohy-Borst valve (also known as a hemostasis valve) 240 may be attached to the lock 230 at the proximal end and may be coupled to the Luer wing 250 at the distal end. The Tuohy-Borst valve 240 may receive the shaft 220 inserted therein, and the shaft 220 may move within the valve 240 in a direction parallel to its longitudinal axis. Tuohy-Borst valve 240 can include a luer port 242 for securing valve 240 to other medical instruments and devices that can be used during a procedure to deliver stent 100 to the stented area within a patient's body. Luer wings 250 can be securely attached to sheath 260. Shaft 220 is configured to extend through lock 230, Tuohy-Borst valve 240, luer wings 250, and sheath 260.

[0044] The sheath 260 can include a proximal portion 262 terminating at the Luer wings 250, a distal portion 266 terminating at a terminal transition 296 at the proximal end 292 of the delivery tip 290, and a central portion 264 between the proximal portion 262 and the distal portion 266. In various embodiments, the sheath portions 262, 264, 266 can be tubular structures made of different materials and / or can have different outer diameters, for example, to increase flexibility along the longitudinal axis from the proximal end 202 to the distal end 204. The sheath 260 is configured to slide longitudinally over the shaft 220 and the stent 100 between a pre-deployment position and a deployed position. For example, in the pre-deployment position, the sheath 260 extends over the pre-deployed stent 100 to the terminal transition 296 of the delivery tip 290. After navigating the stent delivery system 200 to the stented area, the sheath 260 can be retracted over the stent 100 by releasing the lock 230 and pulling the sleeves 230, 240, 250 toward the delivery handle 210 at the proximal end 202 of the system 200. The stent 100 is deployed by expanding as the sheath 260 passes over it and releases the stent 100 from its pre-deployment, compressed state. In various embodiments, the sheath 260 can include one or more markers, such as radiopaque markers, to enhance visualization of the position of the pre-deployed stent 100 within the stent delivery system 200 in medical image data. In one representative embodiment, the distal portion 266 of the sheath 260 can be made of a medical-grade polymer, such as a polyether block amide, such as PEBAX. In one exemplary embodiment, the distal portion 266 of the sheath 260 can include a distal-most segment 266a having a flexible durometer of approximately 35, a mid-segment 266b having a semi-flexible durometer of approximately 55, and a proximal segment 266c having a rigid durometer of approximately 72. In this manner, the stiffness of the distal portion 266 of the sheath 260 may increase from the distal-most segment 266a to the proximal segment 266c.

[0045] refer to Figure 9 , shows a graph that plots the stiffness or flexibility 302 of the inner portion 200E of the stent delivery system 200, the stent 100, and the outer portion 200F of the stent delivery system 200, as combined. Figure 9 As shown, the stiffness 302 gradually increases and / or steps up from the distal end 204 of the stent delivery system 200 having the loaded stent 100 toward the proximal end 202 of the system 200. For example, the delivery tip may have a stiffness of approximately 35. Figure 9As shown, the delivery tip 290 portion of the stent delivery system 200 can have the most flexible stiffness 302. The next segment in the proximal direction from the delivery tip 290 is the stent bed 280 loaded with the stent 100 and a segment of the distal portion of the sheath 266. The distal portion 266 of the sheath 260 can have a distal-most segment 266a having a flexible stiffness of approximately 35. Thus, the combination of the distal portion 266 of the sheath with the stent bed 280 and the group of flexible segments 120 of the stent 100 can have a greater stiffness 302 than the delivery tip 290. Continuing in the proximal direction, the combined stiffness 302 of the distal-most segment 266a of the distal portion of the sheath 266, the group of rigid segments 130 of the stent 100, and the stent bed 280 increases due to the group of rigid segments 130 of the stent 100.

[0046] The middle section 266b of the distal portion 266 of the sheath can have a semi-flexible durometer of approximately 55, and the proximal section 266c can have a rigid durometer of approximately 72. The push coil 270 can have a flexible section 272 with loose windings and a rigid section 274 with tight windings. Thus, the stiffness 302 continues to increase for the combination of the flexible section 272 of the push coil 270 and the middle section 266b of the distal portion of the sheath 266. In the same manner, the stiffness 302 increases stepwise for the combination of the rigid section 274 of the coil and the middle section 266b of the distal portion of the sheath 266.

[0047] The distal shaft portion 226 in the proximal direction from the push coil 270 can have a greater stiffness than the coil. Thus, the stiffness 302 of the stent delivery system 200 with the loaded stent 100 can again be stepped up for the combined system components including the distal shaft portion 226 in the proximal direction from the push coil 270 and the proximal segment 266 c of the distal portion 266 of the sheath 260.

[0048] In summary, not only do the different materials and different hardnesses of the individual components affect the flexibility of the stent delivery system 200 with the loaded stent 100, but the combination of the components loaded with the stent 100 along the longitudinal axis of the system 200 provides a gradual increase in stiffness 302 from the distal end 204 toward the proximal end 202 of the system 200 in a new way, which improves the control and navigation of the system 200 for delivering the stent 100.

[0049] Figure 10 FIGURE 4 is a flow chart 400 illustrating exemplary steps 402 through 410 that may be used to provide enhanced navigation of a stent delivery system 200 for placement of a stent 100, according to various embodiments. Figure 10, a flowchart 400 including exemplary steps 402 to 410 is shown. Certain embodiments may omit one or more steps, and / or perform the steps in a different order than listed, and / or combine certain steps discussed below. For example, some steps may not be performed in certain embodiments. As another example, certain steps may be performed in a different chronological order than listed below, including simultaneously.

[0050] At step 402, the stent delivery system 200 can be inserted into a venous sinus or other body cavity. For example, the stent delivery system 200 can access the venous sinus at the sigmoid node via the jugular vein. The stent delivery system 200 can include a collapsed, pre-deployed stent 100 carried between a shaft 220 and / or stent bed 280 and a sheath 260 near the distal end 203 of the system 200. In various embodiments, the stent 100 can be made of nitinol. Inserting the stent delivery system 200 into the venous sinus or other body cavity provides body temperature that warms the nitinol stent 100, which allows the stent 100 to return to its original expanded shape after the sheath 260 of the system is removed at step 408.

[0051] In step 404, the stent delivery system 200 is navigated to position the stent 100 at a target site in the venous sinus or other body cavity. For example, the stent delivery system 200 can approach the venous sinus via the jugular vein, pass through the sigmoid node and sigmoid sinus, and enter the transverse sinus. The target site or stent area for placement of the stent 100 can essentially span from the distal end of the transverse sinus to the sigmoid sinus. Navigation of the stent delivery system 200 with the stent 100 includes passing through the curved sigmoid node. Therefore, in various embodiments, the stent 100 and the stent delivery system 200 can have increased flexibility from the proximal ends 102, 202 of the stent 100 and the catheter 200 to the distal ends 104, 204 of the stent 100 and the catheter 200. This gradual change in flexibility provides increased maneuverability at the distal ends 104, 204 while providing stiffness control of the system 200 toward the proximal end 102 of the system 200.

[0052] At step 406, the lock 230 of the stent delivery system 200 is released to allow the sheath 260 to move over the shaft 220 of the system 200. For example, the lock 230 may be unscrewed from the shaft 220 or otherwise loosened.

[0053] At step 408, catheter hubs 230, 240, 250 may be pulled toward delivery handle 210 to slide sheath 260 back over stent 100, thereby deploying stent 100. For example, the sheath may be attached to catheter hubs 230, 240, 250 at Luer wings 250 such that sheath 260 moves with hubs 230, 240, 250 as hubs 230, 240, 250 are pulled on shaft 220.

[0054] At step 410, the delivery tip 290 can be pulled through the lumen in the deployed stent 100 and the stent delivery system 200 can be removed from the sinus or other body lumen. For example, removal of the sheath 260 at step 408 can deploy the collapsed stent 100 to an expanded state that opens the stent lumen. Thus, when the stent delivery system 200 is pulled back through and out of the sinus or other body lumen to remove the stent delivery system 200 from the patient, the delivery tip 290 of the stent delivery system 200 can pass through the opened stent lumen.

[0055] Aspects of the present invention provide a stent delivery system 200. According to various embodiments, the stent delivery system 200 includes a delivery handle 210 at the proximal end 202 of the stent delivery system 200, catheter sleeves 230, 240, 250, a delivery tip 290 at the distal end 204 of the stent delivery system 200, a shaft 220, a stent 100, and a sheath 260. The delivery tip 290 includes a distal end 294 and a proximal end 292. The delivery tip 290 has a first flexibility. The shaft 220 extends from the delivery handle 210, through the catheter sleeves 230, 240, 250, and into the delivery tip 290. The shaft 220 includes a coil 270 and a stent bed 280. The coil 270 includes a coil distal end and a coil proximal end. The stent bed 280 is between the coil distal end and the proximal end 292. Stent 100 is loaded onto stent bed 280 and includes a stent distal end 104, a stent proximal end 102, and a cylindrical body between the stent distal end 104 and the stent proximal end 102. A first portion 120 of the cylindrical body at the stent distal end 104 is more flexible than a second portion 130 of the cylindrical body at the stent proximal end 130. A sheath 260 is coupled to catheter hubs 230, 240, and 250 and is movable over stent bed 280 between a pre-deployment position and a deployed position. In the pre-deployment position, sheath 260 extends over stent bed 280. In the deployed position, sheath 260 is retracted from stent bed 280. In the pre-deployment position, stent 100 is compressed by sheath 260 over stent bed 280. When sheath 260 is retracted from stent bed 280 in the deployed position, stent 100 expands. Sheath 260 includes a distal sheath end and a proximal sheath end. The sheath 260 includes a flexible segment 266a at the distal end of the sheath, a semi-flexible segment 266b adjacent to the flexible segment 266a, and a rigid segment 266c adjacent to the semi-flexible segment 266b. The combination of the stent bed 280, the first cylindrical portion 120 of the stent 100, and the flexible segment 266a of the sheath 260 has a second flexibility that is less than the first flexibility. The combination of the stent bed 280, the second cylindrical portion 130 of the stent 100, and the flexible segment 266a of the sheath 260 has a third flexibility that is less than the second flexibility.

[0056] In various embodiments, the coil 270 includes a loosely wound region 272 at the distal end of the coil that has greater flexibility than a tightly wound region 274 of the coil 270 at the proximal end of the coil. In certain embodiments, the combination of the loosely wound region 272 of the coil 270 and the semi-flexible segment 266b of the sheath 260 has a fourth flexibility that is less than the third flexibility. In a representative embodiment, the combination of the tightly wound region 274 of the coil 270 and the semi-flexible segment 266b of the sheath 260 has a fifth flexibility that is less than the fourth flexibility. In various embodiments, the combination of the tightly wound region 274 of the push coil 270 and the rigid segment 266c of the sheath 260 has a sixth flexibility that is less than the fifth flexibility. In certain embodiments, the combination of the shaft 220 adjacent to the coil 270 at the proximal end of the coil and the rigid segment 266c of the sheath 260 has a seventh flexibility that is less than the sixth flexibility.

[0057] In one exemplary embodiment, one or more of the delivery tip 290 and the sheath 260 are made of a medical-grade polymer, such as polyether block amide. In various embodiments, the stent bed 280 is a thin-walled tube having a constant stiffness. In certain embodiments, the delivery tip 290 has a durometer of approximately 35. In one exemplary embodiment, the one or more flexible segments 266a of the sheath 260 have a durometer of approximately 35, the semi-flexible segments 266b of the sheath 260 have a durometer of approximately 55, and the rigid segments 266c of the sheath 260 have a durometer of approximately 72.

[0058] Various embodiments provide a stent 100 comprising a distal end 104 having a first diameter D2, a proximal end 102 having a second diameter D1 that is larger than the first diameter D2, and a cylinder between the distal end 104 and the proximal end 102. The cylinder comprises circumferential strut segments 110 and longitudinal connecting members 118. Each circumferential strut segment 110 comprises strut members 112 arranged in a pattern. Each circumferential strut segment 110 is connected to at least one other circumferential strut segment 110 by a portion of the longitudinal connecting members 118. A first plurality of circumferential strut segments 120 at the distal end 104 of the stent 100 has greater flexibility than a second plurality of circumferential strut segments 130 at the proximal end 102 of the stent 100.

[0059] In some embodiments, the first plurality of circumferential strut segments 120 at the distal end 104 of the stent 100 have a lower radially outward expansion strength than the second plurality of circumferential strut segments 130 at the proximal end 102 of the stent 100. In a representative embodiment, at least a portion of the cylinder is conical. In various embodiments, the longitudinal connecting members 118 are arranged in an open cell design. In some embodiments, the cylinder is made of nickel titanium. In a representative embodiment, the length of the cylinder is 6 to 9 centimeters.

[0060] In various embodiments, the pattern of strut members 112 is a zigzag pattern having peaks 114 and valleys 116. In certain embodiments, the longitudinal connecting members 118 are arranged in a periodic peak-to-valley connection scheme. In a representative embodiment, a first width W2 of one or both of the strut members 112 and the longitudinal connecting members 118 of a first plurality of circumferential strut segments 120 at the distal end 104 of the stent 100 is less than a second width W1 of one or both of the strut members 112 and the longitudinal connecting members 118 of a second plurality of circumferential strut segments 130 at the proximal end 102 of the stent 100. In various embodiments, the first plurality of circumferential strut segments 120 at the distal end 104 of the stent 100 is 8 circumferential strut segments 110 and the second plurality of circumferential strut segments 130 at the proximal end 102 of the stent 100 is 14 circumferential strut segments 110.

[0061] As used in this article, "and / or" represents any one or more items connected by "and / or" in a list. As an example, "x and / or y" represents any element in a three-element group {(x), (y), (x, y)}. As another example, "x, y and / or z" represents any element in a seven-element group {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. As used in this article, the term "exemplary" represents a non-limiting example, example or illustration. As used in this article, the terms "for example" and "such as" list one or more non-limiting examples, examples or illustrations. As used in this article, a structure that is "configured" or "operable" to perform a function requires that the structure is not only capable of performing the function, but is actually caused to perform the function, regardless of whether the function is actually performed.

[0062] Although the present invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt specific situations or materials to the teachings of the present invention without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed, but rather is intended to encompass all embodiments falling within the scope of the appended claims.

Claims

1. A stent delivery system for delivering a self-expanding stent to a venous sinus, the stent delivery system comprising: a delivery handle at the proximal end of the stent delivery system; catheter sleeve; a delivery tip at a distal end of the stent delivery system, wherein the delivery tip comprises a distal end and a proximal end, and wherein the delivery tip has a first flexibility; a shaft extending from the delivery handle, through the catheter hub, and into the delivery tip, wherein the shaft includes a coil and a stent bed, the coil having a coil distal end and a coil proximal end, the stent bed being between the coil distal end and the tip proximal end; a stent loaded onto the stent bed, wherein the stent extends between a stent distal end and a stent proximal end, the stent including a lumen extending through the stent from the stent distal end to the stent proximal end in a deployed state, and wherein a first portion of the stent at the stent distal end has greater flexibility than a second portion of the stent at the stent proximal end; and a sheath coupled to the catheter hub and movable over the stent bed between a pre-deployment position and a deployed position, wherein the sheath extends over the stent bed if in the pre-deployment position, wherein the sheath is pulled back from the stent bed if in the deployed position, wherein the stent is compressed by the sheath over the stent bed if in the pre-deployment position, wherein the stent expands if the sheath is pulled back from the stent bed in the deployed position, wherein the sheath comprises a sheath distal end and a sheath proximal end, and wherein the sheath comprises a flexible segment at the sheath distal end having a first stiffness, a semi-flexible segment adjacent the flexible segment having a second stiffness greater than the first stiffness, and a rigid segment adjacent the semi-flexible segment having a third stiffness greater than the second stiffness, wherein the combination of the stent bed, the first portion of the stent, and the flexible section of the sheath has a second flexibility that is less than the first flexibility, and wherein the combination of the stent bed, the second portion of the stent, and the flexible section of the sheath has a third flexibility that is less than the second flexibility; wherein the stent is configured to be positioned at a target site in the venous sinus, the target site spanning from a distal end of the transverse sinus into the sigmoid sinus; wherein the stent is deployed at the target site by pulling the sheath backward over the stent; and wherein the stent delivery system is removed from the venous sinus by pulling the delivery tip through the lumen in the stent and out of the venous sinus.

2. The stent delivery system according to claim 1, wherein: The stent delivery system is administered via the jugular vein to access the venous sinus at the sigmoid node.

3. The stent delivery system according to claim 1, wherein: The stent delivery system is configured to be navigated through the sigmoid node.

4. The stent delivery system according to claim 1, further comprising: A lock is provided for releasing the stent delivery system to allow movement of the sheath.

5. The stent delivery system according to claim 1, wherein: By pulling the catheter hub toward the delivery handle, the sheath is slid back over the stent to deploy the stent at the target site.

6. The stent delivery system according to claim 1, wherein: The coil includes a loosely wound region at a distal end of the coil having greater flexibility than a tightly wound region of the coil at a proximal end of the coil.

7. The stent delivery system according to claim 6, wherein: The combination of the loosely wound region of the coil and the semi-flexible section of the sheath has a fourth flexibility that is less than the third flexibility.

8. The stent delivery system according to claim 7, wherein: The combination of the tightly wound region of the coil and the semi-flexible section of the sheath has a fifth flexibility that is less than the fourth flexibility.

9. The stent delivery system according to claim 8, wherein: The combination of the tightly wound region of the coil and the rigid section of the sheath has a sixth flexibility that is less than the fifth flexibility.

10. The stent delivery system according to claim 9, wherein: The shaft is adjacent to the coil and in combination with the rigid section of the sheath at the proximal end of the coil has a seventh flexibility that is less than the sixth flexibility.

11. The stent delivery system according to claim 1 , wherein: The distal end of the stent has a first diameter; The proximal end of the stent has a second diameter that is larger than the first diameter; and The stent includes circumferential strut segments and longitudinal connecting members, each circumferential strut segment including strut members arranged in a pattern, and each circumferential strut segment is connected to at least one other circumferential strut segment via a portion of the longitudinal connecting members, wherein a first plurality of circumferential strut segments at the distal end of the stent have greater flexibility than a second plurality of circumferential strut segments at the proximal end of the stent.

12. The stent delivery system according to claim 11, wherein: The first plurality of circumferential strut segments at the distal end of the stent have a lower radially outward expansion strength than the second plurality of circumferential strut segments at the proximal end of the stent.

13. The stent delivery system according to claim 11, wherein: At least a portion of the stent is conical.

14. The stent delivery system according to claim 11, wherein: The longitudinal connecting members are arranged in an open cell design.

15. The stent delivery system according to claim 11, wherein: The stent is made of nickel titanium.

16. The stent delivery system according to claim 11, wherein: The length of the stent is 6 to 9 cm.

17. The stent delivery system according to claim 11, wherein: The pattern of the strut members is a zigzag pattern having peaks and valleys; and / or wherein the longitudinal connecting members are arranged in a periodic peak-to-valley connection scheme.

18. The stent delivery system according to claim 11, wherein: A first width of one or both of the strut members and the longitudinal connecting members of the first plurality of circumferential strut segments at the distal end of the stent is less than a second width of one or both of the strut members and the longitudinal connecting members of the second plurality of circumferential strut segments at the proximal end of the stent.

19. The stent delivery system according to claim 11, wherein: The first plurality of circumferential strut segments at the distal end of the stent is 8 circumferential strut segments and the second plurality of circumferential strut segments at the proximal end of the stent is 14 circumferential strut segments.

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