Stent pusher devices, systems, and methods

Abstract

Disclosed herein are devices, systems, and methods for delivering a stent to a treatment site within a blood vessel. According to some embodiments, a stent pusher includes a proximal core wire, a distal core wire, and a pusher ring between the proximal core wire and the distal core wire. The distal core wire is configured to transition between a first configuration in which the distal core wire forms a substantially straight first structure and a second configuration in which the distal core wire forms a coiled second structure having a larger diameter and a smaller length than the first structure.

Description

Technical Field

[0001] The present technology relates to devices, systems, and methods for delivering a stent to a treatment site within a patient's blood vessel. Background Art

[0002] The walls of the vasculature, particularly arterial walls, can develop pathological dilated regions called aneurysms, which often have weak walls prone to rupture. Aneurysms are typically caused by weakening of the blood vessel wall due to disease, injury, or congenital anomalies. Aneurysms occur in different parts of the body and are most commonly abdominal aortic aneurysms and cerebral (e.g., brain) aneurysms in the neurovascular system. When the weakened wall of an aneurysm ruptures, especially in the case of a ruptured cerebral aneurysm, it results in death.

[0003] Aneurysms are typically treated by excluding or at least partially isolating the weakened portion of the blood vessel from the arterial circulation. For example, conventional aneurysm treatments include: (i) surgical clipping, where a metal clip is fixed around the base of the aneurysm; (ii) filling the aneurysm with small flexible coils (microcoils); (iii) using embolization materials to "fill" the aneurysm; (iv) using detachable balloons or coils to occlude the parent vessel supplying the aneurysm; and (v) endovascular stenting.

[0004] It is well known that endovascular stents are used in the medical field to treat vascular stenosis or aneurysms. A stent is a prosthesis that radially expands or otherwise expands within a blood vessel or lumen to support the blood vessel from collapsing. Methods for delivering these endovascular stents are also well known.

[0005] Conventional methods for introducing a compressed stent into a blood vessel and positioning it within a stenotic or aneurysmal region include advancing the distal portion of a guiding catheter percutaneously through the patient's vascular system until the distal portion is close to the stenosis or aneurysm. A second inner catheter is advanced through the distal region of the guiding catheter and positioned distal to the lesion. Then, a stent delivery system is advanced into the distal region of the inner catheter, and the distal portion of the compressed stent carried by the delivery system is positioned near the desired point of the lesion within the blood vessel. Then, the compressed stent is released and expanded such that it supports the blood vessel at the point of the lesion. Summary of the Invention

[0006] The present subject technology, for example, according to various aspects described below, includes reference Figures 1A to 8 for illustration. For convenience, various examples of aspects of the present subject technology are described as numbered clauses (clause 1, 2, 3, etc.). These are provided as examples and do not limit the present subject technology.

[0007] 1. A stent pusher assembly, comprising:

[0008] Stent pusher, the stent pusher comprising:

[0009] A proximal core wire, the proximal core wire including a proximal end and a distal end opposite the proximal end along a longitudinal dimension of the proximal core wire;

[0010] A distal core wire, the distal core wire including a proximal end at the distal end of the proximal core wire and a distal end opposite the proximal end of the distal core wire along a longitudinal dimension of the distal core wire;

[0011] A pusher ring carried by the distal core wire, the pusher ring being configured to contact a proximal end portion of a stent to apply a distally directed force to the proximal end portion of the stent to prevent or limit proximal movement of the stent relative to the stent pusher,

[0012] wherein the distal core wire is configured to transition between a first configuration in which the distal core wire forms a first structure and a second configuration in which the distal core wire forms a second structure,

[0013] wherein in the first configuration, the first structure formed by the distal core wire is substantially straight without coils, and the first structure defines a first length and a first diameter, and

[0014] wherein in the second configuration, the second structure formed by the distal core wire includes a coil portion defining a plurality of coils, and the second structure defines a second length less than the first length and a second diameter greater than the first diameter.

[0015] 2. The stent pusher assembly according to clause 1, further comprising:

[0016] A stent, the stent including a tubular structure, the tubular structure including a proximal end portion and a distal end portion opposite the proximal end portion along a longitudinal dimension of the stent, the stent being configured to be positioned above the distal core wire, wherein the proximal end portion of the stent is distal to the pusher ring, wherein the stent is configured to transition between a compressed stent configuration and an expanded stent configuration, wherein in the compressed stent configuration, the stent defines a first stent length and a first stent diameter, and wherein in the expanded stent configuration, the stent defines a second stent length less than the first stent length and a second stent diameter greater than the first stent diameter; and

[0017] A catheter defining a lumen, wherein the lumen defines a lumen inner diameter less than the second diameter of the distal core wire and the second stent diameter,

[0018] wherein the stent is configured to be positioned within the lumen of the catheter in the compressed stent configuration, wherein the distal core wire is in the first configuration and is positioned within the stent, and

[0019] wherein the pusher ring is configured to engage the stent to translate the stent out of the lumen of the catheter such that the stent can transition from the compressed stent configuration to the expanded stent configuration and such that the distal core wire can transition from the first configuration to the second configuration.

[0020] 3. The stent pusher assembly according to any one of the preceding clauses, wherein the distal core wire is configured to be pushed out of the lumen of the catheter into a blood vessel in the first configuration and is configured to transition from the first configuration to the second configuration when located outside the lumen of the catheter.

[0021] 4. The stent pusher assembly according to any one of the preceding clauses, wherein the distal core wire comprises a shape memory alloy and has an austenite finish (Af) temperature of about 36 °C such that the distal core wire transitions from the first configuration to the second configuration in response to the temperature of the distal core wire rising above the Af temperature when positioned in a blood vessel.

[0022] 5. The stent pusher assembly according to any one of the preceding clauses, wherein the distal core wire comprises a distal straight portion extending from the coil portion to the distal end of the distal core wire, wherein the distal straight portion maintains a length and a diameter in the first configuration and the second configuration.

[0023] 6. The stent pusher assembly according to any one of the preceding clauses, wherein the transition of the distal core wire from the first configuration to the second configuration reduces the length of the distal core wire by at least 30%.

[0024] 7. The stent pusher assembly according to any one of the preceding clauses, wherein in the case where the distal core wire is in the second configuration, the length of the coil portion is equal to the second stent length.

[0025] 8. The stent pusher assembly according to any one of the preceding clauses, wherein the second diameter is configured to allow the stent pusher to engage the stent in the expanded stent configuration to translate the stent within a blood vessel.

[0026] 9. The stent pusher assembly according to any one of the preceding clauses, wherein the second diameter is configured to allow the distal core wire to engage the stent in the expanded stent configuration to juxtapose the stent into a blood vessel wall.

[0027] 10. The stent pusher assembly according to any one of the preceding clauses, wherein the shortening rate of the distal core wire is equal to the shortening rate of the stent.

[0028] 11. The stent pusher assembly according to any one of the preceding clauses, wherein the second diameter is at least three times the first diameter.

[0029] 12. The stent pusher assembly according to any one of the preceding clauses, further comprising a re-sheathing ring carried by the distal core wire distal to the pusher ring, the re-sheathing ring being configured to engage the stent when the stent is positioned within the lumen of the catheter such that the re-sheathing ring is configured to apply a proximally directed force to the stent in response to proximal retraction of the proximal core wire.

[0030] 13. The stent pusher assembly according to any one of the preceding clauses, wherein the stent comprises a plurality of braided filaments.

[0031] 14. The stent pusher assembly according to any one of the preceding clauses, wherein the pusher ring comprises a proximally facing surface facing the proximal core wire, a distally facing surface facing the distal core wire, and a tubular sidewall extending therebetween, the pusher ring defining a radial dimension greater than the first diameter of the distal core wire and less than the second diameter, wherein the distally facing surface of the pusher ring is configured to contact the proximal end portion of the stent.

[0032] 15. The stent pusher assembly according to any one of the preceding clauses, wherein the distal core wire comprises nitinol.

[0033] 16. The stent pusher assembly according to any one of the preceding clauses, wherein the proximal core wire comprises stainless steel.

[0034] 17. The stent pusher assembly according to any one of the preceding clauses, wherein the proximal core wire comprises nitinol.

[0035] 18. The stent pusher assembly according to any one of the preceding clauses, wherein the proximal core wire is harder than the distal core wire.

[0036] 19. A stent pusher, comprising:

[0037] A distal core wire configured to receive a tubular medical device thereon; and

[0038] A pusher member carried by the distal core wire, the pusher member being configured to contact the proximal end portion of the tubular medical device,

[0039] The distal core wire is configured to transition between a small-profile configuration and a deployed configuration. In the small-profile configuration, the distal core wire forms a first structure that is substantially straight and has a first length. In the deployed configuration, the distal core wire forms a second structure that defines a plurality of coils and has a second length that is less than the first length.

[0040] 20. The stent pusher according to any one of the preceding clauses, wherein when the distal core wire is in the small-profile configuration, the first structure has a first radial dimension, and when the distal core wire is in the deployed configuration, the second structure has a second radial dimension, and the second radial dimension is greater than the first radial dimension.

[0041] 21. The stent pusher according to any one of the preceding clauses, wherein the shortening rate of the distal core wire when transitioning from the small-profile configuration to the deployed configuration corresponds to the shortening rate of the tubular medical device.

[0042] 22. The stent pusher according to any one of the preceding clauses, wherein the distal core wire is configured to transition between the small-profile configuration and the deployed configuration in response to the temperature of the distal core wire rising above the Af temperature of the distal core wire.

[0043] 23. The stent pusher according to any one of the preceding clauses, further comprising a proximal core wire extending proximally from the pusher member.

[0044] 24. The stent pusher according to any one of the preceding clauses, wherein the proximal core wire is stiffer than the distal core wire.

[0045] 25. The stent pusher according to any one of the preceding clauses, wherein the pusher member includes a distally facing surface, a proximally facing surface, and sidewalls extending therebetween, and the distally facing surface is configured to engage the proximal end portion of the tubular medical device.

[0046] 26. The stent pusher according to any one of the preceding clauses, further comprising a re-sheathing ring carried by the distal core wire distal to the pusher member, the re-sheathing ring being configured to apply a proximally directed force to the tubular medical device in response to the re-sheathing ring retracting proximally.

[0047] 27. A method of delivering a stent to a treatment site within the lumen of a patient's blood vessel using a stent pusher assembly, the stent pusher assembly including a catheter, a stent pusher positioned within the lumen of the catheter and including a proximal core wire, a distal core wire, and a pusher ring carried by the distal core wire, and a stent positioned within the lumen of the catheter above the distal core wire and distal to the pusher ring, the method comprising:

[0048] Positioning a distal end portion of the catheter within the blood vessel lumen at or near the treatment site;

[0049] Engaging the stent with the pusher ring to translate the stent and the distal core wire out of the lumen of the catheter, to allow the stent to transition from a compressed stent configuration to a deployed stent configuration, and to allow the distal core wire to transition from a first configuration to a second configuration, in the first configuration, the distal core wire forms a first structure that is substantially straight without coils and defines a first length and a first diameter, in the second configuration, the distal core wire forms a second structure that includes a coil portion defining a plurality of coils such that the second structure defines a second length less than the first length and a second diameter greater than the first diameter.

[0050] 28. The method according to any one of the preceding clauses, further comprising engaging the luminal surface of the stent with the distal core wire to move the stent closer to the wall of the blood vessel.

[0051] 29. The method according to any one of the preceding clauses, wherein engaging the luminal surface of the stent with the distal core wire includes pushing and / or pulling a proximal end of the proximal core wire.

[0052] 30. The method according to any one of the preceding clauses, wherein translating the stent out of the lumen of the catheter such that the stent transitions from a compressed stent configuration to a deployed stent configuration causes the stent to transition from a first stent length to a second stent length less than the first stent length, and wherein the shortening rate of the stent is equal to the shortening rate of the distal core wire.

[0053] 31. The method according to any one of the preceding clauses, wherein the distal core wire is configured to transition from the first configuration to the second configuration in response to the temperature of the distal core wire rising above about 36°C.

[0054] 32. The method according to any one of the preceding clauses, wherein when the stent and the distal core wire are translated out of the lumen of the catheter, the position of the distal end of the distal core wire within the blood vessel lumen remains substantially constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale. Instead, emphasis is placed on clearly illustrating the principles of the present disclosure.

[0056] Figure 1A and Figure 1B show an example of incomplete stent juxtaposition.

[0057] Figure 2A and Figure 2B show a straight stent pusher. Figure 2A shows a stent pusher and a stent positioned within the lumen of a catheter, and Figure 2B shows a stent pusher and a stent positioned outside the lumen of the catheter.

[0058] Figure 3 shows a stent pusher according to the present technology.

[0059] Figure 4A depicts the distal core wire of the Figure 3 stent pusher in a first configuration.

[0060] Figure 4B depicts the distal core wire of the Figure 3 stent pusher in a second configuration.

[0061] Figure 5 depicts the Figure 3 engagement portion of the stent pusher.

[0062] Figure 6A depicts an intravascular stent pusher assembly according to the present technology, the stent pusher assembly including the Figure 3 stent pusher, stent, and catheter.

[0063] Figure 6B depicts the Figure 6A stent pusher assembly according to the present technology, wherein the stent and the stent pusher are positioned outside the lumen of the catheter while within a blood vessel.

[0064] Figure 7 and Figure 8 show methods of juxtaposing a stent against a vessel wall using a stent pusher assembly according to the present technology and using a straight stent pusher, respectively. Detailed Description

[0065] The present technology relates to devices, systems, and methods for delivering a stent to a treatment site within a blood vessel. For example, some embodiments of the present technology relate to a stent pusher assembly including a catheter, a stent, and a stent pusher. According to various embodiments, the stent pusher includes a proximal core wire, a distal core wire configured to be located beneath the stent, and a pusher loop carried by at least one of the proximal core wire or the distal core wire and configured to engage the proximal end of the stent. The stent pusher and the stent are configured to be slidably received within the lumen of the catheter, wherein the stent is in a compressed stent configuration and the distal core wire is in a first configuration in which the distal core wire is substantially straight. The distal core wire is configured to transition from the first configuration to a second configuration in which the distal core wire includes a coiled portion defining a plurality of coils. For example, the distal core wire can be configured to transition to the second configuration upon release from the catheter lumen and / or in response to the temperature of the distal core wire rising above a transition temperature of the distal core wire. The transition of the distal core wire to the second configuration and / or the second configuration of the distal core wire can be configured to facilitate delivery of the stent to the treatment site.

[0066] When delivering a stent to a treatment site within a blood vessel, the stent should fully engage the blood vessel wall. However, as Figure 1A and Figure 1B shown, in some cases, incomplete stent apposition (ISA) occurs and one or more portions of the stent do not contact the blood vessel wall. ISA can include: outer curve ISA (see Figure 1A ), in which one or more portions of the stent fail to contact the outer curve of the blood vessel; and / or inner curve ISA (see Figure 1B ), in which one or more portions of the stent do not contact the inner curve of the blood vessel. ISA is more likely to occur when deploying a braided stent and / or when deploying a stent in a tortuous vasculature. For example, a braided stent undergoes significant deformation during delivery and deployment and may require substantial manipulation by a clinician to fully open and engage the blood vessel wall. ISA is associated with thromboembolic complications such as thrombosis or in-stent stenosis, incomplete occlusion of a saccular aneurysm treated with a bridging stent, and worse clinical outcomes for the patient.

[0067] Another challenge when delivering a stent to a treatment site within a tortuous vasculature is damage to the blood vessel wall. Many existing stent pushers (such as Figure 2A and Figure 2BThe shown linear stent pusher (200) includes a straight distal core wire (202). When the stent (204) is compressed over the distal core wire (202) within the lumen of the catheter (206), the stent (204) assumes a compressed stent configuration in which the stent (204) has a greater length than when the stent (204) is in an expanded stent configuration. For example, a braided stent typically shortens at a shortening ratio of at least 30% when deployed to an expanded stent configuration such that the length of the compressed stent is greater than the length of the expanded stent. As a result, the length of the distal core wire (202) is longer than the length of the expanded stent to accommodate the greater length of the stent (204) in the compressed stent configuration. To translate the stent (204) distally out of the lumen of the catheter (206) and deploy the stent (204) at the treatment site, the stent pusher (200) can be advanced distally relative to the catheter (206). However, because the distal core wire (202) is long enough to accommodate the compressed length of the stent (204), the distal core wire (202) can extend distally a significant distance corresponding to the shortening ratio to release the entire stent (204) from the lumen of the catheter (206). As Figure 2B shown, this extension of the stent pusher (200) can cause the distal end (202b) of the distal core wire (202) to contact the vessel wall, which can damage the vessel and result in bleeding, thrombosis, and other serious complications.

[0068] To address the foregoing stent delivery challenges, the stent pusher of the present technology may include a distal core wire configured to transition between a first configuration and a second configuration, in which the distal core wire has a greater diameter and a smaller length than in the first configuration. For example, the distal core wire may be configured to transition between a first configuration, in which the distal core wire is substantially straight, and a second configuration, in which the distal core wire defines a plurality of coils such that the distal core wire has a shorter length and radially expands to define a greater diameter defined by the outer diameter of the coils in the second configuration. The distal core wire may assume the first configuration when positioned within the catheter lumen and may assume the second configuration when positioned outside the catheter lumen and unconstrained by the catheter lumen. The transition of the distal core wire from the first configuration to the second configuration may facilitate the deployment (e.g., radial expansion) of the stent disposed over the distal core wire at the treatment site within the blood vessel. For example, because the distal core wire has a greater diameter in the second configuration, the distal core wire may be configured to more easily engage the luminal surface of the stent than a straight distal core wire, which may facilitate the expansion of the stent and / or the juxtaposition of the stent against the vessel wall. The clinician may iteratively push and pull the stent pusher to massage the stent and juxtapose the stent against the vessel wall. This manipulation causes the stent pusher to engage the inner surface of the stent, which may apply a radially outward force to the stent to facilitate the opening and juxtaposition of the stent. Because the distal core wire in the second configuration has a greater diameter, the distal core wire need not travel as far (if at all) to contact the inner surface of the stent and may easily apply a radially outward force to the stent. In contrast, during such a massage adjustment procedure, a straight distal core wire must travel further to engage the inner surface of the stent, thereby requiring more manipulation and increasing the difficulty of the procedure. Additionally, when the distal core wire transitions from the first configuration to the second configuration, the length of the distal core wire may decrease in conjunction with the shortening of the stent, which may limit the distal travel of the distal core wire during stent delivery to prevent accidental contact and damage to the vessel wall. Specifically, the overlying catheter may be retracted relative to the stent and the stent pusher such that the radial constraint is removed from the stent and the stent pusher, and each of the stent and the stent pusher is allowed to radially expand. This radial expansion causes the stent and the stent pusher to shorten.

[0069] Figure 3Illustrates a stent pusher 300 in accordance with several embodiments of the present technology. The stent pusher 300 includes: a proximal core wire 302 having a proximal end 302a and a distal end 302b opposite the proximal end 302a along the longitudinal dimension of the proximal core wire 302; and a distal core wire 304 having a proximal end 304a and a distal end 304b opposite the proximal end 304a along the longitudinal dimension of the distal core wire 304. The distal end 302b of the proximal core wire 302 and the proximal end 304a of the distal core wire 304 meet at a junction portion 305 of the stent pusher 300, which is configured to engage an overlying stent. As described below, the junction portion 305 includes the distal end 302b of the proximal core wire 302, the proximal end 304a of the distal core wire 304, a pusher ring 306, and / or a re-sheathing ring 308. The junction portion 305 is configured to engage the overlying stent via the pusher ring 306 and / or the re-sheathing ring 308. Specifically, the pusher ring 306 includes a distally facing surface that is positioned exactly proximal to the proximal end portion of the stent such that distal advancement of the proximal core wire 302 causes the distally facing surface of the pusher ring 306 to contact the proximal end portion of the stent. The re-sheathing ring 308 is configured to contact the inner surface of the stent and / or the thickness of the stent via a hole when the stent is compressed onto the re-sheathing ring 308. The proximal core wire 302 may be configured to be manipulated by a user to support movement of the stent pusher 300 within the lumen of a catheter. As described in more detail herein, the distal core wire 304 may be configured to be positioned beneath a stent within the lumen of a catheter in a first configuration during delivery of the stent and may be configured to transition to a second radially expanded and longitudinally shortened configuration. This transition of the distal core wire 304 may facilitate expansion of the stent and / or prevent or limit forward travel of the distal end 304b of the distal core wire 304 during delivery of the stent.

[0070] The stent pusher 300 may be configured to engage a stent that overlies the stent pusher 300 at the junction portion 305, which may include the distal end 302b of the proximal core wire 302, the proximal end 304a of the distal core wire 304, the pusher ring 306, and / or the re-sheathing ring 308. As previously described and as referenced Figure 5More particularly, the pusher ring 306 may have a distally facing surface that is positioned proximally of the proximal end portion of the stent such that distal advancement of the proximal core wire 302 causes the distally facing surface of the pusher ring 306 to engage the proximal end portion of the stent to facilitate distal movement of the stent relative to the overlying catheter and may be positioned at or near the proximal end 304a of the distal core wire 304. In some embodiments, the pusher ring 306 is positioned between the proximal core wire 302 and the distal core wire 304, the pusher ring 306 is carried by the distal core wire 304, and / or the pusher ring 306 is carried by the proximal core wire 302. The re-sheathing ring 308 may be configured to engage the stent when positioned within the catheter lumen and apply a proximally directed force to the stent to cause proximal movement of the stent relative to the overlying catheter. The re-sheathing ring 308 may be carried by the distal core wire 304 and may be positioned distally of the pusher ring 306. In some embodiments, the sheath 310 is positioned along and / or around at least a portion of the proximal core wire 302, which may enhance the deliverability of the stent pusher 300 by preventing or limiting buckling and / or kinking of the proximal core wire 302 without adding significant stiffness to the stent pusher 300. It may be advantageous for the pusher ring 306 and the re-sheathing ring 308 to be carried by the distal core wire 304 and positioned distally of the junction between the proximal core wire 302 and the distal core wire 304 such that the junction may be positioned within the sheath 310. The sheath 310 may protect the junction from degradation during use of the stent pusher 300. Additionally, positioning the junction within the sheath 310 allows solder and / or other adhesives to be positioned over the junction and / or fill the lumen of the sheath 310, which may allow for the formation of a higher strength junction.

[0071] Figure 3 The distal core wire 304 is shown in a second configuration in which the distal core wire 304 is radially expanded and longitudinally shortened relative to the first configuration. As previously described, the distal core wire 304 in the first configuration is substantially straight and has a greater length and a smaller diameter relative to the second configuration. Figure 4A and Figure 4B The distal core wire 304 is shown in the first configuration and the second configuration, respectively. In the first configuration and the second configuration, the distal core wire 304 may form a first structure and a second structure, respectively.

[0072] As Figure 4AAs shown, in the first configuration, the first structure formed by the distal core wire 304 can be straight, such that the first structure formed by the distal core wire 304 has no curves, bends, angles, or coils. In such examples, the diameter of the first structure can be equivalent to the diameter of the distal core wire 304 itself. According to various embodiments, the diameter of the distal core wire 304 itself is from about 0.06 millimeters to about 0.11 millimeters, from about 0.07 millimeters to about 0.10 millimeters, from about 0.08 millimeters to about 0.09 millimeters, about 0.06 millimeters, about 0.07 millimeters, about 0.08 millimeters, about 0.09 millimeters, about 0.10 millimeters, or about 0.11 millimeters. In some cases, the first structure formed by the distal core wire 304 in the first configuration can be substantially straight, such that the first structure only has small curves, bends, angles, or coils. For example, even if the first structure has a diameter slightly larger than the diameter of the distal core wire 304 itself, the first structure can be substantially straight as long as the diameter of the first structure is less than the diameter of the second structure formed by the distal core wire 304 in the second configuration.

[0073] The distal core wire 304 itself can have a length measured from the proximal end 304a of the distal core wire 304, the pusher ring 306, and / or the re-sheathing ring 308 to the distal end 304b of the distal core wire 304. The length of the distal core wire 304 itself does not change whether the distal core wire 304 is in the first configuration or the second configuration. In contrast, the first structure formed by the distal core wire 304 can have a first length L1, and the second structure formed by the distal core wire 304 can have a second length L2, and each of the first length and the second length can be different from the length of the distal core wire 304 itself.

[0074] The first structure formed by the distal core wire 304 in the first configuration may have a first length L1 and a first diameter D1. The first length L1 may be measured from the proximal end 304a of the distal core wire 304, the pusher ring 306, and / or the re-sheathing ring 308 to the distal end 304b of the distal core wire 304. The first length L1 may be based on and optionally at least equal to the length of the compressed stent that the stent pusher 300 is configured to be used with. The first diameter D1 may include the maximum diameter of the first structure formed by the distal core wire 304. For example, if the first structure formed by the distal core wire 304 is straight and has no curves, bends, angles, or coils, the first diameter D1 may be equal to the diameter of the distal core wire 304 itself. However, if the first structure formed by the distal core wire 304 is slightly bent, curved, angled, or coiled, the first diameter D1 is greater than the diameter of the distal core wire 304 itself. The first diameter D1 may be based on and / or substantially correspond to the inner diameter of the compressed stent that the stent pusher 300 is configured to be used with and / or the inner diameter of the catheter that the stent pusher 300 is configured to be used with. In some embodiments, for example when the first diameter D1 is based on the inner diameter in the compressed state, the first diameter D1 is less than the inner diameter of the compressed stent that the stent pusher 300 is configured to be used with, such that when positioned within the catheter lumen, the distal core wire 304 has little engagement with the stent, which may reduce the force required to advance the stent pusher 300 distally within the catheter lumen. In embodiments where the first diameter D1 substantially corresponds to the inner diameter of the compressed stent, for example, if the distal core wire 304 attempts to expand while still positioned within the catheter lumen and the compressed stent, the first diameter D1 may be approximately equal to the inner diameter of the compressed stent. The first diameter D1 of the first structure formed by the distal core wire 304 in the first configuration may be between about 0.2 mm and about 0.6 mm, between about 0.3 mm and about 0.5 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, or about 0.6 mm. The ratio of the first diameter D1 to the diameter of the distal core wire 304 itself may be between about 1 and about 10, between about 2 and about 9, between about 3 and about 8, between about 4 and about 7, between about 5 and about 6, about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, or about 10.

[0075] When the distal core wire 304 is in the second configuration, the distal core wire 304 forms a second structure having a second length L2 that is less than the first length L1 and a second diameter D2 that is greater than the first diameter D1. The second length L2 is defined between the same two points as L1 and can similarly be measured as the linear distance from the proximal end 304a of the distal core wire 304, the pusher ring 306, and / or the re-sheathing ring 308 to the distal end 304b of the distal core wire 304. In some embodiments, the second length L2 is substantially the same as the length of a stent in an expanded stent configuration that is configured to be used with the stent pusher 300. The second diameter D2 can include the maximum diameter of the second structure formed by the distal core wire 304 in the second configuration. In some embodiments, the second diameter D2 is not greater than the inner diameter of a stent when the stent, which is configured to be used with the stent pusher 300, is in an expanded stent configuration. The second diameter D2 can be between about 2 millimeters and about 4.5 millimeters, between about 2.5 millimeters and about 4 millimeters, between about 3 millimeters and about 3.5 millimeters, about 2 millimeters, about 2.5 millimeters, about 3 millimeters, about 3.5 millimeters, about 4 millimeters, or about 4.5 millimeters. The ratio between the second diameter D2 of the second structure and the first diameter D1 of the first structure can be between about 3 and about 23, between about 5 and about 20, or between about 10 and about 15. The ratio between the second diameter D2 and the first diameter D1 can be at least 3, at least 5, at least 10, at least 15, or at least 20.

[0076] As Figure 3 and Figure 4BAs shown, in some embodiments, the distal core wire 304 forms a coiled three-dimensional second structure in the second configuration and includes a coil portion 312 that defines a plurality of coils 314. In some embodiments, the coil portion 312 does not include the entire distal core wire 304 (e.g., the coil portion 312 has a length that is less than the total length of the distal core wire 304). Thus, the distal core wire 304 can include a distal straight portion 316 between the coil portion 312 and the distal end 304b of the distal core wire 304. The distal straight portion 316 can prevent or limit contact of the distal end 304b of the distal core wire 304 with a blood vessel when the distal core wire 304 is advanced distally out of the catheter lumen. In the absence of the distal straight portion 316, when the distal core wire 304 assumes a coiled configuration, the distal end 304b of the distal core wire 304 may contact a blood vessel shortly after being released from the catheter lumen. Such contact with the vessel wall can result in injury and / or bleeding. In some embodiments, it may be useful for the distal straight portion 316 to have a length that is long enough to prevent or limit the distal end 304b of the distal core wire 304 from swaying or otherwise moving when the coil portion 312 is positioned outside the catheter lumen and expanded. The straight portion 316 can act as a buffer to absorb the movement of the coil portion 312 and stabilize the distal end 304b. However, the distal straight portion 316 can have a length that is small enough to prevent or limit contact and damage to the vessel wall when the stent pusher 300 is advanced distally.

[0077] The straight portion 316 can have a length of about 5 millimeters to about 10 millimeters, about 6 millimeters to about 9 millimeters, about 7 millimeters to about 8 millimeters, about 5 millimeters, about 6 millimeters, about 7 millimeters, about 8 millimeters, about 9 millimeters, about 10 millimeters, less than about 10 millimeters, less than about 9 millimeters, less than about 8 millimeters, less than about 7 millimeters, less than about 6 millimeters, or less than about 5 millimeters. The length of the straight portion 316 can be about 30% of a second length L2 of the second structure formed by the distal core wire 304, about 25% of the second length L2 of the second structure formed by the distal core wire 304, about 20% of the second length L2 of the second structure formed by the distal core wire 304, about 15% of the second length L2 of the second structure formed by the distal core wire 304, about 10% of the second length L2 of the second structure formed by the distal core wire 304, about 5% of the second length L2 of the second structure formed by the distal core wire 304, or less than 5% of the second length L2 of the second structure formed by the distal core wire 304. In some embodiments, the length and / or diameter of the distal core wire 304 at the distal straight portion 316 is substantially unchanged between the first configuration and the second configuration. For example, in either configuration, the diameter of the straight portion 316 can be the same as the diameter of the distal core wire 304 itself.

[0078] According to various embodiments, the distal end 304b and / or the distal straight portion 316 of the distal core wire 304 may include radiopaque markers to facilitate visualization of the distal core wire 304 when located within a patient's vasculature. The distal end 304b and / or the distal straight portion 316 of the distal core wire 304 may include a coil (e.g., formed of a coil, carrying a coil, etc.) configured to impart flexibility to the distal end 304b and / or the distal straight portion 316 of the distal core wire 304. Such a coil may be radiopaque. The stent may include radiopaque markers to facilitate visualization of the stent when located within a patient's vasculature. In some embodiments, the position of the radiopaque marker carried by the distal core wire 304 may be compared to the position of the radiopaque marker carried by the stent to advantageously evaluate shortening of the distal core wire 304 relative to shortening of the stent during use.

[0079] In the case where the distal core wire 304 forms a coiled second structure in the second configuration, the second diameter D2 may be measured between adjacent peaks 318a, 318b of the coil portion 312. The distal core wire 304 may form any suitable three-dimensional second structure in the second configuration such that the second diameter D2 is greater than the first diameter D1 and the second length L2 is less than the first length L1. For example, the distal core wire 304 may be folded in the second configuration such that the distal straight portion 316 is longitudinally positioned proximate the reinsertion loop 308 and radially offset from the reinsertion loop. Accordingly, a first portion of the distal core wire 304 extending between the proximal end 304a and the fold may be radially spaced apart from a second portion of the distal core wire 304 extending between the fold and the distal straight portion 316 such that the second diameter D2 is based on the radial offset between the first and second portions of the distal core wire 304. Additionally or alternatively, the distal core wire 304 may carry one or more radially expandable elements such as a braid, balloon, resilient disk, etc., the one or more radially expandable elements being configured to expand upon release from the catheter lumen to facilitate expansion of an overlying stent.

[0080] The second length L2 of the second structure formed by the distal core wire 304 may be selected such that the shortening rate of the distal core wire 304 when transitioning from the first configuration to the second configuration is similar to (e.g., within plus or minus 10%) and / or equal to the shortening rate of a stent with which the stent pusher 300 is configured to be used. The shortening rate of the distal core wire 304 being equivalent to the shortening rate of the stent allows the distal end 304b of the distal core wire 304 to remain substantially longitudinally aligned with the distal end of the stent, which may prevent or limit contact of the distal end 304b with the vessel wall. The shortening rate of the distal core wire 304 being greater than the shortening rate of the stent allows the distal end 304b of the distal core wire 304 to travel proximally relative to the distal end of the stent, which may also prevent or limit contact of the distal end 304b with the vessel wall.

[0081] The shortening rate of the distal core wire 304 can be determined by subtracting the first length L1 from the second length L2 and then dividing by the first length L1. Only as an example, if a stent configured to be used with the stent pusher 300 has a shortening rate of 30%, the second length L2 should be 70% of the first length L1. According to various embodiments, the shortening rate of the distal core wire 304 can be about 20%, about 30%, about 40%, and / or about 50%. As previously described, the shortening rate of the distal core wire 304 can substantially correspond to the shortening rate of the stent to be used with the stent pusher 300. The second length L2 of the second structure formed by the distal core wire 304 is a function of the first length L1 of the first structure formed by the distal core wire 304 in the first configuration, the pitch P of the second structure formed by the distal core wire 304 in the second configuration, and the second diameter D2. In some embodiments, the second diameter D2 is based on the inner diameter of the expanded stent that the stent pusher 300 is configured to be used with. The second diameter D2 can be selected to balance the expansion force and ease of use. A larger second diameter D2 can enable the distal core wire 304 to apply a greater radial expansion force on the stent during deployment and can increase the ease of massaging and adjusting the stent with the distal core wire 304. However, if the radial expansion force from the distal core wire 304 with a larger second diameter D2 is too high, the distal core wire 304 can damage the blood vessel and may cause dissection. In contrast, a smaller second diameter D2 may be less effective in assisting stent expansion but may be less likely to damage the blood vessel. The second diameter D2 can be equal to the inner diameter of the expanded stent. In some embodiments, the second diameter D2 can be less than the inner diameter of the expanded stent to prevent the distal core wire 304 from applying a large radial force on the stent. The second diameter D2 can be about 5%, about 10%, or about 15% smaller than the minimum recommended blood vessel diameter used by the stent to be used with the stent pusher 300. The pitch P of the distal core wire 504 can be selected based on the desired first length L1, second length L2, and second diameter D2 of the distal core wire 304.

[0082] The first diameter D1 of the first structure formed by the distal core wire 304 may not be greater than the inner diameter of the stent to be used with the stent pusher 300 in the compressed stent configuration. In some embodiments, the first diameter D1 is less than the inner diameter of the stent to be used with the stent pusher 300 in the compressed stent configuration. In the expanded stent configuration, the second diameter D2 of the second structure formed by the distal core wire 304 may be greater than the first diameter D1 but not greater than and / or less than the inner diameter of the stent to be used with the stent pusher 300. It may be advantageous for the second diameter D2 of the second structure formed by the distal core wire 304 not to be greater than the inner diameter of the stent to prevent the distal core wire 304 from causing trauma to the vessel wall during expansion. Self-expanding stents are typically oversized relative to the indicated vessel diameter, so sizing the distal core wire 304 relative to the stent may result in the distal core wire 304 applying too much radial force on the stent and the vessel wall, which may potentially damage the vessel or cause the stent to translate away from its desired deployment location. According to various embodiments, the second diameter D2 may be at least three times the first diameter D1.

[0083] The distal core wire 304 may be formed of a material that facilitates its transition from the first configuration to the second configuration. For example, the distal core wire 304 may include a material having high elasticity, such as a superelastic material. The second configuration may include a passive, unloaded state, and the distal core wire 304 may be deformed to assume the first configuration, for example, by inserting the distal core wire 304 into a catheter lumen. For example, the deforming force may be removed when the distal core wire 304 is released from the catheter lumen, which may allow the distal core wire 304 to elastically return to the second configuration. In some embodiments, the distal core wire 304 includes a material such as nitinol, stainless steel, and / or another elastic and biocompatible metal. In some embodiments, the distal core wire 304 may include a shape memory material (e.g., shape memory alloy, nitinol, etc.) and may have a transition temperature above which the distal core wire 304 transitions from the first configuration to the second configuration.

[0084] The distal core wire 304 may include a shape memory material that is configured to exhibit an austenite parent phase at high temperature and a martensite phase at low temperature. There are four transition temperatures associated with the austenite-to-martensite and martensite-to-austenite transitions of the shape memory material. When the material is cooled to the martensite start temperature (Ms), martensite begins to form from the fully austenite. The temperature at which the transformation is complete is called the martensite finish temperature (Mf). When the material is fully martensite and subjected to heating, austenite begins to form at the austenite start temperature (As) and ends at the austenite finish temperature (Af).

[0085] The crystal structure of martensite allows a shape memory material in the martensite state to undergo certain deformations without breaking atomic bonds. For example, a shape memory material in the martensite state can undergo a strain of about 6% to 8%. Thus, when the temperature of the material is below the As temperature, the material retains its martensite structure and is generally flexible and plastic. The deformation of the martensite structure is retained. When the temperature of the material is raised above the As temperature, the martensite begins to transform into austenite, and when the temperature of the material is raised above the Af temperature, the transformation is complete. Once in the austenite state, the shape memory material becomes elastic again and returns to its original shape.

[0086] In some cases, it may be useful to set the Af temperature and / or the As temperature of the distal core wire 304 to be above room temperature so that the distal core wire 304 can be manipulated while in the martensite phase. The distal core wire 304 in the martensite phase can be easily deformed to assume its first configuration and form a first structure that is compressed to a small diameter inside the catheter. The distal core wire 304 in the martensite phase does not exert excessive expansion force on the stent inside the catheter, and since the distal core wire 304 is in the martensite phase, the distal core wire 304 remains deformed in the first configuration. The Af temperature of the distal core wire 304 can be approximately equal to body temperature so that the distal core wire 304 is configured to transform into austenite after being delivered to a treatment location inside the patient's vasculature. When the distal core wire 304 transforms into austenite, it can recover the remembered shape, where the distal core wire 304 forms a second structure in the second configuration. This shape recovery can cause self-expansion of the distal core wire 304.

[0087] In some embodiments, the distal core wire 304 has an As temperature at which the distal core wire 304 begins to transform from the first configuration to the second configuration and / or an Af temperature at which the distal core wire 304 completes the transformation from the first configuration to the second configuration. The Af of the distal core wire 304 can be based on and / or similar to normal body temperature such that in response to the stent pusher 300 being positioned within the patient's vasculature, the temperature of the distal core wire 304 is raised above the Af of the distal core wire 304 and / or the Af of the distal core wire 304, and the distal core wire 304 transforms into the second configuration. For example, the average body temperature is 36.7 °C, and the Af of the distal core wire 304 can be about 35 °C, about 36 °C, about 37 °C, or about 38 °C.

[0088] The proximal core wire 302 and / or the distal core wire 304 may include wires, tubes (e.g., hypotubes), braids, coils, or other suitable components, or combinations of wires, tubes, and / or other elongate members. The proximal core wire 302 may have features common to the distal core wire 304, and / or the proximal core wire 302 may have one or more features different from the distal core wire 304. For example, the proximal core wire 302 may have sufficient column strength to support translation of the stent pusher 300 relative to the overlying catheter, while the distal core wire 304 may be sufficiently flexible to support shape changes from a first configuration to a second configuration. In some embodiments, one or more portions of the distal core wire 304 (e.g., the distal end 304b, the distal straight portion 316, etc.) are soft such that if one or more portions of the distal core wire 304 contact the vessel wall, they do not cause significant trauma. The parameters of the proximal core wire 302 and / or the distal core wire 304 may be selected based on the intended characteristics or functions of the respective core wires. For example, the proximal core wire 302 may have a larger diameter than the distal core wire 304, and / or the proximal core wire 302 may be formed of a harder material than the distal core wire 304. In some embodiments, the proximal core wire 302 includes a harder material, such as stainless steel, while the distal core wire 304 includes a more flexible material, such as nitinol.

[0089] The proximal core wire 302 may be integral with the distal core wire 304, or the proximal core wire 302 and the distal core wire 304 may be formed as discrete components that are fixed together after being formed separately. In some embodiments, the distal end 302b of the proximal core wire 302 is fixed to the proximal end 304a of the distal core wire 304 using brazing, welding, adhesives, mechanical fasteners, and / or other suitable fastening. As Figure 5 shown, in some embodiments, the fastening material 317 (e.g., adhesive, solder, etc.) may be positioned over the joint between the distal end 302b of the proximal core wire 302 and the proximal end 304a of the distal core wire 304.

[0090] The proximal core wire 302 and / or the distal core wire 304 may include a lubricating material positioned on at least a portion of the wire, such as PTFE (polytetrafluoroethylene or TEFLON TM ), or other polymers. The diameter of the proximal core wire 302 and / or the diameter of the distal core wire 304 may vary and / or taper along some or all of the length of the respective core wire. The proximal core wire 302 and / or the distal core wire 304 may include one or more fluorosafe and / or radiopaque markers (not shown), which include bands, deposited materials, exposed portions of the core wire, etc. In some embodiments, the distal end 304b of the distal core wire 304 may include and / or carry a coil, which may facilitate navigation of the stent pusher 300 through the vasculature and / or visualization of the stent pusher 300.

[0091] The stent pusher 300 can be configured to carry a stent on the distal core wire 304. As Figure 3 and Figure 5 shown, the stent pusher 300 can include a pusher ring 306 that is configured to engage the proximal end of a stent carried by the distal core wire 304. The pusher ring 306 can include a proximally facing surface 320, a distally facing surface 322, and a sidewall 324 extending between the proximally facing surface 320 and the distally facing surface 322. In some embodiments, the sidewall 324 is substantially tubular such that the pusher ring 306 is annular. The pusher ring 306 can include another suitable shape, such as a rectangular prism, a triangular prism, a sphere, and / or any other suitable shape for engaging the proximal end of a stent carried by the stent pusher 300. The pusher ring 306 or one or more portions thereof (e.g., the distally facing surface 322 of the pusher ring 306) can be configured to apply a distally directed force to the proximal end of the stent to translate the stent out of the catheter lumen and / or to prevent or limit proximal movement of the stent relative to the stent pusher 300. The pusher ring 306 can have an outer diameter that is larger than the outer diameter of the distal core wire 304 and / or the proximal core wire 302. Specifically, the pusher ring 306 can have an outer diameter that corresponds to and / or is slightly larger than the outer diameter of a stent in a compressed stent configuration that is configured to be used with the stent pusher 300. Additionally or alternatively, the pusher ring 306 can have an outer diameter that is smaller than the outer diameter of a stent in a deployed stent configuration that is configured to be used with the stent pusher 300.

[0092] The pusher ring 306 can be positioned proximate to the junction between the proximal core wire 302 and the distal core wire 304. In some embodiments, for example as Figure 5As shown, the pusher ring 306 can be carried by the distal core wire 304. Alternatively, the pusher ring 306 can be carried by the proximal core wire 302 and / or positioned between the proximal core wire 302 and the distal core wire 304. The pusher ring 306 (or a portion thereof) can be configured to rotate relative to the proximal core wire 302 and / or the distal core wire 304. For example, the pusher ring 306 can define an aperture 326 that is configured to receive the proximal core wire 302 and / or the distal core wire 304 therein. The aperture 326 can have a diameter that is at least as large as the outer diameter of the core wire configured to be received therein. In some embodiments, the diameter of the aperture 326 is greater than the outer diameter of the core wire configured to be received therein such that there is a radial gap between the pusher ring 306 and the core wire and the pusher ring 306 can rotate relative to the core wire. However, in some embodiments, the pusher ring 306 is carried by the proximal core wire 302 and / or the distal core wire 304 and / or fixed to the proximal and / or distal core wire such that the pusher ring 306 cannot rotate relative to the proximal core wire 302 and / or the distal core wire 304. For example, the aperture 326 of the pusher ring 306 can be slightly reduced in size relative to the outer diameter of the core wire configured to be received therein such that friction between the pusher ring 306 and the core wire prevents the pusher ring 306 from rotating on the core wire.

[0093] In various embodiments, the pusher ring 306 can be configured to tilt relative to the proximal core wire 302 and / or the distal core wire 304, which can facilitate navigation of the stent pusher 300 through tortuous anatomy. This tilting can be achieved by sizing the aperture 326 to be larger than the outer diameter of the core wire configured to be received therein. However, in some embodiments, the pusher ring 306 cannot tilt relative to the proximal core wire 302 and / or the distal core wire 304.

[0094] The pusher ring 306 may be longitudinally slidable relative to the proximal core wire 302 and / or the distal core wire 304, or may be longitudinally fixed relative to the proximal core wire 302 and / or the distal core wire 304. For example, if the pusher ring 306 is carried by the proximal core wire 302 and / or the distal core wire 304 and there is an interference fit between the pusher ring 306 and the proximal core wire 302 and / or the distal core wire 304, then the pusher ring 306 may not be slidable relative to the proximal core wire 302 and / or the distal core wire 304. Additionally or alternatively, the pusher ring 306 may be fixed to the proximal core wire 302 and / or the distal core wire 304 by welding, brazing, adhesives, mechanical fastening, etc., such that the pusher ring 306 cannot slide. In some embodiments, the pusher ring 306 is not fixed to the proximal core wire 302 and / or the distal core wire 304 and there is a loose fit between the pusher ring 306 and the proximal core wire 302 and / or the distal core wire 304, such that the pusher ring 306 is slidable relative to the core wire. In some embodiments, one or more restraints may be carried by the proximal core wire 302 and / or the distal core wire 304 and may be positioned proximal and / or distal to the pusher ring 306 such that the restraints limit the longitudinal movement of the pusher ring 306.

[0095] According to some embodiments, the engagement portion 305 includes a re-sheathing ring 308 that is configured to facilitate re-sheathing a stent carried by the stent pusher 300. As Figure 5 shown, the re-sheathing ring 308 may be carried by the distal core wire 304 and positioned distal to the pusher ring 306. The re-sheathing ring 308 may be configured to engage the inner surface of the stent and move the stent proximally relative to the catheter such that the stent can be re-sheathed into the catheter lumen. In some embodiments, the re-sheathing ring 308 includes a polymeric cylindrical pad and / or an elastic coil that is oversized relative to the inner diameter of the compressed stent such that when the stent is compressed onto the pad and / or coil, the pad and / or coil frictionally engages the inner surface of the stent. According to various embodiments, the re-sheathing ring 308 may include a rigid (e.g., formed of metal or rigid polymer) sprocket having protrusions configured to extend into the holes of the stent and engage the stent along the thickness of its sidewalls. The re-sheathing ring 308 may include any suitable engagement member, stent engagement member, and / or coupler described in U.S. Patent Application No. 63 / 269,157, U.S. Patent Application No. 15 / 951,779, and / or U.S. Patent Application No. 16 / 459,118, each of which is incorporated herein by reference in its entirety.

[0096] The reinsertion ring 308 (or a portion thereof) can be configured to rotate relative to the distal core wire 304. For example, the reinsertion ring 308 can define an aperture 328 configured to receive the distal core wire 304 therein. The aperture 328 can have a diameter that is at least as large as the outer diameter of the distal core wire 304. In some embodiments, the diameter of the aperture 328 is greater than the outer diameter of the distal core wire 304 such that there is a radial gap between the reinsertion ring 308 and the distal core wire 304, and the reinsertion ring 308 can rotate relative to the distal core wire 304. However, in some embodiments, the reinsertion ring 308 is carried by and / or fixed to the distal core wire 304 such that the reinsertion ring 308 cannot rotate relative to the distal core wire 304. For example, the aperture 328 of the reinsertion ring 308 can be slightly reduced in size relative to the outer diameter of the distal core wire 304 such that friction between the reinsertion ring 308 and the distal core wire 304 prevents the reinsertion ring 308 from rotating on the distal core wire 304.

[0097] In various embodiments, the reinsertion ring 308 can be configured to tilt relative to the distal core wire 304, which can facilitate navigation of the stent pusher 300 through tortuous anatomy. This tilting can be achieved by sizing the aperture 328 to be larger than the outer diameter of the distal core wire 304. However, in some embodiments, the reinsertion ring 308 cannot tilt relative to the distal core wire 304.

[0098] The reinsertion ring 308 may be able to slide longitudinally relative to the distal core wire 304 or may be longitudinally fixed relative to the distal core wire 304. For example, if the reinsertion ring 308 is carried by the distal core wire 304 with an interference fit between the reinsertion ring 308 and the distal core wire 304, the reinsertion ring 308 may not be able to slide relative to the distal core wire 304. Additionally or alternatively, the reinsertion ring 308 can be fixed to the distal core wire 304 by welding, brazing, adhesives, mechanical fastening, etc. such that the reinsertion ring 308 cannot slide. In some embodiments, the reinsertion ring 308 is not fixed to the distal core wire 304 and there is a loose fit between the reinsertion ring 308 and the distal core wire 304 such that the reinsertion ring 308 can slide relative to the distal core wire. In some embodiments, one or more restraints can be carried by the distal core wire 304 and can be positioned proximal and / or distal to the reinsertion ring 308 such that the restraints limit longitudinal movement of the reinsertion ring 308 relative to the distal core wire 304.

[0099] Although Figure 3 and Figure 5306 and the re-entry ring 308. The spacer may be carried by the distal core wire 304 and configured to define a minimum longitudinal distance between the pusher ring 306 and the re-entry ring 308. The spacer may include a coil, a solid tube, or other structural element that may be mounted on the distal core wire 304 to longitudinally separate adjacent components of the engagement portion 305, such as the pusher ring 306 and the re-entry ring 308. In some embodiments, the one or more spacers may be zero pitch coils with flat ends and / or tubes (e.g., laser cut tubes, solid tubes, etc.) that may be rotatably mounted or non-rotatably fixed (e.g., welded) to the distal core wire 304. The spacer may have a radially outermost dimension that is smaller than the radially outermost dimension of the pusher ring 306 and / or the re-entry ring 308, such that the spacer does not contact the stent during normal operation of the stent pusher 300.

[0100] like Figure 3 and Figure 5 As shown, the stent pusher 300 may include a sheath 310 positioned over at least a portion of the proximal core wire 302. The sheath 310 may facilitate navigation of the stent pusher 300 through the catheter lumen. For example, the sheath 310 may include a coil so that the sheath 310 enhances the pushability of the stent pusher 300 while maintaining the lateral and / or bending flexibility of the stent pusher 300. Additionally or alternatively, the sheath 310 may reduce the gap between the proximal core wire 302 and the catheter lumen, which may improve pushability and reduce the risk of kinking when navigating tortuous vessels. In addition, the sheath 310 may cover the joint between the distal end 302b of the proximal core wire 302 and the proximal end 304a of the distal core wire 304 to prevent or limit degradation of the joint as the stent pusher 300 is used. For example, as Figure 5 As shown, the sheath 310 may radially include a fastening material 317 positioned above the joint between the distal end 302b of the proximal core wire 302 and the proximal end 304a of the distal core wire 304. The sheath 310 may include a coil (see Figure 3 and Figure 5 ) or any other suitable tubular structure, such as a hypotube, braid, etc.

[0101] Figure 6A and Figure 6B The stent pusher 300 is shown deploying a stent 600 from a catheter 602 at a treatment site within a blood vessel. Stents configured for use with the stent pushers of the present technology, including stent 600, may include a tubular medical device configured to radially expand from a compressed stent configuration to an expanded stent configuration. Figure 6A and Figure 6BAs shown, the stent 600 includes a proximal end portion 600a and a distal end portion 600b that is opposite the proximal end portion 600a along the longitudinal dimension of the stent 600. The stent 600 can be configured to transition between a compressed stent configuration (e.g., see Figure 6A ) and an expanded stent configuration (e.g., see Figure 6B ). In the compressed stent configuration, the stent 600 has a first stent length and a first stent diameter. In the expanded stent configuration, the stent 600 has a second stent length that is less than the first stent length and a second stent diameter that is greater than the first stent diameter.

[0102] The stent 600 can be braided, knitted, woven, and / or laser cut and can include a mesh forming a plurality of holes defined by filaments, wires, or struts and separated by points where the filaments, wires, or struts cross (e.g., in the case of a braided or woven stent) or intersect (e.g., in the case of a laser cut stent). In some embodiments, the stent 600 includes a graft, a rolled-up stent, a tubular implant, and / or another interventional element. The stent can have a therapeutic function. For example, the stent 600 can be configured to act as a "flow diverter" device for treating aneurysms, such as those found in blood vessels in the brain or within the skull or at other locations in the body such as peripheral arteries. Thus, the stent 600 can have a porosity that is low enough (e.g., a surface coverage that is high enough, a density that is high enough, etc.) to prevent or limit blood flow through the sidewalls of the stent. For example, the stent 600 can have a surface coverage of at least 20%. The stent 600 can optionally be similar to any version or size of the PIPELINE TM embolization device sold by Medtronic Neurovascular of Irvine, California USA. In some embodiments, the stent 600 can be any of the stents described in U.S. Application No. 15 / 892,268, entitled "VASCULAR EXPANDABLE DEVICES," filed on February 8, 2018, the entire content of which is hereby incorporated herein by reference.

[0103] As Figure 6A shown, the stent pusher 300 and the stent 600 can be positioned within the lumen 604 of the catheter 602 for navigation through a blood vessel to a treatment site. The catheter 602 can include any suitable elongate shaft defining a lumen for receiving the stent pusher 300 and the stent 600. The catheter 602 can optionally include various lengths of MARKSMAN available from Medtronic Neurovascular of Irvine, California USA TMAny catheter within a catheter. In some embodiments, catheter 602 includes a microcatheter having an inner diameter of about 0.030 inches or less (e.g., 0.027 inches, 0.021 inches, 0.017 inches, etc.) and / or an outer diameter of 3 French or less near its distal end. Catheter 602 may include a microcatheter configured to enter the internal carotid artery, another location distal to the internal carotid artery within the neurovascular system, or any other suitable location.

[0104] When positioned within lumen 604, stent pusher 300 may carry stent 600. Specifically, stent 600 may be disposed over distal core wire 304 such that proximal end portion 600a of stent 600 is positioned distal to pusher ring 306. Lumen 604 of catheter 602 may have a diameter smaller than a second stent diameter (e.g., the diameter of the stent in an expanded stent configuration) and / or smaller than a second diameter D2 of distal core wire 304 (e.g., the diameter of distal core wire 304 when in a second radially expanded configuration). Thus, when positioned within lumen 604, stent 600 and distal core wire 304 may be in a compressed stent configuration and a first configuration, respectively. In the first configuration, distal core wire 304 is substantially straight, where a first diameter D1 of distal core wire 304 is not greater than the inner diameter of stent 600 in a compressed stent configuration.

[0105] The distal end 602b of catheter 602 may be positioned at or adjacent to the treatment site. For example, as Figure 6A shown, in some embodiments, distal end 602b of catheter 602 is positioned distal to an aneurysm. To deploy stent 600 at the treatment site, stent pusher 300 and stent 600 may be advanced distally relative to catheter 602. Catheter 602 may be pulled proximally while preventing or restricting proximal movement of proximal core wire 302. Additionally or alternatively, proximal core wire 302 may be advanced distally while preventing or restricting distal movement of catheter 602. Either way, pusher ring 306 may engage proximal end portion 600a of stent 600 and apply a distally directed force to stent 600. In some embodiments, for example, if the re-sheathing ring 308 is configured to apply an outward force to stent 600 in a compressed configuration, distal movement of proximal core wire 302 and re-sheathing ring 308 relative to catheter 602 may cause re-sheathing ring 308 to apply a distally directed force to stent 600.

[0106] Releasing the stent 600 from the lumen 604 of the catheter 602 allows the stent 600 to self-expand. In some embodiments, the stent 600 can be actively expanded by a separate expandable element (e.g., a balloon, braid, release member, etc.). Releasing the distal core wire 304 from the lumen 604 of the catheter 602 can allow the distal core wire 304 to transition from a first configuration to a second (e.g., radially expanded and longitudinally shortened) configuration. The distal core wire 304 can be configured to transition from the first configuration to the second configuration after a duration has passed after being released from the catheter 602 (e.g., if additional time is required for the temperature of the distal core wire 304 to rise above the transition temperature of the distal core wire 304). Alternatively, the distal core wire 304 can be configured to transition from the first configuration to the second configuration immediately upon being released from the catheter 602. The rapid transition of the distal core wire 304 from the first configuration to the second configuration can enable the distal core wire 304 to press radially outward against the stent 600 when the stent 600 expands, facilitating such expansion and anchoring of the stent 600 to the vessel wall.

[0107] Figure 6B Depicted is the stent 600 deployed at the treatment site and in an expanded stent configuration. As Figure 6B shown, full expansion of the stent 600 can be permitted by positioning the distal end portion 602b of the catheter 602 proximal to the proximal end portion 600a of the stent 600. In other words, the entire stent 600 can be positioned distal and external to the lumen 604 of the catheter 602. When the distal core wire 304 is positioned distal and external to the lumen 604, the released portion of the distal core wire 304 can assume a predetermined second configuration and form a second structure that has a greater diameter than the first structure formed by the distal core wire 304 when the distal core wire 304 was within the lumen 604. Additionally, as the distal core wire 304 is released from the lumen 604 and transitions to the second configuration, the length of the structure formed by the distal core wire 304 decreases (e.g., the length of the second structure formed by the distal core wire 304 in the second configuration is less than the length of the first structure formed by the distal core wire 304 in the first configuration). Thus, the structure formed by the distal core wire 304 can radially expand and longitudinally shorten along with the expansion and shortening of the stent 600. As the structure formed by the distal core wire 304 transitions to a larger diameter, the distal core wire 304 can apply a radially outward force to any portion of the stent 600 that is expanding slowly or not expanding, which can facilitate the expansion of the stent 600. Additionally, because the structure formed by the distal core wire 304 shortens when transitioning to the second configuration, the distal straight portion 316 of the distal core wire 304 can be advanced distally only a small distance or not at all, reducing the risk of vessel wall damage associated with a straight stent pusher. As Figure 6A and Figure 6BAs shown, the distal end 304b of the distal core wire 304 may be advanced distally very little, thereby preventing or limiting contact of the distal end 304b with and potential damage to the blood vessel.

[0108] In some cases, it may be desirable to withdraw at least a portion of the stent 600 into the lumen 604 of the catheter 602 after at least partially delivering the stent 600. For example, a user may expand the distal portion 600b of the stent 600 before realizing that the stent 600 is not positioned at the intended treatment site, is not the appropriate size, etc. Accordingly, the stent 600 may be pulled proximally relative to the catheter 602 such that at least a portion of the stent 600 is re-sheathed into the lumen 604. To move the stent 600 proximally relative to the catheter 602, the catheter 602 may be moved distally relative to the blood vessel while preventing or limiting distal movement of the stent pusher 300 relative to the blood vessel, and / or the stent pusher 300 may be moved proximally relative to the blood vessel while preventing or limiting proximal movement of the catheter 602 relative to the blood vessel. Because the re-sheathing ring 308 engages the stent 600 in a compressed configuration, proximal movement of the proximal core wire 302 and the re-sheathing ring 308 relative to the catheter 602 may cause the re-sheathing ring 308 to apply a proximally-directed force to the stent 600. This proximally-directed force may cause the stent 600 to move proximally relative to the catheter 602 and into and / or through the lumen 604.

[0109] In the case where the re-sheathing ring 308 is released from the lumen 604 and the overlying portion of the stent 600 is permitted to expand, the re-sheathing ring 308 may no longer engage the inner surface of the stent 600 and, thus, may no longer apply a proximally-directed re-sheathing force to the stent 600. As a result, it may be advantageous for the re-sheathing ring 308 to be positioned precisely distally of the pusher ring 308 (e.g., spaced no more than 6 mm, spaced no more than 3 mm, spaced no more than 2 mm, etc.) such that a greater length of the stent 600 may be delivered before the re-sheathing ring 308 is released from the lumen 604 and re-sheathing of the stent 600 is no longer possible. In some embodiments, the re-sheathing ring 308 may be positioned relative to the pusher ring 306 such that re-sheathing is possible after at least 60% of the stent 600 has been deployed, at least 75% of the stent 600 has been deployed, at least 80% of the stent 600 has been deployed, at least 85% of the stent 600 has been deployed, at least 90% of the stent 600 has been deployed, or at least 95% of the stent 600 has been deployed.

[0110] Figure 7 and Figure 8 is schematically depicted deploying the stent 700 using the stent pusher 300 of the present technology (see Figure 8 ) as compared to deploying the stent 700 using a conventional straight stent pusher 800 (see Figure 7The benefits of (). After deploying the stent 700, the doctor typically adjusts the stent 700 in a massaging manner and positions the stent 700 against the vessel wall. This massaging adjustment may include iteratively pushing (e.g., advancing distally) and pulling back (e.g., retracting proximally) the stent pusher, as Figure 7 and Figure 8 depicted by the dashed arrows in. This manipulation causes the stent pusher to engage the inner surface of the stent 700, which can apply a radially outward force to the stent 700 to facilitate the opening and positioning of the stent 700. As Figure 7 shown, since the diameter of the second structure formed by the distal core wire 304 in the second configuration is larger, the distal core wire does not have to travel very far (if at all) to contact the inner surface of the stent 700 and apply a radially outward force to the stent 700. In contrast and as Figure 8 shown, the distal core wire 804 of the straight stent pusher 800 must travel radially across the lumen of the vessel (as Figure 8 depicted by the solid arrow in) to reach the inner surface of the stent 700. Thus, engaging a particular portion of the stent 700 with the stent pusher 800 can be challenging and requires additional manipulation of the stent pusher 800, thereby adding time and complexity to the procedure.

[0111] Conclusion

[0112] Although many embodiments have been described above with respect to systems, devices, and methods for delivering a stent to a treatment site within a blood vessel, the technology is also applicable to other applications and / or other methods. Additionally, other embodiments other than those described herein are also within the scope of the technology. Additionally, several other embodiments of the technology may have configurations, components, or procedures different from those described herein. Accordingly, one of ordinary skill in the art will understand that the technology may have other embodiments with additional elements, or the technology may have other embodiments without several of the features referenced above Figures 1A to 8 shown and described.

[0113] The description of embodiments of the technology is not intended to be exhaustive or to limit the technology to the exact forms disclosed above. Where context permits, the singular term or plural term may also respectively include the plural term or the singular term. While specific embodiments and examples of the technology have been described above for illustrative purposes, those skilled in the relevant art will recognize that various equivalent modifications can be made within the scope of the technology. For example, while steps are presented in a given order, alternative embodiments may perform the steps in a different order. The various embodiments described herein can also be combined to provide additional embodiments.

[0114] As used herein, the terms "substantially," "essentially," "about" and similar terms are used as approximate terms and not as terms of degree, and are intended to account for the inherent deviations of the measured or calculated values recognized by one of ordinary skill in the art.

[0115] In addition, unless the word "or" is explicitly limited to mean a single item that excludes the other items when referring to a list of two or more items, the use of "or" in such a list shall be construed to include (a) any single item in the list, (b) all items in the list, or (c) any combination of items in the list. Additionally, the term "comprising" is used throughout to mean including at least the recited features, such that any greater number of the same features and / or additional types of other features are not excluded. It should also be understood that specific embodiments have been described herein for purposes of illustration, but various modifications may be made without departing from the technology. Additionally, while advantages associated with certain embodiments of the technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need to exhibit such advantages to fall within the scope of the technology. Accordingly, the present disclosure and the associated technology may cover other embodiments not expressly shown or described herein.

Claims

1. A stent pusher assembly, comprising: A stent pusher, the stent pusher comprising: A proximal core wire, the proximal core wire comprising a proximal end and a distal end opposite the proximal end along a longitudinal dimension of the proximal core wire; A distal core wire, the distal core wire comprising a proximal end at the distal end of the proximal core wire and a distal end opposite the proximal end of the distal core wire along a longitudinal dimension of the distal core wire; and A pusher ring carried by the distal core wire, the pusher ring being configured to contact a proximal end portion of the stent to apply a distally directed force to the proximal end portion of the stent to prevent or limit proximal movement of the stent relative to the stent pusher, wherein the distal core wire is configured to transition between a first configuration in which the distal core wire forms a first structure and a second configuration in which the distal core wire forms a second structure, wherein in the first configuration, the first structure formed by the distal core wire is substantially straight without coils, and the first structure defines a first length and a first diameter, and wherein in the second configuration, the second structure formed by the distal core wire comprises a coil portion defining a plurality of coils, and the second structure defines a second length less than the first length and a second diameter greater than the first diameter.

2. The stent pusher assembly according to claim 1, further comprising: A stent, the stent comprising a tubular structure, the tubular structure comprising a proximal end portion and a distal end portion opposite the proximal end portion along a longitudinal dimension of the stent, the stent being configured to be positioned above the distal core wire, wherein the proximal end portion of the stent is distal to the pusher ring, wherein the stent is configured to transition between a compressed stent configuration and an expanded stent configuration, wherein in the compressed stent configuration, the stent defines a first stent length and a first stent diameter, and wherein in the expanded stent configuration, the stent defines a second stent length less than the first stent length and a second stent diameter greater than the first stent diameter; and A catheter, the catheter defining a lumen, wherein the lumen defines a lumen inner diameter less than the second diameter of the distal core wire and the second stent diameter, wherein the stent is configured to be positioned within the lumen of the catheter in the compressed stent configuration, wherein the distal core wire is in the first configuration and is positioned within the stent, and wherein the pusher ring is configured to engage the stent to translate the stent out of the lumen of the catheter such that the stent can transition from the compressed stent configuration to the expanded stent configuration and such that the distal core wire can transition from the first configuration to the second configuration.

3. The stent pusher assembly according to claim 2, wherein the distal core wire is configured to be pushed out of the lumen of the catheter into a blood vessel in the first configuration and is configured to transition from the first configuration to the second configuration when located outside the lumen of the catheter.

4. The stent pusher assembly according to claim 1, wherein the distal core wire comprises a shape memory alloy and has an austenite finish (Af) temperature of about 36 °C, so as to cause the distal core wire to transition from the first configuration to the second configuration in response to the temperature of the distal core wire rising above the Af temperature when positioned in a blood vessel.

5. The stent pusher assembly according to claim 1, wherein the distal core wire comprises a distal straight portion extending from the coil portion to the distal end of the distal core wire, and the distal straight portion maintains a length and a diameter in the first configuration and the second configuration.

6. The stent pusher assembly according to claim 1, wherein the transition of the distal core wire from the first configuration to the second configuration reduces the length of the distal core wire by at least 30%.

7. The stent pusher assembly according to claim 2, wherein, When the distal core wire is in the second configuration, the length of the coil portion is equal to the length of the second stent.

8. The stent pusher assembly according to claim 2, wherein the second diameter is configured to allow the stent pusher to engage the stent in the expanded stent configuration so as to translate the stent within a blood vessel.

9. The stent pusher assembly according to claim 2, wherein the second diameter is configured to allow the distal core wire to engage the stent in the expanded stent configuration so as to juxtapose the stent against the blood vessel wall.

10. The stent pusher assembly according to claim 2, wherein the shortening rate of the distal core wire is equal to the shortening rate of the stent.

11. The stent pusher assembly according to claim 1, wherein the second diameter is at least three times the first diameter.

12. The stent pusher assembly according to claim 2, further comprising a re-sheathing ring carried by the distal core wire distal to the pusher ring, the re-sheathing ring being configured to engage the stent when the stent is positioned within the lumen of the catheter, such that the re-sheathing ring is configured to apply a proximally directed force to the stent in response to the proximal core wire being retracted proximally.

13. The stent pusher assembly according to claim 2, wherein the stent comprises a plurality of braided filaments.

14. The stent pusher assembly according to claim 1, wherein the pusher ring comprises a proximally facing surface facing the proximal core wire, a distally facing surface facing the distal core wire, and a tubular sidewall extending therebetween, the pusher ring defining a radial dimension greater than the first diameter of the distal core wire and less than the second diameter, and the distally facing surface of the pusher ring is configured to contact the proximal end portion of the stent.

15. A stent pusher, comprising: a distal core wire configured to receive a tubular medical device thereon; and a pusher member carried by the distal core wire, the pusher member being configured to contact the proximal end portion of the tubular medical device. The distal core wire is configured to transition between a small-profile configuration and a deployed configuration. In the small-profile configuration, the distal core wire forms a first structure that is substantially straight and has a first length. In the deployed configuration, the distal core wire forms a second structure that defines a plurality of coils and has a second length that is less than the first length.

16. The stent pusher according to claim 15, wherein when the distal core wire is in the small-profile configuration, the first structure has a first radial dimension, and when the distal core wire is in the deployed configuration, the second structure has a second radial dimension, and the second radial dimension is greater than the first radial dimension.

17. The stent pusher according to claim 15, wherein the distal core wire is configured to transition between the small-profile configuration and the deployed configuration in response to the temperature of the distal core wire rising above the Af temperature of the distal core wire.

18. The stent pusher according to claim 15, further comprising a proximal core wire extending proximally from the pusher member.

19. The stent pusher according to claim 18, wherein the proximal core wire is stiffer than the distal core wire.

20. A method of delivering a stent to a treatment site within the lumen of a patient's blood vessel using a stent pusher assembly, the stent pusher assembly including a catheter, a stent pusher positioned within the lumen of the catheter and including a proximal core wire, a distal core wire, and a pusher ring carried by the distal core wire, and a stent positioned within the lumen of the catheter above the distal core wire and distal to the pusher ring, the method comprising: Positioning a distal end portion of the catheter within the blood vessel lumen at or near the treatment site; and Engaging the stent with the pusher ring to translate the stent and the distal core wire out of the lumen of the catheter to allow the stent to transition from a compressed stent configuration to a deployed stent configuration and to allow the distal core wire to transition from a first configuration to a second configuration. In the first configuration, the distal core wire forms a first structure that is substantially straight without coils and defines a first length and a first diameter. In the second configuration, the distal core wire forms a second structure that includes a coil portion defining a plurality of coils such that the second structure defines a second length that is less than the first length and a second diameter that is greater than the first diameter.

21. The method according to claim 20, further comprising engaging the luminal surface of the stent with the distal core wire such that the stent moves closer to the wall of the blood vessel.

22. The method according to claim 21, wherein engaging the luminal surface of the stent with the distal core wire includes pushing and / or pulling a proximal end of the proximal core wire.

23. The method according to claim 20, wherein the stent is translated out of the lumen of the catheter such that the transformation of the stent from a compressed stent configuration to a deployed stent configuration causes the stent to transform from a first stent length to a second stent length that is less than the first stent length, and wherein the shortening rate of the stent is equal to the shortening rate of the distal core wire.

24. The method according to claim 20, wherein the distal core wire is configured to transform from the first configuration to the second configuration in response to the temperature of the distal core wire rising above about 36 °C.

25. The method according to claim 20, wherein when the stent and the distal core wire are translated out of the lumen of the catheter, the position of the distal end of the distal core wire within the blood vessel lumen remains substantially constant.

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