Composite detachment element for implant delivery

Abstract

A connector for detachably coupling an implant to a delivery wire, includes: a structure having a distal portion coupled to a proximal end of the implant, and a proximal portion coupled to a distal end of the delivery wire; wherein the structure comprises a first element formed by a first material, and second elements formed by a second material, wherein the second elements are distributed in the first element.

Description

Docket: No. 24-011 PCTCOMPOSITE DETACHMENT ELEMENT FOR IMPLANT DELIVERYFIELD

[0001] The present disclosure relates generally to medical devices and medical procedures, such as intravascular procedures and any procedures involving delivery of implants, and more particularly, to connectors for detachably coupling implants with delivery wires.BACKGROUND

[0002] Implants, such as stents, flow diverters, vaso-occlusive devices, aneurysm neck-bridging devices, etc., have been utilized to treat patients.

[0003] Stents are small, expandable structures that are inserted into the body of the patient during a minimally invasive procedure. A stent's function is to hold open a narrowed or weak passage in the body, such as a blood vessel or airway. Stents and flow diverters have been implanted in patients to treat various medical conditions. Stents may be used to treat, or help support a treatment of, a variety of diseases and medical conditions, including but not limited to: heart diseases, aneurysms, lung diseases, peripheral arterial diseases, and carotid artery diseases. In one application of treatment of heart diseases, stents may be used to treat coronary artery disease, which occurs when plaque builds up in the arteries that supply the heart with oxygenated blood. Stents may also treat angina, a type of chest pain caused by blocked arteries.

[0004] Vaso-occlusive devices and neck-bridging devices may be utilized in treatment of aneurysms. Vaso-occlusive device may be inserted into an aneurysm to at least partly fill a volume of the aneurysm for treatment of the aneurysm. A neck-bridging device may be placed in the blood vessel extending across a neck of an aneurysm to support the treatment of the aneurysm.

[0005] In some cases, an implant may be coupled to a delivery wire for delivery of the implant. Specifically, the implant may be coupled to the delivery wire via a connector (detachment element). During a procedure, the implant and the delivery wire inside a delivery catheter may be advanced distally relative to the delivery catheter, until the implant exits out of a distal end of the delivery catheter. Then the connector is electrolytically dissolved to thereby detach the implant from the delivery wire.Docket: No. 24-011 PCT

[0006] Electrolytic dissolution approach has been used for detaching implants from delivery wires using stainless steel as the detachment zone material. To achieve good detachment performance, an electrolyte (e.g. blood) with sufficient ion conductivity needs to be present. In the case of the delivery of vaso-occlusive devices into an aneurysm, detachment may progress without issue for the initial few vaso-occlusive devices during a procedure. However, it may become more challenging when more vaso-occlusive devices are introduced into the aneurysm to increase packing density. This is due to a decrease in ion conductivity brought about by decrease of blood (electrolyte) as the aneurysm is being packed, and due to accumulation of detachment gas bubbles formed during the electrolytic dissolution process. This creates a high impedance condition where the electrolytic dissolution process can slow down or even stop. In such challenging electrolytic detachment scenario, the vaso-occlusive device cannot be detached predictably, and may require multiple application of detachment energy (e.g., current) in order to detach the implant from the delivery wire. In some cases, the physician may need to pull out the deliver wire to confirm detachment of the implant.SUMMARY

[0007] A connector for detachably coupling an implant to a delivery wire, includes: a structure having a distal portion coupled to a proximal end of the implant, and a proximal portion coupled to a distal end of the delivery wire; wherein the structure comprises a first element formed by a first material, and second elements formed by a second material, wherein the second elements are distributed in the first element.

[0008] Optionally, the second elements comprise elongated fibers surrounded by the first material of the first element.

[0009] Optionally, each of the fibers is parallel to, or forms an acute angle with, a longitudinal axis of the structure.

[0010] Optionally, the elongated fibers comprise at least seven fibers.

[0011] Optionally, the structure is electrolytically dissolvable to permit the implant and the delivery wire to separate from each other.

[0012] Optionally, the first material and the second material are configured to enable galvanic corrosion.

[0013] Optionally, the first material and the second material have different respective negative electrochemical corrosion potentials.Docket: No. 24-011 PCT

[0014] Optionally, the first material has more negative electrochemical corrosion potential than the second material.

[0015] Optionally, a difference between the negative electrochemical corrosion potentials is larger than zero.

[0016] Optionally, a difference between the negative electrochemical corrosion potentials is larger than 10 mV.

[0017] Optionally, a difference between the negative electrochemical corrosion potentials is larger than 100 mV.

[0018] Optionally, the first element is configured to dissolve first before at least one of the second elements is dissolved.

[0019] Optionally, the second elements and the first element are configured to form galvanic corrosion cells during an electrolytic dissolution process.

[0020] Optionally, the first element is a cathode, and the second elements are anodes.

[0021] Optionally, the first element is an anode, and the second elements are cathodes.

[0022] Optionally, a volume of the second elements is larger than 5% of the total volume of the connector, but less than 100% of the total volume of the connector.

[0023] Optionally, a volume of the second elements is larger than 20% of the total volume of the connector, but less than 100% of the total volume of the connector.

[0024] Optionally, a volume of the second elements is larger than 30% of the total volume of the connector, but less than 100% of the total volume of the connector.

[0025] Optionally, the first material comprises Zn, Zn alloys, Mg, Mg alloys, Nitinol, FeMn, FeMnN, Stainless steel, or any combination of two or more of the foregoing.

[0026] Optionally, the second material has a Young’s modulus that is larger than 30 Msi.

[0027] Optionally, the second material has a Young’s modulus that is larger than 40 Msi.

[0028] Optionally, the second material comprises Mo, Mo alloys, W, W alloys, Mo-Re alloys, Mo-W alloys, Mo-Rh alloys, Mo-Ta alloys, Mo-Pt alloys, Mo-Nb alloys, Mo-lr alloys, Ni-based alloys, Co-based alloys, Fe-based alloys, or any combination of two or more of the foregoing.

[0029] Optionally, the structure has a Young’s modulus larger than 25 Msi.Docket: No. 24-011 PCT

[0030] Optionally, the structure has a tensile strength larger than 150 ksi.

[0031] Optionally, the structure has a cross-sectional width less than 0.01”.

[0032] Optionally, the structure has a cross-sectional width less than 0.005”.

[0033] Optionally, the structure has a cross-sectional width that is 0.00175” + / - 0.0001”.

[0034] Optionally, the structure has a length that is less than 0.01”.

[0035] Optionally, the structure has a length that is less

[0036] than 0.005”.

[0037] Optionally, the structure has a length that is 0.002” + / - 0.001”.

[0038] Other and further aspects and features will be evident from reading the following detailed description.DESCRIPTION OF THE DRAWINGS

[0039] The drawings illustrate the design and utility of embodiments, in which similar elements are referred to by common reference numerals. In order to better appreciate how the above-recited and other advantages and objects are obtained, a more particular description of the embodiments will be rendered, which are illustrated in the accompanying drawings. These drawings depict only exemplary embodiments and are not therefore to be considered limiting in the scope of the claims.

[0040] FIG. 1 is a side view of a medical system, particularly showing an implant within a delivery catheter in a delivery configuration;

[0041] FIG. 2 is a side view of the medical system, particularly showing the implant delivered out of the delivery catheter in a deployed configuration;

[0042] FIG. 3 shows an implant detachably coupled to a delivery wire via a connector;

[0043] FIG. 4 illustrates components of the connector of FIG. 3;

[0044] FIG. 5 shows a cross-section of the connector of FIG. 3;

[0045] FIG. 6 shows an example of materials utilized to make the connector of FIG. 3;

[0046] FIG. 7 shows an exemplary implementation of the connector of FIG. 3; and

[0047] FIG. 8 is a chart comparing detachment times for different connectors made from different materials.Docket: No. 24-011 PCTDETAILED DESCRIPTION

[0048] Various embodiments are described hereinafter with reference to the figures. It should be noted that elements of similar structures or functions are represented by the same reference numerals throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the embodiments. They are not intended as an exhaustive description of the invention or as a limitation on the scope of the invention. In addition, an illustrated embodiment needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated, or if not so explicitly described.

[0049] Referring to FIGS. 1-2, a treatment system 10 in accordance with the present disclosure will now be described. The treatment system 10 comprises a delivery catheter 12 and an implant 14 slidably disposed within the delivery catheter 12. The implant 14 comprises a mesh body 16 and a pusher member 18 to which the mesh body 16 is detachably coupled.

[0050] The delivery catheter 12 has a tubular configuration, and can, e.g., take the form of a micro-catheter or the like. The delivery catheter 12 comprises an elongate sheath body 22 having a proximal portion 24 and a distal portion 26, and a lumen 28 (shown in phantom) extending through the sheath body 22 between the proximal portion 24 and the distal portion 26. The proximal portion 24 of the sheath body 22 remains outside of the patient and accessible to the operator when the treatment system 10 is in use, while the distal portion 26 of the sheath body 22 is sized and dimensioned to reach remote locations of a vasculature and is configured to deliver the implant 14 to a target location in a blood vessel. The delivery catheter 12 may have at least one port 30 in fluid communication with the lumen 28 of the delivery catheter 12, which is used to introduce fluids into the sheath body 22. The implant 14 is disposed in the lumen 28 of the delivery catheter 12, as better appreciated in FIG. 1.

[0051] The delivery catheter 12 may include one or more, or a plurality of regions along its length having different configurations and / or characteristics. For example, the distal portion 26 of the sheath body 22 may have an outer diameter less than the outer diameter of the proximal portion 24 of the sheath body 22 to reduce the profile of the distal portion 26 and facilitate navigation in tortuous vasculature. Furthermore,Docket: No. 24-011 PCTthe distal portion 26 may be more flexible than the proximal portion 24. Generally, the proximal portion 24 may be formed from material that is stiffer than the distal portion 26 of the sheath body 22, so that the proximal portion 24 has sufficient pushability to advance through the patient's vascular system, while the distal portion 26 may be formed of a more flexible material so that the distal portion 26 may remain flexible and track more easily over a guidewire to access remote locations in tortuous regions of the vasculature. The sheath body 22 may be composed of suitable polymeric materials, metals and / or alloys, such as polyethylene, stainless steel or other suitable biocompatible materials or combinations thereof. In some instances, the proximal portion 24 may include a reinforcement layer, such a braided layer or coiled layer to enhance the pushability of the sheath body 22. The sheath body 22 may include a transition region between the proximal portion 24 and the distal portion 26.

[0052] In general, the implant 14 may be inserted into the patient by inserting (e.g., minimally invasively) the treatment system 10 into the patient's vasculature to reach a target site (e.g., blood vessel, aneurysm, etc.). The treatment system 10 may be used in an “over-the-wire” configuration, wherein the delivery catheter 12 is introduced into the patient over a guidewire that has been previously introduced, and the delivery catheter 12 extends over the entire length of the guidewire (not shown). Alternatively, the treatment system 10 may be used in a “rapid-exchange” configuration, where a guidewire extends through only a distal portion of the treatment system 10 from a guidewire port (not shown). In other alternative embodiments, the system 10 may be introduced into the patient after a guidewire had been withdrawn leaving a sheath or access catheter distal portion at the target site for the treatment system 10 to navigate through the vasculature of the patient within the sheath or access catheter.

[0053] At the target site inside the patient, the implant 14 may be pushed distally out of the delivery catheter 12 residing in the parent vessel and into the target site via the pusher member 18. After being delivered from the delivery catheter 12, the implant 14 may self-expand into a pre-set expanded configuration. Once the implant 14 is delivered to the target sight, the delivery catheter 12 may then be removed from the patient.

[0054] The pusher member 18 may be a coil, wire, tendon, or the like, having a sufficient columnar strength to permit pushing of the implant 14 into the targetDocket: No. 24-011 PCTlocation. The pusher member 18 has a proximal portion 32 that extends proximal from the proximal portion 24 of the delivery catheter 12 and a distal portion 34 with a distal end 20 to which the implant 14 is coupled. The pusher member 18 may be made of a conventional guidewire, torqueable cable tube, or a hypotube. In either case, there are numerous materials that can be used for the pusher member 18 to achieve the desired properties that are commonly associated with medical devices. Some examples can include metals, metal alloys, polymers, metal-polymer composites, and the like, or any other suitable material. For example, the pusher member 18 may include nickel-titanium alloy, stainless steel, a composite of nickeltitanium alloy and stainless steel. In some cases, the pusher member 18 can be made of the same material along its length, or in some embodiments, can include portions or sections made of different materials. In some embodiments, the material used to construct the pusher member 18 is chosen to impart varying flexibility and stiffness characteristics to different portions of the pusher member 18. For example, the proximal region 32 and the distal portion 34 of the pusher member 18 may be formed of different materials, for example materials having different moduli of elasticity, resulting in a difference in flexibility. For example, the proximal portion 32 can be formed of stainless steel, and the distal portion 34 can be formed of a nickeltitanium alloy. However, any suitable material or combination of material may be used for the pusher member 18, as desired.

[0055] The implant 14 includes a body 40, and is sized for implantation at a target location, which can take any geometry or shape in its cross-section. The body 40 of the implant may include a mesh (e.g., braided structure) and / or a coil element. In the illustrated example, the implant 14 has a proximal end 36 and a distal end 38. The implant 14 has a compact delivery configuration when radially restrained within the delivery catheter 12 and is biased to radially expand outward into a deployed configuration when released from the delivery catheter 12 into a target location (e.g., blood vessel). The cross-sectional dimension of the implant 14, in its expanded deployed configuration, may, e.g., be greater than 1.1 times, or greater than 1.2 times, or greater than 1.5 times, or greater than 2 times, or greater than 3 times, or greater than 4 times, or greater than 5 times, or greater than 6 times, or greater than 7 times, or greater than 8 times, or greater than 9 times, or greater than 10 times, the cross-sectional dimension of the implant 14, in its compact delivery configuration.Docket: No. 24-011 PCT

[0056] FIG. 3 shows an implant 300 detachably coupled to a delivery wire 310 via a connector 320. The implant 300 may be the implant 14 of FIG. 1 , or may be any of other types of implants. By means of non-limiting examples, the implant 300 may be a stent, a flow diverter, a vaso-occlusive device, a framing device, a neck-bridging device, etc. The implant 300 may be non-biodegradable or biodegradable. The delivery wire 310 may be the pusher member 18 or at least a part of the pusher member 18 of FIG. 1. The connector 320 is configured for detachably coupling the implant 300 to the delivery wire 310. The connector 320 includes a structure 350 having a distal portion 354 coupled to a proximal end 302 of the implant 300, and a proximal portion 352 coupled to a distal end 360 of the delivery wire 310.

[0057] FIG. 4 illustrates components of the connector 320 of FIG. 3. FIG. 5 shows a cross-section of the connector 320 of FIG. 3. As shown in these figures, the structure 350 comprises a first element 370 formed by a first material, and second elements 380 formed by a second material. The second elements 380 are distributed in the first element 370. The second elements 380 are encased inside the first element 370. In particular, each of the second elements 380 is surrounded by the first material of the first element 370, and some of the first material of the first element 370 circumferentially surrounds the group of the second elements 380. In the illustrated examples, the second elements 380 comprise elongated fibers surrounded by the first material of the first element 370. Each of the fibers is parallel to, or forms an acute angle with, a longitudinal axis of the structure 350 (or of the delivery wire 310). In the illustrated example, the elongated fibers comprise at least seven fibers. In other cases, the connector 320 may include more than seven fibers, or fewer than seven fibers (e.g., 1 fiber, 2 fibers, 3 fibers, 4 fibers, 5 fibers, or 6 fibers).

[0058] Also, in the illustrated example, the second elements 380 extend through an entire length of the connector 320 (e.g., they are at least the same length of the connector 320 or of the first element 370). In other cases, the second elements 380 may be shorter or longer than the first element 370.

[0059] In some cases, a volume of all of the second elements 380 may be larger than 5% of the total volume of the structure 350 or connector 320, but less than 100% of the total volume of the structure 350 or connector 320. In other cases, a volume of the second elements 380 may be larger than 20% of the total volume of the structure 350 or connector 320, but less than 100% of the total volume of theDocket: No. 24-011 PCTstructure 350 or connector 320. In further cases, a volume of the second elements 380 may be larger than 30% of a volume of the total volume of the structure 350 or connector 320, but less than 100% of the total volume of the structure 350 or connector 320.

[0060] The structure 350 of the connector 320 is electrolytically dissolvable to permit the implant 300 and the delivery wire 310 to separate from each other. In the illustrated example, the first material and the second material are configured to enable galvanic corrosion, i.e., the second elements 380 of the connector 320 and the first element 370 of the connector 320 are configured to form galvanic corrosion cells during an electrolytic dissolution process. In the galvanic corrosion cell, an electrochemical process occurs where two dissimilar metals come into contact with each other in the presence of an electrolyte, causing one metal to corrode at an accelerated rate while the other is protected from corrosion, essentially creating a mini "battery". The more active metal acts as the anode (corroding) and the less active metal acts as the cathode (protected).

[0061] The first material of the first element 370 and the second material of the second elements 380 have different respective negative electrochemical corrosion potentials. For example, the first material of the first element 370 may have a more negative electrochemical corrosion potential than the second material of the second elements 380. In some cases, a difference between the negative electrochemical corrosion potentials may be larger than zero, larger than 10 mV, or larger than 100 mV. In other cases, the second material may have a more negative electrochemical corrosion potential than the first material.

[0062] In the illustrated example, each of the second elements 380 have a circular cross-section, thereby providing a high contact surface area with the first element 370 to enhance formation of galvanic cell. In other cases, each second elements 380 may have any of other cross-sectional shapes, such as an elliptical shape, a square shape, a rectangular shape, a pentagonal shape, a hexagonal shape, etc.

[0063] In some cases, the first element 370 of the connector 320 is a cathode, and the second elements 380 of the connector 350 are anodes. In other cases, the first element 370 of the connector 320 is an anode, and the second elements 380 of the connector 320 are cathodes.Docket: No. 24-011 PCT

[0064] The connector 320 is configured to undergo electrolytic dissolution with galvanic corrosion to achieve detachment of the implant from the delivery wire. Such detachment is faster and is more reliable than conventional technique using connector with homogeneous material. In some cases, the electrolytic dissolution may occur simultaneously with galvanic corrosion (from galvanic corrosion cells formed between the first and second elements 370, 380 of the connector 320). In some cases, the first element 370 is configured to start to dissolve first before at least one of the second elements 380 starts to dissolve, thereby exposing the second elements 380. In particular, a part of the first element 370 at the peripheral part of the connector 320 may dissolve (corrode) first due to electrolytic dissolution. After the part of the first element 370 at the peripheral part of the connector 320 is dissolved, the second elements 380 are exposed, and start to corrode also due to electrolytic dissolution. At the same time, the multiple galvanic cells form between the first element 370 and second elements 380 due to a difference in negative electrochemical corrosion potentials between them. This leads to galvanic corrosion to occur simultaneously with the electrolytic dissolution. Thus, the galvanic corrosion further accelerates the dissolution process.

[0065] Optionally, the first element 370 and the second elements 380 may be configured to have certain respective mechanical strengths and / or stiffnesses.

[0066] For example, in some cases, the second material of the second elements 380 of the connector 320 may have a Young’s modulus that is larger than 30 Msi. In other cases, the second material of the second elements 380 of the connector 320 may have a Young’s modulus that is larger than 40 Msi. In further cases the second material of the second elements 380 of the connector 320 may have a Young’s modulus less than 30 Msi or less than 40 Msi.

[0067] By means of non-limiting examples, the first material of the first element 370 of the connector 320 may include Zn, Zn alloys, Mg, Mg alloys, Nitinol, FeMn, FeMnN, stainless steel, or any combination of two or more of the foregoing.

[0068] By means of non-limiting examples, the second material of the second elements 380 of the connector 320 may include Mo, Mo alloys, W, W alloys, Mo-Re alloys, Mo-W alloys, Mo-Rh alloys, Mo-Ta alloys, Mo-Pt alloys, Mo-Nb alloys, Mo-lr alloys, Ni-based alloys, Co-based alloys, Fe-based alloys, or any combination of two or more of the foregoing.Docket: No. 24-011 PCT

[0069] In some cases, the second material of the second elements 380 of the connector 320 may have a higher Young’s modulus compared to the first material of the first element 370. This allows the second elements 380 to act as reinforcement for the connector 320. The second elements 380 may be configured to have higher axial stiffness than the first element 370, thereby enabling the transmission of more axial force compared to the first element 370. The first element 370 may be configured to provide structural support for the second elements 380, such as providing lateral support to prevent buckling and kink resistance.

[0070] In other cases, the first material of the first element 370 may have a higher Young’s modulus compared to the second material of the second elements 380. In such cases, the first element 370 is configured to transmit more axial force compared to the second elements 380.

[0071] Also, optionally, the first element 370 and / or the second elements 380 may be configured to have lower magnetic susceptibility than stainless steel that is currently used to make the connector 320, so that the resulting detachment remnant from the connector 320 (detachment element) has less contribution to MR artifact.

[0072] Although the second elements 380 have been described as extending through an entire length (longitudinal length) of the connector 320, in other cases, the second elements 380 may not extend through the entire length of the connector 320. For example, in other cases, the second elements 380 may be shorter than the length of the connector 320. In such cases, the second elements 380 are distributed in the first element 370, and one or more second elements 380 may be at different longitudinal positions with respect to another one or more second elements 380.

[0073] In some cases, the structure 350 of the connector 320 may have a Young’s modulus larger than 25 Msi. In other cases, the structure 350 of the connector 320 may have a Young’s modulus less than 25 Msi. Also, in some cases, the structure 350 of the connector 320 may have a tensile strength larger than 150 ksi. In other cases, the structure 350 of the connector 320 may have a tensile strength less than 150 ksi. Also, in some cases, the structure 350 of the connector 320 may achieve an elongation of 1 % or higher at a tensile load of 150 ksi. The 1 % feature is advantageous because it ensures proper manufacturability of the connector 320 without breaking.

[0074] In some cases, the structure 350 of the connector 320 may have a cross-sectional width less than 0.01”, or less than 0.005” (e.g., 0.00175” + / - 0.0001”). InDocket: No. 24-011 PCTother cases, the structure 350 of the connector 320 may have a cross-sectional width larger than 0.01”.

[0075] Also, in some cases, the structure 350 of the connector 320 may have a length measured in a direction that is parallel to the longitudinal axis of the connector 320 (or of the delivery wire 310), wherein the length is less than 0.01 ”, or less than 0.005” (e.g., 0.002” + / - 0.001”). In other cases, the length may be larger than 0.01”.

[0076] The connector 320 made from composite material is more advantageous than a detach element made from a homogeneous material, such as stainless steel. This is because the connector 320 made from composite material provides shorter detachment time (detachment of implant from delivery wire), and more predictable detachment performance (e.g., reliable detachment and / or consistent detachment time, etc.). This is at least partly due to the galvanic corrosion cells formed between the first element 370 and the second elements 380 of the connector 320 during the electrolytic dissolution process, which accelerates the dissolution of the connector 320. Also, the combination of electrolytic dissolution mechanism and multiple galvanic corrosion cells provided by the connector 320 ensures that the connector 320 will dissolve continuously without disruption even in challenging conditions. Other connectors (detach elements) made from a homogeneous material provide detachment that is not predictable in challenge conditions (e.g., high impedance). Sometimes, the user may need to pull out the delivery wire in order to confirm that the implant has been detached from the delivery wire. The connector 320 described herein provides faster detachment time, and more predictable detachment performance even in challenging conditions. Also, the connector 320 described herein optionally allows the delivery wire to be kink resistance, and to be able to transmit higher pushing force. This in turn allows a longer implant to be delivered.

[0077] FIG. 6 shows an example of materials utilized to make the connector 320 of FIG. 3. In the example shown, the first element 370 of the connector 320 is made from FeMnN, and the second elements 380 of the connector 320 is made from Mo. In other cases, the first element 370 of the connector 320 may be made from other materials, such as any of the materials disclosed herein. Similarly, in other cases, the second elements 380 of the connector 320 may be made from other materials, such as any of the materials disclosed herein.

[0078] FIG. 7 shows an exemplary implementation of the connector 320 of FIG. 3.The structure 350 with the first element 370 and the second elements 380 isDocket: No. 24-011 PCTimplemented using a wire 702. A first portion of the wire 702 is covered with a first tube 710 for insulation, and a second portion of the wire 702 is also covered with a second tube 712 for insulation. The two tubes 710, 712 are separated by a distance for forming the detachment zone (length) of the connector 320. Thus, the structure 350 of the connector 320 may be a part of a wire (e.g., the wire 702). After the implant 300 is detached from the delivery wire 310, the first portion of the wire 702 distal to the connector 320 may remain coupled with the implant 300, and the second portion of the wire 702 proximal to the connector 320 may remain coupled with the delivery wire 310. A third portion (between the first and second portions) of the wire 702 implementing the detachment zone of the connector 310 will be dissolved and / or corroded during the detachment process.

[0079] Accordingly, the term “coupled” may refer to a mechanical attachment, such as an attachment implemented using a coupler, or may refer to an integral attachment between two items that are integrally formed together. For example, the coupling of the proximal portion of the structure 350 of the connector 320 to the distal end of the delivery wire 310 may refer to an integral attachment in which the structure 350 is integrally formed with the delivery wire 310 (e.g., the structure 350 is integral with the wire implementing the delivery wire 310), or it may refer to a connection between the structure 350 and the distal end of the delivery 310 implemented using a separate coupler, such as a weld, a solder, etc. Similarly, the coupling of the distal portion of the structure 350 of the connector 320 to the proximal end of the implant 300 may refer to an integral attachment in which the structure 350 is integrally formed with a part of the implant 300 (e.g., the structure 350 is integral with a wire portion that will remain with the implant 300 after the connector 320 is dissolved and / or corroded), or it may refer to a connection between the structure 350 and the proximal end of the implant 300 implemented using a separate coupler, such as a weld, a solder, a hook, an anchor, etc.

[0080] It should be noted that the connector 320 is not limited by the examples described herein, and that the connector 320 may be implemented using other techniques.

[0081] FIG. 8 is a chart showing results of the testing, in which detachment times for different connectors made from different materials are compared. As shown in the figure, a connector with a diameter of 0.00175” made from stainless-steel (SS) provides a detachment time that is higher than 2.5 seconds (average time for aDocket: No. 24-011 PCTsample size of 10). In other words, it takes more than 2.5 seconds for the connector made homogeneously from stainless-steel to dissolve in order to detach the implant from the delivery wire. On the other hand, a connector with the same diameter (0.00175”) made from a composite structure (e.g., like the structure 350 of the connector 320 shown in FIGS. 3-5) provides a faster detachment time of 1.8 seconds (average time for a sample size of 10). The composite structure in the testing is made from FeMnN I Mo (like that shown in FIG. 6) - i.e., it has FeMnN as the first material for the first element 370 of the connector 320, and Mo (40% by volume) as the second material for the second elements 380. The electrochemical corrosion potential for the first and second materials is: -619 mV for FeMnN, and -280 mV for Mo. The connector 320 has a cross-sectional dimension (diameter) of 0.00175”, and a detachment zone (length) of 0.002”. In other cases, the composite structure of the connector 320 may be made from any of the materials disclosed herein. As shown in the results of FIG. 8, the connector with the composite structure provides faster detachment time than the connector made from a single material.

[0082] Testing has also been done to compare detachment reliability in challenging condition (high impedance condition) between the connector made from stainless-steel, and the composite connector made from FeMnN I Mo (like that shown in FIG. 6). A sample size of 5 was utilized for each connector. In the testing, diluted saline (contains 0.0065% salt) was used to simulate high impedance condition. In such condition, none of the 5 connectors made from stainless-steel was detached from the delivery wires. On the other hand, under such condition, all 5 connectors with the composite structure were successfully detached. Thus, the connector with the composite structure provides more reliable detachment performance than the connector made from a single material.

[0083] A method of use will now be described with reference to the system of FIG. 3. The system of FIG. 3 may be a part of a treatment system (e.g., treatment system 10) that includes a delivery catheter. During a procedure, the delivery catheter containing the implant 300 and the delivery wire 310 is inserted into a patient. The implant 300 coupled to the delivery wire 310 via the connector 320 is then advanced distally inside the delivery catheter. Such may be accomplished by advancing the delivery wire 310 distally relative to the delivery catheter, thereby pushing the implant 300 distally via the delivery wire 310. The advancement is performed until the implant 300 is delivered out of a lumen at the distal end of theDocket: No. 24-011 PCTdelivery catheter and into a target site inside the patient. The target site may be a blood vessel, an aneurysm, etc. After being delivered from the delivery catheter, the implant 300 may self-expand into a pre-set expanded configuration. After the implant 300 is delivered to the target sight, the implant 300 is then detached from the delivery wire 310, thereby allowing the delivery catheter to be removed from the patient.

[0084] The detachment of the implant 300 from the delivery wire 310 is achieved by a dissolution of the connector 320 in an electrolytic dissolution process. During such process, a current is delivered through the connector 320 to cause the connector 320 to dissolve. In one implementation, a power supply may be coupled to a proximal portion of the delivery wire 310. The power supply may also be coupled to a proximal portion of a handle of the delivery catheter or to the patient. The power supply provides the current to the delivery wire. The current travels to the connector 320 wherein the detachment zone is located, and may flow to the patient, and subsequently to a ground or to the power supply. Alternatively, the current may travel to the connector 320, and may then travel to a return path via the delivery catheter (e.g., catheter shaft) and / or another component extending near the detachment zone. The power supply may be a direct current power supply, an alternating current power supply, or may be switchable between a direct current and an alternating current.

[0085] The current from the power supply initiates an electrolytic process in a fluid medium such as a bloodstream, which may be used as an electrolyte. Because the connector 320 includes the structure 350 (composite structure) having the first and second elements 370, 380 with different negative electrochemical corrosion potentials, galvanic corrosion cells will be formed between the first element 370 and the second elements 380 during the electrolytic dissolution process. In some cases, the first material of the first element 370 has more negative electrochemical corrosion potential than the second material of the second elements 380. Thus, the first element 370 is the anode that begins dissolving first to expose the second elements 380 (acting as the cathode in the galvanic corrosion cell). In particular, a part of the first element 370 at the peripheral part of the connector 320 may dissolve (corrode) first due to electrolytic dissolution. After the part of the first element 370 at the peripheral part of the connector 320 is dissolved, the second elements 380 are exposed, and start to corrode also due to electrolytic dissolution. At the same time,Docket: No. 24-011 PCTthe multiple galvanic cells form between the first element 370 and second elements due to a difference in negative electrochemical corrosion potentials between them. This leads to galvanic corrosion to occur simultaneously with the electrolytic dissolution. Thus, both the second elements 380 and the remaining part of the first element 370 will both corrode quickly after the second elements 380 are exposed to the electrolytic dissolution. Accordingly, the galvanic corrosion accelerates the dissolution process.

[0086] In the case in which the implant 300 is a vaso-occlusive device being delivered into an aneurysm, the aneurysm may be partially occupied by previously delivered vaso-occlusive device(s), or by the current vaso-occlusive device. In such case, there may be a decrease in ion conductivity brought about by decrease of blood (electrolyte) as the aneurysm is being packed. This creates a high impedance condition where the electrolytic dissolution process may slow down or even stop when conventional connector is used. However, because the connector 320 includes the composite structure 350 with the first and second elements 370, 380, the connector 320 may be dissolved quickly and reliably (due to the galvanic corrosion cells formed by the first and second elements 370, 380) despite the challenging condition. Accordingly, the physician does not need to pull out the delivery wire to confirm detachment of the implant.

[0087] In some cases, the treatment system may be used in an “over-the-wire” configuration, wherein the delivery catheter is introduced into the patient over a guidewire that has been previously introduced, and the delivery catheter extends over the length of the guidewire (not shown). Alternatively, the treatment system may be used in a “rapid-exchange” configuration, where a guidewire extends through only a distal portion of the treatment system from a guidewire port (not shown). In other alternative embodiments, the system may be introduced into the patient after a guidewire had been withdrawn leaving a sheath or access catheter at the target site for the treatment system 10 to navigate through the vasculature of the patient within the sheath or access catheter.

[0088] Although particular embodiments have been shown and described, it will be understood that it is not intended to limit the claimed inventions to the preferred embodiments, and it will be obvious to those skilled in the art that various changes and modifications may be made without department from the spirit and scope of the claimed inventions. The specification and drawings are, accordingly, to be regardedDocket: No. 24-011 PCTin an illustrative rather than restrictive sense. The claimed inventions are intended to cover alternatives, modifications, and equivalents.

Claims

Docket: No. 24-011 PCTCLAIMS1. A connector for detachably coupling an implant to a delivery wire, comprising:a structure having a distal portion coupled to a proximal end of the implant, and a proximal portion coupled to a distal end of the delivery wire;wherein the structure comprises a first element formed by a first material, and second elements formed by a second material, wherein the second elements are distributed in the first element.

2. The connector of claim 1 , wherein the second elements comprise elongated fibers surrounded by the first material of the first element.

3. The connector of claim 2, wherein each of the fibers is parallel to, or forms an acute angle with, a longitudinal axis of the structure.

4. The connector of claim 2, wherein the elongated fibers comprise at least seven fibers.

5. The connector of claim 1 , wherein the structure is electrolytically dissolvable to permit the implant and the delivery wire to separate from each other.

6. The connector of claim 1 , wherein the first material and the second material are configured to enable galvanic corrosion.

7. The connector of claim 1 , wherein the first material and the second material have different respective negative electrochemical corrosion potentials.

8. The connector of claim 7, wherein the first material has more negative electrochemical corrosion potential than the second material.

9. The connector of claim 7, wherein a difference between the negative electrochemical corrosion potentials is larger than zero.Docket: No. 24-011 PCT10. The connector of claim 7, wherein a difference between the negative electrochemical corrosion potentials is larger than 10 mV.

11. The connector of claim 7, wherein a difference between the negative electrochemical corrosion potentials is larger than 100 mV.

12. The connector of claim 1 , wherein the first element is configured to begin dissolving first before at least one of the second elements is dissolved.

13. The connector of claim 1 , wherein the second elements and the first element are configured to form galvanic corrosion cells during an electrolytic dissolution process.

14. The connector of claim 1 , wherein the first element is a cathode, and the second elements are anodes.

15. The connector of claim 1 , wherein the first element is an anode, and the second elements are cathodes.

16. The connector of claim 1 , wherein a volume of the second elements is larger than 5% of a total volume of the connector, but less than 100% of the total volume of the connector.

17. The connector of claim 1 , wherein a volume of the second elements is larger than 20% of a total volume of the connector, but less than 100% of the total volume of the connector.

18. The connector of claim 1 , wherein a volume of the second elements is larger than 30% of a total volume of the connector, but less than 100% of the total volume of the connector.

19. The connector of claim 1 , wherein the first material comprises Zn, Zn alloys, Mg, Mg alloys, Nitinol, FeMn, FeMnN, Stainless steel, or any combination of two or more of the foregoing.Docket: No. 24-011 PCT20. The connector of claim 1 , wherein the second material has a Young’s modulus that is larger than 30 Msi.

21. The connector of claim 1 , wherein the second material has a Young’s modulus that is larger than 40 Msi.

22. The connector of claim 1 , wherein the second material comprises Mo, Mo alloys, W, W alloys, Mo-Re alloys, Mo-W alloys, Mo-Rh alloys, Mo-Ta alloys, Mo-Pt alloys, Mo-Nb alloys, Mo-lr alloys, Ni-based alloys, Co-based alloys, Fe-based alloys, or any combination of two or more of the foregoing.

23. The connector of claim 1 , wherein the structure has a Young’s modulus larger than 25 Msi.

24. The connector of claim 1 , wherein the structure has a tensile strength larger than 150 ksi.

25. The connector of claim 1 , wherein the structure has a cross-sectional width less than 0.01”.

26. The connector of claim 1 , wherein the structure has a cross-sectional width less than 0.005”.

27. The connector of claim 1 , wherein the structure has a cross-sectional width that is 0.00175” + / - 0.0001”.

28. The connector of claim 1 , wherein the structure has a length that is less than 0.01”.

29. The connector of claim 1 , wherein the structure has a length that is less than 0.005”.

30. The connector of claim 1 , wherein the structure has a length that is 0.002” + / -0.001”.

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