Patent ID: 12256939

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification.

All numeric values are herein assumed to be modified by the term “about,” whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In many instances, he terms “about” may include numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.

Various embodiments of the disclosed inventions are described hereinafter with reference to the figures. It should be noted that the figures are not drawn to scale and that elements of similar structures or functions are represented by like 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, which is defined only by the appended claims and their equivalents. In addition, an illustrated embodiment of the disclosed inventions needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment of the disclosed inventions is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated.

FIG.1illustrates a known vaso-occlusive device delivery system10. In the system10illustrated inFIG.1, the vaso-occlusive device is a vaso-occlusive coil300. The system10includes a number of subcomponents or sub-systems. These include a delivery catheter100, a pusher assembly200, a vaso-occlusive coil300, and a power supply400. The delivery catheter100includes a proximal end102, a distal end104, and a lumen106extending between the proximal and distal ends102,104. The lumen106of the delivery catheter100is sized to accommodate axial movement of the pusher assembly200and the vaso-occlusive coil300. Further, the lumen106is sized for the passage of a guidewire (not shown) which may optionally be used to properly guide the delivery catheter100to the appropriate delivery site.

The delivery catheter100may include a braided-shaft construction of stainless steel flat wire that is encapsulated or surrounded by a polymer coating. By way of non-limiting example, HYDROLENE® is a polymer coating that may be used to cover the exterior portion of the delivery catheter100. Of course, the system10is not limited to a particular construction or type of delivery catheter100and other constructions known to those skilled in the art may be used for the delivery catheter100. The inner lumen106may be advantageously coated with a lubricious coating such as PTFE to reduce frictional forces between the delivery catheter100and the respective pusher assembly200and vaso-occlusive coil300being moved axially within the lumen106. The delivery catheter100may include one or more optional marker bands108formed from a radiopaque material that can be used to identify the location of the delivery catheter100within the patient's vasculature system using imaging technology (e.g., fluoroscope imaging). The length of the delivery catheter100may vary depending on the particular application, but generally is around 150 cm in length. Of course, other lengths of the delivery catheter100may be used with the system10described herein.

The delivery catheter100may include a distal end104that is straight as illustrated inFIG.1. Alternatively, the distal end104may be pre-shaped into a specific geometry or orientation. For example, the distal end104may be shaped into a “C” shape, an “S” shape, a “J” shape, a 45° bend, a 90° bend. The size of the lumen106may vary depending on the size of the respective pusher assembly200and vaso-occlusive coil300, but generally the OD of the lumen106of the delivery catheter100(I.D. of delivery catheter100) is less than about 0.02 inches. The delivery catheter100is known to those skilled in the art as a microcatheter. While not illustrated inFIG.1, the delivery catheter100may be utilized with a separate guide catheter (not shown) that aids in guiding the delivery catheter100to the appropriate location within the patient's vasculature.

As illustrated inFIGS.1and3, the system10includes a pusher assembly200configured for axial movement within the lumen106of the delivery catheter100. The pusher assembly200generally includes a proximal end202and a distal end204. The pusher assembly200includes a pusher conduit214, which has a proximal tubular portion206and a distal coil portion208, and defines a pusher lumen212and a distal opening in communication with the pusher lumen212.

FIG.3illustrates a detailed longitudinal cross-sectional view of the junction250between the pusher assembly200and the vaso-occlusive coil300according to one embodiment of the disclosed inventions. Similar elements of this embodiment are identified with the same reference numbers as discussed above with respect toFIG.1. The pusher assembly200includes a proximal end202and a distal end204and measures between around 184 cm to around 186 cm in length. The proximal tubular portion206may be formed from, for example, a flexible stainless steel hypotube. The proximal tubular portion206may be formed from stainless steel hypotube having an OD of 0.01325 inches and inner diameter (ID) of 0.0075 inches. The length of the hypotube section may be between around 140 cm to around 150 cm, although other lengths may also be used.

A distal coil portion208is joined in end-to-end fashion to the distal face of the proximal tubular portion206. The joining may be accomplished using a weld or other bond. The distal coil portion208may have a length of around 39 cm to around 41 cm in length. The distal coil portion208may comprise a coil of 0.0025 inches×0.006 inches. The first dimension generally refers to the OD of the coil wire that forms the coil. The latter dimension generally refers to the internal mandrel used to wind the coil wire around to form the plurality of coil winds and is the nominal ID of the coil. One or more windings of the distal coil portion208may be formed from a radiopaque material, forming marker coils. For example, the distal coil portion208may include a segment of stainless steel coil (e.g., 3 cm in length), followed by a segment of platinum coil (which is radiopaque and also 3 mm in length), followed by a segment of stainless steel coil (e.g., 37 cm in length), and so on and so forth.

An outer sleeve232or jacket surrounds a portion of the proximal tubular portion206and a portion of the distal coil portion208of the pusher conduit214. The outer sleeve232covers the interface or joint formed between the proximal tubular portion206and the distal coil portion208. The outer sleeve232may have a length of around 50 cm to around 54 cm. The outer sleeve232may be formed from a polyether block amide plastic material (e.g., PEBAX7233lamination). The outer sleeve232may include a lamination of PEBAX and HYDROLENER that may be heat laminated to the pusher assembly200. The OD of the outer sleeve232may be less than 0.02 inches and advantageously less than 0.015 inches. In the embodiment depicted inFIG.3, the pusher conduit214forms a negative (i.e., return) conductor222(described below). Accordingly, the outer sleeve232is removed from the very distal end of the pusher conduit214, during manufacturing, to form an exposed negative electrical contact224. In other embodiments where the negative conductor222is a separate wire running through the pusher conduit224, the outer sleeve232may cover the entire pusher conduit214, and the negative electrical contact224may be a ring electrode disposed around the proximal tubular portion206of the pusher conduit214.

As shown inFIG.3, the system10also includes a proximal seal230attached to the interior surface of the distal coil portion208of the pusher conduit214in the pusher lumen212. The proximal seal230may be formed of an adhesive. A tubular member226is disposed in the proximal seal230and defines a tube lumen228. A positive conductor220is a wire that runs between the proximal and distal ends202,204of the pusher assembly200in the pusher lumen212and into the tube lumen228. The positive conductor220extends through the proximal seal230while the proximal seal230maintains a substantially fluid tight seal between regions proximal and distal of the proximal seal230.

The positive conductor220may be formed from an electrically conductive material, such as copper wire coated with polyimide, with an OD of around 0.00175 inches. The proximal end of the positive conductor220is electrically connected to a positive electrical contact216. As mentioned above, the pusher conduit214forms a negative conductor222, and a portion of the pusher conduit214at the proximal end202forms a negative electrical contact224. As shown inFIG.1, positive and negative electrical contacts216,224are located at the proximal end of the pusher assembly200. The positive electrical contact216may be formed from a metallic solder (e.g., gold). Both the positive and negative electrical contacts216,224may be configured to interface with corresponding electrical contacts (not shown) in the power supply400(described below). The positive conductors220may be coated with an insulative coating such as polyimide except where it connects to the positive electrical contact216.

A sacrificial link234electrically connects the positive and negative conductors220,222, and forms a circuit therewith. The sacrificial link234is an elongate body having proximal and distal ends236,238. The sacrificial link may be a strand/filament, a tube, or a ribbon. The sacrificial link234is partially disposed in the tube lumen228. The sacrificial link234is made from an electrically conductive material such as titanium, titanium alloy, nitinol, magnesium, magnesium alloy, various electrically conductive polymers, and combinations thereof. Electrically conductive polymers include polyacetylene, polypyrrole, polyaniline, poly(p-phenylene vinylene), poly(thiophene), poly(3,4-ethylenedioxythiophene), poly(p-phenylene sulfide), and various powder-filled or fiber-filled composite polymers., such as carbon filled polymers. Powder-filled composite polymers include graphite-filled polyolefins, graphite-filled polyesters, graphite-filled epoxies, graphite-filled silicones, silver-loaded epoxies, and silver-loaded silicones. Fiber-filled composite polymers include carbon fibers, stainless steel fibers, nickel fibers, or aluminum fibers dispersed in polyolefins, polyesters, epoxies, or silicones

When a current is applied through the sacrificial link234, resistance to current flows through the sacrificial link234generates heat that thermally disintegrates (i.e., decomposes) the sacrificial link234, breaking the electrical circuit. Resistance of the sacrificial link234is much higher than that of the positive conductor220and the conduit208. The disparity in resistance focuses heat generation focus at the sacrificial link234. While previously known heat actuated detachment systems utilize separate heating elements to melt attachment members, the system10depicted inFIG.3uses a conductive and resistive sacrificial link234to generate heat to thermally disintegrate itself. The distal coil portion208of the pusher assembly does not generate heat that affects the sacrificial link234, because to current applied through the circuit is relatively low.

The sacrificial link234also mechanically connects the vaso-occlusive coil300to the pusher assembly200. The vaso-occlusive coil300includes a proximal end302, a distal end304, and a lumen306extending there between. The vaso-occlusive coil300is made from a biocompatible metal such as platinum or a platinum alloy (e.g., platinum-tungsten alloy). The vaso-occlusive coil300includes a plurality of coil windings308. The coil windings308are generally helical about a central axis disposed along the lumen306of the vaso-occlusive coil300. The vaso-occlusive coil300may have a closed pitch configuration as illustrated inFIGS.1and3. A tether (not shown), such as a suture, may extend from the proximal end302through the lumen306to the distal end304where it is connected to the distal end304of the vaso-occlusive coil300.

The vaso-occlusive coil300generally includes a straight configuration (as illustrated inFIG.1) when the vaso-occlusive coil300is loaded within the delivery catheter100. Upon release, the vaso-occlusive coil300generally takes a secondary shape which may include three-dimensional helical configurations.FIG.2illustrates one exemplary configuration of a vaso-occlusive coil300in a natural state. In the natural state, the vaso-occlusive coil300transforms from the straight configuration illustrated in, for instance,FIG.1into a secondary shape. The secondary shaped may include both two and three dimensional shapes of a wide variety.FIG.2is just one example of a secondary shape of a vaso-occlusive coil300and other shapes and configurations are contemplated to fall within the scope of the disclosed inventions. Also, the vaso-occlusive coil300may incorporate synthetic fibers (not shown) over all or a portion of the vaso-occlusive coil300as is known in the art. These fibers may be attached directly to coil windings308or the fibers may be integrated into the vaso-occlusive coil300using a weave or braided configuration. Of course, the system10described herein may be used with occlusive coils300or other occlusive structures having a variety of configurations, and is not limited to occlusive coils300having a certain size or configuration.

The vaso-occlusive coil300depicted inFIG.3includes an adapter310at its proximal end302. The adapter310has proximal and distal portions312,314. The adapter310may be a flattened body defining an opening316at the distal end thereof. The adapter310may be formed from a non-conductive material. The distal portion314of the adapter310is permanently attached to an interior surface of the vaso-occlusive coil300at the proximal end of the occlusive coil lumen306. The distal portion314of the adapter310may be attached to the occlusive coil with an adhesive.

The proximal portion312of the adapter310is detachably connected (i.e., releasably attached) to the pusher assembly200by the sacrificial link234. The proximal end236of the sacrificial link234is mechanically and electrically connected to the positive conductor220. The sacrificial link234also forms a loop240passing through the opening316in the adapter310. The distal end238of the sacrificial link234is mechanically and electrically connected to the negative conductor222, i.e. the pusher conduit214. Interference between the loop240of the sacrificial link234and the opening316the adapter310mechanically connects the vaso-occlusive device300to the pusher assembly200.

As shown inFIG.1, the system10further includes a power supply400for supplying direct current to the positive and negative conductors220,222. Activation of the power supply400causes electrical current to flow in a circuit including the positive and negative conductors220,222and the sacrificial link234. The power supply400preferably includes an onboard energy source, such as batteries (e.g., a pair of AAA batteries), along with drive circuitry402. The drive circuitry402may include one or more microcontrollers or processors configured to output a driving current. The power supply400illustrated inFIG.1includes a receptacle404configured to receive and mate with the proximal end202of the delivery wire assembly200. Upon insertion of the proximal end202into the receptacle404, the positive, negative electrical contracts216,224disposed on the delivery wire assembly200electrically couple with corresponding contacts (not shown) located in the power supply400.

A visual indicator406(e.g., LED light) is used to indicate when the proximal end202of delivery wire assembly200has been properly inserted into the power supply400. Another visual indicator420is activated if the onboard energy source needs to be recharged or replaced. The power supply400includes an activation trigger or button408that is depressed by the user to apply the electrical current to the sacrificial link234via the positive and negative conductors220,222. Once the activation trigger408has been activated, the driver circuitry402automatically supplies current. The drive circuitry402typically operates by applying a substantially constant current, e.g., around 50-1,000 mA. Alternatively, the drive circuitry402can operate by applying two different currents, e.g., 350 mA (relatively high current) and 100 mA (relatively low current) for different functions, as described below. A visual indicator412may indicate when the power supply400is supplying adequate current to the sacrificial link234.

The power supply400may optionally include detection circuitry416that is configured to detect when the vaso-occlusive coil300has detached from the pusher assembly200. The detection circuitry416may identify detachment based upon a measured impedance value. Another visual indicator414may indicate when the occlusive coil300has detached from the pusher assembly200. As an alternative to the visual indicator414, an audible signal (e.g., beep) or even tactile signal (e.g., vibration or buzzer) may be triggered upon detachment. The detection circuitry416may be configured to disable the drive circuitry402upon sensing detachment of the occlusive coil300.

In use, the vaso-occlusive coil300is attached to the pusher assembly200at junction250. The attached vaso-occlusive coil300and pusher assembly200are threaded through the delivery catheter100to a target location (e.g., an aneurysm) in the patient's vasculature. Once the distal end304of the vaso-occlusive coil300reaches the target location, the vaso-occlusive coil300is pushed further distally until it's completely exits the distal end104of the delivery catheter100.

In order to detach the vaso-occlusive coil300from the pusher assembly200, the power supply400is activated by depressing the trigger408. The drive circuitry402in the power supply400applies a current to the positive and negative conductors220,222through the positive and negative electrical contacts216,224. As the applied current travels through the sacrificial link234, the sacrificial link234generates heat. The generated heat thermally disintegrates the sacrificial link234. After activation of the power supply400, the vaso-occlusive coil300is typically detached in less than 1.0 second.

Because most of the sacrificial link234is located in the pusher lumen212, the distal end of the pusher conduit214including the distal end of the outer sleeve232thermally insulates the sacrificial link234from the environment external to the pusher assembly200. This insulation both protects tissue adjacent the pusher assembly200and increases the heat applied to the sacrificial link234.

The vaso-occlusive device delivery systems10depicted inFIGS.4-7are similar to the system10depicted inFIG.3. Similar elements of this embodiment are identified with the same reference numbers as discussed above with respect toFIG.3. A feature common to the systems10depicted inFIGS.4to7that is different from the system10depicted inFIG.3is that the negative conductor222is a wire that runs between the proximal and distal ends202,204of the pusher assembly200in the pusher lumen212, like the positive conductor220. The positive and negative conductors220,222both run through the proximal seal230and the tubular member226. As described above, in embodiments where both the positive and negative conductors220,222are wires running through the pusher lumen212, the outer sleeve232may cover the entire pusher conduit214, and the negative electrical contact224may be a ring electrode disposed around the proximal tubular portion206of the pusher conduit214and electrically connected to a proximal end of the negative conductor222.

Another feature common to the systems10depicted inFIGS.4to7is that the positive and negative conductors220,222are connected to each, other distal of the tubular member, by the sacrificial link234. In the system10depicted inFIG.4, the sacrificial link234is an elongate member234connecting the respective distal terminal ends of the positive and negative conductors220,222. One of the conductors, in this case the negative conductor222, forms a loop240through the opening316in the adapter310, thereby mechanically connecting the vaso-occlusive coil300to the pusher assembly200. When current is applied through the sacrificial link234, sacrificial link234is thermally disintegrated by resistive heating, thereby releasing the vaso-occlusive coil300from the pusher assembly200.

In the system10depicted inFIG.5, the sacrificial link234is in the form of a small tube234. The respective distal ends of the positive and negative conductors220,222extend into the small tube234through opposite openings, and are attached to the sacrificial link234therein. Otherwise, the system10depicted inFIG.5is identical to the system10depicted inFIG.4.

As in the system10depicted inFIG.4, the sacrificial link234depicted inFIG.6is an elongate member234connecting the respective distal terminal ends of the positive and negative conductors220,222. In the embodiment depicted inFIG.6, however, the elongate member234forms a loop240through the opening316in the adapter310, thereby mechanically connecting the vaso-occlusive coil300to the pusher assembly200. Otherwise, the system10depicted inFIG.6is identical to the system10depicted inFIG.4.

The system10depicted inFIG.7is similar to the system10depicted inFIG.6. However the loop240formed by the elongate member/sacrificial link234does not pass through the opening316in the adapter310. Instead a locking ring242mechanically connects the elongate member loop240to the opening316in the adapter310.

The vaso-occlusive device delivery systems10depicted inFIGS.8-14are similar to the system10depicted inFIG.3. Similar elements of this embodiment are identified with the same reference numbers as discussed above with respect toFIG.3. The systems10depicted inFIGS.8,9, and11-14do not have separate insulating tubular members. Instead the sacrificial links234are directly connected to the respective pusher conduit214in the pusher lumen212. The arrows in the positive conductor220, sacrificial link234, and the pusher conduit214illustrate the current flow. The sacrificial links234depicted inFIGS.8to14are cylindrical bodies with an OD approximately equal to the ID of the pusher conduit214. Therefore, when the sacrificial links234are inserted into the respective pusher lumens212, the outer surface of sacrificial links234are in direct contact with an inner surface of the respective pusher conduits214. The proximal ends236of the sacrificial links234are also attached to the respective proximal seals230. The distal ends238of sacrificial links234are attached to distal seals318disposed in the lumens306of the respective vaso-occlusive coils300, thereby connecting the vaso-occlusive coils300with the respective pusher assemblies200. The distal seals318can be formed from adhesives.

In the system depicted inFIG.8, sacrificial link234is a conductive tube234having a conductive tube lumen244. The distal end of the positive conductor220is disposed in the conductive tube lumen244. The entire portion of the positive connector220disposed in the conduct of tube lumen244is bare wire in electrical contact with the conductive tube234. When current is applied through the sacrificial link234, sacrificial link234is thermally disintegrated by resistive heating, thereby releasing the vaso-occlusive coil300from the pusher assembly200. Although the outer sleeve232depicted inFIG.8does not extend to the distal terminal end of the pusher assembly200, in other embodiments the outer sleeve232can extend to the distal terminal end and distally beyond.

The system10depicted inFIG.9is similar to the system10depicted inFIG.8, except that the outer sleeve232extends further distally in the system10depicted inFIG.9to cover and further insulate the conductive tube/sacrificial link234.

The system10depicted inFIG.10is similar to the system10depicted inFIG.9, except that an insulating tubular member226is disposed around the proximal end236of the conductive tube/sacrificial link234. The tubular member226insulates the proximal end236of the conductive tube234from the negative conductor222. However the terminal most winding246of the negative conductor222(pusher conduit214) extends distally beyond the tubular member226, thereby electrically connecting the positive and negative conductors220,222through a smaller area. Further, only the distal most portion248of the positive conductor220is exposed, thereby further reducing the area of electrical contact between the positive and negative conductors220,222, and increasing the resistivity of the sacrificial link234and the heat generated therein.

The vaso-occlusive device delivery systems10depicted inFIGS.11-14are similar to the systems10depicted inFIG.8-10. Similar elements of this embodiment are identified with the same reference numbers as discussed above with respect toFIGS.8-10. The respective sacrificial links234depicted inFIGS.11-14are elongate bodies234defining open proximal ends236, close distal ends238, and conductive bore lumens244. The elongate bodies234are connected to respective proximal and distal seals230,318, thereby connecting the vaso-occlusive coils300from the pusher assemblies200. The elongate bodies234can be injection molded around their respective positive conductors220.

In the system10depicted inFIG.11, the positive conductor220extends into the conductive bore lumen244and is electrically connected to the elongate body234therein. The system10depicted inFIG.12is similar to the system10depicted inFIG.11, except that the distal end of the positive conductor220has a protrusion252extending obliquely along a longitudinal axis of the first conductor and into the elongate body234. The protrusion252forms a hook securing the positive conductor220in the elongate body234, and strengthening the mechanical connection therebetween.

The system10depicted inFIG.13is similar to the system10depicted inFIG.12. Instead of an oblique protrusion, the distal end of the positive connector220includes a radially enlarged portion254but also strengthens the mechanical connection between the positive conductor220and the conductor bore234. The radially enlarged portion254also concentrates current density in the distal end of the positive connector220.

System depicted inFIG.14this similar to the system10depicted inFIG.11, except that the proximal end236of the elongate body234extends completely through the proximal seal230. This design facilitates separation of vaso-occlusive coil300from the pusher assembly200.

The vaso-occlusive device delivery system10depicted inFIG.15is similar to the system10depicted inFIG.3. Similar elements of this embodiment are identified with the same reference numbers as discussed above with respect toFIG.3. The proximal and distal ends236,238of the sacrificial link234form proximal and distal spherical enlargements236,238, respectively, forming a “dog-bone” shape. The proximal spherical enlargement236is disposed in and connected to the proximal seal230, which is itself connected to the distal end of the pusher conduit214. The proximal seal230may be made from a non-conductive polymer, and includes distally extending portion256that thermally insulates the sacrificial link234.

The distal spherical enlargement238is disposed in an opening316in the adapter310and connected to the adapter310, which is itself connected to the proximal end302of the vaso-occlusive coil300. The proximal and distal spherical enlargements236,238strengthen the mechanical connections between the sacrificial link234and the proximal seal230and the adapter310. Further, the vaso-occlusive coil300depictedFIG.15also includes a stretch-resisting member320attached to the distal end304of vaso-occlusive coil300. The proximal end of the stretch-resisting member320forms a loop322passing through a second opening316in the adapter310, thereby attaching the stretch-resisting member320to the adapter310.

The vaso-occlusive device delivery system10depicted inFIG.16is similar to the system10depicted inFIG.15. Similar elements of this embodiment are identified with the same reference numbers as discussed above with respect toFIG.15. The sacrificial link234depicted inFIG.16is an elongate body forming a loop240. The sacrificial link234is connected to a polymer proximal seal230similar to the one depicted inFIG.15. The adapter310includes a ring324disposed in the distal seal318and the tether326extending proximally of the distal seals318. The tether is threaded through the loop240formed by the sacrificial link234. The stretch-resisting member320is threaded through the ring324in the adapter310, thereby connecting the vaso-occlusive coil300to the pusher assembly200. The vaso-occlusive coil300also includes a cylindrical member328disposed around the tether326.

The vaso-occlusive device delivery system10depicted inFIG.17is similar to the system10depicted inFIG.16. Similar elements of this embodiment are identified with the same reference numbers as discussed above with respect toFIG.16. There are two differences between the systems10depicted inFIGS.16and17. First, the proximal seal230depicted inFIG.17does not have a distally extending portion like the one depicted inFIG.16. Instead, the outer sleeve232of the pusher assembly200extends distally of the pusher conduit214, thermally insulating the sacrificial link234.

The vaso-occlusive device delivery system10depicted inFIG.18is similar to the system10depicted inFIG.17. Similar elements of this embodiment are identified with the same reference numbers as discussed above with respect toFIG.17. The system10depicted inFIG.18is not include an adapter like the one depicted inFIG.17. Instead, the stretch-resisting member320extends through the distal seal318and the cylindrical member328to form a loop322through the loop240formed by the sacrificial link234.

FIGS.19to23depict a composite sacrificial link234for use with any of the above-described embodiments. The sacrificial link234includes an electrically conductive member258partially disposed in an electrically insulating member260, leaving an exposed portion262of the electrically conductive member258. Sacrificial link234also defines grooves264for connecting to positive and negative conductors (seeFIG.23), and an opening266for connecting to the vaso-occlusive coil (seeFIG.23). InFIG.23, the proximal end302of the vaso-occlusive coil300includes an open winding330loop through the opening266in the sacrificial link234. Positive and negative conductors can be electrically connected to the electrically conductive member258by a conductive adhesive or welding268. When a current is applied through the sacrificial link234, resistive heating thermally disintegrates the exposed portion262of the electrically conductive member258, thereby releasing the vaso-occlusive coil300from the pusher assembly200.

The electrically conductive member258can be made of a conductive polymer, such as any those described above. The electrically insulating member can be made from any non-conductive polymer. Rigid non-conductive polymers include polycarbonate and polystyrene. Soft non-conductive polymers include silicone and polyurethane. The sacrificial link234can be made by either co-molding the conductive and non-conductive polymers, or over-molding the nonconductive polymer on top of the conductive polymer.

The sacrificial link234depicted inFIG.21includes a notch270in the electrically conductive member258. As shown inFIG.21, the cross-sectional area of the electrically conductive member258is at a minimum at the notch270. The decreased cross-sectional area increases resistance, thereby increasing heat generated at the notch270. The sacrificial link234depicted inFIG.22includes a small gap272in the electrically conductive member258. When current is applied through the sacrificial link234, the current will arc through the272, generating a large amount of heat and sparks to thermally disintegrate the exposed portion262of the electrically conductive member258.

The vaso-occlusive device delivery system10depicted inFIG.24is similar to the system10depicted inFIG.15. Similar elements of this embodiment are identified with the same reference numbers as discussed above with respect toFIG.15. Like the sacrificial link234depicted inFIG.15, the sacrificial link234depicted inFIG.24has proximal and distal spherical enlargements236,238in its proximal and distal ends236,238, respectively, forming a “dog-bone” shape. However, the proximal spherical enlargement236of the sacrificial link234extends proximally of the proximal seal230, creating a mechanical interference with the proximal seal230preventing distal movement of the sacrificial link234. Further, the distal spherical enlargement238to sacrificial link234extends distally of the distal seal318, creating a mechanical interference with the distal seal318preventing proximal movement of the sacrificial link234. Sacrificial link234also includes an exposed portion262between the proximal and distal seals230,318. Moreover, the stretch-resisting member320forms a loop322around the distal spherical enlargement238, connecting the stretch-resisting member320to the sacrificial link234. When current is applied through the sacrificial link234, heat is generated at the exposed portion262, thermally disintegrating the exposed portion262and releasing the vaso-occlusive coil300from the pusher assembly200.

The vaso-occlusive device delivery system10depicted inFIG.25is similar to the system10depicted inFIG.24. Similar elements of this embodiment are identified with the same reference numbers as discussed above with respect toFIG.24. The proximal and distal seals230,318depicted inFIG.25each have a flat profile. The sacrificial link234is disposed in the proximal seal230, except for an exposed portion262, which is connected to the proximal end of the distal seal318. The proximal and distal seals230,318each define respective pluralities of fingers274,276. The distal terminal end of the distal coil portion208of the pusher conduit214and the proximal terminal end of the vaso-occlusive coil300each include open windings246,330. The fingers274defined by the proximal seal230are interlaced between adjacent open windings246of the distal terminal end of the distal coil portion208, mechanically connecting the proximal seal230, and the sacrificial link234contained therein, to the pusher conduit214. The fingers276defined by the distal seal318are interlaced between adjacent open windings330of the proximal terminal end of the vaso-occlusive coil300, mechanically connecting the distal seal318, and the sacrificial link234attached thereto, to the vaso-occlusive coil300. When current is applied through the sacrificial link234, heat is generated at the exposed portion262, thermally disintegrating the exposed portion262and releasing the vaso-occlusive coil300from the pusher assembly200.

FIG.26illustrates a schematic view of the junction250between the pusher assembly200and the vaso-occlusive coil300according to one embodiment of the disclosed inventions. The system10depicted inFIG.26is similar to the system10depicted inFIG.18. Similar elements of this embodiment are identified with the same reference numbers as discussed above with respect toFIG.18. The system10includes positive and negative conductors220,222and a sacrificial link234connected thereto. The positive and negative conductors220,222are disposed on the proximal side of the proximal seal230in the sacrificial link234is disposed on the distal side of the proximal seal230. First and second load bearing connectors278,280connected distal ends of the positive and negative conductors220,222two opposite sides of the sacrificial link234, respectively. While the first and second load bearing connectors278,280form rings for attachment of the positive and negative conductors220,222and the sacrificial link234, the load bearing connectors278,280and the positive and negative conductors220,222and the sacrificial link234may be tied to each other. Sacrificial link234is made of the material such as nitinol (other materials described above) that thermally disintegrates upon application of a relatively high current, for example 350 mA.

A stretch-resisting member320passes proximally through the distal seal318and forms a loop322around the sacrificial link234, thereby connecting the vaso-occlusive coils300to the pusher assembly200. The stretch-resisting member320is formed from a low melting point polymer.

In use the system10depicted inFIG.26has two modes of operation to detach the vaso-occlusive device300from the pusher assembly200. In the “melting mode,” the relatively low current, for example 100 mA, is applied through the sacrificial link234. This generates small amount of heat, which is not sufficient to generate a temperature that will disintegrate the sacrificial link234. However, this heat is sufficient to generate a temperature that will melt the stretch-resisting member320looping through an in contact with the sacrificial link234, detaching the vaso-occlusive device300the pusher assembly200. In the “disintegrating mode,” a relatively high current, for example 350 mA, is applied through the sacrificial link234, the relatively high current generates a temperature that thermally disintegrates to sacrificial link234, detaching the vaso-occlusive device300from the pusher assembly200. The power supply400can be controllable to selectively deliver the relatively low current or the relatively high current to the sacrificial link234.

The systems10depicted inFIG.27is similar to the system10depicted inFIG.26. Similar elements of this embodiment are identified with the same reference numbers as discussed above with respect toFIG.26. The system depicted inFIG.27includes an alternative positive conductor282, which has a higher resistivity than the positive conductor220. In this case, the alternative positive conductor282has a higher resistivity because it is length of nitinol wire, thereby increasing the total length of nitinol wire in the circuit. The alternative positive conductor282is also connected to the sacrificial link234such that the alternative positive and negative conductors282,222and the sacrificial link234form circuit.

When a relatively high current, is applied through the alternative positive and negative conductors282,222and the sacrificial link234, the heat generated by the resistance of sacrificial link234does not raise the temperature of the sacrificial link234sufficiently to thermally disintegrate the sacrificial link234. However, applying a relatively high current through the alternative positive and negative conductors282,222and the sacrificial link234does raise the temperature of sacrificial link234sufficiently to melt the stretch-resisting member320in contact therewith. Accordingly, the power supply400can select between the “melting mode” and “disintegrating mode” by flowing current through either the positive or alternative positive conductors220,282, instead of varying the amount of current flowed through the system10.

The systems10depicted inFIG.28is similar to the system10depicted inFIG.26. Similar elements of this embodiment are identified with the same reference numbers as discussed above with respect toFIG.26. In the system10depicted inFIG.28, the positive and negative conductors220,222extend distally through the proximal seal230and connect directly to the sacrificial link234. In this case, the positive and negative conductors220,222are wrapped around respective opposite ends of the sacrificial link234and soldered thereto, mechanically and electrically connecting the conductors220,22to the sacrificial link234without load bearing connectors.

Although particular embodiments of the disclosed inventions have been shown and described herein, it will be understood by those skilled in the art that they are not intended to limit the present inventions, and it will be obvious to those skilled in the art that various changes and modifications may be made (e.g., the dimensions of various parts) without departing from the scope of the disclosed inventions, which is to be defined only by the following claims and their equivalents. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. The various embodiments of the disclosed inventions shown and described herein are intended to cover alternatives, modifications, and equivalents of the disclosed inventions, which may be included within the scope of the appended claims.