Patent Application
20120209310
The field of the disclosed inventions generally relates to systems and delivery devices for implanting vaso-occlusive devices for establishing an embolus or vascular occlusion in a vessel of a human or veterinary patient. More particularly, the disclosed inventions relate to the connective junctions between a delivery wire assembly and the vaso-occlusive device being implanted using the delivery wire assembly.
Vaso-occlusive devices or implants are used for a wide variety of reasons, including treatment of intra-vascular aneurysms. Commonly used vaso-occlusive devices include soft, helically wound coils formed by winding a platinum (or platinum alloy) wire strand about a “primary” mandrel. The coil is then wrapped around a larger, “secondary” mandrel, and heat treated to impart a secondary shape. For example, U.S. Pat. No. 4,994,069, issued to Ritchart et al., which is fully incorporated herein by reference, describes a vaso-occlusive device that assumes a linear, helical primary shape when stretched for placement through the lumen of a delivery catheter, and a folded, convoluted secondary shape when released from the delivery catheter and deposited in the vasculature.
In order to deliver the vaso-occlusive devices to a desired site in the vasculature, e.g., within an aneurysmal sac, it is well-known to first position a small profile, delivery catheter or “micro-catheter” at the site using a steerable guidewire. Typically, the distal end of the micro-catheter is provided, either by the attending physician or by the manufacturer, with a selected pre-shaped bend, e.g., 45°, 26°, “J”, “S”, or other bending shape, depending on the particular anatomy of the patient, so that it will stay in a desired position for releasing one or more vaso-occlusive device(s) into the aneurysm once the guidewire is withdrawn. A delivery or “pusher” wire is then passed through the micro-catheter, until a vaso-occlusive device coupled to a distal end of the delivery wire assembly is extended out of the distal end opening of the micro-catheter and into the aneurysm. Once in the aneurysm, segments of some vaso-occlusive devices break off to allow more efficient and complete packing. The vaso-occlusive device is then released or “detached” from the end delivery wire assembly, and the delivery wire assembly is withdrawn back through the catheter. Depending on the particular needs of the patient, one or more additional occlusive devices may be pushed through the catheter and released at the same site.
One well-known way to release a vaso-occlusive device from the end of the delivery wire assembly is through the use of an electrolytically severable junction, which is a small exposed section or detachment zone located along a distal end portion of the delivery wire assembly. The detachment zone is typically made of stainless steel and is located just proximal of the vaso-occlusive device. An electrolytically severable junction is susceptible to electrolysis and disintegrates when the delivery wire assembly is electrically charged in the presence of an ionic solution, such as blood or other bodily fluids. Thus, once the detachment zone exits out of the catheter distal end and is exposed in the vessel blood pool of the patient, a current applied through an electrical contact to the conductive pusher wire completes an electrolytic detachment circuit with a return electrode, and the detachment zone disintegrates due to electrolysis.
The vaso-occlusive device is attached to the delivery wire assembly distal of the detachment zone at a main junction. In some vaso-occlusive device delivery systems, a main junction link joins the vaso-occlusive device to the delivery wire assembly and is covered with an adhesive, such as ultraviolet curable glue, wherein the main junction include part of the vaso-occlusive device, part of the delivery wire assembly, the main junction link, and the adhesive.
In one embodiment of the disclosed inventions, a vaso-occlusive device delivery system includes a delivery wire assembly having a core wire disposed in a delivery wire lumen, and a vaso-occlusive device having a tapered proximal end and defining a vaso-occlusive device lumen. The vaso-occlusive device further comprises a tether disposed in the lumen, wherein the tether is secured to the core wire. The system may optionally include a link respectively attached to the core wire, the proximal end of the vaso-occlusive device, and the tether. Alternatively or additionally, the vaso-occlusive device is screwed onto the link. The system may also include a clip respectively attached to the core wire and the tether. In some embodiments, the clip is laminated to the core wire. In other embodiments, the distal end of the clip forms a loop to which the tether is attached. In some embodiments, the distal end of the core wire forms a loop to which the tether is attached. In other embodiments, the distal end of the core wire is flattened and restrains the tether on the core wire.
In another embodiment of the disclosed inventions, a vaso-occlusive device delivery system includes a delivery wire assembly, a link attached to a distal end portion of the delivery wire assembly, a transition coil attached to the link and having a transition coil outer diameter, and a vaso-occlusive device attached to the transition coil and having a vaso-occlusive device outer diameter larger than the transition coil outer diameter. In some embodiments, the transition coil is attached to an interior surface of the vaso-occlusive device. In other embodiments, the transition coil is attached to a proximal end surface of the vaso-occlusive device.
In still another embodiment of the disclosed inventions, a vaso-occlusive device delivery system includes a delivery wire assembly having a core wire disposed in a delivery wire lumen, a transition member attached to a distal end portion of the core wire and having a transition member outer diameter, and a vaso-occlusive device defining a lumen having a tether disposed therein and secured to the core wire, the vaso-occlusive device having an outer diameter larger than an out diameter of the transition member. In some embodiments, the transition member is attached to an interior surface of the vaso-occlusive device. In other embodiments, the transition member is attached to a proximal end surface of the vaso-occlusive device. The system may optionally include a clip respectively attached to the core wire and the tether. In some embodiments, the core wire is laminated to the clip. In other embodiments, a distal end of the transition member forms a loop to which the tether is attached. Alternatively or additionally, the transition member comprises an open pitch coil. In other embodiments, the transition member comprises a coil having an open pitch proximal portion and a closed pitch distal portion. In still other embodiments, the transition member comprises a tube having a continuous proximal portion and a slotted distal portion.
Other and further aspects and features of embodiments of the disclosed inventions will become apparent from the ensuing detailed description in view of the accompanying figures.
The drawings illustrate the design and utility of embodiments of the disclosed inventions, in which similar elements are referred to by common reference numerals. These drawings are not necessarily drawn to scale.
Various embodiments 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 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.
The delivery catheter 100 may 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 catheter 100. Of course, the system 10 is not limited to a particular construction or type of delivery catheter 100 and other constructions known to those skilled in the art may be used for the delivery catheter 100. The inner lumen 106 may be advantageously coated with a lubricious coating such as PTFE to reduce frictional forces between the delivery catheter 100 and the respective delivery wire assembly 200 and occlusive coil 300 being moved axially within the lumen 106. The delivery catheter 100 may include one or more optional marker bands 108 formed from a radiopaque material that can be used to identify the location of the delivery catheter 100 within the patient's vasculature system using imaging technology (e.g., fluoroscope imaging). The length of the delivery catheter 100 may vary depending on the particular application, but generally is around 150 cm in length. Of course, other lengths of the delivery catheter 100 may be used with the system 10 described herein.
The delivery catheter 100 may include a distal end 104 that is straight as illustrated in
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A portion of the core wire 210 is advantageously coated with an insulative coating 218. The insulative coating 218 may include polyimide. The entire length of the core wire 210 is coated with an insulative coating 218, except for the proximal end 214 of the core wire 210 that contacts the electrical contact 216, and a small region 220 located in a portion of the core wire 210 that extends distally with respect to the distal end 204 of the delivery wire assembly 200. This latter, “bare” portion of the core wire 210 forms the electrolytic detachment zone 220, which dissolves upon application of electrical current from the power supply 400.
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An outer sleeve 262 or jacket surrounds a portion of the proximal tubular portion 206 and a portion of the distal coil portion 208 of the delivery wire conduit 224. The outer sleeve 262 covers the interface or joint formed between the proximal tubular portion 206 and the distal coil portion 208. The outer sleeve 262 may have a length of around 50 cm to around 54 cm. The outer sleeve 262 may be formed from a polyether block amide plastic material (e.g., PEBAX 7233 lamination). The outer sleeve 262 may include a lamination of PEBAX and HYDROLENE® that may be heat laminated to the delivery wire assembly 200. The OD of the outer sleeve 262 may be less than 0.02 inches and advantageously less than 0.015 inches. During manufacturing, the outer sleeve 262 is removed from the very distal end of the delivery wire conduit 224 to form an exposed return cathode.
The core wire 210, which runs through the delivery wire conduit 224, terminates at electrical contact 216 at one end and extends distally with respect to the distal coil portion 208 of the delivery wire conduit 224 to the core wire distal end 222 at the other end. The core wire 210 is coated with an insulative coating 218 such as polyimide except at the electrolytic detachment zone 220 and the proximal segment coupled to the electrical contact 216. The electrolytic detachment zone 220 is located less and half a millimeter (e.g., about 0.02 mm to about 0.2 mm) distally with respect to the distal end of the distal coil portion 208. The core wire 210 may have an OD of around 0.00175 inches.
The occlusive coil 300 includes a proximal end 302, a distal end 304, and a lumen 306 extending there between. The occlusive coil 300 is made from a biocompatible metal such as platinum or a platinum alloy (e.g., platinum-tungsten alloy). A tether 310, such as a suture, extends from the proximal end 302 through the lumen 306 to the distal end 304 where it is connected to the distal end 304 of the occlusive coil 300. The occlusive coil 300 includes a plurality of coil windings 308. The coil windings 308 are generally helical about a central axis disposed along the lumen 306 of the occlusive coil 300. The occlusive coil 300 may have a closed pitch configuration as illustrated in
The occlusive coil 300 generally includes a straight configuration (as illustrated in
Of course, the system 10 described herein may be used with occlusive coils 300 or other occlusive structures having a variety of configurations, and is not limited to occlusive coils 300 having a certain size or configuration. The distal end 222 of the core wire 210 is connected to the proximal end 302 of the occlusive coil 300 at a main junction 250. It is preferable to apply an adhesive 240 to cover the main junction 250. The adhesive 240 may include an epoxy material which is cured or hardened through the application of heat or UV radiation. For example, the adhesive 240 may include a thermally cured, two-part epoxy such as EPO-TEK® 353ND-4 available from Epoxy Technology, Inc., 14 Fortune Drive, Billerica, Mass. The adhesive 240 encapsulates the main junction 250 and increases its mechanical stability. Additional features and components used to provide mechanical interlock between the delivery wire assembly 200 and occlusive coil 300, while maintaining a smaller OD, are described below in greater detail.
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It should be appreciated that the materials for forming the occlusive coil 300 are not be limited to the examples described previously. In any of the embodiments described herein, the material for the coil 300 may be a radio-opaque material such as a metal or a polymer. Also, in other embodiments, the material for the coil 300 may be rhodium, palladium, rhenium, as well as tungsten, gold, silver, tantalum, and alloys of these metals. These metals have significant radio-opacity and in their alloys may be tailored to accomplish an appropriate blend of flexibility and stiffness. They are also largely biologically inert. Also, any materials which maintain their shape despite being subjected to high stress may be used to construct the coil 300.
For example, certain “super-elastic alloys” include various nickel/titanium alloys (48-58 atomic % nickel and optionally containing modest amounts of iron); copper/zinc alloys (38-42 weight % zinc); copper/zinc alloys containing 1-10 weight % of beryllium, silicon, tin, aluminum, or gallium; or nickel/aluminum alloys (36-38 atomic % aluminum), may be used. In further embodiments, titanium-nickel alloy known as “nitinol” may be used to form the coil 300. These are very sturdy alloys which will tolerate significant flexing without deformation even when used as very small diameter wire.
In any of the embodiments described herein, the wire used to form the coil 300 may have a cross-sectional dimension that is in the range of 0.00002 and 0.01 inches. The coil 300 may have a cross-sectional dimension between 0.003 and 0.03 inches. In various embodiments, the wires can have any geometry, such as square, rectangle, or circle. For neurovascular applications, the diameter of the coil may be anywhere from 0.008 to 0.018 inches. In other embodiments, the wires may have other cross-sectional dimensions, and the coil 300 may have other cross-sectional dimensions. In some embodiments, the wire for forming the coil 300 should have a sufficient diameter to provide a hoop strength to the resulting occlusive coil 300 sufficient to hold the coil 300 in place within the chosen body site, lumen or cavity, without substantially distending the wall of the site and without moving from the site as a result of the repetitive fluid pulsing found in the vascular system.
In any of the embodiments described herein, the axial length of the coil 300 may be in the range of 0.5 to 100 cm, and more preferably, in the range of 2.0 to 40 cm. Depending upon use, the coil 300 may have 10-75 turns per centimeter, or more preferably 10-40 turns per centimeter. In other embodiments, the coil 300 may have other lengths and/or other number of turns per centimeter.
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The power supply 400 preferably includes an onboard energy source, such as batteries (e.g., a pair of AAA batteries), along with drive circuitry 402. The drive circuitry 402 may include one or more microcontrollers or processors configured to output a driving current. The power supply 400 illustrated in
A visual indicator 406 (e.g., LED light) is used to indicate when the proximal end 202 of delivery wire assembly 200 has been properly inserted into the power supply 400. Another visual indicator 420 is activated if the onboard energy source needs to be recharged or replaced. The power supply 400 includes an activation trigger or button 408 that is depressed by the user to apply the electrical current to the sacrificial electrolytic detachment zone 220. Once the activation trigger 408 has been activated, the driver circuitry 402 automatically supplies current until detachment occurs. The drive circuitry 402 typically operates by applying a substantially constant current, e.g., around 1.5 mA.
The power supply 400 may include optional detection circuitry 410 that is configured to detect when the occlusive coil 300 has detached from the core wire 210. The detection circuitry 410 may identify detachment based upon a measured impedance value. A visual indicator 412 may indicate when the power supply 400 is supplying adequate current to the sacrificial electrolytic detachment zone 220. Another visual indicator 414 may indicate when the occlusive coil 300 has detached from the core wire 210. As an alternative to the visual indicator 414, an audible signal (e.g., beep) or even tactile signal (e.g., vibration or buzzer) may be triggered upon detachment. The detection circuitry 410 may be configured to disable the drive circuitry 402 upon sensing detachment of the occlusive coil 300.
The power supply 400 may contain another visual indicator 416 that indicates to the operator when non-bipolar delivery wire assembly 200 is inserted into the power supply 400. Non-bipolar delivery wire assemblies 200 use a separate return electrode that typically is in the form of a needle that was inserted into the groin area of the patient. The power supply 400 is configured to detect when a non-bipolar delivery wire assembly 200 has been inserted, which causes the visual indicator 416 (e.g., LED) is turned on and the user is advised to insert the separate return electrode (not shown in
The present application claims the benefit under 35 U.S.C. §119 to U.S. Provisional Application No. 61/441,541, filed Feb. 10, 2011, the contents of which are incorporated herein by reference as though set forth in full.
| Number | Date | Country | |
|---|---|---|---|
| 61441541 | Feb 2011 | US |
