RETRIEVAL SYSTEMS AND METHODS FOR USE THEREOF

RELATED APPLICATIONS

[0001] This application is a non-provisiona! of U.S. Provisional Application No. 61/297.403 filed January 22. 2010 entitled RETRIEVAL SYSTEMS AND METHODS FOR USE THEROF, the entirety of which is incorporated by reference.

FIELD OF THE INVENTION

[0002] The devices described herein are intended to retrieve obstructions from the body. In a first variation, the devices are constructed in wire form where the wires diverge from a main bundle to form a variety of shapes that form a composite device. The benefit of such a diverging wire construction is that the composite complex device can be of a "joint-less" construction. Such devices have applicability through out the body, including clearing of blockages within body lumens, such as the vasculature, by providing a capturing portion that can envelop the obstruction to address the frictionai resistance between the obstruction and body lumen prior to attempting to translate and/or mobilize the obstruction within the body lumen, in addition, the devices described below include features that prevent unwanted and premature mobilization of the obstruction when removing the obstruction through tortuous anatomy.

BACKGROUND OF THE INVENTION

[0003] Many medical device applications require advancement of dev;ce in a reduced profile to a remote site within the body, where on reaching a target site the device assumes or is deployed into a relatively larger profile. Applications in the cerebral vasculature are one such example of medical procedures where a catheter advances from a remote part of the body (typically a leg) through the vasculature and into the cerebral region of the vasculature to deploy a device. Accordingly, the deployed devices must be capable of achieving a larger profile while being able to fit within a small catheter or microcatheter. In addition, the degree to which a physician is limited in accessing remote regions of the cerebral vasculature is directly related to the limited ability of the device to constrain into a reduced profile for delivery. [0004] Treatment of ischemic stroke is one such area where a need remains to deliver a device in a reduced profile and deploy the device to ultimately remove a blockage in an artery leading to the brain. Left untreated, the blockage causes a lack of supply of oxygen and nutrients to the brain tissue. The brain relies on its arteries to supply oxygenated blood from the heart and lungs. The blood returning from the brain carries carbon dioxide and cellular waste. Blockages that interfere with this supply eventually cause the brain tissue to stop functioning. If the disruption in supply occurs for a sufficient amount of time, the continued lack of nutrients and oxygen causes irreversible cell death (infarction). Accordingly, immediate medical treatment of an ischemic stroke is critical for the recovery of a patient.

[0005] Naturally, areas outsice of ischemic stroke applications can also benefit from improved devices. Such improved devices can assume a profile for ultimate delivery to remote regions of the body and can remove obstructions.

There also remains a need for devices and systems that can safely remove the obstruction from the body once they are secured within the device at the target site. Furthermore, there remains a need for such devices that are able to safely removed once deployed distally to the obstructions in the even that the obstructions is unable to be retrieved.

[0006] Furthermore, the techniques for treating strokes described herein can be combined with stenting as well as the delivery of clot dissolving substances.

[0007] The use of stents to treat ischemic stroke is becoming more common, Tyically. a physician places an unexpanded stent across a clot and then expands the stent to compress the clot and partially open the vessel. Once the vessel is at least partially open, clot dissolving fluids, such as t-PA or urokinase, can be deployed through a microcathter to further dissolve the clot. However, these fluids generally take a long time to dissolve clot (sometimes up to several hours). Thus, the use of these fluids has not been terribly effective at dissolving clot in vessels where a complete blockage occurs. The use of a stent allows immediate flow to the vessel, the fluid can then be administered over several hours to dissolve the clot. Once the clot dissolves, the stent can either be left in place (i.e., a permanent stent), or removed (i.e., a temporary stent). [0008] However, once blood flow is restored, a portion of the clot dissolving substance is dispersed downstream of the clot via blood flow. This minimizes the contact time and amount between the fluid and the clot thereby decreasing the efficiency of the stent and fluid treatment.

[0009] The methods, devices and systems, address the problems described above.

SUMMARY OF THE INVENTION

[0010] The examples discussed herein show the inventive device m a form that is suitable to retrieve obstructions or dots within the vasculature. The term obstructions may include blood clot, plaque, cholesterol, thrombus, naturally occurring foreign bodies (i.e., a part of the body that is lodged within the lumen), a non-natural!y occurring foreign body (i.e., a portion of a medical device or other non-naturally occurring substance lodged within the lumen.) However, the devices are not limited to such applications and can apply to any number of medical applications where elimination or reduction of the number of connection points is desired.

[0011] In one variation, the devices for removing an obstruction from a blood vessel comprise a main bundle comprising a group of wires having a first end and a second end; a capturing portion formed by the group of wires and having a translating surface adjacent to a capturing surface, the translating surface having an open proximal end and the capturing surface having a permeable distal end, where the group of wires forming the capturing surface comprise a crossing mesh pattern having a plurality of interference points in the crossing mesh pattern where adjacent wires cross; where the capturing portion is formed from the group of wires such that the group of wires diverges from the second end of the main bundle to form the permeable distal end, the group of wires extend back in a proximal direction to form the capturing surface, the translating surface, and open proximal end about the main bundle, and where upon axial compression of the capturing surface the interference points of the crossing mesh engage to limit radial expansion of the capturing surface.

[0012] In another variation, the device includes a retrieval device for removing an obstruction from a body lumen, the retrieval device comprising: at least one leading wire; a retrieval body comprising a translating section adjacent to a capturing section, the translating section having an open proximal end and the capturing section having a permeable distal end. where the leading wire extends to a portion of the capturing section to permit articulation of the open proximal end relative to the leading wire, and where the capturing section comprises a crossing mesh pattern having a plurality of interference points in the crossing mesh pattern where a plurality of wires cross; and where upon axial compression of the capturing surface the interference points of the crossing mesh engage to limit radial expansion of the capturing surface.

[0013] In some variations, a variation of the device includes a translating surface and capturing surface that are configured so that a translating surface axial strength is greater than a capturing surface axia! strength, wherein application of a tensile force on the main bundle causes axial compression of the capturing surface without causing axial compression and deformation of the translating surface. As discussed herein, the capturing portion can be formed such that articulation of the capturing portion relative to the main bundle does not cause the open proximal end to reduce in size. In some examples, the capturing surface is configured to generate a spring force against the translating surface when a proximal force applied by the main bundle of wires compresses the capturing surface against the translating surface when encountering resistance from the obstruction, where the capturing surface is configured to have a sufficient axial stiffness to direct the spring force and proximal force to the open proximal end as the open proximal end engages the obstruction where the capturing surface is also sufficiently flexible to conform to a shape of the vessel.

[0014] in additional variations, the capturing section is configured so that when the open proximal end of the translating section engages resistance equal to or greater than a threshold force, proximal movement of the main bundle inverts the capturing section within the translating section and reduces a size of the capturing section. Moreover, the capturing section and traversing section can be configured to invert upon continued proximal movement of the main bundle such that the traversing surface moves dista!ly to the capturing surface.

[0016] The main bundle of the device can be joined to a proximal bundle, where the proximal bundle comprises a stiffness greater than the main bundle and where the main bundle extends for a pre-determined distance from the permeable distal end to allow navigation of a distal portion of the medical device within the cerebral vasculature. The capturing surface can have an increased frictional resistance as compared to the translating surface, such that the capturing surface engages the obstruction for removal of the obstruction.

[0016] The main bundle of wires can include at least a first wire and a second wire where the first and second wire each have different characteristics. Some of the wires forming the main bundle of wires can include at least one shape memory alloy wire. One or more wires can comprise a super-elastic outer shell and an inner core of a radiopaque material.

[0017] In another variation, the device includes a retrieval device for removing an obstruction from a body lumen, the retrieval device comprising: at least one leading wire; a retrieval body comprising a translating section adjacent to a capturing section, the translating section having an open proximal end and the capturing section having a permeable distal end, where the leading wire extends to a portion of the capturing section to permit articulation of the open proximal end relative to the leading wire, and where the capturing section comprises a crossing mesh pattern having a plurality of interference points in the crossing mesh pattern where a plurality of wires cross; and v/here upon axiai compression of the capturing surface the interference points of the crossing mesh engage to limit radial expansion of the captunng surface.

[0018] Another variation of a medical device for removing an obstruction from a blood vessel, the medical device includes a distal capturing portion having an open proximal end and a fluidly permeable distal end, the distal capturing portion having a translating surface adjacent to the open proximal end and a capturing surface adjacent the fluidly permeable distal end: a proximal capturing portion having an open distal end and a f uidiy permeable proximal end, the distal proximal portion having a translating surface adjacent to the open distal end and a capturing surface adjacent the fluidly permeab e proximal end: at least one lead element extending through the proximal capturing portion to the distal capturing portion, where the lead element is moveable relative to the proximal capturing portion such that proximal movement of the lead element decreases a distance between the open ends of the distal capturing portion and proximal capturing portion; and at least one filament forming the proximal capturing portion, the filament including at feast one fluid delivery passage extending therethrough and a fluid delivery port on a surface of the filament such that fluid can be delivered from a perimeter of the proximal capturing portion.

[0019] Methods and procedures disclosed herein include methods of removing an obstruction from a blood vessel In one variation the method can include inserting an expandable structure within the obstruction, where the expandable structure comprises at least one fluid delivery port adjacent to an interior surface of the expandable structure element; expanding the expandable structure within the obstruction; and delivering a substance through the fluid delivery port such that the substance begins to dissolve the obstruction. The expandable structure can be fabricated from at least one tubular element, the tubular element comprising a fluid delivery passage extending through at least a portion of the tubular element, where the fluid delivery passage terminates in at least one of the fluid delivery ports. In another variation, the expandable structure comprises a stent portion and a fluid delivery membrane located within the stent portion, where expanding the expandable structure comprises expanding the stent portion and where delivering the substance comprises delivering the substance through at least one delivery port located in the fluid delivery membrane.

[0020] Another variation of a method for removing an obstruction from a blood vessel includes inserting a microcatheter distally to the obstruction, where the microcatheter comprises an expandable structure; deploying the expandable structure from the microcatheter: withdrawing the microcatheter proximally to the obstruction and maintaining the expandable structure such that it remains within the obstruction: advancing a fluid delivery member within the expandable structure such that a fluid delivery section of the fluid delivery member is exposed and adjacent to the expandable structure and obstruction; delivering a fluid through the fluid delivery section such that fluid is able to engage a length of the obstruction, where the fluid is configured to dissolve the obstruction.

[0021] In those variation of the device that are navigated in tortuous anatomy (such as the cerebral vasculature), the device can include a main bundle joined to a proximal bundle, where the proximal bundle comprises a stiffness greater than the main bundle and where the main bundle extends for at least a predetermined range from the permeable distal end to allow navigation of a distal portion of the medical device within the cerebral vasculature.

[0022] The devices of the present invention typically include a main bundle from which the wires extend. In most case, the main bundle extends for a length sufficient to withdraw the device from a body of a patient. Accordingly, in such cases, the main bundle shall extend through the length of a catheter. In alternate constructions, the main bundle may be affixed to a single wire or member. In such cases, a main bundle does not extend from the capturing portion to the exterior of the patient, instead, a single wire extends to the operator interface of the device where the wire is affixed to a main bundle.

[0023] Devices of the present invention can incorporate any number of wires of different characteristics including, but not limited to. materials, shapes, sizes and/or diameters. Clearly, the number of permutations of device configurations is significant. Providing devices with such a composite construction allows for the manipulation of the device's properties to suite the intended application.

[0024] In an additional variation, the surface of the capturing portion can include a wire frame structure, a mesh, a single wound wire, a film, a membrane, a polymer covering, and a plurality of crossing wires or a heterogeneous mixing of these. In additional variations, a section of the capturing portion can include wires, while another section of the capturing portion can include a film. Clearly, any number of permutations is within the scope of this disclosure. In any case, the capturing surface should prevent the obstruction from escaping as the dev ^; ce is removed from the body Clearly, the capturing surface can comprise any number of shapes or configurations.

[0026] As noted herein, the joint-less construction improves the flexibility and strength of the device by eliminating joints, connection points, or other attachment points, !n addition, the joint-less construction improves the ability of the device to be delivered through a small microcatheter. As a result, the device and

microcatheier are able to access remote regions of the vasculature.

[0026] The devices may be fabricated to be self-expanding upon deployment from a catheter. Alternatively, the devices can be constructed from shape-memory alloys such that they automatically deploy upon reaching a pre-determined transition temperature. [0027] The devices of the present invention may also include features to prevent migration of the obstruction as the capturing portion encapsulates the obstruction. For example, a proximal foot (such as region of increased surface area) can be located on or in the catheter. In another variation, an additional capture portion is located on the catheter where the proximal end of this capture is a mesh, a single wound wire, a film, a membrane, a polymer covering, or a plurality of crossing wires affixed to or in the catheter. Accordingly, the capturing portions both envelope or surround the obstruction as they are moved together. As noted below, additional variations may allow for temporarily locking of the two capturing portions together for increase effectiveness in removing the obstruction from the body.

[0028] The capturing portions disclosed herein can include mechanical features that assist in removal of the obstruction. These features can be hooks, fibers, barb, or any such structure. Any portion of the capturing portion or even the device can have such hooks, fibers, or barbs that grip into the obstruction as the device surrounds the obstruction. It will be important that such features prevent the obstruction from sliding proximally but do not hinder the ability of the practitioner to remove the device from the body.

[0029] It should be noted that reference to surrounding, capturing or securing the obstruction includes partially and/or fully surrounding, engulfing, encapsulating, and/or securing the obstruction. In any case, a portion of the device engages the obstruction prior to translation of the obstruction within the lumen.

[0030] It should be noted that in seme variations of the invention, ail or some of the device can be designed to increase their ability to adhere to the obstruction. For example, the wires may be coupled to an energy source (e.g.. RF, ultrasonic, or thermal energy) to "weld" to the obstruction. Application of energy to the device can allow the surrounding porton to defo m into the obstruction and ''embed" within the obstruction. Alternatively, the device can impart a positive charge to the obstruction to partially liquefy the obstruction sufficiently to allow for easier removal. In another variation, a negative charge could be applied to further build thrombus and nest the device for better pulling force. The wires can be made stickier by use of a hydrophilic substance(s), or by chemicals that would generate a chemical bond to the surface of the obstruction. Alternatively, the filaments may reduce the temperature of the obstruction to congeal or adhere to the obstruction.

[0031] Additional devices and methods for treating ischemic stroke are discussed in commonly assigned U.S. Patent application nos.: 11/671 ,450 filed February 5, 2007; 11/684,521 filed March 9, 2007: 11/684,535 filed March 9. 2007; 1 1/684,541 filed March 9, 2007; 11/684,546 filed March 9, 2007; 11/684,982 filed March 12, 2007; 1 1.736,526 filed April 17, 2007; 11/736,537 filed April 17, 2007; 11/852,975 filed September 10, 2007: 2'344,378 filed December 26, 2008; and PCT Application No. PCT/US2010/026571 (Publication No. WO 2010/102307) filed March 8, 2010; the entirety of each of which ;s incorporated by reference. The principles of the invention as discussed herein may be applied to the above referenced cases to produce devices useful in treating ischemic stroke, in other words, the wire-shaped construction of devices according to present invention may assume the shapes disclosed the above-referenced cases when such a combination is not inconsistent with the features described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Each of the following figures diagrammatically illustrates aspects of the invention. Variation of the invention from the aspects shown in the figures is contemplated.

[0033] Fig. 1 A illustrates an example of a device according to the present invention when used in a system for removing obstructions from body lumens.

[0034] Fig. 1 B illustrates a first example of an obstruction removal medical device.

[0035] Fig. 1C illustrates the obstruction removal device articulating relative to leading wires (or a main bundle) without deforming an open end of the capturing portion.

[0036] Figs. 2A to 2E show a capturing portion for use with systems described herein where the capturing portion has sections of varying axial strengths. Such features can optionally be designed to provide a spring force when a section of the capturing portion is compressed and/or staged inversion of the capturing portion so that it can be removed through an immovable obstruction.

[0037] Figs. 3A to 3B illustrate additional variations of devices having capturing portions 226 that have a basket type configuration. [0038] Fig. 3C illustrates a variation of a proximal capturing portion located on an exterior of a delivery sheath.

[0039] Fig. 4A illustrates a variation of a capturing portion having a main bundle that extends beyond a certain distance to provide a device having an extremely flexible distal region and a relatively stiff proximal region with a strong joint region that will be sufficiently spacec from tortuous anatomy during use of the device.

[0040] Fig. 4B illustrates a main bundle having a curved or shaped portion.

[0041] Figs. 4C to 4E illustrate wires of different constructions within a main bundle.

[0042] Fig. 5A illustrates am example of a proximal foot located on a catheter of the present system.

[0043] Fig. 5B illustrates a distal and a proximal capturing portion located on a system under the present invention.

[0044] Figs. 5C to 5E illustrate an overview of a variation of a delivery system employing a proximal and distal capturing portion.

[0045] Figs. 5F illustrates compression or collapsing of a proximal capturing portion about an obstruction prior to translation of the obstruction in the vessel.

[0046] Figs. 6A to 6B illustrate an example of traversing an obstruction with a sheath to deploy a distal capturing portion.

[0047] Figs. 7A to 7C illustrates a condition where a section of the capturing portion deflects to provide a spring force that gradually drives a traversing section along the obstruction.

[0048] Figs. 7D to 7G illustrate staged inversion of the distal capturing portion to allow removal of the device from an immovable clot.

[0049] Fig. 8A illustrates closure of the proximal opening of a capturing portion without the benefit of articulation of the captunng portion about a leading wire.

[0060] Fig. 8B illustrates, conceptually, one benefit of articulation of a capturing portion about a leading wire or main bundle of wires.

[00S1] Figs. 8C to 8D illustrate a proximal capturing portion and a distal capturing portion approaching an obstruction. [0052] Fig. 8E illustrates the system as the two capturing portions are drawn together.

[0053] 8F illustrates a device after securing an obstruction between proximal and distal capturing sections.

[0054] Fig. 9 illustrates a main bundle as including an increased surface area or medial foot that is used to dislodge or loosen the obstruction from a wall of the body passage.

[0055] Fig. 10 illustrates a variation of a proximal and distal end of a retrieval device.

[0056] Fig. 1 1 A to 1 1 G illustrates another variation of a funnel catheter using a mesh or layer of material to form a funnel

[0057] Figs. 12A illustrates another variation of a distal basket and a proximal basket.

[0058] Figs. 12B to 12D illustrate a distal basket having features to minimize or prevent radial expansion during inversion or staged inversion.

[0059] Figs. 13A tc 13F illustrate a variation of an infusion stent structure located at an end of a shaft.

[0060] Figs. 14A to 14E illustrate use of an infusion stent structure to open flow in a vessel having a clot.

DETAILED DESCRIPTION

[0061] It is understood tnat the examples below discuss uses in the cerebral vasculature (namely the arteries). However, unless specifically noted, variations of the device and method are not limited to use in the cerebral vasculature. Instead, the invention may have applicability in various parts of the body. Moreover, the invention may be used in various procedures where the benefits of the method and/or device are desired.

[0062] Fig. 1A illustrates a system 10 for removing obstructions from body lumens as described herein. In the illustrated example, this variation of the system 10 is suited for removal of an obstruction in the cerebral vasculature. Typically, the system 10 includes a catheter 12 microcatheter, sheath, guide-catheter, or simple tube/sheath configuration for delivery of tne obstruction removal device to the target anatomy. The catheter should be sufficient to deliver the device as discussed below. The catheter 12 may optionally include an inflatable balloon 18 for temporarily blocking blood flow or for expanding the vessel to release the obstruction.

[0063] it is noted that any number of catheters or microcatheters maybe used to locate the catheter/microcatheter 12 carrying the obstruction removal device 200 at the desired target site. Such techniques are well understood standard interventional catheterization techniques. Furthermore, the catheter 12 may be coupled to auxiliary or support components 14, 16 (e.g., energy controllers, power supplies, actuators for movement of the device(s). vacuum sources, inflation sources, sources for therapeutic substances, pressure monitoring, flow monitoring, various bio-chemical sensors, bio-chemicai substance, etc.) Again, such components are within the scope of the system 10 described herein.

[0064] In addition, devices of the present invention may be packaged in kits including the components discussed above along with guiding catheters, various devices that assist in the stabilization or removal of the obstruction (e.g., proxima!- assist devices that holds the proximal end of the obstruction in place preventing it from straying during removal or assisting in the removal of the obstruction), balloon- tipped guide catheters, dilators, etc.

[0066] Fig. 1 B illustrates a first example of an obstruction removal medical device according to the features described herein. As shown, the device 200 generally includes capturing portion 226 comprising a translating section/surface 222 and a capturing section/surface 224. In the illustrated variation, the translating section 222 shown comprises a wire framework. However any number of configurations is within the scope of this disclosure. In many variations of the device, the translating section 222 provides a low friction surface so that it translates over the obstruction without significantly moving the obstruction. This permits the capturing portion 226 to envelop or surround the obstruction prior to attempting to move the obstruction within the body lumen. As noted herein, the translating section 222 attempts to reduce the outward radial force applied by the obstruction against the wall of the lumen during movement of the obstruction withm the lumen.

[0066] Fig. 1 B illustrates a distal section of the capturing portion 226 tnat serves as a capturing section/surface 232. The capturing section 232 has an increased frictiona! surface (in this variation illustrated by the crossing 204 wires) so that it can capture and ultimately remove the obstruction. The frictionai surface of the capturing section 232 can also be described as an increased coverage density. In essence, as the frictionai surface of capturing section 232 coverage density increases, there is a greater "device" surface area to interact with the obstruction. In some variations the capturing section 232 increases in frictionai surface between the translating section 234 and the end of the device 200.

[0067] As shown, the device 200 includes a main bundle 202 comprising a group of individual leading wires 204. in this variation, the bundle of leading wires 204 is surrounded by a coil or coiled wire 205. The coiled wire 205 can comprise a single leading wire that joins the device 202. Alternatively, the coiled wire 205 can extend terminate or wrap back prior to forming the capture portion 226. Moreover, the coiled wire 205 can extend throughout a length the main bundle 202, or along one or more segments of the main bundle 202.

[0068] While the example shows the group consisting of four individual leading wires 204, the bundle 202 can have any number of leading wires. In various examples 2, 4, or 8 wires were used to construct the device. In certain variations, the number of wires in the main bundle loop around from the capturing portion. For example _: if 2 leading wires a e used to construct the device, then when constructing the main bundle 202 2 wires are set to extend distally towards the captun ^' ng portion, where the 2 wires are then shaped to form the capturing portion. Eventually, the wires then loop back to extend proxima!iy away from the capturing portion. Therefore, the 2 wires are doubled in the main bundle to create separate wires in the main bundle.

[0069] The individual wires 204 themselves may be comprised of a number of different 'micro" filaments, wires, or a singie type of wire. Variations of the wires 204 are discussed in detail below: however, the wires 204 can be strands, filaments, or any similar structure that is able to be joined to form the device. The bundle 202 may be braided, wrapped, twisted, or joined in any manner such that they do not separate or become unbundled except where desired. For example, wires m any section of the device 200 can be bonded together (e.g., with epoxy, a polymeric coating, weld, solder, and/or adhesive, etc.) to prevent the wires from separating during deformation of the device as it deploys or removes the obstruction. In addition, the main bundle 202 can incorporate any number of features to assist in orienting the device 200 within the body passage. For example, the main bundle 202 can include a pre-set bend that would bias the capturing portion 226 in a desired orientation upon deployment as discussed below.

[0070] As also discussed below, vanaiions of the present device 200 include capturing portions 226 where the translating section 234 provides a greater axial strength than an axial strength of the capturing section 232. The axial strength (e.g.. column strength) determines whether the respective section of the capturing portion 226 compresses when the device 200 encounters resistance from an object and as a proximal or pulling force is applied through the main bundle or leading wire 202. !n use, the translating section 234 resists axial compression and deformation so that it can locate about the obstruction. While the nature of moving the translating section will place the structure in a state of compression, there will be no visible deformation or deflection that prevents the translating section from advancing across an obstruction.

[0071] There are a number of approaches to adjust the axial strength of a capturing section 232 as well as the entire structure. In a first example, the manner in which the leading wire is wound to form the respective surface 232, 234 impact the respective axial strength. As shown, the traversing section 234 comprises a series of wrapped wires extending in an axiai direction. This axial alignment causes the wires to oppose axial forces and thus increases the axial strength of the traversing section 234 relative to the capturing section 232. In the latter section, the wires 232 extend in a helical direction about the section 232. Thus there is less resistance to an axial load when compared to the traversing section 234.

[0072] Alternatively, or in combination, additional techniques can produce a device 200 with a capturing portion 226 that has sections of varying axial strength. In one example, the wire diameter can be adjusted to produce the desired column strength. Generally, for a given construction, a larger diameter wire increases the column strength of the section, in addition, larger diameter leading wires can terminate at the translating section 234 to permit smaller diameter wires to form the capturing section 232. In another example, the leading wire 204 composition can be selected to produce the desired axial strength. For example, drawn filled tube (DFT) wire has 30% platinum 70% nitenol. Decreasing the amount of platinum and increasing the nitenol increases the wire strength and results in higher column strength, in yet another example, the respective section, or the entire capturing portion 226. can be processed to produce the desired axial strength. For example, changing the annealing profile (e.g., temp, time) affects the wire strength, and therefore the axial strength.

[0073] Variations of devices 200 described herein can have capturing portions with alternate configurations than those shown in above. The capturing portion 226 can include constructional designs such as a basket, a filter, a bag, a coil, a helical wire structure, a mesh, a single wound wire, a film, a membrane, a polymer covering, , or a plurality of crossing wires In variations of the device, the capturing portion 226 is sufficiently permeable to allow blood or other fluid flow therethrough. As noted above, capturing portion 226 may be any structure that covers, encapsulates, engulfs, and/or ensnares the obstruction either fully or partially. Accordingly, although the capturing portion 226 is illustrated as a filter/bag, the wires may diverge to form a coil, helical shape, other mesh structure, or any other structure that defines a space that can be translated over the obstruction to ultimately remove the obstruction 2.

[0074] The capturing portion 226 can include an open proximal end 228, a permeable distal end 230 and a capturing surface 232 located therebetween. The capturing surface 232 of the capturing portion 226 defines a volume, cavity, or space that is able to cover, encapsulate, envelop, engulf, ensnare and/or surround the obstruction. Generally, the term traversing wire or filament refers to the section of leading v/ire 204 that forms the traversing surface 238. Generally, the traversing wires form the capturing surface 238 and then form the open proximal end 228. As discussed herein and illustrated below, the open proximal end 228 expands within the lumen, typically to the lumen walls, so that the obstruction enters the open proximal end 228 as the bundle 202 (or leading wire) translates the device 200 proximaliy.

[007S] The permeable distal end 230 is typically sufficiently porous so that fluid or blood may flow through. However, the end 230 is sufficiently closed (or has an increased surface area) so that the obstruction should not escape through the distal end 230 of the device 200. This construction typically causes the the obstruction to become ensnared within the capturing portion 226 and prevented from passing through by the permeable distal end 230. [0076] As shown in Fig. 1C, an important feature of the present devices 200 is that the main bundle 202 and capturing portion 226 can articulate relative to one another without interfering with the size or profile of the open proximal end 228. This feature is described more fully below. As shown, the main bundle 202 extends through the open proximal end 228 and through at least a the traversing section 234captuhng portion 226.

[0077] Fig. 1C illustrates a condition where the main bundle 202 and capturing portion 226 articulate relative to one-another. Because the main bundle 202 joins the capturing section 232 at a distance from the open proximal end 228 movement of the main bundle 202 relative to an axis 236 of the capturing portion 226 does not reduce a profile of the open proximal end 228. If the main bundle 202 were affixed or connected to the open proximal end 228, then any movement of the bundle 202 away from the capturing portion's axis 236 would exert a force on the open end. This force, in turn, would cause the open end to narrow or deform. By doing so, the open end would not be able to uniformly expand against the lumen wall to capture the obstruction.

[0078] Turning now to the construction of the device 200, as shown above, the main bundle or a leading wire 202 extends beyond the open proximal end 228 and forms the capturing portion. In one variation, the construction of the device relies on converging/diverging wires to form continuous shapes so that the device is completely joint or connection free. However, as noted herein, the leading wire or main bundle 202 can be affixed to a structure that forms the capturing portion via an attachment point, joint, or junction. In addition, the structures forming the capturing portion can be fabricated from such processes as laser cutting of tubes, etching, metal injection molding, or any other such process.

[0079] The devices of the present invention can also include additional features to aid in removal of obstructions For example, as shown in Figs. 1 B to 1C, the open proximal end 228 can include one or more petals or flanges 238 extending radially outward. The flanges 238 allow device 200 to have a flared structure at the open proximal end 228. In one example, the capturing portion 226 can be slightly oversized relative to the body passage containing the obstruction or slightly larger than the capturing portion, The flanges 238 provide an additional force against the wall of the passage to ensure that the device 200 is able to surround or encapsulate the obstruction. In yet another feature, in variations of a system having a proximal and distal capturing portion, the flanges can serve to lock the proximal and distal capturing portions together once they encapsulate or surround an obstruction. This feature minimizes the chance that the obstruction escapes from the capturing portions as the device and obstruction are removed from the body lumen.

[0080] In additional variations, the main bundle can diverge to form the capturing portion in multiple locations so long as the capturing portion's ability to articulate is not sacrificed. For example, the main bundle can diverge in several locations along the capturing surface (not shown).

[0081] Figs. 1 B to 1 C also shows an integrally formed reinforcement ring 240 located along the length of the capturing surface 232 (i.e., on the traversing wires). The reinforcement ring 240 can be a separate or discrete ring located on or in the capturing surface 232. Alternatively, or in combination, the reinforcement ring 240 can be a ring shape that is integrally formed through arrangement of the wires 204 (as show in Figs. I B to 1C). The reinforcement ring 240 assists in expanding the device when deployed in the body lumen and/or prevents the device (e.g.. the open proximal end) from collapsing as the device moves within the lumen to secure the obstruction. The reinforcement ring 240 can comprise a single wire, or a twisted pair of wires. Alternatively, the rings do not need to extend entirely circumferentia!iy around the capturing surface. Instead, a reinforcement portion may extend between adjacent traversing wires but does not necessarily extend around the circumference of the capturing section. As noted herein, reinforcement portions may extend between adjacent traversing wires in multiple locations.

[0082] Figs. 2A to 2E show several benefits of varying axial strengths of the different sections of a capture portion 226. As shown in Fig. 2A, when the physician retrieves the capturing portion 226 by pulling on the leading wire or main bundle 202 (as shown by arrow 120), the entire capturing portion 226 translates as shown by arrow 122. However, when the device 200 encounters resistance (as schematically shown by force arrows 124) the lesser axial strength of the capturing section 232 causes axial deformation or compression of the capturing section 232 (as shown by Fig. 2B). In certain variations, the capturing section 232 can be constructed to function as spring such that deformation of the capturing section 232 stores energy. Accordingly, the physician can pull the main bundle 202 to build energy in the capturing section 232 _; then relax the force on the main bundle 202. The stored energy in the capturing section 232 gradually drives the open proximal end of the translating section 234 over or along the obstruction. The physician can apply this "pull and relax" technique repeatedly until the obstruction is sufficiently captured by the capturing portion 226.

[0083] Fig. 2C shows an additional safety benefit given the varying axial strengths of the different sections of a capture portion 226. In the event the capturing portion 226 encounters an excessive degree or threshold of force (as denoted by arrows 124), the reduced axial strength of the capturing section 232 can invert within the translating section 234. As shown, the permeable distal end 230 of the capturing section 232 inverts and is pulled by the main bundle 202 within the translating section 234 and reduces in size. As shown in Fig. 2D. continued pulling on the main bundle 202 causes eventual inversion of the translating section 234 so that the capturing section 232 extends through the translating section 234 and the permeable distal end 230 is now proximal to the translating section 234. Continuing to apply move the main bundle 202 in a proximal direction 120 inverts the capturing portion 226 as shown in Fig. 2£. As shown, the translating section 234 is now distal to the capturing section 232. This causes a reduction in the size of the capturing portion through inversion of the capturing portion 226. This feature permits withdrawal of the capturing portion 226 within a delivery sheath 106 or through an immobile obstruction (as discussed below). As shown below, the ability to sequentially invert the capturing portion 226 and reduce its diameter enables retrieval of the device if deployed distal to atherosclerotic plaque or an immobile object where continued pulling against the object could cause damage or tearing of the body passage or vessel wail. It was found that retrieval devices that are not constructed with regions of varying axial strength, spring function, or staged inversion can often flatten or expand in diameter when attempting to retrieve the device though an immobile or stubborn oostittction.

[0084] Figs. 3A to 3B illustrate additional variations of devices having capturing portions 226 that have a baske: type configuration. As shown, the capturing portions 226 and surface 232 comprise a denser mesh of traversing wires that ultimately lead to the traversing section 234 that terminates in flanges 238 at the open proximal end 228 In such vacations, a first portion of the traversing surface 232that is adjacent to the open proximal end has a low coverage density relative to the remaining portion of the capturing surface having a higher coverage density that eventually forms the permeable distal end 230. This construction lowers the lowering frictional resistance of the first portion of the capturing surface when moving over or against the obstruction but allows the remaining portion of the capturing surface to encapsulate and secure the obstruction.

[0085] As shown in Fig. 3B, the wires diverge from the main bundle towards the distal end of the capturing portion 226 to form the permeable distal end 230. The permeable distal end 230 can actually have the same configuration as the capturing surface 232. In other words, the permeable distal end can simply be an extension of the capturing surface that extends over the distal end of the capturing portion.

[0086] Naturally, the divergence of the wires can occur over a length of the capturing portion 226 rather than immediately at the distal end. For example, as show m Fig. 3D. the wires diverge towards a mid-section of the capturing portion and ultimately form the permeable distal end 230.

[0087] Fig. 3C illustrates another feature for use with system described herein. In this variation, the system includes a proximal capturing portion 260 located on an exterior of a delivery sheath 106. The main bundle 202 extends through the sheath 106 to a distal capturing portion (not shown). As discussed below, the proximal capturing portion 26C can be similar to the distal capturing portions 226 described herein with the exception that the distal end 262 of the proximal capturing portion is open while tne proximal end 264 of the proximal capturing portion is closed. Furthermore, the proximal capturing portion 260 articulates with respect to the sheath 106 much in the same manner as the distal capturing portion 226 articulates relative to the main bundle 202. In this variation, the proximal end 264 of the proximal capturing portion 260 is tapered or has a smaller profile than the remaining proximal capturing portion 260. Such a feature may be useful to improve the deliverability of the device to the intended site as well as to maneuver around any obstructions within the body passage. In addition, as noted below, the proximal capturing portion 260 can be compressed about the obstruction to improve the ability of the system to remove the obstruction. The construction of the proximal capturing portion 260 can optionally include variations having regions of differing axial strength, or sections capable of generating spring force. Typically, since the proximal capturing portion 260 is not advanced distal to the obstruction, the need for staged inversion is not necessary. Accordingly, any number of capturing designs can be incorporated for the proximal capturing portion.

[0088] In some variations, the leading wire can extend to the proximal end of the system for manipulation by the physician. However, it is often the case that the characteristics of the device must vary along its length. For example, when the device is tended for use in remote torruous anatomy, the proximal section of the device is desirably stiffer (to advance the distal portion of the cevice to the target anatomy). However, the distal section o the device must have properties that make it suitable for the tortuous anatomy In the case where devices are used in the cerebral vasculature, the distal section must be extremely flexible, while the proximal section should be stiff. In many cases, different material properties are required. A problem then arises in attempting to join different materials especially in the joining region.

[0089] Conventional joining methods include soldering, welding, gluing, thermal junctions, etc. These joining methods produce an area naving an increase in the stiffness of the device. For example, if two wires are to be laser welded together, then the section where they are joined has an overlap which yields greater stiffness than the rest of the wire. This increased area of stiffness is often balanced against the strength of the joined segment. If the joined region is too long, the strength will be sufficient but the increase in stiffness often prevents navigation through the tortuous anatomy. IF the joined region is too short, then the device can navigate through the anatomy but the bond is weaker and a risk of failure increases.

[0090] Fig. 4A illustrates another variation of an improvement for use with the devices described herein especially for use in tortuous anatomy such as the cerebral vasculature. In this example, the capturing portion 226 is show w ^; th a number of leading wires 204 extending proximally. To provide the desired characteristics, the leading wires 204 are joined in region 196 to wires 198 having a structure that is suitable for the proximal anatomy (e.g., the wires are larger m diameter or stiffer). To enable use of the device 200 in the cerebral anatomy without compromising bond strength characteristics or flexibility of the device 200, the leading wires extend a ore-determined region so that the bond region 196 is placed out of the tortuous anatomy. Since the cerebral vasculature is

approximately 30 centimeters in length, the leading wires 204 can extend for a length 195 of at least a predetermined length so that it remains very flexible when navigating the cerebral vasculature or other tortuous anatomy. In one example the length was 20 centimeters (but can be 3C or more centimeters). By deliberately extending the leading wires 204 by length 194, the length of the bond region 196 can be chosen to accommodate the prox mai anatomy (where a greater stiffness of the bond region 1 6 can be accommodated). The length of the bond region 196 can vary depending on the application (e g., from 2 to20 cm for a device intended for cerebral the cerebral vasculature). However, the bond can extend along the entire proximal section of leading wire.

[0091] Fig. 4B illustrates an addition aspect of for use with devices described herein where the main bundle 202 has a curved or bend portion 252. This pre-set shape assists in orienting the capturing portion 226 within the body passage since the bend will cause the device to bias against a wall of the body passage.

[0092] Fig. 4C and 4D show cross sectional views taken along the line A-A in Fig. 4B. As shown ₍ the wire form construction described herein allows for a number of configurations depending on the particular application. For example, the individual wires 204 (as discussed herein) may themselves comprise a bundle of smaller wires or filaments. In addition, the w.res can be selected from materials such as stainless steel, titanium, platinum, gold, iridium, tantalum, Nitinol. alloys, and/or polymeric strands. In addition, the wires used in a device may comorise a heterogeneous structure by using combinations of wires of different materials to produce a device having the particular desired properties. For example, one or more wires in the device may comprise a shape memory or superelastic alloy to impart predetermined shapes or resiliency to the device. In some variations, the mechanical properties of select wires can be altered. In such a case, the select wires can be treated to alter properties including: b ttleness, ductility, elasticity, hardness, malleability, plasticity, strength, and toughness.

[0093] The device may include a number of radiopaque wires, such as gold and platinum for improved visibility under fluoroscopic imaging. In other words, any combination of materials may be incorporated into the device. In addition to the materials, the size of the wires may vary as needed. For example, the diameters of the wires may oe the same or may vary as needed.

[0094] in addition, the individual wires may have cross-sectional shapes ranging from circular, oval, d-shaped, rectangular shape, etc. Fig. 4C illustrates one possible variation in which a number of circular wires 204 are included v/ith a el- shaped wire 205. Moreover, the device is not imited to having wires having the same cross-sectional shape or size. Instead, the device can have wires having different cross-sectional shapes. For example, as shown in Fig. 4D, one or more wires 205 can have a different cross-sectional shape or size than a reminder of the wires 204. Clearly, any number of variations is within the scope of this disclosure.

[0095] To illustrate one such example, a device can have 8-12 wires made of .003' round supereiastic material (e.g., nitinol). The device may additionally have 2-4 wires made from .002" platinum for fluoroscopy. Of the 8-12 nitinol wires, 1-4 of these wires can be made of a larger diameter or different cross-seckon to increase the overall strength of the device. Finally, a coupie of polymer fibers can be added where the fibers have a desired surface property for clot adherence, etc. Such a combination of wires provides a composite device with properties not conventionally possible in view cf other formation means (such as laser cutting or etching the shape from a tube or joining materials with welds, etc.). Clearly, any number of permutations is possible given the principles of the invention.

[0096] In another example, the device may be fabricated from wires formed from a polymeric material or composite blend of polymeric materials. The polymeric composite can be selected such that it is very floppy until it is exposed to either the body fluids and or some other delivered activator that causes the polymer to further polymerize or stiffen for strength. Various coatings could protect the polymer from further polymerizing before the device is properly placed. The coatings could provide a specific duration for placement (e.g., 5 minutes) after which the covering degrades or is activated with an agent (that doesn't affect the surrounding tissues) allowing the device to increase in stiffness so that it doesn't stretch as the thrombus is pulled out. For example, shape memory polymers would allow the device to increase in stiffness. [0097] In another variation, one or more of the wires used in the device may comprise a Drawn Filled Tube (DFT) such as those provided by Fort Wayne Metals, Fort Wayne, Indiana. As shown in Fig. 4E, such a DFT wire 252 comprises a first material or shell 208 over a second material 210 having properties different from the outer shell. While a variety of materials can be used, one variation under the present devices includes a DFT wire having a supereiastic (e.g., Nitinol) outer tube with a radiopaque material within the super-elastic outer shell. For example, the radiopaque material can include any commercially used radiopaque material, including but not limited to platinum, iridium, gold, tantalum, or similar alloy. One benefit of making a capturing portion from the DFT wire noted above, is that rather than having one or more markers over the capturing portion, the entire capturing portion can be fabricated from a super-elastic material while, at the same feme, the super-elastic capturing portion is made radiopaque given the core of radiopaque material within the super-elastic shell. Ciear!y, any composite DFT wire 252 can be incorporated into the system and capturing portions described herein.

[0098] Fig. 5A shows a working end of a variation of a system 10 for removing an obstruction from a body lumen. In this variation, the system 10 includes a main bundle 202 and capturing portion 226 extending out of a micro- catheter or catheter 102. The micro-catheter 102 can optionally include a proximal foot 256 that can slide axiaiiy over main bundle 202 and can be variably positioned in relation to the capturing portion 226. The proximal foot 256 can include any number of configurations apart from the petal/flange 258 configuration (i.e., the foot can be a balloon, coil, shoulder, etc. where such structures simply replace the petals in Fig. 5A). !n any case, the proximal foot 256 provides an increased surface area that provides an opposing force to the capturing portion 226. where the opposing force aids the movement of the obstruction within the capturing portion 226. Alternatively, the proximal foot stabilizes the obstruction and keeps the obstruction from moving with the capturing portion until the captunng portion envelops the obstruction.

[0099] The size of the proximal foct 256 can be adjusted depending on the target site anatomy. For example, a larger surface area can be employed if the target site is within a bifurcation of the body passage. The Size of the proximal foot 256 can also be adjustable during the procedure. For example, in the case of a petal/flange 268 configuration, the petals 258 can assume a larger size to initially stabilize the obstruction and then reduce in size to allow the obstruction to be completely engulfed by capturing section 226.

[0100] The proximal foot 256 can extend from an interior of the catheter 102, such as from within the internal lumen of the catheter or from an additional lumen withm a wall of the catheter. Alternatively, the proximal foot 256 can be

permanently affixed to the catheter 102. In such a case, a separate catheter {without a proximal foot) can be employed to traverse the obstruction for deployment of the device distal!y to the obstruction. Once the device is deployed, the catheters can be exchanged to provide the proximal foot. In an additional variation, the proximal foot 256 can be affixed to a delivery sheath (as described below) and be collapsed within the catheter, where advancement out of the catheter expands the proximal foot 256 so that it may function as described above.

[0101] In an additional variation, a proximal capturing portion (as shown in Fig. 3H) can be used with a foot 256 that is located about the main bundle 202. Such a variation may or may not include a distal capturing portion. Accordingly, the construction of the proximal capturing portion (as described herein to include sections of varying axial strength) can be used to perform a push and relax technique (similar to that of the pull and relax technique describee herein).

[0102] Fig. 5B illustrates another variation of the system 10 where the system includes a proximal capturing portion 260 located on an exterior of a delivery sheath 06. Naturally, the proximal capturing portion 260 could also be affixed to an exterior of a micro-catheter. The proximal capturing portion 260 is similar to the capturing portions 226 described herem with the exception that the distal end 262 of the proximal capturing portion is open while the proximal end 264 of the proximal capturing portion is closed. The proximal capturing portion can also optionally be configured to have regions of varying axial strength, spring rate, and various other features associated with the distal capturing portion 226. In the illustrated variation, the capturing portion 226 and main bundle 202 move relative to the proximal capturing portion 260 to capture an obstruction. Furthermore, tne proximal capturing portion 260 articulates with respect to the sheath 106 much in the same manner as the distal capturing portion 226 articulates relative to the ma n bundle 202. As shown, the petals 238 on the open ends 228 and 262 can interact to nest once the capturing portions 226 and 260 are moved sufficiently close to one another. The outward force caused by the retained obstruction provides a frictional interaction between adjacent petals/flanges 238 to maintain the nesting.

[0103] Variations of the device include additional structures, such as springs, hooks, barbs, etc, to cause the open ends 228 and 262 to interlock. As noted above, a separate catheter can be used to initially deploy the capturing portion 226 beyond the obstruction. Although the capturing portions shown have the same configuration, the capturing portions 226 and 260 used in any given system do not have to match in size, shape, and configuration. For example, the proximal capturing portion can be impermeable to flow while the distal capturing portion allows flow. In another example, one basket may be undersized relative to the other to improve nesting.

[0104] In any case, the construction of the system 10 shown in Fig. 5B includes open ends 228 and 262 of capturing portions 226 and 260 that are unconnected. Accordingly, as the capturing portions 226 and 260 move towards one another as a result of the main bundle 202 translating relative to the delivery sheath 106 the open ends are free to articulate around the main bundle 202 and delivery sheath 106 respectively to remain expanded against the lumen wall.

[0105] Figs. 5C to 5E illustrate a variation of a system for delivery of the capturing portions 226 and 260. Fig. 5C shows the proximal 260 capturing portion affixed to a delivery sheath 106. In alternate variations, the proximal capturing portion 260 can be replaced With a proximal foot (not shown). As noted above, the main bundle or leading wires 202 extends through the delivery sheath 106 and connects to the distal capturing portion 226 beyond the opening 228 of the distal capturing portion 200. The main bundle or leading wire 202 extends through the proximal capturing portion 260. This allows the free ends of the capturing portions 228 and 262 to remain relatively unattached so that they can articulate and conform to the curvature of the vessels (as discussed below). The capturing portions 226 and 260, main bundle 202 and delivery sheath 106 extend through a microcatheter 102.

[0106] Fig. 5D illustrates a state of deployment after the microcatheter 102 traverses the obstruction (not shown). Once the microcatheter 102 is distal to the obstruction, the distal capturing portion 226 deploys from the end of the microcatheter 102. As noted herein, the capturing portions can self-expand or can expand upon actuation by the physician. In any case, the distal capturing portion 226 should be sufficiently collapsible to remain within the microcatheter 102 for deployment distal to an obstruction. To deploy the distal capturing portion 200 from the catheter 102. the main bundle 202 can translate to push the distal capturing portion 226 to eject it from the catheter 102. Alternatively, the microcatheter 102 can be withdrawn from the distal capturing portion 226.

[0107] Fig. 5E illustrates the deployment state after the catheter 102 is withdrawn proximal to the obstruction (not shown) and after the proximal capture portion 260 is delivered from the microcatheter 102. As noted above, the proximal capture portion 260 can be affixed to an exterior of the catheter, in which case the catheter may be either de-sheathed or exchanged. Alternatively, and as shown, the proximal capturing portion 260 is affixed to a delivery sheath 106 and is fabricated to collapse within the microcatheter for ultimate deployment, whereby translating the sheath 106 delivers the proximal portion 260 from the microcatheter.

[0108] Fig. 5F shows another aspect of the system 0 where the proximal end 264 of the proximal capturing portion 260 is collapsed or compressed about an obstruction 2 prior to translation of the obstruction 2 within the vessel, in this illustration, the proximal capturing portion 260 is compressible by advancing the catheter 102 over the closed proximal end 264 of the capturing portion 260. In such a case, the proximal capturing portion 260 is slidable within and relative to the catheter 102. Naturally, variations may include compressing the proximal end 264 during translation of the obstruction 2. In either case, the proximal capturing portion 260 can be compressed in a numser of different ways. For instance, the proximal basket can be compressed using a catheter 102(as shown), or the delivery sheath 106, or any other number of mechanisms (not illustrated).

[0109] As shown, the proximal enc 264 can be compressed using a sheath 106 and/or catheter 102 However, other means of compressing may be employed (e.g., a loop structure, a tube over the sheath, a draw-string configuration, etc.) in use, once the distal capturing portion 226 is deployed distally to the obstruction 2 and the catheter 102 is withdrawn proximal to the obstruction 2, the proximal capturing portion 260 is deployed. As the proximal capturing portion 260 partially (or totally) engulfs the obstruction 2, the physician can collapse or compress the proximal capturing portion 260 to better secure the obstruction within the system 10.

[0110] it is noted that any number of shapes, configurations, as well as any number of joined wires may be contemplated to form devices under the present disclosure. However, variations of the invention include selecting a number of wires to produce specific structural properties to the device. For example, the devices can have any number of wires where the limit is determined by the ability to produce a device of a sufficiently small size to access the area containing the obstruction. However, in some cases, it may be desired that wires are chosen to impart specified characteristics. For example, in the illustrated variation, the main bundle may comprise any number of wires that do not diverge to form subsequent shapes in the device. In other words, not all of the wires forming a section are required to diverge to form an adjacent section. Instead, these non-diverging wires may simply loop" back away from the device. In an additional variation, one or more wires may diverge to form a particular portion of the capturing portion (e.g., the closed end, traversing wires, etc.). Then the wires can loop back to converge again with the main bundle.

[0111] Figs. 6A to 6E show one example of the deployment of a variation of a device according to the present invention about an obstruction in a vessel. The figures are intended to demonstrate the initial placement of tne device immediately prior to removal of the obstruction,

[0112] Fig. 6A illustrates an obstruction 2 lodged within a body lumen or vessel 6. In the case where the vessel is a cerebral artery, the obstruction may result in an ischemic stroke. Using standard interventional catheterization techniques, a microcatheter 102 and guicewire 104 traverse the obstruction. The microcatheter 102 may be advanced through the obstruction 2. Alternatively, the microcatheter 102 may "push" aside the obstruction and is advanced around the obstruction. In any case, the microcatheter 102 travels from the near end 3 (or proximal side) of the obstruction 2 to the far end 4 (or distal side) of the obstruction 2. It is noted that the catheter 102 may be centered or off-center with respect to the obstruction 2. Furthermore, the device may or may not be used with a guidewire to navigate to the site and traverse the obstruction. [0113] Some variations of the device may be placed without an

accompanying guidewire. Moreover, the structures discussed herein may be directly incorporated into a guidewire assembly where deployment may require a sheath or other covering to release the components from constraint.

[0114] Fig. 6B illustrates deployment of a capturing portion 226 and main bundle 202 of the device 200 from within the microcatheter 102 distal to the obstruction 2. Accordingly, in most variations, the capturing portion 226 is designed to fit within the catheter 102 for delivery and expand upon deployment.

Alternatively, the device may be actuated to assume the desired shape (e.g., upon reaching a transition temperature where one or more wires comprise a shape memory alloy). As shown, the capturing portion 226 includes a traversing section 234 and a capturing section 232. In some procedures the traversing section 234 engulfs the obstruction 2 with little or no complication as the main bundle 202, catheter 102, or sheath 106 pulls the capturing portion 226 in a proximal direction.

[0115] However, as discussed above, there may be some procedures where the distal capturing portion 226 is deployed distal to an obstruction 2 that is deposited within the vessel or iumen such that a steady translation of the capturing portion 226 will not engulf the obstruction 2. Figs. 7A to ?G illustrate some examples of such a situation. As shown ;n Fig. 7A, a sheath 106 might be able to traverse the obstruction 2 to deploy the distal capturing portion 226 in preparation for engulfing the obstruction 2. Fig. 7B illustrates a condition where the traversing section 234 engages the obstruction 2 but is unable to easily or fully engulf the obstruction 2. However, in those variations where the capturing portion 226 includes regions having different axial strength (as discussed above), continued pulling of the main bundle 202 in a proximal direction 120 causes the capturing section 234 to compress. When the capturing section 234 is constructed to function as spring, the deformation of the capturing section 232 stores energy from the proximal movement of the main bundie 202. This storing of energy allows the physician to reiax the pulling force 120 on the main bundie 202. Fig. 7C shows a compressed capturing section 234. The energy stored in the capturing section 232 gradually drives the open proximal end 228 of the translating section 234 over or along the obstruction 2. The physician can apply this "pull anc relax" technique repeatedly until the obstruction is sufficiently captured by the capturing portion 226. In some variations, the capturing section 234 remains compressed as the obstruction 2 finally breaks loose and removed.

[0116] Fig. 7D represents the situation where a distal capturing portion distal to an object 2 that is significantly embedded within a vessel or body lumen. In such cases, the force required to remove the obstruction 2 may damage the vessel or lumen. Such obstructions include atherosclerotic plaque or other immobile objects. As shown, when the distal capturing portion 226 is pulled once the proximal force 120 reaches a threshold value (as determined by the construction cf the capturing portion 226) the capturing portion 226 undergoes a staged inversion as the permeable end 230 enters the traversing section 232. in this variation, the permeable end 230 actually enters the obstruction 2. The construction of the capturing portion 226 prevents flattening or expanding in diameter, where such movements would prevent removal of the capturing portion. Again, if the force applied by the capturing portion 226 breaks the obstruction 2 free. The obstruction 2 can be removed even though a part of the capturing portion 226 is within the obstruction 2 as shown in Fig. 2D.

[0117] Fig. 7E shows advanced inversion of the capturing portion 226 as the capturing section 234 is now proximal to the traversing section 232. The traversing section 232 may be deformed upon inversion but will taper towards the capturing section 234 as the capturing section 234 passes through the obstruction 2 {typically via an opening that was previously created by advancement of a sheath 106 through or around the obstruction 2).

[0118] Fig. 7F shows the capturing portion 226 nearly passing through the obstruction 2 so that it may be removed from the body. As shown in Fig. 7G, the capturing portion 226 is now fully inverted and is in a state where it can re-enter a catheter for removal from the patient.

[0119] The construction described herein that allows for staged inversion of the capturing portion 2 provides a significant safety feature. A physician must undertake additional surgical intervention to remove any retrieval device that has become lodged distally to an immobile obstruction. The ability of staged inversion allows the physician to invert and remove the capturing portion 226 if application of a predetermined or threshold force is exceeded by proximal displacement of the device. This feature reduces the need for additional surgical intervention to remove a retrieval device that would otherwise become lodged or separated as a result of excessive forces being applied.

[0120] Figs. 8A to 8B illustrate an additional benefit of affixing a leading wire or bundle of wires 202 beyond a proximai opening 223 of a capturing portion 226. Fig. 5A illustrates a basket type structure 90 where a wire 202 is affixed to a proximal end 92. As shown, as the leading wire 202 pulls the casket 90 through tortuous anatomy 6, the force component pulling away from an axis of the device 90 causes the proximal open end 92 to constrict or reduce in size. As shown, as the proximal end 92 approaches the obstruction 2 the perimeter of the end is not placed against the walls of the body passage 6. As a result, the constricted opening 92 places an increased axial force on the obstruction 2 as the basket 90 translates over the obstruction 2 (because the proximal end 92 pushes against the obstruction rather than sliding around it), making encapsulation of the obstruction more difficult and possible leading to vascular damage.

[0121] Fig. 8B shows a device 200 according to the principles disclosed herein. The leading wire 202 is affixed to the distal end 230 of the capturing portion 226. As the main bundle 202 is pulled through the curved vascular path, the capturing portion 226 pivots or articulates about the buncle 202 and remains aligned with the axis of the vessel. As a result any misalignment between the leading wire 202 and an axis of the capturing portion 226 does not affect the open proximal end 228. As noted above, some closing of the open proximal end may- occur, though it will not be sufficient to interfere with the obstruction as the capturing portion moves over the obstruction. Such a configuration allows the perimeter of the open proximal end 228 to remain against the wall of the passage 6. As shown, because the open proximal end 228 is not constricted, the open proximal end 228 is better suited to slide around the obstruction for eventual removal.

[0122] Fig. 8C shows withdrawal of the microcatheter 102 to the proximal side 3 of the obstruction 2 and deployment of a proximal capturing portion 260 (m alternate variations, a proximal foot can be used or the capturing portion 226 alone can be used). Again, the catheter 102 can be exchanged for a catheter 102 having a proximal capturing portion 260. Alternatively, and as shown in the accompanying figures, the proximal capturing portion 260 can be affixed to a delivery sheath 106 that is fed through the microcatheter 102.

[0123] As also shown in the figure, the main bundle 202 and capturing portions become misaligned due to the tcrtuousity of the anatomy. However, because the capturing portions 226 and 260 are able to pivot or articulate relative to the main bundle 202 and catheter 102 or sheath 106. the open ends are able to remain against the lumen wall. In conventional devices where the open end is attached to either a wire or catheter, when the wire or catheter bends in the anatomy, the forces exerted on the open ends deform or distort the end to assume a reduced profile. Accordingly, the physician may have difficulty in removing an obstruction if the profile of the open end becomes reduced in size. Closing of the open end can also result in vascular damage if the physician applies too much force in translating the device.

[0124] Fig. 8D shows movement of the capturing portions 226 and 260 adjacent to the obstruction 2. The proximal capturing portion 260 can remain stationary or may be advanced relative tc the distal capturing portion 226.

Regardless, the physician is able to ensnare the obstruction 2 within the cavities defined by the capturing portions 226 and 260. Fig. 8E illustrates the system as the two capturing portions are drawn together. For purposes of clarity, the obstruction is not shown. Upon sufficient advancement of the capturing portion 226 and proximal capturing portion 260 relative to one-another, flanges 238 on the respective open ends can interlock. This feature provides added safety in removing the device as the obstruction is encapsulated between the two nested portions.

[0125] Fig. 8F illustrates a device 200 after securing an oostruction between a proximal 260 and distal 226 capturing sections. As shown, the captured obstruction 2 is held between capturing portions 226 and 260 where the flanges 238 nest within one-another to "lock" the capturing portions together. In some variations of the device, one of the capturing portions can be undersized relative to the other. This configuration allows for the undersized capturing portion to become further compressed as the devices are pulled together. The compression of the capturing surface then serves to further compress the obstruction 2 captured within the device. [0126] The capturing portions described herein can include coverings or wrappings so long as the other features of the device are not impaired. Such coverings can oe located on both capturing portions 226 anc 260, only one or more capturing portions. The covering can include a strand or fiber wrapped or woven about the section, a polymer film, or a dipped polymer coating such as silicone, urethane, etc. The coating on either capturing portion can be solid or porous, in the latter case, blood can continue to flow through the coating, in one variation, the proximal capturing portion 260 could employ a solid covering while the distal capturing portion 200 could include a porous covering. In such a case, blood or other fluid flow could be temporarily halted by the presence of the solid covering to assist in removal of the obstruction.

[0127] Fig. 9 illustrates a variation of the system where the main bundle 202 includes a medial foot 274. The construction of the medial foot 274 can be similar to that of the proximal foot discussed above (e.g., wires looped into a petal configuration.) However, the medial foot includes a surface area or diameter larger than a diameter of the main bundle. In any case, the increased surface area of the medial foot 274 provides an increased resistance to the obstruction 2 as the distal capturing portion 200 and main bundle 202 are pulled in a proximal direction towards an obstruction 2. The medial foot 274 engages the obstruction 2 to partially displace or loosen the obstruction from the walls of the body passage. The medial foot 274 can be slidably located on the mam bundle such that after a threshold force, the medial foot moves within the distal capturing portion 200. The main bundle 202 can Include any number of medial feet 274.

[0128] Although the illustrated variation shown above comprise open-ended, circular, looped or partial loop shape cross sectional areas, variations of the capturing portions can include any number of shapes. For example, such a shape can include a circle, an arcuate shape, a partial circular shape, a loop, an oval, a square, a rectangle, a polygon, an overlaoping loop, a pair of semi-circles, etc.) The various shapes may be heat set to be either se -expanding (i.e., superelastic) or the use of shape memory alloys can allow for the device to assume the particular shape upon reaching a desired transition temperature.

[0120] The exemplary shapes discussed above permit the shaped section to adjust in diameter in response to placement in varying diameters of body lumens. It is noted that a device may have different shaped sections on different ends of the device.

[0130] While many different shapes are contemplated to be within the scope of this disclosure, the shapes will depend upon the ultimate application of the device. As noted herein, the illustrated examples have particular applicability In retrieving obstructions from the vasculature. Accordingly, for these applications the shaped sections should form a shape so that they can expand against a vessel wall without causing trauma to the vessel. For example, upon release from the catheter, the shaped section can assume their resting shape and expand within the vessel. The resting shape can be constructed to have a size slightly greater than that of the vessel. Sizing the device relative to the target vessel may assist in placing the parts of the device against a vessel.

[0131] In an additional aspect, the shaped sections may be designed to have an unconstrained shape that is larger than the intended target vessel or simply different than a cross sectional profile of the intended vessel {i.e., not circular or tubular, but e.g., linear or other different shape), in such an example, as the shaped section is released from the delivery catheter, the shape section attempts to return to the unconstrained shape. In these variations where the unconstrained shape is different from the circular profile of the vessel, the leading wire assumes a shape that accommodates the vessel but is more rigid and stable since its unconstrained shape is entirely different from that of the vessel, in other ords, the shaped section continually exerts an outward force on the vessel.

[0132] In yet another aspect, the snaped sections shown herein may not necessarily lie in the same plane. Instead, they can be axialiy spaced by an offset. One benefit of constructing the device to have non-planar shaped section is that the configuration might allow for delivery of the device through a smaller

microcatheter because the shaped sections do not interfere with one another when collapsed to fit within the microcatheter.

[0133] Another aspect applicable to all variations of the devices is to configure the devices (whether the traversing filament or the surrounding portion) for better adherence to the obstruction. One such mode includes the use of coatings that bond to certain clots {or other materials causing the obstruction.) For example, the wires may be coated with a hydrogei or adhesive that bonds to a thrombus. Accordingly, as the device secures aoout a clot, the combination of the additive and the mechanical structure of the device may improve the effectiveness of the device in removing the obstruction. Coatings may also be combined with the capturing portions or catheter to improve the aoility of the device to encapsulate and remove the obstruction (e.g.. a hydrcphilic coating).

[0134] Such improvements may also be mechanical or structural. Any portion of the capturing portion can have hooks, fibers, or barbs that grip into the obstruction as the device surrounds the obstruction. The hooks, fibers, or barbs 154 can be incorporated into any portion of the device. However, it will be important that such features do not hinder the ability of the practitioner to remove the device from the body.

[0135] In addition to additives, the device can be coupled to an RF or other power source (such as 14 or 16 in Fig. 1A). to allow current, ultrasound or RF energy to transmit through the device and induce clotting or cause additional coagulation of a ciot or other the obstruction.

[0136] The methods described herein may also include treating the obstruction prior to attempting to remove the obstruction. Such a treatment can include applying a chemical or pharmaceutical agent with the goal of making the occlusion shrink or to make it more rigid for easier removal. Such agents include, but are not limited to chemotherapy drugs, or solutions, a mild formalin, or aldehyde solution.

[0137] As for other details of the present invention, materials and

manufacturing techniques may be employed as within the level of those with skill In the relevant art. The same may hold true with respect to method-based aspects of the invention in terms of additional acts that are commonly or logically employed. In addition, though the invention has been described in reference to several examples, optionally incorporating various features, the invention is not to be limited to that which is described or indicated as contemplated with respect to each variation of the invention.

[0138] Fig. 10 illustrates one variation of a retrieval device 200 including a distal capture portion 226 coupled to one or more leading wires in the form of a main bundle 202. The main bundle extends through a sheath 106 that includes a proximal capture portion 260. The configuration of the retrieval device 200 can incorporate the proximal and distal capture portions discussed herein as well as various other configurations discussed in the commonly assigned patent applications noted above. In addition, the relative sizes of the various components shown in Fig. 10 and discussed below are for illustrative purposes only.

[0139] An end 264 of the proximal capture portion 260 is affixed to a distal end of the sheath 106. However, as noted above, other variations are within the scope of the disclosure. The main bundle 202 can optionally terminate at a handle 242. As noted above, in certain variations, the main bundle >s joined to a stiffer wire or stiffer bundle of wires. This allows the device 200 to have a very flexible distal section with a relatively stiffer proximal section. Fig. 4A above, discusses placement of a joint at a location spaced from the distal section of the device so as to increase a bond strength but not impair the distal section's flexibility. In any case, the device 200 can have a proximal bundle 203 that comprises either the exposed wires or a covering/tube over the wires. In certain variations, the bundle or wire 202, 203 can be encapsulated with a coating.

[0140] The proximal end of the sheath 106 includes a sheath handle 244. As discussed herein, axial movement of the bundle 202 or proximal bundle 203 (typically at the handle 242) results in movement 126, or translation of the bundle within the sheath 106. This action moves the distal capture portion 226 (as shown by arrows 126). In certain variations, the device 200 is leaded into a microcatheter (not shown but discussed above) that is delivered to the site of the obstruction and crosses the obstruction.

[0141] In some variations, the sheath hub 244 includes one or more locking hubs 246. Where actuation (either axial or rotational) of the locking hub 246 locks the main bundle 202 relative to the sheath handle 244 and sheath 106. It follows that such locking action also locks the distal capture portion 226 relative to the proximal capture portion 260. A variety of methods can be employed to increase a frictional interference between the locking hub 246 and the proximal bundle 203. As a result, when a physician determines a length of an obstruction, the physician can set a spacing between the capturing portions 226 260 by locking the proximal bundle 203 relative to the sheath hub 244. Accordingly, the proximal bundle 203 can include any type of incremental markings to allow the physician to readily determine a spacing of the capturing portions. As illustrated, the sheath hub 244 can include additional injection ports to deliver fluid or other substances through the sheath 106.

[0142] As noted above, the device 200 can be used with micro-catheter. In those variations it is important that the device 200 is loaded without damaging the distai bundle 202, capture portions 226 230, and/or sheath 106. As a result, the device 200 can include an optional funnel 286 that reduces the proximal capture portion 260 (a d /or the distai capture portion 226) for loading within the microcatheter and/or sheath 106.

[0143] Another variation of the device 200 includes an insertion tool 280 slidabiy affixed to the sheath 280. Because variations of the device 200 can be extremely flexible, the insertion tool 280 can be used to provide column strength to the sheath 106, bundle 202 or other components as the device 200 is pushed into the microcatheter. The insertion tool comprises a rigid section 282 and a frictional coupler 284. The rigid section 282 has a column strength that supports the device 200 to prevent buckling. The frictional coupler 284 can be a flexible material that allows an operator to squeeze or grip the coupler 284 to create a temporary frictional interface between the loading tool 280 and the device 200 {typically the sheath 106). Such an action allows axial advancement cf the device 200 as the loading tooi 280 is advanced into the microcatheter. Once the rigid section 282 is fully inserted into the microcatheter, the operator releases the frictional coupler 284 and can withdraw the loading tool 280 from the catheter without withdrawing the device 200. The insertion tool 280 can also include an optional loading tube 286 slidabiy coupled to the rigid section 282. When used, the funnel 286 can withdraw the proximal and distal capturing portion 226 260 within the loading tube 286. The loading tube 286 then couples to a microcatheter allowing the capturing portions to advance therein as the rigid section 282 and frictional coupler 284 advance the device 200 relative to the loading tube 286.

[0144] Fig. 11 A to 11 B illustrates another variation of a funnel catheter 350 suited to remove a retrieval device 200 from the body. As shown in Fig. 1 1 A, the funnel catheter 350 includes a first shaft 352 and a second shaft 354 slidabiy located therein. A mesh 370 is fused to each shaft 352 354 at a distal location 362 364. Accordingly, relative movement of the shafts 352 354 (either the first shaft 352 can be pushed or the second shaft 354 can be pulled) creates a funnel shape 372 as the mesh portion affixed to the second shaft 354 is inverted within the remainder of the mesh 370. !t is noted that in some variations of the system, the mesh funnel funnels are combined with the tine Dased funnels described above. Such that one funnel comprises the tines while the other comprises the mesh structure described herein.

[0145] In another variation, a third distally located capture portion (Similar to a distal capture portion) can be used to d¾w the retrieval device within a guide sheath, in such a variation, the third capture portion can be a larger distal capture portion and when the retrieval device engulfs an obstruction, the third basket portion can be proximally withdrawn to capture the retrieval device and obstruction.

[0146] As illustrated in Fig. 11 B, as the retrieval device 200 and obstruction 2 approach the funnel catheter 350, the distal attachment points 362 364 of the shafts 352 354 are moved together to invert the mesh 370 and form a funnel 372. The retrieval device 200 can then be withdrawn into the funnel. This design allows for the retrieval device 200 to be fully withdrawn into the catheter 350 while the funnel 372 is expanded. Alternatively, the funnel 372 can be used to compress the retrieval device 200 and obstruction 2 prior to withdrawal into the catheter 350.

[0147] The mesh 370 can include any medically acceptable material such as a nitenol braid. Furthermore, the mesh allows for flow through the vessel or lumen while expanded. However, additional variations of the device can include a solid layer of material substituted for the mesh

[0148] Figs. 11C to 11 E illustrate another variation of a funnel catheter 350 suited to remove a retrieval device 200 from the body. As shown in Fig. 1 1C, the funnel catheter 350 includes a first shaft 352 and a second shaft 354 slidabiy located therein. A mesh 370 is joined omy the rear shaft 354 at a distal location 362. The end of the mesh 370 is free at the distal end of the device 350. The mesh 370 is sized at a distal end 371 to neck down. Accordingly, as the distal shaft moves rearward, the mesh 370 is unsupported. The necked section 371 of the mesh allows for distal advancement of the device 200 through the neck portion 371. However, as shown by Fig. 11 D, rearward movement of the device 200 causes engagement with the neck portion 371. Further rearward movement of the device 200 causes the unsupported mesh 370 to form a funnel shape 372 as shown in Fig. 11 E. The funnel shape allows for the retrieval device 200 to be fully withdrawn into the catheter 350 while the funnel 372 is expanded. Alternatively, the funnel 372 can be used to compress the retrieval device 200 and obstruction 2 prior to withdrawal into the catheter 350. To compress the funnel, the device 200 can be advanced out of the funnel and away fron the mesh 370. Next, the distal shaft 352 can be advanced through the neck portion 371 of the mesh 370 to receive the device 200. in another variation, the device 350 can include a single shaft 354 where the mesh 370 can extend beyond the shaft 354. The mesh can be heat set to assume a funnel shape upon the application of a current or as it reaches body temperature, !n another variation, the mesh 370 can comprise a super-elastic material that assumes the shape shown in Fig. 11 E when released from a constraining member.

[0149] Figs. 11 F to 1 G illustrate yet another variation a funnel catheter 350 suited to remove a retrieval device 200 from the body. In this variation, the funnel catheter 350 includes a single shaft 354 having a mesh 370 is fused to a distal location 364. The mesh 370 is free at a proximal side. The mesh is also preformed to assume a funnel shape as shown in Fig. 1 1G. Accordingly, upon delivery the mesh 370 can be constrained (e.g.. via a sheath, or other removable restraint). Once the restraint is removed, the mesh 370 expands to form a funnel 372.

[0160] Fig. 12A illustrates another variation of a retrieval device 200 having the features described herein, in this additional variation, retriever device 200 is provided sterile (EtO), and is covered by a sleeve to protect the device prior to use. The variation can be used svith a commercially available .027" ID microcatheter and 8F guiding catheter. As discussed above, retriever device 200 includes a distal basket 226 and a proximal basket 260 that are mounted coaxialiy relative to each other where the distal basket is smaller than the proximal basket, as shown m Fig. 12A. In a variation of the device, the two baskets can be delivered into the target vessei as an integrated system through a microcatheter. In one example, the proximal basket measures 8 mm in length and 3.5 mm in diameter; and the distal basket measures 6.5 mm in length and 2.7 mm in diameter. In this variation, the proximal and distal baskets are designed to nest together in situ, and have features (tulips) at their extremities which permit an inter-nesting geometry. This example allows for a nested basket structure of 13mm in length. The distal basket is delivered on the distal side of the thrombo-embolus. and the proximal basket proximal is delivered on the proximal side of the thrombo-embolus or clot. The two baskets are then brought together, and the entire system (including the captured thrombo-emboius) is pulled back to the guide catheter (in the carotid or subclavian artery) where it is removed {optionally with the aid of the Exit Funnel.)

[0151] As described above, the baskets are delivered on either side of a clot. In one variation of the system described herein, each basket of the retriever device 200 is radiopaque enabling a physician to visualize and position the baskets, and encage the dot or obstruction under fluoroscopy. Once the baskets are positioned together, they can be locked together in position using a Rotating Hemostatic Valve (RHV) or similar device at the proximal handle region, and the entire system is removed.

[0152] In certain variations, the baskets of the retriever device 200 are designed to be very soft and flexible. In such cases, each basket is made from a continuous wire structure, and is free from welds, solders, adhesives. or other mechanical junctions. The continuous wire structure is comprised of a thin nitinol tube with a platinum core. This material is radiopaque and allows for direct and continuous fluoroscopic visualization during embolectomy procedures. The absence of external marker bands reduces the stiffness of the device resulting in improved device performance and deliverabiiity, as well as reduces the frictional forces to enhance the ease and ability to fully surround the dot in vivo.

[0153] The nitinol wires comprising the distal basket are integrated directly into the full length core wire at the proximal region of the device, Similarly, the nitinol wires comprising the proximal basket terminate into a long flexible coil, which is then integrated directly into the wall structure of the proximal shaft. The design of both baskets is free from joints, welds, achesives or other junctions which promotes enhanced flexibility, deliverabiiity and strength.

[0154] The baskets of the retriever device 200 are designed to reduce the frictional forces between the embolus and the vessel wali prior to mobilizing the embolus, in the design of conventional devices, the embolus is "grabbed and pulled" in one motion, thereby exerting a considerable translation force on the both the embolus and on the vessel. In contrast, and as shown in Fig. 12B, the design of the retriever device 200 first reduces the frictional forces using section 234 before the embolus is mobilized by capturing section 232. As each basket surrounds the embolus, low friction wires break the contact between the vessel and the embolus, reducing the friction and allowing for easier subsequent mobilization of the embolus.

[0166] Fig. 12B also illustrates another feature for a variation of the system described herein. In this variation, a distal basket 226 is constructed to have a crossing mesh pattern as shown by crossing wires in sections 235. This crossing wire mesh 235 permits the distal basket 226 to limit radial expansion when encountering a significant resistance force prior to the staged inversion described above. Therefore, radial expansion is limited by the crossing sections 235 during pulling of the distal basket 226 and to prevent or reduce the chance of premature inversion. The crossings pattern of the capturing section 232 transmits the longitudinal force more axially, limiting the radial expansion. Fig. 12C illustrates the distal basket encounters a resistance when moved proximally. Fig. 12D illustrates the crossing or twist 235 pattern of the capturing section to selectively interfere at one or more interference points 237. This selective interference limits further radial expansion to limit the capturing portion 232 from expanding in radial size and improves the removal of the device without causing the device to expand and become more fixated distally to an obstruction.

[0166] Fig. 13A illustrates another variation of a device according to the present system. In this variation the system includes an infusion stent structure 400 for deploying into a thrombus or clot and immediately re-establishing flow. This stent structure 400 can also deliver a clot dissolving substance (e.g., t-PA, urokinaise, etc.) for improved results. The infusion stent structure 400 is provided sterile (EtO), and can be covered by a sleeve to protect the device prior to use. It can be used with a commercially available .027" ID microcatheter and a

commercially available .010" guidewire (or .010"distal .012"proximai guidewire). However, the infusion stent structure 400 can also be usee with other catheters and guidewires as needed.

[0167] In one variation, the infusion stent structure 400 is a self-expandable braided stent measuring 25mm in length and 2.5mm in diameter. As shown in Fig. 13B. the structure 400 can have a proximal shaft 402 with a central lumen opening 406 at a distal end of the shaft 402. This lumen and opening allows the optional passage of a guide-wire or the delivery of lytics or other substances. The guidewire ensures that distal access is maintained until optimal placement is achieved and provides the ability to mechanically agitate or disrupt the thrombus with the wire, which freely passes through the lumen of the proximal shaft into the lumen of the stent, even in a deployed state. Additionally, as shown in Fig. 13C this central lumen of the proximal shaft allows for the removal of the guide-wire and for direct intra-arterial infusion of t-PA 2 through the proximal shaft and opening 406- directly into the thrombus. The stent's braided construction also facilitates recapture into the microcatheter, a known problem with current temporary stent designs.

[0158] Fig. 13D illustrates a partial cross sectional view of the stent structure 400 where the centra! lumen extends through a section of the stent 400 and further optionally includes a number of ports 408 in addition to the lumen opening 406. This permits delivery of s substance along a length of the stent rather than at the lumen opening.

[0159] As discussed above, the infusion stent 400 can be formed from a continuous wire structure where the wires overlap to form a braided stent structure. The result is a continuous wire structure that is free from any welds, solders, adhesives, or other mechanical junctions. Variations include the continuous wire structure being comprised of a thin nitinol tube with a platinum or other radiopaque core. The wire material is radiopaque and allows for direct and continuous fluoroscopic visualization during recanalization procedures. The absence of external marker bands reduces the stiffness of the device resulting m improved device performance and deiiverabiltty, and results in a reduction of frictional forces that enhances the ease and ability to recapture the device with the microcatheter.

[0160] The nitinol wires of the stent continue to form a long flexible coil, which is integrated directly into the wall structure of the proximal shaft. This means that the structure is a continuous integrator! of the stent and delivery shaft resulting in a design that is free from joints, welds, adhesives or other junctions that promotes enhanced flexibility, deliverabiiity and strength.

[0161] As shown in Fig. 13E and 13F, a beneficial design feature of the braided wires is that the wires slide easily and independently over one another. This facilitates resheathing of the stent back into the microcatheter. The sliding wires allow the stent to change the mesh pattern during resheathing into the microcatheter, allowing for facilitated removal of the stent from within a clot as compared to other temporary stents on the market. Fig. 13F shows the wires sliding into a more axial orientation (i.e., parallel to an axis of the stent) at the proximal region as they enter the microcatheter, resulting in easier re-entry. This prevents the stent from expanding in diameter upon withdrawal. The stent can be permanently affixed to the shaft 402 or it can be releasbly detachable from the shaft (e.g., through a mechanical release, electrolytic detachment joint, etc.)

[0162] Figs. 1 A to 14E illustrate one example of use of an infusion stent device 400. As shown, a microcatheter 12 is positioned and traverses a clot or obstruction 2. Optionally, one variation of the system can include a .014" guidewire (not shown) and a .027' microcatheter 12 to traverse the clot. The guidewire can be used to agitate or maneuver through the clot and the guidewire can be optionally removed as shown in Figs. 14A and 14B.

[0163] Next, infusion stent 400 is then delivered to the site of the clot 2 through the microcatheter 12 in a constrained state. The microcatheter can optionally be pulled proximally back through the clot 2 to expose the stent 400 as shown in Fig. 14C. Next, when the microcatheter 2 is moved proximal to the clot 2 the stent 400 self-expands (or can be acutatec via a spring release or other mechanism). As shown in Fig. 14D, the expanded stent 400 pushes the occlusion 2 aside, providing immediate recanaltzation to the vessel 6 and flow to the distal territories. In addition, the stent structure 400 includes a lumen 406 for delivery of the guidewire, fluids, or other devices as necessary. For example, as shown in Fig. 14E. the stent structure can further include a flush tube or lumen extending therethrough. The tube can either be fixed within the stent or advanced through an opening 406 at the proximal end of the stent. The flush tube allows delivery of fluids to the distal end of the dot or through the clot when optional ports 408 are employed.

[0164] The entire stent structure can optionally be made radiopaque (e.g., using the DFT described above), enabling the physician to visualize the entire stent under fluoroscopy. By observing blood flow along with the structure of the stent under fluoroscopy, the physican can to determine if the entire stent structure is narrowing (e.g., via a vessel or clot) or if the clot is pushing through the stent. Such an observation would be difficult or impossible using a conventional stent structure with radiopaque markers. [0165] The proximal end of a delivery shaft of the infusion stent can have a luer with a standard fitting. This luer can accept a commercially available .010" guidewire (or .010-distal/.012"proxtmal guidewire) The wire can be used for initial delivery of the stent, and then removed once the stent is deployed. At anytime during the procedure the guidewire can be reinserted and re-advanced to the location of the stent to maintain wire position across the clot should the stent need to be recaptured and repositioned.

[0166] Various changes may be made to the invention described and equivalents (whether recited herein or not included for the sake of some brevity) may be substituted without departing from the true spirit and scope of the invention. Also, any optional feature of the inventive variations may be set forth and claimed independently, or in combination with any one or more of the features described herein. Accordingly, the invention contemplates combinations of various aspects of the embodiments or combinations of the embodiments themselves, where possible. Reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms "a," "and," "said," and 'the ' include plural references unless the context clearly dictates otherwise.

[0167] It is important to note that where possible, aspects of the various described embodiments, or the embodiments themselves can be combined. Where such combinations are intended to be within the scope of this disclosure.