Thrombus removal system and process

Abstract

A device capable of capturing and facilitating the removal of a thrombus in blood vessels (or stones in biliary or urinary ducts, or foreign bodies) uses a soft coil mesh with the aid of a pull wire or string to engage the surface of a thrombus, and remove the captured thrombus. The soft coil mesh is formed by an elongated microcoil element that forms the helical elements of a macrocoil element. The microcoil element provides a relatively elastic effect to the helical elements forming the macrocoil and allows for control of gripping forces on the thrombus while reducing non-rigid contact of the device with arterial walls. The use of multiple coil mesh elements, delivered through a single lumen or multiple lumens, preferably with separate control of at least one end of each coil, provides a firm grasp on a distal side of a thrombus, assisting in non-disruptive or minimally disrupted removal of the thrombus upon withdrawal of the device.

Description

RELATED APPLICATION DATA

The present application claims priority from U.S. Provisional Application Ser. No. 60/851,699 filed 13 Oct. 2006 and is a continuation-in-part of U.S. patent application Ser. No. 11/356,321 filed 16 Feb. 2006 now U.S. Pat. No. 7,955,345, which is in turn a continuation-in-part of U.S. patent application Ser. No. 11/097,354, filed 1 Apr. 2005 now U.S. Pat. No. 7,955,344.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to intravascular medical devices. More particularly, the present invention pertains to devices for isolating, capturing, and removing blood clots from a blood vessel. This same system may also be used to safely and effectively retrieve obstructions, such as coils, balloons, or catheter fragments dislodged during interventional procedures, from the blood stream. The same system may further be used to remove obstructions from ducts and other cavities of the body, such as, for example, foreign bodies or stones from the urinary or the biliary tracts.

2. Background of the Art

The present invention pertains generally to thrombus collection and removal. The process of thrombosis may produce a clot in a patient's vasculature. Such clots may occasionally be harmlessly dissolved in the blood stream. At other times, however, such clots may lodge in a blood vessel or embolize to a distal blood vessel where they can partially or completely occlude the flow of blood. If the partially or completely occluded vessel provides blood to sensitive tissue such as the brain or heart, for example, serious tissue damage may result.

When symptoms of vascular occlusion are apparent, such as an occlusion resulting in a stroke, immediate intervention is required to minimize tissue damage. One approach is to treat a patient with clot dissolving drugs, such as recombinant tissue plasminogen activator, streptokinase, or heparin. These drugs, however, do not immediately dissolve the blood clot and generally are useful only when administered within a short time period after onset of stroke symptoms.

Published U.S. Patent Application 2005/0038447 describes A medical device for removing clots from a blood vessel, comprising: a first longitudinally-oriented spine having a distal end; a pushing member coupled to the proximal end of the first longitudinally-oriented spine and extending proximally therefrom; and a clot-grabbing basket generally disposed between and coupled to the first longitudinally-oriented spine.

Published U.S. Patent Application 2004/0138692 discloses an embolus extractor, comprising: an elongated shaft having a proximal end and a distal end; first and second struts, each strut having a proximal end and a distal end coupled to the distal end of the shaft; the first and second struts having a first position and a second position, wherein in the first position, the distal ends and the proximal ends of the struts are spaced at a first distance, and in the second position the distal ends and the proximal ends of the struts are spaced at a second distance, the second distance being less than the first distance; and third and fourth struts, each strut coupled to one of the first and second struts via a proximal end and distal end.

Published U.S. Patent Application 2004/0098023 discloses a vasoocclusive device, comprising: a core member; and a fibrous structure carried by the core member, the fibrous structure comprises one or more strands of nanofibers. The vasoocclusive device may provide the fibrous structure in a product generated at least in part by an electrospinning process comprises the steps of: supplying a polymer solution through a needle; electrostatically charging the needle; electrostatically charging a metal plate that is placed at a distance from the needle, the metal plate having a charge that is opposite that of the needle, thereby sending a jet of the polymer solution towards the metal plate; and collecting the fibrous structure from the metal plate.

Published U.S. Patent Application 2004/0039435 discloses a self-expanding, pseudo-braided device embodying a high expansion ratio and flexibility as well as comformability and improved radial force. The pseudo-braided device is particularly suited for advancement through and deployment within highly tortuous and very distal vasculature. Various forms of the pseudo-braided device are adapted for the repair of aneurysms and stenoses as well as for use in thrombectomies and embolic protection therapy.

There are a variety of ways of discharging shaped coils and linear coils into a body cavity. In addition to those patents that describe physically pushing a coil out of the catheter into the body cavity (e.g., Ritchart et al.), there are a number of other ways to release the coil at a specifically chosen time and site. U.S. Pat. No. 5,354,295 and its parent, U.S. Pat. No. 5,122,136, both to Guglielmi et al., describe an electrolytically detachable embolic device.

A variety of mechanically detachable devices are also known. Various examples of these devices are described in U.S. Pat. No. 5,234,437, to Sepetka, U.S. Pat. No. 5,250,071 to Palermo, U.S. Pat. No. 5,261,916, to Engelson, U.S. Pat. No. 5,304,195, to Twyford et al., U.S. Pat. No. 5,312,415, to Palermo, and U.S. Pat. No. 5,350,397, to Palermo et al.

Various configurations have been used to remove calculi from the biliary or urinary system. See, for instance, U.S. Pat. No. 5,064,428. Additionally, devices having various configurations have been used to remove objects from the vasculature. For example, surgical devices comprising one or more expandable and collapsible baskets have been described for removing or piercing a thrombus in the vasculature. See, U.S. Pat. No. 6,066,149. U.S. Pat. No. 5,868,754 describes a three prong-shaped device for capturing and removing bodies or articles from within a vessel.

U.S. Pat. Nos. 5,895,398 and 6,436,112 to Wensel disclose a clot and foreign body removal device comprising a clot capture coil connected to an insertion mandrel within a catheter. The clot capture coil disclosed by Wensel is made out of a material with shape memory which allows it to be deformed within the catheter and then reformed to its original coil configuration when the coil is moved outside of the catheter lumen. The Wensel invention also provides for a biphasic coil which changes shape upon heating or passing an electric current, wherein the coil can be used to ensnare and corkscrew a clot in a vessel, which is then extracted from the vessel by moving the clot capture coil and catheter proximally until the clot can be removed. According to the Wensel invention, foreign bodies are similarly captured by deploying the coil distal to the foreign body and moving the clot capture coil proximally until the foreign body is trapped within the coil

Published U.S. Patent Application 2004/0225229 describes a device comprising a core wire having a distal end and a proximal end; a catheter shaft having a proximal catheter end, a distal catheter end and a lumen through which the core wire is passed such that the distal end of the core wire extends beyond the distal catheter end; a retrieval element disposed at the distal end of the core wire, the retrieval element movable from a radially contracted position to a radially expanded position; and a first stop element attached to the core wire, the first stop element configured to prevent over-expansion of the retrieval element.

Among commercial thrombus-removal systems are at least the following:

• • 1) The MERCI system of Concentric Medical that has a form of a corkscrew or helix spring. In this system, which may use a large 0.018 F microcatheter, the microcatheter tip is first positioned across the thrombus with the help of a guidewire after which the guidewire is exchanged with the system which is deployed distal and into the thrombus. The corkscrew shape of the device facilitates penetration into the thrombus. The thrombus can then be retrieved from the artery into a large 9 French guiding catheter, and removed from the patient's body.
  • 2) The In-Time system of Boston Scientific resembles a clam-shell when compressed, but once the microcatheter is placed through the thrombus and the device extended out of the microcatheter, it expands into 4 strings that form an oval, as with a rugby football. The system is then pulled back to engage and remove the thrombus from the blood vessel. This is similar to the disclosed structure in Published US Application 2004/0138692.
  • 3) Another system, known in the trade as a “lasso” is basically a simple catheter with a wire attached to its end. The wire makes a loop and enters back into the catheter (e.g., a large 0.018 F microcatheter). The operator changes the aspect of the loop by pulling on the wire. This system was originally conceived to catch foreign bodies.
  • 4) The Catch system of Balt is a stent closed on one end forming a basket that is deployed distal to the thrombus. The operator then pulls the system and retrieves the thrombus. This is similar to the structure in FIG. 7 of U.S. Pat. No. 6,805,684.
    The above systems may have various practical and cost disadvantages. Although several of the commercial systems are designed to penetrate clot, this may in fact be impossible if the clot is made up of firm fibrin. The device may therefore not penetrate the clot but instead will slide over the thrombus. The process of engagement and retraction of a thrombus may also fractionate the clot, producing distal embolization. Currently available systems can also be difficult to guide or deploy at the site of the thrombus, or may be traumatic to the artery, and some systems are quite expensive. In addition, all these systems are bulky and cannot be safely and effectively used in small caliber blood vessels. All references cited herein are incorporate by reference in their entirety for the content of their disclosure.

SUMMARY OF THE INVENTION

A device capable of isolating, capturing, and facilitating the removal of a thrombus in blood vessels (or stones in biliary or urinary ducts, or foreign bodies) uses a soft coil mesh with the aid of a pull wire to engage the surface of a thrombus, and remove the captured thrombus. The mechanical thrombectomy device is positioned by MRI or angiography guided percutaneous transluminal catheter delivery within the lumen of the blood vessel directly adjacent to the thrombus. The soft coil mesh is formed by an elongated microcoil element that forms the helical elements of a macrocoil element having an adjustable stiffness which provides reliable dynamic compliance matching with the viscoelastic properties of the thrombus undergoing removal. The microcoil elements further provide a relatively elastic effect to the helical element forming the macrocoil that allows for control of gripping forces on the thrombus while reducing non-rigid circumferential contact of the device with vessel endoluminal surfaces. The use of multiple coil mesh elements, delivered through a single lumen or multiple lumen catheters, preferably with separate control of at least one end of each coil, provides a firm grasp on a distal side of a thrombus, facilitating non-disruptive or minimally disruptive removal of the thrombus upon withdrawal of the device.

One aspect of the present invention is to provide a mechanical thrombectomy system that can reliably and safely navigate tortuous blood vessels to the site of an intracranial or extracranial thrombus.

A second aspect of the present invention is to provide a mechanical thrombectomy device that can reliably and securely entrap a soft or hard thrombus without fragmenting the thrombus or damaging the intima of the blood vessel.

A third aspect of this invention is to provide a mechanical thrombectomy device that is biocompatible, visible on both X-ray and MR imaging, and compatible with standard medical catheters.

A further aspect of this invention is to provide a mechanical thrombectomy device that can safely and completely remove thrombus of any density from any blood vessel in the human body.

A still further aspect of the invention is the provision of a single macrocoil that may be displaced from a carrier on the distal and proximal sides of a thrombus to engage the thrombus from the distal and proximal sides, respectively.

Another further aspect of the invention is the provision of multiple macrocoils that may be separately displaced from a carrier on the proximal and the distal sides of the thrombus to engage the thrombus from the proximal and distal sides, respectively.

Another further aspect of the invention is the provision of a macrocoil that may be displaced from a carrier on the distal side of a thrombus and a separate thrombus support that may be positioned the proximal side of the thrombus to engage the thrombus from both the distal and proximal sides.

A still further aspect of the present invention is the provision of eyelets that may be displaced on the distal side of the thrombus to facilitate engagement of the thrombus using the macrocoil.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a structural material 2 that can be used as a soft coil capture element.

FIG. 1A shows the microcoil/macrocoil structure of the soft coil capture device described herein.

FIG. 1B shows the macrocoil loops constrained in a microcatheter, with a pull string attached to the distal tip of the macrocoil assembly which extends out of the microcatheter, and a pusher wire attached to the proximal end of the macrocoil assembly.

FIG. 2 shows a side view of a general principle of operation for systems according to the present technology.

FIG. 2A shows the deployment of two separate microcatheters, each with a separate macrocoil mesh element, each macrocoil mesh element having separate end controls extending from each microcatheter. The two mesh elements are shown integrating on a distal side of a thrombus.

FIG. 2B shows the meshwork of the capture device in close contact with the distal portion of a thrombus within an artery.

FIG. 3 shows the capture device in a more extensively associated thrombus engaging position during the progression of the soft coil delivery.

FIG. 4A shows the capture device in a pre-capture position within an artery in a second mode of soft coil delivery, with the coil within a first microcatheter and an extraction wire or extraction string provided from a second microcatheter.

FIG. 4B shows the capture device of FIG. 4A with the macrocoil/microcoil element in a deployed position within an artery.

FIG. 5A shows the capture device in a format of providing two distinct macrocoil/microcoil systems.

FIG. 5B shows the capture device in a format of providing two distinct macrocoil/microcoil systems with separate extraction strings or separate retraction strings.

FIG. 6 shows a pneumatic delivery microcatheter delivery system with constrained coils within the catheter.

FIG. 7 shows a dual lumen catheter system deploying two macrocoil mesh elements, each with separate end controls of a mesh wire, which have entwined beyond a thrombus.

FIG. 7A shows a series of steps in which a dual lumen catheter is deploying two macrocoil mesh assemblies, each with separate end controls of the mesh wire in each lumen. The macrocoils have entwined and progressively encircle the thrombus as the microcatheter is withdrawn.

FIG. 8 shows placement of a distal tip with multiple release segments beyond a clot.

FIG. 9A shows the advance of a cannula/coil to form a complex coil shape distal to the clot.

FIG. 9B shows the further advance of a cannula/coil to form a more complex coil shape distal to the clot following the initial displacement of FIG. 9A.

FIG. 9C shows the displacement of a cannula/coil on the proximal side of the thrombus after the formation of the more complex coil shape in FIG. 9B.

FIG. 9D shows the retraction of the device after the cannula/coil on the proximal side of the thrombus has been achieved, thus removing the clot while supported on both the distal and proximal sides of the thrombus.

FIG. 10A shows a assembly drawing with separately magnified device components for better definition.

FIG. 10B shows a cross-section of a portion of the device of FIG. 10A near an eyelet.

FIG. 7A±20FIG. 1211be interrupted by include eyelets formed from the microcoils. Eyelets may be formed along the length of the macrocoil element by dislocated microcoils extending away from the axis of the macrocoil elongate element and providing openings through which the core wire may pass. When tension is applied to the core wire, the macrocoil forms loops along the length of the macrocoil. The tension on the macrocoil is imposed on the distal end at the point of connection and pressure applied at the eyelets. Because of pressure at the eyelets, at least some loops likely will be formed adjacent at least one eyelet, sometimes with at least one eyelet approximately defining a beginning of a loop.

A method of removing a solid object from a vessel using the immediately described device could include steps such as: inserting the catheter into a vessel adjacent a solid object in the vessel; extending at least a distal end of at least one macrocoil element beyond the solid object, away from the catheter; applying tension to the core wire; retracting the at least distal end of the macrocoil element to reshape the at least one macrocoil and conform at least a portion of the macrocoil to a surface of the solid object; and withdrawing the macrocoil element and moving the solid object.

FIG. 13 further shows operation of a mechanical treatment device as The Device comprises thin wire coils placed within a microcatheter having a small internal diameter (0.024″ or less). A guiding catheter of larger diameter is positioned using angiography guidance into the blood vessel that contains the obstruction. The microcatheter is inserted through the guiding catheter and led by a microguidewire to pass between the obstruction and the lumen wall. The microguidewire is removed, and the coils are passed through the microcatheter. Portions of the coils then wrap around the obstruction producing a mesh that prevents fragmentation of the obstruction. The mesh and knot are tightened mechanically and the mesh and obstruction are pulled back into the end hole of the guiding catheter. Whenever possible, the obstruction is pulled into the guiding catheter and out of the body. If the obstruction is too large to be removed through the guiding catheter, the guiding catheter and obstruction are removed together. This device may be described as a device for retrieval of objects from within vessels of patients comprising a length of microcoil having approximately helical turns within section of the length of microcoil and an average diameter of the helical turns, at least some of the segments in the length of microcoil having eyelets that extend beyond the average diameter, and a core wire passing through adjacent eyelets from a distal end to a proximal end of the length of microcoil, the core wire being restrained near the distal end of the length of microcoil. The average diameter is preferably less than 0.050 inches. The device may be carried within a lumen of a microcatheter wherein the lumen internal diameter is greater than the average diameter of the length of microcoil. The tension applied on the proximal end of the core wire will cause the length of microcoil to form loops outside of the average diameter of the length of microcoil.

Although the examples show specific dimensions and materials, the examples and descriptions are not intended to be limiting to the scope of practice and protection of the technology described. Rather, any specific statements or values are intended to be examples within the generic concepts of the inventions and the disclosure taught and provided herein.

Experimentation with the Thrombus Removal System has been conducted in order to remove both soft and very firm clot from the arterial lumens of multiple arteries (renal, subclavian, common and internal carotid arteries) in the pig model. Soft clot was only a few hours old. Hard clot was made by allowing a pig's blood to stand for four days. The firm, fibrin-containing portion separated from the plasma, and the hard clot embolized into the selected artery of a second pig.

Both complex three-dimensional and less complex two-dimensional platinum coils were used in these experiments, including coil structures that were not designed for use in thrombectomy procedures, but rather being the commercially available types used to fill cerebral aneurysms. These coils have a variable cross-sectional diameter and length, and are attached to a stainless steel pusher wire. A commercially available microcatheter with an inner lumen of 0.018 inch was passed beyond the thrombus, particularly between the intima and the thrombus (non-occluded space between the thrombus and the walls) in the case of a firm thrombus, with the aid of a commercially available 0.014 inch microguidewire. A thin nylon line (0.006 inch) was attached to the distal end of a coil, and the coil/string complex gently passed into a microcatheter, to a point distal to the thrombus. Alternatively, the coil/string complex was preloaded into the microcatheter that was passed without the aid of a microguidewire past the distal end of the thrombus. The coils were pushed from the microcatheter, which was progressively pulled back until it was proximal to the thrombus and clot extraction attempted, as previously described.

Soft clot tended to be removed easily from the arteries studied because the clot adhered to the meshwork of the coil and the pulling wire. However, initial experiments with single coils of different sizes, including both 3-D and 2-D coils, demonstrated the inability to consistently and successfully extract the firm clot with this method, even when the coil had formed a mesh around the thrombus and the nylon string was pulled as much as possible to tighten the mesh around the clot. Rather, the coil sometimes simply unraveled from around the thrombus, sliding back into the more proximal microcatheter. It was apparent that in those failed circumstances the loops of the coil were simply wrapping around the clot without becoming tightly engaged, and that such a non-structured mesh was insufficient to overcome the combination of forces keeping the thrombus in place, including friction between the thrombus and the intima and blood flow pushing the embolus distally. However, intertwining and/or overlapping of the loops along the distal aspect of the thrombus, as one would tie a shoelace, kept the distal mesh in place without allowing the entire coil complex to unravel.

In subsequent experiments, two microcatheters were passed distal to the firm clot, each positioned in the same manner as previously described. The distal end of a 3-D coil was pushed into the arterial lumen from the first microcatheter, then the distal end of a second coil, either a 2-D or a 3-D configuration, was pushed forward from the second microcatheter, allowing loops of the two coils to intertwine. By “two coils” in this description, it is meant that there are two masses of coils, one each delivered from a microcatheter, although the term includes two coil masses emanating from two lumens of a single microcatheter, as opposed to requiring two completely distinct microcatheters. Further coils were extended to make a complex, random mesh, then the nylon strings were pulled so that a tight “cap” or “knot” was formed on the distal surface of the clot. The microcatheters were partially withdrawn and as more coils were pushed from the microcatheter, they passively encircled the middle portions of the clot. The process was continued, with more coils (at least a total of two and up to six coils would be used in a preferred range of mesh applications) placed proximal to the clot. The nylon strings was then pulled tightly to form a tight meshwork encircling the entire clot so that little or no fragmentation would occur.

Using this technique, it was possible to successfully extract firm clots from all arteries embolized without evidence of fragmentation on subsequent post-extraction angiography. Coils having diameters equal to or slightly larger than that of the arterial lumen appeared to make the best distal meshwork and, therefore, the most stable macrocoil constructs. By then passively encircling the clot, there was no tendency for the distal “cap” to simply slide from the top over the side of the clot. Post-extraction angiography and post-mortem examination, including microscopy, did not demonstrate any evidence of arterial injury. This was the expected result, given the extensive experience of using these soft platinum coils within the vascular system without producing vascular dissection or vasospasm.

Another way of generally describing articles and methods according to the practice of the technology originally disclosed herein includes a medical device for removing a thrombus from a blood vessel, comprising: a) two microcatheter lumens, each lumen containing: b) a macrocoil thrombus engaging component having a length with a proximal end and a distal end, the length of the macrocoil comprising microcoils that allow the length of the macrocoil to be extendable; c) a first wire capable of providing force on the distal end of the macrocoil; d) a second wire capable of providing force on the proximal end of the macrocoil. The device may have at least two lumens on distinct microcatheters, and the at least two lumens may be attached to a single catheter. A method may be practiced for using the device wherein for at least one macrocoil thrombus engaging coil, a microguidewire is passed through at least one of the lumens to help place the microcatheter distal to the thrombus; the microguidewire is removed; a macrocoil pull-string system comprising push-pull capability is passed through the at least one of the lumens; the macrocoil pull-string system is passed distal to the clot; the pull-string system is used to form an at least partially enclosing distal meshwork on the distal surface of the thrombus, passively encircling mesh around the clot; the pull string is pulled to tighten the meshwork; the macrocoils may have internal structures including loops and other random attachments to facilitate the formation of a tight meshwork; and at least a portion of the device is progressively withdrawn so that the meshwork becomes more tightly engaged with the clot. The method of using the device may be practiced wherein the at least one set of microcoils of at least one macrocoil exhibits a conformation memory of an amorphous shape with overlapping structure resisting complete elongation when ends of the at least one macrocoil are stressed. The conformation memory may form at least one structure selected from the group consisting of knots, loops, multiple crossovers, kinks and snags to reduce excessive slipping of macrocoils, which slipping would allow liner extension of macrocoil material. The method may have the at least one structure assist in forming a network comprising the at least one macrocoil engaging a distal surface of the thrombus. The method may be practiced so that the at least one macrocoil encircles or conforms to the surface of the distal side of the thrombus as the at least one macrocoil is extended from the microcatheter. The method may use a pull-string to tighten the at least one macrocoil against the distal side of the thrombus.

A dual lumen catheter or two separate catheters may deploy a single macrocoil mesh with controls on both ends, or two separate meshes, each with one or two separate end controls of the macrocoil mesh in each lumen. Examples of the end control elements are a pull wire or push pull wire attached to either end of the macrocoil mesh. A thrombus usually has a potential space between the thrombus and the wall of the vessel, allowing the soft macrocoil mesh to passively slid between the surface of the thrombus and the vessel wall. It is to be noted that the deployed macrocoil mesh has no clearly defined shape (such as a basket, box, pyramidal coil complex, or the like) so that the macrocoil mesh may conform to any surface, such as that of the thrombus, as it passively surrounds that surface. Proximal ends of the controlling wires or strings may be used to control the location, deployment, tension, withdrawal and other movement of the macrocoil mesh by appropriately pushing, pulling, twisting, orienting, reorienting, positioning or otherwise moving those proximal ends. Passively encircling the clot reduces the chance of unwanted fragmentation of the thrombus and subsequent embolization of the fragment to vital tissues.

Where there is the deployment of two separate microcatheters, each with a separate macrocoil mesh element, each macrocoil mesh element may have separate end controls extending from each microcatheter, respectfully. Two mesh elements may integrate into a mass on the distal side of a thrombus. Push-pull guidance wire combinations are provided for the respective pairs of macrocoil elements.

In the use of a dual lumen catheter system deploying two macrocoil meshes with separate end controls for each mesh coming out of each lumen of the microcatheter, the distal ends of the mesh, the end controls may operate as push-pull wires, guidance wires, orientation elements, positioning elements, current carrying conductors (as when heating the microcoils in the macrocoil mesh) and the like. The end controls may be the same or different in the construction of the device to assure their ability to perform the ultimately desired tasks. Both end controls aid in the formation of a knot or tight tangle of the distal ends of each macrocoil mesh over the distal aspect of the thrombus, in the passive encirclement of the mid and proximal portions of the thrombus, and in the tightening of the meshwork around the surface of the thrombus.

It is to be noted that the dashed lines for catheters shown behind thrombus in some of the illustrations are not intended to limit the images to catheters passing through the thrombus, and in fact as clearly described herein, the location of the catheters is preferably adjacent to a thrombus. In this regard, it is one of the many novel aspects of the present technology that may be practiced according to these teachings that the catheters are intentionally passed adjacent to and not through a thrombus. It is also novel to pass multiple catheters adjacent to a thrombus in a single medical procedure according to the technology described herein

There are numerous considerations of materials and properties that can be discussed herein to provide general and specific assistance to the design of instruments for various locations and procedures. The composition of the microcoils forming the macrocoil mesh may be any material that will retain its structural integrity during the expected length of an extended procedure, with safeguards built in for overextended periods of the coils being within an environment that may deteriorate or dissolve them. For example, if a standard procedure were expected to take 1-2 hours, it would be appropriate if the coils would remain intact in the operational environment for at least 24 hours and retain their physical properties. The microcoil material can be allowed to breakup or even dissolve after that time, in the event that there is a problem during the procedure, such as if a coil breaks or separates from the mesh.

Typically, the microcoil material will have essentially unaffected properties during the operation. Useful materials may be metals, alloys, plastics (polymeric materials), composites, ceramics and the like. The properties of the microcoil material are intended to provide the macrocoil mesh with resilient properties through the extensibility of the microcoils and macrocoils, and not necessarily elasticity in the material of the wire forming the various coils. The material of the wire may in fact be clearly inelastic within standards for metal wire, plastic wire, ceramic wire and composite wire, for example, having less than 20% or 10% elongation at breaking point for the wire.

Deployment of the at least one wire (with macrocoil mesh therein) may be from a single lumen on a catheter, multiple lumens on a single catheter, single lumens on multiple catheters, multiple lumens on multiple catheters, and 1, 2, 3, 4, 5 6 or more catheters or microcatheters may be used in the process.

The multiple coils may remain separate and distinct when deployed, may incidentally overlap, may intentionally overlap, may tangle with each other, may grip each other or otherwise interact. For example, when the distal ends of the macrocoils are extended from the microcatheter lumens (one microcatheter with two lumens or two separate microcatheters with one lumen each), they will overlap to produce a knot, tangle, or other firm connection. In addition, one or more of loops (the macrocoil loops) may engage each other to form a loose, incidental lock or slip resistant engagement between one or more macrocoils. Design may be built into the macrocoils, such as spikes (less preferred because of potential wall irritation), hooks and loops, posts, and hooks alone to produce a tighter mesh network and to decrease the likelihood of coil loops being extended to relatively ineffectual linearity when one end control is firmly pulled in attempting to position the mesh against the surface of a thrombus.

There are many other variants that may be provided in the practice of the present technology. Among the variations to be considered is the use of actual knot-tying techniques using multiple macrocoil/microcoil structures according to the present descriptions.

In the knot-tying format, two distinct macrocoils are fed from a single lumen, at least two separate lumens, or at least two adjacent lumens, such that a first macrocoil forms a loop with an opening large enough for a straight segment of a second macrocoil to pass through the opening, then passing at least one second macrocoil through the opening, and adjusting the local relative positions of the now at least two macrocoils so that a knot-like arrangement of the coils occurs. The interaction and engagement of the individual macrocoils of the at least two macrocoils also acts to provide a supporting structure and capability to the system.

This feature is more than superficially beneficial. When prior art capture systems are analyzed, they are found to be essentially one-size-fits-all, with only minimum variability in the size of the capture device allowed because of the more defined structure of the capture portion, as can be noted in Rosenbluth (U.S. Pat. No. 6,511,492), where a variety of cage and net structures are provided. Especially with the cage structures, the likelihood of a thrombus being disrupted during insertion and retraction is very high, especially with the more rigid elemental constructions in the pyramidal coil and cage structures. The relatively fixed size of the capture portion means that the system will use a single size for a large thrombus or a small thrombus. The potential for damage or inoperability varies among the range of size of the potential thrombus, and might require an attempt to provide distinct capture systems with advanced knowledge (which may be erroneous) of the specific size and shape of the thrombus. The present technology, because of the flexibility and conformability of the macrocoil/microcoil structure, can be used on an extremely wide variation in size of thrombi, and the coils will themselves conform to the size of whatever thrombus is present. The pull strings aid in altering the position of the distal tip of one or more macrocoils, so that the formation of the knot is facilitated. The pull string also tightens the mesh work distal to the thrombus. Finally, after macrocoils are passively looped around the mid and proximal aspects of the clot, the pull string aids in tightening the entire construct to decrease the chance of clot fragmentation.

The presently described technology includes a medical device for removing a thrombus from a blood vessel. The device may comprise at least one microcatheter lumen, the at least one microcatheter lumen having at least two regions of a deployable macrocoil therein, each macrocoil segment being capable of separate deployment along a length of the macrocoil, and each of the at least two deployable macrocoils, when deployed, being capable of being withdrawn from a location by withdrawal of the lumen. The device may have at least one macrocoil segment comprises a macrocoil thrombus engaging component having a length with a proximal end and a distal end, the length of the macrocoil segment comprised of microcoils that allow the length of the macrocoil segment to be extendable and flexible. The device may also have at least two macrocoil segments comprise a macrocoil thrombus engaging component having a length with a proximal end and a distal end, the length of the macrocoil segment comprised of microcoils that allow the length of the macrocoil segment to be extendable and flexible

An alternative structure may comprise a medical device for removing a thrombus from a blood vessel having at least one microcatheter lumen, the at least one microcatheter lumen having at least one region of a distally positioned deployable macrocoil therein with respect to a length of the lumen and a shaped structure proximally positioned with respect to the length of the lumen. For example, the shaped structure may comprise a porous basket element, a porous coil of a different structure than the first macrocoil, a preformed shape or another porous deployable coil structure.

The present technology also includes, a method of capturing a solid object within a vessel in a patient comprising inserting a medical device for removing a solid object from a vessel, the device comprising at least one microcatheter lumen, the at least one microcatheter lumen having at least one region of a distally positioned deployable macrocoil therein with respect to a length of the lumen and a shaped structure proximally positioned with respect to the length of the lumen, the inserting done so that a first at least one deployable microcoil is beyond the solid object and the shaped structure is not beyond the solid object, deploying the first at least one deployable microcoil beyond the solid object to provide a distal engaging element beyond the solid object and deploying the shaped structure not beyond the solid object to form a proximal engaging structure for the solid object. In this method after forming the distal engaging structure and the proximal engaging structure, the device itself or portions thereof may be withdrawn to withdraw the solid object from the vessel or move the solid object within the vessel.

Another method of capturing a solid object within a vessel in a patient comprises inserting a medical device for removing a solid object from a vessel. The device would then comprise at least one microcatheter lumen, the at least one microcatheter lumen having at least two regions of a deployable macrocoil therein, each macrocoil segment being capable of separate deployment along a length of the macrocoil, and each of the at least two deployable macrocoils, when deployed, being capable of being withdrawn from a location by withdrawal of the lumen, the inserting being done so that a first at least one deployable microcoil is beyond the solid object and a second at least one other microcoil is not beyond the solid object, deploying the first at least one deployable microcoil beyond the solid object to provide a distal engaging element beyond the solid object and deploying the second at least one other microcoil not beyond the solid object to form a proximal engaging structure for the solid object. Also in this method, after forming the distal engaging structure and the proximal engaging structure, withdrawing the device or a portion thereof to withdraw the solid object from the vessel or move the solid object within the vessel while the solid object is secured distally and proximally along the direction of movement.

Additionally, as noted elsewhere, the conformability of the macrocoil system of the described technology offers the potential for reduced disruption of a thrombus and the generation of floating clots that could cause a stroke. Although there is never a guarantee of avoiding such issues during medical procedures, at least the potential is there for reducing the likelihood of such potentially disastrous events.

Animal and bench experiments have been performed using the Device. Studies were performed that investigated the removal of both soft and very firm fibrin-laden clot material from the arterial lumens of multiple blood vessels (renal, subclavian, external and internal carotid arteries) in the pig model. Soft clot was only a few hours old. Hard clot was made by allowing a pig's blood to stand for 4-6 days. The firm, fibrin-containing portion separated from the plasma, and the hard clot was embolized into the selected artery of a second pig.

Methodology Summary Study I

A commercially available microcatheter with an inner lumen of 0.018″ was passed beyond the thrombus, specifically between the intima and the thrombus (non-occluded space between the thrombus and the walls). In the case of a firm thrombus, the process was aided by a commercially available 0.014″ microguidewire. A thin nylon line (0.006″) was attached to the distal end of a coil and the coil/string complex gently passed into a microcatheter to a point distal to the thrombus. Alternatively, the coil/string complex was preloaded into the microcatheter that was passed without the aid of a microguidewire past the distal end of the thrombus. The coils were pushed from the microcatheter, which was progressively pulled back until it was proximal to the thrombus and clot extraction attempted, as previously described.

Conclusions Summary Study I

Soft clot tended to be removed easily from the arteries studied because the clot adhered to the meshwork of the coil and the pulling wire of the Device. However, initial experiments with single coils of different sizes, including both 3-D and 2-D coils, demonstrated the inability to consistently and successfully extract the firm clot with this method, even when the coil had formed a mesh around the thrombus and the nylon string was pulled as much as possible to tighten the mesh around the clot. Rather, the coil sometimes simply unraveled from around the thrombus, sliding back into the more proximal microcatheter. It was apparent in those failed circumstances that the loops of the coil were simply wrapping around the clot without becoming tightly engaged and that such a non-structured mesh was insufficient to overcome the combination of forces keeping the thrombus in place, including friction between the thrombus and the intima and blood flow pushing the embolus distally. However, intertwining and/or overlapping of the loops along the distal aspect of the thrombus, as one would tie a shoelace, kept the distal mesh in place without allowing the entire coil complex to unravel.

Methodology Summary Study II

In subsequent experiments, two microcatheters were passed distal to the firm clot, each positioned in the same manner as previously described. The distal end of a 3-D coil was pushed into the arterial lumen from the first microcatheter, then the distal end of a second coil. Either a 2-D or a 3-D configuration was pushed forward from the second microcatheter, allowing loops of the two coils to intertwine. By “two coils” in this description, it is meant that there are two masses of coils, each delivered from a microcatheter. The term includes two coil masses emanating from two lumens of a single microcatheter, as opposed to requiring two distinct microcatheters. Further coils were extended to make a complex, random mesh, and then the nylon strings were pulled so that a tight “cap” or “knot” was formed on the distal surface of the clot. The microcatheters were partially withdrawn and as more coils were pushed from the microcatheter, they passively encircled the middle portions of the clot. The process was continued with more coils (at least a total of two and up to six coils would be used in a preferred range of mesh applications) placed proximal to the clot. The nylon strings were then pulled tightly to form a tight meshwork encircling the entire clot so that little or no fragmentation would occur.

Conclusions Summary Study II

Using this technique, it was possible to successfully extract firm clots from all arteries embolized without evidence of fragmentation on subsequent post-extraction angiography. Coils having diameters equal to or slightly larger than that of the arterial lumen appeared to make the best distal meshwork and therefore, the most stable macrocoil constructs. By then passively encircling the clot, there was no tendency for the distal “cap” to slide from the top over the side of the clot. Post-extraction angiography and post-mortem examination, including microscopy, did not demonstrate any evidence of arterial injury.

Other variations in the materials, designs and processes may be apparent and obvious to those skilled in the art from the generic teaching and examples provided herein.

Claims

1. A device for retrieval of objects from within vessels of patients comprising: a length of microcoil having approximately helical turns continuously or within adjacent sections of the length of microcoil and the helical turns have an average diameter, at least some of the continuous length or the segments sections in the length of microcoil having eyelets that extend beyond the average diameter extending outwardly from the helical turns and defining an axis offset from an axis of the helical turns, and a core wire passing through at least some adjacent eyelets from a distal end to a proximal end of the length of microcoil, the core wire being restrained near the distal end of the length of microcoil.

2. The device of claim 1 wherein the average diameter of the helical turns is less than 0.050 inches.

3. The device of claim 2 carried within a lumen of a microcatheter wherein the lumen internal diameter is greater than the average diameter of the helical turns of the length of microcoil.

4. The device of claim 2 wherein tension applied on the proximal end of the core wire will cause the length of microcoil to form loops outside of the average diameter of the length of microcoil.

5. A device for insertion into a vessel for the removal of at least one solid object from within the vessel, the device comprising: a catheter having a lumen; within the lumen of the catheter is at least: a macrocoil elongate element having an axis and a length, multiple eyelets on the macrocoil elongate element that extend away outwardly from the macrocoil elongate element and define an axis offset from the axis of the macrocoil elongate element, and a core wire extending through at least two of the multiple eyelets; wherein the core wire is attached at a distal point along the length of the macrocoil elongate element, wherein increasing tension on the core wire, which tension is in part guided by the core wire passing through multiple eyelets, causes the macrocoil elongate element to form loops, curves, bundles or a non-linear compressed shape.

6. The device of claim 5 wherein the macrocoil elongate element consists of a) a continuous length of microcoils or b) segments of microcoils separated by eyelets along the length of the macrocoil that elongate element, the continuous length of microcoils or the segments of microcoils add flexibility and conformability to the microcoil macrocoil elongate element.

7. The device of claim 6 wherein the macrocoil elongate element comprises a continuous length of microcoils.

8. The device of claim 7 wherein the eyelets are formed along the length of the macrocoil elongate element by dislocated microcoils extending away from the axis of the macrocoil elongate element and providing openings through which the core wire may pass passes.

9. The device of claim 6 wherein microcoils are positioned within the macrocoil elongate element so that an exterior surface of the microcoils positioned against a thrombus in a vessel will first engage an exterior surface of the thrombus.

10. The device of claim 5 wherein when tension is applied to the core wire, the macrocoil elongate element forms loops along the length of the macrocoil elongate element.

11. The device of claim 10 wherein at least some loops will be formed adjacent at least one eyelet.

12. A medical device for removing a thrombus from a blood vessel, comprising at least one elongated microcatheter lumen, wherein the medical device comprising at least one elongated flexible element microcatheter lumen comprising a) comprises at least one macrocoil comprising with a) a continuous segment of microcoils or b) at least two separate flexible element segments comprising microcoils therein, each the continuous segment or each flexible element segment of the at least one macrocoil being capable of conformation to at least one solid object after deployment from the at least one microcatheter lumen, each segment of the continuous segment or each flexible elements element segment having eyelets extending away from an axis of the continuous segment or the flexible element segments, respectively, and a core wire extending through the eyelets and along an outer surface of the continuous segment or the at least two separate flexible element segments, wherein tension on the core wire causes at least some adjacent eyelets to contract, forming a loop in the continuous segment of microcoils or a flexible element segment of the at least two separate flexible element segments, and the continuous segments or the flexible element segments, when deployed to a location outside of the microcatheter lumen, is capable of being withdrawn from the location outside the microcatheter lumen by withdrawal of the at least one microcatheter lumen.

13. The medical device of claim 12 wherein the at least one flexible element segment consists essentially of a continuous set of microcoils having an axis, the core wire and at least some eyelets are formed by microcoils extending away from the axis of the continuous set of microcoils.

14. The medical device of claim 12 wherein the eyelets are formed on the macrocoil by affixed attached eyelets extending away from the axis.

15. The medical device of claim 12 wherein the core wire is secured to passes through at least some adjacent eyelets.

16. A medical device for removing a thrombus from a blood vessel, comprising at least one microcatheter lumen, the at least one microcatheter lumen having at least one deployable flexible element comprising a macrocoil having sections of microcoils separated by offset microcoils that form eyelets, each section of microcoils being capable of conformation to at least one solid object after deployment from the microcatheter lumen, each eyelet extending away outwardly from the sections of microcoils and defining an axis offset from an axis of the sections of microcoils with a core wire extending through the eyelets, wherein tension on the core wire causes at least some adjacent eyelets to contract towards each other, forming a loop in the flexible element, the loop comprising microcoils, and each of the at least one deployable flexible elements, when deployed to a location outside of the microcatheter lumen, is capable of being withdrawn from the location by withdrawal of the lumen.

17. The medical device of claim 16 wherein the flexible element consists essentially of a continuous set of microcoils having an axis, the core wire and at least some eyelets are formed by microcoils extending away from the axis of the sections of microcoils.

18. The medical device of claim 16 wherein eyelets are form formed on the macrocoil by affixed attached eyelets extending away from the axis of the sections of microcoils.

19. The medical device of claim 16 wherein the core wire is secured to passes through at least some adjacent eyelets.

20. The device of claim 16 wherein microcoils are positioned within the macrocoil so that an exterior surface of the microcoils positioned against the thrombus in the blood vessel will first engage an exterior surface of the thrombus when the loop is drawn against the thrombus.

21. The device of claim 5 wherein the catheter having the lumen consists of a single lumen, the macrocoil elongate element, the multiple eyelets on the macrocoil elongate element, and the core wire extending through at least two of the multiple eyelets within the single lumen.

22. The medical device of claim 16 wherein a microcatheter having the microcathter lumen consists of a single lumen, the macrocoil, the multiple eyelets on the macrocoil, and the core wire extending through at least two adjacent ones of the multiple eyelets within the single lumen.