Embolic protection device with locking device

A device and method for locking onto a guidewire. The device includes an element transversely movable along the guidewire. The element may have a plurality of portions and a biasing member connecting first and second portions of the transversely moveable element such that the first portion and another of the portions are movable from a first position, where the first portion and the other portion are aligned with respect to one another, to a second position, where the first portion is no longer aligned with respect to the other portion, the device being locked to the guidewire in the second position. The device can be used for locking an embolic protection device including a filter to a guidewire that is adapted to be introduced into a vascular system of a patient.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to an embolic protection device and, more particularly, to an embolic protection device with a locking device for releasably locking the embolic protection device onto a guidewire.

2. Description of the Related Art

An embolic protection device includes a filter that captures embolic material released during an interventional procedure for treating stenosis of a patient's blood vessel. Such an embolic protection device is described in U.S. Patent Publication Nos. 2002/0049467 A1, 2002/0026213 A1, 2002/0002384 A1, and 2003/0032977 A1. The entire disclosures of these publications are incorporated herein by reference.

In an embolic protection device, a filter is deployed at a location within the patient's blood vessel which allows it to capture released embolic material. After a stenosis has been treated, the filter is retracted. For example, the embolic filter may abut a stop provided at a distal end of a guidewire. The filter may be pressed against the stop either: by advancing the filter toward the stop using a retrieval catheter, or by retracting the guidewire until the stop abuts the filter. When the filter and stop on the guidewire abut, the stop maintains the position of the filter against the force of the advancing retrieval catheter, thereby allowing the retrieval catheter to move over and collapse the filter. The collapsed filter can then be retracted from the blood vessel.

It would be beneficial to provide an embolic filter that can be used with any guidewire and, in particular, a guidewire that does not have a stop for abutting against the filter, i.e., a so-called “barewire.”

BRIEF SUMMARY OF THE INVENTION

A first aspect of the invention is a device for locking a medical device onto a guidewire. The device includes an element transversely movable along the guidewire, the element having a plurality of portions. The device also includes a biasing member connecting first and second portions of the transversely moveable element. The first portion and another portion of the transversely are movable from a first position, where the first portion and the other portion are aligned with respect to one another, to a second position, where the first portion is cinched, or not aligned with respect to the other portion, and the device is locked to the guidewire.

The first portion may be moved out of alignment with respect to the second portion by, for example, being oriented at an angle with respect to the second portion or being laterally offset with respect to the other portion.

The device may be biased to move from the first position to the second position at a portion of the guidewire having a stiffness less than a predetermined biasing force of the biasing element. This may correspond to a floppy end portion of the guidewire.

One or more of the portions of the transversely moveable element may be cylindrically shaped, and the biasing member may be an elastic member that biases the first and second portions. The elastic member may be one or more elastic elements connecting the first and second portions of the transversely moveable element. For example, the elastic member can be two elastic elements that are aligned with the guidewire in the first position, each elastic element being attached at a first end to the first portion of the transversely moveable element and at a second end to the second portion of the transversely moveable element.

The first and second portions of the transversely moveable element may abut one another with the first portion and/or the second portion having an end shaped to facilitate movement of the first and second portions from the first position to the second position. Specifically, one of the first or second portions may have an end in contact with the other portion that is shaped to provide for limited contact between the first and second portions or a point, or substantially a point, contact between the first and second portions.

The first portion may also include two opposing tabs, each tab provided at an end of the first portion that is adjacent to the second portion and at a position substantially 90 degrees with respect to the elastic element.

Alternatively, the biasing member may be a helical elastic element that is connected between the first and second portions. The first portion can include an inclined proximal end, and the second portion can include an inclined distal end, the inclined proximal end of the first portion being adjacent to the inclined distal end of the second portion.

Each portion of the transversely moveable member may have at least one inclined end, and the portions of may, together, form a substantially cylindrical shape when in the first, aligned position.

In a second aspect of the invention, there is provided an embolic protection device, including a filter and the device for locking a medical device onto a guidewire described above.

Preferably, the filter can include a collapsible filter body adapted for delivery through the vascular system of the patient; the filter body being moveable between a collapsed position, which is capable of movement through the vascular system, and an expanded position, wherein the filter is capable of capturing embolic material while allowing blood to pass through the filter body. The filter body can include an inlet end and an outlet end; the inlet end having inlet openings sized to allow the blood and the embolic material to enter the filter body, and the outlet end having numerous outlet openings sized to allow passage of the blood but to retain the embolic material within the filter body.

In a third aspect of the invention, a method is provided for locking a medical device onto a guidewire. The method includes the steps of advancing a locking device along a relatively stiff portion of the guidewire, wherein first and second portions of an element that is transversely moveable along the guidewire are substantially aligned and are connected by a biasing member; providing the device at a less stiff, or floppy, portion of the guidewire; and biasing either the first portion or the second portion so that one portion of the transversely moveable element is not aligned with respect to the other portion, thereby locking the device on the guidewire.

The one portion of the transversely moveable element may be moved out of alignment by, for example, being oriented at an angle with respect to the second portion or being laterally offset with respect to the other portion.

The method may also include the steps of advancing a retracting device over the locking device so that the first and second portions of the device are again aligned with respect to one another, and retracting the device along the guidewire.

In a fourth aspect of the invention, there is provided a device for locking onto a guidewire, including an element transversely movable along a guidewire, the element comprising a collet portion, the collet portion having a deflectable tooth feature, wherein the tooth feature can be deflected from a first position to a second position, the device being locked to the guidewire in the second position.

The device may include a filter moveable on the guidewire, wherein the guidewire is adapted to be introduced into a vascular system of a patient.

In a fifth aspect of the invention, a method is provided for locking a device onto a guidewire, the guidewire including a stiff portion with a first stiffness and a floppy portion with a second, lesser stiffness. The method includes advancing the device along the stiff portion of the guidewire, the device comprising an element transversely movable along the guidewire, the element comprising a collet portion, the collet portion having at least one deflectable tooth feature, wherein the tooth feature can be deflected from a first position to a second position, the device being locked to the guidewire in the second position; providing the device at the floppy portion of the guidewire; and biasing the tooth element so that the guidewire becomes pinched between the tooth element and an opposing surface of the collet, whereby the device is locked to the guidewire.

In a sixth aspect of the invention, a device is provided for locking onto a guidewire including an element transversely movable along a guidewire, the element comprising a tubular portion, wherein the tubular portion can be deformed from a first position to a second position, the device being locked to the guidewire in the second position.

The device may include a filter moveable on the guidewire, wherein the guidewire is adapted to be introduced into a vascular system of a patient.

In a seventh aspect of the invention, a method is provided for locking a device onto a guidewire, the guidewire including a stiff portion with a first stiffness and a floppy portion with a second, lesser stiffness. The method includes advancing the device along the stiff portion of the guidewire, the device comprising an element transversely movable along the guidewire, the element comprising a tubular portion, wherein the tubular portion can be deformed from a first position to a second position, the device being locked to the guidewire in the second position; providing the device at the floppy portion of the guidewire; and deforming the tubular portion to the second position, so that a lumen of the tubular portion reduces in profile, thereby pinching the guidewire and locking the device to the guidewire.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

While the invention is open to various modifications and alternative forms, specific embodiments thereof are shown by way of examples in the drawings and are described herein in detail. There is no intent to limit the invention to the particular form disclosed.

FIG. 1is a view of an embolic protection device1according to a first exemplary embodiment of the invention. The embolic protection device1includes a filter40and a guidewire lock, or brake200. The structure of the filter40, which is described in detail below, may include a collapsible filter body41, a sleeve43, and a guide olive57. However, the invention is not limited to specific features of the filter40.

A proximal inlet end44(i.e., upstream) of the filter body41includes one or more large inlet openings50, and a distal outlet end47(i.e., downstream) of the filter body41includes many small outlet openings51. The inlet openings50allow both blood and embolic material released during a procedure to enter the filter body41. The outlet openings51allow blood to pass through the filter body41, but the released embolic material is retained in the filter body41.

The filter body41is moveable between a collapsed position (not shown), in which the filter can be delivered through a patient's vascular system and an expanded position (shown inFIG. 1), in which embolic material released during the procedure is captured within the filter body41.

The filter40can also include a sleeve43with a lumen56. When the filter40is advanced into a patient's body via a guidewire100, the guidewire100is positioned within the lumen56. The sleeve43prevents the released embolic material within the filter body41from escaping into the lumen56.

Moreover, the guide olive57may be provided at a distal end47of the filter body41and can be integrally formed with the filter body41. The guide olive57assists with insertion and advancement of the embolic protection device1into the blood vessel.

As shown inFIG. 1, the guidewire lock200can be provided at the distal end of the filter40. However, the invention is not limited in this respect, and the lock200could also be provided at a proximal end of the filter40.

In this exemplary embodiment, the lock200is an element that is transversely moveable along the guidewire100. As shown inFIGS. 2A and 2B, the lock200includes a transversely moveable first portion210, a transversely moveable second portion220, and a biasing member230that connects the first and second portions210,220. The biasing member230may be two elastic elements232,234provided at opposing sides of the first and second portions210,220. Each of the elastic elements232,234is attached at a first end212to the first portion210and at a second end222to the second portion220.

As shown inFIGS. 2A and 2B, the first and second portions210,220can abut against one another. Moreover, at least one of the first and/or the second210,220portions can include openings236at the abutting end of the first and/or second220portions. These openings236provide a point contact240of decreased area, or rocking point, between the first and second portions. This rocking point decreases the stability of the first and second210,220portions when they are aligned with respect to one another. As shown inFIG. 2A, the openings236can be snake-mouth cuts.

The first and second portions210,220can be cylinders made of, for example, a biocompatible metal such as stainless steel, NITNOL, CoCr or Ti. In addition, the cylinders may be made from a hard plastic like polycarbonate, ULTEM, or acrylonitrile butadiene styrene (ABS).

The elastic elements232,234can be extension springs made of, for example, NITNOL, stainless steel, or CoCr. Alternatively, the elastic elements232,234could be made of a polymer with good elasticity, such as latex, silicone, polyurethane, TPE, or PEBAX.

Preferably, the first and second portions210,220each have an inner diameter that is slightly larger than an outer diameter of the guidewire100. For example, in the case of filter designed for a carotid procedure using an 0.014 inch guidewire, the inner diameter of the first and second portions210,220might be about 0.0155 inches, while a wall thickness of the first and second portions210,220might be 0.002-0.003 inches. This would result in first and second portions210,220with an outer diameter between 0.0195 and 0.0215 inches. By this structure, the first and second portions210,220are capable of movement along the guidewire100with the guidewire100provided within the first and second portions210,220.

FIGS. 3-13show an example of delivery and deployment of the embolic protection device1within the patient's blood vessel110in order to treat a stenosed region111.

As shown inFIG. 3, a guidewire100is introduced into the blood vessel110. The guidewire100includes a stiff elongated portion101and a floppy portion102. The floppy portion102is the distal part of the guidewire100and typically makes up about 5-20 cm of the guidewire100, although the invention is not limited in this respect. The floppy portion102includes a part with a stiffness that is less than the biasing force of the elastic elements232,234. Specifically, the floppy portion102can have a stiffness that gradually decreases from a stiffest portion adjacent to the elongated portion101to a floppiest (least stiff) portion at a distal end102A of the guidewire100. Accordingly, there is a point within the area of gradually decreasing stiffness of the floppy portion102where the stiffness of the guidewire100will be less than the biasing force of the elastic elements232,234.

The construction of the distal, floppy portion102varies among guidewire designs, but typically consists of a tapered core wire, made from either stainless steel or NITINOL surrounded by covering, which may be a coil or a polymer coating. The profile of the tapered core wire is typically design specific, but the covering (e.g., coil or polymer coating) typically has an outer diameter that is consistent along the length of the guidewire100. The invention is not limited by the design of the guidewire.

Thereafter, as shown inFIG. 4, the filter40is introduced into the blood vessel110along the guidewire100by a delivery catheter10. The collapsed filter40may be provided within a pod13of the delivery catheter10.

As shown inFIG. 5, when the filter40is advanced to a position distal to the stenosis111, an inner stem of the delivery catheter10is retracted and the filter40expands within the blood vessel110. At this time, the filter40is not fixed to the guidewire100. Thereafter, as shown inFIGS. 6 and 7, the delivery catheter10is withdrawn from the blood vessel110.

Then, a medical device is positioned within the stenosis111. The medical device can be, for example, an atherectomy device, an angioplasty balloon112as shown inFIG. 8, or a stent113as shown inFIG. 9. However, the invention is not limited in this respect. Once the procedure on the stenosed region111of the blood vessel110is completed, as shown inFIG. 10, a retrieval catheter3is advanced toward the filter40. Then, either the retrieval catheter3pushes the filter40toward the floppy portion102of the guidewire100or the guidewire100is retracted toward the filter40.

As shown inFIG. 11, when the lock200at the distal end of the filter40is positioned at the floppy portion102of the guidewire100, a predetermined biasing force of the lock's elastic members232,234overcomes the stiffness of the floppy portion102of the guidewire100. This occurs at the position in the floppy portion102where the guidewire102no longer has enough stiffness to prevent the cylinders from folding over themselves.

Accordingly, the guidewire is biased so that the first and second portions210,220are cinched, or no longer aligned. Therefore, the lock200cannot move in either transverse direction on the guidewire100. Detailed schematics of the biasing of the lock200are shown inFIGS. 14A-15C.

At this time, the lock200, and therefore the filter40, is immovable to the floppy portion102of the guidewire100. Because the filter40is held in place by the lock200, the retrieval catheter3can be advanced over the filter40, thereby collapsing the filter40.

Moreover, as shown inFIG. 12, the retrieval catheter3can be further advanced over the lock200causing the first and second portions210,220of the lock200to become aligned and, therefore, transversely moveable on the guidewire. Then, the filter40and the lock200(i.e., the embolic protection device1) are released from the guidewire100and, as shown inFIG. 13, can be retracted from the blood vessel110. Alternatively, once the filter40is collapsed, the embolic protection device1, which is still immoveable to the guidewire100, can be removed when the guidewire100is retracted.

FIG. 14Ais a schematic view of the embolic protection device1in a first position, in which the first and second portions210,220of the lock200and the biasing member230are aligned with respect to one another and with respect to the guidewire100. At this position, the stiffness of the guidewire100is greater than the biasing force of the biasing member230. Accordingly, the first and second portions210,220are held in an aligned position by the guidewire100and are transversely moveable along the guidewire100.

FIG. 14Bis a schematic view of the embolic protection device1in a second position, in which the first portion210of the lock200is oriented at an angle, and therefore no longer aligned, with respect to the second portion220. At this second position, the predetermined biasing force of the elastic member230overcomes the stiffness of the floppy portion102, causing the first portion210to be moved out of alignment with respect to the second portion220. In this second position, the embolic protection device1is restricted from moving in both transverse directions on the guidewire100. Thus, the embolic protection device1is locked to the guidewire100.

FIG. 15Ashows the lock200in a transversely movable position, which exists when the stiffness of the guidewire100maintains alignment of the first and second portions210,220.FIG. 15Bshows the lock200being biased toward the locked position, which exists when the predetermined biasing force of the elastic member230(i.e., elastic elements232,234) overcomes the stiffness of the floppy portion102of the guidewire100. The first portion210abuts against the second portion220and rotates about the point contact240of the second portion220so that the first portion210is oriented at an angle with respect to the second portion220.FIG. 15Cshows the lock200at a final locked position, which exists when the elastic elements232,234reach a neutral, unbiased state.

FIG. 16is a schematic of a modification of the first exemplary embodiment of the lock200. The lock includes a first portion210, a second portion220, and a biasing member230(indicated by a spring shaped member). The biasing member230is connected between points at ends212,222of the first portion210and second portion220, respectively, and the second portion220includes the point contact240. In this modification, the first modification includes two tabs210′ that are provided at positions that are 90 degrees with respect to the position of the biasing member230. These tabs210′ allow the first portion210to provide a better contact with the floppy portion102of the guidewire100.

FIG. 17Aillustrates the biased movement of the first and second portions210,200if they were not provided on a guidewire100. That is, if the first and second portions210,220were not provided on the guidewire100, the biasing force of the elastic member230would bias the first portion210from an aligned position to a position where the first portion210and the second portion220are parallel to one another.

In contrast,FIG. 17Billustrates the biased movement of the first and second portions210,200of the first embodiment when they are provided on a guidewire100. Although the elastic member230partially overcomes the stiffness of the floppy portion102of the guidewire100, the floppy portion102has some stiffness, which prevents the first portion210from moving to a position where the first portion210and the second portion220are next to one another. As shown in this figure, the lower tab210′ contacts the floppy portion102of the guidewire102, providing a better locking force.

FIG. 18shows the first and second portions210,220provided on a pin, or stylet300. It is expected that, when the embolic protection device1of first exemplary embodiment is packaged for sale, the pin300will be provided within the first and second portions210,220. Thereafter, before use of the filter40and lock200, the guidewire100is provided within the filter40and lock200. The guidewire100will push the pin300out from within the first and second portions210,220, and the filter40and lock200will be properly positioned on the guidewire100for insertion into the patient's body. It is also possible to use a tube in place of the pin, or a tube with an internal stop, that allows the guidewire to be inserted easily, and upon insertion, the guidewire will contact the stop and urge the tube out of the first and second portions, leaving the guidewire disposed within the portions as desired.

FIGS. 19A and 19Bshow a second exemplary embodiment of the lock200′ that can be used with the filter40. In this exemplary embodiment, instead of using an elastic member230that is aligned with respect to the guidewire100in the first, aligned position, a helical elastic member230A is connected between a first portion210A and a second portion220B. The first portion210A includes a proximal end210A′ that is inclined at about 45 degrees, and the second portion includes a distal end220A′ that is inclined at about 45 degrees. The inclined proximal end210A′ of the first portion210A is adjacent to the inclined distal end220A′ of the second portion220A.

That is, as shown inFIG. 19A, when the first portion210A, and second portion220A are provided on the stiff portion101of the guidewire100(i.e., the first position), the inclined ends210A′,220A′ are arranged such that the first and second portions210A,220A form a substantially cylindrical shape. Moreover, as shown inFIG. 19B, when the first portion210A, and second portion220B are provided on the floppy portion102of the guidewire100(i.e., the second position), the biasing force of the elastic member230A overcomes the stiffness of the floppy portion102of the guidewire100. This causes the first portion210A to rotate with respect to the second portion220A.

The rotation of the first portion210A causes the inclined ends210A′,220A′ to be moved to a position in which the first portion210A and second portion220A no longer form a substantially cylindrical shape. That is, as shown inFIG. 19B, the first portion210A and second portion220A are oriented at an angle with respect to one another (i.e., second position). One of ordinary skill will understand that the amount of rotation of the first portion210A depends on the elasticity of the elastic member230A, the stiffness of the floppy portion102, and the positions where the elastic member230A is attached to the first and second portions210A,220A.

Moreover, one or both of the first and second portions210,220could include a structure that prevents the first portion210A from rotating more than 180 degrees. This would prevent the first and second portions210,220from rotating 360 degrees. That is, if the first portion210A is allowed to rotate 360 degrees, the first and second portions210,220would again form an aligned, substantially cylindrical shape and be transversely moveable, rather than locked in place.

FIGS. 20A and 20Bshow a third exemplary embodiment of the lock200″. In this exemplary embodiment, an elastic member230B, a first portion210B, and a second portion220B are aligned with respect to the guidewire100in a first, aligned position. However, unlike the first exemplary embodiment, in this exemplary embodiment, a third portion240B is provided between the first portion210A and the second portion220B.

That is, as shown inFIG. 20A, when the first portion210B, second portion220B, and third portion240B are provided on the stiff portion101of the guidewire100(i.e., the first position), inclined ends210B′,220B′, and240B′ of the portions210B,220B,240B are arranged such that the portions210B,220B,240B form a substantially cylindrical shape. Moreover, as shown inFIG. 20B, when the portions210B,220B,240B are provided on the floppy portion102of the guidewire100(i.e., the second position), the biasing force of the elastic member2301B overcomes the stiffness of the floppy portion102of the guidewire100. This causes the third portion240B to be laterally offset with respect to the other portions2101B,220B. Accordingly, the lock200″ is locked to the guidewire100.

Moreover, as shown inFIG. 20C, the third portion240B can include an additional inclined portion230B′. This inclined portion230B′ provides a surface that first contacts the retrieval catheter3, when the retrieval catheter3is advanced over the filter40in order to re-align the portions210B,220B,240B so that the filter40and lock200″ can be withdraw from the blood vessel110. Accordingly, the retrieval catheter3can easily push the portions210B,220B, and240B back into alignment.

Finally,FIG. 21shows a third exemplary embodiment of the lock200′″ in a non-aligned position. In this exemplary embodiment, the lock200′″ includes several transversely moveable portions310,320,330,340,350that are attached to each other by connection portions315,325,335,345. The transversely moveable portions310,320,330,340,350and connection portions315,325,335,345can be made of a shape memory material, such as NITINOL.

Accordingly, in the non-aligned position (i.e., second position), a shape-memory force of the shape-memory of the transversely moveable portions310,320,330,340,350and connections315,325,335,345overcomes the stiffness of the floppy portion102of the guidewire100. This causes the lock200′″ to be locked in place. In contrast, in an aligned position (i.e., first position), the stiffness of the guidewire100overcomes the shape memory of the shape memory material and aligns the transversely moveable portions310,320,330,340,350in a substantially cylindrical shape. In this first position, the transversely moveable portions310,320,330,340,350, and therefore, the filter40, can move transversely along the guidewire100.

Like the third exemplary embodiment, in this exemplary embodiment, the transversely moveable portions310,320,330,340,350can include inclined portions, which provide surfaces that first contact the retrieval catheter3, when the retrieval catheter3is advanced over the filter40and lock200′″. Accordingly, the retrieval catheter3can easily push the transversely moveable portions310,320,330,340,350back into alignment.

Referring now toFIG. 22, there is shown another embodiment of a lock in accordance with the present invention. In this embodiment, the lock comprises a tubular element500having a first end502and a second end, an inner lumen506and a wall thickness504. The inner lumen506is sized and configured to be disposed on a guidewire100, and the first end502is sized and configured to abut against an end of a filter device600. As a result of the wall504geometry, dimensions, or the material properties, the tubular member is capable of undergoing strain in the axial direction.

Referring now toFIG. 23, when the tubular member is strained in the axial direction, the average lumen diameter decreases. A reduction in average lumen diameter causes the tubular element500to hinder the movement of a guidewire100that it is disposed on, thereby locking it to the guidewire100. Axial strain may be caused, for example, when a guidewire100frictionally engages the inner lumen506in one direction and when a filter device600applies an axial load to the proximal end in one direction.

It is contemplated that the tubular element500may be unlocked by passing a secondary catheter800over the tubular element500. The secondary catheter800has an internal lumen sized and configured to contact the outer surface of the tubular element500, and when it passes over the tubular element500it causes an axial strain in a direction opposite to that strain which caused the tubular element500to lock onto the guidewire100. This reversed strain will unlock the tubular element500.

In accordance with this embodiment, the tubular element500may be constructed of a metal, such as stainless steel, nitinol, CoCr, or any other suitable metal, or it may be constructed of a plastic, such as Pebax, polyurethane, TPE, or any other suitable plastic.

It is contemplated that the use of more rigid materials such as metals may require a tubular element500with a mesh-like construction. The mesh-like construction is intended to expand and contract in diameter when an axial load is applied to the tubular element500. The mesh-like construction may be formed by braiding strands of wire, or by removing material from a solid tube, using fabrication methods such as laser-cutting, micro-machining, photo-etching, or other methods that are well known in the art.

In further accordance with this embodiment, when a mesh-like tubular element500is disposed on a guidewire100, movement of the guidewire100in a distal direction will cause contact between the surface of the tubular element500lumen and the guidewire100. This contact will result in a frictional load that tends to elongate the tubular element500in an axial direction. When a threshold limit of elongation is reached by the tubular element500, the lumen diameter will reduce sufficiently to hinder movement of the guidewire100through the lumen of the tubular element500.

In accordance with the present invention, it will be appreciated that a tubular element500made from a thin-walled elastomeric material, and a mesh-like tubular element500made from a more rigid material may be combined in order to form a tubular element500that hinders movement of a guidewire100in both transverse directions.

Referring now toFIG. 24, there is shown yet another embodiment of the lock in accordance with the present invention. In this embodiment, the lock comprises a collet700having a base and one or more teeth extending from the base in a generally axial direction. The teeth are shown to have a tapered construction, which provides the advantage of improved deliverability; however this is not necessary to the invention. The base includes a first end706, capable of abutting against a filter device600.

The collet teeth704can be deflected in a generally radial direction, and when disposed on a guidewire100, deflecting them in the radially inward direction results in contact between the collet teeth704and the guidewire100. When the guidewire100slides against the teeth in a direction counter to the direction of tooth extension from the base, the collet teeth704are urged radially inward and movement of the guidewire100is inhibited. This locks the collet700to the guidewire100.

In further accordance with this embodiment, the collet teeth704may comprise surfaces that further prevent movement of the guidewire100when the collet700is engaged. For example, the collet surface may be roughened, gnarled, include ridges, or have any other structural elements that would result in a similar effect. Additionally, the collet teeth704may have surfaces formed from a material with a friction of coefficient that is higher than the collet base702material. For example, the collet base702may be formed from stainless steel or Nitinol, while the collet teeth704may include a low durometer polyurethane for its construction.

Referring now toFIG. 25, the collet700may be unlocked from the guidewire100by passing a secondary catheter800between the collet teeth704and the guidewire100. The secondary catheter800is sized to slide within the collet700, and forces the collet teeth704in a radially outward direction, thereby unlocking the collet700.

It will be appreciated that the collet700may be deployed onto the guidewire100by delivering it over the guidewire100on a secondary catheter800to the deployment location. A tertiary catheter sized and configured to be delivered over the secondary catheter800, and having a first end sized to abut the first end of the collet base702can then be advanced over the secondary catheter800. The first end of the tertiary catheter may be pressed against the first end of the collet base702and the collet700is thereby removed from the secondary catheter800, becoming disposed on the guidewire100, as shown inFIG. 24.

The invention is not limited to the exemplary embodiments described above. That is, departures can be made from the exemplary embodiments without departing from the spirit and scope of the invention, which is only limited by the following claims.