Patent Description:
The present disclosure generally relates to a tissue-removing catheter, and more particular, to a drive assembly configured to operatively couple a drive coil to a motor of the tissue-removing catheter.

Tissue-removing catheters are used to remove unwanted tissue in body lumens. As an example, atherectomy catheters are used to remove material from a blood vessel to open the blood vessel and improve blood flow through the vessel. This process can be used to prepare lesions within a patient's coronary artery to facilitate percutaneous coronary angioplasty (PTCA) or stent delivery in patients with severely calcified coronary artery lesions. Atherectomy catheters typically employ a rotating element which is used to abrade or otherwise break up the unwanted tissue.

Document <CIT> relates to a tissue-removing catheter.

Document <CIT> relates to a rotational atherectomy device with exchangeable drive shaft and meshing gears.

In one aspect, a tissue-removing catheter for removing tissue in a body lumen generally comprises a drive assembly including a gear rotatable about an axis, a gear extension coupled to the gear and extending axially outward from the gear, and a lock received in and coupled to the gear extension. The gear extension is configured to be rotatably driven by the gear, and the lock is configured to be rotatably driven by the gear extension. A drive coil is received in and coupled to the lock. The drive coil is configured to be rotatably driven by the lock, whereby rotation of the gear imparts rotation to the drive coil.

In another aspect, a tissue-removing catheter for removing tissue in a body lumen generally comprises a drive assembly including a gear rotatable about an axis. A gear extension is coupled to the gear and extends axially outward from the gear. A lock received in and coupled to the gear extension. The gear extension is configured to be rotatably driven by the gear. The lock is configured to be rotatably driven by the gear extension. An elongate drive member is received in and coupled to the lock. The drive member is configured to be rotatably driven by the lock. Rotation of the gear imparts rotation to the drive member.

Further disclosed herein is a tissue-removing catheter that includes a drive assembly, wherein the drive assembly includes a gear rotatable about an axis, a gear extension coupled to the gear and extending axially outward from the gear, and a lock received in and coupled to the gear extension, wherein the gear extension is rotatably driven by the gear, and the lock is rotatably driven by the gear extension, wherein an elongate drive member is received in and coupled to the lock, and wherein the drive member is driven by the lock, whereby rotation of the gear imparts rotation to the drive coil.

Referring to the drawings, and in particular <FIG>, a rotational tissue-removing catheter for removing tissue in a body lumen is generally indicated at reference number <NUM>. The illustrated catheter <NUM> is a rotational atherectomy device suitable for removing (e.g., abrading, cutting, excising, ablating, etc.) occlusive tissue (e.g., embolic tissue, plaque tissue, atheroma, thrombolytic tissue, stenotic tissue, hyperplastic tissue, neoplastic tissue, etc.) from a vessel wall (e.g., coronary arterial wall, etc.). The catheter <NUM> may be used to facilitate percutaneous coronary angioplasty (PTCA) or the subsequent delivery of a stent. Features of the disclosed embodiments may also be suitable for treating chronic total occlusion (CTO) of blood vessels, and stenoses of other body lumens and other hyperplastic and neoplastic conditions in other body lumens, such as the ureter, the biliary duct, respiratory passages, the pancreatic duct, the lymphatic duct, and the like. Neoplastic cell growth will often occur as a result of a tumor surrounding and intruding into a body lumen. Removal of such material can thus be beneficial to maintain patency of the body lumen.

The catheter <NUM> is sized for being received in a blood vessel of a subject. Thus, the catheter <NUM> may have a maximum size of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> French (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>) and may have a working length of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM> depending of the body lumen. While the remaining discussion is directed toward a catheter for removing tissue in blood vessels, it will be appreciated that the teachings of the present disclosure also apply to other types of tissue-removing catheters, including, but not limited to, catheters for penetrating and/or removing tissue from a variety of occlusive, stenotic, or hyperplastic material in a variety of body lumens.

Referring to <FIG> and <FIG>, the catheter <NUM> comprises an elongate drive member <NUM> and an elongate inner liner <NUM> received in and extending along the drive member. In the illustrated embodiment, the elongate drive member <NUM> comprises a drive coil indicated by the same reference numeral <NUM>. The drive coil <NUM> and inner liner <NUM> extend along a longitudinal axis LA of the catheter from a proximal end portion <NUM> to a distal end portion <NUM> of the catheter. A tissue-removing element <NUM> (e.g., an abrasive burr) is disposed on a distal end of the drive coil <NUM> and is configured for rotation to remove tissue from a body lumen as will be explained in greater detail below. An isolation sheath <NUM> (<FIG>) is disposed around the drive coil <NUM>. The drive coil <NUM> and the inner liner <NUM> are both configured to translate relative to the isolation sheath <NUM>. The catheter <NUM> is sized and shaped for insertion into a body lumen of a subject. The isolation sheath <NUM> isolates the body lumen from at least a portion of the drive coil <NUM> and inner liner <NUM>. The inner liner <NUM> defines a guidewire lumen <NUM> (<FIG>) for slidably receiving a guidewire <NUM> therein so that the catheter <NUM> can be advanced through the body lumen by traveling along the guidewire. The guidewire can be a standard <NUM> (<NUM>-inch) outer diameter, <NUM> length guidewire. In certain embodiments, the inner liner <NUM> may have a lubricious inner surface for sliding over the guidewire <NUM> (e.g., a lubricious surface may be provided by a lubricious polymer layer or a lubricious coating). In the illustrated embodiment, the guidewire lumen <NUM> extends all the way through the length of the inner liner <NUM> such that the guidewire <NUM> is extendable along an entire working length of the catheter <NUM>. In one embodiment, the overall working length of the catheter <NUM> may be between about <NUM> (<NUM> inches) and about <NUM> (<NUM> inches). In use, the guidewire <NUM> may extend about <NUM> (<NUM> inches) past a distal end of the inner liner <NUM>.

Referring to <FIG>, the tissue-removing element <NUM> extends along the longitudinal axis LA from a proximal end adjacent the distal end portion of the drive coil <NUM> to an opposite distal end. Any suitable tissue-removing element for removing tissue in the body lumen as it is rotated may be used in one or more embodiments. In one embodiment, the tissue-removing element <NUM> comprises an abrasive burr configured to abrade tissue in the body lumen. The abrasive burr <NUM> may have an abrasive outer surface formed, for example, by a diamond grit coating, surface etching, or the like. In one embodiment, the tissue-removing element comprises a stainless steel spheroid body with an exterior surface including <NUM> of exposed diamond crystals. The tissue-removing element <NUM> may also be radiopaque to allow the tissue-removing element to be visible under fluoroscopy. In other embodiments, the tissue-removing element can comprise one or more cutting elements having smooth or serrated cutting edges, a macerator, a thrombectomy wire, etc. A suitable tissue-removing element is described in <CIT>.

Referring to <FIG> and <FIG>, the drive coil <NUM> may comprise a tubular stainless steel coil configured to transfer rotation to the tissue-removing element <NUM>. Configuring the drive coil <NUM> as a coiled structure provides the drive coil with a flexibility that facilitates delivery of the catheter <NUM> through the body lumen. In addition, the coil configuration allows for the rotation and torque of the drive coil <NUM> to be applied to the tissue-removing element <NUM> when the catheter <NUM> is traversed across a curved path. The stiffness of the drive coil <NUM> also impacts the ease at which the coil is traversed through the body lumen as well as the coil's ability to effectively transfer torque to the tissue-removing element <NUM>. In one embodiment, the drive coil <NUM> is relatively stiff such that axial compression and extension of the coil is minimized during movement of the catheter <NUM> through a body lumen. The coil configuration of the drive coil <NUM> is also configured to expand its inner diameter when the coil is rotated so that the drive coil remains spaced from the inner liner <NUM> during operation of the catheter <NUM>. In one embodiment, the drive coil <NUM> has an inner diameter of about <NUM> inches (<NUM>) and an outer diameter of about <NUM> inches (<NUM>). The drive coil <NUM> may have a single layer construction. For example, the drive coil may comprise a <NUM> filar (i.e., wire) coil with a lay angle of about <NUM> degrees. Alternatively, the drive coil <NUM> could be configured from multiple layers without departing from the scope of the disclosure. For example, the drive coil <NUM> may comprise a base coil layer and a jacket (e.g., Tecothane™) disposed over the base layer. In one embodiment, the drive coil comprises a <NUM> filar coil with a lay angle of about <NUM> degrees. The Tecothane™ jacket may be disposed over the coil. Alternatively, the drive coil <NUM> may comprise a dual coil layer configuration which also includes an additional jacket layer over the two coil layers. For example, the drive coil may comprise an inner coil layer comprising a <NUM> filar coil with a lay angle of about <NUM> degrees, and an outer coil layer comprising a <NUM> filar coil with a lay angle of about <NUM> degrees. Drive coils having other configurations are also envisioned. A suitable drive coil is described in <CIT>.

Referring to <FIG> and <FIG>, the inner liner <NUM> may comprise a multiple layer tubular body configured to isolate the guidewire <NUM> from the drive coil <NUM> and tissue-removing element <NUM>. The inner liner <NUM> has an inner diameter that is sized to pass the guidewire <NUM>. The inner liner <NUM> protects the guidewire from being damaged by the rotation of the drive coil <NUM> by isolating the guidewire from the rotatable drive coil. The inner liner <NUM> may also extend past the tissue-removing element <NUM> to protect the guidewire <NUM> from the rotating tissue-removing element. Thus, the inner liner <NUM> is configured to prevent any contact between the guidewire <NUM> and the rotating components of the catheter <NUM>. Therefore, any metal-to-metal engagement is eliminated by the inner liner <NUM>. This isolation of the drive coil <NUM> and tissue-removing element <NUM> from the guidewire <NUM> also ensures that the rotation of the drive coil and tissue-removing element is not transferred or transmitted to the guidewire. As a result, a standard guidewire <NUM> can be used with the catheter <NUM> because the guidewire does not have to be configured to withstand the torsional effects of the rotating components. Additionally, by extending through the tissue-removing element <NUM> and past the distal end of the tissue-removing element, the inner liner <NUM> stabilizes the tissue-removing element by providing a centering axis for rotation of the tissue-removing element about the inner liner. In one embodiment, the inner liner <NUM> has an inner diameter ID of about <NUM> inches (<NUM>), an outer diameter OD of about <NUM> inches (<NUM>), and a length of about <NUM> inches (<NUM>). The inner diameter ID of the inner liner <NUM> provides clearance for the standard <NUM>-inch guidewire <NUM>. The outer diameter OD of the inner liner <NUM> provides clearance for the drive coil <NUM> and tissue-removing element <NUM>. Having a space between the inner liner <NUM> and the drive coil <NUM> reduces friction between the two components as well as allows for saline perfusion between the components. A suitable inner liner is described in<CIT>.

Referring to <FIG>, <FIG> and <FIG>, the catheter <NUM> further comprises a handle <NUM> secured at a proximal end of the isolation sheath <NUM>. The handle <NUM> comprises a housing <NUM> that supports the components of the handle. The housing <NUM> has a generally elongate egg shape and includes as plurality of housing sections secured together to enclose the internal components of the handle <NUM>.

Referring to <FIG>, and <FIG>, the housing <NUM> supports an actuator <NUM> (e.g., a lever, a button, a dial, a switch, or other device) configured for selectively actuating a motor <NUM> disposed in the handle to drive rotation of the drive coil <NUM>, and a tissue-removing element <NUM> mounted at the distal end of the drive coil. The motor <NUM> is configured to rotate the drive coil <NUM> and tissue-removing element <NUM> at speeds of greater than about <NUM>,<NUM> RPM. The motor <NUM> is coupled to the drive coil <NUM> by a gear assembly <NUM> and drive assembly <NUM> supported within the housing <NUM>. The gear assembly <NUM> comprises a gearbox housing <NUM> that mounts and at least partially encloses a pair of gears (e.g., driver gear <NUM> and drive gear <NUM>) for transferring the rotation of a shaft of the motor <NUM> to the drive coil <NUM>. The gearbox housing <NUM> includes a motor sleeve <NUM> on a proximal side of the housing that receives a distal end portion of the motor <NUM>, and a tube sleeve portion <NUM> on the proximal side of the housing that receives a distal end portion of a buckle tube <NUM>. The gearbox housing <NUM> attaches to a carriage or advancer frame <NUM> (<FIG>) for moving the motor <NUM> and gear assembly <NUM> within the housing <NUM>, as explained below. The driver gear <NUM> is attached to the motor shaft (not shown) such that the driver gear rotates with the motor shaft when the motor <NUM> is activated. The driven gear <NUM> meshes with the driver gear <NUM> so that rotation of the driver gear causes the driven gear to rotate in the opposite direction. As described below, the drive assembly <NUM> attaches the driven gear <NUM> to the drive coil <NUM> so that the rotation of the driven gear causes the drive coil to rotate. A controller <NUM> (<FIG>) may be provided in the handle <NUM>. The controller <NUM> may be programmed to control operation of the catheter. A suitable construction of gearbox housing <NUM>, the carriage <NUM>, the controller <NUM>, the buckle tube <NUM>, and other related components and structures are described in <CIT>.

It is understood that other suitable actuators, including but not limited to touchscreen actuators, wireless control actuators, automated actuators directed by a controller, etc., may be suitable to selectively actuate the motor in other embodiments. In some embodiments, a power supply may come from a battery (not shown) contained within the handle <NUM>. The battery can provide the current source for the guidewire detection circuit. In other embodiments, the power supply may come from an external source.

Referring to <FIG> and <FIG>, a slide or advancer <NUM> is positioned on the handle <NUM> and is operatively coupled to the drive coil <NUM> for movement of the drive coil relative to the handle to advance and retract the drive coil and tissue-removing element <NUM>. In the embodiment shown in <FIG> and <FIG>, the actuator <NUM> is coupled to the advancer <NUM>, although the actuator may be separate from the advancer such as shown schematically in <FIG>. As shown in <FIG> and <FIG>, the housing <NUM> of the handle <NUM> may define a slot <NUM> which limits the movement of the slide <NUM> relative to the handle. Thus, the length of the slot determines the amount of relative movement between the drive coil <NUM> and the handle <NUM>. In one embodiment, the slot has a length of about <NUM> (<NUM> inches). The slide <NUM> is operatively attached to the motor and drive assembly. In particular, the illustrated slide <NUM> is operatively attached to the advancer frame <NUM> so that movement of the slide causes movement of the advancer frame, thus in turn, axial movement of at least the motor <NUM>, the gear assembly <NUM>, the drive assembly <NUM>, the drive coil <NUM>, and the tissue-removing element <NUM>. In the illustrated embodiment, the advancer <NUM> also advances the liner <NUM> simultaneously with the other components. A suitable construction of the slide or advancer is described in <CIT>.

Referring to <FIG> and <FIG>, the drive assembly <NUM> comprises a gear extension <NUM> (e.g., a gear insert) coupled to the driven gear <NUM> (the driven gear may be considered part of the drive assembly), and a lock <NUM> (e.g., an insert) received in the gear extension. In one embodiment, the gear extension <NUM> is press fit into the driven gear <NUM>. Alternatively, the gear extension <NUM> may be formed integrally with the driven gear <NUM>. The gear extension <NUM> has a proximal portion <NUM> extending proximally (and axially) outward from the driven gear <NUM>, and a distal portion <NUM> extending distally (and axially) from the driven gear. A proximal portion <NUM> comprises a cylindrical member having a uniform outer diameter extending along its length, although it may have other shapes. The proximal portion <NUM> may be supported by (e.g., received in) one or more bearings <NUM> (e.g., roller bearings; <FIG>) to facilitate rotation of the driving assembly <NUM> about the axis LA. The proximal portion <NUM> defines an axial passage <NUM> having a polygonal (e.g., generally rectangular) cross section and extending axially through the proximal and distal ends of the proximal portion. As seen best in <FIG>, a pair of arcuate ribs <NUM> project proximally outward from the proximal end of the gear extension <NUM>. The arcuate ribs <NUM> facilitate molding gates during manufacturing.

The distal portion <NUM> of the gear extension <NUM> comprises a pair of snap-fit cantilever arms <NUM> spaced apart and generally opposing one another. Axially-extending alignment slots or grooves <NUM> are defined between the cantilever arms <NUM> and generally oppose one another. In the illustrated embodiment, the cantilever arms <NUM> are resiliently deflectable away from one another and relative to the drive gear and the distal portion <NUM>. Each cantilever arm <NUM> defines a snap opening <NUM> (e.g., slot, groove, recess, depression, through opening, blind opening, etc.) configured to receive a detent of the lock <NUM>, as described below. Ramp surfaces <NUM> on interior sides of the arms <NUM> lead to the respective openings <NUM> and are configured to facilitate entry of the lock between the arms and guide the detents into the respective snap opening <NUM>. The gear extension <NUM> may be formed from any suitable material including without limitation, stainless steel and Peek.

Referring to <FIG>, the lock <NUM> comprises an elongate lock body <NUM> having proximal and distal end ends, detents <NUM> (e.g., catches, beads, hooks, bumps, or other projections; see <FIG>, <FIG>, <FIG>, and <FIG>) at the distal end of the lock body, and tongues <NUM> (see <FIG> and <FIG>) at the distal end of the lock body. The lock <NUM> (e.g., the lock body <NUM>) defines a lock passage <NUM> extending axially through the proximal and distal ends thereof. As explained below, at least a portion of the coil passage <NUM> is sized and shaped to receive (e.g., slidably receive) the drive coil <NUM> therein. The lock body <NUM> has a polygonal (e.g., generally rectangular) cross section and is sized and shaped to be inserted (e.g., slid) into the gear extension <NUM> (and the axial passage <NUM>) through the distal portion <NUM>. The relative dimensions and shapes of the corresponding cross sections of the lock body <NUM> and the axial passage <NUM> are such that the two are inhibited from substantially rotating relative to one another as the driven gear <NUM> rotates the gear extension <NUM>. More specifically, the interior of the proximal portion <NUM> defining the passage <NUM> will engage the lock body <NUM> during rotation of the gear extension by the drive gear <NUM>, thereby transferring torque from the gear extension to the lock body <NUM>. The transfer of torque may be distributed along at least majority of the axial length of the lock body, such as at least about <NUM>% or at least about <NUM>%, or at least about <NUM>%, or at least about <NUM>%, or about an entirety of the axial length. Accordingly, rotation of the driven gear <NUM> and the gear extension <NUM> about the common axis imparts rotation of the lock body <NUM>.

In the illustrated embodiment, the detents <NUM> are on opposite sides of the lock body <NUM>, and the tongues <NUM> are also on opposite sides of the lock body, such that the tongues are generally disposed between the detents around the exterior of the lock body. The illustrated detents <NUM> are configured to engage the cantilever arms <NUM> as the lock <NUM> is inserted into the distal portion <NUM>. The illustrated detents <NUM> are generally rigid and generally do not deflect when engaging the arm <NUM>. Instead, the detents <NUM> impart resilient deflection of the arms <NUM> away from one another as the lock <NUM> is inserted into the distal portion <NUM>. The detents <NUM> have proximal surfaces which are chamfered or beveled to facilitate the insertion of the detents <NUM> and the distal end portion of the lock <NUM> between the arms <NUM>. Continued insertion of the lock <NUM> moves the detents <NUM> into respective snap openings <NUM>, whereupon the arm <NUM> snap back into their initial, non-deflected positions. In this configuration, the detents <NUM> are captured in the respective snap openings <NUM>, and the lock is coupled to the gear extension <NUM>. During insertion, the tongues <NUM> facilitate alignment by entering and sliding axially into respective grooves <NUM> of the distal portion <NUM>. When the lock <NUM> and the gear extension <NUM> are coupled to one another, the tongues <NUM> function as stops to inhibit further proximal sliding of the lock relative to the gear extension, while the distal edges of the detents <NUM> engage respective distal interior sides defining the snap openings <NUM> to inhibit distal sliding of the lock relative to the gear extension.

The lock <NUM> is fixedly coupled to the drive coil <NUM>, such as by adhesive, welding, mechanical fixing, or in other ways. In the illustrated embodiment, the lock <NUM> is configured to be welded on the drive coil <NUM>. In such an embodiment, the lock <NUM> may be formed from metal, such as stainless steel, or other material suitable for welding to the drive coil <NUM>. As shown in <FIG>, a proximal portion of the drive coil <NUM> received in the lock passage <NUM> is welded to the lock <NUM> at a location that is between the proximal and distal ends of the lock and spaced apart from each of the proximal and distal ends thereof. Preferably, the drive coil <NUM> is welded more adjacent to the proximal end of the lock body <NUM> while still being spaced distally from the proximal end, such as from about <NUM> in to about <NUM> in, or from about <NUM> in to about <NUM> in (or other distances), so that the weld is not exposed at the proximal end of the lock body. In one example, the lock body <NUM> defines at least one transverse welding aperture <NUM> (e.g., one, two, three, four, or more) extending generally transversely through (e.g., radially) through the lock body relative to the coil passage <NUM>.

In the illustrated embodiment, the lock body <NUM> defines four welding apertures <NUM> (e.g., generally round apertures), spaced around the body, with each aperture extending through a respective one of the four sides of the body. It is understood that the one or more apertures may be other shapes, such as slot shaped extending circumferentially, rectangular, oval or other shapes and sizes. The illustrated welding apertures <NUM> are configured to receive a welding tip (e.g., a tip of a laser welder or arc welder; not shown), which directs welding energy (i.e., heat) toward a portion of the lock body <NUM> and an adjacent portion of the coil drive <NUM> to weld the two portions to one another. It is understood that the welding tip of the welder may not be received in the welding aperture, but in either embodiment, the welding energy is directed into the welding aperture to weld the lock body <NUM> to the drive coil <NUM>. Referring to <FIG>, as illustrated, each welding aperture <NUM> includes a radially outer bore <NUM> and a radially inner counterbore <NUM>. An interior shoulder or flange <NUM> (e.g., an annular shoulder or flange) of the lock body <NUM> is disposed at a radially inner end of the welding aperture <NUM>. The welding tip of the welder may direct welding energy toward the at least a portion of the interior shoulder <NUM> (e.g., a proximal portion) to heat the shoulder and the adjacent portion of the drive coil <NUM>, thereby welding the two to one another at the weld location. A cross section of a weld location is shown in <FIG>.

In the illustrated embodiment, shown in <FIG> and <FIG>, the proximal end of the drive coil <NUM> is spaced distally from the proximal end of the lock <NUM> and the lock passage <NUM>. In one example, the lock body <NUM> defines an internal coil stop <NUM> (see also <FIG>) spaced distally from the proximal end of the lock <NUM> to inhibit further movement of the drive coil proximally beyond the stop in the lock passage <NUM>. In the illustrated embodiment, as shown in <FIG>, the coil stop <NUM> is shoulder at the intersection of a coil-receiving portion <NUM> (i.e., distal portion) of the lock passage having a first cross-sectional dimension (e.g., a first diameter), and a liner-receiving portion <NUM> (i.e., a proximal portion) of the lock passage having a second cross-sectional dimension (e.g., a second diameter) which is less than the first cross-sectional dimension. The drive coil <NUM> is received in the coil-receiving portion and the proximal end of the drive coil generally abuts the stop or shoulder <NUM> and is inhibited from entering the liner-receiving portion. The shoulder <NUM> may be an annular shoulder and may be beveled or chamfered so that there are no perpendicular or acute edges of the lock body <NUM> leading from the liner-receiving portion to the interior of the guidewire. The smaller cross-sectional dimension of the liner-receiving portion facilitates alignment of the liner <NUM> in the drive coil <NUM> and the lock body <NUM>. The proximal end of the lock body <NUM> may also be chamfered or beveled or filleted, as illustrated, to facilitate insertion of the liner <NUM> into the liner-receiving potion of the lock passage <NUM>.

In an exemplary method of making the tissue-removing catheter, the drive coil <NUM> is inserted into and welded to the lock <NUM>, such as describe above. The lock <NUM>, with the drive coil <NUM> welded thereto, is then inserted into the distal portion <NUM> of the gear extension <NUM> and snap-fit coupled thereto when the detents <NUM> enter the snap opening <NUM> of the cantilever arms <NUM> to effectively couple the drive coil <NUM> to the drive assemble <NUM>.

Referring to <FIG>, to remove tissue in the body lumen V of a subject, a practitioner inserts the guidewire <NUM> into the body lumen of the subject, to a location distal of the tissue L that is to be removed. Subsequently, the practitioner inserts the proximal end portion of the guidewire <NUM> through the guidewire lumen <NUM> of the inner liner <NUM> and through the handle <NUM> so that the guidewire extends through the proximal end of the handle. With the catheter <NUM> loaded onto the guidewire <NUM>, the practitioner advances the catheter <NUM> along the guidewire until the tissue-removing element <NUM> is positioned proximal and adjacent the tissue L. While the tissue-removing element <NUM> is rotating, the practitioner may selectively move the drive coil <NUM> distally along the guidewire <NUM> to abrade the tissue and, for example, increase the size of the passage through the body lumen V. The practitioner may also move the drive coil <NUM> proximally along the guidewire <NUM>, and may repetitively move the component in distal and proximal directions to obtain a back-and-forth motion of the tissue-removing element <NUM> across the tissue. During the abrading process, the inner liner <NUM> isolates the guidewire <NUM> from the rotating drive coil <NUM> and tissue-removing element <NUM> to protect the guidewire from being damaged by the rotating components. As such, the inner liner <NUM> is configured to withstand the torsional and frictional effects of the rotating drive coil <NUM> and tissue-removing element <NUM> without transferring those effects to the guidewire <NUM>. When the practitioner is finished using the catheter <NUM>, the catheter can be withdrawn from the body lumen V and unloaded from the guidewire <NUM> by sliding the catheter proximally along the guidewire. The guidewire <NUM> used for the abrading process may remain in the body lumen V for use in a subsequent procedure.

When introducing elements of the present disclosure or the one or more embodiment(s) thereof, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of the elements.

Claim 1:
A tissue-removing catheter (<NUM>) for removing tissue in a body lumen, the tissue-removing catheter (<NUM>) comprising:
a drive assembly (<NUM>) including a gear (<NUM>) rotatable about an axis, a gear extension (<NUM>) coupled to the gear (<NUM>) and extending axially outward from the gear (<NUM>), and a lock (<NUM>) received in and coupled to the gear extension (<NUM>), wherein a distal portion (<NUM>) of the gear extension (<NUM>) comprises a pair of snap-fit cantilever arms (<NUM>) spaced apart and generally opposing one another, wherein each cantilever arm (<NUM>) defines a snap opening (<NUM>) configured to receive a detent (<NUM>) of the lock (<NUM>), wherein the gear extension (<NUM>) is configured to be rotatably driven by the gear (<NUM>), and the lock (<NUM>) is configured to be rotatably driven by the gear extension (<NUM>); and
an elongate drive member (<NUM>) received in and coupled to the lock (<NUM>), wherein the drive member is configured to be rotatably driven by the lock (<NUM>), whereby rotation of the gear (<NUM>) imparts rotation to the drive member.