Patent Description:
The present disclosure generally relates to a tissue-removing catheter, and more particular, to an isolation liner for a 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.

<CIT> describes a tissue-removing catheter with guidewire detection sensor. <CIT> describes a tissue-removing catheter including a turbine.

An aspect of the present disclosure provides a tissue-removing catheter for removing tissue in a body lumen. The tissue-removing catheter includes an elongate body, a tissue-removing element, and an inner liner. The elongate body has an axis and proximal and distal end portions spaced apart from one another along the axis. The elongate body is sized and shaped to be received in the body lumen. The tissue-removing element is mounted on the distal end portion of the elongate body and is configured to remove tissue as the tissue-removing element is rotated by the elongate body within the body lumen. The inner liner is received within the elongate body and defines a guidewire lumen. The inner liner isolates an interior of the guidewire lumen from the elongate body and tissue-removing element such that a torsional force is not transferred from the elongate body and tissue-removing element to the interior of the guidewire lumen when the elongate body and tissue-removing element are rotated during operation of the tissue-removing catheter. The inner liner includes a distal end margin configured to extend distally of the tissue-removing element. The distal end margin may have a construction different from a construction of a second portion of the inner liner, which the second portion is positioned proximal of the distal end margin. The distal end margin may be more flexible than the second portion of the inner liner.

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 on 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>, the catheter <NUM> comprises an elongate drive coil <NUM> (broadly, an elongate body) disposed around an elongate inner liner <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> 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> 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>-inch (<NUM>) 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 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 by an extension distance, e.g. about <NUM> (<NUM> inches), past a distal end of the inner liner <NUM>.

Referring to <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 a plurality of housing sections secured together to enclose the internal components of the handle <NUM>. In the illustrated embodiment, the housing <NUM> includes a bottom housing section 41A, a middle housing section 41B secured to the top of the bottom housing section, and a top housing section 41C secured to the top of the middle housing section. In one embodiment, the bottom housing section 41A is removable from the middle housing section 41B to provide access to the components of the handle <NUM> in the interior of the housing <NUM> by a user. It will be understood that the housing <NUM> can have other shapes and configurations without departing from the scope of the disclosure.

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 the 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. In one embodiment, the motor <NUM> rotates the drive coil <NUM> and tissue-removing element <NUM> between about <NUM>,<NUM> and about <NUM>,<NUM> RPM.

The motor <NUM> is coupled to the drive coil <NUM> by a gear assembly <NUM> and a 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 for transferring the rotation of a shaft of the motor <NUM> to the drive coil <NUM>. The gearbox housing <NUM> also attaches to a carriage or advancer frame <NUM> for moving the motor <NUM> and gear assembly <NUM> within the housing <NUM>. Further, attaching the gearbox housing <NUM> to the distal end of the advancer frame <NUM> secures the motor <NUM> in the advancer frame so that the motor moves along with the advancer frame. A driver gear <NUM> is attached to the motor <NUM> such that the driver gear rotates with the motor shaft when the motor <NUM> is activated (<FIG>). A driven gear <NUM> is in mesh with the driver gear <NUM> so that rotation of the driver gear causes the driven gear to rotate in the opposite direction. 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> may be provided in the handle <NUM>. The controller <NUM> may be programmed to control operation of the catheter.

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>, <FIG>, and <FIG>, a slide or advancer <NUM> is positioned on the handle <NUM> and is operatively coupled to the inner liner <NUM> for movement of the inner liner relative to the handle to advance and retract the inner liner, drive coil <NUM>, and tissue-removing element <NUM>. 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 <NUM> determines the amount of relative movement between the inner liner <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 advancer frame <NUM> so that movement of the slide causes movement of the advancer frame. The advancer frame <NUM> comprises an arch shaped body configured to slidingly receive the cylindrically shaped motor <NUM>. Bearings <NUM> (<FIG>) are mounted on the frame <NUM>. The bearings <NUM> engage the housing <NUM> so that the bearings can slide along the housing to facilitate movement of the frame <NUM> in the housing.

Referring to <FIG> and <FIG>, the isolation sheath <NUM> comprises a tubular sleeve configured to isolate and protect a subject's arterial tissue within a body lumen from the rotating drive coil <NUM>. The isolation sheath <NUM> is fixed to the handle <NUM> at a proximal end of the sheath and does not rotate. The isolation sheath <NUM> provides a partial enclosure for the drive coil <NUM> and inner liner <NUM> to move within the sheath. The inner diameter of the isolation sheath <NUM> is sized to provide clearance for the drive coil <NUM>. The space between the isolation sheath <NUM> and the drive coil <NUM> allows for the drive coil to rotate within the sheath and provides an area for saline perfusion between the sheath and drive coil. The outer diameter of the isolation sheath <NUM> is sized to provide clearance with an inner diameter of a guide catheter (not shown) for delivering the catheter <NUM> to the desired location in the body lumen. In one embodiment, the isolation sheath <NUM> has an inner diameter of about <NUM> inches (<NUM>), an outer diameter of about <NUM> inches (<NUM>), and a length of about <NUM> (<NUM> inches). The isolation sheath <NUM> can have other dimensions without departing from the scope of the disclosure. In one embodiment, the isolation sheath <NUM> is made from Polytetrafluorethylene (PTFE). Alternatively, the isolation sheath <NUM> may comprise a multi-layer construction. For example, the isolation sheath <NUM> may comprise an inner layer of perfluoroalkox (PFA), a middle braided wire layer, and an outer layer of Pebax.

Referring to <FIG>, the drive coil <NUM> may comprise a tubular stainless steel coil configured to transfer rotation and torque from the motor <NUM> to the tissue-removing element <NUM>. Configuring the drive coil <NUM> as a coiled structure 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 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.

Referring to <FIG> and <FIG>, the inner liner <NUM> comprises 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> is extendable through the handle <NUM> from a position within the handle to a position distal of the handle. In one embodiment, the inner liner <NUM> is coupled to the components within the handle <NUM> but is not fixedly attached to the housing <NUM> to allow translation of the inner liner relative to the housing. In another embodiment, the inner liner <NUM> is fixedly coupled to components within the handle <NUM> to prevent translation of the inner liner relative to the housing <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> can be 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 the inner liner <NUM> through the tissue-removing element <NUM> and past the distal end of the tissue-removing element, the inner liner stabilizes the tissue-removing element by providing a centering member or axis for rotation of the tissue-removing element.

In the illustrated embodiment, the inner liner <NUM> comprises an inner PTFE layer <NUM> an intermediate braided layer <NUM> comprised of stainless steel, and an outer layer <NUM> of polyimide (<FIG>). The PTFE inner layer <NUM> provides the inner liner <NUM> with a lubricous interior which aids in the passing of the guidewire <NUM> through the inner liner. The braided stainless steel intermediate layer <NUM> provides rigidity and strength to the inner liner <NUM> so that the liner can withstand the torsional forces exerted on the inner liner by the drive coil <NUM>. In one embodiment, the intermediate layer <NUM> is formed from <NUM> stainless steel. The outer polyimide layer <NUM> provides wear resistance as well as having a lubricous quality which reduces friction between the inner liner <NUM> and the drive coil <NUM>. Additionally, a lubricious film, such as silicone, can be added to the inner liner <NUM> to reduce friction between the inner liner and the drive coil <NUM>. In one embodiment, the inner layer <NUM>, intermediate layer <NUM>, and outer layer <NUM> extend along an entire length of the inner liner <NUM>. In one embodiment, at least a portion <NUM> (<FIG>) of the inner liner <NUM> that extends distally of the tissue-removing element <NUM> is free of at least one of the inner layer <NUM>, intermediate layer <NUM>, or outer layer <NUM>, or a material of at least one of the inner layer, intermediate layer, or outer layer. For example, the portion <NUM> of the inner liner <NUM> may be free of the intermediate layer <NUM> of stainless steel, or generally free of a braided or stainless steel layer/material. In this embodiment, removing the stainless steel layer from the distal end margin of the inner liner <NUM> increases the flexibility of the inner liner at the distal end margin which facilitates traversing the inner liner through the body lumen of the subject. The portion <NUM> (e.g., the more flexible distal end margin) also facilitates tracking the catheter <NUM> on the guidewire and centering the liner <NUM> and tissue-removing element <NUM> within a lesion in the body lumen for abrading the lesion. Having the more flexible distal end margin <NUM> of the inner liner <NUM> also eliminates the need to attach a separate structure, such as an atraumatic tip, to a distal end of the inner liner. In the illustrated embodiment, the portion <NUM> extends from a distal end of the inner liner <NUM> and along only a part of the length of the inner liner that extends distally of the tissue-removing element <NUM>. For example, the portion <NUM> may extend along less than <NUM> of the inner liner <NUM>. However, the portion <NUM> may extend along other lengths and be disposed along other sections of the inner liner <NUM>. For example, the portion <NUM> may extend from the distal end of the inner liner <NUM> to a location proximal to a distal end of the tissue-removing element <NUM>. In one embodiment, the portion <NUM> may be spaced from a distal end of the inner liner <NUM>. In one embodiment, the portion <NUM> of the inner liner <NUM> may comprise an entire portion of the inner liner extending distally of the tissue-removing element <NUM>.

Referring to <FIG>, 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 (<NUM>) guidewire <NUM>. The outer diameter OD of the inner liner <NUM> provides clearance for the drive coil <NUM> and tissue-removing element <NUM>. The presence of 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.

Referring to <FIG>, <FIG>, and <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. The tissue-removing element <NUM> is operatively connected to the motor <NUM> for being rotated by the motor. When the catheter <NUM> is inserted into the body lumen and the motor <NUM> is rotating the tissue-removing element <NUM>, the tissue-removing element is configured to remove occlusive tissue in the body lumen to separate the tissue from the wall of the body lumen. 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 the illustrated embodiment, the tissue-removing element <NUM> comprises an abrasive burr configured to abrade tissue in the body lumen when the motor <NUM> rotates the abrasive burr. The abrasive burr <NUM> has an abrasive outer surface formed, for example, by a diamond grit coating, surface etching, or the like. In other embodiments, the tissue-removing element <NUM> can comprise one or more cutting elements having smooth or serrated cutting edges, a macerator, a thrombectomy wire, etc..

Referring to <FIG>, a cavity <NUM> extends longitudinally through the tissue-removing element <NUM> such that the tissue-removing element defines openings at its proximal and distal ends. The cavity <NUM> includes a first diameter portion <NUM> extending distally from the proximal end of the tissue-removing element <NUM> and a second diameter portion <NUM> extending distally from the first diameter portion forming a first shoulder <NUM> disposed between the first and second diameter portions. A third diameter portion <NUM> extends distally from the second diameter portion <NUM> and forms a second shoulder <NUM> between the second and third diameter portions. A fourth diameter portion <NUM> extends distally from the third diameter portion to the distal end of the tissue-removing element and forms a third shoulder <NUM> between the third and fourth diameter portions. The diameters of the first, second, third, and fourth diameter portions <NUM>, <NUM>, <NUM>, <NUM> are constant along their lengths. In the illustrated embodiment, a diameter D1 of the first diameter portion <NUM> is larger than a diameter D2 of the second diameter portion <NUM>, the diameter D2 is larger than a diameter D3 of the third diameter portion <NUM>, and the diameter D3 is larger than a diameter D4 of the fourth diameter portion <NUM>. In one embodiment, the diameter D1 of the first diameter portion <NUM> is about <NUM> inches (<NUM>), the diameter D2 of the second diameter portion <NUM> is about <NUM> inches (<NUM>), the diameter D3 of the third diameter portion <NUM> is about <NUM> inches (<NUM>), and the diameter D4 of the fourth diameter portion <NUM> is about <NUM> inches (<NUM>). Other cross-sectional dimensions are also envisioned without departing from the scope of the disclosure.

The inner liner <NUM> extends through the drive coil <NUM> and past the distal end of the tissue-removing element <NUM>. The fourth diameter portion <NUM> of the cavity <NUM> is sized to pass the inner liner <NUM> with a small clearance. The inner diameter D4 provides clearance between the tissue-removing element <NUM> and the inner liner <NUM> to reduce friction between the components. Accordingly, the tissue-removing element <NUM> is shaped and arranged to extend around at least a portion of the drive coil <NUM> and inner liner <NUM> and thus provides a relatively compact assembly for abrading tissue at the distal end portion of the catheter <NUM>.

Referring to <FIG>, a bushing <NUM> is received in the cavity <NUM> of the tissue-removing element <NUM> and around the inner liner <NUM>. The bushing <NUM> comprises a center ring portion <NUM>, a proximal ring portion <NUM>, extending proximally from the center ring portion, and a distal ring portion <NUM>, extending distally from the center ring portion. The ring portions of the bushing <NUM> define a channel <NUM> extending through the bushing that receives a portion of the inner liner <NUM>. In the illustrated embodiment, the center ring portion <NUM> has a larger outer diameter than the proximal and distal ring portions <NUM>, <NUM>. The center ring portion <NUM> is disposed in the second diameter portion <NUM> of the cavity <NUM>, the proximal ring portion <NUM> is disposed in the first diameter portion <NUM>, and the distal ring portion <NUM> is disposed in the second and third diameter portions <NUM>, <NUM>. In one embodiment, the bushing <NUM> is made from polyetheretherketone (PEEK) and polytetrafluoroethylene (PTFE). However, the bushing <NUM> can be formed from other material without departing from the scope of the disclosure.

Referring to <FIG>, <FIG>, a first bearing <NUM> is disposed around the proximal ring portion <NUM> of the bushing <NUM>, and a second bearing <NUM> is disposed around the distal ring portion <NUM> of the bushing. The first bearing <NUM> has an outer diameter D5 that is greater than an outer diameter D6 of the second bearing <NUM>. In one embodiment, the first and second bearings <NUM>, <NUM> are made from Zirconia. The first bearing <NUM> is disposed in registration with the first diameter portion <NUM> of the cavity <NUM> in the tissue-removing element <NUM> and seats between a distal end of the drive coil <NUM> at a proximal end of the first bearing, and the center ring portion <NUM> of the bushing <NUM> and first shoulder <NUM> at a distal end of the first bearing. The second bearing <NUM> is disposed in registration with the second diameter portion <NUM> of the cavity <NUM> and is seated between the second shoulder <NUM> at a distal end of the second bearing, and the center ring portion <NUM> of the bushing <NUM> at a proximal end of the second bearing. As such the bushing <NUM> and first and second bearings <NUM>, <NUM> are held within the cavity <NUM> of the tissue-removing element <NUM>. Broadly, the bushing <NUM> and first and second bearings <NUM>, <NUM> may be considered a coupling assembly <NUM> for coupling the inner liner <NUM> to the tissue-removing element <NUM>.

Referring to <FIG>, an interior surface of the bushing <NUM> is fixedly attached to the inner liner <NUM> such that the inner liner is coupled to the tissue-removing element <NUM> through the bushing. In one embodiment an adhesive such as an epoxy glue bonds the bushing <NUM> to the inner liner <NUM>. As such, the bushing <NUM> does not rotate around the inner liner <NUM>. The drive coil <NUM> is directly and fixedly attached to the tissue-removing element <NUM>. The tissue-removing element <NUM> can be fixedly attached to the distal end of the drive coil <NUM> by any suitable means. In one embodiment, adhesive bonds the drive coil <NUM> to the tissue-removing element <NUM>. The drive coil <NUM> is received in the first diameter portion <NUM> of the cavity <NUM> and a distal end of the drive coil abuts the first bearing <NUM>. However, the inner liner <NUM> is not directly attached to the tissue-removing element <NUM>, and the drive coil <NUM> is not directly attached to the bushing <NUM>, first and second bearings <NUM>, <NUM>, or inner liner. Thus, rotation of the drive coil <NUM> and tissue-removing element <NUM> is not transmitted to the inner liner <NUM> to also rotate the inner liner. Rather the tissue-removing element <NUM> rotates around the bushing <NUM> and first and second bearings <NUM>, <NUM>. And because the inner liner is fixedly attached to the bushing <NUM>, which is retained within the cavity <NUM> of the tissue-removing element <NUM> by the drive coil <NUM>, the inner liner <NUM> is coupled to the drive coil and tissue-removing element through the bushing and bearing arrangement. It will be understood that the inner liner <NUM> may be coupled to the tissue-removing element <NUM> by other means. Alternatively, the inner liner <NUM> may not be coupled to the tissue-removing element <NUM>.

Referring to <FIG>, <FIG>, and <FIG>, to remove tissue T in the body lumen L of a subject, a practitioner inserts the guidewire <NUM> into the body lumen L of the subject, to a location distal of the tissue T 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 a proximal port <NUM> in the handle. With the catheter <NUM> loaded onto the guidewire <NUM>, the practitioner advances the catheter along the guidewire until the tissue-removing element <NUM> is positioned proximal and adjacent the tissue T. When the tissue-removing element <NUM> is positioned proximal and adjacent the tissue T, the practitioner actuates the motor <NUM> using the actuator <NUM> to rotate the drive coil <NUM> and the tissue-removing element mounted on the drive coil. The tissue-removing element <NUM> abrades (or otherwise removes) the tissue T in the body lumen L as it rotates. While the tissue-removing element <NUM> is rotating, the practitioner may selectively move the drive coil <NUM> and inner liner <NUM> distally along the guidewire <NUM> to abrade the tissue T and, for example, increase the size of the passage through the body lumen L. The practitioner may also move the drive coil <NUM> and inner liner <NUM> proximally along the guidewire <NUM>, and may repetitively move the components in distal and proximal directions to obtain a back-and-forth motion of the tissue-removing element <NUM> across the tissue T by sliding the advancer <NUM> back and forth within the slot <NUM> in the handle <NUM>. 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 L 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 L for use in a subsequent procedure.

When introducing elements of the present invention 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 comprising:
an elongate body (<NUM>) having an axis (LA) and proximal and distal end portions (<NUM>, <NUM>) spaced apart from one another along the axis, the elongate body being sized and shaped to be received in the body lumen;
a tissue-removing element (<NUM>) mounted on the distal end portion of the elongate body, the tissue-removing element being configured to remove tissue as the tissue-removing element is rotated by the elongate body within the body lumen; and
an inner liner (<NUM>) received within the elongate body and defining a guidewire lumen (<NUM>), the inner liner isolating an interior of the guidewire lumen from the elongate body and tissue-removing element such that torsional force is not transferred from the elongate body and tissue-removing element to the interior of the guidewire lumen when the elongate body and tissue-removing element are rotated during operation of the tissue-removing catheter, the inner liner including a distal end margin (<NUM>) configured to extend distally of the tissue-removing element, the distal end margin having a construction different from a construction of a second portion of the inner liner which is positioned proximal of the distal end margin, and wherein the distal end margin of the inner liner is more flexible than the remaining portion of the inner liner.