Patent Description:
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 catheter for use in revascularization procedures and method of using same.

In one aspect, a tissue-removing catheter for removing tissue in a body lumen generally comprises an elongate body having 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. A handle is mounted on to the proximal end portion of the elongate body and is operable to cause rotation of the elongate body. A tissue-removing element is mounted on the distal end portion of the elongate body. The tissue-removing element is configured to remove the tissue as the tissue-removing element is rotated by the elongate body within the body lumen. An inner liner is received within the elongate body and coupled to the handle at a proximal end of the inner liner. The inner liner defines a guidewire lumen. The inner liner isolates an interior of the guidewire lumen from the elongate body and tissue-removing element such that rotational and torsional forces are 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.

In another aspect, a tissue-removing catheter for removing tissue in a body lumen generally comprises an elongate body having 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. A tissue-removing element is mounted on the distal end portion of the elongate body. The tissue-removing element is configured to remove the tissue as the tissue-removing element is rotated by the elongate body within the body lumen. An inner liner is received within the elongate body and is movable relative to the elongate body. The inner liner defines a guidewire lumen. The inner liner isolates an interior of the guidewire lumen from the elongate body and tissue-removing element such that rotational and torsional forces are 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.

In an example, a method (not claimed) of removing tissue in a body lumen generally comprises advancing a tissue-removing catheter over a guidewire in the body lumen to position a distal end of the catheter adjacent the tissue and a proximal end portion of the catheter outside of the body lumen. The catheter comprises an elongate body and a tissue removing element mounted on a distal end portion of the elongate body. An inner liner is disposed within the elongate body. The inner liner defines a guidewire lumen in which the guidewire is disposed during the advancement of the catheter. The method further comprises actuating a motor to rotate the elongate body and tissue-removing element of the catheter to remove the tissue. And isolating the guidewire from the elongate body and tissue-removing element with the inner liner so that rotational and torsional forces are not transferred from the rotating elongate body and tissue-removing element to the guidewire during rotation of the elongate body and tissue-removing element.

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 outer layer <NUM> (broadly, an elongate body) disposed around an elongate inner liner <NUM>. The outer layer <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 outer layer <NUM> and is configured for rotation to remove tissue from a body lumen as will be explained in greater detail below. A sheath <NUM> (<FIG>) is disposed around the outer layer <NUM>. The outer layer <NUM> and the inner liner <NUM> are both configured to translate relative to the sheath <NUM>. The outer layer <NUM> and inner liner <NUM> are also configured to translate relative to each other. The catheter <NUM> is sized and shaped for insertion into a body lumen of a subject. The sheath <NUM> isolates the body lumen from at least a portion of the outer layer <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 from the proximal end portion <NUM> through the distal end portion <NUM> of the catheter <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).

The catheter <NUM> further comprises a handle <NUM> secured at the proximal end portion <NUM> of the catheter. The handle <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 outer layer <NUM>, and tissue-removing element <NUM> mounted at the distal end of the outer layer. The motor <NUM> is coupled to the outer layer <NUM> by a gear assembly <NUM> and drive <NUM> supported by the handle <NUM>. A slide or advancer <NUM> is positioned on the handle <NUM> and operatively coupled to the outer layer <NUM> for movement of the outer layer relative to the handle to advance and retract the outer layer and tissue-removing element <NUM>. The handle <NUM> defines a slot (not shown) 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 outer layer <NUM> and the handle <NUM>. A perfusion port <NUM> may be disposed at the proximal end <NUM> of the catheter <NUM>. The port <NUM> communicates with a space between the sheath <NUM> and the outer layer <NUM> for delivering fluid (e.g., saline) to cool the rotating outer layer during use. A proximal port <NUM> allows for passage of the guidewire <NUM> and inner liner <NUM> through the proximal end of the handle <NUM>. A guidewire lock (not shown) may be provided on the handle <NUM> to lock the guidewire <NUM> in place relative to the handle.

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>. In other embodiments, the power supply may come from an external source.

Referring to <FIG> and <FIG>, the outer sheath <NUM> comprises a tubular sleeve configured to isolate and protect a subject's arterial tissue within a body lumen from the rotating outer layer <NUM>. The sheath <NUM> is fixed to the handle <NUM> at a proximal end of the sheath and does not rotate. A hub <NUM> mounted on the proximal end of the sheath <NUM> attaches the sheath to the handle <NUM>. The hub <NUM> includes a locking feature <NUM> (e.g., threaded luer lock) for engaging the handle <NUM> to attach the sheath <NUM> to the handle. The sheath <NUM> provides a partial enclosure for the outer layer <NUM> and inner liner <NUM> to move within the sheath. The inner diameter of the sheath <NUM> is sized to provide clearance for the outer layer <NUM>. The space between the sheath <NUM> and the outer layer <NUM> allows for the outer layer to rotate within the sheath and provides an area for saline perfusion between the sheath and outer layer. The outer diameter of the 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. A strain relief <NUM> is provided at the proximal end of the sheath <NUM> to alleviate tension applied to the proximal end of the sheath <NUM> as the sheath is bent during use of the catheter <NUM>. In one embodiment, the 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 sheath <NUM> can have other dimensions without departing from the scope of the disclosure. In one embodiment, the outer sheath <NUM> is made from Polytetrafluorethylene (PTFE). Alternatively, the outer sheath <NUM> may comprise a multi-layer construction. For example, the outer sheath <NUM> may comprises an inner layer of perfluoroalkox (PFA), a middle braided wire layer, and an outer layer of Pebax. Alternatively, the outer layer can be formed from polymide or PEEK.

Referring to <FIG>, <FIG>, <FIG>, and <FIG>, the outer layer <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 outer layer <NUM> as a coiled structure provides the outer layer with a flexibility that facilitates delivery of the catheter <NUM> through the body lumen. Also, the coil configuration allows for the rotation and torque of the outer layer <NUM> to be applied to the tissue-removing element <NUM> when the catheter <NUM> is traversed across a curved path. The stiffness of the outer layer <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 outer layer <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. For example, the outer layer may have an axial compression stiffness of between about <NUM> and about <NUM> N/mm. The coil configuration of the outer layer <NUM> is also configured to expand its inner diameter when the coil is rotated so that the outer layer remains spaced from the inner liner <NUM> during operation of the catheter <NUM>. In one embodiment, the outer layer <NUM> has an inner diameter of about <NUM> inches (<NUM>) and an outer diameter of about <NUM> inches (<NUM>). The outer layer <NUM> may have a single layer construction. For example, the outer layer may comprise a <NUM> filar (i.e., wire) coil with a lay angle of about <NUM> degrees. Alternatively, the outer layer <NUM> could be configured from multiple layers without departing from the scope of the disclosure. For example, the outer layer <NUM> may comprise a base coil layer and a jacket (e.g., Tecothane™) disposed over the base layer. In one embodiment, the outer layer comprises a <NUM> filar coil with a lay angle of about <NUM> degrees. The Tecothane™ jacket may be disposed over the coil. Alternatively, the outer layer <NUM> may comprise a dual coil layer configuration which also includes an additional jacket layer over the two coil layers. For example, the outer layer 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. Outer layer having other configurations are also envisioned.

Referring to <FIG>, <FIG>, and <FIG>, the inner liner <NUM> comprises a multiple layer tubular body configured to isolate the guidewire <NUM> from the outer layer <NUM> and tissue-removing element <NUM>. The inner liner <NUM> is extendable through the handle <NUM> from a position proximal of the handle to a position distal of the handle. In one embodiment, the inner liner <NUM> is coupled to the handle <NUM> but is not fixedly attached to the handle <NUM> to allow translation of the inner liner relative to the handle. In this embodiment, rotation of the inner liner <NUM> is not prevented. However, the clearance between the inner liner <NUM> and the outer layer <NUM> prevents any rotation of the inner liner caused by the rotation of the outer layer. In this embodiment, both the inner liner <NUM> and outer layer <NUM> are permitted to translate relative to the handle <NUM>. Allowing this co-translation of the inner liner <NUM> and outer layer <NUM> minimizes compression and extension of the coiled outer layer <NUM> when force is applied to the outer layer to move the outer layer within the body lumen. In another embodiment, the inner liner <NUM> may be fixedly attached to the handle <NUM> to prevent relative movement between the inner liner and the handle. Thus, in this embodiment, the inner liner <NUM> remains stationary and is prevented from translating relative to the handle <NUM>. Additionally, all rotation of the inner liner <NUM> is prevented. In this embodiment, the outer layer <NUM> translates over the stationary inner liner <NUM>.

The inner liner <NUM> has an inner diameter that is sized to pass the guidewire <NUM>. The inner liner <NUM> protects the guide wire from being damaged by the rotation of the outer layer <NUM> by isolating the guidewire from the rotatable outer layer. The inner liner <NUM> also extends 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 outer layer <NUM> and tissue-removing element <NUM> from the guidewire <NUM> also ensures that the rotation of the outer layer 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.

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. The PTFE inner layer <NUM> provides the inner liner <NUM> with a lubricous interior which aids in the passing of the guidewire <NUM> though 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 outer layer <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 outer layer <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 outer layer <NUM>. 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 outer layer <NUM> and tissue-removing element <NUM>. Having a space between the inner liner <NUM> and the outer layer <NUM> reduces friction between the two components as well as allows for saline perfusion between the components.

In the illustrated embodiment, a marker band <NUM> is provided on an exterior surface of the distal end of the inner liner <NUM>. The marker band <NUM> configures the tip of the inner liner <NUM> to be fluoroscopically visible which allow a physician to verify the position of the liner during a medical procedure. In this embodiment, the distal end of the inner liner <NUM> may be laser cut to provide a low profile tip. In one embodiment, the marker band <NUM> comprises a strip of platinum iridium.

It is further envisioned that the distal end of the inner liner <NUM> can have other constructions without departing from the scope of the disclosure. For example, an atraumatic tip <NUM> may be attached to the distal end of the inner liner <NUM> (<FIG>). The atraumatic tip <NUM> provides a soft, low profile distal end to facilitate delivery of the inner liner <NUM> through the body lumen without causing trauma. The atraumatic tip <NUM> may have a maximum outer diameter of about <NUM> inches (<NUM>). Other sizes of the atraumatic tip are also envisioned. In another embodiment, a tapered tip <NUM> may be attached to the distal end of the inner liner <NUM> (<FIG>). The tapered tip <NUM> may be formed from a layer of material configured to protect the distal end of the inner liner <NUM>.

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 outer layer <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 one 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> 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 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> receives a portion of the outer layer <NUM> for mounting the tissue-removing element <NUM> to the outer layer. The cavity <NUM> includes a first diameter portion <NUM> extending from the proximal end of the tissue-removing element <NUM>, a tapered diameter portion <NUM> extending from the first diameter portion toward the distal end of the tissue-removing element, and a second diameter portion <NUM> extending from the tapered diameter portion to the distal end of the tissue-removing element. The diameters of the first and second diameter portions <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>. In one embodiment, the diameter D1 of the first diameter portion <NUM> is about <NUM> inches (<NUM>), and the diameter D2 of the second diameter portion <NUM> is about <NUM> inches (<NUM>). The tapered diameter portion <NUM> provides a transition between the first and second diameter portions <NUM>, <NUM>. The outer layer <NUM> is received in the first diameter portion <NUM> and a distal end of the outer layer abuts the tapered diameter portion <NUM>. The tissue-removing element <NUM> can be fixedly attached to the distal end of the outer layer <NUM> by any suitable means. In one embodiment an adhesive bonds the tissue-removing element <NUM> to the outer layer <NUM>. The inner liner <NUM> extends through the outer layer <NUM> and the second diameter portion <NUM> of the tissue-removing element <NUM>. The second diameter portion <NUM> is sized to pass the inner liner <NUM> with a small clearance. The inner diameter D2 provides clearance between the tissue-removing element <NUM> and inner liner <NUM> to reduce friction between the components and allow a space for saline perfusion. Accordingly, the tissue-removing element <NUM> is shaped and arranged to extend around at least a portion of the outer layer <NUM> and inner liner <NUM> and thus provides a relatively compact assembly for abrading tissue at the distal end portion of the catheter <NUM>.

The exterior surface of the tissue-removing element <NUM> includes a proximal segment <NUM>, a middle segment <NUM>, and a distal segment <NUM>. A diameter of the proximal segment <NUM> increases from the proximal end of the tissue-removing element <NUM> to the middle segment <NUM>. The middle segment has a constant diameter and extends from the proximal segment <NUM> to the distal segment <NUM>. The diameter of the distal segment <NUM> tapers from the middle segment <NUM> to the distal end of the tissue-removing element <NUM>. The tapered distal segment <NUM> provides the tissue-removing element <NUM> with a general wedge shape configuration for wedging apart constricted tissue passages as it simultaneously opens the passage by removing tissue using the abrasive action of the tissue-removing element. The distal end of the tissue-removing element <NUM> is also rounded to provide the tissue-removing element with a blunt distal end.

Referring to <FIG> and <FIG>, to remove tissue in the body lumen of a subject, a practitioner inserts the guidewire <NUM> into the body lumen of the subject, to a location distal of the tissue 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 port <NUM> in the handle. The inner liner <NUM> may also extend through the handle <NUM> and out the proximal port <NUM>. 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. When the tissue-removing element <NUM> is positioned proximal and adjacent the tissue, the practitioner actuates the motor <NUM> using the actuator <NUM> to rotate the outer layer <NUM> and the tissue-removing element mounted on the outer layer. The tissue-removing element <NUM> abrades (or otherwise removes) the tissue in the body lumen as it rotates. While the tissue-removing element <NUM> is rotating, the practitioner may selectively move the outer layer <NUM> and inner liner <NUM> distally along the guidewire <NUM> to abrade the tissue and, for example, increase the size of the passage through the body lumen. The practitioner may also move the outer layer <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. During the abrading process, the inner liner <NUM> isolates the guidewire <NUM> from the rotating outer layer <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 outer layer <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 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 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 (<NUM>) 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 (LA), the elongate body being sized and shaped to be received in the body lumen;
a handle (<NUM>) mounted on to the proximal end portion (<NUM>) of the elongate body and operable to cause rotation of the elongate body (<NUM>);
a tissue-removing element (<NUM>) mounted on the distal end portion (<NUM>) of the elongate body (<NUM>), the tissue-removing element being configured to remove the tissue as the tissue-removing element (<NUM>) is rotated by the elongate body within the body lumen; and
an inner liner (<NUM>) received within the elongate body (<NUM>) and coupled to the handle (<NUM>) at a proximal end of the inner liner, the inner liner (<NUM>) defining a guidewire lumen (<NUM>), the inner liner isolating an interior of the guidewire lumen from the elongate body and tissue-removing element (<NUM>) such that rotational and torsional forces are not transferred from the elongate body (<NUM>) and tissue-removing element (<NUM>) to the interior of the guidewire lumen (<NUM>) when the elongate body and tissue-removing element are rotated during operation of the tissue-removing catheter (<NUM>);
wherein the inner liner (<NUM>) comprises a plurality of layers each extending from the proximal end of the inner liner (<NUM>) to a distal end of the inner liner (<NUM>);
wherein the inner liner (<NUM>) includes an inner layer (<NUM>), an outer layer (<NUM>), and an intermediate layer (<NUM>) disposed between the inner and outer layers; and
wherein the inner layer (<NUM>) comprises Polytetrafluorethylene (PTFE), the intermediate layer (<NUM>) comprises stainless steel, and the outer layer (<NUM>) comprises polyimide.