Patent Description:
The present disclosure generally relates to a tissue-removing catheter, and more particular, to a tissue-removing catheter including a distal tip.

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 a guidewire isolation liner. <CIT> describes a tissue-removing catheter with guidewire detection sensor. <CIT> describes a catheter. <CIT> describes a catheter for use in revascularization procedures.

In one aspect, a tissue-removing catheter for removing tissue in a body lumen generally comprises an elongate drive member having an axis and proximal and distal end portions spaced apart from one another along the axis. The elongate drive member is sized and shaped to be received in the body lumen and configured to be rotated about the axis. A tissue-removing element is operatively coupled to the distal end portion of the elongate drive member. The tissue-removing assembly is configured to be rotated by the elongate drive member to remove the tissue in the body lumen. An inner liner is received within the drive coil and defines a liner passage sized and shaped to receive a guidewire therein. The inner liner has proximal and distal end portions. A distal tip extends distally outward from the tissue-removing element. The distal tip has a proximal end portion disposed within the tissue-removing element and a distal end portion spaced distally from the tissue-removing element. The distal tip defining a tip opening extending through the proximal and distal end portions. The tip opening is in communication with the liner passage and configured to receive the guidewire therein. The tissue-removing element is rotatable relative to the distal tip. The distal end portion of the inner liner is axially spaced apart from the proximal end portion of the distal tip such that the distal tip is free from direct connection to the inner liner.

In another aspect, a tissue-removing catheter for removing tissue in a body lumen generally comprises an elongate drive member having an axis and proximal and distal end portions spaced apart from one another along the axis. The elongate drive member is sized and shaped to be received in the body lumen and configured to be rotated about the axis. A tissue-removing element is operatively coupled to the distal end portion of the elongate drive member. The tissue-removing assembly is configured to be rotated by the elongate drive member to remove the tissue in the body lumen. An inner liner is received within the drive coil and defines a liner passage sized and shaped to receive a guidewire therein. The inner liner has proximal and distal end portions. A distal tip extends distally outward from the tissue-removing element. The distal tip has a proximal end portion disposed within the tissue-removing element and a distal end portion spaced distally from the tissue-removing element. The distal tip defining a tip opening extending through the proximal and distal end portions. The tip opening is in communication with the liner passage and configured to receive the guidewire therein. The tissue-removing element is rotatable relative to the distal tip. The bushing passage is in communication with the liner passage and the tip opening, and is configured to receive the guidewire therein. The distal end portion of the inner liner is fixedly coupled to the proximal end portion of the bushing. The distal tip is integrally formed with the bushing such that the distal tip and the bushing are formed as a one-piece structure.

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>, the catheter <NUM> comprises an elongate drive member, as illustrated a drive coil <NUM>, disposed around an elongate inner liner <NUM> defining a liner passage <NUM>. The elongate drive member may be another drive member other than the drive coil, such as a drive shaft, a drive lumen, or other type of elongate drive member. 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 assembly <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> (<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 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>, <FIG> and <FIG>, the catheter <NUM> further comprises a handle <NUM> secured at a proximal end of the isolation sheath <NUM>. As shown in <FIG> and <FIG>, 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 assembly <NUM> mounted on the distal end of the drive coil. The motor <NUM> is configured to rotate the drive coil <NUM> and tissue-removing assembly <NUM> at speeds of greater than about <NUM>,<NUM> RPM. In one embodiment, the motor <NUM> rotates the drive coil <NUM> and tissue-removing assembly <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 drive assembly <NUM> supported within the housing <NUM>. As shown in <FIG>, 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 assembly <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>. In the illustrated embodiment, the actuator <NUM> is coupled to the advancer <NUM>.

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 assembly <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 assembly <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 <NUM> 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 illustrated inner liner <NUM> comprises a multiple layer tubular body configured to isolate the guidewire <NUM> from the drive coil <NUM> and tissue-removing assembly <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.

In the illustrated embodiment, as shown in <FIG>, 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> 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 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>. 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> (<NUM>-inch) guidewire <NUM>. The outer diameter OD of the inner liner <NUM> provides clearance for the drive coil <NUM> and tissue-removing assembly <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 assembly <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 assembly <NUM> is operatively connected to the motor <NUM> via the drive coil <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 assembly <NUM>, the tissue-removing assembly is configured to remove occlusive tissue in the body lumen to separate the tissue from the wall of the body lumen.

Referring to <FIG>, the illustrated tissue-removing assembly <NUM> includes a tissue-removing element <NUM> configured to engage and remove the tissue, a coupler <NUM> configured to operatively couple the tissue-removing element to the drive coil <NUM>, and an internal bearing assembly, generally indicated at <NUM>, configured to facilitate rotation of the tissue-removing element without damaging the inner liner <NUM>.

Any suitable tissue-removing element <NUM> 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 assembly can comprise one or more cutting elements having smooth or serrated cutting edges, a macerator, a thrombectomy wire, etc..

Referring still to <FIG>, the coupler <NUM> has a proximal end fixedly secured to the drive coil <NUM>, and a distal end fixedly secured to the proximal end of the tissue-removing element <NUM>. The coupler transfers rotation from the drive coil <NUM> to the tissue-removing element <NUM>. Together, the coupler <NUM> and the tissue-removing element <NUM> define an internal cavity <NUM> extending axially along the longitudinal axis LA. The coupler <NUM> may be formed from metal or other material, and may be welded and/or crimped to the drive coil and the tissue-removing element <NUM>. The coupler <NUM> may be fixedly coupled to the drive coil <NUM> and the tissue-removing element <NUM> in other ways. In one or more embodiments, the tissue-removing assembly <NUM> may not include the coupler, but instead, the drive coil <NUM> may be fixedly coupled directly to the tissue-removing element <NUM>, such as by welding or in other ways.

Referring to <FIG>, the bearing assembly <NUM> includes a bushing <NUM> received in the internal cavity <NUM> of the tissue-removing assembly <NUM>. As seen best in <FIG>, 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 bushing <NUM> defines an axial passage <NUM> extending through the bushing. As shown in <FIG>, a proximal counterbore at the proximal end of the internal passage of the bushing <NUM> receives a distal end of the inner liner <NUM>. The inner liner <NUM> may be secured to the bushing within the proximal counterbore, such as by epoxy adhesive. 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> and <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 may be greater than an outer diameter D6 of the second bearing <NUM>, although the diameters may be the same. In one embodiment, the bearings <NUM>, <NUM> are made from Zirconia. The first bearing <NUM> is disposed in a counterbore of the cavity defined by the distal end coupler <NUM> and is held captive in the counterbore by a proximal end of the center ring portion <NUM> of the bushing <NUM>. The second bearing <NUM> is disposed in a counterbore of the cavity adjacent a distal end of the tissue-removing element <NUM> and is held captive in the counterbore by a distal end of the center ring portion <NUM> of the bushing <NUM>. As such the bushing <NUM> and bearings <NUM>, <NUM> are held within the cavity of the tissue-removing assembly <NUM>. Broadly, the bushing <NUM> and bearings <NUM>, <NUM> may be considered a coupling assembly <NUM> for coupling the inner liner <NUM> to the tissue-removing assembly <NUM>.

In the illustrated embodiment, rotation of the drive coil <NUM> and tissue-removing assembly <NUM> is not transmitted to the inner liner <NUM> such that the liner does not rotate with the drive coil <NUM>. Rather the coupler <NUM>, the tissue-removing element <NUM>, and the bearings <NUM>, <NUM> rotate about the bushing <NUM>. And because the inner liner is fixedly attached to the bushing <NUM>, which is retained within the cavity <NUM> of the tissue-removing assembly <NUM>, the inner liner <NUM> is coupled to the drive coil and tissue-removing assembly through the bushing and bearing arrangement. Thus, the inner liner <NUM> will translate with the coil <NUM> and the tissue-removing assembly <NUM>, however, the inner liner will not rotate with the drive coil and the tissue-removing element <NUM>. It will be understood that the inner liner <NUM> may be coupled to the tissue-removing assembly <NUM> by other means. Alternatively, the inner liner <NUM> may not be coupled to the tissue-removing assembly <NUM>.

Referring to <FIG> and <FIG>, the catheter <NUM> further includes a distal tip, generally indicated at <NUM>, extending distally outward from the tissue-removing assembly <NUM>. The illustrated distal tip <NUM> has a generally cylindrical shape with an axis extending along the longitudinal axis LA of the catheter <NUM>. A proximal end of the tip <NUM> is fixedly coupled to the bushing <NUM> at a location within the tissue-removing assembly <NUM>. In particular, the illustrated tip <NUM> is received in a distal counterbore of the bushing <NUM> adjacent the distal end of the bearing passage <NUM>, and may be fixedly secured therein by adhesive or in other ways. The tip <NUM> may be fixedly coupled to the bushing <NUM> by thermal bonding or welding, heatshrink, adhesive, overmolding, or in other ways. The distal tip <NUM> extends through a distalmost opening defined by the tissue-removing element <NUM>, and may project a distance d1 from about <NUM> to about <NUM>, or about <NUM> beyond the distalmost end of the tissue-removing element. The tip <NUM> defines a tip opening <NUM> extending axially through proximal and distal end thereof. The tip opening <NUM> is axially aligned and in communication with the bushing passage <NUM> and the liner passage <NUM>. Together, the tip opening <NUM> and the passages <NUM>, <NUM> are designed and constructed to receive a guidewire therein (e.g., a <NUM>" guidewire). The diameters of the tip opening <NUM> and the passages <NUM>, <NUM> may be equal or different, with the understanding that the sizes are suitable for receiving the guidewire therein. In one example, the diameters of the tip opening <NUM> and the passages <NUM>, <NUM> are equal. The diameters may be from about <NUM> to about <NUM>, and in one example, about <NUM>. A maximum outer diameter of the tip <NUM> may be from about <NUM> to about <NUM>, and in one example about <NUM>.

The tip <NUM> in general may be more flexible than the tissue-removing element <NUM> such that the tip facilitates centering of the tissue-removing element in the lesion to enhance effective deliver of the catheter into the lesion. The tip <NUM> may be less flexible than the guidewire to provide a suitable transition of stiffness between the guidewire and the tissue-removing element <NUM>, which is believed to protect against guide damage. In one embodiment, shown in <FIG>, the tip <NUM> may include a frame <NUM> to provide rigidity to the tip, while still allowing the tip to flex. In one example, the frame <NUM> may comprise (e.g., be formed from) a shape-memory material, such as Nitinol (nickel titanium). The frame <NUM> may be shape-set in a straight or linear configuration to resist bending, while allowing bending and enabling rebound to the linear configurations. The frame <NUM> may be braided from strands or filars of such material, as shown in <FIG>. The stiffness of the frame <NUM> may be selected and achieved by a selecting a suitable filar density and/or suitable lay angle of the filars. In another example, as shown in <FIG>, a frame <NUM>' may be formed from a hypotube of the shape-memory material, such as Nitinol. The hypotube may be cut (e.g., laser cut) or otherwise formed with slots to adjust the stiffness of the frame <NUM>'. The stiffness of the frame <NUM>' may be selected and achieved by a suitable cut pattern for the slots and/or shapes and sizes of the slots.

The tip <NUM> may include a body layer <NUM> (e.g., an outer layer or encapsulating layer) including (e.g., formed from) a softer material that is softer and more flexible than the frame <NUM>, <NUM>'. For example, the body layer <NUM> may encapsulate (e.g., fully encapsulate) the frame <NUM>, <NUM>'. The material of the body layer <NUM> may have a Shore D hardness that is less than a Shore D hardness of the frame <NUM>, <NUM>'. As an example, the Shore D hardness of the material may be from about <NUM>-72D. A suitable polymeric material may be a thermoplastic elastomer, a polyimide, or other materials. For example, the layer <NUM> may comprise block copolymers made up of rigid polyamide blocks and soft polyether blocks, among other thermoplastic elastomers. Together, the frame <NUM>, <NUM>' and the layer <NUM> encapsulating or overlying the frame may constitute the body of the tip <NUM>. The layer <NUM> may be suitably adhered to the bushing <NUM>.

Referring to <FIG>, an inner layer <NUM> of the tip <NUM> may define at least a longitudinal portion of the tip opening <NUM>. The inner layer <NUM> may define the inner surface of the tip <NUM>. The inner layer <NUM>, for example, may comprise a low friction material to reduce friction imparted on the guidewire <NUM>, since the guidewire is immediately adjacent and may contact the inner layer. The inner layer <NUM> may comprise a polymeric material, such as polytetrafluoroethylene, perfluoroalkoxy, fluorinated ethylene propylene, and/or combination thereof. The inner layer <NUM> may extend along substantially the entire length of the tip <NUM>, and may be spaced slightly from the distalmost end of the top.

Referring still to <FIG>, the distal tip <NUM> may further comprise an atraumatic distalmost end portion <NUM>. The distalmost end portion <NUM> is designed and constructed to inhibit damaging (e.g. perforating, dissecting, scraping, cutting, etc.) the body lumen (e.g., vessel) during delivery of the catheter <NUM> to the lesion. The distalmost end portion <NUM> may include a suitable material having a hardness that is less than the hardness of the body layer <NUM> and the frame <NUM>, <NUM>'. For example, the distalmost end portion <NUM> may comprise (e.g., be formed from) material have a Shore D hardness that is less than a Shore D hardness of the body layer <NUM> and the frame <NUM>, <NUM>'. As an example, the Shore D hardness of the material may be from about <NUM>-72D. For example, the distalmost end portion <NUM> may comprise block copolymers made up of rigid polyamide blocks and soft polyether blocks, among other thermoplastic elastomers and polymers. In one example, the distalmost end portion <NUM> may be radiopaque to aid in fluoroscopic visualization. A filler material, such as tungsten or barium sulfate, may be included in the distalmost end portion <NUM>. In the illustrated embodiment, the distalmost end of the distalmost end portion <NUM> is beveled to facilitate centering of the tissue-removing element <NUM> in the lesion.

Referring to <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 the 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 assembly <NUM> is positioned proximal and adjacent the tissue T. When the tissue-removing assembly <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 assembly mounted on the drive coil. The tissue-removing assembly <NUM> abrades (or otherwise removes) the tissue T in the body lumen L as it rotates. While the tissue-removing assembly <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 assembly <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 assembly <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 assembly <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.

Referring to <FIG>, another embodiment of a tissue-removing assembly for use with the catheter <NUM> is generally indicated at reference numeral <NUM>'. This embodiment may be similar or identical to the tissue-removing assembly <NUM>, except as described below herein. As an example, coupling <NUM>', bearings <NUM>, <NUM>, and tissue-removing element <NUM> may be identical to the corresponding components of the first tissue-removing assembly <NUM>. Unlike the first tissue-removing assembly, a distal tip <NUM>' is integrally formed with a bushing <NUM>' such that the distal tip and the bushing is an integrally formed, one-piece structure. In other words, a distal end portion of the bushing <NUM>' defines the distal tip <NUM>'. The other structures of the bushings <NUM>' may be similar to identical to the structures of the first bushing <NUM>.

The distal tip <NUM>' extends through a distalmost opening defined by the tissue-removing element <NUM>', and may project a distance d2 from about <NUM> to about <NUM>, or from about <NUM> to about <NUM>, or about <NUM> beyond the distalmost end of the tissue-removing element. The tip <NUM>' defines a tip opening <NUM>' extending axially through proximal and distal end thereof. The tip opening <NUM>' is a continuation of (and axially aligned and in communication with) the bushing passage <NUM>' and the inner liner passage <NUM>'. Together, the tip opening <NUM>' and the passages <NUM>', <NUM>' are designed and constructed to receive a guidewire therein (e.g., a <NUM>" guidewire), as with the first embodiment. The diameters of the tip opening <NUM>' and the passages <NUM>', <NUM>' may be equal or different, with the understanding that the sizes are suitable for receiving the guidewire therein. In one example, the diameters of the tip opening <NUM>' and the passages <NUM>', <NUM>' are equal. The diameters may be from about <NUM> to about <NUM>, and in one example, about <NUM>. A maximum outer diameter of the tip <NUM> may be from about <NUM> to about <NUM>, and in one example about <NUM>.

The distal tip <NUM>' in general may be more flexible than the bushing <NUM>' and the tissue-removing element <NUM>' such that the tip facilitates centering of the tissue-removing element in the lesion to enhance effective deliver of the catheter into the lesion. The tip <NUM>' may be less flexible than the guidewire to provide a suitable transition of stiffness between the guidewire and the tissue-removing element <NUM>', which is believed to protect against guide damage. The integrated tip <NUM>' and bushing <NUM>' also suitably isolates the guidewire <NUM> from the rotating tissue-removing element <NUM>'. In one example, the tip <NUM>' (and the bushing <NUM>') may comprise one or more of PEEK (polyetheretherketone), Carbon fiber, and combinations thereof. For example, the integrated tip <NUM>' and bushing <NUM>' may be formed from a Carbon filled PEEK material, such as a <NUM>% Carbon fiber reinforced PEEK material. The Carbon filled PEEK has a modulus of elasticity less than the modulus of elasticity of stainless steel. In the illustrated embodiment, the distal tip <NUM>' has a wall thickness that is non-uniform along its length to promote flexing of the tip at the desired longitudinal location. In the illustrated embodiment, the tip <NUM>' has a maximum wall thickness at its maximum outer diameter OD, which is adjacent to and spaced distally from the distalmost end of the tissue-removing element <NUM>'. The wall thickness of the tip <NUM>' decreases gradually (i.e., tapers) distally to decrease stiffness of the tip toward its distalmost end. The wall thickness of the tip <NUM>' also tapers proximally toward the distal opening of the tissue-removing element <NUM>'.

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 comprising:
an elongate drive member (<NUM>) having an axis (LA) and proximal and distal end portions spaced apart from one another along the axis, the elongate drive member being sized and shaped to be received in the body lumen and configured to be rotated about the axis;
a tissue-removing element (<NUM>) operatively coupled to the distal end portion of the elongate drive member, the tissue-removing element being configured to be rotated by the elongate drive member to remove the tissue in the body lumen;
an inner liner (<NUM>) received within the elongate drive member and defining a liner passage (<NUM>) sized and shaped to receive a guidewire therein, the inner liner having proximal and distal end portions; and
a distal tip (<NUM>) extending distally outward from the tissue-removing element, wherein the distal tip has a proximal end portion disposed within the tissue-removing element and a distal end portion spaced distally from the tissue-removing element, the distal tip defining a tip opening extending through the proximal and distal end portions, the tip opening being in communication with the liner passage and configured to receive the guidewire therein,
wherein the tissue-removing element is rotatable relative to the distal tip,
wherein the distal end portion of the inner liner is axially spaced apart from the proximal end portion of the distal tip such that the distal tip is free from direct connection to the inner liner; and
further comprising a bearing assembly (<NUM>) operatively coupled to the tissue-removing element, wherein the inner liner and the distal tip are coupled to the bearing assembly.