阅读说明：本技术 具有导丝隔离衬套的组织移除导管 (Tissue removal catheter with guidewire isolation bushing ) 是由 A·詹莫斯 J·凯利 C·麦克马伦 M·弗莱明 C·米德 G·卡罗尔 P·莫顿 于 2018-05-03 设计创作，主要内容包括：一种用于移除体腔中的组织的组织移除导管(10)包括细长主体(12)和安装于细长主体(12)的近端部分的手柄(40)。手柄(40)可操作成引起细长主体(12)的旋转。组织移除元件(20)安装在细长主体(12)的远端部分上。组织移除元件(20)构造成,随着该组织移除元件(20)在体腔内由细长主体(12)旋转而移除组织。内衬套(14)被接纳在细长主体(12)内,并且在内衬套(14)的近端部分处联接于手柄(40)。内衬套(14)限定有导丝(26)内腔。内衬套(14)在内衬套(14)的远端部分处联接于组织移除元件(20),使得内衬套(14)在体腔中的平移运动引起组织移除元件(20)的对应平移运动。(A tissue-removing catheter (10) for removing tissue in a body lumen includes an elongate body (12) and a handle (40) mounted to a proximal portion of the elongate body (12). The handle (40) is operable to cause rotation of the elongate body (12). A tissue-removing element (20) is mounted on a distal portion of the elongate body (12). The tissue-removing element (20) is configured to remove tissue as the tissue-removing element (20) is rotated within the body lumen by the elongate body (12). The inner liner (14) is received within the elongated body (12) and is coupled to the handle (40) at a proximal portion of the inner liner (14). The inner liner (14) defines a guidewire (26) lumen. The inner liner (14) is coupled to the tissue removal element (20) at a distal portion of the inner liner (14) such that translational movement of the inner liner (14) in the body lumen causes a corresponding translational movement of the tissue removal element (20).)

1. A tissue-removing catheter for removing tissue in a body lumen, the tissue-removing catheter comprising:

an elongated body having an axis and proximal and distal portions spaced apart from each other along the axis, wherein the elongated body is sized and shaped to be received in the body lumen;

a handle mounted to the proximal portion of the elongated body and operable to cause rotation of the elongated body;

a tissue-removing element mounted on the distal end portion of the elongate body, the tissue-removing element configured to remove the tissue as the elongate tissue rotates the tissue-removing element within the body lumen; and

an inner sleeve received within the elongate body and coupled to the handle at a proximal portion of the inner sleeve, the inner sleeve defining a guidewire lumen, the inner sleeve coupled to the tissue removal element at a distal portion of the inner sleeve such that translational movement of the inner sleeve in the body lumen causes corresponding translational movement of the tissue removal element.

2. The tissue-removing catheter set forth in claim 1, further comprising a coupling assembly disposed in the tissue-removing element for coupling the inner sheath to the tissue-removing element, the tissue-removing element being rotatable about at least a portion of the coupling assembly.

3. The tissue-removing catheter set forth in claim 2, wherein the elongate body retains the coupling assembly in the tissue-removing element.

4. The tissue-removing catheter set forth in claim 2, wherein the coupling assembly includes a bushing attached to the distal end portion of the inner sleeve, the bushing receiving a section of the inner sleeve within a channel of the bushing.

5. The tissue-removing catheter set forth in claim 4, wherein the bushing comprises a central ring portion, a proximal ring portion extending proximally from the central ring portion, and a distal ring portion extending distally from the central ring portion, the central ring portion having an outer cross-sectional dimension greater than an outer cross-sectional dimension of the proximal ring portion and the distal ring portion.

6. The tissue-removing catheter set forth in claim 5, wherein the coupling assembly further comprises a first bearing disposed about the proximal ring portion and a second bearing disposed about the distal ring portion.

7. The tissue-removing catheter set forth in claim 6, wherein the first bearing has an outer cross-sectional dimension that is greater than an outer cross-sectional dimension of the second bearing.

8. The tissue-removing catheter set forth in claim 6, wherein the bushing is made of Polyetheretherketone (PEEK) and Polytetrafluoroethylene (PTFE) and the bearing is made of zirconia.

9. The tissue-removing catheter set forth in claim 1, wherein the distal end of the inner sleeve extends distally of the tissue-removing element.

10. A tissue-removing catheter for removing tissue in a body lumen, the tissue-removing catheter comprising:

an elongated body having an axis and proximal and distal portions spaced apart from each other along the axis, wherein the elongated body is sized and shaped to be received in the body lumen;

a tissue-removing element mounted on the distal end portion of the elongate body, the tissue-removing element configured to remove the tissue as the elongate tissue rotates the tissue-removing element within the body lumen; and

an inner sleeve received within the elongate body, the inner sleeve defining a guidewire lumen, the inner sleeve coupled to the tissue removal element at a distal portion of the inner sleeve such that translational movement of the inner sleeve within the body lumen causes corresponding translational movement of the tissue removal element.

11. The tissue-removing catheter set forth in claim 10, further comprising a coupling assembly disposed in the tissue-removing element for coupling the inner sheath to the tissue-removing element, the tissue-removing element being rotatable about at least a portion of the coupling assembly.

12. The tissue-removing catheter set forth in claim 11, wherein the elongate body retains the coupling assembly in the tissue-removing element.

13. The tissue-removing catheter set forth in claim 11, wherein the coupling assembly includes a bushing attached to the distal end portion of the inner sleeve, the bushing including a central ring portion, a proximal ring portion extending proximally from the central ring portion, a distal ring portion extending distally from the central ring portion, and a channel extending through the bushing, the bushing receiving a segment of the inner sleeve within the channel of the bushing, the coupling assembly further including a first bearing disposed about the proximal ring portion and a second bearing disposed about the distal ring portion.

14. The tissue-removing catheter set forth in claim 10, further comprising a cavity extending through the tissue-removing element from a proximal end to a distal end of the tissue-removing element, wherein the cavity comprises a first section extending distally from the proximal end and a second section extending distally from the first section, the first section having a cross-sectional dimension greater than a cross-sectional dimension of the second section.

15. The tissue-removing catheter set forth in claim 14, further comprising a bushing disposed in the cavity, the bushing including a central ring portion, a proximal ring portion extending proximally from the central ring portion, and a distal ring portion extending distally from the central ring portion, the central ring portion being disposed in the second section of the cavity.

16. The tissue-removing catheter set forth in claim 15, further comprising a first bearing disposed about the proximal ring portion of the bushing, and a second bearing disposed about the distal ring portion of the bushing, the first bearing being disposed in the first section of the cavity and the second bearing being disposed in the second section of the cavity.

17. The tissue-removing catheter set forth in claim 16, wherein the cavity comprises a third section extending distally from the second section and a fourth section extending distally from the third section to the distal end of the tissue-removing element, the third section having a cross-sectional dimension greater than a cross-sectional dimension of the fourth section.

18. The tissue-removing catheter set forth in claim 17, wherein the proximal ring portion of the bushing is disposed in the first section of the cavity and the distal ring portion of the bushing is disposed in the second and third sections of the cavity.

19. A method of removing tissue in a body lumen, the method comprising:

advancing an elongate body and a tissue-removing element mounted on a distal end portion of the elongate body through a body lumen to position the tissue-removing element adjacent to the tissue and to position a proximal end portion of the elongate body outside the body lumen;

advancing an inner liner disposed within the elongate body through the body lumen to position a distal portion of the inner liner adjacent the tissue and a proximal portion of the inner liner outside the body lumen, the inner liner defining a guidewire lumen; and

coupling the inner liner to the tissue-removing element at the distal portion of the inner liner such that translational movement of the inner liner in the body lumen causes corresponding translational movement of the tissue-removing element.

20. The method of removing tissue of claim 19, further comprising rotating the tissue-removing element about a coupling assembly disposed in the tissue-removing element, the coupling assembly coupling the inner liner to the tissue-removing element.

Technical Field

The present disclosure relates generally to a tissue removal catheter and, more particularly, to an isolation hub and tissue removal element for a tissue removal catheter.

Background

Tissue removal catheters are used to remove unwanted tissue in a body cavity. As an example, rotational atherectomy catheters are used to remove material from a blood vessel to open the blood vessel and improve blood flow through the blood vessel. The procedure may be used to prepare a lesion in a coronary artery of a patient to facilitate Percutaneous Transluminal Coronary Angioplasty (PTCA) or stent delivery in a patient with a heavily calcified coronary lesion. Atherectomy catheters typically employ a rotating element that is used to abrade or otherwise destroy unwanted tissue.

Disclosure of Invention

In one aspect, a tissue removal catheter for removing tissue in a body lumen generally includes an elongate body having an axis and proximal and distal portions spaced apart from one another along the axis. The elongated body is sized and shaped to be received in a body lumen. A handle is mounted to a proximal portion of the elongated body and is operable to cause rotation of the elongated body. A tissue-removing element is mounted on the distal portion of the elongate body. The tissue-removing element is configured to remove tissue as the tissue-removing element is rotated by the elongate body within the body lumen. An inner liner is received within the elongated body and is coupled to the handle at a proximal portion of the inner liner. The inner liner defines a guidewire lumen. The inner liner is coupled to the tissue removal element at a distal portion of the inner liner such that translational movement of the inner liner in the body lumen causes corresponding translational movement of the tissue removal element.

In another aspect, a tissue removal catheter for removing tissue in a body lumen generally includes an elongate body having an axis and proximal and distal portions spaced apart from one another along the axis, wherein the elongate body is sized and shaped to be received in a body lumen. A tissue-removing element is mounted on the distal portion of the elongate body. The tissue-removing element is configured to remove tissue as the tissue-removing element is rotated by the elongate body within the body lumen. An inner liner is received within the elongated body. The inner liner defines a guidewire lumen. The inner liner is coupled to the tissue removal element at a distal portion of the inner liner such that translational movement of the inner liner in the body lumen causes corresponding translational movement of the tissue removal element.

In yet another aspect, a method of removing tissue in a body lumen generally includes advancing an elongate body and a tissue-removing element mounted on a distal end portion of the elongate body through the body lumen to position the tissue-removing element adjacent to the tissue and to position a proximal end portion of the elongate body outside of the body lumen. An inner liner disposed within the elongate body is advanced through the body lumen to position a distal portion of the inner liner adjacent tissue and to position a proximal portion of the inner liner outside the body lumen. The inner liner defines a guidewire lumen. Coupling the inner liner to the tissue-removing element at a distal portion of the inner liner such that translational movement of the inner liner in the body lumen causes corresponding translational movement of the tissue-removing element.

Drawings

Fig. 1 is a front view of a catheter of the present disclosure;

FIG. 2 is an enlarged front view of the distal portion of the catheter;

FIG. 3 is an enlarged front view of the proximal portion of the catheter;

FIG. 4 is an enlarged, fragmentary, longitudinal cross-sectional view of the distal portion of the catheter of FIG. 2;

FIG. 5 is a cross-sectional view taken through line 5-5 of FIG. 2;

FIG. 6 is a partial front view of an insulation bushing of a catheter with portions broken away to show internal detail;

FIG. 7 is an enlarged longitudinal cross-sectional view of the tissue-removing element of the catheter;

FIG. 8 is a perspective view of the bushing of the catheter;

FIG. 9 is a perspective view of a first bearing of the catheter; and

fig. 10 is a perspective view of a second bearing of the catheter.

Corresponding reference characters indicate corresponding parts throughout the drawings.

Detailed Description

Referring to the drawings, and in particular to FIG. 1, a rotary tissue removal catheter for removing tissue in a body lumen is generally indicated by reference numeral 10. The illustrated catheter 10 is an atherectomy device adapted to remove (e.g., grind, cut, resect, ablate, etc.) occlusive tissue (e.g., embolic tissue, plaque tissue, atherosclerosis, thrombolytic tissue, stenotic tissue, hyperplastic tissue, neoplastic tissue, etc.) from a vessel wall. The catheter 10 may be used to facilitate percutaneous coronary angioplasty (PTCA) or subsequent stent delivery. Features of the disclosed embodiments may also be suitable for treating Chronic Total Occlusion (CTO) of blood vessels, as well as strictures of other body lumens such as ureters, biliary tracts, respiratory tracts, pancreatic ducts, lymphatic vessels, and the like, and strictures of other proliferative and neoplastic diseases in other body lumens. Tumors surrounding and invading body cavities often result in the growth of neoplastic cells. Thus, removing such material may be beneficial to maintain patency of the body cavity.

The catheter 10 is sized to be received in a blood vessel of a subject. Thus, the maximum dimension of the catheter 10 may be 3, 4, 5, 6, 7, 8, 9, 10, or 12 French (1, 1.3, 1.7, 2, 2.3, 2.7, 3, 3.3, or 4 millimeters) and the working length may be 20, 30, 40, 60, 80, 100, 120, 150, 180, or 210 centimeters, depending on the body lumen. While the remaining discussion is directed to a catheter for removing tissue in a blood vessel, it should be understood that the teachings of the present disclosure are also applicable to other types of tissue removal catheters, including but not limited to catheters for penetrating and/or removing tissue from various occlusive, stenotic or proliferative materials in various body lumens.

Referring to fig. 1 and 2, catheter 10 includes an elongate outer layer 12 disposed about an elongate inner liner 14. The outer layer 12 and the inner liner 14 extend along a longitudinal axis LA of the catheter from a proximal portion 16 to a distal portion 18 of the catheter. A tissue-removing element 20 is disposed on the distal end of the outer layer 12 and is configured to rotate to remove tissue from a body lumen, as will be described in more detail below. A sleeve 22 is disposed about the outer layer 12. Both outer layer 12 and inner liner 14 are configured to translate relative to sleeve 22. The catheter 10 is sized and shaped so that it can be inserted into a body cavity of a subject. The sleeve 22 isolates the body cavity from at least a portion of the outer layer 12 and the inner liner 14. The inner liner 14 defines a guidewire lumen 24 (fig. 5) for slidably receiving a guidewire 26 within the guidewire lumen 24 such that the catheter 10 can be advanced through a body lumen by traveling along the guidewire. The guidewire may be a standard 0.014 inch outer diameter, 300 centimeter long guidewire. In certain embodiments, inner liner 14 may have a lubricious inner surface for sliding over guidewire 26 (e.g., the lubricious surface may be provided by a lubricious polymer layer or a lubricious coating). In the illustrated embodiment, the guidewire lumen 24 extends from the proximal portion 16 of the catheter 10 through the distal portion 18 such that the guidewire 26 may extend along the entire working length of the catheter 10. In one embodiment, the total working length of the catheter 10 may be between about 135 centimeters (53 inches) to about 142 centimeters (56 inches).

The catheter 10 also includes a handle 40 secured at the proximal portion 16 of the catheter. Handle 40 supports an actuator 42 (e.g., a lever, button, dial, switch, or other device), which actuator 42 is configured for selectively actuating a motor 43 disposed in the handle to drive rotation of outer layer 12 and tissue-removing element 20 mounted at the distal end of the outer layer. Motor 43 is coupled to outer layer 12 by a gear assembly 44 and a drive 48 supported by handle 40. A slider or advancer 45 is positioned on the handle 40 and is operatively coupled to the outer layer 12 to move the outer layer relative to the handle to advance and retract the outer layer and the tissue removal element 20. The handle 40 defines a slot (not shown) that limits movement of the slider 45 relative to the handle. The length of the slot thus determines the amount of relative movement between the outer layer 12 and the handle 40. An irrigation port 46 may be provided at the proximal end 16 of the catheter 10. A port 46 communicates with the space between the sleeve 22 and the outer layer 12 for delivering a fluid (e.g., saline) to cool the rotating outer layer during use. Proximal port 47 allows guidewire 26 and inner liner 14 to pass through the proximal end of handle 40. A guidewire lock (not shown) may be provided on the handle 40 to lock the guidewire 26 in place relative to the handle.

It should be understood that in other embodiments, other suitable actuators, including but not limited to touch screen actuators, wireless controlled actuators, automatic actuators guided by a controller, etc., may be suitable for selectively actuating the motors. In some embodiments, the power supply may come from a battery (not shown) housed within the handle 40. In other embodiments, the power supply may be from an external source.

Referring to fig. 1 and 3, the outer cannula 22 includes a tubular sleeve configured to isolate and protect arterial tissue within a body lumen of a subject from the rotating outer layer 12. The sleeve 22 is fixed to the handle 40 at the proximal end of the sleeve and does not rotate. An interface 52 mounted on the proximal end of the cannula 22 attaches the cannula to the handle 40. The hub 52 includes a locking feature 54 (e.g., a threaded luer lock), the locking feature 54 for engaging the handle 40 to attach the cannula 22 to the handle. The sleeve 22 provides a partial enclosure for movement of the outer layer 12 and inner liner 14 within the sleeve. The inner diameter of the sleeve 22 is sized to provide clearance for the outer layer 12. The space between the sleeve 22 and the outer layer 12 allows the outer layer to rotate within the sleeve and provides an area for saline infusion between the sleeve and the outer layer. The outer diameter of the cannula 22 is sized to provide clearance with the inner diameter of a guide catheter (not shown) used to deliver the catheter 10 to a desired location in a body lumen. A strain relief 56 is provided at the proximal end of the sleeve 22 to relieve tension applied to the proximal end of the sleeve 22 as the sleeve bends during use of the catheter 10. In one embodiment, the cannula 22 has an inner diameter of about 0.050 inches (1.27 millimeters), an outer diameter of about 0.055 inches (1.4 millimeters), and a length of about 1500 millimeters (59 inches). The sleeve 22 may have other dimensions without departing from the scope of the present disclosure. In one embodiment, the outer sleeve 22 is made of Polytetrafluoroethylene (PTFE). Alternatively, the outer sleeve 22 may comprise a multi-layer construction. For example, the outer sleeve 22 may include an inner layer of Perfluoroalkoxy (PFA), an intermediate braided wire layer, and an outer layer of Pebax.

Referring to fig. 1, 2, 4 and 5, outer layer 12 may comprise a tubular stainless steel coil configured to transmit rotation and torque from motor 43 to tissue-removing element 20. Configuring the outer layer 12 into a coiled configuration provides flexibility to the outer layer that facilitates delivery of the catheter 10 through a body lumen. Further, the coil configuration allows rotation and torque of outer layer 12 to be applied to tissue-removing element 20 as catheter 10 traverses a curved path. The stiffness of the outer layer 12 also affects the ease with which the coil traverses the body lumen and the ability of the coil to effectively transfer torque to the tissue-removing element 20. In one embodiment, the outer layer 12 is relatively rigid such that axial compression and extension of the coil is minimized during movement of the catheter 10 through a body lumen. The coil configuration of outer layer 12 is also configured to expand its inner diameter as the coil is rotated so that the outer layer remains spaced from inner liner 14 during operation of catheter 10. In one embodiment, the outer layer 12 has an inner diameter of about 0.023 inches (0.6 millimeters) and an outer diameter of 0.035 inches (0.9 millimeters). The outer layer 12 may have a single layer construction. For example, the outer layer may comprise a 7-filament (i.e., wire) coil having a lay angle of about 30 degrees. Alternatively, the outer layer 12 may be constructed from multiple layers,without departing from the scope of the present disclosure. For example, the outer layer 12 may include a base coil layer and a sheath (e.g., Tecothane) disposed over the base layer^TM). In one embodiment, the outer layer comprises 15-wire coils having a lay angle of about 45 degrees. Tecothane^TMA sheath may be disposed over the coil. Alternatively, the outer layer 12 may comprise a dual coil layer construction that also includes an additional jacket layer over the two coil layers. For example, the outer layer may include an inner coil layer comprising a 15-wire coil having a lay angle of about 45 degrees and an outer coil layer comprising a 19-wire coil having a lay angle of about 10 degrees. Outer layers having other configurations are also contemplated.

Referring to fig. 1, 2, and 4-6, inner liner 14 includes a multi-layered tubular body configured to isolate at least a portion of guidewire 26 from outer layer 12 and tissue-removing element 20. Inner liner 14 may extend through handle 40 from a position proximal to the handle to a position distal to the handle. In one embodiment, inner liner 14 is coupled to handle 40, but is not fixedly attached to handle 40 to allow inner liner to translate relative to the handle. In this embodiment, rotation of inner liner 14 is not inhibited. However, the clearance between inner sleeve 14 and outer layer 12 and the attachment of the inner sleeve to coupling assembly 57 in tissue removal element 20 prevents any rotation of the inner sleeve caused by rotation of the outer layer and tissue removal element. In this embodiment, inner liner 14 and outer layer 12 are both allowed to translate relative to handle 40.

Inner liner 14 has an inner diameter sized to pass guidewire 26. Inner liner 14 protects the guidewire from damage caused by rotation of outer layer 12 by isolating the guidewire from the rotatable outer layer. Inner sleeve 14 also extends past tissue-removing element 20 to protect guidewire 26 from the rotating tissue-removing element. Thus, inner liner 14 is configured to prevent any contact between guidewire 26 and rotating components of catheter 10. Thus, inner liner 14 eliminates any metal-to-metal fit. This isolation of the outer layer 12 and tissue removal element 20 from the guidewire 26 also ensures that rotation of the outer layer and tissue removal element is not transferred or transmitted to the guidewire. As a result, a standard guidewire 26 may be used with the catheter 10 because the guidewire does not have to be configured to withstand the twisting action of the rotating components. In addition, by extending through tissue-removing element 20 and past the distal end of the tissue-removing element, inner sleeve 14 stabilizes the tissue-removing element by providing a centering shaft for rotating the tissue-removing element about the inner sleeve.

In the illustrated embodiment, inner liner 14 includes an inner PTFE layer 60, an intermediate braid layer 62 composed of stainless steel, and an outer layer 64 of polyimide. The PTFE inner layer 60 provides a lubricious interior to the inner liner 14 that aids in threading the guidewire 26 through the inner liner. The braided stainless steel intermediate layer 62 provides rigidity and strength to the inner liner 14 so that the liner can withstand torsional forces exerted by the outer layer 12 on the inner liner. In one embodiment, the intermediate layer 62 is formed from 304 stainless steel. Outer polyimide layer 64 provides wear resistance and has lubricity that reduces friction between inner liner 14 and outer layer 12. In one embodiment, inner liner 14 has an inner diameter ID of about 0.016 inches (0.4 mm), an outer diameter OD of about 0.019 inches (0.5 mm), and a length of about 59 inches (1500 mm). The inner diameter ID of inner liner 14 provides clearance for a standard 0.014 inch guidewire 26. Outer diameter OD of inner sleeve 14 provides clearance for outer layer 12 and tissue-removing element 20. The space provided between the inner liner 14 and the outer layer 12 reduces friction between the two components and allows saline between the components to be poured.

Referring to fig. 1, 2, 5 and 7, tissue-removing element 20 extends along longitudinal axis LA from a proximal end adjacent to the distal portion of outer layer 12 to an opposite distal end. Tissue-removing element 20 is operatively connected to motor 43 for rotation by the motor. When the catheter 10 is inserted into a body lumen and the motor 43 rotates the tissue-removing element 20, the tissue-removing element is configured to remove occluded tissue in the body lumen to separate the tissue from the body lumen wall. In one or more embodiments, any suitable tissue-removing element for removing tissue in a body lumen as the body lumen is rotated can be used. In the illustrated embodiment, the tissue removal element 20 comprises an abrading rasp configured to abrade tissue in a body cavity as the motor 43 rotates the abrading rasp. The grinding rasp 20 has a ground outer surface formed, for example, by diamond grit coating, surface etching, or the like. In other embodiments, the tissue-removing elements may include one or more cutting elements having smooth or serrated cutting edges, macerators, thrombectomy lines, or the like.

Referring to fig. 7, a cavity 72 extends longitudinally through tissue-removing element 20 such that the tissue-removing element defines openings at its proximal and distal ends. Cavity 72 includes a first diameter portion 74 extending distally from the proximal end of tissue-removing element 20 and a second diameter portion 78 extending distally from the first diameter portion, forming a first shoulder 80 disposed between the first and second diameter portions. Third diameter portion 82 extends distally from second diameter portion 78 and forms a second shoulder 84 between the second diameter portion and the third diameter portion. Fourth diameter portion 86 extends distally from the third diameter portion to the distal end of the tissue-removing element and forms a third shoulder 88 between the third diameter portion and the fourth diameter portion. The diameters of the first diameter portion 74, the second diameter portion 78, the third diameter portion 82, and the fourth diameter portion 86 are constant along their lengths. In the illustrated embodiment, diameter D1 of first diameter portion 74 is greater than diameter D2 of second diameter portion 78, diameter D2 is greater than diameter D3 of third diameter portion 82, and diameter D3 is greater than diameter D4 of fourth diameter portion 86. In one embodiment, the diameter D1 of the first diameter portion 74 is about 0.037 inches (0.95 millimeters), the diameter D2 of the second diameter portion 78 is about 0.035 inches (0.9 millimeters), the diameter D3 of the third diameter portion 82 is about 0.033 inches (0.85 millimeters), and the diameter D4 of the fourth diameter portion 86 is about 0.031 inches (0.8 millimeters). Other cross-sectional dimensions are also contemplated without departing from the scope of the present disclosure.

Referring to fig. 4 and 7-10, bushing 90 is received in cavity 72 of tissue-removing element 20 and surrounds inner sleeve 14. Bushing 90 includes a central ring portion 92, a proximal ring portion 94 extending proximally from the central ring portion, and a distal ring portion 96 extending distally from the central ring portion. Each ring portion of bushing 90 defines a passage 99 extending through the bushing, the passage 99 receiving a portion of inner sleeve 14. In the illustrated embodiment, the outer diameter of the central ring portion 92 is greater than the outer diameter of the proximal ring portion 94 and the distal ring portion 96. The center ring portion 92 is disposed in the second diameter portion 78 of the cavity 72, the proximal ring portion 94 is disposed in the first diameter portion 74, and the distal ring portion 96 is disposed in the second diameter portion 78 and the third diameter portion 82. in one embodiment, the bushing 90 is made of Polyetheretherketone (PEEK) and Polytetrafluoroethylene (PTFE). However, the bushing 90 may be formed from other materials without departing from the scope of the present disclosure.

A first bearing 98 is disposed about the proximal ring portion 94 of the bearing 90 and a second bearing 100 is disposed about the distal ring portion 96 of the bearing. The outer diameter D5 of the first bearing 98 is greater than the outer diameter D6 of the second bearing 100. In one embodiment, the bearings 98, 100 are made of zirconia. First bearing 98 is configured to align with first diameter portion 74 of cavity 72 in tissue-removing element 20 and is disposed between the distal end of outer layer 12 at the proximal end of the first bearing and central ring portion 92 and first shoulder 80 of bushing 90 at the distal end of the first bearing. The second bearing 100 is configured to align with the second diameter portion 78 of the cavity 72 and is disposed between the second shoulder 84 at the distal end of the second bearing and the central ring portion 92 of the bushing 90 at the proximal end of the second bearing. Thus, bushing 90 and bearings 98, 100 remain within cavity 72 of tissue-removing element 20. In general, bushing 90 and bearings 98, 100 may be considered a coupling assembly 57 for coupling inner sleeve 14 to tissue-removing element 20.

Referring to fig. 4, the inner surface of bushing 90 is fixedly attached to inner liner 14 such that the inner liner is coupled to tissue-removing element 20 by the bushing. In one embodiment, an adhesive, such as an epoxy glue, bonds bushing 90 to inner liner 14. Thus, bushing 90 does not rotate about inner liner 14. The outer layer 12 is directly and fixedly attached to the tissue-removing element 20. The tissue-removing element 20 may be fixedly attached to the distal end of the outer layer 12 by any suitable means. In one embodiment, an adhesive bonds outer layer 12 to tissue-removing element 20. The outer layer 12 is received in the first diameter portion 74 of the cavity 72 with the distal end of the outer layer abutting the first bearing 98. However, the outer layer 12 is not directly attached to the bushing 90, bearings 98 and 100, or inner liner 12. Thus, rotation of outer layer 12 and tissue-removing element 20 is not transferred to inner sleeve 14 such that the inner sleeve also rotates. Instead, tissue-removing element 20 rotates about bushing 90 and bearings 98, 100. And because the inner sleeve is securely attached to the bushing 90 held within the cavity 72 of the tissue-removing element 20 by the outer layer 12, the inner sleeve 14 is coupled to the outer layer by a bushing and bearing arrangement. Thus, translational movement of outer layer 12 is transferred to inner liner 14 such that as one of the inner and outer layers is advanced or retracted within the body lumen, the inner and outer layers will translate together. This configuration prevents outer layer 12 and tissue-removing element 20 from advancing past the distal end of inner sleeve 14 and contacting guidewire 26. As a result, the following configuration is prevented: in this configuration, inner sleeve 14 is not positioned to isolate guidewire 26 from outer layer 12 and tissue-removing element 20.

Inner liner 14 extends through outer layer 12 and past the distal end of tissue-removing element 20. Fourth diameter portion 86 of cavity 72 is sized to allow inner liner 14 to pass through with little clearance. Inner diameter D4 provides clearance between tissue-removing element 20 and inner sleeve 14 to reduce friction between the components. Thus, the tissue-removing elements 20 are shaped and arranged to extend around at least a portion of the inner and outer liners 14, 12 and thus provide a relatively compact assembly for abrading tissue at the distal portion of the catheter 10.

Referring to fig. 7, the outer surface of the body of tissue-removing element 20 includes a proximal section 102, an intermediate section 104, and a distal section 106. The diameter of proximal section 102 increases from the proximal end of tissue-removing element 20 to intermediate section 104. The intermediate section has a constant diameter and extends from the proximal section 102 to the distal section 106. The diameter of distal section 106 tapers from intermediate section 104 to the distal end of tissue-removing element 20. The transition between the proximal section 102 and the intermediate section 104 forms a first angle a between the proximal section and the intermediate section. In one embodiment, the angle α is less than about 170 degrees. In one embodiment, angle α is about 165 degrees. Similarly, the transition between the intermediate section 104 and the distal section 106 forms a second angle β between the intermediate section and the distal section. In one embodiment, the angle β is less than about 170 degrees. In one embodiment, the angle β is about 165 degrees. Tapered proximal and distal portions 102, 106 provide tissue-removing element 20 with a generally forward and rearward wedge configuration to wedge the narrowed tissue channel open as it simultaneously removes tissue using the abrasive action of the tissue-removing element.

Referring to fig. 1 and 2, to remove tissue in a body lumen of a subject, a physician inserts a guidewire 26 into the body lumen of the subject to a location distal to the tissue to be removed. The physician then inserts the proximal portion of guidewire 26 through guidewire lumen 24 of inner sleeve 14 and through handle 40 such that the guidewire extends through proximal port 47 in the handle. Inner liner 14 may also extend through handle 40 and out proximal port 47. With the catheter 10 loaded onto the guidewire 26, the physician advances the catheter along the guidewire until the tissue-removing element 20 is positioned proximal to and adjacent to the tissue. When tissue-removing element 20 is positioned proximal to and adjacent to tissue, the physician uses actuator 42 to actuate motor 43 to rotate outer layer 12 and the tissue-removing element mounted thereon. As the tissue-removing element is rotated, tissue-removing element 20 abrades (or otherwise removes) tissue in the body lumen. While tissue-removing element 20 is rotated, the physician may selectively move outer layer 12 and inner liner 14 distally along guidewire 26 to abrade tissue and, for example, increase the size of the passage through the body lumen. The physician may also move outer layer 12 and inner sleeve 14 proximally along guidewire 26, and may repeatedly move the components in the distal and proximal directions to achieve a back and forth movement of tissue-removing element 20 across the tissue. During the abrading process, bushing 90 and bearings 98, 100 couple inner sleeve 14 to outer layer 12 and allow the outer layer and tissue-removing element to rotate about the inner sleeve. Inner liner 14 isolates guidewire 26 from rotating outer layer 12 and tissue-removing element 20 to protect the guidewire from damage by rotating components. Thus, inner sleeve 14 is configured to withstand the twisting and frictional effects of rotating outer layer 12 and tissue-removing element 20 without transferring those effects to guidewire 26. Further, the coupling of inner sleeve 14 and tissue-removing element 20 allows for the transfer of movement of the inner sleeve, such as translational movement within a body lumen, to outer layer 12 and the tissue-removing element to move the outer layer and the tissue-removing element with the inner sleeve through the body lumen. When the physician is finished using the catheter 10, the catheter can be withdrawn from the body cavity and detached from the guidewire 26 by sliding the catheter proximally along the guidewire. The guidewire 26 used for the milling procedure may remain in the body lumen for subsequent procedures.

When introducing elements of the present invention or one or more embodiments thereof, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

As various changes could be made in the above devices, systems, and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.