Tissue-removing catheter with guidewire isolation liner

A tissue-removing catheter for removing tissue in a body lumen includes an elongate body and a tissue-removing element mounted on a 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 a 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.

FIELD

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

BACKGROUND

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.

SUMMARY

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 still another aspect, a method 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.

DETAILED DESCRIPTION

Referring to the drawings, and in particularFIG. 1, a rotational tissue-removing catheter for removing tissue in a body lumen is generally indicated at reference number10. The illustrated catheter10is 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 catheter10may 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 catheter10is sized for being received in a blood vessel of a subject. Thus, the catheter10may have a maximum size of 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 mm) and may have a working length of 20, 30, 40, 60, 80, 100, 120, 150, 180 or 210 cm 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 toFIGS. 1 and 2, the catheter10comprises an elongate outer layer12(broadly, an elongate body) disposed around an elongate inner liner14. The outer layer12and inner liner14extend along a longitudinal axis LA of the catheter from a proximal end portion16to a distal end portion18of the catheter. A tissue-removing element20is disposed on a distal end of the outer layer12and is configured for rotation to remove tissue from a body lumen as will be explained in greater detail below. A sheath22(FIG. 1) is disposed around the outer layer12. The outer layer12and the inner liner14are both configured to translate relative to the sheath22. The outer layer12and inner liner14are also configured to translate relative to each other. The catheter10is sized and shaped for insertion into a body lumen of a subject. The sheath22isolates the body lumen from at least a portion of the outer layer12and inner liner14. The inner liner14defines a guidewire lumen24(FIG. 5) for slidably receiving a guidewire26therein so that the catheter10can be advanced through the body lumen by traveling along the guidewire. The guidewire can be a standard 0.014 inch outer diameter, 300 cm length guidewire. In certain embodiments, the inner liner14may have a lubricious inner surface for sliding over the guidewire26(e.g., a lubricious surface may be provided by a lubricious polymer layer or a lubricious coating). In the illustrated embodiment, the guidewire lumen24extends from the proximal end portion16through the distal end portion18of the catheter10such that the guidewire26is extendable along an entire working length of the catheter10. In one embodiment, the overall working length of the catheter10may be between about 135 cm (53 inches) and about 142 cm (56 inches).

The catheter10further comprises a handle40secured at the proximal end portion16of the catheter. The handle40supports an actuator42(e.g., a lever, a button, a dial, a switch, or other device) configured for selectively actuating a motor43disposed in the handle to drive rotation of the outer layer12, and tissue-removing element20mounted at the distal end of the outer layer. The motor43is coupled to the outer layer12by a gear assembly44and drive48supported by the handle40. A slide or advancer45is positioned on the handle40and operatively coupled to the outer layer12for movement of the outer layer relative to the handle to advance and retract the outer layer and tissue-removing element20. The handle40defines a slot (not shown) which limits the movement of the slide45relative to the handle. Thus, the length of the slot determines the amount of relative movement between the outer layer12and the handle40. A perfusion port46may be disposed at the proximal end16of the catheter10. The port46communicates with a space between the sheath22and the outer layer12for delivering fluid (e.g., saline) to cool the rotating outer layer during use. A proximal port47allows for passage of the guidewire26and inner liner14through the proximal end of the handle40. A guidewire lock (not shown) may be provided on the handle40to lock the guidewire26in 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 handle40. In other embodiments, the power supply may come from an external source.

Referring toFIGS. 1 and 3, the outer sheath22comprises a tubular sleeve configured to isolate and protect a subject's arterial tissue within a body lumen from the rotating outer layer12. The sheath22is fixed to the handle40at a proximal end of the sheath and does not rotate. A hub52mounted on the proximal end of the sheath22attaches the sheath to the handle40. The hub52includes a locking feature54(e.g., threaded luer lock) for engaging the handle40to attach the sheath22to the handle. The sheath22provides a partial enclosure for the outer layer12and inner liner14to move within the sheath. The inner diameter of the sheath22is sized to provide clearance for the outer layer12. The space between the sheath22and the outer layer12allows 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 sheath22is sized to provide clearance with an inner diameter of a guide catheter (not shown) for delivering the catheter10to the desired location in the body lumen. A strain relief56is provided at the proximal end of the sheath22to alleviate tension applied to the proximal end of the sheath22as the sheath is bent during use of the catheter10. In one embodiment, the sheath22has an inner diameter of about 0.050 inches (1.27 mm), an outer diameter of about 0.055 inches (1.4 mm), and a length of about 1500 mm (59 inches). The sheath22can have other dimensions without departing from the scope of the disclosure. In one embodiment, the outer sheath22is made from Polytetrafluorethylene (PTFE). Alternatively, the outer sheath22may comprise a multi-layer construction. For example, the outer sheath22may 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 toFIGS. 1, 2, 4, and 5, the outer layer12may comprise a tubular stainless steel coil configured to transfer rotation and torque from the motor43to the tissue-removing element20. Configuring the outer layer12as a coiled structure provides the outer layer with a flexibility that facilitates delivery of the catheter10through the body lumen. Also, the coil configuration allows for the rotation and torque of the outer layer12to be applied to the tissue-removing element20when the catheter10is traversed across a curved path. The stiffness of the outer layer12also 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 element20. In one embodiment, the outer layer12is relatively stiff such that axial compression and extension of the coil is minimized during movement of the catheter10through a body lumen. For example, the outer layer may have an axial compression stiffness of between about 2 and about 10 N/mm. The coil configuration of the outer layer12is also configured to expand its inner diameter when the coil is rotated so that the outer layer remains spaced from the inner liner14during operation of the catheter10. In one embodiment, the outer layer12has an inner diameter of about 0.023 inches (0.6 mm) and an outer diameter of about 0.035 inches (0.9 mm). The outer layer12may have a single layer construction. For example, the outer layer may comprise a 7 filar (i.e., wire) coil with a lay angle of about 30 degrees. Alternatively, the outer layer12could be configured from multiple layers without departing from the scope of the disclosure. For example, the outer layer12may comprise a base coil layer and a jacket (e.g., Tecothane™) disposed over the base layer. In one embodiment, the outer layer comprises a 15 filar coil with a lay angle of about 45 degrees. The Tecothane™ jacket may be disposed over the coil. Alternatively, the outer layer12may 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 15 filar coil with a lay angle of about 45 degrees, and an outer coil layer comprising a 19 filar coil with a lay angle of about 10 degrees. Outer layer having other configurations are also envisioned.

Referring toFIGS. 1, 2, and 4-6, the inner liner14comprises a multiple layer tubular body configured to isolate the guidewire26from the outer layer12and tissue-removing element20. The inner liner14is extendable through the handle40from a position proximal of the handle to a position distal of the handle. In one embodiment, the inner liner14is coupled to the handle40but is not fixedly attached to the handle40to allow translation of the inner liner relative to the handle. In this embodiment, rotation of the inner liner14is not prevented. However, the clearance between the inner liner14and the outer layer12prevents any rotation of the inner liner caused by the rotation of the outer layer. In this embodiment, both the inner liner14and outer layer12are permitted to translate relative to the handle40. Allowing this co-translation of the inner liner14and outer layer12minimizes compression and extension of the coiled outer layer14when force is applied to the outer layer to move the outer layer within the body lumen. In another embodiment, the inner liner14may be fixedly attached to the handle40to prevent relative movement between the inner liner and the handle. Thus, in this embodiment, the inner liner14remains stationary and is prevented from translating relative to the handle40. Additionally, all rotation of the inner liner14is prevented. In this embodiment, the outer layer12translates over the stationary inner liner14.

The inner liner14has an inner diameter that is sized to pass the guidewire26. The inner liner14protects the guide wire from being damaged by the rotation of the outer layer12by isolating the guidewire from the rotatable outer layer. The inner liner14also extends past the tissue-removing element20to protect the guidewire26from the rotating tissue-removing element. Thus, the inner liner14is configured to prevent any contact between the guidewire26and the rotating components of the catheter10. Therefore, any metal-to-metal engagement is eliminated by the inner liner14. This isolation of the outer layer12and tissue-removing element20from the guidewire26also 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 guidewire26can be used with the catheter10because the guidewire does not have to be configured to withstand the torsional effects of the rotating components. Additionally, by extending through the tissue-removing element20and past the distal end of the tissue-removing element, the inner liner14stabilizes the tissue-removing element by providing a centering axis for rotation of the tissue-removing element about the inner liner.

In the illustrated embodiment, the inner liner14comprises an inner PTFE layer60an intermediate braided layer62comprised of stainless steel, and an outer layer64of polyimide. The PTFE inner layer60provides the inner liner14with a lubricous interior which aids in the passing of the guidewire26though the inner liner. The braided stainless steel intermediate layer62provides rigidity and strength to the inner liner14so that the liner can withstand the torsional forces exerted on the inner liner by the outer layer12. In one embodiment, the intermediate layer62is formed from 304 stainless steel. The outer polyimide layer64provides wear resistance as well as having a lubricous quality which reduces friction between the inner liner14and the outer layer12. Additionally, a lubricious film, such as silicone, can be added to the inner liner14to reduce friction between the inner liner and the outer layer12. In one embodiment, the inner liner14has 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 the inner liner14provides clearance for the standard 0.014 inch guidewire26. The outer diameter OD of the inner liner14provides clearance for the outer layer12and tissue-removing element20. Having a space between the inner liner14and the outer layer12reduces friction between the two components as well as allows for saline perfusion between the components.

In the illustrated embodiment, a marker band66is provided on an exterior surface of the distal end of the inner liner14. The marker band66configures the tip of the inner liner14to 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 liner14may be laser cut to provide a low profile tip. In one embodiment, the marker band66comprises a strip of platinum iridium.

It is further envisioned that the distal end of the inner liner14can have other constructions without departing from the scope of the disclosure. For example, an atraumatic tip68may be attached to the distal end of the inner liner14(FIG. 7). The atraumatic tip68provides a soft, low profile distal end to facilitate delivery of the inner liner14through the body lumen without causing trauma. The atraumatic tip68may have a maximum outer diameter of about 0.02 inches (0.6 mm). Other sizes of the atraumatic tip are also envisioned. In another embodiment, a tapered tip70may be attached to the distal end of the inner liner14(FIG. 8). The tapered tip70may be formed from a layer of material configured to protect the distal end of the inner liner14.

Referring toFIGS. 1, 2, and 9, the tissue-removing element20extends along the longitudinal axis LA from a proximal end adjacent the distal end portion of the outer layer12to an opposite distal end. The tissue-removing element20is operatively connected to the motor43for being rotated by the motor. When the catheter10is inserted into the body lumen and the motor43is rotating the tissue-removing element20, 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 element20comprises an abrasive burr configured to abrade tissue in the body lumen when the motor43rotates the abrasive burr. The abrasive burr20may 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 5 μm of exposed diamond crystals. The tissue-removing element20may 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 cavity72extends longitudinally through the tissue-removing element20such that the tissue-removing element defines openings at its proximal and distal ends. The cavity72receives a portion of the outer layer12for mounting the tissue-removing element20to the outer layer. The cavity72includes a first diameter portion74extending from the proximal end of the tissue-removing element20, a tapered diameter portion76extending from the first diameter portion toward the distal end of the tissue-removing element, and a second diameter portion78extending from the tapered diameter portion to the distal end of the tissue-removing element. The diameters of the first and second diameter portions74,78are constant along their lengths. In the illustrated embodiment, a diameter D1of the first diameter portion74is larger than a diameter D2of the second diameter portion78. In one embodiment, the diameter D1of the first diameter portion74is about 0.035 inches (0.9 mm), and the diameter D2of the second diameter portion78is about 0.022 inches (0.56 mm). The tapered diameter portion76provides a transition between the first and second diameter portions74,78. The outer layer12is received in the first diameter portion74and a distal end of the outer layer abuts the tapered diameter portion76. The tissue-removing element20can be fixedly attached to the distal end of the outer layer12by any suitable means. In one embodiment an adhesive bonds the tissue-removing element20to the outer layer12. The inner liner14extends through the outer layer12and the second diameter portion78of the tissue-removing element20. The second diameter portion78is sized to pass the inner liner14with a small clearance. The inner diameter D2provides clearance between the tissue-removing element20and inner liner14to reduce friction between the components and allow a space for saline perfusion. Accordingly, the tissue-removing element20is shaped and arranged to extend around at least a portion of the outer layer12and inner liner14and thus provides a relatively compact assembly for abrading tissue at the distal end portion of the catheter10.

The exterior surface of the tissue-removing element20includes a proximal segment80, a middle segment82, and a distal segment84. A diameter of the proximal segment80increases from the proximal end of the tissue-removing element20to the middle segment82. The middle segment has a constant diameter and extends from the proximal segment80to the distal segment84. The diameter of the distal segment84tapers from the middle segment82to the distal end of the tissue-removing element20. The tapered distal segment84provides the tissue-removing element20with 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 element20is also rounded to provide the tissue-removing element with a blunt distal end.

Referring toFIGS. 1 and 2, to remove tissue in the body lumen of a subject, a practitioner inserts the guidewire26into 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 guidewire26through the guidewire lumen24of the inner liner14and through the handle40so that the guidewire extends through the proximal port47in the handle. The inner liner14may also extend through the handle40and out the proximal port47. With the catheter10loaded onto the guidewire26, the practitioner advances the catheter along the guidewire until the tissue-removing element20is positioned proximal and adjacent the tissue. When the tissue-removing element20is positioned proximal and adjacent the tissue, the practitioner actuates the motor43using the actuator42to rotate the outer layer12and the tissue-removing element mounted on the outer layer. The tissue-removing element20abrades (or otherwise removes) the tissue in the body lumen as it rotates. While the tissue-removing element20is rotating, the practitioner may selectively move the outer layer12and inner liner14distally along the guidewire26to abrade the tissue and, for example, increase the size of the passage through the body lumen. The practitioner may also move the outer layer12and inner liner14proximally along the guidewire26, and may repetitively move the components in distal and proximal directions to obtain a back-and-forth motion of the tissue-removing element20across the tissue. During the abrading process, the inner liner14isolates the guidewire26from the rotating outer layer12and tissue-removing element20to protect the guidewire from being damaged by the rotating components. As such, the inner liner14is configured to withstand the torsional and frictional effects of the rotating outer layer12and tissue-removing element20without transferring those effects to the guidewire26. When the practitioner is finished using the catheter10, the catheter can be withdrawn from the body lumen and unloaded from the guidewire26by sliding the catheter proximally along the guidewire. The guidewire26used for the abrading process may remain in the body lumen for use in a subsequent procedure.

As various changes could be made in the above apparatuses, 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.