A debulking catheter includes an advancer for advancing a tissue-removing element, and a linear-force indicator. The linear-force indicator provides feedback to the user based on an amount of linear force being applied to the advancer.

FIELD

The present technology is generally related to a debulking catheter for debulking a body lumen.

BACKGROUND

Debulking catheters are used to remove unwanted tissue in body lumens. As an example, atherectomy catheters are used to remove tissue from a blood vessel to open the blood vessel and improve blood flow through the vessel. Atherectomy catheters typically abrade, cut, excise, ablate or otherwise remove the unwanted tissue.

SUMMARY

In one aspect, the present disclosure provides a debulking catheter for debulking a body lumen. The debulking catheter comprises a catheter body extending distally from the handle and configured to be inserted into the body lumen. The catheter body has a length and includes a drive shaft extending along the length of the catheter body. The drive shaft is configured to be rotated about its longitudinal axis. A tissue-removing element is coupled to and configured to be rotated by the drive shaft. The tissue-removing element is configured to remove tissue from the body lumen as it is rotated by the drive shaft. A handle is operatively coupled to a proximal end of the catheter body. The handle includes a drive operatively coupled to the drive shaft and configured to impart rotation of the drive shaft about its longitudinal axis. An advancer of the handle is operatively coupled to the drive to selectively translate the drive together with the drive shaft and the burr to linearly advance and retract the drive shaft and the burr relative to the handle. A linear-force indicator of the handle is configured to provide feedback to the user indicating an amount of linear force being applied to the advancer.

DETAILED DESCRIPTION

The present disclosure relates to a rotational debulking catheter for removing tissue in a body lumen. As an example, the rotational debulking catheter is suitable for use as rotational atherectomy device 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 blood vessel wall (e.g., coronary arterial wall, venous wall etc.), such as shown inFIG.13. The catheter 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. The features of the disclosed embodiments are not limited to treatment of blood vessels. For example, the disclosed features may also be used for treating 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.

Referring now toFIG.1, one embodiment of a rotational tissue-removing catheter for removing tissue in a body lumen is generally indicated at reference number10. The catheter10includes an elongate catheter body11sized for being received in a blood vessel of a subject. Thus, the catheter body11may 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.1and2, the catheter body11comprises an elongate drive shaft, e.g., drive coil12, disposed around an elongate inner liner14. The drive coil12and inner liner14extend along a longitudinal axis LA of the catheter body11from a proximal end portion16to a distal end portion18of the catheter body. An abrasive burr20(or other tissue-removing element) is disposed on a distal end of the drive coil12and is configured for rotation to remove tissue from a body lumen. The abrasive burr20may have an abrasive outer surface formed, for example, by a diamond grit coating, surface etching, or the like. An isolation sheath22(FIG.1) is disposed around the drive coil12. The drive coil12and the inner liner14are both configured to translate relative to the isolation sheath22. The isolation sheath22isolates the body lumen from at least a portion of the drive coil12and inner liner14. The space between the isolation sheath22and the drive coil12allows for the drive coil to rotate within the sheath and provides an area for saline perfusion between the sheath and drive coil. The inner liner14defines a guidewire lumen24for 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 all the way through the length of the inner liner14such 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). In use, the guidewire26may extend about 40 mm (1.6 inches) past a distal end of the inner liner14.

Referring toFIGS.1,3and4, the catheter10further includes a handle, generally indicated at40, coupled to a proximal end of the catheter body11. The handle40comprises a housing40athat supports the components of the handle. The housing40asupports an actuator42(e.g., a lever, a button, a dial, a switch, or other device, as shown inFIG.1) configured for selectively actuating a drive, generally indicated at44, disposed in the handle to drive rotation of the drive coil12and burr20mounted at the distal end of the drive coil. The drive44is configured to rotate the drive coil12and burr20at speeds of greater than about 80,000 RPM. In one embodiment, as shown inFIG.1, the drive44includes a motor43(e.g., an electric motor), a gear assembly46coupled to the motor, and driveshaft48coupled to the gear assembly and the drive coil12. Torque is transferred from the motor43to the drive coil12. The motor43may be powered by a battery (external or internal) or other internal or external electrical power source. Moreover, a controller50(FIG.1) may be programmed to control operation of the catheter10. The drive44may be of other types, such as a pneumatic drive, a hydraulic drive, or other types of drives suitable for driving rotation of the drive coil.

Referring toFIGS.1,3, and4, an advancer45(e.g., a slide) of the handle40is operatively coupled to the drive44to selectively translate (e.g., linearly advance) the drive together with the drive coil12and the burr20to advance and retract the drive coil and burr relative to the handle and the isolation sheath22at the distal end of the sheath. The drive44may be coupled to a linear rail or other track or guide, such as illustrated in other embodiments inFIGS.8-12. The housing40aof the handle40may define a slot54(FIGS.3and4) which limits the movement of the slide45relative to the handle. Thus, the length of the slot54determines the amount the burr20may be linearly advanced or displaced from the distal end of the isolation sheath22during debulking operation. In one embodiment, the slot54has a length of about 70 mm (2.8 inches), and thus the burr may be selectively advanced 70 mm (2.8 inches) between a fully retracted, proximal position to a fully advanced, distal position relative to the isolation sheath22. A guidewire lock47(FIG.1) on the handle40is selectively actuated to lock the guidewire26relative to the catheter10to inhibit linear movement of the catheter on the guidewire while allowing rotation of the drive coil12and burr20on the guidewire.

Referring toFIGS.3and4, the catheter10further includes a linear-force indicator, generally indicated at60, configured to provide an indication or feedback to the user as to the amount of linear force the user is applying to the advancer45during the debulking operation. During debulking and as the burr20is being rotated by the drive44, the user applies a linear force to the advancer45to move the rotating burr against the obstruction (e.g., lesion L) in the lumen. The obstruction, in turn, applies a counterforce back to the advancer45and to the user. In some situations, such as when the obstruction is relatively difficult to abrade, the user may continue to apply an increasing amount of linear force to the advancer45in an attempt to clear the obstruction. This may lead to tissue damage and/or damage to the motor43if the force continues to increase. The linear-force indicator60is configured to indicate or provide feedback to the user when an amount of force being applied to the advancer45is greater than a predetermined threshold amount.

Referring still toFIGS.3and4, the linear-force indicator60includes an articulating coupler, generally indicated at64(broadly, a movable coupler), operatively connecting the advancer45to the drive44such that linear force applied to the advancer is imparted to the drive through the articulating coupler. The articulating coupler64also provides movement of the advancer45relative to the drive44(i.e., slippage) when a linear force greater than the threshold linear force is applied to the advancer. Accordingly, when the linear force applied to the advancer45by the user is less than or equal to the predetermined threshold amount, then the applied linear force is applied to the drive44and the articulating coupler64does not slip (i.e., the coupler is in a non-articulated position). However, when the linear force applied to the advancer45by the user is more than the predetermined threshold amount, then the applied linear force is not applied to the drive44(or the force imparted to the drive is substantially decreased) and instead the articulating coupler64slips and the advancer moves relative to the drive (i.e., the coupler is moved to an articulated position). In the illustrated embodiment, the articulating coupler64includes a fixed arm68and an articulating arm70hingedly or pivotally connected to one another at a hinged or pivot connection. The fixed arm68is fixedly secured to the drive44(e.g., to the motor43) and the articulating arm70is fixedly coupled to the advancer45so that the advancer is rotatable or pivotable (broadly, movable) relative to the drive44about a pivot axis. Other types of connections for the articulating coupler are possible.

The articulating coupler64is biased to its neutral or non-articulated position, such as shown inFIGS.3and4, by a biasing device74, such as one or more springs or other resilient devices. In the illustrated embodiment, the springs74extend between and are engageable with lever arms76of the articulating arm70and the drive44. The lever arms76are pivotable about the pivot axis with the advancer45and are diametrically opposed relative to the pivot axis. When advancing the advancer45distally to move the burr20toward the occlusion (e.g., lesion L as shown inFIGS.3and4), a distal one of the springs74inhibits the advancer from pivoting relative to the drive44about the pivot axis until and unless the linear force applied to the advancer is greater than the predetermined threshold amount, at which time the force overcomes the biasing forces of the spring74and the articulating coupler64articulates to an articulated position. This articulation is felt by the user and indicates to the user that the force applied to the advancer45may need to be decreased. Among other suitable parameters, the one or more springs74are selected to apply the appropriate amount of biasing force to correspond to the desired predetermined threshold amount of linear force. At least some of the excessive linear force applied to the advancer45that is greater than the threshold force is absorbed by the spring(s)74and not transferred to the drive or burr, thereby, in some situations, limiting excessive force being transmitted to the occlusion in the body lumen.

The articulating coupler64may be biased to its non-articulated position in other ways, using other types of spring or resilient devices or in other ways. For example, another embodiment of a catheter110is shown inFIGS.5and6. This catheter110is similar to the embodiment shown inFIGS.3and4, with like components indicated by corresponding reference numeral plus 100. The difference between this catheter110and the catheter10is that this embodiment includes a single spring174(e.g., a compression spring) received on the fixed arm168of the coupler164. When advancing the advancer145distally to move the burr120toward the occlusion, the spring174inhibits the advancer from pivoting relative to the drive144about the pivot axis until and unless the threshold linear force is applied to the advancer, at which time the force overcomes the biasing force of the spring and the coupler articulates to an articulated position.

In one or more embodiments, such as each of the catheters10,110, the linear-force indicator60,160includes an electrical threshold force detector80,180that is activated when the linear force applied to the advancer45,145is greater than the predetermined threshold amount. It is understood that the electrical threshold force detector80,180may be included independent of the articulating coupler64,164and vice versa. In the illustrated embodiment, the electrical threshold force detector80,180includes an electrical switch that is open when the articulating coupler64,164is in the non-articulated position and closed when the articulating coupler is in the articulated position. The illustrated articulating lever arm76,176forms a first electrical terminal (e.g., a positive electrical terminal) of the switch which makes electrical contact with a second electrical terminal88,188(e.g., a negative electrical terminal) to close a circuit, which in turn activates an alarm90,190indicating to the user that the linear force is greater than the predetermined threshold amount. The first electrical terminal may be on or part of one of lever arms76,176of the coupler64,164. The alarm90,190may be one or more of an auditory alarm (e.g., a buzzer or beeper), a visual alarm (e.g., a light, or a flashing light, such as an LED), or a haptic alarm (e.g., vibration). Closing the switch may also actuate reduction in power supplied to the motor43,143, including but not limited to reducing power to zero, to reduce the speed of the motor, and in turn reduce the speed of the rotating burr20,120. When the switch is open (e.g., reopened), the alarm90,190may turn off and the power to the motor may return to normal operating parameters.

Referring toFIGS.7and8, a catheter, generally indicated at210, includes a different embodiment a linear-force indicator, generally indicated at260, configured to provide an indication or feedback to the user as to the amount of linear force the user is applying to the advancer245during the debulking operation. This linear-force indicator260is similar to the first embodiment of the linear-force indicator60, with like components indicated by corresponding reference numeral plus 200. The main difference between the first linear-force indicator60and the present linear-force indicator260is that the present linear-force indicator does not include the articulating coupler. Instead, the present linear-force indicator260includes a slide coupler261coupled to the advancer245to allow the advancer to move relative to the drive244when a linear force greater than the threshold linear force is applied to the advancer. The slide coupler261includes a slide263coupled (e.g., fixedly coupled) to a linear guide265that is fixedly coupled to the drive244. The slide263is linearly moveable (e.g., slidable) on the liner guide265. This embodiment also includes a linear rail, although the rail may be omitted.

A biasing device274, such as one or more springs or other resilient devices, biases the slide coupler261(therefore, the advancer245) to a neutral position, as shown inFIG.7. In the illustrated embodiment, the biasing device includes two compression springs274on the liner guide265and disposed between opposing stops271and the slide263. When advancing the advancer245distally to move the burr220toward the occlusion (e.g., lesion L as shown inFIG.8), a distal one of the springs274inhibits the advancer from sliding linearly relative to the drive244on the linear guide265until and unless the linear force applied to the advancer is greater than the predetermined threshold amount, at which time the force overcomes the biasing forces of the spring274and the advancer moves distally on the liner guide and relative to the drive. This movement is felt by the user and indicates to the user that the force applied to the advancer245may need to be decreased. Among other suitable parameters, the one or more springs274are selected to apply the appropriate amount of biasing force to correspond to the desired predetermined threshold amount of linear force. At least some of the excessive linear force applied to the advancer245that is greater than the threshold force is absorbed by the spring(s)274and not transferred to the drive244or burr220, thereby, in some situations, limiting excessive force being transmitted to the occlusion in the body lumen.

In the illustrated embodiment, the linear-force indicator260includes an electrical threshold force detector280that is activated when the linear force applied to the advancer245is greater than the predetermined threshold amount. It is understood that the electrical threshold force detector280may be included independent of the linear guide265, such as shown inFIGS.11and12, and vice versa. In the illustrated embodiment, the electrical threshold force detector280includes an electrical switch that is open when the advancer245is in the neutral position, and closed when the advancer is moved (i.e., displaced) to the distal (or proximal) position. The illustrated slide263includes a first arm or portion277forming a first electrical terminal (e.g., a positive electrical terminal) of the switch which makes electrical contact with a second electrical terminal288(e.g., a negative electrical terminal) to close a circuit, which in turn activates an alarm290indicating to the user that the linear force is greater than the predetermined threshold amount. The first electrical terminal277may be on or part of the advancer245. The second electrical terminal288may be on or part of the post271. The alarm290may be one or more of an auditory alarm (e.g., a buzzer or beeper), a visual alarm (e.g., a light, or a flashing light, such as an LED), or a haptic alarm (e.g., vibration). Closing the switch may also actuate reduction in power supplied to the motor of the drive244, including but not limited to reducing power to zero, to reduce the speed of the motor, and in turn reduce the speed of the rotating burr220. When switch is open (e.g., reopened), the alarm290may turn off and the power to the motor may return to normal operating parameters.

Referring toFIGS.9and10, another embodiment of a linear-force indicator, generally indicated at360, is similar to the linear-force indicator260, with like components indicated by corresponding reference numeral plus 100. The present linear-force indicator360further includes a slide potentiometer391associated with the advancer345. In particular, the slide potentiometer391(e.g., a slide pot) indicates the linear position of the advancer345(and slide363) relative to potentiometer (and the drive344). The linear guide may be omitted. A signal or data from the slide potentiometer391may be used by a controller397(e.g., a processor and associated memory) to determine the relative position of the advancer345. In one example, when a relatively low or moderate force is applied to the advancer345such that the advancer moves relative to the drive344but does not move to the extent necessary to close the switch, the controller397may give feedback to the user, such as by reducing the speed of the burr320and/or giving a warning (e.g., tactile, auditory, and/or visual), based on the signal generated by the potentiometer indicating the linear position of the advancer. Thus, the slide potentiometer391facilitates feedback to the user before the maximum amount of linear force is reached whereby the switch is closed and the motor may be stopped and the rotational speed of the burr320is reduced to zero. It is understood that the switch, including the second electrical terminal388, may be omitted, and the controller397may determine a threshold linear movement based on the signal generated by the side potentiometer, whereby the motor is stopped.

Referring toFIGS.11and12, a catheter, generally indicated at410, includes a different embodiment of a linear-force indicator, generally indicated at460, configured to provide an indication or feedback to the user as to the amount of linear force the user is applying to the advancer445during the debulking operation. In this embodiment, the advancer445is not moveable relative to the drive444, or at least any movement is nominal and/or would not be readily noticed by the user. Instead, the linear-force indicator460includes one or more load cells499(e.g., button load cells) configured to sense or detect linear force applied to the advancer445. The load cells499are coupled to the drive444and the advancer445, e.g., arms of the advancer, engage the load cells. Electrical signals generated by the load cells499may be used by a controller497to determine the amount of force being applied to the advancer445and/or determine whether a threshold amount of force is exceeded and/or control the motor based on the detected amount of force. For example, the controller497may be configured to selectively warn or indicate to the user (e.g., audible, tactile, and/or visual warning490) when the force applied to the advancer is approaching a threshold amount. In one example, the controller497may be configured to selectively reduce the speed of the motor based on the signals generated by the load cell499. The controller497may also be configured to stop the motor of the drive444and/or provide a suitable warning or indication when a threshold amount of force is reached or exceeded.

In an exemplary method of use, the catheter of any of the described embodiments is inserted into the body lumen (e.g., blood vessel) to deliver the tissue-removing element (e.g., burr) to the lesion L, such as shown inFIG.13. In one example, a guidewire is delivered to the lesion L and the catheter is then slid along the guidewire to the lesion L. At the lesion, the catheter is operated to rotate the tissue-removing element to debulk the lesion. During rotation of the tissue-removing element, the advancer is moved linearly to impart linear (e.g., distal and/or proximal) movement of the tissue-removing element at the lesion. With each embodiment, the corresponding linear-force indicator provides feedback to the user indicating an amount of linear force being applied to the advancer in the manner set forth above with respect to each embodiment.