Method and system for controlling the rotational speed of a stirrer or catheter

Abstract

A method and device handle having a slide assembly for controlling the rotational speed of a catheter assembly under various rotational loads is disclosed, the method including driving the catheter assembly in a first direction at a target rotational speed, detecting an actual rotational speed of the catheter assembly in the first direction, comparing the target rotational speed of the catheter assembly in the first direction with the actual rotational speed, and stopping driving the catheter assembly in the first direction before completing the predetermined number of rotations in the first direction when the actual rotational speed decreases to a predetermined value over a predetermined time frame.

Description

Technical Field

[0001] The present disclosure generally relates to methods and systems for controlling the rotational speed of a stirrer or catheter, and more particularly, to methods and systems for controlling the rotational speed of a stirrer or catheter within a device handle of a medical device for excising material from the inner wall surface of a body lumen.

Background Art

[0002] Thrombi or blood clots occur within the vascular system as a result of blood coagulation from injury or turbulent blood flow. Due to its ability to restrict blood flow, if a thrombus is generated within a blood vessel lumen, it must be removed. Deep vein thrombosis involves forming a thrombus within a vein that is present deep within the body, such as the femoral vein or the popliteal vein. One risk of the presence of deep vein thrombosis (DVT) is that the thrombus migrates to form an embolus, resulting in impairment of lung function.

[0003] Several methods have been developed to treat deep vein thrombosis. One method is known in which the shaft body of a catheter system is inserted into a blood vessel, and then a drug such as a thrombolytic agent is injected into the embolus portion to dissolve and remove the thrombus. However, this technique for removing thrombi is known to cause bleeding. In addition, within the coronary artery, percutaneous coronary angioplasty (PTCA) may be performed to open an artery affected by plaque or thrombus formation. In this method, the blood vessel is expanded using a balloon, and a stent in a mesh shape or a coil shape remains in the blood vessel as a support for the blood vessel. However, these methods are less likely to be applicable when the plaque in the stenosis is calcified or when the stenosis grows within the bifurcation portion of the coronary artery.

[0004] Treatment has been proposed in which a thrombus is mechanically disrupted and aspirated out of the blood vessel lumen. The thrombus is subsequently removed by a shaft body inserted into the blood vessel. This treatment can reduce or in some cases eliminate the use of drugs overall. Such a system is disclosed in U.S. Patent No. 6,024,751. SUMMARY OF THE INVENTION

[0005] A method and system are disclosed for ensuring proper removal of a stenosis in a blood vessel and reducing the risk of exposing biological tissue and / or the blood vessel to danger by stopping the rotation of an agitator or catheter assembly upon engagement with the biological tissue and / or blood vessel.

[0006] A method is disclosed for detecting the torque of a catheter assembly under various rotational loads, the method including driving the catheter assembly in a first direction at a target rotational speed, detecting the actual rotational speed of the catheter assembly in the first direction, comparing the target rotational speed and the actual rotational speed of the catheter assembly in the first direction, and stopping the driving of the catheter assembly in the first direction before completion of a planned number of rotations in the first direction when the actual rotational speed decreases by a planned value over a planned time frame.

[0007] A device handle for removing substances inside a living body lumen is disclosed. The device handle is a slide assembly, including a drive shaft assembly configured to rotate a catheter assembly, a slide assembly, a motor configured to apply a rotational force to the drive shaft assembly and the catheter assembly, and a processor. The processor is configured to control the driving of the catheter assembly at a target rotational speed in a first direction, detect the actual rotational speed of the catheter assembly in the first direction, compare the target rotational speed and the actual rotational speed of the catheter assembly in the first direction, and stop the driving of the catheter assembly in the first direction before the completion of the planned number of rotations in the first direction when the actual rotational speed decreases by a planned percentage over a planned time frame.

[0008] A method for removing substances from the inner wall surface of a living body lumen, the method comprising inserting a catheter assembly into the living body lumen, the catheter assembly including a radially expandable agitator that is rotatable by the catheter assembly and axially translatable, disposing the radially expandable agitator distally of a stenosis in the living body lumen, accelerating the radially expandable agitator in a first direction to expand the diameter of the radially expandable agitator, excising the stenosis inside the living body lumen with the radially expandable agitator in an expanded state to release the substance from the stenosis, and accelerating the radially expandable agitator in a second direction to reduce the diameter of the radially expandable agitator.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0033] In the following, embodiments of the present disclosure will be described with reference to the drawings. For ease of explanation, the dimensional ratios in the drawings are exaggerated and thus, in some cases, different from the actual ratios.

[0034] Figure 1A is a perspective view of a medical device 100, which includes a handle 110 having a slide assembly 120 for use with a catheter assembly 130 according to an exemplary embodiment. As shown in Figure 1A, the medical device 100 may be used in a therapy (treatment) for excising a stenosis or occlusion caused by plaque, thrombus, etc. inside a blood vessel (not shown). In this specification, the side of the device 100 inserted into the blood vessel is referred to as the "distal side", and the hand-operated side is referred to as the "proximal side".

[0035] As shown in Figure 1A, the handle 110 includes a guide rail assembly 112 having one or more passages 114 configured to receive the slide assembly 120. The catheter assembly 130 is configured to be mounted on or received by the distal portion 121 of the slide assembly 120. According to an exemplary embodiment, the slide assembly 120 may include a plurality of bearings, such as ball bearings, configured to move on the passage 114 for smoother operation. For example, according to an exemplary embodiment, the plurality of bearings may be four 10mm ball bearings.

[0036] According to an exemplary embodiment, the medical device 100 is preferably configured to have a manual retraction of, for example, about 250 mm to 350 mm, preferably at least 300 mm. For example, a plurality of markings or indicia 118 may be provided on the inner surface 116 of the handle 110 to assist the operator in determining the axial displacement amount of the agitator of the catheter assembly 130 during use. According to an exemplary embodiment, the retraction is only a manually controlled retraction. As shown in Figure 1A, the handle 110 may include a plurality of cover plates, such as an upper front cover plate and a rear cover plate. According to an exemplary design, for example, the handle 110 may have a height of about 75 mm to 90 mm, a width of about 80 mm to 100 mm, and a length of about 300 mm to 400 mm.

[0037] According to an exemplary embodiment, the handle 110 is preferably designed to detect and stop, for example, an agitator 132 that is part of the catheter assembly 130 when the agitator 132 engages the blood vessel wall. For example, according to an exemplary embodiment, a control system, such as a processor or controller inside the slide assembly 120 of the handle 110, may be configured to have a blood vessel detection condition that can be detected by a 180-degree blood vessel twist, where the 180-degree blood vessel twist is equal to 180 degrees plus 90 degrees in the luer connection to the catheter assembly (or catheter) 130. According to an exemplary embodiment, the handle 110 is configured such that, for example after detection of a blood vessel twist, the luer connection 210 to the catheter assembly 130 stops within 360 degrees.

[0038] As shown in FIG. 1B, the catheter assembly 130 of the medical device 100 may include an agitator 132. According to an exemplary embodiment, the agitator 132 may be arranged or installed on the distal end or distal portion of the catheter assembly 130. The agitator 132 may be, for example, an excision unit that is radially expandable and contractible. For example, the agitator 132 may be a mechanical agitator along the treatment length of the catheter assembly 130 for mechanically agitating a clot at the treatment site and / or for dispersing a lytic agent at the treatment site. The mechanical agitator may include a radially expandable agitator 132 that is rotatable and / or axially translatable by the catheter assembly 130. According to an exemplary embodiment, the radially expandable agitator 132 of the catheter assembly 130 may be a self-expanding type, such as a nitinol (Ni-Ti) cage 134. According to an exemplary embodiment, the radially expandable agitator has a mass 136 on the distal end that provides a moment of inertia. For example, as shown in FIG. 1B, the mass 136 may be generated from a collection of distal ends of a material that constitutes the radially expandable agitator 132, such as nitinol. According to an exemplary embodiment, the agitator 132 may have a helical shape and may be configured to expand and contract when accelerated and decelerated, respectively, due to the moment of inertia and the helical design.

[0039] According to an exemplary embodiment, for example, as the constituent material of the stirrer 132, a shape memory alloy having a shape memory effect or superelasticity by heat treatment, or stainless steel may preferably be used. As the shape memory alloy, a Ni-Ti based alloy, a Cu-Al-Ni based alloy, a Cu-Zn-Al based alloy, and a combination of shape memory alloys are preferably used.

[0040] According to an exemplary embodiment, for example, the stirrer 132 of the catheter assembly 130 may include an elastic element, and the elastic element may be radially constrained to have a small profile (small diameter), and may be released from the radial constraint to have a large profile (large diameter) having a non-linear geometry. The radial constraint may be provided by a sleeve or a sheath, and the sleeve or sheath may cover and uncover the radially expandable stirrer by being advanced and retracted axially with respect to the catheter assembly 130. Thus, the catheter assembly 130 may be introduced into the treatment site inside the vascular structure by the covered (and thus radially constrained) expandable stirrer 132. After reaching the desired treatment site S, the outer sheath 230 (FIG. 7) may be retracted axially to release the radially expandable stirrer 132, and may expand to engage a clot in the blood vessel. The stirrer 132 may then be rotated and / or translated axially to engage and fragment the clot, for example, in combination with the release of a thrombolytic agent.

[0041] Figure 2 is another perspective view of handle 110 having slide assembly 120 for use with an agitator or catheter, according to an exemplary embodiment. As shown in Figure 2, slide assembly 120 may include a drive module frame 122 configured to receive drive shaft assembly 124. Drive shaft assembly 124 may include, for example, a drive shaft having a press-fit gear and cord wheel attachment 126. According to an exemplary embodiment, for example, an extendable motor shaft may be used to eliminate the need for a separate drive shaft. Slide assembly 120 also includes motor 128. Drive shaft assembly 124 may include a drive gear that meshes with a driven gear (or rotating shaft) of motor 128. Motor 128 may function as a drive source including a rotating shaft to which the drive gear is fixed.

[0042] According to an exemplary embodiment, motor 128 may be configured to have an operating voltage of, for example, about 6 to 12 volts (V). For example, according to an exemplary embodiment, the rating of a motor having a high torque coefficient of, for example, about 6.5 mNm / A to 7.0 mNm / A, a peripheral speed constant of about 1350 RPM / V to 1400 RPM / V, and a maximum output of 40 W at 12 V may be set from 4.5 V to 15 V.

[0043] According to an exemplary embodiment, the slide assembly 120 also includes a plurality of electronic components 129, which may be mounted, for example, on a printed circuit board (PCB) (not shown). The electronic components 129 are configured to execute processes as disclosed herein. The electronic components 129 may include, for example, a processor or microprocessor, an operating system, one or more memories or memory cards, and / or a servo motor controller. According to an exemplary embodiment, the processor has at least one of an instruction unit that instructs the motor controller and a calculation unit that calculates a current, for example, an average current monitored about 50 times per millisecond. The motor controller has at least one of a current supply unit to the motor, a determination unit that determines the amount of current to flow, and a monitoring unit for monitoring the flowing current or the current to be flowed. The processor may determine the amount of current to flow. According to an exemplary embodiment, the handle 110 of the medical device 100 may include, for example, a power jack, a USB port, a power switch and a status LED, and an operation switch 204 for the stirrer 132.

[0044] For example, according to an exemplary embodiment, the mechanical drive of the drive shaft assembly 124 may include an encoder and a code wheel, and the mechanical drive is configured to convert a measurement value from the code wheel into a speed measurement value. For example, the encoder may be a three-channel optical encoder, and the optical encoder uses, for example, 500 orthogonal signals per revolution (CPR) for motor control. According to an exemplary embodiment, an index signal is sent to the processor to track the entire rotation. According to an exemplary embodiment, instead of the encoder and the code wheel, a speed sensor may be used.

[0045] According to an exemplary embodiment, for example, the drive shaft assembly 124 is preferably configured to have a peak agitator speed or target of, for example, about 3200 RPM (revolutions per minute) for 8 revolutions, a maximum speed of about 4000 RPM, and a speed of about 3 revolutions of the agitator of the catheter assembly 130 at about 2000 RPM.

[0046] According to an exemplary embodiment, the slide assembly 120 may be programmed to rotate the agitator of the catheter assembly in a manner that includes 8 clockwise rotations, a pause period of, for example, 500 milliseconds (msec), and 8 counterclockwise rotations. According to an exemplary embodiment, the process repeats after a 500 - millisecond pause period. According to an exemplary embodiment, the slide assembly 120 may be programmed or configured such that the rotation of the agitator of the catheter assembly includes 8 clockwise rotations (first direction), a coasting period (or coasting time) during which the agitator or catheter assembly is not under a rotational load (e.g., 3 - 6 rotations, more preferably 4 - 5 rotations), a pause period of, for example, 500 milliseconds (msec), and 8 counterclockwise rotations (second direction). According to an exemplary embodiment, the process repeats, after another coasting period (coasting time), for example, 3 - 6 rotations, more preferably 4 - 5 rotations, and a 500 - millisecond pause period. According to an exemplary embodiment, for example, the coasting period and the pause period may be from 0.4 seconds to 0.6 seconds, more preferably about 0.5 seconds.

[0047] FIG. 3 is a perspective view of the slide assembly 120 and the drive module assembly 124 of the handle 110 according to an exemplary embodiment. As shown in FIG. 3, the handle 120 may also include a power source 125, for example, one or more batteries 127. According to an exemplary embodiment, the one or more batteries 125 preferably have a battery life for motor operation of at least 2.0 hours or more. In addition or alternatively, the slide assembly 120 may include an AC / DC power source.

[0048] FIG. 4 is a perspective view of a portion of the slide assembly 120 according to an exemplary embodiment. As shown in FIG. 4, the slide assembly 120 may include a drive module frame 122 configured to receive a drive shaft assembly 124. The drive shaft assembly 124 may include, for example, a stainless steel shaft having a press-fit gear and a code wheel attachment 126. In addition, according to an exemplary embodiment, one or more batteries 125 may be provided as a power source 127.

[0049] FIGS. 5 and 6 are perspective views of the catheter interface 200 on the handle 110 in an operative position, respectively, without a stirrer and having a stirrer shaft luer 210 attached to the distal end of the drive shaft assembly 124. As shown in FIGS. 5 and 6, the catheter interface 200 includes a connector 210, e.g., a male fitting located on the distal end of the drive shaft assembly 124 and configured to receive a connector 220, e.g., a female connection or shaft luer (or luer lock interface) on the proximal end of the catheter assembly 130.

[0050] According to an exemplary embodiment, as shown in FIGS. 5 and 6, the slide assembly 120 of the handle 110 may include a grip feature 202, the grip feature having a width of, for example, about 65 mm to 75 mm, e.g., 70 mm, and arranged such that the right-handed thumb is at position (1) 201, the right middle finger is at position (2) 203, and the right index finger is at position (3) 205, and these fingers may press an actuation switch 204 that activates the rotation of the stirrer 132. As shown, the handle 120 is designed to be operated by the user's right hand. According to an alternative embodiment, the position of the actuation switch 204 may be movable, for example, to the opposite side, and the slide assembly 120 of the handle 110 may be operated by the user's left hand.

[0051] FIG. 7 is a perspective view of a catheter interface 200 on a handle having a catheter assembly 130 and a stirrer (or stirrer module) (not shown) inserted into an outer sheath 230, the stirrer being located at the distal end (or distal position) of the blood clot. As shown in FIG. 7, the stirrer of the catheter assembly 130 is inserted into the outer sheath 230 and is located at or near the distal end of the blood clot. The constituent materials of the catheter assembly 130 and the outer sheath 230 are not particularly limited. However, for example, polyolefins such as polyethylene and polypropylene, polyesters such as polyamide and polyethylene terephthalate, fluorine-based polymers such as ETFE, polyether ether ketone (PEEK), or polyimide may preferably be used for the catheter assembly 130 and the outer sheath 230. In addition, the catheter assembly 130 and the outer sheath 230 may be configured to include a plurality of materials, or a reinforcing material such as a wire may be incorporated therein.

[0052] According to an exemplary embodiment, as shown in FIG. 7, the catheter interface 200 also includes a receiving region 240 configured to receive a luer (or tee) connection 232 at the proximal end 234 of the outer sheath 230. As shown in FIG. 7, the receiving region 240 may have a pair of side walls 242, 244 and a rounded or oval receiving portion 246.

[0053] FIG. 8 is a perspective view of the catheter interface 200 on the handle, with the tee connection 232 of the outer sheath 230 retracted to accommodate the stirrer (the catheter assembly 130 is not shown). As shown in FIG. 8, the stirrer of the catheter assembly 130 may then be positioned at or near the distal end of the blood clot, and the luer (or tee assembly) 232 on the proximal end 234 of the outer sheath 230 may be moved proximally and installed inside the receiving region 240.

[0054] FIG. 9 is a perspective view of the catheter interface 200 on the slide assembly 120 of the handle 110 after the clamping plate 242 is installed covering the luer (or tee) 232. As shown in FIG. 9, the clamping plate 242 may include a recess 244 that helps secure the luer (or tee) 232 inside the receiving region 240. According to an exemplary embodiment, the luer (or tee) 232 may be a tissue plasminogen activator (TPA) luer or tee 232.

[0055] FIG. 10 is a rotational speed profile 300 showing speed versus rotation according to an exemplary embodiment. As shown in FIG. 10, according to an exemplary embodiment, during the use of the handle 110 and the slide assembly 120 to remove a blood clot, the speed 310 of the agitator of the catheter assembly 130 gradually increases to a target agitator speed of, for example, about 3200 RPM and then decreases. As shown in FIG. 10, for a planned number of rotations, for example 8 rotations, in the first or second direction as disclosed herein at the target rotational speed, a portion of the 8 rotations, i.e., at the initial movement, will be executed at a rotational speed below the target rotational speed of 3200 RPM.

[0056] FIG. 11 is a rotational speed profile 400 showing current / torque versus rotation according to an exemplary embodiment. As shown in FIG. 11, according to an exemplary embodiment, the drive motor 128 is controlled by an electronic component 129, such as a processor, microprocessor, or controller, such that the drive motor 128 follows a speed profile as shown in FIG. 10, but the circuit 129 does not allow the current to exceed a planned or predefined limit 410 as shown in FIG. 11. As shown in FIG. 11, after the initial peak, the current is only allowed to decrease below the current limit 410 or remain in that state. Thus, by limiting the torque, the operator of the medical device 100 may detect when the medical device 100 engages the blood vessel wall and stop the agitator 132.

[0057] For example, according to an exemplary embodiment, the device handle 100 may be configured to control the rotational speed of the catheter assembly 130, such as the agitator 132, under various rotational loads. As described above, the device handle 110 includes a slide assembly 120 having a drive shaft assembly 124 configured to rotate the catheter assembly 130, a motor 128 configured to apply a rotational force to the drive shaft assembly 124 and the catheter assembly 130, and a processor. The processor may execute a process of driving the catheter assembly 130 at a target rotational speed in a first direction (e.g., clockwise), and stop the rotational direction when a predetermined torque limit is exceeded.

[0058] According to an exemplary embodiment, the processor may further execute a process of changing the rotational direction of the catheter assembly 130 from the first direction to the second direction (e.g., counterclockwise), monitoring the rotational speed of the catheter assembly 130, and updating a predetermined torque limit to achieve a target rotational speed for the rotational direction of the catheter assembly 130 in the same direction as the rotational speed of the catheter assembly 130 obtained during the monitoring of the rotational speed. According to an exemplary embodiment, if the rotational speed is less than the target rotational speed, the processor may increase the initial current (or start current) for the next cycle of the rotational direction of the catheter assembly 130.

[0059] According to an exemplary embodiment, changing the rotational direction of the catheter assembly 130 may include reducing the torque applied to the catheter assembly 130 to zero after a planned number of rotations in a first direction, allowing the catheter assembly to come to a stop, and stopping the rotation of the catheter assembly 130 for a planned period of time before rotating the catheter assembly 130 in a second direction. In addition, the process may include rotating the catheter assembly in a second direction during a planned number of rotations in the second direction, reducing the torque applied to the catheter assembly to zero after the planned number of rotations in the second direction, allowing the catheter assembly to come to a stop, and stopping the rotation of the catheter assembly for a planned period of time before rotating the catheter assembly in a first direction. The rotation of the catheter assembly 130 in the first and second directions may be repeated as needed, for example, to treat a stenosis inside a blood vessel. For example, according to an exemplary embodiment, the device handle 100 may be used for inserting the catheter assembly 130 into a body lumen, and the catheter assembly 130 includes an agitator 132 disposed distal to a stenosis in the body lumen and configured to excise the stenosis inside the body lumen by the agitator 132.

[0060] FIG. 12 is a rotational speed profile 500 showing speed versus rotation according to an exemplary embodiment, and FIG. 13 is a diagram 600 showing current / torque versus rotation corresponding to the speed as shown in FIG. 12. As shown in FIGS. 12 and 13, if the actual speed drops by a predetermined percentage, for example Y percent (Y%) over X ms (X milliseconds), according to an exemplary embodiment, a brake or stop mechanism may be applied to the motor 128. For example, instead of using a motor to stop or slow down (i.e., brake) the agitator 132, according to an exemplary embodiment, a mechanical brake pad 920 (FIG. 16) may be used. In addition, during detection of the actual rotational speed of the catheter assembly 130, the received signal may suffer from unwanted distortions (i.e., noise) that make the measurement inaccurate. According to an exemplary embodiment, an average speed value may be used to address unwanted distortions or noise that may be experienced during capture, storage, transmission, processing, or conversion of the signal corresponding to the actual rotational speed of the catheter assembly 130.

[0061] 12 and 13, the device handle 100 may control the torque of the catheter assembly 130 under various rotational loads by driving the catheter assembly 130 in a first direction (e.g., clockwise) at a target rotational speed, detecting an actual rotational speed of the catheter assembly 130 in the first direction, comparing the target and actual rotational speeds of the catheter assembly 130 in the first direction, and stopping driving the catheter assembly 130 in the first direction prior to completion of a predetermined number of rotations in the first direction when the actual rotation decreases by a predetermined percentage over a predetermined time frame. Additionally, as described above, the process may be applied in a second direction, e.g., counterclockwise.

[0062] FIG. 14 is a rotational speed profile 700 showing speed vs. rotation according to an exemplary embodiment, and FIG. 15 is a rotational speed profile 800 showing current / torque vs. rotation corresponding to the speed as shown in FIG. 15. As shown in FIGS. 14 and 15, if the actual speed matches the target speed for the cycle, no change is necessary. However, if the actual speed is less than the target speed, the initial current limit for the next cycle may be increased.

[0063] FIG. 16 is a cross-sectional view of a mechanical brake 900 according to an exemplary embodiment. As shown in FIG. 16, the mechanical brake 900 may include a wire cylinder 910 and a brake pad 920. Upon receiving a signal from the processor, the wire cylinder 910 abuts against the motor shaft 930 and presses the brake pad 920 outward.

[0064] FIG. 17 is a flowchart showing a first loop (i.e., loop 1 or the first cycle) 1100 for speed control, current limit, and operation control for an exemplary system. As shown in FIG. 17, in the first loop 1100, the cycle includes speed control, current limit, and operation control. For example, as shown in FIG. 10, while using the handle 110 and the slide assembly 120 to remove a blood clot, the speed 310 of the agitator 132 of the catheter assembly 130 gradually increases to a target agitator speed of, for example, about 3200 RPM. Once the target agitator speed for a defined number of cycles, e.g., 3200 RPM, is achieved, the agitator speed is then reduced or decreased (i.e., gradually drops, for example, by turning off the current to the agitator 132, thereby allowing the agitator 132 to coast to zero (0) RPM). The rotational direction of the agitator 132 is then changed (i.e., from clockwise to counterclockwise, or from counterclockwise to clockwise). As shown in FIG. 17, for example, for a planned number of rotations, e.g., 8 rotations, in a first direction (i.e., clockwise or counterclockwise) or a second direction (i.e., counterclockwise or clockwise) as disclosed herein at the target rotational speed, a portion of the 8 rotations, i.e., at the initial start, will be executed at a rotational speed less than the target rotational speed of 3200 RPM.

[0065] As shown in FIG. 17, for example, as shown in the rotational speed profile 400 illustrated in FIG. 11, the drive motor 128 is controlled by an electronic component 129, such as a processor, a microprocessor, or a controller, so that the drive motor 128 follows the speed profile as shown in FIG. 10. However, the circuit 129 does not allow the current to exceed a planned or predefined limit 410 as shown in FIG. 11. As shown in FIG. 17, the current limit may be preset, or alternatively, may be calculated by a loop (3) 1200 (FIG. 19). The current is measured at the target rotational speed, and the current limit may be updated based on the current measured at the target rotational speed. The current is then switched off (i.e., no longer provided to the motor 128 driving the catheter assembly 130), and the catheter assembly 130 (i.e., the agitator 132) will coast to a stop for changing the rotational direction of the agitator. Thus, by limiting the torque, the operator of the medical device 100 may detect when the medical device 100 engages the blood vessel wall and stop the agitator 132.

[0066] In addition, in the first loop 1000, for example, the processor may be configured to monitor (i.e., detect) the rotational speed of the agitator 132 and further execute a process of changing the rotational direction of the catheter assembly 130 from a first direction to a second direction (e.g., counterclockwise). In addition, once a planned number of rotations, such as 8 rotations, is completed, the processor may be configured to pause (i.e., completely stop the rotation of) the catheter assembly 130 (and the agitator 132) for a planned time period, such as 0.5 seconds. Once the planned time period has elapsed, the rotational direction of the agitator 132 may be changed to complete the first loop 1000.

[0067] FIG. 18 is a flow diagram showing a second loop (i.e., loop 2) 1100 for speed control and operation control of the agitator 132 of the catheter assembly 130 of an exemplary system. As represented in FIG. 18, a rotational speed profile 500 as shown in FIG. 12 and a current / torque versus rotation as shown in FIG. 13 corresponding to the speed as represented in FIG. 12 may be used to control the speed and current applied to the agitator 132. For example, at the start of a subsequent loop (e.g., the second loop (i.e., loop 2)), the speed of the agitator 132 (i.e., the detected speed) may be compared with a planned target to determine whether the rotational speed of the agitator 132 is above the planned target speed or operating at a low speed (i.e., below or less than the planned target speed). For example, if the rotational speed is within the range of the planned target speed (i.e., RPM), the current provided to the motor 128 driving the catheter assembly 130 and the agitator 132 may be approved and thus no change is required.

[0068] Alternatively, as shown in FIGS. 12, 13, and 18, if the actual speed of the catheter assembly 130 and the agitator 132 drops by a planned percentage, e.g., Y percent (Y%), over X ms (X milliseconds), an emergency condition will occur, and thus a braking or stopping mechanism, e.g., a reverse current brake, may be applied to the motor 128. For example, according to an exemplary embodiment, instead of using the motor to stop or decelerate (i.e., brake) the agitator 132, a mechanical brake pad 920 (FIG. 16) may be used. In addition, during detection of the actual rotational speed of the agitator 132 of the catheter assembly 130, the received signal may be victimized by unwanted deformations (i.e., noise) that may make the measured value inaccurate. According to an exemplary embodiment, an average speed value may be used to cope with unwanted deformations or noise that may be experienced during capture, storage, transmission, processing, or conversion of the signal corresponding to the actual rotational speed of the catheter assembly 130. If the emergency brake is activated, the speed of the agitator is preferably established to be zero (0) RPM and the operation is reset as shown, for example, in the first loop 1000.

[0069] Figure 19 is a flow diagram showing a third loop (i.e., loop 3) 1200 for determining the current limit of the motor 128 of the catheter assembly 130 of an exemplary system. As shown in Figure 19, if a cycle is started and a steady state speed (i.e., RPM) is recorded or detected, the steady state speed is compared to a planned target speed, such as 3200 RPM, and an initial current limit may be evaluated over, for example, 8 detected revolutions. If the actual speed, for example, matches the target speed for the cycle, no change in the current provided to the motor 128 is necessary and the initial current limit may be maintained or held in that state. However, if the actual speed is less than the target speed (i.e., too low) or alternatively greater than the target speed (i.e., too high), the initial current limit of the motor 128 may be increased or decreased for the next cycle. According to an exemplary embodiment, the change in current limit may be for the next cycle in the same direction of rotation as the detected speed, or alternatively, the change in current limit may be for the next rotation in a different direction of rotation.

[0070] FIG. 20 is a flow diagram 1300 showing a process 1310 for speed control, current limiting, and operation control of the agitator of a catheter assembly of an exemplary system according to an exemplary embodiment. As shown in FIG. 20, first, in step 1320, the system is powered “on”. Once the system is powered “on” in step 1320, in step 1330, an initial set of operating parameter values (i.e., planned values and planned operating conditions) is provided to, for example, a controller or a microcontroller (i.e., a processor or a microprocessor and / or one or more memories or memory cards). According to an exemplary embodiment, the initial values and operating parameters may include a set of constant set values, which may include a target rotation angle, a reference rotation speed for loop (2) 1100 (i.e., speed control and operation control of the agitator 132 of the catheter assembly 130), a brake time, and a speed profile. In addition, variable parameters are the values initially set, which are stored in the controller (or microcontroller), updated in each cycle, and may include, for example, the current limit of the agitator and the rotation direction. In step 1340, a determination is made as to whether the system's operating switch is set to either “on” or “off”. In step 1342, if the system operating switch is in the “off” position, the process proceeds to step 1344 where the motor control status is set to “inactive”, and the process returns to step 1340 until the system operating switch is changed to “on”.

[0071] If the system operation switch is changed to "ON" in step 1346, the process proceeds to step 1350, where the planned or set values and variables for the motor controller regarding current limit and target rotation speed are input to the controller. In step 1360, after setting the values and variables for the motor controller, the motor controller status is set or changed to "usable state". In step 1362, the average current value is collected from the motor controller. In step 1364, a new current limit value is calculated based on the actual average current value, and the controller is updated with the new current limit value calculated as the current limit. The calculated new current limit is lower than the previous current limit. The new current limit value may be calculated based on the non - averaged current value, e.g., the raw current data monitored by the motor controller before calculating the average. In step 1370, during the operation of the catheter assembly, the stable rotation speed of the system (i.e., the processor and / or memory and the speed sensor) is collected. In step 1380, the actual rotation angle is evaluated (i.e., calculated), and if the actual rotation angle is less than or equal to the set value (i.e., the planned value), the process proceeds to step 1600 as shown in FIG. 23.

[0072] Alternatively, if the actual rotation angle as calculated in step 1380 is greater than the set value (or the planned value), the process proceeds to step 1382. In step 1382, the rotation speed value is set to zero (0), and that value is sent to the motor controller. The process then proceeds to step 1384, where the determination of the braking time is started, and the process proceeds to step 1400 as shown in FIG. 21.

[0073] FIG. 21 is a flowchart 1900 shown for evaluating the average rotational speed calculated for the cycle of the agitator of a catheter assembly according to an exemplary embodiment, such as shown in loop (3) 1200. As shown in FIG. 21, the process starts at step 1910 where the average rotational speed for one cycle is calculated. In step 1920, if the average speed is less than the set value, the current limit value is set higher than the initial value of this cycle for the next same-direction operation. In step 1930, if the average speed is equal to the set value, the current limit value is set to the same value as the initial value for the next same-direction operation. In step 1940, if the average speed is greater than the set value, the current limit value is set lower than the initial value of this cycle for the next same-direction operation. After each of steps 1920, 1930, and 1940, the direction of rotation, e.g., the direction of rotation of the agitator, is reversed or set in the opposite direction as shown, for example, in step 1410 of FIG. 22.

[0074] FIG. 22 is a continuation of flowchart 1300 showing a routine for speed control, current limit, and operation control of the agitator of the catheter assembly of the exemplary system of FIG. 20. As shown in FIG. 22, in step 1410, the controller sets the direction of rotation opposite to the current direction. In step 1420, the current brake time is calculated. In step 1420, if the brake time is less than the set time, the brake time is recalculated. If the brake time is greater than the set value, the process proceeds to step 1430 where a load value is set and the process proceeds to step 1332 and then returns to step 1340 to determine whether the system operation switch of FIG. 20 is "on" or "off".

[0075] FIG. 23 is a continuation of flowchart 1600 showing routines for speed control, current limiting, and operation control of the agitator of the catheter assembly of the exemplary system of FIG. 20. As shown in FIG. 23, at step 1610, a rotational speed value (i.e., the speed of the rotational value) for the system is collected within one predetermined time period. At step 1620, a determination is made as to whether the collected rotational speed has decreased by a predetermined percentage over the predetermined time period. If the rotational speed collected at step 1620 has not decreased by the predetermined percentage over the predetermined time period, the process proceeds to step 1334. However, if the rotational speed collected at step 1620 has decreased by the predetermined percentage over the predetermined time period, the process proceeds to step 1630 where a safety state routine is executed. At step 1640, the rotational speed value is set to zero (0) and that value is sent to the motor controller. At step 1650, the motor controller is commanded to enter a non-operational state. At step 1660, the motor controller enters the non-operational state and the routine is stopped.

[0076] The foregoing detailed description describes device handles for medical devices and treatment methods. However, the invention is not limited to the exact embodiments and variations described. Various changes, modifications, and equivalents may be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims. It is expressly intended that all such changes, modifications, and equivalents within the scope of the claims be embraced by the claims.

Claims

1. A method for detecting the torque of a catheter assembly by a processor under various rotational loads, wherein the method performed by the processor comprises: applying a driving force to rotate the catheter assembly in a first direction at a target rotational speed; detecting the actual rotational speed of the catheter assembly in the first direction; comparing the target rotational speed and the actual rotational speed of the catheter assembly in the first direction; after the actual rotational speed reaches the value of the target rotational speed, when the actual rotational speed decreases by a predetermined percentage over a time frame indicating a predetermined length of time, stopping the driving that applies the driving force to the catheter assembly in the first direction before the completion of the predetermined number of rotations in the first direction; after the actual rotational speed reaches the value of the target rotational speed and after the completion of the driving that applies the driving force for the predetermined number of rotations in the first direction, causing the catheter assembly that is still rotating in the first direction to travel so as to rotate by a number of rotations less than the predetermined number of rotations; after the causing to travel step, stopping the rotation of the catheter assembly in the first direction; changing the rotational direction of the catheter assembly from the first direction to a second direction; monitoring the actual rotational speeds of the catheter assembly in the first and second directions; A method comprising the above steps.

2. The method according to claim 1, wherein the causing to travel step and the step of stopping the rotation of the catheter assembly are from 0.4 seconds to 0.6 seconds.

3. Updating a predetermined torque limit, which is the upper limit of the torque acting on the predetermined catheter assembly, to achieve the target rotational speed for the catheter assembly in the same direction as the rotational direction of the catheter assembly obtained during the monitoring of the actual rotational speed; The method according to claim 1, further comprising the above step.

4. The step of changing the rotational direction of the catheter assembly comprises: after the predetermined number of rotations in the first direction, reducing the torque applied to the catheter assembly to zero; allowing the catheter assembly to stop; before rotating the catheter assembly in the second direction, stopping the rotation of the catheter assembly for a predetermined time. The method according to claim 1, comprising

5. The method performed by the processor comprises rotating the catheter assembly in the second direction during the planned number of rotations in the second direction, after the planned number of rotations in the second direction, reducing the torque applied to the catheter assembly to zero, allowing the catheter assembly to stop, before rotating the catheter assembly in the first direction, stopping the rotation of the catheter assembly for the planned time, repeating the rotation of the catheter assembly in the first and second directions, The method according to claim 4, comprising

6. The method performed by the processor comprises averaging the actual rotational speeds of the catheter assembly in the first and second directions during detection of the actual rotational speed to address fluctuations in the detected actual rotational speed as a result of noise The method according to claim 5, comprising

7. The method according to claim 1, wherein the target rotational speed is at most 3200 revolutions per minute (rpm).

8. The method according to claim 3, wherein the planned number of rotations in each of the first and second directions at the target rotational speed is 8 rotations.

9. The method performed by the processor, wherein when the actual rotational speed decreases by a planned percentage over a planned time frame, the step of stopping the drive of the catheter assembly in the first direction occurs before completion of the planned number of rotations in the first direction. The method according to claim 1.

10. A device handle for excising a substance inside a living body lumen, the device handle comprising a slide assembly comprising a drive shaft assembly configured to rotate a catheter assembly, a motor configured to apply a rotational force to the drive shaft assembly and the catheter assembly, and a processor, the processor comprising controlling a drive to apply a rotational force to the catheter assembly at a target rotational speed in a first direction, detecting an actual rotational speed of the catheter assembly in the first direction, comparing the target rotational speed and the actual rotational speed of the catheter assembly in the first direction, After the actual rotation speed reaches the value of the target rotation speed, when the actual rotation speed decreases by a planned percentage over a time frame indicating a planned length of time, before the completion of the planned number of rotations in the first direction, stopping the drive that applies the rotational force to the catheter assembly in the first direction; After the actual rotation speed reaches the value of the target rotation speed and after the completion of the drive that applies the rotational force for the planned number of rotations in the first direction, causing the catheter assembly to rotate at a number of rotations less than the planned number of rotations in the first direction in which rotation is being continued; After the causing step, stopping the rotation of the catheter assembly in the first direction; Changing the rotation direction of the catheter assembly from the first direction to the second direction; Monitoring the actual rotation speed of the catheter assembly in the first and second directions; A device handle configured to perform.

11. The device handle according to claim 10, wherein the causing step and the step of stopping the rotation of the catheter assembly are from 0.4 seconds to 0.6 seconds.

12. The processor is Updating a planned torque limit that is an upper limit of the torque acting on the planned catheter assembly in order to achieve the target rotation speed for the catheter assembly in the same direction as the rotation direction of the catheter assembly obtained during the monitoring of the actual rotation speed; The device handle according to claim 11, configured to perform.

13. The processor is After the planned number of rotations in the first direction, reducing the torque applied to the catheter assembly to zero; Allowing the catheter assembly to stop; Before rotating the catheter assembly in the second direction, stopping the rotation of the catheter assembly for a planned time; The device handle according to claim 12, configured to change the rotation direction of the catheter assembly thereby.

14. The processor is During the planned number of rotations in the second direction, controlling the rotation of the catheter assembly in the second direction; After the planned number of rotations in the second direction, reducing the torque applied to the catheter assembly to zero; Allowing the catheter assembly to stop; Before rotating the catheter assembly in the first direction, stopping the rotation of the catheter assembly for the planned time; The device handle according to claim 13, which is configured to perform the above.

15. The processor is configured to: Control the step of repeating the rotation of the catheter assembly in the first and second directions The device handle according to claim 14, which is configured to perform the above.

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