High-power plaque resection system with multiple safety limitations

Abstract

A plaque removal system includes an electrically driven mechanism adapted to rotatably actuate a plaque removal burr head; and a controller adapted to regulate the operation of the electrically driven mechanism. The controller regulates the operation of the electrically driven mechanism based on power input limits limiting how much power can be delivered to the plaque removal burr head and energy input limits limiting how much energy can be delivered to the plaque removal burr head. The controller can also regulate the operation of the electrically driven mechanism based on dynamic torque limits.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Application Serial No. 62 / 978,600, filed February 19, 2020, pursuant to 35 USC §119, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to medical devices and methods for manufacturing and using medical devices. More particularly, this invention relates to apparatus and methods for removing occlusive material from body cavities. Furthermore, this invention relates to a plaque resection device for occlusive pathways through body cavities (such as blood vessels). Background Technology

[0004] Many patients suffer from arterial and other vascular occlusions that restrict blood flow. An occlusion can be partial, reducing blood flow through the blocked portion of the vessel, or complete (e.g., chronic total occlusion), which essentially blocks blood flow through the blocked vessel. In some cases, a stent can be placed in the area of ​​the occlusion being treated. However, restenosis can occur within the stent, further obstructing the vessel and restricting blood flow. Vascular reconstruction techniques involve using various devices to create or expand an opening through the occlusion. Plaque excision is a technique in which a catheter with cutting elements is advanced through the occlusion to form or widen a path through it. Alternative plaque excision devices are still needed to penetrate the occlusion. Summary of the Invention

[0005] This invention provides designs, materials, manufacturing methods, and alternatives for use in medical devices. As an example, a plaque resection system includes an electrically driven mechanism adapted to rotatably actuate a plaque resection burr head; and a controller adapted to regulate the operation of the electrically driven mechanism based on a power input limit limiting how much power can be applied to the plaque resection burr head and an energy input limit limiting how much energy can be applied to the plaque resection burr head.

[0006] Alternatively or additionally, the electric drive mechanism may include a drive cable adapted for connection with the plaque removal rotary burr head and an electric drive motor adapted for rotating the drive cable.

[0007] Alternatively or additionally, the plaque removal system may also include a plaque removal burr head that is rotatably fixed to a drive cable.

[0008] Alternatively or additionally, the controller may also be adapted to adjust the operation of the electric drive mechanism according to a dynamic torque limit.

[0009] Alternatively or additionally, the dynamic torque limit can be varied according to the operating rate of the electric drive mechanism.

[0010] Alternatively or additionally, the controller may also be adapted to provide feedback to the operator of the plaque removal system when power input limits and / or energy input limits are exceeded during operation of the plaque removal system.

[0011] Alternatively or additionally, feedback may include a temporary reduction in the operating speed of the electric drive mechanism.

[0012] Alternatively or additionally, the controller may include a speed reference block that includes power input limits and energy input limits and is configured to output a reference signal; a control block adapted to receive the reference signal from the speed reference block and generate a control force signal; and a drive motor circuit block adapted to receive the control force signal from the control block and thus regulate the operation of the electric drive mechanism.

[0013] Alternatively or additionally, the drive motor circuit block may include a dynamic torque limit, and thus may regulate the operation of the electric drive mechanism.

[0014] Alternatively or additionally, dynamic torque limits may include current limits.

[0015] Alternatively or additionally, the control block may include a proportional-integral-derivative (PID) controller.

[0016] As another example, a plaque removal system includes an electric drive motor operably coupled to a drive cable, a plaque removal rotary burr operably coupled to the drive cable, and a control system operably coupled to the drive motor. The control system includes a speed reference block that includes power input limits and energy input limits and is configured to output a reference signal; a control block adapted to receive the reference signal from the speed reference block and generate a control force signal; and a drive motor circuit block adapted to receive the control force signal from the control block and thus regulate the operation of the electric drive mechanism.

[0017] Alternatively or additionally, the control block may also include a state estimation block that receives a position signal from the electric drive motor and outputs a motor speed signal summed with the reference signal from the speed reference block.

[0018] Alternatively or additionally, the electric drive motor may include a brushless DC electric motor.

[0019] Alternatively or additionally, the drive motor circuit block may also include a dynamic torque limit, and thus regulate the operation of the electric drive mechanism.

[0020] Alternatively or additionally, dynamic torque limits may include current limits.

[0021] Alternatively or additionally, the control block may include a proportional-integral-derivative (PID) controller.

[0022] As another example, a plaque removal system includes an electric drive motor operably coupled to a drive cable, a plaque removal rotary burr operably coupled to the drive cable, and a control system operably coupled to the drive motor. The control system includes a speed reference block that includes a power input limit and an energy input limit and is configured to output a reference signal, the reference signal being limited by at least one of the power input limit and the energy input limit; a control block adapted to receive the reference signal from the speed reference block and generate a control force signal; and a drive motor circuit block adapted to receive the control force signal from the control block and including dynamic torque limiting and adjusting the operation of the electric drive motor according to the control force signal and the dynamic torque limit.

[0023] Alternatively or additionally, the control system may also be adapted to provide feedback to the operator of the plaque removal system when the system approaches or exceeds any of the power input limit, energy input limit, or dynamic torque limit during operation of the plaque removal system.

[0024] Alternatively or additionally, feedback may include a identifiable reduction in the operating speed of the electric drive mechanism.

[0025] The above overview of some embodiments is not intended to describe every disclosed embodiment or implementation of the invention. These embodiments are illustrated more specifically by way of example in the following figures and detailed descriptions. Attached Figure Description

[0026] The invention can be more fully understood by considering the following detailed description of various embodiments of the invention taken in conjunction with the accompanying drawings, in which:

[0027] Figure 1 This is a schematic block diagram of an example plaque resection system;

[0028] Figure 2 This is a schematic block diagram of an example plaque resection system;

[0029] Figure 3 This is a schematic block diagram of an example plaque resection system;

[0030] Figure 4 This is a schematic block diagram of an example plaque resection system;

[0031] Figure 5 This is a schematic block diagram of an example plaque resection system;

[0032] Figure 6 This is a schematic block diagram of an example plaque resection system; and

[0033] Figure 7 This is a three-dimensional view of an example plaque resection system.

[0034] While the invention is adaptable to various modifications and alternatives, its specific details have been shown by way of example in the accompanying drawings and will be described in more detail. However, it should be understood that it is not intended to limit the invention to the specific embodiments described. Rather, it is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Detailed Implementation

[0035] For the purposes of the following definitions, unless otherwise specified in the claims of this specification or elsewhere, these definitions shall apply.

[0036] All numerical values ​​herein are assumed to be modified by the term "about," whether or not explicitly stated otherwise. The term "about" generally refers to a range of numbers that a person skilled in the art would consider equivalent to the referenced value (i.e., having the same function or result). In many instances, the term "about" may include numbers rounded to the nearest significant figure.

[0037] A description of a range of numbers represented by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0038] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include a plural of indicators unless otherwise expressly indicated. As used in this specification and the appended claims, the term “or” is generally used in the sense of including “and / or” unless otherwise expressly indicated.

[0039] The following detailed description should be read with reference to the accompanying drawings, in which similar elements in different drawings have the same numbering. The drawings, which are not necessarily drawn to scale, depict illustrative embodiments and are not intended to limit the scope of the invention.

[0040] Many patients have occluded arteries, other blood vessels, and / or occluded ducts or other body cavities that may restrict the flow of bodily fluids (e.g., blood, bile, etc.). The occlusion may be partial, reducing blood flow through the occluded portion of the vessel, or complete (e.g., chronic total occlusion), essentially blocking blood flow through the occluded vessel. Vascular reconstruction techniques involve using various devices to create or expand an opening through the occlusion. Plaque resection is a technique in which a catheter with a cutting element is advanced through the occlusion to create or expand a path through it. Ideally, the cutting element removes the occlusion without damaging the surrounding vessel walls and / or previously implanted stents that have restenosis. However, in some cases, the cutting element can be manipulated and / or advanced to contact the vessel walls and / or stents. Therefore, it may be desirable to utilize materials and / or design plaque resection devices that can remove the occlusion without damaging the surrounding vessel walls and / or previously implanted stents that have restenosis. Additionally, it may be desirable to use the cutting element to remove hard occlusive materials, such as calcified materials, as well as softer occlusive materials. The methods and systems disclosed herein can be designed to overcome at least some of the limitations of prior plaque removal devices while effectively removing occlusive materials. For example, some of the devices and methods disclosed herein may include a cutting element with a unique cutting surface geometry and / or design.

[0041] Figure 1 This is a schematic block diagram of an example plaque removal system 10, which includes a drive mechanism 12 adapted to rotatably actuate a plaque removal burr head 14. While the example plaque removal system 10 is described herein as an electrically actuated plaque removal system, it should be understood that in some cases, the plaque removal system 10 can be modified to be gas-actuated, where compressed air or another compressed fluid is used to drive a turbine that actuates the plaque removal burr head 14. Illustrative but non-limiting examples of gas-actuated plaque removal systems include the Jetstream™ Plaque Removal System and the ROTABLATOR™ Plaque Removal System, available from Boston Scientific.

[0042] The plaque removal system 10 includes a controller 16 adapted to regulate the operation of the drive mechanism 12. In some cases, the plaque removal system 10 may include a user interface 18 operably connected to the controller 16, enabling the controller 16 to display information about the performance of the drive mechanism 12. For example, this information may include one or more of the instantaneous speed of the drive mechanism 12, the instantaneous torque experienced by the plaque removal burr head 14, etc. In some cases, the plaque removal system 10 may not include the user interface 18. In some cases, the plaque removal burr head 14 may also be referred to as or include a cutting head or cutting member, and these terms are used interchangeably.

[0043] Figure 2 This is a schematic block diagram of an example plaque removal system 20, in which the drive mechanism 12 may include a drive motor 22 and a drive cable 24 operatively connected to the drive motor 22 and the plaque removal rotator head 14. In some cases, features of the plaque removal system 20 may be combined with features of the plaque removal system 10. In some cases, the plaque removal system 20 may also include a handle (not shown). In some cases, the drive motor 22 may be sized relative to the weight and other dimensions of the plaque removal system 20 to be able to accelerate the plaque removal rotator head to full speed in less than 3 seconds, or in some cases in less than 2 seconds. As an example, the motor 22 may be rated at least 60 watts. In a particular example, the motor 22 may be rated at approximately 80 watts. These are merely examples.

[0044] Figure 3 This is a schematic block diagram of an example plaque removal system 40, which includes a control system 42 adapted to regulate the operation of a drive mechanism 12 to rotatably actuate a plaque removal burr head 14. In some cases, features of the plaque removal system 40 may be combined with one or more of plaque removal systems 10 and 20. The control system 42 may include a reference block 32 and a proportional-derivative-integral (PID) controller 44 operatively coupled to the reference block 32. In some cases, the reference block 32 may determine a speed reference value 46 selectable between a nominal value, a negative value, and zero. Although in some cases the reference block 32 may add an offset value, in some cases the PID controller 44 may also be adapted to add an offset value to the speed reference value 46 received from the reference block 32, thereby outputting an output signal 48.

[0045] Figure 4 This is a schematic block diagram of an example plaque removal system 50, which includes a control system 52 adapted to regulate the operation of a drive motor 22 to rotatably actuate a plaque removal burr head 14. In some cases, features of the plaque removal system 50 may be combined with one or more of plaque removal systems 10, 20, or 40. The control system 52 is operatively coupled to the drive motor 22 and includes a feedback loop 54 adapted to monitor the performance of the drive motor 22 and output a control force signal 56. A drive circuit 58 is adapted to receive the control force signal 56 and regulate the operation of the drive motor 22 according to the control force signal 56.

[0046] In some cases, feedback loop 54 may include a reference block for determining a speed reference value and a proportional-integral-derivative (PID) controller operatively coupled to the reference block for receiving the speed reference value. The PID controller is adapted to determine a control force signal using the speed reference value, a proportional (P) gain value, an integral (I) gain value, and a derivative (D) gain value. In some cases, feedback loop 54 may be adapted to add an offset value to the reference signal provided to reference loop 54 to accurately maintain the speed of drive motor 22 during no-load conditions. In some cases, for example, if the plaque-removing rotator head 14 is jammed, control system 52 may also be adapted to increase the torque provided by drive motor 22 until a torque threshold is reached within a short period of time, and subsequently direct drive motor 22 to reverse at a low speed to release energy in the drive mechanism.

[0047] Figure 5 This is a schematic block diagram illustrating an illustrative control algorithm 60, which can be implemented, for example, in controller 16 ( Figure 1 and 2 ), control system 42 ( Figure 3 ) or control system 52 ( Figure 4 This can be implemented within any of the following systems: Illustrative control algorithm 60. In some cases, such as illustrative control algorithm 60, the plaque resection system, such as plaque resection systems 10, 20, 40, 50, has additional protective measures to help protect the patient. It should be understood that there are limitations on how much power and energy can be applied to the patient during rotational plaque resection. For example, applying too much power while increasing the ablation rate can also lead to vascular injury. Applying too much energy can cause an excessive increase in steady-state temperature in the patient's body near the plaque resection burr head. It should be understood that power and energy are related because power is defined as energy per unit time. Illustrative control algorithm 60 can also be considered to provide dynamic torque limits. In some cases, the amount of torque that can be applied can vary with the rotational speed. For example, additional torque may be required when initially starting to rotate the plaque resection burr head because of the need to overcome the inertia of the drive mechanism (such as drive mechanism 12). Illustrative control algorithm 60 can be considered to have multiple blocks. Speed ​​reference block 62 provides a signal indicating a speed reference. The speed reference can have a speed limit, which is stored in the speed reference block 62 and can provide a throttling effect on the output speed signal.

[0048] Energy limiting block 64 stores energy input limits that restrict how much energy can be applied to the plaque resection burr head. In some cases, the energy input limits can be considered self-resetting to account for how quickly heat can dissipate. Energy limiting block 64 can take into account system inefficiencies by estimating the energy applied to the plaque resection burr head, rather than the energy lost to the surrounding environment outside the patient.

[0049] Power limiting block 66 stores power input limits that restrict how much time-averaged power can be applied to the plaque resection burr head 14. In some cases, power limiting block 66 can reference known limits on safe average power and output a deceleration signal only when approaching or exceeding known limits. Power limiting block 66 can explain system inefficiency by estimating the power delivered to the plaque resection burr head 14, rather than the power lost to the surrounding environment outside the patient.

[0050] Speed ​​controller 68 receives inputs from each of speed reference block 62, energy limiting block 64, and power limiting block 66 and determines the appropriate speed for operating the drive mechanism. Current limiting block 70 receives a signal from speed controller 68 and includes a current input limit that restricts how much torque can be applied via the plaque removal system. Current limiting block 70 signals current controller 72, which monitors excessive current (torque) and outputs a drive signal to drive motor 74. It should be understood that drive motor 74 represents drive motor 22 shown in the previous figures.

[0051] The illustrative control algorithm 60 can be considered a feedback algorithm. As can be seen, the drive motor 74 outputs a current signal 76, which can be provided to one or more of the energy limiting block 64, power limiting block 66, current limiting block 70, and current controller 72. Similarly, the drive motor 74 outputs a speed signal 78, which is provided to one or more of the energy limiting block 64, power limiting block 66, speed controller 68, and current limiting block 70. A timer 80 provides a timer signal to the energy limiting block 64, which allows the control algorithm 60 to calculate power based on energy and vice versa.

[0052] Figure 6 This is a schematic block diagram of an example atherosclerotic plaque resection system 90. In some cases, the features of plaque resection system 90 may be combined with one or more of plaque resection systems 10, 20, 40, or 50. The example plaque resection system 90 includes a control system 92 and a drive mechanism 94. The drive mechanism 94 includes a drive motor 96, which, in some cases, as shown, may be a brushless DC electric motor. The drive mechanism 94 includes a set of gears 98 that provide the desired gear reduction relative to the output of the drive motor 96. The drive coil 100 represents a drive cable, such as drive cable 24, which is often modeled and treated as a spring coil due to the way it responds to rotation. The plaque resection atherectomy head 102 is shown coupled to the drive coil 100.

[0053] The control system 92 includes a proportional-integral-derivative (PID) controller 104, which provides a proportional (P) term 106, an integral (I) term 108, and a derivative (D) term 110 to a summing block 112. A speed reference block 114 provides a speed reference value to the summing block 116, wherein the speed reference value is summed with a speed value provided by a state estimation block 118. The state estimation block 118 receives a position signal from a drive motor 96. A motor drive block 120 receives a signal from the summing block 112 and outputs a drive signal to the drive motor 96.

[0054] It should be understood that the control system 92 can be considered suitable for providing functions related to the control algorithm 60. In some cases, for example, the speed reference block 114 stores or otherwise includes power input limits that restrict how much time-averaged power can be supplied to the plaque-removing rotator head 102 and / or drive coil 100, and energy input limits that restrict how much energy can be supplied to the plaque-removing rotator head 102 and / or drive coil 100. In some cases, a moving average value related to the thermal time constant for a particular tissue of interest can be used. In some cases, the motor drive block 120 may store or otherwise include dynamic torque limits. For example, the dynamic torque limit can be represented by current.

[0055] In some cases, if one or more of the energy input limit, power (or time-averaged power) input limit, and dynamic torque limit approach or exceed a predetermined safety limit, the control system 92 may initiate a deceleration sufficient to be noticeable to the system user. The system does not stop, but only slows down temporarily. In some cases, this may be stepped, as a first deceleration may begin when approaching one of the safety limits, and a second deceleration (greater than the first) may begin when exceeding one of the safety limits.

[0056] Figure 7 This is a perspective view of an example plaque excision system 130. In some cases, plaque excision system 130 may be considered as a representation of plaque excision systems 10, 20, 40, 50, or 90. In some cases, features of plaque excision system 130 may be combined with, for example, features of any one of plaque excision systems 10, 20, 40, 50, or 90. Plaque excision system 130 includes a handle 132. Although not shown, it should be understood that plaque excision system 130 includes a drive mechanism (such as, Figures 1 to 3 The drive mechanism 12 shown) and the controller (such as, Figures 1 to 2The controller shown is located within the handle 132 and regulates the operation of the drive mechanism. For example, the handle 132 may include a foot 134 for stabilizing the handle 132 on a flat surface during operation. A control mechanism 136 extends out of the handle 132 and can be used to control one or more features of the plaque removal system 130 during use. For example, the control mechanism 136 may be used to allow a user to change the operating speed of the drive mechanism.

[0057] The handle 132 includes a proximal region 138 and a distal region 140. As can be seen, the distal region 140 includes a hole 142 adapted to allow a drive cable (such as...) Figure 2 and Figure 4 The drive cable 24 exits the handle 132. Although not visible, the proximal region 138 can be configured to receive a guide wire 144 extending through the plaque removal system 130. It should be understood that in the distal region 140, the guide wire 144 will extend through a drive cable not shown in this figure. In some cases, the plaque removal rotary atherectomy head 14 can be attached to a simple drive mechanism (not shown) that does not include the controls discussed herein.

[0058] It should be understood that the present invention is merely illustrative in many respects. Changes may be made in details, particularly in terms of shape, size, and arrangement of steps, without departing from the scope of the invention. To the appropriate extent, this may include the use of any of the features of an example embodiment used in other embodiments. Of course, the scope of the invention is defined by the language of the appended claims.

Claims

1. A plaque removal system, comprising: An electric drive mechanism adapted to rotatably actuate a plaque-removing burr head; as well as A controller adapted to regulate the operation of the electric drive mechanism, the controller regulating the operation of the electric drive mechanism according to power input limits limiting how much power can be delivered to the plaque removal burr head and energy input limits limiting how much energy can be delivered to the plaque removal burr head. The controller is further adapted to adjust the operation of the electric drive mechanism according to a dynamic torque limit, and the dynamic torque limit varies according to the operating rate of the electric drive mechanism.

2. The plaque resection system according to claim 1, wherein the electric drive mechanism comprises: A drive cable suitable for connection with a plaque removal rotary burr head; as well as An electric drive motor suitable for rotating the drive cable.

3. The plaque removal system of claim 2, further comprising a plaque removal burr head rotatably fixed to the drive cable.

4. The plaque removal system according to any one of claims 1 to 3, wherein the controller is further adapted to provide feedback to the operator of the plaque removal system when the power input limit and / or the energy input limit is exceeded during operation of the plaque removal system.

5. The plaque removal system of claim 4, wherein the feedback includes a temporary reduction in the operating speed of the electric drive mechanism.

6. The plaque resection system of claim 1, wherein the controller comprises: A speed reference block, the speed reference block including the power input limit and the energy input limit and configured to output a reference signal; A control block adapted to receive the reference signal from the velocity reference block and generate a control force signal; as well as A drive motor circuit block adapted to receive the control force signal from the control block and thus regulate the operation of the electric drive mechanism.

7. The plaque removal system of claim 6, wherein the drive motor circuit block includes the dynamic torque limit and thus regulates the operation of the electric drive mechanism.

8. A plaque removal system comprising: An electric drive motor that can be operatively connected to a drive cable; A plaque-removing rotary burr operatively connected to the drive cable; as well as A control system operably coupled to the drive motor, the control system comprising: A speed reference block, which includes a power input limit and an energy input limit and is configured to output a reference signal; A control block, adapted to receive the reference signal from the velocity reference block and generate a control force signal; and A drive motor circuit block, adapted to receive the control force signal from the control block and thus regulate the operation of the electric drive motor. The drive motor circuit block further includes a dynamic torque limit, and thus regulates the operation of the electric drive motor, wherein the dynamic torque limit varies according to the operating rate of the electric drive motor.

9. The plaque removal system of claim 8, wherein the control block further comprises a state estimation block that receives a position signal from the electric drive motor and outputs a motor speed signal summed with the reference signal from the speed reference block.

10. The plaque removal system of claim 9, wherein the electric drive motor comprises a brushless DC electric motor.

11. A plaque removal system comprising: An electric drive motor that can be operatively connected to a drive cable; A plaque-removing rotary burr operatively connected to the drive cable; as well as A control system operably coupled to the electric drive motor, the control system comprising: A speed reference block, the speed reference block including a power input limit and an energy input limit and configured to output a reference signal, the reference signal being limited by at least one of the power input limit and the energy input limit; A control block, adapted to receive the reference signal from the velocity reference block and generate a control force signal; and A drive motor control block, the drive motor control block being adapted to receive the control force signal from the control block, and including dynamic torque limiting and adjusting the operation of the electric drive motor according to the control force signal and the dynamic torque limiting, wherein the dynamic torque limiting varies according to the operating rate of the electric drive motor.

12. The plaque removal system of claim 11, wherein the control system is further adapted to provide feedback to the operator of the plaque removal system when the system approaches or exceeds any one of the power input limit, the energy input limit, or the dynamic torque limit during operation of the plaque removal system.

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