Irrigation pump with ablative and non-ablative operating modes

Abstract

The present invention is entitled "Irrigation Pump with Ablative and Non-Ablative Operating Modes". The present invention discloses a pump comprising a cylinder, a piston and a controller. The cylinder has a first end and a second end and includes a first inlet-outlet port and a second inlet-outlet port, each of the first inlet-outlet port and the second inlet-outlet port being configured to alternately introduce fluid into the cylinder and output fluid from the cylinder. The piston is configured to move between the first end and the second end within the cylinder by alternately reversing the direction of movement of the piston so as to pump the fluid through the first inlet-outlet port and the second inlet-outlet port. The controller is configured to control the movement of the piston within the cylinder, including: (a) selecting between a first operating mode and a second operating mode; (b) in the first operating mode, controlling the piston to oscillate within a predefined interval that does not exceed a predefined distance from the first end and the second end; and (c) in the second operating mode, controlling the piston to move at a selected speed between the first end and the second end.

Description

[0001] Priority Declaration

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 786,404, filed December 29, 2018. This application is related to U.S. Patent Application No. 62 / 786,404, entitled “Dual-Action Irrigation Pump with Variable Speed to Provide Constant Fluid Flow,” Attorney Docket No. ID-1557 / BIO6047USNP1 / 2002-2047, each of which is hereby incorporated by reference as if fully set forth in this application. Technical Field

[0003] The present invention relates generally to pumps, and particularly to medical irrigation pumps. Background Art

[0004] Irrigation pumps are used in some medical procedures. Various technologies have been developed to improve the performance of medical irrigation pumps.

[0005] For example, U.S. Patent 6,913,933 describes a method for improving the dispensing rate of a fluid in a metering system using speed, the method comprising the steps of modifying the fluid flow velocity profile during a portion thereof so as to significantly increase or decrease the speed of the motor during certain portions of the metering cycle in order to improve the efficiency of the metering system.

[0006] US Patent 5,066,282 describes a disposable positive-displacement piston pump with a polycarbonate body, a piston, an inlet valve, and an outlet valve. The outlet valve is connected to an outlet chamber separated from the outlet valve by an elastomeric membrane. The elastomeric membrane surrounds a collection chamber filled with a fluid, such as air, at atmospheric pressure. The pulsation of the outlet pressure caused by the piston's stroke is attenuated by the flexure of the elastomeric membrane, thereby compressing the fluid within the collection chamber.

[0007] U.S. Patent 9,622,814 describes an ablation catheter that controls temperature and reduces the condensation of biological fluids on the catheter electrode, preventing an increase in the impedance of tissue in contact with the electrode and maximizing the potential energy transfer to the tissue, thereby increasing the size of lesions produced by ablation. The electrode includes channels positioned to allow saline to flow out of the lumen of the electrode. The fluid flow is pulsed to increase turbulence, thereby reducing areas of stagnant flow and producing the desired cooling effect. Summary of the Invention

[0008] Embodiments of the invention described herein provide a pump comprising a cylinder, a piston, and a controller. The cylinder comprises a first inlet-outlet port and a second inlet-outlet port, each of the first inlet-outlet port and the second inlet-outlet port being configured to alternately introduce a fluid into the cylinder and output the fluid from the cylinder. The piston is configured to move within the cylinder in a periodic cycle that alternately reverses the direction of movement of the piston so as to pump the fluid through the first inlet-outlet port and the second inlet-outlet port. The controller is configured to control the movement of the piston within the cylinder, including setting for the piston: (a) a first velocity during a first predefined interval before reversing the direction of movement; (b) a second velocity greater than the first velocity during a second predefined interval after reversing the direction; and (c) a baseline velocity less than the first velocity outside of the first interval and the second interval.

[0009] In some embodiments, the pump includes a piston position sensing assembly (PPSA) configured to generate a control signal indicating a position of the piston within the cylinder, the controller configured to receive the control signal and control movement of the piston based on the control signal. In other embodiments, the controller is configured to control movement of the piston between a first end and a second end of the cylinder, the PPSA including: (a) a first electrical switch configured to generate a first position signal when the piston is within a predefined distance from the first end; and (b) a second electrical switch configured to generate a second position signal when the piston is within the predefined distance from the second end, and the PPSA is configured to generate the control signal based on at least one of the first position signal and the second position signal.

[0010] In one embodiment, the controller is configured to: control a given volume of fluid to be pumped through the first inlet-outlet port and the second inlet-outlet port during a first time period including at least a first predefined interval and a second predefined interval, and is configured to: when the piston is outside the first and second intervals, control the same given volume of fluid to be pumped through the first inlet-outlet port and the second inlet-outlet port during a second time period approximately equal to the first time period. In another embodiment, at least one of the first inlet-outlet port and the second inlet-outlet port is coupled to a fluid reservoir via a first conduit and to a catheter via a second conduit for flushing tissue with fluid during a medical procedure.

[0011] According to one embodiment of the present invention, there is further provided a method for pumping fluid during medical surgery, the method comprising: in a pump including a cylinder having a first inlet-outlet port and a second inlet-outlet port, the pump alternately introducing fluid into and discharging fluid from the cylinder through each of the first inlet-outlet port and the second inlet-outlet port, moving a piston within the cylinder in a periodic cycle that alternately reverses the direction of movement of the piston to pump fluid through the first inlet-outlet port and the second inlet-outlet port. Controlling the movement of the piston within the cylinder comprises setting the piston: (a) a first velocity during a first predefined interval before reversing the direction of movement; (b) a second velocity greater than the first velocity during a second predefined interval after reversing the direction; and (c) a baseline velocity less than the first velocity outside the first and second intervals.

[0012] According to one embodiment of the present invention, there is also provided a pump comprising a cylinder, a piston and a controller. The cylinder has a first end and a second end and includes a first inlet-outlet port and a second inlet-outlet port, each of the first inlet-outlet port and the second inlet-outlet port being configured to alternately introduce a fluid into the cylinder and output the fluid from the cylinder. The piston is configured to move between the first end and the second end in the cylinder by alternately reversing the direction of movement of the piston so as to pump the fluid through the first inlet-outlet port and the second inlet-outlet port. The controller is configured to control the movement of the piston in the cylinder, including: (a) selecting between a first operating mode and a second operating mode; (b) in the first operating mode, controlling the piston to oscillate within a predefined interval that does not exceed a predefined distance from the first end and the second end; and (c) in the second operating mode, controlling the piston to move at a selected speed between the first end and the second end.

[0013] In some embodiments, the controller is configured to receive a signal indicating a position of the piston within the cylinder and control the movement of the piston based on the signal. In other embodiments, at least one of the first inlet-outlet port and the second inlet-outlet port is coupled to a fluid reservoir via a first conduit and to a catheter via a second conduit for irrigating tissue with fluid during a medical procedure. In other embodiments, the medical procedure includes tissue ablation performed by the catheter, and the controller is configured to select the second operating mode in response to receiving a control signal indicating tissue ablation.

[0014] In one embodiment, tissue ablation includes positioning a catheter at a first ablation site and a second ablation site, and in a second operating mode, the controller is configured to control the piston to: (a) move at a first selected speed when the catheter is positioned at the first ablation site; and (b) move at a different second selected speed when the catheter is positioned at the second ablation site. In another embodiment, in the second operating mode, the controller is configured to control the piston to move at a constant speed. In another embodiment, in the second operating mode, the controller is configured to control the piston to move at a variable speed.

[0015] According to one embodiment of the present invention, there is further provided a method for pumping fluid during medical surgery, the method comprising: in a pump including a cylinder having a first end and a second end and including a first inlet-outlet port and a second inlet-outlet port, the pump alternately introducing fluid into and outputting fluid from the cylinder through each of the first inlet-outlet port and the second inlet-outlet port, moving a piston within the cylinder between the first end and the second end by alternately reversing the direction of movement of the piston so as to pump the fluid through the first inlet-outlet port and the second inlet-outlet port. The movement of the piston within the cylinder comprises: (a) selecting between a first operating mode and a second operating mode; (b) in the first operating mode, controlling the piston to oscillate within a predefined interval that does not exceed a predefined distance from the first end and the second end; and (c) in the second operating mode, controlling the piston to move at a selected speed between the first end and the second end.

[0016] According to one embodiment of the present invention, there is also provided a pump comprising a cylinder, a piston and a controller. The cylinder has a first end and a second end and includes a first inlet-outlet port and a second inlet-outlet port, each of the first inlet-outlet port and the second inlet-outlet port being configured to alternately introduce a fluid into the cylinder and output the fluid from the cylinder. The piston is configured to move between the first end and the second end in the cylinder by alternately reversing the direction of movement of the piston so as to pump the fluid through the first inlet-outlet port and the second inlet-outlet port. The controller is configured to control the movement of the piston in the cylinder, including: (a) selecting between a first operating mode and a second operating mode; (b) in the first operating mode, controlling the piston to remain stationary at a predefined distance greater than zero from the first end or from the second end; and (c) in the second operating mode, controlling the piston to move at a selected speed between the first end and the second end.

[0017] The present invention will be more fully understood through the following detailed description of embodiments of the present invention in conjunction with the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1is a schematic illustration of a catheter-based ablation system according to an embodiment of the present invention;

[0019] Figure 2 is a schematic side view of an irrigation pump of an ablation system according to an embodiment of the present invention;

[0020] Figure 3A is a schematic illustration of the movement of a piston within a cylinder of a medical irrigation pump according to an embodiment of the present invention;

[0021] Figure 3B is a graph schematically showing a motion distribution of a piston in a cylinder of a medical irrigation pump according to an embodiment of the present invention;

[0022] Figure 4 is a flow chart schematically illustrating a method for flowing a constant output of flushing fluid over time according to an embodiment of the present invention;

[0023] Figure 5 is a schematic illustration of the distribution of motion of a piston in an irrigation pump used in a cardiac ablation procedure according to another embodiment of the present invention; and

[0024] Figure 6 A flow chart schematically illustrates a method for pumping irrigation fluid during a cardiac ablation procedure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] Overview

[0026] Some cardiac surgeries include tissue ablation, such as radiofrequency (RF) ablation, performed at a predefined site in the patient's heart to treat arrhythmias. An RF ablation system typically includes an ablation electrode coupled to the distal end of a catheter, and a navigation subsystem, such as a magnetic position tracking subsystem, for navigating the distal end of the catheter to the ablation site. The RF ablation system also includes an irrigation assembly for irrigating the ablated tissue with an irrigation fluid. Importantly, the tissue is irrigated before and during ablation using controlled irrigation parameters, such as flow rate, without introducing electrical noise that could interfere with the magnetic field of the magnetic position tracking subsystem.

[0027] Embodiments of the present invention described below provide methods and apparatus for improving control of irrigation parameters during an ablation procedure. In some embodiments, an irrigation assembly includes: (a) a fluid reservoir containing an irrigation fluid; (b) one or more irrigation openings located at a distal end of a catheter for irrigating a patient's cardiac tissue; and (c) a pump configured to pump the irrigation fluid between the reservoir and the irrigation openings.

[0028] In some embodiments, the pump includes a cylinder having a first end and a second end (also referred to herein as a wall) and including a first inlet-outlet port and a second inlet-outlet port, each of the first inlet-outlet and the second inlet-outlet port being coupled to a reservoir and a catheter. Each of the inlet-outlet ports is configured to alternately introduce fluid from the reservoir into the cylinder and output fluid from the cylinder to the distal end of the catheter. The pump includes a piston configured to move within the cylinder between the first wall and the second wall by alternately reversing the direction of motion of the piston so as to pump the fluid through the first inlet-outlet port and the second inlet-outlet port.

[0029] In some embodiments, the pump further comprises a controller configured to control the movement of the piston within the cylinder. The controller is configured to select between an ablative mode of operation and a non-ablative mode of operation of the pump. In the ablative mode of operation, the controller is configured to control the piston to move at a selected speed between the first wall and the second wall so as to flush the ablation site. In the non-ablative mode of operation, the controller is configured to control the piston to oscillate within a predefined interval that does not exceed a predefined distance from the first wall and the second wall of the cylinder so as to maintain a low flushing flow between tissue ablations. In some embodiments, the controller is configured to receive a signal indicating the position of the piston within the cylinder and to control the movement of the piston based on the signal. The controller is further configured to receive a control signal and to select between the non-ablative mode of operation and the ablation mode of operation based on the control signal.

[0030] In other embodiments, the piston is configured to move between the walls in a periodic cycle that alternately reverses the direction of movement of the piston at the wall to pump fluid through the first inlet-outlet port and the second inlet-outlet port. In such embodiments, the controller is configured to control the movement of the piston between the walls, including setting the piston: (a) a first velocity during a first preset interval from the wall before reversing the direction of movement; (b) a second velocity greater than the first velocity during a second preset interval from the wall after reversing the direction; and (c) a baseline velocity less than the first velocity outside the first and second preset intervals. The controller is configured to set the size of the first and second preset intervals and the corresponding first and second velocities to control the flow rate of the flushing fluid relative to a specific flow rate and, where applicable, to maintain a constant flow rate through the inlet-outlet port when the piston reverses direction.

[0031] The disclosed technology improves patient safety and the quality of ablation procedures by improving control of irrigation parameters during ablation and during ablation intervals of cardiac tissue.

[0032] In the context of the present invention and in the claims, the terms "pump" and "irrigation pump" may refer to a dual-function pump or any other suitable type of pump.

[0033] System Description

[0034] Figure 1 2 is a schematic illustration of a catheter-based ablation system 20 according to an embodiment of the present invention. System 20 includes a catheter 21 having a shaft distal end 22 that is navigated by a physician 30 through the vascular system into a heart 26 of a patient 28. In some embodiments, physician 30 inserts shaft distal end 22 through sheath 23 while manipulating distal end 22 using a manipulator 32 located at the proximal end of catheter 21.

[0035] Reference is now made to Illustration 25 . In some embodiments, system 20 includes a magnetic sensor 51 (also referred to herein as a magnetic position tracking sensor), or sensor 51 for simplicity, and an ablation catheter 50 coupled to distal end 22 .

[0036] In these embodiments, catheter 21 may be used for various procedures, such as electrophysiological (EP) mapping of heart 26 and for ablating selected tissue of heart 26. Catheter 21 includes irrigation openings for irrigating tissue of heart 26 during EP procedures, and particularly during ablation as will be described in detail below.

[0037] In some embodiments, the proximal end of catheter 21 is electrically connected to console 48 and, in parallel, to irrigation assembly 11, which provides irrigation fluid 88 (also referred to herein as fluid 88 for simplicity) for ablations and other procedures performed by system 20. In one embodiment, as will be described in detail below, console 48 includes processor 39, controller 33, and interface circuitry 38 configured to exchange signals between processor 39 and / or controller 33 and various components, modules, and assemblies of system 20.

[0038] In some embodiments, the interface circuit 38 is configured to receive electrical signals from the catheter 21 and other sensors of the system 20. The circuit 38 is further configured to send the electrical signals received from the processor 39 and the controller 33 to various components and assemblies of the system 20, such as for applying power via the catheter 21 to ablate tissue of the heart 26, and for controlling other components and assemblies of the system 20. For example, as will be described in detail below, during ablation, the catheter 21 is configured to irrigate the ablated tissue with an irrigation fluid. In one embodiment, the processor 39 is configured to control an ablation electrode (not shown) disposed at the distal end 22 to apply radiofrequency (RF) energy to tissue of the heart 26. As will be described in detail below, the controller 33 is configured to apply an irrigation fluid 88 to the tissue, for example, during an ablation procedure.

[0039] In some embodiments, system 20 includes a plurality (eg, three) magnetic field generators 36 configured to generate an alternating magnetic field. Magnetic field generators 36 are placed at known locations outside of patient 28, for example, below patient bed 29.

[0040] In some embodiments, console 48 also includes display 27 and a drive circuit (not shown) configured to drive magnetic field generator 36 .

[0041] During an EP procedure, physician 30 navigates distal end 22 of catheter 21 within heart 26. In some embodiments, magnetic sensor 51 is configured to generate a position signal indicative of the position of distal end 22 within heart 26 in response to the magnetic field radiated from magnetic field generator 36.

[0042] In some embodiments, based on the position signal received from sensor 51 , processor 39 is configured to display the position of distal end 22 in the coordinate system of system 20 , for example, on display 27 .

[0043] This position sensing method is used, for example, in the CARTO manufactured by Biosense Webster Inc. (Irvine, Calif.). TM The position sensing method is implemented in a system and is described in detail in U.S. Patents 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, and 6,332,089, in PCT Patent Publication WO 96 / 05768, and in U.S. Patent Application Publications 2002 / 0065455 Al, 2003 / 0120150 Al, and 2004 / 0068178 Al.

[0044] In some embodiments, the irrigation assembly 11 includes a pump 44, in this example an irrigation pump, the structure and function of which are described below. Figure 2 、 Figure 3A and Figure 5 The irrigation assembly 11 also includes a fluid reservoir 55 that is configured to contain an irrigation fluid 88 , such as a saline solution or any other type of fluid suitable for irrigating the tissue of the heart 26 .

[0045] In some embodiments, flushing assembly 11 includes tubes 52A and 52B configured to flow fluid 88 between reservoir 55 and pump 44. Flushing assembly 11 also includes tubes 49A and 49B configured to flow fluid 88 between pump 44 and catheter 21.

[0046] In some embodiments, the controller 33 is configured to receive electrical signals indicative of control parameters of the irrigation assembly 11 via the cable 53. Based on these control parameters, the controller 33 is configured to control the flow of the fluid 88 to the distal end 22 and within the irrigation assembly 11. Embodiments of methods and apparatus for controlling the flow of the fluid 88 are described below. Figures 2 to 6 Described in detail in.

[0047] The processor 39 and / or controller 33 typically comprise a general-purpose processor or controller that is programmed in software to perform the functions described herein. The software may be downloaded to the processor 39 and controller 33 in electronic form, for example, over a network, or alternatively or in addition, the software may be provided and / or stored on a non-transitory tangible medium, such as on magnetic, optical, or electronic memory.

[0048] Controlling the flow of fluid in a pump

[0049] Figure 2 is a schematic side view of a pump 44 according to an embodiment of the present invention. In some embodiments, the pump 44 includes a cylinder 111 configured to contain an irrigation fluid 88 for irrigating the tissue of the heart 26. The pump 44 also includes a piston 99 configured to move within the cylinder 111 (e.g., along the axis 105) using a stepper motor (not shown) or any suitable type of motion device (such as, but not limited to, any other type of suitable motor or actuator). In the example of the pump 44, the cylinder 111 and the piston 99 each have a circular cross-section. The pump 44 can be a modified version of the pump 10 shown and described in U.S. Provisional Patent Application No. 62 / 786,404, filed on December 29, 2018.

[0050] In the context of this patent application and claims, the term "cylinder" as a term of art refers to any suitable container in which the piston 99 or any other suitable type of piston moves. In this context, the cylinder and piston can have any suitable cross-section, not necessarily circular.

[0051] In some embodiments, cylinder 111 has a left wall 66 and a right wall 77, also referred to herein for simplicity as the "first end and second end" of cylinder 111 or "wall 66 and wall 77," respectively. In some embodiments, cylinder 111 includes an inlet-outlet port 112 and an inlet-outlet port 114 formed in wall 66 and wall 77, respectively.

[0052] In the context of this patent application and claims, the respective terms “inlet-outlet port 112 and inlet-outlet port 114,” “port 112 and port 114,” and “first inlet-outlet port and second inlet-outlet port” are used interchangeably and refer to openings in cylinder 111. In one embodiment, each of the first inlet-outlet port and the second inlet-outlet port is configured to alternately introduce fluid 88 into and output fluid 88 from cylinder 111.

[0053] In some embodiments, each of the inlet-outlet port 112 and the inlet-outlet port 114 may have two openings. Figure 2 In the side view, the two openings are in the same plane (the plane is perpendicular to Figure 2 (plane), so the second opening is hidden behind the first opening, and the two openings are shown as a single opening. In some embodiments, the first opening of inlet-outlet port 112 is coupled to tube 52A via valve 122A, and the second opening of inlet-outlet port 112 is coupled to tube 49A via valve 122B. Similarly, the first opening of inlet-outlet port 114 is coupled to tube 52B via valve 124A, and the second opening of inlet-outlet port 114 is coupled to tube 49B via valve 124B.

[0054] In some embodiments, tubes 49A and 49B are coupled to a common tube 49C, which is also coupled to catheter 21. Similarly, tubes 52A and 52B are coupled to a common tube 52C, which is also coupled to reservoir 55.

[0055] In some embodiments, in a pump (such as pump 44), each of inlet-outlet port 112 and inlet-outlet port 114 exchanges fluid 88 with two entities (in this example, reservoir 55 and conduit 21). Each of valves 122A, 122B, 124A, and 124B is configured to allow fluid 88 to flow in one direction and prevent fluid 88 from flowing in the opposite direction (e.g., a one-way valve), and is also configured to reverse the direction of flow. Controller 33 is configured to control the flow direction of fluid 88 by switching the direction of movement of piston 99. In such embodiments, the movement of piston 99 determines the flow direction in the above-mentioned valves. For example, when piston 99 moves toward wall 77, valve 122A introduces fluid 88 from reservoir 55 into cylinder 111 via tube 52C and tube 52A, while valve 124B outputs fluid 88 from cylinder 111 into conduit 21 via tube 49B and tube 49C. In an alternative embodiment, controller 33 is configured to control the flow direction of valves 122A, 122B, 124A, and 124B via electrical cable 53. In this embodiment, valves 122a, 122b, 124a, and 124b may be in the form of electrically powered solenoid valves.

[0056] In some embodiments, piston 99 moves within cylinder 111 in a periodic cycle that alternately reverses the direction of movement of piston 99 to pump fluid 88 through inlet-outlet port 112 and inlet-outlet port 114. For example, when piston 99 moves in a reversed direction toward left wall 66, valve 122B enables outflow of fluid 88 disposed between piston 99 and wall 66 to flow from pump 44 into catheter 21 via port 112 and tubes 49A and 49C for flushing the tissue of heart 26. Simultaneously, valve 124A enables fluid 88 to flow from reservoir 55 into cylinder 111 via tubes 52C and 52B and through port 114.

[0057] In some embodiments, the pump 44 includes a piston position sensing assembly (PPSA) 54 that is configured to sense the position of the piston 99 along the shaft 105 and to generate a signal indicative of the position of the piston 99 within the cylinder 111. In some embodiments, the PPSA 54 includes any suitable type of position sensor. Figure 2 In the example shown, PPSA 54 includes electrical switches 56A and 56B positioned proximate to wall 66 and wall 77, respectively. In some embodiments, electrical switches 56A and 56B are electrically coupled to controller 57, which is electrically connected to controller 33. In other embodiments, electrical switches 56A and 56B may be directly electrically coupled to controller 33.

[0058] In some embodiments, PPSA 54 can be calibrated during assembly of system 20 and / or at least prior to the first medical procedure requiring irrigation. During calibration, controller 33 controls the movement of piston 99 along axis 105 between walls 66 and 77. When piston 99 reaches wall 66, electrical switch 56A sends a signal to controller 57 indicating the position of piston 99. Controller 33 then controls the movement of piston 99 within cylinder 111 toward wall 77 and counts the number of steps of the stepper motor. When piston 99 reaches wall 77, electrical switch 56B sends a signal to controller 57 indicating the position of piston 99, and controller 57 concludes calibration.

[0059] In some embodiments, based on the calibration, counting of the number of steps and their direction, the controller 57 may send the aforementioned signal to the controller 33 indicating the position of the piston 99 within the cylinder 111 .

[0060] In alternative embodiments, piston 99 may not be in physical contact with walls 66 and 77, but may be in proximity to these walls, such as within a predefined distance of a few millimeters or within any other suitable distance.

[0061] In other embodiments, the PPSA 54 may have any other suitable configuration using any suitable technique for generating a signal indicative of the current position of the piston 99 within the cylinder 111 .

[0062] This particular configuration of the irrigation assembly 11 and system 20 is shown by way of example in order to illustrate certain problems solved by embodiments of the present invention and to demonstrate the application of these embodiments in enhancing the performance of such systems. However, embodiments of the present invention are by no means limited to this particular class of exemplary systems, and the principles described herein may be similarly applied to other classes of medical ablation and / or irrigation systems.

[0063] Figure 3A is a schematic illustration of the movement of piston 99 within cylinder 111 during flushing according to an embodiment of the present invention. In some embodiments, controller 33 is configured to control the movement of piston 99 in a periodic cycle that alternately reverses the direction of movement of piston 99 using motion profile 80 to pump fluid 88 at a constant rate.

[0064] Note that when piston 99 reaches either wall 66 or wall 77, controller 33 must change direction of motion, so piston 99 remains stationary (i.e., remains stationary) at walls 66 and 77 before changing direction. In other words, when piston 99 is positioned at walls 66 and 77, its velocity is zero, and therefore, fluid 88 is not pumped at these locations. In one embodiment, controller 33 is configured to use the following in Figure 3BThe technique described in maintains a constant flow rate of fluid 88.

[0065] In other embodiments, piston 99 does not make physical contact with at least one of wall 66 and wall 77. In such embodiments, controller 33 may change the direction of movement of piston 99 before it reaches either wall 66 or wall 77. For example, controller 33 may change the direction of movement of piston 99 when piston 99 is within a predetermined interval of a few millimeters of wall 66, or within any other suitable predetermined interval.

[0066] Use a pump to control the constant rate of fluid pumping

[0067] Figure 3B 1 is a schematic diagram 100 schematically illustrating the distribution of movement of the piston 99 within the cylinder 111 during flushing according to an embodiment of the present invention. In some embodiments, the schematic diagram 100 is based on the above Figure 3A The motion profile 80 shown in FIG. 1 shows the speed of motion of the piston 99 as a function of the position of the piston 99. For conceptual clarity, the diagram 100 is divided into a plurality of segments corresponding to the position of the piston 99 within the cylinder 111.

[0068] In some embodiments, when the piston 99 is Figure 3A When shown positioned at segment 164 between walls 66 and 77, controller 33 is configured to move piston 99 toward wall 77 at a baseline velocity, referred to as "BLS" on the velocity axis of motion of diagram 100. Note that BLS is dependent upon the dimensions of cylinder 111, which defines the volume of fluid 88, and is also based on predefined parameters of the ablation procedure, such as, but not limited to, ablation power and a target temperature of the ablated tissue.

[0069] As described above, piston 99 moves toward wall 77, and PPSA 54 sends a signal indicating the corresponding position of piston 99 within cylinder 111. Note that controller 33 reverses the direction of movement of piston 99 when it reaches or approaches walls 66 and 77.

[0070] In some embodiments, when the piston 99 is at a predefined spacing 176 (e.g., approximately 1 mm or any other suitable spacing) from the wall 77, the controller 33 receives a signal from the PPSA 54 indicating the corresponding position of the piston, and in response, the controller 33 sets a first speed S1 to the piston that is greater than BLS.

[0071] In the context of the present disclosure and claims, the term "about" or "approximately" for any numerical value or range indicates a suitable dimensional tolerance that allows a part or collection of components to function for the intended purpose described herein. More specifically, "about" or "approximately" can refer to a range of ±20% of the value of the recited value, for example, "about 90%" can refer to a range of values from 71% to 99%.

[0072] In some embodiments, when the piston 99 is close to the wall 77 (e.g., approximately 2 mm), the controller may reduce the speed of the piston 99 to a complete stop, as shown by the speed "S0" at point 177, which corresponds to the piston 99 being in physical contact with the wall 77 or within a predetermined interval from the wall 77.

[0073] In some embodiments, in response to receiving a signal from PPSA 54 indicating that piston 99 is in physical contact with wall 77 (or within a predetermined spacing from the wall), controller 33 is configured to reverse the direction of movement of piston 99 toward wall 66 and set piston 99 to a speed S2 of movement shown at predefined spacing 178 in diagram 100. Note that spacing 176 and spacing 178 may overlap in position (e.g., both are proximate to wall 77) but cause the piston to move in different directions and, therefore, are shown as different spacings in diagram 100.

[0074] In some embodiments, controller 33 is configured to compensate for the decrease in flow of pump 44 caused by a complete stop at wall 77 (corresponding to point 177) by setting speed S1 to piston 99 at interval 176 before reversing the direction of motion and setting speed S2 to the piston at interval 178 after reversing the direction of motion. As described above, speed S2 is greater than speed S1 and both speeds S1 and S2 are greater than BLS, and this sequence causes the flow of pump 44 to increase to compensate for the decrease in flow when the piston is located near wall 77 and in contact with the wall.

[0075] In such an embodiment, at a first time interval, referred to herein as segment 174 of schematic 100, pump 44 delivers a volume of fluid 88 (e.g., to conduit 21) at a given time that is similar to the volume that would be delivered by pump 44 if piston 99 were moving at the BLS speed. In other words, controller 33 also sets pump 44 to maintain a constant flow of fluid 88 when the direction of motion is reversed at walls 66 and 77.

[0076] In some embodiments, the controller 33 is configured to set the speeds S1 and S2 and the physical dimensions of the intervals 176 and 178 using any suitable arrangement for achieving the aforementioned constant flow of fluid 88 through the pump 44. In such embodiments, the controller 33 may set the intervals 176 and 178 to have similar or different physical travels and / or durations relative to each other. For example, the controller 33 may set the speed S2 to be substantially greater than the speed S1 and the interval 178 to be shorter than the interval 176, or may use any other suitable combination of speeds and interval durations for optimizing the flow rate of the pump 44.

[0077] In some embodiments, in response to receiving a signal from PPSA 54 indicating that the piston has ended its travel in gap 178, controller 33 controls movement of piston 99 toward wall 66 at a predefined gap 179 located outside of gaps 176 and 178 and sets the speed of piston 99 to BLS.

[0078] In some embodiments, in response to receiving a signal from PPSA 54 indicating that the piston has ended travel in interval 179 , controller 33 sets the speed of piston 99 to S1 at a predefined interval 165 before reversing the direction of motion at wall 66 .

[0079] Using the same sequence as described above for point 177, in response to receiving a signal from PPSA 54 indicating that the piston has ended its travel in interval 165, controller 33 reduces the speed of movement of piston 99 to a complete stop at point 166, which corresponds to piston 99 being in physical contact with wall 66 or within a predetermined interval from the wall.

[0080] In some embodiments, in response to receiving a signal from PPSA 54 indicating that piston 99 is in physical contact with wall 66 (or within a predetermined interval from the wall), controller 33 is configured to reverse the direction of movement of piston 99 toward wall 77 and to provide piston 99 with a speed of motion S2 at a predefined interval 167 after reversing the direction of movement.

[0081] In some embodiments, in response to receiving a signal from PPSA 54 indicating that piston 99 has ended its travel along gap 167 , controller 33 controls movement of piston 99 toward wall 77 at gap 164 , which is located outside of gaps 165 and 167 , and sets the speed of piston 99 to BLS.

[0082] In some embodiments, at the second time interval of segment 169 of schematic 100, referred to herein, the pump 44 flows a volume of fluid 88 (e.g., to conduit 21) at a given time that is similar to the volume flowed by the pump 44 when the piston 99 moves at the BLS speed, as described above for segment 174.

[0083] In some embodiments, controller 33 is configured to move piston 99 within cylinder 111 in a periodic cycle that alternately reverses the direction of movement of piston 99 to pump fluid 88 through inlet-outlet port 112 and inlet-outlet port 114 in response to a signal received from processor 39. When physician 30 decides to stop irrigating the tissue of heart 26, or when system 20 automatically stops irrigation, processor 39 sends a signal to controller 33 to stop moving piston 99 within cylinder 111, and irrigation stops.

[0084] Figure 4 Flowchart 200 schematically illustrates a method for delivering a constant output of irrigation fluid 88 through pump 44 according to an embodiment of the present invention. The method begins at piston movement step 202, where controller 33 receives a control signal from processor 39 for irrigating tissue of heart 26 with irrigation fluid 88 and controls piston 99 to move in a selected direction at a baseline speed (BLS), as described above. Figure 3B The interval 164 is described.

[0085] At position signal receiving step 204, controller 33 receives a signal from PPSA 54 indicating the corresponding position of piston 99 moving toward wall 77, as described above. Figure 3B At the first speed setting step 206, in response to receiving a signal from the PPSA 54 indicating that the piston has ended its travel in the gap 164, the controller 33 controls the piston 99 to move along the gap 165 toward the wall 77 at a speed S1. Subsequently, when approaching the wall 77, the controller 33 reduces the speed of the piston 99 to a complete stop when it reaches the wall 77, as described above in Figure 3B As described in .

[0086] At the second speed setting step 208, in response to receiving a signal from the PPSA 54 indicating that the piston is in contact with the wall 77 or is close to the wall (e.g., within the predetermined distance from the wall), the controller 33 reverses the direction of movement and controls the piston 99 to move toward the wall 66 along the distance 167 at a speed S2, as described above. Figure 3B At the third speed setting step 210, in response to receiving a signal from the PPSA 54 indicating that the piston has ended its travel in the interval 167, the controller 33 sets the movement of the piston 99 toward the wall 66 along the interval 179 at BLS, as described above in Figure 3BIn some embodiments, step 210 typically ends when controller 33 receives a signal from PPSA 54 indicating that the piston has ended travel in interval 179, and the method loops back to step 206 and continues until controller 33 receives a control signal from processor 39 to stop irrigating the tissue of heart 26.

[0087] Control of irrigation pumps between and during ablations

[0088] Figure 5 Schematic illustration of the motion profile of a piston 99 in a pump 44 for use in a cardiac ablation procedure according to another embodiment of the present invention. In some embodiments, the controller 33 is configured to operate the pump 44 in two operating modes, referred to herein as a first operating mode and a second operating mode.

[0089] In some embodiments, the first operating mode is performed at a predefined interval 311 that does not exceed a predefined distance, such as, but not limited to, approximately 0.5 cm from wall 66 or wall 77. In the first operating mode, controller 33 is configured to operate pump 44 in a non-ablative state 333, such that physician 30 operates distal tip 22 in heart 26 but is not ablating tissue of heart 26. Note that in the ablation state, which will be described in detail below, it is important to pump fluid 88 without changing the direction of motion of piston 99, and therefore, controller 33 uses non-ablative state 333 to position piston 99 proximate to one of wall 66 and wall 77 and, if desired, perform specific irrigation within heart 26, as described in detail below.

[0090] In some embodiments, in the non-ablation state 333, the controller 33 is configured to control the piston 99 to oscillate within the predefined interval 311. In such embodiments, the piston 99 moves within the interval 311 in a periodic cycle that alternately reverses the direction of movement of the piston 99 so as to pump the fluid 88 through the inlet-outlet port 112 and the inlet-outlet port 114. It is noted that by oscillating the piston 99 within the interval 311, the irrigation assembly 11 irrigates the tissue of the heart 26 with a pulse of fluid 88 that is defined by the width of the interval 311 and the speed of movement of the piston 99, or in other words, the pulse is defined by the cycle time of one oscillation (e.g., starting and ending at the wall 66).

[0091] In other embodiments, the controller 33 may, for example, Figure 3B and Figure 4 The techniques described in are used to control the movement of piston 99 within gap 311 to pump a constant flow of fluid 88.

[0092] In alternative embodiments, controller 33 may use any other suitable motion profile to control the motion of piston 99. For example, in response to a command signal from processor 39, controller 33 may control the velocity of piston 99 over time to increase or decrease the amount of fluid 88 pumped by pump 44. This exemplary motion profile may be defined manually by physician 30 or automatically by processor 39 in response to receiving one or more signals related to the medical procedure.

[0093] In other embodiments, controller 33 may control pump 44 to remain stationary at any suitable predefined distance from wall 66 and / or wall 77 (generally within spacing 311 ).

[0094] In some embodiments, controller 33 is configured to select between operating pump 44 in an ablative state 300 (typically during tissue ablation) and in a non-ablative state 333 (typically between ablations). In some cases, controller 33 receives a command signal from processor 39 for switching between state 300 and state 333.

[0095] In some embodiments, in the ablation state 300 corresponding to the aforementioned second mode of operation, the controller 33 is configured to control the piston 99 to move between the wall 66 and the wall 77 at a selected speed. The selected speed can be constant during ablation of all ablation sites in the heart 26, or can vary between specific ablation sites in the heart 26 in response to different ablation conditions (e.g., time, temperature, and RF energy applied to the tissue). In addition, during ablation at a specific ablation site, the controller 33 can change the speed of movement of the piston 99, for example, in response to changes in the temperature measured at the ablation site. In other words, the controller 33 is configured to control the piston 99 to move at a variable speed during tissue ablation.

[0096] In some embodiments, when the piston is positioned within the predefined interval 322 (which is not within and does not overlap the interval 311), the controller 33 operates the pump 44 in the ablation state 300. The speed of movement of the shaft 105 within the predefined distance interval 322 can be different from the speed of movement of the shaft 105 within the predefined distance interval 322. Figure 3B The movement speed of the shaft 105 is consistent.

[0097] In other embodiments, the controller 33 may select to switch from the first operating mode (i.e., the non-ablative state 333) to the second operating mode (i.e., the ablation state 300) while the piston 99 is still located within the gap 311. Similarly, the controller 33 may select to switch from the second operating mode back to the first operating mode after the piston 99 has been located within the gap 311 at the other end of the cylinder 111.

[0098] In one embodiment, processor 39 may send a first command signal to controller 33 to switch to ablative state 300 when the piston is within gap 311, proximate wall 66, and may send a second command signal to switch back to non-ablative state 333 when the piston is within gap 311, proximate wall 77. Figure 5 In the exemplary embodiment shown, the arrow representing ablation state 300 begins within interval 311 located proximate wall 66 and terminates within interval 311 located proximate wall 77. In such embodiments, controller 33 is configured to operate pump 44 in ablation state 300 until piston 99 makes physical contact with wall 77.

[0099] In other embodiments, controller 33 is configured to select between the first operating mode and the second operating mode independently of processor 39. For example, in response to receiving a position signal from PPSA 54 indicating that piston 99 is located within gap 311, controller 33 may switch from the ablation state 300 of the second operating mode to the non-ablation state 333 of the first operating mode.

[0100] Additionally or alternatively, the controller 33 is configured to select between the first operating mode and the second operating mode using other sequences, for example, after flushing the ablation site in the heart 26 with a predefined volume of fluid 88, or based on any other suitable signal, or by using any suitable sequence programmed in the controller 33.

[0101] Figure 5 This particular sequence is shown by way of example to illustrate certain issues, such as having sufficient fluid 88 for irrigating tissue using a pump during ablation. As described above, embodiments of the present invention address these issues, and these embodiments also demonstrate their application in enhancing the performance of pumps operating in cardiac ablation systems. However, embodiments of the present invention are by no means limited to these specific classes of exemplary pumps and systems, and the principles described herein may be similarly applied to other classes of pumps and medical ablation systems.

[0102] Figure 6 A flowchart 400 schematically illustrates a method for pumping irrigation fluid 88 during a cardiac ablation procedure performed by irrigation assembly 11 according to another embodiment of the present invention. The method begins at a first piston movement step 402, in which controller 33 controls piston 99 to move at a selected speed in the direction indicated by the arrow in ablation state 300. Note that at step 402, controller 33 operates pump 44 in the second operating mode during ablation of tissue in heart 26 and controls piston 99 to move toward wall 77.

[0103] At position signal receiving step 404, controller 33 receives a signal from PPSA 54 indicating the corresponding position of piston 99 moving toward wall 77, as described above. Figure 3B At the piston oscillation step 406, in response to receiving a position signal indicating that the piston 99 is located near the wall 77 within the gap 311, the controller 33 controls the piston 99 to oscillate within the gap 311 using the non-ablation state 333, as described above in Figure 5 As described in .

[0104] At a control signal receiving step 408, controller 33 receives (e.g., from processor 33) a control signal instructing to initiate tissue ablation in heart 26. Note that the first flush depicted in step 402 is performed when distal tip 22 is positioned at a first ablation site, and the control signal of step 408 is received when distal tip 22 is generally positioned at a second, different ablation site.

[0105] At a second piston movement step 410, in response to receiving the control signal, controller 33 switches the operating mode of pump 44 and controls piston 99 to move toward wall 66 to flush tissue with fluid 88 during ablation at the second ablation site. In some embodiments, controller 33 controls piston 99 to move at the speed selected at step 402 above, but in the opposite direction, i.e., toward wall 66. In other embodiments, the ablation parameters at the second ablation site may be different from the ablation parameters at the first ablation site, and thus, the speed selected at step 410 may be different from the speed selected at step 402 above, so as to perform appropriate flushing with fluid 88 during ablation at the second ablation site.

[0106] In some embodiments, after ending step 401 , the method loops back to step 404 and continues until the physician 30 has ablated the last ablation site.

[0107] In some embodiments, pump 44 is Figures 1-6 As shown and appearing in the claims section, the term "pump" may include a dual-function pump or any other suitable type of pump.

[0108] Although the embodiments described herein primarily address tissue irrigation in cardiac ablation procedures, the methods and systems described herein may also be used in other applications, such as in other cardiac applications, in any type of ablation procedure applied to tissue of any other organ.

[0109] It should therefore be understood that the embodiments described above are cited by way of example, and that the present invention is not limited to what is specifically shown and described above. On the contrary, the scope of the present invention includes combinations and subcombinations of the various features described above, as well as variations and modifications thereof, which will occur to those skilled in the art upon reading the above description and which are not disclosed in the prior art. The documents incorporated by reference into this patent application are considered an integral part of this application, except that if any term defined in these incorporated documents conflicts with a definition explicitly or implicitly given in this specification, only the definition in this specification shall be considered.

Claims

1. A pump comprising: a cylinder having a first end and a second end and including a first inlet-outlet port and a second inlet-outlet port, wherein each of the first inlet-outlet port and the second inlet-outlet port is configured to alternately introduce a fluid into the cylinder and output the fluid from the cylinder; a piston configured to move within the cylinder between the first end and the second end by alternately reversing the direction of movement of the piston to pump the fluid through the first inlet-outlet port and the second inlet-outlet port; as well as a controller configured to control the movement of the piston within the cylinder in one or more of a first operating mode and a second operating mode such that: (a) in the first operating mode, the piston oscillates within a predefined interval that does not exceed a predefined distance from the first end or from the second end; or (b) in the second operating mode, the piston moves between the first end and the second end at a selected speed, Wherein the controller is configured to select the second operating mode in response to receiving a control signal indicative of tissue ablation.

2. The pump according to claim 1, wherein The controller is configured to receive a signal indicative of a position of the piston within the cylinder and to control movement of the piston based on the signal.

3. The pump according to claim 1, wherein At least one of the first inlet-outlet port and the second inlet-outlet port is coupled to a fluid reservoir via a first conduit and to a catheter via a second conduit for flushing tissue with the fluid during a medical procedure.

4. The pump according to claim 3, wherein The tissue ablation includes positioning the catheter at a first ablation site and a second ablation site, and wherein, in the second operating mode, the controller is configured to control the piston to: (a) move at a first selected speed when the catheter is positioned at the first ablation site; and (b) move at a different second selected speed when the catheter is positioned at the second ablation site.

5. The pump according to claim 1, wherein In the second operating mode, the controller is configured to control the piston to move at a constant speed.

6. The pump according to claim 1, wherein In the second operating mode, the controller is configured to control the piston to move at a variable speed.

7. A pump comprising: a cylinder having a first end and a second end and including a first inlet-outlet port and a second inlet-outlet port, wherein each of the first inlet-outlet port and the second inlet-outlet port is configured to alternately introduce a fluid into the cylinder and output the fluid from the cylinder; a piston configured to move within the cylinder between the first end and the second end by alternately reversing the direction of movement of the piston to pump the fluid through the first inlet-outlet port and the second inlet-outlet port; as well as a controller configured to control the movement of the piston within the cylinder in one or more of a first operating mode and a second operating mode such that: (a) in the first operating mode, the piston remains stationary at a predefined distance greater than zero from the first end or from the second end; or (b) in the second operating mode, the piston moves between the first end and the second end at a selected speed, Wherein the controller is configured to select the second operating mode in response to receiving a control signal indicative of tissue ablation.

8. The pump according to claim 7, wherein The controller is configured to receive a signal indicative of a position of the piston within the cylinder and to control movement of the piston based on the signal.

9. The pump according to claim 7, wherein At least one of the first inlet-outlet port and the second inlet-outlet port is coupled to a fluid reservoir via a first conduit and to a catheter via a second conduit for flushing tissue with the fluid during a medical procedure.

10. The pump according to claim 9, wherein The tissue ablation includes positioning the catheter at a first ablation site and a second ablation site, and wherein, in the second operating mode, the controller is configured to control the piston to: (a) move at a first selected speed when the catheter is positioned at the first ablation site; and (b) move at a different second selected speed when the catheter is positioned at the second ablation site.

11. The pump according to claim 7, wherein In the second operating mode, the controller is configured to control the piston to move at a constant speed.

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