Driver systems and methods for circulatory assist devices

Abstract

Systems and methods for driving a circulatory assist device, such as a device having a volume displacement member with an expandable chamber (e.g., balloon), are disclosed herein. Generally, in some variations, a driver system can include a chamber with an operating chamber volume fillable with an inflation fluid, a driving mechanism configured to cyclically decrease and increase the operating chamber volume at a driving frequency, a fluid flow line configured to convey inflation fluid between the operating chamber volume and an expandable chamber of a circulatory assist device, and a controller. The controller can be configured to control conveyance of inflation fluid to cyclically move the volume displacement member at the driving frequency between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume, thereby regulating a pumping throughput of the circulatory assist device.

Description

Attorney Docket No.: CDB.016WODRIVER SYSTEMS AND METHODS FOR CIRCULATORY ASSIST DEVICESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of priority to U.S. Provisional Patent Application 63 / 725,824, filed November 27, 2024, which is incorporated by reference herein in its entirety.TECHNICAL FIELD

[0002] The present technology relates to driver systems and methods for actuating circulatory assist devices.BACKGROUND

[0003] For patients suffering from cardiogenic shock, or those undergoing high-risk percutaneous coronary interventions (PCI), a patient's heart function may be compromised such that the use of circulatory assist devices may be required to maintain adequate blood flows through the circulatory system.

[0004] One common type of circulatory assist device is an intra-aortic balloon pump (IABP). IABPS are catheters having an inflatable balloon which can be placed in the descending aorta and cyclically inflated to displace the blood. To provide sufficient blood flow for circulatory assistance, the balloon in IABPs and other balloon pump-based circulatory assist devices must be cyclically inflated and deflated with an inflation fluid in a highly-controlled manner. However, proper operation of balloon pump-based circulatory assist devices can present various challenges. For example, it can be difficult to inflate and deflate the balloon pump with high precision of inflation pressures, yet underinflation or overinflation can lead to ineffective and / or inefficient pumping in the circulatory assist device. As another example, many off-the-shelf pump systems not only have inadequate pumping specifications for circulatory assist devices, but also tend to have high electrical power requirements resulting in a 3-phase electrical connection (which is more complex than a single phase electrical connection) and have significant Acoustic Energy levels (dB) and in pitch (Hz), making them inappropriate for use in a clinical setting. Thus, there is a need for new and improved systems and methods for driving circulatory assist devices.Attorney Docket No.: CDB.016WOSUMMARY

[0005] The subject technology is illustrated, for example, according to various aspects described below, including with reference to FIGS. 1-26. Various examples of aspects of the subject technology are described as numbered clauses (1, 2, 3, etc.) for convenience. These are provided as examples and do not limit the subject technology.1. A driver system for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device comprises a volume displacement member with an expandable chamber and the volume displacement member is movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the driver system comprises: a driver chamber with an operating chamber volume fillable with an inflation fluid; a driving mechanism configured to cyclically decrease and increase the operating chamber volume at a driving frequency; a fluid flow line configured to convey inflation fluid between the operating chamber volume and the expandable chamber; and a controller configured to control the driving mechanism such that inflation fluid is conveyed between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase at the driving frequency, thereby regulating a pumping throughput of the circulatory assist device; and wherein the controller is configured to maintain the driving frequency at 5 Hz or greater.2. The system of clause 1, wherein the controller is configured to control the driving mechanism such that a predetermined volume of inflation fluid is conveyed into and out of the volume displacement member at the driving frequency.3. The system of clause 1 or 2, wherein the controller is configured to automatically regulate at least one of the driving frequency, a stroke length, or a driving speed of the driving mechanism based at least in part on a signal received from at least one sensor.Attorney Docket No.: CDB.016WO4. The system of clause 3, wherein the at least one sensor senses at least one of an inflation fluid pressure, inflation fluid temperature, blood pressure in the heart or blood vessel, or blood flow in the patient’s heart or blood vessel.5. The system of any one of clauses 1-4, wherein the inflation fluid is conveyed to the expandable chamber at a pressure of between about 100 mmHg and about 1500 mmHg.6. The system of any one of clauses 1-5, wherein the inflation fluid is withdrawn from the expandable chamber at a negative pressure of between about -200 mmHg and about -700 mmHg.7. The system of any one of clauses 1-6, wherein at least about 1.5 ml of inflation fluid is conveyed to and from the expandable chamber during each cycle.8. The system of any one of clauses 1-7, wherein the driver chamber comprises a housing and a movable divider, wherein the operating chamber volume is on a first side of the movable divider.9. The system of clause 8, further comprising a seal around a periphery of the divider providing a fluid seal between the movable divider and the housing.10. The system of clause 9, wherein the seal is coupled to the movable divider so as to move with the movable divider relative to the housing.11. The system of any one of clauses 8-10, wherein the driver chamber further comprises one or more vents on a second side of the movable divider opposite the first side.12. The system of any one of clauses 8-11, wherein the movable divider comprises a membrane having a fully pressurizing configuration and a fully depressurizing configuration.Attorney Docket No.: CDB.016WO13. The system of any one of clauses 8-12, wherein the movable divider comprises a plunger coupled to a driving rod, wherein the driving rod is operably coupled to the driving mechanism.14. The system of clause 12 or 13, wherein the fully pressurizing configuration and the fully depressurizing configuration correspond to respective end points of a stroke length of the driving mechanism.15. The system of any one of clauses 12-14, wherein the membrane has a nonlinear profile in the fully pressurizing configuration.16. The system of any one of clauses 12-15, further comprising a driving rod coupled to the membrane with one or more coupling discs.17. The system of any one of clauses 12-16, wherein the membrane comprises an inner edge coupled to a periphery of the plunger.18. The system of any one of clauses 12-17, wherein the membrane comprises an outer edge coupled to an internal surface of the housing.19. The system of clause 18, wherein the membrane has a fully pressurizing configuration and a fully depressurizing configuration corresponding to end points of a stroke length of the driving mechanism, wherein the inner edge and the outer edge are farther apart when the membrane is in the fully pressurizing configuration than when the membrane is in the fully depressurizing configuration.20. The system of clause 12, wherein the membrane is actuated between the fully pressurizing configuration and the fully depressurizing configuration without a direct mechanical link between the driving mechanism and the membrane.21. The system of clause 20, wherein the membrane is magnetically actuated between the fully pressurizing configuration and the fully depressurizing configuration.Attorney Docket No.: CDB.016WO22. The system of clause 20 or 21, wherein the membrane is actuated between the fully pressurizing configuration and the fully depressurizing configuration by application of a pressure or a vacuum to the second side of the movable divider.23. The system of clause 12, wherein the membrane forms a bladder configured to form a circumferential seal against an internal surface of the housing.24. The system of any one of clauses 1-23, wherein the driver chamber comprises a temperature modulation system operably coupled to the controller.25. The system of any one of clauses 1-24, wherein the driving mechanism comprises at least one linear actuator.26. The system of clause 25, wherein the at least one linear actuator comprises a first linear actuator configured to decrease the operating chamber volume, and a second linear actuator configured to decompress the operating chamber volume.27. The system of clause 26, wherein the driving mechanism comprises an adjustable connection rod unit with an adjustable effective length for converting a rotational input to a linear output.28. The system of any one of clauses 1-27, wherein the driving mechanism comprises a driving disc oriented non-orthogonally to a rotational axis of the driving disc for converting a rotational input to a linear output.29. The system of any one of clauses 1-28, wherein the inflation fluid comprises helium.30. The system of any one of clauses 1-29, wherein the fluid flow line comprises a pump catheter having a first distal end and a first proximal end, and an extension tubing having a second distal end and a second proximal end, andAttorney Docket No.: CDB.016WO wherein the first distal end is configured to couple to the expandable chamber of the volume displacement member, the second distal end is configured to couple to the first proximal end, and the second proximal end is configured to couple to the driver chamber.31. The system of any one of clauses 1-30, further comprising a hub comprising one or more valves configured to control introduction, removal, or both introduction and removal of inflation fluid from the fluid flow line.32. The system of any one of clauses 1-31, wherein the controller is configured to operate the driving mechanism at a driving frequency of at least 10 Hz.33. The system of any one of clauses 1-32, wherein the controller is configured to operate the driving mechanism at a driving frequency of at least 20 Hz.34. The system of any one of clauses 1-33, wherein the controller is configured to operate the driving mechanism at a driving frequency of at least 30 Hz.35. The system of any one of clauses 1-34, further comprising at least one pressure sensor configured to measure pressure of the inflation fluid.36. The system of clause 35, wherein the controller is configured to adjust at least one of a driving frequency, a stroke length, or a driving speed of the driving mechanism based on the pressure of the inflation fluid.37. The system of clause 35 or 36, wherein the controller is configured to adjust a stroke length of the driving mechanism as a function of driving frequency of the driving mechanism.38. The system of any one of clauses 1-37, wherein the controller is configured to adjust a at least one of a driving frequency, a stroke length, or a driving speed of the driving mechanism based on a flow rate of the inflation fluid.Attorney Docket No.: CDB.016WO39. A method for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device has a volume displacement member with an expandable chamber and the volume displacement chamber is movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the method comprises: providing a driver chamber with an operating chamber volume fillable with an inflation fluid, a driving mechanism configured to cyclically decrease and increase the operating chamber volume at a driving frequency, and a fluid flow line configured to convey inflation fluid between the operating chamber volume and the expandable chamber; and regulating a pumping throughput of the circulatory assist device by controlling conveyance of inflation fluid between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase at the driving frequency, wherein the driving frequency is 5 Hz or greater.40. The method of clause 39, further comprising automatically regulating the pumping throughput of the circulatory assist device based on a signal received from at least one sensor.41. The method of clause 39 or 40, wherein the at least one sensor senses at least one of an inflation fluid pressure, inflation fluid temperature, blood pressure in the heart or blood vessel, or blood flow in the patient’s heart or blood vessel.42. The method of any one of clauses 39-41, further comprising operating the driving mechanism at a driving frequency of at least 10 Hz.43. The method of any one of clauses 39-42, further comprising operating the driving mechanism at a driving frequency of at least 20 Hz.44. The method of any one of clauses 39-43, further comprising operating the driving mechanism at a driving frequency of at least 30 Hz.Attorney Docket No.: CDB.016WO45. A system, comprising: a circulatory assist device comprising a volume displacement member with an expandable chamber, wherein the volume displacement member is cyclically movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume; and a driver system for actuating the circulatory assist device, the driver system comprising: a driver chamber with an operating chamber volume fillable with an inflation fluid; a driving mechanism configured to cyclically decrease and increase the operating chamber volume at a driving frequency; a fluid flow line configured to convey inflation fluid between the operating chamber volume and the expandable chamber; and a controller configured to control conveyance of inflation fluid between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase at the driving frequency, thereby regulating a pumping throughput of the circulatory assist device, wherein the controller is configured to maintain the driving frequency at 5 Hz or greater.46. The system of clause 45, wherein the controller is configured to automatically regulate at least one of the driving frequency, a stroke length, or a driving speed of the driving mechanism based at least in part on a signal received from at least one sensor.47. The system of clause 45 or 46, wherein the driver chamber comprises a housing and a movable divider, wherein the operating chamber volume is on a first side of the movable divider.48. The system of any one of clauses 45-47, wherein the inflation fluid comprises helium.Attorney Docket No.: CDB.016WO49. The system of any one of clauses 45-48, wherein the inflation fluid comprises hydrogen.50. The system of any one of clauses 45-49, wherein the inflation fluid comprises carbon dioxide.51. The system of any one of clauses 45-50, wherein the fluid flow line comprises a pump catheter having a first distal end and a first proximal end, and an extension tubing having a second distal end and a second proximal end, and wherein the first distal end is configured to couple to the expandable chamber of the volume displacement member, the second distal end is configured to couple to the first proximal end, and the second proximal end is configured to couple to the driver chamber.52. The system of any one of clauses 45-51, further comprising a hub comprising one or more valves configured to control introduction, removal, or both introduction and removal of inflation fluid from the fluid flow line.53. The system of any one of clauses 45-52, wherein the controller is configured to operate the driving mechanism at a driving frequency of at least 10 Hz.54. The system of any one of clauses 45-53, wherein the controller is configured to operate the driving mechanism at a driving frequency of at least 20 Hz.55. The system of any one of clauses 45-54, wherein the controller is configured to operate the driving mechanism at a driving frequency of at least 30 Hz.56. The system of any one of clauses 45-55, wherein the controller is configured to vary at least one of the driving frequency, a stroke length, or a driving speed of the driving mechanism.Attorney Docket No.: CDB.016WO57. The system of any one of clauses 45-56, wherein the volume displacement member comprises a balloon.58. The system of any one of clauses 45-57, wherein the circulatory assist device comprises a conduit surrounding at least a portion of the volume displacement member, wherein the conduit comprises an expandable support and at least one fluid impermeable membrane coupled to the expandable support.59. A driver system for a circulatory assist device positionable in a vessel of a patient, the circulatory assist device having an inflatable member operable at a variable inflation frequency to produce a selected blood flow rate, the driver system comprising: a driver chamber fillable with an inflation fluid, the driver chamber having an operating chamber volume and an outlet; a driving mechanism operable to cyclically change the operating chamber volume between a high volume state and a low volume state at a driver frequency, wherein a displacement volume of inflation fluid is displaced from the driver chamber through the outlet in each cycle; and a controller coupled to the driving mechanism and configured to vary the displacement volume so as to produce the selected blood flow rate.60. The system of clause 59, wherein the driving mechanism comprises a movable divider in the chamber, wherein the divider is movable through a stroke length between the high volume state and the low volume state, wherein the controller is configured to vary the stroke length to vary the displacement volume.61. The system of clause 60, wherein the divider comprises a driving rod coupled to the divider.62. The system of clause 61, wherein the divider comprises a membrane.63. The system of clause 62, wherein the driving mechanism comprises a plunger or piston coupled to the membrane.Attorney Docket No.: CDB.016WO64. The system of any one of clauses 59-63, wherein the controller is configured to vary the displacement volume based on one or more parameters selected from inflation fluid pressure, inflation frequency, blood pressure in the vessel, blood flow rate in the vessel, current power consumption by the driver system, one or more pressure measurements within the driver system, one or more flow rate measurements within the driver system.65. The system of any one of clauses 59-64, further comprising a pressure sensor configured to measure a pressure of the inflation fluid in the driver chamber, wherein the controller is configured to adjust the displacement volume based on a signal from the pressure sensor.66. The system of any one of clauses 59-65, further comprising at least one flow rate sensor configured to measure a blood flow rate provided by the circulatory assist device, wherein the controller is configured to adjust the displacement volume based on the measured blood flow rate.67. The system of clause 66, wherein the at least one flow rate sensor comprises one or more sensors configured to measure a differential pressure of inflation fluid within the driver system, wherein the blood flow rate is calculated by the differential pressure measurement.68. The system of any one of clauses 59-67, wherein the controller is configured to vary the displacement volume in accordance with a linear relationship between the blood flow rate and the driving frequency.69. The system of any one of clauses 59-68, wherein the controller is further configured to vary the driving frequency.70. A driver system for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device comprises a volume displacement member with an expandable chamber and the volume displacement member is movable between an expansion phase in which the expandable chamber has a firstAttorney Docket No.: CDB.016WO volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the driver system comprises: a driver chamber with an operating chamber volume fillable with an inflation fluid, wherein the operating chamber volume is at least partially defined by a flexible membrane; a driving mechanism configured to cyclically decrease and increase the operating chamber volume by moving the membrane between a fully pressurizing configuration and a fully depressurizing configuration; a fluid flow line configured to convey inflation fluid between the operating chamber volume and the expandable chamber; and a controller configured to control the driving mechanism such that inflation fluid is conveyed between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase, thereby regulating a pumping throughput of the circulatory assist device.71. The system of clause 70, wherein the membrane is coupled to a plunger, wherein the plunger is movable by the driving mechanism.72. The system of clause 71, wherein the membrane is coupled to a periphery of the plunger.73. The system of clause 72, wherein the membrane comprises an inner edge coupled to the periphery of the plunger and an outer edge coupled to a wall at least partially defining the operating chamber volume.74. The system of clause 73, wherein the inner edge and the outer edge of the membrane are farther apart when the membrane is in the fully pressurizing configuration than when the membrane is in the fully depressurizing configuration.75. The system of any one of clauses 70-74, wherein the membrane is actuated between the fully pressurizing configuration and the fully depressurizing configuration without a direct mechanical link between the driving mechanism and the membrane.Attorney Docket No.: CDB.016WO76. The system of clause 73, wherein the membrane forms a bladder configured to form a circumferential seal against the wall at least partially defining the operating chamber volume.77. A driver system for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device comprises a volume displacement member with an expandable chamber and the volume displacement member is movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the driver system comprises: a driver chamber with an operating chamber volume fillable with an inflation fluid, wherein the operating chamber volume is at least partially defined by a movable surface; a driving mechanism configured to cyclically decrease and increase the operating chamber volume with a magnetic coupling between the driving mechanism and the movable surface; a fluid flow line configured to convey inflation fluid between the operating chamber volume and the expandable chamber; and a controller configured to control the driving mechanism such that inflation fluid is conveyed between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase, thereby regulating a pumping throughput of the circulatory assist device.78. The system of clause 77, wherein the driver chamber comprises a housing, and wherein the movable surface is on a movable divider arranged within the housing.79. The system of clause 78, wherein the movable divider comprises one or more magnetic coupling discs.80. The system of clause 79, wherein the movable surface comprises a flexible membrane.Attorney Docket No.: CDB.016WO81. The system of clause 77, wherein the driver chamber comprises a housing, and wherein the movable surface is a wall of the housing.82. A driver system for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device comprises a volume displacement member with an expandable chamber and the volume displacement member is movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the driver system comprises: a driver chamber comprising a housing at least partially defining an operating chamber volume fillable with an inflation fluid; a driving mechanism configured to cyclically contract and expand the housing; a fluid flow line configured to convey inflation fluid between the operating chamber volume and the expandable chamber; and a controller configured to control the driving mechanism such that inflation fluid is conveyed between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase, thereby regulating a pumping throughput of the circulatory assist device.83. The system of clause 82, wherein the housing comprises a bellows.84. The system of clause 82 or 83, wherein the housing comprises one or more pleats.85. The system of any one of clauses 82-84, wherein the housing comprises one or more hinge joints.86. The system of any one of clauses 82-85, further comprising a filler material sized and shaped to occupy at substantial portion of the interior of the operating chamber volume.Attorney Docket No.: CDB.016WO87. A driver system for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device comprises a volume displacement member with an expandable chamber and the volume displacement member is movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the driver system comprises: a driver chamber configured to be in fluidic communication with a reservoir containing an inflation fluid, wherein the driver chamber comprises an operating chamber volume fillable with the inflation fluid; a fluid flow line configured to convey inflation fluid to and from the expandable chamber; one or more sensors configured to provide a sensor signal indicative of a status of the inflation fluid in at least one of the driver chamber, the fluid flow line, or the hub; and a controller configured to (i) operate the driver chamber such that inflation fluid is conveyed between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase at the driving frequency, thereby regulating a pumping throughput of the circulatory assist device, and (ii) modulate a flow rate of the inflation fluid from the reservoir to the driver chamber based at least in part on the sensor signal.88. The system of clause 87, further comprising a hub configured to be in fluidic communication with the driver chamber, the fluidic flow line, and the reservoir containing the inflation fluid.89. The system of clause 87 or 88, wherein the controller is further configured to at least partially evacuate inflation fluid from one or more of the driver chamber, the fluid flow line, or the volume displacement member.90. The system of any one of clauses 87-89, wherein the controller is configured to at least partially evacuate inflation fluid from the driver chamber, the fluid flow line, and the volume displacement member in response to a detected adverse event.Attorney Docket No.: CDB.016WO91. The system of clause 90, wherein the one or more sensors comprises a pressure sensor.92. A driver system for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device comprises a volume displacement member with an expandable chamber and the volume displacement member is movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the driver system comprises: a driver chamber configured to be in fluidic communication with a negative pressure source, wherein the driver chamber comprises an operating chamber volume fillable with the inflation fluid; a fluid flow line configured to convey inflation fluid to and from the expandable chamber; one or more sensors configured to provide a sensor signal indicative of a status of the inflation fluid in at least one of the driver chamber, the fluid flow line, or the hub; one or more valves configured to control a flow of the inflation fluid to the negative pressure source; and a controller configured to operate the one or more valves to modulate the flow of the inflation fluid to the negative pressure source in response to the sensor signal.93. The system of clause 92, wherein the one or more valves comprises a plurality of valves arranged in parallel.94. The system of clause 92 or 93, wherein the controller is further configured to operate the one or more valves to at least partially evacuate inflation fluid from one or more of the driver chamber, the fluid flow line, or the volume displacement member.95. The system of any one of clauses 92-94, further comprising a hub configured to be in fluidic communication with the driver chamber, the fluidic flow line, and a reservoir containing the inflation fluid.Attorney Docket No.: CDB.016WO96. The system of any one of clauses 92-95, wherein the controller is configured to operate the driver chamber such that inflation fluid is conveyed between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase at the driving frequency, thereby regulating a pumping throughput of the circulatory assist device.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Instead, emphasis is placed on illustrating clearly the principles of the present disclosure.

[0007] FIG. 1 is a schematic illustration of an example driver system for a circulatory assist device, in accordance with the present technology.

[0008] FIG. 2A is a schematic illustration of an example circulatory assist device, in accordance with the present technology.

[0009] FIG. 2B is a schematic illustration of an example circulatory assist device positioned in a patient, in accordance with the present technology.

[0010] FIGS. 3 A-3E are schematic illustrations of an example circulatory assist device during operation, in accordance with the present technology.

[0011] FIG. 4 is a schematic illustration of an example chamber in a driver system, in accordance with the present technology.

[0012] FIG. 5 is a schematic illustration of an example chamber in a driver system, in accordance with the present technology.

[0013] FIGS. 6A and 6B depict example coupling discs for use in an example chamber in a driver system, in accordance with the present technology.

[0014] FIGS. 7A-7C are schematic illustrations of an example chamber in a driver system, in accordance with the present technology.

[0015] FIGS. 8A and 8B are schematic illustrations of an example chamber in a driver system, in accordance with the present technology.

[0016] FIGS. 9A and 9B are schematic illustrations of an example chamber in a driver system, in accordance with the present technology.Attorney Docket No.: CDB.016WO

[0017] FIGS. 9C and 9D are schematic illustrations of an example chamber in a driver system, in accordance with the present technology.

[0018] FIGS. 9E and 9F are schematic illustrations of an example chamber in a driver system, in accordance with the present technology.

[0019] FIGS. 10A and 10B are schematic illustrations of an example chamber in a driver system, in accordance with the present technology.

[0020] FIG. 11 is a summary of example specifications for a chamber in a driver system, in accordance with the present technology.

[0021] FIG. 11A is a summary of example specifications for an extension line and a catheter in a driver system, in accordance with the present technology.

[0022] FIGS. 12A and 12B are schematic illustrations of an example chamber in a driver system, in accordance with the present technology.

[0023] FIGS. 13A and 13B are schematic illustrations of an example chamber in a driver system, in accordance with the present technology.

[0024] FIGS. 14A and 14B are schematic illustrations of an example chamber in a driver system, in accordance with the present technology.

[0025] FIG. 15 is a schematic illustration of an example driving mechanism in a driver system, in accordance with the present technology.

[0026] FIG. 16 is a schematic illustration of an example driving mechanism in a driver system, in accordance with the present technology.

[0027] FIGS. 17-20B are schematic illustrations of an example driving mechanism in a driver system, in accordance with the present technology.

[0028] FIG. 21 is a schematic illustration of an example driving mechanism in a driver system, in accordance with the present technology.

[0029] FIG. 22A is a schematic illustration of an example chamber with a temperature modulation system, in accordance with the present technology.

[0030] FIG. 22B is a schematic diagram of circuitry components for operating a chamber with a temperature modulation system.Attorney Docket No.: CDB.016WO

[0031] FIGS. 23A and 23B are schematic illustrations of an example extension tubing having adjustable length, in accordance with the present technology.

[0032] FIGS. 24 A and 24B are schematic illustrations of an example extension tubing having adjustable length, in accordance with the present technology.

[0033] FIG. 25 is a schematic illustration of an example temperature modulation arrangement for modulating temperature of at least a portion of a driver system, in accordance with the present technology.

[0034] FIG. 26 is a schematic illustration of an example implementation of a driver system incorporating refilling features and safety features, in accordance with the present technology.DETAILED DESCRIPTION

[0035] The present technology relates to driver systems and methods for circulatory assist devices. Some variations of the present technology, for example, are directed to driver systems and methods for circulatory assist devices having an inflatable balloon. Specific details of several variations of the technology are described below with reference to FIGS. 1-26.

[0036] As used herein, the terms “proximal” and “distal” (and derivatives thereof) are used primarily within a frame of reference of a user placing a circulatory assist device within a patient, unless otherwise specified. For example, “proximal” primarily refers to a direction closer to the user, while “distal” primarily refers to a direction farther from the user.I. Overview

[0037] Disclosed herein are systems and methods for driving circulatory assist devices, such as a circulatory assist device having an inflatable balloon and / or other fillable (e.g., inflatable) volume displacement member configured for facilitating pumping of a fluid through the circulatory assist device. For example, in some variations, a driver system can include a chamber (also referred to herein as a “driver chamber”) with an operating chamber volume fillable with an inflation fluid, a driving mechanism having a stroke length and configured to cyclically decrease (e.g., compress) and increase (e.g., decompress) the operating chamber volume at a driving frequency, a fluid flow line configured to convey inflation fluid between the operating chamber volume and the inflatable balloon, and a controller operably coupled to the driver chamber, the driving mechanism, and / or the fluid flow line. The controller can be configured to automatically regulate a pumping throughput of the circulatory assist device,Attorney Docket No.: CDB.016WO such as by adjusting the driving frequency, the change in operating chamber volume, the stroke length, a filling pressure in the operating chamber volume, and / or compliance of the operating chamber volume.

[0038] For example, FIG. 1 is a schematic illustration of an example driver system, in accordance with the present technology. As shown in FIG. 1, the driver system 100 can be operably coupled to a circulatory assist device 10 that is placed in a patient P (e.g., in a heart chamber such as the left or right ventricle, in an ascending aorta, in a descending aorta, etc.). The circulatory assist device 10 can include an inflatable balloon (not shown in the schematic of FIG. 1) and / or other inflatable volume displacement member. The driver system 100 can include a driver chamber 110 having an operating chamber volume 112 (e.g., a variable volume), and a driving mechanism 120 configured to control a change in volume of the operating chamber volume (e.g., by a stroke length controlled by the driving mechanism 120). The driving mechanism 120 is configured to cyclically compress and decompress (e.g., change the working volume of) the operating chamber volume 112. The operating chamber volume 112 can be fillable with an inflation fluid (e.g., a compressible fluid or gas such as helium, hydrogen, carbon dioxide, nitrogen, etc., and / or an incompressible fluid such as water or saline) and is in fluidic communication with a fluid flow line 150 for conveying inflation fluid between the operating chamber volume and the inflatable balloon (e.g., from the operating chamber volume 112 to the balloon, and from the balloon to the operating chamber volume 112). As shown in FIG. 1, the fluid flow line 150 can include one or more fluidic channels (e.g., tubing) in series, such as a catheter 154 having at least a portion that is insertable in a patient, and / or an extension line 152 having a distal end coupled to the catheter 154 and a proximal end in fluidic communication with the operating chamber volume 112. In some variations, the extension line 152 may be omitted from the fluid flow line 150 (e.g., fluid flow line 150 can include only the catheter 154), such as in instances where the driver system is located sufficiently near the patient, if the catheter 154 is sufficiently long to traverse the distance between the driver system and the patient, etc.

[0039] When the operating chamber 112 is compressed, inflation fluid is driven from operating chamber 112 through the fluid flow line 150 into the inflatable balloon. The driver system 100 can be configured to deliver inflation fluid to the inflatable balloon at stroke volumes ranging from 10-250 ml, and at a pressure of at least 200 mmHg, in some variations pressures of at least 500 mmHg, and, in some embodiments, at maximum pressures not exceeding about 1500 mmHg. For example, the driver system 100 can be configured to deliverAttorney Docket No.: CDB.016WO inflation fluid to the inflatable balloon at a positive pressure of between about 200 mmHg and about 1500 mmHg, or between about 100 mmHg and about 800 mmHg. When the operating chamber 112 is decompressed, negative pressure is applied through the fluid flow line 150 to draw inflation fluid from the inflatable balloon into the operating chamber 112. Such negative pressures can be lower than about -100 mmHg, in other variations lower than about -400 mmHg, lower than about -600 mmHg, and, in some embodiments, will usually not be lower than about -700 mmHg. For example, the driver system 100 can be configured to draw inflation fluid from the inflatable balloon at a negative pressure of between about 100 mmHg and about 0600 mmHg, or between about -200 mmHg and about -700 mmHg. In some variations, driver system 100 is configured to alternate between the compressed and decompressed states at a frequency of at least 200 cycles per minute, or at least 300 cycles per minute, or at least 500 cycles per minute, and in some examples as high as 10,000 cycles per minute. The driver systems of the invention are uniquely configured to continuously operate at these very high frequencies and pressure ranges over long periods of time (e.g., 14 or more days) while minimizing fluid leakage, heat, and noise.

[0040] In some variations, the driver system 100 can further include a hub 130 configured to enable control of introduction of inflation fluid into the fluid flow line 150 (and / or the operating chamber volume 112), and / or removal of the inflation fluid from the fluid flow line 150 (and / or the operating chamber volume 112). For example, a controller 160 can be operably coupled to one or more valves 132 and / or pumps (not shown) such that the controller 160 can control flow of an inflation fluid between a fluid reservoir 140 and the fluid flow line 150 (and / or the operating chamber volume 112). In some variations, the hub 130 can additionally or alternatively control pressure inside the operating chamber volume 112 (by application of a positive pressure and / or vacuum, etc.), such as in a step-wise or incremental manner. However, in some variations the driver system 100 can omit the hub 130, and / or at least a portion of the functionality of the hub 130 described herein may be incorporated into the chamber 110., For example, in some variations, the controller 160 can operate to control pressure inside the operating chamber volume 112 by, for example, dampening the end of the compression phase (e.g., not finishing the end of an inflation stroke of a piston mechanism in the driving chamber, as described herein) in a tuned manner so as to increase the effective dead volume within the fluidic system).

[0041] The controller 160 can additionally or alternatively function to control other aspects of the driver system in view of desired inflation and deflation of the balloon in theAttorney Docket No.: CDB.016WO circulatory assist device, including but not limited to operation of the driving mechanism 120 (e.g., speed of operation such as within a stroke or pump cycle, stroke length, driving frequency, etc.) to increase and decrease the volume of the operating chamber, control of fluidic pressure in the system, control of temperature within the system, control of dead volume within the system, and / or control of compliance of the driver chamber during operation. In some variations, the controller 160 can receive temperature information from one or more temperature sensors on or in the driver chamber 110 and / or hub 130, and provide closed-loop control of the chamber 110 and / or hub 130 so as to control pressure during compression and decompression of the chamber 110 (and corresponding inflation and deflation of a balloon or other volume displacement member in the circulatory assist device 10), control impedance to flow of the inflation fluid within the fluidic system, improve detection of any fluidic leaks in the fluidic system, etc.

[0042] Variations of such driver systems, as described herein, have various advantages. For example, the driver system is operable at high frequencies to enable high frequency inflation and deflation, with a fast response time for such inflation and deflation. When operated to drive an inflation fluid to and from an inflatable balloon in a circulatory assist device, the driver system can help enable a high volumetric flow through and / or from the circulatory assist device. Furthermore, the driver system is operable to pressurize and depressurize the inflatable balloon with high precision, thereby enabling greater control over the amount and / or rate of inflation and deflation of the balloon (e.g., to avoid insufficient inflation and / or deflation, to avoid excessive inflation and / or deflation beyond a predetermined threshold that may, for example, relate to desired pump output, etc.) and resulting in greater pumping efficiency of the circulatory assist device.

[0043] Additional advantages of the driver system, as further described below, include the ability to dynamically adjust and / or address changing conditions within the driver system and / or patient environment system, such as leakages of inflation fluid within the system (e.g., within the driver chamber and / or fluid flow line) and temperature (which can affect fluid dynamics and / or filling pressure, for example). Furthermore, the driver system, when operated, can advantageously result in low noise and low vibrations, making it suitable for a variety of environments including clinical environments (e.g., bedside). Other aspects, such as being a compact size with a low footprint, can additionally or alternatively help make the driver system suitable for clinical environments.Attorney Docket No.: CDB.016WO

[0044] Further aspects of example circulatory assist devices, and driver systems and methods therefor, are described in further detail below.II. Circulatory assist devices

[0045] In some variations, a circulatory assist system includes a circulatory assist device that is positionable in a patient (e.g., in a cardiovascular lumen, such as a blood vessel and / or heart chamber). For example, the circulatory assist device can function as a percutaneous ventricular assist device (pVADs), a transvalvular pVAD, or an intra-vascular and intra-ventricular blood pump, though other uses of the circulatory assist device are contemplated.

[0046] In some variations, the circulatory assist device (e.g., blood pump) can include a pump body having a conduit, at least one inlet valve, and a volume displacement member arranged in the conduit. The conduit may have an inlet, an outlet, and a longitudinal flow axis extending between the inlet and the outlet. The inlet valve may be configured to receive a fluid (e.g., patient body fluid such as blood) along the flow axis. Furthermore, in some variations, the portion of the conduit between the volume displacement member and an outlet of the conduit may be valveless (e.g., the circulatory assist device may include only one or more inlet valves). The fluid column traveling in an axial direction in the conduit may have particular advantages, as described below. The volume displacement member may be operable in an expansion phase and a contraction phase, where the volume displacement member defines an expandable chamber that has a higher volume when the volume displacement member is in the expansion phase and a lower volume when the volume displacement is in the contraction phase. The pump body may be configured to convey fluid through the outlet during both at least a part of the expansion phase and at least a part of the contraction phase of the volume displacement member. In some variations, the pump body may be configured to substantially continuously convey fluid through the outlet during both at least a part of the expansion phase and at least a part of the contraction phase of the volume displacement member. Additionally or alternatively, in some variations the circulatory assist device may include other suitable pump device(s) configured to convey fluid through the outlet of the conduit. In some variations, the circulatory assist device may include a pump body with a conduit having an inlet, and outlet, and a longitudinal flow axis extending between the inlet and the outlet, where the inlet comprises one or more inlet valves (e.g., at least one one-way valve) and the outlet comprises one or more outlet valves (e.g., at least one one-way valve).Attorney Docket No.: CDB.016WO

[0047] For example, in some variations, as shown in FIG. 2A, a circulatory assist device 200 can include a pump body 220 configured to receive a fluid (e.g., blood) when placed in a cardiovascular lumen of a patient and convey the fluid back to the cardiovascular lumen for circulatory assistance. The circulatory assist device 200 can, for example, be similar to the circulatory assist device 10 described herein with respect to FIG. 1. The pump body 220 may include a conduit with a distal inflow region 220a that conveys fluid into the pump body 220, a proximal outflow region 220c that conveys fluid out of the pump body 220, and an intermediate region 220b between the inflow region 220a and the outflow region 220c. In some variations, the intermediate region 220b is configured to retain received fluid until the fluid exits through the outflow region 220c. Generally, the pump body 220 (at least the intermediate region 220b, for example) may have an elongated shape (e.g., cylindrical or elongated with an elliptical cross-section), such as a tubular or pipe-like shape. However, in some variations the pump body 220 may have an elongated shape with a varying cross-section (e.g., the pump body 220 may be bulbous or hourglass-shaped) along the conduit length. The conduit may have a longitudinal flow axis extending between an inlet of the inflow region 220a and an outlet of the outflow region 220c. The flow axis may generally follow a longitudinal axis of the conduit of the pump body 220, which may be at least partially linear and / or at least partially curved. As such, the flow axis between the inlet and the outlet may be linear, may be curved, or may have one or more portions that are linear and one or more portions that are curved. Furthermore, the exact path of the flow axis may change dynamically depending on, for example, the shape of the pump body 220 during any given point in time during operation (e.g., a linear portion of the flow axis may become more curved, a curved portion of the flow axis may become more linear, the contour of a curved portion of the flow axis may change, etc.). For example, as the pump body 220 is operated, the exact relative positions of the inlet and the outlet of the conduit may change.

[0048] As further described below, the pump body 220 may further include an inlet valve 240 configured to receive a fluid through the inlet of the conduit along the flow axis, and a volume displacement member 230 (e.g., balloon) arranged in the conduit. The volume displacement member 230 may be operable in an expansion phase and a contraction phase. For example, in variations in which the volume displacement member 230 includes a balloon, the balloon may be inflated up to a first volume of its expandable chamber in the expansion phase, and deflated down to a second volume of its expandable chamber in the contraction phase, wherein the second volume is less than the first volume. In operation, the pump body 220 mayAttorney Docket No.: CDB.016WO be configured to convey the received fluid through an outlet of the outflow region 220c during both at least a part of the expansion phase and at least a part of the contraction phase of the volume displacement member 230. In some variations, such conveyance of fluid through the outlet may be sustained at least partially due to created and maintained momentum of a fluid column along the flow axis of the conduit. Additional details of continued momentum of flow, and further example features for creating and maintaining momentum of fluid in the pump body 220, are described in International Patent Application No. PCT / IB2024 / 057381, which is incorporated in its entirety by this reference.

[0049] In some variations, the pump body 220 may be coupled to or otherwise arranged on a catheter 210, which can be used to position the pump body 220 in the patient and / or facilitate operation of the volume displacement member 230 in the expansion phase and the contraction phase. The catheter 210 can, for example, be similar to catheter 154 as described herein with respect to FIG. 1. In some variations, the pump body 220 may be coupled to a distal portion of the catheter 210, while a proximal portion (not shown in FIG. 2 A) of the catheter 210 may be outside the patient and coupled to an extension tubing (e.g., extension tubing 152) and / or otherwise in fluidic communication with the driver system for expansion and contraction (e.g., inflation and deflation) of the volume displacement member 230. For example, the catheter 210 may include one or more lumens for conveying a guidewire and / or steering wire(s) that are controlled external to the patient for positioning the pump body 220 in the patient. Additionally or alternatively, in some variations (e.g., in which the volume displacement member 230 includes a balloon), the catheter 210 may include one or more lumens for conveying a fluid (e.g., gas) for cyclically inflating the balloon. Furthermore, in some variations the catheter 210 may additionally or alternatively include one or more lumens for conveying at least one wire or other conductive element for carrying signals to and / or from sensor(s) in the pump body 220, catheter, 210, and / or other portion of the circulatory assist device 200. Even further, in some variations the catheter 210 may additionally or alternatively include one or more lumens coupled to a manometer to facilitate measurement of pressure within the balloon. A lumen may, in some variations, be configured to perform any one or more of the above-described lumen functions.

[0050] In some variations, the pump body 220 may include one or more features to aid repositioning or retrieval of the pump body 220 from the patient (e.g., after circulatory assistance is no longer needed, or if the pump body 220 is to be swapped with another circulatory assist device). Additionally or alternatively, the distal end of the pump body 220Attorney Docket No.: CDB.016WO may include one or more atraumatic features to help reduce or avoid tissue trauma in the event that the distal end of the pump body 220 abuts tissue (e.g., left ventricle wall). For example, as shown in FIG. 2A, a connector 226 coupled to or integrally formed with a distal end of the pump body 220 may include a curved pigtail structure at the distalmost end of the connector.

[0051] In some variations, as shown in FIG. 2A, the pump body 220 may include a conduit with an expandable support 222 and at least one fluid impermeable membrane 224 adjacent to the expandable support. The pump body 220, for example by virtue of the geometric and / or material properties of the support 222 and / or the membrane 224, may be substantially low-compliant so as to resist deformation during the expansion and contraction cycles of the volume displacement member 230. Furthermore, the conduit may have a circular, ellipsoidal, or other suitable curved wall, so as to help the conduit (and the overall pump body 220) be more resistant to failure in response to internal pressure (i.e., positive and / or negative pressure). The walls of the conduit, including the support 222 and the membrane 224, can be configured to provide a counterpressure during the pressure cycling during inflation and deflation. Additionally, the curved wall of the conduit may help facilitate suitable clearance between the outer surface of the volume displacement member 230 and the conduit.

[0052] The support 222 functions at least in part to provide structural support to the pump body 220. For example, the support 222 may help the conduit to be resistant against diametrical expansion and / or collapse in response to increased pressure when filled with blood and during expansion of the volume displacement member. Such non-distensibility allows spacing to be maintained between the pump body 220 and the ventricular wall to minimize trauma to heart tissue and also increases pump efficiency. Additionally, the support 222 may help the conduit be resistant against collapsing in response to decreased pressure (e.g., during contraction of the volume displacement member). In some variations, the support 222 may be configured to be collapsible or crimpable into a lower profile transport state during delivery to the target placement location (e.g., left ventricle and / or ascending aorta), and / or when subject to sufficient external forces to allow for endovascular delivery and retrieval. The support 222 may further be configured to expand into a deployed state, such as by self-expansion and / or expansion with another device (e.g., balloon-expandable). In some variations, the support 122 may include a frame or skeleton of a resilient metal such as nickel -titanium alloy, cobaltchrome, chromoly steel, or stainless steel, etc., or a suitable polymeric material such as nylon. The support 222 may, for example, include woven wires, mesh, a basket, laser-cut material, or a monolithic tube having an arrangement of openings, slits, or cells which allow expansion inAttorney Docket No.: CDB.016WO at least one dimension from the transport state to the deployed state. For example, the support 222 can include a plurality of struts or cells arranged in a radially expandable geometry. The support 222 can include a single continuous body, or can include multiple bodies coupled together (e.g., nested mesh tube structures with overlapping walls).

[0053] As described above, in some variations, the pump body 220 may include at least one fluid impermeable membrane 224 adjacent to a surface of the support 222. The membrane 224 may extend along at least a portion of the length of pump body 220. For example, as shown in FIG. 2A, the membrane 224 may extend along at least the intermediate region 220b of the pump body 220. The membrane 224 may further extend along at least a portion of the inflow region 220a and at least a portion of the outflow region 220c. In some variations, at least a portion of the inflow region 220a and / or the outflow region 220c may remain uncovered by the membrane 224 so as to permit passage of fluid through the support 222 in and / or out of the conduit (e.g., through open and uncovered cells of the support 222). The membrane 224 may include one continuous layer of material, or may include multiple segments of material that are coupled to one another (e.g., radial or longitudinal strips sealed to one another, such as by heat welding). Additionally or alternatively, the membrane may have a varying durometer across its body (e.g., along the length of the pump body), which may, for example, create a flexible or adaptable structure for fitting to suitable anatomy.

[0054] The pump body 220 may include at least one membrane 224 adjacent to an inner surface and / or an outer surface of the support 222. In some variations, one or more membranes 224 may be adjacent to an inner surface and / or an outer surface of the support 222. That is, the one or more membranes 224 may include an inner membrane and / or an outer membrane. For example, the pump body 220 may include an inner membrane coupled to an inner surface of the support 222. As another example, the pump body 220 may include an outer membrane adjacent to an outer surface of the support 222. In this example, the outer membrane may be coupled to the outer surface of the support 222, or may be unattached from the outer surface of the support 222. In variations in which the outer membrane is not attached to the outer surface of the support 222, the outer membrane may overlie the outer surface of the support 222 such that the outer membrane is configured to expand in tandem with the support 222 when the support 222 is expanded. In these variations, the outer membrane may help contain radially outward pressure in the pump body 220, while the support 222 may help prevent collapse of the pump body 220 by providing outward support against negative (e.g., inward) pressure.Attorney Docket No.: CDB.016WO

[0055] As yet another example, the pump body 220 may include both an inner membrane coupled to an inner surface of the support 222, and an outer membrane coupled to an outer surface of the support 222, such that at least a portion of the support 222 is embedded in a membrane material (or sandwiched between membrane layers). Furthermore, the pump body 220 may include more than one layer of an inner membrane (e.g., two or more inner membrane layers), and / or more than one layer of an outer membrane (e.g., two or more outer membrane layers). In variations in which the pump body 220 includes both an inner membrane and an outer membrane, the inner membrane and the outer membrane may extend over the same portions of the support 222, or may extend over different portions of the support 222.

[0056] The inner membrane and / or the outer membrane may be coupled to the support in any suitable manner, including, for example, spray lamination, welding, bonding, electrospinning, and / or adhesive. Furthermore, in some variations, the support 222 may be at least partially embedded within a fluid impermeable membrane 224 (e.g., via overmolding or other suitable technique). In some variations, the one or more membranes 224 may be coupled to the support 222 continuously along the inner and / or outer surfaces of the support 222. However, in some variations, at least some of the one or more membranes 224 may be coupled to the support 222 at only a portion of the inner and / or outer surfaces of the support 222, such as only along certain selected axial locations of the support 122 and / or certain selected radial locations around the support 122).

[0057] In some variations, the material of the one or more membranes 224 may be flexible and durable, such as nylon or polyurethane with high durometer values. This can be achieved by using a polymer with high tensile modulus. For example, the membrane comprises a TPU such as pellethane or tecothane. In one example, the membrane can include tecothane in a durometer of approximately 72D, which may accommodate the stress placed on the conduit during operation of the circulatory assist device 200, without undergoing plastic deformation. In some variations, the one or more membranes 224 may include an inelastic (e.g., low- compliant) material. For example, an inelastic material for the one or more membranes 224 may be suitable in variations in which the membrane(s) 224 are coupled to the support 222 at only a portion of the inner and / or outer surfaces of the support 222.

[0058] The volume displacement member 230 may include any of various types of mechanisms capable of displacing a volume of fluid in a cyclical, repeating manner. In some variations, the volume displacement member 230 may include an inflatable balloon that can be inflated with a fluid to an expanded, high-volume state and deflated partially or completely toAttorney Docket No.: CDB.016WO a contracted, low-volume state. In other variations, a piston, bellows, accordion-style expandable body, and / or other type of volume displacement member may be used. The volume displacement member is capable of moving cyclically between the contracted low-volume state in which it occupies a smaller portion of the conduit, to an expanded high-volume state, in which it occupies a substantially larger portion of the conduit, thus displacing blood therefrom. The volume displacement member 230 may be configured to cyclically move between these contracted and expanded states at a high frequency, such as at least about 200 beats per minute, at least about 300 beats per minute, at least about 500 beats per minute, at least about 800 beats per minute, at least about 1000 beats per minute, or at least about 1200 beats per minute, at least about 1500 beats per minute, at least about 2000 beats per minute, at least about 2500 beats per minute, at least about 3000 beats per minute (e.g., between about 200 beats per minute and about 3000 beats per minute, or between about 500 beats per minute and about 2000 beats per minute, or between about 800 beats per minute and about 1000 beats per minute). In some variations, the frequency of the contraction / expansion cycle of the volume displacement member 230 may be dynamically controlled and / or set to a predetermined desired frequency. In some variations, the frequency of the contraction / expansion cycle of the volume displacement member 230, in combination with the features (e.g., dimensions) of the rest of the pump body 220, is controlled such that the pump body is configured to convey fluid through the outlet with a flow rate of at least about 2L / min, at least about 3L / min, at least about 4L / min, at least about 5 L / min, or at least about 6L / min.

[0059] When in the fully expanded state, the volume displacement member 230 may have a maximum diameter that is smaller than the inner diameter of the support 220, thereby allowing the outer surface of the expanded volume displacement member 230 to be spaced apart from the support 220, which provides clearance for fluid to move through the conduit between the inlet and the outlet even when the volume displacement member 230 is fully expanded. Such clearance may, in some instances, further function to help limit hemolysis during high frequency operation of the volume displacement member 230. For example, in some variations, when the volume displacement member 230 is fully expanded, a spacing of at least about 0.05 mm, or at least about 1.0 mm-5.0 mm (e.g., about 1.0 mm-3.0 mm) may be maintained between the volume displacement member 230 and an interior surface of the support 220.

[0060] In variations in which the volume displacement member 230 is a balloon, it may include a durable material such as polyurethane, nylon, PEBAX, PET, PE, PVC, pellethane, orAttorney Docket No.: CDB.016WO a suitable silicone blend. The balloon may be formed of a single, thin wall of such material. For example, in one illustrative variation, the balloon may be made of pellethane 55D (or a material with similar mechanical properties), and have a wall thickness of about 10 pm-100 pm (e.g., about 20 pm). As shown in FIG. 2 A, the balloon may have a generally elongated shape and extend longitudinally along at least a portion of the length of the pump body 220. For example, the balloon in its expanded state may have a generally ellipsoidal shape.

[0061] As described above, the pump body 220 may further include at least one inlet valve 240 configured to receive fluid along the flow axis of the conduit. In this manner, flow entering the pump body 220 may travel in an axial flow direction, with little to no radial flow component orthogonal to the flow axis. The inlet valve 240 may be a one-way valve with a preferential flow direction, where the one-way valve permits flow into the pump body 220 through the inflow region 220a, while substantially preventing flow out of the pump body 220 through the inflow region 220a. Accordingly, the inlet valve 240 may be configured to operate between an open state in which flow in a first direction (e.g., into the pump body 220) is permitted, and a closed state in which flow in a second direction opposite the first direction (e.g., out of the pump body 220) is substantially prevented. For example, in the open state of the inlet valve 240, the valve leaflets may be arranged such that the leaflets do not coapt, while in the closed state of the inlet valve 240, the valve leaflets may be arranged such that the leaflets coapt. In some variations, the inlet valve 240 may be configured to transition between the closed and open states in a transition time of between about 1 ms and about 100 ms (e.g., about 10 ms). In some variations, the inlet valve 240 may be a passive valve configured to open and close in response to pressure change, though in some variations the inlet valve 240 may additionally or alternatively be an active valve whose opening and closure may be controlled by a suitable actuator. In some variations, the inlet valve 240 can be a multi-leaflet valve including a plurality of leaflets. For example, the inlet valve 240 can be a tricuspid valve, or a bicuspid valve.

[0062] As shown in FIG. 2B, in some variations, the circulatory assist device 200 may be configured for placement at least partially in the left ventricle (LV) and / or the ascending aorta (AA). For example, in some variations, the pump body 220 can be placed across the native aortic valve (AV) such that a first portion of the pump body 220 (including some or all of the distal inflow region) is in the left ventricle, and a second portion of the pump is in the ascending aorta. In some variations, the pump body 220 can be placed such that the inlet is located in the left ventricle, below the plane of the aortic valve. In some variations, the pumpAttorney Docket No.: CDB.016WO body 220 can be placed such that the inlet is located in the aorta (e.g., ascending aorta) above the plane of the aortic valve, while a portion of the inflow region is in the left ventricle. Although the pump body 220 is shown in FIG. 2B as having approximately half of its length in the left ventricle and half of its length in the ascending aorta, it should be understood that placement of the pump body 220 may vary. For example, in some embodiments, some or all of the pump body 220 can be placed in the aorta (ascending aorta, aortic arch, and / or descending aorta).

[0063] As described above, the circulatory assist device 200 is characterized by axial flow between the inlet and the outlet of the conduit. In other words, in some variations, fluid pumped by the circulatory assist device 200 travels from the inlet to the outlet substantially entirely or predominantly axially along (e.g., aligned with) the flow axis of the conduit. In some variations, the fluid flow in the conduit has limited to no radial flow component, and / or limited to no circumferential flow component. The flow axis of the conduit may be substantially coincident with a longitudinal axis of the conduit, for example, though it should be understood that axial flow includes both flow of fluid coincident with the longitudinal axis and flow of fluid generally parallel to the longitudinal axis. The circulatory assist device 200 with axial flow may have a number of advantages. For example, because forces acting on the fluid within the pump body are generally oriented in the same direction, the fluid travels generally in a linear path (without a significant change in its principal flow or momentum direction) through the circulatory assist device 100 and experiences less turbulence compared to fluid that does experience a change in its principal flow or momentum direction, thereby resulting in less disturbance in components of the fluid itself (e.g., less hemolysis in blood pumped by the circulatory assist device 200). Additionally, since flow occurs all in the same general axial direction (e.g., with little to no radial flow component), the kinetic behavior of the pump body (e.g., expansion and contraction of the volume displacement member, such as inflation and deflation of a balloon) can be more streamlined and energy efficient. Furthermore, such generally axial flow may help the pump body (especially, for example, the inflow region) be less prone to obstruction, as in some variations, the inlet valve for the axial flow configuration may be generally oriented such that it is less likely to be blocked by cardiac wall tissue or other surrounding tissue. However, in some variations the circulatory assist device 200 may include one or more inlets configured to provide at least partially radial flow of blood into the pump body (e.g., one or more inlets arranged on a side wall of the conduit, to receive flow in aAttorney Docket No.: CDB.016WO direction orthogonal to the longitudinal axis of the conduit, or otherwise non-parallel to the longitudinal axis of the conduit).

[0064] FIGS. 3A-3E illustrate various phases of operation in which fluid may be allowed to exit the conduit of the pump body via maintained momentum during the expansion phase and at least a part of the contraction phase of a volume displacement member 230. Although the volume displacement member 230 is primarily shown and described below as a balloon, it should be understood that the same principles of operation apply with respect to other variations of circulatory assist devices that include different kinds of volume displacement members 230.

[0065] FIG. 3 A illustrates a pump body 220 that has received fluid (e.g., blood) through the inlet valve 240, and has a volume displacement member 230 being inflated to expand within the pump body 220. As the volume displacement member 230 inflates, it displaces surrounding fluid, thereby pushing fluid both distally toward the inflow region 220a and proximally toward the outflow region 220c. Fluidic pressure causes the inlet valve 240 to close, while also urging fluid to exit the pump body 220. As shown in FIG. 3B, when the inlet valve 240 is fully closed, some or all of the fluid volume in the pump body 120 exits through the outlet of the outflow region 220c.

[0066] Inflation of the volume displacement member 230 also helps generate momentum of the fluid column traveling toward the outflow region 220c in the pump body 220. FIG. 3C illustrates when the volume displacement member 230 is at an end portion of the expansion phase, and the volume displacement member 230 is inflated to a maximum volume. At this stage of operation, the fluid mass in the pump body 220 has momentum toward the outflow region 220c to exit the pump body 220 through the outlet, and such movement of the fluid mass results in a negative pressure within the pump body 220. Under such momentum and negative pressure within the pump body 220, the inlet valve 240 opens and additional fluid is pulled into the pump body 220 through the open inlet valve 240 in the axial flow direction, as shown in FIG. 3C.

[0067] As shown in FIG. 3D, when the volume displacement member 230 enters its contraction phase and begins to deflate, the fluid momentum continues, and additional fluid is pulled into the pump body 220 in the axial flow direction through the open inlet valve 240. In some instances, the amount of fluid momentum may decrease at this stage if additional fluid is also pulled into the pump body 220 through the outflow region 220c. However, in theseAttorney Docket No.: CDB.016WO instances, the momentum (and volume) of fluid pulled through the inflow region 220a is greater than that of fluid pulled distally through the outflow region 220c. Accordingly, fluid momentum may slow, but still continues in the direction from the inflow region 220a toward the outflow region 220c, thereby drawing in additional fluid into the pump body 220 for further pumping.

[0068] FIG. 3E illustrates when the volume displacement member 230 is at an end portion of the contraction phase, and the volume displacement member 230 is deflated to a minimum volume. At this stage of operation, the fluid mass continues to have momentum in the proximal direction toward the outflow region 220c, and fluid continues to exit the pump body 220 through the outlet of the conduit. Following the contraction phase, the volume displacement member 230 returns to its expansion phase, and the above-described cycle of expansion and contraction (with continued momentum and fluid conveyance through the conduit outlet, as shown in FIGS. 3A-3E) may repeat. Further details regarding axial flow in the circulatory assist device 200 are described in International Patent Application No. PCT / IB2024 / 057381, which was incorporated by reference above.

[0069] Other aspects of the present technology may have additional benefits. For example, the pump body 220 can have an elongated shape that is well-suited for axial flow, which can be advantageous because increased length of the pump body 220 provides a longer landing zone that can be placed within and against leaflets of a valve (e.g., native leaflets of an aortic valve between the left ventricle and the ascending aorta). Accordingly, an elongated circulatory assist device 200 can be delivered to a transvalvular position with greater ease, as less precision is required for the circulatory assist device 200 to be placed in a suitable position across a valve (e.g., aortic valve).

[0070] Although FIGS. 2A-3E show a particular example of a circulatory assist device, it should be understood that the driver systems and methods described herein can additionally or alternatively be used to drive the operation of other circulatory assist devices with volume displacement members (e.g., balloons). For example, the driver systems and methods in accordance with the present technology can be operated with other circulatory assist devices such as those described in U.S. Patent Application No. 18 / 300,207 filed April 13, 2023, U.S. Patent Application No. 18 / 500,906 filed November 2, 2023, International Patent Application No. PCT / EP2023 / 059293 filed April 6, 2023, International Patent Application No. PCT / EP2023 / 080613 filed November 2, 2023, International Patent Application No. PCT / IB2024 / 057381, International Patent Application No. PCT / IB2024 / 060293 filed OctoberAttorney Docket No.: CDB.016WO19, 2024, and International Patent Application No. PCT / IB2024 / 058253 filed August 24, 2024, each of which is incorporated herein in its entirety by reference.III. Chamber

[0071] As described above, the driver system 100 can include a driver chamber 110 having an operating chamber volume that is fillable with an inflation fluid for inflating a balloon (or other volume displacement member) in a circulatory assist device. The volume of the operating chamber can be changed, i.e., increased and / or decreased. The operating chamber volume can be compressible and decompressible, such as through the operation of the driving mechanism 120. When the volume of the operating chamber volume is decreased (e.g., by compression) to a low volume state, a displacement volume of the inflation fluid in the operating chamber volume moves through the fluid flow line 150 in a first (e.g., distal) direction to cause inflation of the balloon (or expansion of an expandable chamber of the volume displacement member) of the circulatory assist device. Generally, the balloon inflation occurs when the pressure inside of the balloon (Pbaiioon) is greater than the pressure in the conduit (Pconduit) in the pump body outside of the balloon. When the operating chamber volume is increased (e.g., decompressed or expanded) to a high volume state, the inflation fluid in the balloon moves in a second (e.g., proximal) direction to cause deflation of the balloon (or contraction of the expandable chamber of the volume displacement device) of the circulatory assist device. Generally, the balloon deflation occurs when Pbaiioon is lower than the Pconduit.

[0072] Generally, when the volume displacement member is being expanded, the driver chamber 110 may be configured to transfer a certain (e.g., predetermined) amount of inflation fluid (e.g., helium) through the fluid flow line into the expandable chamber of the volume displacement member in the circulatory assist device (e.g., into the balloon of the circulatory assist device), where this amount of inflation fluid may be determined at least in part by the desired maximum volume of the expandable chamber and the desired pressure of the expandable chamber when the volume displacement member is in the fully pressured configuration (e.g., based on the ideal gas law). The driver chamber 110 may be further configured to remove the same amount of inflation fluid from the expandable chamber of the volume displacement member when the volume displacement member is being contracted. This dynamic mass transfer (i.e., transfer of mass of the inflation fluid) may be accomplished by the driver system 100 at a desired certain driving frequency, by operating the driver system 100 to create a certain pressure differential over the fluid flow line into the volume displacement member. For example, the driver chamber 110 is operated such that the volumeAttorney Docket No.: CDB.016WO displacement of inflation fluid in the driver chamber 110 is sufficiently large to sustain this pressure difference during the expansion and contraction of the volume displacement member (e.g., inflation and deflation of the balloon). In a thermodynamic concept, for example, the driving chamber 110 may be operated to perform an amount of work W given by W = f P*dv, where P is pressure, and dv is the chamber volume displacement.

[0073] In some variations, the driver chamber 110 is configured to reduce the dead volume of inflation fluid in the driver system; that is, the volume of inflation fluid that remains in the fluidic path but is not effective in the operation of the balloon or other volume displacement member. As an illustrative example in which the volume displacement member includes a balloon, the inflation of the balloon may involve the fluidic transfer of not just the inflated balloon volume, but also the volume in the fluidic path between the balloon and one or more components of the driver system 100 (e.g., fluid flow line 150 including extension tubing 152 and / or catheter 154), hub 130, operating chamber volume, etc.). Generally, fluid must fill this fluidic path between the balloon and such component(s) of the driver system 100 in order to result in inflation of the balloon, and be at least partially removed from such fluidic path in order to result in deflation of the balloon. For example, in some variations, to inflate a balloon having an inflated volume of 2 mL, the driver system is configured to fill the volume in the fluidic path including 4 mL of the catheter, 6 mL of the extension tubing, 1 mL of the hub, and 4 mL of the operating chamber volume. Any fluidic volume beyond this 17 mL that is transferred by the driver system 100 represents an inefficiency, increases operational requirements and / or demands on the driver system 100, and / or decreases the fluidic output of the driver system 100. The same principle applies in other examples with varying volumetric dimensions, such as where to inflate a balloon having an inflated volume of 2mL, the driver system is configured to fill the volume in the fluidic path including between about 6 mL-9mL of the catheter, between about 7mL-l ImL of the extension tubing, between about 2 mL-4 mL of the hub, and between about 3 mL-5 mL of the operating chamber volume.

[0074] For example, the dead volume may be reduced at least in part by minimizing the path length of the fluid flow (e.g., among the driver chamber 110, the hub 130, the extension line 152, and / or the catheter 154). Reducing the amount of dead volume can be advantageous for improving the efficiency of operation of the driver system. In some variations, the dead volume is no greater than up to about 10 mL, about 6 mL, or about 4 mL within the driver chamber 110 (e.g., between about 1 and 5 times, between about 1 and 3 times, or between about 1 and 2 times the volume of the volume displacement member when expanded) (e.g., asAttorney Docket No.: CDB.016WO measured up to an outlet of the driver chamber 110 leading to the hub or fluid flow line). FIG. 11 summarizes additional specifications for an example chamber 110, and in some variations, the driver chamber 110 can be configured to satisfy one or more of the specifications outlined in FIG. 11.

[0075] Furthermore, in some variations, the driver chamber 110 is configured to have reduced leakage of inflation fluid from the driver chamber 110 (e.g., from the operating chamber volume 112), or at least reduced impact of leakage of inflation fluid from the driver chamber 110. This can be accomplished, for example, at least in part by structuring the driver chamber 110 in fluidic communication with a secondary volume 114 as shown in FIG. 1, such as by structuring the driver chamber 110 as an enclosed system where the operating chamber volume 112 is further surrounded by a secondary volume, or by coupling a reservoir with the secondary volume (e.g., bladder reservoir, bellows-operated reservoir, etc.) to the backside of the driving chamber 110 (e.g., portion of the driving chamber 110 not including the operating chamber volume 112). The secondary volume can be filled with a fluid having identical properties as the inflation fluid (e.g., can be the same type of fluid as the inflation fluid) in the operating chamber volume 112. Accordingly, any leakage of inflation fluid from inside the driver chamber 110 to outside the driver chamber 110 can be offset or equalized by similar transfer of fluid from outside the driver chamber 110 to inside the driver chamber 110. Additionally or alternatively, the controller 160 can be configured to control one or more valves (e.g., valve 132) to actively introduce supplemental inflation fluid from a fluid reservoir 140 into the path of fluid flow (e.g., into the operating chamber volume 112, into the hub 130, into the extension line 152, and / or into the catheter 154) to compensate for leakage of inflation fluid out of the operating chamber volume 112 and / or elsewhere in the fluidic system. In some variations, such one or more valves may be present on the hub 130, or in the fluidic flow path between the hub 130 and the reservoir 140 (or other supplemental reservoir of inflation fluid). Such valves may additionally or alternatively be used to refresh (e.g., replace) the inflation fluid within the operating chamber volume 112. For example, in some variations, the driver can be configured to refresh the inflation fluid by first (i) opening a valve (e.g., a three-way valve) located in the fluidic path and minimizing the operating chamber volume 112 (e.g., through compression) to flush the inflation fluid within the operating chamber volume out of the fluidic circuit (e.g., into a reservoir or the outside), and then (ii) with the valve closed, transferring inflation fluid from the fluid source 140 into the operating chamber volume 112, such as by increasing the operating chamber volume to its maximum volume (e.g., throughAttorney Docket No.: CDB.016WO decompression). In some variations, this process may be cyclically repeated a few times to purge and refresh the inflation fluid. Reducing the leakage of inflation fluid and / or reducing the impact of such leakage can be advantageous, for example, to help maintain expected pressure within the path of fluid flow, thereby maintaining efficient operation and avoiding inadvertent or unintentional underinflation of the balloon of the circulatory assist device. The system may further be configured with one or more sensors to sense any loss of inflation fluid, e.g., by sensing a pressure reduction in the fluid circuit, and automatically opening a valve at a predetermined threshold to inject more inflation fluid into the operating chamber.

[0076] In some variations, the driver chamber 110 can include a housing and a movable divider (e.g., piston, partition, membrane, etc.), wherein the operating chamber volume is on a first side of the movable divider, and a backside chamber volume is on a second side of the movable divider that is opposite the first side. The movable divider can function as a dynamic chamber wall of the operating chamber volume, in that it can be translated and / or deformed (by movement of the driving mechanism) to cause a decrease and increase (e.g., by compression and decompression, respectively) of the operating chamber volume. The housing can include a rigid and substantially non-compliant outer chamber wall such that the motion and / or displacement of the driving mechanism is translated into compression of the operating chamber volume and hence compression of the inflation fluid held therein. In some variations, as shown in FIG. 1, the driver chamber 110 can include a sensor arrangement 172 including one or more sensors for monitoring one or more properties (e.g., temperature, pressure, position of a piston or other divider) of the driver chamber 110. Various examples of the driver chamber, including aspects of example housings and movable dividers, are further described below.

[0077] When operated, the driver system can naturally become warmer due to operating components, which may affect the fluidic properties of the inflation fluid and affect the accuracy and precision with which the flow of inflation fluid can be controlled, thereby affecting the pumping efficiency. To address this issue, in some variations, the driver chamber 110 (and / or other components of the driver system, such as the hub 130) can include a temperature modulation system (e.g., cooling and / or heating system) configured to help control temperature of the driver chamber 110 (and / or other portions of the driver system). In some variations, the temperature modulation system can include one or more heat exchangers, such as one or more passive cooling elements (e.g., through convection cooling) and / or one or more active cooling elements. Cooling elements can include, for example, one or more channels or enclosures that are adjacent (e.g., in contact with) a surface of the driver chamber 110 andAttorney Docket No.: CDB.016WO configured to hold a cooling medium (e.g., fluid) with a high specific heat capacity (e.g., water, other suitable fluid). Thus, the cooling medium can help stabilize and substantially maintain the temperature of the driver system, particularly when the driver system is being operated (e.g., during filling and / or emptying of the driver chamber 110, during cyclical operation of expansion and contraction of the operating chamber volume, etc.). Similarly, convection cooling may be accomplished with air or other suitable gas as a cooling medium, and such convection cooling may be enhanced with cooling fins on one or more components of the driver system (e.g., on or in the driver chamber 110, on the hub 130, etc.). In some variations, convective cooling may be enhanced with one or more fluid displacement mechanisms (e.g., fan, pump, etc.) to help circulate the cooling medium with positive displacement or negative displacement (e.g., vacuum). As such, in some variations the temperature modulation system can include one or more passive heat exchangers incorporating natural convection cooling and / or one or more active heat exchangers incorporating forced convection cooling. Another example of a cooling element is a Peltier module that is coupled to a surface of the driver chamber 110 and / or other component to be cooled. Further details of the control of a Peltier module, such as with the controller 160, are described in further detail herein. In some variations, the temperature modulation system can additionally or alternatively include at least one heat exchanger, such as a passive heat exchanger incorporating natural convection cooling and / or an active heat exchanger with forced convection cooling facilitated with one or more pumps fans, and / or the like. Additionally or alternatively, the temperature modulation system can include a heating system with one or more heating elements, such resistive heating elements. In some variations, the temperature modulation system may be feedback controlled to maintain the driver and / or the inflation fluid within a specific temperature range.

[0078] FIG. 25 is a schematic of an example temperature modulation arrangement 2500 for modulating temperature of a driver chamber 110 and / or hub 130, although other components (e.g., actuator for the driver chamber 110, etc.) of the driver system, while not explicitly shown in FIG. 25, can similarly be cooled and / or heated in a similar manner. As shown in FIG. 25, a cooling medium (e.g., air, water, etc.) can be introduced into a fluidic circuit through a cooling medium inlet 2510. The cooling medium can pass through a deaerator 2520 and then through a fluidic channel adjacent to the driver chamber 110 and / or hub 130. The cooling medium can circulate adjacent to an active cooling element 2530 (e.g., Peltier module) and / or through a suitable heat exchanger 2540 such as those described elsewhere herein. The controller 160 can control operation (e.g., speed, fluidic volumetric pump rate, etc.)Attorney Docket No.: CDB.016WO of a pump 2550 that continues to circulate the cooling medium in the fluidic circuit, such as based at least in part on sensor feedback from a thermocouple configured to measure temperature of the cooling medium as or after it passes through the active stage cooling 2530 and / or heat exchanger 2540.

[0079] For example, FIG. 4 is a schematic illustration of a chamber 410, which is an example of chamber 110. As shown in FIG. 4, the driver chamber 410 includes a housing 414 and a movable divider in the housing 414. The movable divider can include a plunger 424 coupled to a driving rod 422, where the driving rod 422 is operably coupled to a driving mechanism (not shown), such as any of those described in further detail herein. An operating chamber volume 412 can be located on a first side (e.g., distal side) of the plunger 424. The operating chamber volume 412 can be in fluidic communication with the fluid flow line (e.g., fluid flow line 150). For example, an outlet 414o of the operating chamber volume 412 can be in fluidic communication with the hub (e.g., hub 130), which in turn can be in fluidic communication with the fluid flow line for passing inflation fluid from the operating chamber volume 412 to the balloon of the circulatory assist device. Furthermore, the operating chamber volume may contain one or more pressure and / or temperature sensors. The output signals of these sensors may be used to control the actuation of the driving mechanism and its motion.

[0080] The housing 414 (or at least a portion thereof defining the operating chamber volume 412) can be substantially rigid, and include a non-compliant, rigid material such as metal (e.g., stainless steel). The plunger 424 can form a peripheral seal against the inner wall surface of the operating chamber volume 412, such that when the plunger 424 moves (e.g., translates) within the housing 414 to decrease and increase the operating chamber volume 412, the seal substantially prevents inflation fluid within the operating chamber volume 412 from exiting the operating chamber volume 412 via the interface between the plunger 424 and the inner wall surface of the operating chamber volume 412. Thus, the inflation fluid within the operating chamber volume 412 becomes pressurized and driven through the outlet 414o of the driver chamber 410. For example, a cross-sectional shape and size of the plunger 424 can be substantially similar to the inner wall surface of the operating chamber volume 412. Additionally or alternatively, the plunger 424 can include a seal 426 (e.g., gasket) coupled around a periphery of the plunger 424 that engages the inner wall surface of the operating chamber volume 412. In some variations, at least an inner wall surface of the housing (or at least the operating chamber volume 412) and / or the plunger 424 can have a circular crosssection, though the inner wall surface of the housing and / or the plunger 424 can have anyAttorney Docket No.: CDB.016WO suitable cross-sectional shape, such as elliptical, circular, triangular, rectangular, or any other suitable polygonal shape.

[0081] The driving rod 422 can be coupled to a driving mechanism to move (and cause movement of the plunger 424) in accordance with a stroke of the driving mechanism. For example, the driving rod 422 can move farther into the housing 414 to drive the plunger 424 to a first travel endpoint to cause a decrease (e.g., compression) of the operating chamber volume 412. Conversely, the driving 422 can move farther out of the housing 414 to drive the plunger 424 to a second travel endpoint to cause an increase (e.g., decompression) of the operating chamber volume 412. The distance between the first and second travel endpoints can correspond to (e.g., equal) the stroke length of the driving mechanism. Accordingly, with cyclical motion of the driving mechanism providing an output for the movement of the driving rod 422 and plunger 424, the driving mechanism can thereby cause cyclical decrease and increase of the operating chamber volume, which corresponds to cyclical inflation and deflation of the balloon, respectively. Although the driving rod 422 and plunger 424 are shown in FIG. 4 as configured generally move in a linear motion and in a proximal-distal direction, it should be understood that the driving rod 422 and plunger 424 can move in any suitable manner, such in a curved path. Additionally or alternatively, while the driving rod 422 and plunger 424 can be arranged generally in-line (e.g., axially aligned) with an outlet 414o of the housing 410 as shown in FIG. 4, in some variations the driving rod 422 and plunger 424 can be positioned offset (e.g., orthogonal, or at any suitable angle) relative to the an outlet of the housing 410, as long as movement of the driving rod 422 and plunger 424 is configured to drive decrease and / or increase of the operating chamber volume 412.

[0082] The driving rod 422 may be oriented relative to gravity in any suitable orientation. For example, in some variations, the driver system may be oriented in a vertical configuration in which the driving rod 422 moves vertically during its cyclical motion, which may in some instances help reduce power requirements and / or reduce vibrations within the driver system. As another example, the driver system may be oriented in a horizontal configuration in which the driving rod 422 moves horizontally during its cyclical motion. However, the driver system may be oriented at other suitable angles relative to gravity.

[0083] In some variations, the driver system can include one or more sensors configured to indicate the position, speed, force, power, and / or other aspect of motion of the driving rod 422 and / or plunger 424. For example, the driver chamber 410 can include one or more sensors (e.g., proximity sensors) configured to provide information regarding the positionAttorney Docket No.: CDB.016WO of the driving rod 422 and / or plunger 424. Additionally or alternatively, the driving rod 422 and / or plunger 424 can include an accelerometer configured to provide information regarding speed and / or acceleration of the driving rod 422. Additionally or alternatively the position, speed, force and power consumption can be derived from the power electronic stages utilized for the driving mechanism. Additionally or alternatively the position and speed can be derived from the sensor integrated withing the helium hub 130. Furthermore, the driving mechanism actuating the driving rod 422 can additionally or alternatively include a position sensor (e.g., encoder, proximity sensor, etc.) that can indicate the forward and / or backward position or motion of the driving rod 422 and / or plunger 424. Such sensor data regarding the position, speed, and / or other aspect of motion of the driving rod 422 and / or plunger 424 can be used to provide feedback control for actuating the driving rod 422.

[0084] The driver chamber 410 can further include a backside chamber volume 416 located on a second side (e.g., proximal side) of the plunger 424, opposite the operating chamber volume 412. The backside chamber volume 416 can be configured to become enlarged when the operating chamber volume 412 is decreased (e.g., compressed), and become smaller when then operating chamber volume 412 is increased (e.g., decompressed). In some variations, the backside chamber volume 416 can include one or more vents 418 that allow the backside chamber volume 412 to be an open system, in that the backside chamber volume 412 has an internal pressure substantially equal to the environment immediately outside the housing 414 (e.g., open to ambient air). The vents 418 allow this equalization of pressure, thereby making it easier for the driving rod 422 to move more freely within the driver chamber 410 (e.g., require less driving force). The vents 418 can, for example, include one or more holes in a back wall of the housing 414 as shown in FIG. 4, and / or on any suitable side of the backside chamber volume 416. In some variations, the driver chamber 410 can include multiple vents 418 arranged around the driving rod 422, such as in a radially symmetric manner (e.g., circumferentially equally distributed around the driving rod 422) or asymmetric manner. In some variations, the driver chamber can include one or more vents (e.g., vents 418) configured to additionally or alternatively vent to a reservoir of inflation fluid. Furthermore, in some variations, the backside chamber volume 416 can be coupled to a pump configured and controllable to alternately increase and decrease the pressure within the backside chamber volume 416 to assist the driving rod and plunger to decrease and increase, respectively, the operating chamber volume 412 (e.g., to reduce the driving force needed on the driving rod 422 to decrease and increase the operating chamber volume 412).Attorney Docket No.: CDB.016WO

[0085] Additionally or alternatively, the backside chamber volume may contain one or more pressure sensors and / or one or more temperature sensors. The output signals of these sensors may, for example, be used as an input for controlling the actuation of the driving mechanism and its motion.

[0086] In some variations, the portion of the housing 414 through which the driving rod 422 moves (e.g., a wall of the backside chamber volume 416, as shown in FIG. 4) can include one or more bearings 419, lubricant, and / or the like, to help reduce the friction between the driving rod 422 and the housing 414 as the driving rod 422 moves. The bearing(s) 419 can, for example, include a ball bearing, linear bearing, a magnetic bearing, a sleeve made of lubricious or low-friction material, etc.

[0087] In some variations, the driver chamber 410 can include a temperature modulation system 430. For example, similar to that described above, the temperature modulation system can include passive cooling elements and / or active cooling and / or heating elements. Passive cooling elements can include, for example, one or more channels or enclosures that are adjacent (e.g., in contact with) a surface of the driver chamber 410 and configured to hold a cooling fluid with a high specific heat capacity (e.g., water, other suitable fluid). Active cooling elements can include, for example, a Peltier module that is coupled to a surface of the driver chamber 410. Additionally or alternatively, the temperature modulation system can include heating elements, such as resistive heating elements.

[0088] Additionally or alternatively, in some variations, the movable divider can include a membrane that dynamically moves (e.g., deforms and / or translates) with compression and decompression of the operating chamber volume. For example, FIG. 5 is a schematic illustration of an example chamber 510, which is an example of chamber 110. The driver chamber 510 is similar to the driver chamber 410, except as described below. For example, like the driver chamber 410, the driver chamber 510 can include a housing 514 defining an operating chamber volume 512 that is fillable with an inflation fluid, and a backside chamber volume 516, similar to operating chamber volume 412 and backside chamber volume 416, respectively. Like driving rod 422, a driving rod 522 can be configured to pass through the backside chamber volume (e.g., with movement eased by a bearing 519, similar to bearing 419). Furthermore, in some variations, the backside chamber volume 516 can include one or more vents 518, similar to vents 418. However, instead of a plunger, the driver chamber 510 can include a movable divider including a flexible membrane 524 that is sealed (e.g., around its edges or its periphery) to an inner surface of the housing 414. The membrane 524 can beAttorney Docket No.: CDB.016WO coupled to the driving rod 522, such that movement of the driving rod 522 deforms the membrane 524 between a pressurizing configuration (e.g., corresponding to a distal travel endpoint of the driving rod 522) and a depressurizing configuration (e.g., corresponding to a proximal travel endpoint of the driving rod 522). When the membrane 524 is in the pressurizing configuration, the operating chamber volume 512 is compressed. For example, when in the pressurizing configuration, the membrane 524 can be convex relative to the driving rod 522 (e.g., bellowed out or curved toward the operating chamber volume 512 side of the driver chamber). In some variations, when in this pressurizing configuration, the membrane 524 may closely match the surface shape of (e.g., substantially conform to, contact, etc.) the adjacent internal surface of the driver chamber 510, thereby advantageously minimizing dead volume in the fluidic system. When the membrane 524 is in the depressurizing configuration, the operating chamber volume 512 is decompressed. For example, when in the depressurizing configuration, the membrane 524 can be concave relative to the driving rod 522 (e.g., bellowed in or curved toward the backside chamber volume 516 side of the driver chamber). As another example, the membrane may be configured to translate between a pressurizing configuration (e.g., pressurizing location corresponding to a distal travel endpoint of the driving rod 522) and a depressurizing configuration (e.g., depressurizing location corresponding to a proximal travel end point of the driving rod 522), where the membrane may have limited deformation across its surface.

[0089] The membrane can be made of any suitable material and / or have any suitable thickness that enables the membrane to be deformable yet sufficiently low-compliant and durable (e.g., fatigue-resistant through deformation cycles). In some variations, the membrane may have a durometer of at least about 70A, or at least about 90A. Examples of a suitable material include elastomers such as EPDM and suitable polyurethanes, though other membrane materials are contemplated in accordance with the present technology. For example, in some variations in which the membrane is configured to deform (e.g., flex between convex and concave configurations, stretch) while its outer edges are fixed to the housing, the material of the membrane may be more compliant and / or elastic. As another example, in some variations in which the membrane is configured to translate, the material of the membrane may be less compliant and / or elastic. In some examples, membrane 524 may be a resilient elastomer that can be deformed and / or stretched by translation of driving rod 522, and membrane 524 will resiliently return to its undeformed configuration, thus reducing the work required of driving rod 522. Membrane 524 may be mounted within the driver housing such that it is in the fullyAttorney Docket No.: CDB.016WO uncompressed configuration in its unbiased state (operating chamber volume 512 in its largest state), such that it is in the fully compressed configuration in its unbiased state (operating chamber volume 512 in its smallest state), or such that it is between the fully uncompressed and fully compressed positions in the unbiased state.

[0090] In some variations, the driving rod 522 can be coupled to the membrane 524 via one or more coupling discs 526. For example, the membrane can be arranged between (e.g., clamped by) a first coupling disc 526 adjacent to a first side of the membrane and a second coupling disc 526 adjacent to a second side of the membrane. The coupling discs 526 can be coupled to a distal end of the driving rod 522 with any suitable fasteners (e.g., with threaded interfaces, such as threaded interfaces on one or both coupling discs 526, or on a separate fastener such as a threaded nut). The one or more coupling discs 526 function to uniformly distribute the forces exerted on the membrane so as to stabilize it and improve the predictability of the membrane’s deformation in response to pressurization. Although the coupling discs 526 are described above as separate components, in some variations the driving rod 522 can additionally or alternatively include one or more coupling features that function in a similar manner as coupling discs 526 except that they are integrally formed (e.g., directly cast, overmolded, etc.) in the membrane. Furthermore, in some variations one or both coupling discs 526 may be encapsulated within the membrane 524. Furthermore, in some variations, the membrane 524 can include suitable reinforcement features (e.g., thicker and / or less compliant material coupled to or integrally formed within the membrane, such as with a composite membrane structure) around the region of the membrane that is coupled to the driving rod 522.

[0091] FIGS. 6A and 6B illustrate an example coupling disc arrangement with coupling discs 626, which are examples of coupling discs 526. The coupling disc arrangement includes a proximal mount 628a, distal mount 628b, and two coupling discs 626 configured for placement between the proximal mount 628a and the distal mount 628b. The proximal and distal mounts can be configured to provide structural support and / or fastening surfaces to assist with the coupling of the coupling discs 626 to the driving rod (e.g., driving rod 522). For example, in some variations the proximal and distal mounts can be rigid (e.g., formed of metal), while the coupling discs 626 can include a semi-rigid material (e.g., more rigid than the membrane material). The coupling discs 626 can include a semi-rigid material (e.g., foam, an elastomer, etc.) so as to conform to the membrane as it deforms, without causing damage to the membrane.Attorney Docket No.: CDB.016WO

[0092] Additionally or alternatively, the membrane can include a reinforced region where the membrane interacts with the driving rod 522 (e.g., a central region of the membrane 524), to similarly increase the predictability of the membrane deformation in response to pressurization. For example, the membrane 524 can be thicker in the reinforced region compared to more peripheral regions of the membrane 524, and / or can include one or more ribs or other reinforcement members to enhance stability of the reinforced region of the membrane 524.

[0093] In some variations, the membrane may be actuated between pressurizing and depressurizing configurations without a driving rod. For example, in some variations, one or more coupling discs may be coupled to the membrane and controlled via magnets. For example, as shown in FIG. 7A, a pair of coupling discs (including a proximal disc 526a on a first side of the membrane and a distal disc 526b on a second side of the membrane) may include a magnetic material and / or be coupled to a magnetic material (e.g., in a mount similar to mounts 628a, 628b). Movement of the discs 526a, 526b can be controlled by one or more electromagnetic actuators. For example, as shown in FIG. 7B, electromagnetic actuators 523ab, 523b may be polarized to urge the discs 526a, 526b to move the membrane 524 into a pressurizing configuration, by polarizing a proximal electromagnetic actuator 523a on a backside chamber volume side of the membrane to repel the proximal disc 526a and / or polarizing a distal electromagnetic actuator 523b on an operating chamber volume side of the membrane to attract the distal disc 526b. Conversely, as shown in FIG. 7C, the electromagnetic actuators 523a, 523b may be reverse polarized to urge the discs 526a, 526b to move the membrane 524 into a depressurizing configuration. By alternately and cyclically polarizing and reverse polarizing the electromagnetic actuators in this manner, the discs 526a, 526b may be caused to move the membrane 524 between the pressurizing and depressurizing configurations at a particular drive frequency.

[0094] The diameter of the coupling discs 526 (and / or the diameter of the reinforced region in the membrane) can affect the profile of the membrane 524 in its pressurizing configuration. In some variations, when the membrane 524 is in the pressurizing configuration, the membrane 524 can have a non-linear profile. For example, as shown in FIG. 5, the membrane 524 in the pressurizing configuration can have an outwardly curved or bell-shaped profile 524', such that the membrane surface approaches a wall of the housing 514, thereby reducing dead volume. In some variations the deflecting portions of the membrane 524 in its pressurizing configuration do not physically contact the wall of the housing 514 (e.g., theAttorney Docket No.: CDB.016WO membrane 524 does not “bottom out” against the housing 514 during its cyclical deformation). In some variations, an inner surface of the housing 514 (e.g., surface(s) closest to the membrane 524 when the membrane 524 is in its fully positive or negative pressurizing configurations) may include a soft, compliant material (e.g., polymer, foam, etc.), which may allow the membrane 524 to “bottom out” while reducing wear and tear on the membrane 524. Furthermore, in some variations, the bell-shaped membrane profile can be configured to help facilitate smooth membrane motion to reduce or eliminate turbulence in the inflation fluid flow.

[0095] In general, the bell-shaped membrane profile can depend at least in part on the surface area contact between the membrane and the coupling discs, the diameter of the driver chamber, and / or the membrane material itself (e.g., type, thickness, etc.). For example, in some variations, to minimize the dead volume when the volume displacement member is in its expanded state (e.g., inflated balloon), the internal surface of the driver chamber can be shaped to maximize as much as possible the surface area of contact between the membrane and the internal surface of the operating chamber volume when the membrane is in its pressurizing configuration. In other words, by maximizing the surface area of contact between the membrane and the inner wall of the operating chamber volume when the membrane is in its pressurizing configuration, the percentage of inflation fluid that remains in the operating chamber volume at this phase in the drive cycle is minimized, thereby reducing dead volume. The operating chamber volume geometry is at least in part based on the geometry of the coupling discs, the diameter of the driver chamber, and the material characteristics and / or thickness of the membrane. Additionally, the internal surface of the operating chamber volume can include texturing (e.g., one or more pressure equalization grooves) configured to help the internal surface of the operating chamber volume release the membrane more effectively when expansion of the operator chamber volume (and accompanying contraction of the volume displacement member) is to be commenced, thereby improving efficiency of the driver system.

[0096] FIGS. 8A and 8B illustrate an example chamber 810, which is similar to chamber 510 and chamber 110. FIG. 8 A illustrates a cutaway perspective view of the driver chamber 810, including a cylindrical housing 814, a driving rod 822, and coupling discs 826 configured to clamp a membrane (not shown in FIG. 8A) therebetween. Like in the driver chamber 510, the membrane can be sealed (e.g., around its edges or its periphery) to an inner surface of the housing 814, and divide the housing 414 to define at least an operating chamber volume 812 and a backside chamber volume 816. The driving rod 822 can extend generally along a central axis of the housing 814, and can be actuated by a driving mechanism (notAttorney Docket No.: CDB.016WO shown) to translate through a backside wall of the housing 814 according to a stroke length of the driving mechanism. Such movement through the housing wall can, in some variations, have reduced friction with a bearing 819 (e.g., similar to bearing 519).

[0097] In some variations, the driver chamber can include a movable divider including a membrane configured in different manners. For example, FIGS. 9A and 9B are schematic illustrations of an example chamber 910, which is an example of chamber 110. Chamber 910 can include a housing 914 and a movable divider including a plunger 926 and a membrane 924. In some variations, the plunger 926 can be similar to the plunger 424 described herein with respect to FIG. 4, except a periphery of the plunger 926 can be coupled to the membrane 924 functioning as a “rolling” membrane. For example, the membrane 924 can include an inner edge (e.g., inner circumferential edge) that is coupled to the periphery of the plunger 926, and an outer edge (e.g., outer circumferential edge) that is coupled to an internal surface of the housing 914. In other words, the membrane 924 can form a skirt seal around the plunger 926. The membrane 924 can be coupled to the plunger 926 by clamping, with adhesive, thermal bonding or welding, and / or in any suitable manner. The membrane 924 can function as a dynamic, deformable peripheral seal (e.g., skirt seal) between the plunger 926 and the housing 914. Like the membrane 524, the membrane 924 can be made of any suitable material and / or have any suitable thickness that enables the membrane to be sufficiently low-compliant and durable (e.g., fatigue-resistant through deformation cycles). An example of a suitable material is an elastomer such as EPDM 70A, though other membrane materials are contemplated in accordance with the present technology.

[0098] The driver chamber 910 can include an operating chamber volume 912 fillable with an inflation fluid, and a backside chamber volume 916, where the operating chamber volume 912 is on a first side (e.g., distal side) of the plunger 926 and membrane 924, and the backside chamber volume 916 is on a second side (e.g., proximal side) of the plunger 926 and membrane 924 opposite the first side.

[0099] The plunger 926 can be coupled to a driving rod 922 (which can be actuated by a driving mechanism), such that movement of the driving rod 922 causes movement of the plunger 926 and / or deformation of the membrane 924. Endpoints of a stroke of the driving mechanism that actuates the driving rod 922 can correspond to the movable divider (e.g., plunger 926 and membrane 924) being in a pressurizing configuration (e.g., corresponding to a distal travel endpoint of the driving rod 922) and a depressurizing configuration (e.g., corresponding to a proximal travel endpoint of the driving rod 922). FIG. 9A illustrates anAttorney Docket No.: CDB.016WO example of the driver chamber 910 when the movable divider is in the pressurizing configuration and the operating chamber volume 912 is compressed, and FIG. 9B illustrates an example of the driver chamber 910 when the movable divider is in the depressurizing configuration and the operating chamber volume 912 is decompressed. As shown in FIGS. 9A and 9B, in some variations, the inner and outer edges of the membrane 924 are farther apart when the membrane 924 is in the pressurizing configuration (e.g., placing the membrane 924 in tension when in the pressurizing configuration), compared to when the membrane 924 is in the depressurizing configuration. FIGS. 9E and 9F illustrate another example of the driver chamber 910 in the pressurizing configuration and the depressurizing configuration, respectively, in which the inner and outer edges of the membrane 924 are farther apart when the membrane 924 is in the depressurizing configuration (e.g., placing the membrane 924 in tension when in the depressurizing configuration), compared to when the membrane 924 is in the pressurizing configuration. The membrane 924 can be configured to remain a generally fixed dimension between the inner and outer edges and to roll or fold as the movable divider moves between these pressurizing and depressurizing configurations, which can advantageously facilitate plunger movement with low friction and increased durability. In some variations, the plunger 926 can be controlled (e.g., with controller 160) with dynamic braking at one or both endpoints of a stroke in the cycle (e.g., when moving the membrane 924 toward the pressurizing configuration and / or when moving the membrane 924 toward the depressurizing configuration), where the dynamic braking can be tuned to reduce sudden impact on the membrane 924 when transitioning between the pressurizing and depressurizing configurations, which may reduce wear and tear on the membrane 924.

[0100] In some variations, as shown in FIGS. 9C and 9D, the membrane 924 stretches, elongates, and / or deforms rather than roll, fold, or invert when moving between the pressurizing configuration (e.g., shown in FIG. 9C) and depressurizing configuration (e.g., shown in FIG. 9D). In other words, while dynamically deforming in accordance with movement of the driving rod 922, the inner edge of the membrane 924 can always be oriented distally of the outer edge of the membrane 924. In some variations, a predetermined pressure differential across the membrane 924 between the operating chamber volume 912 and the backside chamber volume 914 may be maintained. For example, in some variations a controller (such as controller 130), can be configured to administer and / or remove fluid via a port in the operating chamber volume 912) to modulate pressure within the operating chamber volume 912. As another example, the driving chamber 910 can additionally or alternatively be radiallyAttorney Docket No.: CDB.016WO compliant so as to maintain a substantially uniform pressure (or maintain pressure within an acceptable range) in the operating chamber volume 912 and backside chamber volume 916, independent of position of the plunger 926. This pressure differential across the membrane 924 can help maintain appropriate tension in the membrane 924 as the membrane 924 moves between the pressurizing and depressurizing configurations, thereby helping to maintain predictability and / or control of the membrane, and hence the predictability and / or control of how the operating chamber volume 912 is pressurized and depressurized. However, in some variations it may be advantageous or desirable to control the operating chamber volume 912 as underpressurized relative to the backside chamber volume 916, such as depending on the operational mechanics of the volume displacement member.

[0101] FIGS. 10A and 10B are schematic illustrations of an example chamber 1010 (which is an example of chamber 110) with a movable divider including a membrane. As shown in FIGS. 10A and 10B, the driver chamber 1010 can include a housing 1014 and a movable divider including a plunger 1026 and a membrane 1024. In some variations, the plunger 1026 and membrane 1024 can be similar to the plunger 926 and membrane 924 described herein, except that the membrane 1024 can form a bladder configured to form a circumferential seal against an internal surface of the housing. The bladder can include a bladder volume that is fillable with a fluid such that the bladder is pressurized. The pressurized bladder can be configured to move with the plunger 1026 between a pressurizing configuration (e.g., as shown in FIG. 10A) and a depressurizing configuration (e.g., as shown in FIG. 10B). The fluid filling the bladder can be any suitable fluid for pressurizing the bladder, such as a gas or liquid. The pressure inside the bladder can, in some variations, be greater than atmospheric pressure (or pressure immediately outside of the bladder) so as to substantially prevent atmospheric air from entering the backside chamber 1016. The fluid may be a compressible fluid such as air, helium, nitrogen or carbon dioxide, or an essentially incompressible fluid. For example, in some variations the bladder can be pressurized with water or oil.

[0102] The pressurization of the bladder helps make the movement of the membrane highly predictable and enhancing the circumferential seal with the inner surface of the driver chamber wall. Furthermore, in some variations the pressure within the bladder can be maintained at a sufficiently high level so as to substantially withstand cavitation (e.g., substantially prevent leakage of air from the backside chamber volume 1016, such as toward the operating chamber volume 1012) when the plunger 1026 and the membrane 1024 are moving to depressurize the operating chamber volume 1012 (e.g., move toward theAttorney Docket No.: CDB.016WO depressurizing configuration shown in FIG. 10B). For example, the fluid may include a liquid that has a low vapor pressure, and the pressure in the bladder can be maintained above the vapor pressure so as to reduce the likelihood of cavitation.

[0103] In some variations, driver chamber 110 itself is configured to contract in size in order to compress its interior volume. For example, one or more walls of the driver housing may be configured to shorten and lengthen to compress and decompress the driver chamber. In some variations, the driver chamber 110 can include a bellows configured to transition between a pressurizing configuration in which an operating chamber volume within the bellows is compressed, and a depressurizing configuration in which the operating chamber volume is decompressed. In some variations, driver chamber 110 is configured to contract in size in order to reduce the dead volume within the chamber. Conventional bellows systems, which are traditionally used to push and pull air through compression and expansion of the bellows, have a drawback in that they tend to have a higher dead volume, which especially in the application of driving a circulatory assist device at high frequencies will lead to undesirable pumping inefficiencies. Accordingly, in some variations of a bellows-type chamber 110 such as those described herein, the driver chamber 110 can include one or more features that contribute to reducing dead volume in the fluidic system, thereby improving the efficiency of the overall driver system. For example, in some variations, a bellows in the driver chamber 110 can include a filler material that functions to occupy at least a portion of volume within the bellows structure that otherwise would contribute to dead volume for the moving volume of inflation fluid from the driver chamber 110. Various specific examples of bellows-type chambers are described below, though it should be understood that in other variations, individual features of such examples can be combined in any suitable manner.

[0104] In general, a bellows-type chamber 110 (not shown in the figures) can include a first end (e.g., proximal end) that is coupled to a driving rod, and a second end (e.g., distal end) that is arranged opposite the first end, where the driving rod can be actuated in a cyclical manner in accordance with a stroke length to move the first and second ends closer together toward a pressurizing configuration, and farther apart toward a depressurizing configuration. The bellows can be flexible due to including a flexible material and / or including a structure that is configured to allow for change in distance between the first and second ends of the bellows. For example, the bellows can include a flexible material such as a suitable elastomer or polymer and / or a suitable metal (e.g., with the bellows formed into a sheet, membrane, etc.) with high fatigue resistance. Additionally or alternatively, the bellows can include pleats (e.g.,Attorney Docket No.: CDB.016WO with an accordion-like profile), sliding plates, etc. that structurally can accommodate change in length and hence change in the operating chamber volume as the bellows is actuated by the driving rod.

[0105] FIGS. 12A and 12B, for example, are cross-sectional schematic illustrations of an example chamber 1210 (which is an example of chamber 110) including a bellows 1214 that defines an operating chamber volume 1212 (labeled in FIG. 12B). The bellows 1214 can include a first bellows end 1214p (e.g., proximal end) coupled to a driving rod 1222, and a second bellows end 1214d (e.g., distal end). The first bellows end 1214p and the second bellows end 1214d are arranged on opposite sides of the bellows 1214, such that a forward and backward movement of the driving rod 1222 (coupled to the first bellows end 1214p) across its stroke causes the first bellows end 1214p and the second bellows end 1214d move closer to each other to a pressurizing configuration (e.g., as shown in FIG. 12A) and farther from the second bellows end 1214d to a depressurizing configuration (e.g., as shown in FIG. 12B).

[0106] The bellows 1214 can further include rounded hinge joints 1216 where flexing occurs during the bellows movement. For example, as FIGS. 12A and 12B illustrate a cross- sectional view of the driver chamber 1210, in some variations the hinge joints 1216 can collectively form at least one annular space (e.g., ring) around the operating chamber volume 1212. Although FIGS. 12A and 12B illustrates a bellows with a single such annular space, in some variations the driver chamber 1210 can include multiple pleats that are axially distributed along a direction parallel to the driving rod 1222, with multiple annular spaces formed by various sets of hinge joints 1216 at different axial locations. At least some of the hinge joints 1216 can be configured to maintain their rounded shape throughout the cycle of bellows movement, including when the bellows 1214 is substantially closed or in the pressurizing configuration. This can advantageously reduce stress and fatigue on the bellows material over repeated cycles, and / or can increase the radial strength of the bellows material. Additionally or alternatively, at least some of the hinge joints 1216 can include a filler material 1218, such that the space in the hinge joints 1216 do not contribute to the fluidic dead volume with respect to the inflation fluid that is moved by the driver system in and out of the driver chamber outlet 1210o to drive the circulatory assist system. The filler material 1218 can, for example, include silicone, TPU, and / or other suitable material, and can be injected, molded, and / or formed in any suitable manner and coupled to the bellows to be contained within at least some of the hinge joints 1216.Attorney Docket No.: CDB.016WO

[0107] FIGS. 13A and 13B are cross-sectional schematic illustrations of an example chamber 1310 (which is an example of chamber 110) including a bellows 1314 that defines an operating chamber volume 1312 (labeled in FIG. 13B). Similar to the bellows 1214, the bellows 1314 can include a first bellows end 1314p (e.g., proximal end) coupled to a driving rod 1322, and a second bellows end 1314d (e.g., distal end). The first bellows end 1314p and the second bellows end 1314d are arranged on opposite sides of the bellows 1314, such that a forward and backward movement of the driving rod 1322 (coupled to the first bellows end 1314p) across its stroke causes the first bellows end 1314p to move closer to the second bellows end 1314d to a pressurizing configuration (e.g., as shown in FIG. 13A) and farther from the second bellows end 1314d to a depressurizing configuration (e.g., as shown in FIG. 13B). The bellows 1314 can include a plurality of pleats configured in an accordion-like fashion, so as to facilitate cyclical collapse and extension as the bellows transitions between the pressurizing configuration and the depressurizing configuration.

[0108] The bellows 1314 can further include a filler material configured to occupy at least a portion of the operating chamber volume 1312 (or at least a portion of the interior volume of the bellows 1314) so as to occupy a space that would otherwise contribute to dead volume. Thus, such filler material can reduce the amount of dead volume present in the fluidic system. For example, as shown in FIG. 13A, a filler material 1318 can be sized and / or shaped to occupy at substantial portion of the interior of the bellows 1314 (e.g., a substantial portion of the operating chamber volume 1312) when the bellows 1314 is in the pressurizing configuration. In some variations, the filler material 1318 can, for example, occupy at least 50%, at least 75%, at least 80%, at least 90%, or at least 95% of the interior of the bellows 1314 (e.g., of the operating chamber volume 1312) when the bellows 1314 is in the pressurizing configuration. Like the filler material described above with respect to FIGS. 12A and 12B, the filler material 1318 can, for example, include silicone, TPU, and / or other suitable material. The filler material 1318 can be formed into a block or other suitable mass (e.g., through injection molding, etc.) and coupled to the driving rod 1322 (or a structure coupled to the driving rod 1322, such as a plate), such as with an overmolding process, fasteners, adhesives, etc. In some variations, the bellows 1314 can additionally or alternatively include a filler material arranged in at least some of the hinge joints of the pleats, similar to filler material 1218 in the hinge joints 1216 described with respect to FIGS. 12A and 12B.

[0109] In some variations in which the driver chamber 110 includes a bellows, the bellows can additionally or alternatively be actuated between the pressurizing configurationAttorney Docket No.: CDB.016WO and the depressurizing configuration with a magnetic actuator arrangement. For example, FIGS. 14A and 14B are cross-sectional schematic illustrations of a chamber 1410, which is an example of chamber 110. The driver chamber 1410 can be similar to the driver chamber 1210, except as described below. For example, the driver chamber 1410 can include a bellows 1414 that defines an operating chamber volume 1412 (labeled in FIG. 14B). The bellows 1414 can include a first bellows end 1414a (e.g., proximal end) and a second bellows end 1414b (e.g., distal end). The first bellows end 1414a and the second bellows end 1414b are arranged on opposite sides of the bellows 1414.[0110J However, the first and second bellows ends 1414a and 1414b can be configured to be actuated using an arrangement other than a driving rod. For example, as shown in FIGS. 14A and 14B, the first bellows end 1414a can be coupled to a first disc 1415a or other suitable support, and the second bellows end 1414b can be coupled to a second disc 1415b or other suitable support. One or both of discs 1415a and 1415b can include a magnetic material, so as to be movable by control of one or more nearby magnetic actuators (not shown). Accordingly, a magnetic actuator can be operated to cause the first and second discs 1415a and 1415b to move closer together and / or farther apart, which can cause the first bellows end 1414a to move closer to the second bellows end 1414b to a pressurizing configuration (e.g., as shown in FIG. 12A) and / or farther from the second bellows end 1414b to a depressurizing configuration (e.g., as shown in FIG. 14B). In some variations, the discs 1415a and 1415b may be removably coupled to the bellows ends 1414a and 1414b. For example, the bellows can be disposable (e.g., single-use or limited-use) and / or sterilizable to make the inner surface of the bellows sterile, and the discs 1415a and 1415b can be attached to the bellows ends 1414a and 1414b when the sterilized bellows is fitted to the driver system. oni] In some variations, the bellows 1414 can be biased toward either the pressurizing configuration or toward the depressurizing configuration, such as with one or more springs 1416 arranged at or near the hinge joint(s) of the bellows 1414. Additionally or alternatively, the springs 1416 can help relieve stress and / or fatigue on the hinge joints of the bellows.

[0112] For example, the bellows 1414 can be biased toward the pressurizing configuration due to the spring(s) 1416. In this example, a magnetic actuator can be selectively operated to urge the discs 1415a and 1415b apart in order to transition the bellows 1414 toward the depressurizing configuration (e.g., intermittently power an electromagnetic actuator to depressurize the bellows, such as periodically). Between points in time when the magneticAttorney Docket No.: CDB.016WO actuator does not urge the discs apart, the discs can passively return closer to each other to restore the bellows to the pressurizing configuration, via the spring(s) 1416. Conversely, as another example, the bellows 1414 can be biased toward the depressurizing configuration due to the spring(s) 1416. In this example, a magnetic actuator can be selectively operated to urge the discs 1415a and 1415b closer together in order to transition the bellows 1414 toward the pressurizing configuration (e.g., intermittently or periodically power an electromagnetic actuator to pressurize the bellows). Between points in time when the magnetic actuator does not urge the discs closer together, the discs can passively return farther apart from each other to restore the bellows to the depressurizing configuration. However, in some variations, the bellows 1414 can be controlled in both directions (e.g., toward both the pressurizing and depressurizing configurations) with one or more magnetic actuators.

[0113] In some variations, the driver chamber 1410 can additionally or alternatively include a filler material 1418 (e.g., similar to filler material 1218 or 1318) configured to occupy at least some space in the interior of the bellows 1414 that would otherwise contribute to dead volume in the fluid system. Additionally or alternatively, one or both of discs 1415a and 1415b can be actuated by a mechanical driver.

[0114] Although illustrative examples of the driver chamber 110 have been shown in the figures and described above, it should be understood that other variations of the driver chamber 110 within the scope of the present technology include any suitable combination of features of the examples described herein.IV. Driving mechanism

[0115] In some variations, the driver system can further include a driving mechanism 120 configured to actuate a driving rod (e.g., any of driving rods 422, 522, 822. 922, 1022, 1222, 1322) in a cyclical manner, thereby inducing pumping with the driver chamber 110. Although the motion specifications for the driving mechanism may vary depending on the application and / or stroke volume desired at any particular time, in general, in some variations the driving mechanism can be configured to actuate the driving rod at a frequency of between about 3 Hz (180 beats per minute) and about 50 Hz (3000 beats per minute), or between about 10 Hz (600 beats per minute) and about 30 Hz (1800 beats per minute), where each cycle includes travel in a first (e.g., distal) direction over a stroke length travel in a second (e.g., proximal) direction opposite the first direction over the stroke length. For example, the driving mechanism may be configured to actuate the driving rod over a stroke length (half a cycle) ofAttorney Docket No.: CDB.016WO at least about 1 mm (e.g., between about 1 mm and about 3 mm) in an amount of time between about 5 ms and about 50 ms, although the stroke length will vary according to the desired volume of inflation fluid to be displaced in each cycle and volume of the operating chamber.

[0116] The driving mechanism can, in some variations, be mounted in a fixture configured to resist reciprocal motion during stroke cycles of the driving mechanism. As such, the fixture can be configured to stabilize the overall driving mechanism (e.g., limiting axial movement of the driving mechanism itself such that the driving mechanism’s output is transferred in a forward displacement of the driving rod). For example, the fixture can include a suspension system. In some variations, the suspension can be active (e.g., include one or more controllable elements for countering reciprocal motion of the driving mechanism body) or passive. For example, the driving mechanism can be coupled to one or more springs configured to absorb energy as the driving mechanism is operated.[0.117] Additionally or alternatively, a fixture for the driving mechanism can include a temperature modulation system (e.g., similar to any of the temperature modulation systems described herein with respect to cooling and / or heating the driver chamber, such as temperature modulation system 430. For example, similar to that described above, the temperature modulation system can include passive cooling elements and / or active cooling elements. Passive cooling elements can include, for example, one or more channels or enclosures that are adjacent (e.g., in contact with) a surface of the fixture and configured to hold a cooling fluid with a high specific heat capacity (e.g., water, other suitable fluid). Active cooling elements can include, for example, a Peltier module that is coupled to a surface of the fixture. Additionally or alternatively, the fixture can include one or more heating elements, such as resistive heating elements. Further, the driving system may comprise a temperature sensor. The output signal of the temperature sensor may be used for feedback control of the temperature modulation system and / or the driving mechanism.

[0118] In some variations, the driving mechanism includes a linear actuator having a linear output coupled to the driving rod. For example, FIG. 15 is a schematic illustration of a slider 1530 that provides a linear output operably coupled to a chamber 1510. The slider can, for example, be moved in a linear manner using any suitable linear actuator, such as a voice coil, electromagnetic system, etc. As shown in FIG. 15, the slider 1530 can be coupled to a driving rod 1522 that is in turn coupled to a plunger 1524. As the slider 1530 moves distally, the driving rod 1522 and plunger 1524 are actuated distally (e.g., to a pressurizing configuration to drive inflation fluid distally toward the balloon of the circulatory assist device). Similarly,Attorney Docket No.: CDB.016WO as the slider 1530 moves proximally, the driving rod 1522 and plunger 1524 are actuated proximally (e.g., to a depressurizing configuration to drive inflation fluid proximally away from the balloon of the circulatory assist device).

[0119] Although FIG. 15 illustrates a variation in which decrease and increase of an operating chamber volume is achieved with one slider 1530, in some variations the increase and decrease can be achieved with multiple sliders operating with multiple driving chambers. For example, a first driving mechanism with a first slider 1530 can be configured to operate with a first driving chamber, and a second driving mechanism with a second slider 1530 can be configured to operate with a second driving chamber. The first and second driving mechanisms can operate synchronously but in opposite directions, such as their momentums cancel each other out, thereby counteracting motion, vibration and / or noise in the system and reducing the need of more complicated damping systems. Furthermore, in some variations, the operation of such opposing driving mechanisms may account for effects of gravity. For example, in some variations in which opposing first and second driving mechanisms are driving linear actuators horizontally, they may be operated in a substantially symmetric manner, or at least without compensating for effects of gravity, since gravity affects both driving mechanisms in an equal manner. As another example, in some variations in which opposing first and second driving mechanisms are driving linear actuators vertically or with a vertical vector component (e.g., where the linear actuators are driven along a path at an angle that is non-orthogonal relative to horizontal), one of the driving mechanisms may be controlled to work with gravity (e.g., during portions of the cycle where gravity supplements desired movement of a slider 1530) while the other driving mechanism may be controlled to work against gravity (e.g., during portions of the cycle where gravity opposes desired movement of a slider 1530).

[0120] In some variations, the driving mechanism includes an actuator in which rotational input is converted to a linear output coupled to the driving rod. For example, FIG. 16 is a schematic illustration of a driving mechanism having a rotary input 1630 and a connecting rod 1622 having a proximal end coupled to the rotary input 1630 and a distal end coupled to a chamber 1610. As shown in FIG. 16, the output 1622 can be coupled to a plunger 1624 (or to a driving rod). In some variations, the connecting rod 1622 can function as a driving rod. As the rotary input 1630 rotates (e.g., co degrees), it causes rotation of the proximal end of the connecting rod 1622 and simultaneous linear displacement of the distal end of the connecting rod 1622. The position of the distal end of the connecting rod 1622, and hence the position of the plunger 1624, at any given time during a rotational cycle of the rotary inputAttorney Docket No.: CDB.016WO1630 depends at least in part on the following factors: the length of the connecting rod (Li), the radial distance between the center of rotation of the rotary input 1630 and the location where the rotary input 1630 is connected to the connecting rod (L2), and the angles 0i and 02 shown in FIG. 16. The stroke length over which the plunger 1624 moves with each cycle also depends on these factors. Over a complete rotation of the rotary input 1630, the distal end of the connecting rod 1622 completes a cycle of distal and proximal movement of the plunger 1624.

[0121] In some variations, the stroke length of the driving mechanism (e.g., the plunger 1614) can be adjusted during operation of the driving mechanism, such as by varying one or more of the above factors. For example, an effective length of the connecting rod can be adjusted to control stroke length. FIG. 17 is a schematic illustration of an example of a driving mechanism 1700 having a rotational input that is converted to a linear output. The driving mechanism 1700 can include an input motor 1710, a cam 1720 coupled to the input motor 1710, a connection rod unit 1730 coupled to the cam 1720, and a piston 1740 coupled to the connection rod unit 1730 and functioning as a linear output.

[0122] The input motor 1710 can include any suitable rotary actuator (e.g., servomotor) that can be electronically controlled, such as with the controller 160. The input motor 1710 can include an output shaft that is coupled to an input side of the cam 1720, which functions to offset the rotation of a first end of the connection rod unit 1730 (e.g., such that the first end of the connection rod unit rotates around an axis laterally offset from the rotational axis of the input motor 1710). As shown in FIG. 17, for example, an input side of the cam 1720 is configured to rotate around the same axis of the rotational axis of the input motor 1710, and an output side of the cam 1720 is configured to revolve around the input side of the cam 1720.

[0123] As shown in greater detail in FIG. 18 A, the connection rod unit 1730 can include a connecting rod body 1734, an output disc 1732 configured to rotate within the connecting rod body 1734, and a pair of dynamic members 1736 having adjustable length. As labeled in FIG. 18B, the connecting rod body 1734 can include a rotatable input connection 1738 (including, e.g., abearing) configured to rotatably coupleto the output side of the cam 1720, and a rotatable piston connection 1739 (including, e.g., a bearing) configured to rotatably couple to the piston 1740. The connecting rod body 1734 can furthermore define a pair of slots 1735 that are aligned in a direction along the length of the connection rod unit 1730.

[0124] The output disc 1732 can have coupling points 1733 configured to engage the slots 1735 so as to move within the slots 1735 when the output disc 1732 rotates. Each dynamicAttorney Docket No.: CDB.016WO member 1736 can have variable length. For example, a dynamic member 1736 can include an inner sub-member arranged telescopically within an outer sub-member, such that the inner and outer sub-members are nested and can collapse and / or extend relative to one another to result in change in length of the overall dynamic member 1736. In other variations, the dynamic member 1736 can additionally or alternatively include elastic materials, and / or collapsible features (e.g., pleats) to facilitate change in length of the overall dynamic member 1736.

[0125] The dynamic members 1736 and the rotatable output disc 1732 can cooperate to help enable adjustment of the effective length of the connection rod unit 1734, and hence the adjustable stroke length of a driving mechanism including such a connection rod unit 1734. For example, as shown in FIG. 19A, in a first configuration, the effective length of the connection rod unit 1734 (that is, the distance between the input connection 1738 and the piston connection 1739 in the connecting rod body 1734) is a first length LI. As shown in FIG. 19B, when the output disc 1732 rotates (and the piston connection 1739 enables rotation of the piston relative to the output disc), the effective length of the connection rod unit 1734 is a second length L2 that is shorter than L 1. Depending on the direction of rotation of the output disc 1732, the dynamic members 1736a and 1736b move in opposition. For example, as shown in FIG. 19B, one of the dynamic members (dynamic member 1736a) is longer than the other dynamic member on the opposite side (dynamic member 1736b).

[0126] FIGS. 20 A and 20B illustrate an example of the change in effective length in operation of the connection rod unit 1730 in a driving mechanism 1700. In FIG. 20A, the connection rod unit 1730 is in a similar configuration as that shown in FIG. 19A, allowing for a first effective length of the connection rod unit 1734. In FIG. 20B, the length of the dynamic members 1736a are adjusted in opposition to cause rotation of the output disc 1732, leading to a configuration similar to that shown in FIG. 19B, in which the effective length of the connection rod unit 1730 is a second effective length shorter than the first effective length. Specifically, one of the dynamic members (dynamic member 1736b) is adjusted (e.g., actuated) to be longer than the other dynamic member on the opposite side (dynamic member 1736a), causing the rotation of the output disc 1732 and a reduction in the effective length of the connection rod unit 1730 (and hence, reduction in the stroke length of the driving mechanism 1700. Accordingly, a controller (e.g., controller 160) can be configured to control the stroke length of the driving mechanism 1700 for actuating the compression and decompression of the driver chamber 110 by controlling the relative lengths of the dynamic members 1736a and 1736b.Attorney Docket No.: CDB.016WO

[0127] FIG. 21 is a schematic illustration of another variation of a driving mechanism 2100 (which can be an example of driving mechanism 120). As shown in FIG. 21, the driving mechanism 2100 can include an input motor 2110 having a motor shaft 2112, and an output disc 2120 that is coupled to the motor shaft 2112 and oriented non-orthogonally to the rotational axis of the motor shaft 2112 (and / or the rotational axis of the output disc 2120). In other words, the output disc 2120 can be tilted with respect to the rotational axis of the motor shaft 2112 and / or the rotational axis of the output disc 2120. A driving rod 2122, which can be oriented substantially parallel to the rotational axis of the motor shaft 2112 and / or the rotational axis of the output disc 2120, can be coupled to peripheral portion of the output disc 2120 at a connection 2130, such as with welding, fasteners, and / or in any suitable manner.

[0128] The driving rod 2122 can be actuated in a linear direction when the output disc 2120 rotates. As the output disc 2120 rotates, it causes linear displacement of driving rod 2122 (and any plunger coupled to the driving rod 2122). The longitudinal position of the distal end of the driving rod 2122, and hence the position of any plunger coupled to the driver rod 2122, depends at least in part on the angle of tilt (0) of the output disc 2120 and the radial distance of the connection 2130 from the output disc’s center of rotation. Generally, the greater the angle of tilt 9 and the larger the radial distance defined above, the greater distance the driving rod 2122 is displaced per half-revolution of the output disc 2120. The position of the output disc 2120 after a half-revolution is shown, for example, in dashed line in FIG. 21. Over a complete rotation of the output disc 2120, the driving rod 2122 completes a cycle of distal and proximal movement. In some variations, the angle of tilt 9 is fixed, while in some variations the angle of tilt 9 can be adjusted (e.g., with a controller, such as controller 160), which can, for example, function to adjust the stroke length of the driving mechanism 2100. Additionally or alternatively, the radial distance between the connection 2130 and the output disc’s center of rotation can be fixed or adjustable, which can, for example, function to adjust the stroke length of the driving mechanism 2100.

[0129] In some variations, any of the driving mechanisms described herein with respect to actuating a driving rod can additionally or alternatively be configured to cyclically move other suitable portions of the driver system, such as magnets (e.g., for actuating disc 1415a and / or disc 1415b). Furthermore, it should be understood that the driving mechanisms shown and described with respect to FIGS. 15-21 are illustrative examples, and in other variations, aspects of these driving mechanisms can be combined in any suitable manner.Attorney Docket No.: CDB.016WOV. Hub and fluid reservoir

[0130] As described elsewhere herein, in some variations, the driver system 100 can further include a hub 130 configured to enable control of introduction of inflation fluid into the fluid flow line 150 (and / or the operating chamber volume 112), and / or removal of the inflation fluid from the fluid flow line 150 (and / or the operating chamber volume 112). In some variations, the hub 130 can be located fluidically in-line between the driver chamber 110 and the fluid flow line 150. For example, the hub 130 can include a first inlet configured to be fluidic communication with an outlet of the operating chamber volume 112, and an outlet configured to be in fluidic communication with the fluid flow line 150 (e.g., extension tubing 152, catheter 154, etc.). Furthermore, in some variations the hub 130 (and / or the hub inlet and / or hub outlet) may be enclosed in a fluidic reservoir (e.g., same fluid as the inflation fluid) to help prevent air ingress into the fluidic flow path at any fluidic connections to the hub 130. In some variations, one or more functions of the hub (e.g., controlling introduction of inflation fluid into the fluid flow line 150 and / or the operating chamber volume 112, controlling removal of the inflation fluid from the fluid flow line 150 and / or the operating chamber volume 112) may be incorporated into the driver chamber 110 (e.g., in a flange of a piston cylinder or other driving member of the driver chamber 110).

[0131] The hub 130 can further be in fluidic communication with a fluid reservoir 140 holding a supply of inflation fluid (e.g., helium) that can be transferred to and / or from the driver chamber 110, the fluid flow line 150, or both. For example, the hub 130 can include a second inlet configured to be in fluidic communication with the fluid reservoir 140, and the outlet of the fluid reservoir 140 can be in fluidic communication with both first and second inlets of the hub 130. Inflation fluid in and / or out of the hub 130 can be controlled with one or more valves, such as at least one valve 132 arranged between reservoir 140 and the hub 130. The valve 132 can be actuated to open and / or close to control flow of inflation fluid, such as by a controller (e.g., controller 160). In some variations, the valve 132 can be actively controlled to open and close by a controller in a selective manner, while in some variations the valve 132 can be biased toward a closed state and actively controlled to open in a selective manner.

[0132] In some variations, the hub 130 can further include one or more sensors configured to measure state of the inflation fluid flowing in the fluid flow line 150. For example, the hub 130 can include at least one sensor arrangement 134, which can include at least one pressure sensor and / or at least one temperature sensor configured to measure pressure and temperature of the inflation fluid, respectively. Alternatively or in addition, the sensorAttorney Docket No.: CDB.016WO arrangement may include a sensor (e.g. a spectral sensor) capable of monitoring the composition of the inflation fluid. Additionally or alternatively, the sensor arrangement may include at least one sensor (e.g., capacitance sensor, image sensor, etc.) configured to detect the presence and / or amount of blood in the inflation fluid. Furthermore, the sensor arrangement may include at least one sensor configured to provide information from which leakage of inflation fluid in the fluidic system may be determined (e.g., by measuring density of the inflation fluid). Information from the sensor arrangement 134 along with other sensor information (e.g., regarding volume of the operating chamber volume) can be communicated to the controller 160 for purposes of controlling (e.g., optimizing) the fluidic system, as described in further detail below.VI. Fluid flow line

[0133] The fluid flow line 150 functions to convey inflation fluid to and / or from the hub 130 (if present), the driver chamber 110, and / or the volume displacement member of the circulatory assist device. In some variations, as shown in in the schematic of FIG. 1, the fluid flow line 150 can include an extension tubing 152 and a pump catheter 154. In some variations, the fluid flow line 150 can omit a separate extension tubing 152 (e.g., the fluid flow line 150 can include a pump catheter 154). In some variations, the pump catheter 154 can include an integrated extension lumen that is in in fluidic communication with the hub 130 and circulatory assist device 10, in addition or as an alternative to a separate extension tubing 152. In some variations, the extension tubing 152 may be omitted from the fluid flow line 150 (e.g., fluid flow line 150 can include only the catheter 154), such as in instances where the driver system is located sufficiently near the patient, if the catheter 154 is sufficiently long to traverse the distance between the driver system and the patient, etc.

[0134] The extension tubing 152 can include a proximal portion coupled to the hub 130 and a distal portion coupled to the pump catheter 154. However, in some variations the extension tubing 152 can be omitted and the pump catheter 154 can be coupled to the hub 130. The extension tubing 152 can include a lumen that is in fluidic communication with both the hub 130 and the pump catheter 154, thereby functioning to convey inflation fluid to and / or from the hub 130 and the pump catheter 154. In some variations, the extension tubing 152 is configured to have a small amount of dead volume as possible, while avoiding excessive resistance of fluid flow therethrough. Generally, extension tubing 152 having a larger diameter can result in a greater amount of dead volume but lower fluidic resistance, while extension tubing 152 having a smaller diameter can result in a lower amount of dead volume but greaterAttorney Docket No.: CDB.016WO fluidic resistance. In some variations, the extension tubing can include medical grade tubing having a hydraulic diameter of between about 2mm and about 4 mm, with suitably high radial force (e.g., to help reduce loss of fluidic output) yet bendability (e.g., to help prevent kinking of the extension tubing). Furthermore, the length of the extension tubing 152 can vary from application to application (e.g., depending on the patient environment), though in some variations it may be desirable to have the extension tubing 152 as short as possible to enable the driver chamber 110 to be as close as possible to the patient (e.g., attached to the bedside), so as to reduce both the dead volume and the fluidic resistance. For example, in some variations the extension tubing can be less than about 3 meters, less than about 2 meters, less than about 1.5 meters, or less than about 1 meter in length. In some variations, the length of the extension tubing 152 can be variable (e.g., adjustable), such as by rolling or winding. For example, a variable length extension tubing 152 can be configured with a longer length for manipulation purposes of the fluid flow line such as while setting up the patient for a procedure, and then configured with a shorter length during operation of the driver system.

[0135] Other features of the fluid flow line can be configured to help reduce obstruction in flow and reduce fluidic resistance (e.g., smooth transition between the volume displacement member of the circulatory assist device 10 and the catheter 154, smooth transition between the catheter 154 and the extension tubing 152, smooth transitions between the fluid flow line and connections to the hub, driving chamber 110, and / or the like). Additionally or alternatively, gradual changes in diameter of the fluid flow line can be configured to help balance trade-offs between fluidic volume and fluidic resistance along various portions of the fluid flow line.[0.136] Generally, the pump catheter 154 can include a proximal portion configured to extend outside of the patient P (e.g., through an insertion site, such as at the femoral artery) and couple to a distal portion of the extension tubing 152. The pump catheter 154 can further include a distal portion coupled to the balloon (or other volume displacement member) of the circulatory assist device 10, with a lumen that is in fluidic communication with the balloon. For example, FIG. 2A illustrates a portion of an example catheter 210, which is an example of the pump catheter 154. The catheter 210 has a distal portion configured to be in fluidic communication with the balloon 230, such as in a manner similar to that described in further detail in U.S. Provisional Patent Application No. 63 / 591,900 (which was incorporated by reference above). In some variations, the proximal portion of the pump catheter 154 can be coupleable to the extension tubing 152 (e.g., with a fluidic connector), and in some of these variations can be releasably coupleable to the extension tubing 152. However, in someAttorney Docket No.: CDB.016WO variations the proximal portion of the pump catheter 154 can be integrally formed with the extension tubing 152.

[0137] In some variations, the extension tubing 152 may have a length of between about 300 mm and about 3500 mm, and / or the catheter 154 may have a length of between about 600 mm and about 2000 mm. In some variations, the combined length of the extension tubing 152 and catheter 154 may be between about 800 nm and about 6000, between about 1000 mm and about 5000 mm, or between about 1500 and about 3000 mm. In some variations, the extension tubing 152 may have an adjustable length. For example, the extension tubing 152 may be lengthened to make it easier to manipulate or otherwise handle (e.g., when setting up for a cardiac assist procedure), then shortened to reduce the operational fluid path length as needed, such as during the cardiac assist procedure after setup. For example, as shown in FIGS. 23 A and 23B, in some variations the extension tubing 152 may include two or more discrete telescopic segments (e.g., segments 152a and 152b) extending between the hub 130 and a catheter hub 153 connecting the extension tubing 152 and the catheter. In these variations, at least some of the segments may slidably nest to facilitate extension (FIG. 23 A) and contraction (FIG. 23B); for example, a variation with two segments 152a and 152b of approximately equal length may be extended to facilitate an extension line having a length of 2L as shown in FIG. 23 A, and the segment 152b may be nested within segment 152a to facilitate an extension line having a length of L as shown in FIG. 23B. Although extension tubing 152 is shown in the figures as including two segments of approximately equal length, it should be understood that in other variations, the extension tubing 152 can include any suitable number of segments (three, four, five or more, etc.) that are equal or unequal in length. Additionally or alternatively, as another example, the length of extension tubing 152 may be adjustable as a result of forming at least a portion of the extension tubing 152 as a coil that can extend and compress in longitudinal length, and / or as a result of at least a portion of the extension tubing 152 including a material with a suitable amount of stretch (e.g., lengthens under tension). Additionally or alternatively, the extension tubing 152 can be cut to a suitable desired length.

[0138] As another example, as shown in FIGS. 24A and 24B, in some variations the extension tubing 152 may include two or more segments (portions of tubing) (e.g., 152a and 152b) extending between the hub 130 and a catheter hub 153 connecting the extension tubing 152 and the catheter. In these variations, the extension tubing 152 may be flexible and foldable and / or invertible to facilitate extension (FIG. 24A) and contraction (FIG. 24B). For example, the extension tubing 152 may unfold to facilitate extension (FIG. 24A) and fold and / or invertAttorney Docket No.: CDB.016WO to facilitate contraction (FIG. 24B). As another example, the extension tubing 152 may include pleats that enable extension and contraction in an accordion-style, and / or include stretchable material. Although extension tubing 152 is shown in the figures as including two segments of approximately equal length, it should be understood that in other variations, the extension tubing 152 can include any suitable number of segments (three, four, five or more, etc.) that are equal or unequal in length.

[0139] Additionally or alternatively, in some variations the effective or hydraulic diameter of the lumen of the extension tubing 152 may be between about 2.0 mm and about 4.0 mm, and / or the effective or hydraulic diameter of the lumen of the catheter 154 may be between about 1.8 mm and about 3.0 mm, or between about 2.0 mm and about 2.22 mm. Generally, larger effective or hydraulic diameter generally means less impedance for fluid movement through the fluid flow line. Further examples of dimensions and performance characteristics for the extension tubing and the catheter are shown in FIG. 11 A.

[0140] Additionally or alternatively, in some variations the pressure resistance in the lumen of the fluid flow line (e.g., including the extension tubing 152 and catheter 154) that the driving system must be configured to overcome when driving fluid to and / or from the volume displacement member may be no greater than about 1500 mbar and no less than about -600 mb ar.VII. Controller

[0141] As described herein, the driver system can include a controller 160 configured to control aspects of the driver system in view of desired inflation and deflation of the balloon in the circulatory assist device. For example, the controller 160 can be configured to control operation of the driving mechanism 120 (e.g., speed, stroke length, driving frequency, etc.), control of the volume of the operating chamber, control of the rate of change of the operating chamber volume, control of fluidic pressure in the system, control of temperature within the system, control of dead volume within the system, and / or control of compliance of the driver chamber during operation.

[0142] The controller can include at least one processor 162 and at least one memory device 164. The processor 162 can be configured to execute instructions that are stored in the memory device 164 such that, when it executes the instructions, the processor 162 performs aspects of the methods described herein, such as for controlling operation of the driving mechanism, control of the operating chamber volume, control of fluidic pressure in the system,Attorney Docket No.: CDB.016WO control of temperature within the system, control of dead volume, control of compliance of the driver chamber during operation, etc. The instructions may be executed by computerexecutable components integrated with a software application, applet, host, server, network, website, communication service, communication interface, hardware, firmware, software elements of a user computer or mobile device, smartphone, or any suitable combination thereof. In some variations, the one or more processors 162 can be incorporated into a computing device or system such as a cloud-based computer system, a mainframe computer system, a gridcomputer system, or other suitable computer system.

[0143] Furthermore, the memory device 164 can include program code including instructions executable by the one or more processors 162. The program code can be stored on any type of computer-readable medium, such as a storage device including a disk or hard drive. Computer-readable media containing code, or portions of code, can include any appropriate media known in the art, such as non-transitory computer-readable storage media. Computer- readable media can include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage and / or transmission of information, including, but not limited to, random-access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory, or other memory technology; compact disc read-only memory (CD-ROM), digital video disc (DVD), or other optical storage; magnetic cassettes, magnetic tape, magnetic disk storage, or other magnetic storage devices; solid state drives (SSD) or other solid state storage devices; or any other medium which can be used to store the desired information and which can be accessed by a system device.

[0144] In some variations, to control operation of the driving mechanism 120, the controller 160 can be configured to adjust the speed of the driving mechanism 120, the stroke length of the driving mechanism 120, and / or the driving frequency of the driving mechanism 120, so as to achieve a desired volumetric flow through the fluid flow line and / or frequency of directional change of fluid flow through the fluid flow line. The type of adjustments to the driving mechanism 120 may depend on the exact nature of the driving mechanism 120, and specific examples of the same are described elsewhere herein. For example, as described in further detail above, the stroke length of a driving mechanism similar to driving mechanism 1700 described above with respect to FIGS. 17-20B can be adjusted by controlling the effective length of the connecting rod unit 1730 (e.g., by adjusting the length of one or more dynamic members 1736). As another example, driving frequency of the driving mechanism 120 can beAttorney Docket No.: CDB.016WO adjusted by controlling the rotational rate of an input motor of the driving mechanism (e.g., rotary input 1630) or translational rate of a linear actuator (e.g., slider 1530).

[0145] In some variations, the controller 160 may be configured to maintain a driving frequency of the driving mechanism 120 at about 10 Hz or greater (e.g., at least 10 Hz, at least 15 Hz, at least 20 Hz, at least 25 Hz, and least 30 Hz, at least 35 Hz, at least 40 Hz, at least 50 Hz, between about 10 Hz and about 50 Hz, between about 10 Hz and about 30 Hz, etc.). Alternatively, the controller 160 may be configured to maintain a driving frequency at lower frequencies, such as below about 10 Hz (e.g., below 8 Hz, below 5 Hz, below 3 Hz, between about 1 Hz and about 5 Hz, between about 1 Hz and about 3 Hz).

[0146] In some variations, to control fluidic pressure in the driver system (e.g., in the operating chamber volume 112, in the fluidic flow line 150, etc.), the controller 160 can be configured to release or add inflation fluid to decrease or increase fluidic pressure, respectively. For example, in some variations, the controller 160 can be configured to open one or more valves 132 to allow flow of inflation fluid from a reservoir 140 into the fluidic flow line 150 and / or operating chamber volume 112. For example, the controller 160 can open such valve(s) 132 to control introduction of inflation fluid in one or more predetermined doses (e.g., in accordance with a predetermined filling pattern). Such predetermined doses may, for example, each be configured as a single use volume (e.g., capsule, cartridge, etc.) including an exact dose of inflation fluid for one pump cycle of the driving system. Additionally or alternatively, the controller 160 can open such valve(s) 132 in response to an indication (e.g., from sensor arrangement 134) that the pressure in the fluidic system is below a target value.

[0147] As another example, the controller 160 can be configured to open one or more active control valves 170 in fluidic communication with the fluidic system (e.g., the operating chamber volume 112, the hub 130, the fluidic flow line 150) that function to enable outflow of inflation fluid, such as to prevent overinflation. In some variations, the controller 160 can open such overpressure valve(s) 170 in response to an indication (e.g., from sensor arrangement 134) that the pressure in the fluidic system is above a target value or a system maximum value. In some variations, a system maximum value can be a predetermined value (e.g., about 900 mmHg). For example, the system maximum value can be set based at least in part on a maximum desired inflation pressure for the balloon in the circulatory assist device 10 and / or a maximum desired system fluidic pressure for the driver system 100. Accordingly, the controller 160 can be configured to open one or more overpressure valves as a safety measure. However, in some variations the system can additionally or alternatively include one or more passiveAttorney Docket No.: CDB.016WO overpressure valves that are similar to control valves 170 except that such passive overpressure valves are configured to open in response to the presence of a predetermined threshold of pressure difference across the valve, to enable outflow of inflation fluid.

[0148] In some variations, the controller 160 can be configured to control temperature of the driver system (e.g., chamber 110). For example, the controller 160 can receive temperature information (e.g., from sensor arrangement 134, from one or more sensors 172 on the driver chamber 110, etc.) and activate a temperature modulation system (e.g., temperature modulation system 430) to maintain a desired temperature. This active temperature control can be performed in addition to, or as an alternative to, passive temperature modulation methods such as those described elsewhere herein (e.g., using cooling elements incorporating fluid having a high specific heat capacity).

[0149] For example, as described elsewhere herein, when operated, the driver system can naturally become warmer due to operating components, which may affect the fluidic properties of the inflation fluid and affect the accuracy and precision with which the flow of inflation fluid can be controlled (e.g., due to temperature affecting viscosity and / or density of the inflation fluid, which thereby affects inflation and deflation pressures within the driver chamber 110 and other parts of the fluidic system, as well tendencies of any leakage of the inflation fluid), thereby affecting the pumping efficiency. Accordingly, the controller 160 can activate a temperature modulation system to help lower the temperature of the system. In some variations, the temperature modulation system can include a Peltier module. For example, as shown in the schematic illustration of FIG. 22A, a chamber 2200 (which is an example of chamber 110) can include a Peltier module 2240. As shown in FIG. 22B, a controller 160 can include various circuitry (e.g., H-bridge) to operate the Peltier module for cooling the driver chamber 2200.

[0150] As another example, tight control of the inflation fluid when introducing the inflation fluid can be important, as the variability in properties of the inflation fluid may vary with the effect of temperature. Accordingly, in some variations the controller 160 can be configured to maintain the temperature of the inflation fluid (in the reservoir 150, in the driver chamber 110, etc.) within a predetermined temperature range. For example, in some variations in which the inflation fluid is helium, the controller 160 can be configured to maintain the temperature of the inflation fluid at or above body temperature of a human (e.g., between about 35 degrees Celsius and about 40 degrees Celsius), as inflation fluid being below body temperature may result in undesirable condensation in the driving system, and inflation fluidAttorney Docket No.: CDB.016WO being excessively warm may result in undesirable blood damage or other patient harm, and / or to help stabilize pressure in the catheter and other portions of the fluid flow path. In some variations, cooling and / or heating of the inflation fluid may be accomplished at least in part by controlling temperature of the driver chamber, the hub, and / or the fluid flow line, etc. However, in some variations the temperature of the inflation fluid may be maintained at least in part through convective cooling inside the circulatory assist device. Additionally or alternatively, in some variations in which the inflation fluid is helium, the controller 160 can be configured to cool the driver chamber 110 to a predetermined temperature, such as a predetermined cooling temperature below ambient temperature (e.g., between -5 degrees Celsius and 5 degrees Celsius around a working point or predetermined temperature), such as with a Peltier module and / or in any suitable manner. Such thermal conditioning of the driver chamber 110 can also be helpful to calibrate the appropriate amount of inflation fluid that should be introduced into the fluidic system during filling. Additionally or alternatively, in some variations in which the inflation fluid is helium, the controller 160 can be configured to cool the hub 130 to a predetermined temperature, such as a predetermined cooling temperature to 50 degrees Celsius or lower. Additionally or alternatively, in some variations in which the inflation fluid is helium, the controller 160 can be configured to cool to a predetermined temperature any one or more components of the driver system not directly in contact with the inflation fluid, such as the actuator for the driver chamber (e.g., linear actuator configured to move a plunger or piston within the driver chamber, as described elsewhere herein); such a predetermined temperature for such components may be below about 80 degrees Celsius or below about 100 degrees Celsius.

[0151] As another example, in some variations atmospheric pressure can have an effect on operation of the driver chamber 110. For example, variations in which the driver chamber 110 includes a membrane (e.g., chamber 510, chamber 810, chamber 910, chamber 1010, chamber 1210, chamber 1310, chamber 1410), changes in atmospheric pressure due to altitude, weather conditions, and / or the like can cause changes in the behavior of the membrane with respect to decreasing and / or increasing the operating chamber volume. Accordingly, control of temperature in the system can help compensate or address the effects of atmospheric pressure. For example, in some variations, a pressure sensor on the driver chamber (e.g., in sensor arrangement 172) such as a barometer can provide sensor information regarding atmospheric pressure. As one example, this pressure information can be provided as input to a feedback loop to the controller 160, which can be configured to adjust stroke length (and correspondingAttorney Docket No.: CDB.016WO stroke volume) of the driving mechanism. As another example, pressure sensor information can be provided as input to a feedback loop to the controller 160, which can be configured to adjust the temperature with a temperature modulation system (e.g., temperature modulation system 430) to maintain a desired driver output in view of the changed fluidic properties of the inflation fluid.

[0152] In some variations, the controller may be configured to adjust the control of one or more of the parameters mentioned above (including, e.g., speed, stroke length, driving frequency, volume of the driver chamber, rate of change of the driver chamber volume, fluidic pressure in the system, temperature within the system, dead volume within the system, and / or compliance of the driver chamber), in response to feedback from pressure sensors, temperature sensors, flow sensors, or external sensors which feed their signal into the controller to facilitate closed loop control of the driver. Such sensor(s) may be incorporated in, for example, the driver chamber, the hub, the extension tubing, etc. Additionally or alternatively, one or more sensors in the circulatory assist device (e.g., coupled to the balloon or other volume displacement member) that provide information indicative of state of the volume displacement member. For example, the conduit and / or volume displacement member may include or have coupled to it one or more temperature sensors (e.g., configured to measure the internal temperature of the conduit and / or volume displacement member), one or more pressure sensors (e.g., configured to measure the pressure within the conduit and / or volume displacement member during expansion and / or contraction of the volume displacement member), and / or one or more sensors configured to measure the rate of expansion and / or contraction of the volume displacement member. Such sensor(s) may provide their sensor measurements to the controller as feedback for closed loop control of the driver.

[0153] In some variations, the controller 160 may be configured to dynamically adjust the control of one or more of the parameters mentioned above (including, e.g., speed, stroke length, volume of the driver chamber, rate of change of the driver chamber volume, fluidic pressure in the system, temperature within the system, dead volume within the system, and / or compliance of the driver chamber), across different driving frequencies, such as to achieve a selected or otherwise desired displacement volume of inflation fluid that is displaced from the driver chamber. For example, the stroke length and / or speed of the driving mechanism, pressure or temperature of inflation fluid, and / or other parameters, may be dynamically varied as a function of one or more sensor inputs such as driving frequency, pressure or temperature within the driver system and / or circulatory assist device (e.g., within the fluidic path, volumeAttorney Docket No.: CDB.016WO displacement member, and / or conduit that surrounds at least a portion of the volume displacement member), heart rate, blood pressure, or blood flow rate within an anatomical region of the patient (e.g., left ventricle, right ventricle, aorta, other chamber or vessel in which the circulatory assist device is placed). As one illustrative example, the system may be configured to receive signals from a flow rate sensor that is configured to measure a blood flow rate in a blood vessel, and the controller may be configured to adjust the displacement volume based on the measured blood flow rate. In some variations, such a blood flow rate may be measured directly with one or more flow rate sensors. Additionally or alternatively, in some variations, such a blood flow rate may be measured indirectly with one or more suitable flow rate sensors. For example, multiple pressure sensors may indirectly provide a measurement of blood flow rate, based on pressure waves within the blood vessel (e.g., differential pressure measurement between pressure waves). Other types of sensors may additionally or alternatively be used to provide sensor feedback to the driver system for adjusting displacement volume including, without limitation, external or intravascular ultrasound sensors, vascular flow sensors, heart rate sensors, sound sensors (microphones), temperature probes, blood pressure sensors, and others.[0.154] Additionally or alternatively, in some variations, one or more patient metrics (e.g., heart rate, blood pressure, blood flow rate within an anatomical region of the patient) for use as feedback to the driver system may be determined by one or more external devices, such as medical imaging (e.g., ultrasound such as echocardiography, MRI, CT, fluoroscopy, etc.), external sensors (e.g., electrocardiogram (ECG) sensors, wearable microphones or ultrasound patches), and / or the like. Sensor information from such external sensors may be used by the controller 160 to adjust one or more driver parameters, as described herein.

[0155] Additionally or alternatively, in some variations, power consumption by the driver system may be used as feedback to the driver system for adjusting one or more driver parameters (including, e.g., speed, stroke length, volume of the driver chamber, rate of change of the driver chamber volume, fluidic pressure in the system, temperature within the system, dead volume within the system, and / or compliance of the driver chamber). For example, the controller 160 may monitor a current rate of power consumption, a percentage or amount of power remaining in a stored power source (e.g., battery) providing power to the driver system, a percentage or amount of power from a stored power source (e.g., battery) that has been consumed, and / or the like. The controller 160 may then adjust one or more driver parameters based at least in part on such power consumption information.Attorney Docket No.: CDB.016WO

[0156] As such, the driving mechanism may be characterized as having a driving mechanism stroke length and / or speed profile across a driving frequency range, such that the controller may change stroke length and / or speed (and hence inflation fluid pressure and / or blood flow rate) as a function of driving frequency. The function may be pre-programmed (e.g., based on empirical testing), and / or based on feedback from one or more sensors as described above. In some variations, the function may be linear or any suitable relationship (e.g., parabolic curve). In some examples, the driver system is configured to receive signals from sensors measuring key cardiovascular parameters such as ventricular pressure, aortic pressure, aortic blood flow rate, and heart rate, and the driver system is automatically regulated so that patient circulation is maintained at desired levels.VIII. Inflation Fluid Refilling and Safety

[0157] Throughout various components of a driver system for driving inflation fluid in and out of the circulatory assist device, the inflation fluid can leak from the fluidic circuit. For example, some materials used to form tubing in the fluid flow line, the volume displacement member of the circulatory assist device, etc. are not necessarily perfectly impermeable to molecules of the inflation fluid, and may permit diffusion of the inflation fluid out of the fluidic circuit. Furthermore, imperfect sealing between non-integrally formed parts may permit further leakage of inflation fluid. As such, the fluidic circuit may suffer from leakage effects, such as reduced pressures leading to inefficient operation of the driver system and circulatory assist device.

[0158] Additionally, it may be desirable to ensure that the inflation fluid used to cyclically expand the volume displacement member in the circulatory assist device is of sufficient purity. For example, maintaining a high purity inflation fluid (especially at correct and known pressures) may help facilitate optimal operation of the driver system and circulatory assist device by allowing for efficient and predictable pumping behavior.

[0159] Furthermore, the nature of inflation fluid used to cyclically expand the volume displacement member of the circulatory assist device may also pose safety risks. For example, in the event of anomalies such as balloon linkage, kinking of fluidic lines (e.g., catheter, extension tubing), continued operation of the driver system may cause risk to the patient.

[0160] To address these and other challenges, the driver system may include one or more components configured to refill inflation fluid in the fluidic circuit, in the driver chamber 110, the hub 130, the fluid flow line 150, and the volume displacement member of theAttorney Docket No.: CDB.016WO circulatory assist device 10, etc. In some variations, the system may include, for example, a manifold that is operated to control refilling of inflation fluid from a fluid source 140 into the hub 130 (and / or driver chamber 110) via one or more manifold valves (e.g., schematically included in FIG. 1 as one or more valves 132). In some variations, the overall driver system is configured to maintain the amount of inflation fluid leakage below about 1 (std) ml (e.g., standard milliliter / minute).

[0161] Additionally, to improve patient safety, the driver system may incorporate one or more safety features that function to quickly put the driver system into a safe state, such as with the volume displacement member (e.g., balloon) in a deflated state. For example, in general, in response to a detection of an adverse event (e.g., pressure above a predetermined maximum pressure, or pressure below a predetermined minimum pressure), the controller 160 may be configured to perform one or more of multiple potential safety operations. For example, a safety operation may include ceasing operation of the driver system with the driver chamber 110 is in the decompressed state (e.g., piston or plunger stroke position is at a point in the stroke cycle corresponding to the balloon or other volume displacement member being sufficiently deflated). Another example of a safety operation includes opening one or more safety valves to vent any overpressure in the fluid flow line, such as into the manifold and into a buffer vessel configured to receive vented inflation fluid, thereby preventing subsequent balloon inflation.

[0162] In some variations, the manifold may be kept at negative (vacuum) pressure. This reduces the fluid impedance of the one or more valves 132, which may be advantageous to enable a faster response time for venting inflation fluid as needed through the one or more valves 132. The fluid impedance may additionally or alternatively be further reduced with a sufficiently large valve orifice in the one or more valves 132. Another advantage in keeping the manifold at negative pressure is to help increase the pressure differential between the inside and outside of the volume displacement member of the circulatory assist device, which may help facilitate faster venting of overpressure within the fluidic system.

[0163] In some variations, the hub 130 may include or be in fluidic communication with one or more valves (e.g., also schematically included in FIG. 1 as one or more valves 132) that may be operated to modulate flow of inflation fluid in and out of the hub 130. In some variations, such valves may function as safety valves for venting. Multiple valves placed in parallel may be incorporated for redundancy and / or improving efficiency of venting. For example, these valves may be fast switching (e.g., with a response time of approximately 10 ms or less) and have a sufficiently large valve orifice (e.g., at least about 2 mm) to help facilitateAttorney Docket No.: CDB.016WO venting. In some variations, such valves may be open by default, such that venting occurs automatically in the event of a power outage.

[0164] In some variations, the hub 130 may include one or more pressure sensors configured to monitor pressure waveforms within the hub 130 (and hence within the fluidic circuit) during operation. The hub 130 may include multiple pressure sensors for redundancy, in case of sensor failure. In general, as described elsewhere herein, pressure data from such sensor(s) relating to pressure within the driver system may be used by the controller 160 to operate the refilling and / or venting of inflation fluid. For example, sensor data from the pressure sensors in the fluidic circuit may be used to help detect the presence and / or amount of inflation fluid leakage from the fluidic circuit. High bandwidth (e.g., ~1.8 kHz) and high accuracy pressure sensors may be advantageous for this purpose.

[0165] FIG. 26 is a schematic illustration of an example implementation of a driver system incorporating refilling features and safety features such as those described above. Although the driver system is primarily referred to below as a helium circuit and references a piston or plunger-type driver chamber (e.g., similar to the chamber 410 and chamber 510 described herein with respect to FIGS. 4 and 5, respectively), it should be understood that the below example may similar apply to other types of inflation fluid other than helium, as well as other types of driving chambers such as those described herein.

[0166] The helium circuit shown in FIG. 26 includes at least an inflation fluid source (He tank) which is an example of fluid source 140, a hub 2630 (an example of hub 130) in fluidic communication with a driver chamber 2610 (an example of chamber 110) and volume displacement member of a circulatory assist device 10, and a manifold 2640 configured to receive inflation fluid from the inflation fluid source (He tank) that is passed into the hub 2630. The helium circuit further includes a vacuum pump (VP) that connects into valve (V2) associated with the manifold 2640 and is operable to maintain the manifold 2640 at negative pressure. The helium circuit further includes multiple valves including pressure safety relief valves (RV1 and RV2) that vent into atmosphere, and a vent valve (V6) in the manifold 2640 that is default closed and opens to vent to atmosphere.

[0167] The inflation fluid source (He tank) may include a tank or other reservoir of sufficiently large volume (e.g., 12L) to help reduce the need for a tank exchange during a patient procedure. The vacuum pump (VP) may be configured with sufficient capacity to quickly evacuate the fluidic circuit, such as to a level of <10 mbar(a), which may help preventAttorney Docket No.: CDB.016WO fresh (e.g., pure) inflation fluid from intermixing with remnant inflation fluid in the fluidic system that would otherwise result in a low purity level of the operational inflation fluid. As described above, the vacuum pump (VP) may be fluidically connected to the manifold 2640 via valve (V2).

[0168] The driver chamber 2610 may include a double acting pneumatic piston cylinder that is rated with a minimum lifetime of at least 360 minutes. The piston cylinder connection towards the hub 2630 may be enlarged in diameter to 4.5 mm in order to lower the flow impedance. In one example implementation that results in a suitable trade-off between the force generated by gas pressure and mass acceleration forces, the piston cylinder may have a diameter of 63 mm and a stroke length of 20 mm, such that a stroke volume of 62 ml is obtained. The piston cylinder may include a peripheral seal including thermoplastic polyurethane (TPU). In some variations, when an acceptable small leak around the piston cylinder is present, the pump stroke itself is not affected by leakage over the piston seal. The effects of leakage on a longer time scale are reduced, as both sides are filled to an extent that the pressures are balanced on average; that is, during the compression (inflation) cycle there is a pressure gradient from pump to backside, but in the decompression (deflation) phase this is reversed. Accordingly, just a small quantity of inflation fluid leaks up and down over the seal, but pump pressures and inflation fluid purity are not affected. Furthermore, in some variations, the driver chamber 2610 includes one or more (e.g., two) thermocouples and a cooling element (e.g., water cold plate) to reduce excessive heat from inflation fluid dissipation and piston friction. The driver chamber 2610 may further include limit switches (e.g., proximity sensors) that are configured to monitor end point positions of the piston for the drive cycle.

[0169] As shown in FIG. 26, the hub 2630 between the driver chamber 2610 and the fluid flow line (e.g., catheter) to the circulatory assist device 10 may be configured with low dead volume to improve pump efficiency. In some variations, the hub 2630 may further include one or more (e.g., two) pressure sensors (PT cath 1 and PT_cath_2), one or more (e.g., two) temperature sensors TC Hub l and TC_Hub_2), similar to that described above. The hub 2630 may include a connection to inflation fluid refill circuit hardware such as two default open valves (V4Fa and V4Fb) that facilitate the evacuation and subsequent filling of the fluidic circuit with high purity inflation fluid, as well as for safety venting of the fluidic circuit. In some variations, the driver chamber 2610 and the hub 2630 may be connected with flexible tubing, so as to accommodate repetitive movements of an actuator (e.g., linear actuator) for the driver chamber 2610 with respect to the hub 2630.Attorney Docket No.: CDB.016WO

[0170] The helium circuit shown in FIG. 26 may include various safety features. For example, a continuous separation of pressures between the fluid flow line (e.g., extension line) and the inflation fluid source (He tank) can be facilitated by controlled dosing of inflation fluid into the driver chamber 2610. Specifically, this controlled dosing may be accomplished with the use of a separate filling chamber (filling cylinder) that is filled to a regulated inflation fluid pressure via valve (V5), and at least one proximity sensor that monitors the state of this filling chamber (filling cylinder). A controlled quantity of inflation fluid may be sampled from the filling chamber by opening and closing valve (V5). Subsequently, the inflation fluid may flow into an already evacuated fluidic circuit and piston backside, via valves VI and VF4ab and valve V4B, respectively. This dosing may also help protect against inadvertently exposing the patient to large doses of inflation fluid in the event of a failure of the volume displacement member of the circulatory assist device (e.g., balloon rupture).

[0171] As another example of a safety feature, in the event of failure of the pressure regulatory, the overpressure of inflation fluid may be relieved via one or more (e.g., two) safety relief valves (V4Fa and V4Fb) as described above at a predefined burst pressure (e.g., 2 barg). The safety valves (V4Fa and V4Fb) may be placed in parallel for redundancy.

[0172] As another example of a safety feature, in the event of extreme failure such as vacuum pump failure, backup may be provided by an auxiliary circuit through which the fluidic circuit can be filled manually. For example, an operator may put the manual valve (MV Fill) in the manual position, and then manually fill (and evacuate and refill) the fluidic circuit by operating an external vacuum source and manual pump such as a syringe through a port (Manual Fill Port). Manually introduced inflation fluid can be introduced into the fluidic circuit through a valve (V 6).Example Specifications

[0173] In some variations, the minimum volume of fluid (e.g., helium) to be moved by the driver system (e.g., stroke volume of driver system) during each cycle is between about 20 mL and about 120 mL, or between 25 mL and about 100 mL, or between about 25 mL and about 50 mL, or between about 50 mL and about 75 mL (e.g., about 62 mL). Generally, such volume of fluid may depend on factors including the pressure range expected over the fluid flow line, the impedance of the fluid flow line, dead volume, and / or volume displacement member stroke volume. In an example embodiment, a maximum stroke volume may be about 250 mL (e.g., for an 80 mm diameter driver chamber having a 50 mm piston stroke length).Attorney Docket No.: CDB.016WO

[0174] In some variations, an “efficiency” of the combined driver system and circulatory assist device may be defined as the ratio of the balloon volume of the circulatory assist device to the stroke volume of the driver system.

[0175] In an example implementation for a circulatory assist device having a balloon (or other volume displacement member) with a balloon volume (or other volume of the volume displacement member) of about 1.5 mL, the driver system’s stroke volume may be between about 60 mL and about 65 mL, or about 62 mL (e.g., efficiency of about 2%). In another example implementation for a circulatory assist device having a balloon (or other volume displacement member) with a balloon volume (or other volume of the volume displacement member) of about 4.5 mL, the driver system’s stroke volume may be between about 115 mL and about 125 mL, or about 120 mL (e.g., efficiency of about 4%). In another example implementation for a circulatory assist device having a balloon (or other volume displacement member) with a balloon volume (or other volume of the volume displacement member) of about 6 mL, the driver system’s stroke volume may be between about 115 mL and about 125 mL, or about 120 mL (e.g., efficiency of about 5%).

[0176] Additionally or alternatively, in some variations the speed of fluid (e.g., helium) to be delivered or removed from the volume displacement member (e.g., driver stroke volume) may depend at least in part on balloon volume and / or dead volume. In some variations, the driving frequency is at least 100 bpm, between about 100 bpm and about 1100 bpm, between about 200 bpm and about 10,000 bpm, between about 400 bpm and about 2000 bpm, or between about 500 bpm and about 1500 bpm. In some variations, the driving frequency is between about 300 bpm (5 Hz) and about 2000 bpm (about 33.3 Hz), where duration of inflation (compression) is about 67 ms and duration of deflation (decompression) is about 133 ms. In some variations, the driving frequency is up to about 900 bpm (15 Hz), where duration of inflation (compression) is about 22 ms and duration of deflation (decompression) is about 44ms. For example, in some variations, the driving frequency is about 2000 bpm (or about 33.3 Hz), where the duration for each driving cycle for the driving mechanism is about 30 ms.

[0177] The pressure within the driving system may vary during a driving cycle (including inflation and deflation of a balloon-type volume displacement member) between about -400 mmHg and about 700 mmHg, or between about -200 mmHg and about 450 mmHg. With an assumption of inflation occurring over about 33% of the driving cycle and deflation occurring over about 67% of the driving cycle, fluid may be delivered to the volume displacement member over about 10 ms of the driving cycle (with an average pressure increaseAttorney Docket No.: CDB.016WO of about 110,000 mmHg / s), and fluid may be evacuated from the volume displacement member over about 20 ms of the driving cycle. In some variations, the volumetric flow into the balloon controlled by the controller during inflation may be about 2 mL in 10 ms (or about 0.2 L / s), while volumetric flow through the driver system (including the extension tubing and catheter) controlled by the controller during deflation may be about 22 mL in 10 ms (or about 2.2 L / s). However, in some variations the volumetric flow into the balloon controlled by the controller during inflation of the balloon may be between about 0.1 L / s and about 0.5 L / s, and the volumetric flow through the driver system controlled by the controller during deflation of the balloon may be between about 1.8 L / s and about 3 L / s. In variations in which the inflation fluid is helium, mass flow into the balloon controlled by the controller during inflation may be expressed as about 60 mg / s and mass flow through the driver system controlled by the controller during deflation may be expressed as about 442 mg / s. Furthermore, in some variations, the mass flow into the balloon may be between about 50 mg and about 70 mg, and / or the mass flow through the driver system may be between about 430 mg / s and about 460 mg / s.

[0178] FIG. 11 illustrates various example specifications for a driver system in relation to a circulatory assist device including a balloon that is cyclically filled with helium as the inflation fluid. In an example implementation, the driver system may be configured to deliver to the balloon a minimum volume of at least 4 ml of helium at a pressure of 600 mbar, and deliver to the fluid flow line a minimum volume of at least 11 ml of helium at a pressure of 600 mbar. The driver system may be configured to deliver a helium inflation pressure of at least 700 mbar to the fluid flow line-hub connection, and a helium vacuum pressure of -600 mbar to the fluid flow line-hub connection. The driver system may be configured to operate between about 10 Hz and about 40 Hz, with varying maximum frequencies depending on the volume of the balloon (e.g., maximum 40 Hz for a balloon volume of 2ml, maximum 30 Hz for a balloon volume of 3 ml, maximum 25 Hz for a balloon volume of 4ml). The driver system may be configured to maintain a maximum helium gas temperature of 37 degrees Celsius at steady state at the defined maximum frequency of operation. In some variations, the driver system may be configured to operate at a sound level (at maximum driver output) of no more than about 60 dBA. Similar to safety features described herein, in the event a helium leakage occurs in the driver system, a sensor feedback loop (e.g., pressure feedback) may be configured to power off the actuator(s) actuating the driver chamber, and apply a vacuum to the hub to leave the balloon in a completely deflated state with no possibility of refilling.Attorney Docket No.: CDB.016WOConclusion

[0179] Although many of the embodiments are described above with respect to systems, devices, and methods for driving a volume displacement member for a circulatory assist device, the technology is applicable to other applications and / or other approaches, including those that require high frequency pumping operation with high frequency (including with high precision and / or accuracy). Moreover, other embodiments in addition to those described herein are within the scope of the technology. Additionally, several other embodiments of the technology can have different configurations, components, or procedures than those described herein. A person of ordinary skill in the art, therefore, will accordingly understand that the technology can have other embodiments with additional elements, or the technology can have other embodiments without several of the features shown and described above with reference to FIGS. 1-26.

[0180] The descriptions of embodiments of the technology are not intended to be exhaustive or to limit the technology to the precise form disclosed above. Where the context permits, singular or plural terms may also include the plural or singular term, respectively. Although specific embodiments of, and examples for, the technology are described above for illustrative purposes, various equivalent modifications are possible within the scope of the technology, as those skilled in the relevant art will recognize. For example, while steps are presented in a given order, alternative embodiments may perform steps in a different order. The various embodiments described herein may also be combined to provide further embodiments.

[0181] As used herein, the terms “generally,” “substantially,” “about,” and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations in measured or calculated values that would be recognized by those of ordinary skill in the art.

[0182] Moreover, unless the word “or” is expressly limited to mean only a single item exclusive from the other items in reference to a list of two or more items, then the use of “or” in such a list is to be interpreted as including (a) any single item in the list, (b) all of the items in the list, or (c) any combination of the items in the list. Additionally, the term "comprising" is used throughout to mean including at least the recited feature(s) such that any greater number of the same feature and / or additional types of other features are not precluded. It will also be appreciated that specific embodiments have been described herein for purposes of illustration,Attorney Docket No.: CDB.016WO but that various modifications may be made without deviating from the technology. Further, while advantages associated with certain embodiments of the technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology can encompass other embodiments not expressly shown or described herein.

Claims

1. Attorney Docket No.: CDB.016WOCLAIMSI / We claim:

1. A driver system for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device comprises a volume displacement member with an expandable chamber and the volume displacement member is movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the driver system comprises: a driver chamber with an operating chamber volume fillable with an inflation fluid; a driving mechanism configured to cyclically decrease and increase the operating chamber volume at a driving frequency; a fluid flow line configured to convey inflation fluid between the operating chamber volume and the expandable chamber; and a controller configured to control the driving mechanism such that inflation fluid is conveyed between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase at the driving frequency, thereby regulating a pumping throughput of the circulatory assist device; and wherein the controller is configured to maintain the driving frequency at 5 Hz or greater.

2. The system of claim 1, wherein the controller is configured to control the driving mechanism such that a predetermined volume of inflation fluid is conveyed into and out of the volume displacement member at the driving frequency.

3. The system of claim 1 or 2, wherein the controller is configured to automatically regulate at least one of the driving frequency, a stroke length, or a driving speed of the driving mechanism based at least in part on a signal received from at least one sensor.Attorney Docket No.: CDB.016WO4. The system of claim 3, wherein the at least one sensor senses at least one of an inflation fluid pressure, inflation fluid temperature, blood pressure in the heart or blood vessel, or blood flow in the patient’s heart or blood vessel.

5. The system of any one of claims 1-4, wherein the inflation fluid is conveyed to the expandable chamber at a pressure of between about 100 mmHg and about 1500 mmHg.

6. The system of any one of claims 1-5, wherein the inflation fluid is withdrawn from the expandable chamber at a negative pressure of between about -200 mmHg and about -700 mmHg.

7. The system of any one of claims 1-6, wherein at least about 1.5 ml of inflation fluid is conveyed to and from the expandable chamber during each cycle.

8. The system of any one of claims 1-7, wherein the driver chamber comprises a housing and a movable divider, wherein the operating chamber volume is on a first side of the movable divider.

9. The system of claim 8, further comprising a seal around a periphery of the divider providing a fluid seal between the movable divider and the housing.

10. The system of claim 9, wherein the seal is coupled to the movable divider so as to move with the movable divider relative to the housing.

11. The system of any one of claims 8-10, wherein the driver chamber further comprises one or more vents on a second side of the movable divider opposite the first side.

12. The system of any one of claims 8-11, wherein the movable divider comprises a membrane having a fully pressurizing configuration and a fully depressurizing configuration.Attorney Docket No.: CDB.016WO13. The system of any one of claims 8-12, wherein the movable divider comprises a plunger coupled to a driving rod, wherein the driving rod is operably coupled to the driving mechanism.

14. The system of claim 12 or 13, wherein the fully pressurizing configuration and the fully depressurizing configuration correspond to respective end points of a stroke length of the driving mechanism.

15. The system of any one of claims 12-14, wherein the membrane has a nonlinear profile in the fully pressurizing configuration.

16. The system of any one of claims 12-15, further comprising a driving rod coupled to the membrane with one or more coupling discs.

17. The system of any one of claims 12-16, wherein the membrane comprises an inner edge coupled to a periphery of the plunger.

18. The system of any one of claims 12-17, wherein the membrane comprises an outer edge coupled to an internal surface of the housing.

19. The system of claim 18, wherein the membrane has a fully pressurizing configuration and a fully depressurizing configuration corresponding to end points of a stroke length of the driving mechanism, wherein the inner edge and the outer edge are farther apart when the membrane is in the fully pressurizing configuration than when the membrane is in the fully depressurizing configuration.

20. The system of claim 12, wherein the membrane is actuated between the fully pressurizing configuration and the fully depressurizing configuration without a direct mechanical link between the driving mechanism and the membrane.

21. The system of claim 20, wherein the membrane is magnetically actuated between the fully pressurizing configuration and the fully depressurizing configuration.Attorney Docket No.: CDB.016WO22. The system of claim 20 or 21, wherein the membrane is actuated between the fully pressurizing configuration and the fully depressurizing configuration by application of a pressure or a vacuum to the second side of the movable divider.

23. The system of claim 12, wherein the membrane forms a bladder configured to form a circumferential seal against an internal surface of the housing.

24. The system of any one of claims 1-23, wherein the driver chamber comprises a temperature modulation system operably coupled to the controller.

25. The system of any one of claims 1-24, wherein the driving mechanism comprises at least one linear actuator.

26. The system of claim 25, wherein the at least one linear actuator comprises a first linear actuator configured to decrease the operating chamber volume, and a second linear actuator configured to decompress the operating chamber volume.

27. The system of claim 26, wherein the driving mechanism comprises an adjustable connection rod unit with an adjustable effective length for converting a rotational input to a linear output.

28. The system of any one of claims 1-27, wherein the driving mechanism comprises a driving disc oriented non-orthogonally to a rotational axis of the driving disc for converting a rotational input to a linear output.

29. The system of any one of claims 1-28, wherein the inflation fluid comprises helium.

30. The system of any one of claims 1-29, wherein the fluid flow line comprises a pump catheter having a first distal end and a first proximal end, and an extension tubing having a second distal end and a second proximal end, andAttorney Docket No.: CDB.016WO wherein the first distal end is configured to couple to the expandable chamber of the volume displacement member, the second distal end is configured to couple to the first proximal end, and the second proximal end is configured to couple to the driver chamber.

31. The system of any one of claims 1-30, further comprising a hub comprising one or more valves configured to control introduction, removal, or both introduction and removal of inflation fluid from the fluid flow line.

32. The system of any one of claims 1-31, wherein the controller is configured to operate the driving mechanism at a driving frequency of at least 10 Hz.

33. The system of any one of claims 1-32, wherein the controller is configured to operate the driving mechanism at a driving frequency of at least 20 Hz.

34. The system of any one of claims 1-33, wherein the controller is configured to operate the driving mechanism at a driving frequency of at least 30 Hz.

35. The system of any one of claims 1-34, further comprising at least one pressure sensor configured to measure pressure of the inflation fluid.

36. The system of claim 35, wherein the controller is configured to adjust at least one of a driving frequency, a stroke length, or a driving speed of the driving mechanism based on the pressure of the inflation fluid.

37. The system of claim 35 or 36, wherein the controller is configured to adjust a stroke length of the driving mechanism as a function of driving frequency of the driving mechanism.

38. The system of any one of claims 1-37, wherein the controller is configured to adjust a at least one of a driving frequency, a stroke length, or a driving speed of the driving mechanism based on a flow rate of the inflation fluid.Attorney Docket No.: CDB.016WO39. A method for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device has a volume displacement member with an expandable chamber and the volume displacement chamber is movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the method comprises: providing a driver chamber with an operating chamber volume fillable with an inflation fluid, a driving mechanism configured to cyclically decrease and increase the operating chamber volume at a driving frequency, and a fluid flow line configured to convey inflation fluid between the operating chamber volume and the expandable chamber; and regulating a pumping throughput of the circulatory assist device by controlling conveyance of inflation fluid between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase at the driving frequency, wherein the driving frequency is 5 Hz or greater.

40. The method of claim 39, further comprising automatically regulating the pumping throughput of the circulatory assist device based on a signal received from at least one sensor.

41. The method of claim 39 or 40, wherein the at least one sensor senses at least one of an inflation fluid pressure, inflation fluid temperature, blood pressure in the heart or blood vessel, or blood flow in the patient’s heart or blood vessel.

42. The method of any one of claims 39-41, further comprising operating the driving mechanism at a driving frequency of at least 10 Hz.

43. The method of any one of claims 39-42, further comprising operating the driving mechanism at a driving frequency of at least 20 Hz.

44. The method of any one of claims 39-43, further comprising operating the driving mechanism at a driving frequency of at least 30 Hz.Attorney Docket No.: CDB.016WO45. A system, comprising: a circulatory assist device comprising a volume displacement member with an expandable chamber, wherein the volume displacement member is cyclically movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume; and a driver system for actuating the circulatory assist device, the driver system comprising: a driver chamber with an operating chamber volume fillable with an inflation fluid; a driving mechanism configured to cyclically decrease and increase the operating chamber volume at a driving frequency; a fluid flow line configured to convey inflation fluid between the operating chamber volume and the expandable chamber; and a controller configured to control conveyance of inflation fluid between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase at the driving frequency, thereby regulating a pumping throughput of the circulatory assist device, wherein the controller is configured to maintain the driving frequency at 5 Hz or greater.

46. The system of claim 45, wherein the controller is configured to automatically regulate at least one of the driving frequency, a stroke length, or a driving speed of the driving mechanism based at least in part on a signal received from at least one sensor.

47. The system of claim 45 or 46, wherein the driver chamber comprises a housing and a movable divider, wherein the operating chamber volume is on a first side of the movable divider.

48. The system of any one of claims 45-47, wherein the inflation fluid comprises helium.Attorney Docket No.: CDB.016WO49. The system of any one of claims 45-48, wherein the inflation fluid comprises hydrogen.

50. The system of any one of claims 45-49, wherein the inflation fluid comprises carbon dioxide.

51. The system of any one of claims 45-50, wherein the fluid flow line comprises a pump catheter having a first distal end and a first proximal end, and an extension tubing having a second distal end and a second proximal end, and wherein the first distal end is configured to couple to the expandable chamber of the volume displacement member, the second distal end is configured to couple to the first proximal end, and the second proximal end is configured to couple to the driver chamber.

52. The system of any one of claims 45-51, further comprising a hub comprising one or more valves configured to control introduction, removal, or both introduction and removal of inflation fluid from the fluid flow line.

53. The system of any one of claims 45-52, wherein the controller is configured to operate the driving mechanism at a driving frequency of at least 10 Hz.

54. The system of any one of claims 45-53, wherein the controller is configured to operate the driving mechanism at a driving frequency of at least 20 Hz.

55. The system of any one of claims 45-54, wherein the controller is configured to operate the driving mechanism at a driving frequency of at least 30 Hz.

56. The system of any one of claims 45-55, wherein the controller is configured to vary at least one of the driving frequency, a stroke length, or a driving speed of the driving mechanism.Attorney Docket No.: CDB.016WO57. The system of any one of claims 45-56, wherein the volume displacement member comprises a balloon.

58. The system of any one of claims 45-57, wherein the circulatory assist device comprises a conduit surrounding at least a portion of the volume displacement member, wherein the conduit comprises an expandable support and at least one fluid impermeable membrane coupled to the expandable support.

59. A driver system for a circulatory assist device positionable in a vessel of a patient, the circulatory assist device having an inflatable member operable at a variable inflation frequency to produce a selected blood flow rate, the driver system comprising: a driver chamber fillable with an inflation fluid, the driver chamber having an operating chamber volume and an outlet; a driving mechanism operable to cyclically change the operating chamber volume between a high volume state and a low volume state at a driver frequency, wherein a displacement volume of inflation fluid is displaced from the driver chamber through the outlet in each cycle; and a controller coupled to the driving mechanism and configured to vary the displacement volume so as to produce the selected blood flow rate.

60. The system of claim 59, wherein the driving mechanism comprises a movable divider in the chamber, wherein the divider is movable through a stroke length between the high volume state and the low volume state, wherein the controller is configured to vary the stroke length to vary the displacement volume.

61. The system of claim 60, wherein the divider comprises a driving rod coupled to the divider.

62. The system of claim 61, wherein the divider comprises a membrane.

63. The system of claim 62, wherein the driving mechanism comprises a plunger or piston coupled to the membrane.Attorney Docket No.: CDB.016WO64. The system of any one of claims 59-63, wherein the controller is configured to vary the displacement volume based on one or more parameters selected from inflation fluid pressure, inflation frequency, blood pressure in the vessel, blood flow rate in the vessel, current power consumption by the driver system, one or more pressure measurements within the driver system, one or more flow rate measurements within the driver system.

65. The system of any one of claims 59-64, further comprising a pressure sensor configured to measure a pressure of the inflation fluid in the driver chamber, wherein the controller is configured to adjust the displacement volume based on a signal from the pressure sensor.

66. The system of any one of claims 59-65, further comprising at least one flow rate sensor configured to measure a blood flow rate provided by the circulatory assist device, wherein the controller is configured to adjust the displacement volume based on the measured blood flow rate.

67. The system of claim 66, wherein the at least one flow rate sensor comprises one or more sensors configured to measure a differential pressure of inflation fluid within the driver system, wherein the blood flow rate is calculated by the differential pressure measurement.

68. The system of any one of claims 59-67, wherein the controller is configured to vary the displacement volume in accordance with a linear relationship between the blood flow rate and the driving frequency.

69. The system of any one of claims 59-68, wherein the controller is further configured to vary the driving frequency.

70. A driver system for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device comprises a volume displacement member with an expandable chamber and the volume displacement member is movable between an expansion phase in which the expandable chamber has a firstAttorney Docket No.: CDB.016WO volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the driver system comprises: a driver chamber with an operating chamber volume fillable with an inflation fluid, wherein the operating chamber volume is at least partially defined by a flexible membrane; a driving mechanism configured to cyclically decrease and increase the operating chamber volume by moving the membrane between a fully pressurizing configuration and a fully depressurizing configuration; a fluid flow line configured to convey inflation fluid between the operating chamber volume and the expandable chamber; and a controller configured to control the driving mechanism such that inflation fluid is conveyed between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase, thereby regulating a pumping throughput of the circulatory assist device.

71. The system of claim 70, wherein the membrane is coupled to a plunger, wherein the plunger is movable by the driving mechanism.

72. The system of claim 71, wherein the membrane is coupled to a periphery of the plunger.

73. The system of claim 72, wherein the membrane comprises an inner edge coupled to the periphery of the plunger and an outer edge coupled to a wall at least partially defining the operating chamber volume.

74. The system of claim 73, wherein the inner edge and the outer edge of the membrane are farther apart when the membrane is in the fully pressurizing configuration than when the membrane is in the fully depressurizing configuration.

75. The system of any one of claims 70-74, wherein the membrane is actuated between the fully pressurizing configuration and the fully depressurizing configuration without a direct mechanical link between the driving mechanism and the membrane.Attorney Docket No.: CDB.016WO76. The system of claim 73, wherein the membrane forms a bladder configured to form a circumferential seal against the wall at least partially defining the operating chamber volume.

77. A driver system for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device comprises a volume displacement member with an expandable chamber and the volume displacement member is movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the driver system comprises: a driver chamber with an operating chamber volume fillable with an inflation fluid, wherein the operating chamber volume is at least partially defined by a movable surface; a driving mechanism configured to cyclically decrease and increase the operating chamber volume with a magnetic coupling between the driving mechanism and the movable surface; a fluid flow line configured to convey inflation fluid between the operating chamber volume and the expandable chamber; and a controller configured to control the driving mechanism such that inflation fluid is conveyed between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase, thereby regulating a pumping throughput of the circulatory assist device.

78. The system of claim 77, wherein the driver chamber comprises a housing, and wherein the movable surface is on a movable divider arranged within the housing.

79. The system of claim 78, wherein the movable divider comprises one or more magnetic coupling discs.

80. The system of claim 79, wherein the movable surface comprises a flexible membrane.Attorney Docket No.: CDB.016WO81. The system of claim 77, wherein the driver chamber comprises a housing, and wherein the movable surface is a wall of the housing.

82. A driver system for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device comprises a volume displacement member with an expandable chamber and the volume displacement member is movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the driver system comprises: a driver chamber comprising a housing at least partially defining an operating chamber volume fillable with an inflation fluid; a driving mechanism configured to cyclically contract and expand the housing; a fluid flow line configured to convey inflation fluid between the operating chamber volume and the expandable chamber; and a controller configured to control the driving mechanism such that inflation fluid is conveyed between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase, thereby regulating a pumping throughput of the circulatory assist device.

83. The system of claim 82, wherein the housing comprises a bellows.

84. The system of claim 82 or 83, wherein the housing comprises one or more pleats.

85. The system of any one of claims 82-84, wherein the housing comprises one or more hinge joints.

86. The system of any one of claims 82-85, further comprising a filler material sized and shaped to occupy at substantial portion of the interior of the operating chamber volume.Attorney Docket No.: CDB.016WO87. A driver system for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device comprises a volume displacement member with an expandable chamber and the volume displacement member is movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the driver system comprises: a driver chamber configured to be in fluidic communication with a reservoir containing an inflation fluid, wherein the driver chamber comprises an operating chamber volume fillable with the inflation fluid; a fluid flow line configured to convey inflation fluid to and from the expandable chamber; one or more sensors configured to provide a sensor signal indicative of a status of the inflation fluid in at least one of the driver chamber, the fluid flow line, or the hub; and a controller configured to (i) operate the driver chamber such that inflation fluid is conveyed between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase at the driving frequency, thereby regulating a pumping throughput of the circulatory assist device, and (ii) modulate a flow rate of the inflation fluid from the reservoir to the driver chamber based at least in part on the sensor signal.

88. The system of claim 87, further comprising a hub configured to be in fluidic communication with the driver chamber, the fluidic flow line, and the reservoir containing the inflation fluid.

89. The system of claim 87 or 88, wherein the controller is further configured to at least partially evacuate inflation fluid from one or more of the driver chamber, the fluid flow line, or the volume displacement member.

90. The system of any one of claims 87-89, wherein the controller is configured to at least partially evacuate inflation fluid from the driver chamber, the fluid flow line, and the volume displacement member in response to a detected adverse event.Attorney Docket No.: CDB.016WO91. The system of claim 90, wherein the one or more sensors comprises a pressure sensor.

92. A driver system for actuating a circulatory assist device positionable in a patient’s heart or blood vessel, wherein the circulatory assist device comprises a volume displacement member with an expandable chamber and the volume displacement member is movable between an expansion phase in which the expandable chamber has a first volume and a contraction phase in which the expandable chamber has a second volume less than the first volume, wherein the driver system comprises: a driver chamber configured to be in fluidic communication with a negative pressure source, wherein the driver chamber comprises an operating chamber volume fillable with the inflation fluid; a fluid flow line configured to convey inflation fluid to and from the expandable chamber; one or more sensors configured to provide a sensor signal indicative of a status of the inflation fluid in at least one of the driver chamber, the fluid flow line, or the hub; one or more valves configured to control a flow of the inflation fluid to the negative pressure source; and a controller configured to operate the one or more valves to modulate the flow of the inflation fluid to the negative pressure source in response to the sensor signal.

93. The system of claim 92, wherein the one or more valves comprises a plurality of valves arranged in parallel.

94. The system of claim 92 or 93, wherein the controller is further configured to operate the one or more valves to at least partially evacuate inflation fluid from one or more of the driver chamber, the fluid flow line, or the volume displacement member.

95. The system of any one of claims 92-94, further comprising a hub configured to be in fluidic communication with the driver chamber, the fluidic flow line, and a reservoir containing the inflation fluid.Attorney Docket No.: CDB.016WO96. The system of any one of claims 92-95, wherein the controller is configured to operate the driver chamber such that inflation fluid is conveyed between the operating chamber volume and the expandable chamber to cyclically move the volume displacement member between the expansion phase and the contraction phase at the driving frequency, thereby regulating a pumping throughput of the circulatory assist device.

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