Patent ID: 12251550

DETAILED DESCRIPTION

The blood pump system of the present invention is particularly well-suited for use as an implantable left ventricular assist device (LVAD), and includes an undulating membrane pump suitable for long-term implantation in a patient having end term heart failure. A blood pump system constructed in accordance with the principles of the present invention includes a blood pump and an extracorporeal battery, controller and programmer. The blood pump system of the present invention may be implantable and/or may be a heart pump (e.g., LVAD). The blood pump includes a housing having an inlet, and outlet, a flexible membrane, and an encapsulated actuator assembly. When configured as an LVAD, the housing includes an inlet cannula that is inserted into a patient's left ventricle near the apex and an outlet cannula that is surgically placed in fluid communication with the patient's aorta. By activating the actuator assembly within the blood pump, the membrane is induced to undulate, thereby causing blood to be drawn into the pump through the inlet cannula and expelled through the outlet cannula into the aorta. Flow rate and pulsatility may be manipulated by changing one or more of the frequency, amplitude and duty cycle of the actuator assembly.

For improved hydraulic performance, the blood pump may include a membrane assembly including a membrane and skirt disposed within the housing to guide blood flow from the inlet of the pump towards the outlet. The skirt may be positioned within the housing such that blood flows across opposing sides of the skirt and towards the undulating membrane upon activation of the pump. For enhanced protection of blood flowing through the blood pump, the actuator assembly may be encapsulated using an encapsulation assembly such that a blood flow channel between the inlet cannula and the outlet cannula of the blood pump is defined by the encapsulation assembly and an interior surface of the housing of the blood pump.

Referring now toFIG.1, pump system10constructed in accordance with the principles of the present invention is described. Blood pump system10includes pump20, controller30, battery40, programmer50and optionally, a software module programmed to run on mobile device60. Pump20is configured to be implanted within a patient's chest so that inlet cannula21is coupled to left ventricle LV of heart H. Outlet cannula22of pump20is configured to be coupled to aorta A. Inlet cannula21preferably is coupled to the apex of left ventricle LV, while outlet cannula22is coupled to aorta A in the vicinity of the ascending aorta, above the level of the cardiac arteries. Pump20may be affixed within the patient's chest using a ring-suture or other conventional technique. Outlet cannula22, which may comprise a Dacron graft or other synthetic material, is coupled to outlet23of implantable pump20.

Referring now also toFIG.2, pump20in a preferred embodiment consists of upper housing portion24joined to lower housing portion25along interface26, for example, by threads or welding, to form fluid tight pump housing27that may have a cylindrical shape. Upper housing portion24includes inlet cannula21and electrical conduit28for receiving electrical wires from controller30and battery40. Lower housing portion25includes outlet23that couples to outlet cannula22, as shown inFIG.1. Pump housing27is made of a biocompatible material, such as stainless steel or titanium, and is sized to be implanted within a patient's chest.

Referring again toFIG.1, in one embodiment, controller30and battery40are extracorporeal, and are sized so as to be placed on a belt or garment worn by the patient. Both controller30and battery40are electrically coupled to pump20, for example, via cable29that extends through a percutaneous opening in the patient's skin and into electrical conduit28of pump housing27. Illustratively, battery40is electrically coupled to controller30via cable41that is integrated into belt42. In an alternative embodiment, controller30may be enclosed within a biocompatible housing and sized to be implanted subcutaneously in the patient's abdomen. In this alternative embodiment, controller30may include a wireless transceiver for bi-directional communications with an extracorporeal programming device and also includes a battery that is continuously and inductively charged via extracorporeal battery40and an extracorporeal charging circuit. As will be understood, the foregoing alternative embodiment avoids the use of percutaneous cable29, and thus eliminates a frequent source of infection for conventional LVAD devices.

Battery40preferably comprises a rechargeable battery capable of powering pump20and controller30for a period of several hours, e.g., 4-12 hours, before needing to be recharged. Battery40may include a separate charging circuit, not shown, as is conventional for rechargeable batteries. Battery40preferably is disposed within a housing suitable for carrying on a belt or holster, so as not to interfere with the patient's daily activities.

Programmer50may consist of a conventional laptop computer that is programmed to execute programmed software routines, for use by a clinician or medical professional, for configuring and providing operational parameters to controller30. The configuration and operational parameter data are stored in a memory associated with controller30and used by the controller to control operation of pump20. As described in further detail below, controller30directs pump20to operate at specific parameters determined by programmer50. Programmer50preferably is coupled to controller30via cable51only when the operational parameters of the pump are initially set or periodically adjusted, e.g., when the patient visits the clinician.

In accordance with another aspect of the invention, mobile device60, which may a conventional smartphone, may include an application program for bi-directionally and wirelessly communicating with controller30, e.g., via WiFi or Bluetooth communications. The application program on mobile device60may be programmed to permit the patient to send instructions to controller to modify or adjust a limited number of operational parameters of pump20stored in controller30. Alternatively or in addition, mobile device60may be programmed to receive from controller30and to display on screen61of mobile device60, data relating to operation of pump20or alert or status messages generated by controller30.

With respect toFIGS.3A and3B, controller30is described in greater detail. As depicted inFIG.1, controller30may be sized and configured to be worn on the exterior of the patient's body and may be incorporated into a garment such as a belt or a vest. Controller30includes input port31, battery port32, output port33, indicator lights34, display35, status lights36and buttons37.

Input port31is configured to periodically and removably accept cable51to establish an electrical connection between programmer50and controller30, e.g., via a USB connection. In this manner, a clinician may couple to controller30to set or adjust operational parameters stored in controller30for controlling operation of pump. In addition, when programmer50is coupled to controller30, the clinician also may download from controller30data relating to operation of the pump, such as actuation statistics, for processing and presentation on display55of programmer50, illustrated inFIG.5A. Alternatively, or in addition, controller30may include a wireless transceiver for wirelessly communicating such information with programmer50. In this alternative embodiment, wireless communications between controller30and programmer50may be encrypted with an encryption key associated with a unique identification number of the controller, such as a serial number.

Battery port32is configured to removably accept cable41, illustratively shown inFIG.1as integrated with belt42, so that cable41routed through the belt and extends around the patient's back until it couples to controller30. In this manner, battery40may be removed from belt42and disconnected from controller30to enable the patient to periodically replace the battery with a fully charged battery. It is expected that the patient will have available to him or her at least two batteries, so that while one battery is coupled to controller30to energize the controller and pump, the other battery may be connected to a recharging station. Alternatively, or in addition, battery port32may be configured to accept a cable that is coupled directly to a power supply, such a substantially larger battery/charger combination that permits the patient to remove battery40while lying supine in a bed, e.g., to sleep.

Output port33is electrically coupled to cable29, which in turn is coupled to pump20through electrical conduit28of pump housing27. Cable29provides both energy to energize pump20in accordance with the configuration settings and operational parameters stored in controller30, and to receive data from sensors disposed in pump20. In one embodiment, cable29may comprise an electrical cable having a biocompatible coating and is designed to extend percutaneously. Cable29may be impregnated with pharmaceuticals to reduce the risk of infection, the transmission of potentially hazardous substances or to promote healing where it extends through the patient's skin and tissue.

As mentioned above, controller30may include indicator lights34, display35, status lights36and buttons37. Indicator lights34may visually display information relevant to operation of the system, such as the remaining life of battery40. Display35may be a digital liquid crystal display that displays real time pump performance data, physiological data of the patient, such as heart rate, or operational parameters of the pump, such as the target pump pressure or flow rate, etc. When it is determined that certain parameter conditions exceed preprogrammed thresholds, an alarm may be sounded, an alert may be displayed on display35and/or an internal vibrating element may vibrate controller30to provide tactile stimulation. Status lights36may comprise light emitting diodes (LEDs) that are turned on or off to indicate whether certain functionality of the controller or pump is active. Buttons37may be used to wake up display35, to set or quiet alarms, etc.

With respect toFIG.3B, the components of the illustrative embodiment of controller30ofFIG.3Aare described. In addition to the components of controller30described in connection withFIG.3A, controller30further includes microprocessor38, memory39, battery43, optional transceiver44and amplifier circuitry45. Microprocessor may be a general purpose microprocessor, for which programming to control operation of pump20is stored in memory39. Memory39also may store configuration settings and operational parameters for pump20. Battery43supplies power to controller30to provide continuity of operation when battery40is periodically swapped out. Optional transceiver44(e.g., communication unit) facilitates wireless communication with programmer50and/or mobile device60via any of a number of well-known communications standards, including BLUETOOTH™, ZigBee, and/or any IEEE 802.11 wireless standard such as Wi-Fi or Wi-Fi Direct. Controller30further may include amplifier circuitry49for amplifying electrical signals transferred between controller30and pump20.

Referring now toFIG.4, battery40is described. Battery40provides power to pump20and also may provide power to controller30. Battery40may consist of a single battery or a plurality of batteries disposed within a housing, and preferably is sized and configured to be worn on the exterior of the patient's body, such as on belt42. Battery life indicator46may be provided on the exterior of battery40to indicate the amount of the remaining charge of the battery. Cable41may have one end removably coupled to battery40and the other end removably coupled to battery port32of controller30to supply power to energize pump20. In one embodiment, battery40may be rechargeable using a separate charging station, as is known in the art of rechargeable batteries. Alternatively, or in addition, battery40may include port47which may be removably coupled to a transformer and cable to permit the battery to be recharged using a conventional residential power outlet, e.g., 120 V, 60 Hz AC power.

Referring now toFIGS.5A-5B, programmer50is described. Programmer50may be a conventional laptop or tablet computer loaded with programmed software routines for configuring controller30and setting operational parameters that controller30uses to control operation of pump20. As discussed above, programmer50typically is located in a clinician's office or hospital, and is coupled to controller30via cable51or wirelessly to initially set up controller30, and then periodically thereafter as required to adjust the operational parameters as may be needed. The operation parameters of controller30set using the programmed routines of programmer50may include but are not limited to pump operating mode, applied voltage, pump frequency, pump amplitude, target flow rate, pulsatility, etc. When first implanted, the surgeon or clinician may use programmer50to communicate initial operating parameters to controller30. Following implantation, the patient periodically may return to the clinician's office for adjustments to the operational parameters which may again be made using programmer50.

Programmer50may be any type of conventional personal computer device such as a laptop or a tablet computer having touch screen capability. As illustrated inFIG.5B, programmer50preferably includes processor52, memory53, input/output device54, display55, battery56and communication unit57. Memory53may include the operating system for the programmer, as well as the programmed routines needed to communicate with controller30. Communication unit57may include any of a number of well-known communication protocols, such as BLUETOOTH™, ZigBee, and/or any IEEE 802.11 wireless standard such as Wi-Fi or Wi-Fi Direct. As illustrated inFIG.5A, the programmed routines used to program and communicate with controller30also may provide data for display on the screen of programmer50identifying operational parameters with which controller30controls pump20. The programmed routines also may enable programmer50to download from controller30operational data or physiologic data communicated by the pump and to display that information in real time while the programmer is coupled to the controller via a wired or wireless connection. The transferred data may then be processed and displayed on the screen of programmer50.

Referring now toFIGS.6and7, a preferred embodiment of pump assembly70and pump20are illustrated. However, it is understood that pump assemblies and pumps, and components included therein, may have different shapes and sizes than those illustrated inFIGS.6and7without departing from the invention described herein. As is illustrated inFIG.7, pump assembly70is configured to fit within pump housing27. To fix pump assembly70within pump housing27, pump assembly70may include fixation ring71, which may extend from and around stator assembly72, and may be captured between upper housing portion24and lower housing portion25when the housing portions are assembled, as illustrated inFIG.7. In this manner, stator assembly72may be suspended within the pump housing in close-fitting relation to the interior walls of the pump housing. Fixation ring71preferably is a rigid annular structure that is disposed concentrically around stator assembly72, having a larger diameter than stator assembly72. Fixation ring71may be rigidly coupled to stator assembly72via struts73. Struts73may create gap74between fixation ring71and stator assembly72, which preferably is about 0.05 mm at its most restricted point.

As shown inFIG.7, pump assembly70may be disposed in pump housing27such that fixation ring71is captured on step75formed between upper housing portion24and lower housing portion25. In this manner, stator assembly72may be suspended within, and prevented from moving within, pump housing27. Pump housing27preferably is sized and configured to conform to pump assembly70such that, stator assembly72does not contact the interior of the pump housing at any location other than at fixation ring71.

FIG.8is an exploded view of pump20, depicting the arrangement of the internal components of pump assembly70arranged between upper housing portion24and lower housing portion25. In particular, pump assembly70may comprise stator assembly72, magnetic ring assembly76, first electromagnetic coil77, second electromagnetic coil78, fixation ring71, first suspension ring79, second suspension ring80, posts81and membrane assembly82. Stator assembly72may comprise tapered section83, electromagnetic coil holder portions84,85and86, and flanged portion87. Magnetic ring assembly76may comprise magnetic ring88and magnetic ring holder portions89and90. First and second electromagnetic coils77and78, together with electromagnetic coil holder portions84,85and86may form electromagnetic assembly91. Electromagnetic assembly91together with stator assembly72form an actuator assembly. The actuator assembly together with magnetic ring assembly76in turn forms the actuator system of pump20.

First electromagnetic coil77and second electromagnetic coil78may be concentrically sandwiched between electromagnetic coil holder portions84,85and86to form electromagnetic assembly91. Tapered section83, which may be coupled to fixation ring71and first suspension spring79, may be located concentrically atop electromagnetic assembly91. Magnetic ring88may be disposed with magnetic ring holder portions89and90to form magnetic ring assembly76, which may be concentrically disposed for reciprocation over electromagnetic assembly91. Second suspension ring80may be disposed concentrically beneath electromagnetic assembly91. Flanged portion87may be concentrically disposed below second suspension ring80. Posts81may engage first suspension ring79, magnetic ring assembly76and second suspension ring80at equally spaced locations around the actuator assembly. Membrane assembly82may be positioned concentrically below flanged portion87and engaged with posts81.

Further details of pump assembly70are provided with respect toFIG.9. Specifically, actuator assembly95comprises stator assembly72and electromagnetic assembly91, including first and second electromagnetic coils77and78. During use of pump20, actuator assembly95remains stationary relative to pump housing27. First electromagnetic coil77and second electromagnetic coil78may be separated by electromagnetic holder portion85. Controller30and battery40are electrically coupled to electromagnetic coils77and78via cable29that extends through electrical conduit28of pump housing27to supply current to electromagnetic coils77and78. First electromagnetic coil77and second electromagnetic coil78may be in electrical communication with one another or may be configured to operate independently and have separate wired connections to controller30and battery40via cable29.

Electromagnetic coils77and78may be made of any electrically conductive metallic material such as copper and further may comprise of one or more smaller metallic wires wound into a coil. The wires of the electromagnetic coils are insulated to prevent shorting to adjacent conductive material. Other components of pump assembly70, such as stator assembly72, preferably also are insulated and/or made of non-conductive material to reduce unwanted transmission of the electrical signal.

Actuator assembly95may be surrounded by first suspension ring79and second suspension ring80. Suspension rings79and80may be annular in shape and fit concentrically around actuator assembly95. First suspension ring79preferably is rigidly affixed to tapered section83near a top portion of stator assembly72via struts73extending from the suspension ring to the stator assembly. As discussed above, struts73may also affix fixation ring71to stator assembly72. Fixation ring71and first suspension spring79may be sized and positioned such that a gap of no less than 0.5 mm exists between first suspension ring79and fixation ring71. Second suspension ring80similarly may be rigidly affixed via struts near the bottom of stator assembly72, below electromagnetic assembly91. Suspension rings79and80preferably are sized and shaped such that when suspension rings79and80are positioned surrounding actuator assembly95, a gap of no less than 0.5 mm exists between actuator assembly95and suspension rings79and80.

First suspension ring79and second suspension ring80may comprise stainless steel, titanium, or cobalt chromium alloys having elastic properties and which exhibits a spring force when deflected in a direction normal to the plane of the spring. First suspension ring79and second suspension ring80may be substantially rigid with respect to forces applied tangential to the suspension ring. In this manner, first suspension ring79and second suspension ring80may exhibit a spring tension when deformed up and down relative to a vertical axis of the actuator assembly but may rigidly resist movement along any other axis, e.g., tilt or twist movements.

Magnetic ring assembly76may be annular in shape and concentrically surrounds actuator assembly95. Magnetic ring88may comprise one or more materials exhibiting magnetic properties such as iron, nickel, cobalt or various alloys. Magnetic ring88may be made of a single unitary component or comprise several magnetic components that are coupled together. Magnetic ring assembly76may be sized and shaped such that when it is positioned concentrically over actuator assembly95, a gap of no less than 0.5 mm exists between an outer lateral surface of actuator assembly95and an interior surface of magnetic ring assembly76.

Magnetic ring assembly76may be concentrically positioned around actuator assembly95between first suspension ring79and second suspension ring80, and may be rigidly coupled to first suspension ring79and second suspension ring80. Magnetic ring assembly76may be rigidly coupled to the suspension rings by more than one post81spaced evenly around actuator assembly95and configured to extend parallel to a central axis of pump assembly70. Suspension rings79and80and magnetic ring assembly76may be engaged such that magnetic ring assembly76is suspended equidistant between first electromagnetic coil77and second electromagnetic coil78when the suspension rings are in their non-deflected shapes. Each of suspension rings79and80and magnetic ring holder portions89and90may include post receiving regions for engaging with posts81or may be affixed to posts81in any suitable manner that causes suspension rings79and80and magnetic ring assembly76to be rigidly affixed to posts81. Posts81may extend beyond suspension rings79and80to engage other components, such as flanged portion87and membrane assembly82.

First electromagnetic coil77may be activated by controller applying an electrical signal from battery40to first electromagnetic coil77, thus inducing current in the electromagnetic coil and generating a magnetic field surrounding electromagnetic coil77. The direction of the current in electromagnetic coil77and the polarity of magnetic ring assembly76nearest electromagnetic coil77may be configured such that the first electromagnetic coil magnetically attracts or repeals magnetic ring assembly76as desired. Similarly, a magnetic field may be created in second electromagnetic coil78by introducing a current in the second electromagnetic coil. The direction of the current in second electromagnetic coil78and the polarity of magnetic ring assembly76nearest the second electromagnetic coil also may be similarly configured so that first electromagnetic coil77magnetically attracts or repels magnetic ring assembly76when an appropriate current is induced in second electromagnetic coil78.

Because magnetic ring assembly76may be rigidly affixed to posts81, which in turn may be rigidly affixed to first suspension ring79and second suspension ring80, the elastic properties of the suspension rings permit magnetic ring assembly76to move up towards first electromagnetic coil77or downward toward second electromagnetic coil78, depending upon the polarity of magnetic fields generated by the electromagnetic rings. In this manner, when magnetic ring assembly76experiences an upward magnetic force, magnetic ring assembly76deflects upward towards first electromagnetic coil77. As posts81move upward with magnetic ring assembly76, posts81cause the suspensions rings79and80to elastically deform, which creates a spring force opposite to the direction of movement. When the magnetic field generated by the first electromagnetic coil collapses, when the electrical current ceases, this downward spring force causes the magnetic ring assembly to return to its neutral position. Similarly, when magnetic ring assembly76is magnetically attracted downward, magnetic ring assembly76deflects downward towards second electromagnetic ring78. As posts81move downward with magnetic ring assembly76, posts81impose an elastic deformation of the first and second suspension rings, thus generating a spring force in the opposite direction. When the magnetic field generated by the second electromagnetic ring collapses, when the electrical current ceases, this upward spring force causes the magnetic ring assembly to again return to its neutral position.

Electromagnetic coils77and78may be energized separately, or alternatively, may be connected in series to cause the electromagnetic coils to be activated simultaneously. In this configuration, first magnetic coil may be configured to experience a current flow direction opposite that of the second electromagnetic coil. Accordingly, when current is induced to first electromagnetic coil77to attract magnetic ring assembly76, the same current is applied to second electromagnetic coil78to induce a current that causes second electromagnetic coil78to repel magnetic ring assembly76. Similarly, when current is induced to second electromagnetic coil78to attract magnetic ring assembly76, the current applied to first electromagnetic coil77causes the first electromagnetic coil to repel magnetic ring assembly76. In this manner, electromagnetic coils77and78work together to cause deflection of magnetic ring assembly76.

By manipulating the timing and intensity of the electrical signals applied to the electromagnetic coils, the frequency at which magnetic ring assembly76deflects towards the first and second electromagnetic coils may be altered. For example, by alternating the current induced in the electromagnetic coils more frequently, the magnetic ring assembly may be caused to cycle up and down more times in a given period. By increasing the amount of current, the magnetic ring assembly may be deflected at a faster rate and caused to travel longer distances.

Alternatively, first electromagnetic coil77and second electromagnetic coil78may be energized independently. For example, first electromagnetic coil77and second electromagnetic coil78may be energized at varying intensities; one may be coordinated to decrease intensity as the other increases intensity. In this manner, intensity of the signal applied to second electromagnetic coil78to cause downward magnetic attraction may simultaneously be increased as the intensity of the signal applied to first electromagnetic coil77causes an upward magnetic attraction that decreases.

In accordance with one aspect of the invention, movements of magnetic ring assembly76may be translated to membrane assembly82which may be disposed concentrically below stator assembly72. Membrane assembly82preferably is rigidly attached to magnetic ring assembly76by posts81. In the embodiment depicted inFIG.9, posts81may extend beyond second suspension ring80and coupled to membrane assembly82.

Referring now toFIG.10, one embodiment of membrane assembly82is described in greater detail. Membrane assembly82may comprise rigid membrane ring96and membrane97. Rigid membrane ring96exhibits rigid properties under typical forces experienced during the full range of operation of the present invention. Post reception sites98may be formed into rigid membrane ring96to engage membrane assembly82with posts81. Alternatively, posts81may be attached to rigid membrane ring96in any other way which directly translates the motion of magnetic ring assembly76to rigid membrane ring96. Rigid membrane ring96may be affixed to membrane97and hold the membrane in tension. Membrane97may be molded directly onto rigid membrane ring96or may be affixed to rigid membrane ring96in any way that holds membrane97uniformly in tension along its circumference. Membrane97alternatively may include a flexible pleated structure where it attaches to rigid membrane ring96to increase the ability of the membrane to move where the membrane is affixed to rigid membrane ring96. Membrane97may further include circular aperture99disposed in the center of the membrane.

In a preferred embodiment, membrane97has a thin, planar shape and is made of an elastomer having elastic properties and good durability. Alternatively, membrane97may have a uniform thickness from the membrane ring to the circular aperture. As a yet further alternative, membrane97may vary in thickness and exhibit more complex geometries. For example, as shown inFIG.10, membrane97may have a reduced thickness as the membrane extends from rigid membrane ring96to circular aperture99. Alternatively, or in addition to, membrane97may incorporate metallic elements such as a spiral spring to enhance the spring force of the membrane in a direction normal to plane of the membrane, and this spring force may vary radially along the membrane. In yet another embodiment, membrane97may be pre-formed with an undulating shape.

FIG.11depicts moving portions of the embodiment of pump assembly70shown inFIGS.6-9as non-grayed out elements. Non-moving portions of the pump assembly, including actuator assembly95and electromagnetic assembly91(partially shown) may be fixed to pump housing27by fixation ring71. Moving portions of pump assembly70may include posts81, first suspension spring79, magnetic ring assembly76, second suspension spring80and membrane assembly82. As magnetic ring assembly76moves up and down, the movement is rigidly translated by posts81to membrane assembly82. Given the rigidity of the posts, when magnetic ring assembly76travels a certain distance upward or downward, membrane assembly82may travel the same distance. For example, when magnetic ring assembly76travels 2 mm from a position near first electromagnetic coil77to a position near second electromagnetic coil78, membrane assembly82may also travel 2 mm in the same direction. Similarly, the frequency at which magnetic ring assembly76traverses the space between the first and second electromagnetic coils may be the same frequency at which membrane assembly82travels the same distance.

Referring now toFIG.12, in the embodiment of pump20described inFIGS.6-9, blood may enter pump20from the left ventricle through inlet cannula21and flow downward along pump assembly70into delivery channel100, defined by the interior surface of pump housing27and exterior of pump assembly70. Delivery channel100begins at the top of stator assembly72and extends between tapered section83and the interior of pump housing27. As the blood moves down tapered section83, it is directed through gap74and into a vertical portion of delivery channel100in the area between pump housing27and actuator assembly95, and including in the gap between magnetic ring assembly76and electromagnetic assembly91. Delivery channel100extends down to flanged portion87of stator assembly72, which routes blood into flow channel101, within which membrane assembly82is suspended. By directing blood from inlet cannula21through delivery channel100to flow channel101, delivery channel100delivers blood to membrane assembly82. By actuating electromagnetic coils77and78, membrane97may be undulated within flow channel101to induce wavelike formations in membrane97that move from the edge of the membrane towards circular aperture99. Accordingly, when blood is delivered to membrane assembly82from delivery channel100, it may be propelled radially along both the top and bottom of membrane97towards circular aperture99, and from there out of outlet23.

In accordance with one aspect of the present invention, the undulating membrane pump described herein reduces thrombus formation by placing moving parts directly within the primary flow path, thereby reducing the risk of flow stagnation. Specifically, the moving components depicted inFIG.11, including magnetic ring assembly76, suspension rings79and80, posts81and membrane assembly82all are located within delivery channel100and flow channel101. Flow stagnation may further be avoided by eliminating secondary flow paths that may experience significantly slower flow rates. The width of the fluid passages, i.e., delivery channel100and flow channel101, may be optimized to minimize blood exposure to shear conditions. The flow channels may be sized and shaped to optimize hydraulic performance. Specifically, flow channel101may be sized and configured to facilitate blood flow towards the outlet and resist blood flow towards the inlet. It is understood that the size and shape of flow channels may affect blood flow through the pump and that an optimal size and shape may be selected to optimize hydraulic performance. For example, the size and shape of flow channels may be optimized to resist backflow and recirculation while permitting forward flow; thus, backflow is resisted without choking of the forward flow.

Turning now toFIGS.13and14, a lower portion of pump20, including flanged portion87, membrane assembly82and lower housing portion25is shown. Delivery channel100may be in fluid communication with membrane assembly82and flow channel101which is defined by a bottom surface of flanged portion87and the interior surface of lower housing portion25. Flanged portion87may comprise feature102that extends downward as the bottom of flanged portion87moves radially inward. The interior surface of lower housing portion25may also slope upward as it extends radially inward. The combination of the upward slope of the interior surface of lower housing portion25and the bottom surface of flanged portion87moving downward narrows flow channel101as the channel moves radially inwards from delivery channel100to circular aperture99of membrane97, which is disposed about pump outlet23.

As explained above, membrane assembly82may be suspended by posts81within flow channel101below the bottom surface of flanged portion87and above the interior surface of lower housing portion25. Membrane assembly82may be free to move up and down in the vertical direction within flow channel101, which movement is constrained only by suspension rings79and80. Membrane assembly82may be constrained from twisting, tilting or moving in any direction in flow channel101other than up and down by rigid posts81and by the suspension rings.

Flow channel101is divided by membrane97into an upper flow channel and a lower flow channel by membrane97. The geometry of membrane97may be angled such that when membrane assembly82is at rest, the top surface of membrane97is parallel to the bottom surface of flanged portion87and the bottom surface of membrane97is parallel to the opposing surface of lower housing portion25. Alternatively, membrane97may be sized and shaped such that when membrane assembly82is at rest, the upper and lower flow channels narrow as they move radially inward from delivery channel100to circular aperture99in membrane97.

Referring now also toFIG.14, as rigid membrane ring96is caused by posts81to move up and down in flow channel101, the outermost portion of membrane97nearest rigid membrane ring96, moves up and down with rigid membrane ring96. Membrane97, being flexible and having elastic properties, gradually translates the up and down movement of the membrane portion nearest rigid membrane ring96along membrane97towards circular aperture99. This movement across flexible membrane97causes wavelike deformations in the membrane which may propagate inwards from rigid membrane ring96towards aperture99.

The waves formed in the undulating membrane may be manipulated by changing the frequency at which rigid membrane ring96moves up and down as well as the distance rigid membrane ring96moves up and down. As explained above, the amplitude and frequency at which rigid membrane ring96moves up and down is determined by the amplitude and frequency at which magnetic ring assembly76reciprocates over electromagnetic assembly91. Accordingly, the waves formed in the undulating membrane may be adjusted by changing the frequency and amplitude at which magnetic ring assembly76is reciprocated.

When blood is introduced into flow channel101from delivery channel100, the undulations in membrane97cause blood to be propelled toward circular aperture99and out of pump housing27via outlet23. The transfer of energy from the membrane to the blood is directed radially inward along the length of the membrane towards aperture99, and propels the blood along the flow channel towards outlet23along both sides of membrane97.

For example, when rigid membrane ring96moves downward in unison with magnetic ring assembly76, the upper portion of flow channel101near delivery channel100expands, causing blood from delivery channel100to fill the upper portion of the flow channel near the outer region of membrane97. As rigid membrane ring96moves upward, the upper portion of flow channel101begins to narrow near rigid membrane ring96, causing wave-like deformations to translate across the membrane. As the wave propagates across membrane97, blood in the upper portion of flow channel101is propelled towards circular aperture and ultimately out of pump housing27through outlet23. Simultaneously, as rigid membrane ring96moves upwards, the lower portion of flow channel101nearest the outer portion of membrane97begins to enlarge, allowing blood from delivery channel100to flow into this region. Subsequently, when rigid membrane ring96is again thrust downwards, the region of lower portion of flow channel101nearest outer portion of membrane97begins to narrow, causing wave-like deformations to translate across the membrane that propel blood towards outlet23.

By manipulating the waves formed in the undulating membrane by changing the frequency and amplitude at which magnetic ring assembly76moves up and down, the pressure gradient within flow channel101and ultimately the flow rate of the blood moving through flow channel101may be adjusted. Appropriately controlling the movement of magnetic ring assembly76permits oxygen-rich blood to be effectively and safely pumped from the left ventricle to the aorta and throughout the body as needed.

In addition to merely pumping blood from the left ventricle to the aorta, pump20of the present invention may be operated to closely mimic physiologic pulsatility, without loss of pump efficiency. In the embodiment detailed above, pulsatility may be achieved nearly instantaneously by changing the frequency and amplitude at which magnetic ring assembly76moves, to create a desired flow output, or by ceasing movement of the magnetic ring assembly for a period time to create a period of low or no flow output. Unlike typical rotary pumps, which require a certain period of time to attain a set number of rotations per minute to achieve a desired fluid displacement and pulsatility, pump20may achieve a desired flow output nearly instantaneously and similarly may cease output nearly instantaneously due to the very low inertia generated by the small moving mass of the moving components of the pump assembly. The ability to start and stop on-demand permits rapid changes in pressure and flow. Along with the frequency and amplitude, the duty cycle, defined by the percentage of time membrane97is excited over a set period of time, may be adjusted to achieve a desired flow output and pulsatility, without loss of pump efficiency. Even holding frequency and amplitude constant, flow rate may be altered by manipulating the duty cycle between 0 and 100%.

In accordance with another aspect of the invention, controller30may be programmed by programmer50to operate at selected frequencies, amplitudes and duty cycles to achieve a wide range of physiologic flow rates and with physiologic hemodynamics. For example, programmer50may direct controller30to operate pump20at a given frequency, amplitude and/or duty cycle during a period of time when a patient is typically sleeping and may direct controller30to operate pump20at a different frequency, amplitude and or duty cycle during time periods when the patient is typically awake. Controller30or pump also may include an accelerometer or position indicator to determine whether the patient is supine or ambulatory, the output of which may be used to move from one set of pump operating parameters to another. When the patient experiences certain discomfort or a physician determines that the parameters are not optimized, physician may alter one or more of at least frequency, amplitude and duty cycle to achieve the desired functionality. Alternatively, controller30or mobile device60may be configured to alter one or more of frequency, amplitude and duty cycle to suit the patient's needs.

Pump20further may comprise one or more additional sensors for adjusting flow output and pulsatility according to the demand of the patient. Sensors may be incorporated into pump20or alternatively or in addition to may be implanted elsewhere in or on the patient. The sensors preferably are in electrical communication with controller30, and may monitor operational parameters that measure the performance of pump20or physiological sensors that measure physiological parameters of the patients such as heart rate or blood pressure. By using one or more physiological sensors, pulsatile flow may be synchronized with a cardiac cycle of the patient by monitoring blood pressure or muscle contractions, for example, and synchronizing the duty cycle according to the sensed output.

Controller30may compare physiological sensor measurements to current pump output. If it is determined by analyzing sensor measurements that demand exceeds current output, frequency, amplitude and/or duty cycle may be automatically adjusted to meet current demand. Similarly, the controller may determine that current output exceeds demand and thus alter output by changing frequency, amplitude and/or duty cycle. Alternatively, or in addition to, when it is determined that demand exceeds current output, an alarm may sound from controller30. Similarly, operational measurements from operational sensors may be compared against predetermined thresholds and where measurements exceed predetermined thresholds or a malfunction is detected, an alarm may sound from controller30.

Pump20is sized and shaped to produce physiological flow rates, pressure gradients and pulsatility at an operating point at which maximum efficiency is achieved. Specially, pump20may be sized and shaped to produce physiological flow rates ranging from 2 to 15 liters per minute at pressure gradients lower than a threshold value associated with hemolysis. Also, to mimic a typical physiological pulse of 60 beats per minute, pump20may pulse about once per second. To achieve such pulsatility, a duty cycle of 20-50% may be utilized with an “on” or “high” period of 0.2-0.5 seconds and an “off” or “low” period of 0.5-0.8 seconds, for example, where a “high” setting represents an operating point of frequency and amplitude resulting in increased blood flow rates against physiologic pressure, whereas a “low” setting represents an operating point of frequency and amplitude resulting in lower blood flow rates against physiologic pressures. For a given system, maximum efficiency at a specific operating frequency, amplitude and voltage may be achieved while producing a flow rate of 2 to 15 liters per minute at a duty cycle of 20-50% by manipulating one or more of the shape and size of blood flow channels, elastic properties of the suspension rings, mass of the moving parts, membrane geometries, and elastic properties and friction properties of the membrane. In this manner, pump20may be designed to produce desirable physiological outputs while continuing to function at optimum operating parameters.

By adjusting the duty cycle, pump20may be configured to generate a wide range of output flows at physiological pressure gradients. For example, for an exemplary LVAD system configured to produce 2 to 15 liters per minute at a duty cycle of 20-50%, optimal operating frequency may be 25-70 Hz or even 120 Hz. For this system, flow output may be increased to 10 liters per minute or decreased to 4 liters per minute, for example, by changing only the duty cycle. As duty cycle and frequency operate independent of one another, duty cycle may be manipulated between 0 and 100% while leaving the frequency unaffected.

The pump system described herein, tuned to achieve physiological flow rates, pressure gradients and pulsatility, also avoids hemolysis and platelet activation by applying low to moderate shear forces on the blood, similar to those encountered by blood elements in the normal, non-diseased vascular system. In the embodiment detailed above, delivery channel100may be sized and configured to also avoid friction between moving magnetic ring assembly76, suspension rings79and80, posts81and lower housing portion25by sizing the channel such that clearances of at least 0.5 mm are maintained between all moving components. Similarly, magnetic ring assembly76, suspension rings79and80, and posts81all may be offset from stator assembly72by at least 0.5 mm to avoid friction between the stator assembly and the moving parts.

Referring now toFIGS.15A and15B, an alternative exemplary embodiment of the pump assembly of the present invention is described. Pump20′ is constructed similar to pump20described inFIGS.7,8, and12, in which similar components are identified with like-primed numbers. Pump20′ is distinct from pump20in that membrane assembly82′ includes skirt115coupled to membrane97′. Skirt illustratively includes first portion115aand second portion115b. First portion115aof skirt115extends upward within delivery channel100′ toward inlet21′ in a first direction, e.g., parallel to the longitudinal axis of stator assembly72′ and/or to the central axis of pump housing27′. Second portion115bof skirt115curves toward outlet23′ such that second portion115bis coupled to membrane97′ so that membrane97′ is oriented in a second direction, e.g., perpendicular to first portion115aof skirt115. For example, skirt115may have a J-shaped cross-section, such that first portion115aforms a cylindrical-shaped ring about stator assembly72′ and second portion115bhas a predetermined radius of curvature which allows blood to flow smoothly from delivery channel100′ across skirt115to the outer edge of membrane97′ and into flow channel101′, while reducing stagnation of blood flow. Skirt115breaks flow recirculation of blood within delivery channel100′ and improves hydraulic power generated for a given frequency while minimizing blood damage. In addition, the J-shape of skirt115around stator assembly72′ may be stiffer than a planar rigid membrane ring, thereby reducing flexing and fatigue, as well as drag as the blood moves across membrane97′.

Skirt115exhibits rigid properties under typical forces experienced during the full range of operation of the present invention and may be made of a biocompatible metal, e.g., titanium. Skirt115is preferably impermeable such that blood cannot flow through skirt115. Post reception sites98′ may be formed into skirt115to engage membrane assembly82′ with posts81′. Alternatively, posts81′ may be attached to skirt115in any other way which directly translates the motion of magnetic ring assembly76′ to skirt115.

As magnetic ring assembly76′ moves up and down, the movement is rigidly translated by posts81′ to J-shape of skirt115of membrane assembly82′. Given the rigidity of the posts, when magnetic ring assembly76′ travels a certain distance upward or downward, membrane assembly82′ may travel the same distance. For example, when magnetic ring assembly76′ travels 2 mm from a position near first electromagnetic coil77′ to a position near second electromagnetic coil78′, membrane assembly82′ may also travel 2 mm in the same direction. Similarly, the frequency at which magnetic ring assembly76′ traverses the space between the first and second electromagnetic coils may be the same frequency at which membrane assembly82′ travels the same distance.

Skirt115may be affixed to membrane97′ and hold membrane97′ in tension. Membrane97′ may be molded directly onto skirt115or may be affixed to skirt115in any way that holds membrane97′ uniformly in tension along its circumference. For example, skirt115may be coated with the same material used to form membrane97′ and the coating on skirt115may be integrally formed with membrane97′.

Blood may enter pump20′ from the left ventricle through inlet cannula21′ and flow downward along the pump assembly into delivery channel100′. As the blood moves down tapered section83′, it is directed through gap74′ and into a vertical portion of delivery channel100′ in the area between pump housing27′ and actuator assembly95′. As shown inFIG.15A, skirt115divides delivery channel100′ into upper delivery channel100aand lower delivery channel100bsuch that blood flow through delivery channel100′ is divided into flow channel101avia upper delivery channel100aand flow channel101bvia lower delivery channel100b, wherein flow channels101aand101bare separated by membrane97′. As will be understood by one of ordinary skill in the art, the volume of blood flow through each of delivery channels100aand100bmay depend on the diameter of first portion115aof skirt115. For example, the larger the diameter of first portion115aof skirt115, the larger the volume of delivery channel100aand the smaller the volume of delivery channel100b. The ratio of the volume of delivery channel100ato the volume of delivery channel100bmay be, for example, 1:1, 1:2, 1:3, 1:4, 2:1, 3:1, 4:1, etc., depending on the amount of desired blood flow on each surface of membrane97′.

By directing blood from inlet cannula21′ across skirt115within delivery channel100′, blood flow is divided into delivery channel100aand100band to flow channels101aand101b, respectively, such that blood flows across the upper and lower surfaces of membrane97′ of membrane assembly82′. For example, as shown inFIG.16A, blood flow through a pump having a planar rigid membrane ring spaced apart a relatively small distance from the pump housing may allow unrestricted blood flow across the upper surface of the flexible membrane while restricting blood flow across the lower surface of the flexible membrane. Whereas, as depicted inFIGS.16B and16C, blood flow through a pump having a J-shaped skirt or integrated portion may be distributed across both the upper and lower sides of the flexible membrane at a desired ratio.

Second portion115bof skirt115curves toward outlet23′ such that second portion115bis coupled to membrane97′ so that membrane97′ is oriented in a second direction, e.g., perpendicular to first portion115aof skirt115. For example, skirt115may have a J-shaped cross-section, such that first portion115aforms a cylindrical-shaped ring about stator assembly72′ and second portion115bhas a predetermined radius of curvature which allows blood to flow smoothly from delivery channel100′ across skirt115to the outer edge of membrane97′ and into flow channel101′, while reducing stagnation of blood flow. Skirt115breaks flow recirculation of blood within delivery channel100′ and improves hydraulic power generated for a given frequency while minimizing blood damage. In addition, the J-shape of skirt115around stator assembly72′ may be stiffer than a planar rigid membrane ring, thereby reducing flexing and fatigue, as well as drag as the blood moves across membrane97′.

Referring back toFIG.15A, by actuating electromagnetic coils77′ and78′, membrane97′ may be undulated within flow channels101aand101bto induce wavelike formations in membrane97′ that move from the edge of membrane97′ towards circular aperture99′. Accordingly, when blood is delivered to membrane assembly82′ from delivery channel100′, it may be propelled radially along both the upper and lower surfaces of membrane97′ towards circular aperture99′, and from there out of outlet23′. The distribution of blood flow across the upper and lower surfaces of membrane97′ reduces recirculation of blood within delivery channel101′, and reduces repeated exposure of blood to high shear stress areas, which results in remarkably improved hydraulic performance of pump20′.

Referring now toFIG.16C, pump400is illustrated which is similar to pump20and includes pump housing402, integrated assembly406, membrane416and actuator assembly404which may be the same or similar to actuator assembly95. Integrated assembly406may be disposed around actuator assembly404and may include magnetic assembly408and transition portion410. Magnetic assembly408may be similar to magnetic ring assembly76and/or may include one or more magnet422and/or iron portion420. It is understood that magnetic assembly408may include a Halbach array. Integrated assembly406may further include outer cover418to permit hermetic sealing of the components in integrated assembly406(e.g., magnetic assembly408) as well as magnet backing424to facilitate magnet alignment and assembly. Integrated assembly406may also include one or more bearing portions419.

Integrated assembly406may be similar to skirt115in function, except that integrated assembly406may incorporate magnetic assembly408. Integrated assembly406may extend upward within delivery channel405and further include transition portion410that extends toward membrane416, which may be the same as or similar to membrane97. Transition portion410may attach the integrated assembly406to membrane416. Integrated assembly406may define a first blood channel412between integrated assembly406and pump housing402and may further define a second blood channel between integrated assembly406and actuator assembly404. Similar to skirt115, integrated assembly406may divert blood into first blood channel412and second blood channel414and ultimately to membrane416.

Pump housing402may include one or more magnets413and one or more bearing portions417. Bearing portion417may be in fluid communication (e.g., via blood in first blood channel412) with bearing portion419and together may form a bearing that resists radial movement of moving assembly406. Bearing portions417and419may be comprised of biocompatible materials, such as ceramics, alumina, zirconia, or zirconia-toughened alumina, or engineered plastics, such as poly-ether-ether-ketone (PEEK) and Delrin, or metallic alloys coated with tribologic coatings, such as titanium coated with titanium nitride (TiN) or zirconium nitride (ZrN). Magnets413and magnetic assembly408may interact to resist axial movement and cause moving assembly to return to a neutral position axially.

One or more magnets of magnetic assembly408may be enlarged to increase second blood channel414, while maintaining attraction between one or more coils (e.g., coils411) of actuator assembly404and magnetic assembly408. The increased second blood channel414may reduce the risk of shear-induced damage to the blood and/or thermal injury. As shown inFIG.16C, pump400may having a single moving assembly (e.g., integrated assembly406) in addition to membrane416.

Referring now toFIG.16D, pump450including inlet spring458and outlet spring460is illustrated. Pump450may be similar to pump400and may include actuator assembly452, which may be similar to actuator assembly404, pump housing456, which may be similar to pump housing402, and integrated assembly454, which may be similar to integrated assembly406. As shown inFIG.16, integrated assembly454may be coupled to inlet spring458and outlet spring460. Inlet spring456and outlet spring460may be coupled at one end to integrated assembly454and at the other end to pump housing456. Inlet spring458and outlet spring460may be monobloc springs, for example, or any other well-known springs. Inlet spring458and outlet spring460, may be comprised of biocompatible metals, such as stainless steel, titanium, or cobalt chromium, for example, and/or may be processed by methods to remove surface defects or cold work the materials to increase durability and hemocompatibility. The inlet spring458and/or outlet spring460may be made by cutting shapes out of the flat sheet of the biocompatible metal. Alternatively, the inlet spring458and/or the outlet spring460may be machined out of a solid block of material, therefore allowing for a more contoured and/or three dimensional design. In preferred embodiments, the solid block of material is stainless steel or titanium. Inlet spring458and outlet spring460may resist both radial and axial movement of moving assembly456and may cause moving assembly456to return to a neutral position. It is understood that either the inlet spring458and/or outlet spring460may be optional (e.g., the pump450may include inlet spring458and/or outlet spring460). As also shown inFIG.16D, dampening structure462may be coupled to and/or extend from actuator assembly452and may facilitate in dampening vibration of pump450(e.g., caused by moving assembly454). Dampening structure462may be comprised of polymer materials, such as biocompatible polyurethane, for example, with Shore Hardness values from20to80A. It is understood that inlet spring458and outlet spring460may be the same or similar to suspension springs. Alternatively, an active dampening structure may be used. An active dampening structure may include or otherwise employ one or more moving mass or tuned mass damper for reducing vibration. In one example, the active dampening structure may be located on the outside surface of the pump, such as vibration dampening assembly523inFIG.17.

Referring now toFIG.17, pump500with an encapsulation assembly is illustrated. Pump500is similar to pump20described above with respect toFIGS.7,8, and12. For example, pump500may include inlet cannula501, which may be similar to inlet cannula21, outlet cannula502, which may be similar to outlet cannula22, upper housing portion515which may be similar to upper housing portion24, and lower housing portion517, which may be similar to lower housing portion25. Upper housing portion515may be coupled to lower housing portion517as well as outlet cannula502. Lower housing portion517may be coupled outlet cannula502. Upper housing portion515and/or inlet cannula501may be coupled to stator assembly511, which may include upper stator portion521and lower stator portion520as well as core stator portion545. Core stator portion545may be coupled to both upper stator portion521and lower stator portion520and may support electromagnetic coils (e.g. first electromagnetic coil504and second electronic magnetic coil505).

As shown inFIG.17, upper stator portion521and lower stator portion520may form stator assembly511and may be designed to house and secure electromagnetic assembly503, which may be similar in structure and/or function to electromagnetic assembly91. For example, electromagnetic assembly503may include first electromagnetic coil504and second electronic magnetic coil505. It is understood that electromagnetic assembly503may be any electromagnetic assembly described herein and/or may include greater than or fewer than two electromagnetic coils. Electromagnetic assembly503together with stator assembly511form an actuator assembly.

Magnetic assembly513, which may be similar in structure and function to magnetic ring assembly76, may be suspended around electromagnetic assembly503. For example, magnetic assembly513may be the magnetic assembly illustrated inFIG.19. Magnetic assembly513may also be coupled to first spring534, which may be similar to first suspension spring79, and second suspension spring535, which may be similar to second suspension spring80. First suspension spring534may also be coupled to upper stator portion521and second suspension spring535may also be coupled to lower stator portion520. First suspension spring534and second suspension spring535may bias magnetic assembly513towards a neutral position between first suspension spring534and second suspension spring535and/or may offset magnetic assembly513from actuator assembly546. It is further understood that first suspension spring534and second suspension spring535may resist twist and/or tilt movement of magnetic assembly513and/or is provide a restoring force to return the magnet assembly513toward a center position. Specifically, first suspension spring534and second suspension spring535may assist in keeping the axial centerline of the stator and the magnetic ring parallel.

Upper stator portion521may be further coupled to top encapsulator532and lower stator portion520may be coupled to bottom encapsulator531. Top encapsulator532and bottom encapsulator531may each be coupled to magnetic assembly513. Top encapsulator532and bottom encapsulator531may be elastic membranes made from any well-known elastic or expandable material and/or structure. For example, top encapsulator532and/or bottom encapsulator531may be made from any well-known elastic and/or thermoplastic material and/or visco-elastic material (e.g., silicone) and/or any ridged material forming a structure designed to expand (e.g., a metallic structure having bellows). Top encapsulator532and bottom encapsulator531may exert a spring force on magnetic assembly513due to the elastic properties of each. Top encapsulator532and first suspension spring534may work together to collectively apply a spring force to magnetic assembly513and similarly bottom encapsulator531and second suspension spring535may work together to apply a spring force to magnetic assembly513. First suspension spring534and/or second suspension spring535may be sized and otherwise designed to accommodate the spring force of top encapsulator532and/or bottom encapsulator531. For example, first suspension spring534and/or second suspension spring535may be sized and otherwise shaped to achieve a desired neutral position of magnetic assembly513based at least in part on the elastic properties of top encapsulator532and bottom encapsulator531.

Magnetic assembly513, top encapsulator532and bottom encapsulator531, and stator assembly511may collectively form encapsulation assembly525which may form a continuous surface thereby encapsulating actuator assembly546, first suspension spring534and second suspension spring535. In this manner, blood flow channel537may be defined between magnetic assembly513, top encapsulator532and bottom encapsulator531, and stator assembly511(i.e., the encapsulation assembly525) on one side, and an interior surface of upper housing portion515and lower housing portion lower housing portion517on the other side.

Encapsulation assembly525may present a number of advantages. For example, because actuator assembly546, first suspension spring534and second suspension spring535are encapsulated, blood is prevented from interacting with actuator assembly546, first suspension spring534and second suspension spring535and therefore such encapsulation may prevent damage to the blood (e.g., hemolysis) that may occur when these components interact with the blood and magnetic assembly513during operation of pump500. Moreover, the blood path may be smoother from a hydrodynamic standpoint with fewer areas with stagnation and turbulent flow thereby reducing the risk for thrombus formation. The blood path may be optimized to minimize blood exposure to shear conditions which can cause damage to blood elements, such as the adhesion protein, von Willebrand Factor.

Membrane assembly538may be coupled to magnetic assembly513such that membrane assembly538moves together with magnetic assembly513. Membrane assembly538may include skirt550and membrane507, which may be similar to skirt115and membrane97′, respectively, as described above with respect toFIG.16B. Membrane507may be circular in shape and may include a circular aperture in the center. For example, skirt550may be disposed around encapsulation assembly525and may extend within delivery channel537in a vertical direction and may curve toward membrane507, which may be oriented in a horizontal direction. For example, skirt550may have a J-shaped cross-section, such that a portion of skirt550forms a cylindrical-shaped structure about stator assembly and may have a predetermined radius of curvature which allows blood to flow smoothly from delivery channel537across skirt550to membrane507, reducing stagnation of blood flow.

Skirt550may reduce or eliminate flow recirculation of blood within delivery channel537and improve hydraulic power generated for a given frequency while minimizing blood damage. In addition, the J-shape of skirt550may be stiffer than membrane507, thereby reducing flexing and fatigue, as well as drag as the blood moves across membrane507. Membrane assembly538may be rigidly coupled to magnetic assembly513via a plurality of rigid pins and/or via surface contact that may be welded. As magnetic assembly513moves up and down (e.g. reciprocates), so too will skirt550, thereby causing wavelike undulations in membrane507that propels blood over and under membrane507splitting blood flow path537include blood flow paths506towards outlet cannula502of pump500.

Upper housing portion515may include vibration dampening assembly523which may be designed to dampen vibration of pump500as magnetic assembly513reciprocates in operation. For example, vibration dampening assembly523may be a tuned mass damper, wherein a mass is tuned to oscillate in a 180 degree phase to the primary motion of the actuator. Vibration dampening assembly523may include mass540suspended by one or more vibration springs541. For example, mass540may be an annular mass. Vibration dampening assembly523may be disposed around and/or positioned on an outer surface of upper housing portion515, or otherwise incorporated into upper housing portion515. Mass540and vibration spring541may be sized and shaped to reduce vibration levels of pump500due to magnetic assembly513reciprocating.

Referring now toFIG.18, an exploded view of the actuator assembly, magnetic assembly, and membrane assembly is illustrated. As shown inFIG.18, inlet block601may include inlet cannula621, which may be similar to inlet cannula501ofFIG.17, as well as upper stator portion622, which may be similar to upper stator portion521ofFIG.17. First suspension spring603, which may be similar to first suspension spring534ofFIG.17, may be coupled to upper stator portion622.

Core assembly602may be coupled to upper stator portion622and may be disposed below first suspension spring603. Core assembly602may include electromagnetic assembly605, which may be similar to actuator assembly546ofFIG.17, and core stator portion624, which may be the same as core stator portion545ofFIG.17. Core stator portion624may support electromagnetic assembly605. Core assembly602may include encapsulation portion626, which may be a flexible membrane (e.g., silicone) that may cover all or a portion of electromagnetic assembly605and/or core stator portion545. Magnetic assembly607, which may be similar to magnetic assembly513ofFIG.17, may be disposed around core assembly602and may be coupled to inlet block601via first suspension spring534. Magnetic assembly607may include pin receiving portion619sized and designed to receive and engage pin615.

Second suspension spring609, which may be similar to second suspension spring535ofFIG.17, may also be coupled to magnetic assembly607and also coupled to lower stator portion611, which may similar to lower stator portion520ofFIG.17. In this manner, magnetic assembly607may be concentrically positioned between the first suspension spring603and second suspension spring609such that magnetic assembly607may oscillate between first suspension spring603and second suspension spring609. First suspension spring603and second suspension spring609may be further coupled to core assembly602. Lower stator portion611may further include protrusion628, which may extend upward with respect to lower stator portion611. For example, protrusion628may extend through core stator portion624and engage upper stator portion622to couple lower stator portion611and core stator portion624to upper stator portion622. In one example, the engagement between protrusion628and upper stator portion622may be a threaded engagement.

Membrane assembly645may include skirt613and membrane640. Skirt613may be similar to skirt550ofFIG.17and membrane640may be similar to membrane507ofFIG.17. Skirt613may further include a plurality of pin receiving portions617that may be apertures that extend through skirt613and may be sized and shaped to receive pins615. Pins615may be any type of well-known pin that may extend through skirt613and couple skirt613to magnetic assembly607. In this manner, membrane assembly645may be rigidly coupled to magnetic assembly607. It is understood that magnetic assembly607may alternatively be coupled to skirt613using any other well-known coupling technique (e.g., adhesive, threaded engagement, etc.)

Referring now toFIG.19, magnetic ring assembly700is illustrated. As shown inFIG.19, magnetic ring assembly700may include magnet701, magnet705and magnet709which each may include one or more magnet portions that form a ring and/or have a general radius of curvature. It is understood that magnet portions701,705and709may include one or more magnet and/or iron portions (e.g. iron cobalt). In embodiments, the magnetic portions701,705, and709are iron cobalt. In embodiments, magnetic ring assembly700may include three magnets of iron, neon, and/or boron with a back iron cover of iron-cobalt, for example. It is further understood that magnetic portions701,705and/or709may be or include a Halbach array. Magnetic ring assembly700may further include inner housing706that may house or otherwise support moving magnet portions701,705and709. Outer housing707may be disposed over inner housing706and magnet portions701,705and709and may couple to inner housing706to secure and seal magnet portions701,705and709to inner housing706. While three magnet portions701,705, and709are illustrated inFIG.19, it is understood that greater or few magnet portions could be included in magnet ring assembly700. It is understood that magnetic ring assembly700may include magnetic segments such as magnet portions701,705and709arranged in a series. Alternatively, magnetic ring assembly700may include a single continuous cylindrical magnet or a series of magnets.

FIGS.20A-20C, illustrate pump800, encapsulation assembly850and membrane assembly817. Referring now toFIG.20A, encapsulation assembly850may be the same as encapsulation assembly525ofFIG.17. Specifically, encapsulation assembly850may include upper stator assembly801, top encapsulator815, magnetic assembly805, bottom encapsulator816, and lower stator assembly803, which may be similar to upper stator portion521, top encapsulator519, magnetic assembly513, bottom encapsulator521, and lower stator portion520ofFIG.17, respectively. Upper stator assembly801may be coupled to inlet cannula855. Magnetic assembly805may include pin receiving portions821.

As shown inFIG.20A, magnetic assembly805may be positioned between and coupled to top encapsulator815and bottom encapsulator816. Top encapsulator815may engage upper stator portion801. Encapsulation assembly850may be axially and concentrically aligned with membrane assembly817which may be similar to membrane assembly538ofFIG.17. For example, membrane assembly817may include skirt807and membrane818, which may be similar to skirt550and membrane507ofFIG.17.

FIG.20Billustrates how the membrane assembly817may be concentrically positioned around and offset from magnetic ring assembly805. As illustrated inFIG.20B, membrane assembly817may be rigidly coupled to magnetic ring assembly805via pins811that may extend through membrane assembly817and engage magnetic assembly805. Referring now toFIG.20C, a connection between membrane assembly817and magnetic assembly805is illustrated. As shown inFIG.20C, membrane assembly817may include aperture820through which pin811may be inserted to engage with pin receiving portion821of magnetic assembly805sized and designed to receive pin811.

Referring now toFIGS.21A-21C, movement of membrane901in operation of the pump are illustrated. As shown inFIG.21A, magnetic assembly903, which may be similar to magnetic assembly513ofFIG.17, has moved to an upper most position with respect stator assembly909, which may be similar to stator assembly511. As a result, membrane assembly907, which may be similar to membrane assembly538, may too move upward, causing membrane901, which may be similar to membrane507, to move upward. However, freestanding portion905of membrane905may remain at a lower position as membrane assembly907moves upward. As depicted inFIG.21BandFIG.21C, membrane assembly907may move downward to a second and third position, respectively, in which the portion of membrane901freestanding end901rises while membrane assembly907lowers. In this manner, a wave-like undulation may be generated toward the free standing end905which propels blood to free standing end905. This process repeats and membrane901moves back upward to the first position as shown inFIG.21A, before again moving to the second and third positions as shown inFIGS.21B and21C.

Referring now toFIG.22AandFIG.22B, pump1000may be similar to pump500ofFIG.17. As shown inFIG.22A, pump1000may include encapsulation assembly1001, upper housing portion1002, lower housing portion1003, and membrane assembly1004, which may be similar to encapsulation assembly525, upper housing portion515, lower housing portion517, and membrane assembly535. Encapsulation assembly1001on one side and upper housing portion1002and lower housing portion1003on the other side may form blood flow path1005. As shown inFIG.22A, blood may enter the components shown in red and thus may enter inlet cannula1006, travel in blood flow path1005along membrane assembly1004, and exit outlet cannula1007.

FIG.22Bis a top-down view of pump1000depicting encapsulation assembly1001, membrane assembly1004, and a portion upper housing portion1002. As shown inFIG.22B, blood path1005is defined by encapsulation assembly1001and an interior surface of upper housing portion1002and is split into two blood flow paths by membrane assembly1004. Upper housing portion1002may further include positioning sensors1008that may determine certain operational information about the pump and/or position of membrane assembly1005.

Membrane assembly1004is illustrated in greater detail inFIG.23. As shown inFIG.23, membrane assembly1004may include one or more sensor targets1301. Sensor targets1301may be permanent magnets that are targets for the sensors that are mounted on the outside of the pump housing and may create a moving field for the sensors. Sensors targets1301may be used together with positioning sensors1008illustrated inFIG.22Bto determine information about the position of membrane assembly1004with respect to the pump. Such information may be used to control the motion of the membrane in a closed loop circuit, thereby broadening the range of operation, and preventing excessive amplitude which could damage springs. In one embodiment, sensor targets may be similar to such structure described in further detail in U.S. Pat. No. 10,799,625, which is incorporated herein by reference. Membrane assembly1004may include one or more sensor receiving portions1303that may be sized and shaped to receive sensor target1301. Sensor receiving portion1303may be sealed with seal portion1302that may cover sensor receiving portion1303and sensor target1301.

Referring now toFIG.24, a cross-sectional view of pump1100with various isolated portions is illustrated. Pump1100may be similar to pump500inFIG.17and may include stator assembly1103, electromagnetic assembly1108, magnetic assembly1107, top encapsulator1109, and bottom encapsulator1111, encapsulation assembly1113. Magnetic assembly1107may include isolated portions1124that may include gaps and/or empty spaces in magnetic assembly1107that may be filled with epoxy backfilling1124. Electromagnetic assembly1108may similarly include isolated portions1126that may include gaps and/or empty spaces in electromagnetic assembly1108that may be filled with epoxy backfilling. Such epoxy backfilling of isolated portions1124and1126may protects metallic components and/or wires and/or provide a locking feature to prevent unscrewing. Epoxy backfilling may be added under vacuum before such components are sealed closed. For example, the actuator assembly1106, which may include core stator portion1104and electromechanical assembly1108, may be hermetically sealed (e.g., by welding of the joints). Core stator portion1104may support electromechanical assembly1108.

Referring now toFIG.25, a perspective view of actuator assembly1106is illustrated. As is shown inFIG.25, actuator assembly1106may include several grooves1130positioned on the outer surface of actuator assembly1106. The grooves1130may be sized and arranged to prevent eddy current circulation in the stator. The groves1130may also provide the wiring path for connection to the coils. InFIG.25, wire paths1132are shown in one of the circular grooves for connection to the coils. The grooves1130may be sized to ease the backfilling of the stator from the inner diameter that may be used for the entry of epoxy to the outer diameter of the actuator assembly.

Referring again toFIG.24, isolated portions1122may be filled with encapsulation fluid. For example, the encapsulation fluid may be a perfluorocarbon such as perfluorodecalin. Isolated portions1122may be defined by the space between actuator assembly1106and stator assembly1125, top encapsulator1109, magnetic assembly1107, and bottom encapsulator1111, for example. Encapsulation fluid may be inert fluid that may prevent migration of air, water, and other dissolved components. Encapsulation fluid may be silicone oil, saline, and/or deionized water. Encapsulation fluid may be added to pump1100though the following process. First, a two-way tap may be connected to pump1100(e.g., through the inlet block). The pump core may then be placed under vacuum as a connector that may be switched to liquid path. Once encapsulation fluid has filled up isolated portions1122, the chamber pressure may return to atmosphere pressure. Then the encapsulation backfilling access is sealed.

Referring now toFIG.26AandFIG.26B, inlet block1400may be similar to inlet block601inFIG.18. As shown inFIG.26A, inlet block1400may include at least a portion of stator assembly as well as inlet cannula1402. For example, inlet block1400may include stator engagement1406for engaging the stator assembly. Stator engagement1406may be a threaded engagement. Inlet block1400may further include several dividers1404positioned near the bottom of inlet cannula1402which create a mechanical connection between the actuator and the housing. As shown inFIG.26B, which is a top down view of inlet block1400, blood may enter the pump through inlet cannula1402. The shape of dividers1404may be designed to prevent flow stagnation to reduce the risk of thrombus formation. As blood traverses inlet block1400, it may be divided into various blood flow paths by dividers1404. The inlet block1400may include a channel for electrically connecting the actuator assembly to the outside of the pump and/or a channel to fill the cavity1122as shown inFIG.24.

Referring now toFIGS.27A-27B, pump1500is illustrated. Pump1500may be similar to pump500inFIG.17. For example, pump1500may include inlet cannula1502, stator assembly1507, top encapsulator1510, magnetic assembly1511, bottom encapsulator1514, electromagnetic assembly1512, upper housing portion1503, lower housing portion1505, membrane assembly1509and outlet cannula1515, which may be similar to include inlet cannula501, stator assembly511, top encapsulator532, magnetic assembly513, bottom encapsulator531, electromagnetic assembly503, upper housing portion515, lower housing portion517, membrane assembly538, and outlet cannula502, respective, as described above with respect toFIG.17. As shown inFIG.27A, the elastic properties of top encapsulator1510and bottom encapsulator1514may provide a spring function to return the actuator to a center position. As shown inFIG.27B, pump housing1500may include one or bearing portions1517. Bearing portion1517may resist radial movement of magnetic assembly1511within pump1500.

Referring now toFIG.28, pump1600is illustrated and may include top encapsulator1603and bottom encapsulator1610, which each may include bellows. Pump1600may be similar to pump500inFIG.17. For example, pump1600may include inlet cannula1610, stator assembly1604, magnetic assembly1602, bottom encapsulator1610, electromagnetic assembly1605, upper housing portion1611, lower housing portion1612, and membrane assembly1613, which may be similar to include inlet cannula501, stator assembly511, magnetic assembly513, electromagnetic assembly503, upper housing portion515, lower housing portion517, and membrane assembly538ofFIG.17, respectively. Top encapsulator1603and bottom encapsulator1610may be similar to top encapsulator532and bottom encapsulator531ofFIG.17, however, top encapsulator1603may include bellows1614and bottom encapsulator1610may include bellows1615. For example, top encapsulator1603and bottom encapsulator1610may be formed from one or more well-known metals or metal alloys and bellows1614and1615may be pleated bellows. In this manner, top encapsulator1614and bottom encapsulators1614may be made of metal but may still be flexible and facilitate movement of magnetic assembly1602.

Referring now toFIGS.29A-29B, pump1700including flexure springs1710attached to actuator compartment1716is illustrated. Pump1700may be similar to pump500inFIG.17. For example, pump1700may include inlet cannula1701, stator assembly1702, top encapsulator1704, magnetic assembly1705, bottom encapsulator1706, electromagnetic assembly1708, and membrane assembly1738, which may be similar to include inlet cannula501, stator assembly511, top encapsulator532, magnetic assembly513, bottom encapsulator531, electromagnetic assembly503, and membrane assembly538ofFIG.17.

Membrane assembly1738may be coupled to magnetic assembly1705. Electromagnetic assembly1708may be positioned within actuator compartment1716which may be cylindrical or similarly shaped structure acting as a physical connection between the magnet ring and the flexure bearing, which may be porous. For example, actuator compartment may be a thin walled cylinder. Electromagnetic assembly1708may be isolated from the rest of pump1700by top encapsulator1704and bottom encapsulator1706. Actuator compartment1716may be connected to stator assembly1702via one or more flexure (spiral) springs1701. Flexure spring1710is shown in more detail inFIG.29B. Flexure spring1710may include several curved through cuts1720achieving a spiral shape on flexure spring1710. Flexure spring1710may optionally include several actuator compartment engagement portions along a permit of flexure spring1710. Flexure spring1710may connect to stator assembly1702at stator receiving portion1723and may connect to actuator compartment1716via actuator compartment engagement portions1722. Flexure spring1710may incorporate dimensions and material properties that allow it to provide a spring force. Actuator compartment1716may be coupled to magnetic assembly1705; in embodiments, actuator compartment1716and magnetic assembly1705are flexibly connected by a flexure bearing. The flexure bearing may provide restoring force and may resist radial movement.

Referring now toFIG.29B, perspective views of flexure springs and the actuator compartment are illustrated. As shown inFIG.29B, stator assembly1702may include central component1734which may be cylindrical in shape and may engage upper flexural spring1730and lower flexural spring1732, each of which may be similar to flexural spring1710. Upper flexural spring1730and lower flexural spring1732may each also be coupled to actuator compartment1716, which may be rigidly coupled to magnetic assembly1705. Top encapsulator1704and bottom encapsulator1706may each be coupled to stator assembly1702and magnetic assembly1705. The electromagnetic assembly (not shown) may be disposed in actuator compartment1716but may be rigidly connected to central component1734such that actuator compartment1716is free to move axially with respect to stator assembly1702. Membrane assembly1738may be coupled to magnetic assembly1705.

As magnetic assembly1705interacts with electromagnetic assembly, magnetic assembly1705may be caused to reciprocate up and down with respect to stator assembly1702. As actuator compartment1716may be rigidly coupled to magnetic assembly1705, actuator compartment1716may similarly reciprocate. Upper flexure spring1730and lower flexure spring1732may permit actuator compartment1716to move in the axial direction and upper flexure spring1730and lower flexure spring1732may cause actuator compartment1716and thus magnetic assembly1738to return to a neutral position via a spring force in upper flexure spring1730and lower flexure spring1732. Upper flexure spring1730and lower flexure spring1732may further resist twist or tilt of actuator component1716and magnetic assembly1705.

While various illustrative embodiments of the invention are described above, it will be apparent to one skilled in the art that various changes and modifications may be made therein without departing from the invention. For example, pump assembly70shown inFIG.9may be ordered differently and may include additional or fewer components of various sizes and composition. The appended claims are intended to cover all such changes and modifications that fall within the true spirit and scope of the invention.