Patent Description:
The present disclosure relates generally to mechanical circulatory support systems, and more specifically relates to implantable blood pump assemblies that include a plurality of sensors and a controller that combines data streams received from the sensors.

Ventricular assist devices, known as VADs, are implantable blood pumps used for both short-term (i.e., days, months) and long-term (i.e., years or a lifetime) applications where a patient's heart is incapable of providing adequate circulation, commonly referred to as heart failure or congestive heart failure. A patient suffering from heart failure may use a VAD while awaiting a heart transplant or as a long term destination therapy. In another example, a patient may use a VAD while recovering from heart surgery. Thus, a VAD can supplement a weak heart (i.e., partial support) or can effectively replace the natural heart's function. VADs can be implanted in the patient's body and powered by an electrical power source inside or outside the patient's body.

A controller can be used to control operation of the implanted VAD. The controller can be operatively connected to the VAD via a wired, wireless, and/or mechanical connection, which can be used to supply the VAD with operating power (e.g., electrical and/or mechanical power) and control signals to control the operation of the VAD.

At least some VADs utilize feedback from one or more sensors to control operation of the VAD. Some VADs, for example, use a pressure sensor to measure pressure and monitor a patient's cardiac cycle for control of the VAD. While the sensors of at least some VADs provide valuable information, there are drawbacks with the quality and scope of the information provided by the sensors. For example, sometimes sensors are unable to provide accurate information due to malfunction and/or limitations in operational capabilities of the sensors. For example, some sensors, such as current sensors, may not provide usable information during all stages of heart or pump cycles. Further, it may be difficult to determine if individual sensors are providing accurate information. In addition, certain values, such as cardiac characteristics or pump operating parameters, cannot be determined from data provided by individual sensors alone and, therefore, individual sensors may provide less than optimal clinical information for operating the VAD. <CIT> discloses a cardiac assist apparatus comprising a blood pump, a drive unit for driving the blood pump, a power supply for supplying power to the drive unit, a frequency sensor that senses a rotational speed of the blood pump, a current sensor that senses an average direct current waveform of the drive unit, a power supply voltage sensor that senses a power supply voltage, and a blood pump controller that receives data from the frequency sensor, current sensor, and the power supply voltage sensor and controls operation of the blood pump in response thereto. A further prior art example can be found in <CIT>.

Accordingly, a need exists for improved VADs that combine information from multiple sensors to monitor a patient's cardiac cycle and/or control operation of the VAD.

The invention is defined by the features of independent claim <NUM>. The present disclosure is directed to a circulatory support system including an implantable blood pump and a controller. The implantable blood pump includes a housing defining an inlet, an outlet, a flow path extending from the inlet to the outlet, and an internal compartment separated from the flow path. The implantable blood pump also includes a rotor positioned within the flow path and operable to pump blood from the inlet to the outlet, and a stator positioned within the internal compartment and operable to drive the rotor. The implantable blood pump further includes a plurality of sensors including at least two of the following: a current sensor configured to detect a current provided to the stator, a rotor position sensor configured to detect a position of the rotor relative to the housing, an accelerometer configured to detect acceleration of the blood pump in at least one direction, and a pressure sensor positioned between the inlet and the outlet and configured to detect a pressure of blood flowing through the flow path. The controller is connected to the plurality of sensors and includes a signal-processing module and at least one of an operator interface module and a pump control module. The signal-processing module is configured to receive, from each of the plurality of sensors, a data stream. The signal-processing module is also configured to filter the data streams received from the plurality of sensors, determine at least one of a pump operating parameter, a cardiac characteristic, and a pump control parameter based on at least two of the filtered data streams, and output the at least one of the pump operating parameter, the cardiac characteristic, and the pump control parameter to at least one of the operator interface module and the pump control module.

The present disclosure is also directed to a method of operating an implantable blood pump (not claimed). The blood pump includes a housing defining an inlet, an outlet, a flow path extending from the inlet to the outlet, and an internal compartment separated from the flow path. The blood pump also includes a rotor positioned within the flow path and operable to pump blood from the inlet to the outlet, and a stator positioned within the internal compartment and operable to drive the rotor. The method includes detecting, using a plurality of sensors, at least two of the following: a current provided to the stator, a position of the rotor relative to the housing, an acceleration of the blood pump in at least one direction, and a pressure of blood flowing through the flow path. The method also includes receiving, at a signal-processing module of a controller connected to the plurality of sensors, a data stream from each of the plurality of sensors, and filtering, by the controller, the data streams received from the plurality of sensors. The method further includes determining, by the controller, at least one of a pump operating parameter, a cardiac characteristic, and a pump control parameter based on at least two of the filtered data streams, and outputting the at least one of the pump operating parameter, the cardiac characteristic, and the pump control parameter from the signal-processing module to at least one of an operator interface module and a pump control module.

The present disclosure is further directed to an implantable blood pump including a housing defining an inlet, an outlet, a flow path extending from the inlet to the outlet, and an internal compartment separated from the flow path. The implantable blood pump also includes a rotor positioned within the flow path and operable to pump blood from the inlet to the outlet, a stator positioned within the internal compartment and operable to drive the rotor, and a plurality of sensors. The plurality of sensors includes a current sensor configured to detect a current provided to the stator, a rotor position sensor configured to detect a position of the rotor relative to the housing, an accelerometer configured to detect acceleration of the blood pump in at least one direction, and a pressure sensor positioned between the inlet and the outlet and configured to detect a pressure of blood flowing through the flow path. The plurality of sensors are connected to a controller configured to receive a data stream from each of the plurality of sensors, filter the data streams received from the plurality of sensors, and determine at least one of a pump operating parameter, a cardiac characteristic, and a pump control parameter based on the filtered data streams.

The present disclosure is directed to implantable blood pump assemblies. Embodiments of the implantable blood pump assemblies disclosed herein include a plurality of sensors that are connected to a controller. For example, in some embodiments, the plurality of sensors include a current sensor, a rotor position sensor, an accelerometer, and a pressure sensor. A signal-processing module of the controller receives data streams from each of the plurality of sensors and filters the data streams. In some embodiments, at least one supplemental data stream is generated based on the data streams of the plurality of sensors. For example, the supplemental data stream may include a pressure of blood flowing out of the blood pump assembly through an outlet. Based on the filtered data streams, the controller may determine at least one of a pump operating parameter, a cardiac characteristic, and a pump control parameter. The pump operating parameter, cardiac characteristic, or pump control parameter may be output to an operator interface module for presentation to an operator and/or output to a pump control module configured to control the blood pump assembly.

Further, the data streams may be compared and combined to provide clinical and operational information that is more robust and accurate than information based on individual data streams alone. In some embodiments, the accuracy of each data stream may be determined based on a comparison of the data streams and each data stream may be assigned a quality rating based on the determined accuracy of the data streams. As a result, the implantable blood pump assemblies described herein may provide more accurate and more complete information for clinical assessment of a patient than prior blood pump assemblies. In addition, the implantable blood pump assemblies may be at least partially autonomously operated based on the multiple data streams.

Referring now to the drawings, <FIG> is an illustration of a mechanical circulatory support system <NUM> implanted in a patient's body <NUM>. The mechanical circulatory support system <NUM> includes an implantable blood pump assembly <NUM> that includes a blood pump <NUM>, a ventricular cuff <NUM>, and an outflow cannula <NUM>. The mechanical circulatory support system <NUM> also includes an external system controller <NUM> and one or more power sources <NUM> (e.g., batteries).

The blood pump assembly <NUM> can be implemented as or can include a ventricular assist device (VAD) that is attached to an apex of the left ventricle, as illustrated, or the right ventricle, or both ventricles of the heart <NUM>. The blood pump assembly <NUM> can be attached to the heart <NUM> via the ventricular cuff <NUM> which is sewn to the heart <NUM> and coupled to the blood pump assembly <NUM>. The other end of the blood pump assembly <NUM> connects to the ascending or descending aorta via the outflow cannula <NUM> so that the blood pump assembly <NUM> effectively diverts blood from the weakened ventricle and propels it to the aorta for circulation to the rest of the patient's vascular system. The VAD can include a centrifugal (as shown) or axial flow pump as described in further detail herein that is capable of pumping the entire output delivered to the left ventricle from the pulmonary circulation (i.e., up to <NUM> liters per minute).

<FIG> illustrates the mechanical circulatory support system <NUM> during battery powered operation. A communication line <NUM> connects the implanted blood pump assembly <NUM> to the external system controller <NUM>, which monitors system <NUM> operation. In the illustrated embodiment, the communication line <NUM> is shown as a driveline that exits through the patient's abdomen <NUM>, although it should be understood that the blood pump assembly <NUM> may be connected to the external system controller <NUM> via any suitable communication line, including wired and/or wireless communication. The system can be powered by either one, two, or more power sources <NUM>. It will be appreciated that although the system controller <NUM> and power source <NUM> are illustrated outside/external to the patient body, the communication line <NUM>, system controller <NUM> and/or power source <NUM> can be partially or fully implantable within the patient, as separate components or integrated with the blood pump assembly <NUM>.

<FIG> is an illustration of an implantable blood pump assembly <NUM> suitable for use in the mechanical circulatory support system <NUM> of <FIG>, where the blood pump assembly <NUM> is shown in an operational position implanted in a patient's body. In the illustrated embodiment, the blood pump assembly <NUM> is a left ventricular assist blood pump assembly connected to the left ventricle LV of the heart H.

The blood pump assembly <NUM> includes a blood pump <NUM> including a circular shaped housing <NUM> having a first outer face or wall <NUM> and a second outer face or wall <NUM>. The blood pump assembly <NUM> further includes an inlet cannula <NUM> (generally, an inlet conduit) that, in the illustrated embodiment, extends from the first outer wall <NUM> of the pump housing <NUM>. When the blood pump assembly <NUM> is implanted into a patient's body, as shown in <FIG>, the first outer wall <NUM> of the housing <NUM> is positioned against the patient's heart H, and the second outer wall <NUM> of the housing <NUM> faces away from the heart H. The inlet cannula <NUM> extends into the left ventricle LV of the heart H to connect the blood pump assembly <NUM> to the heart H. The second outer wall <NUM> of the housing <NUM> has a chamfered edge <NUM> to avoid irritating other tissue that may come into contact with the blood pump assembly <NUM>, such as the patient's diaphragm.

<FIG> is a schematic cross-sectional view of the blood pump assembly <NUM> of <FIG>. <FIG> is a perspective cut away view of the blood pump assembly <NUM>. <FIG> is an enlarged view of the blood pump assembly <NUM>. The blood pump assembly <NUM> further includes a stator <NUM>, a rotor <NUM>, an on-board controller <NUM>, and a plurality of sensors <NUM> (shown in <FIG>). In the illustrated embodiment, the stator <NUM>, the rotor <NUM>, the on-board controller <NUM>, and at least some of the plurality of sensors <NUM> are enclosed within the pump housing <NUM>. In the illustrated embodiment, the stator <NUM> and the on-board controller <NUM> are positioned on the inflow side of the pump housing <NUM> toward the first outer wall <NUM>, and the rotor <NUM> is positioned along the second outer wall <NUM>. In other embodiments, the stator <NUM>, the rotor <NUM>, and the on-board controller <NUM> may be positioned at any suitable location within the pump housing <NUM> that enables the blood pump assembly <NUM> to function as described herein. Power is supplied to operational components of the blood pump assembly <NUM> (e.g., the stator <NUM> and the on-board controller <NUM>) from a remote power supply via a power supply cable <NUM> (shown in <FIG>).

The pump housing <NUM> defines an inlet <NUM> for receiving blood from a ventricle of a heart (e.g., left ventricle LV shown in <FIG>), an outlet <NUM> for returning blood to a circulatory system, and a flow path <NUM> extending from the inlet <NUM> to the outlet <NUM>. The pump housing <NUM> further defines an intemal compartment <NUM> separated from the flow path <NUM>, for example, by one or more dividing walls <NUM>.

The pump housing <NUM> also includes an intermediate wall <NUM> located between the first outer wall <NUM> and the second outer wall <NUM>, and a peripheral wall <NUM> that extends between the first outer wall <NUM> and the intermediate wall <NUM>. Together, the first outer wall <NUM>, the dividing wall <NUM>, the intermediate wall <NUM>, and the peripheral wall <NUM> define the internal compartment <NUM> in which the stator <NUM> and the on-board controller <NUM> are enclosed.

In the illustrated embodiment, the pump housing <NUM> also includes a cap <NUM> removably attached to the pump housing <NUM> along the intermediate wall <NUM>. The cap <NUM> is threadably connected to the pump housing <NUM> in the illustrated embodiment, although in other embodiments the cap <NUM> may be connected to the pump housing <NUM> using any suitable connection means that enables the blood pump assembly <NUM> to function as described herein. In some embodiments, for example, the cap <NUM> is non-removably connected to the pump housing <NUM>, for example, by welding. The removable cap <NUM> includes the second outer wall <NUM>, the chamfered edge <NUM>, and defines the outlet <NUM>. The cap <NUM> also defines a volute <NUM> that is in fluid communication with the outlet <NUM>, and a rotor chamber <NUM> in which the rotor <NUM> is positioned. The cap <NUM> can be attached to the pump housing <NUM> using any suitable connection structure. For example, the cap <NUM> can be engaged via threads with the peripheral wall <NUM> to seal the cap <NUM> in engagement with the peripheral wall <NUM>.

The rotor <NUM> is positioned within the blood flow path <NUM>, specifically, within the rotor chamber <NUM>, and is operable to rotate in response to an electromagnetic field generated by the stator <NUM> to pump blood from the inlet <NUM> to the outlet <NUM>. The rotor defines a central aperture <NUM> through which blood flows during operation of the blood pump <NUM>. The rotor <NUM> includes impeller blades <NUM> located within the volute <NUM> of the blood flow path <NUM>, and a shroud <NUM> that covers the ends of the impeller blades <NUM> facing the second outer wall <NUM> to assist in directing blood flow into the volute <NUM>.

In the illustrated embodiment, the rotor <NUM> includes a permanent magnet <NUM> that defines the central aperture <NUM>. The permanent magnet <NUM> has a permanent magnetic north pole N and a permanent magnetic south pole S for combined active and passive magnetic levitation of the rotor <NUM> and for rotation of the rotor <NUM>. In operation, the stator <NUM> is controlled to drive (i.e., rotate) the rotor and to radially levitate the rotor <NUM> by generating electromagnetic fields that interact with the permanent magnetic poles S and N of the permanent magnet <NUM>.

Any suitable stator <NUM> can be employed to rotate the rotor <NUM>. The stator <NUM> generally includes a plurality of winding structures that generate suitable electromagnetic fields that interact with the rotor <NUM> to cause rotor <NUM> to rotate and levitate. In the illustrated embodiment, the stator <NUM> includes a plurality of pole pieces <NUM> arranged circumferentially at intervals around the dividing wall <NUM>. The example blood pump assembly <NUM> includes six pole pieces <NUM>, two of which are visible in <FIG>. In other embodiments, the blood pump assembly <NUM> can include more than or less than six pole pieces, such as four pole pieces, eight pole pieces, or any other suitable number of pole pieces that enables the blood pump assembly <NUM> to function as described herein. In the illustrated embodiment, each of the pole pieces <NUM> includes a drive coil <NUM> for generating an electromagnetic field to rotate the rotor <NUM>, and a levitation coil <NUM> for generating an electromagnetic field to control the radial position of the rotor <NUM>.

Each of the drive coils <NUM> and the levitation coils <NUM> includes multiple windings of a conductor wound around the pole pieces <NUM>. The drive coils <NUM> and the levitation coils <NUM> of the stator <NUM> are arranged in opposing pairs and are controlled to drive the rotor and to radially levitate the rotor <NUM> by generating electromagnetic fields that interact with the permanent magnetic poles S and N of the permanent magnet <NUM>. Suitable methods for generating electromagnetic fields to rotate and radially levitate the rotor <NUM> are described, for example, in <CIT>. Although the drive coil <NUM> and levitation coil <NUM> are shown as separate coils in the illustrated embodiment, it should be understood that the drive coil <NUM> and levitation coil <NUM> may be implemented as a single coil configured to generate electromagnetic fields for both rotating and radially levitating the rotor <NUM>.

The inlet cannula <NUM> is attached to the pump housing <NUM> at the inlet <NUM>. As shown in <FIG>, the pump housing <NUM> includes an inlet cannula receiving portion <NUM> that includes suitable connecting structure for connecting the inlet cannula <NUM> to the pump housing <NUM>. In the illustrated embodiment, the pump housing <NUM> includes an internally threaded sleeve <NUM> that threadably engages external threads <NUM> on a downstream end <NUM> of the inlet cannula <NUM> to connect the inlet cannula <NUM> to the pump housing <NUM>.

The inlet cannula <NUM> defines an inlet flow path <NUM> that supplies blood to the inlet <NUM> of the pump housing <NUM>. As shown in <FIG>, in the illustrated embodiment, the inlet cannula <NUM> extends into the blood flow path <NUM> defined by the pump housing <NUM> such that the inlet flow path <NUM> partially overlaps with the blood flow path <NUM>.

The downstream end <NUM> of the inlet cannula <NUM> has a reduced cross-sectional area (e.g., relative to an upstream end of the inlet cannula <NUM>) that produces a localized region of high velocity blood flow through the inlet flow path <NUM> and the blood flow path <NUM>. Specifically, the cross-sectional area of the inlet flow path <NUM> gradually and continuously decreases towards the downstream end <NUM> of the inlet cannula <NUM> such that blood flowing through the inlet cannula <NUM> at a constant flow rate will experience an increase in velocity as it flows through the downstream end <NUM> of the inlet cannula <NUM>. Consequently, during operation of the blood pump assembly <NUM>, the reduced-cross-sectional area of the downstream end <NUM> produces a localized region of high velocity blood flow that flows through the inlet <NUM> and through the blood flow path <NUM>.

In some embodiments, a portion <NUM> of the internal compartment <NUM> (shown in <FIG>) is hermetically sealed from the portions of the internal compartment which may be in communication with fluid (e.g., blood) to inhibit fluid ingress into the portion of the internal compartment <NUM> in which electronics (e.g., stator <NUM> and on-board controller <NUM>) are housed. In the illustrated embodiment, for example, a sensor assembly housing <NUM> forms a seal against the pump housing <NUM> to hermetically seal the portion <NUM> of the internal compartment <NUM> (shown in <FIG>) in which electronics are housed from the internal cavity defined by the sensor assembly housing <NUM>.

With additional reference to <FIG>, the plurality of sensors <NUM> includes at least one pressure sensor <NUM>, a first current sensor <NUM>, a second current sensor <NUM>, an accelerometer <NUM>, and a rotor position sensor <NUM>. The first current sensor <NUM> and the second current sensor <NUM> are configured to detect current provided to the stator <NUM>. For example, the first sensor <NUM> is connected to the drive coils <NUM> and is configured to measure a current provided to the drive coils <NUM> of the stator <NUM> from the power supply. The second current sensor <NUM> is connected to the levitation coils <NUM> and is configured to measure a current provided to the levitation coils <NUM> of the stator <NUM> from the power supply. In other embodiments, the blood pump assembly <NUM> may include any suitable current sensors that enable the blood pump assembly <NUM> to operate as described herein. For example, in some embodiments, the blood pump assembly <NUM> includes a single current sensor that is configured to measure both the current provided to the drive coils <NUM> and the current provided to the levitation coils <NUM>. In some embodiments, the first current sensor <NUM> and/or the second current sensor <NUM> are located outside of the housing <NUM>. For example, in some embodiments, the first current sensor <NUM> and/or the second current sensor <NUM> may be connected to the controller <NUM> (shown in <FIG>) and/or the power source <NUM> (shown in <FIG>).

The rotor position sensor <NUM> is configured to detect a position of the rotor <NUM> relative to the stator <NUM>. For example, in the illustrated embodiment, the rotor position sensor <NUM> is a Hall effect sensor which provides an output voltage that is directly proportional to the strength of a magnetic field that is located between the pole pieces <NUM> and the permanent magnet <NUM>. The rotor position sensor <NUM> may provide the output voltage to the on-board controller <NUM> as a continuous data stream. The on-board controller <NUM> may continuously track the position of the rotor <NUM> by relating the data stream to a position of the rotor <NUM> relative to the stator <NUM>. The data stream from the rotor position sensor <NUM> may be used to selectively attract and repel the permanent magnetic poles S and N of the permanent magnet <NUM> to adjust the position of the rotor <NUM> and/or cause the rotor <NUM> to rotate within the stator <NUM> during operation of the blood pump assembly <NUM>.

In the illustrated embodiment, the blood pump assembly <NUM> includes two pressure sensors <NUM> configured to detect a pressure of blood flowing through the blood flow path <NUM>. For example, as shown in <FIG> and <FIG>, in the illustrated embodiment, each pressure sensor <NUM> includes a sensing element <NUM> and a deflectable membrane <NUM> positioned between the sensing element <NUM> and the blood flow path <NUM>. The blood pump assembly <NUM> can include more than or less than two pressure sensors <NUM> in other embodiments.

The pressure sensors <NUM> are located such that each of the pressure sensors <NUM> can detect the pressure of fluid flow through the blood flow path <NUM>. For example, in the illustrated embodiment, the pressure sensors <NUM> are located adjacent the downstream end <NUM> of the inlet cannula <NUM>, at the interface between the inlet cannula <NUM> and the pump housing <NUM>. More specifically, the pressure sensors <NUM> are located between an outlet <NUM> of the inlet cannula <NUM> and an inlet <NUM> to the rotor chamber <NUM>.

The accelerometer <NUM> of the example embodiment is mounted to a circuit board <NUM> of the on-board controller <NUM>, and is configured to detect acceleration of the blood pump assembly <NUM> in at least one direction. For example, the accelerometer <NUM> may be a three-axis linear accelerometer configured to measure acceleration in three directions.

In the illustrated embodiment, the blood pump assembly <NUM> has an axis <NUM> about which the rotor <NUM> rotates. In the illustrated embodiment, the blood flow path <NUM> extends along the axis <NUM>. The accelerometer is configured to detect acceleration of the blood pump assembly <NUM> in a first direction parallel to the axis <NUM>, a second direction perpendicular to the axis <NUM>, and a third direction perpendicular to the axis <NUM> and perpendicular to the second direction. The accelerometer is configured to provide a data stream to the controller <NUM> indicating the detected acceleration. In some embodiments, the on-board controller <NUM> is configured to determine a patient's activity level, the orientation of the blood pump <NUM>, and/or a displacement of the blood pump <NUM> or heart wall based on acceleration in at least one of the first direction, the second direction, and the third direction. In other embodiments, the blood pump assembly <NUM> may include a plurality of accelerometers <NUM> and each accelerometer <NUM> may provide information on acceleration in at least one direction.

The on-board controller <NUM> can include one or more modules or devices that are enclosed within the pump housing <NUM>. The on-board controller <NUM> can generally include any suitable computer and/or other processing unit, including any suitable combination of computers, processing units and/or the like that may be communicatively coupled to one another (e.g., on-board controller <NUM> can form all or part of a controller network). Thus, on-board controller <NUM> can include one or more processor(s) and associated memory device(s) configured to perform a variety of computer-implemented functions (e.g., performing the methods, steps, calculations and/or the like disclosed herein). As used herein, the term "processor" refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field programmable gate array (FPGA), and other programmable circuits. Additionally, the memory device(s) of on-board controller <NUM> may generally include memory element(s) including, but not limited to, non-transitory computer readable medium (e.g., random access memory (RAM), read only memory (ROM)), computer readable non-volatile medium (e.g., a flash memory), a floppy disk, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD) and/or other suitable memory elements. Such memory device(s) can generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s), configure the on-board controller <NUM> to perform various functions including, but not limited to, controlling the supply of electrical current to the stator <NUM>, determining a waveform relating to a pump operating parameter, a cardiac characteristic, or a pump control parameter, determining or calculating cardiac events or characteristics based on information provided by the plurality of sensors <NUM>, such as heart rate, contractility, end-systolic pressure, end-diastolic pressure, atrial kick pressure, left ventricular contractility, max left ventricular pressure, and left ventricular relaxation, adjusting the speed of the rotor <NUM> based on information provided by the plurality of sensors <NUM> and/or one or more of the determined cardiac events or characteristics, outputting measurement data to an external controller (e.g., external system controller <NUM>), and various other suitable computer-implemented functions. In addition, the memory can be used to store patient specific parameters that are used by the on-board controller <NUM> to control patient specific operational aspects of the blood pump assembly <NUM>, as well as related software modules.

In the illustrated embodiment, the on-board controller <NUM> is implemented as one or more circuit boards <NUM> (shown in <FIG>) and various components carried on the circuit boards (e.g., processors and memory devices) to control operation of the blood pump <NUM> by controlling the electrical supply to the stator <NUM>.

A communication line (e.g., communication line <NUM> shown in <FIG>) couples the blood pump assembly <NUM> and on-board controller <NUM> to the external system controller <NUM> (shown in <FIG>), which monitors system operation via various software applications. As noted above, the blood pump assembly <NUM> itself also includes several software applications that are executable by the on-board controller <NUM> for various functions, such as to control radial levitation and/or drive of the rotor <NUM> of the pump assembly <NUM> during operation. The external system controller <NUM> can in turn be coupled to batteries <NUM> or a power module (not shown) that connects to an AC electrical outlet. The external system controller <NUM> can also include an emergency backup battery (EBB) to power the system (e.g., when the batteries <NUM> are depleted) and a membrane overlay, including Bluetooth capabilities for wireless data communication. An external computer that is configurable by an operator, such as clinician or patient, can further be coupled to the circulatory support system <NUM> for configuring the external system controller <NUM>, the implanted blood pump assembly <NUM>, and/or patient specific parameters, updating software on the external system controller <NUM> and/or the implanted blood pump assembly <NUM>, monitoring system operation, and/or as a conduit for system inputs or outputs.

<FIG> is a schematic view of a sensing and control system <NUM> suitable for use in the mechanical circulatory support system <NUM> of <FIG>. The sensing and control system <NUM> includes a controller <NUM> which, in some embodiments, may comprise at least one of controller <NUM> (shown in <FIG>) and/or on-board controller <NUM> (shown in <FIG>). The controller <NUM> includes an operator interface module <NUM>, a pump control module <NUM>, and a sensor-processing module <NUM>. In some embodiments, one or more of the operator interface module <NUM>, the pump control module <NUM>, and the sensor-processing module <NUM> are located at a computing unit that is separate from the controller <NUM> and on-board controller <NUM>.

Sensing and control system <NUM> further includes the plurality of sensors <NUM>, which includes the pressure sensor <NUM>, the first current sensor <NUM>, the second current sensor <NUM>, the accelerometer <NUM>, and the rotor position sensor <NUM>. The plurality of sensors <NUM> are connected to the controller <NUM> by suitable electrical conduits for receiving electrical power therefrom and sending signals thereto. For example, the signal-processing module <NUM> of the controller <NUM> is configured to receive a data stream from the pressure sensors <NUM>, the first current sensor <NUM>, the second current sensor <NUM>, the accelerometer <NUM>, and the rotor position sensor <NUM>. In addition, the controller <NUM> may generate a supplemental data stream based on the data streams received from the plurality of sensors <NUM>. For example, the controller <NUM> may determine a supplemental data stream indicating a pressure of the blood flowing out of the blood pump <NUM> through the outlet <NUM> based on measurements from the first current sensor <NUM> and at least one of the pressure sensors <NUM>.

The signal-processing module <NUM> is configured to filter the data streams received from the plurality of sensors <NUM>. For example, some of the data streams may include a waveform signal and the signal-processing module <NUM> may perform a waveform feature extraction on the data streams. During the waveform feature extraction process, the signal-processing module <NUM> identifies characteristics of the waveform signal that represent measured values such as bearing current, rotor position, blood flow through the blood pump assembly <NUM>, pressure of the blood exiting the blood pump assembly <NUM> (e.g., aortic pressure), and pressure of blood entering the blood pump assembly <NUM> (e.g., left ventricle LV pressure). In addition, the signal-processing module <NUM> may identify patient activity level, pump orientation, and motion of the left ventricle LV based on the data streams from the accelerometer and/or other sensors of the plurality of sensors <NUM>.

In some embodiments, the signal-processing module <NUM> may perform a spectral analysis on the data streams based on frequency spectrums. For example, in some embodiments, the spectral analysis includes applying a fast Fourier transform (FFT) to the data streams to identify characteristics of the data streams such as the frequency and amplitude content of any periodic signals in the data streams. In some embodiments, an FFT may be applied to the accelerometer data stream and the transformed data stream may indicate frequencies associated with a rotor spin rate (rotor speed and its harmonics) along with other vibratory signals such as vibrations from valve closing. The vibratory signals provide "heart sounds" (colloquially referred to as "lub dub" sounds) which can be interpreted in accordance with known diagnostic practices. For example, changes in amplitude of the heart sound frequencies may be used to detect a degree of valve opening and even to diagnose valvular disorders such as aortic regurgitation or stenosis.

Also, the signal-processing module <NUM> may be configured to remove noise or artifacts from the signal and/or adjust parameters of the waveform based on preset thresholds and ranges. In other words, the signal-processing module <NUM> "cleans-up" the raw data stream to provide a filtered data stream that is simpler for controller <NUM> to use in calculations and/or to output.

The controller <NUM> is also configured to compare the data streams and/or values determined based on the data streams, and determine a signal quality parameter for each data stream received at the signal-processing module from the sensors <NUM>. For example, the controller <NUM> may determine a pump operating parameter, a cardiac characteristic, or a pump control parameter based on each data stream, and compare the determined values to each other to determine signal accuracy and reliability. In some embodiments, the controller <NUM> determines a value that is independently derivable from each data stream such as a heart rate. Based on the comparison, the controller <NUM> may associate a quality rating with each data stream or sensor <NUM>. For example, if one of the determined values differs from at least one other determined value, the controller <NUM> may identify which of the values is more likely to be correct and associate a higher quality rating with the data stream that was used to determine the value. The controller <NUM> may associate a lower quality rating with the other data stream. In some embodiments, data streams with lower quality ratings (e.g., quality ratings below a preset threshold) are omitted from further computations.

In addition, the controller <NUM> can be configured to determine at least one of a pump operating parameter, a cardiac characteristic, and a pump control parameter based on the filtered data streams. For example, the controller <NUM> may determine any of the following based on the filtered data streams: heart rate, cycle timing, bearing current amplitude, displacement amplitude of rotor <NUM>, maximum flow through the blood pump assembly <NUM>, minimum flow through the blood pump assembly <NUM>, average flow through the blood pump assembly <NUM>, amplitude of the flow through the blood pump assembly <NUM>, maximum rate of change of flow through the blood pump assembly <NUM>, minimum rate of change of flow through the blood pump assembly <NUM>, maximum aortic pressure, minimum aortic pressure, average aortic pressure, maximum rate of change of aortic pressure, minimum rate of change of aortic pressure, maximum left ventricle pressure, minimum left ventricle pressure, average left ventricle pressure, maximum rate of change of left ventricle pressure, minimum rate of change of left ventricle pressure, maximum left ventricle acceleration, pitch angle of blood pump assembly <NUM>, yaw angle of the blood pump assembly <NUM>, activity level of the patient, and degree of aortic valve opening.

For example, the controller <NUM> may be programmed to determine the heart rate of a patient by applying a fast Fourier transform to the pressure data collected by the pressure sensors <NUM>, and/or by calculating a time interval between cardiac cycle detection points evident from the pressure waveform (e.g., beginning of systole, end of systole, beginning of diastole, and/or end of diastole). The controller <NUM> may also be programmed to determine ventricular filling pressure or minimum pressure, maximum pressure or maximum systolic pressure, pressure amplitude (i.e., the difference between maximum pressure and minimum pressure), average pressure, contractility (i.e., maximum systolic dP/dt), relaxation (i.e., minimum systolic dP/dt), end systolic pressure, end diastolic pressure, atrial kick pressure, and any other cardiac characteristic by applying mathematical operations to the data collected by the sensors <NUM>.

Moreover, the controller <NUM> may combine two or more of the data streams to determine the pump operating parameter, the cardiac characteristic, and/or the pump control parameter. In some embodiments, the controller <NUM> combines data streams and provides a statistically weighted value. In other words, the controller <NUM> determines a statistical weight of each data stream based on the quality rating, preset criteria, and/or any other suitable factor, and calculates the value with the determined weights applied to each of the data streams.

For example, in some embodiments, the controller <NUM> may determine a heart rate value based on the accelerometer data stream, flow waveform data stream, and LV pressure waveform data stream by applying a fast Fourier transform to each data stream. Applying the FFT to the data streams may highlight peaks in the low frequency domain (e.g., the low frequency domain may be in a range of about <NUM> to about <NUM>) in each data stream, and a heart rate value may be determined based on each data stream. In some embodiments, the heart rate value determined based on the flow waveform data stream may be used as the derived value because the flow waveform data stream may have the highest quality and accuracy rating of the received data streams. For example, the flow waveform data stream may have a higher signal-to-noise and sampling rate than the accelerometer and LV pressure waveform data streams. However, the derived value may be compared to the heart rate values determined based on the accelerometer and LV pressure waveform data streams to provide a confidence rating for the derived value. For example, the derived value may have a high or strong confidence rating if one or both of the accelerometer and LV pressure waveform data streams provide a heart rate value that matches or is within a predetermined tolerance range of the derived value. The derived value may have a low or weak confidence rating if one or both of the accelerometer and LV pressure waveform data streams provide a heart rate value that is outside a predetermined tolerance range of the derived value.

Additionally, in some embodiments, the controller <NUM> is configured to determine an operating parameter of the blood pump assembly based on a multi-variable algorithm or function that takes into account one or more of the measured values and the determined cardiac characteristics or events. In some embodiments, for example, the controller <NUM> is configured to determine a target rotor speed based on a statistically weighted function with one or more of the following variables: heart rate, minimum ventricle pressure, ventricle pressure amplitude, and maximum dP/dt.

The signal-processing module <NUM> may output the determined value(s) to the pump control module <NUM> and/or the operator interface module <NUM>. The operator interface module <NUM> may present the values to an operator using an input/output device <NUM> connected to the controller <NUM>. The input/output device <NUM> may include, for example and without limitation, input devices including a keyboard, mouse, touchscreen, joystick(s), throttle(s), buttons, switches, and/or other input devices. For example, and without limitation, the input/output device <NUM> may include output devices including a display (e.g., a liquid crystal display (LCD), or an organic light emitting diode (OLED) display), speakers, indicator lights, instruments, and/or other output devices. In some embodiments, the operator interface module <NUM> is configured to receive at least one operator input such as a patient's clinical condition and provide the operator input to the pump control module <NUM> for use in controlling operation of the blood pump assembly <NUM>. The patient's clinical condition may be clinical measurement or observation by a medical professional such as a heart characteristic or a medical diagnosis.

The pump control module <NUM> may use the determined value(s) to control operation of the blood pump assembly <NUM>. Accordingly, the controller <NUM> may provide at least partially autonomous or closed-loop control of the blood pump assembly <NUM> by using the information received from the sensors to modify operation of the blood pump assembly <NUM>. In some embodiments, the controller <NUM> provides operational control using any of the following based on the determined value(s): rotational speed of the rotor <NUM>, mean VAD flow control, VAD flow amplitude control, minimum left ventricle LV control, left ventricle LV pressure amplitude control, and combinations thereof. For example, in some embodiments, the pump control module <NUM> is included on the on-board controller <NUM> and is configured to control a rotational speed of the rotor <NUM> based on the determined value(s) received from the signal-processing module <NUM>. For example, the on-board controller <NUM> is operatively connected to the stator <NUM>, and configured to control operation of the blood pump <NUM> by controlling the supply of electrical current to the stator <NUM> and thereby control rotation of the rotor <NUM>. The pump control module <NUM> can be configured to control the rotor <NUM> in continuous flow operation and/or pulsatile flow operation.

In some embodiments, for example, the controller <NUM> is configured to control operation of the blood pump <NUM> to achieve a desired or preset cardiac characteristic. The controller <NUM> can periodically or continuously query the sensors <NUM>, and compare the detected or determined values with one or more set points (e.g., a pressure set point, a flow set point). If the detected or determined values are different from the set point, the controller <NUM> can adjust the operation of the blood pump assembly <NUM> to achieve the set point. In some embodiments, the controller <NUM> is configured to determine if the difference between the characteristic and the set point exceeds a threshold difference before adjusting the operation of the blood pump assembly <NUM>.

The set point can be established by operator input, for example, from a patient or a clinician, and can be stored in a memory device of the controller <NUM>. The set point can be a fixed (i.e., time invariable) set point, or the set point can be a time variable set point. For example, a pressure set point can vary according to different phases of the cardiac cycle. That is, the pressure set point can be defined by a pressure profile that defines a desired or target pressure set point at different times or phases of the cardiac cycle. In addition, the operator input can include a plurality of set points and the controller <NUM> can select a set point based on a determined operating parameter and/or cardiac characteristic. In some embodiments, the set point(s) can include a nominal flow set point, a nominal rotor speed set point, a flow amplitude set point, and/or a set point for any other suitable operating parameter.

Further, in some embodiments, the set point may be adjusted in real time based on measurements received from the sensors <NUM> and/or the determined cardiac events or characteristics. For example, in some embodiments, the controller <NUM> is configured to increase or decrease a pressure set point based on the maximum slope of the measured ventricle pressure waveform (dP/dt). The maximum dP/dt is related to the contractility of the left ventricle, and can be used to adjust the pressure set point, and the resulting rotor speed, to achieve a desired left ventricle unloading. For example, the controller <NUM> may be configured to increase the pressure set point and/or the rotor speed based on the determined maximum dP/dt to increase left ventricle unloading. Further, in some embodiments, the controller <NUM> is configured to increase or decrease the pressure set point based on a determined heart rate of a patient. For example, an increased heart rate is indicative of increased need for cardiac output (e.g., from exercise), and the controller <NUM> can be configured to increase the pressure set point by a corresponding amount. Additionally or alternatively, the controller <NUM> may be configured to increase or decrease the pressure set point based on feedback received from the accelerometer <NUM> included in the blood pump assembly <NUM>. For example, the controller <NUM> may determine that a user of the blood pump assembly <NUM> is exercising or engaged in rigorous activity based on feedback from the accelerometer <NUM>, and increase the pressure set point or speed of the rotor accordingly.

In various embodiments, the controller <NUM> may determine certain pump operating and/or patient conditions based on measurements received from the sensors <NUM>, and control the blood pump <NUM> accordingly. For example, Table <NUM> below is an exemplary correlation table illustrating how measured and/or determined parameters from sensors <NUM> may be associated and/or correlated with pump operating conditions and patient conditions. In particular, for a specific parameter, listed in the left-most column, Table <NUM> illustrates how a positive (+) or negative (-) deviation from an average or expected value for the parameter is correlated with a particular pump condition ("Suction") and/or one of several patient conditions ("Arrhythmia", "Hypertension", "Exercise", "Sleep", and "Recovery").

In Table <NUM>, the rotor displacement amplitude refers to the average peak-to-peak radial rotor displacement amplitude for a period of time, provided in units of micrometers (µm). The rotor displacement amplitude may be determined based on the data stream from the rotor position sensor <NUM>. The bearing current amplitude refers to the average peak-to-peak bearing current amplitude over the period of time, provided in units of milliamperes (mA). The bearing current amplitude may be determined based on the data stream from the current sensors <NUM>. The minimum, mean, and maximum flow values refer to the average minimum, mean, and maximum flow, respectively, for the period of time, provided in units of liters per minute. The flow amplitude refers to the average peak-to-peak flow amplitude rate for the period of time, provided in units of liters per minute. The flow values may be determined based on the data stream from the current sensors <NUM>. The minimum, mean, and maximum LV pressure values refer to the average minimum, mean, and maximum left ventricular pressure values, respectively, for the period of time, provided in units of millimeters of mercury (mmHg). The LV pressure amplitude refers to the average peak-to-peak left ventricular pressure amplitude over the period of time, provided in units of mmHg. The LV pressure values may be determined based on the data stream from the inflow pressure sensors <NUM>. The maximum LV wall velocity refers to the average peak left ventricular wall velocity during systole over the period of time, provided in units of millimeters per second. The maximum LV wall velocity may be determined based on the data stream from the accelerometer <NUM>. The patient activity level refers to the overall patient activity level provided as a percentage of a maximum level indicated as an "exercise" state of the patient. The patient activity level may be determined based on the data stream from the accelerometer <NUM>. The minimum, mean, and maximum aortic pressure refer to the average minimum, mean, and maximum aortic pressure, respectively, for the time period, provided in mmHg. The minimum, mean, and maximum aortic pressure may be determined based on the data stream from the current sensors <NUM> and the pressure sensors <NUM>. The aortic pressure amplitude refers to the average peak-to-peak aortic pressure amplitude for the period of time, provided in mmHg. The aortic pressure amplitude may be determined based on the data stream from the current sensors <NUM> and the pressure sensors <NUM>. The heart rate refers to the average heart rate for the period of time, provided in beats per minute. The heart rate variability refers to the variability in average heart rate over the period of time, provided as a percentage. The systolic percentage refers to the average percentage of a cardiac cycle spent in systole. The heart rate, heart rate variability, and systolic percentage may be determined based on the data streams from the rotor position sensor <NUM>, the current sensors <NUM>, the pressure sensors <NUM>, and the accelerometer <NUM>. The LV systolic elastance (contractility) refers to the slope of the LV elastance curve during systole (from a pressure-volume (PV) loop) which measures the contractility of the left ventricle, provided in units of mmHg/mL. The LV diastolic elastance refers to the slope of the left ventricular elastance curve during diastole (PV loop) which measures the diastolic stiffness of the left ventricle, provided in units of mmHg/mL. The LV filling status is a derived value that combines the minimum left ventricular pressure and flow amplitudes, and is provided as a percentage. The aortic valve flow refers to the estimated total flow through the aortic valve, provided in units of liters per minute. The total cardiac output refers to the estimated total cardiac output, provided in units of liters per minute. The VAD work share refers to a percentage value of the total hydraulic work (systemic circulation) performed by the ventricular assist device compared to the left ventricle. The systemic vascular resistance refers to the average systemic resistance over the time period, provide in units of mmHg/liters per minute. The overall exertion status is a derived value that combines patient activity level, the LV filling status, and the heart rate, and is provided as a percentage. The inflow occlusion is a percentage of occlusion or blockage of the inflow (where <NUM>% represents complete occlusion of the inflow and <NUM>% represents completely open inflow). The outflow occlusion is a percentage of occlusion of the outflow.

A number of the parameters in Table <NUM> are derived from two or more measured or determined data streams. For example, the hemodynamic status parameters (the LV systolic elastance, the LV diastolic elastance, the LV filing status, the aortic valve flow, the total cardiac output, and the VAD work share) may be determined based on the left ventricle pressure waveform and the flow waveform. Also, the systemic vascular resistance, the overall exertion status, the inflow occlusion, and the outflow occlusion may be determined based on the left ventricle pressure waveform and the flow waveform.

As shown in Table <NUM>, the parameters may be used to indicate pump operating conditions and patient conditions. For example, the controller <NUM> may recognize positive and negative variations (+/-) from an average or expected value for each parameter, and associate the variation with one or more conditions in Table <NUM>, listed along the top row. The conditions indicated with a "+"are associated with a positive variation from average or expected value for the respective parameter. The conditions indicated with a "-" are associated with a negative variation from the average or expected value for the respective parameter.

In some embodiments, significance values may be assigned to the parameters when multiple parameters are associated with a single condition. The parameters may be weighted based on the significance values to provide a more accurate indication of the conditions. The significance values may be based on the quality ratings of the data feeds from sensors, the determined reliability of the parameter, and/or any other suitable factor. In such embodiments, the controller <NUM> may weight the parameters based on the significance values to determine a pump operating condition or patient condition indicated by the positive and negative deviations. For example, Table <NUM> below illustrates a list of exemplary significance ratings for the parameters listed in Table <NUM>, using a scale in which <NUM> represents the greatest significance and <NUM> represents the lowest significance.

As noted above, the controller <NUM> may control the blood pump <NUM> based on the pump operating condition and/or patient condition determined from the data feeds received from the plurality of sensors <NUM>. For example, Table <NUM> below illustrates an exemplary control scheme that may be implemented by controller <NUM> to control the blood pump <NUM>. Specifically, Table <NUM> indicates under which conditions controller <NUM> will increase pump speed ("+") relative to a rotor speed set point, and under which conditions the controller <NUM> will decrease pump speed ("- ") relative to a rotor speed set point.

Additionally, in some embodiments, the controller <NUM> is configured to control the speed of the rotor <NUM> according to a speed profile that defines a time-variable speed set point of the rotor <NUM>. In such embodiments, the controller <NUM> can be configured to modulate the speed of the rotor <NUM> to different speed set points within a single cardiac cycle of a patient's heart. This type of rotor speed control, also known as "synchronized pulsing", may be implemented by the controller <NUM> in any suitable manner that enables the blood pump assembly <NUM> to function as described herein. In some embodiments, for example, the controller <NUM> can be configured to increase the speed of the rotor <NUM> during systole (known as "co-pulsation"), or decrease the speed of the rotor <NUM> during systole (known as "counter-pulsation"). In yet other embodiments, the controller <NUM> can be configured to increase the speed of the rotor <NUM> over a first period of time during systole, and decrease the speed of the rotor <NUM> over a second period of time during systole. Additionally, synchronized pulsing of the rotor may be implemented by the controller <NUM> at varying intervals. For example, the controller <NUM> can be configured to modulate the speed of the rotor <NUM> to different speed set points within a single cardiac cycle of a patient's heart, or across more than one cardiac cycle of a patient's heart (for example, across two cardiac cycles).

In other embodiments, the controller <NUM> is configured to control the speed of the rotor <NUM> according to a fixed (i.e., time invariable) speed set point. In such embodiments, the controller <NUM> can be configured to control the speed of the rotor <NUM> to achieve an average speed equal to the speed set point. Rotor speed profiles and/or set points can be established by operator input, for example, from a patient or a clinician, and can be stored in a memory device of the controller <NUM>.

Suitably, the control and sensing system <NUM> is configured to combine information from different sensors <NUM> to provide operating parameters for different operating states of the blood pump assembly <NUM>. For example, the controller <NUM> may rely primarily on sensors <NUM> other than the current sensors <NUM>, <NUM> when the blood pump assembly <NUM> is in a pulsing mode because the current sensors <NUM>, <NUM> may not provide continuous data streams when the blood pump assembly <NUM> is operating in the pulsing mode.

In addition, the controller <NUM> may switch between the operating states based on the information received from the sensors <NUM>. For example, the filtered data stream from the accelerometer <NUM> may indicate that the patient is active and the controller <NUM> may alter the pulse synchronization process based on the information from the accelerometer <NUM>. In some embodiments, the controller <NUM> may select a pulse mode (e.g., co-pulse mode in which pump speed increases during systole, counter-pulse mode in which pump speed decreases during diastole, a combination of co-pulse and counter-pulse, or asynchronous pulse mode) of the blood pump assembly <NUM> based on the information from the plurality of sensors <NUM>. In addition, the controller <NUM> may select one or more pulse parameters (e.g., amplitude, frequency, duration) based on the information from the plurality of sensors <NUM>.

As noted above, one or more of the determined cardiac events or characteristics may be used by the controller <NUM> to perform closed-loop speed control of the pump rotor <NUM>. For example, an increase in heart rate, minimum ventricle pressure, or ventricle pressure amplitude generally indicates an increased need for cardiac output. Accordingly, in some embodiments, the controller <NUM> is configured to adjust the speed of the rotor <NUM> by a corresponding amount when data from at least one of the sensors <NUM> indicates an increase in heart rate, minimum ventricle pressure, and/or ventricle pressure amplitude.

Additionally, in some embodiments, one or more of the determined cardiac events or characteristics can be used to examine and/or evaluate physiologic cardiac function. For example, the left ventricle pressure amplitude (i.e., the difference between maximum pressure and minimum pressure) is a combined indicator of both filling pressure and heart contractility. The minimum dP/dt can be used to evaluate the relaxation speed of the ventricle and to identify possible fibrosis or electrical conduction issues. The maximum dP/dt can be used to evaluate the systolic elastance curve of the ventricle, which is a direct measure of left ventricle functional performance. This may be used, for example, to detect left ventricle recovery, and to adjust the target pressure and/or rotor speed set points stored in controller <NUM> accordingly.

<FIG> is an example plot of data that may be collected and output by the pressure sensors <NUM> during operation of the blood pump assembly <NUM>. The example plot illustrates the left ventricle pressure waveform <NUM> (i.e., pressure vs. time) over a period of about <NUM> seconds. The signal-processing module <NUM> may receive the waveform <NUM> and perform the filtering operation, e.g., the waveform extraction, and then determine one or more values based on the filtered data stream. For example, the controller <NUM> may be configured to determine the ventricular filling pressure or minimum pressure by identifying a local minimum pressure value on the pressure waveform within a single phase of the cardiac cycle. An example ventricular filling pressure value is identified at point <NUM> in <FIG>. Additionally, the controller <NUM> may be configured to determine maximum systolic pressure by identifying a local maximum pressure value on the pressure waveform within a single phase of the cardiac cycle. An example maximum systolic pressure value is identified at point <NUM> in <FIG>. The controller <NUM> may be further configured to determine the pressure amplitude <NUM> within a single cardiac phase of the pressure waveform by determining the difference between the maximum pressure <NUM> and the minimum pressure <NUM>. The controller <NUM> may be further configured to determine contractility by determining the maximum slope <NUM> of the pressure waveform within the systolic phase of a single cardiac cycle. The controller <NUM> may also be configured to determine relaxation by determining the minimum slope <NUM> of the pressure waveform within the systolic phase of a single cardiac cycle. The controller <NUM> may also be configured to determine end-systolic pressure and end-diastolic pressure by identifying pressure values along the pressure waveform at the end of the systolic and diastolic phases, respectively, of the cardiac cycle. The controller <NUM> may also be configured to identify atrial kick pressure by identifying the pressure value at a localized maximum value on the pressure waveform within the diastolic phase of a single cardiac cycle (i.e., between the end of systole of a first cardiac cycle and the beginning of systole of a second cardiac cycle). The controller <NUM> may be configured to determine or identify the various phases of the cardiac cycle (e.g., systole and diastole) for the pressure waveform based on, for example, minimum pressure values, maximum pressure values, maximum slope values, and minimum slope values. For example, the controller <NUM> may be configured to determine that a certain portion of the pressure waveform corresponds to the systolic phase of the cardiac cycle by determining or identifying a region on the pressure waveform between the maximum slope and the minimum slope.

<FIG> is an example plot of data that may be collected and output by the plurality of sensors. The example plot illustrates an acceleration waveform <NUM>, a rotor position waveform <NUM>, a rotor speed waveform <NUM>, a flow waveform <NUM>, and an estimated flow waveform <NUM>. For example, the acceleration waveform <NUM> is based on data collected by the accelerometer <NUM>. The rotor position waveform <NUM> is based on data collected by the rotor position sensor <NUM>. The flow waveform <NUM> is based on values determined using data streams from one or more of the sensors <NUM>, such as the first current sensor <NUM> and the pressure sensors <NUM>. The data shown in the example plot was collected while the controller <NUM> was operating to synchronize the blood pump assembly <NUM> pulse to the heart pulse using measurements from the current sensors <NUM>, <NUM>. For example, the controller <NUM> identified when the instantaneous current/flow reading switched between a low and high value and changed operation of the blood pump assembly to accommodate changes. The instantaneous current/flow reading was considered a high value when the instantaneous current/flow reading was above an average flow value and considered a low value when instantaneous current/flow reading was below the average flow value. The controller <NUM> recognized the onset of systole when the instantaneous current/flow reading transitioned from a low value to a high value and indicated a change from diastolic flow to systolic flow. The controller <NUM> then operated the blood pump assembly <NUM> to account for the onset of systole.

<FIG> is another example plot of data that may be collected and output by the plurality of sensors. The example plot illustrates an acceleration waveform <NUM>, a rotor position waveform <NUM>, a rotor speed waveform <NUM>, a flow waveform <NUM>, and an estimated flow waveform <NUM>. For example, the acceleration waveform <NUM> is based on data collected by the accelerometer <NUM>. The rotor position waveform <NUM> is based on data collected by the rotor position sensor <NUM>. The flow waveform <NUM> is based on values determined using data streams from one or more of the sensors <NUM>. The data shown in the example plot was collected while the controller <NUM> was operating to synchronize the pulse of the blood pump assembly <NUM> to the heart pulse using measurements from an outflow flow sensor positioned on an exterior of the blood pump assembly <NUM>.

<FIG> and <FIG> are flow diagrams illustrating one embodiment of a method <NUM> of operating an implantable blood pump (e.g., blood pump <NUM>) in a patient. In the illustrated embodiment, the method <NUM> includes detecting <NUM> a current provided to a stator (e.g., stator <NUM>) using a current sensor (e.g., current sensors <NUM>, <NUM>), detecting <NUM> a position of a rotor (e.g., rotor <NUM>) relative to a housing (e.g., housing <NUM>) using a rotor position sensor (e.g., rotor position sensor <NUM>), detecting <NUM> an acceleration of the blood pump in at least one direction using an accelerometer (e.g. accelerometer <NUM>), and detecting <NUM> a pressure of blood flowing through a flow path using a pressure sensor (e.g., pressure sensors <NUM>). The method <NUM> further includes receiving <NUM> a data stream from the current sensor at a signal-processing module (e.g., signal-processing module <NUM>) of a controller connected to the plurality of sensors, receiving <NUM> a data stream from the rotor position sensor at the signal-processing module, receiving <NUM> a data stream from the accelerometer at the signal-processing module, and receiving <NUM> a data stream from the pressure sensor at the signal-processing module.

The method <NUM> also includes filtering <NUM>, by a controller, each of the data streams received at the signal-processing module, and determining <NUM>, by the controller, at least one of a pump operating parameter, a cardiac characteristic, and a pump control parameter based on at least two of the filtered data streams. For example, in some embodiments, filtering the data streams includes performing a waveform feature extraction on the data streams. Features of the waveform (e.g., amplitude, frequency, wavelength) may indirectly correspond to pump operating conditions and/or to cardiac characteristic. Accordingly, one or more of the waveform features extracted from one or more of the data streams may be used by the controller to determine the pump operating parameter, the cardiac characteristic, or the pump control parameter.

The method <NUM> further includes outputting <NUM> the at least one of the pump operating parameter, the cardiac characteristic, and the pump control parameter from the signal-processing module to at least one of an operator interface module (e.g., operator interface module <NUM>) and a pump control module (e.g., pump control module <NUM>). The pump control module may control operation of the pump based on the value received from the signal-processing module. For example, in some embodiments, the pump control module controls a rotational speed of the rotor based on the value received from the signal-processing module. Also, in some embodiments, the operator interface module may provide the value received from the signal-processing module to an operator using a display.

In some embodiments, the method <NUM> further includes generating a supplemental data stream based on at least two of the data streams received by the signal-processing module. For example, the signal-processing module may determine a waveform of a pressure of the blood flowing out of the blood pump through the outlet based on the current provided to the stator and the pressure of the blood flowing through the flow path. Accordingly, the supplemental data stream may represent a pressure of the patient's blood flow (e.g., an aortic pressure). The supplemental data stream may be filtered and combined with or compared to the other filtered data streams. Moreover, the controller may determine at least one of a pump operating parameter, a cardiac characteristic, and a pump control parameter based on the additional filtered data stream.

Also, in some embodiments, the method <NUM> includes comparing the data streams received from each sensor. The data streams may be compared by determining a cardiac characteristic based on each data stream and comparing the determined cardiac characteristics. For example, the determined values may be evaluated to identify an outlier value, i.e., a determined value that differs significantly from at least two other values. In addition, the determined values may be compared to directly measured or estimated values to identify values that differ significantly from expected and/or measured cardiac characteristics. For example, in some embodiments, a patient's heart rate is determined based on each data stream. Each determined heart rate may be compared to an actual measured value of the patient's heart rate and/or a range of expected heart rates for the patient to check if the data streams are within preset accuracy ranges. In addition or alternatively, the determined heart rates are compared to each other to check if any of the data streams is significantly more/less accurate than other data streams.

In addition, in some embodiments, the method <NUM> includes associating a quality rating with each data stream. For example, the signal-processing module may assign a numerical or other value to each data stream based on a point grading system or a predetermined scale (e.g., a scale of <NUM>-<NUM>, with <NUM> being the lowest quality rating and <NUM> being the highest quality rating). The quality rating may allow the controller to weight the data streams and rely more heavily on data streams with higher quality ratings. In addition, in some embodiments, the controller may disregard data streams with quality ratings that do not meet a threshold value. Moreover, the controller may provide the quality rating of one or more of the data streams for presentation to the operator using an operator interface. In other embodiments, the data streams may be compared and rated in any suitable manner. For example, in some embodiments, the signal-processing module may compare and rate the data streams based on characteristics of the data streams such as signal strength.

<FIG> is a flow diagram illustrating example data flow and processing of data collected by sensors and processed by a controller (e.g., controller <NUM>, shown in <FIG>) during operation of an implantable blood pump (e.g., blood pump <NUM>) in a patient. In the illustrated embodiment, data feeds are provided by current sensors <NUM>, a rotor drive current sensor <NUM>, a LV pressure sensor <NUM>, and an accelerometer <NUM>. The accelerometer <NUM> includes a Z-acceleration component <NUM>, a Y-acceleration component <NUM>, and an X-acceleration component <NUM>.

The data feeds from the sensors <NUM>, <NUM>, <NUM>, <NUM> are transformed and/or filtered to extract a plurality of parameters. For example, the data feeds from the current sensors <NUM> undergo a bearing current transformation <NUM> and a rotor radial position calculation <NUM> to provide bearing current data and rotor radial position data, respectively. The resulting bearing current data and rotor radial position data undergo respective waveform feature extractions <NUM> and <NUM>. The bearing current waveform feature extraction <NUM> can be used to determine or extract various parameters <NUM>, including heart rate and cycle timing, and bearing current amplitude. Similarly, the rotor position waveform feature extraction <NUM> can be used to determine various parameters <NUM>, including heart rate and cycle timing (e.g., as a redundant value), and bearing displacement amplitude.

Additionally, a rotor speed <NUM> is calculated based on the data feed from the current sensors <NUM> and/or rotor drive current sensor <NUM>. For example, the controller receives one or more data streams of the displacement and the angular position of the rotor and determines how much drive current and bearing current to provide for the rotor based on the data streams. The provided bearing currents and drive currents are measured by one or more of the current sensors <NUM>. The measured drive currents relate directly to rotor speed <NUM>. Accordingly, the calculated rotor speed <NUM> can be determined based on the data feed from the rotor drive current sensor <NUM>. The calculated rotor speed <NUM> is used to calculate <NUM> a VAD flow value. The resulting VAD flow value undergoes a VAD flow waveform extraction <NUM>, which can be used to determine or extract various parameters <NUM>, including heart rate and cycle timing (e.g., as a redundant value), maximum, minimum, and mean flow (Q) (e.g., in liters per minute), flow amplitude (e.g., in liters per minute), and minimum and maximum slopes (dQ/dt) of the flow waveform.

Further, the calculated rotor speed <NUM> is used in combination with the data feed from the LV pressure sensor <NUM> to calculate <NUM> an aortic pressure value. The resulting aortic pressure value undergoes an aortic pressure (AOP) waveform extraction <NUM>, which can be used to determine or extract various parameters <NUM>, including heart rate and cycle timing (e.g., as a redundant value), maximum, minimum, and mean aortic pressure values (e.g., in mmHg), aortic pressure amplitude (e.g., mmHg), and minimum and maximum slopes (dAOP/dt) of the aortic pressure waveform.

In addition, the calculated VAD flow value <NUM> is used in combination with the data feed from the LV pressure sensor <NUM> to calculate <NUM> a left ventricular (LV) pressure value. The resulting LV pressure value undergoes an LV pressure (LVP) waveform extraction <NUM>, which can be used to determine or extract various parameters <NUM>, including heart rate and cycle timing (e.g., as a redundant value), maximum, minimum, and mean LV pressure values (e.g., in mmHg), LV pressure amplitude (e.g., mmHg), and minimum and maximum slopes (dLVP/dt) of the LV pressure waveform.

In the illustrated embodiment, the data feeds from the Z-acceleration component <NUM>, the Y-acceleration component <NUM>, and the X-acceleration component <NUM> undergo feature extraction processes to determine additional parameters. For example, the data feed from the Z-acceleration component <NUM> undergoes a wall motion feature extraction <NUM> process to determine or extract various parameters <NUM>, including heart rate and cycle timing (e.g., as a redundant value), and maximum LV acceleration (e.g., in mm/s/s).

Additionally, in the illustrated embodiment, the data feeds from the Z-acceleration component <NUM>, the Y-acceleration component <NUM>, and the X-acceleration component <NUM> are combined in a pump orientation determination function <NUM> to determine an orientation of the blood pump <NUM>. The pump orientation determination function <NUM> can be used to determine or extract various parameters <NUM>, including a pitch angle of the blood pump <NUM> and a yaw angle of the blood pump <NUM>.

Additionally, in the illustrated embodiment, the data feeds from the Y-acceleration component <NUM> and the X-acceleration component <NUM> are combined in a patient activity level determination function <NUM> to determine a patient activity level <NUM>.

Also, two or more of the extracted parameters may be combined to provide combined parameters <NUM> and/or signal quality metrics. The combined parameters <NUM> can include, for example and without limitation: heart rate, cardiac cycle variability, cardiac cycle percentage systole, minimum flow through the blood pump assembly <NUM>, maximum flow through the blood pump assembly <NUM>, average flow through the blood pump assembly <NUM>, amplitude of flow through the blood pump assembly <NUM>, maximum rate of change of flow through the blood pump assembly <NUM>, minimum rate of change of flow through the blood pump assembly <NUM>, maximum aortic pressure, minimum aortic pressure, average aortic pressure, amplitude of aortic pressure, maximum rate of change of aortic pressure, minimum rate of change of aortic pressure, maximum left ventricle pressure, minimum left ventricle pressure, average left ventricle pressure, amplitude of left ventricle pressure, maximum rate of change of left ventricle pressure, minimum rate of change of left ventricle pressure, maximum left ventricle acceleration, pitch angle of blood pump assembly <NUM>, yaw angle of the blood pump assembly <NUM>, and activity level of the patient.

In addition, one or more patient clinical conditions <NUM> may be determined based on the combined parameters <NUM>. The clinical conditions <NUM> can include, for example and without limitation: LV systolic elastance (contractility), LV diastolic elastance, LV relaxation constant, LV filling status, aortic valve flow, total cardiac output, VAD work share, systemic vascular resistance, aortic compliance, overall exertion status of the patient, inflow occlusion, and outflow occlusion.

Although certain steps of the example methods are numbered, such numbering does not indicate that the steps must be performed in the order listed. Thus, particular steps need not be performed in the exact order they are presented, unless the description thereof specifically require such order. The steps may be performed in the order listed, or in another suitable order.

As described herein, the implantable blood pump assemblies of the present disclosure provide several advantages over previous VAD designs. For example, embodiments of the implantable blood pump assemblies disclosed herein include a plurality of sensors connected to a controller. By combining and/or comparing data streams from the plurality of sensors, the blood pump assemblies provide a greater scope of information and more reliable information than previous systems. Also, a controller is able to determine and provide information related to the signal accuracy of the plurality of sensors which can provide greater operator confidence in the accuracy and reliability of the system. Moreover, the controller may determine values that are statistically weighted based on the comparison of information from the plurality of sensors to ensure accurate information is used for operating the blood pump assemblies. In addition, the implantable blood pump assemblies may be operate at least partially autonomously using the information provided by the plurality of sensors and the closed-loop controls of the controller connected to the plurality of sensors.

Although the embodiments and examples disclosed herein have been described with reference to particular embodiments, it is to be understood that these embodiments and examples are merely illustrative of the principles and applications of the present disclosure. It is therefore to be understood that numerous modifications can be made to the illustrative embodiments and examples and that other arrangements can be devised without departing from the scope of the present disclosure as defined by the claims.

Claim 1:
A circulatory support system (<NUM>) comprising:
an implantable blood pump (<NUM>) comprising:
a housing (<NUM>) defining an inlet (<NUM>), an outlet (<NUM>), a flow path (<NUM>) extending from the inlet (<NUM>) to the outlet (<NUM>), and an internal compartment (<NUM>) separated from the flow path (<NUM>);
a rotor (<NUM>) positioned within the flow path (<NUM>) and operable to pump blood from the inlet (<NUM>) to the outlet (<NUM>);
a stator (<NUM>) positioned within the internal compartment (<NUM>) and operable to drive the rotor (<NUM>);
a plurality of sensors (<NUM>) comprising:
a current sensor (<NUM>, <NUM>) configured to detect a current provided to the stator (<NUM>);
and
a pressure sensor (<NUM>) positioned between the inlet (<NUM>) and the outlet (<NUM>) and configured to detect a pressure of blood flowing through the flow path (<NUM>);
characterized by comprising a controller (<NUM>) connected to the plurality of sensors (<NUM>) and including a signal-processing module (<NUM>), an operator interface module (<NUM>), and a pump control module (<NUM>), wherein the signal-processing module (<NUM>) is configured to:
receive, from each of the plurality of sensors (<NUM>), a data stream;
filter the data streams received from the plurality of sensors (<NUM>);
determine a cardiac characteristic based on the filtered data streams; and
output the cardiac characteristic to at least one of the operator interface module (<NUM>) and the pump control module (<NUM>).