Medical device and method for estimating time between voltage levels of a power supply

Abstract

A medical device system and method estimates a time from a first voltage of a power source of a medical device to a second voltage of the power source. The medical device includes a sensor coupled to the power source for generating a physiological signal. The medical device system determines a current draw from the power source required to generate the physiological signal and / or process the physiological signal to detect an event from the physiological signal. A processor of the medical device system is configured to estimate the time from the first voltage to the second voltage of the power source based at least on the determined current draw.

Description

Technical Field

[0001] This disclosure generally relates to a medical device having a depletable power supply and a method for estimating the remaining time between two voltage levels of the power supply. Background Technology

[0002] Various medical devices for delivering therapy and / or monitoring physiological conditions are already in clinical use or proposed for clinical use in patients. Examples include medical devices that deliver therapy to a patient's heart, muscles, nerves, brain, stomach, or other organs or tissues and / or monitor conditions related to a patient's heart, muscles, nerves, brain, stomach, or other organs or tissues. Some medical devices may employ one or more electrodes to deliver therapeutic electrical signals to such organs or tissues and / or one or more electrodes to sense inherent electrical signals generated by such organs or tissues within the patient's body. Similarly, some medical devices may additionally or alternatively include one or more other sensors for sensing physiological parameters of the patient for monitoring medical conditions.

[0003] For example, some medical devices can act as pacemakers or cardioverter-defibrillators that deliver therapeutic electrical signals to the heart. Therapeutic electrical signals can include pulses for pacing or electric shocks for cardioversion or defibrillation. In some instances, the medical device can sense signals from the patient to control the delivery of therapeutic electrical signals. For example, intrinsic cardiac electrical signals accompanying cardiac depolarization can be sensed to control the delivery of therapeutic signals to the heart based on the sensed intrinsic signals. Upon detection of abnormal heart rhythms (such as bradycardia, tachycardia, or fibrillation), one or more appropriate therapeutic electrical stimulation pulses can be delivered to restore or promote a relatively more normal heart rhythm. For example, in some cases, implantable medical devices can deliver pacing stimulation to the patient's heart upon detection of tachycardia or bradycardia, and / or deliver cardioversion or defibrillation shocks to the heart upon detection of fibrillation. Rate-responsive pacemakers can sense signals from the patient that are related to the patient's physical activity to control the rate of cardiac pacing.

[0004] Implantable medical devices are typically powered by one or more internal batteries that deplete over time as battery capacity is used to power various electronic components and processors that perform the functions of the medical device, such as sensing signals from the patient via one or more sensors and / or generating and delivering therapy to the patient. Summary of the Invention

[0005] The technology disclosed herein generally relates to estimating the remaining time between two voltage points of a power source for a medical device. The medical device may be an implantable medical device (IMD), such as an implantable pulse generator (IPG) configured to deliver therapeutic electrical stimulation pulses powered by one or more batteries. For example, the IMD may be a pacemaker, an implantable cardioverter defibrillator (ICD), or a device that delivers therapeutic electrical stimulation to muscles, nerves, or the brain. In other instances, the IMD may be a medical monitor configured to sense physiological signals in the absence of therapeutic delivery capabilities.

[0006] A medical device operating according to the techniques disclosed herein determines an estimated remaining time between two voltages of the device's power supply by determining the current consumption required to perform the device's functions, which may vary over time. The determined current consumption may include estimates of sensor operation current consumption, processing load current consumption, and therapy delivery current consumption. Each of these current consumptions can be estimated based on the medical device's historical functionality since it was put into use for a patient, for example, from the time of IMD implantation.

[0007] In one example, a medical device system includes a power source, a sensor coupled to the power source to generate a physiological signal, control circuitry coupled to the power source and the sensor, and a processor. The control circuitry is configured to operate in an operating mode that includes detecting an event from the physiological signal. The processor is configured to determine the current consumption from the power source required for operation in the operating mode. The current consumption is associated with the current from the power source required for at least one of the following: generating the physiological signal or detecting the event from the physiological signal. The processor is further configured to determine an estimated time from a first voltage of the power source to a second voltage of the power source based on the current consumption and a power capacity difference. The first voltage of the power source corresponds to a first power capacity, and the second voltage corresponds to a second power capacity less than the first power capacity. The power capacity difference is the difference between the first power capacity and the second power capacity. The processor is configured to generate an output based on the estimated time. A memory may be configured to store data related to the estimated time in response to the generated output.

[0008] In another example, a method includes generating a physiological signal via a sensor, detecting an event from the physiological signal for operation in an operating mode of a medical device, and determining a current consumption from a power source required for operation in the operating mode. The current consumption is associated with a current from the power source required for at least one of: generating the physiological signal or detecting the event from the physiological signal. The method further includes determining an estimated time from a first voltage of the power source to a second voltage of the power source based on the current consumption and a power capacity difference. The first voltage of the power source corresponds to a first power capacity, and the second voltage corresponds to a second power capacity less than the first power capacity. The power capacity difference is the difference between the first power capacity and the second power capacity. The method further includes generating an output based on the estimated time, and may include storing data related to the estimated time in response to the generated output.

[0009] In another example, a non-transitory computer-readable medium stores a set of instructions that, when executed by a processing circuitry system of a medical device system, cause the medical device system to generate physiological signals via sensors, detect events from the physiological signals for operation in an operating mode of the medical device system, and determine the current consumption from a power source required for operation in the operating mode. The current consumption is associated with the current from the power source required for at least one of: generating the physiological signal or detecting the event from the physiological signal. The instructions further cause the medical device system to determine an estimated time from a first voltage of the power source to a second voltage of the power source based on the current consumption and a power capacity difference. The first voltage of the power source corresponds to a first power capacity, and the second voltage corresponds to a second power capacity less than the first power capacity. The power capacity difference is the difference between the first power capacity and the second power capacity. The instructions further cause the system to generate an output based on the estimated time, and cause the system's memory to store data related to the estimated time in response to the generated output.

[0010] Details of one or more aspects of this disclosure are set forth in the accompanying drawings and the following description. Other features, objects, and advantages described in this disclosure will become apparent from the description and drawings and from the claims. Attached Figure Description

[0011] Figure 1 This is a conceptual diagram illustrating an IMD system that includes a battery-powered IMD, which can be used to sense signals from a patient and deliver therapeutic electrical stimulation therapy.

[0012] Figure 2 yes Figure 1 The diagram shown is a conceptual representation of an IMD.

[0013] Figure 3 yes Figure 1 The diagram shows an example configuration of an IMD.

[0014] Figure 4 This is a graph showing the change in IMD power supply voltage over time since the start of service.

[0015] Figure 5 This is a flowchart illustrating a method for determining the predicted time between two voltage levels of an IMD power supply, based on an example.

[0016] Figure 6 This is a flowchart illustrating methods for determining the total current consumption and estimating the lifetime of an IMD, based on several examples.

[0017] Figure 7 It is an example lookup table based on the therapeutic delivery current consumption value stored in the IMD for an instance.

[0018] Figure 8 This is a flowchart of a method for determining comparative lifetime estimates that can be performed by a medical device system, based on an example.

[0019] Figure 9 It is a diagram of an example of a graphical user interface that can be generated by a medical device system to display estimated life expectancy information to a user. Detailed Implementation

[0020] Generally, this disclosure relates to medical devices and techniques for determining the estimated lifetime of a power source for a medical device between two voltage levels. As used herein, the term "lifetime" refers to the time between two voltage levels of a power source for a medical device, for example, in years, weeks, days, hours, or minutes. By estimating the lifetime or time from the current voltage level to a predetermined voltage level, the remaining lifespan of the medical device can be estimated and / or recommended times for recharging or replacing the power source (or replacing the medical device itself) can be reported, potentially before the end of the functional lifespan of the medical device. A medical device may be an IMD (In-Mortar Device), but is not necessarily an implantable device. For example, a medical device may be a wearable device or a battery-powered bedside or remote monitor. In various instances, a medical device implementing the techniques disclosed herein includes an internal or portable power source that depletes over time while it powers the functionality of the medical device. For example, the power source may include one or more rechargeable or non-rechargeable batteries.

[0021] As disclosed herein, techniques for estimating power supply lifetime include determining an estimated current consumption from the power supply required to perform various device functions that may vary over time. In some instances, the estimated current consumption may include the current consumption required to operate physiological sensors and / or process physiological signals generated by the sensors. For example, monitoring or therapy delivery functions may vary over time due to automatic or manual adjustments, depending on patient needs and / or the operating mode of the medical device. As a result, the current demand from the medical device's power supply for one or more electronic components (such as therapy delivery circuitry, sensor circuitry, or processing circuitry) may vary over time. Therefore, lifetime estimates can be determined by considering, at least in part, an estimate of the current consumption required to perform device functions that may vary over time, based on historical functional data that may be stored by the medical device.

[0022] For example, lifetime estimation might require determining the current consumption from the medical device's power supply needed to operate in a specific therapy delivery mode. A therapy delivery mode could be an operating mode of the medical device used to control and generate therapy delivered to a patient. Therapy delivery modes might require the generation of physiological signals via sensors for analysis and for controlling therapy delivery and timing. Therefore, lifetime estimation could include determining the current consumption associated with operating sensors to generate physiological signals and / or the processing load required for the processor to analyze physiological signals for controlling therapy delivery. Determining the estimated lifetime could further include estimating the current consumption required to generate and deliver therapy, for example, the current consumption required to generate electrical stimulation pulses such as cardiac pacing pulses. Multiple components of the estimated total current consumption can be determined, such as processing load current consumption, sensor operating current consumption, and / or therapy delivery current consumption, each of which can vary dynamically over time to estimate the power lifetime between two voltages of the medical device's power supply. The total current consumption may also consider the quiescent current consumption required to perform the functions of the medical device, which may be relatively static or constant during the functional lifetime of the medical device. By determining the current consumption estimates for the dynamic monitoring and / or therapy delivery functions of medical devices, lifespan estimates may be more accurate, thereby improving medical devices by providing more reliable notifications or warnings to users, clinicians, or caregivers when power is depleted.

[0023] Figure 1This is a conceptual diagram illustrating an IMD system 10, which can be used to sense signals from a patient and deliver therapeutic electrical stimulation therapy. In some instances, the IMD system 10 includes an IMD 14 that can be configured to communicate wirelessly with an external device 20. The IMD 14 is shown as a leadless cardiac pacemaker as an example of a medical device that can be configured to estimate power lifetime according to the techniques disclosed herein. The IMD 14 can be a transcatheter intracardiac pacemaker adapted for complete implantation within the heart chambers, such as complete implantation within the right ventricle (RV) of heart 8, as shown, complete implantation within the left ventricle (LV), or complete implantation within the atrium. Compared to subcutaneously implanted pacemakers or other IMDs, the IMD 14 can be smaller in size and can typically be cylindrical to allow for transvenous implantation via a delivery catheter. The IMD 14 is shown positioned along the endocardial wall within the RV, for example, near the apex of the RV, although various locations within or on the heart 8 or other implantation sites within the patient are possible.

[0024] The IMD 14 is capable of generating electrical stimulation pulses (e.g., pacing pulses) delivered to the heart 8 via one or more electrodes on the outer housing of the IMD 14. For example, the IMD 14 can be configured to deliver ventricular pacing pulses and sense cardiac electrical signals using housing-based electrodes to generate an intracardiac electrogram (EGM) signal. The cardiac electrical signals can be sensed using housing-based electrodes also used to deliver pacing pulses to the RV. As described below, the IMD 14 may additionally include physiological sensors in addition to the electrodes, which are powered by the IMD power supply to generate physiological signals other than the EGM signal. These physiological signals can be analyzed by a processing circuitry system enclosed by the housing of the IMD 14 for use in controlling cardiac pacing therapy. In one example, the physiological signal is a motion signal containing cardiac motion for detecting cardiac mechanical events, as described below.

[0025] IMD 14 can be configured to control the delivery of cardiac pacing pulses to the heart 8 in a manner that facilitates synchronization between atrial and ventricular activation, for example, by maintaining a target atrioventricular (AV) interval between atrial events and ventricular pacing pulses. That is, IMD 14 controls pacing pulse delivery to maintain the desired AV interval between atrial contractions corresponding to atrial systole and ventricular pacing pulses delivered to induce ventricular depolarization and ventricular systole.

[0026] In some instances, atrial contraction events that generate active ventricular filling can be detected using an IMD 14 implanted within the ventricular chamber. Atrial contraction events can be detected from motion sensors, such as an accelerometer enclosed by the housing of the IMD 14. The motion signal generated by the accelerometer implanted within the ventricular chamber (which may be referred to as the “intraventricular motion signal”) contains motion signals caused by ventricular and atrial events. For example, the acceleration of blood flowing into the RV through the tricuspid valve 16 between the RA and RV caused by atrial contraction and referred to as an “atrial jump” can be detected by the IMD 14 from the signal generated by the accelerometer contained within the IMD 14. The IMD 14 can detect other motion signals, such as motion caused by ventricular contraction and / or passive ventricular filling, as well as motion due to the patient’s physical activity. The accelerometer (or other types of motion sensors) can be configured to generate patient activity signals related to the patient’s level of physical activity.

[0027] In some instances, the IMD 14 can be configured to operate in at least two different therapy delivery modes. One therapy delivery mode can be an atrial-synchronized ventricular pacing mode, in which atrial contraction events are sensed from an acceleration signal generated by an accelerometer contained in the IMD 14, and ventricular pacing pulses are generated in response to the sensed atrial contraction events. Another therapy delivery mode can be a non-atrial-tracking ventricular pacing mode, which does not require sensing atrial contraction events from the acceleration signal to control the timing of the ventricular pacing pulses on a per-beat basis. The ventricular pacing pulses can be delivered according to a programmed lower pacing rate, which can be adjusted to a temporary pacing rate set based on the patient's activity level determined from the accelerometer signal. In the non-atrial-tracking ventricular pacing mode, the IMD 14 can be configured to provide rate-responsive pacing by adjusting the pacing rate delivered to the heart 8. For example, as the patient's activity level increases, the pacing rate increases to provide appropriate metabolic support.

[0028] The current consumption on the IMD power supply may differ for the two different therapy delivery modes, as one mode may require increased current consumption compared to the other. In examples of atrial tracking and non-atrial ventricular pacing modes, the atrial tracking therapy delivery mode requires greater current for dual-chamber sensing compared to the non-atrial tracking ventricular pacing mode, which does not require dual-chamber sensing. The dual-chamber sensing required during atrial tracking pacing mode requires current consumption for operating the accelerometer on a continuous or per-beat basis to detect atrial contraction events and for operating the processor used to analyze the acceleration signal to detect atrial contraction events. In other examples, the IMD 14 may have a single therapy delivery mode; however, the rate of generating pacing pulses may vary over time and / or the current consumption required to operate sensors for patient monitoring purposes may vary over time. The lifetime estimation techniques disclosed herein take into account dynamic variations in power supply current consumption, which may depend on the sensing operation mode, the therapy delivery operation mode, and / or other factors.

[0029] IMD 14 may be capable of bidirectional wireless communication with external device 20 for programming IMD operating parameters, such as sensing and pacing control parameters. Aspects of external device 20 may generally correspond to the external programming / monitoring unit disclosed in U.S. Patent No. 5,507,782 (Kieval et al.), which is incorporated herein by reference in its entirety. External device 20 is generally referred to as a “programmer” because it is typically used by physicians, technicians, nurses, clinicians, or other qualified users to program the operating parameters in IMD 14. External device 20 may be located in a clinic, hospital, or other medical facility. External device 20 may alternatively be embodied as a home monitor or handheld device that can be used in a medical facility, a patient’s home, or another location.

[0030] External device 20 may include processor 52, memory 53, display 54, user interface 56, and telemetry unit 58. Processor 52 controls the operation of the external device and processes data and signals received from IMD 14. Display unit 54, which may include a graphical user interface, displays data and other information to the user for viewing IMD operation and programmed parameters, as well as cardiac electrical signals and acceleration or other sensor signals retrieved from IMD 14. Display unit 54 can generate displays of data and information related to IMD functionality for the user to view IMD operation and programmed parameters, as well as cardiac electrical signals, cardiac motion signals, or other physiological data that can be acquired by IMD 14 and transmitted to external device 20 during an inquiry session.

[0031] User interface 56 may include a mouse, touchscreen, keypad, etc., to enable users to interact with external device 20 to initiate telemetry sessions with IMD 14, retrieve data from IMD 14, and / or transmit data to IMD 14, including programmable parameters for controlling cardiac event sensing and therapy implementation. Telemetry unit 58 includes a transceiver and antenna configured to communicate bidirectionally with telemetry circuitry contained in IMD 14, and is configured to operate in conjunction with processor 52 to send and receive data related to pacemaker functionality via communication link 24.

[0032] In some instances, the external device processor 52 may perform the operations disclosed herein to determine current consumption and / or estimate IMD power lifetime using data retrieved from IMD 14 via communication link 24. The processor 52 may cause the display unit 54 to generate output, which is stored in memory 53 and used to display data related to IMD power lifetime, such as measured power supply voltage, estimated lifetime, historical sensor operation and / or therapy delivery-related data used to estimate lifetime, and / or one or more notifications related to replacement or recharge time recommendations. The display unit 54 may be a graphical user interface that allows a user to interact with the display, for example, to select various displays or information for viewing. In some instances, a user may input one or more programmable parameter settings for controlling sensor operation and therapy delivery to estimate comparative lifetime. For example, the processing circuitry included in IMD 14 and / or processor 52 may determine the estimated lifetime based on currently programmed sensing and therapy delivery control parameters and actual historical data.

[0033] In some instances, processor 52 may be configured to determine multiple comparative estimates of IMD power lifetime stored in memory 53 and cause display unit 54 to generate a display of the results. For example, a user may input one or more alternative programmable settings for sensing and / or therapy delivery control parameters via user interface 56. Processor 52 may determine one or more alternative estimated lifetimes based on the alternative settings for comparison with lifetimes estimated based on currently actually programmed control parameters and actual historical IMD operating data. Processor 52 may cause display unit 54 to generate a comparative display of actual lifetime estimates and alternative lifetime estimates based on one or more programmable control parameters reprogrammed to the alternative settings input by the user. Based on this comparative display, the user may choose to change one or more programmable sensing or therapy delivery control parameters according to patient needs, understanding how the IMD power lifetime is expected to be affected. Any control parameter programming changes may be transmitted back to IMD 14 via communication link 24. In some cases, programming changes may increase the estimated IMD power lifetime, while in others, programming changes may decrease the estimated lifetime as an acceptable trade-off for potential therapeutic benefits to improve patient monitoring or delivered therapy.

[0034] Can be used as A communication link 24 is established between the IMD 14 and the external device 20 via a radio frequency (RF) link such as Wi-Fi or a Medical Implantable Communication Service (MICS) or other RF or communication frequency bandwidth or communication protocol. Data stored or retrieved by the IMD 14, including physiological signals or associated data derived therefrom, device diagnostic results, a history of detected rhythmic episodes and delivered therapies, and estimated lifespan and / or data that can be used by the external device 20 to calculate the estimated lifespan, can be retrieved by the external device 20 from the IMD 14 upon querying. In some instances, the external device 20 may include a programming head placed close to the IMD 14 to establish and maintain the communication link 24; in other instances, the external device 20 and the IMD 14 may be configured to communicate using a distance telemetry algorithm and circuitry system that does not require the programming head and does not require user intervention to maintain the communication link.

[0035] In some instances, a user can interact with external device 20 to transmit commands via communication link 24 to perform IMD power lifetime estimation and return the estimated lifetime and / or data used to calculate the estimated lifetime. In other instances, during any established communication session, when the estimated lifetime is available (e.g., stored in the IMD memory), IMD 14 can transmit a notification to external device 20 relating to the estimated lifetime of the IMD power supply. This notification may include an estimated remaining number of days (or other time units) up to a specified voltage level or a recommended replacement time or end-of-service notification, as described below.

[0036] Consideration has been made that external device 20 can be connected to a communication network, either wired or wirelessly, via telemetry circuitry including a transceiver and antenna, or via hardwired communication lines for transmitting data to a centralized database or computer, to allow for remote patient management. The remote patient management system, which includes a centralized patient database, can be configured to utilize currently disclosed technologies to enable clinicians to view programmed parameters in IMD 14 and data retrieved from IMD 14, including data and notifications related to the estimated lifespan of the IMD power supply.

[0037] Figure 2 It is based on an instance. Figure 1 The diagram shows a conceptual representation of IMD 14. IMD 14 includes a housing 150 containing a closed power supply and internal device circuitry. IMD 14 includes electrodes 162 and 164 spaced along the housing 150 for sensing cardiac electrical signals and delivering pacing pulses. Electrode 164 is shown as a tip electrode extending from the distal end 102 of IMD 14, and electrode 162 is shown as a loop electrode along a middle portion of the housing 150 (e.g., adjacent to the proximal end 104). The distal end 102 is referred to as "distal" because it is expected to be the proximal end when IMD 14 is advanced through a delivery tool (such as a catheter) and placed against a target pacing site.

[0038] Electrodes 162 and 164 form an anode and cathode pair for bipolar cardiac pacing and sensing. In alternative embodiments, IMD 14 may include two or more annular electrodes, two tip electrodes, and / or other types of electrodes exposed along housing 150 for delivering electrical stimulation to the patient's heart and sensing cardiac electrical signals. Electrodes 162 and 164 may be, but are not limited to, titanium, platinum, iridium, or alloys thereof, and may contain low-polarity coatings such as titanium nitride, iridium oxide, ruthenium oxide, platinum black, etc. Electrodes 162 and 164 may be positioned along IMD 14 at locations other than those shown. While IMD 14 is shown as a leadless pacemaker with housing-based electrodes, in other instances, IMD 14 may be configured to couple to one or more medical leads carrying one or more electrodes and / or other sensors for sensing cardiac or other physiological signals.

[0039] The housing 150 is formed of a biocompatible material, such as stainless steel or titanium alloy. In some instances, the housing 150 may include an insulating coating. Examples of insulating coatings include parylene, urethane, PEEK, or polyimide. The entire housing 150 may be insulating, except for electrodes 162 and 164. Electrode 164 may act as a cathode electrode and be coupled via an electrical feedthrough across the housing 150 to an internal circuitry system enclosed by the housing 150, such as a pacemaker pulse generator and cardiac electrical signal sensing circuitry. Electrode 162 may be formed as a definition of the housing 150, such as... Figure 2 The conductive portion of the annular electrode, generally shown, is electrically isolated from the rest of the housing 150. In other embodiments, instead of providing a local annular electrode such as the anode electrode 162, the entire periphery of the housing 150 can serve as an electrode electrically isolated from the tip electrode 164. During pacing and sensing with the cathode tip electrode 164, the electrode 162, formed along the conductive portion of the housing 150, acts as a return anode.

[0040] The housing 150 may include a control electronics subassembly 152, which houses electronics for sensing cardiac signals, generating pacing pulses, controlling therapy delivery, and other functions of the IMD 14, as described below. Figure 3 As described. In some instances, the motion sensor may be implemented as a multi-axis accelerometer enclosed within a housing 150. The accelerometer provides signals to a processor contained in a control electronics subassembly 152 for signal processing and analysis to detect atrial contraction events, for example, for controlling the timing of ventricular pacing pulses synchronized with atrial events, and / or to detect patient physical activity, for example, for controlling rate-responsive ventricular pacing rates.

[0041] An accelerometer can be a three-dimensional accelerometer. In some instances, an accelerometer may have a "longitudinal" axis parallel to or aligned with the longitudinal axis 108 of the IMD 14 and two orthogonal axes extending in a radial direction relative to the longitudinal axis 108. Each axis of a one-dimensional or multi-dimensional accelerometer may be defined by a piezoelectric element, microelectromechanical system (MEMS) device, or other sensor element capable of generating an electrical signal in response to a change in acceleration applied to a sensor element (e.g., by converting acceleration into a force or displacement that has been converted into an electrical signal). In a multi-dimensional accelerometer, the sensor elements may be arranged orthogonally or non-orthogonally. Each sensor element or "axis" may generate an acceleration vector signal corresponding to a vector aligned with the direction of the axis of the sensor element.

[0042] In some cases, one, two, or all three acceleration vector signals generated by the three-dimensional accelerometer can be selected for detecting cardiac mechanical events, such as atrial contraction events controlled by atrial-synchronized ventricular pacing delivered by the IMD 14. The number of axes of the multidimensional accelerometer selected for monitoring motion will affect the current consumption of the IMD power supply. Therefore, the techniques disclosed herein for estimating lifetimes to a specified power supply voltage level can take into account the number of accelerometer axes selected for monitoring cardiac motion and / or patient physical activity, as well as the cumulative time, which can be determined as the time since the IMD 14 has been implanted, during which each axis of the accelerometer has been energized to generate a vector signal.

[0043] The housing 150 further includes a battery subassembly 160, which is an IMD power source that supplies power to the control electronics subassembly 152. The battery subassembly 160 may incorporate features of batteries disclosed in commonly assigned U.S. Patent Nos. 8,433,409 (Johnson et al.) and 8,541,131 (Lund et al.), both of which are incorporated herein by reference in their entirety. The control circuitry included in the control electronics subassembly 152 is configured to measure the voltage of the battery (or multiple batteries) included in the battery subassembly 160. As described below, when a predetermined voltage corresponding to the known remaining capacity of the power source (e.g., one or more batteries included in the battery subassembly 160) is reached, the control circuitry can determine an estimated lifetime until a second specified voltage, such as a voltage designated as the end-of-service (EOS) voltage, is reached below which the battery capacity is insufficient to power the circuitry of the control electronics subassembly 152 to perform normal IMD operation.

[0044] The IMD 14 may include a set of fixation forks 166 to secure the IMD 14 to patient tissue, for example, through active engagement with the ventricular endocardium and / or interaction with ventricular trabeculae. The fixation forks 166 are configured to anchor the IMD 14 to position the electrode 164 operatively close to the target tissue for delivery of therapeutic electrical stimulation pulses. Various types of active and / or passive fixation members can be employed to anchor or stabilize the IMD 14 in the implantation site. The IMD 14 may optionally include a delivery tool interface 158. The delivery tool interface 158 may be positioned at the proximal end 104 of the IMD 14 and is configured to connect to a delivery device, such as a catheter, for positioning the IMD 14 at the implantation site (e.g., intracardiac) during the implantation procedure.

[0045] The example of an IMD14 configured as a leadless intracardiac pacemaker and capable of determining a lifetime estimate according to the techniques disclosed herein is illustrative in nature. It should be understood that the disclosed techniques can be implemented in a variety of implantable and non-implantable medical devices having a depletable power source (e.g., one or more rechargeable or non-rechargeable batteries). The disclosed techniques can be used to estimate the time between two predetermined voltage levels of a depletable power source for any medical device having physiological signal sensors and / or requiring therapies with current from the depletable power source. In some instances, the estimated time or lifetime is from a predetermined voltage level associated with a known power capacity up to a second voltage level associated with a second, lower known power capacity. The second, lower voltage and power capacity may be a service termination voltage when the remaining capacity is insufficient to power the medical device's functionality. In this case, the lifetime is an estimate of the remaining functional lifetime of the medical device's power source. In other instances, the estimated time is from a predetermined voltage up to reaching another predetermined voltage level (and a known battery capacity), which may correspond to a recommended voltage level at which power source replacement or recharging may be recommended or required.

[0046] Various medical devices capable of implementing the disclosed technologies can include pacemakers, implantable cardioverter defibrillators, neurostimulators, muscle stimulators, drug pumps, heart monitors, blood pressure monitors, etc. Such devices can be leadless devices with housing-based electrodes, such as… Figure 2 Generally as shown, or configured to be coupled to one or more medical electrical leads carrying electrodes and / or other sensors. Furthermore, while the illustrative examples presented herein refer to single-chamber pacemakers with dual-chamber sensing capabilities, it should be understood that the techniques disclosed herein can be implemented in any single-chamber, dual-chamber, or multi-chamber pacemaker or ICD.

[0047] Figure 3 yes Figure 1 The diagram shows an example configuration of the IMD 14. The IMD 14 may include a therapy delivery circuit 202, a cardiac electrical signal sensing circuit 204, a control circuit 206, a memory 210, a telemetry circuit 208, a physiological sensor 212, and a power supply 214. Figure 3 The various circuits represented herein can be combined on one or more integrated circuit boards, which include specific integrated circuits (ASICs), electronic circuits, processors (shared, dedicated, or grouped) and memory, combinational logic circuits, state machines, or other suitable components that execute one or more software or firmware programs to provide the described functions.

[0048] Power supply 214 provides power to control circuitry 206 and each other circuit and component of IMD 14 as needed to perform functions belonging to IMD 14. Power supply 214 may include one or more energy storage devices, such as one or more rechargeable or non-rechargeable batteries. Power supply 214 may correspond to a battery sub-assembly, such as battery sub-assembly 160 coupled to control electronics sub-assembly 152, where other circuit systems and components may reside. However, the architecture of power supply 214 and other medical circuit systems may vary between medical devices and depend on the specific medical device size, power requirements, shape, etc. For clarity, not all connections between power supply 214 and other IMD circuits and components are shown. Figure 3 In, but should be from Figure 3 The overall block diagram can be understood as follows. For example, power supply 214 can provide power to the following as needed: the charging and switching circuitry system included in the therapy delivery circuitry 202; amplifiers, analog-to-digital converters (ADCs) 226 and other components of cardiac electrical signal sensing circuitry 204; telemetry circuitry 208; memory 210; and sensor 212 under the control of control circuitry 206.

[0049] In the examples described herein, sensor 212 includes an accelerometer. Sensor 212 generates electrical signals relating to motion or vibration of sensor 212 (and IMD 14), for example, when subjected to flowing blood and cardiac motion within the heart or other implantation sites. However, sensor 212 is not limited to an accelerometer, and other physiological sensors may be used in medical devices to sense physiological signals from a patient to detect events and control therapy delivery or to monitor physiological conditions. However, in the examples presented herein, sensor 212 is provided as an accelerometer for generating acceleration signals due to cardiac events (e.g., contraction and relaxation of heart chambers) and may include acceleration signals due to patient physical activity or other bodily movements.

[0050] Sensor 212 may include multi-axis accelerometers, such as two-dimensional or three-dimensional accelerometers, each accelerometer axis of which can be individually selected to provide a signal (specified as...). Figure 3The sensor 212 may contain X, Y, or Z axis signals, which can be analyzed individually or in combination with one or more other accelerometer axis signals, for detecting cardiac mechanical events and / or for monitoring patient physical activity. The sensor 212 may include one or more filters, amplifiers, rectifiers, analog-to-digital converters (ADCs), and / or other components for generating acceleration signals from each accelerometer axis, which are then passed to control circuitry 206. For example, each axis of a multi-axis accelerometer may generate an acceleration vector signal corresponding to acceleration along the respective axis. Each individual axis signal may be filtered by a high-pass filter (e.g., a 10Hz high-pass filter). The filtered signals may be digitized by the ADC and rectified for use by control circuitry 206 to detect cardiac events. In some instances, if detection of atrial signals with lower frequency content is required, the high-pass filter may be reduced (e.g., reduced to 5Hz). In other instances, each accelerometer axis signal of sensor 212 may be filtered by a low-pass filter (e.g., a 30Hz low-pass filter) with or without a high-pass filter.

[0051] Each accelerometer axis, sometimes referred to as a "channel," generates an acceleration vector signal, which is passed to a signal processing circuitry system, for example, to generate a filtered, digitized acceleration vector signal. Each accelerometer axis can be individually selected by control circuitry 206. For example, a power control signal can be passed from control circuitry 206 to sensor 212 to enable power supply 214 to selectively power each accelerometer axis to generate an acceleration vector signal. One, two, or all three accelerometer axes can be selected to generate acceleration vector signals (e.g., X, Y, or Z signals), which are used individually or in combination by control circuitry 206 to detect cardiac events and to control the rate or frequency of therapy delivered by therapy delivery circuitry 202.

[0052] Furthermore, control circuitry 206 can select one or more accelerometer axis signals for sensing other types of events or motion. For example, one or more accelerometer axis signals can be selected individually or in combination as patient body activity signals used by control circuitry 206 to determine patient activity metrics. Control circuitry 206 can use patient activity metrics to control the rate of therapy delivered by therapy delivery circuitry 202, for example, to provide rate-responsive cardiac pacing.

[0053] An example of an accelerometer used in an implantable medical device that can be implemented in conjunction with the techniques disclosed herein is generally disclosed in U.S. Patent No. 5,885,471 (Ruben et al.), which is incorporated herein by reference in its entirety. Implantable medical device arrangements including piezoelectric accelerometers for detecting patient motion are disclosed, for example, in U.S. Patent Nos. 4,485,813 (Anderson et al.) and 5,052,388 (Sivula et al.), both of which are incorporated herein by reference in their entirety. Examples of a three-dimensional accelerometer that can be implemented in an IMD 14 and used to detect cardiac mechanical events using the currently disclosed techniques are generally disclosed in U.S. Patent Nos. 5,593,431 (Sheldon) and 6,044,297 (Sheldon), both of which are incorporated herein by reference in their entirety. Other accelerometer designs can be used to generate electrical signals relating to accelerations applied to the IMD 14 due to cardiac motion and patient physical activity.

[0054] Cardiac electrical signal sensing circuit 204 is configured to receive cardiac electrical signals via electrodes 162 and 164 through pre-filter and amplifier circuit 220. Pre-filter and amplifier circuit 220 may include a high-pass filter to remove DC offset, such as a 2.5 to 5 Hz high-pass filter, or a broadband filter with a passband of 2.5 Hz to 100 Hz to remove DC offset and high-frequency noise. Pre-filter and amplifier circuit 220 may further include an amplifier to amplify the “raw” cardiac electrical signal passed to analog-to-digital converter (ADC) 226. ADC 226 can pass a multi-bit digital EGM signal to control circuit 206 for identification of ventricular electrical events (e.g., R waves or T waves associated with ventricular myocardial depolarization and repolarization, respectively) and / or atrial electrical events (e.g., P waves associated with atrial myocardial depolarization). Identification of cardiac electrical events can be used in algorithms for establishing atrial contraction event sensing control parameters applied to acceleration signals from sensor 212.

[0055] The digital signal from ADC 226 can be passed to rectifier and amplifier circuitry 222, which may include a rectifier, bandpass filter, and amplifier for passing the cardiac signal to cardiac event detector 224. Cardiac event detector 224 may include a sensing amplifier or other detection circuitry that compares the incoming rectified cardiac electrical signal to a cardiac event sensing threshold, such as an R-wave sensing threshold that may be automatically adjusted. When the incoming signal exceeds the R-wave sensing threshold, cardiac event detector 224 generates an R-wave sensing event signal (R-sensing) that is passed to control circuitry 206. In other instances, cardiac event detector 224 may receive the digital output of ADC 226 for detecting R-waves using comparators, morphological signal analysis of digital EGM signals, or other R-wave detection techniques. Control circuitry 206 may provide sensing control signals to cardiac electrical signal sensing circuitry 204, such as the R-wave sensing threshold, sensitivity, and various blanking and refractory periods applied to the cardiac electrical signal to control R-wave sensing. The R-wave sensing event signal transmitted from the cardiac event detector 224 to the control circuit 206 can be used to plan ventricular pacing pulses and to identify the timing of ventricular electrical events in the executed algorithm for detecting atrial contraction events from signals received from the sensor 212.

[0056] Control circuitry 206 is shown to include atrial event detector circuitry 240, pacing timing circuitry 242, and processor 244. Control circuitry 206 can receive R-wave sensing event signals and / or digital cardiac electrical signals from cardiac electrical signal sensing circuitry 204 for detecting and confirming cardiac events and controlling ventricular pacing. For example, when IMD 14 operates in a non-atrial tracking ventricular pacing mode (e.g., VDI or VVI pacing mode), the R-wave sensing event signal can be passed to pacing timing circuitry 242 to suppress or plan ventricular pacing pulses. The R-wave sensing event signal can also be passed to atrial event detector circuitry 240 to set the time window used by control circuitry 206 when detecting atrial contraction events in acceleration signals received from sensor 212.

[0057] Atrial event detector circuit 240 is configured to detect atrial contraction events from signals received from sensor 212. For example, an atrial event detection window may be set by the atrial event detector circuit during which an atrial event detection threshold is applied to an acceleration vector signal or a combination of acceleration vector signals received from a selected accelerometer axis for atrial event sensing. When the threshold is exceeded, an atrial event, also referred to herein as an "atrial contraction event," corresponds to atrial contraction or atrial contraction period. Example techniques for detecting atrial events from accelerometer signals are generally disclosed in U.S. Patent No. 10,286,214 (Demmer et al.), which is incorporated herein by reference in its entirety.

[0058] Atrial event detector circuit 240 transmits an atrial event detection signal to processor 244 and / or pacing timing circuit 242 in response to the detection of an atrial event. Pacing timing circuit 242 (or processor 244) may additionally receive R-wave sensing event signals from cardiac event detector 224 for controlling the timing of pacing pulses delivered by therapy delivery circuit 202. Processor 244 may include one or more clocks for generating a clock signal used by pacing timing circuit 242 to time out an AV pacing interval that begins upon receiving an atrial event detection signal from atrial event detector circuit 240. Pacing timing circuit 242 may include one or more pacing escape interval timers or counters for timeing out various pacing escape intervals (which may be programmable intervals stored in memory 210 and retrieved by processor 244 for setting pacing escape intervals, such as AV pacing intervals and ventricular lower-rate pacing intervals).

[0059] The pacing timing circuit 242 can activate a lower pacing rate interval timer to control a minimum ventricular pacing rate. For example, if no atrial contraction event is detected in the acceleration signal received from sensor 212 (which triggers a ventricular pacing pulse at a programmed AV pacing interval), the ventricular pacing pulse can be delivered by the therapy delivery circuit 202 when the lower pacing rate interval expires (initiated at the time of a previously sensed or paced ventricular event) to prevent ventricular cardiac arrest and maintain a minimum ventricular rate. Sometimes, the control circuit 206 can control the therapy delivery circuit 202 in a non-atrial tracking ventricular pacing mode (sometimes referred to as "asynchronous ventricular pacing"). The non-atrial tracking ventricular pacing mode can be represented as a VVI pacing mode, in which the ventricular pacing pulse is delivered in the absence of a sensed R wave and is suppressed in response to an R wave sensing event signal from the sensing circuit 204. In some instances, dual-chamber sensing can be performed during a non-atrial tracking ventricular pacing mode (e.g., a VDI pacing mode). VDI pacing modes can include atrial event sensing from one, two, or all three accelerometer axes to sense atrial contraction events for heart rhythm detection.

[0060] In some cases, processor 244 receives acceleration signals from one or more accelerometer axes to determine patient activity metrics and sensor-indicated pacing rates (SIRs) for controlling the ventricular pacing rate based on patient activity levels during non-atrial-tracking ventricular pacing modes (e.g., VVIR pacing modes). One or more accelerometer axis signals can be used to determine patient activity metrics. Depending on the specific pacing therapy mode in effect, each accelerometer axis may be energized and de-energized at different times. For example, during VDD pacing modes, one, two, or all three axes of the three-dimensional accelerometer may be used to generate motion signals analyzed by processor 244 and / or atrial event detector circuitry 240 for detecting atrial contraction events. At other times, one of the three axes of the accelerometer included in sensor 212 may be used to determine the SIR for controlling ventricular pacing, e.g., in VVIR pacing modes. During non-atrial-tracking VVIR pacing modes, one or more accelerometer axis signals selected for generating acceleration vector signals for atrial contraction event sensing may remain de-energized.

[0061] Therefore, the current consumption required to power the operation of sensor 212 to generate acceleration signals can vary dynamically over time. Furthermore, the power required by control circuitry 206 to process and detect atrial contraction events can vary dynamically over time when the pacing therapy delivery mode switches between atrial-tracking ventricular pacing and non-atrial-tracking ventricular pacing modes. Control circuitry 206 can be configured to track the time each axis of the accelerometer included in sensor 212 is "on" or powered by power supply 214 to generate motion signals from the corresponding axis. The cumulative "on" time for each accelerometer axis since the implantation of IMD 14 can be stored in memory 210 for determining sensor operating current consumption and estimating the lifetime of power supply 214, as described below.

[0062] Memory 210 may include buffers for storing the history of various functions and / or pacing modes in the operational history of IMD 14, for example, starting from the time of implantation. Memory 210 may store a timestamp marking the implantation time of IMD 14. From that time onward, memory 210 may store the operational history of IMD 14. For example, memory 210 may include a sensor channel “on” time buffer 250 for storing the cumulative total time for each accelerometer axis to be energized to generate an acceleration vector signal. Buffer 250 may include, for example, three memory locations for storing the total on time of each of the three accelerometer axes of sensor 212. Control circuitry 206 may retrieve the total “on” time of each accelerometer axis to determine an estimated power lifetime. In other instances where sensor 212 includes more than one type of sensor, each type of sensor may correspond to a sensor “channel,” and / or one or more sensors may each have multiple “channels” corresponding to different axes, orientations, vectors, or other sensing components of a given sensor. Therefore, in each instance, the sensor channel “on” time buffer 250 can store the total on time of each type of sensor and / or the total on time of each sensor channel associated with the physiological sensor contained in sensor 212.

[0063] Memory 210 may further include a therapy delivery mode time buffer 252 for accumulating the time the control circuitry 206 operates in a specified therapy delivery mode. Specifically, the control circuitry 206 may track the percentage of time a therapy delivery mode is active that requires processing signals from sensor 212, which may impose a relatively higher processing burden and therefore greater current consumption than other therapy delivery modes. The processing burden required to analyze signals from sensor 212 to detect cardiac events may require additional current consumption from power supply 214, which is not required during other therapy delivery modes. For example, the control circuitry 206 may at least track the time the IMD 14 operates in a dual-chamber sensing mode (e.g., VDD and / or VDI pacing mode). When cardiac electrical signal sensing circuitry 204 performs ventricular event sensing (e.g., R-wave sensing) without needing to analyze accelerometer signals for detecting cardiac events, the processing burden for detecting atrial contraction events from accelerometer signals increases the current consumption from power supply 214 compared to, for example, a single-chamber sensing mode (e.g., VVI or VVIR pacing mode). When operating in a rate-responsive pacing mode (e.g., VVIR pacing mode), the accelerometer signal from sensor 212 can be used to determine a patient's physical activity metric for adjusting the ventricular pacing rate. However, the processing burden of determining the physical activity metric (which may occur every two seconds or more frequently) is relatively lower than the processing burden required to detect atrial contraction events from the accelerometer signal, which occurs as frequently as each cardiac cycle. Therefore, control circuitry 206 can be configured to track and store accumulated time in one or more operating modes (e.g., therapy delivery mode) for estimating power lifetime, taking into account the additional processing burden required to detect atrial contraction events from one or more acceleration vector signals received from sensor 212, to obtain a more reliable and accurate lifetime estimate.

[0064] Therefore, control circuit 206 can determine the cumulative time of operation in dual-chamber sensing mode since IMD implantation and store the cumulative time in dual-chamber sensing mode in therapy mode in therapy mode time buffer 252. Specifically, the cumulative time of operation modes requiring atrial contraction sensing using accelerometer signals since implantation (e.g., dual-chamber sensing or atrial tracking ventricular pacing) can be stored in therapy mode time buffer 252. In one example, the cumulative time of operation in VDD pacing mode is accumulated and stored.

[0065] Memory 210 may further store therapy delivery parameters for estimating the lifetime of power supply 214. For example, control circuit 206 may count all pacing pulses delivered by therapy delivery circuit 202 since pacemaker implantation. The total number of delivered pacing pulses may be stored in pacing parameter buffer 254 along with other pacing control parameters such as pacing pulse amplitude and pacing pulse width. The cumulative number of generated pacing pulses, as well as the currently programmed pacing pulse width and pacing pulse amplitude, may be retrieved by control circuit 206 from memory 210 for estimating power supply lifetime.

[0066] In other instances, it should be understood that accumulated sensor operating time can be stored in the memory of the medical device for use with one or more sensors and / or sensor channels associated with single-chamber sensing, dual-chamber sensing, or multi-chamber sensing. For example, in a dual-chamber or multi-chamber pacemaker, memory 210 may additionally or alternatively store a history of the number of pacing pulses and / or other electrical stimulation pulses delivered to one or more cardiac chambers or therapy delivery sites. For example, the number of pacing pulses and / or other electrical stimulation pulses delivered to each of the atrial and ventricular chambers in dual-chamber pacing mode can be tracked to determine the therapy delivery current consumption associated with dual-chamber pacing. In still other instances, the number of pacing pulses and / or other electrical stimulation pulses delivered to each of the atrial, right, and left ventricles can be counted and stored from the time of implantation to determine the therapy current consumption associated with multi-chamber therapies such as cardiac resynchronization therapy.

[0067] The memory 210 can accumulate the total time spent in one or more sensing and / or therapy delivery modes, which may include single-chamber, dual-chamber, and / or multi-chamber sensing and / or therapy delivery modes, each requiring processing one or more sensor signals, and thus each mode is associated with processing load current consumption. Therefore, in other instances, the techniques disclosed herein, illustrated by determining the sensor operating current consumption, processing load current consumption, and therapy delivery current consumption of a single-chamber ventricular pacemaker (capable of dual-chamber sensing to provide atrial tracking ventricular pacing), can be extended to determine the sensor operating current consumption, processing load current consumption, and / or therapy delivery current consumption of a dual-chamber or multi-chamber pacemaker or ICD.

[0068] The therapy delivery circuit 202 may include a charging circuit 230, a switching circuit 232, and an output circuit 234. The charging circuit 230 may include a holding capacitor that can be charged to the pacing pulse amplitude at a multiple of the battery voltage signal of the power supply 214 under the control of a voltage regulator. The pacing pulse amplitude can be set based on a control signal from the control circuit 206, which is based on a programmed pacing pulse amplitude stored in the memory 210. The switching circuit 232 can control when the holding capacitor of the charging circuit 230 is coupled to the output circuit 234 for pacing pulse delivery. For example, the switching circuit 232 may include a switch that is activated by a timing signal received from the pacing timing circuit 242 when the AV pacing interval (or VV lower rate pacing interval) expires and remains closed for a programmed pacing pulse width (retrieved from the memory 210) so that the holding capacitor of the charging circuit 230 can discharge. During the programmed pacing pulse duration, the holding capacitor, pre-charged to the pacing pulse voltage amplitude, discharges across electrodes 162 and 164 through the output capacitor of output circuit 234.

[0069] In this manner, the therapy delivery circuit 202 generates pacing pulses delivered via electrodes 162 and 164 coupled to the therapy delivery circuit 202 according to the therapy delivery operation mode (e.g., VDD, VDI, VVI, VVIR, etc.). The control circuit 206 can control the switching between various therapy delivery operation modes (e.g., between VDD pacing mode and VVIR pacing mode) to provide atrial-ventricular pacing as much as possible, but switches to VVIR pacing mode when atrial tracking is not ideal (e.g., due to atrial tachyarrhythmias or undersensing or oversensing of atrial contraction events).

[0070] As described above, power supply 214 powers sensor 212 to power one or more selected accelerometer axes as needed for detecting cardiac events, such as atrial contraction events, and / or for determining patient physical activity and controlling the rate of therapy generated by therapy delivery circuitry 202 according to therapy delivery modes. Power supply 214 further powers control circuitry 206, for example, the processing circuitry system included in atrial event detector circuitry 240 and processor 244, for detecting cardiac events from acceleration vector signals received from sensor 212. The pacing mode can vary between an atrial-synchronized ventricular pacing mode that requires sensing atrial events from accelerometer signals and a pacing mode that does not require sensing atrial events from accelerometer signals. Depending on the characteristics of the acceleration vector signals, one, two, or all three accelerometer axis signals can be selected to detect atrial events. Therefore, the current consumption from power supply 214 required to operate sensor 212 can vary over time depending on the pacing mode and the number of accelerometer channels selected for detecting atrial events or sensing other movements such as patient physical activity. While lifetime estimation may include determining the current consumption for generating cardiac pacing pulses based on the average delivery rate of the pacing pulse over time, as well as the pacing pulse width and amplitude, the lifetime estimation technique disclosed herein takes into account the sensor operating current consumption and processing burden current consumption associated with operating sensor 212 and detecting cardiac events from acceleration vector signals.

[0071] The techniques for estimating lifetime disclosed herein determine the current consumption from power supply 214 required for operation in an operating mode that requires operating sensor 212 and processing signals received from sensor 212 by control circuitry 206. Current consumption may include sensor operating current consumption, based on the cumulative time each accelerometer channel (e.g., each X, Y, and Z axis) has been energized to generate an acceleration vector signal, e.g., a percentage of time since IMD 14 was implanted. Current consumption may additionally or alternatively include processing burden current consumption, based on the current from power supply 214 required to power the processor contained in control circuitry 206 during atrial tracking ventricular pacing mode or dual-chamber sensing mode to process the received acceleration vector signals for detecting cardiac events (e.g., atrial contraction events). Therefore, the current consumption used to estimate lifetime can be determined based on the cumulative time (e.g., the percentage of time since IMD 14 has been operated in a specified mode (e.g., atrial tracking ventricular pacing mode or any dual-chamber sensing mode) that requires operation of sensor 212 and detection of atrial events from selected accelerometer channel signals. In other instances, the percentage of time operated in one or more operating modes (which may be sensing or therapy delivery modes) since pacemaker or ICD implantation can include single-chamber, dual-chamber, and / or multi-chamber or multi-site sensing or therapy delivery modes.

[0072] Memory 210 may contain computer-readable instructions that, when executed by control circuitry 206, cause control circuitry 206 to perform various functions belonging to IMD 14 throughout this disclosure. The computer-readable instructions may be encoded within memory 210. Memory 210 may contain any non-transitory computer-readable storage medium, including any volatile, non-volatile, magnetic, optical, or electrical medium, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or other digital media, with the sole exception of transient propagation signals. Memory 210 may store time-stipulated data and other data used by control circuitry 206 to control the delivery of pacing pulses by therapy delivery circuitry 202 (e.g., by detecting atrial contraction events from accelerometer signals and setting a pacing escape interval timer included in pacing timing circuitry 242).

[0073] Memory 210 may further store instructions executed by control circuitry 206 for estimating the lifetime of power supply 214 between two voltage levels, as described herein. Control circuitry 206 may retrieve data from various buffers 250, 252, and 254 as needed to execute instructions. Control circuitry 206 may execute instructions on a scheduled basis, such as daily, weekly, or monthly, or upon receiving a command from an external device via telemetry circuitry 208. After determining the estimated lifetime, control circuitry 206 may generate outputs for storage in memory 210, such as an estimated time until recommended device replacement or service end, which may be used to generate notifications transmitted by telemetry circuitry 208.

[0074] Telemetry circuit 208 includes a transceiver 209 and an antenna 211 for transmitting and receiving data via a radio frequency (RF) communication link. As described above, telemetry circuit 208 may be able to communicate with external device 20 ( Figure 1 Two-way communication is enabled. Sensor signals and cardiac electrical signals and / or data derived therefrom can be transmitted by telemetry circuit 208 to external device 20. Programmable control parameters and algorithms for performing atrial event detection and ventricular pacing control can be received by telemetry circuit 208 and stored in memory 210 for access by control circuit 206. As described below, control circuit 206 can generate various notifications related to the estimated lifespan of power supply 214 and control telemetry circuit 208 to transmit notifications related to said estimated lifespan, such as the recommended replacement time of IMD 14 or the end of service of power supply 214.

[0075] In some instances, control circuit 206 can control telemetry circuit 208 to transmit data from another medical device (e.g., Figure 1 The external device 20 shown is used to perform a power lifetime estimate. For example, control circuitry 206 can retrieve data from buffers 250, 252, and 254, which store data related to current consumption from power supply 214, and pass the data to telemetry circuitry 208 for transmission to another medical device. A processor included in the other medical device can use the transmitted data to determine a power lifetime estimate. In yet another instance, control circuitry 206 can use data retrieved from memory 210 to determine total current consumption, for example, as described below. Figure 5 As described herein, the total current consumption or a determined current consumption component is transmitted to another medical device via telemetry circuit 208 for lifetime estimation. Therefore, the operation performed to estimate the lifetime between two voltages of power supply 214 (associated with a known capacity variation) can be collaboratively performed by one or more processors across one or more medical devices. As used herein, a “processor” configured to determine the estimated lifetime according to the techniques disclosed herein can refer to multiple processors or processing circuitry distributed across one or more medical devices or a computer system, for example… Figure 1 The IMD processor 244 and external device processor 52 are shown.

[0076] The functions attributed to IMD 14 herein may be embodied in one or more processors, controllers, hardware, firmware, software, or any combination thereof. Describing different features as specific circuitry is intended to highlight different functional aspects and does not necessarily imply that such functions must be implemented by separate hardware, firmware, or software components or by any particular circuit architecture. Rather, the functions associated with one or more circuits described herein may be performed by separate hardware, firmware, or software components, or integrated within general-purpose hardware, firmware, or software components. For example, atrial contraction event detection from sensor signals and ventricular pacing control operations performed by IMD 14 may be implemented in control circuitry 206, which executes instructions stored in memory 210 and depends on inputs from sensing circuitry 204 and sensor 212. Given the disclosure herein, providing software, hardware, and / or firmware to perform the described functions in the context of any modern pacemaker is within the capabilities of those skilled in the art.

[0077] Figure 4 It is a graphical illustration of how the power supply voltage changes over time (300). Figure 4The voltage discharge curve shown illustrates the voltage depletion behavior of an IMD power supply 214 according to one example. Power supply 214 has an initial voltage referred to as a “Start of Service” (BOS) voltage 301, which may be the power supply voltage at the time of battery connection during the manufacture of IMD 14. The voltage may decrease from the BOS voltage 301 and remain relatively stable over an extended period, as indicated by the flat portion of a voltage “plateau” 302. This first plateau portion 302 is followed by a first relatively steep discharge portion 303 and a second relatively short voltage plateau portion 306. After the relatively short duration of the second plateau portion 306, the power supply voltage may drop sharply as the power is depleted. An End of Service (EOS) voltage 312 is reached during the second steep discharge portion 314. When the EOS voltage 312 is reached, the remaining capacity of power supply 214 is insufficient to power the circuitry of IMD 14 to perform basic functions such as therapy delivery and sensing functions.

[0078] Because the medical device may be performing critical or life-saving monitoring or therapy delivery, it may be necessary to determine when power supply 214 reaches a capacity greater than the EOS (Effective Time of Replacement) while still maximizing the lifespan of the medical device. Therefore, control circuitry 206 can measure the power supply voltage on a planned basis and determine when it reaches a reference voltage, such as the Recommended Replacement Time (RRT) voltage 308. Control circuitry 206 can be configured to generate a recommended replacement notification in response to detecting a specified reference voltage. Alternatively, when control circuitry 206 measures the power supply voltage and determines that it has reached a third lower reference voltage 310, control circuitry 206 can generate a notification indicating that IMD power supply 214 has reached a selective replacement time. This third reference voltage may be referred to as the Selective Replacement Indicator (ERI) voltage 310 because it can be selected shortly before a second steep discharge portion 314, which can rapidly lead to the EOS of the medical device. Therefore, one or more reference voltages can be specified before the EOS voltage 312, for example, along the second plateau portion 306, such as the RRT voltage 308 which occurs relatively early along the second plateau and the ERI voltage 310 which occurs relatively late along the second plateau 306, just before the steep discharge portion 314 where the voltage discharge curve finally drops rapidly. When the control circuit 206 measures a power supply voltage equal to or less than the reference voltage, the control circuit 206 can generate a notification to be transmitted to the external medical device 20 to notify the patient or clinician.

[0079] However, it may be necessary to predict the remaining time between the two voltage levels of power supply 214 in order to generate timely notifications related to the expected remaining usable life of the medical device, thereby enabling the planning of medical device or power supply replacement procedures or recharging of the power supply before reaching the EOS voltage 312. The voltage level and duration of the first platform portion 302 can vary between devices, even those of the same model, and due to different programmable control parameters and operating modes of the devices. The voltage level can even fluctuate slightly up and down on the first platform portion 302. Therefore, if the voltage of power supply 214 measured by control circuit 206 falls anywhere along the first platform 302, it is difficult to predict the time position of the measured voltage level relative to the second lower voltage level, because the voltage variation along the first platform portion 302 is relatively small and may fluctuate. The estimated power supply life from the measured voltage along the first platform 302 up to the second lower voltage level may be an unreliable life estimate because it is difficult to estimate where the measured voltage is at the first platform 302 for a relatively long duration.

[0080] The reference supply voltage 304 measured along the steep discharge section 303 between the first plateau 302 and the second plateau 306 can be referred to as the pre-recommended replacement time (pre-RRT) voltage 304. This reference voltage, or pre-RRT voltage 304, can correspond to a reliably known remaining supply capacity. For example, the remaining capacity of supply 214 can be established at the reference pre-RRT voltage 304 by bench testing. In one example, the BOS voltage 301 is 3.2 volts and corresponds to 100% remaining capacity, which can be, for example, about 100 mA-hours. In an illustrative example, the pre-RRT voltage 304 can be 2.65 volts, corresponding to 25% remaining capacity or about 25 mA-hours. However, it should be understood that the BOS voltage 301 and any reference voltage selected from the supply discharge curve for estimating the lifetime between the two reference voltages are not limited to any particular BOS supply voltage and capacity or any particular discharge voltage curve characteristic. As an example, but without any limitations, the BOS voltage of the batteries used in IMDs can range from 1 to 10 volts, and the capacity can be at most 1 to 2 amp-hours or higher. Figure 4 As the examples show, the power supply can discharge without a platform, on a single platform, on two platforms, or on more than two platforms.

[0081] In one example, power source 214 comprises one or more hybrid primary cells containing lithium, fluoride, and silver vanadium oxide. Other battery chemistry used in medical devices implementing the lifetime estimation techniques disclosed herein may include lithium-based batteries, such as, but not limited to, lithium iodide, lithium manganese dioxide, lithium silver vanadium oxide, lithium polyfluoride, lithium silver chromate, lithium copper sulfide, lithium thionyl chloride, or mixtures thereof, and non-lithium-based batteries, such as battery chemistry containing zinc or nickel cadmium. The lifetime estimation techniques disclosed herein can be implemented in combination with any desired battery chemistry and BOS capacity, provided that at least one specified voltage along the discharge profile can be reliably measured and associated with a known remaining capacity. The second lower voltage may be an EOS voltage 312 with zero remaining capacity. In other examples, the second lower voltage may be greater than the EOS voltage and associated with a known remaining capacity, such that the capacity difference between the first reference voltage and the second lower reference voltage is known.

[0082] exist Figure 4 In this example, the remaining battery capacity can be reliably determined for a reference voltage that appears along the relatively steep discharge section 303. Using this reference voltage associated with the known remaining battery capacity, the estimated lifetime of power supply 214 up to a second lower voltage (e.g., EOS voltage 312) associated with the second remaining capacity can be determined. In some instances, the estimated lifetime can be determined as the number of days (or other units of time) from the pre-RRT voltage to the EOS voltage, but it should be understood that the techniques disclosed herein can be used to estimate the lifetime between any two selected voltages, each associated with a determined remaining power supply capacity.

[0083] As described below, control circuit 206 can measure the power supply voltage at planned time intervals or at planned times during the day. When the pre-RRT voltage 304 is reached, this indicates a transition of the power supply voltage from the first plateau 302 to the second plateau 306. When a reference pre-RRT voltage 304 associated with known remaining power capacity is reached, control circuit 206 is triggered to perform lifetime estimation. Lifetime can be estimated based on historical data stored in memory 210 and the known remaining capacity at pre-RRT voltage 304 and the known remaining capacity at a second lower voltage (which can be 0 at EOS voltage 312).

[0084] Control circuitry 206 may include a timer or counter to begin counting the number of days (or other lifetime units) that have elapsed since the measurement of the pre-RRT voltage 304. The lifetime estimate may be repeated at planned time intervals or at planned times within a day until the EOS voltage 312 is reached (or until IMD 14 or power supply 214 is replaced or recharged). The estimated lifetime may be determined daily, for example, based on the pre-RRT voltage capacity and updated values ​​stored in the sensor channel “on” time buffer 250, the therapy delivery mode time buffer 252, and the pacing parameter buffer 254. However, after the pre-RRT voltage is reached, control circuitry 206 may count the number of days that have elapsed since reaching the pre-RRT voltage and subtract the number of days from the lifetime estimated based on the pre-RRT voltage capacity. When the estimated lifespan reaches a threshold number of days designated as RRT or ERI, the control circuit 206 can generate a notification via the telemetry circuit 208 to inform the patient and / or clinician that it is recommended to replace or recharge the IMD14 or power supply, or that it is necessary to avoid reaching the EOS voltage 312.

[0085] Figure 5 This is a flowchart 350 illustrating a method for determining the estimated time between two voltage levels of a power supply for a medical device, based on one example. The techniques disclosed herein can be applied to power supplies comprising one or more non-rechargeable primary batteries and / or rechargeable batteries. The process of flowchart 350 can be performed periodically, e.g., daily or on the basis of other schedules, to estimate the lifetime of a power supply for a medical device (e.g., power supply 214 of IMD 14). The processes shown in flowchart 350 and other flowcharts presented herein can be performed by a processor contained in the same device as the power supply whose lifetime is being estimated. In other instances, the process for estimating lifetime can be performed wholly or partially by a processor of another medical device or computer after receiving data required to determine lifetime from the medical device (e.g., external device processor 52). For convenience, the process for estimating lifetime as an estimated time from a first voltage to a second voltage of the power supply is described as being performed by control circuitry 206, e.g., by processor 244; however, it should be understood that in some instances, external device processor 52 can perform the operations for determining the estimated time. For example, processor 52 can receive data transmitted from IMD 14 to determine the estimated time. Therefore, in some instances, the function of determining the estimated time can be distributed across two or more processors.

[0086] At box 351, control circuitry 206 measures the voltage of power supply 214. For example, the battery voltage of power supply 214 can be measured daily or according to another predetermined schedule. In some instances, the battery voltage can be measured at a single point in time for each scheduled measurement. In other instances, the scheduled measurement may involve measuring the battery voltage at multiple points in time and averaging the results.

[0087] In some instances, control circuitry 206 can estimate the lifetime of power supply 214 only when the measured supply voltage is equal to or less than a specified reference voltage. Therefore, control circuitry 206 can compare the measured voltage with the reference voltage at block 352. When the measured voltage is greater than the reference voltage, control circuitry 206 can return to block 351 to await the next scheduled voltage measurement. When the measured voltage is greater than the reference voltage, the expected lifespan of the medical device may be relatively long, for example, greater than 6 months or more for an IMD, or greater than 24 hours or more for a rechargeable device, making any notification regarding the remaining lifespan of the medical device potentially unnecessary or non-urgent. In some cases, depending on the discharge characteristics of the power supply, it may be difficult to estimate the lifetime when the measured voltage is greater than the reference voltage. For example, when the measured voltage along... Figure 4 When the discharge curve reaches the first plateau portion 302, the lifetime estimate may be unreliable. Therefore, the reference voltage at block 352 can be as follows: Figure 4 The pre-RRT voltage 304 shown can be the voltage of the first steep discharge portion 303 following the first plateau portion 302. The pre-RRT voltage 304 can be specified based on bench testing performed to characterize the discharge profile of the power supply. In one example, for a power supply with a service start voltage of approximately 3.2 volts, the pre-RRT voltage is 2.65 volts.

[0088] The specified reference voltage can be any voltage that can be reliably measured and associated with a known remaining power supply capacity. For example, the remaining battery capacity when the pre-RRT voltage 304 is reached can be reliably known as approximately 25% of the startup or BOS battery capacity. The lifetime of power supply 214 can be estimated using the known remaining battery capacity at the reference voltage level, such as at the pre-RRT voltage, and the total current consumption required for sensing and therapy delivery operations can be estimated based on historical data acquired by control circuitry 206 and programmed therapy control parameters.

[0089] To estimate the current consumption required to continue operation according to anticipated patient needs, control circuitry 206 can estimate the therapy delivery current consumption at block 354, the sensor operation current consumption at block 356, and the processing load current consumption at block 358 based on the history of medical device operation (e.g., since BOS or IMD 14 implantation). At block 354, the therapy delivery current consumption can be estimated based on the therapy delivery history and currently programmed therapy control parameters. The following is in conjunction with... Figure 6 Describe an example method for estimating the current consumption of therapy delivery.

[0090] At block 356, control circuitry 206 can estimate the sensor operating current consumption. The sensor operating current consumption can be determined based on the history of sensor operation and / or programmed sensor operation control parameters. In the illustrative example presented herein, the sensor operating current consumption is estimated for operating a triaxial accelerometer. However, in other examples, other types of physiological sensors can be included in a medical device performing lifetime estimation according to the techniques disclosed herein. Other types of sensors can include pressure sensors, optical sensors such as tissue or blood oxygen sensors, acoustic sensors, ultrasonic sensors, flow sensors, etc. In some examples, multiple sensors and / or multiple sensor channels for a given sensor can be included in the medical device. For example, multiple sensor channels can be provided, where each channel corresponds to a different vector, axis or direction, different frequency or other operating components, and / or different signal processing or analysis (e.g., different signal filtering, signal amplification, sampling rate, determination of signal characteristics, etc.). Therefore, the sensor operating current consumption estimated at block 356 can be based on... Figure 3 The total time history of each sensor and / or sensor channel contained in sensor 212 being energized to generate a signal, and the control circuit 206 can detect physiological events or determine physiological parameters from the signals.

[0091] Processing burden current consumption can be estimated by control circuitry 206 at block 358. Processing burden current consumption can be associated with one or more operating modes of the medical device that require varying degrees of signal processing and analysis compared to other operations of the medical device. Processing burden may depend on the processing required to control therapy delivery. However, in some instances, this processing may be necessary to monitor physiological signals and generate alarms or notifications of medical conditions. In the examples presented herein, processing burden current consumption depends on the percentage of time the IMD 14 has historically operated in sensing or therapy delivery modes (e.g., a designated cardiac pacing mode requiring processing and analysis of one or more sensor signals). For example, when the IMD 14 operates in atrial-tracking ventricular pacing mode, dual-chamber sensing is required, which includes detecting atrial contraction events from one or a combination of accelerometer axis signals. The processing burden current consumption during atrial-tracking ventricular pacing mode is relatively greater than that during non-atrial-tracking ventricular pacing modes due to the processing required to sense (detect) atrial contraction events from accelerometer axis signals during atrial-tracking ventricular pacing mode. The following is combined with… Figure 6 Describe an example method for determining the current consumption of the processing load.

[0092] At block 360, the total current consumption is determined by adding the estimated therapy delivery current consumption, sensor operation current consumption, and processing load current consumption. The total current consumption may further include an estimated quiescent current consumption to account for the current required from the power supply to power the basic IMD functions, which may vary only slightly over time, compared to variations in therapy delivery, sensor operation, and processing load associated with switchable sensing and / or therapy delivery modes. For example, the quiescent current consumption component of the total current consumption determined at block 360 may account for the current required to operate the cardiac electrical signal sensing circuitry 204 to sense cardiac electrical events on a per-beat basis and other ongoing functions of the control circuitry 206. This quiescent current consumption is expected to remain relatively constant throughout the functional lifetime of the IMD 14 and can therefore be included as a fixed value in the total current consumption determined at block 360, which may be stored in memory 210.

[0093] At box 362, total current consumption can be converted to an estimated time up to a second lower voltage level associated with a second remaining battery capacity. For example, total current consumption can be converted to an estimated lifetime from the pre-RRT voltage along the steep slope of the discharge curve up to the EOS voltage level (associated with 0% remaining capacity). Lifetime can be determined at box 362 as the number of remaining days from a first measured battery voltage level (e.g., a reference pre-RRT voltage level with known remaining capacity) up to the second lower battery voltage level (e.g., the EOS voltage). For example, the lifetime (in days) from the pre-RRT voltage to the EOS voltage can be determined by dividing the capacity difference between the first and second voltages at the pre-RRT voltage (e.g., in ampere-hours) by the total current consumption (in amperes) and then dividing this result by 24 hours / day, converting the total current consumption to lifetime in days. Depending on the medical device, the estimated lifetime can be determined in other time units, such as hours, weeks, months, or years.

[0094] At box 364, control circuitry 206 can determine whether an elapsed time counter is running. When the reference pre-RRT voltage is first reached, the elapsed time counter can be activated at box 366 to begin counting the number of days (or other time units) elapsed since the supply voltage reached the reference pre-RRT voltage. For example, the counting of days can begin from the time the measured supply voltage was at the pre-RRT voltage. The supply voltage measurement result can have a resolution of less than 10 millivolts, for example, about 7 millivolts. Therefore, the determination of when the supply voltage reached the reference pre-RRT voltage can be within an error range of two days or less, or even one day or less.

[0095] Once the elapsed time counter has been running at block 364 (e.g., previously activated in response to a first estimated lifetime determined upon reaching the reference pre-RRT voltage), control circuitry 206 can adjust the estimated lifetime determined at block 362 based on the reference pre-RRT voltage (and stored in memory 210) by subtracting the number of days counted by the elapsed time counter since reaching the pre-RRT voltage. In this way, a new estimated lifetime determined using the known power supply capacity at the reference pre-RRT voltage can be adjusted by the actual number of days that have elapsed after one or more days since reaching the pre-RRT voltage. This adjusted estimated lifetime, determined at block 368, corresponds to the lifetime remaining from the current power supply voltage, which is less than the reference pre-RRT voltage.

[0096] In an illustrative example, when the measured battery voltage is at pre-RRT, the estimated lifetime initially determined by control circuitry 206 at block 362 could be 500 days. The elapsed time counter is 0 and begins counting the days elapsed since the pre-RRT voltage was measured. Based on the pre-RRT voltage capacity and new estimates of therapy delivery current consumption, sensor operating current consumption, and processing load current consumption, the estimated lifetime at a later point in time at block 362 could be 350 days. The pre-RRT voltage capacity is used to determine the estimated lifetime because the power supply capacity at the pre-RRT voltage is known, while the remaining power supply capacity at the currently measured voltage, which is less than the pre-RRT voltage, may be unknown. The elapsed time counter may have reached a value of 50 days since the pre-RRT voltage was reached. Therefore, in this example, the adjusted estimated lifetime at block 368 is 350 days minus the 50 days elapsed since the pre-RRT voltage was reached, resulting in an adjusted lifetime of 300 days until the EOS voltage. The adjusted lifetime may not change the value of the elapsed time counter. By tracking the number of days since the pre-RRT voltage was reached using a time counter, the estimated future lifespan based on the remaining battery capacity at the pre-RRT voltage can be adjusted by the actual number of days elapsed since the pre-RRT voltage was measured.

[0097] If the estimated lifetime (which may be based on an estimated lifetime adjusted by a time counter) reaches a first threshold of remaining days (box 370), a Recommended Replacement Time (RRT) notification can be generated at box 372. In one example, an RRT notification is generated when the estimated lifetime is 180 days. The RRT notification can be transmitted to external device 20 via telemetry circuitry 208 the next time an interrogation command is received from an external device (e.g., external device 20).

[0098] When the adjusted estimated lifetime reaches a second lower threshold number of days (box 374), control circuitry 206 can generate a Selective Replacement Indicator (ERI) notification at box 376. The second lower threshold number of days can be, for example, 30 to 90 days. The ERI notification can instruct clinicians that IMD 14 or power supply 214 should be replaced or recharged to avoid reaching the EOS voltage and interrupting therapy delivery. Control circuitry 206 can continue measuring the power supply voltage at box 382 and determining the lifetime estimate at box 378 until the lifetime estimate reaches zero days remaining. When the estimated lifetime is zero days, end-of-service (EOS) notification can be generated by control circuitry 206 at box 380 and transmitted to an external device by telemetry circuitry 208.

[0099] In some instances, power supply voltage measurements performed on a planned basis (e.g., daily at the same time when the lifespan is determined) can also trigger RRT, ERI, or EOS notifications. For example, if the RRT voltage, ERI voltage, or EOS voltage (as determined in boxes 370, 374, or 378) is reached before the adjusted lifespan estimate reaches a threshold number of days (as determined in boxes 370, 374, or 378 respectively), it can trigger such notifications. Figure 4 If the discharge curve is shown, then control circuit 206 can generate a notification based on the measured battery voltage (at blocks 372, 376, or 380). The generated notification can be stored in memory 210 for transmission via telemetry circuit 208. In this way, the measured power supply voltage can serve as a backup trigger for RRT, ERI, and / or EOS notifications when the power supply voltage reaches the corresponding threshold voltage before the adjusted estimated lifetime reaches the threshold number of days used to generate RRT, ERI, or EOS notifications. Once the EOS days or EOS voltage is reached, the process can be terminated. Figure 5 The process makes it unnecessary to determine the power supply voltage measurement results or lifetime estimate. However, the determination of power supply voltage measurements and lifetime estimates can continue as scheduled (e.g., daily) before an EOS notification is generated.

[0100] Figure 6 This is a flowchart 400 illustrating methods for determining total current consumption and estimating lifetime based on several examples. The process of flowchart 400, as defined in block 401, can be executed when the measured supply voltage is less than or equal to a first reference voltage (a pre-RRT voltage corresponding to known remaining supply capacity or other specified reference voltage). Control circuitry 206 can measure the battery voltage of supply 214 at planned time intervals or during planned times of day. After the pre-RRT voltage is reached, the process for determining the estimated lifetime is executed and can be repeated on a planned or triggered basis or upon receiving a command from another medical device.

[0101] In some instances, the power supply voltage measurement result is optional once the first reference voltage is reached and an elapsed time counter is started to count the number of days since the first reference voltage was reached. Determining the estimated lifetime after the reference voltage is reached does not require the power supply voltage. As mentioned above, the estimated lifetime can be calculated using the known remaining battery capacity at the pre-RRT voltage, the estimated total current consumption, and the actual number of days elapsed since the pre-RRT voltage was measured. However, as mentioned above, the power supply voltage measurement can be performed each time the lifetime is estimated, so that the actual battery voltage can trigger a replacement notification or EOS notification.

[0102] At block 402, control circuitry 206 retrieves pacing control parameters to determine the therapy delivery current consumption. In one example, the currently programmed pacing pulse width and pacing pulse amplitude are retrieved from memory 210. At block 404, control circuitry 206 may determine pacing impedance. For example, control circuitry 206 may control therapy delivery circuitry 202 to apply a drive signal (current or voltage) to electrodes 162 and 164, thereby enabling the recording of the resulting signal (voltage or current) for determining pacing impedance. In other examples, previously measured pacing impedance stored in memory 210 may be retrieved for determining pacing current consumption.

[0103] At box 406, the therapy delivery current consumption is determined using the retrieved pacing pulse amplitude and pacing pulse width settings and the measured pacing impedance. In some instances, the therapy delivery current consumption is determined by retrieving the current consumption value from a lookup table (LUT) stored in memory 210 (or memory 53 of external device 20 when processor 52 is determining the estimated lifetime).

[0104] Figure 7 This is an example of a LUT 500 that stores the current consumption values ​​for therapeutic delivery. Multiple LUTs can be stored in memory 210, each LUT corresponding to a specified pacing parameter. Each LUT can store current consumption values ​​associated with multiple combinations of two other pacing parameter values ​​within a specified range for a third pacing parameter value. Figure 7 In this example, LUT 500 corresponds to a specified pacing impedance range 502, for example, greater than X ohms and less than or equal to Y ohms. Two, three, or more LUTs can be stored in memory 210, each LUT corresponding to a different pacing impedance range. For example, one LUT can be stored for pacing impedances of up to and including 450 ohms. A second LUT can be stored for pacing impedances greater than 450 ohms and less than or equal to 550 ohms. A third LUT can be stored for pacing impedances greater than 550 ohms.

[0105] LUT 500 contains stored pacing current consumption values ​​508 for each combination of multiple pulse amplitude settings 504 and multiple pulse width settings 506. Control circuitry 206 selects from LUT 500 the pacing current consumption value corresponding to the retrieved pacing pulse width and pacing pulse amplitude. For illustration, when the pacing impedance falls within the range 502 specified for LUT 500, the pacing pulse amplitude is 0.6 volts (second column) and the pacing pulse width is 0.24 (first row), and the pacing current consumption value retrieved from LUT 500 is 77 (in 8-bit mathematics). It should be understood that, based on... Figure 7Specific examples of LUTs are formatted using different combinations of pacing parameters. For instance, each LUT can store specified values ​​or ranges of pacing pulse amplitude with multiple current consumption values ​​for each combination of different pacing impedance ranges and pacing pulse width ranges. In various instances, the LUT can store current consumption values ​​for combinations of two, three, four, or more pacing parameters, and multiple arrangements of pacing parameters within the LUT are possible. Other pacing parameters that can be considered in the LUT may include pacing rate, pacing frequency, or therapy delivery mode.

[0106] For example, when delivering dual-chamber or multi-chamber pacing therapy, additional LUTs can be provided for each chamber or pacing site. For instance, one or more LUTs can store current consumption values ​​associated with the delivery of atrial pacing pulses, while another set of one or more LUTs can store current consumption values ​​associated with the delivery of ventricular pacing pulses. In other cases, a single set of LUTs can be expanded to include appropriate ranges of pacing parameters, such as pacing impedance, pacing pulse amplitude, and / or pacing pulse width, which will be relevant to all chambers or sites to which the pacing therapy is being delivered. For example, LUTs can store current consumption values ​​across a range of pacing pulse amplitude and pacing pulse width for all available settings of atrial and ventricular pacing control parameters. These LUTs can be stored for multiple pacing impedance ranges spanning the expected range of atrial and ventricular pacing impedance. In this way, appropriate current consumption values ​​can be stored in LUTs (or a set of LUTs) for retrieval to determine the therapy delivery current consumption associated with the therapy delivered to each chamber or multiple cardiac locations.

[0107] The pacing current consumption value stored in LUT 500 can represent the expected pacing current consumption for the corresponding pulse amplitude, pulse width, and pacing impedance when the therapy delivery circuit 202 generates pacing pulses at a specified rate. In one example, the current consumption value stored in each LUT corresponds to 100% of the time pacing at a rate of 60 pulses per minute. Therefore, control circuit 206 can adjust the pacing current consumption value retrieved from the LUT based on the actual pacing frequency since implantation. Control circuit 206 can be configured to count the total number of pacing pulses generated by the therapy delivery circuit 202 since IMD implantation. Control circuit 206 can be further configured to track the total time since implantation or since the last lifespan estimate. These values ​​of the total number of pacing pulses generated and the total time since implantation can be tracked by a counter included in control circuit 206. The pacing current consumption retrieved from LUT 500 can be multiplied by the total number of pacing pulses since implantation and divided by the time since implantation to adjust the retrieved current consumption according to the actual pacing frequency since implantation.

[0108] Therefore, in Figure 6At block 406, control circuitry 206 determines the therapy delivery current consumption by retrieving the pacing pulse width, amplitude, and impedance from a LUT stored in memory 210 and corresponding to the pacing current consumption at an assumed pacing frequency. The retrieved pacing current consumption is adjusted to correspond to the actual pacing frequency using the stored total number of generated pacing pulses and the stored total time since implantation. At block 406, the adjusted pacing current consumption is determined as the therapy delivery current consumption.

[0109] When a medical device delivers therapy to multiple heart chambers, cardiac locations, or more generally multiple therapy delivery sites, the therapy delivery current consumption can be determined for each therapy delivery site and summed to determine the total therapy delivery current consumption. The therapy delivery current consumption determined for each site can be determined by retrieving the current consumption of pacing parameters specific to that therapy delivery site from the LUT and adjusting the LUT current consumption according to the percentage of time since implantation when therapy has been delivered to that therapy delivery site. For example, in a dual-chamber or multi-chamber pacemaker, the atrial therapy current consumption and the ventricular therapy current consumption (for each of one or both ventricles) can be determined and summed to determine the total therapy delivery current consumption.

[0110] In other instances, multiple LUTs can each store current consumption values ​​associated with different therapy delivery modes. For example, at least one LUT can store current consumption values ​​for single-chamber therapy; at least one LUT can store current consumption values ​​for dual-chamber therapy and / or at least one LUT can store current consumption values ​​for multi-chamber therapy. In this case, the current consumption value for each therapy delivery mode (e.g., single-chamber and dual-chamber pacing modes) can be retrieved from the respective single-chamber pacing mode LUT and dual-chamber pacing mode LUT. The retrieved current consumption values ​​can be adjusted for the percentage of time spent in the respective single-chamber pacing mode and dual-chamber pacing mode to determine the corresponding single-chamber pacing therapy current consumption and dual-chamber pacing therapy current consumption. The pacing mode current consumptions can be summed to determine the total therapy delivery current consumption.

[0111] exist Figure 6At box 408, control circuitry 206 retrieves the total “on” time for each accelerometer axis of sensor 212 during the operational lifetime of IMD 14, e.g., since implantation of IMD 14. The total “on” time for each accelerometer axis can be accumulated by control circuitry 206 and stored in memory 210, e.g., in buffer 250, as described above. Since one, two, or three accelerometer axes can be selected at a time to generate acceleration vector signals, each channel can have a different total “on” time. Furthermore, one or more accelerometer axes can be selected to monitor patient activity during rate-responsive pacing modes. For example, when IMD 14 is configured to switch between atrial tracking VDD pacing mode and non-tracking, rate-responsive VVIR pacing mode, the total “on” time for each accelerometer axis will depend on which axes are selected to generate acceleration signals for sensing atrial contraction events and for tracking patient physical activity, as well as the relative amount of time spent in each therapy delivery mode.

[0112] The power supply current consumption of each accelerometer axis is determined by multiplying the total "on" time of the retrieved given axis by the predetermined accelerometer current consumption for each channel. At box 410, the three current consumptions determined for each of the three axes of the accelerometer can be added together to determine the sensor operating current consumption.

[0113] At block 412, control circuitry 206 can retrieve the total time spent in VDD pacing mode since implantation. As described above, control circuitry 206 can be configured to switch between two or more pacing modes for controlling therapy delivery circuitry 202 to generate pacing pulses. The atrial-tracking ventricular pacing mode can include sensing atrial contraction events from one or more acceleration vector signals received from sensor 212, which may include powering one or more selected accelerometer axes. Sensor operating current consumption is determined by taking into account the current consumption required to operate the accelerometer axes selected to generate acceleration signals that can detect atrial contraction events. However, control circuitry 206 performs signal analysis on the received accelerometer axis signals to detect atrial contraction events on a beat-by-beat basis, enabling the generation of ventricular pacing pulses during the atrioventricular interval following each atrial contraction event detection. Therefore, this atrial-tracking ventricular pacing mode (e.g., VDD pacing mode) requires greater processing power and current consumption than non-atrial-tracking ventricular pacing modes (e.g., VVI pacing mode or VOO pacing mode, which do not require detection of atrial contraction events from acceleration signals on a per-beat basis).

[0114] Therefore, to improve the accuracy of lifetime estimation, control circuitry 206 can track the total time spent in VDD pacing mode since implantation. The percentage of time spent in VDD pacing mode can be multiplied by a predetermined processing current consumption required for control circuitry 206 to detect atrial contraction events. This processing burden current consumption, determined at block 414, and the sensor operating current consumption, determined at block 410, both represent the current consumption from power supply 214 required for operation in a specific therapy delivery mode (e.g., atrial-tracking ventricular pacing mode), which requires the generation and analysis of physiological signals by sensor 212 to control therapy delivery. The physiological signals generated by sensor 212, such as acceleration vector signals, are different from the cardiac electrical signals sensed by cardiac electrical signal sensing circuitry 204. The generation, processing, and analysis of this additional physiological signal, as required by a specific therapy delivery mode, increases the current consumption from power supply 214 and is therefore taken into account in the lifetime estimation techniques disclosed herein. In various instances, at least sensor operating current consumption and / or processing burden current consumption corresponding to the operating mode requiring processing and analysis of sensor signals are determined for power supply lifetime estimation.

[0115] exist Figure 6 In one example, the processing burden current consumption is determined based on the percentage of time the control circuit 206 has operated in a specific therapy delivery mode since implantation. In other examples, the processing burden current consumption may be determined based on the percentage of time the medical device has operated in one or more sensing and / or therapy delivery operating modes. For example, the control circuit 206 may track the total time operating in a dual-chamber sensing mode that requires processing and analyzing accelerometer signals to detect atrial contraction events. In other examples, the processing burden current consumption may be determined for two or more operating modes of the medical device. A portion of the processing burden current consumption may be determined for each of the multiple operating modes, where each operating mode is associated with a different processing current requirement multiplied by the percentage of time the medical device has operated in the associated operating mode. The processing burden of each of the multiple operating modes may be summed to obtain the total processing burden current consumption.

[0116] At box 416, the total current consumption is determined by adding the therapy delivery current consumption, sensor operating current consumption, processing load current consumption, and any predetermined quiescent current consumption used to power basic IMD functions that require relatively constant current consumption throughout the IMD's lifetime. At box 418, the lifetime is determined based on the difference between the power supply capacity associated with a first reference voltage and the power supply capacity associated with a second, lower reference voltage. The estimated lifetime between the two voltage levels is obtained by dividing the capacity difference by the total current consumption and then converting it to the desired time unit. For example, dividing the capacity difference in ampere-hours by the current consumption in amperes can be divided by 24 hours / day to obtain the estimated lifetime (in days) from the first voltage to the second voltage. In some instances, the first voltage is Figure 4 The pre-RRT voltage shown is the second voltage, which is the EOS voltage, and the capacity difference between the pre-RRT voltage and the EOS voltage can be set to 25% of the BOS capacity.

[0117] At box 420, the estimated lifetime from the first voltage to the second voltage can be adjusted by subtracting the actual number of days that have elapsed since the self-measured first reference voltage. This adjusted estimated lifetime can be compared with a lifetime threshold to determine when an output should be generated, such as a notification recommending replacement or an EOS notification (as described above). Figure 5 (As described).

[0118] Figure 8 It is based on an example that can be made by a medical device system (e.g., Figure 1 The flowchart 600 describes a method for determining a comparative lifetime estimate executed by the IMD system 10). At block 602, lifetime can be estimated by using historical data and currently programmed control parameters to determine the estimated time between two supply voltages, each associated with a specified remaining supply capacity. The lifetime estimated at block 602 can be further described in conjunction with the above. Figure 5 and 6 The described example techniques are used to determine this. For example, data accumulated and stored by the medical device relating to the cumulative “on” time of each channel or axis of a physiological sensor and / or stored data relating to the total time spent operating in one or more operating modes corresponding to different processing current consumption requirements can be retrieved to determine an estimated lifetime based on the medical device’s historical operation.

[0119] At box 604, the processor of the medical device system can determine one or more alternative lifetimes. For example, the processor 52 of the external medical device 20 can determine an alternative lifetime based on alternative settings of one or more programmable parameters. For example, fewer physiological sensor channels can be used to estimate the lifetime. Using a triaxial accelerometer as an example, if two or all three axes are selected during atrial tracking ventricular pacing mode to generate acceleration signals for detecting atrial contraction events, the processor can determine alternative sensor operating current consumption to eliminate the current consumption for one accelerometer axis based on alternative programming of sensing control parameters for selecting one less axis to sense the atrial contraction event. For example, when three axes are selected to sense atrial contraction events, the alternative lifetime can be determined by adding the current consumption required to generate accelerometer vector signals only from two accelerometer axes, rather than all three, using the cumulative operating time stored in memory 210 for only two axes.

[0120] In another instance, the processor can determine the alternative lifetime based on changes to the operating mode of the medical device. For example, if the operating mode is programmed for a permanent atrial-tracking ventricular pacing mode and automatically switches to a temporary non-tracking ventricular pacing mode, the alternative lifetime can be determined based on reprogramming the permanent pacing mode to a non-tracking ventricular pacing mode. In this case, the alternative lifetime can be determined by eliminating the processing load current consumption determined based on the cumulative time spent in the atrial-tracking ventricular pacing mode. By reprogramming to a non-tracking ventricular pacing mode, the functional lifetime of the IMD 14 can be extended while still providing ventricular rate support.

[0121] In other instances, alternative values ​​or settings for other programmable parameters that control therapy delivery, such as pacing pulse amplitude, pacing pulse width, pacing electrode selection (with different pacing impedances), and lower pacing rates, can replace the currently programmed values ​​or settings to determine alternative lifetimes. For example, alternative pacing control parameters can be used to retrieve therapy delivery current consumption values ​​from the LUT to determine alternative therapy delivery current consumption compared to the current consumption determined at box 602.

[0122] Alternative values ​​or settings of any control parameter, which are programmable parameters and considered in the dynamic portion of the total current consumption determined for estimated lifetime, can be selected to determine the alternative lifetime at box 604. The estimated lifetime determined at box 602 is based on historical operating data of the medical device and currently programmed control parameters. The alternative lifetime determined at box 604 is based on at least one variation of the programmable control parameters that would alter the total current consumption required for sensor operation, processing of physiological signals during a specified operating mode, and / or therapy delivery. One or more alternative lifetimes can be determined at box 604, each lifetime based on alternative values ​​or settings of one or more programmable control parameters.

[0123] At box 606, the medical device system 10 generates a comparison lifetime output. For example, the estimated lifetime can be determined by control circuit 206 and via telemetry circuit 208 (in... Figure 3 The data is transmitted to the external device 20. One or more alternative lifetimes can be determined by the processor 52 of the external device 20. At block 606, the processor 52 of the external device 20 can cause the display unit 54 to generate an estimated lifetime display based on historical data and currently programmed parameters and one or more alternative lifetimes.

[0124] Figure 9 This is a diagram of a graphical user interface (GUI) 700 containing data that can be output by one or more processors of the medical device system 10 for displaying estimated lifespan and related data. The processor 22 of the external device 20 can generate data output for display unit 54 to display in the GUI 700. In one example, a notification window 710 is displayed, which contains any statements or notifications related to the estimated lifespan. For example, the estimated lifespan in days (which may be in...) can be reported in the notification window 710. Figure 5 The adjusted estimated lifespan is determined at box 368. Alternatively or alternatively, the measured power supply voltage can be reported. When a threshold voltage or threshold number of days has been reached, notification window 710 can report a notification indicating that the replacement time, voltage, or EOS has been reached.

[0125] GUI 700 may further include a table 701 containing data related to the reported estimated lifetime. Table 701 may include an estimated lifetime 702, which... Figure 9The example is displayed in days. The estimated lifetime 702 is determined using the techniques described above based on actual historical operating data accumulated in the IMD memory 210 and currently programmed control parameters. Programmable control parameters 704 associated with the estimated lifetime 702 can be listed according to their actual current values ​​or settings, which contribute to or influence the determination of the total current consumption used to determine the estimated lifetime 702. The listed control parameters 704 may include programmable therapy control parameters (such as pulse amplitude, pulse width, and lower pacing rate). Control parameters 704 may further include programmable sensing control parameters, such as physiological sensor selection parameters. In an example of an IMD 14 with a triaxial accelerometer, the axis selected for detecting atrial contraction events can be displayed. Control parameters 704 may further include programmable operating modes, such as programmable therapy delivery modes and / or programmable sensing or monitoring modes.

[0126] In the illustrative example shown, the listed value 720 of the control parameter 704 used to determine the estimated lifetime 702 includes a permanent VDD pacing mode (which can be temporarily switched to other pacing modes according to the pacing mode switching criteria applied by the control circuit 206). Other programmable control parameters on which the estimated lifetime 702 is based are shown as including a programmed pulse amplitude of 3.0 volts, and accelerometer axes 1 and 2 selected to generate an acceleration vector signal to detect atrial contraction events during VDD pacing mode. It should be understood that the specific control parameters and values ​​listed in Table 701 are illustrative rather than limiting in nature. It should be recognized that Table 701 may list more or fewer than three programmable control parameters that contribute to or influence the dynamic portion of the total current consumption determined for the estimated lifetime 702.

[0127] Lifetime table 701 may further include a list of operational metrics 705, which control circuitry 206 determines and stores in memory 210 for use in determining estimated lifetime 702. The operational metrics 705 listed in table 701 may be operational metrics that influence or contribute to the determination of total current consumption for estimated lifetime 702. For example, operational metrics 705 associated with estimated lifetime may include the percentage of time the IMD 14 operates in VDD pacing mode, measured pacing impedance, and total “on” time for each accelerometer axis. Operational metrics 705 may be non-programmable values, but are values ​​that are measured or accumulated and stored in memory 210 of the IMD 14 to determine the dynamic portion of total current consumption used to determine estimated lifetime 702, such as processing load current consumption (associated with the percentage of time in VDD pacing mode), sensor operating current consumption (associated with the “on” time for each accelerometer axis), and therapy delivery current consumption (associated with pacing impedance).

[0128] In an illustrative example, the value 722 of the operational metric 705 displayed in the GUI 700 includes the percentage of time spent in VDD pacing mode, pacing impedance, and the percentage of cumulative time each accelerometer axis is energized. The percentage of time spent in VDD pacing mode, due to atrial contraction event detection, helps handle the burden current consumption and is determined to be 80% by the control circuitry 206. The pacing impedance is measured at 450 ohms. The pacing impedance contributes to the therapeutic delivery current consumption. The “on” time of each accelerometer axis contributes to the sensor's operational current consumption. The first accelerometer axis is energized for 100% of the time and can be used for atrial contraction event sensing and monitoring of patient physical activity. The second accelerometer axis may be energized for 50% of the time, only during VDD pacing, and the accelerometer axis may be de-energized at certain times due to a blanking period that can be applied during each cardiac cycle. The third accelerometer axis may be an unselected axis, energized for 0% of the time, as shown by the displayed value 722 of the operational metric 705.

[0129] exist Figure 9 The specific operating metric 705 shown as an example is illustrative in nature. It should be recognized that more or fewer than three operating metrics may be displayed in Table 701. Each of the operating metrics shown may be selected for display because each operating metric affects or contributes to the dynamic portion used to determine the total current consumption for the estimated lifetime 702.

[0130] The GUI 700 allows the user to view the estimated lifetime 702 and one or more alternative lifetimes 706a-706n determined based on alternative settings 730, 740 of one or more programmable control parameters 704. The processor 52 of the external device 20 can be configured to determine the alternative lifetime 706 based on adjusted values ​​of one or more programmable control parameters 704, rather than the actual programmed parameter values ​​720 associated with the estimated lifetime 702. In some instances, the alternative control parameter settings are automatically selected by the processor 52. Alternatively or additionally, alternative settings or values ​​for the programmable control parameters can be manually entered by a user interacting with the graphical user interface.

[0131] A list of control parameter settings 720 and operating metric values ​​722 corresponding to the estimated lifetime 702 can be fixed in the displayed output table 701, as these settings and values ​​represent the current settings and values ​​of the programmable control parameters and historical operating metrics used to determine the estimated lifetime 702. However, the values ​​730, 740 of the control parameters 704 listed in association with one or more alternative lifetimes 706a, 706n can be adjusted by the processor 52 or by the user. For example, a user interacting with the GUI 700 can adjust one or more control parameter settings 730 listed for the alternative lifetime 706a. The processor 52 of the external device 20 can determine the alternative lifetime 706a based on the adjusted control parameter settings 730 by redetermining the total current consumption based on the adjusted control parameters.

[0132] In this hypothetical example, the user can select an alternative permanent pacing mode for VVIR and a pacing pulse amplitude of 2.8 volts. Since atrial contraction event sensing is not performed during permanent VVIR pacing mode, the selected accelerometer axis may be indicated as inapplicable (N / A). Based on these alternative control parameter settings 730, the processor 52 can determine the expected or relative changes in the operational metric 705. For example, if the pacing mode is changed to VVIR, the percentage of time spent in VDD pacing mode could be 0%. In this example, the pacing impedance could be maintained at 450 ohms. Because the accelerometer axis selected for atrial contraction event detection is not used during VVIR pacing, the expected axis “on” time for the first axis used to monitor patient activity might be 100%, while the expected axis “on” time for the remaining two axes might be zero.

[0133] Processor 52 redetermines the sensor operating current consumption, processing load current consumption, and therapy delivery current consumption based on alternative control parameter settings 730 and estimated operating metrics 732. The alternative lifetime 706a is determined by processor 52 based on the redetermined total current consumption. In this hypothetical example, alternative control parameter settings could result in an alternative lifetime of 320 days compared to the estimated lifetime of 200 days for 702. The alternative lifetime can be determined based on the power supply capacity at a reference voltage (e.g., at the pre-RRT voltage) and by combining the above... Figure 5 The value of the time counter is used for adjustment.

[0134] In another illustrative example, the alternative lifetime 706n can be determined by processor 52 based on pacing mode VDD, pulse amplitude 3.0 volts, and all three accelerometer axes selected for sensing atrial contraction events, for comparison with lifetime using only the two accelerometer axes associated with the estimated lifetime 702. In this case, the percentage of operation in VDD pacing mode listed in operational metric 742 can be estimated to be the same as the measured percentage listed in operational metric 722 of the actual estimated lifetime 702. The measured pacing impedance is the same as 450 ohms. The axis “on” time for axis 1 is expected to be 100%, axis 2 50% (the same as the actual axis 2 on time listed in operational metric 722), and axis 3 50%, which are summed for atrial contraction event sensing in alternative control parameter settings 740. Compared to the estimated lifetime of 200 days 702 when only two accelerometer axes are used for atrial event detection, the processor 52 can determine a relatively shorter alternative lifetime of 170 days 706n due to the selection of a third accelerometer axis for atrial event detection.

[0135] These illustrative examples demonstrate that the techniques disclosed herein for estimating the time between two voltages of a medical device power supply can be based on actual, programmed control parameter settings and historical operating metrics, or alternative control parameter settings and assumed operating metrics (based on alternative control parameter settings). In this way, the estimated lifetime 702 based on actual control parameter settings and historical operating metrics can be compared with one or more alternative lifetimes that could be expected if one or more control parameters were programmed to change, which may include sensing and / or therapy delivery control parameters. Furthermore, it should be understood that alternative lifetimes 706a-706n can be determined and compared when the estimated lifetime 702 is uncertain. For example, alternative lifetimes 706a-706n can be determined at or after IMD implantation based on various choices of programmable control parameters 704 required to determine total current consumption and alternative lifetimes 706a-706n, and estimated or assumed values ​​of operating metrics 705. When determining the estimated lifetime 702 or alternative lifetime 706a-n during IMD implantation, the first voltage may be the BOS voltage corresponding to 100% power capacity, and the second lower voltage may be any selected voltage associated with the second lower power capacity, such as the EOS voltage and 0% capacity.

[0136] The GUI 700 displayed by display unit 54 may include "select" buttons 712, 714, and 716 for each of the lists of control parameter values ​​720, 730, and 740 associated with the corresponding estimated lifespan 702 and alternative lifespans 706a and 706n. The user can use selection button 712 to select an existing control parameter value 720. External device 20 does not make any programming changes to control parameter 704 because the selection corresponds to an existing programmed control parameter value.

[0137] However, given an understanding of how operational metrics 732 and 742 will alter expected lifespan, the user can select alternative control parameter settings 730 or 740 based on alternative lifespans 706a or 706n. Various trade-offs can be made between therapy delivery and / or physiological signal monitoring operations and power lifespan. For example, when the alternative lifespan 706n is within an acceptable range of the estimated lifespan 702, selection button 716 can be used to select the expected improvement in therapy delivery based on more accurate atrial event sensing, which is based on all three sensing vectors. On the other hand, control parameter value 730 can be selected using selection button 714 to maximize lifespan while providing basic ventricular rate support to the patient in VVIR pacing modes as listed in control parameter setting 730.

[0138] In response to a user selection of selection button 714 or 716 associated with an alternative lifetime 706a or 706n, external device processor 52 can control telemetry unit 58 to transmit the corresponding programmable control parameter setting 730 or 740 (or at least any setting indicating a change from the current setting 720) to IMD 14. In this way, the user can adjust one or more programmable control parameters 704 in GUI 700 to observe how changes in the programmable control parameters alter the expected alternative lifetimes 706a-706n compared to the actual estimated lifetime 702. Using selection buttons 714 or 716, the user can simultaneously input programmable changes to multiple programmable control parameters based on a comparison display of the estimated and alternative lifetime values ​​702, 706a-706n.

[0139] The exemplary techniques of this disclosure are set forth in the following terms.

[0140] Clause 1: A method comprising: generating a physiological signal via a sensor coupled to a power source; detecting an event from the physiological signal; determining a first current consumption, the first current consumption including current from the power source required for at least one of: generating the physiological signal and detecting the event from the physiological signal; determining an estimated time from a first voltage of the power source to a second voltage of the power source based on the first current consumption and a power source capacity difference, wherein the first voltage of the power source corresponds to a first power source capacity, the second voltage corresponds to a second power source capacity less than the first power source capacity, and the power source capacity difference is the difference between the first power source capacity and the second power source capacity; generating an output based on the estimated time; and storing data corresponding to the estimated time in a memory in response to the generated output.

[0141] Clause 2: The method according to Clause 1 includes: determining that the estimated time has reached a threshold lifetime; and generating the output by generating a notification in response to the estimated time reaching the threshold lifetime.

[0142] Clause 3: The method according to Clause 1 or 2 includes: determining the cumulative time for powering the sensor to generate the physiological signal; and determining the first current consumption based at least on the cumulative time for powering the sensor to generate the physiological signal.

[0143] Clause 4: The method according to any one of Clauses 1 to 3, comprising: switching between a first operating mode that includes detecting the event from the physiological signal and a second operating mode that does not include detecting the event from the physiological signal; determining a cumulative time of operation in the first operating mode; and determining the first current consumption based at least on the cumulative time of operation in the first operating mode.

[0144] Clause 5: The method according to any one of Clauses 1 to 4 includes determining the first current consumption by at least determining the processing burden current consumption, the processing burden current consumption corresponding to the current from the power source required to detect the event from the physiological signal.

[0145] Clause 6: The method according to any one of Clauses 1 to 5 further comprises determining the first current consumption by determining the therapeutic delivery current consumption from the power source required for the delivery of the therapy.

[0146] Clause 7: The method according to Clause 6, wherein the control circuit is configured to determine the therapy delivery current consumption by: determining pacing impedance; determining pacing current consumption based at least on the pacing impedance; determining pacing frequency; and determining the therapy delivery current consumption based on the pacing current consumption and the pacing frequency.

[0147] Clause 8: The method according to Clause 7 further includes: storing at least one lookup table containing multiple pacing current consumption values ​​corresponding to multiple pacing control parameter values; wherein determining the therapy delivery current consumption includes selecting a pacing current consumption value from the lookup table.

[0148] Clause 9: A method according to any one of Clauses 1 to 8, comprising: generating a channel signal through each of a plurality of channels of the sensor when each channel is selectively powered by the power supply; and determining the first current consumption by: determining, for each of the plurality of channels, the cumulative time during which the channel is selectively powered by the power supply to generate the channel signal; and determining the first current consumption based on the determined cumulative time during which each channel of the sensor is selectively powered by the power supply.

[0149] Clause 10: A method according to any one of Clauses 1 to 9, comprising: determining the voltage of the power supply; determining that the voltage of the power supply has reached a first voltage corresponding to the first power supply capacity; and in response to determining that the voltage of the power supply has reached the first voltage, determining the first current consumption and the estimated time until the second voltage.

[0150] Clause 11: A method according to any one of Clauses 1 to 10, comprising: determining a voltage of the power supply; determining that the voltage of the power supply has reached a first voltage; in response to determining that the voltage of the power supply has reached the first voltage, starting a timer to track elapsed time; determining a value of the timer when the estimated time is determined; and adjusting the estimated time by the value of the timer.

[0151] Clause 12: A method according to any one of Clauses 1 to 11, comprising: determining a first current consumption based on a current setting of control parameters; determining a second current consumption based on an alternative setting of the control parameters; determining an alternative estimated time from the first voltage of the power supply to the second voltage of the power supply based on the second current consumption and the power supply capacity difference; and generating a comparison output of the estimated time and the alternative estimated time.

[0152] Clause 13: The method according to any one of Clauses 1 to 12 includes displaying a graphical user interface in response to the generated output, the graphical user interface including at least a display representing the estimated time.

[0153] Clause 14: A method according to any one of Clauses 1 to 13, comprising: generating the physiological signal by generating an acceleration signal from at least one axis of an accelerometer having a plurality of axes; detecting a cardiac event from the physiological signal; generating a pacing pulse in response to each cardiac event detected from the physiological signal; and determining the first current consumption by: determining a sensor operating current consumption by determining a cumulative time for selectively powering each of the plurality of axes of the accelerometer to generate the physiological signal; determining a processing burden current consumption required to detect the cardiac event from the physiological signal; and determining a therapy delivery current consumption by: determining a pacing impedance; determining at least one pacing pulse control parameter; determining a pacing frequency; and determining the therapy delivery current consumption based on the pacing impedance, the at least one pacing pulse control parameter, and the pacing frequency; and determining the first current consumption based at least on the sensor operating current consumption, the processing burden current consumption, and the therapy delivery current consumption.

[0154] Clause 15: A non-transitory computer-readable medium storing a set of instructions that, when executed by a processing circuitry system of a medical device system, cause the medical device system to perform the following operations: generate a physiological signal via a sensor coupled to a power source; detect an event from the physiological signal; determine a current consumption comprising at least one of the following: generating the physiological signal and detecting the event from the power source; determine an estimated time from a first voltage of the power source to a second voltage of the power source based on the first current consumption and a power source capacity difference, wherein the first voltage of the power source corresponds to a first power source capacity, the second voltage corresponds to a second power source capacity less than the first power source capacity, and the power source capacity difference is the difference between the first power source capacity and the second power source capacity; generate an output based on the estimated time; and store data corresponding to the estimated time in response to the generated output.

[0155] It should be understood that, depending on the examples, certain actions or events in any of the methods described herein may be performed in a different order, or may be added, combined, or omitted entirely (e.g., not all described actions or events are necessary for practicing the methods). Furthermore, in some instances, actions or events may be performed, for example, through multithreaded processing, interrupt handling, or simultaneous execution by multiple processors, rather than sequentially. Additionally, although some aspects of this disclosure are described for clarity as being performed by a single circuit or unit, it should be understood that the techniques of this disclosure can be performed through a combination of units or modules associated with, for example, a medical device.

[0156] In one or more instances, the described functionality may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functionality may be stored on a computer-readable medium in the form of one or more instructions or code and may be executed by a hardware-based processing unit. The computer-readable medium may include a computer-readable storage medium, which corresponds to a tangible medium such as a data storage medium (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store the required program code in the form of instructions or data structures and is accessible by a computer).

[0157] Instructions can be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable logic arrays (FPLAs), or other equivalent integrated or discrete logic circuit systems. Therefore, the term "processor" as used herein can refer to any of the foregoing structures or any other structure suitable for implementing the techniques described herein. Furthermore, the techniques can be fully implemented in one or more circuit or logic elements.

[0158] Therefore, a medical device system has been presented in the foregoing description with reference to specific examples. It should be understood that the various aspects disclosed herein can be combined in combinations different from the specific combinations presented in the accompanying drawings. It should be understood that various modifications can be made to the reference examples without departing from the scope of this disclosure and the following claims.

Claims

1. A medical device system comprising: power supply; A sensor, coupled to the power source and configured to generate physiological signals; A control circuit coupled to the power supply and the sensor, the control circuit being configured to detect events from the physiological signals and to determine the voltage of the power supply; as well as Processor, the processor being configured to: Determine that the voltage of the power supply has reached the first voltage; Determine a first current consumption, which includes the current from the power source required for at least one of the following: generating the physiological signal and detecting the event from the physiological signal; In response to determining that the voltage of the power supply has reached the first voltage, a timer is started to track the elapsed time; An estimated time from the first voltage of the power supply to the second voltage of the power supply is determined based on the first current consumption and the power supply capacity difference, wherein the first voltage of the power supply corresponds to the first power supply capacity, the second voltage corresponds to the second power supply capacity which is less than the first power supply capacity, and the power supply capacity difference is the difference between the first power supply capacity and the second power supply capacity. The estimated time is adjusted by the value of the timer; as well as The output is generated based on the adjusted estimated time; as well as A memory configured to store data corresponding to the estimated time in response to the output generated by the processor.

2. The medical device system of claim 1, wherein the processor is configured to: It has been determined that the estimated time has reached the threshold lifetime; and The output is generated by generating a notification in response to the estimated time reaching the threshold lifetime.

3. The medical device system according to claim 1 or 2, wherein the control circuit is configured to: Determine the cumulative time for powering the sensor to generate the physiological signal; and The first current consumption is determined at least based on the cumulative time for powering the sensor to generate the physiological signal.

4. The medical device system according to claim 1 or 2, wherein: The control circuit is configured to: Switching between a first operating mode that includes detecting the event from the physiological signal and a second operating mode that does not include detecting the event from the physiological signal; as well as Determine the cumulative time of operation in the first operating mode; and The processor is configured to determine the first current consumption based at least on the cumulative time of operation in the first operating mode.

5. The medical device system of claim 1 or 2, wherein the processor is configured to determine the first current consumption by at least determining the processing burden current consumption, the processing burden current consumption corresponding to the current from the power source required by the control circuit to detect the event from the physiological signal.

6. The medical device system of claim 1 or 2, further comprising a therapy delivery circuit coupled to the power source and configured to deliver therapy; The processor is further configured to determine the first current consumption by determining the therapy delivery current consumption from the power source required to deliver the therapy.

7. The medical device system of claim 6, wherein the control circuitry is configured to determine the therapeutic delivery current consumption by: Determine the pacing impedance; The pacing current consumption is determined at least based on the pacing impedance; Determine the pacing rate; and The therapy delivery current consumption is determined based on the pacing current consumption and the pacing frequency.

8. The medical device system according to claim 7, further comprising: The memory stores at least one lookup table containing multiple pacing current consumption values ​​corresponding to multiple pacing control parameter values; The control circuitry is configured to determine the therapy delivery current consumption by selecting a pacing current consumption value from the lookup table.

9. The medical device system according to claim 1 or 2, wherein: The sensor includes multiple channels, each of which is configured to generate a channel signal when selectively powered by the power source. and The control circuit is configured to determine the first current consumption in the following manner: For each of the plurality of channels, determine the cumulative time during which the channel is selectively powered by the power supply to generate the channel signal; as well as The first current consumption is determined based on a defined cumulative time during which each channel of the sensor is selectively powered by the power source.

10. The medical device system according to claim 1 or 2, wherein, The estimated time corresponds to the estimated power supply lifetime, and the processor is further configured to: Determine the time elapsed after the measured voltage reaches the first voltage; The estimated power life is adjusted based on the elapsed time.

11. The medical device system according to claim 1 or 2, wherein, The first voltage corresponds to the voltage at the pre-recommended replacement time.

12. The medical device system according to claim 1 or 2, wherein the processor is configured to: The first current consumption is determined based on the current setting of the control parameters; The second current consumption is determined based on alternative settings of the control parameters; Based on the second current consumption and the power supply capacity difference, determine the alternative time from the first voltage of the power supply to the second voltage of the power supply; and Generate a comparison output between the estimated time and the alternative time.

13. The medical device system of claim 1 or 2, further comprising a display unit configured to display a graphical user interface in response to a generated output, the graphical user interface including at least a display representing the estimated time.

14. The medical device system according to claim 1 or 2, wherein: The sensor includes an accelerometer having multiple axes, each axis of which is configured to generate an acceleration signal along the direction of the axis, and the sensor is configured to generate the physiological signal including acceleration signals from at least one of the multiple axes; The control circuit is configured to detect cardiac events from the physiological signals; The medical device system further includes a therapy delivery circuit configured to generate a pacing pulse in response to each cardiac event detected from the physiological signal; The processor is configured to determine the first current consumption in the following manner: The sensor operating current consumption is determined by determining the cumulative time for selectively powering each of the plurality of axes of the accelerometer to generate the physiological signal; Determine the processing load current consumption required to detect the cardiac event from the physiological signals; as well as The therapeutic delivery current consumption is determined in the following ways: Determine the pacing impedance; Determine at least one pacing pulse control parameter; Determine the pacing rate; and The therapeutic delivery current consumption is determined based on the pacing impedance, the at least one pacing pulse control parameter, and the pacing frequency. as well as The first current consumption is determined based at least on the sensor operating current consumption, the processing load current consumption, and the therapy delivery current consumption.

15. The medical device system according to claim 1 or 2, wherein, The processor will not determine the estimated time based on the first current consumption until it determines that the voltage has reached the first voltage.

Images