Energy management with prioritization for implantable devices

Abstract

Devices and methods for energy management are disclosed herein. In some embodiments, a device includes an energy harvesting mechanism configured to produce energy from motion of a patient. The device can also include a power source configured to receive an energy input from the energy harvesting mechanism and to deliver an energy output to power a plurality of device functions. Furthermore, the device can include processing circuitry and a memory operably coupled to the processing circuitry and storing instructions that, when executed by the processing circuitry, cause the device to detect an energy deficit between the energy input and the energy output of the power source, select one or more device functions of the plurality of device functions to deactivate based on a prioritization scheme, and deactivate the one or more device functions.

Description

ENERGY MANAGEMENT WITH PRIORITIZATION FOR IMPLANTABLE DEVICES[0001 This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 622,289, filed January 18, 2024, the entire content of which is incorporated herein by reference.TECHNICAL FIELD[0002[ The present technology generally relates to medical devices, and in particular, to energy management with prioritization for implantable devices.BACKGROUND

[0003] Various types of implantable medical devices have been developed for monitoring or treating one or more conditions of a patient. For example, a cardiac pacemaker can monitor a patient’ s heart activity and provide therapeutic electrical stimulation to the heart via electrodes. The electrical stimulation provided by the cardiac pacemaker can include signals such as pacing pulses to address abnormal cardiac rhythms (e.g., bradycardia). Some types of cardiac pacemakers are implanted a distance from the heart and are coupled to one or more leads that extend intravascularly into the heart to position the electrodes in contact with cardiac tissue. However, the leads may be prone to fracture, which may result in unreliable or incorrect pacing, and may require replacement of the lead or even the entire pacemaker.

[0004] Some types of cardiac pacemakers are sized to be completely implanted within one of the chambers of the heart, and may include electrodes integrated with or attached to the device housing rather than leads. Such pacemakers can be less invasive than traditional pacemakers and can avoid complications associated with lead fracture. However, the relatively small size of such pacemakers may limit the types of power sources that can be incorporated into the device. Smaller power sources may have lower power capacity, which can limit the longevity of the device.BRIEF DESCRIPTION OF THE DRAWINGS(00051 Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Instead, emphasis is placed on illustrating clearly the principles of the present disclosure.

[0006] FIG. 1 illustrates a pacing device implanted in the heart of a patient, in accordance with embodiments of the present technology.(0007| FIG. 2 is a perspective view of a pacing device configured in accordance with embodiments of the present technology.

[0008] FIG. 3 is a side view of another pacing device configured in accordance with embodiments of the present technology.

[0009] FIG. 4 is a schematic block diagram illustrating electronic components of a pacing device configured in accordance with embodiments of the present technology.

[0010] FIG. 5 is a side cross-sectional view of a device including an energy harvesting mechanism, in accordance with embodiments of the present technology.

[0011] FIGS. 6A-6D are illustrative graphs of cardiac motion with a normal cardiac rhythm at 77 BPM and during atrial fibrillation at 77 BPM.

[0012] FIG. 7 is a flow diagram illustrating a method for managing energy in an implantable device, in accordance with embodiments of the present technology.

[0013] FIG. 8 is a flow diagram illustrating a method for managing energy in an implantable device, in accordance with embodiments of the present technology.

[0014] FIG. 9 is a schematic representation of a prioritization scheme, in accordance with embodiments of the present technology.

[0015] FIG. 10 is a flow diagram illustrating a method for optimizing energy consumption of an implantable device, in accordance with embodiments of the present technology.DETAILED DESCRIPTION[0016| The present technology relates to energy management for implantable devices, such as cardiac pacing devices. In some embodiments, for example, a device includes an energy harvesting mechanism configured to produce energy from motion of a patient (e.g., cardiac motion of a patient’ s heart). The device can also include a power source configured to receive an energy input from the energy harvesting mechanism and to deliver an energy output to power a plurality of device functions (e.g., pacing functions, sensing functions, diagnostic functions, telemetry functions, etc.). The device can detect an energy deficit between the energy input and the energy output of the power source (e.g., due to reduced harvesting efficiency of the energy harvesting mechanism), select one or more device functions of the plurality of device functions to deactivate based on a prioritization scheme, and deactivate the one or more device functions. Further, the device can reactivate one or more of the deactivated device functions, for example, when the energy deficit is improving.[00171 The present technology can provide many advantages compared to conventional devices and methods. For instance, the energy harvesting mechanisms herein can produce electrical energy from physiological motion, thereby extending the lifetime of the implantable device by allowing for intrinsic power generation, e.g., recharging the power source in situ within the patient’s body. The energy management methods described herein further allow the implantable device to conserve and / or re-allocate energy as needed. In some embodiments, the energy management methods include selectively deactivating and / or activating one or more device functions of the implantable device to improve the longevity of the implantable device while maintaining necessary and / or desired functionalities. Moreover, the energy management methods can provide a dynamic system that can change over time depending on energy production (e.g., from the energy harvesting mechanism) and / or energy consumption (e.g., from the one or more device functions). Further, the one or more device functions can be deactivated and / or activated in an arrangement customized to the patient’s needs.[0018| For example, a piezoelectric energy harvesting mechanism may be used in a leadless pacing device that is contained entirely within a chamber of the heart. In such a location, the pacing device may be in constant motion due to the mechanical function of theheart, which presents an opportunity to harvest energy from the cardiac environment to assist in powering the device. However, changes to the motion of the heart may affect energy harvesting and thus, the ability of the pacing device to perform its intended function. In some embodiments, the pacing device may need to ensure that available energy is first allocated to life sustaining therapy and basic device functions, and secondarily to quality of life or communication functions. This prioritization may be complicated by common conditions of the heart that may simultaneously or independently modify the supply of harvestable energy and demand for energy usage, e.g., in the form of pacing. For instance, in the case of a dual chamber pacing device, both the supply and demand for energy may be impacted by the onset of atrial fibrillation. Although the power source may be able to provide backup for shortfalls in energy harvesting for a short period of time, some conditions may rapidly draw down the available power and interrupt therapy. Accordingly, a successful pacing device may need to balance energy expenditures with the power generated by the energy harvesting mechanism, e.g., to ensure continuity in the delivery of life sustaining therapy.[OOI9J To address these and other challenges, the present technology provides energy management methods and systems that can detect the factors affecting the energy supply and energy demands of a pacing device (or other implantable device), and can determine how to prioritize the functions performed by the device for a given energy budget (e.g., “triaging” which device functions can and cannot be turned off). In some embodiments, the devices herein can detect energy inputs and energy outputs, and can respond to energy deficits (e.g., due to low power generation) by prioritizing certain device functions over other device functions. For instance, a prioritization scheme can be implemented to account for factors contributing to various operational states and to determine the appropriate response for each condition. In some embodiments, only the most essential device functions are sustained in conditions of low energy yield. Alternatively or in combination, device functions may be optimized to minimize energy consumption and improve energy harvesting, e.g., including modulating the delivery of pacing signals. Device functions may be selectively turned back on based on the prioritization scheme, as power source charge status and / or energy harvesting surplus permits. The prioritization scheme may optionally be customized to the particular patient, e.g., based on a patient- specific user profile that tracks user needs, physician preferences, etc.

[0020] Embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings in which like numerals represent like elements throughout the several figures, and in which example embodiments are shown. Embodiments of the claims may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The examples set forth herein are non-limiting examples and are merely examples among other possible examples.|0021 | As used herein, the terms “vertical,” “lateral,” “upper,” “lower,” etc., can refer to relative directions or positions of features of the embodiments disclosed herein in view of the orientation shown in the Figures. For example, “upper” or “uppermost” can refer to a feature positioned closer to the top of a page than another feature. These terms, however, should be construed broadly to include embodiments having other orientations, such as inverted or inclined orientations where top / bottom, over / under, above / below, up / down, and left / right can be interchanged depending on the orientation.

[0022] The headings provided herein are for convenience only and do not interpret the scope or meaning of the claimed present technology. Embodiments under any one heading may be used in conjunction with embodiments under any other heading.I. Overview of Implantable Pacing Devices(0023| FIGS. 1-4 provide a general overview of implantable devices configured in accordance with embodiments of the present technology. Specifically, FIG. 1 illustrates a pacing device implanted in a patient’s heart, FIG. 2 illustrates an example configuration for a pacing device, FIG. 3 illustrates another example configuration for a pacing device, and FIG. 4 illustrates electronic components that can be included in a pacing device. Any of the features of the embodiments of FIGS. 1-4 can be combined with each other and / or with any of the other embodiments described herein.

[0024] Referring first to FIG. 1, which illustrates a pacing device 100 implanted in the heart H of a patient, the device 100 is configured to monitor activity of the heart H and provide electrical stimulation (e.g., pacing signals) to the heart H. In some embodiments, the device 100 is a leadless intracardiac pacemaker configured to be implanted entirely within a heart chamber, such as entirely within the right atrium (RA), entirely within the right ventricle (RV), entirely within the left atrium (FA), or entirely within the left ventricle(LV). The device 100 can be implanted at any of a variety of locations to sense and / or deliver therapy to any chamber or chambers of the heart H. For example, as shown in FIG. 1, the device 100 can be a right atrial intracardiac pacemaker that is implanted in the RA of the patient’s heart H in a target implant region T (e.g., the triangle of Koch). The target implant region T can lie between the bundle of His and the coronary sinus, and / or can be adjacent to the tricuspid valve. In other embodiments, the device 100 can instead be configured as a right ventricular intracardiac pacemaker that is implanted in the RV of the heart H, with the target implant region T lying along the endocardial wall at or near the apex of the RV.

[0025] The device 100 can include a housing 102 having a size and form factor suitable for transvenous delivery into the heart H via a catheter. In the illustrated embodiment, the housing 102 has an elongate shape extending from a distal portion 104 to a proximal portion 106. The housing 102 can have a generally cylindrical shape (e.g., pillshaped or capsule-shaped), a generally prismatic shape (e.g., a rectangular prism), or any other suitable shape. The housing 102 can define an interior cavity that contains the electronic components of the device 100 (e.g., circuitry, power source, sensors).]0026| The device 100 can include a fixation mechanism 108 to secure the device 100 to the tissue of the heart H. For example, the fixation mechanism 108 can include one or more fixation elements configured to penetrate into tissue, such as one or more tines, coils, barbs, etc. In the illustrated embodiment, the fixation mechanism 108 is coupled to and extends outwardly from the distal portion 104 of the housing 102. Accordingly, when the device 100 is implanted, the distal portion 104 can be positioned in contact with or in close proximity to the cardiac tissue, while the proximal portion 106 can be spaced apart from the cardiac tissue. In other embodiments, however, the fixation mechanism 108 can be located at a different portion of the device 100.

[0027] The device 100 also includes a plurality of electrodes configured to sense electrical activity of the heart H and / or deliver electrical therapy to the heart H. For example, the device 100 can include two, three, four, five, six, seven, eight, nine, ten, or more electrodes. Each electrode can be positioned at any suitable portion of the device 100, such as on or coupled to the housing 102 (e.g., the distal portion 104, the proximal portion 106, an intermediate location between the distal portion 104 and proximal portion 106), or on or coupled to the fixation mechanism 108. In some embodiments, the device 100 includes oneor more electrodes (e.g., cathodes) that directly contact the cardiac tissue (e.g., of a single heart chamber or multiple heart chambers) to sense the activity thereof and / or deliver electrical therapy thereto. Such electrode(s) can be located at the distal portion 104 of the housing 102 and / or incorporated into the fixation mechanism 108, for example. The device 100 can also include at least one electrode (e.g., an anode and / or return electrode) that does not directly contact cardiac tissue. Such electrode(s) can be located at portions of the housing 102 that are spaced apart from cardiac tissue, such as the proximal portion 106. Optionally, a single electrode may serve as a cathode for certain operations, and may serve as an anode and / or return electrode for other operations.[0028| In some embodiments, the device 100 is operably coupled to an external device 110 shown schematically) via bidirectional wireless communication, such as BLUETOOTH®, Wi-Fi, Medical Implant Communication Service (MICS), or other radiofrequency communication technique. The external device 110 can be a computing device or system that is located outside of the patient’s body, and can be used in a healthcare setting (e.g., in a clinic, hospital or other medical facility), at the patient’s home, or suitable combinations thereof. The external device 110 can be configured to control various operational parameters of the device 100, such as therapy parameters (e.g., pacing control parameters such as pacing interval), sensing parameters, power management parameters, etc. For instance, the external device 110 can transmit control signals to the device 100 to program one or more operational parameters of the device 100. Optionally, the external device 110 can display information relating to and / or received from the device 100, such as intracardiac electrogram (EGM) signals obtained by the device 100, motion sensor signals acquired by the device 100, operational parameters of the device 100, etc. In some embodiments, the external device 110 transmits information received from the device 100 to another computing device or system (e.g., a computer, laptop, workstation, mobile device, server, remote patient management system) for display, processing, and / or storage, using any suitable wired or wireless communication technique. The external device 110 can serve as a “programmer” that allows a physician, patient, or other individual to monitor and / or control the operations of the device 100.|0029] Although FIG. 1 illustrates a single device 100, the present technology is also applicable to implantable systems including multiple devices 100 implanted at different locations in the heart H. For example, an implantable system can include a first device 100in the RA and a second device 100 in the RV. In such embodiments, each device 100 can independently have any of the features described herein.] 00301 FIG. 2 is a perspective view of a pacing device 200 configured in accordance with embodiments of the present technology. The device 200 is configured to be implanted within a chamber of a heart of the patient to monitor activity of the heart and / or provide electrical therapy (e.g., pacing therapy) to the heart. The device 200 includes a housing 202 having a size and form factor that allows the device 200 to be entirely implanted within a single chamber of the patient’s heart. In the illustrated embodiment, the housing 202 has an elongate shape (e.g., a generally cylindrical shape, a generally prismatic shape) extending between a distal end 204 and proximal end 206. The housing 202 can define a hermetically sealed internal cavity for housing the electronic components of the device 200. The housing 202 can also include an attachment mechanism 208 (e.g., at the proximal end 206) configured to temporarily engage with a delivery tool during implantation and / or extraction of the device 200.[00311 The housing 202 can be formed partially or entirely from a conductive material, such as titanium or titanium alloy, stainless steel, MP35N (a non-magnetic nickel- cobalt-chromium-molybdenum alloy), a platinum alloy, or other biocompatible metal or metal alloy, or other suitable conductive material. Alternatively or in combination, the housing 202 can be formed partially or entirely from a nonconductive (e.g., insulative) material, such as ceramic, glass, sapphire, silicone, polyurethane, epoxy, acetyl co-polymer plastics, polyether ether ketone (PEEK), a liquid crystal polymer, other biocompatible polymer, or other suitable nonconductive material.

[0032] The device 200 can include a plurality of electrodes 210a-210c configured to sense electrical activity of the heart and / or deliver electrical stimulation to the heart. In the illustrated embodiment, for example, the device 200 includes a first electrode 210a and a second electrode 210b at or proximate to the distal end 204 of the housing 202, and a third electrode 210c on the housing 202. The first and second electrodes 210a, 210b can be configured as cathode electrodes that directly contact cardiac tissue, e.g., a distal end of the first electrode 210a can be configured to rest within a ventricular myocardium of the patient, and the second electrode 210b can be configured to contact an atrial endocardium of thepatient. The third electrode 210c can be configured as an anode and / or return electrode that does not directly contact cardiac tissue.J0033] As shown in FIG. 2, the first electrode 210a can be an elongate structure that extends from the distal end 204 of the housing 202 to penetrate through the wall tissue of a first heart chamber (e.g., the chamber in which the device 200 is implanted) into wall tissue of a second, different heart chamber. For example, in some embodiments, the device 200 is implanted in the RA with the distal end 204 oriented toward the LV (e.g., similar to the arrangement of the device 100 in FIG. 1), and the first electrode 210a extends through the wall tissue of the RA and into the wall tissue of the LV. In the illustrated embodiment, the first electrode 210a is configured as a coil (e.g., a helical and / or spiral coil), while in other embodiments, the first electrode 210a can have a different form factor (e.g., an elongate dart, barb, tine, or other tissue penetrating element). The first electrode 210a can include a proximal end that is coupled to the distal end 204 of the housing 202, and a free distal end that is not attached to the housing 202. The distal end of the first electrode 210a can have a conical, hemi-spherical, or slanted edge distal tip with a narrow tip diameter (e.g., less than 1 mm) for penetrating into and through tissue layers. In some embodiments, the distal end of the first electrode 210a can have a sharpened or angular tip, and / or sharpened or beveled edges, but the degree of sharpness can be constrained to avoid a cutting action that could lead to lateral displacement of the distal end of the first electrode 210a and undesired tissue trauma.|0034| The second electrode 210b can be a structure that extends from the distal end 204 of the housing 202 to contact the wall tissue of the first heart chamber without penetrating the wall tissue. The second electrode 210b can be located proximal to the first electrode 210a. The second electrode 210b can be configured as a coil (e.g., a partial helical and / or spiral coil that does not form a full turn), loop, button, pad, or any other suitable form factor. The second electrode 210b can include a proximal end that is coupled to the distal end 204 of the housing 202, and a distal end that may or may not be coupled to the housing 202. In some embodiments, the second electrode 210b is configured to flexibly maintain contact with wall tissue of the heart chamber in which the device 200 is implanted, (e.g., the RA endocardium), despite variations in the tissue surface and / or in the distance between the distal end 204 of the housing 202 and the tissue surface, which may occur as the wall tissue moves during the cardiac cycle. Accordingly, the second electrode 210b can be flexibleand / or have spring-like properties, e.g., the second electrode 210b can have a spring bias that urges at least a portion of the second electrode 210b away from the distal end 204 of the housing 202 and toward the wall tissue of the heart chamber to maintain consistent contact.

[0035] The first and second electrodes 210a, 210b can each be formed of an electrically conductive material, such as titanium, platinum, iridium, tantalum, or alloys thereof. The first electrode 210a can include one or more insulative coatings (e.g., parylene, polyurethane, silicone, epoxy) that reduce the electrically conductive surface area of the first electrode 210a to define a first electrically active region 212 (e.g., at or near the distal end of the first electrode 210a). The second electrode 210b can include one or more insulative coatings (e.g., parylene, polyurethane, silicone, epoxy) that reduce the electrically conductive surface area of the second electrode 210b to define a second electrically active region 214 (e.g., at an intermediate region between the proximal and distal ends of the second electrode 210b). This approach can increase the electrical impedance of the first and second electrodes 210a, 210b, and thereby reduce the current delivered during a pacing pulse, which can conserve the power used by the device 200. In some embodiments, the first and second electrodes 210a, 210b include an electrically conductive material coating (e.g., TiN) on the first and second electrically active regions 212, 214, respectively, to define the active regions. The first and second electrodes 210a, 210b can be made of the same materials, or can be made of different materials.|0036| All, substantially all, or a portion of the housing 202 can serve as a third electrode 210c (e.g., an anode and / or return electrode) during pacing and / or sensing. In some embodiments, the third electrode 210c partially or fully circumscribes a portion of the housing 202 at or near the proximal end 206. Although FIG. 2 illustrates the third electrode 210c as a singular band, in other embodiments, the third electrode 210c can include multiple segments spaced a distance apart along a longitudinal axis 216 of the housing 202 and / or around a perimeter of the housing 202. Additionally, the third electrode 210c can also be located at other positions along the housing 202, e.g., located at or near the distal end 204 or at other positions along the longitudinal axis 216.|0037| In embodiments where the housing 202 is formed from a conductive material, one or more portions of the housing 202 can be electrically insulated by anonconductive material, such as a coating of parylene, polyurethane, silicone, epoxy or other biocompatible polymer, or other suitable material. For the portions of the housing 202 without the nonconductive material, one or more discrete areas of the housing 202 with conductive material can be exposed to define the third electrode 210c. In embodiments where the housing 202 is formed from a nonconductive material, a conductive material can be applied to one or more discrete areas of the housing 202 to form the third electrode 210c. Optionally, the third electrode 210c can be a discrete component (e.g., a ring electrode) that is coupled to the housing 202.

[0038] The electrodes 210a-210c can be used to sense electrical activity of one or more heart chambers and / or to deliver electrical stimulation to one or more heart chambers. For example, the first electrode 210a can be paired with the second electrode 210b or the third electrode 210c to for sensing ventricular signals and delivering ventricular pacing pulses. As another example, the second electrode 210b can be paired with the first electrode 210a or the third electrode 210c for sensing atrial signals and delivering pacing pulses to the atrial myocardium. In a further example, the third electrode 210c can be paired at different times with both the first electrode 210a and the second electrode 210b for either ventricular or atrial functionality, respectively. As yet another example, the first electrode 210a and the second electrode 210b can be paired with each other with different polarities for atrial and ventricular functionality.

[0039] In some embodiments, the second electrode 210b is configured as an atrial cathode electrode for delivering pacing pulses to the atrial tissue at a target implant region in combination with the third electrode 210c. The second electrode 210b and the third electrode 210c can also be used to sense atrial P-waves for use in controlling atrial pacing pulses (e.g., delivered in the absence of a sensed P-wave) and for controlling atrial- synchronized ventricular pacing pulses delivered using the first electrode 210a as a cathode and the third electrode 210c as the return anode. The configuration of the electrodes 210a- 210c illustrated in FIG. 2 allows the device 200 to sense cardiac signals from and / or deliver cardiac pacing to one or more chambers of the heart. For example, the present technology can facilitate the delivery of A-V synchronous pacing using a single device 200 implanted within a single heart chamber (e.g., the RA).

[0040] The device 200 can include a fixation mechanism 218 configured to fix the device 200 to cardiac tissue at a target implant region (e.g., the triangle of Koch). In the illustrated embodiment, the first electrode 210a and / or second electrode 210b at the distal end 204 of the housing 202 can serve as the fixation mechanism 218. In other embodiments, the fixation mechanism 218 can be a different component than the first electrode 210a and / or the second electrode 210b, such one or more separate barbs, tines, coils, darts, etc.(00411 FIG. 3 is a side view of another pacing device 300 configured in accordance with embodiments of the present technology. The device 300 is configured to be implanted within a chamber of a heart of a patient to monitor activity of the heart and / or to provide electrical therapy to the heart. In the embodiment shown in FIG. 3, the device 300 includes a housing 302, a plurality of fixation tines 304, a first electrode 306a, and a second electrode 306b.

[0042] The housing 302 can have a size and form factor that allows the device 300 to be entirely implanted within a chamber of a heart of a patient. For example, as shown in FIG. 3, the housing 302 has a generally cylindrical (e.g., pill-shaped or capsule-shaped), elongate form factor extending between a distal end 308 and a proximal end 310. The housing 302 contains electronic components of the device 300, and can be hermetically or near-hermetically sealed to prevent fluid ingress into the housing 302. The materials used to form the housing 302 can include any of the conductive and nonconductive materials described above with respect to FIG. 2.

[0043] The device 300 can include a fixation mechanism configured to fix the device 300 to cardiac tissue at a target implant region (e.g., the endocardial wall near the apex of the RV). In the illustrated embodiment, the device 300 includes a plurality of fixation tines 304 extending from the distal end 308 of the housing 302 and configured to engage with cardiac tissue to secure the housing 302 at a fixed position within the chamber of the heart. The fixation tines 304 can be configured to anchor the housing 302 to the cardiac tissue such that the device 300 moves along with the cardiac tissue during cardiac contractions. The device 300 can include any suitable number of fixation tines 304, such as one, two, three, four, five, or more fixation tines 304. The fixation tines 304 can be fabricated from any suitable material, such as a shape memory material (e.g., Nitinol). Alternatively or incombination, the device 300 can be fixed to cardiac tissue using other types of fixation mechanisms, such as, but not limited to, barbs, coils, darts, and the like.

[0044] Optionally, the device 300 can include an attachment mechanism configured to temporarily couple the device 300 to a delivery tool, e.g., for delivery and / or extraction of the device 300. In the illustrated embodiment, for example, the proximal end 310 includes a flange 318 that defines an opening. The flange 318 can be attached to a tether (e.g., by threading the tether through the opening) that extends through an elongate shaft (e.g., a catheter) to implant or extract the device 300.

[0045] In some embodiments, the device 300 is configured to sense electrical activity of the heart and / or deliver electrical stimulation to the heart via the first electrode 306a and second electrode 306b (collectively, “electrodes 306”). The first electrode 306a can serve as a cathode configured to electrically contact cardiac tissue and deliver pacing pulses thereto, and the second electrode 306b can serve as an anode and / or a return electrode. Optionally, the device 300 can be equipped with multiple cathode electrodes. Such multiple cathode electrodes can be configured to electrically contact and deliver pacing pulses to cardiac tissue of a single heart chamber, or cardiac tissue of multiple heart chambers. In some such embodiments, the multiple cathode electrodes are configured to electrically contact and deliver pacing pulses to cardiac tissue of different heart chambers. For example, one cathode electrode can be configured to electrically contact and deliver pacing pulses to atrial tissue, and another cathode electrode may be configured to electrically contact and deliver pacing pulses to ventricular tissue.

[0046] The electrodes 306 can be configured in many different ways. For example, one or both of the electrodes 306 can be discrete components that are mechanically coupled to the housing 302. As another example, one or both of the electrodes 306 can be defined by an outer portion of the housing 302 that is electrically conductive. The electrodes 306 can be electrically isolated from each other. In some embodiments, a portion of the housing 302 is covered by or formed from an insulative material to isolate the electrodes 306 from each other and / or to provide a desired size and shape for one or both of the electrodes 306. The electrodes 306 can be electrically coupled to at least some of the internal electronic components of the device 300 within the housing 302 (e.g., sensing circuitry, electrical stimulation circuitry, or both).[00471 In the illustrated embodiment, the first electrode 306a is located at the distal end 308 of the housing 302. The first electrode 306a may be referred to as a tip electrode, and the fixation tines 304 can be configured to anchor the device 300 to cardiac tissue such that the first electrode 306a maintains contact with the cardiac tissue. In some examples, the housing 302 includes an end cap 312 at the distal end 308, and the end cap 312 includes a feedthrough assembly to electrically couple the first electrode 306a to the electronics within the housing 302, while electrically isolating the first electrode 306a from the remaining portions of the housing 302, e.g., including the second electrode 306b and / or other conductive portions of the housing 302[0048| The second electrode 306b can be located on the housing 302 away from (e.g., proximal to) the first electrode 306a. As shown in FIG. 3, the housing 302 includes a first portion 314 and a second portion 316, with the first portion 314 being located proximal to the end cap 312, and the second portion 316 being located proximal to the first portion 314. The second portion 316 can optionally define at least part of a power source case that houses a power source (e.g., a battery) of the pacing device 300. In some embodiments, the second electrode 306b is located on the second portion 316, while in other embodiments, the second electrode 306b is located on the first portion 314.

[0049] In some embodiments, the second electrode 306b is a conductive portion of the housing 302 (e.g., an annular portion of the housing 302 that is made partially or entirely from a conductive material). Additionally or alternatively, the second electrode 306b can be a conductive material that is coated onto the material of the housing 302, or a discrete component (e.g., a ring electrode) that is coupled to the housing 302. The remaining portions of the housing 302 can include or be coated with an insulative material so that the second electrode 306b is electrically isolated from the rest of the housing 302 and / or from the first electrodes 306a.

[0050] FIG. 4 is a schematic block diagram illustrating electronic components of a pacing device 400 configured in accordance with embodiments of the present technology. Any of the electronic components shown in FIG. 4 can be incorporated into any of the embodiments of implantable devices described herein, such as the device 100 of FIG. 1, the device 200 of FIG. 2, or the device 300 of FIG. 3.[00511 As shown in FIG. 4, the device 400 includes a plurality of electrodes 402a- 402c that are electrically coupled to components within a housing 404 of the device 400. Although the device 400 is illustrated and described herein as having three electrodes 402a- 402c (e.g., similar to the device 200 of FIG. 2), in other embodiments, the device 400 can be modified to include a different number of electrodes, such as two electrodes (e.g., similar to the device 300 of FIG. 3) or any other suitable number of electrodes.[0052| At least some of the electrodes 402a-402c can be configured to contact tissue of one or more heart chambers, as described elsewhere herein. For example, as discussed above with respect to FIG. 2, the first electrode 402a can be configured to electrically contact and deliver electrical signals to tissue of a first heart chamber (e.g., ventricular tissue), and the second electrode 402b can be configured to electrically contact and deliver electrical signals to tissue of a second, different heart chamber (e.g., atrial tissue). The third electrode 402c can be an anode and / or return electrode that does not electrically contact heart tissue. Optionally, either the first electrode 402a or the second electrode 402b can be omitted, or the device 400 can include additional electrodes that electrically contact and deliver electrical signals to tissue of a heart chamber (e.g., the first heart chamber, the second heart chamber, or another heart chamber).

[0053] The device 400 includes a plurality of electronic components within the housing 404, such as switch circuitry 406, sensing circuitry 408, therapy generation circuitry 410, one or more sensors 412, processing circuitry 414, communication circuitry 416, memory 418, and / or a power source 420. The various circuitry can be or include programmable or fixed function circuitry configured to perform the operations described herein. One or more of the components of the device 400 shown in FIG. 4 can be part of an electronics assembly. For example, one or more of the switch circuitry 406, sensing circuitry 408, therapy generation circuitry 410, sensor(s) 412, processing circuitry 414, communication circuitry 416, and / or memory 418 can be mounted on a circuit board of an electronics assembly of the device 400.

[0054] The switch circuitry 406 can include one or more switches (e.g., a switch matrix, switch arrays, or other collection of switches), multiplexers, transistors, and / or other electrical circuitry. The switch circuitry 406 can selectively couple one or more of the electrodes 402a-402c to other components of the device 400 (e.g., the sensing circuitry 408and / or the therapy generation circuitry 410). The subset of the electrodes 402a-402c to be used can depend on the particular operation of the device 400 that is being performed, such as whether the device 400 is sensing or delivering therapy, the locations of the heart being monitored or treated, etc. In some embodiments, the processing circuitry 414 determines which subset of the electrodes 402a-402c should be used for a particular operation, and controls the switch circuitry 406 to selectively couple those electrodes to the appropriate components of the device 400.

[0055] The sensing circuitry 408 can monitor signals from at least one of electrodes 402a-402c to monitor electrical activity of the heart, impedance, and / or other electrical phenomena. Sensing can be performed to determine heart rates and / or heart rate variability, and / or to detect ventricular dyssynchrony, arrhythmias (e.g., tachyarrhythmias), and / or other electrical signals. The sensing circuitry 408 can include filters, amplifiers, analog-to- digital converters, and / or other circuitry configured to sense cardiac electrical signals via one or more of the electrodes 402a-402c.

[0056] In some embodiments, the switch circuitry 406 as controlled by the processing circuitry 414 selectively couples the sensing circuitry 408 to selected combinations of the electrodes 402a-402c, e.g., to selectively sense the electrical activity of one or more chambers of the heart. For example, the switch circuitry 406 can couple each of the first electrode 402a and the second electrode 402b (in combination with the third electrode 402c) to respective sensing channels provided by the sensing circuitry 408 to sense electrical signals from the cardiac tissues in electrical contact with the first electrode 402a (e.g., ventricular tissue) and the second electrodes 402b (e.g., atrial tissue), respectively. In some embodiments, the sensing circuitry 408 is configured to detect events, (e.g., depolarizations) within the cardiac electrical signals, and to provide indications thereof to the processing circuitry 414. In this manner, the processing circuitry 414 can determine the timing of atrial and / or ventricular depolarizations, and can control the delivery of cardiac pacing (e.g., AV synchronized cardiac pacing) based thereon.

[0057] The therapy generation circuitry 410 can generate electrical stimulation signals, such as cardiac pacing pulses. The therapy generation circuitry 410 can be electrically coupled to one or more of the electrodes 402a-402c to deliver pulses to a portion of cardiac muscle within the heart via one or more of the electrodes 402a-402c. In someembodiments, the therapy generation circuitry 410 delivers pacing stimulation in the form of electrical pulses. The therapy generation circuitry 410 can include charging circuitry, and one or more charge storage devices (e.g., capacitors). Optionally, the therapy generation circuitry 410 can include switches and / or other circuitry to control when the charge storage devices are discharged to the electrodes 402a-402c.[0 58| The switch circuitry 406 as controlled by the processing circuitry 414 can direct electrical stimulation signals from the therapy generation circuitry 410 to a selected combination of the electrodes 402a-402c having selected polarities, e.g., to selectively deliver pacing pulses to the RA, RV, LV, and / or the interventricular septum of the heart. For example, in order to pace one or both of the ventricles, the switch circuitry 406 can electrically couple the first electrode 402a (e.g., which contacts wall tissue of a ventricle or the intraventricular septum) to the therapy generation circuitry 410 as a cathode, and to one or both of the second electrode 402b or the third electrode 402c to the therapy generation circuitry 410 as an anode. As another example, in order to pace the RA, the switch circuitry 406 can couple the second electrode 402b (e.g., which contacts the RA endocardium) to the therapy generation circuitry 410 as a cathode, and to one or both of the first electrode 402a or the third electrode 402c to the therapy generation circuitry 410 as an anode.

[0059] The processing circuitry 414 can include one or more processors, such as a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or equivalent discrete or analog logic circuitry. In some embodiments, the processing circuitry 414 can include multiple components, such as any combination of one or more microprocessors, controllers, DSPs, ASICs, and / or FPGAs, as well as other discrete or integrated logic circuitry. The functions attributed to the processing circuitry 414 herein may be embodied as software, firmware, hardware, or any combination thereof.

[0060] The processing circuitry 414 can control the therapy generation circuitry 410 to deliver stimulation therapy to a patient’s heart according to therapy parameters, which can be stored in the memory 418. For example, the processing circuitry 414 can control the therapy generation circuitry 410 to deliver electrical pulses with the amplitudes, pulse widths, rates, frequencies, and / or electrode polarities specified by the therapy parameters. In this manner, the therapy generation circuitry 410 can deliver pacing pulses to the heartvia one or more of the electrodes 402a-402c. The device 400 can use any combination of the electrodes 402a-402cto deliver therapy and / or detect electrical signals from the patient.[00611 The memory 418 (e.g., a data storage device or other non-transitory medium) can store computer-readable instructions that, when executed by the processing circuitry 414, cause the device 400 to perform the various operations described herein. The memory 418 can include any volatile, non-volatile, magnetic, optical, or electrical media, such as a random-access memory (RAM), read only memory (ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory, or any other digital or analog media.

[0062] The sensor(s) 412 can include one or more sensing elements that transduce patient physiological activity to an electrical signal to sense values of a respective patient parameter. Sensor(s) 412 can include one or more motion sensors, optical sensors, chemical sensors, temperature sensors, pressure sensors, and / or any other types of sensors. The sensor(s) 412 can output patient parameter values to the processing circuitry 414 that can be used as feedback to control sensing and / or delivery of therapy by the device 400.[0063| For example, the sensor(s) 412 can include at least one motion sensor, such as one or more inertial measurement units (IMUs), accelerometers, gyroscopes, electrical or magnetic field sensors, and / or other devices capable of detecting motion and / or the position of the device 400. The motion of the device 400 detected by the motion sensor may be indicative of cardiac events (e.g., paced activation of the ventricles), blood flow through the heart, patient posture, patient activity, and / or noise. The processing circuitry 414 can control and / or monitor the motion data produced by the motion sensor to identify one or more features of the cardiac contraction within the signal (e.g., on a beat-by-beat basis or otherwise) to facilitate delivery of therapy (e.g., delivery of ventricular pacing pulses in an atrial- synchronized manner). Optionally, the processing circuitry 414 can use the motion data to detect a current activity level of the patient, which can be used for rate-responsive pacing of the patient’s heart.

[0064] The communication circuitry 416 is configured to allow the device 400 to wirelessly communicate with another device, such as a device external to the patient’s body (e.g., the external device 110 of FIG. 1) and / or another device under the control of the processing circuitry 414. For instance, the processing circuitry 414 can receive updates tooperational parameters from the other device, and / or can provide collected data, (e.g., sensed heart activity and / or other patient parameters) to the other device via the communication circuitry 416. The communication circuitry 416 can use radiofrequency (RF) communication techniques (e.g., via an antenna) and / or any other suitable communication modality.

[0065] The power source 420 delivers operating power to various components of the device 400. The power source 420 can include one or more batteries, each of which can independently be rechargeable or non-rechargeable. Recharging of the power source 420 can be accomplished through proximal inductive interaction between an external charger and an inductive charging coil within the device 400. Alternatively or in combination, recharging of the power source 420 can be accomplished using an energy harvesting mechanism 422 of the device 400. Additional details of energy harvesting mechanisms and associated methods are provided in Section II below.

[0066] The components of the device 400 illustrated in FIG. 4 can be modified in many different ways. For example, any of the components shown in FIG. 4 can be combined with each other, e.g., the switch circuitry 406 can be incorporated into the sensing circuitry 408 and / or the therapy generation circuitry 410. Any of the components shown in FIG. 4 can be divided into smaller subcomponents. Some of the components in FIG. 4 are optional and may be omitted (e.g., the switch circuitry 406 and / or sensor(s) 412). The device 400 can also include additional components not shown in FIG. 4. For example, the device 400 can include power management circuitry coupled to the power source 420 to allow the processing circuitry 414 to monitor the status of the power source 420 (e.g., charge level, charging rate, net power into and / or out of the power source 420, remaining battery life).

[0067] The components of the device 400 shown in FIG. 4 represent functionality that can be included in any of the devices of the present technology. The components illustrated in FIG. 4 can include any discrete and / or integrated electronic circuit components that implement analog and / or digital circuits capable of producing the functions attributed to the components herein. For example, the components can include analog circuits, such as amplification circuits, filtering circuits, and / or other signal conditioning circuits. The components can also include digital circuits, such as combinational or sequential logic circuits, memory devices, and the like. The functions attributed to the components of FIG.4 may be embodied as one or more processors, hardware, firmware, software, or any combination thereof. The depiction of different features as separate blocks in FIG. 4 is intended to highlight different functional aspects, and does not necessarily imply that such components must be realized by separate hardware or software components. Rather, functionality associated with one or more components may be performed by separate hardware or software components, or integrated within common or separate hardware or software components. For example, although illustrated as separate functional components in FIG. 4, some or all of the functionality attributed to the switch circuitry 406, sensing circuitry 408, therapy generation circuitry 410, sensor(s) 412, and / or communication circuitry 416 can alternatively or additionally be implemented by the processing circuitry 414, or vice-versa.]0068[ In some embodiments, the present technology provides implantable devices that include an energy harvesting mechanism (also known as an “energy harvester” or “harvester”). The power capacity of a power source of an implantable device may be limited due to size constraints, such as if the device is implanted within a small space within the patient’s body (e.g., within a single heart chamber) and / or to avoid the device interfering with normal physiological function, as well as safety considerations. To prolong the usable life of such implantable devices, an energy harvesting mechanism can be used to generate energy in situ to recharge the power source.

[0069] FIG. 5 is a side cross-sectional view of a device 500 including an energy harvesting mechanism 502, in accordance with embodiments of the present technology. The device 500 can be an implantable device, such as a pacing device configured to monitor activity of a patient’s heart and provide electrical stimulation to the heart. In such embodiments, the device 500 can include any of the features of the devices described above in connection with FIGS. 1-4 (e.g., electrodes, fixation mechanism, circuitry, and / or other electronic components). In other embodiments, however, the device 500 can be a different type of implantable medical device.

[0070] The device 500 includes a housing 504 having an elongate shape extending between distal end 508 and a proximal end 510. The housing 504 defines an interior cavity 506 containing the energy harvesting mechanism 502 and other components of the device 500, such as a power source 512, power conditioning circuitry 514, and an electronicsassembly 516. When the device 500 is implanted in a patient’s body, the energy harvesting mechanism 502 generates energy from physiological motion. For example, in some embodiments, the device 500 is configured to be implanted within a heart chamber of the patient and generates energy from cardiac motion (e.g., motion of the heart wall to which the device 500 is affixed) and / or blood flow through the heart chamber. The energy produced by the energy harvesting mechanism 502 can be used to charge the power source 512, which in turn powers the operation of the device 500.

[0071] In some embodiments, the energy harvesting mechanism 502 includes a piezoelectric element 518 that converts mechanical energy into electrical energy via the piezoelectric effect. The piezoelectric element 518 can be or include a flexible elongate member (e.g., beam, plate, shaft, rod, fiber) made partially or entirely out of a piezoelectric material, such as a piezoelectric ceramic (e.g., lead zirconate titanate (PZT)), a single crystal piezoelectric material (e.g., lead magnesium niobate-lead titanate (PMN-PT)), a piezoelectric polymer (e.g., polyvinylidene difluoride (PVDF)), or a piezoelectric composite (e.g., a piezoelectric ceramic embedded in a polymer matrix, such as a macro fiber composite). The piezoelectric element 518 can be in a cantilever configuration in which a first end 522 of the piezoelectric element 518 is fixed relative to the housing 504, and a second end 524 of the piezoelectric element 518 opposite the first end 522 is movable relative to the housing 504. In the illustrated embodiment, the first end 522 of the piezoelectric element 518 is located near the distal end 508 of the housing 504, the second end 524 of the piezoelectric element 518 is located near the proximal end 510 of the housing 504, and the longitudinal axis of the piezoelectric element 518 is aligned with (e.g., parallel to) the longitudinal axis of the housing 504. In other embodiments, however, the piezoelectric element 518 can be oriented differently with respect to the housing 504. Additionally, the energy harvesting mechanism 502 can optionally include multiple piezoelectric elements 518.

[0072] In some embodiments, the second end 524 of the piezoelectric element 518 is coupled to a harvester mass 520 (also known as a “proof mass” or “inertial mass”). Due to the inertia of the harvester mass 520, when the device 500 is subjected to external forces from physiological motion, the harvester mass 520 can cause displacement of the second end 524 of the piezoelectric element 518 relative to the housing 504 and the fixed first end 522 of the piezoelectric element 518, and thus cause elastic deformation of the piezoelectricelement 518. For instance, the piezoelectric element 518 can be deformed from a resting, straightened configuration (shown in FIG. 5) to a bent configuration (e.g., an upwardly bent configuration or a downwardly bent configuration). The resulting mechanical strain in the piezoelectric element 518 can produce an electrical current that can be used to charge the power source 512.[0073| The power source 512 can include one or more rechargeable batteries that are electrically coupled to the energy harvesting mechanism 502 to store the energy produced by the energy harvesting mechanism 502. In the illustrated embodiment, the power source 512 is configured as a tubular structure that surrounds at least a portion of the energy harvesting mechanism 502 (e.g., an intermediate portion of the piezoelectric element 518 between the distal end 508 and the proximal end 510). This configuration can be advantageous for reducing the overall size of the device 500 while maintaining sufficient space within the interior cavity 506 to allow for movement of the harvester mass 520 and piezoelectric element 518. In other embodiments, however, the power source 512 can have a different shape and / or can be located at a different portion within the housing 504.[0074} In some embodiments, the device 500 includes power conditioning circuitry 514 electrically coupled to and interposed between the energy harvesting mechanism 502 and the power source 512. The power conditioning circuitry 514 can be configured to perform operations such as rectification, filtering, voltage regulation, etc., of the electrical signal produced by the energy harvesting mechanism 502, before transmission to the power source 512.

[0075] The power source 512 is electrically coupled to the electronics assembly 516 to power the operation thereof. The electronics assembly 516 can include the electronic components of the device 500, such as any of the components described above with respect to FIG. 4 (e.g., switch circuitry 406, sensing circuitry 408, therapy generation circuitry 410, sensors 412 processing circuitry 414, communication circuitry 416, and / or memory 418). Optionally, the electronics assembly 516 can include components (e.g., processing circuitry 414 and / or other circuitry) that perform power management functions, such as monitoring the status of the power source 512 (e.g., the charge level of the power source 512; whether the charge level is increasing, decreasing, or constant; the net current and / or power into the power source 512) and / or monitoring the power output of the energy harvesting mechanism502 (e.g., amount of current and / or power produced by the energy harvesting mechanism 502), power consumption of the electronics assembly 516, etc.II. Energy Management for Implantable Devices

[0076] In some embodiments, the present technology provides methods, systems, and devices for managing energy in an implantable device, such as any of the devices described in Section I above. Energy management in implantable devices may be beneficial or essential for maintaining device functionalities and / or ensuring continuing therapeutic delivery. Energy management can include an ongoing assessment of energy input (e.g., energy produced) by and / or energy output (e.g., energy consumed) by the device, and may involve the application of corrections, optimizations, and / or reallocations of energy usage when desirable. In certain types of implantable devices such as leadless pacemakers (e.g., as described in connection with FIGS. 1-5 above), energy management may be especially important due to size constraints of internal power sources (e.g., batteries). For instance, a leadless pacemaker placed in a chamber of the heart of a patient generally has a limited occupiable internal volume. As a result, the power source may be relatively small, which can reduce the longevity of the leadless pacemaker. Energy management can help ensure the proper functioning of the leadless pacemaker by evaluating and optimizing the internal distribution of energy. Further, as described herein, energy management can address situations in which implantable devices experience low energy.[00771 In embodiments where the implantable device includes an energy harvesting mechanism (e.g., the energy harvesting mechanism 502 of FIG. 5), energy management may be important or necessary to ensure that fluctuations in the energy produced by the energy harvesting mechanism do not significantly affect important device functions. For instance, in embodiments where the energy harvesting mechanism uses mechanical energy from cardiac motion to produce energy, disruptions to the cardiac motion (e.g., abnormal cardiac rhythms) can impact the energy output and / or energy harvesting efficiency of the energy harvesting mechanism. For example, changes in cardiac conduction pathways and / or hormone signaling can result in altered contractility of the patient’s atria and / or ventricles. Atrial fibrillation, characterized by irregular beating in the atria, can affect the heart’s rhythm, reduce blood flow to the ventricles, and impede contractions of the heart’schambers, thereby reducing mechanical energy available to the energy harvesting mechanism.

[0078] FIGS. 6A-6D are illustrative graphs of cardiac motion with a normal cardiac rhythm at 77 BPM and during atrial fibrillation at 77 BPM. Specifically, FIG. 6A shows time domain acceleration waveforms in a first direction, FIG. 6B shows time domain acceleration waveforms in a second direction, FIG. 6C shows time domain acceleration waveforms in a third direction, and FIG. 6D shows acceleration frequency spectra. The data shown in FIGS. 6A-6D were generated by an electromechanical finite element model of a four-chamber human heart, and the data in FIGS. 6A-6C were collected simultaneously.[00791 Overall cardiac motion may be reduced during atrial fibrillation compared to a normal cardiac rhythm. As shown in FIG. 6A, trace 602 corresponds to the acceleration in the first direction with atrial fibrillation, and trace 603 corresponds to the acceleration in the first direction with a normal cardiac rhythm. Trace 602 has a lower amplitude profile than trace 603, with a notably smaller peak-to-peak amplitude. The lower amplitude profile of trace 602 can indicate reduced contractions and / or contractility strength during atrial fibrillation. Similarly, as shown in FIG. 6B, trace 604 (with atrial fibrillation) has a lower acceleration variability than trace 605 (with a normal cardiac rhythm). As shown in FIG. 6C, trace 606 (with atrial fibrillation) has a lower amplitude profile and variability than trace 607 (with a normal cardiac rhythm). As shown in FIG. 6D, trace 620 (with atrial fibrillation) shows a diminished magnitude of frequency content across all frequency ranges compared to trace 630 (with a normal cardiac rhythm).

[0080] Reductions in cardiac motion, e.g., as demonstrated with the atrial fibrillation traces 602, 604, 606, and 620 of FIGS. 6A-6D, can directly decrease the amount of energy produced by the energy harvesting mechanism. For example, in embodiments where the energy harvesting mechanism is a mechanical-to-electrical transducer (e.g., a piezoelectric harvester), the energy harvesting mechanism may have less mechanical energy to convert during atrial fibrillation, thus resulting in lower energy production. However, the energy demands of the implantable device may be higher during atrial fibrillation, e.g., to provide pacing signals to restore a normal cardiac rhythm.[0081 [ Other examples of heart conditions that may affect the energy produced by an energy harvesting mechanism are structural heart diseases, which include defects in thevasculature; vascular diseases, which include obstructions to blood flow; and acute cardiac events, which include temporary disruptions in blood flow. Extrinsic factors, such as a patient’s activity level, cognitive state, sleep behavior, environment, and more can also impact the energy production of the energy harvesting mechanism. For example, a patient may experience reduced cardiac motion when in a state of low physical activity, resulting in decreased energy production from the energy harvesting mechanism.|0082[ While the factors affecting the energy harvesting mechanism have been discussed herein with reference to a patient’s physiology or current state, it should be understood that other factors may affect the energy harvesting mechanism, such as different pre-set modes of the implantable device, device life cycle, device functions, and / or the configuration of the implanted device. For example, energy harvesting efficiency may be lower if the energy harvesting mechanism is poorly aligned with respect to the direction of motion of the heart (e.g., energy harvesting efficiency may be lower if the energy harvesting mechanism is oriented on the same axis as the direction of motion of FIG. 6B, which has a lower acceleration amplitude, compared to if the energy harvesting mechanism is aligned with the direction of motion of FIG. 6 A or FIG. 6C, which have higher acceleration amplitudes).

[0083] To address these and other challenges, the present technology provides methods, systems, and devices for managing energy in an implantable device by adjusting the functions that are performed by the device. In some embodiments, the implantable device is configured to detect factors that affect the energy supply and energy demand of the device, and to prioritize certain device functions over other device functions to conserve the available energy. The device functions that are prioritized may be functions that are important or necessary to ensure that the device operates properly and / or to maintain patient health. For example, in embodiments where the implantable device is a pacing device, device functions that are important or necessary for delivering life-sustaining pacing therapy may be prioritized over other device functions (e.g., functions for maintaining quality of life, communication with other devices).

[0084] FIG. 7 is a flow diagram illustrating a method 700 for managing energy in an implantable device, in accordance with embodiments of the present technology. The method 700 can be performed using any of the systems and devices described herein, suchas any of the devices of FIGS. 1-5. In some embodiments, some or all of the processes of the method 700 are implemented as computer-readable instructions (e.g., program code) that are configured to be executed by one or more processors (e.g., processing circuitry 414 of the device 400 of FIG. 4).

[0085] The method 700 can begin at block 710 with detecting an energy deficit in an implantable device. An energy deficit can be present when the implantable device lacks sufficient energy or is at risk of running out of energy to power some or all of the functions performed by the implantable device. In some embodiments, the implantable device includes a power source (e.g., the power source 410 of FIG. 4) that outputs energy to power one or more device functions, and an energy deficit exists if the existing energy stored in the power source and / or the energy input into the power source are insufficient or may become insufficient to power some or all of the device functions. The energy input into the power source may be provided by an energy harvesting mechanism (e.g., the energy harvesting mechanism 502 of FIG. 5). The energy harvesting mechanism can be configured to generate electrical energy from physiological motion. For example, when the energy harvesting mechanism is implanted in the heart of a patient, the energy harvesting mechanism can convert cardiac motion into electrical energy. However, the energy input provided by the energy harvesting mechanism may be insufficient in certain situations, e.g., due to atrial fibrillation and / or other conditions as described above.

[0086] In some embodiments, detecting the energy deficit includes comparing the energy input to the power source and the energy output from the power source. The energy input and output can be measured, for example, by measuring the current into and out of the power source over time, respectively (e.g., using a Coulomb counter). The implantable device can be considered to have an energy deficit when the energy input is less than the energy output (e.g., the amount of energy produced by the energy harvesting mechanism is less than the amount of energy used to power the functions of the implantable device). Alternatively, or in combination, an energy deficit can occur when the energy input is greater than the energy output, but the energy input is decreasing and / or the energy output is increasing (e.g., the energy input is projected to be less than the energy output at a future time, such as within 15 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 8 hours, 12 hours, or 24 hours). In some embodiments, an energy deficit occurs when the energy input is zero, e.g., there is no energy being produced by the energy harvesting mechanism. Additionally,or alternatively, an energy deficit can occur when an energy level (e.g., charge level) of the power source is below a pre-determined threshold. For instance, an energy deficit can occur when the energy level (e.g., charge level) of the power source is below 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10% or 5% of its total charge capacity. In some embodiments, the implantable device is considered to have an energy deficit if the energy input is less than the energy output, and the energy level of the power source is below the pre-determined threshold.

[0087] At block 720, the method 700 can continue with selecting one or more device functions of a plurality of device functions to deactivate based on a prioritization scheme. The device functions can include any functions performed by the implantable device, including therapeutic functions (e.g., delivery of electrical stimulation to the patient such as pacing signals, sensing physiological conditions of the patient) as well as non-therapeutic functions (e.g., data processing, monitoring device status, communicating with other devices). For instance, in embodiments where the implantable device is a pacing device (e.g., as described above in connection with FIGS. 1-5), the device functions can include one or more pacing functions, sensing functions, diagnostic functions, rate response functions, safety margin functions, and / or telemetry functions. Additional details and examples of the device functions will be discussed in greater detail with reference to FIG. 9 herein.

[0088] The one or more device functions may be selected in any arrangement, as further discussed herein. In some embodiments, a single device function is selected, while in other embodiments, multiple device functions are selected (e.g., two, three, four, five, or more device functions). In embodiments where multiple device functions are selected, the device functions may be of the same type or category, or may be of different types or categories. For example, selecting the one or more device functions can include selecting a pacing function, a first pacing function and a second pacing function, a pacing function and a sensing function, or all device functions at once.

[0089] In some embodiments, the device functions can be categorized by importance for patient health. For example, device functions can be categorized as necessary for patient health (e.g., life-sustaining functions that are expected to cause significant harm to patient health if deactivated), relevant for patient health (e.g., functions that are expectedto provide a beneficial effect on patient health), or not relevant for patient health (e.g., functions that are not expected to have a significant impact on patient health). For instance, in embodiments where the implantable device is a pacing device (e.g., as described above in connection with FIGS. 1-5), pacing functions can be categorized as necessary for patient health, rate response functions can be categorized as relevant for patient health, and diagnostic functions relating to the status of the power source can be categorized as not relevant for patient health. In some embodiments, placement of the device functions into patient health categories can be pre-determined by a manufacturer of the implantable device and / or healthcare provider. Further, the patient health categories of any of the device functions may change over time while the device remains in operation. For example, when a condition of the patient changes, a device function that was previously categorized as not relevant for patient health can become a device function that is categorized as relevant or necessary for patient health. Such changes may be triggered automatically (e.g., based on pre-programmed rules), based on user input (e.g., instructions from a healthcare provider), or suitable combinations thereof.[00901 Alternatively, or in addition, the device functions can be categorized by importance for device operation. For example, device functions can be categorized as necessary for device operation (e.g., integral functions that may result in device failure if deactivated), relevant for device operation (e.g., functions that are expected to improve device performance), or not relevant for device operation (e.g., functions that are not expected to impact device performance). For instance, in embodiments where the implantable device is a pacing device (e.g., as described above in connection with FIGS. 1- 5), energy harvesting functions can be categorized as necessary for device operation, telemetry functions can be categorized as relevant for device operation, and safety margin functions can be categorized as not relevant for device operation. In some embodiments, placement of the device functions into device operation categories can be pre-determined by a manufacturer of the implantable device and / or healthcare provider. Further, any of the device functions can shift device operation categories while the device remains in operation. For example, changing device conditions (e.g., longevity) can necessitate adjustments to the device operation categorization. Such changes may be triggered automatically (e.g., based on pre-programmed rules), based on user input (e.g., instructions from a healthcare provider), or suitable combinations thereof.[00911 The prioritization scheme can be any pre-determined selection mechanism (e.g., an ordered / ranked list, set of categories, lookup table, decision tree, software algorithm) that indicates how the device functions are to be prioritized (e.g., which device functions should be deactivated versus which device functions should remain active) in the event of an energy deficit. The prioritization scheme can be stored onboard the implantable device (e.g., in a memory such as memory 418 of device 400 of FIG. 4) and / or be received from an external source (e.g., using communications circuitry such as communications circuitry 416 of device 400 of FIG. 4). In some embodiments, the prioritization scheme includes or represents an ordered ranking of the device functions. For example, device functions that are lower in importance (e.g., to patient health and / or device operation) can be lower in the prioritization scheme, while device functions that are higher in importance (e.g., to patient health and / or device operation) can be higher in the prioritization scheme. When selecting the one or more device functions to deactivate, device functions lower in the prioritization scheme may be selected before device functions higher in the prioritization scheme. For instance, in some embodiments where safety margin functions are less important than pacing functions, the safety margin functions can be lower in the prioritization scheme than the pacing functions and thus can be deactivated before the pacing functions. In some embodiments, not all device functions performed by the implantable device are included in the prioritization scheme. For example, an essential device function (e.g., a device function that cannot be modified) may be omitted from the prioritization scheme. In such cases, the essential device function can be configured to be constitutively active. In other embodiments, the essential device function can be included in the prioritization scheme (e.g., having a high ranking) while being constitutively active.|0092| In some embodiments, the importance of some or all of the device functions is determined based on their relative importance to patient health, which may be based on the categories of relevance to patient health discussed herein (e.g., necessary for patient health, relevant for patient health, or not relevant for patient health). This approach may be beneficial to ensure that the patient’ s health is not significantly affected if an energy deficit occurs. For instance, a first device function that is categorized as necessary for patient health can be ranked higher than a second device function that is categorized as relevant for patient health, and the second device function can be ranked higher than a third device function that is categorized as not relevant for patient health. In some embodiments, the ranking is anordinal ranking. For instance, the first device function can be ranked in position one, the second device function can be ranked in position two, the third device function can be ranked in position three, a fourth device function can be ranked in position four, and so on and so forth.[00931 Additionally, or in combination, the importance of some or all of the device functions can be determined based on their relative importance to device operation, which may be based on the categories of relevance to device operation described herein (e.g., necessary for device operation, relevant for device operation, or not relevant for device operation). This approach may be beneficial to ensure that the implantable device is still able to function properly if an energy deficit occurs. The ranking of the device functions with reference to device operation can be generally similar to the ranking of the device functions with reference to patient health. For example, the device functions can be ranked ordinally or categorically, based on relative importance to device operation.

[0094] In some embodiments, the importance of the device functions is determined by a combination of factors, such as relative importance to patient health and relative importance to device operation. For example, at least one of the device functions can be ranked by both relative importance to patient health and relative importance to device operation. In some embodiments, a first set of device functions can be ranked by relative importance to patient health and a second set of device functions can be ranked by relative importance to device operation. The first set of device functions can be ranked higher than the second set of device functions, or vice-versa.

[0095] While the importance of the device functions has been discussed with reference to patient health and device operation, many other factors can alternatively or additionally be considered in the prioritization scheme. In some embodiments, the prioritization scheme may consider energy consumption of one or more device functions (e.g., the amount of energy output from the power source that is used to power the device functions). This approach may be beneficial to mitigate or resolve the energy deficit, e.g., by prioritizing device functions that consume less energy over device functions that consume more energy. For example, in some embodiments, a sensing function can have a higher energy consumption than a diagnostic function, and the prioritization scheme may include the sensing function at a lower priority than the diagnostic function. In someembodiments, it may be beneficial to evaluate both the relative importance of the one or more device functions and an associated energy consumption of the one or more device functions. For example, in such cases where a first device function and a second device function are equally important, but the first device function has a higher energy consumption than the second device function, the prioritization scheme may place the second device function at a higher priority.|0096| Alternatively, or in addition, the prioritization scheme may consider an energy consumption profile associated with the one or more device functions. The energy consumption profile can include time-varying information of the energy consumption of the one or more device functions. For example, an energy consumption profile associated with a telemetry function may indicate a high initial energy consumption (e.g., when communicating with a programmer), and a thereafter low energy consumption (e.g., when idle). In some embodiments, the telemetry function may be placed lower in priority than a diagnostic function which has a low initial energy consumption but a thereafter high energy consumption (e.g., constitutively active), or vice-versa. In other embodiments, however, device functions that are necessary or important to patient health and / or device operation may be prioritized regardless of their energy consumption. For instance, pacing functions typically consume large amounts of energy but may nevertheless be high in the prioritization scheme.[0097| The prioritization scheme can be a dynamic scheme that may change over time. For example, the prioritization scheme can include a first ordering of the one or more device functions for a first period of time, and include a second ordering of the one or more device functions for a second period of time different than the first period of time. In some embodiments, the prioritization scheme transitions from the first ordering to the second ordering in response to a change in patient condition. For example, a temporary cardiac event detected in the patient can cause the transition from the first ordering to the second ordering. Additionally, or alternatively, the prioritization scheme can transition from the first ordering to the second ordering in response to external communications (e.g. via communications circuitry 416 of device 400 of FIG. 4). For example, external instructions from a physician can direct the prioritization scheme to transition from the first ordering to the second ordering. In other embodiments, however, the prioritization scheme may be a static scheme that does not change over time.[0098| Additionally, or in combination, the prioritization scheme can be based on a patient profile (also known as a “user profile”). The patient profile may be pre-determined by a healthcare provider, the patient, or a combination thereof. In some embodiments, the patient profile can be updated by an external device while the device is in operation (e.g., via communications circuitry 416 of device 400 of FIG. 4). The patient profile can include information specific to the patient receiving the implantable device, such as information regarding the patient’s anatomy, physiology, treatment plan (e.g., type of implantable device received by the patient, type of pacing needed), medications, medical history, family medical history, lifestyle factors (e.g., activity level, diet), diagnoses (e.g., cardiac conditions and / or other conditions of the patient), test results, or a combination thereof. In some embodiments, the patient profile can influence the ranking of the relative importance for patient health, relative importance for device operation, or a combination thereof. For example, in some embodiments where a telemetry function is typically ranked higher than a rate response function by default, the patient profile may instead rank the rate response function higher than the telemetry function, e.g., based on the particular patient’s needs and / or preferences.

[0099] In some embodiments, selecting the one or more device functions includes selecting a group of device functions that are intended to be deactivated together. In some embodiments, each device function in the group is associated with the same triggering condition, such as the same level of energy deficit. For example, each device function can be associated with a 5% deficit, 10% deficit, 15% deficit, 20% deficit, 25% deficit, 30% deficit, 35% deficit, 40% deficit, 45% deficit, 50% deficit, 5% surplus, 10% surplus, 15% surplus, 20% surplus, 25% surplus, etc. If a condition associated with a particular group occurs (e.g., a level of energy deficit, a detected cardiac event), all device functions belonging to the particular group can be automatically selected for deactivation. For example, if a telemetry function and a safety margin function are grouped together and each associated with a 5% deficit of energy, the telemetry function and safety margin function can both be deactivated when a 5% deficit is detected. In some embodiments, grouping device functions together can improve energy conservation of the implantable device. In some embodiments where the prioritization scheme includes a patient profile, the patient profile can inform the grouping of the device functions.[0100| At block 730, the method 700 can continue with deactivating the one or more device functions. In some embodiments, deactivating the one or more device functions includes turning off the one or more device functions. Alternatively, or in combination, deactivating the one or more device functions can include transitioning the one or more device functions from a high-power mode to a low-power mode. For example, deactivating the one or more device functions can include transitioning the one or more device functions from 100% power to 50% power, 50% power to 0% power, 100% power to 90% power, 90% power to 80% power, etc. In some embodiments, the deactivation includes changing the frequency (e.g., duty cycle) at which the one or more device functions operate. For example, deactivating the one or more device functions can include limiting an operating time of the one or more device functions to 95%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20% or 10% of its normal operating time.

[0101] At block 740, the method 700 can continue with determining whether the energy deficit is improving. The energy deficit can be considered to be improving (e.g., no longer present) if the implantable device has sufficient energy or is no longer at risk of running out of energy to power some or all of the functions performed by the implantable device. The implantable device can be considered to be improving when the energy output is less than the energy input (e.g., the amount of energy produced by the energy harvesting mechanism is greater than the amount of energy used to power the functions of the implantable device). In some embodiments, the determination includes evaluating whether the energy input to the power source is increasing (e.g., the energy harvesting mechanism is now providing sufficient energy to the power source). Additionally, or alternatively, the determination can include evaluating whether the energy output from the power source is decreasing. The energy deficit can be improving, for example, when the energy output is greater than the energy input, but the energy output is decreasing and / or the energy input is increasing (e.g., the energy output is projected to be less than the energy input at a future time, such as within 15 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 8 hours, 12 hours, or 24 hours). Further, the determination can include evaluating a rate of change of the energy input and / or output. For example, an improvement to the energy deficit can occur when the rate of energy input is increasing, the rate of energy output is decreasing, or a combination thereof. In some embodiments, an improvement to the energy deficit occurs when the difference between the energy input and the energy output is decreasing. In someembodiments, an improvement to the energy deficit occurs when the energy produced by the implantable device is greater than the energy consumed by the implantable device.

[0102] Additionally, or alternatively, the energy deficit can be improving when an energy level (e.g., charge level) of the power source is above a pre-determined threshold. For instance, the energy deficit can be improved (or no longer present) when the energy level (e.g., charge level) of the power source is above 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10% or 5% of its total charge capacity. In some embodiments, the implantable device is no longer considered to have an energy deficit if the energy output is less than the energy input, and the energy level of the power source is above the pre-determined threshold.[0103| If the energy deficit is not improving, the method 700 can continue at block 750 with selecting one or more additional device functions to deactivate based on the prioritization scheme. The process of block 750 may be generally similar to the process of block 720. The one or more additional device functions can include device functions higher on the prioritization scheme. In some embodiments, selecting one or more additional device functions includes selecting device functions that were not previously deactivated in block 730. In some embodiments, selecting one or more additional device functions includes selecting device functions that were previously deactivated in block 730, alternatively or in addition to device functions that were not previously deactivated. Further, the one or more additional device functions can be related to the one or more device functions that were previously deactivated.

[0104] The method 700 can continue at block 760 with deactivating the one or more additional device functions. The process of block 760 may be generally similar to the process of block 730. In some embodiments, deactivating the one or more additional device functions includes turning off the one or more additional device functions. Alternatively, or in combination, deactivating the one or more additional device functions includes transitioning the one or more additional device functions from a high-power mode to a low- power mode. For example, deactivating the one or more additional device functions can include transitioning the one or more additional device functions from 100% power to 50% power, 50% power to 0% power, 100% power to 90% power, 90% power to 80% power, etc. In some embodiments, the deactivation can include changing the frequency (e.g., dutycycle) at which the one or more additional device functions operate. For example, deactivating the one or more additional device functions can include limiting an operating time of the one or more additional device functions to 95%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20% or 10% of its normal operating time. In some embodiments, the processes of blocks 740, 750, and 760 are repeated so that additional device functions are sequentially deactivated until the energy deficit improves.[0105| If the energy deficit is improving, the method 700 can continue at block 770 with selecting one or more deactivated device functions to activate based on the prioritization scheme. Activation can include turning the one or more deactivated device functions on, transitioning the one or more deactivated device functions from a low-power mode to a high-power mode, changing a duty cycle of the one or more device functions, or a combination thereof. In some embodiments, selecting the one or more deactivated device functions follows the prioritization scheme such that higher priority deactivated device functions are activated before lower priority deactivated device functions are activated (e.g., device functions that are more important to patient health and / or device operation are activated before device functions that are less important to patient health and / or device operation). In some embodiments, the one or more deactivated device functions that are selected in block 770 include all of the device functions that were previously deactivated in blocks 730 and / or 760, while in other embodiments, the one or more deactivated device functions selected in block 770 may include only a subset (e.g., pre-determined group or category) of the previously deactivated device functions. In some embodiments, the one or more deactivated device functions include at least one of the one or more previously deactivated device functions.[01061 The method 700 can continue at block 780 with activating the one or more deactivated device functions that were selected in block 770. In some embodiments, activating the one or more deactivated device functions includes turning on the one or more deactivated device functions. Alternatively, or in combination, activating the one or more deactivated device functions can include transitioning the one or more deactivated device functions from a low-power mode to a high-power mode. For example, activating the one or more deactivated device functions can include transitioning the one or more deactivated device functions from 50% power to 100% power, 0% power to 50% power, 90% power to 100% power, 80% power to 90% power, etc. In some embodiments, the activation includeschanging the frequency (e.g., duty cycle) at which the one or more deactivated device functions operate. For example, activating the one or more deactivated device functions can include increasing an operating time of the one or more device functions to 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, or 100% of its normal operating time. In some embodiments, the processes of blocks 740, 770, and 780 are repeated so that the device functions are sequentially activated until all the device functions are now restored and / or until an energy deficit is detected.

[0107] The method 700 illustrated in FIG. 7 can be modified in many different ways. For example, the ordering of the processes shown in FIG. 7 can be varied. Some of the processes of the method 700 can be omitted, and / or the method 700 can include additional processes not shown in FIG. 7. In some embodiments, the method 700 can omit the processes of blocks 710, 720, and 730 and instead start at block 740. For example, no initial selection and deactivation of one or more device functions may occur. Further, the method 700 can continue from block 740 to block 760 and include selecting one or more deactivated device functions to activate. In such cases, the one or more deactivated device functions may have been intentionally deactivated by default. The method 700 can generally loop from any succeeding process to a preceding process. For example, the method 700 can loop from block 780 to block 740, from block 780 to block 710, from block 760 to block 740, and / or from block 760 to block 710. Accordingly, some or all of the processes of the method 700 can be repeated to continuously or periodically adjust the device functions to accommodate fluctuations in energy inputs and / or outputs.

[0108] A method for energy management based on a prioritization scheme (e.g., the method 700 of FIG. 7) may be implemented as part of a larger energy management workflow. In such embodiments, the energy management workflow may include other methods for managing energy of an implantable device, such as methods for adjusting the device operation to improve or optimize energy usage. For example, in embodiments where the implantable device is a pacing device (e.g., as described in connection with the devices of FIGS. 1-5), the energy management workflow can implement an energy optimization process to reduce or minimize the energy consumed by the pacing device in providing pacing signals to the patient, even in the absence of a detected energy deficit.[0109| FIG. 8 is a flow diagram illustrating a method 800 for managing energy in an implantable device, in accordance with embodiments of the present technology. The method 800 can be performed in combination with any of the other methods described herein, such as the method 700 of FIG. 7. The method 800 can be performed using any of the systems and devices described herein, such as any of the devices of FIGS. 1-5. In some embodiments, some or all of the processes of the method 800 are implemented as computer- readable instructions (e.g., program code) that are configured to be executed by one or more processors (e.g., processing circuitry 414 of the device 400 of FIG. 4).

[0110] The method 800 can begin at block 802 with measuring an energy input and an energy output of an implantable device. Measuring the energy input (e.g., energy produced) can include evaluating the performance of an energy harvesting mechanism of the implantable device (e.g., an amount and / or rate of energy produced by the energy harvesting mechanism). In some embodiments, measuring the energy input occurs continuously (e.g., has a 100% operating time). In some embodiments, measuring the energy input occurs periodically (e.g., once every 100 milliseconds, 500 milliseconds, 1 second, 5 seconds, 10 seconds, 30 seconds, one minute, 5 minutes, 10 minutes, 20 minutes, 30 minutes, 1 hour, 2 hours, 3 hours, or more). Measuring the energy input can include measuring the current into a power source of the implantable device (e.g., using a Coulomb counter). Additionally or alternatively, measuring the energy input can include measuring an amount of energy produced by the energy harvesting mechanism (e.g., using an internal component of the energy harvesting mechanism).[0.111] Measuring the energy output (e.g., energy consumed) can include evaluating the amount and / or rate of energy output by a power source of the implantable device. In some embodiments, measuring the energy output occurs continuously (e.g., has a 100% operating time). In some embodiments, measuring the energy output occurs periodically (e.g., once every 100 milliseconds, 500 milliseconds, 1 second, 5 seconds, 10 seconds, 30 seconds, one minute, 5 minutes, 10 minutes, 20 minutes, 30 minutes, 1 hour, or more). Measuring the energy output can include measuring the current out of a power source of the implantable device (e.g., using a Coulomb counter). Measuring the energy output can alternatively or additionally include measuring an amount of energy consumed by one or more device functions of the implantable device. For example, measuring the energy output can include aggregating the sum of the energy consumed by the one or more devicefunctions (e.g., using internal circuitry of one or more device components that perform the one or more device functions).

[0112] In some embodiments, the energy input and the energy output are measured simultaneously. Additionally, or alternatively, the energy input may be measured more or less frequently than the energy output. For example, in some embodiments where the energy output is relatively stable, the energy output can be stored onboard the implantable device (e.g., in a memory such as memory 418 of the device 400 of FIG. 4), while the energy input can be measured periodically (e.g., every 30 seconds).

[0113] At block 804, the method 800 can continue with detecting whether an energy deficit is present in the implantable device. The process of block 804 can be generally similar to the process of block 710. In some embodiments, detecting an energy deficit includes comparing the energy input with the energy output. For example, detecting an energy deficit can include comparing the energy input to the power source with the energy output from the power source. An energy deficit can occur when the energy input to the power source is less than the energy output from the power source. In some embodiments, an energy deficit can occur when the energy input is greater than the energy output, but the energy input is decreasing (e.g., the energy input is projected to be less than the energy output at a future time, such as within 15 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 8 hours, 12 hours, or 24 hours). In some embodiments, an energy deficit occurs when the energy input is zero, e.g., there is no energy being produced by the energy harvesting mechanism.

[0114] If an energy deficit is detected, the method 800 can continue at block 806 with determining whether the power source charge level is below a pre-determined threshold. For example, the block 806 can include measuring the charge level of the power source (e.g., using a Coloumb counter) and comparing it to the pre-determined threshold. The pre-determined threshold can be relative to the power source’s total capacity. For example, the pre-determined threshold can be 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10% or 5% of the power source’s total charge capacity. The pre-determined threshold can be automatically set or can be determined by a healthcare provider and / or the patient.[0115| If the power source charge level is below the threshold, the method 800 can continue at block 808 with deactivating the one or more device functions according to a prioritization scheme, e.g., such that lower priority device functions are deactivated before higher priority functions. The process of block 808 can be generally similar to the process of block 730 of FIG. 7. For example, the one or more device functions can be selected from a plurality of device functions. The plurality of device functions can include any functions performed by the implantable device, including therapeutic functions (e.g., delivery of electrical stimulation to the patient such as pacing signals, sensing physiological conditions of the patient) as well as non-therapeutic functions (e.g., data processing, monitoring device status, communicating with other devices). For instance, in embodiments where the implantable device is a pacing device (e.g., as described above in connection with FIGS. 1- 5), the device functions can include one or more pacing functions, sensing functions, diagnostic functions, rate response functions, safety margin functions, and / or telemetry functions.

[0116] In some embodiments, deactivating the one or more device functions according to a prioritization scheme includes deactivating the one or more device functions according to an order of priority of the one or more device functions represented in the prioritization scheme. The prioritization scheme can be identical or generally similar to any prioritization scheme discussed herein (e.g., in connection with FIG. 7 above). A representative example of a prioritization scheme that may be used in connection with block 808 is described below with respect to FIG. 9. Deactivating the one or more device functions can include turning off the one or more device functions, transitioning the one or more device functions from a high-power mode to a low-power mode, and / or adjusting (e.g., decreasing) the duty cycle at which the one or more device functions operate, as described elsewhere herein.

[0117] After the one or more device functions are deactivated, the method 800 can continue at block 810 with outputting a notification. In some embodiments, the notification can be displayed to a healthcare provider and / or the patient (e.g., via a display of an external device, such as the external device 110 of FIG. 1). The notification can include an indication that the one or more device functions have been deactivated, and, optionally, the identity of the deactivated functions and / or the type of deactivation that has occurred (e.g., turning off, changing power mode, and / or reducing duty cycle). Additionally, or alternatively, thenotification can include an indication that a modification to the implantable device has occurred. In some embodiments, outputting a notification includes communicating with an external device. In accordance with any of the embodiments of the present technology, outputting a notification can include an auditory indication, a visual indication, a haptic indication, or a combination thereof.

[0118] Returning now to block 806, if the power source charge level is not below the threshold, the method 800 can continue at block 812 with performing an energy optimization process. The energy optimization process can include any process that reduces or minimizes the energy consumed by the implantable device during operation, such as redistributing available energy between one or more device functions, adjusting one or more device functions to increase the energy produced by and / or energy consumed by the device functions, or a combination thereof. For example, the energy optimization process can include adjusting a pacing signal produced by the implantable device to reduce the energy used to produce the pacing signal. A representative example of an energy optimization process is discussed further below with reference to method 1000 of FIG. 10, and the process of block 812 can employ any of the processes of the method 1000 of FIG. 10.]0119[ Returning now to block 804, if an energy deficit is not detected, the method 800 can continue at block 814 with determining whether the power source is fully charged. The process of block 814 can include determining whether the charge level of the power source is equal to or substantially equally to the total capacity of the power source (e.g., 100% charge level). If the power source is not fully charged, the method 800 can continue at block 816 with charging the power source (e.g., using energy produced by an energy harvesting mechanism).

[0120] If the power source is fully charged, the method 800 can continue at block 818 with determining whether all of the device functions are activated. In some embodiments, determining whether all of the device functions are activated includes detecting whether all of the device functions are turned on. In some embodiments, determining whether all of the device functions are activated includes detecting whether all of the device functions are operating at full capacity (e.g., not in a low-power mode and / or not at a low duty cycle).[01211 If all device functions are not activated, the method 800 can continue at block820 with activating one or more deactivated device functions according to a prioritization scheme, e.g., such that higher priority device functions are activated before lower priority functions. In some embodiments, the prioritization scheme of block 820 can be the same prioritization scheme as block 808 (e.g., the prioritization scheme described with respect to FIG. 9). The process of block 820 can be generally similar to the process of block 780 of method 700 of FIG. 7. In some embodiments, activating the one or more device functions includes activating at least one of one or more deactivated device functions. In some embodiments, activating the one or more device functions includes activating all of the one or more deactivated device functions. Activating the one or more device functions can include turning on the one or more device functions, transitioning the one or more device functions from a low-power mode to a high-power mode, or adjusting the duty cycle (e.g., increasing) at which the one or more device functions operate, as described elsewhere herein.[ 122| After activating the one or more deactivated device functions, the method 800 can continue at block 810 with outputting a notification. In some embodiments, the notification can be displayed to a healthcare provider and / or the patient (e.g., via a display of an external device). The notification can include an indication that the one or more deactivated device functions have been activated and, optionally, the identity of the activated functions and / or the type of activation that has occurred (e.g., turning on, changing power mode, and / or increasing duty cycle). Additionally, or alternatively, the notification can include an indication that a modification to the implantable device has occurred. In some embodiments, outputting a notification includes communicating with an external device. In accordance with any of the embodiments of the present technology, outputting a notification can include an auditory indication, a visual indication, a haptic indication, or a combination thereof.

[0123] Returning now to block 818, if all device functions are activated, the method 800 can continue at block 822 with shunting energy from the power source. Shunting energy from the power source can include discharging the energy. In some embodiments, shunting the energy advantageously prevents the power source from being overcharged, which can lead to decay of the longevity of the battery and / or decrease its total capacity.[0124| The method 800 illustrated in FIG. 8 can be modified in many different ways. For example, the ordering of the processes shown in FIG. 8 can be varied. Some of the processes of the method 800 can be omitted (e.g., one or more of blocks 810, 812, and / or 822), and / or the method 800 can include additional processes not shown in FIG. 8. The method 800 can generally loop from any succeeding process to a preceding process. For example, the method 800 can loop from block 808 to block 802, from block 810 to block 802, from block 812 to block 802, from block 816 to block 802, from block 818 to block 802, from block 820 to block 802, and / or from block 822 to block 802. Accordingly, some or all of the processes of the method 800 can be repeated to continuously or periodically adjust the operation of the implantable device to accommodate fluctuations in energy inputs and / or outputs, as well as to continuously or periodically optimize energy consumption.(0125] FIG. 9 is a schematic representation of a prioritization scheme 910, in accordance with embodiments of the present technology. The prioritization scheme 910 can be used in any of the methods described herein, such as the method 700 of FIG. 7 and / or the method 800 of FIG. 8. Prioritization scheme 910 can include one or more device functions ordered in terms of priority. For example, in the illustrated embodiment, the prioritization scheme 910 can include one or more pacing functions 920, one or more sensing functions 930, one or more diagnostic functions 940, one or more rate response functions 950, one or more safety margin functions 960, and / or one or more telemetry functions 970. In other embodiments, however, one or more of the device functions illustrated in FIG. 9 can be omitted, and / or the prioritization scheme 910 can include additional device functions not shown in FIG. 9. Optionally, the one or more device functions can be a first set of device functions and the prioritization scheme 910 can additionally include a second set of device functions different from the first set of device functions.(0126] Pacing functions 920 can include one or more device functions responsible for delivering pacing therapy to a patient, e.g., by sending electrical stimulation to cardiac tissue via one or more electrodes. For example, pacing functions 920 can include the delivery of a pacing signal including one or more pacing pulses (e.g., by first electrode 306a and second electrode 306b of the device 300 of FIG. 3). The pacing functions 920 can include delivering a pacing signal to a single chamber or to multiple chambers of the patient’s heart, such as any suitable combination of the RA, RV, LA, and / or LV. In some embodiments, a pacing signal of pacing functions 920 includes an atrial pacing signal (e.g.,a left atrial pacing signal, a right atrial pacing signal, or a combination thereof). The atrial pacing signal can be delivered before a p-wave of a cardiac rhythm of the patient. In some embodiments, the atrial pacing signal can inhibit sinus activity of the heart. In some embodiments, pacing of the right atria can be used to prevent atrial tachyarrhythmias. Additionally, or alternatively, pacing functions 920 can include a ventricular pacing signal (e.g., a left ventricular pacing signal, a right ventricular pacing signal, or a combination thereof). The ventricular pacing signal can be delivered to initiate the electrical activation of the heart, e.g., by producing a QRS complex of the cardiac rhythm of the patient. In some embodiments, the ventricular pacing signal can improve synchrony between the left and right ventricles of the heart of the patient. In some embodiments, pacing functions 920 can include both atrial pacing and ventricular pacing (e.g., dual chamber pacing). Optionally, pacing functions 920 can alternatively or additionally include endocardial and / or epicardial delivery of pacing therapy.[0127| Activating and / or deactivating pacing functions 920 can include altering the operation of a pulse generator of the pacing functions 920. In some embodiments, activating and / or deactivating pacing functions 920 includes adjusting one or more parameters of the pacing functions 920, such as the rate, frequency, amplitude, waveform, pulse width, and / or duty cycle of the pacing functions 920. For example, the pacing rate of a pacing signal can be increased by at least 1 BPM, 2 BPM, 5 BPM, 10 BPM, 15 BPM, or 20 BPM. Conversely, the pacing rate of a pacing signal can be decreased by at least 1 BPM, 2 BPM, 5 BPM, 10 BPM, 15 BPM, or 20 BPM. In some embodiments, parameters of the pacing functions 920 can be changed in response to cardiac events detected by sensing functions 930. For example, if the sensing functions 930 indicate that the patient’s intrinsic heart rate is slower than the minimum pacing rate that has been set, a pacing rate of the pacing functions 920 can be reduced.

[0128] In some embodiments, some or all of the pacing functions 920 are necessary for patient health such that they are never turned off completely. In such embodiments, deactivating the pacing functions 920 can include adjusting the one or more parameters of the pacing functions 920 without turning off the pacing functions 920. For instance, if a patient is dependent on ventricular pacing, the ventricular pacing signal may never be turned off completely, but the parameters of the ventricular pacing signal may be adjusted if it is possible to do so without significant detrimental effects on patient health.[ 129| Optionally, some of the pacing functions 920 may be turned off if they are not necessary for patient health. In some embodiments, the pacing functions 920 includes a plurality of pacing signals, and activating / deactivating the pacing functions 920 includes activating / deactivating at least one pacing signal from the plurality of pacing signals, respectively. For instance, pacing functions 920 can include a first pacing signal that is necessary for patient health and a second pacing signal that is not necessary for patient health. Activating / deactivating pacing functions 920 can include activating / deactivating the second pacing signal, respectively, while keeping the first pacing signal activated. In some embodiments where the implantable device is a dual chamber pacemaker, ventricular pacing may be necessary while atrial pacing may be optional, or vice-versa, depending on the patient’s condition (e.g., if the patient has an intact AV node).{0130) Sensing functions 930 can include one or more device functions configured to sense electrical activity of the heart and / or other biomarkers in order to determine the appropriate timing and / or parameters for pacing therapy. For example, sensing functions 930 can include measuring electrical activity of the heart (e.g., via first electrode 306a and second electrode 306b of the device 300 of FIG. 3), e.g., to determine whether a pacing signal should be applied. The sensing functions 930 can include sensing electrical activity of a single chamber or of multiple chambers of the patient’s heart, such as any suitable combination of the RA, RV, LA, and / or LV. Alternatively or in combination, the sensing functions 930 can include sensing mechanical activity of a single chamber or of multiple chambers of the patient’s heart (e.g., using a motion sensor such as an accelerometer and / or a gyroscope). The sensing functions 930 can include one or more of atrial sensing, ventricular sensing, or a combination thereof. In some embodiments, the sensing functions 930 can operate in connection with the pacing functions 920. For example, when a sensing function 930 is configured to detect atrial activity, the sensing function 930 can limit and / or prevent atrial pacing when atrial activity is self-sufficient. Similarly, when a sensing function 930 is configured to detect ventricular activity, the sensing function can limit and / or prevent ventricular pacing when ventricular activity is self-sufficient.{0131 | In some embodiments, deactivating sensing functions 930 includes turning off one or more sensing functions 930. For instance, if a patient always or frequently needs pacing in a particular heart chamber (e.g., pacing percentage is above 50%, 60%, 70%, 80%, 90%, etc.), pacing can occur without sensing. Further, deactivating sensing functions 930can include deactivating sensing functions in one chamber of the heart but not another. For example, if pacing has been turned off in a particular chamber (e.g., atrial pacing is off), a first sensing function in the particular chamber can be turned off while maintaining a second sensing function in a separate chamber (e.g., in a ventricular chamber). Alternatively, or in combination, deactivating sensing functions 930 can include turning off sensing completely, allowing the device to perform asynchronous pacing (pacing without sensing), regardless of pacing percentage. For example, the implantable device may continue to pace the atria without sensing the atria or the ventricles. In some embodiments, activating sensing functions 930 includes reversing the deactivation of the sensing functions 930 as discussed herein.( 132| In some embodiments, deactivating the sensing functions 930 includes decreasing a sampling rate of one or more sensing functions 930, without turning off the sensing functions 930. For example, the sampling rate can be decreased by at least 1 Hz, 2 Hz, 5 Hz, 10 Hz, 15 Hz, or 20 Hz. Conversely, activating the sensing functions 930 can include increasing a sampling rate of one or more sensing functions 930. For instance, the sampling rate can be increased by at least 1 Hz, 2 Hz, 5 Hz, 10 Hz, 15 Hz, or 20 Hz.|0133] Diagnostic functions 940 can include one or more device functions for monitoring conditions relevant to device operation. In some embodiments, at least some of the diagnostic functions 940 are configured to monitor the status of the device, such as whether the components of the device are functioning properly. The device functions 940 can include performing diagnostic tests for one or more electronic components. For example, diagnostic functions 940 can include a diagnostic test for one or more of a switch circuitry (e.g., switch circuitry 406 of device 400 of FIG. 4), sensing circuitry (e.g., sensing circuitry 408 of device 400 of FIG. 4), therapy generation circuitry (e.g., therapy generation circuitry 410 of device 400 of FIG. 4), sensors (e.g., sensors 412 of device 400 of FIG. 4), processing circuitry (e.g., processing circuitry 414 of device 400 of FIG. 4), communication circuitry (e.g., communication circuitry 416 of device 400 of FIG. 4), memory (e.g., memory 418 of device 400 of FIG. 4), and / or a power source (e.g., power source 420 of device 400 of FIG. 4). In some embodiments, the diagnostic test can determine if the electronic components are properly connected. For example, the diagnostic test can determine if the memory is properly connected with the processing circuitry. In some embodiments, the diagnostic test can determine if the electronic components are fully operational or not. Forexample, the diagnostic test may identify issues in the processing circuitry (e.g., delays, computational errors), issues in the memory (e.g., unresolved storage, overloaded RAM), issues in the communication circuitry (e.g., packet loss, high latency), issues in the sensors (e.g., misplacement, signal interference), and / or any other device diagnostic tests well known in the art. Alternatively, or in combination, diagnostic functions 940 may include diagnostic tests not specific to any one electronic component. For example, in some embodiments, the diagnostic functions 940 include diagnosing one or more of physical damage, faulty wiring, temperature imbalances, power surges, and / or manufacturing defects.

[0134] The diagnostic functions 940 can be further configured to resolve issues in the one or more electronic components. For example, the diagnostic functions 940 may include instructions for troubleshooting and / or correcting issues in device hardware and / or software.

[0135] Additionally, or alternatively, the diagnostic functions 940 can include one or more device functions for monitoring conditions relevant to patient health. In some embodiments, at least some of the diagnostic functions 940 are configured to monitor the status of the patient, such as the patient’s current health parameters (e.g., activity level, temperature, blood pressure, heart sounds), and / or whether there are changes in the patient’s health (e.g., onset of a new condition, worsening or improvement of an existing condition). The diagnostic functions 940 can include detecting changes in the patient’s health and / or performing medically relevant tests. For example, the diagnostic functions 940 can include detecting arrhythmias, patterns in cardiac rhythm, heart rate, cardiac contractility, premature contractions (e.g., premature atrial contraction (PAC), premature ventricular contraction (PVC)), heart failure, and / or other markers of cardiac function. In some embodiments, the diagnostic functions 940 include analysis functions for an electrocardiogram collected by one or more sensors. Additionally, or alternatively, the diagnostic functions 940 can include an analysis of success of one or more device functions. For example, the diagnostic functions 940 can be configured to evaluate the performance of pacing functions 920 (e.g., in stimulating cardiac tissue, such as by measuring the atrial mechanical contraction (A3 / A4) amplitude).[0136| The rate response functions 950 can include one or more device functions relevant to monitoring an activity level of the patient and adjusting pacing based on the activity level. For example, rate response functions 950 can include monitoring an amount of activity of a patient using one or more activity sensors (e.g., movement sensors such as an accelerometer, gyroscope, etc.), and determining an appropriate pacing rate based on an activity metric of the patient, such as an activity count indicating the number of times the signal from the activity sensors crosses a threshold during an activity count interval. The activity count can be correlated to the patient’s body motion and / or metabolic demand, and can be used to determine an appropriate pacing rate for the patient’s current activity level. For example, the pacing rate can be determined using a rate-responsive pacing function (also known as a sensor- indicated rate (SIR) function) that identifies the appropriate pacing rate for each of a plurality of different activity counts. The pacing rate set by the rate-responsive pacing function can be used as the pacing rate. Additional details of techniques for rate- responsive pacing are provided in U.S. Patent Application Publication No. 2020 / 0121931, which is incorporated by reference herein in its entirety.J0137] Safety margin functions 960 can include one or more device functions relevant to ensuring the efficacy of the delivered pacing signals, e.g., by maintaining the strength (e.g., voltage) of the pacing signal at a sufficiently high level to avoid ineffective pacing. The safety margin can correspond to the difference between the minimum voltage needed for successful pacing and the actual voltage used in the pacing signal that is delivered to the patient. The safety margin can be represented as a multiplier (e.g., a safety margin of 100% can correspond to 2X the minimum voltage for successful pacing), as a set voltage amount (e.g., a +1V safety margin), or using other suitable techniques. In some embodiments, deactivating the safety margin functions 960 includes reducing the safety margin, e.g., to less than 100%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, or 10%, or even to 0% (no safety margin); and / or to less than 5 V, 2 V, 1.5 V, IV, 0.5 V, or even to 0 V (no safety margin). This approach may be used, for example, in embodiments where it is acceptable to drop some beats or risk dropping some beats during pacing. Conversely, activating the safety margin functions 960 can include increasing the safety margin, e.g., to at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%; and / or to greater than 0.5 V, I V, 1.5 V, 2 V, or 5 V.[ 138[ Telemetry functions 970 can include one or more device functions relevant to communicating with an external device (e.g., an external device associated with a healthcare provider or the patient, such as the external device 110 of FIG. 1). The telemetry functions 970 can include device functions configured to communicate data from the implantable device to the external device (e.g., device and / or patient status information generated by the diagnostics functions 940), and / or to receive data transmitted from the external device to the implantable device (e.g., instructions for device operation). For example, the external device may periodically interrogate the implantable device to provide status updates, transmit instructions from the healthcare provider to update operational parameters, etc. The implantable device may also push information (e.g., device and / or patient status information) to the external device, without waiting for a request from the external device.

[0139] In some embodiments, deactivating the telemetry functions 970 includes reducing the rate at which the implantable device responds to interrogation from the external device, decreasing the amount of data provided in response to interrogation, providing a notification to the external device that the implantable device lacks sufficient power to respond to interrogation, responding only to interrogations for important information (e.g., information necessary for patient health and / or device operation), delaying responses to interrogations, stopping responses altogether, or suitable combinations thereof. Alternatively or in combination, deactivating the telemetry functions 970 can include reducing the rate at which the implantable device pushes data to the external device, decreasing the amount of the data pushes to the external device, providing a notification to the external device that the implantable device lacks sufficient power to push data, only pushing data for important information (e.g., information necessary for patient health and / or device operation), delaying data pushes, stopping data pushes altogether, or suitable combinations thereof. Conversely, activating the telemetry functions 970 can include increasing the rate at which the implantable device responds to interrogation and / or performs data pushes, increasing the amount of data transmitted to the external device, providing a notification to the external device that the implantable device has sufficient power to respond to interrogation and / or to push data, or suitable combinations thereof.

[0140] As depicted in FIG. 9, the device functions in the prioritization scheme 910 can be ranked from high priority to low priority. In the illustrated embodiment, for example,pacing functions 920 are prioritized above sensing functions 930, which are prioritized above diagnostic functions 940, which are prioritized above rate response functions 950, which are prioritized above safety margin functions 960, which are prioritized above telemetry functions 970. In other embodiments, however, some or all of the device functions may be prioritized differently than the order shown in FIG. 9. For example, an alternative prioritization scheme may include the following ranking of device functions (from highest priority to lowest priority): telemetry functions 970, pacing functions 920, safety margin functions 960, sensing functions 930, rate response functions 950, and diagnostics functions 940. As discussed herein, the one or more device functions need not be ranked ordinally. For example, at least two of the one or more device functions may share a priority level. Moreover, individual functions within a particular category may have different priority levels, e.g., pacing functions 920 that are optional for patient health may be ranked the same as sensing functions 930, while pacing functions 920 that are necessary for patient health may be ranked above sensing functions 930.[01411 In some embodiments, the prioritization scheme 910 is based on a patient profile 980. The patient profile 980 can be pre-determined by the patient, healthcare provider, or a combination thereof. The patient profile 980 can include information specific to the patient receiving the implantable device, such as information regarding the patient’ s anatomy, physiology, treatment plan (e.g., type of implantable device received by the patient, type of pacing needed), medications, medical history, family medical history, lifestyle factors (e.g., activity level, diet), diagnoses (e.g., cardiac conditions and / or other conditions of the patient), test results, or a combination thereof. The patient profile 980 can determine the order of the device functions in the prioritization scheme 910. For example, safety margin functions 960 may be ranked higher for a patient who cannot tolerate missed beats. As another example, diagnostic functions 940 and telemetry functions 970 may be ranked higher if the healthcare provider wishes to monitor the patient’s health status more closely. In other embodiments, however, the prioritization scheme 980 may not be based on a patient profile, and may instead be a default prioritization scheme that applies to all patients.[01 2| When an energy deficit is detected in the implantable device but a charge level of a power source of the implantable device is above a pre-determined threshold (as in the process of block 812 of method 800 of FIG. 8), it may be beneficial to perform an energyoptimization process to reduce or minimize the energy consumed by the implantable device. For example, if the implantable device does not require deactivation of one or more device functions, but could benefit from increased energy efficiency, the device may perform an energy optimization process to improve overall energy efficiency.

[0143] FIG. 10 is a flow diagram illustrating a method 1000 for optimizing energy consumption of an implantable device, in accordance with embodiments of the present technology. The method 1000 can be performed in combination with any of the other methods described herein, such as the method 700 of FIG. 7 and / or the method 800 of FIG. 8. For instance, the method 1000 can be performed as part of the process of block 812 of FIG. 8. The method 1000 can be performed using any of the systems and devices described herein, such as any of the devices of FIGS. 1-5. In some embodiments, some or all of the processes of the method 1000 are implemented as computer-readable instructions (e.g., program code) that are configured to be executed by one or more processors (e.g., processing circuitry 414 of the device 400 of FIG. 4).

[0144] The method 1000 can begin at block 1010, with evaluating a pacing capture threshold (PCT). The PCT can be a measurement of the minimum voltage of the pacing signal that is required to activate the heart, e.g., trigger contractions of one or more of the atria and / or ventricles. The PCT can also include the pulse duration (e.g., pulse width) of the pacing signal. The PCT may vary depending on the particular patient’s condition, type and placement of the implantable device, etc. For example, the PCT can be 0.1 V, 0.3 V, 0.5 V, 0.7 V, 0.9 V, 1 V, 1.25 V, 1.5 V, 1.75 V, 2 V, etc., with a duration of 0.1 milliseconds, 0.2 milliseconds, 0.24 milliseconds, 0.3 milliseconds, 0.4 milliseconds, 0.5 milliseconds, 0.6 milliseconds, 0.7 milliseconds, 0.8 milliseconds, 0.9 milliseconds, 1 milliseconds, etc. In some embodiments, the PCT is used to determine the voltage of the pacing signal, e.g., to ensure that the pacing signal is effective, the minimum voltage of the pacing signal can be constrained to be greater than the PCT (e.g., by a safety margin as described elsewhere herein) or at least equal to the PCT. Optionally, a shorter pulse duration can be used with a higher voltage, or a longer pulse duration can be used with a lower voltage.

[0145] At block 1020, the method 1000 can continue with determining whether the PCT can be lowered. Determining whether the PCT can be lowered can include evaluating whether the voltage of the pacing signal can be reduced while still maintaining effectivepacing. In some embodiments, the determination is performed by a series of pacing pulses that decrement voltage and / or pulse duration from a state of successful capture to a loss-of- capture state, or conversely by incrementing from a low voltage and / or pulse duration in which capture fails to higher voltages and / or pulse durations until capture is achieved. Internal circuitry and algorithms may be used to evaluate which pacing pulses result in successful capture leading to conduction of cardiac action potential and contraction of the heart. Memory of prior device functionality and operation can be used to refine the range of power settings evaluated during the pacing capture management session.[0146 In some embodiments, the PCT determination process involves comparing the permanently programmed pacing output to the last measured PCT plus the programmed safety margin. If the permanently programmed pacing voltage exceeds the last measured PCT plus the safety margin, device performance may be optimized by reprogramming the permanent pacing output to be the PCT plus the safety margin. This approach can effectively allow for larger reductions in permanently programmed pacing output, which can reduce energy consumption.(0147J Alternatively or in combination, measurements of PCT at various pulse widths can be obtained, and the pulse width can be dynamically changed to lower the overall energy being used to deliver pacing. In some instances, the implantable device charges up a capacitor if the pacing output is at or above the voltage level of the power source, which may not be energy efficient. It may be possible to avoid charging up the capacitor or to charge up the capacitor with lower energy consuming k-factors by using a PCT at a wider pulse width and a voltage level below the voltage level of the power source.

[0148] If the PCT can be lowered, the method 1000 can continue at block 1030 with adjusting pacing signal strength. The strength of the pacing signal may be correlated to the voltage of the pacing signal, as well as the duration of the pacing pulse. The pacing voltage can be lowered to be equal to the lower PCT determined in block 1020, or to be greater than the lower PCT by a safety margin. For example, the pacing signal voltage can be decreased by 0.1 V, 0.2 V, 0.3 V, 0.4 V, 0.5 V, 0.6 V, 0.7 V, 0.8 V, 0.9 V, 1 V, etc. Adjusting the pacing signal strength can advantageously conserve energy. For example, if the PCT of an implantable device is set at 1.5 V, with a pacing signal delivering a stimulation of 1.6 V, but effective pacing can still be achieved with a lower PCT of 0.5 V, then the pacing signal isdelivering energy in excess, which can unnecessarily deplete the power source of the implantable device.

[0149] If the PCT cannot be lowered, the method 1000 can continue at block 1040 with evaluating other pacing signal parameters 1040, such as a pacing rate 1042, an atrioventricular interval (AVI) 1044, heart rate variability 1046, or a combination thereof. Adjustments to the other pacing signal parameters 1040 may reduce energy consumption of the implantable device, may shift the cardiac motion to be more on resonance with the energy harvesting mechanism to improve energy harvesting efficiency, or a combination thereof.

[0150] In some embodiments where the energy harvesting mechanism depends on cardiac motion, adjustments to the pacing rate 1042 can improve energy efficiency of the implantable device. For example, decreasing the pacing rate 1042 can result in less energy consumption of the implantable device. In some embodiments, changes in the pacing rate 1042 can alter the frequency content of the cardiac motion, which may affect the harvesting efficiency of the energy harvesting mechanism (e.g., harvesting efficiency may increase if the frequency content of the cardiac motion overlaps with the resonant frequency of the energy harvesting mechanism).

[0151] In some embodiments, adjustments to the atrioventricular interval (AVI) 1044 can improve the energy efficiency of the implantable device. For example, there may be a range of AVIs that are determined by the physician and / or by clinical practice standards to be acceptable for patient health that affect device function. If such a range exists, it is also possible that in range changes of the AVI setting could modify the mechanical motion of the heart in a manner that improves or hampers the effectiveness of the energy harvesting apparatus. The AVI could be periodically evaluated to optimize energy harvesting (e.g., harvesting efficiency may increase if changes to the AVI cause the frequency content of the cardiac motion to overlap with the resonant frequency of the energy harvesting mechanism, increasing the AVI can allow the device to wait longer for intrinsic conduction to occur and can lower the overall ventricular pacing burden, etc.).

[0152] In some embodiments, adjustments to the heart rate variability 1046 can improve the energy efficiency of the implantable device. Adjustments to the heart rate variability (e.g, within a clinically acceptable range for patient health) may alter thefrequency content of the cardiac motion, which may affect the harvesting efficiency of the energy harvesting mechanism (e.g., harvesting efficiency may increase if the frequency content of the cardiac motion overlaps with the resonant frequency of the energy harvesting mechanism).

[0153] Subsequently, the method 1000 can continue at block 1050 with adjusting the pacing signal timing, based on the other pacing signal parameters evaluated in block 1040. Adjusting the pacing signal timing can include adjusting one or more of the pacing rate 1042, atrioventricular interval (AVI) 1044, and / or the heart rate variability 1046, e.g., to improve energy harvesting efficiency, in accordance with the embodiments herein and as previously discussed with respect to the processes of block 1040.

[0154] The method 1000 illustrated in FIG. 10 can be modified in many different ways. For example, the ordering of the processes shown in FIG. 10 can be varied. Some of the processes of the method 1000 can be omitted (e.g., any one of blocks 1010, 1040, 1042, 1044, and / or 1046), and / or the method 1000 can include additional processes not shown in FIG. 10. The method 1000 can generally loop from any succeeding process to a preceding process. For example, the method 1000 can loop from block 1030 to block 1010, from block 1040 to block 1010, and / or from block 1050 to block 1010. Accordingly, some or all of the processes of the method 1000 can be repeated to continuously or periodically adjust the operation of the implantable device to continuously or periodically optimize energy consumption.Examples(01551 The following examples are included to further describe some aspects of the present technology, and should not be used to limit the scope of the technology.

[0156] Example 1. A device comprising: an energy harvesting mechanism configured to produce energy from motion of a patient; a power source configured to receive an energy input from the energy harvesting mechanism and to deliver an energy output to power a plurality of device functions; processing circuitry; and a memory operably coupled to the processing circuitry and storing instructions that, when executed by the processing circuitry, cause the device to perform operations comprising: detecting an energy deficit between the energy input and the energy output of the power source, selecting one or moredevice functions of the plurality of device functions to deactivate based on a prioritization scheme, and deactivating the one or more device functions.

[0157] Example 2. The device of Example 1, wherein the operations further comprise: after deactivating the one or more device functions, determining whether the energy deficit is improving, in response to a determination that the energy deficit is not improving, selecting one or more additional device functions of the plurality of device functions to deactivate based on the prioritization scheme, and deactivating the one or more additional device functions.

[0158] Example 3. The device of Example 1 or 2, wherein the operations further comprise: after deactivating the one or more device functions, determining whether the energy deficit is improving, in response to a determination that the energy deficit is improving, selecting one or more deactivated device functions of the plurality of device functions to activate based on the prioritization scheme, and activating the one or more deactivated device functions.

[0159] Example 4. The device of any one of Examples 1-3, wherein the prioritization scheme is based on a patient profile.[0160| Example 5. The device of any one of Examples 1-4, wherein the plurality of device functions comprise one or more of a pacing function, sensing function, diagnostic function, rate response function, telemetry function, or safety margin function.

[0161] Example 6. The device of Example 5, wherein the pacing function comprises atrial pacing, ventricular pacing, or a combination thereof.[0162[ Example 7. The device of Example 5 or 6, wherein the sensing function comprises atrial sensing, ventricular sensing, or a combination thereof.

[0163] Example 8. The device of any one of Examples 5-7, wherein the diagnostic function comprises monitoring a status of the power source, monitoring a status of the patient, or a combination thereof.

[0164] Example 9. The device of any one of Examples 1-8, wherein the operations further comprise determining whether a charge level of the power source is below a threshold, and the selecting and deactivating are performed in response to a determination that the charge level is below the threshold.[0165| Example 10. The device of any one of Examples 1-9, wherein the operations further comprise: determining whether a charge level of the power source is below a threshold, and in response to a determination that the charge level of the power source is not below the threshold, performing an energy optimization process.

[0166] Example 11. The device of Example 10, wherein performing the energy optimization process comprises adjusting one or more parameters of a pacing signal delivered to the patient.]0167[ Example 12. The device of any one of Examples 1-11, wherein deactivating the one or more device functions comprises changing at least one of the one or more device functions from a high-power mode to a low-power mode, turning off at least one of the one or more device functions, or a combination thereof.[0168| Example 13. The device of any one of Examples 1-12, further comprising communications circuitry configured to communicate with an external device, wherein the operations further comprise outputting a notification to the external device indicating that the one or more device functions have been deactivated.

[0169] Example 14. The device of any one of Examples 1-13, further comprising one or more electrodes configured to deliver electrical stimulation to the patient.(0170[ Example 15. The device of any one of Examples 1-14, wherein the energy harvesting mechanism comprises a piezoelectric harvester.

[0171] Example 16. A method comprising: detecting, via processing circuitry, an energy deficit between an energy input and an energy output of a power source in an implantable device, wherein the energy output is configured to power a plurality of device functions of the implantable device; selecting, via the processing circuitry, one or more device functions of the plurality of device functions to deactivate based on a prioritization scheme; and deactivating, via the processing circuitry, the one or more device functions.

[0172] Example 17. The method of Example 16, further comprising: after deactivating the one or more device functions, determining, via the processing circuitry, whether the energy deficit is improving, in response to a determination that the energy deficit is not improving, selecting, via the processing circuitry, one or more additional device functions of the plurality of device functions to deactivate based on the prioritizationscheme, and deactivating, via the processing circuitry, the one or more additional device functions.

[0173] Example 18. The method of Example 16 or 17, further comprising: after deactivating the one or more device functions, determining, via the processing circuitry, whether the energy deficit is improving, in response to a determination that the energy deficit is improving, selecting, via the processing circuitry, one or more deactivated device functions of the plurality of device functions to activate based on the prioritization scheme, and activating, via the processing circuitry, the one or more deactivated device functions.

[0174] Example 19. The method of any one Examples 16-18, wherein the prioritization scheme is based on a patient profile.

[0175] Example 20. The method of any one of Examples 16-19, wherein the plurality of device functions comprise one or more of a pacing function, sensing function, diagnostic function, rate response function, telemetry function, or safety margin function.

[0176] Example 21. The method of Example 20, wherein the pacing function comprises atrial pacing, ventricular pacing, or a combination thereof.

[0177] Example 22. The method of Example 20 or 21, wherein the sensing function comprises atrial sensing, ventricular sensing, or a combination thereof.

[0178] Example 23. The method of any one of Examples 20-22, wherein the diagnostic function comprises monitoring a status of the power source, monitoring a status of a patient, or a combination thereof.

[0179] Example 24. The method of any one of Examples 16-23, further comprising determining, via the processing circuitry, whether a charge level of the power source is below a threshold, and the selecting and deactivating are performed in response to a determination that the charge level is below the threshold.

[0180] Example 25. The method of any one of Examples 16-24, further comprising: determining, via the processing circuitry, whether a charge level of the power source is below a threshold, and in response to a determination that the charge level of the power source is not below the threshold, performing, via the processing circuitry, an energy optimization process.[0181 [ Example 26. The method of Example 25, wherein performing the energy optimization process comprises adjusting one or more parameters of a pacing signal delivered to a patient.

[0182] Example 27. The method of any one of Examples 16-26, wherein deactivating the one or more device functions comprises changing at least one of the one or more device functions from a high-power mode to a low-power mode, turning off at least one of the one or more device functions, or a combination thereof.

[0183] Example 28. The method of any one of Examples 16-27, further comprising outputting a notification to an external device indicating that the one or more device functions have been deactivated.

[0184] Example 29. The method of any one of Examples 16-28, further comprising delivering electrical stimulation to a patient.

[0185] Example 30. The method of any one of Examples 16-29, wherein the energy input is received from an energy harvesting mechanism of the implantable device.

[0186] Example 31. A non-transitory computer-readable storage medium comprising instructions that, when executed by processing circuitry of an implantable device, cause the implantable device to perform operations comprising the method of any one of claims 16-30.Conclusion

[0187] Although many of the embodiments are described above with respect to systems, devices, and methods for cardiac pacing, the technology is applicable to other applications and / or other approaches, such as other therapies involving implantable devices. Moreover, other embodiments in addition to those described herein are within the scope of the technology. Additionally, several other embodiments of the technology can have different configurations, components, or procedures than those described herein. A person of ordinary skill in the art, therefore, will accordingly understand that the technology can have other embodiments with additional elements, or the technology can have other embodiments without several of the features shown and described above with reference to FIGS. 1-10.[0188| The embodiments of the present technology can be implemented, at least in part, in hardware, software, firmware or any combination thereof. For example, various embodiments can be implemented within one or more processors, including one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components, embodied in programmers (e.g., physician or patient programmers), stimulators, or other devices. The terms “processor” or “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry. 01S9 The various processes described herein can be partially or fully implemented using program code including instructions executable by one or more processors of a computing system for implementing specific logical functions or steps in the process. The program code can be stored on any type of computer-readable medium, such as a storage device including a disk or hard drive. Computer-readable media containing code, or portions of code, can include any appropriate media known in the art, such as non-transitory computer-readable storage media. Computer-readable media can include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage and / or transmission of information, including, but not limited to, random-access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory, or other memory technology; compact disc read-only memory (CD-ROM), digital video disc (DVD), or other optical storage; magnetic cassettes, magnetic tape, magnetic disk storage, or other magnetic storage devices; solid state drives (SSD) or other solid state storage devices; or any other medium which can be used to store the desired information and which can be accessed by a system device.[01901 The descriptions of embodiments of the technology are not intended to be exhaustive or to limit the technology to the precise form disclosed above. Where the context permits, singular or plural terms may also include the plural or singular term, respectively. Although specific embodiments of, and examples for, the technology are described above for illustrative purposes, various equivalent modifications are possible within the scope of the technology, as those skilled in the relevant art will recognize. For example, while steps are presented in a given order, alternative embodiments may perform steps in a different order. The various embodiments described herein may also be combined to provide further embodiments.[01911 As used herein, the terms “generally,” “substantially,” “about,” and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations in measured or calculated values that would be recognized by those of ordinary skill in the art.

[0192] Moreover, unless the word “or” is expressly limited to mean only a single item exclusive from the other items in reference to a list of two or more items, then the use of “or” in such a list is to be interpreted as including (a) any single item in the list, (b) all of the items in the list, or (c) any combination of the items in the list. As used herein, the phrase “and / or” as in “A and / or B” refers to A alone, B alone, and A and B. Additionally, the term “comprising” is used throughout to mean including at least the recited feature(s) such that any greater number of the same feature and / or additional types of other features are not precluded.

[0193] To the extent any materials incorporated herein by reference conflict with the present disclosure, the present disclosure controls.

[0194] It will also be appreciated that specific embodiments have been described herein for purposes of illustration, but that various modifications may be made without deviating from the technology. Further, while advantages associated with certain embodiments of the technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the technology. Accordingly, the disclosure and associated technology can encompass other embodiments not expressly shown or described herein.

Claims

CLAIMS1. A device comprising: an energy harvesting mechanism configured to produce energy from motion of a patient; a power source configured to receive an energy input from the energy harvesting mechanism and to deliver an energy output to power a plurality of device functions; processing circuitry; and a memory operably coupled to the processing circuitry and storing instructions that, when executed by the processing circuitry, cause the device to perform operations comprising: detecting an energy deficit between the energy input and the energy output of the power source, selecting one or more device functions of the plurality of device functions to deactivate based on a prioritization scheme, and deactivating the one or more device functions.

2. The device of claim 1, wherein the operations further comprise: after deactivating the one or more device functions, determining whether the energy deficit is improving, in response to a determination that the energy deficit is not improving, selecting one or more additional device functions of the plurality of device functions to deactivate based on the prioritization scheme, and deactivating the one or more additional device functions.

3. The device of claim 1 or 2, wherein the operations further comprise: after deactivating the one or more device functions, determining whether the energy deficit is improving, in response to a determination that the energy deficit is improving, selecting one or more deactivated device functions of the plurality of device functions to activate based on the prioritization scheme, andactivating the one or more deactivated device functions.

4. The device of any one of claims 1-3, wherein the prioritization scheme is based on a patient profile.

5. The device of any one of claims 1-4, wherein the plurality of device functions comprise one or more of a pacing function, sensing function, diagnostic function, rate response function, telemetry function, or safety margin function.

6. The device of claim 5, wherein the pacing function comprises atrial pacing, ventricular pacing, or a combination thereof.

7. The device of claim 5 or 6, wherein the sensing function comprises atrial sensing, ventricular sensing, or a combination thereof.

8. The device of any one of claims 5-7, wherein the diagnostic function comprises monitoring a status of the power source, monitoring a status of the patient, or a combination thereof.

9. The device of any one of claims 1-8, wherein the operations further comprise determining whether a charge level of the power source is below a threshold, and the selecting and deactivating are performed in response to a determination that the charge level is below the threshold.

10. The device of any one of claims 1-9, wherein the operations further comprise: determining whether a charge level of the power source is below a threshold, and in response to a determination that the charge level of the power source is not below the threshold, performing an energy optimization process.

11. The device of claim 10, wherein performing the energy optimization process comprises adjusting one or more parameters of a pacing signal delivered to the patient.

12. The device of any one of claims 1-11, wherein deactivating the one or more device functions comprises changing at least one of the one or more device functions from a high-power mode to a low-power mode, turning off at least one of the one or more device functions, or a combination thereof.

13. The device of any one of claims 1-12, further comprising communications circuitry configured to communicate with an external device, wherein the operations further comprise outputting a notification to the external device indicating that the one or more device functions have been deactivated.

14. The device of any one of claims 1-13, further comprising one or more electrodes configured to deliver electrical stimulation to the patient.

15. The device of any one of claims 1-14, wherein the energy harvesting mechanism comprises a piezoelectric harvester.

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