Tissue stimulation systems and methods, such as for pacing cardiac tissue - Patents.com

Abstract

The present technology is generally directed to an implantable medical device system for stimulating tissue, such as cardiac tissue. In some embodiments, the implantable medical device system includes a controller-transmitter and a receiver-stimulator in operative communication with each other. The receiver-stimulator can be implanted in a patient's heart. The controller-transmitter can be configured to transmit an acoustic signal to the receiver-stimulator, which receives the acoustic signal and converts it to electrical energy for delivery to the heart via one or more stimulation electrodes. The receiver-stimulator can further be configured to transmit a radio frequency signal to the controller-transmitter that includes information about the patient's sensed physiological parameters, status information, and the like.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Patent Application No. 17 / 668,771, filed February 10, 2022, and entitled "TISSUE STIMULATION SYSTEMS AND METHODS, SUCH AS FOR PACING CARDIAC TISSUE," which is incorporated by reference in its entirety.

[0002] The present technology relates generally to implantable medical devices and, in particular embodiments, to leadless tissue stimulation systems and methods for pacing cardiac tissue. [Background technology]

[0003] Electrical stimulation of body tissues is used throughout medicine for the treatment of both chronic and acute conditions. Among many examples, peripheral muscle stimulation has been reported to accelerate the healing of strains and tears, bone stimulation has been shown to increase the rate of bone regrowth / repair in fractures as well, and nerve stimulation has been used to relieve chronic pain. Additionally, research has been prompted in the use of electrical stimulation to treat various nerve and brain conditions such as idiopathic tremors, Parkinson's disease, migraines, functional deficits resulting from stroke, and epileptic seizures.

[0004] Cardiac pacemakers and implantable defibrillators are examples of commonly implanted devices that utilize electrical stimulation to stimulate the heart and other tissues. Pacemakers are battery-powered electronic devices that are implanted under the skin and connected to the heart by insulated metal lead wires with a tip electrode. Pacemakers were initially developed and are most commonly used to treat slowing heart rates (bradycardia), which can result from a number of conditions. More recently, advances in pacemaker complexity and associated sensing and pacing algorithms have enabled advances in using pacemakers for the treatment of other conditions, notably heart failure (HF) and fast heart rhythms (tachyarrhythmia / tachycardia).

[0005] An electrical energy source connected to an electrode / lead wire system is typically used to stimulate tissue within the body. The use of lead wires is associated with significant problems such as complications due to infection, lead failure, and electrode / lead dislodgement. The requirement for leads to perform stimulation also limits the number of accessible locations within the body. The requirement for leads also limits the ability to stimulate at multiple sites (multi-site stimulation). Summary of the Invention [Means for solving the problem]

[0006] Aspects of the present disclosure are generally directed to systems and methods for stimulating a patient's tissue, such as cardiac tissue, for cardiac pacing. In some of the embodiments described below, for example, a system for stimulating (e.g., pacing) a patient's heart includes a controller-transmitter and one or more receiver-stimulators in operative communication with each other. The receiver-stimulator can be implanted in the patient's heart and the controller-transmitter can be implanted in the patient remote from the heart. The controller-transmitter can be configured to transmit an acoustic signal to the receiver-stimulator, the acoustic signal including acoustic energy and modulated and / or encoded stimulation parameters. The receiver-stimulator can receive the acoustic signal and convert the acoustic signal to electrical energy for delivery to the heart via one or more stimulation electrodes in accordance with the stimulation parameters. The receiver-stimulator can further be configured to transmit a radio frequency signal to the controller-transmitter, the radio frequency signal including information about the patient's sensed physiological parameters, status information, and the like. In some embodiments, the controller-transmitter can receive the radio frequency signal and modify the transmitted acoustic signal accordingly. In some embodiments, the controller-transmitter can further transmit the radio frequency signal to a receiver-stimulator, which can harvest energy from the radio frequency signal to power one or more of its electronic components (e.g., controller, physiological sensor).

[0007] In some additional embodiments described below, a method of delivering electrical stimulation energy to a patient's heart can include receiving a cardiac signal indicative of cardiac function, for example from a receiver-stimulator or controller-transmitter. The method can further include determining a time interval between a selected number of cardiac beats based on the received cardiac signal, determining an average time interval between the beats, and determining a pacing pulse interval. The method can then include delivering electrical stimulation to the heart according to the pacing pulse interval. In some aspects of the technology, determining the time interval does not include (e.g., does not depend on) determining the amplitude or morphology of a waveform of the cardiac signal.

[0008] In some additional embodiments described below, the implanted receiver-stimulator includes a storage unit configured to store electrical energy converted from the acoustic signal transmitted by the controller-transmitter. The storage unit can be electrically coupled to one or more stimulation electrodes via a switch. The receiver-stimulator can further include a controller electrically coupled to the switch and configured to control the switch to open and close one or more times to deliver electrical energy from the storage unit to the stimulation electrodes for output to the heart as a first electrical pulse and a second electrical pulse. The controller-transmitter can be configured to detect the first electrical pulse and pause transmission of the acoustic signal in response to detecting the first electrical pulse. In some embodiments, the controller can control the switch based on a charge state of the storage unit, for example, to deliver a first stimulation pulse such that when the storage unit is sufficiently charged, the controller-transmitter pauses transmission of the acoustic signal. The second electrical pulse can have an amplitude, pulse duration, and / or other characteristics sufficient to stimulate the patient's heart. [Brief description of the drawings]

[0009] 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, emphasis instead being placed upon clearly illustrating the principles of the present disclosure.

[0010] [Figure 1] FIG. 1 is a schematic diagram of a tissue stimulation system configured in accordance with an embodiment of the present technology.

[0011] [Diagram 2] FIG. 2 is a schematic diagram of a tissue stimulation system configured in accordance with an additional embodiment of the present technology.

[0012] [Diagram 3] FIG. 3 illustrates the energy harvesting circuitry of the receiver-stimulator of the system of FIG. 2, configured in accordance with an embodiment of the present technology.

[0013] [Figure 4] FIG. 4 is a schematic diagram of a tissue stimulation system configured in accordance with an additional embodiment of the present technology.

[0014] [Diagram 5] FIG. 5 is a schematic diagram of a tissue stimulation system configured in accordance with an additional embodiment of the present technology.

[0015] [Figure 6] FIG. 6 is a flow diagram of a process or method for a tissue stimulation system to generate and deliver electrical stimuli (eg, electrical pacing pulses) to a patient's heart in accordance with an embodiment of the present technology.

[0016] [Figure 7] FIG. 7 is a partial schematic diagram of a tissue stimulation system configured in accordance with an additional embodiment of the present technology.

[0017] [Figure 8]FIG. 8 illustrates an example control scheme and timing sequence for the system of FIG. 7 in a pacemaker application in accordance with an embodiment of the present technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Detailed Description Specific details of some embodiments of the technology are described herein with reference to FIGURES 1-8. However, the technology can be practiced without some of these specific details. In some instances, well-known structures and techniques often associated with leadless tissue stimulation systems, cardiac pacing, electronic circuitry, acoustic and radio frequency transmission and reception, and the like, have not been shown in detail so as not to obscure the technology. The terminology used in the description presented below is intended to be interpreted in its broadest reasonable manner, even when used in conjunction with the detailed description of certain specific embodiments of the present disclosure. Certain terms may be further emphasized below, however, any terminology intended to be interpreted in any limited manner will be clearly and specifically defined as such in this detailed description section.

[0019] The accompanying figures depict embodiments of the present technology and are not intended to limit its scope. The sizes of the various depicted elements are not necessarily drawn to scale, and these various elements may be arbitrarily enlarged to improve legibility. Details of components may be summarized in the figures and omit details such as the location of components and certain precise connections between such components when such details are not necessary for a complete understanding of how to make and use the technology. Many of the details, dimensions, angles, and other features shown in the figures are merely illustrative of certain embodiments of the present disclosure. Thus, other embodiments may have other details, dimensions, angles, and features without departing from the spirit or scope of the present technology.

[0020] General aspects of the systems and methods of the present technology and the environment in which it may operate are described below with reference to FIG. 1. Further embodiments of the present technology are described below with reference to FIGS. 2-8. Those skilled in the art will appreciate that the components and functionality of the various embodiments may be combined with each other. For example, any of the receiver-stimulator and / or controller-transmitter and associated methods described in detail with reference to FIGS. 2-8 may be combined with each other and / or operate within the environment described with reference to FIG. 1. Additionally, while the present technology is generally described in an environment for stimulating the heart, those skilled in the art will appreciate that one or more aspects of the present technology may be applicable to other implantable devices configured to treat other areas of the human body.

[0021] FIG. 1 is a schematic diagram of a tissue stimulation system 100 ("system 100") configured in accordance with an embodiment of the present technology. In the illustrated embodiment, system 100 is configured to stimulate a heart 102 within a human patient's body 104. System 100 can include a receiver-stimulator 110 (which can also be referred to as a stimulator, ultrasound receiver, acoustic receiver, and the like) in operative communication (e.g., wireless and / or wireless communication) with a controller-transmitter 120 (which can also be referred to as an ultrasound transmitter, pulse generator, acoustic transmitter, and the like). Controller-transmitter 120 can include a battery module 122 and a transmitter module 124 that is operatively coupled to and powered via battery module 122. In some embodiments, both receiver-stimulator 110 and controller-transmitter 120 can be implanted within the human patient's body 104. For example, the receiver-stimulator 110 can be implanted in and / or adjacent to the heart 102 (e.g., in the left ventricle, right ventricle, or adjacent area) to deliver stimulation pulses to the heart 102, while the controller-transmitter 120 can be located elsewhere remote from the heart 102 (e.g., in the thoracic area). As described in more detail below with reference to Figures 2-8, the transmitter module 124 of the controller-transmitter 120 can direct energy (e.g., acoustic energy, ultrasonic energy) towards the receiver-stimulator 110, which can receive the energy and deliver one or more electrical pulses (e.g., stimulation pulses, pacing pulses) to the heart 102.

[0022] In some embodiments, the system 100 can further include a programmer 130 in operative communication with the controller-transmitter 120. The programmer 130 can be positioned outside the body 104 and operable to program various parameters of the controller-transmitter 120 (e.g., by a physician) and / or receive diagnostic information from the controller-transmitter 120. In some embodiments, the system 100 can further include a co-implanted device 132 (e.g., an implantable cardioverter-defibrillator (ICD) or pacemaker) coupled to a pacing lead 134 for delivering stimulation pulses to one or more portions of the heart 102 other than the area stimulated by the receiver-stimulator 110. In other embodiments, the co-implanted device 132 can be a leadless pacemaker, which is implanted directly into the heart, eliminating the need for a separate pacing lead 134. The co-implanted device 132 and the controller-transmitter 120 can work in conjunction to deliver stimulation signals to the heart 102 to cause synchronized heartbeats. In some embodiments, the controller-transmitter 120 can receive signals (e.g., electrocardiogram signals) from the heart 102 and determine information related to the heart 102, such as heart rate, heart rhythm, etc., including the output of pacing leads 134 located within the heart 102. In some embodiments, the controller-transmitter 120 can alternatively or additionally be configured to receive information (e.g., diagnostic signals) from the receiver-stimulator 110, as described in more detail below with reference to Figures 2-8. The received signals can be used to adjust the ultrasound energy signals delivered to the receiver-stimulator 110.

[0023] The receiver-stimulator 110, controller-transmitter 120, and / or programmer 130 may include machine-readable (e.g., computer-readable) or controller-readable media containing instructions for generating, transmitting, and / or receiving suitable signals (e.g., stimulation signals, diagnostic signals). The receiver-stimulator 110, controller-transmitter 120, and / or programmer 130 may include one or more processors, memory units, and / or input / output devices. Thus, the process of providing stimulation signals and / or performing other associated functions may be implemented by computer-executable instructions contained on, or within a computer-readable medium located on the receiver-stimulator 110, controller-transmitter 120, and / or programmer 130. Additionally, the receiver-stimulator 110, controller-transmitter 120, and / or programmer 130 may include dedicated hardware, firmware, and / or software to execute computer-executable instructions that, when executed, implement any one or more methods, processes, and / or sub-processes described herein. Specialized hardware, firmware, and / or software may also act as "means for" implementing the methods, processes, and / or sub-processes described herein.

[0024] In some embodiments, system 100 can include several features generally similar or the same as those of the leadless tissue stimulation systems disclosed in (i) U.S. Pat. No. 7,610,092, filed Dec. 21, 2005, and entitled "LEADLESS TISSUE STIMULATION SYSTEMS AND METHODS," (ii) U.S. Pat. No. 8,315,701, filed Sep. 4, 2009, and entitled "LEADLESS TISSUE STIMULATION SYSTEMS AND METHODS," and / or (iii) U.S. Pat. No. 8,718,773, filed May 23, 2007, and entitled "OPTIMIZING ENERGY TRANSMISSION IN A LEADLESS TISSUE STIMULATION SYSTEM."

[0025] 2 is a schematic diagram of a leadless tissue stimulation system 200 ("system 200") configured in accordance with an embodiment of the present technology. System 200 can generally include some features similar or the same as those of system 100, described in detail above with reference to FIGURE 1. For example, system 200 can include a receiver-stimulator 210 in operative communication with a controller-transmitter 220.

[0026] In the illustrated embodiment, the controller-transmitter 220 includes a signal conditioning and processing circuit 225, a controller 226 (e.g., control and timing circuitry, a communication module, voltage regulators), a first communication circuit 227, a second communication circuit 228, and a receiving circuit 229. In some embodiments, the signal conditioning and processing circuit 225 can receive signals from the receiving circuit 229 and / or signals from one or more additional sources 221 and condition and / or process these signals before passing them to the controller 226. In some embodiments, the additional source 221 can include an external programmer, such as the programmer 130 of FIG. 1. Furthermore, as described in more detail below with reference to FIG. 5, in some embodiments, the signals from the additional source 221 can include signals from a co-implanted device (e.g., pacing signals) and / or physiological signals from one or more physiological sensors carried within and / or by the controller-transmitter 220. The controller 226 can use information received from the signal conditioning and processing circuit 225 to generate (i) a first control signal for the first communication circuit 227 to generate a first signal 240 for transmission to the receiver-stimulator 210, and / or (ii) a second control signal for the second communication circuit 228 to generate a second signal 242 for transmission to the receiver-stimulator 210.

[0027] In some embodiments, the first signal 240 can be an ultrasonic energy signal (e.g., ultrasonic energy transmission) having a particular frequency range, such as, for example, 500 kHz to 10 MHz, 800 kHz to 2 MHz, or 900 kHz to 1 MHz (e.g., about 921 kHz). The controller-transmitter 220 can transmit the first signal 240 as a focused beam of wireless energy (e.g., ultrasonic energy). Thus, the first communication circuit 227 can comprise one or more transducers, signal generators, amplifiers, and the like, to generate and direct the first signal 240 toward the receiver-stimulator 210. In some embodiments, the second signal 242 is an electromagnetic signal having a frequency greater than the frequency of the first signal 240. For example, the second signal 242 can be a radio frequency (RF) signal having a frequency greater than 1 MHz, greater than 10 MHz, greater than 100 MHz, greater than 400 MHz, or greater. In certain embodiments, the second signal 242 has a frequency of about 402-405 MHz. Thus, the second communication circuit 228 may comprise one or more signal generators, amplifiers, antennas, and the like to generate and direct the second signal 242 towards the receiver-stimulator 210. Thus, in some aspects of the present technology, the system 200 is a dual frequency system that operates at both acoustic (e.g., ultrasonic) and radio frequencies.

[0028] Generally, the receiver-stimulator 210 includes a housing 211 that collectively contains and / or carries various electronic components, circuit components, circuit blocks, functional blocks, and the like that enable the receiver-stimulator 210 to (i) receive a first signal 240 and a second signal 242 from the controller-transmitter 220, (ii) transmit a third signal 244 to the controller-transmitter 220, and (iii) deliver one or more electrical pulses (e.g., pacing pulses, stimulation pulses) to a patient's tissue (e.g., heart 102, shown in FIG. 1). More specifically, in the illustrated embodiment, the receiver-stimulator 210 includes a transducer-pacing circuit 212 that receives the first signal 240 and converts the first signal 240 into an electrical pacing pulse for delivery via one or more electrodes 213 (e.g., a pair of stimulation electrodes). In some embodiments, the transducer-pacing circuit 212 includes one or more piezoelectric elements (e.g., including crystal, ceramic, and / or other materials) that accumulate an electrical charge in response to receiving the first signal 240, and circuitry (e.g., detector circuitry, envelope detector circuitry, rectifier circuitry, filtering circuitry, voltage limiting circuitry) to produce a voltage pulse with an amplitude and length proportional to the first signal 240. The transducer-pacing circuit 212 can deliver the voltage pulse to electrodes 213, which can protrude beyond and / or be embedded within an exterior surface of the housing 211 so as to contact the patient's tissue when the receiver-stimulator 210 is implanted therein. In some embodiments, the housing 211 comprises a hermetically sealed case of a biologically compatible material.

[0029] In the illustrated embodiment, the receiver-stimulator 210 further includes a first antenna 214 that can receive the second signal 242 from the controller-transmitter 220, convert the second signal 242 into an electrical signal, and pass the electrical signal to the energy harvesting circuit 215. In the illustrated embodiment, the receiver-stimulator 210 further includes a communication circuit 217 and a physiological sensor 218 (e.g., cardiac sensor) electrically coupled to the controller 216 (e.g., processor, voltage regulator). The energy harvesting circuit 215 generates power (e.g., harvests energy) from the second signal 242 and passes the power to the controller 216. In some embodiments, the energy harvesting circuit 215, the controller 216, the communication circuit 217, and / or another component of the receiver-stimulator 210 (e.g., capacitor, battery) can store the energy generated by the energy harvesting circuit 215. The physiological sensor 218 can sense one or more intrinsic cardiac parameters of the patient's heart (e.g., heart 102 of FIG. 1) in which the receiver-stimulator 210 is implanted. For example, the physiological sensor 218 can comprise an intracardiac electrogram (IEGM) sensor, and in some embodiments can measure the IEGM at the electrodes 213. In some embodiments, the physiological sensor 218 can additionally or alternatively include a transducer (e.g., low frequency transducer, microphone) that detects one or more cardiac sounds, such as sounds corresponding to the operation of a heart valve (e.g., aortic valve, mitral valve). Similarly, the physiological sensor 218 can detect the onset of certain cardiac events, such as diastole, systole, etc.

[0030] The communication circuitry 217 can be electrically coupled to the second antenna 219 and can generate and / or pass an electrical signal to the second antenna 219 for transmission to the controller-transmitter 220 (e.g., the receiver circuitry 229) as the third signal 244. In some embodiments, the communication circuitry 217 performs pulse width modulation of a signal from the controller 216 (and / or other components of the receiver-stimulator 210) at a high frequency. In some embodiments, the third signal 244 has a frequency that is the same as or generally similar to the frequency of the second signal 242 (e.g., an RF-signal having a frequency of about 402-405 MHz). The communication circuitry 217 and the second antenna 219 can be configured (e.g., shaped, positioned, adjusted) to transmit the third signal 244 towards the controller-transmitter 220 as a focused beam of wireless energy. In some embodiments, the first and second antennas 214, 219 comprise multiple windings of a metallic wire material (eg, gold).

[0031] In some embodiments, the controller 216 can be an application specific integrated circuit (ASIC) or other type of controller configured to at least partially control the operation of various electronic components of the receiver-stimulator 210. For example, the controller 216 can receive power produced by the energy harvesting circuit 215 and a physiological parameter detected by the physiological sensor 218, send a control signal to the communication circuit 217, and generate a third signal 244 including encoded information about the physiological parameter for transmission to the controller-transmitter 220. That is, the controller 216 can utilize the power conveyed via the second signal 242 to generate and transmit back to the controller-transmitter 220 (e.g., via the communication circuit 217 and the second antenna 219) a third signal 244 including information about the detected physiological parameter in real time or near real time. The receiver circuit 229 of the controller-transmitter 220 may include an antenna and / or other components to receive and decode the third signal 244, e.g., before passing it to the signal conditioning and processing circuit 225 and the controller 226. In some embodiments, the delivered signal may additionally or alternatively include information about the status of the receiver-stimulator 210, the efficiency of the pacing stimulation via the electrodes 213, and / or other information detected by the receiver-stimulator 210. The controller-transmitter 220 may utilize the information received via the third signal 244 to modify the first signal 240, such as the timing, amplitude, pulse length, and / or other characteristics of the first signal 240, thereby controlling the electrical stimulation (e.g., pacing stimulation) output by the electrodes 213.

[0032] The power generated by the energy harvesting circuit 215 can alternatively or additionally be used to provide stimulation pulses to the patient's tissue via the electrodes 213. For example, in some embodiments, the controller 216 can combine and / or manage the power received from the first signal 240 and the second signal 242 and provide an appropriate stimulation pulse or pulses to the electrodes 213 (e.g., via the transducer-pacing circuit 212). In some embodiments, the power from the second signal 242 can be used as a backup power source to power the electrodes 213 if the first signal 240 is lost. In some embodiments, the power from the second signal 242 can be used to power the physiological sensor 218 and / or other electronic components of the receiver-stimulator 210.

[0033] 3 illustrates the energy harvesting circuit 215 of the receiver-stimulator 210 shown in FIG. 2 configured in accordance with an embodiment of the present technology. With reference to both FIGS. 2 and 3, the energy harvesting circuit 215 can harvest energy from a second signal 242 (e.g., a radio frequency signal) transmitted from the controller-transmitter 220 to the receiver-stimulator 210. After receiving the second signal 242 through the first antenna 214, the first antenna 214 receives the radio frequency input signal RF IN 3, the energy harvesting circuit 215 receives the input signal RF IN and ground signal RF GROUND The input signal RF includes an electrical connector for receiving the input signal RF. IN is passed through the first diode D1 and the second diode D2, and the input signal RF INIn some embodiments, the first and second diodes D1 and D2 can be Schottky diodes, which have a low forward voltage for energy efficiency. In the illustrated embodiment, the energy harvesting circuit 215 further includes a network of capacitors C (including first through fifth capacitors C1-C5, respectively, which are individually identified). The first through third capacitors C1-C3 are connected to a rectified and conditioned input signal RF. IN Before being input into the charge pump 345, the input signal RF IN 3 and 4 may be connected across the charge pump 345 to provide a selected capacitance for signal conditioning. In some embodiments, the charge pump 345 may be of a type sold by Seiko Instruments Inc. under product model "S882Z." In other embodiments, the charge pump 345 may be another type of charge pump and / or may be integrated into the controller 216 (FIG. 2).

[0034] In the illustrated embodiment, the charge pump outputs an output signal RF that may be further tuned via a resistor R1 (e.g., a high value resistor (HVR)), a fourth capacitor C4, and / or a fifth capacitor C5. OUT 2 and 3, the conditioned output signal RF OUT can be output to the controller 216 (e.g., a voltage regulation circuit of the controller 216) via the anode 347 and the cathode 349. In other embodiments, the energy harvesting circuit 215 can include more or fewer electronic components suitable for harvesting energy from the second signal 242 and outputting the energy (e.g., a voltage) to the controller 216 and / or another component of the receiver-stimulator 210.

[0035] FIG. 4 is a schematic diagram of a tissue stimulation system 400 ("system 400") configured in accordance with an embodiment of the present technology. System 400 may include several features similar or the same as those of systems 100 and / or 200, generally described in detail above with reference to FIGS. 1-3. For example, system 400 may include a receiver-stimulator 410 in operative communication with a controller-transmitter 420. Similarly, in the illustrated embodiment, receiver-stimulator 410 includes a housing 411 that contains and / or carries a transducer-pacing circuit 412, a stimulating electrode 413, a controller 416 (e.g., a voltage regulation ASIC), and a physiological sensor 418. Transducer-pacing circuit 412 may receive a first signal 440 (e.g., an acoustic ultrasound signal) from controller-transmitter 420 and convert the first signal 440 into an electrical pacing pulse for delivery via one or more of electrodes 413.

[0036] In the illustrated embodiment, the receiver-stimulator 410 further includes a communication circuit 448 electrically coupled to the transducer-pacing circuit 412 and / or the controller 416. The communication circuit 448 can receive a portion of the first signal 440 and encode and / or modulate a portion of the first signal 440 with information from the physiological sensor 418 and / or status information about the receiver-stimulator 410 for transmission back to the controller-transmitter 420 as a second signal 452. In some embodiments, the communication circuit 448 is configured to encode information into the second signal 452 using a pulse position and / or pulse width code. In some embodiments, the first and second signals 440, 452 can be acoustic signals (e.g., ultrasound signals) having the same or substantially similar frequencies, such as, for example, about 500 kHz to 10 MHz, 800 kHz to 2 MHz, or 900 kHz to 1 MHz (e.g., about 921 kHz). Thus, the communication circuitry 448 may include one or more transducer elements (e.g., piezoelectric elements), antennas, and / or modulation components configured to generate and direct the second signal 452 as a focused beam of ultrasonic energy toward the controller-transmitter 420 (e.g., an ultrasonic receiver therein). Thus, in some aspects of the present technology, the system 400 is a single frequency system that operates to both receive the first signal 440 and transmit the second signal 452 from the receiver-stimulator 410 at the same or substantially similar frequency.

[0037] In other embodiments, the communication circuitry 448 may include a speaker or piezoelectric beeper that may transmit the second signal 452 as an audible tone to the controller-transmitter 420. In such embodiments, the controller-transmitter 420 may include a microphone to receive the second signal 452 and convert the second signal 452 into an electrical signal.

[0038] FIG. 5 is a schematic diagram of a tissue stimulation system 500 ("system 500") configured in accordance with an embodiment of the present technology. System 500 may generally include several features similar or the same as those of systems 100, 200, and / or 400, described in detail above with reference to FIGS. 1-4. For example, system 500 may include a receiver-stimulator 510 in operative communication with a controller-transmitter 520. Controller-transmitter 520 may include a controller 526 electrically coupled to a first communication circuit 527 and configured to cause first communication circuit 527 to generate a first control signal 540 (e.g., an acoustic ultrasonic signal) for transmission to receiver-stimulator 510. Receiver-stimulator 510 may receive first signal 540 and output an electrical stimulation pattern based on first signal 540.

[0039] In the illustrated embodiment, the controller-transmitter 520 further includes a physiological sensor 550, which may sense, for example, one or more intrinsic cardiac parameters of the patient's heart (e.g., heart 102 of FIG. 1). In some embodiments, the physiological sensor 550 may include one or more electrodes positioned on the casing 511 of the controller-transmitter 520 (e.g., on the exterior or outer surface of the casing 511 facing the heart) to sense far-field electrogram (EGM), impedance, plethysmographic information, and / or hemodynamic activity. In additional embodiments, the physiological sensor 550 can be an optical sensor (e.g., a photoplethysmography (PPG) optical sensor), a microphone, and / or another type of sensor configured to detect one or more heart sounds, such as mitral and / or aortic valve heart sounds. After detecting one or more physiological parameters, the physiological sensor 550 can pass a signal representative of the parameter to the controller 526 and / or other electronic components of the controller-transmitter 520.

[0040] In the illustrated embodiment, the controller-transmitter 520 further includes a receiver circuit 552 that can receive a second signal 551 from a co-implanted device (e.g., co-implanted device 132 of FIG. 1). The second signal 551 can include instructions for programming parameters (e.g., operating parameters) of the controller-transmitter 520 and triggering specific outputs of the first signal 540. In some embodiments, the second signal 551 is a radio frequency signal and the receiver circuit 552 can include an antenna and / or other components to receive and decode the second signal 551. Thus, the second signal 551 can be a wireless radio frequency communication signal. In other embodiments, the second signal 551 can be an electrical signal (e.g., an electrical pulse) generated by the pacing lead 134 of the co-implanted device 132 and / or other electrodes of the co-implanted device 132, such as, for example, a dedicated communication electrode positioned on an external surface of the co-implanted device 132. In other embodiments, the controller-transmitter 520 can be communicatively coupled to the co-implant device 132 via a different wireless or wired communication link. After receiving, decoding, and / or processing the second signal 551, the receiver circuitry 552 can pass the second signal 551 to the controller 526 and / or other electronic components of the controller-transmitter 520.

[0041] The controller 526 is electrically coupled to the physiological sensor 550 and the receiver circuit 552 and can generate a first control signal to generate a first signal 540 based, at least in part, on (i) a physiological parameter detected by the physiological sensor 550 and / or (ii) an instruction transmitted by the co-implanted device 132. That is, the controller 526 can cause the first communication circuit 527 to generate and transmit the first signal 540, e.g., to cause the receiver-stimulator 510 to produce a specific stimulation output, in accordance with the patient's sensed physiological parameter and / or an instruction from the co-implanted device 132. In some embodiments, the controller-transmitter 520 can be configured as a "slave"-"master" co-implanted device 132 such that the parameters (e.g., amplitude, timing, pulse characteristics) of the first signal 540 are driven solely or substantially solely by the instructions of the co-implanted device 132, which are communicated via the second signal 551.

[0042] In the illustrated embodiment, the controller-transmitter 520 further includes a second communication circuit 554 operably coupled to the controller 526. The controller 526 can generate a second control signal to cause the second communication circuit 554 to generate a third signal 553 for transmission to an external device 556, such as a smartphone, tablet, computer, or other electronic device. In some embodiments, the third signal 553 is a Bluetooth® signal (e.g., a Bluetooth® Low Energy (BLE) signal) that communicatively couples the controller-transmitter 520 to the external device 556. Thus, the second communication circuit 554 can comprise a Bluetooth® chip, including a Bluetooth® antenna, amplifier, and / or other electronic components. In some embodiments, the controller 526 can operate the second communication circuit 554 to communicate data from the physiological sensor 550, data from the co-implanted device 132, status information, and / or other information to the external device 556 via the third signal 553. In some embodiments, the external device 556 can be a device of the patient's physician so that information can be automatically communicated from the system 500 to the physician without patient intervention.

[0043] 6 is a flow diagram of a process or method 660 for generating and delivering electrical stimuli (e.g., electrical pacing pulses) to a patient's heart using a tissue stimulation system in accordance with an embodiment of the present technology. Although certain features of method 660 are described in the context of the embodiments described in detail with reference to FIGS. 1-5, those skilled in the art will readily appreciate that method 660 may be performed using other suitable systems and / or devices described herein.

[0044] At block 661, the method 660 includes receiving a cardiac signal from a cardiac sensor of a receiver-stimulator implanted in the heart and / or a controller-transmitter implanted in the patient remote from the heart. For example, in some embodiments, the controller 226 of the controller-transmitter 220 can wirelessly receive the cardiac signal 244 from the physiological sensor 218 of the receiver-stimulator 210 and / or receive the cardiac signal 452 from the physiological sensor 418 of the receiver-stimulator 410. In other embodiments, the physiological sensor 550 of the receiver-stimulator 510 can detect the cardiac signal directly. The cardiac signal can include EGM information, plethysmographic information, audio information, and / or other cardiac information.

[0045] Optionally, at block 662, method 660 may include receiving a pacing signal from the co-implanted device. For example, in some embodiments, controller-transmitter 520 may receive pacing signal 551 from co-implanted device 132 directly via a wireless communication link, or may detect the pacing signal, for example, via one or more electrodes of controller-transmitter 520.

[0046] In block 663, method 660 includes determining a time interval of a predetermined number (N) of beats of the heart based on the received cardiac signal. Generally, this determination is based on the specific type of cardiac signal received from the cardiac sensor. For example, if the cardiac signal is an ECG signal (e.g., recorded at the controller-transmitter or recorded at the receiver-stimulator and wirelessly transmitted to the controller-transmitter), block 663 can include detecting a time interval between one or more of P-waves (e.g., representing atrial depolarization), QRS-compartments (e.g., representing ventricular depolarization), T-waves (e.g., representing ventricular repolarization), and / or other features in the ECG waveform in successive cardiac beats. Similarly, if the cardiac signal is a plethysmography signal, block 663 can include detecting a time interval between spikes in the plethysmography waveform that represent blood volumes (e.g., minimum or maximum blood volumes) in successive cardiac beats. Similarly, if the cardiac signal comprises audio information about cardiac function (e.g., heart valve opening and / or closing), block 663 may include detecting time intervals between features in the audio waveform that represent opening and closing of cardiac valves, contraction and expansion of atria and / or ventricles, etc., in successive heart beats. In some embodiments, the cardiac signal may be processed (e.g., filtered) to better facilitate determining the time intervals between heart beats.

[0047] In block 664, method 660 includes averaging the time interval of N heart beats to determine the first pacing pulse interval, e.g., by dividing the time interval by N. For example, if the time interval between ten heart beats (i.e., N=10) is determined in block 663, block 664 may include dividing the total time elapsed between the first detected heart beat and the tenth detected heart beat by 10 to determine the first pacing pulse interval. In some embodiments, the number of heart beats N can be 2, 2-10, 10, or greater than 10.

[0048] In block 665, method 660 may optionally include determining a second pacing pulse interval based on the pacing signal received in block 662. Typically, this determination is based on the specific type of pacing signal received from the cardiac sensor. For example, if the co-implanted device 132 transmits information (e.g., second signal 551) directly to the controller-transmitter 520 (e.g., via an RF communication link), the transmitted information may include the second pacing pulse interval. If the controller-transmitter detects the pacing signal of the co-implanted device 132 directly (e.g., via one or more electrodes), determining the second pacing pulse interval may include determining the time interval between features (e.g., electrical spikes) indicative of successive heart beats and averaging the number of heart beats (e.g., similar to the methodology of blocks 663 and 664).

[0049] In block 666, the method 660 may optionally include averaging the first and second pacing pulse intervals to determine a third pacing pulse interval. In block 667, the method may include delivering a pacing stimulus to the heart according to the third pacing pulse interval or according to the first pacing pulse interval if the second pacing pulse interval is not detected (i.e., in omission of optional blocks 662, 665, and / or 666). For example, the controller 226 may send a control signal to the first communication circuit 227 to cause the first signal 240 according to the determined third pacing pulse interval (e.g., with the third pacing pulse interval encoded therein). The transducer-pacing circuit 212 may receive the first signal 240 and convert the first signal 240 to an electrical pacing output delivered via the electrode 213 according to the third pacing interval.

[0050] Thus, in some aspects of the technology, method 660 can help ensure that electrodes 213 deliver pacing stimuli at specifically selected times relative to the patient's heartbeat. For example, in some embodiments, pacing stimuli can be reliably applied slightly prior to the ventricular depolarization (e.g., the QRS-compartment of the ECG). Furthermore, method 660 relies on the temporal characteristics of the cardiac signal, rather than the morphology or amplitude of the cardiac signal.

[0051] In some embodiments, method 660 can return to blocks 661 and / or 662. For example, method 660 can include delivering pacing stimuli (block 667) for a predetermined amount of time and / or a predetermined number of cardiac beats before method 660 returns to blocks 661 and / or 662 and recalibrates the pacing pulse interval.

[0052] 7 is a partial schematic diagram of a tissue stimulation system 700 ("system 700") configured in accordance with an embodiment of the present technology. System 700 may include several features similar or the same as those of systems 100, 200, 400, and / or 500, generally described in detail above with reference to FIGS. 1-5. For example, system 700 may include a receiver-stimulator 710 in operative communication with a controller-transmitter 720. Controller-transmitter 720 may generate and transmit a signal 740 (e.g., an acoustic ultrasound signal) to receiver-stimulator 710, including electrical stimulation parameters (e.g., pacing parameters provided by an external programmer, such as programmer 130 of FIG. 1).

[0053] In some embodiments, the controller-transmitter 720 can modulate the signal 740 to include electrical stimulation parameters. For example, the controller-transmitter 720 can pulse modulate the signal 740 such that the duration of a transmission burst or the time between subsequent transmission bursts encodes the electrical stimulation parameters. In some embodiments, the electrical stimulation parameters can include a minimum pacing rate, a threshold detection level for sensing cardiac depolarization, a pacing pulse output voltage, and / or the like. The receiver-stimulator 710 can receive the signal 740 and convert the signal 740 into power to stimulate tissue according to the electrical stimulation parameters. In some embodiments, the controller-transmitter 720 includes a sensor 721 (e.g., one or more electrodes) to detect the electrical output of the receiver-stimulator 710.

[0054] More specifically, in the illustrated embodiment, the receiver-stimulator 710 includes a housing 711 that contains and / or carries multiple electronic components, including a controller 716, a transducer circuit 770, a first storage unit 772, a second storage unit 774, a cathode 776, and an anode 778 (the cathode 776 and the anode 778 may collectively be referred to as "electrodes"). The cathode 776 and the anode 778 may protrude beyond and / or be incorporated within an outer surface of the housing 711 and are configured to be electrically coupled to a patient's tissue (e.g., cardiac tissue) for delivering electrical stimulation energy and / or sensing electrical signals through the tissue. The transducer circuit 770 (e.g., an energy harvesting circuit) can receive the signal 740, convert the signal 740 into power, and pass the power to the first storage unit 772 and the second storage unit 774 via a first electrical line 771 (e.g., a negative output of the transducer circuit 770). That is, the transducer circuit 770 can harvest energy from the signal 740 and charge the first and second storage units 772, 774. The first and second storage units 772, 774 can be capacitors, supercapacitors, rechargeable batteries, and / or other components that can store electrical energy. In the illustrated embodiment, the first storage unit 772 powers the controller 716 via a second electrical line 773.

[0055] The controller 716 can receive inputs from (i) the transducer circuit 770 via a first electrical line 771, (ii) the cathode 776 via a third electrical line 775 (e.g., a cathode bus), and (iii) the anode 778 via a fourth electrical line 777. The fourth electrical line 777 from the anode 778 can provide a ground reference for the controller 716 and / or other components of the receiver-stimulator 710. In the illustrated embodiment, the second storage unit 774 is electrically coupled to the cathode 776 via a switch 780 (e.g., the third electrical line 775 and / or one or more additional electrical lines) and provides power to the cathode 776 when the switch 780 is closed. In other embodiments, the switch 780 can be positioned between the second storage unit 774 and the anode 778, and the cathode 776 can be electrically coupled to the first electrical line 771.

[0056] In some embodiments, the controller 716 can amplify the input signals from the cathode 776 and the anode 778 and apply a detection algorithm to detect a cardiac event. For example, the controller 716 can apply a threshold level detector or other suitable algorithm to sense a cardiac depolarization event. The controller 716 can further determine when to electrically stimulate tissue (e.g., pace tissue) via the cathode 776 and the anode 778 based on (i) the timing of the sensed cardiac depolarization event (and / or another cardiac event) and / or (ii) the electrical stimulation parameters encoded within the signal 740. To apply electrical stimulation energy, the controller 716 can output a control signal via the sixth electrical line 783 to (i) close the switch 780 so that the second storage unit 774 delivers electrical stimulation energy to the cathode 776, and then (ii) open the switch 780 to achieve a desired pacing pulse width.

[0057] In some embodiments, the receiver-stimulator 710 can transmit a communication signal to the controller-transmitter 720 to indicate that the first storage unit 772 and / or the second storage unit 774 are fully charged. For example, the receiver-stimulator 710 can deliver an electrical energy pulse (e.g., a short duration, sub-stimulation pulse) to the cathode 776 that can be detected by the controller-transmitter 720 (e.g., a sensor 721 of the controller-transmitter 710). In other embodiments, the receiver-stimulator 710 can transmit a radio frequency or ultrasonic signal to the controller-transmitter 720, for example, as described in detail above with reference to FIGS. 2-4. After receiving the communication signal, the controller-transmitter 720 can terminate transmission of the signal 740 for a predetermined amount of time.

[0058] Figure 8 illustrates an example control scheme and timing sequence for the system 700 of Figure 7 in a pacemaker application (e.g., a bradycardia pacemaker application) with a receiver-stimulator 710 (Figure 7) implanted in a patient's heart in accordance with an embodiment of the present technology. Figure 8 depicts the evolution over time of (i) the on / off state of the system 700 ("controller-transmitter pacing on / off"), (ii) the patient's ECG ("ECG"), which represents EMG detected via the cathode 776 and / or anode 778, (iii) sensing of cardiac events by the controller 716 ("controller sensed events"), (iv) the acoustic output signal 740 of the controller-transmitter 720 ("controller-transmitter output"), and (v) the electrical output of the receiver-stimulator 710 ("receiver-stimulator output").

[0059] In the illustrated embodiment, the system 700 is enabled ("turned on") in a pacing mode at a first time T1. When the pacing mode is enabled, the controller-transmitter 720 can output a signal 740 including a short first transmission burst 890 and a longer second transmission burst 892 separated by a time interval I. In some embodiments, the time interval I encodes a maximum allowable cardiac interval D1 between cardiac beats for pacemaker applications. The transducer circuit 770 of the receiver-stimulator 710 can receive the second transmission burst 892 and convert acoustic energy into electrical energy for charging the first and second storage units 772, 774. In some embodiments, the receiver-stimulator 710 can determine the length of the second transmission burst 892, for example, by determining when the first and second storage units 772, 774 are sufficiently (e.g., fully) charged and outputting an output signal 894 (e.g., a communication signal, a communication pulse) via the cathode 776 and / or the anode 778 indicating that the charge is sufficient. The controller-transmitter 720 can detect the output signal 894 (e.g., via the sensor 721) and, in response to the detection, pause transmission of the signal 740. In some embodiments, the output signal 894 is a short duration electrical signal that is not configured (e.g., having a sufficiently low amplitude and / or duration) to stimulate the patient's heart. In some aspects of the technology, the arrangement can ensure that the receiver-stimulator 710 is optimally charged (e.g., to provide a prescribed output pacing voltage) regardless of the acoustic transmission path between the controller-transmitter 720 and the receiver-stimulator 710 and any changes in the acoustic transmission path over time (e.g., regardless of any variability in the acoustic transmission path across different heart beats).

[0060] After receiving the signal 740, the controller 716 can set a timer for a defined cardiac interval D1 while monitoring the patient's heart and sensing a defined cardiac event, such as a cardiac depolarization event in the EMG data sensed via the cathode 776 and / or anode 778. If the controller 716 does not sense the defined cardiac event after the interval D1, the controller 716 can send a control signal to close the switch 780 and deliver all or a portion of the electrical energy stored in the second storage unit 774 to the cathode 776 and / or anode 778 to stimulate (e.g., pace) the patient's heart. After a period of time comparable to a desired pacing pulse width, the controller 716 can then send a signal to open the switch 780. In the illustrated embodiment, for example, the receiver-stimulator 710 delivers a pacing pulse 896 at a second time T2 after the first time T1, the cardiac interval D1 has elapsed. The pacing pulse 896 may stimulate the heart to beat following time T2 as represented in the sensed ECG by induced waves 891. After the receiver-stimulator 710 delivers the pacing pulse 896, the controller-transmitter 720 may detect the delivered pacing pulse 896 and recharge the receiver-stimulator 710 by again transmitting signal 740 and charging the first and second storage units 772, 774, and the receiver-stimulator 710 may pause transmission of signal 740 by again outputting output signal 894 once the first and second storage units 772, 774 are sufficiently charged.

[0061] If the controller 716 now senses a defined cardiac event during the interval D1, the controller 716 can maintain the switch 780 in an open position so that stimulation is not applied to the heart. For example, in the illustrated embodiment, the controller 716 senses a defined cardiac event at a third time T3, during the interval D1, after the second time T2 (e.g., as represented by the event marker 893, corresponding to intrinsic cardiac activity 895). Thus, the receiver-stimulator 710 does not output a pacing pulse 896 and the controller-transmitter 720 does not retransmit the signal 740. At this point, the controller 716 can update the initial interval D1 to a second interval D2 based on the detected event marker 893. The interval D1 can be the same or different from the interval D2.

[0062] Continuing monitoring of cardiac events, charging of the receiver-stimulator 710, and delivery of pacing pulses 896 may continue as long as the pacing mode of the controller-transmitter 710 is enabled. For example, in the illustrated embodiment, the receiver-stimulator 710 delivers another pacing pulse 896 at a fourth time T4 after a third time T3, a cardiac interval D2 has elapsed. In some embodiments, the cardiac interval and / or parameters of the pacing pulse 896 may be modified by the controller-transmitter 720 in different transmissions of the signal 740 (e.g., by changing the initial interval D1 to a second interval D2). Furthermore, additional information and / or parameters may also be encoded in the signal 740, for example, by splitting the signal 740 into additional bursts. In such an embodiment, the delay between each burst may correspond to a different parameter.

[0063] The following examples illustrate some embodiments of the present technology. Example 1 1. A system for pacing cardiac tissue of a patient, comprising: a controller-transmitter including a first circuit and a second circuit, the first circuit configured to transmit an acoustic signal and the second circuit configured to receive a radio frequency signal; 1. A receiver-stimulator device configured for implantation within a patient in proximity to cardiac tissue, comprising: An electrode; a third circuit operably coupled to the electrode and configured to receive at least a portion of the acoustic signal, convert the acoustic signal to electrical energy for delivery to the cardiac tissue via the electrode, and electrically pace the cardiac tissue; a fourth circuit configured to transmit a radio frequency signal to the second circuit of the controller-transmitter; and a receiver-stimulator including: A system comprising: Example 2 The system of Example 1, wherein the receiver-stimulator further comprises a physiological sensor configured to sense a physiological parameter of the patient, and the high frequency signal contains information about the sensed physiological parameter. Example 3 The system of example 2, wherein the physiological parameter sensed is an intracardiac electrogram (IEGM). Example 4 The system of example 2, wherein the physiological parameter sensed is heart sounds. Example 5 The system of any one of Examples 2-4, wherein the controller-transmitter further includes a controller electrically coupled to the first circuit and the second circuit, the controller configured to control the first circuit and transmit an acoustic signal based, at least in part, on a sensed physiological parameter. Example 6 The system of any one of Examples 1-5, wherein the radio frequency signal contains information about the status of the receiver-stimulator. Example 7 A system described in any one of Examples 1-6, wherein the radiofrequency signal contains information about the efficiency of delivery of electrical energy to cardiac tissue. Example 8 The high frequency signal is a first high frequency signal, the controller-transmitter further comprises a fifth circuit configured to transmit the second radio frequency signal to the receiver-stimulator; The receiver-stimulator further comprises an energy harvesting circuit configured to receive the second radio frequency signal and convert the second radio frequency signal into electrical energy. A system according to any one of Examples 1-7. Example 9 The system of Example 8, wherein the receiver-stimulator further includes a controller configured to control timing of delivery of electrical energy from the third circuit to the cardiac tissue, the controller being configured to be powered, at least in part, by electrical energy from the energy harvesting circuit. Example 10 The system of Example 8 or Example 9, wherein the receiver-stimulator further includes a physiological sensor configured to sense a physiological parameter of the patient, the physiological sensor being configured to be powered, at least in part, by electrical energy from the energy harvesting circuit. Example 11 The system of Example 10, wherein the receiver-stimulator further comprises a controller configured to (a) receive electrical energy from the energy harvesting circuit and the physiological parameter from the physiological sensor, and (b) control the fourth circuit to generate a first high frequency signal including encoded information about the physiological parameter. Example 12 1. A method of delivering electrical stimulation energy to a patient's heart, comprising: receiving a cardiac signal indicative of cardiac function at a controller-transmitter implanted within the patient; determining, via the controller-transmitter, a time interval between a selected number of cardiac beats based on the received cardiac signal; determining, via the controller-transmitter, an average time interval between beats and determining a pacing pulse interval; wirelessly transmitting a signal from a controller-transmitter to a receiver-stimulator implanted within cardiac tissue, the signal being associated with a pacing pulse interval; delivering electrical stimulation energy to the heart via the receiver-stimulator in accordance with a pacing pulse interval; A method comprising: (Example 13) 13. The method of example 12, wherein the cardiac signal comprises a waveform and determining the time interval does not include determining an amplitude or morphology of the waveform. Example 14 The method of example 12 or example 13, wherein the cardiac signal is an electrocardiogram (ECG) signal. Example 15 The method of example 12 or example 13, wherein the cardiac signal is a plethysmography signal. (Example 16) 14. The method of example 12 or example 13, wherein the cardiac signal is an audio signal. (Example 17) The pacing pulse interval is a first pacing pulse interval, the method further comprising: receiving a pacing signal from a co-implant device implanted within the patient; determining a second pacing pulse interval based on the pacing signal; averaging the first and second pacing pulse intervals to determine a third pacing pulse interval; delivering electrical stimuli to the heart according to a third pacing pulse interval; The method of any one of Examples 12-16, comprising: (Example 18) The method of example 17, wherein the co-implanted device is an implantable cardioverter defibrillator (ICD) or a pacemaker. (Example 19) The method of any one of Examples 12-18, wherein receiving the cardiac signal includes receiving the cardiac signal from a receiver-stimulator implanted in the patient's heart at the controller-transmitter, the controller-transmitter configured to transmit acoustic energy to the receiver-stimulator, and the receiver-stimulator configured to convert the acoustic energy into electrical stimulation energy and deliver the electrical stimulation energy to the heart. (Example 20) 1. A system for stimulating tissue of a patient, comprising: a controller-transmitter configured to transmit an acoustic signal; 1. A receiver-stimulator device configured for implantation within a patient in proximity to tissue, comprising: An electrode; a transducer circuit configured to receive at least a portion of the acoustic signal and convert the acoustic signal into electrical energy; a storage unit electrically coupled to the transducer circuit and configured to store at least a portion of the electrical energy; a switch configured to selectively electrically couple the storage unit to the electrode; and a controller electrically coupled to the switch, the controller configured to control the switch to deliver electrical energy from the storage unit to the electrodes for output to the tissue as a first electrical pulse and a second electrical pulse; Including, The second electrical pulse is configured to stimulate the tissue; the controller-transmitter is configured to detect the first electrical pulse and, in response to detecting the first electrical pulse, pause transmission of the acoustic signal; A receiver-stimulator; A system comprising: Example 21 The system of example 20, wherein the first electrical pulse does not stimulate tissue. Example 22 The system of example 20 or example 21, wherein the first electrical pulse has a shorter pulse width than the second electrical pulse. Example 23 The tissue is cardiac tissue, and the controller-transmitter is configured to encode cardiac intervals for the cardiac tissue in the acoustic signal, and the receiver-stimulator controller further comprises: Senses depolarization of cardiac tissue, Detecting heartbeat intervals in the acoustic signal; Starting a timer for the heartbeat interval; if a depolarization is not sensed during the cardiac interval, after a timer has elapsed, control the switch to deliver a second stimulation pulse; The system according to any one of Examples 20-22, configured as follows: (Example 24) A system described in any one of Examples 20-23, wherein the controller is configured to control the switch and deliver the first stimulation pulse based on a charge state of the storage unit. (Example 25) A system described in any one of Examples 20-24, wherein the controller-transmitter is configured to detect a second electrical pulse and, in response to detecting the second electrical pulse, again transmit an acoustic signal to the receiver-stimulator.

[0064] The above detailed description of the embodiments of the present technology is not intended to be exhaustive or to limit the present technology to the precise form disclosed above. Although specific embodiments of the present technology and examples thereof are described above for illustrative purposes, various equivalent modifications are also possible within the scope of the present technology, as those skilled in the art will recognize. For example, although steps are presented in a given order, alternative embodiments may perform steps in a different order. Similarly, various electronic components and functions may be separated into more or fewer electronic circuit elements and / or functional blocks. Various components and / or functionalities of the embodiments described herein may be combined to provide further embodiments.

[0065] From the foregoing, it should be understood that, although specific embodiments of the present technology are described herein for illustrative purposes, well-known structures and functions have not been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments of the present technology. Where the context permits, singular or plural terms may also include the plural or singular terms, respectively.

[0066] Also, unless the word "or" is expressly limited with reference to a list of two or more items to mean only a single item exclusively from the other items, the use of "or" in such a list shall 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. In addition, the term "comprising" is used throughout to mean including at least the recited features, so that any greater number of the same features and / or other features of additional types are not excluded. Also, while specific embodiments are described herein for illustrative purposes, it should be understood that various modifications can be made without departing from the technology. Furthermore, while advantages associated with some embodiments of the technology are described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments necessarily exhibit such advantages to fall within the scope of the technology. Thus, the present disclosure and associated technology may encompass other embodiments not expressly shown or described herein.

Claims

1. 1. A system for pacing cardiac tissue of a patient, comprising: a controller-transmitter including a first circuit and a second circuit, the first circuit configured to transmit an acoustic signal and the second circuit configured to receive a radio frequency signal; A receiver-stimulator configured to be implanted within the patient proximate to the cardiac tissue, the receiver-stimulator comprising: An electrode; a third circuit operably coupled to the electrode and configured to receive at least a portion of the acoustic signal, convert the acoustic signal to electrical energy for delivery to the cardiac tissue via the electrode, and electrically pace the cardiac tissue; a fourth circuit configured to transmit the radio frequency signal to a second circuit of the controller-transmitter; a receiver-stimulator including: A system comprising:

2. 10. The system of claim 1, wherein the receiver-stimulator further comprises a physiological sensor configured to sense a physiological parameter of the patient, and the radiofrequency signal includes information about the sensed physiological parameter.

3. The system of claim 2 , wherein the sensed physiological parameter is an intracardiac electrogram (IEGM).

4. The system of claim 2 , wherein the sensed physiological parameter is a heart sound.

5. 3. The system of claim 2, wherein the controller-transmitter further comprises a controller electrically coupled to the first circuit and the second circuit, the controller configured to control the first circuit and transmit the acoustic signal based, at least in part, on the sensed physiological parameter.

6. The system of claim 1 , wherein the radio frequency signal includes information about the status of the receiver-stimulator.

7. The system of claim 1 , wherein the radiofrequency signal contains information about the efficiency of the delivery of the electrical energy to the cardiac tissue.

8. the high frequency signal is a first high frequency signal, the controller-transmitter further comprises a fifth circuit configured to transmit a second radio frequency signal to the receiver-stimulator; the receiver-stimulator further comprises an energy harvesting circuit configured to receive the second radio frequency signal and convert the second radio frequency signal into electrical energy. The system of claim 1 .

9. 10. The system of claim 8, wherein the receiver-stimulator further comprises a controller configured to control timing of delivery of the electrical energy from the third circuit to the cardiac tissue, the controller configured to be powered, at least in part, by the electrical energy from the energy harvesting circuit.

10. 10. The system of claim 8, wherein the receiver-stimulator further comprises a physiological sensor configured to sense a physiological parameter of the patient, the physiological sensor configured to be powered, at least in part, by the electrical energy from the energy harvesting circuit.

11. 11. The system of claim 10, wherein the receiver-stimulator further comprises a controller configured to (a) receive the electrical energy from the energy harvesting circuit and the physiological parameter from the physiological sensor, and (b) control the fourth circuit to produce the first radio frequency signal including encoded information about the physiological parameter.

12. 1. A method of delivering electrical stimulation energy to a patient's heart, the method comprising: receiving, at a controller-transmitter implanted within the patient, a cardiac signal indicative of function of the heart; determining, via the controller-transmitter, a time interval between a selected number of beats of the heart based on the received cardiac signal; determining, via the controller-transmitter, an average time interval between beats and a pacing pulse interval; wirelessly transmitting a signal from the controller-transmitter to a receiver-stimulator implanted in cardiac tissue, the signal being associated with the pacing pulse interval; delivering said electrical stimulation energy to said heart via said receiver-stimulator in accordance with said pacing pulse interval; A method comprising:

13. The method of claim 12 , wherein the cardiac signal includes a waveform, and determining the time intervals does not include determining an amplitude or morphology of the waveform.

14. The method of claim 12 , wherein the cardiac signal is an electrocardiogram (ECG) signal.

15. The method of claim 12 , wherein the cardiac signal is a plethysmography signal.

16. The method of claim 12 , wherein the cardiac signal is an audio signal.

17. The pacing pulse interval is a first pacing pulse interval, the method further comprising: receiving a pacing signal from a co-implant device implanted within the patient; determining a second pacing pulse interval based on the pacing signal; averaging the first and second pacing pulse intervals to determine a third pacing pulse interval; delivering the electrical stimulus to the heart in accordance with the third pacing pulse interval; The method of claim 12, comprising:

18. 18. The method of claim 17, wherein the co-implanted device is an implantable cardioverter defibrillator (ICD) or a pacemaker.

19. 13. The method of claim 12, wherein receiving the cardiac signal includes receiving the cardiac signal at the controller-transmitter from the receiver-stimulator implanted in the patient's heart, the controller-transmitter configured to transmit acoustic energy to the receiver-stimulator, and the receiver-stimulator configured to convert the acoustic energy to the electrical stimulation energy and deliver the electrical stimulation energy to the heart.

20. 1. A system for stimulating tissue of a patient, comprising: a controller-transmitter configured to transmit an acoustic signal; a receiver-stimulator configured to be implanted within the patient proximate to the tissue, the receiver-stimulator comprising: An electrode; a transducer circuit configured to receive at least a portion of the acoustic signal and convert the acoustic signal into electrical energy; a storage unit electrically coupled to the transducer circuit and configured to store at least a portion of the electrical energy; a switch configured to selectively electrically couple the storage unit to the electrode; a controller electrically coupled to the switch, the controller configured to control the switch to deliver the electrical energy from the storage unit to the electrode for output to the tissue as a first electrical pulse and a second electrical pulse; Including, the second electrical pulse is configured to stimulate the tissue; the controller-transmitter is configured to detect the first electrical pulse and, in response to detecting the first electrical pulse, to pause transmission of the acoustic signal. Receiver-stimulator and A system comprising:

21. 21. The system of claim 20, wherein the first electrical pulse does not stimulate the tissue.

22. 21. The system of claim 20, wherein the first electrical pulse has a shorter pulse width than the second electrical pulse.

23. The tissue is cardiac tissue, the controller-transmitter is configured to encode cardiac intervals for the cardiac tissue in the acoustic signal, and the receiver-stimulator controller is further configured to: sensing depolarization of the cardiac tissue; detecting the heartbeat interval in the acoustic signal; starting a timer for said cardiac interval; if the depolarization is not sensed during the cardiac interval, after the timer has elapsed, controlling the switch to deliver the second stimulation pulse. The system of claim 20 configured to:

24. 21. The system of claim 20, wherein the controller is configured to control the switch to deliver the first stimulation pulse based on a charge state of the storage unit.

25. 21. The system of claim 20, wherein the controller-transmitter is configured to detect the second electrical pulse and, in response to detecting the second electrical pulse, again transmit the acoustic signal to the receiver-stimulator.

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