A medical device and method conserve electrical power used in monitoring cardiac arrhythmias. The device includes a sensing circuit configured to sense a cardiac signal, a power source and a control circuit having a processor powered by the power source. The control circuit is configured to operate in a normal state by waking up the processor to analyze the cardiac electrical signal for determining a state of an arrhythmia. The control circuit switches from the normal state to a power saving state that includes waking up the processor at a lower rate than during the normal state.

Techniques for minimizing rate of depletion of a non-rechargeable power source, to extend the operational lifetime of an implantable medical device that includes the non-rechargeable power source, by enforcing operational-mode-specific communication protocols whereby inter-device communication between the implantable medical device and another implantable medical device is such that level of power draw from the non-rechargeable power source by the implantable medical device is less than level of power draw from the rechargeable power source by the another implantable medical device for the implantable medical devices to engage in communication with each other.

An implantable medical device is configured determine a numerical value of a variable that is monitored by the implantable medical device and convert the numerical value to a data sequence of modulated electrical stimulation rate intervals. The implantable medical device delivers electrical stimulation pulses according to the data sequence of modulated stimulation rate intervals to cause a modulated rate of activation of excitable tissue of a patient corresponding to the modulated stimulation rate intervals. The modulated rate of activation is detectable by a rate monitor for demodulation to the numerical value of the monitored variable data value. In some examples, the implantable medical device is a pacemaker delivering cardiac pacing pulses according to modulated pacing rate intervals to cause a modulated heart rate of the patient detectable by a heart rate monitor for demodulation to the numerical value of the monitored variable.

Disclosed herein are implantable medical devices (IMDs) including a receiver and a battery, and methods for use therewith. The receiver includes first and second differential amplifiers, each of which monitors for a predetermined signal within a frequency range and drains power from the battery while enabled, and while not enabled drains substantially no power from the battery. To remove undesirable input offset voltages, each of the differential amplifiers, while enabled, is selectively put into an offset correction phase during which time the predetermined signal is not detectable by the differential amplifier. At any given time at least one of the first and second differential amplifiers is enabled without being in the offset correction phase so that at least one of the differential amplifiers is always monitoring for the predetermined signal. In this manner, the receiver is never blind to signals, including the predetermined signals, sent by another IMD.

Methods and devices are provided for managing anti-tachycardia pacing therapy delivered by an implantable medical device (IMD). The methods and devices detect events from cardiac signals sensed at electrodes of the IMD. The cardiac signals represent a ventricular tachycardia (VT) episode that includes at least a select number of VT events having a corresponding VT cycle length. The methods and devices analyze the VT cycle length to define an anti-tachycardia pacing (ATP) therapy that includes a first coupling interval and deliver a first ATP pulse that is spaced the first coupling interval after a reference refractory VT event sensed at the electrodes. The methods and devices deliver a second ATP pulse following the first ATP pulse by a non-stimulation segment that is at least one and three-quarters (1.75) times a projected VT cycle length.

A method and device for managing establishment of a communications link between an external instrument (EI) and an implantable medical device (IMD) are provided. The method stores, in a memory in at least one of the IMD or the EI, a base scanning schedule that defines a pattern for scanning windows over a scanning state. The method enters the scanning state during which a receiver scans for advertisement notices during the scanning windows. At least a portion of the scanning windows are grouped in a first segment of the scanning state. The method stores, in the memory, a scan reset pattern for restarting the scanning state. Further, the method automatically restarts the scanning state based on the scan reset pattern to form a pseudo-scanning schedule that differs from the base scanning schedule and establishes a communication session between the IMD and the EI.

In some examples, determining an estimated remaining longevity of a power source of an implantable medical device comprises determining values of one or more parameters of the power source and one or more operational parameters of the implantable medical device; calculating, based on at least some of the determined parameter values, a first estimated duration until one of the determined parameters of the power source reaches a pre-recommended replacement time (pre-RRT) threshold and adding a timer duration to determine a first estimated longevity value; calculating, based on at least some of the determined parameter values, a second estimated duration until one of the determined parameters of the power source reaches a recommended replacement time (RRT) backup threshold as a second estimated longevity value; determining the estimated remaining longevity based on the two estimated longevity values; and indicating the determined estimated remaining longevity.

A method of programming an implantable medical device (IMD) configured to provide electrical stimulation via a plurality of stimulation vectors during delivery of the electrical stimulation of a plurality of pulse widths to a neural target. The method may comprise comparing strength-duration curve data for the plurality of stimulation vectors to one another, the strength-duration curve data representing, for respective pulse widths and stimulation vectors, a corresponding stimulation strength that evokes a physiological response associated with the neural target. The method may comprise selecting at least one stimulation vector of the plurality of stimulation vectors based on the comparison of the strength-duration curve data for the plurality of stimulation vectors. The method may comprise programming, in response to the selection, the IMD to deliver the electrical stimulation to the neural target via the selected at least one stimulation vector.

Systems, devices, and methods for pacing a heart of a patient are disclosed. A device may include a leadless cardiac pacemaker (LCP) that includes a power supply, a pair of electrodes, and a controller operably connected to the electrodes and the power supply. The controller may identify a capture threshold by setting a pace amplitude at a power supply voltage of the power supply and deliver pacing stimulation pulses with different pulse widths to identify the capture threshold. The LCP may then deliver pacing stimulation pulses based, at least in part, on a pulse amplitude and pulse width associated with the capture threshold, and also adding a capture margin. In some cases, the pulse amplitude may change over time and the LCP may adjust a pulse width along a strength-duration curve to account for the pulse amplitude change and maintain a capture threshold and capture margin.

Disclosed herein are implantable medical devices (IMDs) including a receiver and a battery, and methods for use therewith. The receiver includes first and second differential amplifiers, each of which monitors for a predetermined signal within a frequency range and drains power from the battery while enabled, and while not enabled drains substantially no power from the battery. To remove undesirable input offset voltages, each of the differential amplifiers, while enabled, is selectively put into an offset correction phase during which time the predetermined signal is not detectable by the differential amplifier. At any given time at least one of the first and second differential amplifiers is enabled without being in the offset correction phase so that at least one of the differential amplifiers is always monitoring for the predetermined signal. In this manner, the receiver is never blind to signals, including the predetermined signals, sent by another IMD.