Systems and methods for pacing cardiac conductive tissue are described. A medical system includes electrostimulation circuit that may generate His-bundle pacing (HBP) pulses for delivery at or near the His bundle. A capture verification circuit may detect, from a far-field signal representing ventricular response to the HBP pulses, a His-bundle response representative of excitation of the His bundle directly resulting from the HBP pulses, and a myocardial response representative of excitation of the myocardium directly resulting from the HBP pulses. A control circuit may adjust one or more stimulation parameters based on the His-bundle response and myocardial response. The electrostimulation circuit may generate and deliver the HBP pulses according to the adjusted stimulation parameters to excite the His bundle.

A medical device is configured to deliver therapeutic electrical stimulation pulses by generating frequency modulated electrical stimulation pulse signals. The medical device includes a pulse signal source and a modulator. The pulse signal source generates an electrical stimulation pulse signal having a pulse width. The modulator may include a high frequency modulator configured to modulate a frequency of the pulse signal from a starting frequency down to a minimum frequency during the pulse width. The modulator may include a low frequency bias generator to modulate the offset of the pulse signal between a minimum offset and a maximum offset in other examples.

A method for processing a cardiac signal represented as a function of time includes providing a number n of different threshold levels N.sub.i, with i=1 to n and n being greater than or equal to three; detecting, from a given time T and per threshold level N.sub.i, at least two successive intersections of the cardiac signal with the threshold level N.sub.i, considering a crossing per increasing and/or decreasing value of the cardiac signal with the threshold level N.sub.i; and determining at least one statistical parameter for the cardiac signal from the intersections of the cardiac signal with the at least three different threshold levels N.sub.i. The method may be implemented by a subcutaneous active implantable medical device having a control circuit configured to process a cardiac signal.

A medical device system and method estimate a time from a first voltage of a power source of a medical device to a second voltage of the power source. The medical device includes a sensor coupled to the power source for generating a physiological signal. The medical device system determines a current drain from the power source required for generating the physiological signal and/or processing the physiological signal for detecting events from the physiological signal. A processor of the medical device system is configured to estimate the time from the first voltage of the power source until the second voltage based on at least the determined current drain.

The disclosure relates to a device including a circuit for adjusting the energy of the stimulation pulses, independently controlling the pulse width and the voltage of each stimulation pulse. An iterative search algorithm for determining the optimum energy includes changing both the pulse width and voltage at each new pulse delivered, by setting a high energy value and a low energy value, and delivering a stimulation pulse with the low energy value. A capture test is then carried out. In the presence of a capture, a current iteration is complete and a new iteration is done with the current low energy as a new high energy value. In the absence of capture, the algorithm is terminated with selection of the last energy value that produced the capture as the value of optimum energy.

This disclosure relates to an active implantable medical device of the cardiac resynchronizer type. The device includes a pulse generator to produce pacing pulses, at least one detection electrode for detecting atrial and ventricular events, at least one stimulation electrode, a memory storing executable instructions, and a processor configured to execute the instructions. The processor is configured to execute the instructions to apply an atrioventricular delay (AVD) between a sensed or stimulated atrial event and the delivery of a ventricular pacing pulse, quantify a degree of fusion between the delivery of a pacing pulse to a cavity and a spontaneous contraction of another cavity, calculate a fusion rate, and modify the value of the AVD applied to the delivery of said ventricular pacing pulse, as a function of a comparison.

In some examples, a medical device system includes an electrode. The medical device system may include impedance measurement circuitry coupled to the electrode, the impedance measurement circuitry may be configured to generate an impedance signal indicating impedance proximate to the electrode. The medical device system may include processing circuitry that may be configured to identify a first component of the impedance signal. The first component of the impedance signal may be correlated to a cardiac event. The processing circuitry may be configured to determine that the cardiac event occurred based on the identification of the first component of the impedance signal.

A medical device comprises therapy delivery circuitry and processing circuitry. The therapy delivery circuitry is configured to deliver anti-tachycardia pacing (ATP) therapy to a heart of a patient. The ATP therapy includes one or more pulse trains and each of the one or more pulse trains includes a plurality of pacing pulses. The processing circuitry is configured to, for at least one of the plurality of pacing pulses of at least one of the one or more pulse trains, determine at least one latency metric of an evoked response of the heart to the pacing pulse. The processing circuitry is further configured to modify the ATP therapy based on the at least one latency metric.

A method of pacing a His bundle of a patient heart using a stimulation system including a memory, a pulse generator, a stimulating electrode and at least one sensing electrode includes applying a plurality of impulses through the stimulating electrode to induce a plurality of responses from the patient heart. Each impulse of the plurality of impulses is delivered at a different impulse energy corresponding to a respective output setting of the stimulation system. The response characteristics for each of the plurality of responses are measured and each impulse is assigned a classification based on whether the respective response characteristics indicate capture of one or both of the His bundle and a ventricle of the patient heart. The output setting and classification for each impulse is then stored in the memory.

An implantable medical device and computer implemented methods comprise a sensing circuit configured to sense cardiac activity (CA) signals. An accelerometer is configured to be implanted in a patient and obtain accelerometer data along at least one axis. A memory is configured to store program instructions and device parameters associated with each ventricular arrhythmia (VA) therapy in a collection of VA therapies with different levels of intensity. One or more processors execute the program instructions and are configured to analyze the CA signals over one or more cardiac beats, determine a VA episode based on the analysis of the CA signals, determine a posture of the patient based on the accelerometer data in response to the determination of the VA episode, and select a first VA therapy from the collection of VA therapies based on the posture.