Systems and methods for pacing cardiac conductive tissue are described. In an embodiment, a medical system includes an electrostimulation circuit to generate pacing pulses to stimulate a His bundle or a bunch branch. A sensing circuit senses a far-field ventricular activation, determines a cardiac synchrony indicator using the far-field ventricular activation in response to His bundle or bundle branch pacing, and verifies His-bundle capture status using the determined cardiac synchrony indicator. The system can determine a pacing threshold using the capture status under different stimulation strength values. The electrostimulation circuit can deliver stimulation pulses in accordance with the determined pacing threshold.

An implantable medical device for stimulating a heart, includes a stimulation electrode configured to stimulate a first cardiac region of the heart, and a detection unit configured to detect an intracardiac electrogram at a second cardiac region (ventricle) of the heart. In operation, the device: delivers a stimulation pulse to the heart; evaluates a time and at least one morphologic parameter of a responsive signal of an intracardiac electrogram, wherein the at least one morphologic parameter is chosen from: an absolute value of the signal amplitude, a width of the signal, a positive, negative and/or total area under at least a part of the signal, and a number of occurrences and/or time of occurrence of zero crossings of the signal; and identifies a dislocation of the stimulation electrode if the time of the signal is below a first threshold value and the morphologic parameter exceeds a further threshold value.

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.

An implantable system for stimulating a human/animal heart, comprising a processor, a memory unit, a stimulation unit, a sensing unit, and a diagnostic unit. The system carries out: a) detecting whether at least one malfunction state of the system is present; b) checking whether an electrode provided for stimulating a His bundle of a heart is connected to the stimulation unit; c) switching an operating state of the system into a safety mode when a malfunction state was detected, the safety mode selected from a first safety mode and a second safety mode, wherein i) the first safety mode is selected when no electrode provided for stimulating a His bundle of a heart is connected to the stimulation unit, and ii) the second safety mode is selected when an electrode provided for stimulating a His bundle of a heart is connected to the stimulation unit.

An extra-cardiovascular implantable cardioverter defibrillator (ICD) having a low voltage therapy module and a high voltage therapy module is configured to select, by a control module of the ICD, a pacing output configuration from at least a low-voltage pacing output configuration of the low voltage therapy module and a high-voltage pacing output configuration of the high voltage therapy module. The high voltage therapy module includes a high voltage capacitor having a first capacitance and the low voltage therapy module includes a plurality of low voltage capacitors each having up to a second capacitance that is less than the first capacitance. The ICD control module controls a respective one of the low voltage therapy module or the high voltage therapy module to deliver extra-cardiovascular pacing pulses in the selected pacing output configuration via extra-cardiovascular electrodes coupled to the ICD.

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.

An implantable medical device for stimulating a heart, comprising a control unit, a memory unit, a stimulation unit for stimulating a cardiac region of a heart, and a detection unit for detecting an electrical signal of the heart. The memory unit comprises a computer-readable program that causes the control unit to perform the following steps: a) detecting capture thresholds during an observation period, each capture threshold detected in response to a sequence of pacing pulses delivered by the stimulation unit; b) storing the detected capture thresholds in the memory unit; c) determining threshold-to-threshold differences between two consecutive capture thresholds; and d) if a maximum determined threshold-to-threshold difference within the observation period is equal to or greater than a predetermined limit, adjusting a pacing output of the stimulation unit based on the maximum capture threshold determined within a first time period which is equal to or shorter than the observation period.

A medical device is configured to sense at least one cardiac electrical signal and generate pacing pulses according to a first pacing therapy by generating pacing pulses for delivery to a first combination of ventricular pacing sites including at least one ventricular conduction system pacing site. The medical device may be configured to determine a ventricular conduction condition based on a QRS signal feature of the sensed cardiac signal during the first pacing therapy. The medical device may change to a second pacing therapy different than the first pacing therapy based on the determined ventricular conduction condition.

An extra-cardiovascular implantable cardioverter defibrillator (ICD) having a low voltage therapy module and a high voltage therapy module is configured to select, by a control module of the ICD, a pacing output configuration from at least a low-voltage pacing output configuration of the low voltage therapy module and a high-voltage pacing output configuration of the high voltage therapy module. The high voltage therapy module includes a high voltage capacitor having a first capacitance and the low voltage therapy module includes a plurality of low voltage capacitors each having up to a second capacitance that is less than the first capacitance. The ICD control module controls a respective one of the low voltage therapy module or the high voltage therapy module to deliver extra-cardiovascular pacing pulses in the selected pacing output configuration via extra-cardiovascular electrodes coupled to the ICD.

An example system includes memory configured to store a plurality of lead impedances (LeadZs) and processing circuitry communicatively coupled to the memory. The processing circuitry is configured to determine a first sensed LeadZ, and determine a second sensed LeadZ. The processing circuitry is configured to determine a first difference between the first sensed LeadZ and the second sensed LeadZ, and determine a parameter based at least in part on the first difference. The first sensed LeadZ and the second sensed LeadZ are sensed during a same first cardiac cycle or adjacent cardiac cycles of a heart that is receiving pacing.