The present disclosure pertains to cardiac pacing methods and systems, and, more particularly, to cardiac resynchronization therapy (CRT). In particular, the present disclosure pertains to determining whether a patient is experiencing atrial fibrillation (AF). If the patient is experiencing AF, the efficacy of CRT is determined. A signal is sensed in response to a ventricular pacing stimulus. Through signal processing, a number of features are parsed from the signal and a determination is made as to whether the ventricular pacing stimulus evoked a response from the ventricle.

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 method is provided. The method includes pacing, by electrodes of a catheter, a heart tissue with pulses. The method includes observing, by the electrodes, a period of electrophysiological repolarization for the heart tissue. The period of electrophysiological repolarization is caused by the pacing. The method also includes measuring, by the electrodes, an electrical signal within the heart tissue after the period of electrophysiological repolarization.

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 device for neurostimulation including an electrode structure for delivering stimulation pulses to a nerve as well as for processing and extracting evoked compound action potentials, wherein the electrode structure comprises at least a first anode, at least a second anode opposing the first anode and a plurality of cathodes arranged between said anodes, wherein said cathodes are asymmetrically arranged with respect to said at least first and second anode to permit evoked compound action potential sensing via the anode electrodes simultaneously with stimulation.

Recovery circuitry for passively recovering charge from capacitances at electrodes in an Implantable Pulse Generator (IPG) is disclosed. The passive recovery circuitry includes passive recovery switches intervening between each electrode node and a common reference voltage, and each switch is in series with a variable resistance that may be selected based on differing use models of the IPG. The passive recovery switches may also be controlled in different modes. For example, in a first mode, the only recovery switches closed after a stimulation pulse are those associated with electrodes used to provide stimulation. In a second mode, all recovery switches are closed after a stimulation pulse, regardless of the electrodes used to provide stimulation. In a third mode, all recovery switches are closed continuously, which can provide protection when the IPG is in certain environments (e.g., MRI), and which can also be used during stimulation therapy itself.

Recovery circuitry for passively recovering charge from capacitances at electrodes in an Implantable Pulse Generator (IPG) is disclosed. The passive recovery circuitry includes passive recovery switches intervening between each electrode node and a common reference voltage, and each switch is in series with a variable resistance that may be selected based on differing use models of the IPG. The passive recovery switches may also be controlled in different modes. For example, in a first mode, the only recovery switches closed after a stimulation pulse are those associated with electrodes used to provide stimulation. In a second mode, all recovery switches are closed after a stimulation pulse, regardless of the electrodes used to provide stimulation. In a third mode, all recovery switches are closed continuously, which can provide protection when the IPG is in certain environments (e.g., MRI), and which can also be used during stimulation therapy itself.

Methods and systems are provided for managing residual charge for multi-point pacing therapy. The method and system provide an electrode configuration that includes an atrial (A) electrode, a right ventricular (RV) electrode and multiple left ventricular (LV) electrodes. The method and system deliver pacing pulses for an MPP therapy, during a first cardiac cycle, from a pulse generator to the electrode configurations. The pacing pulses are separated by pacing pulse (PP) intervals. The method and system dynamically adjust at least one of a timing or a duration of discharge pulses for the residual charge to form a discharge sequence. The method and system activate the discharge pulses based on the discharge sequence, during the first cardiac cycle, to the multiple LV electrodes to distribute the residual charge across the PP intervals.

A pacing system, which is particularly suitable for implantable leadless pacemakers, applies passively-balanced voltage-based pacing pulses, and periodically performs capture verification (evoked response detection) by following a pacing pulse with a current-based active balancing pulse, and then measuring any evoked response provoked by the pacing pulse. The active balancing pulse reduces residual charge on the electrodes used for pulsing, and thereby reduces polarization artifacts that could obscure measurement of the evoked response at the electrodes. The amplitude and pulse width of the active balancing current pulse are defined by measurements made in a few preceding pulses. The pacemaker preferably detects indicia of cardiac contractility, and performs capture verification only when contractility indicates that the patient is physically inactive and emotionally stable.

The present disclosure relates to cardiac evoked response detection and, more particularly, reducing polarization effects in order to detect an evoked response following delivery of a stimulation pulse. An implantable medical device (IMD) is configured to deliver a ventricular pacing pulse. A signal is sensed in response to the ventricular pacing stimulus. A window is placed over the sensed signal to obtain a set of data from the signal after a paced event. The set of data extracted from the sensed signal comprises a maximum amplitude, a maximum time associated with the maximum amplitude, a minimum amplitude, and a minimum time associated with the minimum amplitude. Responsive to processing the extracted data, the window is delayed to avoid polarization effects. A determination is then made as to whether the ventricular pacing stimulus is capturing the paced ventricle in response to determining whether the maximum time is greater than the minimum time.