Systems, methods, and devices are described herein for determining cardiac conduction system capture of ventricle from atrium (VfA) therapy. VfA therapy may be delivered at a plurality of different A-V delays while electrical activity of the patient is monitored. The electrical activity may then be utilized to determine whether the cardiac conduction system of the patient has been captured by the VfA therapy.

An IMD system receives a near field His bundle electrical signal produced by a patient's heart via a first sensing electrode vector and a far field cardiac electrical signal via a second sensing electrode vector different than the first sensing electrode vector. The IMD system generates His bundle pacing pulses delivered to the patient's heart via a His pacing electrode vector and determines a type of cardiac capture evoked by a His bundle pacing pulse.

Ventricle-from-atrium (VfA) cardiac therapy may utilize a tissue-piercing electrode implanted in the left ventricular myocardium of the patient's heart from the right atrium through the right atrial endocardium and central fibrous body. The exemplary devices and methods may determine whether the tissue-piercing electrode is achieving effective left ventricular capture. Additionally, one or more pacing parameters, or paced settings, may be adjusted in view of the effective left ventricular capture determination.

Certain embodiments of the present technology described herein relate to detecting atrial oversensing in a His intracardiac electrogram (His IEGM), characterizing atrial oversensing, determining when atrial oversensing is likely to occur, and or reducing the chance of atrial oversensing occurring. Some such embodiments characterize and/or avoid atrial oversensing within a His IEGM. Other embodiments of the present technology described herein relate to determining whether atrial capture occurs in response to His bundle pacing (HBP). Still other embodiments of the present technology described herein relate to determining whether AV node capture occurs in response to HBP.

Cardiac resynchronization therapy (CRT) delivered to a heart of a patient may be adjusted based on detection of a surrogate indication of the intrinsic atrioventricular conduction of the heart. In some examples, the surrogate indication is determined to be a sense event of the first depolarizing ventricle of the heart within a predetermined period of time following the delivery of a fusion pacing stimulus to the later depolarizing ventricle. In some examples, the CRT is switched from a fusion pacing configuration to a biventricular pacing configuration if the surrogate indication is not detected, and the CRT is maintained in a fusion pacing configuration if the surrogate indication is detected.

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.

Systems and methods for pacing cardiac conductive tissue are described. In an embodiment, a medical system includes an electrostimulation circuit to generate His-bundle pacing (HBP) pulses. A sensing circuit senses an atrial activation. A control circuit detects a retrograde atrial conduction timing, such as a His-to-atrial interval between the HBP pulse and the sensed atrial activation in response to the HBP pulse, and verifies capture status using the determined retrograded atrial conduction timing. Based on the capture status, the control circuit determines a HBP threshold, and the electrostimulation circuit delivers HBP pulses in accordance with the determined HBP threshold.

An implantable medical device configured to provide for an intracardiac function comprises a body, a sensor arrangement arranged on the body and configured to receive cardiac sense signals, and a processing circuitry operatively connected to the sensor arrangement. The processing circuitry is configured to process cardiac sense signals received using the sensor arrangement to detect atrial events caused by atrial activity based on a comparison of the cardiac sense signals to a sense threshold for a number of cardiac cycles, to evaluate whether a reduction criterion is fulfilled, wherein the reduction criterion is fulfilled if in X1 out of Y1 cardiac cycles no atrial events have been detected, X1 being a natural number equal to or larger than 1 and Y1 being a natural number equal to or larger than X1, and to reduce the sense threshold if said reduction criterion is fulfilled.

Certain embodiments of the present technology described herein relate to detecting atrial oversensing, characterizing atrial oversensing, determining when atrial oversensing is likely to occur, and or reducing the chance of atrial oversensing occurring. Some such embodiments characterize and/or avoid atrial oversensing.

Cardiac resynchronization therapy (CRT) delivered to a heart of a patient may be adjusted based on detection of a surrogate indication of the intrinsic atrioventricular conduction of the heart. In some examples, the surrogate indication is determined to be a sense event of the first depolarizing ventricle of the heart within a predetermined period of time following the delivery of a fusion pacing stimulus to the later depolarizing ventricle. In some examples, the CRT is switched from a fusion pacing configuration to a biventricular pacing configuration if the surrogate indication is not detected, and the CRT is maintained in a fusion pacing configuration if the surrogate indication is detected.