An implantable medical device system is configured to sense cardiac events in response to a cardiac electrical signal crossing a cardiac event sensing threshold. A control circuit is configured to determine a drop time interval based on a heart rate and control a sensing circuit to hold the cardiac event sensing threshold at a threshold value during the drop time interval.

An example device includes an elongated housing, a first and second electrode, and signal generation circuitry. The housing can be implanted within a single first chamber of the heart. The first electrode extends distally from the distal end of the elongated housing. A distal end of the first electrode can penetrate into wall tissue of a second chamber of the heart. The second electrode, extending from the distal end of the elongated housing, is configured to flexibly maintain contact with the wall tissue of the first chamber without penetration of the wall tissue of the first chamber by the second electrode. Signal generation circuitry can be within the elongated housing and coupled to the first and second electrode. The signal generation circuitry can deliver cardiac pacing to the second chamber via the first electrode and the first chamber via the second electrode.

A computer implemented method and system are provided for detecting premature ventricular contractions (PVCs) in cardiac activity. The method and system obtain cardiac activity (CA) signals for a series of beats, and, for at least a portion of the series of beats, calculate QRS scores for corresponding QRS complex segments from the CA signals. The method and system calculate a variability metric for QRS scores across the series of beats, calculate a QRS complex template using QRS segments from the series of beats, calculate correlation coefficients between the QRS complex template and the QRS complex segments, compare the variability metric to a variability threshold and the correlation coefficients to a correlation threshold, and designate the CA signals to include a predetermined level of PVC burden based on the determining.

A system includes a pulse generator including a can electrode and a lead couplable to the pulse generator, the lead including a distal coil electrode and a proximal coil electrode, wherein both of the coil electrodes are electrically uncoupled from the can electrode such that a unipolar sensing vector is provided between at least one of the coil electrodes and the can electrode.

In some examples, an implantable medical device (IMD) includes a housing defined in part by a longitudinal axis, a header at a distal end of the housing, the header defining a header plane, the header plane disposed at an angle relative to a reference plane, where the reference plane is perpendicular to the longitudinal axis, a fixation mechanism extending from the header, the fixation mechanism configured to be advanced into tissue of a heart of a patient to fix at least a portion of the IMD to the heart, one or more electrodes that extend from the header and are configured to engage with the septum, and circuitry within the housing, wherein the circuitry is configured to deliver cardiac pacing to the heart via the one or more electrodes.

In an embodiment herein, an aortopulmonary stimulation method is provided including positioning at least one aortic electrode in or near the aorta, and using the at least one aortic electrode, to deliver stimulation to the aorta to decrease aortic after load.

In one embodiment, a medical procedure system includes a probe for insertion into a chamber of a heart of a living subject, and including a first electrode to apply a sequence of pacing pulses at a position in the chamber, a second electrode to sense an electrical activation signal responsively to electrical activations induced by capture of the pacing pulses in a myocardium of the chamber, a display, and processing circuitry to evaluate a successful acquisition by the second electrode of the induced electrical activations responsively to the electrical activation signal, the successful acquisition being indicative of a successful capture of the pacing pulses by the myocardium, compute a capture grade responsively to the evaluation of the successful acquisition of the induced electrical activations, the capture grade being indicative of a count of the induced electrical activations evaluated as being successfully acquired, and render the capture grade to the display.

Modular cardiac rhythm management system and method, including:

a first implantable stimulation device (ISD), and
a second ISD,
wherein the first ISD comprises a first detection unit detecting a patient's cardiac rhythm and a first processor analyzing the detected patient's cardiac rhythm and delivering a first antitachycardia pacing therapy (APT),
wherein the second ISD comprises a second detection unit detecting the patient's cardiac rhythm and a second processor analyzing the detected patient's cardiac rhythm and delivering shock therapy or a second APT, and
wherein the first processor allows delivery of APT only if analysis of the patient's cardiac rhythm within preceding time period A reveals tachycardia criterion A′ and absence of shock therapy, and/or
wherein the second processor allows delivery of shock therapy or second APT only if analysis of the patient's cardiac rhythm within preceding time period B reveals tachycardia criterion B′ and absence of first APT.

The control module of a first pacemaker included in an implantable medical device system including the first pacemaker and a second pacemaker is configured to set a pacing escape interval in response to a far field pacing pulse sensed by the first pacemaker. The far field pacing pulse is a pacing pulse delivered by the second pacemaker. The pacing escape interval is allowed to continue without restarting the in response to a far field intrinsic event sensed by the first pacemaker during the pacing escape interval. The first pacemaker delivers a cardiac pacing pulse to the heart upon expiration of the pacing escape interval.

Synchronized stimulation of cardiac tissue can be implemented by implanting two or more rectifier-based AM receivers into different positions within a subject's heart. Each receiver is tuned to a different frequency, and generates an output signal that is capable of stimulating cardiac tissue when a signal at the corresponding tuned frequency arrives at the receiver. An AM transmitter can activate any given one of the receivers by transmitting a signal into the subject's body at the proper frequency. A controller controls the transmitter by commanding the transmitter to transmit pulses of AC at different frequencies at different times, so that when those pulses are received by the correspondingly-tuned receivers, each of the receivers will generate respective output signals that stimulate respective parts of the heart at respective times to promote improved cardiac performance.