A system for treating cardiac arrhythmias comprising a generator including: a sensing circuitry configured to evaluate one or more identified signals representative of electrical activity of the heart and detect an arrhythmia, a control circuitry that is configured to control delivery of a therapy in response to the detected arrhythmia, the therapy including a first stage of electrical pulses delivered via at least a first electrode, wherein the first set of electrical pulses is configured to destabilize and/or terminate a reentry associated with the arrhythmia, and a first lead coupled to the generator, wherein the first lead includes the first electrode.

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.

Method for recovering and stabilizing normal heart rate of patients suffering in or being inclined to having atrial fibrillation, comprising the step of sensing primary electrical pulses generated in the right atrium (1), of generating artificial electrical stimulation pulses coordinated with the sensed pulses and stimulating therewith the portion of the left atrium (9) which is remote from the right atrium (1), whereby increasing the areas of the heart muscles that can be reached during a simulation pulse within a predetermined period of time.

Systems and methods are described herein for selection of a cardiac cycle, or heartbeat, from a plurality of cardiac cycles monitored over time. The cardiac cycle may be selected using various metrics including a single-cycle metric and a cycle-series metric. Further, the selected cardiac cycle may be used for further cardiac analysis (for example, to generate electrical activation times).

An implantable medical system may provide atrioventricular synchronous pacing using the ventricular septal wall. The system may include a ventricular electrode coupled to an intracardiac housing or a first medical lead implantable in the ventricular septal wall of the patient's heart to deliver cardiac therapy to or sense electrical activity of the left ventricle of the patient's heart and a right atrial electrode coupled to a leadlet or second medical lead to deliver cardiac therapy to or sense electrical activity of the right atrium of the patient's heart. A right ventricular electrode may be coupled to the intracardiac housing or the first medical lead and implantable in the ventricular septal wall of the patient's heart to deliver cardiac therapy to or sense electrical activity of the right ventricle of the patient's heart.

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.

Methods and devices herein are provided for managing atrial (A) pacing in connection with premature atrial contracts (PAC). The methods and devices obtain an atrial pace-on-PAC (APAC) interval and cardiac activity (CA) signals. The methods and devices are configured to: i) during a first cardiac beat; following a ventricular paced (VP) or ventricular sensed (VS) event, activate a timer for a post ventricular-atrial refractory period (PVARP) interval; and determine whether a first atrial refractory (AR) event occurs during the PVARP interval; ii) during a second cardiac beat; in response to the detecting that the first AR event occurred, initiate an APAC interval; during the APAC interval for the second cardiac beat, determine whether a second AR event occurs; and update a count of APAC events when the second AR event occurs; and iii) repeat i) and ii) for multiple cardiac beats, to track the count of APAC events.

A ventricular pacemaker is configured to determine a ventricular rate interval by determining at least one ventricular event interval between two consecutive ventricular events and determine a rate smoothing ventricular pacing interval based on the ventricular rate interval. The pacemaker is further configured to detect an atrial event from a sensor signal and deliver a ventricular pacing pulse in response to detecting the atrial event from the sensor signal. The pacemaker may start the rate smoothing ventricular pacing interval to schedule a next pacing pulse to be delivered upon expiration of the rate smoothing ventricular pacing interval.

An implantable system including an atrial leadless pacemaker (aLP) and a ventricular leadless pacemaker (vLP), and methods for use therewith, are configured or used to terminate a pacemaker mediated tachycardia (PMT). In an embodiment, in response to the aLP detecting a PMT, the aLP initiates a PMT PA interval, and the aLP does not inform the vLP, via an i2i communication, of an atrial sensed event that caused the PMT to be detected, thereby preventing the vLP from initiating a PV interval during the PMT PA interval. The aLP selectively terminates the PMT PA interval. Additionally, the aLP informs the vLP, via an i2i communication, of an intrinsic atrial event being detected during the PMT PA interval, or of an atrial paced event being performed in response to the PMT PA interval expiring without an intrinsic atrial event being detected during the PMT PA interval.

An implantable medical device system delivers a pacing pulse to a patient's heart and starts a first pacing interval corresponding to a pacing rate in response to the delivered pacing pulse. The system charges a holding capacitor to a pacing voltage amplitude during the first pacing interval. The system detects an increased intrinsic heart rate that is at least a threshold rate faster than the current pacing rate from a cardiac electrical signal received by a sensing circuit of the implantable medical device. The system starts a second pacing interval in response to an intrinsic cardiac event sensed from the cardiac electrical signal and withholds charging of the holding capacitor for at least a portion of the second pacing interval in response to detecting the increased intrinsic heart rate.