Abstract: A device includes a signal generator module, a processing module, and a housing. The signal generator module is configured to deliver pacing pulses to an atrium. The processing module is configured to detect a ventricular activation event and determine a length of an interval between the ventricular activation event and a previous atrial event that preceded the ventricular activation event. The processing module is further configured to schedule a time at which to deliver a pacing pulse to the atrium based on the length of the interval and control the signal generator module to deliver the pacing pulse at the scheduled time. The housing is configured for implantation within the atrium. The housing encloses the stimulation generator and the processing module.

Abstract: A method for sensing far-field R-waves in a leadless, intracardiac pacemaker implanted in an atrium of a patient's heart may involve sensing an electrical signal generated by the heart with two electrodes and a first sensing channel and/or a second sensing channel of the pacemaker, comparing a first timing marker from the first sensing channel with a second timing marker from the second sensing channel, and either determining that the sensed signal is a P-wave, if the first and second timing markers indicate that the sensed signal was sensed by the first and second sensing channels within a predetermined threshold of time from one another, or determining that the sensed signal is a far-field R-wave, if the sensed signal is sensed by the second sensing channel and not sensed by the first sensing channel.

Abstract: A medical device system, such as an extra-cardiovascular implantable cardioverter defibrillator ICD, senses R-waves from a first cardiac electrical signal by a first sensing channel and stores a time segment of a second cardiac electrical signal in response to each sensed R-wave. The medical device system determines a morphology parameter correlated to signal noise from time segments of the second cardiac electrical signal, detects a noisy signal segment based on the signal morphology parameter; and withholds detection of a tachyarrhythmia episode in response to detecting a threshold number of noisy signal segments.

Abstract: A medical device system, such as an extra-cardiovascular implantable cardioverter defibrillator ICD, senses R-waves from a first cardiac electrical signal by a first sensing channel and stores a time segment of a second cardiac electrical signal in response to each sensed R-wave. The medical device system determines a morphology parameter correlated to signal noise from time segments of the second cardiac electrical signal, detects a noisy signal segment based on the signal morphology parameter; and withholds detection of a tachyarrhythmia episode in response to detecting a threshold number of noisy signal segments.

Abstract: A medical device, such as an extra-cardiovascular implantable cardioverter defibrillator (ICD), senses R-waves from a first cardiac electrical signal by a first sensing channel and stores a time segment of a second cardiac electrical signal acquired by a second sensing channel in response to each sensed R-wave. The medical device determines at least one noise parameter from a group of the stored time segments of the second cardiac electrical signal, detects noise based on the noise parameter, and withholds detection of a tachyarrhythmia episode in response to detecting the noise.

Abstract: A medical device, such as an extra-cardiovascular implantable cardioverter defibrillator (ICD), senses R-waves from a first cardiac electrical signal by a first sensing channel and stores a time segment of a second cardiac electrical signal acquired by a second sensing channel in response to each sensed R-wave. The ICD determines morphology match scores from the stored time segments of the second cardiac electrical signal and, based on the morphology match scores, withholds detection of a tachyarrhythmia episode. In some examples, the ICD detects T-wave oversensing based on the morphology match scores and withholds detection of a tachyarrhythmia episode in response to detecting the T-wave oversensing.

Abstract: A device includes a signal generator module, a processing module, and a housing. The signal generator module is configured to deliver pacing pulses to an atrium. The processing module is configured to detect a ventricular activation event and determine a length of an interval between the ventricular activation event and a previous atrial event that preceded the ventricular activation event. The processing module is further configured to schedule a time at which to deliver a pacing pulse to the atrium based on the length of the interval and control the signal generator module to deliver the pacing pulse at the scheduled time. The housing is configured for implantation within the atrium. The housing encloses the stimulation generator and the processing module.

Abstract: An implantable medical device system capable of sensing cardiac electrical signals includes a sensing circuit, a therapy delivery circuit and a control circuit. The sensing circuit is configured to receive a cardiac electrical signal and sense a cardiac event in response to the signal crossing a cardiac event sensing threshold. The therapy delivery circuit is configured to deliver an electrical stimulation therapy to a patient's heart via the electrodes coupled to the implantable medical device. The control circuit is configured to control the sensing circuit to set a starting value of the cardiac event sensing threshold and hold the starting value constant for a sense delay interval. The control circuit is further configured to detect an arrhythmia based on cardiac events sensed by the sensing circuit and control the therapy delivery circuit to deliver the electrical stimulation therapy in response to detecting the arrhythmia.

Abstract: An extra-cardiovascular implantable cardioverter defibrillator senses R-waves from a first cardiac electrical signal by a first sensing channel and stores a time segment of a second cardiac electrical signal in response to each sensed R-wave. The ICD determines intervals between successively sensed R-waves and, in response to at least a predetermined number of the intervals being less than a tachyarrhythmia detection interval, analyzes at least a portion of the time segment of the second cardiac electrical signal corresponding to a most recent one of the sensed R-waves to confirm the most recent one of the R-waves. The ICD updates an unconfirmed beat count in response to the most recent one of the R-waves not being confirmed and withholds detection of a tachyarrhythmia episode in response to the unconfirmed beat count being equal to or greater than a rejection threshold.

Abstract: A method and medical device for determining sensing vectors that includes sensing cardiac signals from a plurality of electrodes, the plurality of electrodes forming a plurality of sensing vectors, setting a blanking period and a blanking period adjustment window for the plurality of sensing vectors in response to the sensed cardiac signals, determining first signal differences during the blanking period adjustment window, and adjusting the blanking period in response to the determined first signal differences.

Abstract: An implantable pacemaker is configured to sense a cardiac electrical signal received by a pair of electrodes coupled to the pacemaker, start a pacing escape interval to control a time that a pacing pulse is delivered in a heart chamber, and detecting if the sensed cardiac electrical signal is a crosstalk event that is an electrical pulse delivered to the patient by a different device than the implantable pacemaker. The implantable pacemaker withholds restarting the pacing escape interval in response to sensing the cardiac electrical signal based on detecting the sensed cardiac electrical signal as the crosstalk event.

Abstract: A medical device and associated method for detecting and treating tachyarrhythmias acquires a cardiac signal using electrodes coupled to a sensing module. During an initial detection process, a shockable cardiac rhythm is detected by a processing module configured to compare the cardiac signal to a first set of detection criteria. By analyzing the cardiac signal, the processing module establishes at least one patient-specific detection threshold during the initial detection process. Upon establishing the at least one patient-specific detection threshold, the initial detection process is stopped, and a next detection process is started which includes comparing the cardiac signal to a second set of detection criteria including the at least one patient-specific detection threshold. In some embodiments, user programming of tachyarrhythmia detection parameters is not required.

Abstract: A method for adjusting a pacing rate in a dual-chamber, leadless pacemaker implanted in a heart may involve determining, with a leadless atrial pacemaker implanted in an atrium of the heart, that an intrinsic atrial contraction rate of the atrium is faster than a ventricular contraction rate, transmitting a first signal from the atrial pacemaker to a leadless ventricular pacemaker implanted in a ventricle of the heart to increase a ventricular pacing rate of the ventricular pacemaker, receiving the transmitted first signal with the ventricular pacemaker, and increasing the ventricular pacing rate, based on the received first signal.

Abstract: An implantable medical device system including an atrial pacemaker and a ventricular pacemaker is configured to deliver dual chamber pacing in the presence of atrioventricular block. In response to detecting the AV block, the atrial pacemaker may establish a limited number of selectable pacing rates. The atrial pacemaker selects a rate from the limited number of selectable pacing rates and adjusts the atrial pacing rate to the selected rate. The ventricular pacemaker is configured to establish a ventricular pacing rate that is equivalent to the selected rate in response to detecting the AV block. Other examples are described herein.

Abstract: A medical device is configured to deliver a high-energy electrical stimulation pulse to a patient that produces a post-stimulation polarization signal. A cardiac signal analyzer of the medical device is configured to detect a cardiac electrical signal superimposed on the post-stimulation polarization signal, determine at least one feature of the detected cardiac electrical signal, compare the feature to criteria that differentiate an intrinsic cardiac event during the post-stimulation polarization signal from an evoked response signal and identify the detected cardiac electrical signal as the intrinsic cardiac event if the feature meets the criteria.

Abstract: A medical device is configured to deliver a high-energy electrical stimulation pulse to a patient that produces a post-stimulation polarization signal. A cardiac signal analyzer of the medical device is configured to detect a cardiac electrical signal superimposed on the post-stimulation polarization signal, determine at least one feature of the detected cardiac electrical signal, compare the feature to criteria that differentiate an intrinsic cardiac event during the post-stimulation polarization signal from an evoked response signal and identify the detected cardiac electrical signal as the intrinsic cardiac event if the feature meets the criteria.

Abstract: Techniques and systems for monitoring cardiac arrhythmias and delivering electrical stimulation therapy using a subcutaneous implantable cardioverter defibrillator (SICD) and a leadless pacing device (LPD) are described. For example, the SICD may detect a tachyarrhythmia within a first electrical signal from a heart and determine, based on the tachyarrhythmia, to deliver anti-tachyarrhythmia shock therapy to the patient to treat the detected arrhythmia. The LPD may receive communication from the SICD requesting the LPD deliver anti-tachycardia pacing to the heart and determine, based on a second electrical signal from the heart sensed by the LPD, whether to deliver anti-tachycardia pacing (ATP) to the heart. In this manner, the SICD and LPD may communicate to coordinate ATP and/or cardioversion/defibrillation therapy. In another example, the LPD may be configured to deliver post-shock pacing after detecting delivery of anti-tachyarrhythmia shock therapy.

Abstract: A medical device is configured to receive at least two physical cardiac electrical signals from a patient's heart via electrodes defining at least two physical sensing vectors. The medical device determines a signal feature for each of a plurality of virtual sensing vectors extending at a plurality of angles relative to one of the at least two physical sensing vectors during a known cardiac rhythm, compares the determined signal features and establishes criteria for confirming a suspected condition in response to the comparing.

Abstract: A medical device and medical device system for controlling delivery of therapeutic stimulation pulses that includes a sensing device to sense a cardiac signal and emit a trigger signal in response to the sensed cardiac signal, a therapy delivery device to receive the trigger signal and deliver therapy to the patient in response to the emitted trigger signal, and a processor positioned within the sensing device, the processor configured to determine whether the sensed cardiac signal exceeds a possible P-wave threshold, compare a portion of the sensed cardiac signal to a P-wave template having a sensing window having a length less than a width of the P-wave, confirm an occurrence of a P-wave signal in response to the comparing, emit the trigger signal in response to the occurrence of a P-wave signal being confirmed, and inhibit delivery of the emitting signal in response to the occurrence of a P-wave signal not being confirmed.

Abstract: Techniques and systems for monitoring cardiac arrhythmias and delivering electrical stimulation therapy using a subcutaneous implantable cardioverter defibrillator (SICD) and a leadless pacing device (LPD) are described. For example, the SICD may detect a tachyarrhythmia within a first electrical signal from a heart and determine, based on the tachyarrhythmia, to deliver anti-tachyarrhythmia shock therapy to the patient to treat the detected arrhythmia. The LPD may receive communication from the SICD requesting the LPD deliver anti-tachycardia pacing to the heart and determine, based on a second electrical signal from the heart sensed by the LPD, whether to deliver anti-tachycardia pacing (ATP) to the heart. In this manner, the SICD and LPD may communicate to coordinate ATP and/or cardioversion/defibrillation therapy. In another example, the LPD may be configured to deliver post-shock pacing after detecting delivery of anti-tachyarrhythmia shock therapy.