Abstract: An implantable medical device can include a therapy circuit coupled to a therapy delivery terminal, the therapy circuit configured to generate a specified electrostimulation therapy for delivery to a tissue site via the therapy delivery terminal, and a measurement circuit for measuring at least two impedances of a first terminal combination including the therapy delivery terminal, the two impedances corresponding to at least two instances of excitation separated enough in time to capture an impedance artifact due at least in part to a motion of the heart, such as to determine an electrostimulation therapy lead status at least in part using the at least two impedances.

Abstract: A method and system for generating a characterization of one beat of a patient's supraventricular rhythm (SVR) involves performing such characterization while the heart is being paced. During SVR characterization, various pacing parameters are modified and the patient's supraventricular rhythm is characterized while the pacing parameters are modified. The SVR characterization process is effective in single and multiple chamber pacing modes.

Abstract: An implantable medical device can include a therapy circuit coupled to a therapy delivery terminal, the therapy circuit configured to generate a specified electrostimulation therapy for delivery to a tissue site via the therapy delivery terminal, and a measurement circuit for measuring at least two impedances of a first terminal combination including the therapy delivery terminal, the two impedances corresponding to at least two instances of excitation separated enough in time to capture an impedance artifact due at least in part to a motion of the heart, such as to determine an electrostimulation therapy lead status at least in part using the at least two impedances.

Abstract: A method and system for generating a characterization of one beat of a patient's supraventricular rhythm (SVR) involves performing such characterization while the heart is being paced. During SVR characterization, various pacing parameters are modified and the patient's supraventricular rhythm is characterized while the pacing parameters are modified. The SVR characterization process is effective in single and multiple chamber pacing modes.

Abstract: Methods and systems are directed to detecting atrial tachyarrhythmia. A plurality of A-A intervals is detected. The detected A-A intervals are selected and used to detect atrial tachyarrhythmia. Selecting A-A intervals may be based on determining that A-A intervals are qualified. Qualified A-A intervals may be determined if a duration of the particular A-A interval falls outside a predetermined duration range, for example. Qualified A-A intervals may also be determined based on events occurring between consecutively sensed atrial events of the particular A-A interval, and whether the duration of the particular A-A interval falls within the predetermined duration range, for example.

Abstract: Methods and systems are directed to detecting atrial tachyarrhythmia. A plurality of A-A intervals is detected. The detected A-A intervals are selected and used to detect atrial tachyarrhythmia. Selecting A-A intervals may be based on determining that A-A intervals are qualified. Qualified A-A intervals may be determined if a duration of the particular A-A interval falls outside a predetermined duration range, for example. Qualified A-A intervals may also be determined based on events occurring between consecutively sensed atrial events of the particular A-A interval, and whether the duration of the particular A-A interval falls within the predetermined duration range, for example.

Abstract: Methods and systems are directed to detecting atrial tachyarrhythmia. A plurality of A-A intervals is detected. The detected A-A intervals are selected and used to detect atrial tachyarrhythmia. Selecting A-A intervals may be based on determining that A-A intervals are qualified. Qualified A-A intervals may be determined if a duration of the particular A-A interval falls outside a predetermined duration range, for example. Qualified A-A intervals may also be determined based on events occurring between consecutively sensed atrial events of the particular A-A interval, and whether the duration of the particular A-A interval falls within the predetermined duration range, for example.

Abstract: An atrial defibrillation system includes an implantable atrial defibrillator having an atrial defibrillation detector for detecting atrial fibrillation and a cardioverter for cardioverting the atria of a heart. The implantable atrial defibrillator further includes a receiver for receiving commands from an external nonimplanted transmitter. A nonimplantable communication device includes a transmitter for transmitting a command to the receiver. The command causes only the atrial fibrillation detector to be activated resulting only in the detection for atrial fibrillation without committing to atrial fibrillation cardioversion should atrial fibrillation be detected.

Abstract: An implantable atrial defibrillator includes at least one lead for sensing electrical activity of a heart, a synchronizing stage for providing a synchronizing signal upon detection of an R wave, a timer for timing time intervals between immediately successive R waves, and a cardiovertor for cardioverting the heart when a cardiac interval is greater than a determined minimum time interval and in timed relation to a synchronizing signal. The defibrillator further includes first and second R wave detection channels, the first R wave detection channel providing the synchronizing stage with specific R wave detection, and the second R wave detection channel providing the timer with sensitive R wave detection.

Abstract: An implantable atrial defibrillator applies cardioverting electrical energy to the atria of a human heart in need of cardioversion after first determining if there is an absence of potential atrial fibrillation. A sensor associated with the atria of the heart senses activity of the heart and generates a cardiac signal and a first detector detects cardiac events from the cardiac signal. A second detector responsive to time spans between immediately successive detected cardiac events which are grater in duration than a preselected interval detects for an absence of potential atrial fibrillation. An atrial fibrillation detector detects for atrial fibrillation if the second detector fails to detect an absence of atrial fibrillation, and a cardiovertor applies cardioverting electrical energy to the atria when the atria are in fibrillation.

Abstract: An atrial defibrillator and method provides cardioverting electrical energy to the atria of a human heart after timing successive R to R intervals. A detector detects ventricular activations of the heart and a timer times intervals between immediately successive ventricular activations. A cardiovertor applies cardioverting electrical energy to the atria of the heart when a second time interval between a third ventricular activation and a second ventricular activation immediately preceding the third ventricular activation satisfies a predetermined criteria with respect to a first time interval between the second ventricular activation and a first ventricular activation immediately preceding the second ventricular activation.

Abstract: An atrial defibrillation system includes an implantable atrial defibrillator having an atrial defibrillation detector for detecting atrial fibrillation and a cardioverter for cardioverting the atria of a heart. The implantable atrial defibrillator further includes a receiver for receiving commands from an external nonimplanted transmitter. A nonimplantable communication device includes a transmitter for transmitting a command to the receiver. The command causes only the atrial fibrillation detector to be activated resulting only in the detection for atrial fibrillation without committing to atrial fibrillation cardioversion should atrial fibrillation be detected.