Abstract: Response to cardiac resynchronization therapy is predicted for a given stimulation site so that an atrioventricular delay of an implantable device administering cardiac resynchronization therapy may be set to a proper amount. The first deflection of ventricular depolarization is measured, such as through a surface electrocardiogram or through an intracardiac electrogram measured by a lead positioned in the heart at the stimulation site. The maximum deflection of the ventricular depolarization is then measured by the lead positioned at the stimulation site. The interval of time between the first deflection and the maximum deflection of the ventricular depolarization is compared to a threshold to determine whether the stimulation site is a responder site. If the interval is larger than the threshold, then the site is a responder and the atrioventricular delay of the implantable device may be set to less than the intrinsic atrioventricular delay of the patient.

Abstract: Systems and methods for determining pacing timing intervals based on the temporal relationship between the timing of local and non-local cardiac signal features are described. A device includes a plurality of implantable electrodes electrically coupled to the heart and configured to sense local and non-local cardiac signals. Sense circuitry coupled to first and second electrode pairs senses a local cardiac signal via a first electrode pair and a non-local cardiac signal via a second electrode pair. Detection circuitry is used to detect a feature of the local signal associated with activation of a heart chamber and to detect a feature of the non-local signal associated with activation of the heart chamber. A control processor times delivery of one or more pacing pulses based on a temporal relationship between timing of the local signal feature and timing of the non-local signal feature.

Abstract: A pacing system computes optimal cardiac resynchronization pacing parameters using intrinsic conduction intervals. In various embodiments, values for atrio-ventricular delay intervals are each computed as a function of an intrinsic atrio-ventricular interval and a parameter reflective of an interventricular conduction delay. Examples of the parameter reflective of the interventricular conduction delay include QRS width and interval between right and left ventricular senses.

Abstract: Cardiac monitoring and/or stimulation methods and systems that provide one or more of monitoring, diagnosing, defibrillation, and pacing. Cardiac signal separation is employed to detect, monitor, track and/or trend ischemia using cardiac activation sequence information. Ischemia detection may involve sensing composite cardiac signals using implantable electrodes, and performing a signal separation that produces one or more cardiac activation signal vectors associated with one or more cardiac activation sequences. A change in the signal vector may be detected using subsequent separations. The change may be an elevation or depression of the ST segment of a cardiac cycle or other change indicative of myocardial ischemia, myocardial infarction, or other pathological change. The change may be used to predict, quantify, and/or qualify an event such as an arrhythmia, a myocardial infarction, or other pathologic change. Information associated with the vectors may be stored and used to track the vectors.

Abstract: Systems and methods for selection of electrodes and related pacing configuration parameters used to pace a heart chamber are described. A change in the hemodynamic state of a patient is detected. Responsive to the detected change, a distribution of an electrical, mechanical, or electromechanical parameter related to contractile function of a heart chamber with respect to locations of multiple electrodes disposed within the heart chamber is determined. A pacing output configuration, including one or more electrodes of the multiple electrodes, is selected and the heart chamber is paced using the selected pacing output configuration.

Abstract: In a pacing mode where the left ventricle is paced upon expiration of an escape interval that is reset by a right ventricular sense, there is the risk that the left ventricular pace may be delivered in the so-called vulnerable period that occurs after a depolarization and trigger an arrhythmia. To reduce this risk, a left ventricular protective period (LVPP) may be provided. Methods and devices for implementing an LVPP in the context of multi-site left ventricular pacing are described.

Abstract: Biventricular-triggered pacing is a pacing mode that can employ in cardiac resynchronization pacing at elevated heart rates. Described herein are methods and devices for implementing biventricular pacing in the context of multi-site left ventricular pacing.

Abstract: Physiologic demand driven pacing can be used to maintain cardiac synchrony and improve hemodynamic function in patients with heart failure.

Abstract: A non-linear dynamic specified AV delay can be used, such as to help maintain cardiac resynchronization therapy, such as in patients with one or more symptoms of congestive heart failure.

Abstract: A pacing system computes optimal cardiac resynchronization pacing parameters using intrinsic conduction intervals. In various embodiments, values for atrio-ventricular delay intervals are each computed as a function of an intrinsic atrio-ventricular interval and a parameter reflective of an interventricular conduction delay. Examples of the parameter reflective of the interventricular conduction delay include QRS width and interval between right and left ventricular senses.

Abstract: Vector selection is automatically achieved via a thoracic or intracardiac impedance signal collected in a cardiac function management device or other implantable medical device that includes a test mode and a diagnostic mode. During a test mode, the device cycles through various electrode configurations for collecting thoracic impedance data. At least one figure of merit is calculated from the impedance data for each such electrode configuration. In one example, only non-arrhythmic beats are used for computing the figure of merit. A particular electrode configuration is automatically selected using the figure of merit. During a diagnostic mode, the device collects impedance data using the selected electrode configuration. In one example, the figure of merit includes a ratio of a cardiac stroke amplitude and a respiration amplitude. Other examples of the figure of merit are also described.

Abstract: Methods and systems to modulate timing intervals for pacing therapy are described. For each cardiac cycle, one or both of an atrioventricular (A-V) timing interval and an atrial (A-A) timing interval are modulated to oppose beat-to-beat ventricular (V-V) timing variability. Pacing therapy is delivered using the modulated timing intervals.

Abstract: Methods and systems are disclosed for determining whether a patient is a responder to cardiac resynchronization therapy. The beginning and ending of the intrinsic ventricular depolarization are determined through signals measured from one or more electrodes implanted in the patient's heart. An interval between the beginning and ending of the intrinsic ventricular depolarization is computed and is compared to a threshold. The threshold may be determined empirically. The pacing parameters of a heart stimulation device, such as a pacemaker, may then be configured, for example, by setting the paced atrio-ventricular delay based on whether the patient responds positively to cardiac resynchronization therapy.

Abstract: A cardiac arrhythmia can be identified, such as a tachycardia or fibrillation episode (atrial or ventricular). In responses to the detected arrhythmia, a coordinated electrostimulation therapy can be provided using at least one of a defibrillation shock therapy, a pre-shock conditioning therapy, or a post-shock conditioning therapy. The pre-shock or post-shock conditioning therapies can include electrostimulation therapies provided to the natural electrical conduction system of the heart between the atrioventricular node and the Purkinje fibers, inclusive, such as at or near a His bundle of a heart. In an example, a defibrillation threshold can be reduced by providing a pre-shock conditioning electrostimulation therapy to the natural electrical conduction system of the heart between the atrioventricular node and the Purkinje fibers, inclusive, such as at or near a His bundle.

Abstract: A system senses a cardiac signal for diagnostic and/or therapy control purposes using a first set of electrodes and switches to a different second set of electrodes for recognizing cardiac events in the cardiac signal. In various embodiments, the cardiac signal sensed using the second set of electrodes is compared to the cardiac signal sensed using the first set of electrodes, and the cardiac events in the cardiac signal are each recognized using an outcome of the comparison.

Abstract: One way in which cardiac resynchronization therapy may be delivered is to only deliver paces to the left ventricle. If left ventricular pacing is inhibited during a cardiac cycle, it may be desirable to deliver a right ventricular safety pace to prevent asystole. Methods and devices for implementing right ventricular safety pacing in the context of multi-site left ventricular-only pacing are described.

Abstract: A system and method for identifying patients with asynchronous ventricular contractions due to abnormal electro-mechanical coupling and computing optimal pacing parameters for restoring synchronous contractions is disclosed. Such patients may have normal intra-ventricular and inter-ventricular conduction and cannot be identified from intrinsic conduction data alone such as QRS width. Techniques for computing optimal resynchronization pacing in order to compensate for abnormal electro-mechanical coupling are also described.

Abstract: Systems and methods for determining pacing timing intervals based on the temporal relationship between the timing of local and non-local cardiac signal features are described. A device includes a plurality of implantable electrodes electrically coupled to the heart and configured to sense local and non-local cardiac signals. Sense circuitry coupled to first and second electrode pairs senses a local cardiac signal via a first electrode pair and a non-local cardiac signal via a second electrode pair. Detection circuitry is used to detect a feature of the local signal associated with activation of a heart chamber and to detect a feature of the non-local signal associated with activation of the heart chamber. A control processor times delivery of one or more pacing pulses based on a temporal relationship between timing of the local signal feature and timing of the non-local signal feature.

Abstract: A cardiac rhythm management system includes an implantable device executing a dynamic pacing algorithm after an myocardial infarction (MI) event. The dynamic pacing algorithm dynamically adjusts one or more pacing parameters based on a person's gross physical activity level. Examples of the one or more pacing parameters include atrioventricular pacing delays and pacing channels/sites. The dynamic pacing algorithm provides for improved hemodynamic performance when a person's metabolic need is high, and post MI remodeling control when the person's metabolic need is low.

Abstract: A system comprises a cardiac signal sensing and a processing circuit. The cardiac signal sensing circuit senses a first cardiac signal segment that includes a QRS complex and a second cardiac signal segment that includes a fiducial indicative of local ventricular activation. The processor circuit includes a site activation timer circuit configured to determine a time duration between a fiducial of the QRS complex of the first cardiac signal segment and the fiducial of the second cardiac signal segment. The processor circuit is configured to generate, using the determined time duration, an indication of optimality of placement of one or more electrodes for delivering therapy and provide the indication to at least one of a user or process.