Abstract: Techniques are described for detecting ischemia, hypoglycemia or hyperglycemia based on intracardiac electrogram (IEGM) signals. Ischemia is detected based on a shortening of the interval between the QRS complex and the end of a T-wave (QTmax), alone or in combination with a change in ST segment elevation. Alternatively, ischemia is detected based on a change in ST segment elevation combined with minimal change in the interval between the QRS complex and the end of the T-wave (QTend). Hypoglycemia is detected based on a change in ST segment elevation along with a lengthening of either QTmax or QTend. Hyperglycemia is detected based on a change in ST segment elevation along with minimal change in QTmax and in QTend. By exploiting QTmax and QTend in combination with ST segment elevation, changes in ST segment elevation caused by hypo/hyperglycemia can be properly distinguished from changes caused by ischemia.

Abstract: Tachyarrhythmia is treated by applying anti-tachycardia pacing through at least one multi-site electrode set located on, in or around the heart. The electrode set is arranged and located such that an electrical activation pattern having a wave-front between substantially flat and concave is generated through a reentrant circuit associated with the tachyarrhythmia. The electrode set may be one of a plurality of predefined, multi-site electrode sets located on, in or around the atria.

Abstract: An implantable medical device is provided that comprises a housing, sensors configured to be located to proximate a heart, and a sensing module to sense cardiac signals originating from the heart over a channel defined by the sensors. The cardiac signals include intrinsic R-wave events and associated intrinsic confirmation events when the heart exhibits normal sinus rhythm. The device further includes memory to store the cardiac signals sensed over a channel, and a detection module. The detection module identifies an R-wave event within the cardiac signals. The detection module captures, in the memory, a segment of the cardiac signals that precedes the R-wave event as a retrospective segment. The detection module determines whether the retrospective segment includes an intrinsic confirmation event that is associated with and occurs before the R-wave event.

Abstract: A surface electrocardiogram (EKG) is emulated using signals detected by internal leads of an implanted device. In one example, emulation is performed using a technique that concatenates portions of signals sensed using different electrodes, such as by combining far-field ventricular signals sensed in the atria with far-field atrial signals sensed in the ventricles. In another example, emulation is performed using a technique that selectively amplifies or attenuates portions of a single signal, such as by attenuating near-field portions of an atrial unipolar signal relative to far-field portions of the same signal. The surface EKG emulation may be performed by the implanted device itself or by an external programmer based on cardiac signals transmitted thereto. A transtelephonic monitoring network is also described, wherein the emulated surface EKG (or raw data used to emulate the EKG) is relayed from an implanted device to a remote monitor, typically installed in a physician's office.

Abstract: A surface electrocardiogram (EKG) is emulated using signals detected by the internal leads of an implanted device. In one example, the emulation is performed using a technique that concatenates portions of signals sensed using different electrodes. In another example, the emulation is performed using a technique that selectively amplifies or attenuates portions of a single cardiac signal sensed using a single pair of electrodes. The surface EKG emulation may be performed by the implanted device itself or by an external device, such as a programmer, based on cardiac signals transmitted thereto. The external device then displays the emulated surface EKG along with an intracardiac electrogram (IEGM) and set of event markers. Alternatively, the external device displays an entire set of emulated EKGs that had been generated based on the same patient input data but using different emulation techniques.

Abstract: Tachyarrhythmia is treated by applying anti-tachycardia pacing through at least one multi-site electrode set located on, in or around the heart. The electrode set is arranged and located such that an electrical activation pattern having a wave-front between substantially flat and concave is generated through a reentrant circuit associated with the tachyarrhythmia. The electrode set may be one of a plurality of predefined, multi-site electrode sets located on, in or around the atria. Alternatively, the electrode set may be formed using at least two selectable electrodes located on, in or around the atria.

Abstract: Methods and systems of identifying an electrode or combination of electrodes of a multi-electrode device for pacing include selecting a first electrode or electrode combination as a first candidate; delivering a pacing pulse through the first candidate and determining a measurement based on sensed cardiac electrical activity resulting from the first candidate pacing; selecting a second candidate; delivering a pacing pulse through the second candidate and determining a measurement based on sensed cardiac electrical activity resulting from the second candidate pacing; comparing the measurement for the first and second candidates; and identifying the first or second candidate for pacing based on the comparison. The measurement may be one or more of activation time ?Tact, activation recovery interval (ARI), a fractioned electrogram width, and a standard deviation of a fractioned electrogram feature.

Abstract: Exemplary systems, devices, and methods for considering cardiac ischemia in electrode selection are described. One method determines whether an electrode of a multiple-electrode lead is proximate a region of cardiac ischemia or infarct. The method also paces through a different electrode of the multiple-electrode lead in an instance where the electrode is determined to be proximate the region.

Abstract: An exemplary method includes detecting a change in state of a cardiac valve, detecting elongation of the left ventricle substantially along its major axis, determining a time difference between the change in state of the cardiac valve and the elongation of the left ventricle and, based at least in part on the time difference, deciding whether a diastolic abnormality exists. Other exemplary methods, devices, systems, etc., are also disclosed.

Abstract: Implantable systems and method for use therewith are provided that take advantage of various neuromodulation and neurosensing techniques for either preventing atrial fibrillation (AF) or terminating AF. Specific embodiments are for use with an implantable device that includes one or more atrial electrode for sensing atrial fibrillation (AF) and/or delivering AATP and one or more electrode for monitoring and/or stimulating atrial vagal fat pads.

Abstract: An implanted cardiac rhythm management device is disclosed that is operative to detect myocardial ischemia. This is done by evaluating electrogram features to detect an electrocardiographic change; specifically, changes in electrogram segment during the early part of an ST segment. The early part of the ST segment is chosen to avoid the T-wave.

Abstract: An exemplary method includes detecting arrhythmia, detecting myocardial ischemia, determining whether the myocardial ischemia comprises local ischemia or global ischemia and, in response to the determining, calling for delivery of either a local ischemic anti-arrhythmia therapy or a global ischemic anti-arrhythmia therapy. Various other exemplary methods, devices, systems, etc., are also disclosed.

Abstract: An exemplary method includes detecting a change in state of a cardiac valve, detecting elongation of the left ventricle substantially along its major axis, determining a time difference between the change in state of the cardiac valve and the elongation of the left ventricle and, based at least in part on the time difference, deciding whether a diastolic abnormality exists. Other exemplary methods, devices, systems, etc., are also disclosed.

Abstract: An implantable system terminates atrial fibrillation by applying optimized anti-tachycardia pacing (ATP). In one implementation, the system senses and paces at multiple sites on the left atrium. At each site, the system senses reentrant circuits causing the atrial fibrillation. In one implementation, the system applies ATP tuned to the frequency of the reentrant circuit at the electrode that senses the most regular reentrant circuit. In another implementation, the system applies ATP at multiple electrodes, delivering each pulse at each site when the excitable gap is near the site. In other variations, the ATP is optimized for different patterns of sequential, simultaneous, or syncopated delivery to terminate the atrial fibrillation. The system can also monitor multiple heart chambers for cardiac events that favor terminating atrial fibrillation via ATP. The system then times delivery of the ATP according to these cardiac events.

Abstract: Implantable systems, and method for use therewith, are provided that take advantage of various neuromodulation and neurosensing techniques for either preventing atrial fibrillation (AF) or terminating AF. Specific embodiments, as will be described below, are for use with an implantable device that include one or more atrial electrode for sensing atrial fibrillation (AF) and/or delivering AATP and one or more electrode for monitoring and/or stimulating atrial vagal fat pads.

Abstract: A Fast Fourier Transform (FFT) converts time-varying event waveforms into the frequency domain waveforms to thereby decompose the events into their spectral components, which are analyzed to distinguish R-waves from T-waves. In some embodiments, the FFT is only activated if a ventricular tachyarrhythmia is already indicated. For example, an initial ventricular rate may be derived from a ventricular IEGM based on all events detected therein. The initial ventricular rate is compared against one or more thresholds representative of ventricular tachycardia (VT) and/or ventricular fibrillation (VF) to determine if VT/VF is indicated. If so, the FFT is activated to distinguish R-waves from T-waves and, in particular, to detect and eliminate T-wave oversensing. Then, the ventricular rate is re-determined based only on the rate of true R-waves. Therapy is delivered if VT/VF is still detected.

Abstract: An implanted cardiac rhythm management device is disclosed that is operative to detect myocardial ischemia. This is done by evaluating electrogram features to detect an electrocardiographic change; specifically, changes in electrogram segment during the early part of an ST segment. The early part of the ST segment is chosen to avoid the T-wave.

Abstract: An implantable system terminates atrial fibrillation by applying optimized anti-tachycardia pacing (ATP). In one implementation, the system senses and paces at multiple sites on the left atrium. At each site, the system senses reentrant circuits causing the atrial fibrillation. In one implementation, the system applies ATP tuned to the frequency of the reentrant circuit at the electrode that senses the most regular reentrant circuit. In another implementation, the system applies ATP at multiple electrodes, delivering each pulse at each site when the excitable gap is near the site. In other variations, the ATP is optimized for different patterns of sequential, simultaneous, or syncopated delivery to terminate the atrial fibrillation. The system can also monitor multiple heart chambers for cardiac events that favor terminating atrial fibrillation via ATP. The system then times delivery of the ATP according to these cardiac events.

Abstract: Techniques are described for efficiently detecting and distinguishing among cardiac ischemia, hypoglycemia or hyperglycemia based on intracardiac electrogram (IEGM) signals. In one example, a preliminary indication of an episode of cardiac ischemia is detected based on shifts in ST segment elevation within the IEGM. In response, the implanted device then records additional IEGM data for transmission to an external system. The external system analyzes the additional IEGM data to confirm the detection of cardiac ischemia using a more sophisticated analysis procedure exploiting additional detection parameters. In particular, the external system uses detection parameters capable of distinguishing hypoglycemia, hyperglycemia and hyperkalemia from cardiac ischemia, such as QTmax and QTend intervals. Alternatively, the more sophisticated analysis procedure may be performed by the device itself, if it is so equipped. Other examples described herein pertain instead to the detection of atrial fibrillation.

Abstract: An implantable device may employ anodal-based cardiac stimulation to improve hemodynamics. Anodal pacing may be provided on a conditional basis (e.g., upon detection of a defined condition). An implantable device may provide anodal pacing or cathodal pacing according to a defined ratio. An implantable device may use automatic capture detection to determine a pacing energy level that provides effective anodal pacing while attempting to minimize the power consumption associated with the anodal pacing.