Abstract: An intrinsic inter-atrial conduction delay is determined by a pacemaker or implantable cardioverter-defibrillator based, at least in part, on far-field atrial events sensed using ventricular pacing/sensing leads. An atrioventricular pacing delay is then set based on the inter-atrial conduction delay. By detecting atrial events using ventricular leads, rather than using atrial leads, a more useful measurement of the intrinsic inter-atrial conduction delay can be obtained. In this regard, since atrial electrodes detect atrial activity locally around the electrodes, a near-field atrial event sensed using an atrial electrode might not properly represent the actual timing of the atrial event across both the right and left atria. Far-field atrial events sensed using ventricular leads thus allow for a more useful measurement of inter-atrial conduction delays for use in setting atrioventricular pacing delays.

Abstract: An intrinsic inter-atrial conduction delay is determined by a pacemaker or implantable cardioverter-defibrillator based, at least in part, on far-field atrial events sensed using ventricular pacing/sensing leads. An atrioventricular pacing delay is then set based on the inter-atrial conduction delay. By detecting atrial events using ventricular leads, rather than using atrial leads, a more useful measurement of the intrinsic inter-atrial conduction delay can be obtained. In this regard, since atrial electrodes detect atrial activity locally around the electrodes, a near-field atrial event sensed using an atrial electrode might not properly represent the actual timing of the atrial event across both the right and left atria. Far-field atrial events sensed using ventricular leads thus allow for a more useful measurement of inter-atrial conduction delays for use in setting atrioventricular pacing delays.

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: Methods and systems are presented for using an ICD to detect myocardial ischemia. One such method includes sensing via an implantable cardiac-rhythm-management device (ICRMD) a signal indicative of cardiac pressure; determining via a processor associated with the ICRMD, a derivative signal that is a first derivative of the sensed signal; measuring via the processor, a maximum positive value of the derivative signal; measuring via the processor, a maximum negative value of the derivative signal; and indicating via the processor, an ischemia based on a comparison of a ratio of the maximum positive value to the maximum negative value with a predetermined value.

Abstract: Methods and systems are presented for using an ICD to detect myocardial ischemia. In one embodiment, a method includes sensing a signal indicative of cardiac pressure, measuring a height of the sensed signal at a peak amplitude of the sensed signal, and measuring a duration of the sensed signal. The method further includes indicating an ischemia based on a comparison of a ratio of the height to the duration with a predetermined value. In another embodiment, a method includes sensing a signal indicative of cardiac pressure, determining a derivative signal that is a first derivative of the sensed signal, measuring a maximum positive value of the derivative signal, and measuring a maximum negative value of the derivative signal. The method further includes indicating an ischemia based on a comparison of a ratio of the maximum positive value to the maximum negative value with a predetermined value.

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: The implantable device is capable of performing thermal dilution analysis of the cardiac output of a patient using power delivered from an external source. By using power from an external source, the implantable device conserves its power resources for other purposes, such as for pacing or defibrillation therapy. In one example, an external programmer or bedside monitor provides power through a hand-held power delivery wand via electromagnetic induction, with the power routed from a subcutaneous coil to a heating element implanted in the right atrium, which heats blood as it passes through the right atrium. In another example, the heating element is formed of a material that generates heat in response to a beam of ultrasound provided by the wand. In either case, a downstream blood temperature profile is detected using a thermistor implanted in the pulmonary artery and cardiac output is then estimated by analyzing the temperature profile.

Abstract: An exemplary method includes providing a first value indicative of electrode polarization, delivering a cardiac stimulus and determining a second value indicative of electrode polarization associated with the cardiac stimulus, comparing the second value to the first value to determine whether a change in cardiac condition has occurred and, based at least in part on the comparing, deciding whether to adjust a cardiac stimulation therapy.

Abstract: An implantable cardiac system including an implantable cardiac stimulation device provides a heart activity signal of a heart facilitating measurement of slowly changing electrogram features. The system comprises at least one implantable electrode arrangement that senses cardiac electrical activity and provides an intracardiac electrogram signal, a first high pass filter that filters the electrogram and an equalizer that filters the filtered electrogram signal. The equalizer has a transfer function that is non-decreasing for frequencies up to a lower frequency breakpoint that is less than the upper frequency breakpoint, decreasing for frequencies between the lower frequency breakpoint and the upper frequency breakpoint, and generally flat for frequencies above the upper frequency breakpoint through a bandpass region of interest.

Abstract: Detection of atrial fibrillation involves detecting a plurality of ventricular events and obtaining a series of probabilities of AF, each corresponding to a probability of AF for a different beat window having a plurality of ventricular events. AF onset is detected when one or each of a plurality of consecutive AF probabilities satisfies an AF trigger threshold. AF termination is detected when one or each of a plurality of consecutive AF probabilities does not satisfy the AF trigger threshold. Upon detection of AF onset, ventricular events are processed to detect for a sudden onset of irregularity of the ventricular events. AF onset is confirmed when sudden onset is detected and overturned when sudden onset is not detected.

Abstract: Pattern classification techniques are provided for use with an implantable medical device for detecting cardiac ischemia substantially in real-time. Values representative of morphological features of electrical cardiac signals are detected by the implantable medical device. Then, a determination is made as to whether the patient is subject to an on-going episode of cardiac ischemia by applying the values to a pattern classifier configured to identify patterns representative of cardiac ischemia. In one example, the determination is made substantially in real-time by the device itself based on the IEGM signals it detects. In other examples, the IEGM signals are relayed promptly to a bedside monitor or other external device, which analyzes the signals using the pattern classifier to detect ischemia. Therapy may be applied in response to cardiac ischemia. For example, if the implanted device is equipped with a drug pump, appropriate medications may be administered such as anti-thrombolytics.

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: 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: 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: Morphological features within electrical cardiac signals are tracked and feature changes are monitored to detect renal failure. The morphological feature may be an interval between corresponding polarization events such as the interval between QRS-complexes and peaks of corresponding T-waves (QTmax interval); the interval between QRS-complexes and ends of corresponding T-waves (QTend interval); or the interval between P-waves and corresponding QRS-complexes (PR interval). The feature may also be the elevation of a cardiac signal segment between corresponding polarization events, such as QRS-complexes and corresponding T-waves (ST segment); a duration of a polarization event, such as a QRS-complex (QRS width); or an amplitude of a polarization event, such as a T-wave (T-wave amplitude). The change in the feature may comprise a decrease in QTmax intervals, a decrease in QTend intervals, a deviation in ST segment elevation, an increase in QRS width, an increase in PR interval or a deviation in T-wave amplitude.

Abstract: An implantable cardiac device is used to measure one or more parameters relating to cardiac activity of a patient's heart, from which diastolic heart failure (“DHF”) may be monitored and/or detected. These parameters are used to calculate ventricular isovolumetric relaxation time or a related time value. Heart conditions possibly having an influence on the ventricular isovolumetric relaxation time, other than heart conditions due to reduced compliance, may be detected and used to prevent an incorrect calculation of the ventricular isovolumetric relaxation time. The parameters may be measured and the relaxation time calculated multiple times over a period of time, which enables monitoring of the progression of change in the relaxation time. The relaxation time and the progression of change therein are indicators of DHF.

Abstract: Techniques are provided for use by an implantable medical device for determining optimal or preferred atrioventricular (AV) pacing delay values for use in pacing the heart. Briefly, the atria and ventricles are paced using an initial AV pacing delay set to a value less than an intrinsic AV conduction delay so that intrinsic ventricular depolarizations are avoided. An internal electrical cardiac signal is sensed and atrial evoked responses and subsequent ventricular evoked responses are identified therein. Time delays between the atrial and ventricular evoked responses are measured and then a preferred or optimal AV pacing delay value is determined based on: the initial AV pacing delay; the measured time delays between the atrial and ventricular evoked responses; and on a predetermined preferred time delay to be achieved between atrial and ventricular evoked responses. Similar procedures are employed in connection with atrial sensed events. A calibration procedure is also described.

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: A method for operating an implantable medical device includes determining the difference of the absolute value of the voltage of a test QRS complex and the voltage of a baseline QRS template at a plurality of corresponding sample points and detecting ischemia if the sum of the differences at the plurality of sample points is greater than an ischemia detection threshold.

Abstract: Techniques are provided for detecting left ventricular end diastolic pressure (LV EDP) using a pressure sensor implanted within the heart of a patient and for detecting and evaluating heart failure and pulmonary edema based on LV EDP. Briefly, the peak of the R-wave of an intracardiac electrogram (IEGM) is used to trigger the measurement of a pressure value within the left ventricle. This pressure value is deemed to be representative of LV EDP. In this manner, LV EDP is easily detected merely by measuring pressure at one point within the heartbeat—thereby eliminating any need to track ventricular pressure throughout the heartbeat. Techniques for detecting and evaluating heart failure and pulmonary edema based on the R-wave triggered LV EDP measurements are also set forth herein.