Abstract: An implantable cardiac stimulation device, such as a pacemaker or Implantable Cardioverter Defibrillator, is configured to automatically monitor the effects of antiarrhythmic drugs on cardiac electrical signals within a patient to verify the efficacy of the drugs taken. In one example, an analysis of patient cardiac electrical signals is performed by comparing the cardiac electrical signals with values representative of the effects of different classes of antiarrhythmic drugs. If the implantable device determines that the prescribed antiarrhythmic drugs have not been effective, a warning signal is generated. The warning signal is conveyed directly to the patient via a bedside monitor and to the patient's physician via remote connection to an external programmer device so that both are notified of the drug efficacy problems.

Abstract: A technique is provided for filtering far-field electrical cardiac signals from near-field signals. Atrial tip and ring signals are sensed using unipolar electrodes and any timing differences between corresponding events within the signals are detected. Then, far-field signals are filtered from the tip and ring signals based on the detected timing differences, such that substantially only near-field atrial signals remain. The technique exploits the fact that near-field atrial signals are sensed when a conduction wave passes by the atrial electrodes. In contrast, far-field signals from the ventricles propagate to the atrium at near the speed of light. Hence, any significant timing difference between corresponding events appearing in the atrial signals is indicative of a near-field event, whereas the lack of a significant timing difference is indicative of a far-field event. In one example, a sense amplifier is provided with a Boolean logic circuit to aid in time delay-based filtering.

Abstract: An exemplary method includes providing an overdrive pacing rate, based at least in part on the overdrive pacing rate, determining an incidence limit for incidence of intrinsic atrial activity events, determining an incidence of intrinsic atrial activity events, comparing the incidence of intrinsic atrial activity events to the incidence limit and, based at least on the comparing, deciding whether to adjust the overdrive pacing rate. According to this exemplary method, the incidence limit is optionally a function of overdrive pacing rate. Another exemplary method includes determining a dwell limit wherein the dwell limit is optionally a function of overdrive pacing rate. Other exemplary methods, devices, systems, etc., are also disclosed.

Abstract: An exemplary method includes providing an overdrive pacing rate, based at least in part on the overdrive pacing rate, determining an incidence limit for incidence of intrinsic atrial activity events, determining an incidence of intrinsic atrial activity events, comparing the incidence of intrinsic atrial activity events to the incidence limit and, based at least on the comparing, deciding whether to adjust the overdrive pacing rate. According to this exemplary method, the incidence limit is optionally a function of overdrive pacing rate. Another exemplary method includes determining a dwell limit wherein the dwell limit is optionally a function of overdrive pacing rate. 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: 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: An implantable cardiac stimulation device is configured to generate multiphasic stimulation pulse waveforms. These multiphasic stimulation pulse waveforms are configured such that they can be substantially rejected within the intracardiac signal sensing circuitry. In certain implementations this allows for simultaneous stimulation therapy and sensing and analysis of intracardiac signals. In other implementations, the blanking interval associated with the intracardiac signal sensing circuitry may be reduced or eliminated. Furthermore, the fast recharge period may be reduced or eliminated, and/or the polarization at lead-tissue interface may be reduced or effectively eliminated by using multiphasic stimulation pulse waveforms. Such cardiac stimulation techniques are particularly useful in providing antitachycardia pacing (ATP) therapy, wherein pacing during a T wave can lead to fibrillation being triggered.

Abstract: An implantable cardiac stimulation device is described wherein a controller of the cardiac stimulation device controls selected functions of the device based on whether the patient is at rest and further based on whether the patient is prone to vagally-mediated arrhythmias. Functions of the device that may be controlled include, for example, a pacing base rate, an AV/PV delay, and a refractory period as well as overdrive pacing parameters and diagnostic data gathering parameters. In one example, if the patient is not prone to vagally-mediated arrhythmias, the base rate is lowered while the patient is at rest. Also, overdrive pacing parameters are set to be less aggressive. As such, the operation of the cardiac stimulation device is controlled to make it easier for the patient to rest while also reducing power consumption. However, if the patient is prone to vagally-mediated arrhythmias, the base rate is not lowered while the patient is at rest.

Abstract: An implantable cardiac stimulation device is described wherein a controller of the cardiac stimulation device controls selected functions of the device based on whether the patient is at rest and further based on whether the patient is prone to vagally-mediated arrhythmias. Functions of the device that may be controlled include, for example, a pacing base rate, an AV/PV delay, and a refractory period as well as overdrive pacing parameters and diagnostic data gathering parameters. In one example, if the patient is not prone to vagally-mediated arrhythmias, the base rate is lowered while the patient is at rest. Also, overdrive pacing parameters are set to be less aggressive. As such, the operation of the cardiac stimulation device is controlled to make it easier for the patient to rest while also reducing power consumption. However, if the patient is prone to vagally-mediated arrhythmias, the base rate is not lowered while the patient is at rest.

Abstract: Dynamic overdrive pacing adjustment techniques are described for use in implantable cardiac stimulation devices. In a first technique, an overdrive pacing unit of a microcontroller of the implantable device operates to optimize various control parameters that affect overdrive pacing so as to achieve a desired degree of overdrive pacing for the particular patient in which the stimulation device is implanted. Parameters to be optimized include the number of overdrive beats paced once overdrive pacing is trigged, the overdrive pacing response function, the recovery rate, and various base rates. The control parameters are adjusted in a hierarchical order of priority until the desired degree of overdrive pacing is achieved. Adjustment of the number of overdrive beats, the recovery rate, and various base rates is iteratively performed by using incremental numerical adjustments.

Abstract: A method and system for evaluating observed atrial activity, such as via an implantable cardiac stimulation device, to discriminate between the left and right atria as sites of origin of observed atrial flutter. The left and right atrial rates are compared for equivalence, stability, and relative time shift with respect to each other to determine which, if either, can be identified as the chamber of origin of the tachycardia. If relative comparison of the observed left and right atrial events is inconclusive, an evaluation can be made to attempt to determine the first flutter beat and its location under the assumption that the chamber in which a flutter beat was first observed was the site of origin. Determination of a particular atrium as the site of origin of flutter facilitates targeted delivery of ATP therapy to the determined site of origin.

Abstract: An implantable cardiac stimulation device, such as a pacemaker or Implantable Cardioverter Defibrillator, is configured to automatically monitor the effects of antiarrhythmic drugs on cardiac electrical signals within a patient to verify the efficacy of the drugs taken. In one example, an analysis of patient cardiac electrical signals is performed by comparing the cardiac electrical signals with values representative of the effects of different classes of antiarrhythmic drugs. If the implantable device determines that the prescribed antiarrhythmic drugs have not been effective, a warning signal is generated. The warning signal is conveyed directly to the patient via a bedside monitor and to the patient's physician via remote connection to an external programmer device so that both are notified of the drug efficacy problems.

Abstract: Techniques are provided for detecting natural electrical coherence within the heart and for administering or adjusting therapy based upon whether natural electrical coherence is detected. In one example, an implantable cardioverter defibrillator (ICD), upon detecting atrial fibrillation, delays administering an atrial defibrillation pulse until a period of natural electrical coherence is detected between the left and the right atria of the heart. The ICD may further delay the pulse until the ventricles of the heart are refractory so as to help prevent triggering ventricular fibrillation. The pulses are administered at a time selected based upon the period of electrical coherence to reduce the amount of electrical energy required within the pulse to reliably defibrillate the heart. Other types of therapy besides defibrillation therapy such as anti-tachycardia pacing pulses may also be timed based upon detection periods of natural electrical coherence. Method and apparatus embodiments are described.

Abstract: An implantable cardiac stimulation device, e.g., a pacemaker or an implantable cardioverter defibrillator (ICD), is provided which prolongs the atrial refractoriness of a heart. The implantable cardiac stimulation device includes a generator that delivers pacing pulses to an atrium of a heart and a detector that detects atrial activations of the heart. An inhibitor is coupled to the detector that inhibits the generator when an atrial activation is detected within an escape interval. A generator control coupled to the generator causes the generator to deliver a primary pacing pulse to the atrium at the end of the escape interval, absent an atrial activation being detected within the escape interval, and causes the generator to deliver a secondary pacing pulse to the atrium a delay time after an atrial activation is detected within the escape interval or the delivery of a primary pacing pulse to the atrium.

Abstract: An implantable cardiac stimulation device is described wherein a controller of the cardiac stimulation device controls selected functions of the device based on whether the patient is at rest and further based on whether the patient is prone to vagally-mediated arrhythmias. Functions of the device that may be controlled include, for example, a pacing base rate, an AV/PV delay, and a refractory period as well as overdrive pacing parameters and diagnostic data gathering parameters. In one example, if the patient is not prone to vagally-mediated arrhythmias, the base rate is lowered while the patient is at rest. Also, overdrive pacing parameters are set to be less aggressive. As such, the operation of the cardiac stimulation device is controlled to make it easier for the patient to rest while also reducing power consumption. However, if the patient is prone to vagally-mediated arrhythmias, the base rate is not lowered while the patient is at rest.

Abstract: An implantable cardiac stimulation device is described wherein a controller of the cardiac stimulation device controls selected functions of the device based on whether the patient is at rest and further based on whether the patient is prone to vagally-mediated arrhythmias. Functions of the device that may be controlled include, for example, a pacing base rate, an AV/PV delay, and a refractory period as well as overdrive pacing parameters and diagnostic data gathering parameters. In one example, if the patient is not prone to vagally-mediated arrhythmias, the base rate is lowered while the patient is at rest. Also, overdrive pacing parameters are set to be less aggressive. As such, the operation of the cardiac stimulation device is controlled to make it easier for the patient to rest while also reducing power consumption. However, if the patient is prone to vagally-mediated arrhythmias, the base rate is not lowered while the patient is at rest.

Abstract: A method and apparatus for reducing the incidence of atrial arrhythmias by using an overdrive algorithm to determine the application of overdrive stimulation pulses to a patient's heart, e.g., in the atria. In a first aspect of the invention, the apparatus first determines an overdrive pacing rate and then applies pairs of temporally spaced (staggered) pacing pulses, i.e., primary and secondary pacing pulses, at the determined overdrive pacing rate. In a further aspect of the invention, the pairs of pacing pulses are applied at the overdrive pacing rate to multiple spatially spaced electrodes, i.e., electrodes distributed among multiple sites in a patient's heart, e.g., in the atria. In accordance with a first preferred embodiment, the electrodes may be distributed within a single atrium, e.g., the right atrium, of the patient's heart.

Abstract: Dynamic overdrive pacing adjustment techniques are described for use in implantable cardiac stimulation devices. In a first technique, an overdrive pacing unit of a microcontroller of the implantable device operates to optimize various control parameters that affect overdrive pacing so as to achieve a desired degree of overdrive pacing for the particular patient in which the stimulation device is implanted. Parameters to be optimized include the number of overdrive beats paced once overdrive pacing is trigged, the overdrive pacing response function, the recovery rate, and various base rates. The control parameters are adjusted in a hierarchical order of priority until the desired degree of overdrive pacing is achieved. Adjustment of the number of overdrive beats, the recovery rate, and various base rates is iteratively performed by using incremental numerical adjustments.

Abstract: Dynamic overdrive pacing adjustment techniques are described for use in implantable cardiac stimulation devices. In a first technique, an overdrive pacing unit of a microcontroller of the implantable device operates to optimize various control parameters that affect overdrive pacing so as to achieve a desired degree of overdrive pacing for the particular patient in which the stimulation device is implanted. Parameters to be optimized include the number of overdrive beats paced once overdrive pacing is trigged, the overdrive pacing response function, the recovery rate, and various base rates. The control parameters are adjusted in a hierarchical order of priority until the desired degree of overdrive pacing is achieved. Adjustment of the number of overdrive beats, the recovery rate, and various base rates is iteratively performed by using incremental numerical adjustments.