Abstract: An ambulatory or implantable device, such as a pacer, defibrillator, or other cardiac rhythm management device, can tolerate magnetic resonance imaging (MRI) or other noise without turning on an integrated circuit diode by selectively providing a bias voltage that can overcome an expected induced voltage resulting from the MRI or other noise.

Abstract: Methods and devices for classifying a cardiac pacing response involve using a first electrode combination for pacing and a second electrode combination for sensing a cardiac signal following pacing. The cardiac response to pacing may be classified using the sensed cardiac signal. One process involves using the sensed cardiac signal to detect the cardiac response as a fusion/pseudofusion beat. Another process involves using the sensed cardiac signal to classify the cardiac response to pacing as one of at least three cardiac response types.

Abstract: An ambulatory or implantable device, such as a pacer, defibrillator, or other cardiac rhythm management device, can tolerate magnetic resonance imaging (MRI) or other noise without turning on an integrated circuit diode by selectively providing a bias voltage that can overcome an expected induced voltage resulting from the MRI or other noise.

Abstract: An implantable medical device can include a hermetically-sealed implantable housing, an exposed first conductor located on or near the housing, and at least one insulated second conductor located near the exposed first conductor. In an example, the implantable medical device can include an isolation test circuit to provide a test stimulus to the exposed first conductor and configured to measure a portion of the test stimulus coupled to the second conductor.

Abstract: An active implantable medical device (AIMD) for use with a medical lead carrying at least one lead electrode. The AIMD comprises interior electronic circuitry configured for performing a medical function via the medical lead, an electrically conductive case containing the interior electronic circuitry, at least one electrical terminal configured for electrically coupling the electronic circuitry respectively to the lead electrode(s), and an inductive element coupled in series between the electrical terminal(s) and the case. The inductive element is configured for hindering the shunting of electrical current from the at least one electrical terminal to the case that has been induced by electromagnetic interference (EMI) impinging on the medical lead.

Abstract: Physiologic information can be received from a subject during a portion of a magnetic resonance imaging (MRI) session using a sensing circuit of an implantable medical device (IMD). An indication of an active MRI scan can be received, and a time period to inhibit use of physiological information from the subject can be determined following the received indication of the active MRI scan.

Abstract: A system detects events related to cardiac activity. The system comprises a primary cardiac signal sensing circuit, at least one secondary cardiac signal sensing circuit having a higher sensitivity than the primary sensing circuit, and a controller circuit coupled to the primary and secondary cardiac signal sensing circuits. The controller circuit determines a rate of depolarization using the primary sensing circuit and detects tachyarrhythmia using the rate. The controller circuit also detects tachyarrhythmia using the secondary sensing circuit and also deems the tachyarrhythmia valid if the controller circuit detects the tachyarrhythmia using both the primary and secondary sensing circuit.

Abstract: An implantable cardioverter/defibrillator (ICD) executes a rate accuracy enhancement algorithm to select measured atrial and ventricular intervals for classifying a detected tachycardia based on average atrial and ventricular rates calculated from the selected atrial and ventricular intervals. The detected tachycardia is classified as ventricular tachycardia (VT) if the average ventricular rate is substantially higher than the average atrial rate.

Abstract: An implantable medical device delivers anti-tachyarrhythmia therapies including anti-tachycardia pacing (ATP). If a detected tachyarrhythmia is classified as a type suitable for treatment using ATP, the implantable medical device selects one of an atrial ATP (A-ATP) mode, a ventricular ATP (V-ATP) mode, and a concurrent atrio-ventricular ATP (concurrent AV-ATP) mode according to the characteristics of the detected tachyarrhythmia. The concurrent ATP mode is an ATP mode during which the atrial pacing pulses and the ventricular pacing pulses are delivered concurrently. In one embodiment, the concurrent AV-ATP mode includes a synchronized atrio-ventricular ATP (synchronized AV-ATP) mode during which atrial and ventricular pacing pulses are delivered synchronously and an independent atrio-ventricular ATP (independent AV-ATP) mode during which atrial and ventricular pacing pulses are delivered concurrently but timed independently.

Abstract: An implantable medical device capable of being placed between a first operational mode and a second operational mode. The medical device comprises a magnetic field sensing device configured for outputting a signal in response to sensing a magnetic field. The medical device further comprises a logic circuit configured for continuously asserting the signal during a time period when the neurostimulation device is in the first operational mode, and intermittently asserting the signal during at least one time period when the neurostimulation device is in the second operational mode. The medical device further comprises a delay circuit configured for introducing a time delay into the asserted signal, the time delay being less than the time period, but greater than each of the at least one time period. The medical device further comprises control circuitry configured for performing a function in response to receiving the delayed signal at a first input terminal.

Abstract: Methods and devices for classifying a cardiac pacing response involve using a first electrode combination for pacing and a second electrode combination for sensing a cardiac signal following pacing. The cardiac response to pacing may be classified using the sensed cardiac signal. One process involves using the sensed cardiac signal to detect the cardiac response as a fusion/pseudofusion beat. Another process involves using the sensed cardiac signal to classify the cardiac response to pacing as one of at least three cardiac response types.

Abstract: A method of estimating response of a medical lead to an electromagnetic field includes providing a medical lead having a proximal end, a distal end, a plurality of electrodes disposed along the distal end, a plurality of terminals disposed along the proximal end, and a plurality of conductors extending along the medical lead and electrically coupling the electrodes to the terminals; individually applying a test field at each of a plurality of test positions along the medical lead using at least one excitation probe; for each application of the test field, determining a response to the application of the test field at one or more of the electrodes or terminals; generating a transfer function using a combination of the responses determined for the applications of the test field; and using the transfer function to estimate a response of the medical lead to an electromagnetic field.

Abstract: An implantable device, such as a pacer, defibrillator, or other cardiac rhythm management device, can include a failsafe backup, such as a separate and independent safety core that can assume control over operation of the implantable device from a primary controller. In an example, the safety core can include a normal first safety core operating mode and a magnetic resonance imaging (MRI) second safety core operating mode that can provide different functionality from the normal first safety core operating mode.

Abstract: An implantable cardioverter/defibrillator (ICD) delivers atrial pacing under several scenarios during a tachyarrhythmia episode that is detected using a ventricular rate. In various embodiments, the atrial pacing terminates the detected tachyarrhythmia and/or enhances the classification of the detected tachyarrhythmia, thus avoiding ineffective and/or unnecessary delivery of a ventricular anti-tachyarrhythmia therapy when the detected tachyarrhythmia has a supraventricular origin.

Abstract: This document discusses, among other things, systems and methods to discriminate between a ventricular tachyarrhythmia (VT) and a supraventricular tachyarrhythmia (SVT), such as upon detecting sudden onset and one-to-one tachycardia. In certain examples, a detected tachyarrhythmia is analyzed to determine whether it is sudden onset and 1:1. If so, a first fast beat is identified. One or more ventricular intervals in close proximity to the first fast beat are analyzed to determine an initial classification of either VT or SVT. The initial classification is used to adjust a morphological feature correlation coefficient (FCC) threshold. A morphology analysis is performed with the adjusted FCC threshold value to yield a secondary classification.

Abstract: This document discusses, among other things, detection of a sudden onset of a tachyarrhythmia. A sudden onset of tachyarrhythmia is determined by monitoring changes in intrinsic ventricular rate, such as by using one or more sensing channels in the ICD. A lowest tachyarrhythmia rate threshold is accompanied by a slightly lower “hysteresis tachyarrhythmia rate threshold.” If a sudden onset of tachyarrhythmia is declared, the sudden onset status is not reset by the ventricular rate falling below the lowest tachyarrhythmia rate threshold, but is instead reset by the ventricular rate falling below the slightly lower hysteresis tachyarrhythmia rate threshold.

Abstract: An apparatus comprises an implantable ventricular depolarization sensing circuit configured to provide a sensed ventricular depolarization signal, a timer circuit configured to provide a ventricular time interval between ventricular depolarizations, and a controller circuit communicatively coupled to the ventricular depolarization sensing circuit and the timer circuit. The controller circuit includes a ventricular tachycardia (VT) detection circuit configured to declare an episode of VT when a number of accelerated beats are detected, calculate a hysteresis VT detection threshold interval, and deem whether the episode of VT persists using the hysteresis VT detection threshold interval.

Abstract: An apparatus comprises first and second sensing circuits, a template generator circuit, and a correlation circuit. The correlation circuit is configured to identify a first fiducial position in a third cardiac signal sensed using the first sensing circuit during a detected rhythm with elevated ventricular rate, align the template correlation features and the correlation features of a fourth cardiac signal using the first fiducial position, calculate a correlation using the correlation features of the template and the correlation features of the fourth cardiac signal, and iteratively searching for a replacement to the first fiducial position in the third cardiac signal according to the calculated correlation.

Abstract: An implantable medical device delivers anti-tachyarrhythmia therapies including anti-tachycardia pacing (ATP). If a detected tachyarrhythmia is classified as a type suitable for treatment using ATP, the implantable medical device selects one of an atrial ATP (A-ATP) mode, a ventricular ATP (V-ATP) mode, and a concurrent atrio-ventricular ATP (concurrent AV-ATP) mode according to the characteristics of the detected tachyarrhythmia. The concurrent ATP mode is an ATP mode during which the atrial pacing pulses and the ventricular pacing pulses are delivered concurrently. In one embodiment, the concurrent AV-ATP mode includes a synchronized atrio-ventricular ATP (synchronized AV-ATP) mode during which atrial and ventricular pacing pulses are delivered synchronously and an independent atrio-ventricular ATP (independent AV-ATP) mode during which atrial and ventricular pacing pulses are delivered concurrently but timed independently.

Abstract: Systems and methods are described for classifying a cardiac rhythm. A cardiac rhythm is classified using a classification process that includes a plurality of cardiac rhythm discriminators. Each rhythm discriminator provides an independent classification of the cardiac rhythm. The classification process is modified if the modification is likely to produce enhanced classification results. The rhythm is reclassified using the modified classification process.