An example device for detecting one or more parameters of a cardiac signal is disclosed herein. The device includes one or more electrodes and sensing circuitry configured to sense a cardiac signal via the one or more electrodes. The device further includes processing circuitry configured to determine an R-wave of the cardiac signal and determine whether the R-wave is noisy. Based on the R-wave being noisy, the processing circuitry is configured to determine whether the cardiac signal around a determined T-wave is noisy. Based on the cardiac signal around the determined T-wave not being noisy, the processing circuitry is configured to determine a QT interval or a corrected QT interval based on the determined T-wave and the determined R-wave.

A method for assessment, optimization and logging of the effects of a therapy for a medical condition, including (a) receiving into a signal processor input signals indicative of the subject's brain activity; (b) characterizing the spatio-temporal behavior of the brain activity using the signals; (c) delivering a therapy to a target tissue of the subject; (d) characterizing the spatio-temporal effect of the therapy on the brain activity; (e) in response to the characterizing, optimizing at least one parameter of the therapy if the brain activity has not been satisfactorily modified and/or has been adversely modified by the therapy; (f) characterizing the spatio-temporal effect of the at least one optimized parameter; and (g) logging to memory the at least one optimized parameter. A computer readable program storage unit encoded with instructions that, when executed by a computer, performs the method.

Techniques and systems for monitoring cardiac arrhythmias and delivering electrical stimulation therapy using a subcutaneous implantable cardioverter defibrillator (SICD) and a leadless pacing device (LPD) are described. For example, the SICD may detect a tachyarrhythmia within a first electrical signal from a heart and determine, based on the tachyarrhythmia, to deliver anti-tachyarrhythmia shock therapy to the patient to treat the detected arrhythmia. The LPD may receive communication from the SICD requesting the LPD deliver anti-tachycardia pacing to the heart and determine, based on a second electrical signal from the heart sensed by the LPD, whether to deliver anti-tachycardia pacing (ATP) to the heart. In this manner, the SICD and LPD may communicate to coordinate ATP and/or cardioversion/defibrillation therapy. In another example, the LPD may be configured to deliver post-shock pacing after detecting delivery of anti-tachyarrhythmia shock therapy.

Methods of nerve signal differentiation, methods of delivering therapy using such nerve signal differentiation, and to systems and devices for performing such methods. Nerve signal differentiation may include locating two electrodes proximate nerve tissue and differentiating between efferent and afferent components of nerve signals monitored using the two electrodes.

The present invention provides both methods and devices for termination of arrhythmias, such as ventricular or atrial tachyarrhythmias. The device and method involves application of alternating current (AC) for clinically significant durations at selected therapeutic frequencies through the cardiac tissue to a subject experiencing arrhythmia. Methods are also provided to minimize or eliminate pain during defibrillation.

An extra-cardiovascular implantable cardioverter defibrillator (ICD) system receives a cardiac electrical signal by an electrical sensing circuit via an extra-cardiovascular sensing electrode vector and senses cardiac events from the cardiac electrical signal. The ICD system detects tachycardia from the cardiac electrical signal and determines a tachycardia cycle length from the cardiac electrical signal. The ICD system determines an ATP interval based on the tachycardia cycle length and sets an extended ATP interval that is longer than the ATP interval. The ICD delivers ATP pulses to a patient's heart via an extra-cardiovascular pacing electrode vector different than the sensing electrode vector. The ATP pulses include a leading ATP pulse delivered at the extended ATP interval after a cardiac event is sensed from the cardiac electrical signal and a second ATP pulse delivered at the ATP interval following the leading ATP pulse.

A device includes a tissue conduction communication (TCC) transmitter that generates a TCC signal including a carrier signal having a peak-to-peak amplitude and a carrier frequency cycle length including a first polarity pulse for a first half of the carrier frequency cycle length and a second polarity pulse opposite the first polarity pulse for a second half of the carrier frequency cycle length. Each of the first polarity pulse and the second polarity pulse inject a half cycle charge into a TCC pathway. The TCC transmitter starts transmitting the TCC signal with a starting pulse having a net charge that is half of the half cycle charge and transmits alternating polarity pulses of the carrier signal consecutively following the starting pulse.

A computer implemented method and system for detecting arrhythmias in cardiac activity are provided. The method is under control of one or more processors configured with specific executable instructions. The method obtains cardiac activity (CA) signals at the electrodes of an implantable medical device (IMD) in connection multiple cardiac beats and with different IMD orientations relative to gravitational force. The method obtains acceleration signatures at a sensor of the IMD that are indicative of heart sounds generated during the cardiac beats. The method obtains device location information at the IMD, with respect to the gravitational force during the cardiac beats. The method groups the acceleration signatures associated with the first and second set of cardiac beats into the corresponding one of first and second posture bins based on the device location information. The method identifies a difference between the acceleration signals in the first posture bin in connection with treating a heart condition.

Techniques are described for discriminating SVT and, in particular, rapidly conducting AF. The techniques include detecting an onset of a fast rate of ventricular events sensed from a cardiac electrical signal and detecting a pause in the fast rate of ventricular sensed events. A threshold number of ventricular event intervals required to detect a ventricular tachyarrhythmia is detected with each of the threshold number of ventricular event intervals being less than a tachyarrhythmia detection interval. Detection of the ventricular tachyarrhythmia and an electrical stimulation therapy for treating the ventricular tachyarrhythmia are withheld in response to at least the pause being detected.

Adaptive methods for initiating charging of the high power capacitors of an implantable medical device for therapy delivery after the patient experiences a non-sustained arrhythmia, and devices that perform such methods. The adaptive methods and devices adjust persistence criteria used to analyze an arrhythmia prior to initiating a charging sequence to deliver therapy. Some embodiments apply a specific sequence of X-out-of-Y criteria, persistence criteria and last even criteria before starting charging for therapy delivery.