Disclosed are apparatus and methods that provide the ability to electrical stimulate a physical system, and actively eliminate interference with signal acquisition (artifacts) that arises from the stimulation. The technique implemented in the circuits and methods for eliminating interference connects a discharge path to a physical interface to the system to remove charge that is built-up during stimulation. By placing the discharge path in a feedback loop that includes a recording preamplifier and AC-coupling circuitry, the physical interface is brought back to its pre-stimulation offset voltage. The disclosed apparatus and methods may be used with piezoelectric transducers, ultrasound devices, optical diodes, and polarizable and non-polarizable electrodes. The disclosed apparatus can be employed in implantable devices, in vitro or in vivo setups with vertebrate and invertebrate neural tissue, muscle fibers, pancreatic islet cells, osteoblasts, osteoclasts, bacteria, algae, fungi, protists, and plants.

An implantable medical device performs a method that includes detecting a cardiac event interval that is greater than a P-wave oversensing threshold interval. In response to detecting the cardiac event interval greater than the P-wave oversensing threshold interval, the device determines the amplitude of the sensed cardiac signal and withholds restarting a pacing interval in response to the amplitude satisfying P-wave oversensing criteria. A pacing pulse may be generated in response to the pacing interval expiring without sensing an intrinsic cardiac electrical event that is not detected as a P-wave oversensing event.

A medical device system, such as an extra-cardiovascular implantable cardioverter defibrillator ICD, senses R-waves from a first cardiac electrical signal by a first sensing channel and stores a time segment of a second cardiac electrical signal in response to each sensed R-wave. The medical device system determines a morphology parameter correlated to signal noise from time segments of the second cardiac electrical signal, detects a noisy signal segment based on the signal morphology parameter; and withholds detection of a tachyarrhythmia episode in response to detecting a threshold number of noisy signal segments.

An implantable cardioverter defibrillator (ICD) performs a method that includes determining whether first criteria for detecting a ventricular tachyarrhythmia are met by a cardiac electrical signal. The ICD determines features from cardiac signal segment of a group of cardiac signal segments and determines whether a first portion of the features satisfy monomorphic waveform criteria and determines whether a second portion of the features satisfy supraventricular beat criteria. The ICD determines whether second criteria for detecting the ventricular tachyarrhythmia are met and withholds detecting of the ventricular tachyarrhythmia in response to the monomorphic waveform criteria and the supraventricular beat criteria being met.

Methods and devices are provided for managing anti-tachycardia pacing therapy delivered by an implantable medical device (IMD). The methods and devices detect events from cardiac signals sensed at electrodes of the IMD. The cardiac signals represent a ventricular tachycardia (VT) episode that includes at least a select number of VT events having a corresponding VT cycle length. The methods and devices analyze the VT cycle length to define an anti-tachycardia pacing (ATP) therapy that includes a first coupling interval and deliver a first ATP pulse that is spaced the first coupling interval after a reference refractory VT event sensed at the electrodes. The methods and devices deliver a second ATP pulse following the first ATP pulse by a non-stimulation segment that is at least one and three-quarters (1.75) times a projected VT cycle length.

Computer implemented methods, devices and systems for monitoring a trend in heart failure (HF) progression are provided. The method comprises sensing left ventricular (LV) activation events at multiple LV sensing sites along a multi-electrode LV lead. The activation events are generated in response to an intrinsic or paced ventricular event. The method implements program instructions on one or more processors for automatically determining a conduction pattern (CP) across the LV sensing sites based on the LV activation events, identifying morphologies (MP) for cardiac signals associated with the LV activation events and repeating the sensing, determining and identifying operations, at select intervals, to build a CP collection and an MP collection. The method calculates an HF trend based on the CP collection and MP collection and classifies a patient condition based on the HF trend to form an HF assessment.

The present invention relates to the field of medical devices and discloses an implantable medical device for treating arrhythmia. The implantable medical device includes a control unit and, each coupled to the control unit, a sense amplifier, a first switch and a second switch. The sense amplifier includes a polarity selection module, an amplification unit and a filtering unit, which are sequentially connected. The first switch is disposed within the polarity selection module, and the second switch within the filtering unit. The control unit is configured to shield the sense amplifier from interference from a pacing pulse signal by providing multi-stage on/off control over the first and second switches according to a pacing period and a discharging period in a pacing interval. According to embodiments of the invention, the shielding switches in the sense amplifier are switched on/off in multiple stages according to pacing and discharging periods of a pacing pulse signal so as to shield the sense amplifier from interference from the pacing pulse signal and enhance its pacing pulse signal suppression performance.

Devices and methods for dynamically controlling sensitivity associated with detecting R-waves while maintaining the fixed detection threshold are described herein. One such method includes sensing an analog signal indicative of cardiac electrical activity, converting the analog signal indicative of cardiac electrical activity to a digital signal indicative of cardiac electrical activity, and detecting R-waves by comparing the digital signal indicative of cardiac electrical activity to a fixed detection threshold to thereby detect threshold crossings that corresponds to R-waves. The method further includes selectively adjusting a gain applied to the digital signal indicative of cardiac electrical activity to thereby selectively adjust a sensitivity associated with the detecting R-waves, while maintaining the fixed detection threshold.

A method includes acquiring a bipolar signal from a first electrode and a second electrode contacting a first location and a second location, respectively, in a heart of a living subject. The method further includes acquiring a unipolar signal from the first electrode while in contact with the first location, and deriving from the bipolar signal and the unipolar signal a point in time at which the first location is generating the unipolar signal. The method also includes computing a metric for a conduction velocity of the unipolar signal at the first location based on a shape of the unipolar signal at the point in time.

Systems, methods, and devices for determining occurrences of a tamponade condition are disclosed. One exemplary method includes monitoring an accelerometer signal of a leadless cardiac pacemaker attached to a heart wall, determining if a tamponade condition of the patient's heart is indicated based at least in part on the monitored accelerometer signal, and in response to determining that the tamponade condition is indicated, providing a notification of the tamponade condition for use by a physician to take corrective action.