In one embodiment, a WCD is described. The WCD includes a support structure configured to be worn by a patient and a processor coupled to the support structure. The WCD also includes an energy storage module configured to store an electrical charge and in communication with the processor. The WCD also includes a discharge circuit coupled to the energy storage module, the discharge circuit in communication with the processor and configured to discharge the stored electrical charge through a body of the patient. The processor is configured to detect an event at the WCD, classify the detected event, and determine an alarm onset time of the detected event based at least in part on the event classification. The processor is further configured to issue the alarm after the alarm onset time.

In some examples, a medical device system includes an electrode. The medical device system may include impedance measurement circuitry coupled to the electrode, the impedance measurement circuitry may be configured to generate an impedance signal indicating impedance proximate to the electrode. The medical device system may include processing circuitry that may be configured to identify a first component of the impedance signal. The first component of the impedance signal may be correlated to a cardiac event. The processing circuitry may be configured to determine that the cardiac event occurred based on the identification of the first component of the impedance signal.

A subcutaneous implantable active medical device, in particular a subcutaneous cardiac defibrillator, comprising a housing and a subcutaneous implantable lead connected to the housing. The subcutaneous implantable lead comprises a plurality of sensing electrodes forming at least two dipoles from which at least two electrical signals are collected concurrently. The first dipole having a first length less than a second length of the second dipole. The subcutaneous implantable active medical device further comprises a controller configured to determine whether or not tachyarrhythmia is present by determining a criterion of similarity based on the electrical signals collected concurrently via the first dipole and via the second dipole during a defined series of cardiac cycles that is such that detection of a depolarization peak, corresponding to detection of an R wave, is performed via the first dipole.

The present disclosure provides methods and systems for limiting arcing during an electroporation procedure. A method includes delivering a calibration shock using a catheter, measuring a current delivered during the calibration shock and a voltage delivered during the calibration shock, calculating, using a processing device, a calibration shock impedance based on the delivered current and the delivered voltage, calculating, using the processing device, a bridge impedance based on the calibration shock impedance and a target impedance, wherein the bridge impedance is a difference between the calibration shock impedance and the target impedance, adding an impedance in series with the catheter, the impedance being greater than or equal to the bridge impedance, and delivering a therapeutic shock using the catheter in series with the added impedance.

A method and system for managing an implantable medical device (IMD) based on left ventricular hypertrophy (LVH) are provided. The method collects cardiac activity (CA) signals from one or more implantable electrodes at corresponding sensing sites. The method utilizes one or more processors to perform identifying a characteristic of interest from the CA signals, analyzing the characteristic of interest from the CA signals to identify an LVH state indicative of at least one of an occurrence or degree of LVH experienced by the patient, calculating a DFT expectation based on the LVH state and determining, based on the DFT expectation, at least one of i) a defibrillation shock parameter or ii) a maximum energy capacity of the IMD for implant.

An implantable medical device system is configured to sense cardiac events in response to a cardiac electrical signal crossing a cardiac event sensing threshold. A control circuit is configured to determine a drop time interval based on a heart rate and control a sensing circuit to hold the cardiac event sensing threshold at a threshold value during the drop time interval.

A device for monitoring operation of a probe of an implantable active cardiac device, in particular an implantable automatic defibrillator or a defibrillator for cardiac resynchronization. The device comprising a parameter-determining device for determining values of a plurality of parameters characterizing the probe, and a processing unit configured to determine representative values that are representative of at least one parameter of the plurality of parameters characterizing the probe based on at least two different time scales. The processing unit is further configured to compare an analysis value of the at least one parameter of the plurality of parameters characterizing the probe with the representative values of the at least one parameter.

A medical device that includes a power source, a therapy delivery interface, therapy electrodes, electrocardiogram (ECG) sensing electrodes to sense ECG signal of a heart of a patient, a sensor interface to receive and digitize the ECG signal, and a processor. The processor is configured to analyze the ECG signal to determine a cardiac rhythm and a transform value representing a magnitude of a frequency component of the cardiac rhythm, analyze the cardiac rhythm and the transform value to detect a shockable cardiac arrhythmia by classifying the cardiac rhythm as a noise rhythm or a shockable cardiac arrhythmia rhythm based on the transform value, and causing the processor to detect the cardiac arrhythmia if classifying the cardiac rhythm as a shockable cardiac arrhythmia rhythm, initiate a treatment alarm sequence, adjust the shock delivery parameter for a defibrillation shock, and provide the defibrillation shock via the therapy electrodes.

A medical device that includes a power source, a therapy delivery interface, therapy electrodes, electrocardiogram (ECG) sensing electrodes to sense ECG signal of a heart of a patient, a sensor interface to receive and digitize the ECG signal, and a processor. The processor is configured to analyze the ECG signal to determine a cardiac rhythm and a transform value representing a magnitude of a frequency component of the cardiac rhythm, analyze the cardiac rhythm and the transform value to detect a shockable cardiac arrhythmia by classifying the cardiac rhythm as a noise rhythm or a shockable cardiac arrhythmia rhythm based on the transform value, and causing the processor to detect the cardiac arrhythmia if classifying the cardiac rhythm as a shockable cardiac arrhythmia rhythm, initiate a treatment alarm sequence, adjust the shock delivery parameter for a defibrillation shock, and provide the defibrillation shock via the therapy electrodes.

Several defibrillators, defibrillator architectures, defibrillator components and methods of operating defibrillators are described. In one aspect, a defibrillator (as for example an automated external defibrillator) that can be powered by a mobile communication device such as a smart cellular phone or a tablet computer is described. Utilizing a phone (or other mobile communication device) as the power supply for an external defibrillator allows the external defibrillator to be smaller and, in some circumstance, removes the need for a battery that stores sufficient energy for shock deliverywhich would need to be checked and/or replaced on a regular basis. Additionally, when desired, certain control functionality, computation, data processing, and user instructions can be handled/presented by the mobile communications device thereby further simplifying the defibrillator design and improving the user experience. This architecture takes advantage of the nearly ubiquitous availability of smart phones, tablet computers and other mobile communication devices.