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.

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 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 improved self-testing method is described which is incorporated into a defibrillator. The method performs a self-testing protocol which operates on a first frequency until a threshold condition is reached. When the threshold condition is reached, the self-testing protocol switches to a second frequency. Such a method enables quicker identification of a failure mode in a population of defibrillators, while maintaining acceptable battery life in the device.

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.

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.

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.

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 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.

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.