Wearable cardioverter defibrillator (wcd) with low false alarm rate

A method to determine whether a defibrillation shock should be applied with a wearable cardioverter defibrillator (WCD), the method comprising:

• receiving electrocardiography (ECG) data from a patient using the WCD with a preamplifier coupled to one or more ECG electrodes and a right-leg drive (RLD) electrode coupled to the patient's skin to obtain ECG data from the patient as one or more ECG vectors;
• receiving ECG data from the preamplifier with a processor;
• determining with the processor if a shock criterion is met based on a combination of heart rate data and a width of one or more QRS pulses identified in the ECG data;
• signaling the patient that the defibrillation shock is about to be applied;
• and
• applying the defibrillation shock to the patient unless a stop shock signal is caused by the patient within a predetermined period of time after signaling the patient;
• wherein the processor is to determine when a shock criterion is met based on the ECG data from the preamplifier, and to provide the defibrillation shock in the event the shock criterion is met and the stop shock signal is not received with a predetermined time period of the shock criterion being met;
• wherein the predetermined time period comprises a confirmation period when the shock criterion is met and the shock criterion is for ventricular fibrillation (VF);
• and
• wherein the predetermined time period comprises an extended confirmation period different from the confirmation period when the ECG data indicates the shock criterion is met and the shock criterion is for ventricular tachycardia (VT), the shock criterion for VT being different than the shock criterion for VF.

A wearable cardioverter defibrillator (WCD), comprising:

• a plurality of electrocardiography (ECG) electrodes and a plurality of therapy electrodes, the plurality of ECG electrodes and the plurality of therapy electrodes arranged to operatively contact a patient's skin when the WCD is operably attached to the patient;
• an amplifier coupled to the plurality of ECG electrodes to obtain multi-vector ECG data from the patient;
• an energy storage device configured to store an electrical charge;
• a high voltage subsystem coupled to the energy storage device and the plurality of therapy electrodes;
• and
• a processor coupled to the amplifier, the high voltage subsystem, and a user interface, wherein the processor is configured to:
• issue an alarm if a shock criterion is met, wherein the alarm is issued with a false alarm rate of less than one false alarm in ten patient days, and
• cause the high voltage subsystem to discharge the stored electrical charge from the energy storage device to the patient in response to the patient failing to respond to the alarm via the user interface within a predetermined time.

A wearable cardioverter defibrillator (WCD), comprising:

• a plurality of data electrodes and a plurality of defibrillator electrodes to contact a patient's skin when the WCD is delivering therapy to the patient;
• a user interface;
• a preamplifier coupled to the plurality of data electrodes to obtain patient data from the patient as one or more vectors;
• a processor to receive the patient data from the preamplifier and an abort signal from the user interface;
• and
• a high voltage subsystem to provide a defibrillation voltage to the patient through the plurality of defibrillator electrodes in response to a shock signal received from the processor;
• wherein the processor is to determine when a shock criterion is met based on the patient data from the preamplifier, and to provide the shock signal in the event the shock criterion is met and the abort signal is not received within a predetermined time period of the shock criterion being met;
• wherein the predetermined time period comprises a confirmation period when the shock criterion is met and the shock criterion is for ventricular fibrillation (VF), and
• wherein the predetermined time period comprises an extended confirmation period different from the confirmation period when the patient data indicates the shock criterion is met and the shock criterion is for ventricular tachycardia (VT), the shock criterion for VT being different than the shock criterion for VF.