Abstract: In one embodiment, a method to detect noise levels in electrocardiogram (ECG) signals. The method includes connecting to at least three sensing electrodes and obtaining a signal from each of the at least three sensing electrodes. The method also includes defining at least three channels between the at least three electrodes and obtaining heart data for a predetermined time period from the at least three channels wherein the heart data includes heart rate and QRS width. The method further includes comparing the heart data of each of the at least three channels to a consistency threshold.

Abstract: Apparatus and methods for generating pulse pacing in a wearable cardioverter defibrillator (“WCD”). In one aspect the WCD circuitry includes a power source such as a battery coupled to a charger that provides charge energy to an energy storage module. Control circuitry is operatively coupled to the charger and the output circuitry, and configured to cause the WCD circuitry to generate pacing pulses delivered to therapy electrodes (attached to an ambulatory patient) without a current source. The WCD circuitry includes one or more processing elements that are used to execute instructions provided by one or more software modules that are configured to support various functionality, including controlling generation of pacing pulses.

Abstract: A Wearable Cardioverter Defibrillator (WCD) system has a processor that performs two different analyses to an ECG of the patient. A first-level analysis can be computationally economical, while a fuller second-level analysis can give shock/no-shock advice with more certainty. In some of these embodiments the second-level analysis of the ECG is performed only if the first-level analysis of the ECG detects a possible shockable condition. As such, the first-level analysis may operate as a gatekeeping function, often preventing the more computationally intensive second-level analysis from being performed. An advantage can be that the WCD system needs to store less charge, for powering the processor. In turn, this permits portions of the WCD system to be less bulky and weigh less.

Abstract: In embodiments, a wearable cardioverter defibrillator (WCD) system includes electrodes that render an ECG signal of the patient, and a processor that receives ECG data are derived from the rendered ECG signal. The processor may filter the received ECG data with a matched difference filter to detect QRS complexes, and compute a heart rate from the detected QRS complexes. The matched difference filter itself can have coefficient values associated with a baseline QRS complex, which improves detection.

Abstract: A wearable cardioverter defibrillator (WCD) including a support structure configured to be worn by an ambulatory patient, an energy storage module configured to store an electrical charge, a discharge circuit coupled to the energy storage module, electrodes configured to render an electrocardiogram (ECG) signal of the patient while the patient is wearing the support structure, a user interface configured to output an alarm in response to a noise alarm signal, and a processor. The processor is configured to receive the ECG signal, determine whether noise is present on the ECG signal, determine from the ECG signal whether a shock criterion is met, and cause the user interface to generate the noise alarm signal when the noise is present on the ECG signal and the shock criterion is met and not generate the noise alarm signal when noise is present on the ECG signal and the shock criterion is not met.

Abstract: A wearable cardioverter defibrillator system includes a support structure that a patient can wear. The system also includes electrodes that contact the patient, and define two or more channels from which ECG signals are sensed. A processor may evaluate the channels by analyzing their respective ECG signals, to determine which contains less noise than the other(s). The analysis can be by extracting statistics from the ECG signals, optionally after first processing them, and then by comparing these statistics. These statistics may include tall peak counts, amplitudes of peaks compared to historical peak amplitudes, signal baseline shift, dwell time near a baseline, narrow peak counts, zero crossings counts, determined heart rates, and so on. Once the less noisy signal is identified, its channel can be followed preferentially or to the exclusion of other channels, for continuing monitoring and/or determining whether to shock the patient.

Abstract: In embodiments, a Wearable Cardioverter Defibrillator (WCD) system includes a support structure for the patient to wear, and components that the support structure maintains on the patient's body. The components include a defibrillator, associated electrodes, and so on. The defibrillator can operate in a WCD mode while the patient wears the support structure. The defibrillator can further operate in a different, AED mode, during which time the patient need not wear a portion of the support structure, or even the entire support structure. Sometimes the AED mode is a type of a fully automatic AED mode. Other times the AED mode is a type of a semi-automated AED mode, where an attendant is present to administer the shock; at such times, the patient may not even need to have electrodes attached. This way the patient is more comfortable for a longer time.

Abstract: A wearable medical includes a walking detector module with a motion sensor that is configured to detect when the patient is walking or running. In embodiments, a parameter (referred to herein as a “Bouncy” parameter) is determined from Y-axis acceleration measurements. In some embodiments, the Bouncy parameter is a measurement of the AC component of the Y-axis accelerometer signal. This detection can be used by the medical device to determine how and/or whether to provide treatment to the patient wearing the medical device. For example, when used in a WCD, the walking detector can prevent “false alarms” because a walking patient is generally conscious and not in need of a shock.

Abstract: In embodiments, a wearable cardioverter defibrillator (WCD) system includes a support structure for wearing by an ambulatory patient. When worn, the support structure maintains electrodes on the patient's body. Different pairs of these electrodes define different channels, and different patient ECG signals can be sensed from the channels. The ECG signals can be analyzed to determine which one is the best to use, for the WCD system to make a shock/no shock decision. The analysis can be according to widths of the QRS complexes, consistency of the QRS complexes, or heart rate agreement statistics.

Abstract: A wearable medical system (WMS) includes one or more pacing capabilities. The WMS May detect when the patient's heart rhythm starts to deteriorate, but not necessarily in a way that requires Defibrillation. In particular, the WMS may detect bradycardia of one or more types, and then confirm the detection before pacing to treat the detected bradycardia.

Abstract: In one embodiment, a method to determine reliable electrocardiogram (ECG) signal is described. The method includes receiving at least one ECG signal for a period of time from a patient. The method also includes analyzing the at least one ECG signal to determine a first heart rate using a first method and analyzing the at least one ECG signal to determine a second heart rate using a second method different from the first method. The method includes comparing the first and second heart rates to each other and classifying the at least one ECG signal as reliable when a reliability threshold is satisfied.

Abstract: A wearable cardiac defibrillator (“WCD”) system may include a support structure that a patient can wear, an energy storage module that can store an electrical charge, and a discharge circuit that can discharge the electrical charge through the patient so as to shock him or her, while the patient is wearing the support structure. Embodiments may actively take into account bystanders, both to protect them from an inadvertent shock, and also to enlist their help. In some embodiments, the WCD system includes a speaker system and a memory. Prompts have been saved in advance in the patient's own voice, and stored in the memory. In case of an emergency, the prompts may be played by the speaker system in the patient's own voice, and heard by a bystander.

Abstract: A wearable cardioverter defibrillator (WCD) including a support structure configured to be worn by an ambulatory patient, an energy storage module configured to store an electrical charge, a discharge circuit coupled to the energy storage module, electrodes configured to render an electrocardiogram (ECG) signal of the patient while the patient is wearing the support structure, a user interface configured to output an alarm in response to a noise alarm signal, and a processor. The processor is configured to receive the ECG signal, determine whether noise is present on the ECG signal, determine from the ECG signal whether a shock criterion is met, and cause the user interface to generate the noise alarm signal when the noise is present on the ECG signal and the shock criterion is met and not generate the noise alarm signal when noise is present on the ECG signal and the shock criterion is not met.

Abstract: In one example, an apparatus of a wearable cardioverter defibrillator (WCD) system comprises a support structure wearable by a patient, a plurality of electrocardiogram (ECG) electrodes to obtain an ECG signal, a processor to receive and analyze the ECG signal of the patient, wherein the processor is configured to monitor four or more channels of the ECG signal, a high voltage subsystem coupled with defibrillation electrodes configured to be coupled with patient, wherein processor is configured to cause the high voltage subsystem to apply a therapeutic shock to the patient through the defibrillation electrodes in response to a shockable event detected by the processor from the ECG signal. The processor measures a peak-to-peak amplitude of QRS complexes of the ECG signal, and detects asystole in the patient when the peak-to-peak amplitude of one or more QRS complexes is less than an asystole threshold. Other examples and related methods are disclosed herein.

Abstract: A wearable cardioverter defibrillator system includes a support structure that a patient can wear. The system also includes electrodes that contact the patient, and define two or more channels from which ECG signals are sensed. A processor may evaluate the channels by analyzing their respective ECG signals, to determine which contains less noise than the other(s). The analysis can be by extracting statistics from the ECG signals, optionally after first processing them, and then by comparing these statistics. These statistics may include tall peak counts, amplitudes of peaks compared to historical peak amplitudes, signal baseline shift, dwell time near a baseline, narrow peak counts, zero crossings counts, determined heart rates, and so on. Once the less noisy signal is identified, its channel can be followed preferentially or to the exclusion of other channels, for continuing monitoring and/or determining whether to shock the patient.

Abstract: Embodiments of a wearable cardioverter defibrillator (WCD) system include a support structure for wearing by an ambulatory patient and at least one processor. When worn, the support structure maintains electrodes on the patient's body, and using the patient's ECG received via the electrodes, the processor determines widths of the QRS complexes, consistency of the QRS complexes, and/or heart rate and uses these determinations to make no-shock, delay-shock, and shock decisions. Shock decisions can be made for heart rates lower than a VF threshold.

Abstract: In embodiments, a WCD system includes electrodes with which it senses an ECG signal of the patient. A processor may detect sequential peaks within the ECG signal, measure durations of time intervals between the peaks, including between non-sequential peaks, and identify a representative duration that best meets a plausibility criterion. The plausibility criterion may be that the representative duration is the one that occurs the most often, i.e. is the mode. Then a heart rate can be computed from a duration indicated by the representative duration and, if the heart rate meets a shock condition, the WCD system may deliver a shock to the patient. An advantage can be that the representative duration can be close to a good R-R interval measurement of a patient, notwithstanding noise in the ECG signal that is in the shape of peaks.

Abstract: In embodiments, a wearable cardioverter defibrillator (WCD) system includes electrodes that render an ECG signal of the patient, and a processor that receives ECG data are derived from the rendered ECG signal. The processor may filter the received ECG data with a matched difference filter to detect QRS complexes, and compute a heart rate from the detected QRS complexes. The matched difference filter itself can have coefficient values associated with a baseline QRS complex, which improves detection.

Abstract: A wearable cardiac defibrillator (“WCD”) system may include a support structure that a patient can wear, an energy storage module that can store an electrical charge, and a discharge circuit that can discharge the electrical charge through the patient so as to shock him or her, while the patient is wearing the support structure. Embodiments may actively take into account bystanders, both to protect them from an inadvertent shock, and also to enlist their help. In some embodiments the WCD system includes a speaker system that transmits a sound designed to assist a bystander to perform CPR. Optionally CPR chest compressions received by the patient can be further detected, and feedback can be given. In embodiments, a WCD system may include a user interface that can be controlled to output CPR prompts tailored to a skill level of the bystander.

Abstract: A wearable cardioverter defibrillator (WCD) comprises a plurality of electrocardiography (ECG) electrodes, a right-leg drive (RLD) electrode, and a plurality of defibrillator electrodes to contact the patient's skin when the WCD is delivering therapy to the patient, a preamplifier coupled to the ECG electrodes and the RLD electrode to obtain ECG data from the patient as one or more ECG vectors, a processor to receive ECG data from the preamplifier and an abort signal from a user interface, an isolation barrier to isolate the preamplifier from the processor, and a high voltage subsystem to provide a defibrillation voltage to the patient through the defibrillator electrodes in response to a shock signal received from the processor. A shock is provided when an abort signal is not received within a predetermined time period of a shock criterion being met. Less than one false alarm occurs every ten patient-days.