Wearable cardioverter defibrillator (WCD) segment based episode opening and confirmation periods
A wearable cardioverter defibrillator (WCD) comprises a plurality of electrocardiography (ECG) electrodes. An episode is opened responsive to a string of consecutive segments meeting one or more shock criteria, and a shockable rhythm is confirmed for the episode responsive to a subsequent string of consecutive segments meeting one or more confirmation criteria.
1. A wearable cardioverter defibrillator (WCD), comprising:
a plurality of electrocardiogram (ECG) electrodes adapted to contact a patient's skin while the patient is wearing the WCD;
a high voltage subsystem to provide a defibrillation voltage to the patient through a plurality of defibrillator electrodes in response to a shock signal; and
one or more processors to receive ECG data via the plurality of ECG electrodes, wherein the one or more processors are configured to:
analyze multiple segments of the ECG data, wherein a segment of the ECG data comprises a portion of the ECG data,
determine whether individual segments in a string of consecutive segments of the ECG data independently meet a shock criterion,
in the event a predetermined number of segments in the string of consecutive segments of the ECG data meet the shock criterion, open an episode,
determine whether an additional number of segments of the ECG data beyond the predetermined number of segments meets one or more confirmation criteria,
in the event the additional number of segments of the ECG data meets the one or more confirmation criteria, confirm a shockable rhythm in the episode and initiate a patient alert sequence responsive to confirmation of a shockable rhythm, and
provide the shock signal to the high voltage subsystem responsive to completion of the patient alert sequence and otherwise not providing the shock signal responsive to a patient responding to the patient alert sequence.
2. The WCD of claim 1 , wherein the shock criterion comprises all segments in the string of consecutive segments being determined to indicate a shockable rhythm.
3. The WCD of claim 1 , wherein the shock comprises a minimum number of the predetermined number of segments in the string of consecutive segments being determined to indicate a shockable rhythm.
4. The WCD of claim 3 , wherein the string of consecutive segments is six segments, and the predetermined number of segments is five segments.
5. The WCD of claim 1 , wherein the one or more confirmation criteria comprises all segments in the additional number of segments being determined to indicate a shockable rhythm.
6. The WCD of claim 5 , wherein the shockable rhythm is VF and the additional number of segments in the additional number of segments is two segments for the confirmation criteria.
7. The WCD of claim 1 , wherein the one or more confirmation criteria comprises a minimum number of segments in the additional number of segments being determined to indicate a shockable rhythm.
8. The WCD of claim 7 , wherein the shockable rhythm is VT and the additional number of segments in the string of consecutive segments is nineteen segments for the confirmation criteria, and the minimum number of segments in the string of consecutive segments is fifteen segments.
9. The WCD of claim 1 , wherein the one or more processors are configured to determine whether a segment of the ECG data indicates a shockable rhythm based at least in part on a heart rate and a QRS width determined from the segment.
10. The WCD of claim 1 , wherein the one or more processors are configured to classify a segment of the ECG data into one of a plurality of types based at least in part on a heart rate and a QRS width determined from the segment.
11. The WCD of claim 10 , wherein the plurality of types comprises VF, VT, and SVT.
12. The WCD of claim 11 , wherein a segment determined to have a heart rate above 120 beats per minute (BPM) and a QRS width less than 80 milliseconds (ms) is classified as SVT.
13. The WCD of claim 1 , wherein the segments of the ECG data comprise 4.8 seconds in duration.
14. A wearable medical system (WMS), comprising:
a support structure to be worn by a patient;
a plurality of electrocardiogram (ECG) electrodes coupled to the support structure and structured to contact a patient's skin while the patient is wearing the support structure; and
one or more processors to receive ECG data via the plurality of ECG electrodes, wherein the one or more processors are configured to:
analyze multiple segments of the ECG data, wherein a segment of the ECG data comprises a portion of the ECG data,
determine whether individual segments in a string of consecutive segments of the ECG data independently meet an arrhythmia criterion,
in the event a predetermined number of segments in the string of consecutive segments of the ECG data meet the arrhythmia criterion, open an episode,
determine whether an arrhythmia is confirmed in the episode when an additional number of segments of the ECG data beyond the predetermined number of segments meets one or more confirmation criteria,
in the event the additional number of segments of the ECG data meets the one or more confirmation criteria, confirm the arrythmia in the episode and initiate a patient alert sequence responsive to a determination that the arrythmia is confirmed, and
otherwise not initiate the patient alert sequence responsive to a determination that the arrythmia is not confirmed.
15. The WMS of claim 14 , wherein the one or more confirmation criteria comprises a minimum number of the predetermined number of segments in the string of consecutive segments being determined to indicate the arrhythmia.
16. The WMS of claim 15 , wherein the string of consecutive segments is six segments, and the predetermined number of segments is five segments.
17. The WMS of claim 14 , wherein the one or more confirmation criteria comprises a minimum number of segments in the additional number of segments being determined to indicate the arrhythmia.
18. The WMS of claim 14 , wherein the one or more processors are configured to determine whether a segment of the ECG data indicates an arrhythmia based at least in part on a heart rate and a QRS width determined from the segment.
19. The WMS of claim 14 , wherein the one or more processors are configured to classify a segment of the ECG data into one of a plurality of arrhythmias based at least in part on a heart rate and a QRS width determined from the segment.
20. The WMS of claim 19 , wherein the plurality of arrhythmias comprises ventricular fibrillation (VF), ventricular tachycardia (VT), and supraventricular tachycardia (SVT).
21. The WMS of claim 20 , wherein a segment determined to have a heart rate above 120 beats per minute (BPM) and a QRS width less than 80 milliseconds (ms) is classified as SVT.