System and Method for Distinguishing a Cardiac Event From Noise in an Electrocardiogram (ECG) Signal

Abstract

A system includes an ambulatory medical device and a server. The ambulatory medical device comprises: a digital signal processing module configured to: detect an abnormal rhythm from an electrocardiogram (ECG) signal of a patient using a first signal processing routine; and generate a first flag indicating an abnormal rhythm is detected; and a noise detector module configured to: receive the ECG signal from the digital signal processing module; execute a second signal processing routine to classify the abnormal rhythm as one of an arrhythmia event and a noise event; and, if the abnormal rhythm is classified as a noise event, initiate a preconfirmation period during which the noise detector module continues to evaluate the abnormal rhythm and classify the abnormal rhythm as one of an arrhythmia event and a noise event using the second signal processing routine; and generate a second flag indicating the start of the preconfirmation period; and a server configured to: receive the ECG signal, the first flag indicating the abnormal rhythm, and the second flag indicating the start of the preconfirmation period; and provide a visual indication of the preconfirmation period.

1 . A system comprising:
 an ambulatory medical device comprising:
 a digital signal processing module configured to:
 detect an abnormal rhythm from an electrocardiogram (ECG) signal of a patient using a first signal processing routine; and 
 generate a first flag indicating an abnormal rhythm is detected; and 
 
 a noise detector module configured to:
 receive the ECG signal from the digital signal processing module; 
 execute a second signal processing routine to classify the abnormal rhythm as one of an arrhythmia event and a noise event; and, 
 if the abnormal rhythm is classified as a noise event, initiate a preconfirmation period during which the noise detector module continues to evaluate the abnormal rhythm and classify the abnormal rhythm as one of an arrhythmia event and a noise event using the second signal processing routine; and 
 generate a second flag indicating the start of the preconfirmation period; and 
 
   a server configured to:
 receive the ECG signal, the first flag indicating the abnormal rhythm, and the second flag indicating the start of the preconfirmation period; and 
 provide a visual indication of the preconfirmation period. 
   
     
     
         2 . The system of  claim 1 , wherein the ambulatory medical device is configured to monitor and treat the patient for arrhythmia. 
     
     
         3 . The system of  claim 1 , wherein the ambulatory medical device is a wearable defibrillator. 
     
     
         4 . The system of  claim 1 , wherein the digital signal processing module is configured to receive the ECG signal of the patient from an electrode assembly removably attached to the patient. 
     
     
         5 . The system of  claim 1 , wherein the second signal processing routine comprises:
 obtaining the ECG signal;   determining a transformed ECG signal based on the ECG signal;   extracting at least one value representing at least one feature of the transformed ECG signal;   providing the at least one value to determine a score associated with the ECG signal, thereby providing an ECG-derived score;   comparing the ECG-derived score to a predetermined threshold score determined by machine learning; and   classifying the abnormal rhythm as an arrhythmia event or a noise event based on the comparison of the ECG-derived score with the predetermined threshold score.   
     
     
         6 . The system of  claim 5 , wherein the machine learning is one of a multivariate adaptive regression splines classifier and a neural network classifier. 
     
     
         7 . The system of  claim 1 , wherein the visual indication of the preconfirmation period comprises a visual indication of a start of the preconfirmation period that is displayed on a display device operatively connected to the server. 
     
     
         8 . The system of  claim 1 , wherein the visual indication of the preconfirmation period comprises an annotation of a visual representation of the ECG signal for a duration of the preconfirmation period. 
     
     
         11 . The system of  claim 8 , wherein the preconfirmation period is annotated by highlighting a portion of the visual representation of the ECG signal corresponding to the preconfirmation period. 
     
     
         12 . The system of  claim 11 , wherein the preconfirmation period is highlighted by providing a portion of the visual representation of the ECG signal corresponding to the preconfirmation period a color that is different than a remainder of the visual representation of the ECG signal. 
     
     
         13 . The system of  claim 11 , wherein the preconfirmation period is highlighted by providing a portion of the visual representation of the ECG signal corresponding to the preconfirmation period with at least one of icons and text to differentiate the portion from a remainder of the visual representation of the ECG signal. 
     
     
         14 . The system of  claim 1 , wherein the preconfirmation period is between about 10 seconds and about 60 seconds. 
     
     
         15 . The system of  claim 1 , wherein, during the preconfirmation period, an alert device operatively coupled to the at least one processor of the one or more ambulatory medical devices does not provide an alarm to the patient. 
     
     
         16 . A system comprising:
 a wearable defibrillator comprising:
 therapy pads for rendering treatment to a patient wearable the wearable defibrillator; 
 sensing electrodes for obtaining an electrocardiogram (ECG) signal from the patient; 
 a digital signal processing module operatively connected to the therapy pads and the sensing electrodes, the digital signal processing module configured to:
 detect an abnormal rhythm from an electrocardiogram (ECG) signal of a patient using a first signal processing routine; and 
 generate a first flag indicating an abnormal rhythm is detected; and 
 
 a noise detector module configured to:
 receive the ECG signal from the digital signal processing module; 
 execute a second signal processing routine to classify the abnormal rhythm as one of an arrhythmia event and a noise event; and, 
 if the abnormal rhythm is classified as a noise event, initiate a preconfirmation period during which the noise detector module continues to evaluate the abnormal rhythm and classify the abnormal rhythm as one of an arrhythmia event and a noise event using the second signal processing routine; and 
 generate a second flag indicating the start of the preconfirmation period; and 
 
   a server configured to:
 receive the ECG signal, the first flag indicating the abnormal rhythm, and the second flag indicating the start of the preconfirmation period; and 
 provide a visual indication of the preconfirmation period. 
   
     
     
         17 . The system of  claim 16 , wherein the wearable defibrillator is configured to delay a treatment sequence culminating in a delivery of the treatment to the patient by a duration of the preconfirmation period. 
     
     
         18 . The system of  claim 16 , wherein the wearable defibrillator is configured to initiate a treatment sequence culminating in a delivery of the treatment to the patient immediately if the abnormal rhythm is classified as an arrhythmia event. 
     
     
         19 . The system of  claim 16 , wherein the visual indication of the preconfirmation period comprises a visual indication of a start of the preconfirmation period that is displayed on a display device operatively connected to the server. 
     
     
         20 . The system of  claim 16 , wherein the visual indication of the preconfirmation period comprises an annotation of a visual representation of the ECG signal for the duration of the preconfirmation period.