Method and system for analyzing an electrocardiographic signal

Abstract

A method for analyzing an ECG signal includes obtaining a measurement of an area based repolarization interval from at least one beat in the electrocardiogram signal and detecting an altered ventricular repolarization based on the obtained measured area based repolarization interval.

1 . A method for analyzing an electrocardiogram signal, the method comprising: 
 obtaining a measurement of an area based repoloarization interval from at least one beat in the electrocardiogram signal; and    detecting an altered ventricular repolarization based on the obtained measured area based repolarization interval.    
   
   
       2 . The method as set forth in  claim 1  further comprising preprocessing the electrocardiogram signal, the preprocessing including at least one of: 
 filtering the electrocardiogram signal;    extracting a portion of the electrocardiogram signal with at least the beat; and    substantially removing any baseline from the portion electrocardiogram signal.    
   
   
       3 . The method as set forth in  claim 2  wherein the preprocessing comprises the filtering, the extracting and the substantially removing.  
   
   
       4 . The method as set forth in  claim 2  wherein the filtering further comprises: 
 filtering the electrocardiogram signal with a low-pass filter;    reversing the filtered electrocardiogram signal; and    filtering the reversed filtered electrocardiogram signal with the low-pass filter.    
   
   
       5 . The method as set forth in  claim 2  wherein substantially removing any baseline comprises: 
 estimating the baseline using a cubic spline interpolation technique; and    substantially removing the estimated baseline.    
   
   
       6 . The method as set forth in  claim 1  wherein the obtaining further comprises: 
 determining a starting point of a T wave in the beat in the electrocardiogram signal; and    determining an end point of the T wave in the beat in the electrocardiogram signal, wherein the portion of the electrocardiogram signal which is measured is from the starting point to the end point of the T wave.    
   
   
       7 . The method as set forth in  claim 6  wherein the starting point of the T wave is a first time after an R peak in the beat in the electrocardiogram signal.  
   
   
       8 . The method as set forth in  claim 6  wherein the end point of the T wave is when a slope of the T wave in the beat in the electrocardiogram signal goes below a first threshold.  
   
   
       9 . The method as set forth in  claim 1  wherein the obtaining further comprises: 
 obtaining a plurality of measurements, wherein each of the measurements is of a different beat in the electrocardiogram signal;    dividing the obtained plurality of measurements into one or more sets; and    determining a median measurement for each of the sets, wherein the detecting an altered ventricular repolarization is based on the median measurement for one or more of the sets.    
   
   
       10 . The method as set forth in  claim 9  wherein the detecting an altered ventricular repolarization further comprises: 
 determining a time need to reach at least a first set percentage less than one hundred percent of the median measurement for at least one of the sets; and    comparing the determined time need to reach the first set percentage against another time to reach the first set percentage, wherein an altered ventricular repolarization is detected if the determined time deviates from the another time by more than a first set amount.    
   
   
       11 . The method according to  claim 10  wherein the another time comprises at least one of a standard time and another determined time to reach the first set percentage.  
   
   
       12 . The method according to  claim 9  further comprising removing one or more of the beats which are not normal from the electrocardiogram signal.  
   
   
       13 . The method as set forth in  claim 9  further comprising removing one or more of the beats from at least one end of the electrocardiogram signal.  
   
   
       14 . The method as set forth in  claim 1  wherein the detecting an altered ventricular repolarization further comprises: 
 determining a time need to reach at least a first set percentage less than one hundred percent of the obtained measured area based repolarization interval; and    comparing the determined time need to reach the first set percentage against another time to reach the first set percentage, wherein an altered ventricular repolarization is detected if the determined time deviates from the standard time by more than a first set amount.    
   
   
       15 . The method according to  claim 14  wherein the another time comprises at least one of a standard time and another determined time to reach the first set percentage.  
   
   
       16 . A computer readable medium having stored thereon instructions for analyzing an electrocardiogram signal which when executed by a processor, causes the processor to perform the steps of: 
 obtaining a measurement of an area based repolarization interval from at least one beat in the electrocardiogram signal; and    detecting an altered ventricular repolarization based on the obtained measured area based repolarization interval.    
   
   
       17 . The medium as set forth in  claim 15  further comprising preprocessing the electrocardiogram signal, the preprocessing including at least one of: 
 filtering the electrocardiogram signal;    extracting a portion of the electrocardiogram signal with at least the beat; and    substantially removing any baseline from the portion electrocardiogram signal.    
   
   
       18 . The medium as set forth in  claim 17  wherein the preprocessing comprises the filtering, the extracting and the substantially removing.  
   
   
       19 . The medium as set forth in  claim 17  wherein the filtering further comprises: 
 filtering the electrocardiogram signal with a low-pass filter;    reversing the filtered electrocardiogram signal; and    filtering the reversed filtered electrocardiogram signal with the low-pass filter.    
   
   
       20 . The medium as set forth in  claim 17  wherein substantially removing any baseline comprises: 
 estimating the baseline using a cubic spline interpolation technique; and    substantially removing the estimated baseline.    
   
   
       21 . The medium as set forth in  claim 16  wherein the obtaining further comprises: 
 determining a starting point of a T wave in the beat in the electrocardiogram signal; and    determining an end point of the T wave in the beat in the electrocardiogram signal, wherein the portion of the electrocardiogram signal which is measured is from the starting point to the end point of the T wave.    
   
   
       22 . The medium as set forth in  claim 21  wherein the starting point of the T wave is a first time after an R peak in the beat in the electrocardiogram signal.  
   
   
       23 . The medium as set forth in  claim 21  wherein the end point of the T wave is when a slope of the T wave in the beat in the electrocardiogram signal goes below a first threshold.  
   
   
       24 . The medium as set forth in  claim 16  wherein the obtaining further comprises: 
 obtaining a plurality of measurements, wherein each of the measurements is of a different beat in the electrocardiogram signal;    dividing the obtained plurality of measurements into one or more sets; and    determining a median measurement for each of the sets, wherein the detecting an altered ventricular repolarization is based on the median measurement for one or more of the sets.    
   
   
       25 . The medium as set forth in  claim 24  wherein the detecting an altered ventricular repolarization further comprises: 
 determining a time need to reach at least a first set percentage less than one hundred percent of the median measurement for at least one of the sets; and    comparing the determined time need to reach the first set percentage against another time to reach the first set percentage, wherein an altered ventricular repolarization is detected if the determined time deviates from the standard time by more than a first set amount.    
   
   
       26 . The medium according to  claim 25  wherein the another time comprises at least one of a standard time and another determined time to reach the first set percentage.  
   
   
       27 . The medium according to  claim 24  further comprising removing one or more of the beats which are not normal from the electrocardiogram signal.  
   
   
       28 . The medium as set forth in  claim 24  further comprising removing one or more of the beasts from at least one end of the electrocardiogram signal.  
   
   
       29 . The medium as set forth in  claim 16  wherein the detecting an altered ventricular repolarization further comprises: 
 determining a time need to reach at least a first set percentage less than one hundred percent of the obtained measured area based repolarization interval; and    comparing the determined time need to reach the first set percentage against another time to reach the first set percentage, wherein an altered ventricular repolarization is detected if the determined time deviates from the standard time by more than a first set amount.    
   
   
       30 . The medium according to  claim 29  wherein another time comprises at least one of a standard time and another determined time to reach the first set percentage.  
   
   
       31 . A system for analyzing an electrocardiogram signal, the system comprising: 
 a measurement system that obtains a measurement of an area based repolarization interval from at least one beat in the electrocardiogram signal; and    a detecting system that detects an altered ventricular repolarization based on the obtained measured area based repolarization interval.    
   
   
       32 . The system as set forth in  claim 31  further comprising a preprocessing system that includes at least one of: 
 a filtered system that filters the electrocardiogram signal;    an extraction system that extracts a portion of the electrocardiogram signal with at least the beat; and    a baseline removal system that substantially removes any baseline from the portion electrocardiogram signal.    
   
   
       33 . The system as set forth in  claim 32  wherein the preprocessing system comprises the filter system, the extraction system and the baseline removal system.  
   
   
       34 . The system as set forth in  claim 32  wherein the filter system further comprises a bidirectional, low pass filter that filters the electrocardiogram signal.  
   
   
       35 . The system as set forth in  claim 32  wherein baseline removal system further comprises an estimation system that estimates the baseline using a cubic spline interpolation technique, the baseline removal system substantially removing the estimated baseline.  
   
   
       36 . The system as set forth in  claim 32  wherein the measurement system further comprises a determining system that determines a starting point of a T wave in the beat in the electrocardiogram signal and an end point of the T wave in the beat in the electrocardiogram signal, wherein the portion of the electrocardiogram signal which is measured is from the starting point to the end point of the T wave.  
   
   
       37 . The system as set forth in  claim 36  wherein the starting point of T wave is a first time after an R peak in the beat in the electrocardiogram signal.  
   
   
       38 . The system as set forth in  claim 36  wherein the end point of the T wave is when a slope of the T wave in the beat in the electrocardiogram signal goes below a first threshold.  
   
   
       39 . The system as set forth in  claim 31  wherein the measurement system further comprises a median measurement determining system that obtains a plurality of measurements, wherein each of the measurements is of a different beat in the electrocardiogram signal, divides the obtained plurality of measurements into one or more sets, and determines a median measurement for each of the sets, wherein the detecting an altered ventricular repolarization is based on the median measurement for at least one of the sets.  
   
   
       40 . The system as set forth in  claim 39  wherein the detection system further comprises: 
 a determining system that determines a time need to reach at least a first set percentage less than one hundred percent of the median measurement for one or more of the sets; and    a comparison system that compares the determined time need to reach the first set percentage against another time to reach the first set percentage, wherein an altered ventricular repolarization is detected by the detection system if the determined tine deviates from the another time by more than a first set amount.    
   
   
       41 . The system according to  claim 40  wherein the another time comprises at least one of a standard time and another determined time to reach the first set percentage.  
   
   
       42 . The system according to  claim 39  further comprising a removal system that removes one or more of the beats which are not normal from the electrocardiogram signal.  
   
   
       43 . The system sa set forth in  claim 39  further comprising a removing system that removes one or more of the beats from at least one end of the electrocardiogram signal.  
   
   
       44 . The system as set forth in  claim 31  wherein the detection system further comprises: 
 a determining system that determines a time need to reach at least a first set percentage less than one hundred percent of the obtained measured area based repolorization interval; and    a comparison system that compares the determined time need to reach the first set percentage against another time to reach the first set percentage, wherein an altered ventricular repolarization is detected by the detection system if the determined time deviates from the another time by more than a first set amount.    
   
   
       45 . The system according to  claim 44  wherein the another time comprises at least one of a standard time and another determined time to reach the first set percentage.  
   
   
       46 - 59 . (canceled)