ECG P QRS T onset and peak detection method
First Claim
1. A method of detecting P and T waves in an electrocardiogram signal containing said P and T waves and containing previously detected QRS waves, said method comprising the steps of:
- a. selecting a next one of said previously detected QRS waves;
b. defining a first time interval within said electrocardiogram signal, said first time interval preceding said selected QRS wave and containing a plurality of samples of said electrocardiogram signal;
c. defining a second time interval within said electrocardiogram signal, said second time interval following said selected QRS wave and containing a plurality of samples of said electrocardiogram signal;
d. narrowing said first time interval to exclude QRS and previously detected T waves preceding said selected QRS wave;
e. narrowing said second time interval to exclude QRS waves following said selected QRS wave;
f. for each pair of said samples in said first time interval;
i. proceeding to step 1(f)(iv) if said pair of samples are separated by a time duration which does not exceed a predefined time duration;
ii. deriving the area, width, and height of a closed polygon having vertices defined by all samples within said first time interval between and including said pair of samples;
iii. deriving a rating for said polygon as a function of said area, width and height;
iv. selecting another pair of said samples and proceeding to step 1(f)(i);
g. selecting as said P wave that one of said step 1(f) (iii) polygons for which said rating is maximal;
h. for each pair of said samples in said second time interval;
i. proceeding to step 1(h)(iv) if said pair of samples are separated by a time duration which does not exceed a predefined time duration;
ii. deriving the area, width, and height of a closed polygon having vertices defined by all samples within said second time interval between and including said pair of samples;
iii. deriving a rating for said polygon as a function of said area, width and height;
iv. selecting another pair of said samples and proceeding to step 1(h)(i); and
,i. selecting as said T wave that one of said step 1(h) (iii) polygons for which said rating is maximal.
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Abstract
A method and apparatus for detecting P or T waves in an electrocardiogram signal in intervals before and after each (previously) detected QRS wave. Within each interval, a candidate pair of samples are selected. If the candidate pair are separated by a time duration which does not exceed a predefined time duration then that pair is rejected and the process repeats. Otherwise, the area "A" of a closed polygon bounded by all of the samples between and including the candidate pair is derived (the polygon'"'"'s base line extends linearly a distance "d" between the candidate pair of sample intervals). The maximum vertical displacement "h" between the base line and any portion of the polygon above the base line is derived. If "h" does not exceed a predefined minimum vertical displacement, then the candidate pair is rejected and the process repeats. Otherwise, a value Gamma=A*h/d is derived for the candidate pair. If Gamma does not exceed any value of Gamma derived previously in respect of any previously selected candidate pair, then the candidate pair is rejected and the process repeats. Otherwise, a value BestGamma is set equal to the candidate pair'"'"'s value Gamma. Another candidate pair is then selected and the process repeats. The P or T wave is selected as that whose value Gamma equals the value BestGamma.
59 Citations
6 Claims
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1. A method of detecting P and T waves in an electrocardiogram signal containing said P and T waves and containing previously detected QRS waves, said method comprising the steps of:
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a. selecting a next one of said previously detected QRS waves; b. defining a first time interval within said electrocardiogram signal, said first time interval preceding said selected QRS wave and containing a plurality of samples of said electrocardiogram signal; c. defining a second time interval within said electrocardiogram signal, said second time interval following said selected QRS wave and containing a plurality of samples of said electrocardiogram signal; d. narrowing said first time interval to exclude QRS and previously detected T waves preceding said selected QRS wave; e. narrowing said second time interval to exclude QRS waves following said selected QRS wave; f. for each pair of said samples in said first time interval; i. proceeding to step 1(f)(iv) if said pair of samples are separated by a time duration which does not exceed a predefined time duration; ii. deriving the area, width, and height of a closed polygon having vertices defined by all samples within said first time interval between and including said pair of samples; iii. deriving a rating for said polygon as a function of said area, width and height; iv. selecting another pair of said samples and proceeding to step 1(f)(i); g. selecting as said P wave that one of said step 1(f) (iii) polygons for which said rating is maximal; h. for each pair of said samples in said second time interval; i. proceeding to step 1(h)(iv) if said pair of samples are separated by a time duration which does not exceed a predefined time duration; ii. deriving the area, width, and height of a closed polygon having vertices defined by all samples within said second time interval between and including said pair of samples; iii. deriving a rating for said polygon as a function of said area, width and height; iv. selecting another pair of said samples and proceeding to step 1(h)(i); and
,i. selecting as said T wave that one of said step 1(h) (iii) polygons for which said rating is maximal. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification