Non-invasive dynamic tracking of cardiac vulnerability by analysis of T-wave alternans

A method for dynamic tracking of cardiac vulnerability, comprising the steps of:

• sensing an ECG signal from a heart, said ECG signal having a plurality of R-R intervals, each R-R interval including an R-wave and a T-wave;
• sampling said ECG signal;
• predicting the location in said ECG signal of the T-wave in each R-R interval;
• partitioning each T-wave in said ECG signal into a plurality of time divisions;
• summing the samples in each of said time divisions of said ECG signal;
• forming a time series for each of said time divisions, each time series including corresponding sums from corresponding time divisions from successive ones of said T-waves;
• and
• performing dynamic estimation on each said time series to estimate the amplitude of beat-to-beat alternation for each said time division.

A method for non-invasive, dynamic tracking of cardiac vulnerability in a live subject, comprising the steps of:

• (a) placing a precordial ECG lead on the surface of the subject's body proximate to the subject's heart to sense an ECG signal, said ECG signal having a plurality of R-R intervals, each R-R interval including an R-wave and a T-wave;
• (b) amplifying said ECG signal;
• (c) low-pass filtering said ECG signal;
• (d) sampling said ECG signal;
• (e) identifying in said ECG signal the location of the R-wave in each R-R interval;
• (f) comparing each R-R interval with a standard criteria to eliminate premature beats;
• (g) predicting the location in said ECG signal of the T-wave in each R-R interval;
• (h) partitioning each T-wave in said ECG signal into a plurality of time divisions;
• (i) summing the sampled ECG signal in each of said time divisions;
• (j) forming a time series for each of said time divisions, each time series including corresponding sums from corresponding time divisions from successive ones of said T-waves;
• (k) detrending each said time series;
• and
• (l) performing dynamic estimation of the amplitude of beat-to-beat alternation for each said time division on each detrended time series.

An apparatus for dynamically tracking cardiac vulnerability by analyzing alternans in the T-waves of a plurality of R-R intervals of an ECG, said apparatus comprising:

• means for sampling the ECG;
• means for predicting the location in the ECG signal of the T-wave in each R-R interval;
• means for partitioning each T-wave in said ECG signal into a plurality of time divisions;
• means for summing the samples of the ECG signal in each of said time divisions and for forming a time series for each of said time divisions, each time series including corresponding sums from corresponding time divisions from successive ones of said T-waves;
• and
• means for performing dynamic estimation on each time series to estimate the amplitude of alternation for each time division.

An apparatus for the non-invasive, dynamic tracking of cardiac vulnerability through analysis of alternans in the T-waves of an ECG signal, said ECG signal having a plurality of R-to-R intervals, said apparatus comprising:

• means for non-invasively sensing the ECG signal from a living subject;
• means for high-pass filtering the ECG signal to eliminate DC components;
• means for amplifying the ECG signal;
• means for low-pass filtering the ECG signal to eliminate noise;
• means for sampling the ECG signal to produce a sampled ECG signal;
• means for predicting the location in the sampled ECG signal of the T-wave in each R-R interval;
• means for partitioning each T-wave in said sampled ECG signal into a plurality of time divisions;
• means for summing the samples of the ECG signal in each of said time divisions and for forming a time series for each of said time divisions, each time series including corresponding sums from corresponding time divisions from successive ones of said T-waves;
• and
• means for performing dynamic estimation on each time series to estimate the amplitude of alternation for each time division.