Multilead ECG template-derived residua for arrhythmia risk assessment
View Patent ↗A method and system for predicting the onset of heart arrhythmias more accurately observes trends in abnormal or pathologic morphology of the electrocardiogram (ECG). A first set of ECG signals is monitored from a patient. A baseline measurement is generated from the monitored first set of ECG signals to contain nonpathologic ECG morphologies in each lead. A second set of ECG signals is monitored from the patient and the baseline measurement is subtracted from the second set of ECG signals on a beat-to-beat basis. Afterwards, a residuum signal is generated for each lead based on the subtraction. R-wave heterogeneity, T-wave heterogeneity, P-wave heterogeneity, or ST-segment heterogeneity or other indicators of arrhythmia risk or myocardial ischemia are quantified based on the generated residuum signals.
1. A method of quantifying risk of cardiac arrhythmia, comprising:
receiving a first set of electrocardiogram (ECG) signals from spatially separated leads;
generating a baseline beat template associated with the morphology of each ECG signal of the first set of ECG signals;
receiving a second set of ECG signals from spatially separated leads;
calculating, for each lead, a difference between each ECG signal in the second set of ECG signals and the corresponding baseline beat template to produce a residuum signal for each lead;
averaging the residuum signals across the leads to produce an averaged residuum signal; and
quantifying a spatio-temporal heterogeneity of the second set of ECG signals based on the residuum signals and the averaged residuum signal, wherein the spatio-temporal heterogeneity is associated with arrhythmia risk.
2. The method of claim 1 , wherein the quantifying step comprises:
quantifying at least one of R-wave heterogeneity, T-wave heterogeneity, P-wave heterogeneity, and ST-segment heterogeneity.
3. The method of claim 2 , wherein the first receiving step comprises monitoring ECG signals from a patient using a standard 12-lead ECG, wherein the generating step comprises generating a baseline measurement for each lead of the standard 12-lead ECG, and wherein the calculating step produces a residuum signal for each lead of the standard 12-lead ECG.
4. The method of claim 1 , wherein the quantifying step quantifies an R-wave heterogeneity by calculating a maximum square root of a second central moment of the residuum signals about the averaged residuum signal occurring within a QRS duration.
5. The method of claim 1 , wherein the quantifying step quantifies a T-wave heterogeneity by calculating a maximum square root of a second central moment of the residuum signals about the averaged residuum signal occurring within a JT interval.
6. The method of claim 1 , wherein the quantifying step quantifies a P-wave heterogeneity by calculating a maximum square root of a second central moment of the residuum signals about the averaged residuum signal occurring within a PQ interval.
7. The method of claim 1 , wherein the quantifying step quantifies an ST-segment heterogeneity by calculating a maximum square root of a second central moment of the residuum signals about the averaged residuum signal occurring within an ST interval.
8. The method of claim 2 , further comprising identifying a peak level of at least one of quantified R-wave heterogeneity, T-wave heterogeneity, P-wave heterogeneity, and ST-segment heterogeneity.
9. The method of claim 8 , further comprising determining a trend of at least one of peak R-wave heterogeneity level, peak T-wave heterogeneity level, peak P-wave heterogeneity level, and peak ST-segment heterogeneity level over a period of time.
10. The method of claim 8 , wherein the step of identifying further comprises using the peak level to predict risk for cardiac arrhythmias.
11. The method of claim 1 , wherein the generating step comprises computing a median-beat for each ECG signal of the first set of ECG signals.
12. The method of claim 11 , wherein the median-beat is computed over a time period between 5 and 10 minutes.
13. An electrocardiogram (ECG) system for quantifying risk of cardiac arrhythmia, comprising:
an input module configured to receive ECG signals from spatially separated leads; and
a processor configured to:
generate a baseline beat template associated with the morphology of each ECG signal of a first set of ECG signals from the spatially separated leads,
calculate a difference between each ECG signal of a second set of ECG signals from the spatially separated leads and the corresponding baseline beat template to produce a residuum signal for each of the spatially separated leads,
average the residuum signals across the leads to produce an averaged residuum signal; and
quantify a spatio-temporal heterogeneity of the second set of ECG signals based on the residuum signals and the averaged residuum signal, wherein the spatio-temporal heterogeneity is associated with arrhythmia risk.
14. The system of claim 13 , wherein the processor is configured to quantify R-wave heterogeneity, T-wave heterogeneity, P-wave heterogeneity, and ST-segment heterogeneity.
15. The method of claim 13 , wherein the processor is configured to quantify at least one selected from the group consisting of R-wave heterogeneity, T-wave heterogeneity, P-wave heterogeneity, and ST-segment heterogeneity.
16. The system of claim 15 , wherein the processor is configured to produce a residuum signal for each lead of a standard 12-lead ECG.
17. The system of claim 13 , wherein the processor is further configured to quantify an R-wave heterogeneity by calculating a maximum square root of a second central moment of the averaged residuum signal occurring within a QRS duration.
18. The system of claim 13 , wherein the processor is further configured to quantify a T-wave heterogeneity by calculating a maximum square root of a second central moment of the averaged residuum signal occurring within a JT interval.
19. The system of claim 13 , wherein the processor is further configured to quantify a P-wave heterogeneity by calculating a maximum square root of a second central moment of the averaged residuum signal occurring within a PQ interval.
20. The system of claim 13 , wherein the processor is further configured to quantify an ST-segment heterogeneity by calculating a maximum square root of a second central moment of the averaged residuum signal occurring within an ST interval.
21. The system of claim 13 , wherein the processor is further configured to determine at least one of peak quantified R-wave heterogeneity, peak T-wave heterogeneity, peak P-wave heterogeneity, and peak ST-segment heterogeneity.
22. The system of claim 21 , wherein the processor is further configured to determine a trend of at least one of the peak R-wave heterogeneity, peak T-wave heterogeneity, peak P-wave heterogeneity, and peak ST-segment heterogeneity levels over a period of time.
23. The system of claim 13 , wherein the processor is further configured to compute a median-beat for each ECG signal of the first set of ECG signals to generate each baseline beat template.
24. The system of claim 23 , wherein the median-beat is computed over a time period between 5 and 10 minutes.
25. A computer program product stored on non-transitory computer readable media, including a set of instructions that, when executed by a computing device, perform a method of quantifying risk of cardiac arrhythmia, comprising:
receiving a first set of electrocardiogram (ECG) signals;
generating a baseline measurement associated with the morphology of each ECG signal of the first set of ECG signals;
receiving a second set of ECG signals;
calculating, for each lead, a difference between each ECG signal in the second set of ECG signals and the corresponding baseline measurement to produce a residuum signal for each lead;
averaging the residuum signals across the leads to produce an averaged residuum signal; and
quantifying, a spatio-temporal heterogeneity of the second set of ECG signals based on the residuum signals and the averaged residuum signal, wherein the spatio-temporal heterogeneity is correlated with arrhythmia risk.