Detection of atrial arrhythmia
The invention relates to a method and system for detecting atrial arrhythmia, especially atrial fibrillations. Based on at least one electrical signal indicative of a heart's activity, a plurality of short-term HRV data sets are generated, one short-term HRV data set indicating the heart's rate variability within a time period of a given length, and two consecutive short-term HRV data sets having a given time difference. A frequency analysis of each short-term HRV data set is then performed and a power level corresponding to at least one selected frequency component in each short-term HRV data set is defined. The occurrence of the heart's atrial arrhythmia episodes are then estimated on the basis of the power levels defined.
1. A method for detecting atrial arrhythmia for a patient, the method comprising the steps of:
receiving at least one electrical signal indicative of a heart's activity;
based on the at least one electrical signal, generating a plurality of short-term HRV data sets, a short-term HRV data set indicating the heart's rate variability within a time period of a given length, two consecutive short-term HRV data sets having a given time difference;
performing a frequency analysis of at least some of the generated short-term HRV data sets;
based on a performed frequency analysis, defining a power level that corresponds to at least one selected frequency component in the corresponding short-term HRV data set, wherein a power level is defined for at least some of the short-term HRV data sets; and
based on the power levels so defined, ascertaining an occurrence of an atrial arrhythmia episode of the heart.
2. A method according to claim 1 , wherein the ascertaining step includes determining onset and ending moments of an atrial arrhythmia episode of the heart.
3. A method according to claim 1 , wherein the performing step includes performing a frequency analysis of all generated short-term HRV data sets and the defining step includes defining a power level for all generated short-term HRV data sets.
4. A method according to claim 1 , wherein the performing step includes performing a Fourier transformation on at least some of the short-term HRV data sets.
5. A method according to claim 1 , wherein the given length is between 2 and 5 minutes.
6. A method according to claim 5 , wherein the given time difference is substantially shorter than said time period.
7. A method according to claim 6 , wherein the given time difference is between 10 and 30 seconds.
8. A method according to claim 6 , wherein the given time difference remains constant for all short-term HRV data sets generated.
9. A method according to claim 6 , further comprising a step of giving the time difference a new value during the generating step.
10. A method according to claim 9 , further comprising a step of replacing some of the generated short-term HRV data sets by generating new short-term HRV data sets beginning from a selected time moment, wherein the time difference between two consecutive new short-term HRV data sets has said new value.
11. A method according to claim 1 , wherein the at least one selected frequency component is above 0.3 Hz.
12. A method according to claim 11 , wherein the at least one selected frequency component forms at least one frequency band.
13. A method according to claim 1 , wherein the least one selected frequency component is below 0.3 Hz.
14. A method according to claim 1 , wherein the plurality of short-term HRV data sets covers a desired monitoring period.
15. A method according to claim 14 , wherein the desired monitoring period is 24 hours.
16. A system for detecting atrial arrhythmia for a patient, the system comprising:
measurement means for obtaining data indicative of a heart's activity;
processing means for generating a plurality of short-term HRV data sets from the data, a short-term HRV data set indicating the heart's rate variability within a time period of a given length;
frequency analysis means for performing a frequency analysis of at least some of the short-term HRV data sets, the frequency analysis means being configured to define a power level corresponding to at least one selected frequency component in an individual short-term HRV data set for obtaining a plurality of power levels; and
calculation means, responsive to the frequency analysis means, for ascertaining, based on the plurality of power levels, an occurrence of an atrial arrhythmia episode of the heart.
17. A system according to claim 16 , wherein the calculation means is configured to determine onset and ending moments of an atrial arrhythmia episode of the heart.
18. A system according to claim 16 , wherein the frequency analysis means is configured to define a power level corresponding to a selected frequency band in an individual short-term HRV data set.
19. A system according to claim 16 , further comprising means for displaying the atrial arrhythmia episodes and their durations in time domain.
20. A method according to claim 1 wherein the given time difference is substantially shorter than said time period.
21. A method according to claim 20 wherein the given time difference remains constant for all short-term HRV data sets generated.
22. A method according to claim 20 further comprising a step of giving the time difference a new value during the generating step.
23. A method according to claim 22 further comprising a step of replacing some of the generated short-term HRV data sets by generating new short-term HRV data sets beginning from a selected time moment, wherein the time difference between two consecutive new short-term HRV data sets has said new value.
24. A system according to claim 16 where said frequency analysis means performs a Fourier transformation on at least some of the short-term HRV data sets.