RRI measurement device, RRI measurement method and RRI measurement program
An RRI measurement device includes: an R wave detection unit configured to detect a peak point of an R wave from a sampling data sequence of an electrocardiogram signal of a subject; an R wave detection unit configured to estimate a waveform near the R wave of the electrocardiogram signal on the basis of the peak point of the R wave detected by the R wave detection unit and sampling data of the electrocardiogram signal before and after the peak point and to detect the peak point of the R wave again on the basis of the estimated waveform; and an RRI calculation unit configured to calculate an RRI on the basis of time-series data of the peak point of the R wave detected by the R wave detection unit.
1 . An RRI measurement device comprising:
a first detection circuit configured to detect a peak point of an R wave from a sampling data sequence of an electrocardiogram signal of a subject;
a second detection circuit configured to:
estimate a waveform within a predetermined range of the R wave of the electrocardiogram signal based on the peak point of the R wave detected by the first detection circuit and sampling data of the electrocardiogram signal before and after the peak point; and
detect the peak point of the R wave again based on the estimated waveform; and
a calculation circuit configured to calculate an RRI based time-series data of a time Tpeak of the peak point of the R wave detected by the second detection circuit,
wherein the first detection circuit is configured to calculate time difference values for respective sampling data from the sampling data sequence of the electrocardiogram signal and detect a positive peak point of the time difference values immediately before a negative peak point of the time difference values, and set the detected positive peak point as the peak point of the R wave.
2 . The RRI measurement device according to claim 1 , wherein:
the second detection circuit is configured to obtain an approximate curve matching with three points and set a peak of the approximate curve as the peak of the R wave, wherein the three points are the peak point of the R wave detected by the first detection circuit and sampling points of the electrocardiogram signal before and after the peak point.
3 . The RRI measurement device according to claim 2 , wherein:
the second detection circuit is configured to calculate coefficients a, b, and c of the approximate curve expressed by a following expression (1):
A=aT 2 +bT+c (1)
where a value of the sampling data of the electrocardiogram signal is denoted by “A”, and a sampling time is denoted by “T”,
wherein the second detection circuit is configured to calculate a time of a peak point of the expression (1) as the time T peak of the peak point of the R wave on the basis of a time T[n] of the peak point of the R wave detected by the first detection circuit and the coefficients a and b, and
wherein the time of the peak point of the expression (1) is expressed by a following expression (2):
T peak =T[n]−b/ 2 a (2)
4 . The RRI measurement device according to claim 1 , further comprising:
a filtering circuit provided in a preceding stage of the first detection circuit and the second detection circuit, the filtering circuit configured to perform an anti-aliasing filtering process or band-pass filtering process on the sampling data sequence of the electrocardiogram signal,
wherein the first detection circuit and the second detection circuit are each configured to detect the peak point of the R wave using the sampling data sequence processed by the filtering circuit.
5 . The RRI measurement device according to claim 1 , wherein:
the RRI measurement device further comprising an Analog Digital Converter acquiring the electrocardiogram signal in real-time.
6 . The RRI measurement device according to claim 5 , wherein:
the Analog Digital Converter converts the electrocardiogram signal into digital data at a sampling rate of at least 125 samples/sec.
7 . An RRI measurement method comprising:
a first step of detecting a peak point of an R wave from a sampling data sequence of an electrocardiogram signal of a subject;
a second step of estimating a waveform within a predetermined range of the R wave of the electrocardiogram signal based on the peak point of the R wave detected in the first step and sampling data of the electrocardiogram signal before and after the peak point and detecting the peak point of the R wave again on the basis of the estimated waveform; and
a third step of calculating an RRI from time-series data of a time Tpeak of the peak point of the R wave detected in the second step,
wherein the first step comprising calculating time difference values for respective sampling data from the sampling data sequence of the electrocardiogram signal, detecting a positive peak point of the time difference values immediately before a negative peak point of the time difference values, and setting the detected positive peak point as the peak point of the R wave.
8 . The RRI measurement method according to claim 7 , wherein the second step comprises obtaining an approximate curve matching with three points and setting a peak of the approximate curve as the peak of the R wave, wherein the three points are the peak point of the R wave detected in the first step and sampling points of the electrocardiogram signal before and after the peak point.
9 . The RRI measurement method according to claim 8 , wherein:
the second step comprises calculating coefficients a, b, and c of the approximate curve expressed by a following expression (1):
A=aT 2 +bT+c (1)
where a value of the sampling data of the electrocardiogram signal is denoted by “A”, and a sampling time is denoted by “T”,
wherein a time of a peak point of the above expression (1) is calculated as the time T peak of the peak point of the R wave on the basis of a time T[n] of the peak point of the R wave detected in the first step and the coefficients a and b, and
wherein the time of the peak point of the expression (1) is expressed by a following expression (2):
T peak =T[n]−b/ 2 a (2)
10 . The RRI measurement method according to claim 7 , further comprising:
a fourth step of performing, by a filtering circuit, an anti-aliasing filtering process or band-pass filtering process on the sampling data sequence of the electrocardiogram signal prior to the first step,
wherein the first step and the second step comprise detecting the peak point of the R wave using the sampling data sequence processed by the filtering circuit.
11 . The RRI measurement method according to claim 7 , wherein:
the method further comprising a step of acquiring the electrocardiogram signal in real-time.
12 . The RRI measurement method according to claim 11 , wherein:
the method further comprising a step of converting the electrocardiogram signal into digital data at a sampling rate of at least 125 samples/sec.
13 . A non-transitory computer readable storage medium storing an RRI measurement program for causing a computer to execute a method comprising:
a first step of detecting a peak point of an R wave from a sampling data sequence of an electrocardiogram signal of a subject;
a second step of estimating a waveform within a predetermined range of the R wave of the electrocardiogram signal based on the peak point of the R wave detected in the first step and sampling data of the electrocardiogram signal before and after the peak point and detecting the peak point of the R wave again on the basis of the estimated waveform; and
a third step of calculating an RRI from time-series data of a time Tpeak of the peak point of the R wave detected in the second step,
wherein the first step comprises calculating time difference values for respective sampling data from the sampling data sequence of the electrocardiogram signal, detecting a positive peak point of the time difference values immediately before a negative peak point of the time difference values, and setting the detected positive peak point as the peak point of the R wave.
14 . The non-transitory computer readable storage medium according to claim 13 , wherein:
a second detection step comprises obtaining an approximate curve matching with three points and setting a peak of the approximate curve as the peak of the R wave, wherein the three points are the peak point of the R wave detected by a first detection circuit and sampling points of the electrocardiogram signal before and after the peak point.
15 . The non-transitory computer readable storage medium according to claim 14 , wherein:
the second step comprises calculating coefficients a, b, and c of the approximate curve expressed by a following expression (1):
A=aT 2 +bT+c (1)
where a value of the sampling data of the electrocardiogram signal is denoted by “A”, and a sampling time is denoted by “T”,
wherein a time of a peak point of the expression (1) is calculated as the time T peak of the peak point of the R wave on the basis of a time T[n] of the peak point of the R wave detected in the first step and the coefficients a and b, and
wherein the time of the peak point of the expression (1) is expressed by a following expression (2):
T peak =T[n]−b/ 2 a (2)
16 . The non-transitory computer readable storage medium according to claim 13 , wherein:
the method further comprising a step of acquiring the electrocardiogram signal in real-time.
17 . The non-transitory computer readable storage medium according to claim 16 , wherein:
the method further comprising a step of converting the electrocardiogram signal into digital data at a sampling rate of at least 125 samples/sec.