How to calculate the heart rate from an ECG signal?

Hi, I have for example this ecg signal from how I did the plot in time:

load 'sig.mat'
fs = 300;
t=linspace(0,length(sig)/fs,length(sig));
figure()
plot(t,sig/max(sig));
title('Signal in Time Domain');
xlabel('Time(s)');
ylabel('Amplitude');

And from the plot I roughly calculate in the x axis the time between one peak (R wave) to the other. That is circa 1.5 s. If the distance between two R peaks in an ECG is approximately 1.5 seconds, I calculate the heart rate based on that interval.

Converting 1.5 seconds to milliseconds:

1.5 seconds * 1000 = 1500 milliseconds

Now, we can calculate the heart rate:

Heart Rate = 60,000 / 1500 = 40 beats per minute

Therefore, with a distance between two R peaks of approximately 1.5 seconds, the heart rate would be around 40 beats per minute.

There is a more precice way to calculate the heart rate from an ECG signal?

Attention this signal is not filtered. Is better to filter first? And if so, how?

[Cris LaPierre]

No need to convert to milliseconds

HeartRate = 60/1.5 % seconds/min * beats/sec = beats/min

HeartRate = 40

Answer 1

[Cris LaPierre]

See this answer: https://www.mathworks.com/matlabcentral/answers/374766-determining-average-heart-rate-of-ecg-signal

There is also a tool for this in the File Exchange: https://www.mathworks.com/matlabcentral/fileexchange/73049-calculate-heart-rate-from-electrocardiogram-data

[HelpAStudent]

with findpeaks it not help me to find just the R peaks that I want. Since if I do the mean of the distance between this peaks I can't find a normal heart rate.

load sig.mat

% plotting

fs=300;

t = linspace(0,length(sig)/fs,length(sig));
f = linspace(- fs/2, fs/2, length(sig));

figure()
plot(t,sig)
title("signal")
xlabel("seconds")
ylabel("A.U.")

figure()
plot(f,fftshift(abs(fft(sig))))
title("signal spectrum")
xlabel("Hz")
ylabel("Amplitude")

% filtering

sig_noDC = sig - mean(sig);

freq1 = 49;
freq2 = 51;
w1 = freq1/(fs/2);
w2 = freq2/(fs/2);
w = [w1 w2];

[b,a] = butter(3, w, "stop");
filtered_sig = filtfilt(b,a,sig_noDC);

freqX = 0.5;
wX = freqX/(fs/2);

[b,a] = butter(3,wX,"high");
filtered_sig = filtfilt(b,a,filtered_sig);

figure()
plot(t,filtered_sig)
title("filtered signal")
xlabel("seconds")
ylabel("A.U.")

figure()
plot(f,fftshift(abs(fft(filtered_sig))))
title("filtered signal spectrum")
xlabel("Hz")
ylabel("Amplitude")

[pks,locs,w,p] = findpeaks(sig); %find R peak
meanw = mean(w) %w is the width of all the peaks

meanw = 4.7879

heartRate = mean(w)*60

heartRate = 287.2740

[Cris LaPierre]

You will need to spend some time finding the appropriate settings for your findpeaks function call. It also wouldn't hurt to filter your signal, though with the prominence of the R peaks, that's proabably not necessary.

Consider doing this interactive in a live script using the Find Local Extrema live task.

You may find this page helpful, too: https://www.mathworks.com/help/matlab/data_analysis/cleandatawithliveeditortasks.html