ECG R wave amplitude calculation

How can I calcualte the amplitude of R-waves in a ECG signal?

Answer 1

[Star Strider]

Probably the easiest way is to use the findpeaks (link) function.

[sam van Bohemen]

Thanks

I have been using findpeaks to find the peaks, but I cannot find the min values. I have read you can use the inverse of the signal to find the min values, but I have not been able to implement it correctly

[Star Strider]

My pleasure.

How easy that is to do depends on the lead you’re using. The ‘min’ values are the isoelectric baseline, generally taken to be defined by the end of the P wave and the beginning of the QRS complex (assuming no arrhythmias, no conduction delays, and no baseline wander from movement artefact that makes everything else difficult even for human EKG interpretation). In a normal EKG, the QRS complex is less than 120 ms in duration. So one estimate of the isoelectric potential would be at least 60 ms prior to the R wave peak, and probably between 70 and 90 ms.

If by ‘min’ you want the Q wave (that may not exist in a healthy EKG, although that also depends on the lead), that can be much more difficult to determine, both because of its relatively low voltage (less than 0.1 mV or 100 in a healthy heart, so it can get lost in ambient noise), and that it may not be identifiable at all.

In short, I would define the ‘min’ value as the isoelectric region, and be done with it.