Learn / Foundations
ECG foundations
Time and voltage
Convert a caliper span to milliseconds and millivolts at half-box precision.
Understand the measurements
Measure one RR interval
The RR interval is the time between two ventricular depolarisations. Everything about rate comes from it.
Measure the R wave height
Amplitude is read from the isoelectric baseline, the flat line between the T wave and the next P wave, not from the bottom of the S wave.
Count large boxes between R waves
Counting large boxes between R waves is the first step of the 300 method for rate.