Caliper to measure ECG diagram on any page
ECG (electrocardiogram) Calipers allows you to use electronic calipers to make measurements on images of ECGs. Use time calipers to measure intervals or heart rate, amplitude calipers to measure voltage, and angle calipers for specialized uses such as evaluating QTc values, RR rate, etc. It supports recalibration along with zoom on all pages.
To learn more about ECG: https://en.wikipedia.org/wiki/Electrocardiograph