Time

Which is the regular time and wich is the irregular one? It depend from where you are!

Mesurment

Heart rate is generally measured by the wrist, although in some cases, such as arrhythmias in the presence of this method is inaccurate. The auscultation, ie listening to heartbeats through a stethoscope is a more effective method of measurement, as well as an electrocardiogram.
If your heart rate is higher than the norm, it is called tachycardia, bradycardia, if lower.