What is the ratio associated with the rate of beats per min

Tachycardia is a fast heart rate, defined as above 100 bpm at rest. Bradycardia is a slow heart rate, defined as below 60 bpm at rest. During sleep a slow heartbeat with rates around 40-50 bpm is common and is considered normal. When the heart is not beating in a regular pattern, this is referred to as an arrhythmia.