Stimuli resulting in stress, fear or excitement will result in a rapid heartbeat. Nerves connected to the heart regulate the speed with which the cardiac muscle contracts. Interestingly, in an average lifetime, the heart continuously beats more than 2.5 billion times. People with heart disease produce irregular sounds that are emitted for each heartbeat. A pacemaker is an electrical device that is used to stimulate regular beating of the heart for people who have heart disease.
Frequency is denoted as the number of times a regularly recurring phenomenon occurs in one second.
The number of times a heart beats in one minute is divided by 60 seconds to obtain the frequency in Hertz.