Cardiac rhythm is “an electrical impulse generated by highly specialized fibers capable of spontaneously producing and propagating electrical impulse in the myocardium”. When we hear the term “Arrythmia”, it refers to any problem in the rate or rhythm of a person’s heartbeat. During an arrhythmia, the electrical impulses may be too fast, too slow or erratic, causing an irregular heartbeat.

Source: https://www.heart.org/en/health-topics/arrhythmia/about-arrhythmia