Abnormal heart rhythm due to electrical disturbances in the atria (the upper chambers of the heart) or the AV node "relay station", leading to fast heart beats. Examples of atrial arrhythmias includes atrial fibrillation, atrial flutter, and paroxysmal atrial tachycardia (PAT).

Abnormally rapid heart rhythms, medically termed tachycardia.

Abnormally slow heart rhythms, medically termed bradycardia.

Abnormal rapid heart rhythms (arrhythmias) that originate in the lower chambers of the heart (the ventricles). Ventricular arrhythmias include ventricular tachycardia and ventricular fibrillation. Both are life threatening arrhythmias most commonly associated with heart attacks or scarring of the heart muscle from previous heart attack.

Any disturbances of the normal rhythmic beating of the Heart or Myocardial Contraction. Cardiac arrhythmias can be classified by the abnormalities in Heart Rate, disorders of electrical impulse genera [..]

Irregular Heart Rate caused by abnormal function of the Sinoatrial Node. It is characterized by a greater than 10% change between the maximum and the minimum sinus cycle length or 120 milliseconds.