Arrhythmias come in many types, most of which are curable. Once arrhythmia occurs clinically, an electrocardiogram should be performed as soon as possible to determine the type of arrhythmia. Common arrhythmias can be classified into tachyarrhythmias and bradyarrhythmias, and based on the location of occurrence, into supraventricular arrhythmias and ventricular arrhythmias. Clinically common are supraventricular arrhythmias, such as sinus tachycardia, junctional tachycardia, along with atrial tachycardia, atrial fibrillation, and atrial flutter. These generally do not affect the stability of hemodynamics and are relatively easy to treat. On the other hand, ventricular arrhythmias such as ventricular fibrillation, ventricular tachycardia, and sinus arrest are clinically challenging to cure and require aggressive resuscitation.