Supraventricular tachycardia is a disorder of the heart. It is characterized by an accelerated heart rate, which occurs in the atrioventricular node. A tachycardia by definition consists of clinical perception of the rapid heart, or an unusual heart rate. Tachycardia differs from tachyarrhythmias in that in the former the heart is perceived to be fast but always rhythmic, without variations in pulse frequency, while in tachyarrhythmias the heart is also perceived to be rapid, but the pulse is arrhythmic, not regular. Although all tachyarrhythmias are abnormal, not all tachycardias are abnormal, clearly differentiating between a reactive physiological sinus tachycardia, which can be perceived after an emotion, physical exercise, etc. And it has very clear characteristics: it increases progressively until a maximum limit and it descends always progressively, whereas the abnormal tachycardias (that respond to the activation of abnormal electric circuits within the heart), they present / display a characteristic typically common, and are that they respond to The law of "all or nothing", ie the heart is abruptly activated, for example from 60 to 150 beats per minute and is abruptly cut from 150 to 60.