Supraventricular tachycardia
Supraventricular tachycardia (SVT) is an umbrella term for fast heart rhythms arising from the upper part of the heart. This is in contrast to the other group of fast heart rhythms – ventricular tachycardia, which starts within the lower chambers of the heart.
Source: Wikipedia — Supraventricular tachycardia (CC BY-SA 4.0)