Supraventricular tachycardia (SVT) means that from time to time your heart beats very fast for a reason other than exercise,
high fever, or stress. Types of SVT include:
Atrioventricular nodal reentrant tachycardia (AVNRT).
Atrioventricular reciprocating tachycardia (AVRT), including Wolff-Parkinson-White syndrome.
During an episode of SVT, the heart’s electrical system doesn't work right, causing the heart to beat very fast.