What defines supraventricular tachycardia?

Supraventricular tachycardia (SVT) is characterized by a fast heart rate that originates above the ventricles, specifically in the atria or the atrioventricular (AV) node. The defining feature of SVT is the heart rate, which typically ranges from 150 to 250 beats per minute. This rapid rate is due to a reentrant circuit or abnormal electrical activity that causes the heart to beat faster than normal.

The correct definition highlights that the fast rate originates above the ventricles, signifying that the source of the tachycardia is not from the ventricles themselves but rather from the heart's upper chambers. In contrast, other choices either misstate the range of heart rates or describe other cardiac conditions that do not fit the specific criteria of SVT.