Supraventricular Arrhythmia (also called Supraventricular Tachycardia or SVT)

This is an abnormally rapid heart rhythm initiated from an area in the atrium or AV node that takes over the normal rhythm. The resulting heart rhythm is fast and usually regular.

Wolf-Parkinson-White Syndrome (WPW)

This is characterized by an extra electrical pathway (bypass tract) that is present at birth.

The bypass tract connects the atrium (top chamber) to the ventricle (lower chamber) and conducts the electrical impulse between upper and lower chambers more quickly than the normal conduction pathway.

A supraventricular arrhythmia may result if the normal pathway and the bypass tract create a circular electrical circuit.

WPW is also dangerous in patients who have atrial fibrillation, because the rapid, chaotic atrial impulses in the atrium can travel through the bypass tract to the ventricle and result in a very rapid heart rate.

AV Nodal Reentrant Tachycardia (AVNRT)

This condition is characterized by two electrical pathways through the AV node rather than one single electrical pathway.

The double pathways within the AV node can cause the electrical signal to move through a cicular loop (reentry), producing Supraventricular Tachycardia.