Paroxysmal supraventricular tachycardia (PSVT) is another type of “short-circuit” arrhythmia. It may result either from atrio-ventricular nodal re-entrant tachycardia (AVNRT) or from an accessory pathway, which may occur as part of the Wolff-Parkinson-White (WPW) syndrome. PSVT may occur at any age and commonly occurs in patients who have no other types of heart disease. Patients with PSVT typically describe a rapid, or racing, regular heartbeat (between 130 and 230 beats per minute) that starts and stops abruptly. It is commonly misdiagnosed as a panic attack. With the exception of some patients with the Wolff-Parkinson-White syndrome, PSVT generally is not a dangerous arrhythmia. However, it can result in debilitating symptoms. Treatment options include a variety of drugs or catheter ablation, which cures the problem in most patients. In AVNRT, a small extra pathway exists in or near the AV node. If an electrical impulse enters this pathway, it may start traveling in a circular pattern that causes the heart to abruptly start beating fast and regular. Wolff-Parkinson-White syndrome occurs when there is an extra connection between the atria and ventricles (accessory pathway). The presence of this second connection between the atria and ventricles is a setup for developing a “short-circuit” arrhythmia: electrical impulses may start traveling in a circular pattern and cause the heart to beat too rapidly (AVRT: atrio-ventricular reciprocating tachycardia). Under rare circumstances, patients with Wolff-Parkinson-White syndrome can develop an extremely rapid heart rhythm abnormality that may be life-threatening. | 
