Paroxysmal supraventricular tachycardia (PSVT) is commonly encountered in the clinical practice. The typical patient with this disorder is young and experiences sudden onset of palpitation, chest discomfort, or dizziness of various frequency and duration. The rate of the tachycardia is regular (130 to 250 beats per minute). The termination of the paroxysm is abrupt and can occur spontaneously; otherwise the tachycardia is terminated by vagal maneuvers, eg, carotid sinus massage, pharmacologic interventions, electrical pacing, or direct current countershock.
In the majority of cases, the mechanism of PSVT is circus movement of the cardiac impulse.1 Reentrant excitation causing this disorder develops either between the sinus node and the right atrium or within the atria or the atrioventricular node. In a fourth common type of PSVT, the reentry loop incorporates the atria, the atrioventricular node, the ventricular myocardium, and an accessory tract between ventricles and atria. The various forms of reentrant