Paroxysmal Supraventricular Tachyarrhythmias

P aroxysmal supraventricular tachycardias (PSVTs) encompass a wide range of rhythm disorders and occur in patients of all ages, both in the absence of and in conjunction with underlying heart disease. For example, the reciprocating tachycardias (i.e., tachyarrhythmias due to reentry within the atrioventricular [AV] node or those utilizing any of several different types of accessory connectionsl'2) tend to manifest themselves initially in a younger set of patients without clinically apparent underlying structural heart disease. Although these individuals are usually considered to be at relatively low risk for life-threatening complications of antiarrhythmic drug treatment, even a rare severe adverse reaction in this group of patients is tragic. Further, the occurrence of less severe but common side effects in this set of patients can evoke a substantial psychological and economic cost. On the other hand, the primary atrial tachycardias (i.e., atrial fibrillation, atrial flutter, sinus node reentry3) more often occur in older patients and/or individuals with overt or subtle degrees of heart disease.3-5 In