Recurrence rates for SVT after successful procedures are higher than reported in large adult series, ranging from 7% to 17%; whether this reflects technical differences, natural his- tory, or more long-term follow-up is unclear.427 429 Recurrence is highest among right-sided accessory pathways, particularly anteroseptal or multiple pathways, and in AT in the setting of complex congenital heart disease.427 429 Junctional ectopic tachycardia occurs predominantly in very young patients either as a congenital form or, more commonly, after intracardiac repair of congenital heart dis- ease. Nonpostoperative junctional tachycardia has been reported to respond to amiodarone or combination therapy including beta blockers, flecainide, procainamide, or propafe- Ablation for patients with refractory tachycardia or ventricular dysfunction has shown efficacy of 82% to 85%, but inadvertent AV block occurred in 18% and recurrence was seen in 14% of patients.130 Postoperative junctional tachy- cardia occurs in 2% to 10% of young patients undergoing intracardiac surgery, particularly for ventricular or AV septal defects, tetralogy of Fallot, transposition of the great arteries, and Norwood procedures.430,431 Treatment includes sedation with muscle relaxation, limitation of inotropic medications, reduction of core temperature to 34 to 35 C, atrial overdrive pacing, and procainamide or amiodarone infusions.416,432 435 In general, postoperative junctional tachycardia resolves and does not require ongoing therapy. Although this guideline focuses on adults, it should be noted that SVT may occur in the fetus and, if sustained, may put the fetus at risk of cardiovascular collapse mani- fested by hydrops. Mothers require safety monitoring by adult cardiologists during treatment. The most common mechanisms for fetal SVT are AVRT and atrial flutter.436 Persistent SVT with hydrops carries a high mortality rate, and therefore, prompt and aggressive treatment is war- ranted. Maternal administration of antiarrhythmic agents has been shown to be effective through transplacental delivery. 