RADIOFREQUENCY ABLATION OF INTRAATRIAL REENTRANT TACHYCARDIA AFTER SURGICAL PALLIATION OF CONGENITAL HEART-DISEASE

Background Intra-atrial reentrant tachycardia (IART), also called atri al flutter, is a common and potentially lethal complication of surgica l correction of congenital heart disease. Medical management of IART i s often problematic, which prompts an investigation of the utility of radiofrequency (RF) ablation for management of these arrhythmias. Meth ods and Results Ten consecutive patients referred for treatment of rec urrent IART after surgery for congenital heart disease were studied. M edian age was 18.4 years, and median duration of arrhythmia was 6.4 ye ars; a median of three antiarrhythmic drugs had been tried. Surgical p rocedures used were Fontan (6), Mustard/Senning (2), and biventricular repair (2). Intracardiac electrophysiological study demonstrated 30 d istinct IART circuits, defined by activation sequence and cycle length . Mean IART cycle length was 323+/-114 ms. Cycle length was significan tly longer in IART circuits that were successfully ablated compared wi th those that were not (381 versus 248 ms, P<.001). RF ablation was at tempted in 22 of these circuits. Ablation sites were targeted to presu med exit points from zones of slow conduction by electrophysiological criteria. Sites chosen in this manner clustered in four distinct areas of the right atrium. Of 22 IART circuit ablations attempted, 17 (77%) resulted in acute termination of the tachycardia. In 8 of 10 patients in whom at least one IART circuit was successfully ablated, 4 are fre e of clinical tachycardia and 3 are improved over short-term follow-up . No complications were encountered. Conclusions Multiple IART circuit s may be present in patients after surgery for congenital heart defect s. Activation sequences observed were diverse and different from those observed in atrial flutter in patients with normal anatomy. Interrupt ion of IART circuits by RF ablation is feasible using mapping techniqu es aimed at identifying an exit point from a zone of slow conduction. Short-term follow-up suggests that RF ablation may be a useful adjunct in management of IART in these difficult patients.