The Electroanatomic Mechanisms of Atrial Tachycardia in Patients with Tetralogy of Fallot and Double Outlet Right Ventricle

Atrial Tachycardia in Tetralogy of Fallot and DORV. Background: Atrial tachycardias (AT) are common after palliation or repair of congenital heart disease. The electroanatomic mechanism of AT in postoperative tetralogy of Fallot (TOF) and double outlet right ventricle (DORV) patients has not been fully explored. Methods and Results: Retrospective analysis of TOF or DORV patients was performed in the electrophysiology (EP) lab from January 1997 to March 2010. Sustained ATs were mapped using the Carto system (Biosense Webster, Diamond Bar, CA, USA). Fifty-eight patients were identified with 82 EP studies performed and 127 ATs identified. The first EP study for AT was performed at a median age of 35 years (2-58 years). Ninety-five IART circuits were identified, 5 in a figure-of-8 pattern. There were 13 focal ATs, 4 ectopic ATs, and 15 presentations of atrial fibrillation (AF). The cavotricuspid isthmus (CTI) was the critical area for ablation in the majority of TOF and DORV patients (53%). The CTI, along with the lateral RA wall, made up 85% of IART circuits. Excluding AF, the acute success rate for ablation was 90%. Of the 58 patients, 20 had additional ablation attempts, 19 within 3 years of their first ablation. Conclusion: The CTI and lateral RA wall are critical corridors of conduction in 85% of IART circuits in TOF and DORV patients. The acute success rate for AT ablations is high, but a substantial number of patients have required additional ablation procedures. Recurrences may be reduced if both the CTI and lateral RA wall are targeted and blocked, even if the mapped circuit points only to 1 region. (J Cardiovasc Electrophysiol, Vol. 22, pp. 1013-1017, September 2011)