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INTRODUCTION Catheter ablation (CA) of atrial tachyarrhythmias (ATs) in patients with complex congenital heart disease (CHD) often requires technically challenging transbaffle or transconduit puncture. The aim was to assess the feasibility and safety of transbaffle/transconduit puncture based on computed tomography (CT) three-dimensional (3D) reconstruction merged with electro-anatomical mapping (EAM) without per-procedure echocardiographic guidance. METHODS AND RESULTS We included 18 consecutive CHD patients in two centers who had atrial-switch or Fontan surgery and underwent CA of AT by an antegrade approach requiring intracardiac puncture. Twelve patients with atrial-switch surgery and six patients with extracardiac Fontan surgery were referred for CA of AT. Cardiac CT with 3D reconstruction was performed before the procedure. The 3D volume of the systemic venous atrium or extracardiac conduit acquired by EAM was merged with the corresponding CT 3D reconstruction. The ablation catheter was positioned at the optimal puncture site. Under fluoroscopic guidance, the needle was positioned next to the ablation and the puncture was performed. Balloon expansion of the puncture site was performed in every case of transconduit puncture and in two (17%) cases of transbaffle puncture. Overall, 17 intra-atrial reentrant tachycarrythmias and 9 focal ATs were successfully ablated, with no acute complications. The median time to access the pulmonary atrium was 78.5 minutes (range, 55-185) and total median fluoroscopy time was 23 minutes (range, 7-53). CONCLUSIONS Transbaffle and transconduit punctures can be performed safely in CHD patients by using a simple technique relying on CT 3D reconstruction and EAM.

We present a case of sudden cardiac arrest 7 hours after radiofrequency ablation of the atrioventricular junction for symptomatic permanent atrial fibrillation unresponsive to medical therapy. The Holter monitoring revealed a progressive increasing of QT interval after the procedure, highlighting the repolarization instability after acute changes in heart rates associated with modification of ventricular activation, leading to occurrence of short coupling interval ventricular extra beats and finally to a "torsade de pointes." This illustration underlines the need to program a relatively rapid ventricular rate first weeks after junction ablation, especially in case of rapid ventricular rate prior to the procedure, as well as the role of continuous ECG and QT interval monitoring during hospital stay.