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demonstration requires the use of several electrode cath-eters and mapping of the line of block. The aim of this study was prospectively to test the feasibility of a simplified ablation procedure using only two catheters. Methods Radio frequency (RF) ablation of common atrial Results Surface ECG criteria were met in 26 patients. Mapping the line of lesions showed a complete corridor of parallel double potentials in these 26 cases and in 3 of the 4 patients in whom ECG criteria were not met. Conduction evaluated with the Halo catheter showed bi-directional Catheter ablation is an effective treatment in the man-agement of this supraventricular tachycardia[1–3]. Radio work from our laboratory suggests that surface 12-lead ECG criteria could be used to establish the presence offrequency current is successfully delivered to the caudal end of the re-entrant circuit in the myocardial isthmus between the inferior vena cava and the tricuspid valve (IVCT isthmus). In recent studies, achievement of a complete conduction block in the IVCT isthmus has been shown to be an endpoint predictive of a sig-nificantly lower recurrence rate[4–6]. However, its conduction block within this isthmus[8]. Major concern on the use of these surface ECG criteria is about their capability to assess the completeness of the block. The presence of well separated double-potential electrograms during precise mapping of the line of block during atrial pacing is an elegant way to prove that the block is complete[9–10]. Moreover, the disclosure of points of merging double-potential electrograms allows the diag-nosis of incomplete block and localizes the zone of residual conduction, the gap, where subsequent radio frequency (RF) lesions are applied[9]. A simplified ap-proach using surface 12-lead ECG criteria to establis