New Perspectives Provided by Merging Computed Tomographic Scanning and Electroanatomical Mapping of Koch’s Pyramid

Background: Atrioventricular (AV) nodal re-entrant tachycardia (AVNRT) is strongly related to the anatomy and physiology of the AV nodal and junctional area. Objectives: This study aims to precisely ascertain the localization of structures within Koch’s triangle by employing the recording of nodal potentials in conjunction with the integration of three-dimensional electrical maps merged with computed tomographic images. Methods: Five consecutive patients with typical AVNRT and an available cardiac computed tomographic scan were enrolled. High-resolution mapping was performed prior to the initial ablation attempt. Results: The low-frequency, low-amplitude humped nodal potential was consistently detected within the presumed compact node location, found in the superior septal area in three patients and in the mid-paraseptal region in two cases. The length of the region was 4.5 ± 1.2 mm, with its width measured at 2.7 ± 0.6 mm (distance from the atrioventricular membranous septum = 3 ± 0.8 mm). The nodal potential was consistently recorded alongside the slow pathway potential in the infero-septal region, anterior to the orifice of the coronary sinus (distance from the slow pathway potential to the site of His potential = 15 ± 3.2 mm). This suggests that the slow pathway electrogram likely represented the medial or distal portion of the inferior nodal extension, rather than the node itself. In all patients, successful ablation was achieved, requiring a median of 5 4–6 radiofrequency deliveries. No procedural complications were encountered. Conclusions: This study, which integrates three-dimensional electroanatomical maps with reconstructed computed tomographic datasets and utilizes specific anatomical landmarks, provides a reliable and accurate estimation of the atrioventricular conduction axis components in relation to the Koch’s pyramid boundaries.