Magnetocardiographic mapping of reentry tachycardias

Nowadays the atrial approach is preferred for catheter ablation of accessory pathways (APs), to minimise the operative risk, especially in the left heart. In this study magnetocardiographic (MCG) mapping during reentry tachycardias (RTs) has been used to attempt non-invasive preoperative localization of the atrial insertion of the APs. 10 patients are reported, in whom MCG mapping was performed during RTs due to Kent bundles (K), "Mahaim" fibres or dual A-V nodal pathways. In spite of single channel MCG mapping, localization of retrograde atrial activation was achieved in all patients with K. MCG activation pattern was consistent with reentry within the nodal area in only one patient with dual A-V nodal pathways. In the patient with the "Mahaim" fibre, MCG mapping during LBBB-like RT was useful to localize the fascicular insertion of the AP. Further investigation with modern multichannel instrumentations is needed.