MAGNETOCARDIOGRAPHIC LOCALIZATION OF ARRHYTHMIA SUBSTRATES - A METHODOLOGY STUDY WITH ACCESSORY PATHWAY ABLATION AS REFERENCE

In magnetocardiographic (MCG) localization of arrhythmia substrates, a model of the thorax as volume conductor is a crucial component of the calculations. In this study, we investigated different models of the thorax, to determine the most suitable to use in the computations. Our methods and results are as follows. We studied 11 patients with overt Wolff-Parkinson-White syndrome, scheduled for catheter ablation. The MCG registrations were made with a 37-channel ''superconducting quantu m interference device'' system. The underlying equivalent current dipo le was computed for the delta-wave. Three models of the thorax were us ed: the infinite halfspace, a sphere and a box. For anatomical correla tion and to define the suitable sphere and box, magnetic resonance ima ges were obtained. As reference we used the position of the tip of the catheter, at successful radio-frequency-ablation, documented by cinef luoroscopy. Nine patients could be evaluated. The mean errors (range) when using the infinite halfspace, the sphere and the box were 96 (49- 125), 21 (5-39), and 36 mm (20-58 mm), respectively (p < 0.0001). In c onclusion, the sphere was significantly better suited than the other m odels tested in this study, but even with this model the accuracy of M CG localization must further improve to be clinically useful. More rea listic models of the thorax are probably required to achieve this goal .