Key result
Magnetocardiographic localization using a sphere model yielded a mean error of 21 mm, significantly more accurate than infinite halfspace (96 mm) and box (36 mm) models (p < 0.0001).
Why the study?
Does the choice of thorax model (sphere or box vs infinite halfspace) improve the accuracy of magnetocardiographic localization of arrhythmia substrates in patients with Wolff-Parkinson-White syndrome?
Observational (n=11)
Does the choice of thorax model (sphere or box vs infinite halfspace) improve the accuracy of magnetocardiographic localization of arrhythmia substrates in patients with Wolff-Parkinson-White syndrome?
p-value: p=< 0.0001
In magnetocardiographic localization of arrhythmia substrates, a spherical thorax model provides significantly better accuracy than infinite halfspace or box models, though further improvements are needed for clinical utility.
Sphere model may improve MCG localization in WPW; leaves open clinical utility pending larger validation studies.
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 quantum interference device" system. The underlying equivalent current dipole was computed for the delta-wave. Three models of the thorax were used: the infinite halfspace, a sphere and a box. For anatomical correlation and to define the suitable sphere and box, magnetic resonance images were obtained. As reference we used the position of the tip of the catheter, at successful radio-frequency-ablation, documented by cine-fluoroscopy. 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 conclusion, the sphere was significantly better suited than the other models tested in this study, but even with this model the accuracy of MCG localization must further improve to be clinically useful. More realistic models of the thorax are probably required to achieve this goal.
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ÅGREN et al. (1998) conducted an observational in Overt Wolff-Parkinson-White syndrome (n=11). Sphere model for magnetocardiographic localization vs. Infinite halfspace and box models was evaluated on Mean error of localization compared to catheter tip position at successful ablation (p=< 0.0001). Magnetocardiographic localization using a sphere model yielded a mean error of 21 mm, significantly more accurate than infinite halfspace (96 mm) and box (36 mm) models (p < 0.0001).
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