Biomagnetic noninvasive localization of accessory pathways in Wolff-Parkinson-White syndrome.

It was our purpose to assess the clinical relevance of noninvasive magnetocardiographic localization of accessory pathways. Nine patients with Wolff-Parkinson-White (WPW) syndrome were studied. For all of them the site of the accessory pathway was known from invasive catheter mapping. A 37-SQUID (superconducting quantum interference device) sensor multichannel system (KRENIKON) was used, allowing synchronous registration with all channels. The site of the electrophysiological activity at the beginning of the delta wave was determined. Magnetic resonance images of the heart were obtained to correlate the biomagnetically localized activity with the anatomy. Magnetocardiographic localization of the bypass tract corresponded with catheter mapping with a spatial difference of 0-5 cm, 1.8 cm on the average, compared to the results obtained by catheter mapping. Thus, magnetocardiography is a promising new method for noninvasive localization of accessory pathways in WPW patients. This may streamline further invasive procedures.