Non-fluoroscopic localization of a single amagnetic catheter for multiple simultaneous Monophasic Action Potential recordings

A multipurpose catheter, for magnetocardiographically (MCG) guided intracardiac electrophysiological study of cardiac arrhythmias (USA Patent N. 5,056,517 and EUR Patent N. 0428812), is described. Methods: The catheter's tip features five non-polarizable amagnetic electrodes, arranged in such a way that two orthogonal or parallel current dipoles can be generated in the patients heart. Alternatively a magnetic dipole can be generated as well. This catheter can be localized by MCG mapping and inverse solution, with a three-dimensional (3D) accuracy of 10 mm, without the use of fluoroscopy. On the basis of MCG 3D localization, the catheter is placed, as close as possible to the arrhythmogenic zone. Fine adjustments, until the 3D co-ordinates of catheter’s tip will fit those generated by the spontaneous arrhythmia, are driven by MCG mapping. The four tip electrodes are used to record simultaneously four monophasic action potentials (MAPs) with a spatial resolution of 4 mm2. Alternatively 2 MAP under local pacing can be recorded. MAPs (bandwidth DC-1KHz), digitized at 4 KHz. are simultaneously displayed on the PC monitor and written on magneto-optic disk. MAPs duration at 50% and 90% levels of repolarization (d50% and d90%) and local activation times (AT) between the local MAPs are calculated. Results: In 10 normals the average local variation coefficients of d50% and d90% were 4.5% and 5.2%. Local AT was computed with 1 msec resolution. Conclusion: MCG mapping, in combination with this new amagnetic catheter, provides non fluoroscopy-dependant single-catheter intracardiac mapping of local electrophysiological abnormalities right on a predefined arrhythmogenic area.