Cardiac Magnetic Source Imaging (CMSI) is a new method for three-dimensional (3D) functional localization and non fluoroscopic imaging of cardiac electrophysiological (EP) phenomena, by integration of magnetocardiographic mapping (MCGM)and magnetic resonance imaging (MRI). Here a novel patented amagnetic catheter (AC) is described, which provides single catheter simultaneous recording of four monophasic action potentials (Multi-MAP function) and can be localized and 3D imaged by CMSI performed on-line during the EP study (EPS). Methods: The 6F AC features seven non-polarizable amagnetic electrodes, arranged in such a way that orthogonal or parallel current dipoles can be generated in the patients heart. This assembly can be localized by CMSI, with a 3D accuracy of 2-7 mm, without the use of fluoroscopy. On the basis of preoperative MCGM 3D localization of the area of onset of a focal arrhythmia, the AC can be driven, under fluoroscopic control, as close as possible to the arrhythmogenic zone. Once reached the suspected arrhythmogenic area, the tip electrodes are used to record simultaneously four MAPs from an area of about 3.5 mm2. Two side electrodes can be used for local pacing and simultaneous 4MAP recording. MAP signals are differentially amplified, bandpass filtered (DC-1kHz) and digitized at the sampling frequency of 2-4 kHz. MAP duration at 50% and 90% levels of repolarization and local conduction times between the phase 0 of the four MAPs are automatically calculated with a custom software. Results: With this AC, the average amplitude of right atrial MAP (10 patients) was 6.2 ± 2.4 mV and that of the right ventricular (RV) MAP (15 patients) was 23 ± 9 mV. Local variation coefficients of RV MAP duration at 50% and 90% level of repolarization were 7.4% and 3.1%, respectively. In 3/5 patients with focal atrial arrhythmias, the multi-MAP recording technique detected local repolarization inhomogeneity and/or areas of slow conduction or focal block. In two patients EAD- or DAD-like signals were also clearly recorded. Conclusion: In patients with focal arrhythmias the novel CMSI-guided multi-MAP recording technique, is useful to detect local electrophysiological abnormalities, with a single catheter directly positioned at the arrhythmogenic area pre-defined on the basis of preoperative non invasive MCGM. This method therefore has the potential to reduce invasivity and fluoroscopy time during EPS and ablation.
- magnetic imaging
- monophasic action potential