Clinical multichannel MCG in unshielded hospital environment

From November 5th, 2001 to May 19th, 2004, 545 patients (177 with arrhythmias, 67 with WPW syndrome, 60 with Ischemic Heart Disease (IHD), 129 with different kinds of cardiomyopathy, 106 normals, 6 FMCG) have been consecutively investigated at the Catholic University of Rome, with unshielded Multichannel Magnetocardiographic Mapping (MMCG): 20 with the 9-channel system only and 525 with the 36-channel system (207 of them with both systems). 107 patients were investigated also after physical stress, carried out with a standard bicycle ergometer. In all patients MMCG was recorded at least three times, to check for reproducibility and/or for clinical follow-up, for a total of more than 1600 recordings.

MMCG was performed, with both the 9-channel and the 36-channel systems, at 1 kHz in the bandwidth DC-100 Hz. In the last 200 pts, 12-lead ECG was simultaneously recorded with amagnetic electrodes. On each patient file, post-processing and signal analysis for the quantitative assessment of ventricular repolarization and for 3D localization and electroanatomical imaging of cardiac arrhythmias, were carried out independently with two different approaches and software programs developed by CMI and by Neuromag (Finland).

The results with the two methods have been compared. For 3D electroanatomical integration of MMCG localization results, 3D cardiac models have been used, constructed from patient MRI and/or from orthogonal fluoroscopic images taken at the moment of MCG recording.

Qualitative reproducibility of MMCG was satisfactory. However the estimate of quantitative parameters has shown a certain degree of variability, which deserves further evaluation.