Clinical Multichannel MCG in Unshielded Hospital environment

From November 5th, 2001 to March 15th, 2004, 495 patients (164 with arrhythmias, 64 with WPW syndrome, 58 with Ischemic Heart Disease (IHD), 110 with different kinds of cardiomyopathy, 95 normals, 4 FMCG) have been consecutively investigated at the Catholic University of Rome, with unshielded Magnetocardiographic Mapping (MCG): 20 with the 9-channel system only and 475 with the 36-channel system (184 of them with both systems). 86 patients were investigated also after physical stress, carried out with a standard bicycle ergometer. In all patients MCG was recorded at least three times, to check for reproducibility and/o for clinical follow-up, for a total of more than 1600 MCG recordings. Method: MCG was performed in the supine position with a 36-channel system (CardioMag Imaging, CMI, Schenectady, NY), at a sampling rate of 1 KHz in the bandwidth DC-100 Hz, with at least one simultaneous ECG lead. 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 at the by Neuromag (Finland). The results with the two methods have been compared. For 3D electroanatomical integration of MCG 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 (see Veisterä, this conference). Conclusions: qualitative reproducibility of MCG was satisfactory. However the estimate of quantitative parameters has shown a certain degree of variability, which deserves further evaluation.