Validation of magnetocardiographic current density imaging with a non-magnetic stimulation catheter

Progress in revascularization treatment of coronary artery disease (CAD) have triggered a growing interest for new non invasive imaging and localization of myocardial ischemia and viability [13]. Most recently magnetocardiographic (MCG) source imaging has received increasing attention for that purpose, as demonstrated by the relevant number of papers presented at this conference. Different MCG parameters and indexes have been proposed to detect and localize myocardial ischemia. Although the investigation protocols and the analytic methods used by various authors are still widely different, the results seem to confirm that MCG mapping at rest and under effort contains diagnostic information additional to ECG [4-7]. Among different approaches the current-density estimation (CDE) method, by estimating the primary current distributions underlying MCG signals measured from patients suffering from acute or chronic ischemia, provides imaging and localization of ischemic injury current distribution [8-11]. On the other hand CDE has been also applied to localize malignant ventricular tachycardia [12]. Thus such ability to locate current sources, combined with precise timing of events, might be valuable in correlating the pathogenesis injury current-induced arrhythmias with ischemic events. However no systematic validation study on the localization accuracy of CDE was available so far. In this study we have used the amagnetic catheter (AC) stimulation technique [13] to evaluate, in patients, the accuracy of current density imaging on the epicardial surface in localizing intracardiac current distribution and discriminating different simultaneous active cardiac sources. The results were compared with those of a parallel computer simulation study [8]. Goldstandard to test the accuracy of CDE was the localization of the distal terminal of the same amagnetic catheters with the Equivalent Current Dipole (ECD) inverse solution [13-15]. 2 Methods