Computing ischemic regions in the heart: On the use of internal electrodes

In order to better locate ischemic regions in the heart using electrical measurements and inverse solutions, we explore the possibility for supplementing BSPM data sets with additional internal electrodes in the esophagus. We investigated whether such internal electrodes closer to the heart's surface could significantly improve the ability to pinpoint ischemic regions. A framework based on exercise ECG testing and a mathematical model for identifying ischemic regions from ECG measurements was implemented to test the effect of potential internal electrodes. This method identifies areas with abnormal perfusion by minimizing the difference between recorded and simulated ECGs. To investigate the effect of the extra electrodes in the esophagus, we computed the location of the ischemic zones with and without the internal electrodes for both synthetic data and using clinically obtained BSPMs. Computations based on pure synthetic data illuminate that, if an ischemic region is close to an electrode in the esophagus, then the use of internal electrodes might improve the result significantly. However, the simulations also indicate that ischemic areas further away from the internal electrodes are not better recovered with the use of such additional ECGs. This study indicates that the use internal electrodes, along with standard BSPMs, might improve the accuracy of the inverse ECG technology.