Methods to analyse epicardial mapping signals for the electrophysiological detection of viability in chronic ischemic myocardium

Epicardial mapping signals, acquired during bypass surgery, were analyzed to validate the electrophysiological detection of dysfunctional, but viable myocardium. This intraoperative epicardial mapping was performed with a sock electrode, including 102 bipolar leads. The signals were recorded, using a commercial mapping system, and analysed by custom made software tools. We developed and tested algorithms for the automated analysis of the local activation signals, to find changes in characteristic signal parameters for myocardial regions with disturbed contractility. Maximal amplitudes, activation onset and offset and the frequency content were calculated. Results of signal analysis were compared to expert analysis of the preoperative left ventricular angiogram, according to the epicardial grid of the mapping electrode, 1241 myocardial regions were classified in 17 patients, 131 as hypokinetic, 107 as akinetic and 31 as dyskinetic. The developed methods for signal analysis are feasible to determine characteristic time domain parameters in bipolar epicardial electrograms; significant differences of local amplitudes, activation markers and power distribution between regions with different contractility could be observed. These findings are of potential value for the electrophysiological identification of functionally impaired but viable myocardium in patients with chronic ischemic heart disease.