Ablation to prevent cardiac arrhythmias requires interpretation of electrograms to locate the arrhythmogenic tissue. This study examined a novel signal processing technique employing deconvolution to calculate electrograms which best fit observed electrograms. We hypothesize that the power of difference between the calculated and the observed electrogram detects changes in morphology resulting from myocardial infarction. 380 electrograms were recorded from 10 dogs. Scintigraphic studies with Thallium-201 identified recording sites as normal or infarcted tissue. The power of the difference increased 65 percent for infarcted tissue as compared to normal tissue (p