Computed bipolar electrograms from unipolar epicardial recordings

Cardiac mapping systems use either bipolar or unipolar electrodes to determine the spread of electrical activity throughout the heart. Accurate reconstruction of bipolar waveforms from unipolar pairs could offer a method for resolving inconsistencies in detecting local activation while maintaining the advantages of unipolar recordings. In this study unipolar and bipolar electrograms were recorded simultaneously from the right ventricular outflow track as wavefronts were initiated along the longitudinal and transverse axes of the epicardial fibers during activation of the right ventricle alone with superimposed activation of the left ventricle. Calculated bipolar electrograms were computed by subtracting the unipolar electrogram recorded at one pole of a pair spaced 2-mm apart from the one recorded at the other and were compared to the measured bipolar electrograms for a single beat. When the measured and calculated waveforms were compared, 94% of the electrograms had correlation coefficients of at least 0.90. Activation times were accurately selected, with the peaks of the calculated waveforms occurring within 6 ms of the peaks of the measured electrograms for all cases and within 3 ms for 99% of the pairs