Wavefront orientation effects on bipolar epicardial electrograms

It is determined whether information about wavefront orientation could be extracted from electrograms recorded from bipolar electrodes with poles 2 mm apart. Wavefront orientation was measured by using the line connecting the poles of each bipolar electrode as one side of the angle and the tangent to the approaching wavefront at the center of the electrode pair as the other side. Electrograms recorded from sites with small angle wavefront orientation (0°⩽angle⩽30°) had significantly lower (p⩽0.0002, Wilcoxon rank sums test) peak-to-peak amplitudes, maximum amplitudes, and maximum slopes than did electrograms recorded from sites with large angle wavefront orientations (60°⩽angle⩽90°). Electrograms were also classified by shape into groups having 0, 1, 2, or 3 peaks with most electrograms characterized by a single peak (78% for large angle electrograms versus 57% for small angle ones). There were significant differences between the small and large angle groups given the shapes of the electrograms with the most significant differences occurring for electrograms with a single peak