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Figure 5 An example of the activation map used to determine the CV during AF. Three activation maps from the lateral wall of the left atrium during rapid constant pacing during AF with a cycle length of 86 ms are shown. (Top) The ECG (lead II) and a bipolar electrogram (Eg) of atrial activation as well as the stimulus artifact recorded from a pair of mapping electrodes are shown. The maps below correspond to atrial activation on three different occasions indicated by the encircled numbers on the electrogram. Isochrones are drawn every 4 ms. In the map on the left side (circled 1), the atrium was activated by a single broad wave front propagating from left to right. In the map at the center (circled 2), the atrium was activated by another wave front propagating in a different direction. When the atrium was captured by burst pacing (circled 3), an area with a diameter of about 2 cm was activated by uniform wavefronts radially propagating away from the site of stimulation (S). CV was obtained using this map by measuring the distance between an electrode adjacent to the stimulating electrode and the furthest electrode from the stimulating electrode in the direction of rapid propagation divided by the activation times required to propagate across a series of electrode sites. In this example, the distance between an electrode adjacent to the stimulating electrode and the furthest electrode from the stimulating electrode in the direction of rapid propagation was 8 mm (distance was shown by an arrow), and the time required for this propagation was 13 – 5 = 8 ms. Thus, the CV of the impulse was calculated to be 8 mm/8 ms = 1.0 m/s.
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