1. Date of download: 6/30/2016 Copyright © The American College of Cardiology. All rights reserved. From: Determination of refractory periods and conduction velocity during atrial fibrillation using atrial capture in dogs: Direct assessment of the wavelength and its modulation by a sodium channel blocker, pilsicainide J Am Coll Cardiol. 2000;35(1):246-253. doi:10.1016/S0735-1097(99)00488-X Arrangement of the electrodes for recording and pacing. Multiple atrial electrograms were recorded by 96 bipolar electrodes (open circles) placed at 1-mm interpolar and 2-mm interelectrode distances. A pair of electrodes (filled circles) placed at a 1-mm interpolar distance in the center of the mapping electrodes served for pacing. A bipolar electrode (hatched circles) adjacent to the stimulation electrodes was used for sensing. An electrode (double circle) next to these electrodes was used for recording unipolar atrial electrograms from which local activation intervals were measured. Figure Legend:

2. Date of download: 6/30/2016 Copyright © The American College of Cardiology. All rights reserved. From: Determination of refractory periods and conduction velocity during atrial fibrillation using atrial capture in dogs: Direct assessment of the wavelength and its modulation by a sodium channel blocker, pilsicainide J Am Coll Cardiol. 2000;35(1):246-253. doi:10.1016/S0735-1097(99)00488-X Example of unipolar and bipolar recordings used for measurement of intervals during AF. A unipolar atrial electrogram (Eg) and a bipolar atrial electrogram adjacent to the stimulation electrode are shown with intermittent introduction of single stimuli during AF at a predetermined coupling interval (CI) after the index local activation (F0). The bipolar atrial electrogram was used for sensing, and a unipolar atrial electrogram was used for measuring F0F1. (Top) At a CI of 80 ms, the F0F1 measured on two occasions were 70 and 75 ms, which were shorter than CI, suggesting that the atrium was not captured. (Middle) At a CI of 65 ms, the F0F1 were 65 and 65 ms, which were equal to CI, suggesting a possible atrial capture. (Bottom) At a CI of 60 ms, the F0F1 were 80 and 78 ms, which were longer than CI, indicating that the atrium was not captured. Figure Legend:

3. Date of download: 6/30/2016 Copyright © The American College of Cardiology. All rights reserved. From: Determination of refractory periods and conduction velocity during atrial fibrillation using atrial capture in dogs: Direct assessment of the wavelength and its modulation by a sodium channel blocker, pilsicainide J Am Coll Cardiol. 2000;35(1):246-253. doi:10.1016/S0735-1097(99)00488-X Histograms of 100 F0F1 intervals at three coupling intervals (CIs). (Top) A hundred local FF intervals in a baseline AF recorded at a unipolar atrial electrogram were plotted in a histogram, which showed a symmetrical distribution with a Mode FF of 70 ms. (Middle) The histogram of 100 F0F1 intervals obtained by repeated single extra-stimuli at CI of 65 ms appeared to be asymmetrical in distribution compared with the control histogram. (Bottom) The histogram of 100 F0F1 intervals for repeated single extra-stimuli at a shorter CI of 45 ms showed a symmetrical distribution. Figure Legend:

4. Date of download: 6/30/2016 Copyright © The American College of Cardiology. All rights reserved. From: Determination of refractory periods and conduction velocity during atrial fibrillation using atrial capture in dogs: Direct assessment of the wavelength and its modulation by a sodium channel blocker, pilsicainide J Am Coll Cardiol. 2000;35(1):246-253. doi:10.1016/S0735-1097(99)00488-X Comparison of histograms of 100 F0F1 intervals at each coupling interval (CI) with the control histogram using Mann-Whitney U test. The CIs are shown on the abscissa and the p values obtained by Mann-Whitney U test are shown on the ordinate. The figure statistically demonstrates the capture of extrastimuli with CIs ranging from 50 to 70 ms. Figure Legend:

5. Date of download: 6/30/2016 Copyright © The American College of Cardiology. All rights reserved. From: Determination of refractory periods and conduction velocity during atrial fibrillation using atrial capture in dogs: Direct assessment of the wavelength and its modulation by a sodium channel blocker, pilsicainide J Am Coll Cardiol. 2000;35(1):246-253. doi:10.1016/S0735-1097(99)00488-X 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. Figure Legend:

6. Date of download: 6/30/2016 Copyright © The American College of Cardiology. All rights reserved. From: Determination of refractory periods and conduction velocity during atrial fibrillation using atrial capture in dogs: Direct assessment of the wavelength and its modulation by a sodium channel blocker, pilsicainide J Am Coll Cardiol. 2000;35(1):246-253. doi:10.1016/S0735-1097(99)00488-X Change of the capture window by pilsicainide in each dog. The increase of the effective refractory period during AF (FRPAF) by pilsicainide was greater than the increase of mode of 100 FF intervals (Mode FF). As the result, the capture window was decreased by pilsicainide. Figure Legend:

7. Date of download: 6/30/2016 Copyright © The American College of Cardiology. All rights reserved. From: Determination of refractory periods and conduction velocity during atrial fibrillation using atrial capture in dogs: Direct assessment of the wavelength and its modulation by a sodium channel blocker, pilsicainide J Am Coll Cardiol. 2000;35(1):246-253. doi:10.1016/S0735-1097(99)00488-X Effective refractory periods at multiple cycle lengths (standard extra-stimulus method) and the effective refractory period during AF (ERPAF). The effective refractory periods determined by the standard extra-stimulus method at multiple cycle lengths and ERPAF in the baseline condition (circles) and after pilsicainide administration (squares) are illustrated. Data are shown mean ± SD. In the baseline condition, ERPAF was shorter than the effective refractory period determined by the standard extra-stimulus method (basic cycle length 150 ms). After pilsicainide administration, the effective refractory period was increased particularly at shorter cycle lengths, which was most prominent during AF, reflecting use-dependent block property of this drug. ∗ p < 0.01 versus baseline; †p < 0.05 versus baseline. Figure Legend: