Small conductance calcium activated K+ channel inhibitor decreases stretch induced vulnerability to atrial fibrillation

Figures

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  Fig. 1. Graphical representation of the protocols used for the two studies, and picture of the preparation. mmHg refers to LA balloon pressure. Please note that the atrial stretch was held for 5 min before AERP or burst pacing commenced. For study 1n = 22; study 2n = 13.

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  Fig. 2. Effect of atrial stretch on atrial refractoriness. Time plot of the changes in AERP during the study before and after stretch in the vehicle control group (A; black) and treatment group (ICA 1 µM) (B; red). Data are presented as mean ± SEM, n = 11. Multiple comparisons tests were performed. For simplicity only the comparisons: baseline to 30 min; baseline to 0 mmHg, 0 mmHg to 20 mmHg; 20 mmHg to 0 mmHg are shown. mmHg refers to LA balloon pressure. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

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  Fig. 3. Effect of atrial stretch and ICA on action potential durations. (A,B) Effects of intervention on atrial APD90 (A,B), n = 11; and ventricular APD90 recorded at pacing basic cycle length of 200 ms (C,D) n = 9 and 10. Data are presented as mean ± SEM. Vehicle control group at top (black) and treatment group (ICA 1 µM) at bottom (red). Multiple comparisons tests were performed. For simplicity only the comparisons: baseline to 30 min; 0 mmHg to 20 mmHg; 20 mmHg to 0 mmHg are shown. mmHg refers to LA balloon pressure. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

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  Fig. 4. Number of sustained AF episodes. Accumulative number of sustained AF (AF > 2 min) episodes during the 5 atrial stretch levels before (black) and after (red) perfusion with ICA 1 µM. n = 13. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

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  Fig. 5. Individual AF durations. Individual AF durations (>2 s) induced by atrial burst pacing before (A, black) and after perfusion with ICA 1 µM (B, red) at 5 different stretch levels. Top panel shows example of atrial action potential recordings before, during and after burst. Data are presented as box and whiskers with median and 25–75 percentile, n = 13. Note that the Y-axis is logarithmic. mmHg refers to LA balloon pressure. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

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  Fig. 6. Incidence of AF. Incidence (%) of bursts resulting in AF > 2 s. Dots represents the incidence for each animal at each level of balloon pressure. A) before (black) and B) after perfusion with ICA 1 µM (red). Data are presented as box and whiskers with median and 25–75 percentile, n = 13. mmHg refers to LA balloon pressure. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

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  Fig. 7. Frequency distribution of AF episode durations. Relative frequencies of the AF (>2 s) episodes before (A, black) and after ICA 1 µM (B, red). X-axis is divided in 2 s bins, except for the last bin which includes all AF episodes longer than 10 s. n = 13. mmHg refers to LA balloon pressure. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

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  Fig. 8. AF duration increases with stretch. Total AF duration recorded at the different stretch levels before (black) and after ICA 1 µM (red). A positive linear correlation was found for the effect of stretching the left atrium and the AF duration (insert formula) at baseline. The two linear regressions (stretch and AF duration (baseline) vs stretch and AF duration (ICA) are significantly different. n = 13. mmHg refers to LA balloon pressure. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)