Critical Link between Calcium Regional Heterogeneity and Atrial Fibrillation Susceptibility in Sheep Left Atria

Figures

• 

  Figure 1. Experimental set-up for dual optical mapping of Vm and [Ca2+]i. (A) Picture and (B) schematic diagram of the optical design.

• 

  Figure 2. Experimental preparation and signal examples recorded during atrial pacing. (A) Picture of LA endocardial surface preparation. (B) Representative ECG signals (black), optical action potential (blue) and calcium transient signals (red) during pacing at pacing cycle length = 1000 ms. PV, pulmonary veins; LAA, left atrial appendage; FW, free-wall; LCx, left circumflex coronary artery.

• 

  Figure 3. Lack of cross-talk between optical measurements of Vm and [Ca2+]i. (A) Signals recorded from two cameras to detect Vm and [Ca2+]i when the LA preparation was stained with RH237 but not Rhod-2 (top panel) and Rhod-2 but not RH237 (lower panel). Note the lack of cross-talk between Vm and [Ca2+]i cameras. (B) Signals recorded from 2 cameras to detect Vm and [Ca2+]i when the LA preparation was stained with RH237 and Rhod-2 (top panel). Δt was calculated as time to peak to Ca2+ transient minus time to peak to AP (lower panel).

• 

  Figure 4. Action potential duration in three regions of the LA by pacing at three different stimulation sites. (A) Representative optical action potential under control perfusion (Ctl) or immediately after administration of acetylcholine (Ach 10 µM) measured in three regions (area of measurements, PV, LAA, FW, top to bottom) at three different pacing sites (PV, LAA, FW, left to right). (B) Mean data for action potential duration at 80% (APD80, left panel) and 50% (APD50, right panel) repolarization at three pacing sites (PV, LAA, FW, top to bottom) measured in three regions PV (purple), LAA (green), FW (blue) under control perfusion (Ctl, open bar) or after administration of acetylcholine (Ach, grey bar). N = 15; One-way ANOVA followed by a Tukey’s multiple comparison test ** p < 0.01, *** p < 0.001, **** p < 0.0001.

• 

  Figure 5. Calcium transient in three regions of LA by pacing at three different stimulation sites. (A) Representative optical calcium transient under control perfusion (Ctl) or immediately after administration of acetylcholine (Ach 10 µM) measured in three regions (area of measurements, PV, LAA, FW, top to bottom) at three different pacing sites (PV, LAA, FW, left to right). (B) Mean data for calcium transient decay time to 50% (TD50) at three pacing sites (PV, LAA, FW, top to bottom) measured in three regions PV (purple), LAA (green), FW (blue) under control perfusion (Ctl, open bar) or after administration of acetylcholine (Ach, grey bar). N = 13; One-way ANOVA followed by a Tukey’s multiple comparison test * p < 0.05, ** p < 0.01, *** p < 0.001.

• 

  Figure 6. Temporal characteristics of [Ca]i-Vm relationship. (A) Representative activation map for Vm (top panel) and [Ca]i (lower panel) for three pacing sites (PV, LAA, FW, left to right). The site of stimulation is represented as a yellow star. (B) Mean data for Vm-Ca2+ delay (Δt) at three pacing sites (PV, LAA, FW, left to right) measured in three regions PV (purple), LAA (green), FW (blue) under control perfusion (Ctl, open bar) or after administration of acetylcholine (Ach, grey bar). N = 10; One-way ANOVA followed by a Tukey’s multiple comparison test * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001.

• 

  Figure 7. Detailed dynamic analysis of AF episodes (A) Vm and [Ca2+]i signals during acute AF episodes. (B) Example of dominant frequency (left) and regularity index (right) during AF triggered at PV (top) and LAA (bottom) sites. (C) Mean data for dominant frequency (left) and regularity index (right) at LAA (green) and PV (purple) sites. N = 4–5; unpaired t-test. (D) Phase mapping analysis of AF episodes (snapshot of phase values with 20 ms intervals for AF episodes triggered by PV (top) and LAA (bottom) pacing). (E) Mean data for rotor number (top) and duration (bottom). N = 4–5; unpaired t-test.

• 

  Figure 8. RyR stabilization does not prevent acute AF episodes. (A) Example of ECG traces, with or without Dantrolene, a RyR inhibitor. (B) Inducibility of AF for each group. Dantrolene does not change AF vulnerability. N = 16 and 5, chi-square test.