Superiority of Biphasic Over Monophasic Defibrillation Shocks Is Attributable to Less Intracellular Calcium Transient Heterogeneity
Gyo-Seung Hwang, MD, PhD*,
Liang Tang, PhD ,
Boyoung Joung, MD, PhD,
Norishige Morita, MD, PhD*,
Hideki Hayashi, MD, PhD*,
Hrayr S. Karagueuzian, PhD ,
James N. Weiss, MD,
Shien-Fong Lin, PhD and
Peng-Sheng Chen, MD,*
* Division of Cardiology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California
Departments of Medicine (Cardiology) and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, California
Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis, Indiana
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Figure 1 Dual Optical Mapping of Failed Defibrillation With Monophasic and Successful Defibrillation With Biphasic Shocks
The left panels of A and B show the time course of the average fluorescence of the entire mapped region after a monophasic (upper trace) or biphasic shock (lower trace). Right color panels show fluorescence intensity snapshots after a failed shock (400 V) delivered at 0 ms. Red, blue, and green line segments indicate the time of shock, the time of intracellular calcium (Cai) sinkhole formation, and the end of the isoelectric window, respectively. The yellow plus symbols on maximum shock (Vm) maps are at the same location as the yellow plus symbols on the Cai maps. White and green arrows indicate Cai sinkhole and first post-shock activation, respectively.
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Figure 2 Comparison Between Successful BW and Unsuccessful MW Shocks of the Same Strength
There were significant differential effects of monophasic waveform (MW) (diamonds) and biphasic waveform (BW) (squares) shocks on the peak (maximum) area showing simultaneous depolarization of the membrane potential after shock (VmP) and the peak (maximum) area showing higher than average intracellular calcium after shock (CaiP), as well as time from shock to the peak area showing simultaneous depolarization of the membrane potential after shock (VmPT) and time from shock to the peak post-shock intracellular calcium (CaiPT).
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Figure 3 Comparison Between Unsuccessful BW and Unsuccessful MW Shocks of the Same Strength
There were no differences of VmP and CaiP for MW (diamonds) and BW (squares) shocks of the same strength. However, there were significant differences of VmPT and CaiPT. Abbreviations as in Figure 2.
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Figure 4 The Change of APD70 and CaiD70 After MW and BW Shocks Delivered at Different Coupling Intervals
The MW and BW shocks resulted in different action potential duration between phase 0 and 70% repolarization (APD70) and CaiD70 when the coupling interval was short (160 ms) but not when the coupling interval was 300 ms. The optical signals were generated by averaging the fluorescence of the entire mapped region. Abbreviations as in Figure 2.
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Figure 5 Delta APD and Cai Transient Duration Maps and Virtual Electrode Distribution During a 300 V Monophasic Shock
(A) Effects of shock (S) on the optical recordings at the sites indicated by arrows in B. (B) Virtual anode (blue) and virtual cathode (red) during the monophasic shocks. (C) Difference (delta) map between the action potential duration (APD) of the post-shock beat (APD2) constructed by subtracting APD2 of a cathodal shock from APD2 of an anodal shock. White to red colors indicate longer APD at the virtual anode than at virtual cathode, whereas the difference is reversed at surrounding sites. Abbreviations as in Figure 1.
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