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Intracellular calcium and vulnerability to fibrillation and defibrillation in Langendorff-perfused rabbit ventricles.

Hwang, GS; Hayashi, H; Tang, L; Ogawa, H; Hernandez, H; Tan, AY; Li, H; Karagueuzian, HS; Weiss, JN; Lin, SF; Chen, PS
Circulation, 114(24):2595-2603, 2006
Journal Title
BACKGROUND: The role of intracellular calcium (Ca(i)) in defibrillation and vulnerability is unclear.

METHODS AND RESULTS: We simultaneously mapped epicardial membrane potential and Ca(i) during shock on T-wave episodes (n=104) and attempted defibrillation episodes (n=173) in 17 Langendorff-perfused rabbit ventricles. Unsuccessful and type B successful defibrillation shocks were followed by heterogeneous distribution of Ca(i), including regions of low Ca(i) surrounded by elevated Ca(i) ("Ca(i) sinkholes") 31+/-12 ms after shock. The first postshock activation then originated from the Ca(i) sinkhole 53+/-14 ms after the shock. No sinkholes were present in type A successful defibrillation. A Ca(i) sinkhole also was present 39+/-32 ms after a shock on T that induced ventricular fibrillation, followed 22+/-15 ms later by propagated wave fronts that arose from the same site. This wave propagated to form a spiral wave and initiated ventricular fibrillation. Thapsigargin and ryanodine significantly decreased the upper limit of vulnerability and defibrillation threshold. We studied an additional 7 rabbits after left ventricular endocardial cryoablation, resulting in a thin layer of surviving epicardium. Ca(i) sinkholes occurred 31+/-12 ms after the shock, followed in 19+/-7 ms by first postshock activation in 63 episodes of unsuccessful defibrillation. At the Ca(i) sinkhole, the rise of Ca(i) preceded the rise of epicardial membrane potential in 5 episodes.

CONCLUSIONS: There is a heterogeneous postshock distribution of Ca(i). The first postshock activation always occurs from a Ca(i) sinkhole. The Ca(i) prefluorescence at the first postshock early site suggests that reverse excitation-contraction coupling might be responsible for the initiation of postshock activations that lead to ventricular fibrillation.
MeSH terms
Action PotentialsAnimalsBody Surface Potential MappingCalcium/metabolism*Electric Countershock*Heart VentriclesMyocardium/metabolism*PerfusionRabbitsRyanodine/pharmacologyThapsigargin/pharmacologyVentricular Fibrillation/etiology*Ventricular Fibrillation/physiopathology
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Journal Papers > School of Medicine / Graduate School of Medicine > Cardiology
AJOU Authors
황, 교승
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