Early voltage/calcium uncoupling predestinates the duration of ventricular tachyarrhythmias during ischemia/reperfusion.
BACKGROUND
Abnormal intracellular calcium (Ca(i)) kinetics during ischemia/reperfusion (I/R) can alter membrane voltage (V(m)) and destabilize wavefront propagation.


OBJECTIVE
We used optical mapping to investigate the hypothesis that early V(m)/Ca(i) uncoupling during a ventricular tachyarrhythmia (VT) can play a primary role in perpetuation of VT episodes.


METHODS
Seventeen Langendorff-perfused guinea pig hearts were subjected to 15 min I/15 min R. Simultaneous optical recordings of V(m) and Ca(i) signals were obtained using a dual-photodiode array. Spatiotemporal entropy (E) was used to quantify differences in V(m)/Ca(i) kinetics during VT and compare wavefront topology during the first 500 ms of a VT episode.


RESULTS
A total of 39 episodes of VT were analyzed; VT was classified as self-terminating (ST, n = 28) and non-self-terminating (NST, n = 11). The ST/VTs were further classified into short ST/VT (1 to 5 s in duration; n = 16) and long ST/VT (>5 s, n = 12). E values for NST/VTs were significantly higher than E values for both short and long ST/VTs separately as well as E values for ST/VTs as a group. Further, E values for long ST/VTs were significantly higher than E values for short ST/VTs. Wave breaks were consistently identified during periods of high E.


CONCLUSIONS
High E during the first 500 ms of the onset of VT (the first 2 to 3 beats) is significantly correlated with long ST or NST episodes. This may be related to destabilization of wave propagation that helps to perpetuate VT. Early V(m)/Ca(i) uncoupling can predestinate the development of a malignant NST/VT.
Himel
Herman D
HD
VA NY Harbor Healthcare System, Brooklyn, New York 11209, USA.
Bub
Gil
G
Yue
Yuankun
Y
El-Sherif
Nabil
N
D000818:Animals; D015220:Calcium Channels; D020013:Calcium Signaling; D016000:Cluster Analysis; D004594:Electrophysiology; D005260:Female; D006168:Guinea Pigs; D017202:Myocardial Ischemia; D015425:Myocardial Reperfusion / Q000009:adverse effects*; D040242:Risk Reduction Behavior; D017180:Tachycardia, Ventricular / Q000503:physiopathology*; D013997:Time Factors
D015220:Calcium Channels