Background: Ventricular fibrillation (VF) during heart failure is characterized by stable reentrant spiral waves (rotors). Apamin-sensitive small-conductance calcium-activated potassium currents () are heterogeneously upregulated in failing hearts. We hypothesized that influences the location and stability of rotors during VF.
Methods And Results: Optical mapping was performed on 9 rabbit hearts with pacing-induced heart failure. The epicardial right ventricular and left ventricular surfaces were simultaneously mapped in a Langendorff preparation. At baseline and after apamin (100 nmol/L) infusion, the action potential duration (APD) was determined, and VF was induced. Areas with a >50% increase in the maximum action potential duration (ΔAPD) after apamin infusion were considered to have a high distribution. At baseline, the distribution density of phase singularities during VF in high distribution areas was higher than in other areas (0.0035±0.0011 versus 0.0014±0.0010 phase singularities/pixel; =0.004). In addition, high dominant frequencies also colocalized to high distribution areas (26.0 versus 17.9 Hz; =0.003). These correlations were eliminated during VF after apamin infusion, as the number of phase singularities (17.2 versus 11.0; =0.009) and dominant frequencies (22.1 versus 16.2 Hz; =0.022) were all significantly decreased. In addition, reentrant spiral waves became unstable after apamin infusion, and the duration of VF decreased.
Conclusions: The current influences the mechanism of VF in failing hearts as phase singularities, high dominant frequencies, and reentrant spiral waves all correlated to areas of high . Apamin eliminated this relationship and reduced VF vulnerability.
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| http://dx.doi.org/10.1161/CIRCEP.116.004434 | DOI Listing |
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