Effect of epinephrine on frequency content of ventricular fibrillation and probability of spontaneous defibrillation

Epinephrine stabilizes ventricular fibrillation (VF) in the isolated perfused rabbit heart. We tested the hypothesis that epinephrine allows sustained fibrillation by increasing the rate and dispersion of its frequency content. VF was induced in sixteen isolated rabbit hearts, under control conditions and in the presence of epinephrine (100 μg/L). The probability of spontaneous defibrillation was determined in 8 hearts (155 episodes). The frequency content of VP was determined in a separate group of 8 hearts using fast Fourier transform of epicardial monophasic action potential (MAP) recordings (23 episodes). The probability of spontaneous defibrillation was 29% under control conditions and 8% with epinephrine (p<0.05). The mean dominant frequency of fibrillation was 10.0±0.2 Hz with a narrow bandwidth under control conditions and 14.1±0.2 Hz with a wider bandwidth after epinephrine, p<0.0001. These results suggest that, in isolated rabbit hearts, epinephrine increases the mean rate and dispersion of fibrillation leading to its stabilization