Frequency variation of ventricular fibrillation may help predict successful defibrillation in a rat model of cardiac arrest

Background: To evaluate whether the frequency variation of ventricular fi brillation (VF) helps to predict successful defi brillation in a rat model of cardiac arrest. Methods: VF was induced in rats followed by cardiopulmonary resuscitation and then defibrillation. The electrocardiographic signals of 30 rats with first-shock success were obtained from our previous animal experiments, and 300 rats without fi rst-shock success were selected as control. The VF waveform immediately before the fi rst defi brillation was analyzed. Results: Eighty-eight percentages of the frequency variations of an electrocardiogram (ECG) record falling in the range -9.5-9.5 Hz was selected with sensitivity of 0.8, specifi city of 0.583, and area under curve (AUC) of 0.708. Compared with amplitude spectrum area (AMSA) (sensitivity = 0.767, specifi city = 0.547, and AUC = 0.678), combining frequency variation and AMSA significantly increases the predictability with sensitivity of 0.933, specifi city of 0.493, and AUC of 0.732 (p = 0.005). Conclusions: The frequency variation of VF may serve a useful parameter to predict defi brillation success.