Cardioplegia Defibrillation of Circulatory Phase Ventricular Fibrillation in a Swine Model: Three Randomized Controlled Trials

Introduction: We previously found potassium cardioplegia followed by rapid calcium reversal (K plegia) can achieve defibrillation in a swine model of electrical phase ventricular fibrillation (VF) comparable to standard care. Hypothesis: Exploring 3 possible potassium (K) dose and timing protocols, we hypothesize K plegia may benefit resuscitation of circulatory phase VF. Methods: Three separate blinded randomized placebo-controlled trials were performed with electrically-induced VF untreated for durations of 6,9, and 12 minutes in a swine model. All experimental groups received infusion of 1 or 2 boluses of intravenous (IV) K followed by a single calcium reversal bolus. Only K was replaced by saline in the control groups. All other treatments were the same. Outcomes included: amplitude spectrum area (AMSA) during VF, resulting rhythms, number of defibrillations, return of spontaneous circulation (ROSC), and hemodynamics for 1 hour post ROSC. Single nominal and interval outcomes were compared with Fisher’s Exact test and Mann-Whitney U, respectively. Results: Twelve, 12, and 8 animals were included at 6, 9 , and 12 minute VF durations for a total of 32. ROSC, average number of shocks, and post-ROSC norepinephrine requirement are listed below. 4/6 K plegia and 2/6 control animals achieved ROSC in the 9 minute protocol, (p=0.24). Two of 8 animals that achieved ROSC with K plegia did so without electrical defibrillation. Conclusions: The majority of animals achieved ROSC after up to 9 minutes of untreated VF arrest using K plegia protocols. K plegia requires further optimization for both peripheral IV and intraosseous infusion, and to assess for superiority over standard care.