Contributor: Ricky Dhaliwal, MD, JD Educational Pearls: Ventricular Fibrillation (VF) is a potentially fatal cardiac arrhythmia; Refractory VF even more so Epinephrine stimulates alpha and beta receptors which increase sympathetic tone, thereby increasing cardiac oxygen demand and myocardial calcium levels which can cause new arrhythmias, particularly a problem during resuscitation Esmolol (or any beta blocker) can be used in VF refractory to defibrillation, epinephrine and amiodarone in a last-ditch effort. Esmolol in the setting of epinephrine can help prevent some of these known effects from repeated beta stimulation Dosing esmolol for refractory VF: 500mcg/kg bolus, followed by drip (max typically 1000 mcg/kg/min) Esmolol is associated with improved mortality in ACLS care in refractory VF References Long DA, Long B, April MD. Does β-Blockade for Treatment of Refractory Ventricular Fibrillation or Pulseless Ventricular Tachycardia Improve Outcomes?. Ann Emerg Med. 2020;76(1):42-45. doi:10.1016/j.annemergmed.2020.01.025 Lee YH, Lee KJ, Min YH, et al. Refractory ventricular fibrillation treated with esmolol. Resuscitation. 2016;107:150-155. doi:10.1016/j.resuscitation.2016.07.243  Summarized by Jackson Roos, MS4 | Edited by Erik Verzemnieks, MD