Abstract 18003: Intravenous Esmolol Before Defibrillation of Ischemic or Reperfusion Induced Ventricular Fibrillation Improves Post Resuscitation Hemodynamics
BACKGROUND and HYPOTHESIS: Myocardial interstitial catecholamine concentrations are greatly elevated after defibrillation of long duration ventricular fibrillation (VF). These high levels are cytotoxic and subsequent withdrawal of this surge can lead to hemodynamic instability. Beta adrenergic blockade with esmolol might protect against these harmful effects.
METHODS: In 24 anaesthetized pigs the left anterior descending artery was balloon occluded distal to the first diagonal branch. Pigs were then observed for 30 min before deflating the balloon. 10 pigs had VF during the 30 min of ischemia and 10 had VF during reperfusion. VF could not be induced in 4 animals. Following 5 min of VF pigs were randomly assigned to receive either intravenous esmolol (1mg/kg) or saline along with chest compressions delivered by a mechanical device. After 3 min of chest compression they were defibrillated using a step up protocol to determine the defibrillation threshold (DFT) and advanced cardiac life support including CPR and epinephrine was given in both groups. After return of spontaneous circulation pigs were observed for 30 min and if required their blood pressure was supported with epinephrine boluses to maintain SBP >50mm of Hg.
RESULTS Esmolol and saline groups were similar in terms of DFT (131±7.8 J vs. 141±29 J, p=0.72) and time to return of spontaneous circulation 2.58 ± 0.73 min vs. 2.93±1.04 min, p=0.78). The esmolol group showed a trend towards decrease number of refibrillation episodes (1.25±0.49 vs.2.3±0.55, p=0.17) and better survival (8/10 vs. 6/10, p=0.32). Significantly less epinephrine was required in the esmolol group (1.75±0.47 doses per animal vs. 3.6±0.33 doses per animal, p=0.009) to maintain blood pressure. The number of animals which required hemodynamic support post resuscitation was less in esmolol group (4/8 vs. 6/6, p=0.05).
CONCLUSIONS: Intravenous esmolol before defibrillation of ischemic or reperfusion-induced VF reduces the epinephrine requirement and improves post resuscitation hemodynamics.
- © 2012 by American Heart Association, Inc.